#include "httplib.h"
namespace httplib {

/*
 * Implementation that will be part of the .cc file if split into .h + .cc.
 */

namespace stream {

// stream::Result implementations
Result::Result() : chunk_size_(8192) {}

Result::Result(ClientImpl::StreamHandle &&handle, size_t chunk_size)
    : handle_(std::move(handle)), chunk_size_(chunk_size) {}

Result::Result(Result &&other) noexcept
    : handle_(std::move(other.handle_)), buffer_(std::move(other.buffer_)),
      current_size_(other.current_size_), chunk_size_(other.chunk_size_),
      finished_(other.finished_) {
  other.current_size_ = 0;
  other.finished_ = true;
}

Result &Result::operator=(Result &&other) noexcept {
  if (this != &other) {
    handle_ = std::move(other.handle_);
    buffer_ = std::move(other.buffer_);
    current_size_ = other.current_size_;
    chunk_size_ = other.chunk_size_;
    finished_ = other.finished_;
    other.current_size_ = 0;
    other.finished_ = true;
  }
  return *this;
}

bool Result::is_valid() const { return handle_.is_valid(); }
Result::operator bool() const { return is_valid(); }

int Result::status() const {
  return handle_.response ? handle_.response->status : -1;
}

const Headers &Result::headers() const {
  static const Headers empty_headers;
  return handle_.response ? handle_.response->headers : empty_headers;
}

std::string Result::get_header_value(const std::string &key,
                                            const char *def) const {
  return handle_.response ? handle_.response->get_header_value(key, def) : def;
}

bool Result::has_header(const std::string &key) const {
  return handle_.response ? handle_.response->has_header(key) : false;
}

Error Result::error() const { return handle_.error; }
Error Result::read_error() const { return handle_.get_read_error(); }
bool Result::has_read_error() const { return handle_.has_read_error(); }

bool Result::next() {
  if (!handle_.is_valid() || finished_) { return false; }

  if (buffer_.size() < chunk_size_) { buffer_.resize(chunk_size_); }

  ssize_t n = handle_.read(&buffer_[0], chunk_size_);
  if (n > 0) {
    current_size_ = static_cast<size_t>(n);
    return true;
  }

  current_size_ = 0;
  finished_ = true;
  return false;
}

const char *Result::data() const { return buffer_.data(); }
size_t Result::size() const { return current_size_; }

std::string Result::read_all() {
  std::string result;
  while (next()) {
    result.append(data(), size());
  }
  return result;
}

} // namespace stream

namespace sse {

// SSEMessage implementations
SSEMessage::SSEMessage() : event("message") {}

void SSEMessage::clear() {
  event = "message";
  data.clear();
  id.clear();
}

// SSEClient implementations
SSEClient::SSEClient(Client &client, const std::string &path)
    : client_(client), path_(path) {}

SSEClient::SSEClient(Client &client, const std::string &path,
                            const Headers &headers)
    : client_(client), path_(path), headers_(headers) {}

SSEClient::~SSEClient() { stop(); }

SSEClient &SSEClient::on_message(MessageHandler handler) {
  on_message_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_event(const std::string &type,
                                      MessageHandler handler) {
  event_handlers_[type] = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_open(OpenHandler handler) {
  on_open_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_error(ErrorHandler handler) {
  on_error_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::set_reconnect_interval(int ms) {
  reconnect_interval_ms_ = ms;
  return *this;
}

SSEClient &SSEClient::set_max_reconnect_attempts(int n) {
  max_reconnect_attempts_ = n;
  return *this;
}

SSEClient &SSEClient::set_headers(const Headers &headers) {
  std::lock_guard<std::mutex> lock(headers_mutex_);
  headers_ = headers;
  return *this;
}

bool SSEClient::is_connected() const { return connected_.load(); }

const std::string &SSEClient::last_event_id() const {
  return last_event_id_;
}

void SSEClient::start() {
  running_.store(true);
  run_event_loop();
}

void SSEClient::start_async() {
  running_.store(true);
  async_thread_ = std::thread([this]() { run_event_loop(); });
}

void SSEClient::stop() {
  running_.store(false);
  client_.stop(); // Cancel any pending operations
  if (async_thread_.joinable()) { async_thread_.join(); }
}

bool SSEClient::parse_sse_line(const std::string &line, SSEMessage &msg,
                                      int &retry_ms) {
  // Blank line signals end of event
  if (line.empty() || line == "\r") { return true; }

  // Lines starting with ':' are comments (ignored)
  if (!line.empty() && line[0] == ':') { return false; }

  // Find the colon separator
  auto colon_pos = line.find(':');
  if (colon_pos == std::string::npos) {
    // Line with no colon is treated as field name with empty value
    return false;
  }

  auto field = line.substr(0, colon_pos);
  std::string value;

  // Value starts after colon, skip optional single space
  if (colon_pos + 1 < line.size()) {
    auto value_start = colon_pos + 1;
    if (line[value_start] == ' ') { value_start++; }
    value = line.substr(value_start);
    // Remove trailing \r if present
    if (!value.empty() && value.back() == '\r') { value.pop_back(); }
  }

  // Handle known fields
  if (field == "event") {
    msg.event = value;
  } else if (field == "data") {
    // Multiple data lines are concatenated with newlines
    if (!msg.data.empty()) { msg.data += "\n"; }
    msg.data += value;
  } else if (field == "id") {
    // Empty id is valid (clears the last event ID)
    msg.id = value;
  } else if (field == "retry") {
    // Parse retry interval in milliseconds
    {
      int v = 0;
      auto res =
          detail::from_chars(value.data(), value.data() + value.size(), v);
      if (res.ec == std::errc{}) { retry_ms = v; }
    }
  }
  // Unknown fields are ignored per SSE spec

  return false;
}

void SSEClient::run_event_loop() {
  auto reconnect_count = 0;

  while (running_.load()) {
    // Build headers, including Last-Event-ID if we have one
    Headers request_headers;
    {
      std::lock_guard<std::mutex> lock(headers_mutex_);
      request_headers = headers_;
    }
    if (!last_event_id_.empty()) {
      request_headers.emplace("Last-Event-ID", last_event_id_);
    }

    // Open streaming connection
    auto result = stream::Get(client_, path_, request_headers);

    // Connection error handling
    if (!result) {
      connected_.store(false);
      if (on_error_) { on_error_(result.error()); }

      if (!should_reconnect(reconnect_count)) { break; }
      wait_for_reconnect();
      reconnect_count++;
      continue;
    }

    if (result.status() != StatusCode::OK_200) {
      connected_.store(false);
      if (on_error_) { on_error_(Error::Connection); }

      // For certain errors, don't reconnect.
      // Note: 401 is intentionally absent so that handlers can refresh
      // credentials via set_headers() and let the client reconnect.
      if (result.status() == StatusCode::NoContent_204 ||
          result.status() == StatusCode::NotFound_404 ||
          result.status() == StatusCode::Forbidden_403) {
        break;
      }

      if (!should_reconnect(reconnect_count)) { break; }
      wait_for_reconnect();
      reconnect_count++;
      continue;
    }

    // Connection successful
    connected_.store(true);
    reconnect_count = 0;
    if (on_open_) { on_open_(); }

    // Event receiving loop
    std::string buffer;
    SSEMessage current_msg;

    while (running_.load() && result.next()) {
      buffer.append(result.data(), result.size());

      // Process complete lines in the buffer
      size_t line_start = 0;
      size_t newline_pos;

      while ((newline_pos = buffer.find('\n', line_start)) !=
             std::string::npos) {
        auto line = buffer.substr(line_start, newline_pos - line_start);
        line_start = newline_pos + 1;

        // Parse the line and check if event is complete
        auto event_complete =
            parse_sse_line(line, current_msg, reconnect_interval_ms_);

        if (event_complete && !current_msg.data.empty()) {
          // Update last_event_id for reconnection
          if (!current_msg.id.empty()) { last_event_id_ = current_msg.id; }

          // Dispatch event to appropriate handler
          dispatch_event(current_msg);

          current_msg.clear();
        }
      }

      // Keep unprocessed data in buffer
      buffer.erase(0, line_start);
    }

    // Connection ended
    connected_.store(false);

    if (!running_.load()) { break; }

    // Check for read errors
    if (result.has_read_error()) {
      if (on_error_) { on_error_(result.read_error()); }
    }

    if (!should_reconnect(reconnect_count)) { break; }
    wait_for_reconnect();
    reconnect_count++;
  }

  connected_.store(false);
}

void SSEClient::dispatch_event(const SSEMessage &msg) {
  // Check for specific event type handler first
  auto it = event_handlers_.find(msg.event);
  if (it != event_handlers_.end()) {
    it->second(msg);
    return;
  }

  // Fall back to generic message handler
  if (on_message_) { on_message_(msg); }
}

bool SSEClient::should_reconnect(int count) const {
  if (!running_.load()) { return false; }
  if (max_reconnect_attempts_ == 0) { return true; } // unlimited
  return count < max_reconnect_attempts_;
}

void SSEClient::wait_for_reconnect() {
  // Use small increments to check running_ flag frequently
  auto waited = 0;
  while (running_.load() && waited < reconnect_interval_ms_) {
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    waited += 100;
  }
}

} // namespace sse

#ifdef CPPHTTPLIB_SSL_ENABLED
/*
 * TLS abstraction layer - internal function declarations
 * These are implementation details and not part of the public API.
 */
namespace tls {

// Client context
ctx_t create_client_context();
void free_context(ctx_t ctx);
bool set_min_version(ctx_t ctx, Version version);
bool load_ca_pem(ctx_t ctx, const char *pem, size_t len);
bool load_ca_file(ctx_t ctx, const char *file_path);
bool load_ca_dir(ctx_t ctx, const char *dir_path);
bool load_system_certs(ctx_t ctx);
bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                         const char *password);
bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                          const char *key_path, const char *password);

// Server context
ctx_t create_server_context();
bool set_server_cert_pem(ctx_t ctx, const char *cert, const char *key,
                         const char *password);
bool set_server_cert_file(ctx_t ctx, const char *cert_path,
                          const char *key_path, const char *password);
bool set_client_ca_file(ctx_t ctx, const char *ca_file, const char *ca_dir);
void set_verify_client(ctx_t ctx, bool require);

// Session management
session_t create_session(ctx_t ctx, socket_t sock);
void free_session(session_t session);
bool set_sni(session_t session, const char *hostname);
bool set_hostname(session_t session, const char *hostname);

// Handshake (non-blocking capable)
TlsError connect(session_t session);
TlsError accept(session_t session);

// Handshake with timeout (blocking until timeout)
bool connect_nonblocking(session_t session, socket_t sock, time_t timeout_sec,
                         time_t timeout_usec, TlsError *err);
bool accept_nonblocking(session_t session, socket_t sock, time_t timeout_sec,
                        time_t timeout_usec, TlsError *err);

// I/O (non-blocking capable)
ssize_t read(session_t session, void *buf, size_t len, TlsError &err);
ssize_t write(session_t session, const void *buf, size_t len, TlsError &err);
int pending(const_session_t session);
void shutdown(session_t session, bool graceful);

// Connection state
bool is_peer_closed(session_t session, socket_t sock);

// Certificate verification
cert_t get_peer_cert(const_session_t session);
void free_cert(cert_t cert);
bool verify_hostname(cert_t cert, const char *hostname);
uint64_t hostname_mismatch_code();
long get_verify_result(const_session_t session);

// Certificate introspection
std::string get_cert_subject_cn(cert_t cert);
std::string get_cert_issuer_name(cert_t cert);
bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans);
bool get_cert_validity(cert_t cert, time_t &not_before, time_t &not_after);
std::string get_cert_serial(cert_t cert);
bool get_cert_der(cert_t cert, std::vector<unsigned char> &der);
const char *get_sni(const_session_t session);

// CA store management
ca_store_t create_ca_store(const char *pem, size_t len);
void free_ca_store(ca_store_t store);
bool set_ca_store(ctx_t ctx, ca_store_t store);
size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs);
std::vector<std::string> get_ca_names(ctx_t ctx);

// Dynamic certificate update (for servers)
bool update_server_cert(ctx_t ctx, const char *cert_pem, const char *key_pem,
                        const char *password);
bool update_server_client_ca(ctx_t ctx, const char *ca_pem);

// Certificate verification callback
bool set_verify_callback(ctx_t ctx, VerifyCallback callback);
long get_verify_error(const_session_t session);
std::string verify_error_string(long error_code);

// TlsError information
uint64_t peek_error();
uint64_t get_error();
std::string error_string(uint64_t code);

} // namespace tls
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 1: detail namespace - Non-SSL utilities
 */

namespace detail {

bool set_socket_opt_impl(socket_t sock, int level, int optname,
                                const void *optval, socklen_t optlen) {
  return setsockopt(sock, level, optname,
#ifdef _WIN32
                    reinterpret_cast<const char *>(optval),
#else
                    optval,
#endif
                    optlen) == 0;
}

bool set_socket_opt_time(socket_t sock, int level, int optname,
                                time_t sec, time_t usec) {
#ifdef _WIN32
  auto timeout = static_cast<uint32_t>(sec * 1000 + usec / 1000);
#else
  timeval timeout;
  timeout.tv_sec = static_cast<long>(sec);
  timeout.tv_usec = static_cast<decltype(timeout.tv_usec)>(usec);
#endif
  return set_socket_opt_impl(sock, level, optname, &timeout, sizeof(timeout));
}

bool is_hex(char c, int &v) {
  if (is_ascii_digit(c)) {
    v = c - '0';
    return true;
  } else if ('A' <= c && c <= 'F') {
    v = c - 'A' + 10;
    return true;
  } else if ('a' <= c && c <= 'f') {
    v = c - 'a' + 10;
    return true;
  }
  return false;
}

bool from_hex_to_i(const std::string &s, size_t i, size_t cnt,
                          int &val) {
  if (i >= s.size()) { return false; }

  val = 0;
  for (; cnt; i++, cnt--) {
    if (!s[i]) { return false; }
    auto v = 0;
    if (is_hex(s[i], v)) {
      val = val * 16 + v;
    } else {
      return false;
    }
  }
  return true;
}

std::string from_i_to_hex(size_t n) {
  static const auto charset = "0123456789abcdef";
  std::string ret;
  do {
    ret = charset[n & 15] + ret;
    n >>= 4;
  } while (n > 0);
  return ret;
}

std::string compute_etag(const FileStat &fs) {
  if (!fs.is_file()) { return std::string(); }

  // If mtime cannot be determined (negative value indicates an error
  // or sentinel), do not generate an ETag. Returning a neutral / fixed
  // value like 0 could collide with a real file that legitimately has
  // mtime == 0 (epoch) and lead to misleading validators.
  auto mtime_raw = fs.mtime();
  if (mtime_raw < 0) { return std::string(); }

  auto mtime = static_cast<size_t>(mtime_raw);
  auto size = fs.size();

  return std::string("W/\"") + from_i_to_hex(mtime) + "-" +
         from_i_to_hex(size) + "\"";
}

// Format time_t as HTTP-date (RFC 9110 Section 5.6.7): "Sun, 06 Nov 1994
// 08:49:37 GMT" This implementation is defensive: it validates `mtime`, checks
// return values from `gmtime_r`/`gmtime_s`, and ensures `strftime` succeeds.
std::string file_mtime_to_http_date(time_t mtime) {
  if (mtime < 0) { return std::string(); }

  struct tm tm_buf;
#ifdef _WIN32
  if (gmtime_s(&tm_buf, &mtime) != 0) { return std::string(); }
#else
  if (gmtime_r(&mtime, &tm_buf) == nullptr) { return std::string(); }
#endif
  char buf[64];
  if (strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S GMT", &tm_buf) == 0) {
    return std::string();
  }

  return std::string(buf);
}

// Parse HTTP-date (RFC 9110 Section 5.6.7) to time_t. Returns -1 on failure.
time_t parse_http_date(const std::string &date_str) {
  struct tm tm_buf;

  // Create a classic locale object once for all parsing attempts
  const std::locale classic_locale = std::locale::classic();

  // Try to parse using std::get_time (C++11, cross-platform)
  auto try_parse = [&](const char *fmt) -> bool {
    std::istringstream ss(date_str);
    ss.imbue(classic_locale);

    memset(&tm_buf, 0, sizeof(tm_buf));
    ss >> std::get_time(&tm_buf, fmt);

    return !ss.fail();
  };

  // RFC 9110 preferred format (HTTP-date): "Sun, 06 Nov 1994 08:49:37 GMT"
  if (!try_parse("%a, %d %b %Y %H:%M:%S")) {
    // RFC 850 format: "Sunday, 06-Nov-94 08:49:37 GMT"
    if (!try_parse("%A, %d-%b-%y %H:%M:%S")) {
      // asctime format: "Sun Nov  6 08:49:37 1994"
      if (!try_parse("%a %b %d %H:%M:%S %Y")) {
        return static_cast<time_t>(-1);
      }
    }
  }

#ifdef _WIN32
  return _mkgmtime(&tm_buf);
#elif defined _AIX
  return mktime(&tm_buf);
#else
  return timegm(&tm_buf);
#endif
}

bool is_weak_etag(const std::string &s) {
  // Check if the string is a weak ETag (starts with 'W/"')
  return s.size() > 3 && s[0] == 'W' && s[1] == '/' && s[2] == '"';
}

bool is_strong_etag(const std::string &s) {
  // Check if the string is a strong ETag (starts and ends with '"', at least 2
  // chars)
  return s.size() >= 2 && s[0] == '"' && s.back() == '"';
}

size_t to_utf8(int code, char *buff) {
  if (code < 0x0080) {
    buff[0] = static_cast<char>(code & 0x7F);
    return 1;
  } else if (code < 0x0800) {
    buff[0] = static_cast<char>(0xC0 | ((code >> 6) & 0x1F));
    buff[1] = static_cast<char>(0x80 | (code & 0x3F));
    return 2;
  } else if (code < 0xD800) {
    buff[0] = static_cast<char>(0xE0 | ((code >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (code & 0x3F));
    return 3;
  } else if (code < 0xE000) { // D800 - DFFF is invalid...
    return 0;
  } else if (code < 0x10000) {
    buff[0] = static_cast<char>(0xE0 | ((code >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (code & 0x3F));
    return 3;
  } else if (code < 0x110000) {
    buff[0] = static_cast<char>(0xF0 | ((code >> 18) & 0x7));
    buff[1] = static_cast<char>(0x80 | ((code >> 12) & 0x3F));
    buff[2] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[3] = static_cast<char>(0x80 | (code & 0x3F));
    return 4;
  }

  // NOTREACHED
  return 0;
}

} // namespace detail

namespace ws {
namespace impl {

bool is_valid_utf8(const std::string &s) {
  size_t i = 0;
  auto n = s.size();
  while (i < n) {
    auto c = static_cast<unsigned char>(s[i]);
    size_t len;
    uint32_t cp;
    if (c < 0x80) {
      i++;
      continue;
    } else if ((c & 0xE0) == 0xC0) {
      len = 2;
      cp = c & 0x1F;
    } else if ((c & 0xF0) == 0xE0) {
      len = 3;
      cp = c & 0x0F;
    } else if ((c & 0xF8) == 0xF0) {
      len = 4;
      cp = c & 0x07;
    } else {
      return false;
    }
    if (i + len > n) { return false; }
    for (size_t j = 1; j < len; j++) {
      auto b = static_cast<unsigned char>(s[i + j]);
      if ((b & 0xC0) != 0x80) { return false; }
      cp = (cp << 6) | (b & 0x3F);
    }
    // Overlong encoding check
    if (len == 2 && cp < 0x80) { return false; }
    if (len == 3 && cp < 0x800) { return false; }
    if (len == 4 && cp < 0x10000) { return false; }
    // Surrogate halves (U+D800..U+DFFF) and beyond U+10FFFF are invalid
    if (cp >= 0xD800 && cp <= 0xDFFF) { return false; }
    if (cp > 0x10FFFF) { return false; }
    i += len;
  }
  return true;
}

} // namespace impl
} // namespace ws

namespace detail {

// NOTE: This code came up with the following stackoverflow post:
// https://stackoverflow.com/questions/180947/base64-decode-snippet-in-c
std::string base64_encode(const std::string &in) {
  static const auto lookup =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  std::string out;
  out.reserve(in.size());

  // Unsigned: the accumulator is never masked, so with a signed int the
  // `val << 8` below overflows once enough bytes are folded in (undefined
  // behaviour before C++20). Only the low bits are ever emitted, so the
  // wrap-around of an unsigned accumulator does not affect the output.
  uint32_t val = 0;
  auto valb = -6;

  for (auto c : in) {
    val = (val << 8) + static_cast<uint8_t>(c);
    valb += 8;
    while (valb >= 0) {
      out.push_back(lookup[(val >> valb) & 0x3F]);
      valb -= 6;
    }
  }

  if (valb > -6) { out.push_back(lookup[((val << 8) >> (valb + 8)) & 0x3F]); }

  while (out.size() % 4) {
    out.push_back('=');
  }

  return out;
}

std::string sha1(const std::string &input) {
  // RFC 3174 SHA-1 implementation
  auto left_rotate = [](uint32_t x, uint32_t n) -> uint32_t {
    return (x << n) | (x >> (32 - n));
  };

  uint32_t h0 = 0x67452301;
  uint32_t h1 = 0xEFCDAB89;
  uint32_t h2 = 0x98BADCFE;
  uint32_t h3 = 0x10325476;
  uint32_t h4 = 0xC3D2E1F0;

  // Pre-processing: adding padding bits
  std::string msg = input;
  uint64_t original_bit_len = static_cast<uint64_t>(msg.size()) * 8;
  msg.push_back(static_cast<char>(0x80u));
  while (msg.size() % 64 != 56) {
    msg.push_back(0);
  }

  // Append original length in bits as 64-bit big-endian
  for (int i = 56; i >= 0; i -= 8) {
    msg.push_back(static_cast<char>((original_bit_len >> i) & 0xFF));
  }

  // Process each 512-bit chunk
  for (size_t offset = 0; offset < msg.size(); offset += 64) {
    uint32_t w[80];

    for (size_t i = 0; i < 16; i++) {
      w[i] =
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4]))
           << 24) |
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4 + 1]))
           << 16) |
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4 + 2]))
           << 8) |
          (static_cast<uint32_t>(
              static_cast<uint8_t>(msg[offset + i * 4 + 3])));
    }

    for (int i = 16; i < 80; i++) {
      w[i] = left_rotate(w[i - 3] ^ w[i - 8] ^ w[i - 14] ^ w[i - 16], 1);
    }

    uint32_t a = h0, b = h1, c = h2, d = h3, e = h4;

    for (int i = 0; i < 80; i++) {
      uint32_t f, k;
      if (i < 20) {
        f = (b & c) | ((~b) & d);
        k = 0x5A827999;
      } else if (i < 40) {
        f = b ^ c ^ d;
        k = 0x6ED9EBA1;
      } else if (i < 60) {
        f = (b & c) | (b & d) | (c & d);
        k = 0x8F1BBCDC;
      } else {
        f = b ^ c ^ d;
        k = 0xCA62C1D6;
      }

      uint32_t temp = left_rotate(a, 5) + f + e + k + w[i];
      e = d;
      d = c;
      c = left_rotate(b, 30);
      b = a;
      a = temp;
    }

    h0 += a;
    h1 += b;
    h2 += c;
    h3 += d;
    h4 += e;
  }

  // Produce the final hash as a 20-byte binary string
  std::string hash(20, '\0');
  for (size_t i = 0; i < 4; i++) {
    hash[i] = static_cast<char>((h0 >> (24 - i * 8)) & 0xFF);
    hash[4 + i] = static_cast<char>((h1 >> (24 - i * 8)) & 0xFF);
    hash[8 + i] = static_cast<char>((h2 >> (24 - i * 8)) & 0xFF);
    hash[12 + i] = static_cast<char>((h3 >> (24 - i * 8)) & 0xFF);
    hash[16 + i] = static_cast<char>((h4 >> (24 - i * 8)) & 0xFF);
  }
  return hash;
}

std::string websocket_accept_key(const std::string &client_key) {
  const std::string magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  return base64_encode(sha1(client_key + magic));
}

bool is_websocket_upgrade(const Request &req) {
  if (req.method != "GET") { return false; }

  // Check Upgrade: websocket (case-insensitive)
  auto upgrade_it = req.headers.find("Upgrade");
  if (upgrade_it == req.headers.end()) { return false; }
  auto upgrade_val = case_ignore::to_lower(upgrade_it->second);
  if (upgrade_val != "websocket") { return false; }

  // Check Connection header contains "Upgrade"
  auto connection_it = req.headers.find("Connection");
  if (connection_it == req.headers.end()) { return false; }
  auto connection_val = case_ignore::to_lower(connection_it->second);
  if (connection_val.find("upgrade") == std::string::npos) { return false; }

  // Check Sec-WebSocket-Key is a valid base64-encoded 16-byte value (24 chars)
  // RFC 6455 Section 4.2.1
  auto ws_key = req.get_header_value("Sec-WebSocket-Key");
  if (ws_key.size() != 24 || ws_key[22] != '=' || ws_key[23] != '=') {
    return false;
  }
  static const std::string b64chars =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  for (size_t i = 0; i < 22; i++) {
    if (b64chars.find(ws_key[i]) == std::string::npos) { return false; }
  }

  // Check Sec-WebSocket-Version: 13
  auto version = req.get_header_value("Sec-WebSocket-Version");
  if (version != "13") { return false; }

  return true;
}

bool write_websocket_frame(Stream &strm, ws::Opcode opcode,
                                  const char *data, size_t len, bool fin,
                                  bool mask) {
  // First byte: FIN + opcode
  uint8_t header[2];
  header[0] = static_cast<uint8_t>((fin ? 0x80 : 0x00) |
                                   (static_cast<uint8_t>(opcode) & 0x0F));

  // Second byte: MASK + payload length
  if (len < 126) {
    header[1] = static_cast<uint8_t>(len);
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
  } else if (len <= 0xFFFF) {
    header[1] = 126;
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
    uint8_t ext[2];
    ext[0] = static_cast<uint8_t>((len >> 8) & 0xFF);
    ext[1] = static_cast<uint8_t>(len & 0xFF);
    if (strm.write(reinterpret_cast<char *>(ext), 2) < 0) { return false; }
  } else {
    header[1] = 127;
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
    uint8_t ext[8];
    for (int i = 7; i >= 0; i--) {
      ext[7 - i] =
          static_cast<uint8_t>((static_cast<uint64_t>(len) >> (i * 8)) & 0xFF);
    }
    if (strm.write(reinterpret_cast<char *>(ext), 8) < 0) { return false; }
  }

  if (mask) {
    // Generate random mask key
    thread_local std::mt19937 rng(std::random_device{}());
    uint8_t mask_key[4];
    auto r = rng();
    std::memcpy(mask_key, &r, 4);
    if (strm.write(reinterpret_cast<char *>(mask_key), 4) < 0) { return false; }

    // Write masked payload in chunks
    const size_t chunk_size = 4096;
    std::vector<char> buf((std::min)(len, chunk_size));
    for (size_t offset = 0; offset < len; offset += chunk_size) {
      size_t n = (std::min)(chunk_size, len - offset);
      for (size_t i = 0; i < n; i++) {
        buf[i] =
            data[offset + i] ^ static_cast<char>(mask_key[(offset + i) % 4]);
      }
      if (strm.write(buf.data(), n) < 0) { return false; }
    }
  } else {
    if (len > 0) {
      if (strm.write(data, len) < 0) { return false; }
    }
  }

  return true;
}

} // namespace detail

namespace ws {
namespace impl {

bool read_websocket_frame(Stream &strm, Opcode &opcode,
                                 std::string &payload, bool &fin,
                                 bool expect_masked, size_t max_len) {
  // Read first 2 bytes
  uint8_t header[2];
  if (strm.read(reinterpret_cast<char *>(header), 2) != 2) { return false; }

  fin = (header[0] & 0x80) != 0;

  // RSV1, RSV2, RSV3 must be 0 when no extension is negotiated
  if (header[0] & 0x70) { return false; }

  opcode = static_cast<Opcode>(header[0] & 0x0F);
  bool masked = (header[1] & 0x80) != 0;
  uint64_t payload_len = header[1] & 0x7F;

  // RFC 6455 Section 5.5: control frames MUST NOT be fragmented and
  // MUST have a payload length of 125 bytes or less
  bool is_control = (static_cast<uint8_t>(opcode) & 0x08) != 0;
  if (is_control) {
    if (!fin) { return false; }
    if (payload_len > 125) { return false; }
  }

  if (masked != expect_masked) { return false; }

  // Extended payload length
  if (payload_len == 126) {
    uint8_t ext[2];
    if (strm.read(reinterpret_cast<char *>(ext), 2) != 2) { return false; }
    payload_len = (static_cast<uint64_t>(ext[0]) << 8) | ext[1];
  } else if (payload_len == 127) {
    uint8_t ext[8];
    if (strm.read(reinterpret_cast<char *>(ext), 8) != 8) { return false; }
    // RFC 6455 Section 5.2: the most significant bit MUST be 0
    if (ext[0] & 0x80) { return false; }
    payload_len = 0;
    for (int i = 0; i < 8; i++) {
      payload_len = (payload_len << 8) | ext[i];
    }
  }

  if (payload_len > max_len) { return false; }

  // Read mask key if present
  uint8_t mask_key[4] = {0};
  if (masked) {
    if (strm.read(reinterpret_cast<char *>(mask_key), 4) != 4) { return false; }
  }

  // Read payload
  payload.resize(static_cast<size_t>(payload_len));
  if (payload_len > 0) {
    size_t total_read = 0;
    while (total_read < payload_len) {
      auto n = strm.read(&payload[total_read],
                         static_cast<size_t>(payload_len - total_read));
      if (n <= 0) { return false; }
      total_read += static_cast<size_t>(n);
    }
  }

  // Unmask if needed
  if (masked) {
    for (size_t i = 0; i < payload.size(); i++) {
      payload[i] ^= static_cast<char>(mask_key[i % 4]);
    }
  }

  return true;
}

} // namespace impl
} // namespace ws

namespace detail {

bool is_valid_path(const std::string &path) {
  size_t level = 0;
  size_t i = 0;

  // Skip slash
  while (i < path.size() && path[i] == '/') {
    i++;
  }

  while (i < path.size()) {
    // Read component
    auto beg = i;
    while (i < path.size() && path[i] != '/') {
      if (path[i] == '\0') {
        return false;
      } else if (path[i] == '\\') {
        return false;
      }
      i++;
    }

    auto len = i - beg;
    assert(len > 0);

    if (!path.compare(beg, len, ".")) {
      ;
    } else if (!path.compare(beg, len, "..")) {
      if (level == 0) { return false; }
      level--;
    } else {
      level++;
    }

    // Skip slash
    while (i < path.size() && path[i] == '/') {
      i++;
    }
  }

  return true;
}

bool canonicalize_path(const char *path, std::string &resolved) {
#if defined(_WIN32)
  char buf[_MAX_PATH];
  if (_fullpath(buf, path, _MAX_PATH) == nullptr) { return false; }
  resolved = buf;
#elif defined(PATH_MAX)
  char buf[PATH_MAX];
  if (realpath(path, buf) == nullptr) { return false; }
  resolved = buf;
#else
  auto buf = realpath(path, nullptr);
  auto guard = scope_exit([&]() { std::free(buf); });
  if (buf == nullptr) { return false; }
  resolved = buf;
#endif
  return true;
}

bool is_path_within_base(const std::string &resolved_path,
                                const std::string &resolved_base) {
#if defined(_WIN32)
  return _strnicmp(resolved_path.c_str(), resolved_base.c_str(),
                   resolved_base.size()) == 0;
#else
  return strncmp(resolved_path.c_str(), resolved_base.c_str(),
                 resolved_base.size()) == 0;
#endif
}

FileStat::FileStat(const std::string &path) {
#if defined(_WIN32)
  auto wpath = u8string_to_wstring(path.c_str());
  ret_ = _wstat(wpath.c_str(), &st_);
#else
  ret_ = stat(path.c_str(), &st_);
#endif
}
bool FileStat::is_file() const {
  return ret_ >= 0 && S_ISREG(st_.st_mode);
}
bool FileStat::is_dir() const {
  return ret_ >= 0 && S_ISDIR(st_.st_mode);
}

time_t FileStat::mtime() const {
  return ret_ >= 0 ? static_cast<time_t>(st_.st_mtime)
                   : static_cast<time_t>(-1);
}

size_t FileStat::size() const {
  return ret_ >= 0 ? static_cast<size_t>(st_.st_size) : 0;
}

std::string encode_path(const std::string &s) {
  std::string result;
  result.reserve(s.size());

  for (size_t i = 0; s[i]; i++) {
    switch (s[i]) {
    case ' ': result += "%20"; break;
    case '+': result += "%2B"; break;
    case '\r': result += "%0D"; break;
    case '\n': result += "%0A"; break;
    case '\'': result += "%27"; break;
    case ',': result += "%2C"; break;
    // case ':': result += "%3A"; break; // ok? probably...
    case ';': result += "%3B"; break;
    default:
      auto c = static_cast<uint8_t>(s[i]);
      if (c >= 0x80) {
        result += '%';
        char hex[4];
        auto len = snprintf(hex, sizeof(hex) - 1, "%02X", c);
        assert(len == 2);
        result.append(hex, static_cast<size_t>(len));
      } else {
        result += s[i];
      }
      break;
    }
  }

  return result;
}

std::string file_extension(const std::string &path) {
  std::smatch m;
  thread_local auto re = std::regex("\\.([a-zA-Z0-9]+)$");
  if (std::regex_search(path, m, re)) { return m[1].str(); }
  return std::string();
}

bool is_space_or_tab(char c) { return c == ' ' || c == '\t'; }

template <typename T>
bool parse_header(const char *beg, const char *end, T fn);

template <typename T>
bool parse_header(const char *beg, const char *end, T fn) {
  // Skip trailing spaces and tabs.
  while (beg < end && is_space_or_tab(end[-1])) {
    end--;
  }

  auto p = beg;
  while (p < end && *p != ':') {
    p++;
  }

  auto name = std::string(beg, p);
  if (!detail::fields::is_field_name(name)) { return false; }

  if (p == end) { return false; }

  auto key_end = p;

  if (*p++ != ':') { return false; }

  while (p < end && is_space_or_tab(*p)) {
    p++;
  }

  if (p <= end) {
    auto key_len = key_end - beg;
    if (!key_len) { return false; }

    auto key = std::string(beg, key_end);
    auto val = std::string(p, end);

    if (!detail::fields::is_field_value(val)) { return false; }

    // RFC 9110 §5.5: header field values are opaque octets and MUST NOT be
    // percent-decoded by the recipient. Applications that need to interpret a
    // value as a URI component should call httplib::decode_uri_component()
    // (or decode_path_component()) explicitly.
    fn(key, val);

    return true;
  }

  return false;
}

bool parse_trailers(stream_line_reader &line_reader, Headers &dest,
                           const Headers &src_headers) {
  // NOTE: In RFC 9112, '7.1 Chunked Transfer Coding' mentions "The chunked
  // transfer coding is complete when a chunk with a chunk-size of zero is
  // received, possibly followed by a trailer section, and finally terminated by
  // an empty line". https://www.rfc-editor.org/rfc/rfc9112.html#section-7.1
  //
  // In '7.1.3. Decoding Chunked', however, the pseudo-code in the section
  // doesn't care for the existence of the final CRLF. In other words, it seems
  // to be ok whether the final CRLF exists or not in the chunked data.
  // https://www.rfc-editor.org/rfc/rfc9112.html#section-7.1.3
  //
  // According to the reference code in RFC 9112, cpp-httplib now allows
  // chunked transfer coding data without the final CRLF.

  // RFC 7230 Section 4.1.2 - Headers prohibited in trailers
  thread_local case_ignore::unordered_set<std::string> prohibited_trailers = {
      "transfer-encoding",
      "content-length",
      "host",
      "authorization",
      "www-authenticate",
      "proxy-authenticate",
      "proxy-authorization",
      "cookie",
      "set-cookie",
      "cache-control",
      "expect",
      "max-forwards",
      "pragma",
      "range",
      "te",
      "age",
      "expires",
      "date",
      "location",
      "retry-after",
      "vary",
      "warning",
      "content-encoding",
      "content-type",
      "content-range",
      "trailer"};

  case_ignore::unordered_set<std::string> declared_trailers;
  auto trailer_header = get_header_value(src_headers, "Trailer", "", 0);
  if (trailer_header && std::strlen(trailer_header)) {
    auto len = std::strlen(trailer_header);
    split(trailer_header, trailer_header + len, ',',
          [&](const char *b, const char *e) {
            const char *kbeg = b;
            const char *kend = e;
            while (kbeg < kend && (*kbeg == ' ' || *kbeg == '\t')) {
              ++kbeg;
            }
            while (kend > kbeg && (kend[-1] == ' ' || kend[-1] == '\t')) {
              --kend;
            }
            std::string key(kbeg, static_cast<size_t>(kend - kbeg));
            if (!key.empty() &&
                prohibited_trailers.find(key) == prohibited_trailers.end()) {
              declared_trailers.insert(key);
            }
          });
  }

  size_t trailer_header_count = 0;
  while (strcmp(line_reader.ptr(), "\r\n") != 0) {
    if (line_reader.size() > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }
    if (trailer_header_count >= CPPHTTPLIB_HEADER_MAX_COUNT) { return false; }

    constexpr auto line_terminator_len = 2;
    auto line_beg = line_reader.ptr();
    auto line_end =
        line_reader.ptr() + line_reader.size() - line_terminator_len;

    if (!parse_header(line_beg, line_end,
                      [&](const std::string &key, const std::string &val) {
                        if (declared_trailers.find(key) !=
                            declared_trailers.end()) {
                          dest.emplace(key, val);
                          trailer_header_count++;
                        }
                      })) {
      return false;
    }

    if (!line_reader.getline()) { return false; }
  }

  return true;
}

std::pair<size_t, size_t> trim(const char *b, const char *e, size_t left,
                                      size_t right) {
  while (b + left < e && is_space_or_tab(b[left])) {
    left++;
  }
  while (right > 0 && is_space_or_tab(b[right - 1])) {
    right--;
  }
  return std::make_pair(left, right);
}

std::string trim_copy(const std::string &s) {
  auto r = trim(s.data(), s.data() + s.size(), 0, s.size());
  return s.substr(r.first, r.second - r.first);
}

std::string trim_double_quotes_copy(const std::string &s) {
  if (s.length() >= 2 && s.front() == '"' && s.back() == '"') {
    return s.substr(1, s.size() - 2);
  }
  return s;
}

void
divide(const char *data, std::size_t size, char d,
       std::function<void(const char *, std::size_t, const char *, std::size_t)>
           fn) {
  const auto it = std::find(data, data + size, d);
  const auto found = static_cast<std::size_t>(it != data + size);
  const auto lhs_data = data;
  const auto lhs_size = static_cast<std::size_t>(it - data);
  const auto rhs_data = it + found;
  const auto rhs_size = size - lhs_size - found;

  fn(lhs_data, lhs_size, rhs_data, rhs_size);
}

void
divide(const std::string &str, char d,
       std::function<void(const char *, std::size_t, const char *, std::size_t)>
           fn) {
  divide(str.data(), str.size(), d, std::move(fn));
}

void split(const char *b, const char *e, char d,
                  std::function<void(const char *, const char *)> fn) {
  return split(b, e, d, (std::numeric_limits<size_t>::max)(), std::move(fn));
}

void split(const char *b, const char *e, char d, size_t m,
                  std::function<void(const char *, const char *)> fn) {
  size_t i = 0;
  size_t beg = 0;
  size_t count = 1;

  while (e ? (b + i < e) : (b[i] != '\0')) {
    if (b[i] == d && count < m) {
      auto r = trim(b, e, beg, i);
      if (r.first < r.second) { fn(&b[r.first], &b[r.second]); }
      beg = i + 1;
      count++;
    }
    i++;
  }

  if (i) {
    auto r = trim(b, e, beg, i);
    if (r.first < r.second) { fn(&b[r.first], &b[r.second]); }
  }
}

bool split_find(const char *b, const char *e, char d, size_t m,
                       std::function<bool(const char *, const char *)> fn) {
  size_t i = 0;
  size_t beg = 0;
  size_t count = 1;

  while (e ? (b + i < e) : (b[i] != '\0')) {
    if (b[i] == d && count < m) {
      auto r = trim(b, e, beg, i);
      if (r.first < r.second) {
        auto found = fn(&b[r.first], &b[r.second]);
        if (found) { return true; }
      }
      beg = i + 1;
      count++;
    }
    i++;
  }

  if (i) {
    auto r = trim(b, e, beg, i);
    if (r.first < r.second) {
      auto found = fn(&b[r.first], &b[r.second]);
      if (found) { return true; }
    }
  }

  return false;
}

bool split_find(const char *b, const char *e, char d,
                       std::function<bool(const char *, const char *)> fn) {
  return split_find(b, e, d, (std::numeric_limits<size_t>::max)(),
                    std::move(fn));
}

stream_line_reader::stream_line_reader(Stream &strm, char *fixed_buffer,
                                              size_t fixed_buffer_size)
    : strm_(strm), fixed_buffer_(fixed_buffer),
      fixed_buffer_size_(fixed_buffer_size) {}

const char *stream_line_reader::ptr() const {
  if (growable_buffer_.empty()) {
    return fixed_buffer_;
  } else {
    return growable_buffer_.data();
  }
}

size_t stream_line_reader::size() const {
  if (growable_buffer_.empty()) {
    return fixed_buffer_used_size_;
  } else {
    return growable_buffer_.size();
  }
}

bool stream_line_reader::end_with_crlf() const {
  auto end = ptr() + size();
  return size() >= 2 && end[-2] == '\r' && end[-1] == '\n';
}

bool stream_line_reader::getline() {
  fixed_buffer_used_size_ = 0;
  growable_buffer_.clear();

#ifndef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
  char prev_byte = 0;
#endif

  for (size_t i = 0;; i++) {
    if (size() >= CPPHTTPLIB_MAX_LINE_LENGTH) {
      // Treat exceptionally long lines as an error to
      // prevent infinite loops/memory exhaustion
      return false;
    }
    char byte;
    auto n = strm_.read(&byte, 1);

    if (n < 0) {
      return false;
    } else if (n == 0) {
      if (i == 0) {
        return false;
      } else {
        break;
      }
    }

    append(byte);

#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
    if (byte == '\n') { break; }
#else
    if (prev_byte == '\r' && byte == '\n') { break; }
    prev_byte = byte;
#endif
  }

  return true;
}

void stream_line_reader::append(char c) {
  if (fixed_buffer_used_size_ < fixed_buffer_size_ - 1) {
    fixed_buffer_[fixed_buffer_used_size_++] = c;
    fixed_buffer_[fixed_buffer_used_size_] = '\0';
  } else {
    if (growable_buffer_.empty()) {
      assert(fixed_buffer_[fixed_buffer_used_size_] == '\0');
      growable_buffer_.assign(fixed_buffer_, fixed_buffer_used_size_);
    }
    growable_buffer_ += c;
  }
}

mmap::mmap(const char *path) { open(path); }

mmap::~mmap() { close(); }

bool mmap::open(const char *path) {
  close();

#if defined(_WIN32)
  auto wpath = u8string_to_wstring(path);
  if (wpath.empty()) { return false; }

  hFile_ =
      ::CreateFile2(wpath.c_str(), GENERIC_READ,
                    FILE_SHARE_READ | FILE_SHARE_WRITE, OPEN_EXISTING, NULL);

  if (hFile_ == INVALID_HANDLE_VALUE) { return false; }

  LARGE_INTEGER size{};
  if (!::GetFileSizeEx(hFile_, &size)) { return false; }
  // If the following line doesn't compile due to QuadPart, update Windows SDK.
  // See:
  // https://github.com/yhirose/cpp-httplib/issues/1903#issuecomment-2316520721
  if (static_cast<ULONGLONG>(size.QuadPart) >
      (std::numeric_limits<decltype(size_)>::max)()) {
    // `size_t` might be 32-bits, on 32-bits Windows.
    return false;
  }
  size_ = static_cast<size_t>(size.QuadPart);

  hMapping_ =
      ::CreateFileMappingFromApp(hFile_, NULL, PAGE_READONLY, size_, NULL);

  // Special treatment for an empty file...
  if (hMapping_ == NULL && size_ == 0) {
    close();
    is_open_empty_file = true;
    return true;
  }

  if (hMapping_ == NULL) {
    close();
    return false;
  }

  addr_ = ::MapViewOfFileFromApp(hMapping_, FILE_MAP_READ, 0, 0);

  if (addr_ == nullptr) {
    close();
    return false;
  }
#else
  fd_ = ::open(path, O_RDONLY);
  if (fd_ == -1) { return false; }

  struct stat sb;
  if (fstat(fd_, &sb) == -1) {
    close();
    return false;
  }
  size_ = static_cast<size_t>(sb.st_size);

  addr_ = ::mmap(NULL, size_, PROT_READ, MAP_PRIVATE, fd_, 0);

  // Special treatment for an empty file...
  if (addr_ == MAP_FAILED && size_ == 0) {
    close();
    is_open_empty_file = true;
    return false;
  }
#endif

  return true;
}

bool mmap::is_open() const {
  return is_open_empty_file ? true : addr_ != nullptr;
}

size_t mmap::size() const { return size_; }

const char *mmap::data() const {
  return is_open_empty_file ? "" : static_cast<const char *>(addr_);
}

void mmap::close() {
#if defined(_WIN32)
  if (addr_) {
    ::UnmapViewOfFile(addr_);
    addr_ = nullptr;
  }

  if (hMapping_) {
    ::CloseHandle(hMapping_);
    hMapping_ = NULL;
  }

  if (hFile_ != INVALID_HANDLE_VALUE) {
    ::CloseHandle(hFile_);
    hFile_ = INVALID_HANDLE_VALUE;
  }

  is_open_empty_file = false;
#else
  if (addr_ != nullptr) {
    munmap(addr_, size_);
    addr_ = nullptr;
  }

  if (fd_ != -1) {
    ::close(fd_);
    fd_ = -1;
  }
#endif
  size_ = 0;
}
int close_socket(socket_t sock) noexcept {
#ifdef _WIN32
  return closesocket(sock);
#else
  return close(sock);
#endif
}

template <typename T> ssize_t handle_EINTR(T fn) {
  ssize_t res = 0;
  while (true) {
    res = fn();
    if (res < 0 && errno == EINTR) {
      std::this_thread::sleep_for(std::chrono::microseconds{1});
      continue;
    }
    break;
  }
  return res;
}

ssize_t read_socket(socket_t sock, void *ptr, size_t size, int flags) {
  return handle_EINTR([&]() {
    return recv(sock,
#ifdef _WIN32
                static_cast<char *>(ptr), static_cast<int>(size),
#else
                ptr, size,
#endif
                flags);
  });
}

ssize_t send_socket(socket_t sock, const void *ptr, size_t size,
                           int flags) {
  return handle_EINTR([&]() {
    return send(sock,
#ifdef _WIN32
                static_cast<const char *>(ptr), static_cast<int>(size),
#else
                ptr, size,
#endif
                flags);
  });
}

int poll_wrapper(struct pollfd *fds, nfds_t nfds, int timeout) {
#ifdef _WIN32
  return ::WSAPoll(fds, nfds, timeout);
#else
  return ::poll(fds, nfds, timeout);
#endif
}

ssize_t select_impl(socket_t sock, short events, time_t sec,
                           time_t usec) {
  struct pollfd pfd;
  pfd.fd = sock;
  pfd.events = events;
  pfd.revents = 0;

  auto timeout = static_cast<int>(sec * 1000 + usec / 1000);

  return handle_EINTR([&]() { return poll_wrapper(&pfd, 1, timeout); });
}

ssize_t select_read(socket_t sock, time_t sec, time_t usec) {
  return select_impl(sock, POLLIN, sec, usec);
}

ssize_t select_write(socket_t sock, time_t sec, time_t usec) {
  return select_impl(sock, POLLOUT, sec, usec);
}

Error wait_until_socket_is_ready(socket_t sock, time_t sec,
                                        time_t usec) {
  struct pollfd pfd_read;
  pfd_read.fd = sock;
  pfd_read.events = POLLIN | POLLOUT;
  pfd_read.revents = 0;

  auto timeout = static_cast<int>(sec * 1000 + usec / 1000);

  auto poll_res =
      handle_EINTR([&]() { return poll_wrapper(&pfd_read, 1, timeout); });

  if (poll_res == 0) { return Error::ConnectionTimeout; }

  if (poll_res > 0 && pfd_read.revents & (POLLIN | POLLOUT)) {
    auto error = 0;
    socklen_t len = sizeof(error);
    auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                          reinterpret_cast<char *>(&error), &len);
    auto successful = res >= 0 && !error;
    return successful ? Error::Success : Error::Connection;
  }

  return Error::Connection;
}

bool is_socket_alive(socket_t sock) {
  const auto val = detail::select_read(sock, 0, 0);
  if (val == 0) {
    return true;
  } else if (val < 0 && errno == EBADF) {
    return false;
  }
  char buf[1];
  return detail::read_socket(sock, &buf[0], sizeof(buf), MSG_PEEK) > 0;
}

class SocketStream final : public Stream {
public:
  SocketStream(socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
               time_t write_timeout_sec, time_t write_timeout_usec,
               time_t max_timeout_msec = 0,
               std::chrono::time_point<std::chrono::steady_clock> start_time =
                   (std::chrono::steady_clock::time_point::min)());
  ~SocketStream() override;

  bool is_readable() const override;
  bool wait_readable() const override;
  bool wait_writable() const override;
  bool is_peer_alive() const override;
  ssize_t read(char *ptr, size_t size) override;
  ssize_t write(const char *ptr, size_t size) override;
  void get_remote_ip_and_port(std::string &ip, int &port) const override;
  void get_local_ip_and_port(std::string &ip, int &port) const override;
  socket_t socket() const override;
  time_t duration() const override;
  void set_read_timeout(time_t sec, time_t usec = 0) override;

private:
  socket_t sock_;
  time_t read_timeout_sec_;
  time_t read_timeout_usec_;
  time_t write_timeout_sec_;
  time_t write_timeout_usec_;
  time_t max_timeout_msec_;
  const std::chrono::time_point<std::chrono::steady_clock> start_time_;

  std::vector<char> read_buff_;
  size_t read_buff_off_ = 0;
  size_t read_buff_content_size_ = 0;

  static const size_t read_buff_size_ = 1024l * 4;
};

bool keep_alive(const std::atomic<socket_t> &svr_sock, socket_t sock,
                       time_t keep_alive_timeout_sec) {
  using namespace std::chrono;

  const auto interval_usec =
      CPPHTTPLIB_KEEPALIVE_TIMEOUT_CHECK_INTERVAL_USECOND;

  // Avoid expensive `steady_clock::now()` call for the first time
  if (select_read(sock, 0, interval_usec) > 0) { return true; }

  const auto start = steady_clock::now() - microseconds{interval_usec};
  const auto timeout = seconds{keep_alive_timeout_sec};

  while (true) {
    if (svr_sock == INVALID_SOCKET) {
      break; // Server socket is closed
    }

    auto val = select_read(sock, 0, interval_usec);
    if (val < 0) {
      break; // Ssocket error
    } else if (val == 0) {
      if (steady_clock::now() - start > timeout) {
        break; // Timeout
      }
    } else {
      return true; // Ready for read
    }
  }

  return false;
}

template <typename T>
bool
process_server_socket_core(const std::atomic<socket_t> &svr_sock, socket_t sock,
                           size_t keep_alive_max_count,
                           time_t keep_alive_timeout_sec, T callback) {
  assert(keep_alive_max_count > 0);
  auto ret = false;
  auto count = keep_alive_max_count;
  while (count > 0 && keep_alive(svr_sock, sock, keep_alive_timeout_sec)) {
    auto close_connection = count == 1;
    auto connection_closed = false;
    ret = callback(close_connection, connection_closed);
    if (!ret || connection_closed) { break; }
    count--;
  }
  return ret;
}

template <typename T>
bool
process_server_socket(const std::atomic<socket_t> &svr_sock, socket_t sock,
                      size_t keep_alive_max_count,
                      time_t keep_alive_timeout_sec, time_t read_timeout_sec,
                      time_t read_timeout_usec, time_t write_timeout_sec,
                      time_t write_timeout_usec, T callback) {
  return process_server_socket_core(
      svr_sock, sock, keep_alive_max_count, keep_alive_timeout_sec,
      [&](bool close_connection, bool &connection_closed) {
        SocketStream strm(sock, read_timeout_sec, read_timeout_usec,
                          write_timeout_sec, write_timeout_usec);
        return callback(strm, close_connection, connection_closed);
      });
}

bool process_client_socket(
    socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
    time_t write_timeout_sec, time_t write_timeout_usec,
    time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &)> callback) {
  SocketStream strm(sock, read_timeout_sec, read_timeout_usec,
                    write_timeout_sec, write_timeout_usec, max_timeout_msec,
                    start_time);
  return callback(strm);
}

int shutdown_socket(socket_t sock) noexcept {
#ifdef _WIN32
  return shutdown(sock, SD_BOTH);
#else
  return shutdown(sock, SHUT_RDWR);
#endif
}

std::string escape_abstract_namespace_unix_domain(const std::string &s) {
  if (s.size() > 1 && s[0] == '\0') {
    auto ret = s;
    ret[0] = '@';
    return ret;
  }
  return s;
}

std::string
unescape_abstract_namespace_unix_domain(const std::string &s) {
  if (s.size() > 1 && s[0] == '@') {
    auto ret = s;
    ret[0] = '\0';
    return ret;
  }
  return s;
}

int getaddrinfo_with_timeout(const char *node, const char *service,
                                    const struct addrinfo *hints,
                                    struct addrinfo **res, time_t timeout_sec) {
#ifdef CPPHTTPLIB_USE_NON_BLOCKING_GETADDRINFO
  if (timeout_sec <= 0) {
    // No timeout specified, use standard getaddrinfo
    return getaddrinfo(node, service, hints, res);
  }

#ifdef _WIN32
  // Windows-specific implementation using GetAddrInfoEx with overlapped I/O
  OVERLAPPED overlapped = {};
  HANDLE event = CreateEventW(nullptr, TRUE, FALSE, nullptr);
  if (!event) { return EAI_FAIL; }

  overlapped.hEvent = event;

  PADDRINFOEXW result_addrinfo = nullptr;
  HANDLE cancel_handle = nullptr;

  ADDRINFOEXW hints_ex = {};
  if (hints) {
    hints_ex.ai_flags = hints->ai_flags;
    hints_ex.ai_family = hints->ai_family;
    hints_ex.ai_socktype = hints->ai_socktype;
    hints_ex.ai_protocol = hints->ai_protocol;
  }

  auto wnode = u8string_to_wstring(node);
  auto wservice = u8string_to_wstring(service);

  auto ret = ::GetAddrInfoExW(wnode.data(), wservice.data(), NS_DNS, nullptr,
                              hints ? &hints_ex : nullptr, &result_addrinfo,
                              nullptr, &overlapped, nullptr, &cancel_handle);

  if (ret == WSA_IO_PENDING) {
    auto wait_result =
        ::WaitForSingleObject(event, static_cast<DWORD>(timeout_sec * 1000));
    if (wait_result == WAIT_TIMEOUT) {
      if (cancel_handle) { ::GetAddrInfoExCancel(&cancel_handle); }
      ::CloseHandle(event);
      return EAI_AGAIN;
    }

    DWORD bytes_returned;
    if (!::GetOverlappedResult((HANDLE)INVALID_SOCKET, &overlapped,
                               &bytes_returned, FALSE)) {
      ::CloseHandle(event);
      return ::WSAGetLastError();
    }
  }

  ::CloseHandle(event);

  if (ret == NO_ERROR || ret == WSA_IO_PENDING) {
    *res = reinterpret_cast<struct addrinfo *>(result_addrinfo);
    return 0;
  }

  return ret;
#elif TARGET_OS_MAC && defined(__clang__)
  if (!node) { return EAI_NONAME; }
  // macOS implementation using CFHost API for asynchronous DNS resolution
  CFStringRef hostname_ref = CFStringCreateWithCString(
      kCFAllocatorDefault, node, kCFStringEncodingUTF8);
  if (!hostname_ref) { return EAI_MEMORY; }

  CFHostRef host_ref = CFHostCreateWithName(kCFAllocatorDefault, hostname_ref);
  CFRelease(hostname_ref);
  if (!host_ref) { return EAI_MEMORY; }

  // Set up context for callback
  struct CFHostContext {
    bool completed = false;
    bool success = false;
    CFArrayRef addresses = nullptr;
    std::mutex mutex;
    std::condition_variable cv;
  } context;

  CFHostClientContext client_context;
  memset(&client_context, 0, sizeof(client_context));
  client_context.info = &context;

  // Set callback
  auto callback = [](CFHostRef theHost, CFHostInfoType /*typeInfo*/,
                     const CFStreamError *error, void *info) {
    auto ctx = static_cast<CFHostContext *>(info);
    std::lock_guard<std::mutex> lock(ctx->mutex);

    if (error && error->error != 0) {
      ctx->success = false;
    } else {
      Boolean hasBeenResolved;
      ctx->addresses = CFHostGetAddressing(theHost, &hasBeenResolved);
      if (ctx->addresses && hasBeenResolved) {
        CFRetain(ctx->addresses);
        ctx->success = true;
      } else {
        ctx->success = false;
      }
    }
    ctx->completed = true;
    ctx->cv.notify_one();
  };

  if (!CFHostSetClient(host_ref, callback, &client_context)) {
    CFRelease(host_ref);
    return EAI_SYSTEM;
  }

  // Schedule on run loop
  CFRunLoopRef run_loop = CFRunLoopGetCurrent();
  CFHostScheduleWithRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);

  // Start resolution
  CFStreamError stream_error;
  if (!CFHostStartInfoResolution(host_ref, kCFHostAddresses, &stream_error)) {
    CFHostUnscheduleFromRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);
    CFRelease(host_ref);
    return EAI_FAIL;
  }

  // Wait for completion with timeout
  auto timeout_time =
      std::chrono::steady_clock::now() + std::chrono::seconds(timeout_sec);
  bool timed_out = false;

  {
    std::unique_lock<std::mutex> lock(context.mutex);

    while (!context.completed) {
      auto now = std::chrono::steady_clock::now();
      if (now >= timeout_time) {
        timed_out = true;
        break;
      }

      // Run the runloop for a short time
      lock.unlock();
      CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, true);
      lock.lock();
    }
  }

  // Clean up
  CFHostUnscheduleFromRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);
  CFHostSetClient(host_ref, nullptr, nullptr);

  if (timed_out || !context.completed) {
    CFHostCancelInfoResolution(host_ref, kCFHostAddresses);
    CFRelease(host_ref);
    return EAI_AGAIN;
  }

  if (!context.success || !context.addresses) {
    CFRelease(host_ref);
    return EAI_NODATA;
  }

  // Convert CFArray to addrinfo
  CFIndex count = CFArrayGetCount(context.addresses);
  if (count == 0) {
    CFRelease(context.addresses);
    CFRelease(host_ref);
    return EAI_NODATA;
  }

  struct addrinfo *result_addrinfo = nullptr;
  struct addrinfo **current = &result_addrinfo;

  for (CFIndex i = 0; i < count; i++) {
    CFDataRef addr_data =
        static_cast<CFDataRef>(CFArrayGetValueAtIndex(context.addresses, i));
    if (!addr_data) continue;

    const struct sockaddr *sockaddr_ptr =
        reinterpret_cast<const struct sockaddr *>(CFDataGetBytePtr(addr_data));
    socklen_t sockaddr_len = static_cast<socklen_t>(CFDataGetLength(addr_data));

    // Allocate addrinfo structure
    *current = static_cast<struct addrinfo *>(malloc(sizeof(struct addrinfo)));
    if (!*current) {
      freeaddrinfo(result_addrinfo);
      CFRelease(context.addresses);
      CFRelease(host_ref);
      return EAI_MEMORY;
    }

    memset(*current, 0, sizeof(struct addrinfo));

    // Set up addrinfo fields
    (*current)->ai_family = sockaddr_ptr->sa_family;
    (*current)->ai_socktype = hints ? hints->ai_socktype : SOCK_STREAM;
    (*current)->ai_protocol = hints ? hints->ai_protocol : IPPROTO_TCP;
    (*current)->ai_addrlen = sockaddr_len;

    // Copy sockaddr
    (*current)->ai_addr = static_cast<struct sockaddr *>(malloc(sockaddr_len));
    if (!(*current)->ai_addr) {
      freeaddrinfo(result_addrinfo);
      CFRelease(context.addresses);
      CFRelease(host_ref);
      return EAI_MEMORY;
    }
    memcpy((*current)->ai_addr, sockaddr_ptr, sockaddr_len);

    // Set port if service is specified
    if (service && *service) {
      int port = 0;
      if (parse_port(service, strlen(service), port)) {
        if (sockaddr_ptr->sa_family == AF_INET) {
          reinterpret_cast<struct sockaddr_in *>((*current)->ai_addr)
              ->sin_port = htons(static_cast<uint16_t>(port));
        } else if (sockaddr_ptr->sa_family == AF_INET6) {
          reinterpret_cast<struct sockaddr_in6 *>((*current)->ai_addr)
              ->sin6_port = htons(static_cast<uint16_t>(port));
        }
      }
    }

    current = &((*current)->ai_next);
  }

  CFRelease(context.addresses);
  CFRelease(host_ref);

  *res = result_addrinfo;
  return 0;
#elif defined(_GNU_SOURCE) && defined(__GLIBC__) &&                            \
    (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2))
  // #2431: gai_cancel() is non-blocking and may return EAI_NOTCANCELED while
  // the resolver worker still references the stack-local gaicb. The cancel
  // path therefore waits (gai_suspend with no timeout) for the worker to
  // actually finish before letting the stack frame go. The trade-off is that
  // a wedged DNS server can hold this thread for the system resolver timeout
  // (~30s by default) past the caller's connection timeout.
  struct gaicb request {};
  struct gaicb *requests[1] = {&request};
  struct sigevent sevp {};
  struct timespec timeout {
    timeout_sec, 0
  };

  request.ar_name = node;
  request.ar_service = service;
  request.ar_request = hints;
  sevp.sigev_notify = SIGEV_NONE;

  int rc = getaddrinfo_a(GAI_NOWAIT, requests, 1, &sevp);
  if (rc != 0) { return rc; }

  auto cleanup = scope_exit([&] {
    if (request.ar_result) { freeaddrinfo(request.ar_result); }
  });

  int wait_result = gai_suspend(requests, 1, &timeout);

  if (wait_result == 0 || wait_result == EAI_ALLDONE) {
    int gai_result = gai_error(&request);
    if (gai_result == 0) {
      *res = request.ar_result;
      request.ar_result = nullptr;
      return 0;
    }
    return gai_result;
  }

  gai_cancel(&request);
  while (gai_error(&request) == EAI_INPROGRESS) {
    gai_suspend(requests, 1, nullptr);
  }
  return wait_result;
#else
  // Fallback implementation using thread-based timeout for other Unix systems.

  struct GetAddrInfoState {
    ~GetAddrInfoState() {
      if (info) { freeaddrinfo(info); }
    }

    std::mutex mutex;
    std::condition_variable result_cv;
    bool completed = false;
    int result = EAI_SYSTEM;
    std::string node;
    std::string service;
    struct addrinfo hints;
    struct addrinfo *info = nullptr;
  };

  // Allocate on the heap, so the resolver thread can keep using the data.
  auto state = std::make_shared<GetAddrInfoState>();
  if (node) { state->node = node; }
  state->service = service;
  state->hints = *hints;

  std::thread resolve_thread([state]() {
    auto thread_result =
        getaddrinfo(state->node.c_str(), state->service.c_str(), &state->hints,
                    &state->info);

    std::lock_guard<std::mutex> lock(state->mutex);
    state->result = thread_result;
    state->completed = true;
    state->result_cv.notify_one();
  });

  // Wait for completion or timeout
  std::unique_lock<std::mutex> lock(state->mutex);
  auto finished =
      state->result_cv.wait_for(lock, std::chrono::seconds(timeout_sec),
                                [&] { return state->completed; });

  if (finished) {
    // Operation completed within timeout
    resolve_thread.join();
    *res = state->info;
    state->info = nullptr; // Pass ownership to caller
    return state->result;
  } else {
    // Timeout occurred
    resolve_thread.detach(); // Let the thread finish in background
    return EAI_AGAIN;        // Return timeout error
  }
#endif
#else
  (void)(timeout_sec); // Unused parameter for non-blocking getaddrinfo
  return getaddrinfo(node, service, hints, res);
#endif
}

template <typename BindOrConnect>
socket_t create_socket(const std::string &host, const std::string &ip, int port,
                       int address_family, int socket_flags, bool tcp_nodelay,
                       bool ipv6_v6only, SocketOptions socket_options,
                       BindOrConnect bind_or_connect, time_t timeout_sec = 0) {
  // Get address info
  const char *node = nullptr;
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = IPPROTO_IP;

  if (!ip.empty()) {
    node = ip.c_str();
    // Ask getaddrinfo to convert IP in c-string to address
    hints.ai_family = AF_UNSPEC;
    hints.ai_flags = AI_NUMERICHOST;
  } else {
    if (!host.empty()) { node = host.c_str(); }
    hints.ai_family = address_family;
    hints.ai_flags = socket_flags;
  }

#if !defined(_WIN32) || defined(CPPHTTPLIB_HAVE_AFUNIX_H)
  if (hints.ai_family == AF_UNIX) {
    const auto addrlen = host.length();
    if (addrlen > sizeof(sockaddr_un::sun_path)) { return INVALID_SOCKET; }

#ifdef SOCK_CLOEXEC
    auto sock = socket(hints.ai_family, hints.ai_socktype | SOCK_CLOEXEC,
                       hints.ai_protocol);
#else
    auto sock = socket(hints.ai_family, hints.ai_socktype, hints.ai_protocol);
#endif

    if (sock != INVALID_SOCKET) {
      sockaddr_un addr{};
      addr.sun_family = AF_UNIX;

      auto unescaped_host = unescape_abstract_namespace_unix_domain(host);
      std::copy(unescaped_host.begin(), unescaped_host.end(), addr.sun_path);

      hints.ai_addr = reinterpret_cast<sockaddr *>(&addr);
      hints.ai_addrlen = static_cast<socklen_t>(
          sizeof(addr) - sizeof(addr.sun_path) + addrlen);

#ifndef SOCK_CLOEXEC
#ifndef _WIN32
      fcntl(sock, F_SETFD, FD_CLOEXEC);
#endif
#endif

      if (socket_options) { socket_options(sock); }

#ifdef _WIN32
      // Setting SO_REUSEADDR seems not to work well with AF_UNIX on windows, so
      // remove the option.
      set_socket_opt(sock, SOL_SOCKET, SO_REUSEADDR, 0);
#endif

      bool dummy;
      if (!bind_or_connect(sock, hints, dummy)) {
        close_socket(sock);
        sock = INVALID_SOCKET;
      }
    }
    return sock;
  }
#endif

  auto service = std::to_string(port);

  if (getaddrinfo_with_timeout(node, service.c_str(), &hints, &result,
                               timeout_sec)) {
#if defined __linux__ && !defined __ANDROID__
    res_init();
#endif
    return INVALID_SOCKET;
  }
  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  for (auto rp = result; rp; rp = rp->ai_next) {
    // Create a socket
#ifdef _WIN32
    auto sock =
        WSASocketW(rp->ai_family, rp->ai_socktype, rp->ai_protocol, nullptr, 0,
                   WSA_FLAG_NO_HANDLE_INHERIT | WSA_FLAG_OVERLAPPED);
    /**
     * Since the WSA_FLAG_NO_HANDLE_INHERIT is only supported on Windows 7 SP1
     * and above the socket creation fails on older Windows Systems.
     *
     * Let's try to create a socket the old way in this case.
     *
     * Reference:
     * https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-wsasocketa
     *
     * WSA_FLAG_NO_HANDLE_INHERIT:
     * This flag is supported on Windows 7 with SP1, Windows Server 2008 R2 with
     * SP1, and later
     *
     */
    if (sock == INVALID_SOCKET) {
      sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
    }
#else

#ifdef SOCK_CLOEXEC
    auto sock =
        socket(rp->ai_family, rp->ai_socktype | SOCK_CLOEXEC, rp->ai_protocol);
#else
    auto sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
#endif

#endif
    if (sock == INVALID_SOCKET) { continue; }

#if !defined _WIN32 && !defined SOCK_CLOEXEC
    if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1) {
      close_socket(sock);
      continue;
    }
#endif

    if (tcp_nodelay) { set_socket_opt(sock, IPPROTO_TCP, TCP_NODELAY, 1); }

    if (rp->ai_family == AF_INET6) {
      set_socket_opt(sock, IPPROTO_IPV6, IPV6_V6ONLY, ipv6_v6only ? 1 : 0);
    }

    if (socket_options) { socket_options(sock); }

    // bind or connect
    auto quit = false;
    if (bind_or_connect(sock, *rp, quit)) { return sock; }

    close_socket(sock);

    if (quit) { break; }
  }

  return INVALID_SOCKET;
}

void set_nonblocking(socket_t sock, bool nonblocking) {
#ifdef _WIN32
  auto flags = nonblocking ? 1UL : 0UL;
  ioctlsocket(sock, FIONBIO, &flags);
#else
  auto flags = fcntl(sock, F_GETFL, 0);
  fcntl(sock, F_SETFL,
        nonblocking ? (flags | O_NONBLOCK) : (flags & (~O_NONBLOCK)));
#endif
}

bool is_connection_error() {
#ifdef _WIN32
  return WSAGetLastError() != WSAEWOULDBLOCK;
#else
  return errno != EINPROGRESS;
#endif
}

bool bind_ip_address(socket_t sock, const std::string &host) {
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_family = AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;

  if (getaddrinfo_with_timeout(host.c_str(), "0", &hints, &result, 0)) {
    return false;
  }

  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  auto ret = false;
  for (auto rp = result; rp; rp = rp->ai_next) {
    const auto &ai = *rp;
    if (!::bind(sock, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen))) {
      ret = true;
      break;
    }
  }

  return ret;
}

#if !defined _WIN32 && !defined ANDROID && !defined _AIX && !defined __MVS__
#define USE_IF2IP
#endif

#ifdef USE_IF2IP
std::string if2ip(int address_family, const std::string &ifn) {
  struct ifaddrs *ifap;
  getifaddrs(&ifap);
  auto se = detail::scope_exit([&] { freeifaddrs(ifap); });

  std::string addr_candidate;
  for (auto ifa = ifap; ifa; ifa = ifa->ifa_next) {
    if (ifa->ifa_addr && ifn == ifa->ifa_name &&
        (AF_UNSPEC == address_family ||
         ifa->ifa_addr->sa_family == address_family)) {
      if (ifa->ifa_addr->sa_family == AF_INET) {
        auto sa = reinterpret_cast<struct sockaddr_in *>(ifa->ifa_addr);
        char buf[INET_ADDRSTRLEN];
        if (inet_ntop(AF_INET, &sa->sin_addr, buf, INET_ADDRSTRLEN)) {
          return std::string(buf, INET_ADDRSTRLEN);
        }
      } else if (ifa->ifa_addr->sa_family == AF_INET6) {
        auto sa = reinterpret_cast<struct sockaddr_in6 *>(ifa->ifa_addr);
        if (!IN6_IS_ADDR_LINKLOCAL(&sa->sin6_addr)) {
          char buf[INET6_ADDRSTRLEN] = {};
          if (inet_ntop(AF_INET6, &sa->sin6_addr, buf, INET6_ADDRSTRLEN)) {
            // equivalent to mac's IN6_IS_ADDR_UNIQUE_LOCAL
            auto s6_addr_head = sa->sin6_addr.s6_addr[0];
            if (s6_addr_head == 0xfc || s6_addr_head == 0xfd) {
              addr_candidate = std::string(buf, INET6_ADDRSTRLEN);
            } else {
              return std::string(buf, INET6_ADDRSTRLEN);
            }
          }
        }
      }
    }
  }
  return addr_candidate;
}
#endif

socket_t create_client_socket(
    const std::string &host, const std::string &ip, int port,
    int address_family, bool tcp_nodelay, bool ipv6_v6only,
    SocketOptions socket_options, time_t connection_timeout_sec,
    time_t connection_timeout_usec, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, const std::string &intf, Error &error) {
  auto sock = create_socket(
      host, ip, port, address_family, 0, tcp_nodelay, ipv6_v6only,
      std::move(socket_options),
      [&](socket_t sock2, struct addrinfo &ai, bool &quit) -> bool {
        if (!intf.empty()) {
#ifdef USE_IF2IP
          auto ip_from_if = if2ip(address_family, intf);
          if (ip_from_if.empty()) { ip_from_if = intf; }
          if (!bind_ip_address(sock2, ip_from_if)) {
            error = Error::BindIPAddress;
            return false;
          }
#endif
        }

        set_nonblocking(sock2, true);

        auto ret =
            ::connect(sock2, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen));

        if (ret < 0) {
          if (is_connection_error()) {
            error = Error::Connection;
            return false;
          }
          error = wait_until_socket_is_ready(sock2, connection_timeout_sec,
                                             connection_timeout_usec);
          if (error != Error::Success) {
            if (error == Error::ConnectionTimeout) { quit = true; }
            return false;
          }
        }

        set_nonblocking(sock2, false);
        set_socket_opt_time(sock2, SOL_SOCKET, SO_RCVTIMEO, read_timeout_sec,
                            read_timeout_usec);
        set_socket_opt_time(sock2, SOL_SOCKET, SO_SNDTIMEO, write_timeout_sec,
                            write_timeout_usec);

        error = Error::Success;
        return true;
      },
      connection_timeout_sec); // Pass DNS timeout

  if (sock != INVALID_SOCKET) {
    error = Error::Success;
  } else {
    if (error == Error::Success) { error = Error::Connection; }
  }

  return sock;
}

bool get_ip_and_port(const struct sockaddr_storage &addr,
                            socklen_t addr_len, std::string &ip, int &port) {
  if (addr.ss_family == AF_INET) {
    port = ntohs(reinterpret_cast<const struct sockaddr_in *>(&addr)->sin_port);
  } else if (addr.ss_family == AF_INET6) {
    port =
        ntohs(reinterpret_cast<const struct sockaddr_in6 *>(&addr)->sin6_port);
  } else {
    return false;
  }

  std::array<char, NI_MAXHOST> ipstr{};
  if (getnameinfo(reinterpret_cast<const struct sockaddr *>(&addr), addr_len,
                  ipstr.data(), static_cast<socklen_t>(ipstr.size()), nullptr,
                  0, NI_NUMERICHOST)) {
    return false;
  }

  ip = ipstr.data();
  return true;
}

void get_local_ip_and_port(socket_t sock, std::string &ip, int &port) {
  struct sockaddr_storage addr;
  socklen_t addr_len = sizeof(addr);
  if (!getsockname(sock, reinterpret_cast<struct sockaddr *>(&addr),
                   &addr_len)) {
    get_ip_and_port(addr, addr_len, ip, port);
  }
}

void get_remote_ip_and_port(socket_t sock, std::string &ip, int &port) {
  struct sockaddr_storage addr;
  socklen_t addr_len = sizeof(addr);

  if (!getpeername(sock, reinterpret_cast<struct sockaddr *>(&addr),
                   &addr_len)) {
#ifndef _WIN32
    if (addr.ss_family == AF_UNIX) {
#if defined(__linux__)
      struct ucred ucred;
      socklen_t len = sizeof(ucred);
      if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &ucred, &len) == 0) {
        port = ucred.pid;
      }
#elif defined(SOL_LOCAL) && defined(SO_PEERPID)
      pid_t pid;
      socklen_t len = sizeof(pid);
      if (getsockopt(sock, SOL_LOCAL, SO_PEERPID, &pid, &len) == 0) {
        port = pid;
      }
#endif
      return;
    }
#endif
    get_ip_and_port(addr, addr_len, ip, port);
  }
}

// Recursive form retained so operator""_t below can compute hashes for
// switch-case labels at compile time (C++11 constexpr forbids loops). Do not
// call from runtime paths with arbitrary-length inputs — use str2tag()
// instead, which is iterative and stack-safe.
constexpr unsigned int str2tag_core(const char *s, size_t l,
                                           unsigned int h) {
  return (l == 0)
             ? h
             : str2tag_core(
                   s + 1, l - 1,
                   // Unsets the 6 high bits of h, therefore no overflow happens
                   (((std::numeric_limits<unsigned int>::max)() >> 6) &
                    h * 33) ^
                       static_cast<unsigned char>(*s));
}

unsigned int str2tag(const std::string &s) {
  // Iterative form of str2tag_core: the recursive constexpr version is kept
  // for compile-time UDL evaluation of short string literals, but at runtime
  // we may receive arbitrarily long inputs (e.g. fuzzed Content-Type) that
  // would blow the stack with one frame per character.
  unsigned int h = 0;
  for (auto c : s) {
    h = (((std::numeric_limits<unsigned int>::max)() >> 6) & h * 33) ^
        static_cast<unsigned char>(c);
  }
  return h;
}

namespace udl {

constexpr unsigned int operator""_t(const char *s, size_t l) {
  return str2tag_core(s, l, 0);
}

} // namespace udl

std::string
find_content_type(const std::string &path,
                  const std::map<std::string, std::string> &user_data,
                  const std::string &default_content_type) {
  auto ext = file_extension(path);

  auto it = user_data.find(ext);
  if (it != user_data.end()) { return it->second; }

  using udl::operator""_t;

  switch (str2tag(ext)) {
  default: return default_content_type;

  case "css"_t: return "text/css";
  case "csv"_t: return "text/csv";
  case "htm"_t:
  case "html"_t: return "text/html";
  case "js"_t:
  case "mjs"_t: return "text/javascript";
  case "txt"_t: return "text/plain";
  case "vtt"_t: return "text/vtt";

  case "apng"_t: return "image/apng";
  case "avif"_t: return "image/avif";
  case "bmp"_t: return "image/bmp";
  case "gif"_t: return "image/gif";
  case "png"_t: return "image/png";
  case "svg"_t: return "image/svg+xml";
  case "webp"_t: return "image/webp";
  case "ico"_t: return "image/x-icon";
  case "tif"_t: return "image/tiff";
  case "tiff"_t: return "image/tiff";
  case "jpg"_t:
  case "jpeg"_t: return "image/jpeg";

  case "mp4"_t: return "video/mp4";
  case "mpeg"_t: return "video/mpeg";
  case "webm"_t: return "video/webm";

  case "mp3"_t: return "audio/mp3";
  case "mpga"_t: return "audio/mpeg";
  case "weba"_t: return "audio/webm";
  case "wav"_t: return "audio/wave";

  case "otf"_t: return "font/otf";
  case "ttf"_t: return "font/ttf";
  case "woff"_t: return "font/woff";
  case "woff2"_t: return "font/woff2";

  case "7z"_t: return "application/x-7z-compressed";
  case "atom"_t: return "application/atom+xml";
  case "pdf"_t: return "application/pdf";
  case "json"_t: return "application/json";
  case "rss"_t: return "application/rss+xml";
  case "tar"_t: return "application/x-tar";
  case "xht"_t:
  case "xhtml"_t: return "application/xhtml+xml";
  case "xslt"_t: return "application/xslt+xml";
  case "xml"_t: return "application/xml";
  case "gz"_t: return "application/gzip";
  case "zip"_t: return "application/zip";
  case "wasm"_t: return "application/wasm";
  }
}

std::string
extract_media_type(const std::string &content_type,
                   std::map<std::string, std::string> *params = nullptr) {
  // Extract type/subtype from Content-Type value (RFC 2045)
  // e.g. "application/json; charset=utf-8" -> "application/json"
  auto media_type = content_type;
  auto semicolon_pos = media_type.find(';');
  if (semicolon_pos != std::string::npos) {
    auto param_str = media_type.substr(semicolon_pos + 1);
    media_type = media_type.substr(0, semicolon_pos);

    if (params) {
      // Parse parameters: key=value pairs separated by ';'
      split(param_str.data(), param_str.data() + param_str.size(), ';',
            [&](const char *b, const char *e) {
              std::string key;
              std::string val;
              split(b, e, '=', [&](const char *b2, const char *e2) {
                if (key.empty()) {
                  key.assign(b2, e2);
                } else {
                  val.assign(b2, e2);
                }
              });
              if (!key.empty()) {
                params->emplace(trim_copy(key), trim_double_quotes_copy(val));
              }
            });
    }
  }

  // Trim whitespace from media type
  return trim_copy(media_type);
}

bool can_compress_content_type(const std::string &content_type) {
  using udl::operator""_t;

  auto mime_type = extract_media_type(content_type);
  auto tag = str2tag(mime_type);

  switch (tag) {
  case "image/svg+xml"_t:
  case "application/javascript"_t:
  case "application/x-javascript"_t:
  case "application/json"_t:
  case "application/ld+json"_t:
  case "application/xml"_t:
  case "application/xhtml+xml"_t:
  case "application/rss+xml"_t:
  case "application/atom+xml"_t:
  case "application/xslt+xml"_t:
  case "application/protobuf"_t: return true;

  case "text/event-stream"_t: return false;

  default: return !mime_type.rfind("text/", 0);
  }
}

bool parse_quality(const char *b, const char *e, std::string &token,
                          double &quality) {
  quality = 1.0;
  token.clear();

  // Split on first ';': left = token name, right = parameters
  const char *params_b = nullptr;
  std::size_t params_len = 0;

  divide(
      b, static_cast<std::size_t>(e - b), ';',
      [&](const char *lb, std::size_t llen, const char *rb, std::size_t rlen) {
        auto r = trim(lb, lb + llen, 0, llen);
        if (r.first < r.second) { token.assign(lb + r.first, lb + r.second); }
        params_b = rb;
        params_len = rlen;
      });

  if (token.empty()) { return false; }
  if (params_len == 0) { return true; }

  // Scan parameters for q= (stops on first match)
  bool invalid = false;
  split_find(params_b, params_b + params_len, ';',
             (std::numeric_limits<size_t>::max)(),
             [&](const char *pb, const char *pe) -> bool {
               // Match exactly "q=" or "Q=" (not "query=" etc.)
               auto len = static_cast<size_t>(pe - pb);
               if (len < 2) { return false; }
               if ((pb[0] != 'q' && pb[0] != 'Q') || pb[1] != '=') {
                 return false;
               }

               // Trim the value portion
               auto r = trim(pb, pe, 2, len);
               if (r.first >= r.second) {
                 invalid = true;
                 return true;
               }

               double v = 0.0;
               auto res = from_chars(pb + r.first, pb + r.second, v);
               if (res.ec != std::errc{} || v < 0.0 || v > 1.0) {
                 invalid = true;
                 return true;
               }
               quality = v;
               return true;
             });

  return !invalid;
}

EncodingType encoding_type(const Request &req, const Response &res) {
  if (!can_compress_content_type(res.get_header_value("Content-Type"))) {
    return EncodingType::None;
  }

  const auto &s = req.get_header_value("Accept-Encoding");
  if (s.empty()) { return EncodingType::None; }

  // Single-pass: iterate tokens and track the best supported encoding.
  // Server preference breaks ties (br > gzip > zstd).
  EncodingType best = EncodingType::None;
  double best_q = 0.0; // q=0 means "not acceptable"

  // Server preference: Brotli > Gzip > Zstd (lower = more preferred)
  auto priority = [](EncodingType t) -> int {
    switch (t) {
    case EncodingType::Brotli: return 0;
    case EncodingType::Gzip: return 1;
    case EncodingType::Zstd: return 2;
    default: return 3;
    }
  };

  std::string name;
  split(s.data(), s.data() + s.size(), ',', [&](const char *b, const char *e) {
    double quality = 1.0;
    if (!parse_quality(b, e, name, quality)) { return; }
    if (quality <= 0.0) { return; }

    EncodingType type = EncodingType::None;
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
    if (case_ignore::equal(name, "br")) { type = EncodingType::Brotli; }
#endif
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
    if (type == EncodingType::None && case_ignore::equal(name, "gzip")) {
      type = EncodingType::Gzip;
    }
#endif
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
    if (type == EncodingType::None && case_ignore::equal(name, "zstd")) {
      type = EncodingType::Zstd;
    }
#endif

    if (type == EncodingType::None) { return; }

    // Higher q-value wins; for equal q, server preference breaks ties
    if (quality > best_q ||
        (quality == best_q && priority(type) < priority(best))) {
      best_q = quality;
      best = type;
    }
  });

  return best;
}

std::unique_ptr<compressor> make_compressor(EncodingType type) {
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
  if (type == EncodingType::Gzip) {
    return detail::make_unique<gzip_compressor>();
  }
#endif
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
  if (type == EncodingType::Brotli) {
    return detail::make_unique<brotli_compressor>();
  }
#endif
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
  if (type == EncodingType::Zstd) {
    return detail::make_unique<zstd_compressor>();
  }
#endif
  (void)type;
  return nullptr;
}

const char *encoding_name(EncodingType type) {
  switch (type) {
  case EncodingType::Gzip: return "gzip";
  case EncodingType::Brotli: return "br";
  case EncodingType::Zstd: return "zstd";
  default: return "";
  }
}

bool nocompressor::compress(const char *data, size_t data_length,
                                   bool /*last*/, Callback callback) {
  if (!data_length) { return true; }
  return callback(data, data_length);
}

#ifdef CPPHTTPLIB_ZLIB_SUPPORT
gzip_compressor::gzip_compressor() {
  std::memset(&strm_, 0, sizeof(strm_));
  strm_.zalloc = Z_NULL;
  strm_.zfree = Z_NULL;
  strm_.opaque = Z_NULL;

  is_valid_ = deflateInit2(&strm_, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 31, 8,
                           Z_DEFAULT_STRATEGY) == Z_OK;
}

gzip_compressor::~gzip_compressor() { deflateEnd(&strm_); }

bool gzip_compressor::compress(const char *data, size_t data_length,
                                      bool last, Callback callback) {
  assert(is_valid_);

  do {
    constexpr size_t max_avail_in =
        (std::numeric_limits<decltype(strm_.avail_in)>::max)();

    strm_.avail_in = static_cast<decltype(strm_.avail_in)>(
        (std::min)(data_length, max_avail_in));
    strm_.next_in = const_cast<Bytef *>(reinterpret_cast<const Bytef *>(data));

    data_length -= strm_.avail_in;
    data += strm_.avail_in;

    auto flush = (last && data_length == 0) ? Z_FINISH : Z_NO_FLUSH;
    auto ret = Z_OK;

    std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
    do {
      strm_.avail_out = static_cast<uInt>(buff.size());
      strm_.next_out = reinterpret_cast<Bytef *>(buff.data());

      ret = deflate(&strm_, flush);
      if (ret == Z_STREAM_ERROR) { return false; }

      if (!callback(buff.data(), buff.size() - strm_.avail_out)) {
        return false;
      }
    } while (strm_.avail_out == 0);

    assert((flush == Z_FINISH && ret == Z_STREAM_END) ||
           (flush == Z_NO_FLUSH && ret == Z_OK));
    assert(strm_.avail_in == 0);
  } while (data_length > 0);

  return true;
}

gzip_decompressor::gzip_decompressor() {
  std::memset(&strm_, 0, sizeof(strm_));
  strm_.zalloc = Z_NULL;
  strm_.zfree = Z_NULL;
  strm_.opaque = Z_NULL;

  // 15 is the value of wbits, which should be at the maximum possible value
  // to ensure that any gzip stream can be decoded. The offset of 32 specifies
  // that the stream type should be automatically detected either gzip or
  // deflate.
  is_valid_ = inflateInit2(&strm_, 32 + 15) == Z_OK;
}

gzip_decompressor::~gzip_decompressor() { inflateEnd(&strm_); }

bool gzip_decompressor::is_valid() const { return is_valid_; }

bool gzip_decompressor::decompress(const char *data, size_t data_length,
                                          Callback callback) {
  assert(is_valid_);

  auto ret = Z_OK;

  do {
    constexpr size_t max_avail_in =
        (std::numeric_limits<decltype(strm_.avail_in)>::max)();

    strm_.avail_in = static_cast<decltype(strm_.avail_in)>(
        (std::min)(data_length, max_avail_in));
    strm_.next_in = const_cast<Bytef *>(reinterpret_cast<const Bytef *>(data));

    data_length -= strm_.avail_in;
    data += strm_.avail_in;

    std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
    while (strm_.avail_in > 0 && ret == Z_OK) {
      strm_.avail_out = static_cast<uInt>(buff.size());
      strm_.next_out = reinterpret_cast<Bytef *>(buff.data());

      ret = inflate(&strm_, Z_NO_FLUSH);

      assert(ret != Z_STREAM_ERROR);
      switch (ret) {
      case Z_NEED_DICT:
      case Z_DATA_ERROR:
      case Z_MEM_ERROR: inflateEnd(&strm_); return false;
      }

      if (!callback(buff.data(), buff.size() - strm_.avail_out)) {
        return false;
      }
    }

    if (ret != Z_OK && ret != Z_STREAM_END) { return false; }

  } while (data_length > 0);

  return true;
}
#endif

#ifdef CPPHTTPLIB_BROTLI_SUPPORT
brotli_compressor::brotli_compressor() {
  state_ = BrotliEncoderCreateInstance(nullptr, nullptr, nullptr);
}

brotli_compressor::~brotli_compressor() {
  BrotliEncoderDestroyInstance(state_);
}

bool brotli_compressor::compress(const char *data, size_t data_length,
                                        bool last, Callback callback) {
  std::array<uint8_t, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};

  auto operation = last ? BROTLI_OPERATION_FINISH : BROTLI_OPERATION_PROCESS;
  auto available_in = data_length;
  auto next_in = reinterpret_cast<const uint8_t *>(data);

  for (;;) {
    if (last) {
      if (BrotliEncoderIsFinished(state_)) { break; }
    } else {
      if (!available_in) { break; }
    }

    auto available_out = buff.size();
    auto next_out = buff.data();

    if (!BrotliEncoderCompressStream(state_, operation, &available_in, &next_in,
                                     &available_out, &next_out, nullptr)) {
      return false;
    }

    auto output_bytes = buff.size() - available_out;
    if (output_bytes) {
      callback(reinterpret_cast<const char *>(buff.data()), output_bytes);
    }
  }

  return true;
}

brotli_decompressor::brotli_decompressor() {
  decoder_s = BrotliDecoderCreateInstance(0, 0, 0);
  decoder_r = decoder_s ? BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT
                        : BROTLI_DECODER_RESULT_ERROR;
}

brotli_decompressor::~brotli_decompressor() {
  if (decoder_s) { BrotliDecoderDestroyInstance(decoder_s); }
}

bool brotli_decompressor::is_valid() const { return decoder_s; }

bool brotli_decompressor::decompress(const char *data,
                                            size_t data_length,
                                            Callback callback) {
  if (decoder_r == BROTLI_DECODER_RESULT_SUCCESS ||
      decoder_r == BROTLI_DECODER_RESULT_ERROR) {
    return 0;
  }

  auto next_in = reinterpret_cast<const uint8_t *>(data);
  size_t avail_in = data_length;
  size_t total_out;

  decoder_r = BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT;

  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
  while (decoder_r == BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT) {
    char *next_out = buff.data();
    size_t avail_out = buff.size();

    decoder_r = BrotliDecoderDecompressStream(
        decoder_s, &avail_in, &next_in, &avail_out,
        reinterpret_cast<uint8_t **>(&next_out), &total_out);

    if (decoder_r == BROTLI_DECODER_RESULT_ERROR) { return false; }

    if (!callback(buff.data(), buff.size() - avail_out)) { return false; }
  }

  return decoder_r == BROTLI_DECODER_RESULT_SUCCESS ||
         decoder_r == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT;
}
#endif

#ifdef CPPHTTPLIB_ZSTD_SUPPORT
zstd_compressor::zstd_compressor() {
  ctx_ = ZSTD_createCCtx();
  ZSTD_CCtx_setParameter(ctx_, ZSTD_c_compressionLevel, ZSTD_fast);
}

zstd_compressor::~zstd_compressor() { ZSTD_freeCCtx(ctx_); }

bool zstd_compressor::compress(const char *data, size_t data_length,
                                      bool last, Callback callback) {
  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};

  ZSTD_EndDirective mode = last ? ZSTD_e_end : ZSTD_e_continue;
  ZSTD_inBuffer input = {data, data_length, 0};

  bool finished;
  do {
    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
    size_t const remaining = ZSTD_compressStream2(ctx_, &output, &input, mode);

    if (ZSTD_isError(remaining)) { return false; }

    if (!callback(buff.data(), output.pos)) { return false; }

    finished = last ? (remaining == 0) : (input.pos == input.size);

  } while (!finished);

  return true;
}

zstd_decompressor::zstd_decompressor() { ctx_ = ZSTD_createDCtx(); }

zstd_decompressor::~zstd_decompressor() { ZSTD_freeDCtx(ctx_); }

bool zstd_decompressor::is_valid() const { return ctx_ != nullptr; }

bool zstd_decompressor::decompress(const char *data, size_t data_length,
                                          Callback callback) {
  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
  ZSTD_inBuffer input = {data, data_length, 0};

  while (input.pos < input.size) {
    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
    size_t const remaining = ZSTD_decompressStream(ctx_, &output, &input);

    if (ZSTD_isError(remaining)) { return false; }

    if (!callback(buff.data(), output.pos)) { return false; }
  }

  return true;
}
#endif

std::unique_ptr<decompressor>
create_decompressor(const std::string &encoding) {
  std::unique_ptr<decompressor> decompressor;

  if (encoding == "gzip" || encoding == "deflate") {
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
    decompressor = detail::make_unique<gzip_decompressor>();
#endif
  } else if (encoding.find("br") != std::string::npos) {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
    decompressor = detail::make_unique<brotli_decompressor>();
#endif
  } else if (encoding == "zstd" || encoding.find("zstd") != std::string::npos) {
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
    decompressor = detail::make_unique<zstd_decompressor>();
#endif
  }

  return decompressor;
}

// Returns the best available compressor and its Content-Encoding name.
// Priority: Brotli > Gzip > Zstd (matches server-side preference).
std::pair<std::unique_ptr<compressor>, const char *>
create_compressor() {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
  return {detail::make_unique<brotli_compressor>(), "br"};
#elif defined(CPPHTTPLIB_ZLIB_SUPPORT)
  return {detail::make_unique<gzip_compressor>(), "gzip"};
#elif defined(CPPHTTPLIB_ZSTD_SUPPORT)
  return {detail::make_unique<zstd_compressor>(), "zstd"};
#else
  return {nullptr, nullptr};
#endif
}

bool is_prohibited_header_name(const std::string &name) {
  using udl::operator""_t;

  switch (str2tag(name)) {
  case "REMOTE_ADDR"_t:
  case "REMOTE_PORT"_t:
  case "LOCAL_ADDR"_t:
  case "LOCAL_PORT"_t: return true;
  default: return false;
  }
}

bool has_header(const Headers &headers, const std::string &key) {
  if (is_prohibited_header_name(key)) { return false; }
  return headers.find(key) != headers.end();
}

const char *get_header_value(const Headers &headers,
                                    const std::string &key, const char *def,
                                    size_t id) {
  if (is_prohibited_header_name(key)) {
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
    std::string msg = "Prohibited header name '" + key + "' is specified.";
    throw std::invalid_argument(msg);
#else
    return "";
#endif
  }

  auto rng = headers.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second.c_str(); }
  return def;
}

size_t get_header_value_count(const Headers &headers,
                                     const std::string &key) {
  auto r = headers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

template <typename Map>
typename Map::mapped_type
get_multimap_value(const Map &m, const std::string &key, size_t id) {
  auto rng = m.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second; }
  return typename Map::mapped_type();
}

void set_header(Headers &headers, const std::string &key,
                       const std::string &val) {
  if (fields::is_field_valid(key, val)) { headers.emplace(key, val); }
}

bool read_headers(Stream &strm, Headers &headers) {
  const auto bufsiz = 2048;
  char buf[bufsiz];
  stream_line_reader line_reader(strm, buf, bufsiz);

  size_t header_count = 0;

  for (;;) {
    if (!line_reader.getline()) { return false; }

    // Check if the line ends with CRLF.
    auto line_terminator_len = 2;
    if (line_reader.end_with_crlf()) {
      // Blank line indicates end of headers.
      if (line_reader.size() == 2) { break; }
    } else {
#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
      // Blank line indicates end of headers.
      if (line_reader.size() == 1) { break; }
      line_terminator_len = 1;
#else
      continue; // Skip invalid line.
#endif
    }

    if (line_reader.size() > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }

    // Check header count limit
    if (header_count >= CPPHTTPLIB_HEADER_MAX_COUNT) { return false; }

    // Exclude line terminator
    auto end = line_reader.ptr() + line_reader.size() - line_terminator_len;

    if (!parse_header(line_reader.ptr(), end,
                      [&](const std::string &key, const std::string &val) {
                        headers.emplace(key, val);
                      })) {
      return false;
    }

    header_count++;
  }

  // RFC 9110 Section 8.6: Reject requests with multiple Content-Length
  // headers that have different values to prevent request smuggling.
  auto cl_range = headers.equal_range("Content-Length");
  if (cl_range.first != cl_range.second) {
    const auto &first_val = cl_range.first->second;
    for (auto it = std::next(cl_range.first); it != cl_range.second; ++it) {
      if (it->second != first_val) { return false; }
    }
  }

  return true;
}

bool read_websocket_upgrade_response(Stream &strm,
                                            const std::string &expected_accept,
                                            std::string &selected_subprotocol) {
  // Read status line
  const auto bufsiz = 2048;
  char buf[bufsiz];
  stream_line_reader line_reader(strm, buf, bufsiz);
  if (!line_reader.getline()) { return false; }

  // Check for "HTTP/1.1 101"
  auto line = std::string(line_reader.ptr(), line_reader.size());
  if (line.find("HTTP/1.1 101") == std::string::npos) { return false; }

  // Parse headers using existing read_headers
  Headers headers;
  if (!read_headers(strm, headers)) { return false; }

  // Verify Upgrade: websocket (case-insensitive)
  auto upgrade_it = headers.find("Upgrade");
  if (upgrade_it == headers.end()) { return false; }
  auto upgrade_val = case_ignore::to_lower(upgrade_it->second);
  if (upgrade_val != "websocket") { return false; }

  // Verify Connection header contains "Upgrade" (case-insensitive)
  auto connection_it = headers.find("Connection");
  if (connection_it == headers.end()) { return false; }
  auto connection_val = case_ignore::to_lower(connection_it->second);
  if (connection_val.find("upgrade") == std::string::npos) { return false; }

  // Verify Sec-WebSocket-Accept header value
  auto it = headers.find("Sec-WebSocket-Accept");
  if (it == headers.end() || it->second != expected_accept) { return false; }

  // Extract negotiated subprotocol
  auto proto_it = headers.find("Sec-WebSocket-Protocol");
  if (proto_it != headers.end()) { selected_subprotocol = proto_it->second; }

  return true;
}

enum class ReadContentResult {
  Success,         // Successfully read the content
  PayloadTooLarge, // The content exceeds the specified payload limit
  Error            // An error occurred while reading the content
};

ReadContentResult read_content_with_length(
    Stream &strm, size_t len, DownloadProgress progress,
    ContentReceiverWithProgress out,
    size_t payload_max_length = (std::numeric_limits<size_t>::max)()) {
  char buf[CPPHTTPLIB_RECV_BUFSIZ];

  detail::BodyReader br;
  br.stream = &strm;
  br.has_content_length = true;
  br.content_length = len;
  br.payload_max_length = payload_max_length;
  br.chunked = false;
  br.bytes_read = 0;
  br.last_error = Error::Success;

  size_t r = 0;
  while (r < len) {
    auto read_len = static_cast<size_t>(len - r);
    auto to_read = (std::min)(read_len, CPPHTTPLIB_RECV_BUFSIZ);
    auto n = detail::read_body_content(&strm, br, buf, to_read);
    if (n <= 0) {
      // Check if it was a payload size error
      if (br.last_error == Error::ExceedMaxPayloadSize) {
        return ReadContentResult::PayloadTooLarge;
      }
      return ReadContentResult::Error;
    }

    if (!out(buf, static_cast<size_t>(n), r, len)) {
      return ReadContentResult::Error;
    }
    r += static_cast<size_t>(n);

    if (progress) {
      if (!progress(r, len)) { return ReadContentResult::Error; }
    }
  }

  return ReadContentResult::Success;
}

ReadContentResult
read_content_without_length(Stream &strm, size_t payload_max_length,
                            ContentReceiverWithProgress out) {
  char buf[CPPHTTPLIB_RECV_BUFSIZ];
  size_t r = 0;
  for (;;) {
    auto n = strm.read(buf, CPPHTTPLIB_RECV_BUFSIZ);
    if (n == 0) { return ReadContentResult::Success; }
    if (n < 0) { return ReadContentResult::Error; }

    // Check if adding this data would exceed the payload limit
    if (r > payload_max_length ||
        payload_max_length - r < static_cast<size_t>(n)) {
      return ReadContentResult::PayloadTooLarge;
    }

    if (!out(buf, static_cast<size_t>(n), r, 0)) {
      return ReadContentResult::Error;
    }
    r += static_cast<size_t>(n);
  }

  return ReadContentResult::Success;
}

template <typename T>
ReadContentResult read_content_chunked(Stream &strm, T &x,
                                              size_t payload_max_length,
                                              ContentReceiverWithProgress out) {
  detail::ChunkedDecoder dec(strm);

  char buf[CPPHTTPLIB_RECV_BUFSIZ];
  size_t total_len = 0;

  for (;;) {
    size_t chunk_offset = 0;
    size_t chunk_total = 0;
    auto n = dec.read_payload(buf, sizeof(buf), chunk_offset, chunk_total);
    if (n < 0) { return ReadContentResult::Error; }

    if (n == 0) {
      if (!dec.parse_trailers_into(x.trailers, x.headers)) {
        return ReadContentResult::Error;
      }
      return ReadContentResult::Success;
    }

    if (total_len > payload_max_length ||
        payload_max_length - total_len < static_cast<size_t>(n)) {
      return ReadContentResult::PayloadTooLarge;
    }

    if (!out(buf, static_cast<size_t>(n), chunk_offset, chunk_total)) {
      return ReadContentResult::Error;
    }

    total_len += static_cast<size_t>(n);
  }
}

bool is_chunked_transfer_encoding(const Headers &headers) {
  // RFC 9112 6.1: a message is framed with the chunked coding when "chunked"
  // is the final transfer coding. A single field value may list several
  // codings ("gzip, chunked"), and the list may be split across multiple
  // Transfer-Encoding header lines (RFC 9110 5.3). Match the last coding token
  // case-insensitively rather than comparing the whole value against "chunked".
  //
  // Security: reading a chunked message as unframed leaves its body in the
  // socket, where a keep-alive connection parses it as a smuggled request.
  // Headers is an unordered_multimap whose iteration order for duplicate keys
  // is not portable, so when there is more than one Transfer-Encoding line we
  // cannot tell which coding is truly final. In that ambiguous case we fail
  // safe by treating the message as chunked (a mis-parse just closes the
  // connection, whereas the opposite error enables smuggling).
  auto rng = headers.equal_range("Transfer-Encoding");

  size_t line_count = 0;
  bool chunked_present = false;
  bool last_line_ends_with_chunked = false;

  for (auto it = rng.first; it != rng.second; ++it) {
    line_count++;
    const auto &value = it->second;

    std::string last_coding;
    bool line_has_chunked = false;
    split(value.data(), value.data() + value.size(), ',',
          [&](const char *b, const char *e) {
            last_coding.assign(b, e);
            if (case_ignore::equal(last_coding, "chunked")) {
              line_has_chunked = true;
            }
          });

    if (line_has_chunked) { chunked_present = true; }
    last_line_ends_with_chunked = case_ignore::equal(last_coding, "chunked");
  }

  if (line_count == 0) { return false; }
  if (line_count == 1) { return last_line_ends_with_chunked; }
  return chunked_present;
}

template <typename T, typename U>
bool prepare_content_receiver(T &x, int &status,
                              ContentReceiverWithProgress receiver,
                              bool decompress, size_t payload_max_length,
                              bool &exceed_payload_max_length, U callback) {
  if (decompress) {
    std::string encoding = x.get_header_value("Content-Encoding");
    std::unique_ptr<decompressor> decompressor;

    if (!encoding.empty()) {
      decompressor = detail::create_decompressor(encoding);
      if (!decompressor) {
        // Unsupported encoding or no support compiled in
        status = StatusCode::UnsupportedMediaType_415;
        return false;
      }
    }

    if (decompressor) {
      if (decompressor->is_valid()) {
        size_t decompressed_size = 0;
        ContentReceiverWithProgress out = [&](const char *buf, size_t n,
                                              size_t off, size_t len) {
          return decompressor->decompress(
              buf, n, [&](const char *buf2, size_t n2) {
                // Guard against zip-bomb: check
                // decompressed size against limit.
                if (payload_max_length > 0 &&
                    (decompressed_size >= payload_max_length ||
                     n2 > payload_max_length - decompressed_size)) {
                  exceed_payload_max_length = true;
                  return false;
                }
                decompressed_size += n2;
                return receiver(buf2, n2, off, len);
              });
        };
        return callback(std::move(out));
      } else {
        status = StatusCode::InternalServerError_500;
        return false;
      }
    }
  }

  ContentReceiverWithProgress out = [&](const char *buf, size_t n, size_t off,
                                        size_t len) {
    return receiver(buf, n, off, len);
  };
  return callback(std::move(out));
}

template <typename T>
bool read_content(Stream &strm, T &x, size_t payload_max_length, int &status,
                  DownloadProgress progress,
                  ContentReceiverWithProgress receiver, bool decompress) {
  bool exceed_payload_max_length = false;
  return prepare_content_receiver(
      x, status, std::move(receiver), decompress, payload_max_length,
      exceed_payload_max_length, [&](const ContentReceiverWithProgress &out) {
        auto ret = true;
        // Note: exceed_payload_max_length may also be set by the decompressor
        // wrapper in prepare_content_receiver when the decompressed payload
        // size exceeds the limit.

        if (is_chunked_transfer_encoding(x.headers)) {
          auto result = read_content_chunked(strm, x, payload_max_length, out);
          if (result == ReadContentResult::Success) {
            ret = true;
          } else if (result == ReadContentResult::PayloadTooLarge) {
            exceed_payload_max_length = true;
            ret = false;
          } else {
            ret = false;
          }
        } else if (!has_header(x.headers, "Content-Length")) {
          auto result =
              read_content_without_length(strm, payload_max_length, out);
          if (result == ReadContentResult::Success) {
            ret = true;
          } else if (result == ReadContentResult::PayloadTooLarge) {
            exceed_payload_max_length = true;
            ret = false;
          } else {
            ret = false;
          }
        } else {
          auto is_invalid_value = false;
          auto len = get_header_value_u64(x.headers, "Content-Length",
                                          (std::numeric_limits<size_t>::max)(),
                                          0, is_invalid_value);

          if (is_invalid_value) {
            ret = false;
          } else if (len > 0) {
            auto result = read_content_with_length(
                strm, len, std::move(progress), out, payload_max_length);
            ret = (result == ReadContentResult::Success);
            if (result == ReadContentResult::PayloadTooLarge) {
              exceed_payload_max_length = true;
            }
          }
        }

        if (!ret) {
          status = exceed_payload_max_length ? StatusCode::PayloadTooLarge_413
                                             : StatusCode::BadRequest_400;
        }
        return ret;
      });
}

ssize_t write_request_line(Stream &strm, const std::string &method,
                                  const std::string &path) {
  // A request target must not carry CR/LF (or other control octets); otherwise
  // a value smuggled into it splits the request line and injects headers or a
  // whole request. The same field-value check already guards header values in
  // check_and_write_headers and the request target in
  // perform_websocket_handshake; apply it here too.
  if (!fields::is_field_value(path)) { return -1; }

  std::string s = method;
  s += ' ';
  s += path;
  s += " HTTP/1.1\r\n";
  return strm.write(s.data(), s.size());
}

ssize_t write_response_line(Stream &strm, int status) {
  std::string s = "HTTP/1.1 ";
  s += std::to_string(status);
  s += ' ';
  s += httplib::status_message(status);
  s += "\r\n";
  return strm.write(s.data(), s.size());
}

ssize_t write_headers(Stream &strm, const Headers &headers) {
  ssize_t write_len = 0;
  for (const auto &x : headers) {
    // Skip fields with invalid names or values to prevent response splitting
    // via CR/LF injection, matching set_header(). The client validates request
    // headers up front in check_and_write_headers, but the server passes
    // res.headers straight to this writer, and res.headers is a public field
    // an application can populate directly with request-derived values.
    if (!fields::is_field_valid(x.first, x.second)) { continue; }

    std::string s;
    s = x.first;
    s += ": ";
    s += x.second;
    s += "\r\n";

    auto len = strm.write(s.data(), s.size());
    if (len < 0) { return len; }
    write_len += len;
  }
  auto len = strm.write("\r\n");
  if (len < 0) { return len; }
  write_len += len;
  return write_len;
}

bool write_data(Stream &strm, const char *d, size_t l) {
  size_t offset = 0;
  while (offset < l) {
    auto length = strm.write(d + offset, l - offset);
    if (length < 0) { return false; }
    offset += static_cast<size_t>(length);
  }
  return true;
}

template <typename T>
bool write_content_with_progress(Stream &strm,
                                        const ContentProvider &content_provider,
                                        size_t offset, size_t length,
                                        T is_shutting_down,
                                        const UploadProgress &upload_progress,
                                        Error &error) {
  size_t end_offset = offset + length;
  size_t start_offset = offset;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      if (write_data(strm, d, l)) {
        offset += l;

        if (upload_progress && length > 0) {
          size_t current_written = offset - start_offset;
          if (!upload_progress(current_written, length)) {
            ok = false;
            return false;
          }
        }
      } else {
        ok = false;
      }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  while (offset < end_offset && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      error = Error::Write;
      return false;
    } else if (!content_provider(offset, end_offset - offset, data_sink)) {
      error = Error::Canceled;
      return false;
    } else if (!ok) {
      error = Error::Write;
      return false;
    }
  }

  if (offset < end_offset) { // exited due to is_shutting_down(), not completion
    error = Error::Write;
    return false;
  }

  error = Error::Success;
  return true;
}

template <typename T>
bool write_content(Stream &strm, const ContentProvider &content_provider,
                          size_t offset, size_t length, T is_shutting_down,
                          Error &error) {
  return write_content_with_progress<T>(strm, content_provider, offset, length,
                                        is_shutting_down, nullptr, error);
}

template <typename T>
bool write_content(Stream &strm, const ContentProvider &content_provider,
                          size_t offset, size_t length,
                          const T &is_shutting_down) {
  auto error = Error::Success;
  return write_content(strm, content_provider, offset, length, is_shutting_down,
                       error);
}

template <typename T>
bool
write_content_without_length(Stream &strm,
                             const ContentProvider &content_provider,
                             const T &is_shutting_down) {
  size_t offset = 0;
  auto data_available = true;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      offset += l;
      if (!write_data(strm, d, l)) { ok = false; }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  data_sink.done = [&](void) { data_available = false; };

  while (data_available && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      return false;
    } else if (!content_provider(offset, 0, data_sink)) {
      return false;
    } else if (!ok) {
      return false;
    }
  }
  return !data_available; // true only if done() was called, false if shutting
                          // down
}

template <typename T, typename U>
bool
write_content_chunked(Stream &strm, const ContentProvider &content_provider,
                      const T &is_shutting_down, U &compressor, Error &error) {
  size_t offset = 0;
  auto data_available = true;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      data_available = l > 0;
      offset += l;

      std::string payload;
      if (compressor.compress(d, l, false,
                              [&](const char *data, size_t data_len) {
                                payload.append(data, data_len);
                                return true;
                              })) {
        if (!payload.empty()) {
          // Emit chunked response header and footer for each chunk
          auto chunk =
              from_i_to_hex(payload.size()) + "\r\n" + payload + "\r\n";
          if (!write_data(strm, chunk.data(), chunk.size())) { ok = false; }
        }
      } else {
        ok = false;
      }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  auto done_with_trailer = [&](const Headers *trailer) {
    if (!ok) { return; }

    data_available = false;

    std::string payload;
    if (!compressor.compress(nullptr, 0, true,
                             [&](const char *data, size_t data_len) {
                               payload.append(data, data_len);
                               return true;
                             })) {
      ok = false;
      return;
    }

    if (!payload.empty()) {
      // Emit chunked response header and footer for each chunk
      auto chunk = from_i_to_hex(payload.size()) + "\r\n" + payload + "\r\n";
      if (!write_data(strm, chunk.data(), chunk.size())) {
        ok = false;
        return;
      }
    }

    constexpr const char done_marker[] = "0\r\n";
    if (!write_data(strm, done_marker, str_len(done_marker))) { ok = false; }

    // Trailer
    if (trailer) {
      for (const auto &kv : *trailer) {
        // Skip fields with invalid names or values to prevent response
        // splitting via CR/LF injection, matching set_header().
        if (!fields::is_field_valid(kv.first, kv.second)) { continue; }
        std::string field_line = kv.first + ": " + kv.second + "\r\n";
        if (!write_data(strm, field_line.data(), field_line.size())) {
          ok = false;
        }
      }
    }

    constexpr const char crlf[] = "\r\n";
    if (!write_data(strm, crlf, str_len(crlf))) { ok = false; }
  };

  data_sink.done = [&](void) { done_with_trailer(nullptr); };

  data_sink.done_with_trailer = [&](const Headers &trailer) {
    done_with_trailer(&trailer);
  };

  while (data_available && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      error = Error::Write;
      return false;
    } else if (!content_provider(offset, 0, data_sink)) {
      error = Error::Canceled;
      return false;
    } else if (!ok) {
      error = Error::Write;
      return false;
    }
  }

  if (data_available) { // exited due to is_shutting_down(), not done()
    error = Error::Write;
    return false;
  }

  error = Error::Success;
  return true;
}

template <typename T, typename U>
bool write_content_chunked(Stream &strm,
                                  const ContentProvider &content_provider,
                                  const T &is_shutting_down, U &compressor) {
  auto error = Error::Success;
  return write_content_chunked(strm, content_provider, is_shutting_down,
                               compressor, error);
}

template <typename T>
bool redirect(T &cli, Request &req, Response &res,
                     const std::string &path, const std::string &location,
                     Error &error) {
  Request new_req = req;
  new_req.path = path;
  new_req.redirect_count_ -= 1;

  if (res.status == StatusCode::SeeOther_303 &&
      (req.method != "GET" && req.method != "HEAD")) {
    new_req.method = "GET";
    new_req.body.clear();
    new_req.headers.clear();
  }

  Response new_res;

  auto ret = cli.send(new_req, new_res, error);
  if (ret) {
    req = std::move(new_req);
    res = std::move(new_res);

    if (res.location.empty()) { res.location = location; }
  }
  return ret;
}

std::string params_to_query_str(const Params &params) {
  std::string query;

  for (auto it = params.begin(); it != params.end(); ++it) {
    if (it != params.begin()) { query += '&'; }
    query += encode_query_component(it->first);
    query += '=';
    query += encode_query_component(it->second);
  }
  return query;
}

void parse_query_text(const char *data, std::size_t size,
                             Params &params) {
  std::set<std::string> cache;
  split(data, data + size, '&', [&](const char *b, const char *e) {
    std::string kv(b, e);
    if (cache.find(kv) != cache.end()) { return; }
    cache.insert(std::move(kv));

    std::string key;
    std::string val;
    divide(b, static_cast<std::size_t>(e - b), '=',
           [&](const char *lhs_data, std::size_t lhs_size, const char *rhs_data,
               std::size_t rhs_size) {
             key.assign(lhs_data, lhs_size);
             val.assign(rhs_data, rhs_size);
           });

    if (!key.empty()) {
      params.emplace(decode_query_component(key), decode_query_component(val));
    }
  });
}

void parse_query_text(const std::string &s, Params &params) {
  parse_query_text(s.data(), s.size(), params);
}

// Normalize a query string by decoding and re-encoding each key/value pair
// while preserving the original parameter order. This avoids double-encoding
// and ensures consistent encoding without reordering (unlike Params which
// uses std::multimap and sorts keys).
std::string normalize_query_string(const std::string &query) {
  std::string result;
  split(query.data(), query.data() + query.size(), '&',
        [&](const char *b, const char *e) {
          std::string key;
          std::string val;
          divide(b, static_cast<std::size_t>(e - b), '=',
                 [&](const char *lhs_data, std::size_t lhs_size,
                     const char *rhs_data, std::size_t rhs_size) {
                   key.assign(lhs_data, lhs_size);
                   val.assign(rhs_data, rhs_size);
                 });

          if (!key.empty()) {
            auto dec_key = decode_query_component(key);
            auto dec_val = decode_query_component(val);

            if (!result.empty()) { result += '&'; }
            result += encode_query_component(dec_key);
            if (!val.empty() || std::find(b, e, '=') != e) {
              result += '=';
              result += encode_query_component(dec_val);
            }
          }
        });
  return result;
}

bool parse_multipart_boundary(const std::string &content_type,
                                     std::string &boundary) {
  std::map<std::string, std::string> params;
  extract_media_type(content_type, &params);
  auto it = params.find("boundary");
  if (it == params.end()) { return false; }
  boundary = it->second;
  return !boundary.empty();
}

void parse_disposition_params(const std::string &s, Params &params) {
  std::set<std::string> cache;
  split(s.data(), s.data() + s.size(), ';', [&](const char *b, const char *e) {
    std::string kv(b, e);
    if (cache.find(kv) != cache.end()) { return; }
    cache.insert(kv);

    std::string key;
    std::string val;
    split(b, e, '=', [&](const char *b2, const char *e2) {
      if (key.empty()) {
        key.assign(b2, e2);
      } else {
        val.assign(b2, e2);
      }
    });

    if (!key.empty()) {
      params.emplace(trim_double_quotes_copy((key)),
                     trim_double_quotes_copy((val)));
    }
  });
}

#ifdef CPPHTTPLIB_NO_EXCEPTIONS
bool parse_range_header(const std::string &s, Ranges &ranges) {
#else
bool parse_range_header(const std::string &s, Ranges &ranges) try {
#endif
  auto is_valid = [](const std::string &str) {
    return std::all_of(str.cbegin(), str.cend(), is_ascii_digit);
  };

  if (s.size() > 7 && s.compare(0, 6, "bytes=") == 0) {
    const auto pos = static_cast<size_t>(6);
    const auto len = static_cast<size_t>(s.size() - 6);
    auto all_valid_ranges = true;
    split(&s[pos], &s[pos + len], ',', [&](const char *b, const char *e) {
      if (!all_valid_ranges) { return; }

      const auto it = std::find(b, e, '-');
      if (it == e) {
        all_valid_ranges = false;
        return;
      }

      const auto lhs = std::string(b, it);
      const auto rhs = std::string(it + 1, e);
      if (!is_valid(lhs) || !is_valid(rhs)) {
        all_valid_ranges = false;
        return;
      }

      ssize_t first = -1;
      if (!lhs.empty()) {
        ssize_t v;
        auto res = detail::from_chars(lhs.data(), lhs.data() + lhs.size(), v);
        if (res.ec == std::errc{}) { first = v; }
      }

      ssize_t last = -1;
      if (!rhs.empty()) {
        ssize_t v;
        auto res = detail::from_chars(rhs.data(), rhs.data() + rhs.size(), v);
        if (res.ec == std::errc{}) { last = v; }
      }

      if ((first == -1 && last == -1) ||
          (first != -1 && last != -1 && first > last)) {
        all_valid_ranges = false;
        return;
      }

      ranges.emplace_back(first, last);
    });
    return all_valid_ranges && !ranges.empty();
  }
  return false;
#ifdef CPPHTTPLIB_NO_EXCEPTIONS
}
#else
} catch (...) { return false; }
#endif

bool parse_accept_header(const std::string &s,
                                std::vector<std::string> &content_types) {
  content_types.clear();

  // Empty string is considered valid (no preference)
  if (s.empty()) { return true; }

  // Check for invalid patterns: leading/trailing commas or consecutive commas
  if (s.front() == ',' || s.back() == ',' ||
      s.find(",,") != std::string::npos) {
    return false;
  }

  struct AcceptEntry {
    std::string media_type;
    double quality;
    int order;
  };

  std::vector<AcceptEntry> entries;
  int order = 0;
  bool has_invalid_entry = false;

  // Split by comma and parse each entry
  split(s.data(), s.data() + s.size(), ',', [&](const char *b, const char *e) {
    std::string entry(b, e);
    entry = trim_copy(entry);

    if (entry.empty()) {
      has_invalid_entry = true;
      return;
    }

    AcceptEntry accept_entry;
    accept_entry.order = order++;

    if (!parse_quality(entry.data(), entry.data() + entry.size(),
                       accept_entry.media_type, accept_entry.quality)) {
      has_invalid_entry = true;
      return;
    }

    // Remove additional parameters from media type
    accept_entry.media_type = extract_media_type(accept_entry.media_type);

    // Basic validation of media type format
    if (accept_entry.media_type.empty()) {
      has_invalid_entry = true;
      return;
    }

    // Check for basic media type format (should contain '/' or be '*')
    if (accept_entry.media_type != "*" &&
        accept_entry.media_type.find('/') == std::string::npos) {
      has_invalid_entry = true;
      return;
    }

    entries.push_back(std::move(accept_entry));
  });

  // Return false if any invalid entry was found
  if (has_invalid_entry) { return false; }

  // Sort by quality (descending), then by original order (ascending)
  std::sort(entries.begin(), entries.end(),
            [](const AcceptEntry &a, const AcceptEntry &b) {
              if (a.quality != b.quality) {
                return a.quality > b.quality; // Higher quality first
              }
              return a.order < b.order; // Earlier order first for same quality
            });

  // Extract sorted media types
  content_types.reserve(entries.size());
  for (auto &entry : entries) {
    content_types.push_back(std::move(entry.media_type));
  }

  return true;
}

class FormDataParser {
public:
  FormDataParser() = default;

  void set_boundary(std::string &&boundary) {
    boundary_ = std::move(boundary);
    dash_boundary_crlf_ = dash_ + boundary_ + crlf_;
    crlf_dash_boundary_ = crlf_ + dash_ + boundary_;
  }

  bool is_valid() const { return is_valid_; }

  bool parse(const char *buf, size_t n, const FormDataHeader &header_callback,
             const ContentReceiver &content_callback) {

    buf_append(buf, n);

    while (buf_size() > 0) {
      switch (state_) {
      case 0: { // Initial boundary
        auto pos = buf_find(dash_boundary_crlf_);
        if (pos == buf_size()) { return true; }
        buf_erase(pos + dash_boundary_crlf_.size());
        state_ = 1;
        break;
      }
      case 1: { // New entry
        clear_file_info();
        state_ = 2;
        break;
      }
      case 2: { // Headers
        auto pos = buf_find(crlf_);
        if (pos > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }
        while (pos < buf_size()) {
          // Empty line
          if (pos == 0) {
            if (!header_callback(file_)) {
              is_valid_ = false;
              return false;
            }
            buf_erase(crlf_.size());
            state_ = 3;
            break;
          }

          // Check header count limit
          if (header_count_ >= CPPHTTPLIB_HEADER_MAX_COUNT) {
            is_valid_ = false;
            return false;
          }
          header_count_++;

          const auto header = buf_head(pos);

          if (!parse_header(header.data(), header.data() + header.size(),
                            [&](const std::string &, const std::string &) {})) {
            is_valid_ = false;
            return false;
          }

          // Parse and emplace space trimmed headers into a map
          if (!parse_header(
                  header.data(), header.data() + header.size(),
                  [&](const std::string &key, const std::string &val) {
                    file_.headers.emplace(key, val);
                  })) {
            is_valid_ = false;
            return false;
          }

          constexpr const char header_content_type[] = "Content-Type:";

          if (start_with_case_ignore(header, header_content_type)) {
            file_.content_type =
                trim_copy(header.substr(str_len(header_content_type)));
          } else {
            std::string disposition_params;
            if (parse_content_disposition(header, disposition_params)) {
              Params params;
              parse_disposition_params(disposition_params, params);

              auto it = params.find("name");
              if (it != params.end()) {
                file_.name = it->second;
              } else {
                is_valid_ = false;
                return false;
              }

              it = params.find("filename");
              if (it != params.end()) { file_.filename = it->second; }

              it = params.find("filename*");
              if (it != params.end()) {
                // RFC 5987: only UTF-8 encoding is allowed
                const auto &val = it->second;
                constexpr const char utf8_prefix[] = "UTF-8''";
                constexpr size_t prefix_len = str_len(utf8_prefix);
                if (val.size() > prefix_len &&
                    start_with_case_ignore(val, utf8_prefix)) {
                  file_.filename = decode_path_component(
                      val.substr(prefix_len)); // override...
                } else {
                  is_valid_ = false;
                  return false;
                }
              }
            }
          }
          buf_erase(pos + crlf_.size());
          pos = buf_find(crlf_);
        }
        if (state_ != 3) { return true; }
        break;
      }
      case 3: { // Body
        if (crlf_dash_boundary_.size() > buf_size()) { return true; }
        auto pos = buf_find(crlf_dash_boundary_);
        if (pos < buf_size()) {
          if (!content_callback(buf_data(), pos)) {
            is_valid_ = false;
            return false;
          }
          buf_erase(pos + crlf_dash_boundary_.size());
          state_ = 4;
        } else {
          auto len = buf_size() - crlf_dash_boundary_.size();
          if (len > 0) {
            if (!content_callback(buf_data(), len)) {
              is_valid_ = false;
              return false;
            }
            buf_erase(len);
          }
          return true;
        }
        break;
      }
      case 4: { // Boundary
        if (crlf_.size() > buf_size()) { return true; }
        if (buf_start_with(crlf_)) {
          buf_erase(crlf_.size());
          state_ = 1;
        } else {
          if (dash_.size() > buf_size()) { return true; }
          if (buf_start_with(dash_)) {
            buf_erase(dash_.size());
            is_valid_ = true;
            buf_erase(buf_size()); // Remove epilogue
          } else {
            return true;
          }
        }
        break;
      }
      }
    }

    return true;
  }

private:
  void clear_file_info() {
    file_.name.clear();
    file_.filename.clear();
    file_.content_type.clear();
    file_.headers.clear();
    header_count_ = 0;
  }

  bool start_with_case_ignore(const std::string &a, const char *b,
                              size_t offset = 0) const {
    const auto b_len = strlen(b);
    if (a.size() < offset + b_len) { return false; }
    for (size_t i = 0; i < b_len; i++) {
      if (case_ignore::to_lower(a[offset + i]) != case_ignore::to_lower(b[i])) {
        return false;
      }
    }
    return true;
  }

  // Parses "Content-Disposition: form-data; <params>" without std::regex.
  // Returns true if header matches, with the params portion in `params_out`.
  bool parse_content_disposition(const std::string &header,
                                 std::string &params_out) const {
    constexpr const char prefix[] = "Content-Disposition:";
    constexpr size_t prefix_len = str_len(prefix);

    if (!start_with_case_ignore(header, prefix)) { return false; }

    // Skip whitespace after "Content-Disposition:"
    auto pos = prefix_len;
    while (pos < header.size() && (header[pos] == ' ' || header[pos] == '\t')) {
      pos++;
    }

    // Match "form-data;" (case-insensitive)
    constexpr const char form_data[] = "form-data;";
    constexpr size_t form_data_len = str_len(form_data);
    if (!start_with_case_ignore(header, form_data, pos)) { return false; }
    pos += form_data_len;

    // Skip whitespace after "form-data;"
    while (pos < header.size() && (header[pos] == ' ' || header[pos] == '\t')) {
      pos++;
    }

    params_out = header.substr(pos);
    return true;
  }

  const std::string dash_ = "--";
  const std::string crlf_ = "\r\n";
  std::string boundary_;
  std::string dash_boundary_crlf_;
  std::string crlf_dash_boundary_;

  size_t state_ = 0;
  bool is_valid_ = false;
  FormData file_;
  size_t header_count_ = 0;

  // Buffer
  bool start_with(const std::string &a, size_t spos, size_t epos,
                  const std::string &b) const {
    if (epos - spos < b.size()) { return false; }
    for (size_t i = 0; i < b.size(); i++) {
      if (a[i + spos] != b[i]) { return false; }
    }
    return true;
  }

  size_t buf_size() const { return buf_epos_ - buf_spos_; }

  const char *buf_data() const { return &buf_[buf_spos_]; }

  std::string buf_head(size_t l) const { return buf_.substr(buf_spos_, l); }

  bool buf_start_with(const std::string &s) const {
    return start_with(buf_, buf_spos_, buf_epos_, s);
  }

  size_t buf_find(const std::string &s) const {
    auto c = s.front();

    size_t off = buf_spos_;
    while (off < buf_epos_) {
      auto pos = off;
      while (true) {
        if (pos == buf_epos_) { return buf_size(); }
        if (buf_[pos] == c) { break; }
        pos++;
      }

      auto remaining_size = buf_epos_ - pos;
      if (s.size() > remaining_size) { return buf_size(); }

      if (start_with(buf_, pos, buf_epos_, s)) { return pos - buf_spos_; }

      off = pos + 1;
    }

    return buf_size();
  }

  void buf_append(const char *data, size_t n) {
    auto remaining_size = buf_size();
    if (remaining_size > 0 && buf_spos_ > 0) {
      for (size_t i = 0; i < remaining_size; i++) {
        buf_[i] = buf_[buf_spos_ + i];
      }
    }
    buf_spos_ = 0;
    buf_epos_ = remaining_size;

    if (remaining_size + n > buf_.size()) { buf_.resize(remaining_size + n); }

    for (size_t i = 0; i < n; i++) {
      buf_[buf_epos_ + i] = data[i];
    }
    buf_epos_ += n;
  }

  void buf_erase(size_t size) { buf_spos_ += size; }

  std::string buf_;
  size_t buf_spos_ = 0;
  size_t buf_epos_ = 0;
};

std::string random_string(size_t length) {
  constexpr const char data[] =
      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

  thread_local auto engine([]() {
    // std::random_device might actually be deterministic on some
    // platforms, but due to lack of support in the c++ standard library,
    // doing better requires either some ugly hacks or breaking portability.
    std::random_device seed_gen;
    // Request 128 bits of entropy for initialization
    std::seed_seq seed_sequence{seed_gen(), seed_gen(), seed_gen(), seed_gen()};
    return std::mt19937(seed_sequence);
  }());

  std::string result;
  for (size_t i = 0; i < length; i++) {
    result += data[engine() % (sizeof(data) - 1)];
  }
  return result;
}

std::string make_multipart_data_boundary() {
  return "--cpp-httplib-multipart-data-" + detail::random_string(16);
}

bool is_multipart_boundary_chars_valid(const std::string &boundary) {
  auto valid = true;
  for (size_t i = 0; i < boundary.size(); i++) {
    auto c = boundary[i];
    if (!is_ascii_alnum(c) && c != '-' && c != '_') {
      valid = false;
      break;
    }
  }
  return valid;
}

// Escape a multipart field name/filename following the WHATWG HTML standard
// ("escape a multipart form-data name"), which is what browsers send:
// '"' -> %22, CR -> %0D, LF -> %0A
// With escape_quote = false, only CR and LF are escaped; this is for header
// values outside a quoted-string (e.g. Content-Type), where '"' is legal.
std::string escape_multipart_field(const std::string &s,
                                          bool escape_quote = true) {
  std::string result;
  result.reserve(s.size());
  for (auto c : s) {
    switch (c) {
    case '"':
      if (escape_quote) {
        result += "%22";
      } else {
        result += c;
      }
      break;
    case '\r': result += "%0D"; break;
    case '\n': result += "%0A"; break;
    default: result += c; break;
    }
  }
  return result;
}

template <typename T>
std::string
serialize_multipart_formdata_item_begin(const T &item,
                                        const std::string &boundary) {
  std::string body = "--" + boundary + "\r\n";
  body += "Content-Disposition: form-data; name=\"" +
          escape_multipart_field(item.name) + "\"";
  if (!item.filename.empty()) {
    body += "; filename=\"" + escape_multipart_field(item.filename) + "\"";
  }
  body += "\r\n";
  if (!item.content_type.empty()) {
    body +=
        "Content-Type: " + escape_multipart_field(item.content_type, false) +
        "\r\n";
  }
  body += "\r\n";

  return body;
}

std::string serialize_multipart_formdata_item_end() { return "\r\n"; }

std::string
serialize_multipart_formdata_finish(const std::string &boundary) {
  return "--" + boundary + "--\r\n";
}

std::string
serialize_multipart_formdata_get_content_type(const std::string &boundary) {
  return "multipart/form-data; boundary=" + boundary;
}

std::string
serialize_multipart_formdata(const UploadFormDataItems &items,
                             const std::string &boundary, bool finish = true) {
  std::string body;

  for (const auto &item : items) {
    body += serialize_multipart_formdata_item_begin(item, boundary);
    body += item.content + serialize_multipart_formdata_item_end();
  }

  if (finish) { body += serialize_multipart_formdata_finish(boundary); }

  return body;
}

size_t get_multipart_content_length(const UploadFormDataItems &items,
                                           const std::string &boundary) {
  size_t total = 0;
  for (const auto &item : items) {
    total += serialize_multipart_formdata_item_begin(item, boundary).size();
    total += item.content.size();
    total += serialize_multipart_formdata_item_end().size();
  }
  total += serialize_multipart_formdata_finish(boundary).size();
  return total;
}

struct MultipartSegment {
  const char *data;
  size_t size;
};

// NOTE: items must outlive the returned ContentProvider
//       (safe for synchronous use inside Post/Put/Patch)
ContentProvider
make_multipart_content_provider(const UploadFormDataItems &items,
                                const std::string &boundary) {
  // Own the per-item header strings and the finish string
  std::vector<std::string> owned;
  owned.reserve(items.size() + 1);
  for (const auto &item : items)
    owned.push_back(serialize_multipart_formdata_item_begin(item, boundary));
  owned.push_back(serialize_multipart_formdata_finish(boundary));

  // Flat segment list: [header, content, "\r\n"] * N + [finish]
  std::vector<MultipartSegment> segs;
  segs.reserve(items.size() * 3 + 1);
  static const char crlf[] = "\r\n";
  for (size_t i = 0; i < items.size(); i++) {
    segs.push_back({owned[i].data(), owned[i].size()});
    segs.push_back({items[i].content.data(), items[i].content.size()});
    segs.push_back({crlf, 2});
  }
  segs.push_back({owned.back().data(), owned.back().size()});

  struct MultipartState {
    std::vector<std::string> owned;
    std::vector<MultipartSegment> segs;
    std::vector<char> buf = std::vector<char>(CPPHTTPLIB_SEND_BUFSIZ);
  };
  auto state = std::make_shared<MultipartState>();
  state->owned = std::move(owned);
  // `segs` holds raw pointers into owned strings; std::string move preserves
  // the data pointer, so these pointers remain valid after the move above.
  state->segs = std::move(segs);

  return [state](size_t offset, size_t length, DataSink &sink) -> bool {
    // Buffer multiple small segments into fewer, larger writes to avoid
    // excessive TCP packets when there are many form data items (#2410)
    auto &buf = state->buf;
    auto buf_size = buf.size();
    size_t buf_len = 0;
    size_t remaining = length;

    // Find the first segment containing 'offset'
    size_t pos = 0;
    size_t seg_idx = 0;
    for (; seg_idx < state->segs.size(); seg_idx++) {
      const auto &seg = state->segs[seg_idx];
      if (seg.size > 0 && offset - pos < seg.size) { break; }
      pos += seg.size;
    }

    size_t seg_offset = (seg_idx < state->segs.size()) ? offset - pos : 0;

    for (; seg_idx < state->segs.size() && remaining > 0; seg_idx++) {
      const auto &seg = state->segs[seg_idx];
      size_t available = seg.size - seg_offset;
      size_t to_copy = (std::min)(available, remaining);
      const char *src = seg.data + seg_offset;
      seg_offset = 0; // only the first segment has a non-zero offset

      while (to_copy > 0) {
        size_t space = buf_size - buf_len;
        size_t chunk = (std::min)(to_copy, space);
        std::memcpy(buf.data() + buf_len, src, chunk);
        buf_len += chunk;
        src += chunk;
        to_copy -= chunk;
        remaining -= chunk;

        if (buf_len == buf_size) {
          if (!sink.write(buf.data(), buf_len)) { return false; }
          buf_len = 0;
        }
      }
    }

    if (buf_len > 0) { return sink.write(buf.data(), buf_len); }
    return true;
  };
}

void coalesce_ranges(Ranges &ranges, size_t content_length) {
  if (ranges.size() <= 1) return;

  // Sort ranges by start position
  std::sort(ranges.begin(), ranges.end(),
            [](const Range &a, const Range &b) { return a.first < b.first; });

  Ranges coalesced;
  coalesced.reserve(ranges.size());

  for (auto &r : ranges) {
    auto first_pos = r.first;
    auto last_pos = r.second;

    // Handle special cases like in range_error
    if (first_pos == -1 && last_pos == -1) {
      first_pos = 0;
      last_pos = static_cast<ssize_t>(content_length);
    }

    if (first_pos == -1) {
      first_pos = static_cast<ssize_t>(content_length) - last_pos;
      last_pos = static_cast<ssize_t>(content_length) - 1;
    }

    if (last_pos == -1 || last_pos >= static_cast<ssize_t>(content_length)) {
      last_pos = static_cast<ssize_t>(content_length) - 1;
    }

    // Skip invalid ranges
    if (!(0 <= first_pos && first_pos <= last_pos &&
          last_pos < static_cast<ssize_t>(content_length))) {
      continue;
    }

    // Coalesce with previous range if overlapping or adjacent (but not
    // identical)
    if (!coalesced.empty()) {
      auto &prev = coalesced.back();
      // Check if current range overlaps or is adjacent to previous range
      // but don't coalesce identical ranges (allow duplicates)
      if (first_pos <= prev.second + 1 &&
          !(first_pos == prev.first && last_pos == prev.second)) {
        // Extend the previous range
        prev.second = (std::max)(prev.second, last_pos);
        continue;
      }
    }

    // Add new range
    coalesced.emplace_back(first_pos, last_pos);
  }

  ranges = std::move(coalesced);
}

bool range_error(Request &req, Response &res) {
  if (!req.ranges.empty() && 200 <= res.status && res.status < 300) {
    if (res.body.empty() && res.content_provider_ && res.content_length_ == 0) {
      req.ranges.clear();
      if (res.status == StatusCode::PartialContent_206) {
        res.status = StatusCode::OK_200;
      }
      return false;
    }

    ssize_t content_len = static_cast<ssize_t>(
        res.content_length_ ? res.content_length_ : res.body.size());

    std::vector<std::pair<ssize_t, ssize_t>> processed_ranges;
    size_t overwrapping_count = 0;

    // NOTE: The following Range check is based on '14.2. Range' in RFC 9110
    // 'HTTP Semantics' to avoid potential denial-of-service attacks.
    // https://www.rfc-editor.org/rfc/rfc9110#section-14.2

    // Too many ranges
    if (req.ranges.size() > CPPHTTPLIB_RANGE_MAX_COUNT) { return true; }

    for (auto &r : req.ranges) {
      auto &first_pos = r.first;
      auto &last_pos = r.second;

      if (first_pos == -1 && last_pos == -1) {
        first_pos = 0;
        last_pos = content_len;
      }

      if (first_pos == -1) {
        first_pos = content_len - last_pos;
        last_pos = content_len - 1;
      }

      // NOTE: RFC-9110 '14.1.2. Byte Ranges':
      // A client can limit the number of bytes requested without knowing the
      // size of the selected representation. If the last-pos value is absent,
      // or if the value is greater than or equal to the current length of the
      // representation data, the byte range is interpreted as the remainder of
      // the representation (i.e., the server replaces the value of last-pos
      // with a value that is one less than the current length of the selected
      // representation).
      // https://www.rfc-editor.org/rfc/rfc9110.html#section-14.1.2-6
      if (last_pos == -1 || last_pos >= content_len) {
        last_pos = content_len - 1;
      }

      // Range must be within content length
      if (!(0 <= first_pos && first_pos <= last_pos &&
            last_pos <= content_len - 1)) {
        return true;
      }

      // Request must not have more than two overlapping ranges
      for (const auto &processed_range : processed_ranges) {
        if (!(last_pos < processed_range.first ||
              first_pos > processed_range.second)) {
          overwrapping_count++;
          if (overwrapping_count > 2) { return true; }
          break; // Only count once per range
        }
      }

      processed_ranges.emplace_back(first_pos, last_pos);
    }

    // After validation, coalesce overlapping ranges as per RFC 9110
    coalesce_ranges(req.ranges, static_cast<size_t>(content_len));
  }

  return false;
}

std::pair<size_t, size_t>
get_range_offset_and_length(Range r, size_t content_length) {
  assert(r.first != -1 && r.second != -1);
  assert(0 <= r.first && r.first < static_cast<ssize_t>(content_length));
  assert(r.first <= r.second &&
         r.second < static_cast<ssize_t>(content_length));
  (void)(content_length);
  return std::make_pair(static_cast<size_t>(r.first),
                        static_cast<size_t>(r.second - r.first) + 1);
}

std::string make_content_range_header_field(
    const std::pair<size_t, size_t> &offset_and_length, size_t content_length) {
  auto st = offset_and_length.first;
  auto ed = st + offset_and_length.second - 1;

  std::string field = "bytes ";
  field += std::to_string(st);
  field += '-';
  field += std::to_string(ed);
  field += '/';
  field += std::to_string(content_length);
  return field;
}

template <typename SToken, typename CToken, typename Content>
bool process_multipart_ranges_data(const Request &req,
                                   const std::string &boundary,
                                   const std::string &content_type,
                                   size_t content_length, SToken stoken,
                                   CToken ctoken, Content content) {
  for (size_t i = 0; i < req.ranges.size(); i++) {
    ctoken("--");
    stoken(boundary);
    ctoken("\r\n");
    if (!content_type.empty()) {
      ctoken("Content-Type: ");
      stoken(content_type);
      ctoken("\r\n");
    }

    auto offset_and_length =
        get_range_offset_and_length(req.ranges[i], content_length);

    ctoken("Content-Range: ");
    stoken(make_content_range_header_field(offset_and_length, content_length));
    ctoken("\r\n");
    ctoken("\r\n");

    if (!content(offset_and_length.first, offset_and_length.second)) {
      return false;
    }
    ctoken("\r\n");
  }

  ctoken("--");
  stoken(boundary);
  ctoken("--");

  return true;
}

void make_multipart_ranges_data(const Request &req, Response &res,
                                       const std::string &boundary,
                                       const std::string &content_type,
                                       size_t content_length,
                                       std::string &data) {
  process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { data += token; },
      [&](const std::string &token) { data += token; },
      [&](size_t offset, size_t length) {
        assert(offset + length <= content_length);
        data += res.body.substr(offset, length);
        return true;
      });
}

size_t get_multipart_ranges_data_length(const Request &req,
                                               const std::string &boundary,
                                               const std::string &content_type,
                                               size_t content_length) {
  size_t data_length = 0;

  process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { data_length += token.size(); },
      [&](const std::string &token) { data_length += token.size(); },
      [&](size_t /*offset*/, size_t length) {
        data_length += length;
        return true;
      });

  return data_length;
}

template <typename T>
bool
write_multipart_ranges_data(Stream &strm, const Request &req, Response &res,
                            const std::string &boundary,
                            const std::string &content_type,
                            size_t content_length, const T &is_shutting_down) {
  return process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { strm.write(token); },
      [&](const std::string &token) { strm.write(token); },
      [&](size_t offset, size_t length) {
        return write_content(strm, res.content_provider_, offset, length,
                             is_shutting_down);
      });
}

bool has_framed_body(const Request &req) {
  return is_chunked_transfer_encoding(req.headers) ||
         req.get_header_value_u64("Content-Length") > 0;
}

bool is_connection_persistent(const Request &req) {
  auto conn = req.get_header_value("Connection");
  if (conn == "close") { return false; }
  if (req.version == "HTTP/1.0" && conn != "Keep-Alive") { return false; }
  return true;
}

bool expect_content(const Request &req) {
  if (req.method == "POST" || req.method == "PUT" || req.method == "PATCH" ||
      req.method == "DELETE") {
    return true;
  }
  return has_framed_body(req);
}

#ifdef _WIN32
class WSInit {
public:
  WSInit() {
    WSADATA wsaData;
    if (WSAStartup(0x0002, &wsaData) == 0) is_valid_ = true;
  }

  ~WSInit() {
    if (is_valid_) WSACleanup();
  }

  bool is_valid_ = false;
};

static WSInit wsinit_;
#endif

bool parse_www_authenticate(const Response &res,
                                   std::map<std::string, std::string> &auth,
                                   bool is_proxy) {
  auto auth_key = is_proxy ? "Proxy-Authenticate" : "WWW-Authenticate";
  if (res.has_header(auth_key)) {
    thread_local auto re =
        std::regex(R"~((?:(?:,\s*)?(.+?)=(?:"(.*?)"|([^,]*))))~");
    auto s = res.get_header_value(auth_key);
    auto pos = s.find(' ');
    if (pos != std::string::npos) {
      auto type = s.substr(0, pos);
      if (type == "Basic") {
        return false;
      } else if (type == "Digest") {
        s = s.substr(pos + 1);
        auto beg = std::sregex_iterator(s.begin(), s.end(), re);
        for (auto i = beg; i != std::sregex_iterator(); ++i) {
          const auto &m = *i;
          auto key = s.substr(static_cast<size_t>(m.position(1)),
                              static_cast<size_t>(m.length(1)));
          auto val = m.length(2) > 0
                         ? s.substr(static_cast<size_t>(m.position(2)),
                                    static_cast<size_t>(m.length(2)))
                         : s.substr(static_cast<size_t>(m.position(3)),
                                    static_cast<size_t>(m.length(3)));
          auth[std::move(key)] = std::move(val);
        }
        return true;
      }
    }
  }
  return false;
}

class ContentProviderAdapter {
public:
  explicit ContentProviderAdapter(
      ContentProviderWithoutLength &&content_provider)
      : content_provider_(std::move(content_provider)) {}

  bool operator()(size_t offset, size_t, DataSink &sink) {
    return content_provider_(offset, sink);
  }

private:
  ContentProviderWithoutLength content_provider_;
};

// NOTE: https://www.rfc-editor.org/rfc/rfc9110#section-5
namespace fields {

bool is_token_char(char c) {
  return is_ascii_alnum(c) || c == '!' || c == '#' || c == '$' || c == '%' ||
         c == '&' || c == '\'' || c == '*' || c == '+' || c == '-' ||
         c == '.' || c == '^' || c == '_' || c == '`' || c == '|' || c == '~';
}

bool is_token(const std::string &s) {
  if (s.empty()) { return false; }
  for (auto c : s) {
    if (!is_token_char(c)) { return false; }
  }
  return true;
}

bool is_field_name(const std::string &s) { return is_token(s); }

bool is_vchar(char c) { return c >= 33 && c <= 126; }

bool is_obs_text(char c) { return 128 <= static_cast<unsigned char>(c); }

bool is_field_vchar(char c) { return is_vchar(c) || is_obs_text(c); }

bool is_field_content(const std::string &s) {
  if (s.empty()) { return true; }

  if (s.size() == 1) {
    return is_field_vchar(s[0]);
  } else if (s.size() == 2) {
    return is_field_vchar(s[0]) && is_field_vchar(s[1]);
  } else {
    size_t i = 0;

    if (!is_field_vchar(s[i])) { return false; }
    i++;

    while (i < s.size() - 1) {
      auto c = s[i++];
      if (c == ' ' || c == '\t' || is_field_vchar(c)) {
      } else {
        return false;
      }
    }

    return is_field_vchar(s[i]);
  }
}

bool is_field_value(const std::string &s) { return is_field_content(s); }

bool is_field_valid(const std::string &name, const std::string &value) {
  return is_field_name(name) && is_field_value(value);
}

} // namespace fields

bool perform_websocket_handshake(Stream &strm, const std::string &host,
                                        int port, bool is_ssl,
                                        const std::string &path,
                                        const Headers &headers,
                                        std::string &selected_subprotocol) {
  // Validate path and host
  if (!fields::is_field_value(path) || !fields::is_field_value(host)) {
    return false;
  }

  // Validate user-provided headers
  for (const auto &h : headers) {
    if (!fields::is_field_valid(h.first, h.second)) { return false; }
  }

  // Generate random Sec-WebSocket-Key
  thread_local std::mt19937 rng(std::random_device{}());
  std::string key_bytes(16, '\0');
  for (size_t i = 0; i < 16; i += 4) {
    auto r = rng();
    std::memcpy(&key_bytes[i], &r, (std::min)(size_t(4), size_t(16 - i)));
  }
  auto client_key = base64_encode(key_bytes);

  // Build upgrade request
  std::string req_str = "GET " + path + " HTTP/1.1\r\n";
  req_str += "Host: " + make_host_and_port_string(host, port, is_ssl) + "\r\n";
  req_str += "Upgrade: websocket\r\n";
  req_str += "Connection: Upgrade\r\n";
  req_str += "Sec-WebSocket-Key: " + client_key + "\r\n";
  req_str += "Sec-WebSocket-Version: 13\r\n";
  for (const auto &h : headers) {
    req_str += h.first + ": " + h.second + "\r\n";
  }
  req_str += "\r\n";

  if (strm.write(req_str.data(), req_str.size()) < 0) { return false; }

  // Verify 101 response and Sec-WebSocket-Accept header
  auto expected_accept = websocket_accept_key(client_key);
  return read_websocket_upgrade_response(strm, expected_accept,
                                         selected_subprotocol);
}

} // namespace detail

/*
 * Group 2: detail namespace - SSL common utilities
 */

#ifdef CPPHTTPLIB_SSL_ENABLED
namespace detail {

class SSLSocketStream final : public Stream {
public:
  SSLSocketStream(
      socket_t sock, tls::session_t session, time_t read_timeout_sec,
      time_t read_timeout_usec, time_t write_timeout_sec,
      time_t write_timeout_usec, time_t max_timeout_msec = 0,
      std::chrono::time_point<std::chrono::steady_clock> start_time =
          (std::chrono::steady_clock::time_point::min)());
  ~SSLSocketStream() override;

  bool is_readable() const override;
  bool wait_readable() const override;
  bool wait_writable() const override;
  bool is_peer_alive() const override;
  ssize_t read(char *ptr, size_t size) override;
  ssize_t write(const char *ptr, size_t size) override;
  void get_remote_ip_and_port(std::string &ip, int &port) const override;
  void get_local_ip_and_port(std::string &ip, int &port) const override;
  socket_t socket() const override;
  time_t duration() const override;
  void set_read_timeout(time_t sec, time_t usec = 0) override;

private:
  socket_t sock_;
  tls::session_t session_;
  time_t read_timeout_sec_;
  time_t read_timeout_usec_;
  time_t write_timeout_sec_;
  time_t write_timeout_usec_;
  time_t max_timeout_msec_;
  const std::chrono::time_point<std::chrono::steady_clock> start_time_;
};

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
std::string message_digest(const std::string &s, const EVP_MD *algo) {
  auto context = std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)>(
      EVP_MD_CTX_new(), EVP_MD_CTX_free);

  unsigned int hash_length = 0;
  unsigned char hash[EVP_MAX_MD_SIZE];

  EVP_DigestInit_ex(context.get(), algo, nullptr);
  EVP_DigestUpdate(context.get(), s.c_str(), s.size());
  EVP_DigestFinal_ex(context.get(), hash, &hash_length);

  std::stringstream ss;
  for (auto i = 0u; i < hash_length; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }

  return ss.str();
}

std::string MD5(const std::string &s) {
  return message_digest(s, EVP_md5());
}

std::string SHA_256(const std::string &s) {
  return message_digest(s, EVP_sha256());
}

std::string SHA_512(const std::string &s) {
  return message_digest(s, EVP_sha512());
}
#elif defined(CPPHTTPLIB_MBEDTLS_SUPPORT)
namespace {
template <size_t N>
std::string hash_to_hex(const unsigned char (&hash)[N]) {
  std::stringstream ss;
  for (size_t i = 0; i < N; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }
  return ss.str();
}
} // namespace

#ifdef CPPHTTPLIB_MBEDTLS_V4
// Mbed TLS 4.x provides hashing (and TLS RNG) via PSA Crypto, which must be
// initialized once. PSA state is process-global; do not free it.
bool ensure_mbedtls_psa_crypto() {
  static std::once_flag once;
  static bool ok = false;
  std::call_once(once, []() { ok = (psa_crypto_init() == PSA_SUCCESS); });
  return ok;
}

bool psa_hash(psa_algorithm_t alg, const std::string &s,
                     unsigned char *out, size_t out_size) {
  if (!ensure_mbedtls_psa_crypto()) { return false; }
  size_t olen = 0;
  return psa_hash_compute(alg, reinterpret_cast<const uint8_t *>(s.data()),
                          s.size(), out, out_size, &olen) == PSA_SUCCESS &&
         olen == out_size;
}
#endif

std::string MD5(const std::string &s) {
  unsigned char hash[16];
#ifdef CPPHTTPLIB_MBEDTLS_V4
  if (!psa_hash(PSA_ALG_MD5, s, hash, sizeof(hash))) { return {}; }
#elif defined(CPPHTTPLIB_MBEDTLS_V3)
  mbedtls_md5(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
              hash);
#else
  mbedtls_md5_ret(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                  hash);
#endif
  return hash_to_hex(hash);
}

std::string SHA_256(const std::string &s) {
  unsigned char hash[32];
#ifdef CPPHTTPLIB_MBEDTLS_V4
  if (!psa_hash(PSA_ALG_SHA_256, s, hash, sizeof(hash))) { return {}; }
#elif defined(CPPHTTPLIB_MBEDTLS_V3)
  mbedtls_sha256(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                 hash, 0);
#else
  mbedtls_sha256_ret(reinterpret_cast<const unsigned char *>(s.c_str()),
                     s.size(), hash, 0);
#endif
  return hash_to_hex(hash);
}

std::string SHA_512(const std::string &s) {
  unsigned char hash[64];
#ifdef CPPHTTPLIB_MBEDTLS_V4
  if (!psa_hash(PSA_ALG_SHA_512, s, hash, sizeof(hash))) { return {}; }
#elif defined(CPPHTTPLIB_MBEDTLS_V3)
  mbedtls_sha512(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                 hash, 0);
#else
  mbedtls_sha512_ret(reinterpret_cast<const unsigned char *>(s.c_str()),
                     s.size(), hash, 0);
#endif
  return hash_to_hex(hash);
}
#elif defined(CPPHTTPLIB_WOLFSSL_SUPPORT)
namespace {
template <size_t N>
std::string hash_to_hex(const unsigned char (&hash)[N]) {
  std::stringstream ss;
  for (size_t i = 0; i < N; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }
  return ss.str();
}
} // namespace

std::string MD5(const std::string &s) {
  unsigned char hash[WC_MD5_DIGEST_SIZE];
  wc_Md5Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
             static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}

std::string SHA_256(const std::string &s) {
  unsigned char hash[WC_SHA256_DIGEST_SIZE];
  wc_Sha256Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
                static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}

std::string SHA_512(const std::string &s) {
  unsigned char hash[WC_SHA512_DIGEST_SIZE];
  wc_Sha512Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
                static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}
#endif

bool is_ip_address(const std::string &host) {
  struct in_addr addr4;
  struct in6_addr addr6;
  return inet_pton(AF_INET, host.c_str(), &addr4) == 1 ||
         inet_pton(AF_INET6, host.c_str(), &addr6) == 1;
}

template <typename T>
bool process_server_socket_ssl(
    const std::atomic<socket_t> &svr_sock, tls::session_t session,
    socket_t sock, size_t keep_alive_max_count, time_t keep_alive_timeout_sec,
    time_t read_timeout_sec, time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, T callback) {
  return process_server_socket_core(
      svr_sock, sock, keep_alive_max_count, keep_alive_timeout_sec,
      [&](bool close_connection, bool &connection_closed) {
        SSLSocketStream strm(sock, session, read_timeout_sec, read_timeout_usec,
                             write_timeout_sec, write_timeout_usec);
        return callback(strm, close_connection, connection_closed);
      });
}

template <typename T>
bool process_client_socket_ssl(
    tls::session_t session, socket_t sock, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time, T callback) {
  SSLSocketStream strm(sock, session, read_timeout_sec, read_timeout_usec,
                       write_timeout_sec, write_timeout_usec, max_timeout_msec,
                       start_time);
  return callback(strm);
}

std::pair<std::string, std::string> make_digest_authentication_header(
    const Request &req, const std::map<std::string, std::string> &auth,
    size_t cnonce_count, const std::string &cnonce, const std::string &username,
    const std::string &password, bool is_proxy = false) {
  std::string nc;
  {
    std::stringstream ss;
    ss << std::setfill('0') << std::setw(8) << std::hex << cnonce_count;
    nc = ss.str();
  }

  std::string qop;
  if (auth.find("qop") != auth.end()) {
    qop = auth.at("qop");
    if (qop.find("auth-int") != std::string::npos) {
      qop = "auth-int";
    } else if (qop.find("auth") != std::string::npos) {
      qop = "auth";
    } else {
      qop.clear();
    }
  }

  std::string algo = "MD5";
  if (auth.find("algorithm") != auth.end()) { algo = auth.at("algorithm"); }

  std::string response;
  {
    auto H = algo == "SHA-256"   ? detail::SHA_256
             : algo == "SHA-512" ? detail::SHA_512
                                 : detail::MD5;

    auto A1 = username + ":" + auth.at("realm") + ":" + password;

    auto A2 = req.method + ":" + req.path;
    if (qop == "auth-int") { A2 += ":" + H(req.body); }

    if (qop.empty()) {
      response = H(H(A1) + ":" + auth.at("nonce") + ":" + H(A2));
    } else {
      response = H(H(A1) + ":" + auth.at("nonce") + ":" + nc + ":" + cnonce +
                   ":" + qop + ":" + H(A2));
    }
  }

  auto opaque = (auth.find("opaque") != auth.end()) ? auth.at("opaque") : "";

  auto field = "Digest username=\"" + username + "\", realm=\"" +
               auth.at("realm") + "\", nonce=\"" + auth.at("nonce") +
               "\", uri=\"" + req.path + "\", algorithm=" + algo +
               (qop.empty() ? ", response=\""
                            : ", qop=" + qop + ", nc=" + nc + ", cnonce=\"" +
                                  cnonce + "\", response=\"") +
               response + "\"" +
               (opaque.empty() ? "" : ", opaque=\"" + opaque + "\"");

  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, field);
}

bool match_hostname(const std::string &pattern,
                           const std::string &hostname) {
  // Exact match (case-insensitive)
  if (detail::case_ignore::equal(hostname, pattern)) { return true; }

  // Split both pattern and hostname into components by '.'
  std::vector<std::string> pattern_components;
  if (!pattern.empty()) {
    split(pattern.data(), pattern.data() + pattern.size(), '.',
          [&](const char *b, const char *e) {
            pattern_components.emplace_back(b, e);
          });
  }

  std::vector<std::string> host_components;
  if (!hostname.empty()) {
    split(hostname.data(), hostname.data() + hostname.size(), '.',
          [&](const char *b, const char *e) {
            host_components.emplace_back(b, e);
          });
  }

  // Component count must match
  if (host_components.size() != pattern_components.size()) { return false; }

  // Compare each component with wildcard support
  // Supports: "*" (full wildcard), "prefix*" (partial wildcard)
  // https://bugs.launchpad.net/ubuntu/+source/firefox-3.0/+bug/376484
  auto itr = pattern_components.begin();
  for (const auto &h : host_components) {
    auto &p = *itr;
    if (!detail::case_ignore::equal(p, h) && p != "*") {
      bool partial_match = false;
      if (!p.empty() && p[p.size() - 1] == '*') {
        const auto prefix_length = p.size() - 1;
        if (prefix_length == 0) {
          partial_match = true;
        } else if (h.size() >= prefix_length) {
          partial_match =
              std::equal(p.begin(),
                         p.begin() + static_cast<std::string::difference_type>(
                                         prefix_length),
                         h.begin(), [](const char ca, const char cb) {
                           return detail::case_ignore::to_lower(ca) ==
                                  detail::case_ignore::to_lower(cb);
                         });
        }
      }
      if (!partial_match) { return false; }
    }
    ++itr;
  }

  return true;
}

#ifdef _WIN32
// Verify certificate using Windows CertGetCertificateChain API.
// This provides real-time certificate validation with Windows Update
// integration, independent of the TLS backend (OpenSSL or MbedTLS).
bool
verify_cert_with_windows_schannel(const std::vector<unsigned char> &der_cert,
                                  const std::string &hostname,
                                  bool verify_hostname, uint64_t &out_error) {
  if (der_cert.empty()) { return false; }

  out_error = 0;

  // Create Windows certificate context from DER data
  auto cert_context = CertCreateCertificateContext(
      X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, der_cert.data(),
      static_cast<DWORD>(der_cert.size()));

  if (!cert_context) {
    out_error = GetLastError();
    return false;
  }

  auto cert_guard =
      scope_exit([&] { CertFreeCertificateContext(cert_context); });

  // Setup chain parameters
  CERT_CHAIN_PARA chain_para = {};
  chain_para.cbSize = sizeof(chain_para);

  // Build certificate chain with revocation checking
  PCCERT_CHAIN_CONTEXT chain_context = nullptr;
  auto chain_result = CertGetCertificateChain(
      nullptr, cert_context, nullptr, cert_context->hCertStore, &chain_para,
      CERT_CHAIN_CACHE_END_CERT | CERT_CHAIN_REVOCATION_CHECK_END_CERT |
          CERT_CHAIN_REVOCATION_ACCUMULATIVE_TIMEOUT,
      nullptr, &chain_context);

  if (!chain_result || !chain_context) {
    out_error = GetLastError();
    return false;
  }

  auto chain_guard =
      scope_exit([&] { CertFreeCertificateChain(chain_context); });

  // Check if chain has errors
  if (chain_context->TrustStatus.dwErrorStatus != CERT_TRUST_NO_ERROR) {
    out_error = chain_context->TrustStatus.dwErrorStatus;
    return false;
  }

  // Verify SSL policy
  SSL_EXTRA_CERT_CHAIN_POLICY_PARA extra_policy_para = {};
  extra_policy_para.cbSize = sizeof(extra_policy_para);
#ifdef AUTHTYPE_SERVER
  extra_policy_para.dwAuthType = AUTHTYPE_SERVER;
#endif

  std::wstring whost;
  if (verify_hostname) {
    whost = u8string_to_wstring(hostname.c_str());
    extra_policy_para.pwszServerName = const_cast<wchar_t *>(whost.c_str());
  }

  CERT_CHAIN_POLICY_PARA policy_para = {};
  policy_para.cbSize = sizeof(policy_para);
#ifdef CERT_CHAIN_POLICY_IGNORE_ALL_REV_UNKNOWN_FLAGS
  policy_para.dwFlags = CERT_CHAIN_POLICY_IGNORE_ALL_REV_UNKNOWN_FLAGS;
#else
  policy_para.dwFlags = 0;
#endif
  policy_para.pvExtraPolicyPara = &extra_policy_para;

  CERT_CHAIN_POLICY_STATUS policy_status = {};
  policy_status.cbSize = sizeof(policy_status);

  if (!CertVerifyCertificateChainPolicy(CERT_CHAIN_POLICY_SSL, chain_context,
                                        &policy_para, &policy_status)) {
    out_error = GetLastError();
    return false;
  }

  if (policy_status.dwError != 0) {
    out_error = policy_status.dwError;
    return false;
  }

  return true;
}
#endif // _WIN32

// Loads CA file/dir configuration and applies the system CA policy to a
// client TLS context. PEM data and native stores are applied to the context
// directly at set time; has_custom_store reflects them for the Auto policy
// decision.
bool load_client_ca_config(tls::ctx_t ctx,
                                  const std::string &ca_cert_file_path,
                                  const std::string &ca_cert_dir_path,
                                  bool has_custom_store, SystemCAMode mode,
                                  uint64_t &backend_error) {
  auto ret = true;

  if (!ca_cert_file_path.empty()) {
    if (!tls::load_ca_file(ctx, ca_cert_file_path.c_str())) {
      backend_error = tls::get_error();
      ret = false;
    }
  } else if (!ca_cert_dir_path.empty()) {
    if (!tls::load_ca_dir(ctx, ca_cert_dir_path.c_str())) {
      backend_error = tls::get_error();
      ret = false;
    }
  }

  auto has_custom_ca = !ca_cert_file_path.empty() ||
                       !ca_cert_dir_path.empty() || has_custom_store;
  if (mode == SystemCAMode::Enabled ||
      (mode == SystemCAMode::Auto && !has_custom_ca)) {
    if (!tls::load_system_certs(ctx)) { backend_error = tls::get_error(); }
  }

  return ret;
}

bool setup_client_tls_session(const std::string &host, tls::ctx_t ctx,
                                     tls::session_t &session, socket_t sock,
                                     bool server_certificate_verification,
                                     time_t timeout_sec, time_t timeout_usec) {
  using namespace tls;

  if (!ctx) { return false; }

  bool is_ip = is_ip_address(host);

#if defined(CPPHTTPLIB_MBEDTLS_SUPPORT) || defined(CPPHTTPLIB_WOLFSSL_SUPPORT)
  // Chain verification happens during the handshake even for IP hosts; the
  // certificate identity is verified post-handshake via verify_hostname()
  set_verify_client(ctx, server_certificate_verification);
#endif

  session = create_session(ctx, sock);
  if (!session) { return false; }

  // RFC 6066: SNI must not be set for IP addresses. On Mbed TLS and wolfSSL
  // set_hostname also sets SNI, so it must be skipped for IP hosts as well;
  // their identity is checked post-handshake below instead.
  if (!is_ip) {
    if (server_certificate_verification) {
      set_hostname(session, host.c_str());
    } else {
      set_sni(session, host.c_str());
    }
  }

  if (!connect_nonblocking(session, sock, timeout_sec, timeout_usec, nullptr)) {
    return false;
  }

  if (server_certificate_verification) {
    if (get_verify_result(session) != 0) { return false; }

    // Identity check against the peer certificate, post-handshake for all
    // backends (same as SSLClient). For IP hosts this is the only identity
    // verification since no hostname is bound during the handshake.
    auto server_cert = get_peer_cert(session);
    if (!server_cert) { return false; }
    auto cert_guard = detail::scope_exit([&] { free_cert(server_cert); });
    if (!verify_hostname(server_cert, host.c_str())) { return false; }
  }

  return true;
}

} // namespace detail
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 3: httplib namespace - Non-SSL public API implementations
 */

void default_socket_options(socket_t sock) {
  set_socket_opt(sock, SOL_SOCKET,
#ifdef SO_REUSEPORT
                 SO_REUSEPORT,
#else
                 SO_REUSEADDR,
#endif
                 1);
}

bool set_socket_opt(socket_t sock, int level, int optname, int optval) {
  return detail::set_socket_opt_impl(sock, level, optname, &optval,
                                     sizeof(optval));
}

std::string get_bearer_token_auth(const Request &req) {
  if (req.has_header("Authorization")) {
    constexpr auto bearer_header_prefix_len = detail::str_len("Bearer ");
    return req.get_header_value("Authorization")
        .substr(bearer_header_prefix_len);
  }
  return "";
}

const char *status_message(int status) {
  switch (status) {
  case StatusCode::Continue_100: return "Continue";
  case StatusCode::SwitchingProtocol_101: return "Switching Protocol";
  case StatusCode::Processing_102: return "Processing";
  case StatusCode::EarlyHints_103: return "Early Hints";
  case StatusCode::OK_200: return "OK";
  case StatusCode::Created_201: return "Created";
  case StatusCode::Accepted_202: return "Accepted";
  case StatusCode::NonAuthoritativeInformation_203:
    return "Non-Authoritative Information";
  case StatusCode::NoContent_204: return "No Content";
  case StatusCode::ResetContent_205: return "Reset Content";
  case StatusCode::PartialContent_206: return "Partial Content";
  case StatusCode::MultiStatus_207: return "Multi-Status";
  case StatusCode::AlreadyReported_208: return "Already Reported";
  case StatusCode::IMUsed_226: return "IM Used";
  case StatusCode::MultipleChoices_300: return "Multiple Choices";
  case StatusCode::MovedPermanently_301: return "Moved Permanently";
  case StatusCode::Found_302: return "Found";
  case StatusCode::SeeOther_303: return "See Other";
  case StatusCode::NotModified_304: return "Not Modified";
  case StatusCode::UseProxy_305: return "Use Proxy";
  case StatusCode::unused_306: return "unused";
  case StatusCode::TemporaryRedirect_307: return "Temporary Redirect";
  case StatusCode::PermanentRedirect_308: return "Permanent Redirect";
  case StatusCode::BadRequest_400: return "Bad Request";
  case StatusCode::Unauthorized_401: return "Unauthorized";
  case StatusCode::PaymentRequired_402: return "Payment Required";
  case StatusCode::Forbidden_403: return "Forbidden";
  case StatusCode::NotFound_404: return "Not Found";
  case StatusCode::MethodNotAllowed_405: return "Method Not Allowed";
  case StatusCode::NotAcceptable_406: return "Not Acceptable";
  case StatusCode::ProxyAuthenticationRequired_407:
    return "Proxy Authentication Required";
  case StatusCode::RequestTimeout_408: return "Request Timeout";
  case StatusCode::Conflict_409: return "Conflict";
  case StatusCode::Gone_410: return "Gone";
  case StatusCode::LengthRequired_411: return "Length Required";
  case StatusCode::PreconditionFailed_412: return "Precondition Failed";
  case StatusCode::PayloadTooLarge_413: return "Payload Too Large";
  case StatusCode::UriTooLong_414: return "URI Too Long";
  case StatusCode::UnsupportedMediaType_415: return "Unsupported Media Type";
  case StatusCode::RangeNotSatisfiable_416: return "Range Not Satisfiable";
  case StatusCode::ExpectationFailed_417: return "Expectation Failed";
  case StatusCode::ImATeapot_418: return "I'm a teapot";
  case StatusCode::MisdirectedRequest_421: return "Misdirected Request";
  case StatusCode::UnprocessableContent_422: return "Unprocessable Content";
  case StatusCode::Locked_423: return "Locked";
  case StatusCode::FailedDependency_424: return "Failed Dependency";
  case StatusCode::TooEarly_425: return "Too Early";
  case StatusCode::UpgradeRequired_426: return "Upgrade Required";
  case StatusCode::PreconditionRequired_428: return "Precondition Required";
  case StatusCode::TooManyRequests_429: return "Too Many Requests";
  case StatusCode::RequestHeaderFieldsTooLarge_431:
    return "Request Header Fields Too Large";
  case StatusCode::UnavailableForLegalReasons_451:
    return "Unavailable For Legal Reasons";
  case StatusCode::NotImplemented_501: return "Not Implemented";
  case StatusCode::BadGateway_502: return "Bad Gateway";
  case StatusCode::ServiceUnavailable_503: return "Service Unavailable";
  case StatusCode::GatewayTimeout_504: return "Gateway Timeout";
  case StatusCode::HttpVersionNotSupported_505:
    return "HTTP Version Not Supported";
  case StatusCode::VariantAlsoNegotiates_506: return "Variant Also Negotiates";
  case StatusCode::InsufficientStorage_507: return "Insufficient Storage";
  case StatusCode::LoopDetected_508: return "Loop Detected";
  case StatusCode::NotExtended_510: return "Not Extended";
  case StatusCode::NetworkAuthenticationRequired_511:
    return "Network Authentication Required";

  default:
  case StatusCode::InternalServerError_500: return "Internal Server Error";
  }
}

std::string to_string(const Error error) {
  switch (error) {
  case Error::Success: return "Success (no error)";
  case Error::Unknown: return "Unknown";
  case Error::Connection: return "Could not establish connection";
  case Error::BindIPAddress: return "Failed to bind IP address";
  case Error::Read: return "Failed to read connection";
  case Error::Write: return "Failed to write connection";
  case Error::ExceedRedirectCount: return "Maximum redirect count exceeded";
  case Error::Canceled: return "Connection handling canceled";
  case Error::SSLConnection: return "SSL connection failed";
  case Error::SSLLoadingCerts: return "SSL certificate loading failed";
  case Error::SSLServerVerification: return "SSL server verification failed";
  case Error::SSLServerHostnameVerification:
    return "SSL server hostname verification failed";
  case Error::UnsupportedMultipartBoundaryChars:
    return "Unsupported HTTP multipart boundary characters";
  case Error::Compression: return "Compression failed";
  case Error::ConnectionTimeout: return "Connection timed out";
  case Error::ProxyConnection: return "Proxy connection failed";
  case Error::ConnectionClosed: return "Connection closed by server";
  case Error::Timeout: return "Read timeout";
  case Error::ResourceExhaustion: return "Resource exhaustion";
  case Error::TooManyFormDataFiles: return "Too many form data files";
  case Error::ExceedMaxPayloadSize: return "Exceeded maximum payload size";
  case Error::ExceedUriMaxLength: return "Exceeded maximum URI length";
  case Error::ExceedMaxSocketDescriptorCount:
    return "Exceeded maximum socket descriptor count";
  case Error::InvalidRequestLine: return "Invalid request line";
  case Error::InvalidHTTPMethod: return "Invalid HTTP method";
  case Error::InvalidHTTPVersion: return "Invalid HTTP version";
  case Error::InvalidHeaders: return "Invalid headers";
  case Error::MultipartParsing: return "Multipart parsing failed";
  case Error::OpenFile: return "Failed to open file";
  case Error::Listen: return "Failed to listen on socket";
  case Error::GetSockName: return "Failed to get socket name";
  case Error::UnsupportedAddressFamily: return "Unsupported address family";
  case Error::HTTPParsing: return "HTTP parsing failed";
  case Error::InvalidRangeHeader: return "Invalid Range header";
  default: break;
  }

  return "Invalid";
}

std::ostream &operator<<(std::ostream &os, const Error &obj) {
  os << to_string(obj);
  os << " (" << static_cast<std::underlying_type<Error>::type>(obj) << ')';
  return os;
}

std::string hosted_at(const std::string &hostname) {
  std::vector<std::string> addrs;
  hosted_at(hostname, addrs);
  if (addrs.empty()) { return std::string(); }
  return addrs[0];
}

void hosted_at(const std::string &hostname,
                      std::vector<std::string> &addrs) {
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_family = AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;

  if (detail::getaddrinfo_with_timeout(hostname.c_str(), nullptr, &hints,
                                       &result, 0)) {
#if defined __linux__ && !defined __ANDROID__
    res_init();
#endif
    return;
  }
  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  for (auto rp = result; rp; rp = rp->ai_next) {
    const auto &addr =
        *reinterpret_cast<struct sockaddr_storage *>(rp->ai_addr);
    std::string ip;
    auto dummy = -1;
    if (detail::get_ip_and_port(addr, sizeof(struct sockaddr_storage), ip,
                                dummy)) {
      addrs.emplace_back(std::move(ip));
    }
  }
}

std::string encode_uri_component(const std::string &value) {
  std::ostringstream escaped;
  escaped.fill('0');
  escaped << std::hex;

  for (auto c : value) {
    if (detail::is_ascii_alnum(c) || c == '-' || c == '_' || c == '.' ||
        c == '!' || c == '~' || c == '*' || c == '\'' || c == '(' || c == ')') {
      escaped << c;
    } else {
      escaped << std::uppercase;
      escaped << '%' << std::setw(2)
              << static_cast<int>(static_cast<unsigned char>(c));
      escaped << std::nouppercase;
    }
  }

  return escaped.str();
}

std::string encode_uri(const std::string &value) {
  std::ostringstream escaped;
  escaped.fill('0');
  escaped << std::hex;

  for (auto c : value) {
    if (detail::is_ascii_alnum(c) || c == '-' || c == '_' || c == '.' ||
        c == '!' || c == '~' || c == '*' || c == '\'' || c == '(' || c == ')' ||
        c == ';' || c == '/' || c == '?' || c == ':' || c == '@' || c == '&' ||
        c == '=' || c == '+' || c == '$' || c == ',' || c == '#') {
      escaped << c;
    } else {
      escaped << std::uppercase;
      escaped << '%' << std::setw(2)
              << static_cast<int>(static_cast<unsigned char>(c));
      escaped << std::nouppercase;
    }
  }

  return escaped.str();
}

std::string decode_uri_component(const std::string &value) {
  std::string result;

  for (size_t i = 0; i < value.size(); i++) {
    if (value[i] == '%' && i + 2 < value.size()) {
      auto val = 0;
      if (detail::from_hex_to_i(value, i + 1, 2, val)) {
        result += static_cast<char>(val);
        i += 2;
      } else {
        result += value[i];
      }
    } else {
      result += value[i];
    }
  }

  return result;
}

std::string decode_uri(const std::string &value) {
  std::string result;

  for (size_t i = 0; i < value.size(); i++) {
    if (value[i] == '%' && i + 2 < value.size()) {
      auto val = 0;
      if (detail::from_hex_to_i(value, i + 1, 2, val)) {
        result += static_cast<char>(val);
        i += 2;
      } else {
        result += value[i];
      }
    } else {
      result += value[i];
    }
  }

  return result;
}

std::string encode_path_component(const std::string &component) {
  std::string result;
  result.reserve(component.size() * 3);

  for (size_t i = 0; i < component.size(); i++) {
    auto c = static_cast<unsigned char>(component[i]);

    // Unreserved characters per RFC 3986: ALPHA / DIGIT / "-" / "." / "_" / "~"
    if (detail::is_ascii_alnum(static_cast<char>(c)) || c == '-' || c == '.' ||
        c == '_' || c == '~') {
      result += static_cast<char>(c);
    }
    // Path-safe sub-delimiters: "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" /
    // "," / ";" / "="
    else if (c == '!' || c == '$' || c == '&' || c == '\'' || c == '(' ||
             c == ')' || c == '*' || c == '+' || c == ',' || c == ';' ||
             c == '=') {
      result += static_cast<char>(c);
    }
    // Colon is allowed in path segments except first segment
    else if (c == ':') {
      result += static_cast<char>(c);
    }
    // @ is allowed in path
    else if (c == '@') {
      result += static_cast<char>(c);
    } else {
      result += '%';
      char hex[3];
      snprintf(hex, sizeof(hex), "%02X", c);
      result.append(hex, 2);
    }
  }
  return result;
}

std::string decode_path_component(const std::string &component) {
  std::string result;
  result.reserve(component.size());

  for (size_t i = 0; i < component.size(); i++) {
    if (component[i] == '%' && i + 1 < component.size()) {
      if (component[i + 1] == 'u') {
        // Unicode %uXXXX encoding
        auto val = 0;
        if (detail::from_hex_to_i(component, i + 2, 4, val)) {
          // 4 digits Unicode codes: val is 0x0000-0xFFFF (from 4 hex digits),
          // so to_utf8 writes at most 3 bytes. buff[4] is safe.
          char buff[4];
          size_t len = detail::to_utf8(val, buff);
          if (len > 0) { result.append(buff, len); }
          i += 5; // 'u0000'
        } else {
          result += component[i];
        }
      } else {
        // Standard %XX encoding
        auto val = 0;
        if (detail::from_hex_to_i(component, i + 1, 2, val)) {
          // 2 digits hex codes
          result += static_cast<char>(val);
          i += 2; // 'XX'
        } else {
          result += component[i];
        }
      }
    } else {
      result += component[i];
    }
  }
  return result;
}

std::string encode_query_component(const std::string &component,
                                          bool space_as_plus) {
  std::string result;
  result.reserve(component.size() * 3);

  for (size_t i = 0; i < component.size(); i++) {
    auto c = static_cast<unsigned char>(component[i]);

    // Unreserved characters per RFC 3986
    if (detail::is_ascii_alnum(static_cast<char>(c)) || c == '-' || c == '.' ||
        c == '_' || c == '~') {
      result += static_cast<char>(c);
    }
    // Space handling
    else if (c == ' ') {
      if (space_as_plus) {
        result += '+';
      } else {
        result += "%20";
      }
    }
    // Plus sign handling
    else if (c == '+') {
      if (space_as_plus) {
        result += "%2B";
      } else {
        result += static_cast<char>(c);
      }
    }
    // Query-safe sub-delimiters (excluding & and = which are query delimiters)
    else if (c == '!' || c == '$' || c == '\'' || c == '(' || c == ')' ||
             c == '*' || c == ',' || c == ';') {
      result += static_cast<char>(c);
    }
    // Colon and @ are allowed in query
    else if (c == ':' || c == '@') {
      result += static_cast<char>(c);
    }
    // Forward slash is allowed in query values
    else if (c == '/') {
      result += static_cast<char>(c);
    }
    // Question mark is allowed in query values (after first ?)
    else if (c == '?') {
      result += static_cast<char>(c);
    } else {
      result += '%';
      char hex[3];
      snprintf(hex, sizeof(hex), "%02X", c);
      result.append(hex, 2);
    }
  }
  return result;
}

std::string decode_query_component(const std::string &component,
                                          bool plus_as_space) {
  std::string result;
  result.reserve(component.size());

  for (size_t i = 0; i < component.size(); i++) {
    if (component[i] == '%' && i + 2 < component.size()) {
      auto val = 0;
      if (detail::from_hex_to_i(component, i + 1, 2, val)) {
        result += static_cast<char>(val);
        i += 2;
      } else {
        result += component[i];
      }
    } else if (component[i] == '+' && plus_as_space) {
      result += ' '; // + becomes space in form-urlencoded
    } else {
      result += component[i];
    }
  }
  return result;
}

std::string sanitize_filename(const std::string &filename) {
  // Extract basename: find the last path separator (/ or \)
  auto pos = filename.find_last_of("/\\");
  auto result =
      (pos != std::string::npos) ? filename.substr(pos + 1) : filename;

  // Strip null bytes
  result.erase(std::remove(result.begin(), result.end(), '\0'), result.end());

  // Trim whitespace
  {
    auto start = result.find_first_not_of(" \t");
    auto end = result.find_last_not_of(" \t");
    result = (start == std::string::npos)
                 ? ""
                 : result.substr(start, end - start + 1);
  }

  // Reject . and ..
  if (result == "." || result == "..") { return ""; }

  return result;
}

std::string append_query_params(const std::string &path,
                                       const Params &params) {
  std::string path_with_query = path;
  thread_local const std::regex re("[^?]+\\?.*");
  auto delm = std::regex_match(path, re) ? '&' : '?';
  path_with_query += delm + detail::params_to_query_str(params);
  return path_with_query;
}

// Header utilities
std::pair<std::string, std::string>
make_range_header(const Ranges &ranges) {
  std::string field = "bytes=";
  auto i = 0;
  for (const auto &r : ranges) {
    if (i != 0) { field += ", "; }
    if (r.first != -1) { field += std::to_string(r.first); }
    field += '-';
    if (r.second != -1) { field += std::to_string(r.second); }
    i++;
  }
  return std::make_pair("Range", std::move(field));
}

std::pair<std::string, std::string>
make_basic_authentication_header(const std::string &username,
                                 const std::string &password, bool is_proxy) {
  auto field = "Basic " + detail::base64_encode(username + ":" + password);
  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, std::move(field));
}

std::pair<std::string, std::string>
make_bearer_token_authentication_header(const std::string &token,
                                        bool is_proxy = false) {
  auto field = "Bearer " + token;
  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, std::move(field));
}

// Request implementation
size_t Request::get_header_value_u64(const std::string &key, size_t def,
                                            size_t id) const {
  return detail::get_header_value_u64(headers, key, def, id);
}

bool Request::has_header(const std::string &key) const {
  return detail::has_header(headers, key);
}

std::string Request::get_header_value(const std::string &key,
                                             const char *def, size_t id) const {
  return detail::get_header_value(headers, key, def, id);
}

size_t Request::get_header_value_count(const std::string &key) const {
  return detail::get_header_value_count(headers, key);
}

void Request::set_header(const std::string &key,
                                const std::string &val) {
  detail::set_header(headers, key, val);
}

bool Request::has_trailer(const std::string &key) const {
  return trailers.find(key) != trailers.end();
}

std::string Request::get_trailer_value(const std::string &key,
                                              size_t id) const {
  return detail::get_multimap_value(trailers, key, id);
}

size_t Request::get_trailer_value_count(const std::string &key) const {
  auto r = trailers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

bool Request::has_param(const std::string &key) const {
  return params.find(key) != params.end();
}

std::string Request::get_param_value(const std::string &key,
                                            size_t id) const {
  return detail::get_multimap_value(params, key, id);
}

std::vector<std::string>
Request::get_param_values(const std::string &key) const {
  auto rng = params.equal_range(key);
  std::vector<std::string> values;
  values.reserve(static_cast<size_t>(std::distance(rng.first, rng.second)));
  for (auto it = rng.first; it != rng.second; ++it) {
    values.push_back(it->second);
  }
  return values;
}

size_t Request::get_param_value_count(const std::string &key) const {
  auto r = params.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

bool Request::is_multipart_form_data() const {
  const auto &content_type = get_header_value("Content-Type");
  return detail::extract_media_type(content_type) == "multipart/form-data";
}

// Multipart FormData implementation
std::string MultipartFormData::get_field(const std::string &key,
                                                size_t id) const {
  auto rng = fields.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second.content; }
  return std::string();
}

std::vector<std::string>
MultipartFormData::get_fields(const std::string &key) const {
  std::vector<std::string> values;
  auto rng = fields.equal_range(key);
  for (auto it = rng.first; it != rng.second; it++) {
    values.push_back(it->second.content);
  }
  return values;
}

bool MultipartFormData::has_field(const std::string &key) const {
  return fields.find(key) != fields.end();
}

size_t MultipartFormData::get_field_count(const std::string &key) const {
  auto r = fields.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

FormData MultipartFormData::get_file(const std::string &key,
                                            size_t id) const {
  return detail::get_multimap_value(files, key, id);
}

std::vector<FormData>
MultipartFormData::get_files(const std::string &key) const {
  std::vector<FormData> values;
  auto rng = files.equal_range(key);
  for (auto it = rng.first; it != rng.second; it++) {
    values.push_back(it->second);
  }
  return values;
}

bool MultipartFormData::has_file(const std::string &key) const {
  return files.find(key) != files.end();
}

size_t MultipartFormData::get_file_count(const std::string &key) const {
  auto r = files.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

// Multipart FormData writer implementation
bool is_valid_multipart_boundary(const std::string &boundary) {
  return detail::is_multipart_boundary_chars_valid(boundary);
}

MultipartFormDataWriter::MultipartFormDataWriter()
    : boundary_(detail::make_multipart_data_boundary()) {}

MultipartFormDataWriter::MultipartFormDataWriter(std::string boundary)
    : boundary_(std::move(boundary)) {}

const std::string &MultipartFormDataWriter::boundary() const {
  return boundary_;
}

std::string MultipartFormDataWriter::content_type() const {
  return detail::serialize_multipart_formdata_get_content_type(boundary_);
}

std::string
MultipartFormDataWriter::serialize(const UploadFormDataItems &items) const {
  return detail::serialize_multipart_formdata(items, boundary_);
}

size_t MultipartFormDataWriter::content_length(
    const UploadFormDataItems &items) const {
  return detail::get_multipart_content_length(items, boundary_);
}

std::string
MultipartFormDataWriter::item_begin(const UploadFormData &item) const {
  return detail::serialize_multipart_formdata_item_begin(item, boundary_);
}

std::string MultipartFormDataWriter::item_end() {
  return detail::serialize_multipart_formdata_item_end();
}

std::string MultipartFormDataWriter::finish() const {
  return detail::serialize_multipart_formdata_finish(boundary_);
}

// Response implementation
size_t Response::get_header_value_u64(const std::string &key, size_t def,
                                             size_t id) const {
  return detail::get_header_value_u64(headers, key, def, id);
}

bool Response::has_header(const std::string &key) const {
  return headers.find(key) != headers.end();
}

std::string Response::get_header_value(const std::string &key,
                                              const char *def,
                                              size_t id) const {
  return detail::get_header_value(headers, key, def, id);
}

size_t Response::get_header_value_count(const std::string &key) const {
  return detail::get_header_value_count(headers, key);
}

void Response::set_header(const std::string &key,
                                 const std::string &val) {
  detail::set_header(headers, key, val);
}
bool Response::has_trailer(const std::string &key) const {
  return trailers.find(key) != trailers.end();
}

std::string Response::get_trailer_value(const std::string &key,
                                               size_t id) const {
  return detail::get_multimap_value(trailers, key, id);
}

size_t Response::get_trailer_value_count(const std::string &key) const {
  auto r = trailers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

void Response::set_redirect(const std::string &url, int stat) {
  if (detail::fields::is_field_value(url)) {
    set_header("Location", url);
    if (300 <= stat && stat < 400) {
      this->status = stat;
    } else {
      this->status = StatusCode::Found_302;
    }
  }
}

void Response::set_content(const char *s, size_t n,
                                  const std::string &content_type) {
  body.assign(s, n);

  auto rng = headers.equal_range("Content-Type");
  headers.erase(rng.first, rng.second);
  set_header("Content-Type", content_type);
}

void Response::set_content(const std::string &s,
                                  const std::string &content_type) {
  set_content(s.data(), s.size(), content_type);
}

void Response::set_content(std::string &&s,
                                  const std::string &content_type) {
  body = std::move(s);

  auto rng = headers.equal_range("Content-Type");
  headers.erase(rng.first, rng.second);
  set_header("Content-Type", content_type);
}

void Response::set_content_provider(
    size_t in_length, const std::string &content_type, ContentProvider provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = in_length;
  if (in_length > 0) { content_provider_ = std::move(provider); }
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = false;
}

void Response::set_content_provider(
    const std::string &content_type, ContentProviderWithoutLength provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = 0;
  content_provider_ = detail::ContentProviderAdapter(std::move(provider));
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = false;
}

void Response::set_chunked_content_provider(
    const std::string &content_type, ContentProviderWithoutLength provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = 0;
  content_provider_ = detail::ContentProviderAdapter(std::move(provider));
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = true;
}

void Response::set_file_content(const std::string &path,
                                       const std::string &content_type) {
  file_content_path_ = path;
  file_content_content_type_ = content_type;
}

void Response::set_file_content(const std::string &path) {
  file_content_path_ = path;
}

// Result implementation
size_t Result::get_request_header_value_u64(const std::string &key,
                                                   size_t def,
                                                   size_t id) const {
  return detail::get_header_value_u64(request_headers_, key, def, id);
}

bool Result::has_request_header(const std::string &key) const {
  return request_headers_.find(key) != request_headers_.end();
}

std::string Result::get_request_header_value(const std::string &key,
                                                    const char *def,
                                                    size_t id) const {
  return detail::get_header_value(request_headers_, key, def, id);
}

size_t
Result::get_request_header_value_count(const std::string &key) const {
  auto r = request_headers_.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

// Stream implementation
ssize_t Stream::write(const char *ptr) {
  return write(ptr, strlen(ptr));
}

ssize_t Stream::write(const std::string &s) {
  return write(s.data(), s.size());
}

// BodyReader implementation
ssize_t detail::BodyReader::read(char *buf, size_t len) {
  if (!stream) {
    last_error = Error::Connection;
    return -1;
  }
  if (eof) { return 0; }

  if (!chunked) {
    // Content-Length based reading
    if (has_content_length && bytes_read >= content_length) {
      eof = true;
      return 0;
    }

    auto to_read = len;
    if (has_content_length) {
      auto remaining = content_length - bytes_read;
      to_read = (std::min)(len, remaining);
    }
    auto n = stream->read(buf, to_read);

    if (n < 0) {
      last_error = stream->get_error();
      if (last_error == Error::Success) { last_error = Error::Read; }
      eof = true;
      return n;
    }
    if (n == 0) {
      // Unexpected EOF before content_length
      last_error = stream->get_error();
      if (last_error == Error::Success) { last_error = Error::Read; }
      eof = true;
      return 0;
    }

    bytes_read += static_cast<size_t>(n);
    if (has_content_length && bytes_read >= content_length) { eof = true; }
    if (payload_max_length > 0 && bytes_read > payload_max_length) {
      last_error = Error::ExceedMaxPayloadSize;
      eof = true;
      return -1;
    }
    return n;
  }

  // Chunked transfer encoding: delegate to shared decoder instance.
  if (!chunked_decoder) { chunked_decoder.reset(new ChunkedDecoder(*stream)); }

  size_t chunk_offset = 0;
  size_t chunk_total = 0;
  auto n = chunked_decoder->read_payload(buf, len, chunk_offset, chunk_total);
  if (n < 0) {
    last_error = stream->get_error();
    if (last_error == Error::Success) { last_error = Error::Read; }
    eof = true;
    return n;
  }

  if (n == 0) {
    // Final chunk observed. Leave trailer parsing to the caller (StreamHandle).
    eof = true;
    return 0;
  }

  bytes_read += static_cast<size_t>(n);
  if (payload_max_length > 0 && bytes_read > payload_max_length) {
    last_error = Error::ExceedMaxPayloadSize;
    eof = true;
    return -1;
  }
  return n;
}

// ThreadPool implementation
ThreadPool::ThreadPool(size_t n, size_t max_n, size_t mqr,
                              time_t idle_timeout_sec)
    : base_thread_count_(n), max_queued_requests_(mqr),
      idle_timeout_sec_(idle_timeout_sec), idle_thread_count_(0),
      shutdown_(false) {
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  if (max_n != 0 && max_n < n) {
    std::string msg = "max_threads must be >= base_threads";
    throw std::invalid_argument(msg);
  }
#endif
  max_thread_count_ = max_n == 0 ? n : max_n;
  threads_.reserve(base_thread_count_);
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  try {
#endif
    for (size_t i = 0; i < base_thread_count_; i++) {
      threads_.emplace_back(std::thread([this]() { worker(false); }));
    }
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  } catch (...) {
    // If thread creation fails partway (e.g., pthread_create returns EAGAIN),
    // signal the workers we already spawned to exit and join them so the
    // vector destructor does not see joinable threads (which would call
    // std::terminate). Then rethrow so the caller learns of the failure.
    {
      std::unique_lock<std::mutex> lock(mutex_);
      shutdown_ = true;
    }
    cond_.notify_all();
    for (auto &t : threads_) {
      if (t.joinable()) { t.join(); }
    }
    throw;
  }
#endif
}

bool ThreadPool::enqueue(std::function<void()> fn) {
  {
    std::unique_lock<std::mutex> lock(mutex_);
    if (shutdown_) { return false; }
    if (max_queued_requests_ > 0 && jobs_.size() >= max_queued_requests_) {
      return false;
    }
    jobs_.push_back(std::move(fn));

    // Spawn a dynamic thread if no idle threads and under max
    if (idle_thread_count_ == 0 &&
        threads_.size() + dynamic_threads_.size() < max_thread_count_) {
      cleanup_finished_threads();
      dynamic_threads_.emplace_back(std::thread([this]() { worker(true); }));
    }
  }

  cond_.notify_one();
  return true;
}

void ThreadPool::shutdown() {
  {
    std::unique_lock<std::mutex> lock(mutex_);
    shutdown_ = true;
  }

  cond_.notify_all();

  for (auto &t : threads_) {
    if (t.joinable()) { t.join(); }
  }

  // Move dynamic_threads_ to a local list under the lock to avoid racing
  // with worker threads that call move_to_finished() concurrently.
  std::list<std::thread> remaining_dynamic;
  {
    std::unique_lock<std::mutex> lock(mutex_);
    remaining_dynamic = std::move(dynamic_threads_);
  }
  for (auto &t : remaining_dynamic) {
    if (t.joinable()) { t.join(); }
  }

  std::unique_lock<std::mutex> lock(mutex_);
  cleanup_finished_threads();
}

void ThreadPool::move_to_finished(std::thread::id id) {
  // Must be called with mutex_ held
  for (auto it = dynamic_threads_.begin(); it != dynamic_threads_.end(); ++it) {
    if (it->get_id() == id) {
      finished_threads_.push_back(std::move(*it));
      dynamic_threads_.erase(it);
      return;
    }
  }
}

void ThreadPool::cleanup_finished_threads() {
  // Must be called with mutex_ held
  for (auto &t : finished_threads_) {
    if (t.joinable()) { t.join(); }
  }
  finished_threads_.clear();
}

void ThreadPool::worker(bool is_dynamic) {
  for (;;) {
    std::function<void()> fn;
    {
      std::unique_lock<std::mutex> lock(mutex_);
      idle_thread_count_++;

      if (is_dynamic) {
        auto has_work =
            cond_.wait_for(lock, std::chrono::seconds(idle_timeout_sec_),
                           [&] { return !jobs_.empty() || shutdown_; });
        if (!has_work) {
          // Timed out with no work - exit this dynamic thread
          idle_thread_count_--;
          move_to_finished(std::this_thread::get_id());
          break;
        }
      } else {
        cond_.wait(lock, [&] { return !jobs_.empty() || shutdown_; });
      }

      idle_thread_count_--;

      if (shutdown_ && jobs_.empty()) { break; }

      fn = std::move(jobs_.front());
      jobs_.pop_front();
    }

    assert(true == static_cast<bool>(fn));
    fn();
  }

#if defined(CPPHTTPLIB_OPENSSL_SUPPORT) && !defined(OPENSSL_IS_BORINGSSL) &&   \
    !defined(LIBRESSL_VERSION_NUMBER)
  OPENSSL_thread_stop();
#endif
}

/*
 * Group 1 (continued): detail namespace - Stream implementations
 */

namespace detail {

void calc_actual_timeout(time_t max_timeout_msec, time_t duration_msec,
                                time_t timeout_sec, time_t timeout_usec,
                                time_t &actual_timeout_sec,
                                time_t &actual_timeout_usec) {
  auto timeout_msec = (timeout_sec * 1000) + (timeout_usec / 1000);

  auto actual_timeout_msec =
      (std::min)(max_timeout_msec - duration_msec, timeout_msec);

  if (actual_timeout_msec < 0) { actual_timeout_msec = 0; }

  actual_timeout_sec = actual_timeout_msec / 1000;
  actual_timeout_usec = (actual_timeout_msec % 1000) * 1000;
}

// Socket stream implementation
SocketStream::SocketStream(
    socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
    time_t write_timeout_sec, time_t write_timeout_usec,
    time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time)
    : sock_(sock), read_timeout_sec_(read_timeout_sec),
      read_timeout_usec_(read_timeout_usec),
      write_timeout_sec_(write_timeout_sec),
      write_timeout_usec_(write_timeout_usec),
      max_timeout_msec_(max_timeout_msec), start_time_(start_time),
      read_buff_(read_buff_size_, 0) {}

SocketStream::~SocketStream() = default;

bool SocketStream::is_readable() const {
  return read_buff_off_ < read_buff_content_size_;
}

bool SocketStream::wait_readable() const {
  if (max_timeout_msec_ <= 0) {
    return select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
  }

  time_t read_timeout_sec;
  time_t read_timeout_usec;
  calc_actual_timeout(max_timeout_msec_, duration(), read_timeout_sec_,
                      read_timeout_usec_, read_timeout_sec, read_timeout_usec);

  return select_read(sock_, read_timeout_sec, read_timeout_usec) > 0;
}

bool SocketStream::wait_writable() const {
  return select_write(sock_, write_timeout_sec_, write_timeout_usec_) > 0;
}

bool SocketStream::is_peer_alive() const {
  return detail::is_socket_alive(sock_);
}

ssize_t SocketStream::read(char *ptr, size_t size) {
#ifdef _WIN32
  size =
      (std::min)(size, static_cast<size_t>((std::numeric_limits<int>::max)()));
#else
  size = (std::min)(size,
                    static_cast<size_t>((std::numeric_limits<ssize_t>::max)()));
#endif

  if (read_buff_off_ < read_buff_content_size_) {
    auto remaining_size = read_buff_content_size_ - read_buff_off_;
    if (size <= remaining_size) {
      memcpy(ptr, read_buff_.data() + read_buff_off_, size);
      read_buff_off_ += size;
      return static_cast<ssize_t>(size);
    } else {
      memcpy(ptr, read_buff_.data() + read_buff_off_, remaining_size);
      read_buff_off_ += remaining_size;
      return static_cast<ssize_t>(remaining_size);
    }
  }

  if (!wait_readable()) {
    error_ = Error::Timeout;
    return -1;
  }

  read_buff_off_ = 0;
  read_buff_content_size_ = 0;

  if (size < read_buff_size_) {
    auto n = read_socket(sock_, read_buff_.data(), read_buff_size_,
                         CPPHTTPLIB_RECV_FLAGS);
    if (n <= 0) {
      if (n == 0) {
        error_ = Error::ConnectionClosed;
      } else {
        error_ = Error::Read;
      }
      return n;
    } else if (n <= static_cast<ssize_t>(size)) {
      memcpy(ptr, read_buff_.data(), static_cast<size_t>(n));
      return n;
    } else {
      memcpy(ptr, read_buff_.data(), size);
      read_buff_off_ = size;
      read_buff_content_size_ = static_cast<size_t>(n);
      return static_cast<ssize_t>(size);
    }
  } else {
    auto n = read_socket(sock_, ptr, size, CPPHTTPLIB_RECV_FLAGS);
    if (n <= 0) {
      if (n == 0) {
        error_ = Error::ConnectionClosed;
      } else {
        error_ = Error::Read;
      }
    }
    return n;
  }
}

ssize_t SocketStream::write(const char *ptr, size_t size) {
  if (!wait_writable()) { return -1; }

#if defined(_WIN32) && !defined(_WIN64)
  size =
      (std::min)(size, static_cast<size_t>((std::numeric_limits<int>::max)()));
#endif

  return send_socket(sock_, ptr, size, CPPHTTPLIB_SEND_FLAGS);
}

void SocketStream::get_remote_ip_and_port(std::string &ip,
                                                 int &port) const {
  return detail::get_remote_ip_and_port(sock_, ip, port);
}

void SocketStream::get_local_ip_and_port(std::string &ip,
                                                int &port) const {
  return detail::get_local_ip_and_port(sock_, ip, port);
}

socket_t SocketStream::socket() const { return sock_; }

time_t SocketStream::duration() const {
  return std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - start_time_)
      .count();
}

void SocketStream::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

// Buffer stream implementation
bool BufferStream::is_readable() const { return true; }

bool BufferStream::wait_readable() const { return true; }

bool BufferStream::wait_writable() const { return true; }

ssize_t BufferStream::read(char *ptr, size_t size) {
#if defined(_MSC_VER) && _MSC_VER < 1910
  auto len_read = buffer._Copy_s(ptr, size, size, position);
#else
  auto len_read = buffer.copy(ptr, size, position);
#endif
  position += static_cast<size_t>(len_read);
  return static_cast<ssize_t>(len_read);
}

ssize_t BufferStream::write(const char *ptr, size_t size) {
  buffer.append(ptr, size);
  return static_cast<ssize_t>(size);
}

void BufferStream::get_remote_ip_and_port(std::string & /*ip*/,
                                                 int & /*port*/) const {}

void BufferStream::get_local_ip_and_port(std::string & /*ip*/,
                                                int & /*port*/) const {}

socket_t BufferStream::socket() const { return 0; }

time_t BufferStream::duration() const { return 0; }

const std::string &BufferStream::get_buffer() const { return buffer; }

PathParamsMatcher::PathParamsMatcher(const std::string &pattern)
    : MatcherBase(pattern) {
  constexpr const char marker[] = "/:";

  // One past the last ending position of a path param substring
  std::size_t last_param_end = 0;

#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  // Needed to ensure that parameter names are unique during matcher
  // construction
  // If exceptions are disabled, only last duplicate path
  // parameter will be set
  std::unordered_set<std::string> param_name_set;
#endif

  while (true) {
    const auto marker_pos = pattern.find(
        marker, last_param_end == 0 ? last_param_end : last_param_end - 1);
    if (marker_pos == std::string::npos) { break; }

    static_fragments_.push_back(
        pattern.substr(last_param_end, marker_pos - last_param_end + 1));

    const auto param_name_start = marker_pos + str_len(marker);

    auto sep_pos = pattern.find(separator, param_name_start);
    if (sep_pos == std::string::npos) { sep_pos = pattern.length(); }

    auto param_name =
        pattern.substr(param_name_start, sep_pos - param_name_start);

#ifndef CPPHTTPLIB_NO_EXCEPTIONS
    if (param_name_set.find(param_name) != param_name_set.cend()) {
      std::string msg = "Encountered path parameter '" + param_name +
                        "' multiple times in route pattern '" + pattern + "'.";
      throw std::invalid_argument(msg);
    }
#endif

    param_names_.push_back(std::move(param_name));

    last_param_end = sep_pos + 1;
  }

  if (last_param_end < pattern.length()) {
    static_fragments_.push_back(pattern.substr(last_param_end));
  }
}

bool PathParamsMatcher::match(Request &request) const {
  request.matches = std::smatch();
  request.path_params.clear();
  request.path_params.reserve(param_names_.size());

  // One past the position at which the path matched the pattern last time
  std::size_t starting_pos = 0;
  for (size_t i = 0; i < static_fragments_.size(); ++i) {
    const auto &fragment = static_fragments_[i];

    if (starting_pos + fragment.length() > request.path.length()) {
      return false;
    }

    // Avoid unnecessary allocation by using strncmp instead of substr +
    // comparison
    if (std::strncmp(request.path.c_str() + starting_pos, fragment.c_str(),
                     fragment.length()) != 0) {
      return false;
    }

    starting_pos += fragment.length();

    // Should only happen when we have a static fragment after a param
    // Example: '/users/:id/subscriptions'
    // The 'subscriptions' fragment here does not have a corresponding param
    if (i >= param_names_.size()) { continue; }

    auto sep_pos = request.path.find(separator, starting_pos);
    if (sep_pos == std::string::npos) { sep_pos = request.path.length(); }

    const auto &param_name = param_names_[i];

    request.path_params.emplace(
        param_name, request.path.substr(starting_pos, sep_pos - starting_pos));

    // Mark everything up to '/' as matched
    starting_pos = sep_pos + 1;
  }
  // Returns false if the path is longer than the pattern
  return starting_pos >= request.path.length();
}

bool RegexMatcher::match(Request &request) const {
  request.path_params.clear();
  return std::regex_match(request.path, request.matches, regex_);
}

// Enclose IPv6 address in brackets if needed
std::string prepare_host_string(const std::string &host) {
  // Enclose IPv6 address in brackets (but not if already enclosed)
  if (host.find(':') == std::string::npos ||
      (!host.empty() && host[0] == '[')) {
    // IPv4, hostname, or already bracketed IPv6
    return host;
  } else {
    // IPv6 address without brackets
    return "[" + host + "]";
  }
}

std::string make_host_and_port_string(const std::string &host, int port,
                                             bool is_ssl) {
  auto result = prepare_host_string(host);

  // Append port if not default
  if ((!is_ssl && port == 80) || (is_ssl && port == 443)) {
    ; // do nothing
  } else {
    result += ":" + std::to_string(port);
  }

  return result;
}

// Create "host:port" string always including port number (for CONNECT method)
std::string
make_host_and_port_string_always_port(const std::string &host, int port) {
  return prepare_host_string(host) + ":" + std::to_string(port);
}

bool parse_no_proxy_entry(const std::string &token, NoProxyEntry &out);
NormalizedTarget normalize_target(const std::string &host);
bool ip_in_cidr(const IPBytes &ip, const IPBytes &net, int prefix_bits);
bool host_matches_no_proxy(const NormalizedTarget &target,
                           const std::vector<NoProxyEntry> &entries);

bool ip_in_cidr(const IPBytes &ip, const IPBytes &net, int prefix_bits) {
  if (prefix_bits < 0 || prefix_bits > 128) { return false; }
  if (prefix_bits == 0) { return true; }
  int full_bytes = prefix_bits / 8;
  int rem_bits = prefix_bits % 8;
  if (full_bytes > 0 && std::memcmp(ip.data(), net.data(),
                                    static_cast<size_t>(full_bytes)) != 0) {
    return false;
  }
  if (rem_bits == 0) { return true; }
  auto i = static_cast<size_t>(full_bytes);
  auto mask = static_cast<uint8_t>(0xFFu << (8 - rem_bits));
  return (ip[i] & mask) == (net[i] & mask);
}

bool parse_no_proxy_entry(const std::string &token, NoProxyEntry &out) {
  if (token.empty()) { return false; }

  if (token == "*") {
    out.kind = NoProxyKind::Wildcard;
    return true;
  }

  auto slash = token.find('/');
  std::string addr_part =
      (slash == std::string::npos) ? token : token.substr(0, slash);
  std::string prefix_part =
      (slash == std::string::npos) ? std::string() : token.substr(slash + 1);

  // A bare slash or trailing-slash CIDR like "10.0.0.0/" is malformed;
  // don't silently treat it as a /32 (or /128).
  if (slash != std::string::npos && prefix_part.empty()) { return false; }

  // Accept the bracketed IPv6 form ("[::1]", "[fe80::]/10") as well as the
  // bare form. Brackets have no meaning for IPv4, so skip the IPv4 attempt
  // when brackets are present.
  bool bracketed = addr_part.size() >= 2 && addr_part.front() == '[' &&
                   addr_part.back() == ']';
  if (bracketed) { addr_part = addr_part.substr(1, addr_part.size() - 2); }

  if (!bracketed) {
    struct in_addr v4;
    if (inet_pton(AF_INET, addr_part.c_str(), &v4) == 1) {
      int prefix = 32;
      if (!prefix_part.empty()) {
        auto r = from_chars(prefix_part.data(),
                            prefix_part.data() + prefix_part.size(), prefix);
        if (r.ec != std::errc{} ||
            r.ptr != prefix_part.data() + prefix_part.size()) {
          return false;
        }
        if (prefix < 0 || prefix > 32) { return false; }
      }
      out.kind = NoProxyKind::IPv4Cidr;
      std::memcpy(out.net.data(), &v4, sizeof(v4));
      out.prefix_bits = prefix;
      return true;
    }
  }

  struct in6_addr v6;
  if (inet_pton(AF_INET6, addr_part.c_str(), &v6) == 1) {
    int prefix = 128;
    if (!prefix_part.empty()) {
      auto r = from_chars(prefix_part.data(),
                          prefix_part.data() + prefix_part.size(), prefix);
      if (r.ec != std::errc{} ||
          r.ptr != prefix_part.data() + prefix_part.size()) {
        return false;
      }
      if (prefix < 0 || prefix > 128) { return false; }
    }
    out.kind = NoProxyKind::IPv6Cidr;
    std::memcpy(out.net.data(), &v6, sizeof(v6));
    out.prefix_bits = prefix;
    return true;
  }

  // Bracketed entries can only be IPv6. If the IPv6 parse above failed,
  // the entry is malformed — don't fall through to the hostname branch.
  if (bracketed) { return false; }

  // A '/' on a non-IP token means a CIDR prefix without an address. Reject.
  if (slash != std::string::npos) { return false; }
  // Port-specific entries (host:port) are not supported.
  if (token.find(':') != std::string::npos) { return false; }

  std::string hostname = case_ignore::to_lower(token);
  while (!hostname.empty() && hostname.front() == '.') {
    hostname.erase(hostname.begin());
  }
  while (!hostname.empty() && hostname.back() == '.') {
    hostname.pop_back();
  }
  if (hostname.empty()) { return false; }

  out.kind = NoProxyKind::HostnameSuffix;
  out.hostname_pattern = std::move(hostname);
  return true;
}

NormalizedTarget normalize_target(const std::string &host) {
  NormalizedTarget t;
  std::string h = host;

  if (h.size() >= 2 && h.front() == '[' && h.back() == ']') {
    h = h.substr(1, h.size() - 2);
  }

  // Strip a single trailing dot so "example.com." canonicalizes to
  // "example.com".
  if (!h.empty() && h.back() == '.') { h.pop_back(); }

  t.hostname = case_ignore::to_lower(h);

  if (!t.hostname.empty()) {
    struct in_addr v4;
    struct in6_addr v6;
    if (inet_pton(AF_INET, t.hostname.c_str(), &v4) == 1) {
      t.is_ipv4 = true;
      std::memcpy(t.ip.data(), &v4, sizeof(v4));
    } else if (inet_pton(AF_INET6, t.hostname.c_str(), &v6) == 1) {
      t.is_ipv6 = true;
      std::memcpy(t.ip.data(), &v6, sizeof(v6));
    }
  }
  return t;
}

bool host_matches_no_proxy(const NormalizedTarget &target,
                                  const std::vector<NoProxyEntry> &entries) {
  if (target.hostname.empty()) { return false; }
  for (const auto &e : entries) {
    switch (e.kind) {
    case NoProxyKind::Wildcard: return true;
    case NoProxyKind::IPv4Cidr:
      if (target.is_ipv4 && ip_in_cidr(target.ip, e.net, e.prefix_bits)) {
        return true;
      }
      break;
    case NoProxyKind::IPv6Cidr:
      if (target.is_ipv6 && ip_in_cidr(target.ip, e.net, e.prefix_bits)) {
        return true;
      }
      break;
    case NoProxyKind::HostnameSuffix:
      if (target.is_ipv4 || target.is_ipv6) { break; }
      if (target.hostname == e.hostname_pattern) { return true; }
      // Dot-boundary suffix match: prevents "evilexample.com" from matching
      // an entry of "example.com".
      if (target.hostname.size() > e.hostname_pattern.size() + 1) {
        auto offset = target.hostname.size() - e.hostname_pattern.size();
        if (target.hostname[offset - 1] == '.' &&
            target.hostname.compare(offset, e.hostname_pattern.size(),
                                    e.hostname_pattern) == 0) {
          return true;
        }
      }
      break;
    }
  }
  return false;
}

template <typename T>
bool check_and_write_headers(Stream &strm, Headers &headers,
                                    T header_writer, Error &error) {
  for (const auto &h : headers) {
    if (!detail::fields::is_field_valid(h.first, h.second)) {
      error = Error::InvalidHeaders;
      return false;
    }
  }
  if (header_writer(strm, headers) <= 0) {
    error = Error::Write;
    return false;
  }
  return true;
}

} // namespace detail

/*
 * Group 2 (continued): detail namespace - SSLSocketStream implementation
 */

#ifdef CPPHTTPLIB_SSL_ENABLED
namespace detail {

// SSL socket stream implementation
SSLSocketStream::SSLSocketStream(
    socket_t sock, tls::session_t session, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time)
    : sock_(sock), session_(session), read_timeout_sec_(read_timeout_sec),
      read_timeout_usec_(read_timeout_usec),
      write_timeout_sec_(write_timeout_sec),
      write_timeout_usec_(write_timeout_usec),
      max_timeout_msec_(max_timeout_msec), start_time_(start_time) {
#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
  // Clear AUTO_RETRY for proper non-blocking I/O timeout handling
  // Note: create_session() also clears this, but SSLClient currently
  // uses ssl_new() which does not. Until full TLS API migration is complete,
  // we need to ensure AUTO_RETRY is cleared here regardless of how the
  // SSL session was created.
  SSL_clear_mode(static_cast<SSL *>(session), SSL_MODE_AUTO_RETRY);
#endif
}

SSLSocketStream::~SSLSocketStream() = default;

bool SSLSocketStream::is_readable() const {
  return tls::pending(session_) > 0;
}

bool SSLSocketStream::wait_readable() const {
  if (max_timeout_msec_ <= 0) {
    return select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
  }

  time_t read_timeout_sec;
  time_t read_timeout_usec;
  calc_actual_timeout(max_timeout_msec_, duration(), read_timeout_sec_,
                      read_timeout_usec_, read_timeout_sec, read_timeout_usec);

  return select_read(sock_, read_timeout_sec, read_timeout_usec) > 0;
}

bool SSLSocketStream::wait_writable() const {
  return select_write(sock_, write_timeout_sec_, write_timeout_usec_) > 0 &&
         !tls::is_peer_closed(session_, sock_);
}

bool SSLSocketStream::is_peer_alive() const {
  return !tls::is_peer_closed(session_, sock_);
}

ssize_t SSLSocketStream::read(char *ptr, size_t size) {
  if (tls::pending(session_) > 0) {
    tls::TlsError err;
    auto ret = tls::read(session_, ptr, size, err);
    if (ret == 0 || err.code == tls::ErrorCode::PeerClosed) {
      error_ = Error::ConnectionClosed;
    }
    return ret;
  } else if (wait_readable()) {
    tls::TlsError err;
    auto ret = tls::read(session_, ptr, size, err);
    if (ret < 0) {
      auto n = 1000;
#ifdef _WIN32
      while (--n >= 0 && (err.code == tls::ErrorCode::WantRead ||
                          (err.code == tls::ErrorCode::SyscallError &&
                           WSAGetLastError() == WSAETIMEDOUT))) {
#else
      while (--n >= 0 && err.code == tls::ErrorCode::WantRead) {
#endif
        if (tls::pending(session_) > 0) {
          return tls::read(session_, ptr, size, err);
        } else if (wait_readable()) {
          std::this_thread::sleep_for(std::chrono::microseconds{10});
          ret = tls::read(session_, ptr, size, err);
          if (ret >= 0) { return ret; }
        } else {
          break;
        }
      }
      assert(ret < 0);
    } else if (ret == 0 || err.code == tls::ErrorCode::PeerClosed) {
      error_ = Error::ConnectionClosed;
    }
    return ret;
  } else {
    error_ = Error::Timeout;
    return -1;
  }
}

ssize_t SSLSocketStream::write(const char *ptr, size_t size) {
  if (wait_writable()) {
    auto handle_size =
        std::min<size_t>(size, (std::numeric_limits<int>::max)());

    tls::TlsError err;
    auto ret = tls::write(session_, ptr, handle_size, err);
    if (ret < 0) {
      auto n = 1000;
#ifdef _WIN32
      while (--n >= 0 && (err.code == tls::ErrorCode::WantWrite ||
                          (err.code == tls::ErrorCode::SyscallError &&
                           WSAGetLastError() == WSAETIMEDOUT))) {
#else
      while (--n >= 0 && err.code == tls::ErrorCode::WantWrite) {
#endif
        if (wait_writable()) {
          std::this_thread::sleep_for(std::chrono::microseconds{10});
          ret = tls::write(session_, ptr, handle_size, err);
          if (ret >= 0) { return ret; }
        } else {
          break;
        }
      }
      assert(ret < 0);
    }
    return ret;
  }
  return -1;
}

void SSLSocketStream::get_remote_ip_and_port(std::string &ip,
                                                    int &port) const {
  detail::get_remote_ip_and_port(sock_, ip, port);
}

void SSLSocketStream::get_local_ip_and_port(std::string &ip,
                                                   int &port) const {
  detail::get_local_ip_and_port(sock_, ip, port);
}

socket_t SSLSocketStream::socket() const { return sock_; }

time_t SSLSocketStream::duration() const {
  return std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - start_time_)
      .count();
}

void SSLSocketStream::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

} // namespace detail
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 4: Server implementation
 */

// HTTP server implementation
Server::Server()
    : new_task_queue([] {
        return new ThreadPool(CPPHTTPLIB_THREAD_POOL_COUNT,
                              CPPHTTPLIB_THREAD_POOL_MAX_COUNT);
      }) {
#ifndef _WIN32
  signal(SIGPIPE, SIG_IGN);
#endif
}

Server::~Server() = default;

std::unique_ptr<detail::MatcherBase>
Server::make_matcher(const std::string &pattern) {
  if (pattern.find("/:") != std::string::npos) {
    return detail::make_unique<detail::PathParamsMatcher>(pattern);
  } else {
    return detail::make_unique<detail::RegexMatcher>(pattern);
  }
}

Server &Server::Get(const std::string &pattern, Handler handler) {
  return add_handler(get_handlers_, pattern, std::move(handler));
}

Server &Server::Post(const std::string &pattern, Handler handler) {
  return add_handler(post_handlers_, pattern, std::move(handler));
}

Server &Server::Post(const std::string &pattern,
                            HandlerWithContentReader handler) {
  return add_handler(post_handlers_for_content_reader_, pattern,
                     std::move(handler));
}

Server &Server::Put(const std::string &pattern, Handler handler) {
  return add_handler(put_handlers_, pattern, std::move(handler));
}

Server &Server::Put(const std::string &pattern,
                           HandlerWithContentReader handler) {
  return add_handler(put_handlers_for_content_reader_, pattern,
                     std::move(handler));
}

Server &Server::Patch(const std::string &pattern, Handler handler) {
  return add_handler(patch_handlers_, pattern, std::move(handler));
}

Server &Server::Patch(const std::string &pattern,
                             HandlerWithContentReader handler) {
  return add_handler(patch_handlers_for_content_reader_, pattern,
                     std::move(handler));
}

Server &Server::Delete(const std::string &pattern, Handler handler) {
  return add_handler(delete_handlers_, pattern, std::move(handler));
}

Server &Server::Delete(const std::string &pattern,
                              HandlerWithContentReader handler) {
  return add_handler(delete_handlers_for_content_reader_, pattern,
                     std::move(handler));
}

Server &Server::Options(const std::string &pattern, Handler handler) {
  return add_handler(options_handlers_, pattern, std::move(handler));
}

Server &Server::WebSocket(const std::string &pattern,
                                 WebSocketHandler handler) {
  websocket_handlers_.push_back(
      {make_matcher(pattern), std::move(handler), nullptr});
  return *this;
}

Server &Server::WebSocket(const std::string &pattern,
                                 WebSocketHandler handler,
                                 SubProtocolSelector sub_protocol_selector) {
  websocket_handlers_.push_back({make_matcher(pattern), std::move(handler),
                                 std::move(sub_protocol_selector)});
  return *this;
}

bool Server::set_base_dir(const std::string &dir,
                                 const std::string &mount_point) {
  return set_mount_point(mount_point, dir);
}

bool Server::set_mount_point(const std::string &mount_point,
                                    const std::string &dir, Headers headers) {
  detail::FileStat stat(dir);
  if (stat.is_dir()) {
    std::string mnt = !mount_point.empty() ? mount_point : "/";
    if (!mnt.empty() && mnt[0] == '/') {
      std::string resolved_base;
      if (detail::canonicalize_path(dir.c_str(), resolved_base)) {
#if defined(_WIN32)
        if (resolved_base.back() != '\\' && resolved_base.back() != '/') {
          resolved_base += '\\';
        }
#else
        if (resolved_base.back() != '/') { resolved_base += '/'; }
#endif
      }
      base_dirs_.push_back(
          {std::move(mnt), dir, std::move(resolved_base), std::move(headers)});
      return true;
    }
  }
  return false;
}

bool Server::remove_mount_point(const std::string &mount_point) {
  for (auto it = base_dirs_.begin(); it != base_dirs_.end(); ++it) {
    if (it->mount_point == mount_point) {
      base_dirs_.erase(it);
      return true;
    }
  }
  return false;
}

Server &
Server::set_file_extension_and_mimetype_mapping(const std::string &ext,
                                                const std::string &mime) {
  file_extension_and_mimetype_map_[ext] = mime;
  return *this;
}

Server &Server::set_default_file_mimetype(const std::string &mime) {
  default_file_mimetype_ = mime;
  return *this;
}

Server &Server::set_file_request_handler(Handler handler) {
  file_request_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_error_handler_core(HandlerWithResponse handler,
                                              std::true_type) {
  error_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_error_handler_core(Handler handler,
                                              std::false_type) {
  error_handler_ = [handler](const Request &req, Response &res) {
    handler(req, res);
    return HandlerResponse::Handled;
  };
  return *this;
}

Server &Server::set_exception_handler(ExceptionHandler handler) {
  exception_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_pre_routing_handler(HandlerWithResponse handler) {
  pre_routing_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_post_routing_handler(Handler handler) {
  post_routing_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_pre_request_handler(HandlerWithResponse handler) {
  pre_request_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_logger(Logger logger) {
  logger_ = std::move(logger);
  return *this;
}

Server &Server::set_error_logger(ErrorLogger error_logger) {
  error_logger_ = std::move(error_logger);
  return *this;
}

Server &Server::set_pre_compression_logger(Logger logger) {
  pre_compression_logger_ = std::move(logger);
  return *this;
}

Server &
Server::set_expect_100_continue_handler(Expect100ContinueHandler handler) {
  expect_100_continue_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_start_handler(StartHandler handler) {
  start_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_address_family(int family) {
  address_family_ = family;
  return *this;
}

Server &Server::set_tcp_nodelay(bool on) {
  tcp_nodelay_ = on;
  return *this;
}

Server &Server::set_ipv6_v6only(bool on) {
  ipv6_v6only_ = on;
  return *this;
}

Server &Server::set_socket_options(SocketOptions socket_options) {
  socket_options_ = std::move(socket_options);
  return *this;
}

Server &Server::set_default_headers(Headers headers) {
  default_headers_ = std::move(headers);
  return *this;
}

Server &Server::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  header_writer_ = writer;
  return *this;
}

Server &
Server::set_trusted_proxies(const std::vector<std::string> &proxies) {
  trusted_proxies_ = proxies;
  return *this;
}

Server &Server::set_keep_alive_max_count(size_t count) {
  keep_alive_max_count_ = count;
  return *this;
}

Server &Server::set_keep_alive_timeout(time_t sec) {
  keep_alive_timeout_sec_ = sec;
  return *this;
}

template <class Rep, class Period>
Server &Server::set_keep_alive_timeout(
    const std::chrono::duration<Rep, Period> &duration) {
  detail::duration_to_sec_and_usec(duration, [&](time_t sec, time_t /*usec*/) {
    set_keep_alive_timeout(sec);
  });
  return *this;
}

Server &Server::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
  return *this;
}

Server &Server::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
  return *this;
}

Server &Server::set_idle_interval(time_t sec, time_t usec) {
  idle_interval_sec_ = sec;
  idle_interval_usec_ = usec;
  return *this;
}

Server &Server::set_payload_max_length(size_t length) {
  payload_max_length_ = length;
  return *this;
}

Server &Server::set_websocket_max_missed_pongs(int count) {
  websocket_max_missed_pongs_ = count;
  return *this;
}

Server &Server::set_websocket_ping_interval(time_t sec) {
  websocket_ping_interval_sec_ = sec;
  return *this;
}

template <class Rep, class Period>
Server &Server::set_websocket_ping_interval(
    const std::chrono::duration<Rep, Period> &duration) {
  detail::duration_to_sec_and_usec(duration, [&](time_t sec, time_t /*usec*/) {
    set_websocket_ping_interval(sec);
  });
  return *this;
}

bool Server::bind_to_port(const std::string &host, int port,
                                 int socket_flags) {
  auto ret = bind_internal(host, port, socket_flags);
  if (ret == -1) { is_decommissioned = true; }
  return ret >= 0;
}
int Server::bind_to_any_port(const std::string &host, int socket_flags) {
  auto ret = bind_internal(host, 0, socket_flags);
  if (ret == -1) { is_decommissioned = true; }
  return ret;
}

bool Server::listen_after_bind() { return listen_internal(); }

bool Server::listen(const std::string &host, int port,
                           int socket_flags) {
  return bind_to_port(host, port, socket_flags) && listen_internal();
}

bool Server::is_running() const { return is_running_; }

void Server::wait_until_ready() const {
  while (!is_running_ && !is_decommissioned) {
    std::this_thread::sleep_for(std::chrono::milliseconds{1});
  }
}

void Server::stop() noexcept {
  if (is_running_) {
    assert(svr_sock_ != INVALID_SOCKET);
    std::atomic<socket_t> sock(svr_sock_.exchange(INVALID_SOCKET));
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
  }
  is_decommissioned = false;
}

void Server::decommission() { is_decommissioned = true; }

bool Server::parse_request_line(const char *s, Request &req) const {
  auto len = strlen(s);
  if (len < 2 || s[len - 2] != '\r' || s[len - 1] != '\n') { return false; }
  len -= 2;

  {
    size_t count = 0;

    detail::split(s, s + len, ' ', [&](const char *b, const char *e) {
      switch (count) {
      case 0: req.method = std::string(b, e); break;
      case 1: req.target = std::string(b, e); break;
      case 2: req.version = std::string(b, e); break;
      default: break;
      }
      count++;
    });

    if (count != 3) { return false; }
  }

  thread_local const std::set<std::string> methods{
      "GET",     "HEAD",    "POST",  "PUT",   "DELETE",
      "CONNECT", "OPTIONS", "TRACE", "PATCH", "PRI"};

  if (methods.find(req.method) == methods.end()) {
    output_error_log(Error::InvalidHTTPMethod, &req);
    return false;
  }

  if (req.version != "HTTP/1.1" && req.version != "HTTP/1.0") {
    output_error_log(Error::InvalidHTTPVersion, &req);
    return false;
  }

  {
    // Skip URL fragment
    for (size_t i = 0; i < req.target.size(); i++) {
      if (req.target[i] == '#') {
        req.target.erase(i);
        break;
      }
    }

    detail::divide(req.target, '?',
                   [&](const char *lhs_data, std::size_t lhs_size,
                       const char *rhs_data, std::size_t rhs_size) {
                     req.path =
                         decode_path_component(std::string(lhs_data, lhs_size));
                     detail::parse_query_text(rhs_data, rhs_size, req.params);
                   });
  }

  return true;
}

bool Server::write_response(Stream &strm, bool close_connection,
                                   Request &req, Response &res) {
  // NOTE: `req.ranges` should be empty, otherwise it will be applied
  // incorrectly to the error content.
  req.ranges.clear();
  return write_response_core(strm, close_connection, req, res, false);
}

bool Server::write_response_with_content(Stream &strm,
                                                bool close_connection,
                                                const Request &req,
                                                Response &res) {
  return write_response_core(strm, close_connection, req, res, true);
}

bool Server::write_response_core(Stream &strm, bool close_connection,
                                        const Request &req, Response &res,
                                        bool need_apply_ranges) {
  assert(res.status != -1);

  if (400 <= res.status && error_handler_ &&
      error_handler_(req, res) == HandlerResponse::Handled) {
    need_apply_ranges = true;
  }

  std::string content_type;
  std::string boundary;
  if (need_apply_ranges) { apply_ranges(req, res, content_type, boundary); }

  // Prepare additional headers
  if (close_connection || req.get_header_value("Connection") == "close" ||
      400 <= res.status) { // Don't leave connections open after errors
    res.set_header("Connection", "close");
  } else {
    std::string s = "timeout=";
    s += std::to_string(keep_alive_timeout_sec_);
    s += ", max=";
    s += std::to_string(keep_alive_max_count_);
    res.set_header("Keep-Alive", s);
  }

  if ((!res.body.empty() || res.content_length_ > 0 || res.content_provider_) &&
      !res.has_header("Content-Type")) {
    res.set_header("Content-Type", "text/plain");
  }

  if (res.body.empty() && !res.content_length_ && !res.content_provider_ &&
      !res.has_header("Content-Length")) {
    res.set_header("Content-Length", "0");
  }

  if (req.method == "HEAD" && !res.has_header("Accept-Ranges")) {
    res.set_header("Accept-Ranges", "bytes");
  }

  if (post_routing_handler_) { post_routing_handler_(req, res); }

  // Response line and headers
  detail::BufferStream bstrm;
  if (!detail::write_response_line(bstrm, res.status)) { return false; }
  if (header_writer_(bstrm, res.headers) <= 0) { return false; }

  // Combine small body with headers to reduce write syscalls
  if (req.method != "HEAD" && !res.body.empty() && !res.content_provider_) {
    bstrm.write(res.body.data(), res.body.size());
  }

  // Log before writing to avoid race condition with client-side code that
  // accesses logger-captured data immediately after receiving the response.
  output_log(req, res);

  // Flush buffer
  auto &data = bstrm.get_buffer();
  if (!detail::write_data(strm, data.data(), data.size())) { return false; }

  // Streaming body
  auto ret = true;
  if (req.method != "HEAD" && res.content_provider_) {
    if (write_content_with_provider(strm, req, res, boundary, content_type)) {
      res.content_provider_success_ = true;
    } else {
      ret = false;
    }
  }

  return ret;
}

bool
Server::write_content_with_provider(Stream &strm, const Request &req,
                                    Response &res, const std::string &boundary,
                                    const std::string &content_type) {
  auto is_shutting_down = [this]() {
    return this->svr_sock_ == INVALID_SOCKET;
  };

  if (res.content_length_ > 0) {
    if (req.ranges.empty()) {
      return detail::write_content(strm, res.content_provider_, 0,
                                   res.content_length_, is_shutting_down);
    } else if (req.ranges.size() == 1) {
      auto offset_and_length = detail::get_range_offset_and_length(
          req.ranges[0], res.content_length_);

      return detail::write_content(strm, res.content_provider_,
                                   offset_and_length.first,
                                   offset_and_length.second, is_shutting_down);
    } else {
      return detail::write_multipart_ranges_data(
          strm, req, res, boundary, content_type, res.content_length_,
          is_shutting_down);
    }
  } else {
    if (res.is_chunked_content_provider_) {
      auto type = detail::encoding_type(req, res);

      auto compressor = detail::make_compressor(type);
      if (!compressor) {
        compressor = detail::make_unique<detail::nocompressor>();
      }

      return detail::write_content_chunked(strm, res.content_provider_,
                                           is_shutting_down, *compressor);
    } else {
      return detail::write_content_without_length(strm, res.content_provider_,
                                                  is_shutting_down);
    }
  }
}

bool Server::read_content(Stream &strm, Request &req, Response &res) {
  FormFields::iterator cur_field;
  FormFiles::iterator cur_file;
  auto is_text_field = false;
  size_t count = 0;
  if (read_content_core(
          strm, req, res,
          // Regular
          [&](const char *buf, size_t n) {
            // Prevent arithmetic overflow when checking sizes.
            // Avoid computing (req.body.size() + n) directly because
            // adding two unsigned `size_t` values can wrap around and
            // produce a small result instead of indicating overflow.
            // Instead, check using subtraction: ensure `n` does not
            // exceed the remaining capacity `max_size() - size()`.
            if (req.body.size() >= req.body.max_size() ||
                n > req.body.max_size() - req.body.size()) {
              return false;
            }

            // Limit decompressed body size to payload_max_length_ to protect
            // against "zip bomb" attacks where a small compressed payload
            // decompresses to a massive size.
            if (payload_max_length_ > 0 &&
                (req.body.size() >= payload_max_length_ ||
                 n > payload_max_length_ - req.body.size())) {
              return false;
            }

            req.body.append(buf, n);
            return true;
          },
          // Multipart FormData
          [&](const FormData &file) {
            if (count++ == CPPHTTPLIB_MULTIPART_FORM_DATA_FILE_MAX_COUNT) {
              output_error_log(Error::TooManyFormDataFiles, &req);
              return false;
            }

            if (file.filename.empty()) {
              cur_field = req.form.fields.emplace(
                  file.name, FormField{file.name, file.content, file.headers});
              is_text_field = true;
            } else {
              cur_file = req.form.files.emplace(file.name, file);
              is_text_field = false;
            }
            return true;
          },
          [&](const char *buf, size_t n) {
            if (is_text_field) {
              auto &content = cur_field->second.content;
              if (content.size() + n > content.max_size()) { return false; }
              content.append(buf, n);
            } else {
              auto &content = cur_file->second.content;
              if (content.size() + n > content.max_size()) { return false; }
              content.append(buf, n);
            }
            return true;
          })) {
    const auto &content_type = req.get_header_value("Content-Type");
    if (detail::extract_media_type(content_type) ==
        "application/x-www-form-urlencoded") {
      if (req.body.size() > CPPHTTPLIB_FORM_URL_ENCODED_PAYLOAD_MAX_LENGTH) {
        res.status = StatusCode::PayloadTooLarge_413; // NOTE: should be 414?
        output_error_log(Error::ExceedMaxPayloadSize, &req);
        return false;
      }
      detail::parse_query_text(req.body, req.params);
    }
    return true;
  }
  return false;
}

bool Server::read_content_with_content_receiver(
    Stream &strm, Request &req, Response &res, ContentReceiver receiver,
    FormDataHeader multipart_header, ContentReceiver multipart_receiver) {
  return read_content_core(strm, req, res, std::move(receiver),
                           std::move(multipart_header),
                           std::move(multipart_receiver));
}

bool Server::read_content_core(
    Stream &strm, Request &req, Response &res, ContentReceiver receiver,
    FormDataHeader multipart_header, ContentReceiver multipart_receiver) const {
  detail::FormDataParser multipart_form_data_parser;
  ContentReceiverWithProgress out;

  if (req.is_multipart_form_data()) {
    const auto &content_type = req.get_header_value("Content-Type");
    std::string boundary;
    if (!detail::parse_multipart_boundary(content_type, boundary)) {
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::MultipartParsing, &req);
      return false;
    }

    multipart_form_data_parser.set_boundary(std::move(boundary));
    out = [&](const char *buf, size_t n, size_t /*off*/, size_t /*len*/) {
      return multipart_form_data_parser.parse(buf, n, multipart_header,
                                              multipart_receiver);
    };
  } else {
    out = [receiver](const char *buf, size_t n, size_t /*off*/,
                     size_t /*len*/) { return receiver(buf, n); };
  }

  // RFC 9112 §6: no Transfer-Encoding and no Content-Length means no body.
  // For non-SSL builds we still scan non-persistent connections for stray
  // body bytes so the payload limit is enforced (413). On keep-alive,
  // pending bytes may be the next request (issue #2450), so skip.
#if !defined(CPPHTTPLIB_SSL_ENABLED)
  if (!req.has_header("Content-Length") &&
      !detail::is_chunked_transfer_encoding(req.headers)) {
    if (!detail::is_connection_persistent(req) && payload_max_length_ > 0 &&
        payload_max_length_ < (std::numeric_limits<size_t>::max)()) {
      auto has_data = strm.is_readable();
      if (!has_data) {
        auto s = strm.socket();
        if (s != INVALID_SOCKET) {
          has_data = detail::select_read(s, 0, 0) > 0;
        }
      }
      if (has_data) {
        auto result =
            detail::read_content_without_length(strm, payload_max_length_, out);
        if (result == detail::ReadContentResult::PayloadTooLarge) {
          res.status = StatusCode::PayloadTooLarge_413;
          return false;
        } else if (result != detail::ReadContentResult::Success) {
          return false;
        }
        return true;
      }
    }
    return true;
  }
#else
  if (!req.has_header("Content-Length") &&
      !detail::is_chunked_transfer_encoding(req.headers)) {
    return true;
  }
#endif

  if (!detail::read_content(strm, req, payload_max_length_, res.status, nullptr,
                            out, true)) {
    return false;
  }

  req.body_consumed_ = true;

  if (req.is_multipart_form_data()) {
    if (!multipart_form_data_parser.is_valid()) {
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::MultipartParsing, &req);
      return false;
    }
  }

  return true;
}

bool Server::handle_file_request(Request &req, Response &res) {
  for (const auto &entry : base_dirs_) {
    // Prefix match
    if (!req.path.compare(0, entry.mount_point.size(), entry.mount_point)) {
      std::string sub_path = "/" + req.path.substr(entry.mount_point.size());
      if (detail::is_valid_path(sub_path)) {
        auto path = entry.base_dir + sub_path;
        if (path.back() == '/') { path += "index.html"; }

        // Defense-in-depth: is_valid_path blocks ".." traversal in the URL,
        // but symlinks/junctions can still escape the base directory.
        if (!entry.resolved_base_dir.empty()) {
          std::string resolved_path;
          if (detail::canonicalize_path(path.c_str(), resolved_path) &&
              !detail::is_path_within_base(resolved_path,
                                           entry.resolved_base_dir)) {
            res.status = StatusCode::Forbidden_403;
            return true;
          }
        }

        detail::FileStat stat(path);

        if (stat.is_dir()) {
          res.set_redirect(sub_path + "/", StatusCode::MovedPermanently_301);
          return true;
        }

        if (stat.is_file()) {
          for (const auto &kv : entry.headers) {
            res.set_header(kv.first, kv.second);
          }

          auto etag = detail::compute_etag(stat);
          if (!etag.empty()) { res.set_header("ETag", etag); }

          auto mtime = stat.mtime();

          auto last_modified = detail::file_mtime_to_http_date(mtime);
          if (!last_modified.empty()) {
            res.set_header("Last-Modified", last_modified);
          }

          if (check_if_not_modified(req, res, etag, mtime)) { return true; }

          check_if_range(req, etag, mtime);

          auto mm = std::make_shared<detail::mmap>(path.c_str());
          if (!mm->is_open()) {
            output_error_log(Error::OpenFile, &req);
            return false;
          }

          res.set_content_provider(
              mm->size(),
              detail::find_content_type(path, file_extension_and_mimetype_map_,
                                        default_file_mimetype_),
              [mm](size_t offset, size_t length, DataSink &sink) -> bool {
                sink.write(mm->data() + offset, length);
                return true;
              });

          if (req.method != "HEAD" && file_request_handler_) {
            file_request_handler_(req, res);
          }

          return true;
        } else {
          output_error_log(Error::OpenFile, &req);
        }
      }
    }
  }
  return false;
}

bool Server::check_if_not_modified(const Request &req, Response &res,
                                          const std::string &etag,
                                          time_t mtime) const {
  // Handle conditional GET:
  // 1. If-None-Match takes precedence (RFC 9110 Section 13.1.2)
  // 2. If-Modified-Since is checked only when If-None-Match is absent
  if (req.has_header("If-None-Match")) {
    if (!etag.empty()) {
      auto val = req.get_header_value("If-None-Match");

      // NOTE: We use exact string matching here. This works correctly
      // because our server always generates weak ETags (W/"..."), and
      // clients typically send back the same ETag they received.
      // RFC 9110 Section 8.8.3.2 allows weak comparison for
      // If-None-Match, where W/"x" and "x" would match, but this
      // simplified implementation requires exact matches.
      auto ret = detail::split_find(val.data(), val.data() + val.size(), ',',
                                    [&](const char *b, const char *e) {
                                      auto seg_len = static_cast<size_t>(e - b);
                                      return (seg_len == 1 && *b == '*') ||
                                             (seg_len == etag.size() &&
                                              std::equal(b, e, etag.begin()));
                                    });

      if (ret) {
        res.status = StatusCode::NotModified_304;
        return true;
      }
    }
  } else if (req.has_header("If-Modified-Since")) {
    auto val = req.get_header_value("If-Modified-Since");
    auto t = detail::parse_http_date(val);

    if (t != static_cast<time_t>(-1) && mtime <= t) {
      res.status = StatusCode::NotModified_304;
      return true;
    }
  }
  return false;
}

bool Server::check_if_range(Request &req, const std::string &etag,
                                   time_t mtime) const {
  // Handle If-Range for partial content requests (RFC 9110
  // Section 13.1.5). If-Range is only evaluated when Range header is
  // present. If the validator matches, serve partial content; otherwise
  // serve full content.
  if (!req.ranges.empty() && req.has_header("If-Range")) {
    auto val = req.get_header_value("If-Range");

    auto is_valid_range = [&]() {
      if (detail::is_strong_etag(val)) {
        // RFC 9110 Section 13.1.5: If-Range requires strong ETag
        // comparison.
        return (!etag.empty() && val == etag);
      } else if (detail::is_weak_etag(val)) {
        // Weak ETags are not valid for If-Range (RFC 9110 Section 13.1.5)
        return false;
      } else {
        // HTTP-date comparison
        auto t = detail::parse_http_date(val);
        return (t != static_cast<time_t>(-1) && mtime <= t);
      }
    };

    if (!is_valid_range()) {
      // Validator doesn't match: ignore Range and serve full content
      req.ranges.clear();
      return false;
    }
  }

  return true;
}

socket_t
Server::create_server_socket(const std::string &host, int port,
                             int socket_flags,
                             SocketOptions socket_options) const {
  return detail::create_socket(
      host, std::string(), port, address_family_, socket_flags, tcp_nodelay_,
      ipv6_v6only_, std::move(socket_options),
      [&](socket_t sock, struct addrinfo &ai, bool & /*quit*/) -> bool {
        if (::bind(sock, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen))) {
          output_error_log(Error::BindIPAddress, nullptr);
          return false;
        }
        if (::listen(sock, CPPHTTPLIB_LISTEN_BACKLOG)) {
          output_error_log(Error::Listen, nullptr);
          return false;
        }
        return true;
      });
}

int Server::bind_internal(const std::string &host, int port,
                                 int socket_flags) {
  if (is_decommissioned) { return -1; }

  if (!is_valid()) { return -1; }

  svr_sock_ = create_server_socket(host, port, socket_flags, socket_options_);
  if (svr_sock_ == INVALID_SOCKET) { return -1; }

  if (port == 0) {
    struct sockaddr_storage addr;
    socklen_t addr_len = sizeof(addr);
    if (getsockname(svr_sock_, reinterpret_cast<struct sockaddr *>(&addr),
                    &addr_len) == -1) {
      output_error_log(Error::GetSockName, nullptr);
      return -1;
    }
    if (addr.ss_family == AF_INET) {
      return ntohs(reinterpret_cast<struct sockaddr_in *>(&addr)->sin_port);
    } else if (addr.ss_family == AF_INET6) {
      return ntohs(reinterpret_cast<struct sockaddr_in6 *>(&addr)->sin6_port);
    } else {
      output_error_log(Error::UnsupportedAddressFamily, nullptr);
      return -1;
    }
  } else {
    return port;
  }
}

bool Server::listen_internal() {
  if (is_decommissioned) { return false; }

  auto ret = true;
  is_running_ = true;
  auto se = detail::scope_exit([&]() { is_running_ = false; });

  if (start_handler_) { start_handler_(); }

  {
    std::unique_ptr<TaskQueue> task_queue(new_task_queue());

    while (svr_sock_ != INVALID_SOCKET) {
#ifndef _WIN32
      if (idle_interval_sec_ > 0 || idle_interval_usec_ > 0) {
#endif
        auto val = detail::select_read(svr_sock_, idle_interval_sec_,
                                       idle_interval_usec_);
        if (val == 0) { // Timeout
          task_queue->on_idle();
          continue;
        }
#ifndef _WIN32
      }
#endif

#if defined _WIN32
      // sockets connected via WASAccept inherit flags NO_HANDLE_INHERIT,
      // OVERLAPPED
      socket_t sock = WSAAccept(svr_sock_, nullptr, nullptr, nullptr, 0);
#elif defined SOCK_CLOEXEC
      socket_t sock = accept4(svr_sock_, nullptr, nullptr, SOCK_CLOEXEC);
#else
      socket_t sock = accept(svr_sock_, nullptr, nullptr);
#endif

      if (sock == INVALID_SOCKET) {
        if (errno == EMFILE) {
          // The per-process limit of open file descriptors has been reached.
          // Try to accept new connections after a short sleep.
          std::this_thread::sleep_for(std::chrono::microseconds{1});
          continue;
        } else if (errno == EINTR || errno == EAGAIN) {
          continue;
        }
        if (svr_sock_ != INVALID_SOCKET) {
          detail::close_socket(svr_sock_);
          ret = false;
          output_error_log(Error::Connection, nullptr);
        } else {
          ; // The server socket was closed by user.
        }
        break;
      }

      detail::set_socket_opt_time(sock, SOL_SOCKET, SO_RCVTIMEO,
                                  read_timeout_sec_, read_timeout_usec_);
      detail::set_socket_opt_time(sock, SOL_SOCKET, SO_SNDTIMEO,
                                  write_timeout_sec_, write_timeout_usec_);

      if (tcp_nodelay_) { set_socket_opt(sock, IPPROTO_TCP, TCP_NODELAY, 1); }

      if (!task_queue->enqueue(
              [this, sock]() { process_and_close_socket(sock); })) {
        output_error_log(Error::ResourceExhaustion, nullptr);
        detail::shutdown_socket(sock);
        detail::close_socket(sock);
      }
    }

    task_queue->shutdown();
  }

  is_decommissioned = !ret;
  return ret;
}

bool Server::routing(Request &req, Response &res, Stream &strm) {
  if (pre_routing_handler_ &&
      pre_routing_handler_(req, res) == HandlerResponse::Handled) {
    return true;
  }

  // File handler
  if ((req.method == "GET" || req.method == "HEAD") &&
      handle_file_request(req, res)) {
    return true;
  }

  if (detail::expect_content(req)) {
    // Content reader handler
    {
      // Track whether the ContentReader was aborted due to the decompressed
      // payload exceeding `payload_max_length_`.
      // The user handler runs after the lambda returns, so we must restore the
      // 413 status if the handler overwrites it.
      bool content_reader_payload_too_large = false;

      ContentReader reader(
          [&](ContentReceiver receiver) {
            auto result = read_content_with_content_receiver(
                strm, req, res, std::move(receiver), nullptr, nullptr);
            if (!result) {
              output_error_log(Error::Read, &req);
              if (res.status == StatusCode::PayloadTooLarge_413) {
                content_reader_payload_too_large = true;
              }
            }
            return result;
          },
          [&](FormDataHeader header, ContentReceiver receiver) {
            auto result = read_content_with_content_receiver(
                strm, req, res, nullptr, std::move(header),
                std::move(receiver));
            if (!result) {
              output_error_log(Error::Read, &req);
              if (res.status == StatusCode::PayloadTooLarge_413) {
                content_reader_payload_too_large = true;
              }
            }
            return result;
          });

      bool dispatched = false;
      if (req.method == "POST") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), post_handlers_for_content_reader_);
      } else if (req.method == "PUT") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), put_handlers_for_content_reader_);
      } else if (req.method == "PATCH") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), patch_handlers_for_content_reader_);
      } else if (req.method == "DELETE") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), delete_handlers_for_content_reader_);
      }

      if (dispatched) {
        if (content_reader_payload_too_large) {
          // Enforce the limit: override any status the handler may have set
          // and return false so the error path sends a plain 413 response.
          res.status = StatusCode::PayloadTooLarge_413;
          res.body.clear();
          res.content_length_ = 0;
          res.content_provider_ = nullptr;
          return false;
        }
        return true;
      }
    }

    // NOTE: `req.body` is not read here. For a regular handler the body is
    // read inside dispatch_request(), after the route has matched and the
    // pre-request handler has approved the request, so that a rejected
    // request (e.g. failed authentication) never forces us to buffer a
    // potentially large body.
  }

  // Regular handler
  if (req.method == "GET" || req.method == "HEAD") {
    return dispatch_request(req, res, get_handlers_, strm);
  } else if (req.method == "POST") {
    return dispatch_request(req, res, post_handlers_, strm);
  } else if (req.method == "PUT") {
    return dispatch_request(req, res, put_handlers_, strm);
  } else if (req.method == "DELETE") {
    return dispatch_request(req, res, delete_handlers_, strm);
  } else if (req.method == "OPTIONS") {
    return dispatch_request(req, res, options_handlers_, strm);
  } else if (req.method == "PATCH") {
    return dispatch_request(req, res, patch_handlers_, strm);
  }

  res.status = StatusCode::BadRequest_400;
  return false;
}

bool Server::dispatch_request(Request &req, Response &res,
                                     const Handlers &handlers, Stream &strm) {
  for (const auto &x : handlers) {
    const auto &matcher = x.first;
    const auto &handler = x.second;

    if (matcher->match(req)) {
      req.matched_route = matcher->pattern();

      // Run the pre-request handler before reading the body so a rejected
      // request (e.g. failed authentication) never forces us to buffer a
      // potentially large body. `req.matched_route` is available here.
      if (pre_request_handler_ &&
          pre_request_handler_(req, res) == HandlerResponse::Handled) {
        return true;
      }

      // The route matched and the request was approved; read the body now.
      if (detail::expect_content(req) && !read_content(strm, req, res)) {
        output_error_log(Error::Read, &req);
        return false;
      }

      handler(req, res);
      return true;
    }
  }
  return false;
}

void Server::apply_ranges(const Request &req, Response &res,
                                 std::string &content_type,
                                 std::string &boundary) const {
  if (req.ranges.size() > 1 && res.status == StatusCode::PartialContent_206) {
    auto it = res.headers.find("Content-Type");
    if (it != res.headers.end()) {
      content_type = it->second;
      res.headers.erase(it);
    }

    boundary = detail::make_multipart_data_boundary();

    res.set_header("Content-Type",
                   "multipart/byteranges; boundary=" + boundary);
  }

  auto type = detail::encoding_type(req, res);

  if (res.body.empty()) {
    if (res.content_length_ > 0) {
      size_t length = 0;
      if (req.ranges.empty() || res.status != StatusCode::PartialContent_206) {
        length = res.content_length_;
      } else if (req.ranges.size() == 1) {
        auto offset_and_length = detail::get_range_offset_and_length(
            req.ranges[0], res.content_length_);

        length = offset_and_length.second;

        auto content_range = detail::make_content_range_header_field(
            offset_and_length, res.content_length_);
        res.set_header("Content-Range", content_range);
      } else {
        length = detail::get_multipart_ranges_data_length(
            req, boundary, content_type, res.content_length_);
      }
      res.set_header("Content-Length", std::to_string(length));
    } else {
      if (res.content_provider_) {
        if (res.is_chunked_content_provider_) {
          res.set_header("Transfer-Encoding", "chunked");
          if (type != detail::EncodingType::None) {
            res.set_header("Content-Encoding", detail::encoding_name(type));
            res.set_header("Vary", "Accept-Encoding");
          }
        }
      }
    }
  } else {
    if (req.ranges.empty() || res.status != StatusCode::PartialContent_206) {
      ;
    } else if (req.ranges.size() == 1) {
      auto offset_and_length =
          detail::get_range_offset_and_length(req.ranges[0], res.body.size());
      auto offset = offset_and_length.first;
      auto length = offset_and_length.second;

      auto content_range = detail::make_content_range_header_field(
          offset_and_length, res.body.size());
      res.set_header("Content-Range", content_range);

      assert(offset + length <= res.body.size());
      res.body = res.body.substr(offset, length);
    } else {
      std::string data;
      detail::make_multipart_ranges_data(req, res, boundary, content_type,
                                         res.body.size(), data);
      res.body.swap(data);
    }

    if (type != detail::EncodingType::None) {
      output_pre_compression_log(req, res);

      if (auto compressor = detail::make_compressor(type)) {
        std::string compressed;
        if (compressor->compress(res.body.data(), res.body.size(), true,
                                 [&](const char *data, size_t data_len) {
                                   compressed.append(data, data_len);
                                   return true;
                                 })) {
          res.body.swap(compressed);
          res.set_header("Content-Encoding", detail::encoding_name(type));
          res.set_header("Vary", "Accept-Encoding");
        }
      }
    }

    res.content_length_ = res.body.size();
    res.set_header("Content-Length", std::to_string(res.content_length_));
  }
}

bool Server::dispatch_request_for_content_reader(
    Request &req, Response &res, ContentReader content_reader,
    const HandlersForContentReader &handlers) const {
  for (const auto &x : handlers) {
    const auto &matcher = x.first;
    const auto &handler = x.second;

    if (matcher->match(req)) {
      req.matched_route = matcher->pattern();
      if (!pre_request_handler_ ||
          pre_request_handler_(req, res) != HandlerResponse::Handled) {
        handler(req, res, content_reader);
      }
      return true;
    }
  }
  return false;
}

std::string
get_client_ip(const std::string &x_forwarded_for,
              const std::vector<std::string> &trusted_proxies) {
  // X-Forwarded-For is a comma-separated list per RFC 7239
  std::vector<std::string> ip_list;
  detail::split(x_forwarded_for.data(),
                x_forwarded_for.data() + x_forwarded_for.size(), ',',
                [&](const char *b, const char *e) {
                  auto r = detail::trim(b, e, 0, static_cast<size_t>(e - b));
                  ip_list.emplace_back(std::string(b + r.first, b + r.second));
                });

  // A malformed X-Forwarded-For (empty, comma-only, whitespace-only) yields
  // no segments. Signal "no client IP derived" with an empty string so the
  // caller can fall back to the connection-level remote address.
  if (ip_list.empty()) { return std::string(); }

  // Each hop appends the address it received the request from, so the rightmost
  // entries are the ones written by our own infrastructure while the leftmost
  // are whatever the original client chose to send. Walk from the right and
  // skip trusted proxies; the first address that is not a trusted proxy is the
  // furthest point still attributable to a real hop, i.e. the client. Scanning
  // from the left instead lets a client forge an arbitrary address by following
  // it with a trusted proxy's address, which the left-to-right scan then
  // returned as the client.
  for (size_t i = ip_list.size(); i-- > 0;) {
    const auto &ip = ip_list[i];

    auto is_trusted_proxy =
        std::any_of(trusted_proxies.begin(), trusted_proxies.end(),
                    [&](const std::string &proxy) { return ip == proxy; });

    if (!is_trusted_proxy) { return ip; }
  }

  // Every hop was a trusted proxy; fall back to the first entry.
  return ip_list.front();
}

bool
Server::process_request(Stream &strm, const std::string &remote_addr,
                        int remote_port, const std::string &local_addr,
                        int local_port, bool close_connection,
                        bool &connection_closed,
                        const std::function<void(Request &)> &setup_request,
                        bool *websocket_upgraded) {
  std::array<char, 2048> buf{};

  detail::stream_line_reader line_reader(strm, buf.data(), buf.size());

  // Connection has been closed on client
  if (!line_reader.getline()) { return false; }

  Request req;
  req.start_time_ = std::chrono::steady_clock::now();
  req.remote_addr = remote_addr;
  req.remote_port = remote_port;
  req.local_addr = local_addr;
  req.local_port = local_port;

  Response res;
  res.version = "HTTP/1.1";
  res.headers = default_headers_;

  // Request line and headers
  if (!parse_request_line(line_reader.ptr(), req)) {
    res.status = StatusCode::BadRequest_400;
    output_error_log(Error::InvalidRequestLine, &req);
    return write_response(strm, close_connection, req, res);
  }

  // Request headers
  if (!detail::read_headers(strm, req.headers)) {
    res.status = StatusCode::BadRequest_400;
    output_error_log(Error::InvalidHeaders, &req);
    return write_response(strm, close_connection, req, res);
  }

  // RFC 9112 §6.3: Reject requests with both a non-zero Content-Length and
  // any Transfer-Encoding to prevent request smuggling. Content-Length: 0 is
  // tolerated for compatibility with existing clients.
  if (req.get_header_value_u64("Content-Length") > 0 &&
      req.has_header("Transfer-Encoding")) {
    connection_closed = true;
    res.status = StatusCode::BadRequest_400;
    return write_response(strm, close_connection, req, res);
  }

  // Check if the request URI doesn't exceed the limit
  if (req.target.size() > CPPHTTPLIB_REQUEST_URI_MAX_LENGTH) {
    connection_closed = true;
    res.status = StatusCode::UriTooLong_414;
    output_error_log(Error::ExceedUriMaxLength, &req);
    return write_response(strm, close_connection, req, res);
  }

  if (req.get_header_value("Connection") == "close") {
    connection_closed = true;
  }

  if (req.version == "HTTP/1.0" &&
      req.get_header_value("Connection") != "Keep-Alive") {
    connection_closed = true;
  }

  // Only honor X-Forwarded-For if the peer on the actual TCP connection is
  // itself a trusted proxy. Otherwise any direct client could spoof
  // remote_addr simply by sending an arbitrary X-Forwarded-For header.
  auto is_trusted_peer = std::any_of(
      trusted_proxies_.begin(), trusted_proxies_.end(),
      [&](const std::string &proxy) { return proxy == remote_addr; });

  if (is_trusted_peer && req.has_header("X-Forwarded-For")) {
    auto x_forwarded_for = req.get_header_value("X-Forwarded-For");
    auto derived = get_client_ip(x_forwarded_for, trusted_proxies_);
    req.remote_addr = derived.empty() ? remote_addr : derived;
  } else {
    req.remote_addr = remote_addr;
  }
  req.remote_port = remote_port;

  req.local_addr = local_addr;
  req.local_port = local_port;

  if (req.has_header("Accept")) {
    const auto &accept_header = req.get_header_value("Accept");
    if (!detail::parse_accept_header(accept_header, req.accept_content_types)) {
      connection_closed = true;
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::HTTPParsing, &req);
      return write_response(strm, close_connection, req, res);
    }
  }

  if (req.has_header("Range")) {
    const auto &range_header_value = req.get_header_value("Range");
    if (!detail::parse_range_header(range_header_value, req.ranges)) {
      connection_closed = true;
      res.status = StatusCode::RangeNotSatisfiable_416;
      output_error_log(Error::InvalidRangeHeader, &req);
      return write_response(strm, close_connection, req, res);
    }
  }

  if (setup_request) { setup_request(req); }

  if (req.get_header_value("Expect") == "100-continue") {
    int status = StatusCode::Continue_100;
    if (expect_100_continue_handler_) {
      status = expect_100_continue_handler_(req, res);
    }
    switch (status) {
    case StatusCode::Continue_100:
    case StatusCode::ExpectationFailed_417:
      detail::write_response_line(strm, status);
      strm.write("\r\n");
      break;
    default:
      connection_closed = true;
      return write_response(strm, true, req, res);
    }
  }

  // Setup `is_connection_closed` method
  auto sock = strm.socket();
  req.is_connection_closed = [sock]() {
    return !detail::is_socket_alive(sock);
  };

  // WebSocket upgrade
  // Check pre_routing_handler_ before upgrading so that authentication
  // and other middleware can reject the request with an HTTP response
  // (e.g., 401) before the protocol switches.
  if (detail::is_websocket_upgrade(req)) {
    if (pre_routing_handler_ &&
        pre_routing_handler_(req, res) == HandlerResponse::Handled) {
      if (res.status == -1) { res.status = StatusCode::OK_200; }
      return write_response(strm, close_connection, req, res);
    }
    // Find matching WebSocket handler
    for (const auto &entry : websocket_handlers_) {
      if (entry.matcher->match(req)) {
        // Compute accept key
        auto client_key = req.get_header_value("Sec-WebSocket-Key");
        auto accept_key = detail::websocket_accept_key(client_key);

        // Negotiate subprotocol
        std::string selected_subprotocol;
        if (entry.sub_protocol_selector) {
          auto protocol_header = req.get_header_value("Sec-WebSocket-Protocol");
          if (!protocol_header.empty()) {
            std::vector<std::string> protocols;
            std::istringstream iss(protocol_header);
            std::string token;
            while (std::getline(iss, token, ',')) {
              // Trim whitespace
              auto start = token.find_first_not_of(' ');
              auto end = token.find_last_not_of(' ');
              if (start != std::string::npos) {
                protocols.push_back(token.substr(start, end - start + 1));
              }
            }
            selected_subprotocol = entry.sub_protocol_selector(protocols);
          }
        }

        // Send 101 Switching Protocols
        std::string handshake_response = "HTTP/1.1 101 Switching Protocols\r\n"
                                         "Upgrade: websocket\r\n"
                                         "Connection: Upgrade\r\n"
                                         "Sec-WebSocket-Accept: " +
                                         accept_key + "\r\n";
        if (!selected_subprotocol.empty()) {
          if (!detail::fields::is_field_value(selected_subprotocol)) {
            return false;
          }
          handshake_response +=
              "Sec-WebSocket-Protocol: " + selected_subprotocol + "\r\n";
        }
        handshake_response += "\r\n";
        if (strm.write(handshake_response.data(), handshake_response.size()) <
            0) {
          return false;
        }

        connection_closed = true;
        if (websocket_upgraded) { *websocket_upgraded = true; }

        {
          // Use WebSocket-specific read timeout instead of HTTP timeout
          strm.set_read_timeout(CPPHTTPLIB_WEBSOCKET_READ_TIMEOUT_SECOND, 0);
          ws::WebSocket ws(strm, req, true, websocket_ping_interval_sec_,
                           websocket_max_missed_pongs_);
          entry.handler(req, ws);
        }
        return true;
      }
    }
    // No matching handler - fall through to 404
  }

  // Routing
  auto routed = false;
#ifdef CPPHTTPLIB_NO_EXCEPTIONS
  routed = routing(req, res, strm);
#else
  try {
    routed = routing(req, res, strm);
  } catch (std::exception &) {
    if (exception_handler_) {
      auto ep = std::current_exception();
      exception_handler_(req, res, ep);
      routed = true;
    } else {
      res.status = StatusCode::InternalServerError_500;
    }
  } catch (...) {
    if (exception_handler_) {
      auto ep = std::current_exception();
      exception_handler_(req, res, ep);
      routed = true;
    } else {
      res.status = StatusCode::InternalServerError_500;
    }
  }
#endif
  auto ret = false;
  if (routed) {
    if (res.status == -1) {
      res.status = req.ranges.empty() ? StatusCode::OK_200
                                      : StatusCode::PartialContent_206;
    }

    // Serve file content by using a content provider
    auto file_open_error = false;
    if (!res.file_content_path_.empty()) {
      const auto &path = res.file_content_path_;
      auto mm = std::make_shared<detail::mmap>(path.c_str());
      if (!mm->is_open()) {
        res.body.clear();
        res.content_length_ = 0;
        res.content_provider_ = nullptr;
        res.status = StatusCode::NotFound_404;
        output_error_log(Error::OpenFile, &req);
        file_open_error = true;
      } else {
        auto content_type = res.file_content_content_type_;
        if (content_type.empty()) {
          content_type = detail::find_content_type(
              path, file_extension_and_mimetype_map_, default_file_mimetype_);
        }

        res.set_content_provider(
            mm->size(), content_type,
            [mm](size_t offset, size_t length, DataSink &sink) -> bool {
              sink.write(mm->data() + offset, length);
              return true;
            });
      }
    }

    if (file_open_error) {
      ret = write_response(strm, close_connection, req, res);
    } else if (detail::range_error(req, res)) {
      res.body.clear();
      res.content_length_ = 0;
      res.content_provider_ = nullptr;
      res.status = StatusCode::RangeNotSatisfiable_416;
      ret = write_response(strm, close_connection, req, res);
    } else {
      ret = write_response_with_content(strm, close_connection, req, res);
    }
  } else {
    if (res.status == -1) { res.status = StatusCode::NotFound_404; }
    ret = write_response(strm, close_connection, req, res);
  }

  // Drain any unconsumed framed body to prevent request smuggling on
  // keep-alive. Without framing there is no body to drain — reading would
  // consume the next request (issue #2450). If the response has committed the
  // connection to close, there is no next request to protect.
  if (!req.body_consumed_ && detail::has_framed_body(req)) {
    if (res.get_header_value("Connection") == "close") {
      connection_closed = true;
    } else {
      int dummy_status;
      if (!detail::read_content(
              strm, req, payload_max_length_, dummy_status, nullptr,
              [](const char *, size_t, size_t, size_t) { return true; },
              false)) {
        connection_closed = true;
      }
    }
  }

  return ret;
}

bool Server::is_valid() const { return true; }

bool Server::process_and_close_socket(socket_t sock) {
  std::string remote_addr;
  int remote_port = 0;
  detail::get_remote_ip_and_port(sock, remote_addr, remote_port);

  std::string local_addr;
  int local_port = 0;
  detail::get_local_ip_and_port(sock, local_addr, local_port);

  bool websocket_upgraded = false;
  auto ret = detail::process_server_socket(
      svr_sock_, sock, keep_alive_max_count_, keep_alive_timeout_sec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_,
      [&](Stream &strm, bool close_connection, bool &connection_closed) {
        return process_request(strm, remote_addr, remote_port, local_addr,
                               local_port, close_connection, connection_closed,
                               nullptr, &websocket_upgraded);
      });

  detail::shutdown_socket(sock);
  detail::close_socket(sock);
  return ret;
}

void Server::output_log(const Request &req, const Response &res) const {
  if (logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    logger_(req, res);
  }
}

void Server::output_pre_compression_log(const Request &req,
                                               const Response &res) const {
  if (pre_compression_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    pre_compression_logger_(req, res);
  }
}

void Server::output_error_log(const Error &err,
                                     const Request *req) const {
  if (error_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    error_logger_(err, req);
  }
}

/*
 * Group 5: ClientImpl and Client (Universal) implementation
 */
// HTTP client implementation
ClientImpl::ClientImpl(const std::string &host)
    : ClientImpl(host, 80, std::string(), std::string()) {}

ClientImpl::ClientImpl(const std::string &host, int port)
    : ClientImpl(host, port, std::string(), std::string()) {}

ClientImpl::ClientImpl(const std::string &host, int port,
                              const std::string &client_cert_path,
                              const std::string &client_key_path)
    : host_(detail::escape_abstract_namespace_unix_domain(host)), port_(port),
      client_cert_path_(client_cert_path), client_key_path_(client_key_path) {}

ClientImpl::~ClientImpl() {
  // Wait until all the requests in flight are handled.
  size_t retry_count = 10;
  while (retry_count-- > 0) {
    {
      std::lock_guard<std::mutex> guard(socket_mutex_);
      if (socket_requests_in_flight_ == 0) { break; }
    }
    std::this_thread::sleep_for(std::chrono::milliseconds{1});
  }

  std::lock_guard<std::mutex> guard(socket_mutex_);
  shutdown_socket(socket_);
  close_socket(socket_);
}

bool ClientImpl::is_valid() const { return true; }

void ClientImpl::copy_settings(const ClientImpl &rhs) {
  client_cert_path_ = rhs.client_cert_path_;
  client_key_path_ = rhs.client_key_path_;
  connection_timeout_sec_ = rhs.connection_timeout_sec_;
  read_timeout_sec_ = rhs.read_timeout_sec_;
  read_timeout_usec_ = rhs.read_timeout_usec_;
  write_timeout_sec_ = rhs.write_timeout_sec_;
  write_timeout_usec_ = rhs.write_timeout_usec_;
  max_timeout_msec_ = rhs.max_timeout_msec_;
  basic_auth_username_ = rhs.basic_auth_username_;
  basic_auth_password_ = rhs.basic_auth_password_;
  bearer_token_auth_token_ = rhs.bearer_token_auth_token_;
  keep_alive_ = rhs.keep_alive_;
  follow_location_ = rhs.follow_location_;
  path_encode_ = rhs.path_encode_;
  address_family_ = rhs.address_family_;
  tcp_nodelay_ = rhs.tcp_nodelay_;
  ipv6_v6only_ = rhs.ipv6_v6only_;
  socket_options_ = rhs.socket_options_;
  compress_ = rhs.compress_;
  decompress_ = rhs.decompress_;
  payload_max_length_ = rhs.payload_max_length_;
  has_payload_max_length_ = rhs.has_payload_max_length_;
  interface_ = rhs.interface_;
  proxy_host_ = rhs.proxy_host_;
  proxy_port_ = rhs.proxy_port_;
  proxy_basic_auth_username_ = rhs.proxy_basic_auth_username_;
  proxy_basic_auth_password_ = rhs.proxy_basic_auth_password_;
  proxy_bearer_token_auth_token_ = rhs.proxy_bearer_token_auth_token_;
  no_proxy_entries_ = rhs.no_proxy_entries_;
  logger_ = rhs.logger_;
  error_logger_ = rhs.error_logger_;

#ifdef CPPHTTPLIB_SSL_ENABLED
  digest_auth_username_ = rhs.digest_auth_username_;
  digest_auth_password_ = rhs.digest_auth_password_;
  proxy_digest_auth_username_ = rhs.proxy_digest_auth_username_;
  proxy_digest_auth_password_ = rhs.proxy_digest_auth_password_;
  ca_cert_file_path_ = rhs.ca_cert_file_path_;
  ca_cert_dir_path_ = rhs.ca_cert_dir_path_;
  server_certificate_verification_ = rhs.server_certificate_verification_;
  server_hostname_verification_ = rhs.server_hostname_verification_;
  system_ca_mode_ = rhs.system_ca_mode_;
#endif
}

bool
ClientImpl::is_proxy_enabled_for_host(const std::string &host) const {
  if (proxy_host_.empty() || proxy_port_ == -1) { return false; }
  if (no_proxy_entries_.empty()) { return true; }
  // host_ is const so its normalized form is invariant; cache it. The
  // cross-host path (setup_redirect_client passing next_host) re-normalizes.
  if (host == host_) {
    if (!host_normalized_valid_) {
      host_normalized_ = detail::normalize_target(host_);
      host_normalized_valid_ = true;
    }
    return !detail::host_matches_no_proxy(host_normalized_, no_proxy_entries_);
  }
  auto target = detail::normalize_target(host);
  return !detail::host_matches_no_proxy(target, no_proxy_entries_);
}

socket_t ClientImpl::create_client_socket(Error &error) const {
  if (is_proxy_enabled_for_host(host_)) {
    return detail::create_client_socket(
        proxy_host_, std::string(), proxy_port_, address_family_, tcp_nodelay_,
        ipv6_v6only_, socket_options_, connection_timeout_sec_,
        connection_timeout_usec_, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_, interface_, error);
  }

  // Check is custom IP specified for host_
  std::string ip;
  auto it = addr_map_.find(host_);
  if (it != addr_map_.end()) { ip = it->second; }

  return detail::create_client_socket(
      host_, ip, port_, address_family_, tcp_nodelay_, ipv6_v6only_,
      socket_options_, connection_timeout_sec_, connection_timeout_usec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, interface_, error);
}

bool ClientImpl::create_and_connect_socket(Socket &socket,
                                                  Error &error) {
  auto sock = create_client_socket(error);
  if (sock == INVALID_SOCKET) { return false; }
  socket.sock = sock;
  return true;
}

bool ClientImpl::ensure_socket_connection(Socket &socket, Error &error) {
  return create_and_connect_socket(socket, error);
}

bool ClientImpl::setup_proxy_connection(
    Socket & /*socket*/,
    std::chrono::time_point<std::chrono::steady_clock> /*start_time*/,
    Response & /*res*/, bool & /*success*/, Error & /*error*/) {
  return true;
}

void ClientImpl::shutdown_ssl(Socket & /*socket*/,
                                     bool /*shutdown_gracefully*/) {
  // If there are any requests in flight from threads other than us, then it's
  // a thread-unsafe race because individual ssl* objects are not thread-safe.
  assert(socket_requests_in_flight_ == 0 ||
         socket_requests_are_from_thread_ == std::this_thread::get_id());
}

void ClientImpl::shutdown_socket(Socket &socket) const {
  if (socket.sock == INVALID_SOCKET) { return; }
  detail::shutdown_socket(socket.sock);
}

void ClientImpl::close_socket(Socket &socket) {
  // If there are requests in flight in another thread, usually closing
  // the socket will be fine and they will simply receive an error when
  // using the closed socket, but it is still a bug since rarely the OS
  // may reassign the socket id to be used for a new socket, and then
  // suddenly they will be operating on a live socket that is different
  // than the one they intended!
  assert(socket_requests_in_flight_ == 0 ||
         socket_requests_are_from_thread_ == std::this_thread::get_id());

  // It is also a bug if this happens while SSL is still active
#ifdef CPPHTTPLIB_SSL_ENABLED
  assert(socket.ssl == nullptr);
#endif

  if (socket.sock == INVALID_SOCKET) { return; }
  detail::close_socket(socket.sock);
  socket.sock = INVALID_SOCKET;
}

void ClientImpl::disconnect(bool gracefully) {
  shutdown_ssl(socket_, gracefully);
  shutdown_socket(socket_);
  close_socket(socket_);
}

bool ClientImpl::read_response_line(Stream &strm, const Request &req,
                                           Response &res,
                                           bool skip_100_continue) const {
  std::array<char, 2048> buf{};

  detail::stream_line_reader line_reader(strm, buf.data(), buf.size());

  if (!line_reader.getline()) { return false; }

#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
  thread_local const std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r?\n");
#else
  thread_local const std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r\n");
#endif

  std::cmatch m;
  if (!std::regex_match(line_reader.ptr(), m, re)) {
    return req.method == "CONNECT";
  }
  res.version = std::string(m[1]);
  res.status = std::stoi(std::string(m[2]));
  res.reason = std::string(m[3]);

  // Ignore '100 Continue' (only when not using Expect: 100-continue explicitly)
  while (skip_100_continue && res.status == StatusCode::Continue_100) {
    if (!line_reader.getline()) { return false; } // CRLF
    if (!line_reader.getline()) { return false; } // next response line

    if (!std::regex_match(line_reader.ptr(), m, re)) { return false; }
    res.version = std::string(m[1]);
    res.status = std::stoi(std::string(m[2]));
    res.reason = std::string(m[3]);
  }

  return true;
}

bool ClientImpl::send(Request &req, Response &res, Error &error) {
  std::lock_guard<std::recursive_mutex> request_mutex_guard(request_mutex_);
  auto ret = send_(req, res, error);
  if (error == Error::SSLPeerCouldBeClosed_) {
    assert(!ret);
    ret = send_(req, res, error);
    // If still failing with SSLPeerCouldBeClosed_, convert to Read error
    if (error == Error::SSLPeerCouldBeClosed_) { error = Error::Read; }
  }
  return ret;
}

bool ClientImpl::send_(Request &req, Response &res, Error &error) {
  {
    std::lock_guard<std::mutex> guard(socket_mutex_);

    // Set this to false immediately - if it ever gets set to true by the end
    // of the request, we know another thread instructed us to close the
    // socket.
    socket_should_be_closed_when_request_is_done_ = false;

    auto is_alive = false;
    if (socket_.is_open()) {
      is_alive = detail::is_socket_alive(socket_.sock);

#ifdef CPPHTTPLIB_SSL_ENABLED
      if (is_alive && is_ssl()) {
        if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
          is_alive = false;
        }
      }
#endif

      if (!is_alive) {
        // Peer seems gone — non-graceful shutdown to avoid SIGPIPE.
        disconnect(/*gracefully=*/false);
      }
    }

    if (!is_alive) {
      if (!ensure_socket_connection(socket_, error)) {
        output_error_log(error, &req);
        return false;
      }

      {
        auto success = true;
        if (!setup_proxy_connection(socket_, req.start_time_, res, success,
                                    error)) {
          if (!success) { output_error_log(error, &req); }
          return success;
        }
      }
    }

    // Mark the current socket as being in use so that it cannot be closed by
    // anyone else while this request is ongoing, even though we will be
    // releasing the mutex.
    if (socket_requests_in_flight_ > 1) {
      assert(socket_requests_are_from_thread_ == std::this_thread::get_id());
    }
    socket_requests_in_flight_ += 1;
    socket_requests_are_from_thread_ = std::this_thread::get_id();
  }

  for (const auto &header : default_headers_) {
    if (req.headers.find(header.first) == req.headers.end()) {
      req.headers.insert(header);
    }
  }

  auto ret = false;
  auto close_connection = !keep_alive_;

  auto se = detail::scope_exit([&]() {
    // Briefly lock mutex in order to mark that a request is no longer ongoing
    std::lock_guard<std::mutex> guard(socket_mutex_);
    socket_requests_in_flight_ -= 1;
    if (socket_requests_in_flight_ <= 0) {
      assert(socket_requests_in_flight_ == 0);
      socket_requests_are_from_thread_ = std::thread::id();
    }

    if (socket_should_be_closed_when_request_is_done_ || close_connection ||
        !ret) {
      disconnect(/*gracefully=*/true);
    }
  });

  ret = process_socket(socket_, req.start_time_, [&](Stream &strm) {
    return handle_request(strm, req, res, close_connection, error);
  });

  if (!ret) {
    if (error == Error::Success) {
      error = Error::Unknown;
      output_error_log(error, &req);
    }
  }

  return ret;
}

Result ClientImpl::send(const Request &req) {
  auto req2 = req;
  return send_(std::move(req2));
}

Result ClientImpl::send_(Request &&req) {
  auto res = detail::make_unique<Response>();
  auto error = Error::Success;
  auto ret = send(req, *res, error);
#ifdef CPPHTTPLIB_SSL_ENABLED
  return Result{ret ? std::move(res) : nullptr, error, std::move(req.headers),
                last_ssl_error_, last_backend_error_};
#else
  return Result{ret ? std::move(res) : nullptr, error, std::move(req.headers)};
#endif
}

void ClientImpl::prepare_default_headers(Request &r, bool for_stream,
                                                const std::string &ct) {
  (void)for_stream;
  for (const auto &header : default_headers_) {
    if (!r.has_header(header.first)) { r.headers.insert(header); }
  }

  if (!r.has_header("Host")) {
    if (address_family_ == AF_UNIX) {
      r.headers.emplace("Host", "localhost");
    } else {
      r.headers.emplace(
          "Host", detail::make_host_and_port_string(host_, port_, is_ssl()));
    }
  }

  if (!r.has_header("Accept")) { r.headers.emplace("Accept", "*/*"); }

  if (!r.content_receiver) {
    if (!r.has_header("Accept-Encoding")) {
      std::string accept_encoding;
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
      accept_encoding = "br";
#endif
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
      if (!accept_encoding.empty()) { accept_encoding += ", "; }
      accept_encoding += "gzip, deflate";
#endif
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
      if (!accept_encoding.empty()) { accept_encoding += ", "; }
      accept_encoding += "zstd";
#endif
      r.set_header("Accept-Encoding", accept_encoding);
    }

#ifndef CPPHTTPLIB_NO_DEFAULT_USER_AGENT
    if (!r.has_header("User-Agent")) {
      auto agent = std::string("cpp-httplib/") + CPPHTTPLIB_VERSION;
      r.set_header("User-Agent", agent);
    }
#endif
  }

  if (!r.body.empty()) {
    if (!ct.empty() && !r.has_header("Content-Type")) {
      r.headers.emplace("Content-Type", ct);
    }
    if (!r.has_header("Content-Length")) {
      r.headers.emplace("Content-Length", std::to_string(r.body.size()));
    }
  }
}

ClientImpl::StreamHandle
ClientImpl::open_stream(const std::string &method, const std::string &path,
                        const Params &params, const Headers &headers,
                        const std::string &body,
                        const std::string &content_type) {
  StreamHandle handle;
  handle.response = detail::make_unique<Response>();
  handle.error = Error::Success;

  auto query_path = params.empty() ? path : append_query_params(path, params);
  handle.connection_ = detail::make_unique<ClientConnection>();

  {
    std::lock_guard<std::mutex> guard(socket_mutex_);

    auto is_alive = false;
    if (socket_.is_open()) {
      is_alive = detail::is_socket_alive(socket_.sock);
#ifdef CPPHTTPLIB_SSL_ENABLED
      if (is_alive && is_ssl()) {
        if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
          is_alive = false;
        }
      }
#endif
      if (!is_alive) { disconnect(/*gracefully=*/false); }
    }

    if (!is_alive) {
      if (!ensure_socket_connection(socket_, handle.error)) {
        handle.response.reset();
        return handle;
      }

      {
        auto success = true;
        auto start_time = std::chrono::steady_clock::now();
        if (!setup_proxy_connection(socket_, start_time, *handle.response,
                                    success, handle.error)) {
          if (!success) { handle.response.reset(); }
          return handle;
        }
      }
    }

    transfer_socket_ownership_to_handle(handle);
  }

#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl() && handle.connection_->session) {
    handle.socket_stream_ = detail::make_unique<detail::SSLSocketStream>(
        handle.connection_->sock, handle.connection_->session,
        read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
        write_timeout_usec_);
  } else {
    handle.socket_stream_ = detail::make_unique<detail::SocketStream>(
        handle.connection_->sock, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_);
  }
#else
  handle.socket_stream_ = detail::make_unique<detail::SocketStream>(
      handle.connection_->sock, read_timeout_sec_, read_timeout_usec_,
      write_timeout_sec_, write_timeout_usec_);
#endif
  handle.stream_ = handle.socket_stream_.get();

  Request req;
  req.method = method;
  req.path = query_path;
  req.headers = headers;
  req.body = body;

  prepare_default_headers(req, true, content_type);

  auto &strm = *handle.stream_;
  if (detail::write_request_line(strm, req.method, req.path) < 0) {
    handle.error = Error::Write;
    handle.response.reset();
    return handle;
  }

  if (!detail::check_and_write_headers(strm, req.headers, header_writer_,
                                       handle.error)) {
    handle.response.reset();
    return handle;
  }

  if (!body.empty()) {
    if (strm.write(body.data(), body.size()) < 0) {
      handle.error = Error::Write;
      handle.response.reset();
      return handle;
    }
  }

  if (!read_response_line(strm, req, *handle.response) ||
      !detail::read_headers(strm, handle.response->headers)) {
    handle.error = Error::Read;
    handle.response.reset();
    return handle;
  }

  handle.body_reader_.stream = handle.stream_;
  handle.body_reader_.payload_max_length = payload_max_length_;

  if (handle.response->has_header("Content-Length")) {
    bool is_invalid = false;
    auto content_length = detail::get_header_value_u64(
        handle.response->headers, "Content-Length", 0, 0, is_invalid);
    if (is_invalid) {
      handle.error = Error::Read;
      handle.response.reset();
      return handle;
    }
    handle.body_reader_.has_content_length = true;
    handle.body_reader_.content_length = content_length;
  }

  handle.body_reader_.chunked =
      detail::is_chunked_transfer_encoding(handle.response->headers);

  auto content_encoding = handle.response->get_header_value("Content-Encoding");
  if (!content_encoding.empty()) {
    handle.decompressor_ = detail::create_decompressor(content_encoding);
  }

  return handle;
}

ssize_t ClientImpl::StreamHandle::read(char *buf, size_t len) {
  if (!is_valid() || !response) { return -1; }

  if (decompressor_) { return read_with_decompression(buf, len); }
  auto n = detail::read_body_content(stream_, body_reader_, buf, len);

  if (n <= 0 && body_reader_.chunked && !trailers_parsed_ && stream_) {
    trailers_parsed_ = true;
    if (body_reader_.chunked_decoder) {
      if (!body_reader_.chunked_decoder->parse_trailers_into(
              response->trailers, response->headers)) {
        return n;
      }
    } else {
      detail::ChunkedDecoder dec(*stream_);
      if (!dec.parse_trailers_into(response->trailers, response->headers)) {
        return n;
      }
    }
  }

  return n;
}

ssize_t ClientImpl::StreamHandle::read_with_decompression(char *buf,
                                                                 size_t len) {
  if (decompress_offset_ < decompress_buffer_.size()) {
    auto available = decompress_buffer_.size() - decompress_offset_;
    auto to_copy = (std::min)(len, available);
    std::memcpy(buf, decompress_buffer_.data() + decompress_offset_, to_copy);
    decompress_offset_ += to_copy;
    decompressed_bytes_read_ += to_copy;
    return static_cast<ssize_t>(to_copy);
  }

  decompress_buffer_.clear();
  decompress_offset_ = 0;

  constexpr size_t kDecompressionBufferSize = 8192;
  char compressed_buf[kDecompressionBufferSize];

  while (true) {
    auto n = detail::read_body_content(stream_, body_reader_, compressed_buf,
                                       sizeof(compressed_buf));

    if (n <= 0) { return n; }

    bool decompress_ok = decompressor_->decompress(
        compressed_buf, static_cast<size_t>(n),
        [this](const char *data, size_t data_len) {
          decompress_buffer_.append(data, data_len);
          auto limit = body_reader_.payload_max_length;
          if (decompressed_bytes_read_ + decompress_buffer_.size() > limit) {
            return false;
          }
          return true;
        });

    if (!decompress_ok) {
      body_reader_.last_error = Error::Read;
      return -1;
    }

    if (!decompress_buffer_.empty()) { break; }
  }

  auto to_copy = (std::min)(len, decompress_buffer_.size());
  std::memcpy(buf, decompress_buffer_.data(), to_copy);
  decompress_offset_ = to_copy;
  decompressed_bytes_read_ += to_copy;
  return static_cast<ssize_t>(to_copy);
}

void ClientImpl::StreamHandle::parse_trailers_if_needed() {
  if (!response || !stream_ || !body_reader_.chunked || trailers_parsed_) {
    return;
  }

  trailers_parsed_ = true;

  const auto bufsiz = 128;
  char line_buf[bufsiz];
  detail::stream_line_reader line_reader(*stream_, line_buf, bufsiz);

  if (!line_reader.getline()) { return; }

  if (!detail::parse_trailers(line_reader, response->trailers,
                              response->headers)) {
    return;
  }
}

namespace detail {

ChunkedDecoder::ChunkedDecoder(Stream &s) : strm(s) {}

ssize_t ChunkedDecoder::read_payload(char *buf, size_t len,
                                            size_t &out_chunk_offset,
                                            size_t &out_chunk_total) {
  if (finished) { return 0; }

  if (chunk_remaining == 0) {
    stream_line_reader lr(strm, line_buf, sizeof(line_buf));
    if (!lr.getline()) { return -1; }

    // RFC 9112 §7.1: chunk-size = 1*HEXDIG
    const char *p = lr.ptr();
    int v = 0;
    if (!is_hex(*p, v)) { return -1; }

    size_t chunk_len = 0;
    constexpr size_t chunk_len_max = (std::numeric_limits<size_t>::max)();
    for (; is_hex(*p, v); ++p) {
      if (chunk_len > (chunk_len_max >> 4)) { return -1; }
      chunk_len = (chunk_len << 4) | static_cast<size_t>(v);
    }

    while (is_space_or_tab(*p)) {
      ++p;
    }
    if (*p != '\0' && *p != ';' && *p != '\r' && *p != '\n') { return -1; }

    if (chunk_len == 0) {
      chunk_remaining = 0;
      finished = true;
      out_chunk_offset = 0;
      out_chunk_total = 0;
      return 0;
    }

    chunk_remaining = chunk_len;
    last_chunk_total = chunk_remaining;
    last_chunk_offset = 0;
  }

  auto to_read = (std::min)(chunk_remaining, len);
  auto n = strm.read(buf, to_read);
  if (n <= 0) { return -1; }

  auto offset_before = last_chunk_offset;
  last_chunk_offset += static_cast<size_t>(n);
  chunk_remaining -= static_cast<size_t>(n);

  out_chunk_offset = offset_before;
  out_chunk_total = last_chunk_total;

  if (chunk_remaining == 0) {
    stream_line_reader lr(strm, line_buf, sizeof(line_buf));
    if (!lr.getline()) { return -1; }
    if (std::strcmp(lr.ptr(), "\r\n") != 0) { return -1; }
  }

  return n;
}

bool ChunkedDecoder::parse_trailers_into(Headers &dest,
                                                const Headers &src_headers) {
  stream_line_reader lr(strm, line_buf, sizeof(line_buf));
  if (!lr.getline()) { return false; }
  return parse_trailers(lr, dest, src_headers);
}

} // namespace detail

void
ClientImpl::transfer_socket_ownership_to_handle(StreamHandle &handle) {
  handle.connection_->sock = socket_.sock;
#ifdef CPPHTTPLIB_SSL_ENABLED
  handle.connection_->session = socket_.ssl;
  socket_.ssl = nullptr;
#endif
  socket_.sock = INVALID_SOCKET;
}

bool ClientImpl::handle_request(Stream &strm, Request &req,
                                       Response &res, bool close_connection,
                                       Error &error) {
  if (req.path.empty()) {
    error = Error::Connection;
    output_error_log(error, &req);
    return false;
  }

  auto req_save = req;

  bool ret;

  if (!is_ssl() && is_proxy_enabled_for_host(host_)) {
    auto req2 = req;
    req2.path = "http://" +
                detail::make_host_and_port_string(host_, port_, false) +
                req.path;
    ret = process_request(strm, req2, res, close_connection, error);
    req = std::move(req2);
    req.path = req_save.path;
  } else {
    ret = process_request(strm, req, res, close_connection, error);
  }

  if (!ret) { return false; }

  if (res.get_header_value("Connection") == "close" ||
      (res.version == "HTTP/1.0" && res.reason != "Connection established")) {
    // NOTE: this requires a not-entirely-obvious chain of calls to be correct
    // for this to be safe.

    // This is safe to call because handle_request is only called by send_
    // which locks the request mutex during the process. It would be a bug
    // to call it from a different thread since it's a thread-safety issue
    // to do these things to the socket if another thread is using the socket.
    std::lock_guard<std::mutex> guard(socket_mutex_);
    disconnect(/*gracefully=*/true);
  }

  if (300 < res.status && res.status < 400 && follow_location_) {
    req = std::move(req_save);
    ret = redirect(req, res, error);
  }

#ifdef CPPHTTPLIB_SSL_ENABLED
  if ((res.status == StatusCode::Unauthorized_401 ||
       res.status == StatusCode::ProxyAuthenticationRequired_407) &&
      req.authorization_count_ < 5) {
    auto is_proxy = res.status == StatusCode::ProxyAuthenticationRequired_407;

    // Only retry when the 407 actually came from a proxy hop: plain HTTP
    // through an enabled proxy. HTTPS via CONNECT tunnels the 407 from the
    // origin (#2457); direct/bypassed origins have no proxy hop at all.
    if (is_proxy && !(!is_ssl() && is_proxy_enabled_for_host(host_))) {
      return ret;
    }

    const auto &username =
        is_proxy ? proxy_digest_auth_username_ : digest_auth_username_;
    const auto &password =
        is_proxy ? proxy_digest_auth_password_ : digest_auth_password_;

    if (!username.empty() && !password.empty()) {
      std::map<std::string, std::string> auth;
      if (detail::parse_www_authenticate(res, auth, is_proxy)) {
        Request new_req = req;
        new_req.authorization_count_ += 1;
        new_req.headers.erase(is_proxy ? "Proxy-Authorization"
                                       : "Authorization");
        new_req.headers.insert(detail::make_digest_authentication_header(
            req, auth, new_req.authorization_count_, detail::random_string(10),
            username, password, is_proxy));

        Response new_res;

        ret = send(new_req, new_res, error);
        if (ret) { res = std::move(new_res); }
      }
    }
  }
#endif

  return ret;
}

bool ClientImpl::redirect(Request &req, Response &res, Error &error) {
  if (req.redirect_count_ == 0) {
    error = Error::ExceedRedirectCount;
    output_error_log(error, &req);
    return false;
  }

  auto location = res.get_header_value("location");
  if (location.empty()) { return false; }

  detail::UrlComponents uc;
  if (!detail::parse_url(location, uc)) { return false; }

  // Only follow http/https redirects
  if (!uc.scheme.empty() && uc.scheme != "http" && uc.scheme != "https") {
    return false;
  }

  auto scheme = is_ssl() ? "https" : "http";

  auto next_scheme = std::move(uc.scheme);
  auto next_host = std::move(uc.host);
  auto port_str = std::move(uc.port);
  auto next_path = std::move(uc.path);
  auto next_query = std::move(uc.query);

  auto next_port = port_;
  if (!port_str.empty()) {
    if (!detail::parse_port(port_str, next_port)) { return false; }
  } else if (!next_scheme.empty()) {
    next_port = next_scheme == "https" ? 443 : 80;
  }

  if (next_scheme.empty()) { next_scheme = scheme; }
  if (next_host.empty()) { next_host = host_; }
  if (next_path.empty()) { next_path = "/"; }

  auto path = decode_path_component(next_path) + next_query;

  // Same host redirect - use current client
  if (next_scheme == scheme && next_host == host_ && next_port == port_) {
    return detail::redirect(*this, req, res, path, location, error);
  }

  // Cross-host/scheme redirect - create new client with robust setup
  return create_redirect_client(next_scheme, next_host, next_port, req, res,
                                path, location, error);
}

// New method for robust redirect client creation
bool ClientImpl::create_redirect_client(
    const std::string &scheme, const std::string &host, int port, Request &req,
    Response &res, const std::string &path, const std::string &location,
    Error &error) {
  // Determine if we need SSL
  auto need_ssl = (scheme == "https");

  // Clean up request headers that are host/client specific
  // Remove headers that should not be carried over to new host
  auto headers_to_remove = std::vector<std::string>{
      "Host", "Proxy-Authorization", "Authorization", "Cookie", "Cookie2"};

  for (const auto &header_name : headers_to_remove) {
    auto it = req.headers.find(header_name);
    while (it != req.headers.end()) {
      it = req.headers.erase(it);
      it = req.headers.find(header_name);
    }
  }

  // Create appropriate client type and handle redirect
  if (need_ssl) {
#ifdef CPPHTTPLIB_SSL_ENABLED
    // Create SSL client for HTTPS redirect
    SSLClient redirect_client(host, port);

    // Setup basic client configuration first
    setup_redirect_client(redirect_client);

    redirect_client.enable_server_certificate_verification(
        server_certificate_verification_);
    redirect_client.enable_server_hostname_verification(
        server_hostname_verification_);
    redirect_client.system_ca_mode_ = system_ca_mode_;

    // Transfer CA certificate to redirect client
    if (!ca_cert_pem_.empty()) {
      redirect_client.load_ca_cert_store(ca_cert_pem_.c_str(),
                                         ca_cert_pem_.size());
    }
    if (!ca_cert_file_path_.empty()) {
      redirect_client.set_ca_cert_path(ca_cert_file_path_, ca_cert_dir_path_);
    }

    // Client certificates are set through constructor for SSLClient
    // NOTE: SSLClient constructor already takes client_cert_path and
    // client_key_path so we need to create it properly if client certs are
    // needed

    // Execute the redirect
    return detail::redirect(redirect_client, req, res, path, location, error);
#else
    // SSL not supported - set appropriate error
    error = Error::SSLConnection;
    output_error_log(error, &req);
    return false;
#endif
  } else {
    // HTTP redirect
    ClientImpl redirect_client(host, port);

    // Setup client with robust configuration
    setup_redirect_client(redirect_client);

    // Execute the redirect
    return detail::redirect(redirect_client, req, res, path, location, error);
  }
}

// New method for robust client setup (based on basic_manual_redirect.cpp
// logic)
template <typename ClientType>
void ClientImpl::setup_redirect_client(ClientType &client) {
  // Copy basic settings first
  client.set_connection_timeout(connection_timeout_sec_);
  client.set_read_timeout(read_timeout_sec_, read_timeout_usec_);
  client.set_write_timeout(write_timeout_sec_, write_timeout_usec_);
  client.set_keep_alive(keep_alive_);
  client.set_follow_location(
      true); // Enable redirects to handle multi-step redirects
  client.set_path_encode(path_encode_);
  client.set_compress(compress_);
  client.set_decompress(decompress_);

  // NOTE: Authentication credentials (basic auth, bearer token, digest auth)
  // are intentionally NOT copied to the redirect client. Per RFC 9110 Section
  // 15.4, credentials must not be forwarded when redirecting to a different
  // host. This function is only called for cross-host redirects; same-host
  // redirects are handled directly in ClientImpl::redirect().

  // Copy the proxy configuration unconditionally; the per-target bypass is
  // re-evaluated at send time, so a later hop to a non-bypassed host can
  // still use the proxy.
  client.no_proxy_entries_ = no_proxy_entries_;
  if (!proxy_host_.empty() && proxy_port_ != -1) {
    client.set_proxy(proxy_host_, proxy_port_);

    if (!proxy_basic_auth_username_.empty()) {
      client.set_proxy_basic_auth(proxy_basic_auth_username_,
                                  proxy_basic_auth_password_);
    }
    if (!proxy_bearer_token_auth_token_.empty()) {
      client.set_proxy_bearer_token_auth(proxy_bearer_token_auth_token_);
    }
#ifdef CPPHTTPLIB_SSL_ENABLED
    if (!proxy_digest_auth_username_.empty()) {
      client.set_proxy_digest_auth(proxy_digest_auth_username_,
                                   proxy_digest_auth_password_);
    }
#endif
  }

  // Copy network and socket settings
  client.set_address_family(address_family_);
  client.set_tcp_nodelay(tcp_nodelay_);
  client.set_ipv6_v6only(ipv6_v6only_);
  if (socket_options_) { client.set_socket_options(socket_options_); }
  if (!interface_.empty()) { client.set_interface(interface_); }

  // Copy logging and headers
  if (logger_) { client.set_logger(logger_); }
  if (error_logger_) { client.set_error_logger(error_logger_); }

  // NOTE: DO NOT copy default_headers_ as they may contain stale Host headers
  // Each new client should generate its own headers based on its target host
}

bool ClientImpl::write_content_with_provider(Stream &strm,
                                                    const Request &req,
                                                    Error &error) const {
  auto is_shutting_down = []() { return false; };

  if (req.is_chunked_content_provider_) {
    auto compressor = compress_ ? detail::create_compressor().first
                                : std::unique_ptr<detail::compressor>();
    if (!compressor) {
      compressor = detail::make_unique<detail::nocompressor>();
    }

    return detail::write_content_chunked(strm, req.content_provider_,
                                         is_shutting_down, *compressor, error);
  } else {
    return detail::write_content_with_progress(
        strm, req.content_provider_, 0, req.content_length_, is_shutting_down,
        req.upload_progress, error);
  }
}

bool ClientImpl::write_request(Stream &strm, Request &req,
                                      bool close_connection, Error &error,
                                      bool skip_body) {
  // Prepare additional headers
  if (close_connection) {
    if (!req.has_header("Connection")) {
      req.set_header("Connection", "close");
    }
  }

  std::string ct_for_defaults;
  if (!req.has_header("Content-Type") && !req.body.empty()) {
    ct_for_defaults = "text/plain";
  }
  prepare_default_headers(req, false, ct_for_defaults);

  if (req.body.empty()) {
    if (req.content_provider_) {
      if (!req.is_chunked_content_provider_) {
        if (!req.has_header("Content-Length")) {
          auto length = std::to_string(req.content_length_);
          req.set_header("Content-Length", length);
        }
      }
    } else {
      if (req.method == "POST" || req.method == "PUT" ||
          req.method == "PATCH") {
        req.set_header("Content-Length", "0");
      }
    }
  }

  if (!basic_auth_password_.empty() || !basic_auth_username_.empty()) {
    if (!req.has_header("Authorization")) {
      req.headers.insert(make_basic_authentication_header(
          basic_auth_username_, basic_auth_password_, false));
    }
  }

  if (!bearer_token_auth_token_.empty()) {
    if (!req.has_header("Authorization")) {
      req.headers.insert(make_bearer_token_authentication_header(
          bearer_token_auth_token_, false));
    }
  }

  // Proxy-Authorization is only sent when the proxy is actually used for
  // this target — otherwise NO_PROXY-matched requests would leak proxy
  // credentials directly to the destination server.
  if (is_proxy_enabled_for_host(host_)) {
    if (!proxy_basic_auth_username_.empty() &&
        !proxy_basic_auth_password_.empty() &&
        !req.has_header("Proxy-Authorization")) {
      req.headers.insert(make_basic_authentication_header(
          proxy_basic_auth_username_, proxy_basic_auth_password_, true));
    }
    if (!proxy_bearer_token_auth_token_.empty() &&
        !req.has_header("Proxy-Authorization")) {
      req.headers.insert(make_bearer_token_authentication_header(
          proxy_bearer_token_auth_token_, true));
    }
  }

  // Request line and headers
  {
    detail::BufferStream bstrm;

    // Extract path and query from req.path
    std::string path_part, query_part;
    auto query_pos = req.path.find('?');
    if (query_pos != std::string::npos) {
      path_part = req.path.substr(0, query_pos);
      query_part = req.path.substr(query_pos + 1);
    } else {
      path_part = req.path;
      query_part = "";
    }

    // Encode path part. If the original `req.path` already contained a
    // query component, preserve its raw query string (including parameter
    // order) instead of reparsing and reassembling it which may reorder
    // parameters due to container ordering (e.g. `Params` uses
    // `std::multimap`). When there is no query in `req.path`, fall back to
    // building a query from `req.params` so existing callers that pass
    // `Params` continue to work.
    auto path_with_query =
        path_encode_ ? detail::encode_path(path_part) : path_part;

    if (!query_part.empty()) {
      // Normalize the query string (decode then re-encode) while preserving
      // the original parameter order. When path encoding is disabled the
      // caller has supplied an already-encoded target and expects the exact
      // bytes to be sent on the wire, so skip normalization for the query
      // too. Normalizing here would decode-then-re-encode the query and
      // corrupt pre-encoded binary payloads (e.g. turning `%20` into `+`,
      // which a strict RFC 3986 server decodes back as `+`, not a space).
      if (path_encode_) {
        auto normalized = detail::normalize_query_string(query_part);
        if (!normalized.empty()) { path_with_query += '?' + normalized; }
      } else {
        path_with_query += '?' + query_part;
      }

      // Still populate req.params for handlers/users who read them.
      detail::parse_query_text(query_part, req.params);
    } else {
      // No query in path; parse any query_part (empty) and append params
      // from `req.params` when present (preserves prior behavior for
      // callers who provide Params separately).
      detail::parse_query_text(query_part, req.params);
      if (!req.params.empty()) {
        path_with_query = append_query_params(path_with_query, req.params);
      }
    }

    // Write request line and headers
    if (detail::write_request_line(bstrm, req.method, path_with_query) < 0) {
      // A rejected target (e.g. CR/LF smuggled in via a decoded redirect
      // Location under set_path_encode(false)) must fail the request cleanly
      // instead of emitting a request-line-less, header-injecting request.
      error = Error::Write;
      output_error_log(error, &req);
      return false;
    }
    if (!detail::check_and_write_headers(bstrm, req.headers, header_writer_,
                                         error)) {
      output_error_log(error, &req);
      return false;
    }

    // Flush buffer
    auto &data = bstrm.get_buffer();
    if (!detail::write_data(strm, data.data(), data.size())) {
      error = Error::Write;
      output_error_log(error, &req);
      return false;
    }
  }

  // After sending request line and headers, wait briefly for an early server
  // response (e.g. 4xx) and avoid sending a potentially large request body
  // unnecessarily. This workaround is only enabled on Windows because Unix
  // platforms surface write errors (EPIPE) earlier; on Windows kernel send
  // buffering can accept large writes even when the peer already responded.
  // Check the stream first (which covers SSL via `is_readable()`), then
  // fall back to select on the socket. Only perform the wait for very large
  // request bodies to avoid interfering with normal small requests and
  // reduce side-effects. Poll briefly (up to 50ms as default) for an early
  // response. Skip this check when using Expect: 100-continue, as the protocol
  // handles early responses properly.
#if defined(_WIN32)
  if (!skip_body &&
      req.body.size() > CPPHTTPLIB_WAIT_EARLY_SERVER_RESPONSE_THRESHOLD &&
      req.path.size() > CPPHTTPLIB_REQUEST_URI_MAX_LENGTH) {
    auto start = std::chrono::high_resolution_clock::now();

    for (;;) {
      // Prefer socket-level readiness to avoid SSL_pending() false-positives
      // from SSL internals. If the underlying socket is readable, assume an
      // early response may be present.
      auto sock = strm.socket();
      if (sock != INVALID_SOCKET && detail::select_read(sock, 0, 0) > 0) {
        return false;
      }

      // Fallback to stream-level check for non-socket streams or when the
      // socket isn't reporting readable. Avoid using `is_readable()` for
      // SSL, since `SSL_pending()` may report buffered records that do not
      // indicate a complete application-level response yet.
      if (!is_ssl() && strm.is_readable()) { return false; }

      auto now = std::chrono::high_resolution_clock::now();
      auto elapsed =
          std::chrono::duration_cast<std::chrono::milliseconds>(now - start)
              .count();
      if (elapsed >= CPPHTTPLIB_WAIT_EARLY_SERVER_RESPONSE_TIMEOUT_MSECOND) {
        break;
      }

      std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
  }
#endif

  // Body
  if (skip_body) { return true; }

  return write_request_body(strm, req, error);
}

bool ClientImpl::write_request_body(Stream &strm, Request &req,
                                           Error &error) {
  if (req.body.empty()) {
    return write_content_with_provider(strm, req, error);
  }

  if (req.upload_progress) {
    auto body_size = req.body.size();
    size_t written = 0;
    auto data = req.body.data();

    while (written < body_size) {
      size_t to_write = (std::min)(CPPHTTPLIB_SEND_BUFSIZ, body_size - written);
      if (!detail::write_data(strm, data + written, to_write)) {
        error = Error::Write;
        output_error_log(error, &req);
        return false;
      }
      written += to_write;

      if (!req.upload_progress(written, body_size)) {
        error = Error::Canceled;
        output_error_log(error, &req);
        return false;
      }
    }
  } else {
    if (!detail::write_data(strm, req.body.data(), req.body.size())) {
      error = Error::Write;
      output_error_log(error, &req);
      return false;
    }
  }

  return true;
}

std::unique_ptr<Response>
ClientImpl::send_with_content_provider_and_receiver(
    Request &req, const char *body, size_t content_length,
    ContentProvider content_provider,
    ContentProviderWithoutLength content_provider_without_length,
    const std::string &content_type, ContentReceiver content_receiver,
    Error &error) {
  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  auto enc = compress_
                 ? detail::create_compressor()
                 : std::pair<std::unique_ptr<detail::compressor>, const char *>(
                       nullptr, nullptr);

  if (enc.second) { req.set_header("Content-Encoding", enc.second); }

  if (enc.first && !content_provider_without_length) {
    auto &compressor = enc.first;

    if (content_provider) {
      auto ok = true;
      size_t offset = 0;
      DataSink data_sink;

      data_sink.write = [&](const char *data, size_t data_len) -> bool {
        if (ok) {
          auto last = offset + data_len == content_length;

          auto ret = compressor->compress(
              data, data_len, last,
              [&](const char *compressed_data, size_t compressed_data_len) {
                req.body.append(compressed_data, compressed_data_len);
                return true;
              });

          if (ret) {
            offset += data_len;
          } else {
            ok = false;
          }
        }
        return ok;
      };

      while (ok && offset < content_length) {
        if (!content_provider(offset, content_length - offset, data_sink)) {
          error = Error::Canceled;
          output_error_log(error, &req);
          return nullptr;
        }
      }
    } else {
      if (!compressor->compress(body, content_length, true,
                                [&](const char *data, size_t data_len) {
                                  req.body.append(data, data_len);
                                  return true;
                                })) {
        error = Error::Compression;
        output_error_log(error, &req);
        return nullptr;
      }
    }
  } else {
    if (content_provider) {
      req.content_length_ = content_length;
      req.content_provider_ = std::move(content_provider);
      req.is_chunked_content_provider_ = false;
    } else if (content_provider_without_length) {
      req.content_length_ = 0;
      req.content_provider_ = detail::ContentProviderAdapter(
          std::move(content_provider_without_length));
      req.is_chunked_content_provider_ = true;
      req.set_header("Transfer-Encoding", "chunked");
    } else {
      req.body.assign(body, content_length);
    }
  }

  if (content_receiver) {
    req.content_receiver =
        [content_receiver](const char *data, size_t data_length,
                           size_t /*offset*/, size_t /*total_length*/) {
          return content_receiver(data, data_length);
        };
  }

  auto res = detail::make_unique<Response>();
  return send(req, *res, error) ? std::move(res) : nullptr;
}

Result ClientImpl::send_with_content_provider_and_receiver(
    const std::string &method, const std::string &path, const Headers &headers,
    const char *body, size_t content_length, ContentProvider content_provider,
    ContentProviderWithoutLength content_provider_without_length,
    const std::string &content_type, ContentReceiver content_receiver,
    UploadProgress progress) {
  Request req;
  req.method = method;
  req.headers = headers;
  req.path = path;
  req.upload_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  auto error = Error::Success;

  auto res = send_with_content_provider_and_receiver(
      req, body, content_length, std::move(content_provider),
      std::move(content_provider_without_length), content_type,
      std::move(content_receiver), error);

#ifdef CPPHTTPLIB_SSL_ENABLED
  return Result{std::move(res), error, std::move(req.headers), last_ssl_error_,
                last_backend_error_};
#else
  return Result{std::move(res), error, std::move(req.headers)};
#endif
}

void ClientImpl::output_log(const Request &req,
                                   const Response &res) const {
  if (logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    logger_(req, res);
  }
}

void ClientImpl::output_error_log(const Error &err,
                                         const Request *req) const {
  if (error_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    error_logger_(err, req);
  }
}

bool ClientImpl::process_request(Stream &strm, Request &req,
                                        Response &res, bool close_connection,
                                        Error &error) {
  // Auto-add Expect: 100-continue for large bodies
  if (CPPHTTPLIB_EXPECT_100_THRESHOLD > 0 && !req.has_header("Expect")) {
    auto body_size = req.body.empty() ? req.content_length_ : req.body.size();
    if (body_size >= CPPHTTPLIB_EXPECT_100_THRESHOLD) {
      req.set_header("Expect", "100-continue");
    }
  }

  // Check for Expect: 100-continue
  auto expect_100_continue = req.get_header_value("Expect") == "100-continue";

  // Send request (skip body if using Expect: 100-continue)
  auto write_request_success =
      write_request(strm, req, close_connection, error, expect_100_continue);

#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl() && !expect_100_continue) {
    auto is_proxy_enabled = is_proxy_enabled_for_host(host_);
    if (!is_proxy_enabled) {
      if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
        error = Error::SSLPeerCouldBeClosed_;
        output_error_log(error, &req);
        return false;
      }
    }
  }
#endif

  // Handle Expect: 100-continue.
  //
  // Wait for an interim/early response by attempting to read the status line
  // under a short timeout, instead of trusting raw socket readability. Over
  // TLS, post-handshake records (e.g. session tickets) make the socket
  // readable without any HTTP response being available; relying on
  // `select_read` there caused the body to be withheld forever and the
  // request to fail with `Read` (#2458). If no status line arrives within the
  // timeout, send the body anyway (matching curl's behavior).
  auto status_line_read = false;
  if (expect_100_continue && write_request_success) {
    if (CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND > 0) {
      time_t sec = CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND / 1000;
      time_t usec = (CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND % 1000) * 1000;
      strm.set_read_timeout(sec, usec);
      status_line_read = read_response_line(strm, req, res, false);
      strm.set_read_timeout(read_timeout_sec_, read_timeout_usec_);
    }

    if (!status_line_read) {
      // No interim response within the timeout: send the body and handle the
      // response as usual.
      if (!write_request_body(strm, req, error)) { return false; }
      expect_100_continue = false; // Switch to normal response handling
    }
  }

  // Receive response and headers
  // When using Expect: 100-continue, don't auto-skip `100 Continue` response
  if ((!status_line_read &&
       !read_response_line(strm, req, res, !expect_100_continue)) ||
      !detail::read_headers(strm, res.headers)) {
    if (write_request_success) { error = Error::Read; }
    output_error_log(error, &req);
    return false;
  }

  if (!write_request_success) { return false; }

  // Handle Expect: 100-continue response
  if (expect_100_continue) {
    if (res.status == StatusCode::Continue_100) {
      // Server accepted, send the body
      if (!write_request_body(strm, req, error)) { return false; }

      // Read the actual response
      res.headers.clear();
      res.body.clear();
      if (!read_response_line(strm, req, res) ||
          !detail::read_headers(strm, res.headers)) {
        error = Error::Read;
        output_error_log(error, &req);
        return false;
      }
    }
    // If not 100 Continue, server returned an error; proceed with that response
  }

  // Body
  if ((res.status != StatusCode::NoContent_204) && req.method != "HEAD" &&
      req.method != "CONNECT") {
    auto redirect = 300 < res.status && res.status < 400 &&
                    res.status != StatusCode::NotModified_304 &&
                    follow_location_;

    if (req.response_handler && !redirect) {
      if (!req.response_handler(res)) {
        error = Error::Canceled;
        output_error_log(error, &req);
        return false;
      }
    }

    auto out =
        req.content_receiver
            ? static_cast<ContentReceiverWithProgress>(
                  [&](const char *buf, size_t n, size_t off, size_t len) {
                    if (redirect) { return true; }
                    auto ret = req.content_receiver(buf, n, off, len);
                    if (!ret) {
                      error = Error::Canceled;
                      output_error_log(error, &req);
                    }
                    return ret;
                  })
            : static_cast<ContentReceiverWithProgress>(
                  [&](const char *buf, size_t n, size_t /*off*/,
                      size_t /*len*/) {
                    assert(res.body.size() + n <= res.body.max_size());
                    if (payload_max_length_ > 0 &&
                        (res.body.size() >= payload_max_length_ ||
                         n > payload_max_length_ - res.body.size())) {
                      return false;
                    }
                    res.body.append(buf, n);
                    return true;
                  });

    auto progress = [&](size_t current, size_t total) {
      if (!req.download_progress || redirect) { return true; }
      auto ret = req.download_progress(current, total);
      if (!ret) {
        error = Error::Canceled;
        output_error_log(error, &req);
      }
      return ret;
    };

    if (res.has_header("Content-Length")) {
      if (!req.content_receiver) {
        auto len = res.get_header_value_u64("Content-Length");
        if (len > res.body.max_size()) {
          error = Error::Read;
          output_error_log(error, &req);
          return false;
        }
        // Cap the reservation by payload_max_length_ to avoid OOM when a
        // hostile or malformed server sends an enormous Content-Length.
        // The actual body read below is bounded by payload_max_length_,
        // so reserving more than that is never useful.
        auto reserve_len = static_cast<size_t>(len);
        if (payload_max_length_ > 0 && reserve_len > payload_max_length_) {
          reserve_len = payload_max_length_;
        }
        res.body.reserve(reserve_len);
      }
    }

    if (res.status != StatusCode::NotModified_304) {
      int dummy_status;
      auto max_length = (!has_payload_max_length_ && req.content_receiver)
                            ? (std::numeric_limits<size_t>::max)()
                            : payload_max_length_;
      if (!detail::read_content(strm, res, max_length, dummy_status,
                                std::move(progress), std::move(out),
                                decompress_)) {
        if (error != Error::Canceled) { error = Error::Read; }
        output_error_log(error, &req);
        return false;
      }
    }
  }

  // Log
  output_log(req, res);

  return true;
}

ContentProviderWithoutLength ClientImpl::get_multipart_content_provider(
    const std::string &boundary, const UploadFormDataItems &items,
    const FormDataProviderItems &provider_items) const {
  size_t cur_item = 0;
  size_t cur_start = 0;
  // cur_item and cur_start are copied to within the std::function and
  // maintain state between successive calls
  return [&, cur_item, cur_start](size_t offset,
                                  DataSink &sink) mutable -> bool {
    if (!offset && !items.empty()) {
      sink.os << detail::serialize_multipart_formdata(items, boundary, false);
      return true;
    } else if (cur_item < provider_items.size()) {
      if (!cur_start) {
        const auto &begin = detail::serialize_multipart_formdata_item_begin(
            provider_items[cur_item], boundary);
        offset += begin.size();
        cur_start = offset;
        sink.os << begin;
      }

      DataSink cur_sink;
      auto has_data = true;
      cur_sink.write = sink.write;
      cur_sink.done = [&]() { has_data = false; };

      if (!provider_items[cur_item].provider(offset - cur_start, cur_sink)) {
        return false;
      }

      if (!has_data) {
        sink.os << detail::serialize_multipart_formdata_item_end();
        cur_item++;
        cur_start = 0;
      }
      return true;
    } else {
      sink.os << detail::serialize_multipart_formdata_finish(boundary);
      sink.done();
      return true;
    }
  };
}

bool ClientImpl::process_socket(
    const Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &strm)> callback) {
  return detail::process_client_socket(
      socket.sock, read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, max_timeout_msec_, start_time, std::move(callback));
}

bool ClientImpl::is_ssl() const { return false; }

Result ClientImpl::Get(const std::string &path,
                              DownloadProgress progress) {
  return Get(path, Headers(), std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              DownloadProgress progress) {
  return Get(path, params, Headers(), std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              DownloadProgress progress) {
  if (params.empty()) { return Get(path, headers); }

  std::string path_with_query = append_query_params(path, params);
  return Get(path_with_query, headers, std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              DownloadProgress progress) {
  Request req;
  req.method = "GET";
  req.path = path;
  req.headers = headers;
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Get(const std::string &path,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, Headers(), nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, headers, nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, Headers(), std::move(response_handler),
             std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  Request req;
  req.method = "GET";
  req.path = path;
  req.headers = headers;
  req.response_handler = std::move(response_handler);
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, params, headers, nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  if (params.empty()) {
    return Get(path, headers, std::move(response_handler),
               std::move(content_receiver), std::move(progress));
  }

  std::string path_with_query = append_query_params(path, params);
  return Get(path_with_query, headers, std::move(response_handler),
             std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Head(const std::string &path) {
  return Head(path, Headers());
}

Result ClientImpl::Head(const std::string &path,
                               const Headers &headers) {
  Request req;
  req.method = "HEAD";
  req.headers = headers;
  req.path = path;
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Post(const std::string &path) {
  return Post(path, std::string(), std::string());
}

Result ClientImpl::Post(const std::string &path,
                               const Headers &headers) {
  return Post(path, headers, nullptr, 0, std::string());
}

Result ClientImpl::Post(const std::string &path, const char *body,
                               size_t content_length,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const std::string &body,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Params &params) {
  return Post(path, Headers(), params);
}

Result ClientImpl::Post(const std::string &path, size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), content_length, std::move(content_provider),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               UploadProgress progress) {
  return Post(path, Headers(), content_length, std::move(content_provider),
              content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Post(const std::string &path,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), std::move(content_provider), content_type,
              progress);
}

Result ClientImpl::Post(const std::string &path,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               UploadProgress progress) {
  return Post(path, Headers(), std::move(content_provider), content_type,
              std::move(content_receiver), progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Post(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Post(const std::string &path,
                               const UploadFormDataItems &items,
                               UploadProgress progress) {
  return Post(path, Headers(), items, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Post(path, headers, content_length,
              detail::make_multipart_content_provider(items, boundary),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               const std::string &boundary,
                               UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Post(path, headers, content_length,
              detail::make_multipart_content_provider(items, boundary),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const char *body, size_t content_length,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const std::string &body,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               const FormDataProviderItems &provider_items,
                               UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const std::string &body,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  Request req;
  req.method = "POST";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Put(const std::string &path) {
  return Put(path, std::string(), std::string());
}

Result ClientImpl::Put(const std::string &path, const Headers &headers) {
  return Put(path, headers, nullptr, 0, std::string());
}

Result ClientImpl::Put(const std::string &path, const char *body,
                              size_t content_length,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const std::string &body,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Params &params) {
  return Put(path, Headers(), params);
}

Result ClientImpl::Put(const std::string &path, size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), content_length, std::move(content_provider),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return Put(path, Headers(), content_length, std::move(content_provider),
             content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), std::move(content_provider), content_type,
             progress);
}

Result ClientImpl::Put(const std::string &path,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return Put(path, Headers(), std::move(content_provider), content_type,
             std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Put(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Put(const std::string &path,
                              const UploadFormDataItems &items,
                              UploadProgress progress) {
  return Put(path, Headers(), items, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Put(path, headers, content_length,
             detail::make_multipart_content_provider(items, boundary),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              const std::string &boundary,
                              UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Put(path, headers, content_length,
             detail::make_multipart_content_provider(items, boundary),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const char *body, size_t content_length,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const std::string &body,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              const FormDataProviderItems &provider_items,
                              UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const std::string &body,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  Request req;
  req.method = "PUT";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Patch(const std::string &path) {
  return Patch(path, std::string(), std::string());
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                UploadProgress progress) {
  return Patch(path, headers, nullptr, 0, std::string(), progress);
}

Result ClientImpl::Patch(const std::string &path, const char *body,
                                size_t content_length,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Patch(const std::string &path,
                                const std::string &body,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Params &params) {
  return Patch(path, Headers(), params);
}

Result ClientImpl::Patch(const std::string &path, size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), content_length, std::move(content_provider),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return Patch(path, Headers(), content_length, std::move(content_provider),
               content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), std::move(content_provider), content_type,
               progress);
}

Result ClientImpl::Patch(const std::string &path,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return Patch(path, Headers(), std::move(content_provider), content_type,
               std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Patch(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Patch(const std::string &path,
                                const UploadFormDataItems &items,
                                UploadProgress progress) {
  return Patch(path, Headers(), items, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Patch(path, headers, content_length,
               detail::make_multipart_content_provider(items, boundary),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                const std::string &boundary,
                                UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Patch(path, headers, content_length,
               detail::make_multipart_content_provider(items, boundary),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const char *body, size_t content_length,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const std::string &body,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                const FormDataProviderItems &provider_items,
                                UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const std::string &body,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                DownloadProgress progress) {
  Request req;
  req.method = "PATCH";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Delete(const std::string &path,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), std::string(), std::string(), progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers,
                                 DownloadProgress progress) {
  return Delete(path, headers, std::string(), std::string(), progress);
}

Result ClientImpl::Delete(const std::string &path, const char *body,
                                 size_t content_length,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const std::string &body,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), body.data(), body.size(), content_type,
                progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers,
                                 const std::string &body,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, headers, body.data(), body.size(), content_type,
                progress);
}

Result ClientImpl::Delete(const std::string &path, const Params &params,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), params, progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers, const Params &params,
                                 DownloadProgress progress) {
  auto query = detail::params_to_query_str(params);
  return Delete(path, headers, query, "application/x-www-form-urlencoded",
                progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers, const char *body,
                                 size_t content_length,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  Request req;
  req.method = "DELETE";
  req.headers = headers;
  req.path = path;
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }
  req.body.assign(body, content_length);

  return send_(std::move(req));
}

Result ClientImpl::Options(const std::string &path) {
  return Options(path, Headers());
}

Result ClientImpl::Options(const std::string &path,
                                  const Headers &headers) {
  Request req;
  req.method = "OPTIONS";
  req.headers = headers;
  req.path = path;
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

void ClientImpl::stop() {
  std::lock_guard<std::mutex> guard(socket_mutex_);

  // If there is anything ongoing right now, the ONLY thread-safe thing we can
  // do is to shutdown_socket, so that threads using this socket suddenly
  // discover they can't read/write any more and error out. Everything else
  // (closing the socket, shutting ssl down) is unsafe because these actions
  // are not thread-safe.
  if (socket_requests_in_flight_ > 0) {
    shutdown_socket(socket_);

    // Aside from that, we set a flag for the socket to be closed when we're
    // done.
    socket_should_be_closed_when_request_is_done_ = true;
    return;
  }

  disconnect(/*gracefully=*/true);
}

std::string ClientImpl::host() const { return host_; }

int ClientImpl::port() const { return port_; }

size_t ClientImpl::is_socket_open() const {
  std::lock_guard<std::mutex> guard(socket_mutex_);
  return socket_.is_open();
}

socket_t ClientImpl::socket() const { return socket_.sock; }

void ClientImpl::set_connection_timeout(time_t sec, time_t usec) {
  connection_timeout_sec_ = sec;
  connection_timeout_usec_ = usec;
}

void ClientImpl::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

void ClientImpl::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
}

void ClientImpl::set_max_timeout(time_t msec) {
  max_timeout_msec_ = msec;
}

void ClientImpl::set_basic_auth(const std::string &username,
                                       const std::string &password) {
  basic_auth_username_ = username;
  basic_auth_password_ = password;
}

void ClientImpl::set_bearer_token_auth(const std::string &token) {
  bearer_token_auth_token_ = token;
}

void ClientImpl::set_keep_alive(bool on) { keep_alive_ = on; }

void ClientImpl::set_follow_location(bool on) { follow_location_ = on; }

void ClientImpl::set_path_encode(bool on) { path_encode_ = on; }

void
ClientImpl::set_hostname_addr_map(std::map<std::string, std::string> addr_map) {
  addr_map_ = std::move(addr_map);
}

void ClientImpl::set_default_headers(Headers headers) {
  default_headers_ = std::move(headers);
}

void ClientImpl::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  header_writer_ = writer;
}

void ClientImpl::set_address_family(int family) {
  address_family_ = family;
}

void ClientImpl::set_tcp_nodelay(bool on) { tcp_nodelay_ = on; }

void ClientImpl::set_ipv6_v6only(bool on) { ipv6_v6only_ = on; }

void ClientImpl::set_socket_options(SocketOptions socket_options) {
  socket_options_ = std::move(socket_options);
}

void ClientImpl::set_compress(bool on) { compress_ = on; }

void ClientImpl::set_decompress(bool on) { decompress_ = on; }

void ClientImpl::set_payload_max_length(size_t length) {
  payload_max_length_ = length;
  has_payload_max_length_ = true;
}

void ClientImpl::set_interface(const std::string &intf) {
  interface_ = intf;
}

void ClientImpl::set_proxy(const std::string &host, int port) {
  proxy_host_ = host;
  proxy_port_ = port;
  std::lock_guard<std::mutex> guard(socket_mutex_);
  disconnect(/*gracefully=*/true);
}

void ClientImpl::set_proxy_basic_auth(const std::string &username,
                                             const std::string &password) {
  proxy_basic_auth_username_ = username;
  proxy_basic_auth_password_ = password;
}

void ClientImpl::set_proxy_bearer_token_auth(const std::string &token) {
  proxy_bearer_token_auth_token_ = token;
}

void ClientImpl::set_no_proxy(const std::vector<std::string> &patterns) {
  std::vector<detail::NoProxyEntry> parsed;
  parsed.reserve(patterns.size());
  for (const auto &p : patterns) {
    auto trimmed = detail::trim_copy(p);
    if (trimmed.empty()) { continue; }
    detail::NoProxyEntry entry;
    if (detail::parse_no_proxy_entry(trimmed, entry)) {
      parsed.push_back(std::move(entry));
    }
  }
  no_proxy_entries_ = std::move(parsed);
  std::lock_guard<std::mutex> guard(socket_mutex_);
  disconnect(/*gracefully=*/true);
}

#ifdef CPPHTTPLIB_SSL_ENABLED
void ClientImpl::set_digest_auth(const std::string &username,
                                        const std::string &password) {
  digest_auth_username_ = username;
  digest_auth_password_ = password;
}

void ClientImpl::set_ca_cert_path(const std::string &ca_cert_file_path,
                                         const std::string &ca_cert_dir_path) {
  ca_cert_file_path_ = ca_cert_file_path;
  ca_cert_dir_path_ = ca_cert_dir_path;
}

void ClientImpl::set_proxy_digest_auth(const std::string &username,
                                              const std::string &password) {
  proxy_digest_auth_username_ = username;
  proxy_digest_auth_password_ = password;
}

void ClientImpl::enable_server_certificate_verification(bool enabled) {
  server_certificate_verification_ = enabled;
}

void ClientImpl::enable_server_hostname_verification(bool enabled) {
  server_hostname_verification_ = enabled;
}

void ClientImpl::enable_system_ca(bool enabled) {
  system_ca_mode_ = enabled ? SystemCAMode::Enabled : SystemCAMode::Disabled;
}
#endif

void ClientImpl::set_logger(Logger logger) {
  logger_ = std::move(logger);
}

void ClientImpl::set_error_logger(ErrorLogger error_logger) {
  error_logger_ = std::move(error_logger);
}

/*
 * SSL/TLS Common Implementation
 */

ClientConnection::~ClientConnection() {
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (session) {
    tls::shutdown(session, true);
    tls::free_session(session);
    session = nullptr;
  }
#endif

  if (sock != INVALID_SOCKET) {
    detail::close_socket(sock);
    sock = INVALID_SOCKET;
  }
}

// Universal client implementation
Client::Client(const std::string &scheme_host_port)
    : Client(scheme_host_port, std::string(), std::string()) {}

Client::Client(const std::string &scheme_host_port,
                      const std::string &client_cert_path,
                      const std::string &client_key_path) {
  detail::UrlComponents uc;
  if (detail::parse_url(scheme_host_port, uc) && !uc.host.empty()) {
    auto &scheme = uc.scheme;

#ifdef CPPHTTPLIB_SSL_ENABLED
    if (!scheme.empty() && (scheme != "http" && scheme != "https")) {
#else
    if (!scheme.empty() && scheme != "http") {
#endif
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
      std::string msg = "'" + scheme + "' scheme is not supported.";
      throw std::invalid_argument(msg);
#endif
      return;
    }

    auto is_ssl = scheme == "https";

    auto host = std::move(uc.host);

    auto port = is_ssl ? 443 : 80;
    if (!uc.port.empty() && !detail::parse_port(uc.port, port)) { return; }

    if (is_ssl) {
#ifdef CPPHTTPLIB_SSL_ENABLED
      cli_ = detail::make_unique<SSLClient>(host, port, client_cert_path,
                                            client_key_path);
      is_ssl_ = is_ssl;
#endif
    } else {
      cli_ = detail::make_unique<ClientImpl>(host, port, client_cert_path,
                                             client_key_path);
    }
  } else {
    // NOTE: Update TEST(UniversalClientImplTest, Ipv6LiteralAddress)
    // if port param below changes.
    cli_ = detail::make_unique<ClientImpl>(scheme_host_port, 80,
                                           client_cert_path, client_key_path);
  }
}

Client::Client(const std::string &host, int port)
    : Client(host, port, std::string(), std::string()) {}

Client::Client(const std::string &host, int port,
                      const std::string &client_cert_path,
                      const std::string &client_key_path)
    : cli_(detail::make_unique<ClientImpl>(host, port, client_cert_path,
                                           client_key_path)) {}

Client::~Client() = default;

bool Client::is_valid() const {
  return cli_ != nullptr && cli_->is_valid();
}

Result Client::Get(const std::string &path, DownloadProgress progress) {
  return cli_->Get(path, std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(progress));
}
Result Client::Get(const std::string &path,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(content_receiver),
                   std::move(progress));
}
Result Client::Get(const std::string &path,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          DownloadProgress progress) {
  return cli_->Get(path, params, std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers, DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(content_receiver),
                   std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}

Result Client::Head(const std::string &path) { return cli_->Head(path); }
Result Client::Head(const std::string &path, const Headers &headers) {
  return cli_->Head(path, headers);
}

Result Client::Post(const std::string &path) { return cli_->Post(path); }
Result Client::Post(const std::string &path, const Headers &headers) {
  return cli_->Post(path, headers);
}
Result Client::Post(const std::string &path, const char *body,
                           size_t content_length,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, body, content_length, content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const char *body, size_t content_length,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, body, content_length, content_type,
                    progress);
}
Result Client::Post(const std::string &path, const std::string &body,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, body, content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const std::string &body,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, body, content_type, progress);
}
Result Client::Post(const std::string &path, size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, content_length, std::move(content_provider),
                    content_type, progress);
}
Result Client::Post(const std::string &path, size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           UploadProgress progress) {
  return cli_->Post(path, content_length, std::move(content_provider),
                    content_type, std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, std::move(content_provider), content_type, progress);
}
Result Client::Post(const std::string &path,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           UploadProgress progress) {
  return cli_->Post(path, std::move(content_provider), content_type,
                    std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, content_length, std::move(content_provider),
                    content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, content_length, std::move(content_provider),
                    content_type, std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, std::move(content_provider), content_type,
                    progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, std::move(content_provider), content_type,
                    std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Params &params) {
  return cli_->Post(path, params);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const Params &params) {
  return cli_->Post(path, headers, params);
}
Result Client::Post(const std::string &path,
                           const UploadFormDataItems &items,
                           UploadProgress progress) {
  return cli_->Post(path, items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           const std::string &boundary,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, boundary, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           const FormDataProviderItems &provider_items,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, provider_items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const std::string &body,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, body, content_type,
                    std::move(content_receiver), progress);
}

Result Client::Put(const std::string &path) { return cli_->Put(path); }
Result Client::Put(const std::string &path, const Headers &headers) {
  return cli_->Put(path, headers);
}
Result Client::Put(const std::string &path, const char *body,
                          size_t content_length,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, body, content_length, content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const char *body, size_t content_length,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, body, content_length, content_type, progress);
}
Result Client::Put(const std::string &path, const std::string &body,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, body, content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const std::string &body,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, body, content_type, progress);
}
Result Client::Put(const std::string &path, size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, content_length, std::move(content_provider),
                   content_type, progress);
}
Result Client::Put(const std::string &path, size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, content_length, std::move(content_provider),
                   content_type, std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, std::move(content_provider), content_type, progress);
}
Result Client::Put(const std::string &path,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, std::move(content_provider), content_type,
                   std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, content_length, std::move(content_provider),
                   content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, headers, content_length, std::move(content_provider),
                   content_type, std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, std::move(content_provider), content_type,
                   progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, headers, std::move(content_provider), content_type,
                   std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Params &params) {
  return cli_->Put(path, params);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const Params &params) {
  return cli_->Put(path, headers, params);
}
Result Client::Put(const std::string &path,
                          const UploadFormDataItems &items,
                          UploadProgress progress) {
  return cli_->Put(path, items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          const std::string &boundary,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, boundary, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          const FormDataProviderItems &provider_items,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, provider_items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const std::string &body,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Put(path, headers, body, content_type, content_receiver,
                   progress);
}

Result Client::Patch(const std::string &path) {
  return cli_->Patch(path);
}
Result Client::Patch(const std::string &path, const Headers &headers) {
  return cli_->Patch(path, headers);
}
Result Client::Patch(const std::string &path, const char *body,
                            size_t content_length,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, body, content_length, content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const char *body, size_t content_length,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, body, content_length, content_type,
                     progress);
}
Result Client::Patch(const std::string &path, const std::string &body,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, body, content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const std::string &body,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, body, content_type, progress);
}
Result Client::Patch(const std::string &path, size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, content_length, std::move(content_provider),
                     content_type, progress);
}
Result Client::Patch(const std::string &path, size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, content_length, std::move(content_provider),
                     content_type, std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, std::move(content_provider), content_type, progress);
}
Result Client::Patch(const std::string &path,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, std::move(content_provider), content_type,
                     std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, content_length, std::move(content_provider),
                     content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, content_length, std::move(content_provider),
                     content_type, std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, std::move(content_provider), content_type,
                     progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, std::move(content_provider), content_type,
                     std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Params &params) {
  return cli_->Patch(path, params);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const Params &params) {
  return cli_->Patch(path, headers, params);
}
Result Client::Patch(const std::string &path,
                            const UploadFormDataItems &items,
                            UploadProgress progress) {
  return cli_->Patch(path, items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            const std::string &boundary,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, boundary, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            const FormDataProviderItems &provider_items,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, provider_items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const std::string &body,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            DownloadProgress progress) {
  return cli_->Patch(path, headers, body, content_type, content_receiver,
                     progress);
}

Result Client::Delete(const std::string &path,
                             DownloadProgress progress) {
  return cli_->Delete(path, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, progress);
}
Result Client::Delete(const std::string &path, const char *body,
                             size_t content_length,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, body, content_length, content_type, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const char *body, size_t content_length,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, body, content_length, content_type,
                      progress);
}
Result Client::Delete(const std::string &path, const std::string &body,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, body, content_type, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const std::string &body,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, body, content_type, progress);
}
Result Client::Delete(const std::string &path, const Params &params,
                             DownloadProgress progress) {
  return cli_->Delete(path, params, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const Params &params, DownloadProgress progress) {
  return cli_->Delete(path, headers, params, progress);
}

Result Client::Options(const std::string &path) {
  return cli_->Options(path);
}
Result Client::Options(const std::string &path, const Headers &headers) {
  return cli_->Options(path, headers);
}

ClientImpl::StreamHandle
Client::open_stream(const std::string &method, const std::string &path,
                    const Params &params, const Headers &headers,
                    const std::string &body, const std::string &content_type) {
  return cli_->open_stream(method, path, params, headers, body, content_type);
}

bool Client::send(Request &req, Response &res, Error &error) {
  return cli_->send(req, res, error);
}

Result Client::send(const Request &req) { return cli_->send(req); }

void Client::stop() { cli_->stop(); }

std::string Client::host() const { return cli_->host(); }

int Client::port() const { return cli_->port(); }

size_t Client::is_socket_open() const { return cli_->is_socket_open(); }

socket_t Client::socket() const { return cli_->socket(); }

void
Client::set_hostname_addr_map(std::map<std::string, std::string> addr_map) {
  cli_->set_hostname_addr_map(std::move(addr_map));
}

void Client::set_default_headers(Headers headers) {
  cli_->set_default_headers(std::move(headers));
}

void Client::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  cli_->set_header_writer(writer);
}

void Client::set_address_family(int family) {
  cli_->set_address_family(family);
}

void Client::set_tcp_nodelay(bool on) { cli_->set_tcp_nodelay(on); }

void Client::set_socket_options(SocketOptions socket_options) {
  cli_->set_socket_options(std::move(socket_options));
}

void Client::set_connection_timeout(time_t sec, time_t usec) {
  cli_->set_connection_timeout(sec, usec);
}

void Client::set_read_timeout(time_t sec, time_t usec) {
  cli_->set_read_timeout(sec, usec);
}

void Client::set_write_timeout(time_t sec, time_t usec) {
  cli_->set_write_timeout(sec, usec);
}

void Client::set_basic_auth(const std::string &username,
                                   const std::string &password) {
  cli_->set_basic_auth(username, password);
}
void Client::set_bearer_token_auth(const std::string &token) {
  cli_->set_bearer_token_auth(token);
}

void Client::set_keep_alive(bool on) { cli_->set_keep_alive(on); }
void Client::set_follow_location(bool on) {
  cli_->set_follow_location(on);
}

void Client::set_path_encode(bool on) { cli_->set_path_encode(on); }

void Client::set_compress(bool on) { cli_->set_compress(on); }

void Client::set_decompress(bool on) { cli_->set_decompress(on); }

void Client::set_payload_max_length(size_t length) {
  cli_->set_payload_max_length(length);
}

void Client::set_interface(const std::string &intf) {
  cli_->set_interface(intf);
}

void Client::set_proxy(const std::string &host, int port) {
  cli_->set_proxy(host, port);
}
void Client::set_proxy_basic_auth(const std::string &username,
                                         const std::string &password) {
  cli_->set_proxy_basic_auth(username, password);
}
void Client::set_proxy_bearer_token_auth(const std::string &token) {
  cli_->set_proxy_bearer_token_auth(token);
}
void Client::set_no_proxy(const std::vector<std::string> &patterns) {
  cli_->set_no_proxy(patterns);
}

void Client::set_logger(Logger logger) {
  cli_->set_logger(std::move(logger));
}

void Client::set_error_logger(ErrorLogger error_logger) {
  cli_->set_error_logger(std::move(error_logger));
}

/*
 * Group 6: SSL Server and Client implementation
 */

#ifdef CPPHTTPLIB_SSL_ENABLED

// SSL HTTP server implementation
SSLServer::SSLServer(const char *cert_path, const char *private_key_path,
                            const char *client_ca_cert_file_path,
                            const char *client_ca_cert_dir_path,
                            const char *private_key_password) {
  using namespace tls;

  ctx_ = create_server_context();
  if (!ctx_) { return; }

  // Load server certificate and private key
  if (!set_server_cert_file(ctx_, cert_path, private_key_path,
                            private_key_password)) {
    last_ssl_error_ = static_cast<int>(get_error());
    free_context(ctx_);
    ctx_ = nullptr;
    return;
  }

  // Load client CA certificates for client authentication
  if (client_ca_cert_file_path || client_ca_cert_dir_path) {
    if (!set_client_ca_file(ctx_, client_ca_cert_file_path,
                            client_ca_cert_dir_path)) {
      last_ssl_error_ = static_cast<int>(get_error());
      free_context(ctx_);
      ctx_ = nullptr;
      return;
    }
    // Enable client certificate verification
    set_verify_client(ctx_, true);
  }
}

SSLServer::SSLServer(const PemMemory &pem) {
  using namespace tls;
  ctx_ = create_server_context();
  if (ctx_) {
    if (!set_server_cert_pem(ctx_, pem.cert_pem, pem.key_pem,
                             pem.private_key_password)) {
      last_ssl_error_ = static_cast<int>(get_error());
      free_context(ctx_);
      ctx_ = nullptr;
    } else if (pem.client_ca_pem && pem.client_ca_pem_len > 0) {
      if (!load_ca_pem(ctx_, pem.client_ca_pem, pem.client_ca_pem_len)) {
        last_ssl_error_ = static_cast<int>(get_error());
        free_context(ctx_);
        ctx_ = nullptr;
      } else {
        set_verify_client(ctx_, true);
      }
    }
  }
}

SSLServer::SSLServer(const tls::ContextSetupCallback &setup_callback) {
  using namespace tls;
  ctx_ = create_server_context();
  if (ctx_) {
    if (!setup_callback(ctx_)) {
      free_context(ctx_);
      ctx_ = nullptr;
    }
  }
}

SSLServer::~SSLServer() {
  if (ctx_) { tls::free_context(ctx_); }
}

bool SSLServer::is_valid() const { return ctx_ != nullptr; }

bool SSLServer::process_and_close_socket(socket_t sock) {
  using namespace tls;

  // Create TLS session with mutex protection
  session_t session = nullptr;
  {
    std::lock_guard<std::mutex> guard(ctx_mutex_);
    session = create_session(static_cast<ctx_t>(ctx_), sock);
  }

  if (!session) {
    last_ssl_error_ = static_cast<int>(get_error());
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
    return false;
  }

  // Use scope_exit to ensure cleanup on all paths (including exceptions)
  bool handshake_done = false;
  bool ret = false;
  bool websocket_upgraded = false;
  auto cleanup = detail::scope_exit([&] {
    if (handshake_done) { shutdown(session, !websocket_upgraded && ret); }
    free_session(session);
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
  });

  // Perform TLS accept handshake with timeout
  TlsError tls_err;
  if (!accept_nonblocking(session, sock, read_timeout_sec_, read_timeout_usec_,
                          &tls_err)) {
#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
    // Map TlsError to legacy ssl_error for backward compatibility
    if (tls_err.code == ErrorCode::WantRead) {
      last_ssl_error_ = SSL_ERROR_WANT_READ;
    } else if (tls_err.code == ErrorCode::WantWrite) {
      last_ssl_error_ = SSL_ERROR_WANT_WRITE;
    } else {
      last_ssl_error_ = SSL_ERROR_SSL;
    }
#else
    last_ssl_error_ = static_cast<int>(get_error());
#endif
    return false;
  }

  handshake_done = true;

  std::string remote_addr;
  int remote_port = 0;
  detail::get_remote_ip_and_port(sock, remote_addr, remote_port);

  std::string local_addr;
  int local_port = 0;
  detail::get_local_ip_and_port(sock, local_addr, local_port);

  ret = detail::process_server_socket_ssl(
      svr_sock_, session, sock, keep_alive_max_count_, keep_alive_timeout_sec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_,
      [&](Stream &strm, bool close_connection, bool &connection_closed) {
        return process_request(
            strm, remote_addr, remote_port, local_addr, local_port,
            close_connection, connection_closed,
            [&](Request &req) { req.ssl = session; }, &websocket_upgraded);
      });

  return ret;
}

bool SSLServer::update_certs_pem(const char *cert_pem,
                                        const char *key_pem,
                                        const char *client_ca_pem,
                                        const char *password) {
  if (!ctx_) { return false; }
  std::lock_guard<std::mutex> guard(ctx_mutex_);
  if (!tls::update_server_cert(ctx_, cert_pem, key_pem, password)) {
    return false;
  }
  if (client_ca_pem) {
    return tls::update_server_client_ca(ctx_, client_ca_pem);
  }
  return true;
}

// SSL HTTP client implementation
SSLClient::~SSLClient() {
  // Make sure to shut down SSL since shutdown_ssl will resolve to the
  // base function rather than the derived function once we get to the
  // base class destructor, and won't free the SSL (causing a leak).
  // This must happen before the context is freed below: some backends
  // (e.g. mbedTLS) have the SSL session borrow a raw pointer into the
  // context, so freeing the context first leaves close_notify reading
  // freed memory.
  shutdown_ssl_impl(socket_, true);
  if (ctx_) {
    tls::free_context(ctx_);
    ctx_ = nullptr;
  }
}

bool SSLClient::is_valid() const { return ctx_ != nullptr; }

void SSLClient::shutdown_ssl(Socket &socket, bool shutdown_gracefully) {
  shutdown_ssl_impl(socket, shutdown_gracefully);
}

void SSLClient::shutdown_ssl_impl(Socket &socket,
                                         bool shutdown_gracefully) {
  if (socket.sock == INVALID_SOCKET) {
    assert(socket.ssl == nullptr);
    return;
  }
  if (socket.ssl) {
    tls::shutdown(socket.ssl, shutdown_gracefully);
    {
      std::lock_guard<std::mutex> guard(ctx_mutex_);
      tls::free_session(socket.ssl);
    }
    socket.ssl = nullptr;
  }
  assert(socket.ssl == nullptr);
}

bool SSLClient::process_socket(
    const Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &strm)> callback) {
  assert(socket.ssl);
  return detail::process_client_socket_ssl(
      socket.ssl, socket.sock, read_timeout_sec_, read_timeout_usec_,
      write_timeout_sec_, write_timeout_usec_, max_timeout_msec_, start_time,
      std::move(callback));
}

bool SSLClient::is_ssl() const { return true; }

bool SSLClient::create_and_connect_socket(Socket &socket, Error &error) {
  if (!is_valid()) {
    error = Error::SSLConnection;
    return false;
  }
  return ClientImpl::create_and_connect_socket(socket, error);
}

bool SSLClient::setup_proxy_connection(
    Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    Response &res, bool &success, Error &error) {
  if (!is_proxy_enabled_for_host(host_)) { return true; }

  if (!connect_with_proxy(socket, start_time, res, success, error)) {
    return false;
  }

  if (!initialize_ssl(socket, error)) {
    success = false;
    return false;
  }

  return true;
}

// Assumes that socket_mutex_ is locked and that there are no requests in
// flight
bool SSLClient::connect_with_proxy(
    Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    Response &res, bool &success, Error &error) {
  success = true;
  Response proxy_res;
  if (!detail::process_client_socket(
          socket.sock, read_timeout_sec_, read_timeout_usec_,
          write_timeout_sec_, write_timeout_usec_, max_timeout_msec_,
          start_time, [&](Stream &strm) {
            Request req2;
            req2.method = "CONNECT";
            req2.path =
                detail::make_host_and_port_string_always_port(host_, port_);
            if (max_timeout_msec_ > 0) {
              req2.start_time_ = std::chrono::steady_clock::now();
            }
            return process_request(strm, req2, proxy_res, false, error);
          })) {
    // Thread-safe to close everything because we are assuming there are no
    // requests in flight
    shutdown_ssl(socket, true);
    shutdown_socket(socket);
    close_socket(socket);
    success = false;
    return false;
  }

  if (proxy_res.status == StatusCode::ProxyAuthenticationRequired_407) {
    if (!proxy_digest_auth_username_.empty() &&
        !proxy_digest_auth_password_.empty()) {
      std::map<std::string, std::string> auth;
      if (detail::parse_www_authenticate(proxy_res, auth, true)) {
        // Close the current socket and create a new one for the authenticated
        // request
        shutdown_ssl(socket, true);
        shutdown_socket(socket);
        close_socket(socket);

        // Create a new socket for the authenticated CONNECT request
        if (!ensure_socket_connection(socket, error)) {
          success = false;
          output_error_log(error, nullptr);
          return false;
        }

        proxy_res = Response();
        if (!detail::process_client_socket(
                socket.sock, read_timeout_sec_, read_timeout_usec_,
                write_timeout_sec_, write_timeout_usec_, max_timeout_msec_,
                start_time, [&](Stream &strm) {
                  Request req3;
                  req3.method = "CONNECT";
                  req3.path = detail::make_host_and_port_string_always_port(
                      host_, port_);
                  req3.headers.insert(detail::make_digest_authentication_header(
                      req3, auth, 1, detail::random_string(10),
                      proxy_digest_auth_username_, proxy_digest_auth_password_,
                      true));
                  if (max_timeout_msec_ > 0) {
                    req3.start_time_ = std::chrono::steady_clock::now();
                  }
                  return process_request(strm, req3, proxy_res, false, error);
                })) {
          // Thread-safe to close everything because we are assuming there are
          // no requests in flight
          shutdown_ssl(socket, true);
          shutdown_socket(socket);
          close_socket(socket);
          success = false;
          return false;
        }
      }
    }
  }

  // If status code is not 200, proxy request is failed.
  // Set error to ProxyConnection and return proxy response
  // as the response of the request
  if (proxy_res.status != StatusCode::OK_200) {
    error = Error::ProxyConnection;
    output_error_log(error, nullptr);
    res = std::move(proxy_res);
    // Thread-safe to close everything because we are assuming there are
    // no requests in flight
    shutdown_ssl(socket, true);
    shutdown_socket(socket);
    close_socket(socket);
    return false;
  }

  return true;
}

bool SSLClient::ensure_socket_connection(Socket &socket, Error &error) {
  if (!ClientImpl::ensure_socket_connection(socket, error)) { return false; }

  if (is_proxy_enabled_for_host(host_)) { return true; }

  if (!initialize_ssl(socket, error)) {
    shutdown_socket(socket);
    close_socket(socket);
    return false;
  }

  return true;
}

// SSL HTTP client implementation
SSLClient::SSLClient(const std::string &host)
    : SSLClient(host, 443, std::string(), std::string()) {}

SSLClient::SSLClient(const std::string &host, int port)
    : SSLClient(host, port, std::string(), std::string()) {}

void SSLClient::init_ctx() {
  ctx_ = tls::create_client_context();
  if (ctx_) { tls::set_min_version(ctx_, tls::Version::TLS1_2); }
}

void SSLClient::reset_ctx_on_error() {
  last_backend_error_ = tls::get_error();
  tls::free_context(ctx_);
  ctx_ = nullptr;
}

SSLClient::SSLClient(const std::string &host, int port,
                            const std::string &client_cert_path,
                            const std::string &client_key_path,
                            const std::string &private_key_password)
    : ClientImpl(host, port, client_cert_path, client_key_path) {
  init_ctx();
  if (!ctx_) { return; }

  if (!client_cert_path.empty() && !client_key_path.empty()) {
    const char *password =
        private_key_password.empty() ? nullptr : private_key_password.c_str();
    if (!tls::set_client_cert_file(ctx_, client_cert_path.c_str(),
                                   client_key_path.c_str(), password)) {
      reset_ctx_on_error();
    }
  }
}

SSLClient::SSLClient(const std::string &host, int port,
                            const PemMemory &pem)
    : ClientImpl(host, port) {
  init_ctx();
  if (!ctx_) { return; }

  if (pem.cert_pem && pem.key_pem) {
    if (!tls::set_client_cert_pem(ctx_, pem.cert_pem, pem.key_pem,
                                  pem.private_key_password)) {
      reset_ctx_on_error();
    }
  }
}

void SSLClient::set_ca_cert_store(tls::ca_store_t ca_cert_store) {
  if (ca_cert_store && ctx_) {
    // set_ca_store takes ownership of ca_cert_store
    tls::set_ca_store(ctx_, ca_cert_store);
    ca_cert_store_set_ = true;
  } else if (ca_cert_store) {
    tls::free_ca_store(ca_cert_store);
  }
}

void
SSLClient::set_server_certificate_verifier(tls::VerifyCallback verifier) {
  if (!ctx_) { return; }
  tls::set_verify_callback(ctx_, verifier);
}

void SSLClient::set_session_verifier(
    std::function<SSLVerifierResponse(tls::session_t)> verifier) {
  session_verifier_ = std::move(verifier);
}

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
void SSLClient::enable_windows_certificate_verification(bool enabled) {
  enable_windows_cert_verification_ = enabled;
}
#endif

void SSLClient::load_ca_cert_store(const char *ca_cert,
                                          std::size_t size) {
  if (ctx_ && ca_cert && size > 0) {
    ca_cert_pem_.assign(ca_cert, size); // Store for redirect transfer
    tls::load_ca_pem(ctx_, ca_cert, size);
  }
}

bool SSLClient::load_certs() {
  auto ret = true;

  std::call_once(initialize_cert_, [&]() {
    std::lock_guard<std::mutex> guard(ctx_mutex_);

    ret = detail::load_client_ca_config(
        ctx_, ca_cert_file_path_, ca_cert_dir_path_,
        !ca_cert_pem_.empty() || ca_cert_store_set_, system_ca_mode_,
        last_backend_error_);
  });

  return ret;
}

bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
  using namespace tls;

  // Load CA certificates if server verification is enabled
  if (server_certificate_verification_) {
    if (!load_certs()) {
      error = Error::SSLLoadingCerts;
      output_error_log(error, nullptr);
      return false;
    }
  }

  bool is_ip = detail::is_ip_address(host_);

#if defined(CPPHTTPLIB_MBEDTLS_SUPPORT) || defined(CPPHTTPLIB_WOLFSSL_SUPPORT)
  // MbedTLS/wolfSSL need explicit verification mode (OpenSSL uses
  // SSL_VERIFY_NONE by default and performs all verification post-handshake).
  // Chain verification happens during the handshake even for IP hosts; the
  // certificate identity is verified post-handshake via verify_hostname().
  set_verify_client(ctx_, server_certificate_verification_);
#endif

  // Create TLS session
  session_t session = nullptr;
  {
    std::lock_guard<std::mutex> guard(ctx_mutex_);
    session = create_session(ctx_, socket.sock);
  }

  if (!session) {
    error = Error::SSLConnection;
    last_backend_error_ = get_error();
    return false;
  }

  // Use scope_exit to ensure session is freed on error paths
  bool success = false;
  auto session_guard = detail::scope_exit([&] {
    if (!success) { free_session(session); }
  });

  // Set SNI extension (skip for IP addresses per RFC 6066).
  // On MbedTLS, set_sni also enables hostname verification internally.
  // On OpenSSL, set_sni only sets SNI; verification is done post-handshake.
  if (!is_ip) {
    if (!set_sni(session, host_.c_str())) {
      error = Error::SSLConnection;
      last_backend_error_ = get_error();
      return false;
    }
  }

  // Perform non-blocking TLS handshake with timeout
  TlsError tls_err;
  if (!connect_nonblocking(session, socket.sock, connection_timeout_sec_,
                           connection_timeout_usec_, &tls_err)) {
    last_ssl_error_ = static_cast<int>(tls_err.code);
    last_backend_error_ = tls_err.backend_code;
    if (tls_err.code == ErrorCode::CertVerifyFailed) {
      error = Error::SSLServerVerification;
    } else if (tls_err.code == ErrorCode::HostnameMismatch) {
      error = Error::SSLServerHostnameVerification;
    } else {
      error = Error::SSLConnection;
    }
    output_error_log(error, nullptr);
    return false;
  }

  // Post-handshake session verifier callback
  auto verification_status = SSLVerifierResponse::NoDecisionMade;
  if (session_verifier_) { verification_status = session_verifier_(session); }

  if (verification_status == SSLVerifierResponse::CertificateRejected) {
    last_backend_error_ = get_error();
    error = Error::SSLServerVerification;
    output_error_log(error, nullptr);
    return false;
  }

  // Default server certificate verification
  if (verification_status == SSLVerifierResponse::NoDecisionMade &&
      server_certificate_verification_) {
    verify_result_ = tls::get_verify_result(session);
    if (verify_result_ != 0) {
      last_backend_error_ = static_cast<uint64_t>(verify_result_);
      error = Error::SSLServerVerification;
      output_error_log(error, nullptr);
      return false;
    }

    auto server_cert = get_peer_cert(session);
    if (!server_cert) {
      last_backend_error_ = get_error();
      error = Error::SSLServerVerification;
      output_error_log(error, nullptr);
      return false;
    }
    auto cert_guard = detail::scope_exit([&] { free_cert(server_cert); });

    // Hostname verification (post-handshake for all cases).
    // On OpenSSL, verification is always post-handshake (SSL_VERIFY_NONE).
    // On MbedTLS, set_sni already enabled hostname verification during
    // handshake for non-IP hosts, but this check is still needed for IP
    // addresses where SNI is not set.
    if (server_hostname_verification_) {
      if (!verify_hostname(server_cert, host_.c_str())) {
        last_backend_error_ = hostname_mismatch_code();
        error = Error::SSLServerHostnameVerification;
        output_error_log(error, nullptr);
        return false;
      }
    }

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
    // Additional Windows Schannel verification.
    // This provides real-time certificate validation with Windows Update
    // integration, working with both OpenSSL and MbedTLS backends.
    // Skip when a custom CA cert is specified, as the Windows certificate
    // store would not know about user-provided CA certificates. Also skip
    // when system CA trust is explicitly disabled.
    if (enable_windows_cert_verification_ &&
        system_ca_mode_ != SystemCAMode::Disabled &&
        ca_cert_file_path_.empty() && ca_cert_dir_path_.empty() &&
        ca_cert_pem_.empty() && !ca_cert_store_set_) {
      std::vector<unsigned char> der;
      if (get_cert_der(server_cert, der)) {
        uint64_t wincrypt_error = 0;
        if (!detail::verify_cert_with_windows_schannel(
                der, host_, server_hostname_verification_, wincrypt_error)) {
          last_backend_error_ = wincrypt_error;
          error = Error::SSLServerVerification;
          output_error_log(error, nullptr);
          return false;
        }
      }
    }
#endif
  }

  success = true;
  socket.ssl = session;
  return true;
}

void Client::set_digest_auth(const std::string &username,
                                    const std::string &password) {
  cli_->set_digest_auth(username, password);
}

void Client::set_proxy_digest_auth(const std::string &username,
                                          const std::string &password) {
  cli_->set_proxy_digest_auth(username, password);
}

void Client::enable_server_certificate_verification(bool enabled) {
  cli_->enable_server_certificate_verification(enabled);
}

void Client::enable_server_hostname_verification(bool enabled) {
  cli_->enable_server_hostname_verification(enabled);
}

void Client::enable_system_ca(bool enabled) {
  cli_->enable_system_ca(enabled);
}

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
void Client::enable_windows_certificate_verification(bool enabled) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).enable_windows_certificate_verification(
        enabled);
  }
}
#endif

void Client::set_ca_cert_path(const std::string &ca_cert_file_path,
                                     const std::string &ca_cert_dir_path) {
  cli_->set_ca_cert_path(ca_cert_file_path, ca_cert_dir_path);
}

void Client::set_ca_cert_store(tls::ca_store_t ca_cert_store) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_ca_cert_store(ca_cert_store);
  } else if (ca_cert_store) {
    tls::free_ca_store(ca_cert_store);
  }
}

void Client::load_ca_cert_store(const char *ca_cert, std::size_t size) {
  if (is_ssl_) {
    // Use the PEM-based path so the CA data is retained for redirect transfer
    static_cast<SSLClient &>(*cli_).load_ca_cert_store(ca_cert, size);
  }
}

void
Client::set_server_certificate_verifier(tls::VerifyCallback verifier) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_server_certificate_verifier(
        std::move(verifier));
  }
}

void Client::set_session_verifier(
    std::function<SSLVerifierResponse(tls::session_t)> verifier) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_session_verifier(std::move(verifier));
  }
}

tls::ctx_t Client::tls_context() const {
  if (is_ssl_) { return static_cast<SSLClient &>(*cli_).tls_context(); }
  return nullptr;
}

#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 7: TLS abstraction layer - Common API
 */

#ifdef CPPHTTPLIB_SSL_ENABLED

namespace tls {

// Helper for PeerCert construction
PeerCert get_peer_cert_from_session(const_session_t session) {
  return PeerCert(get_peer_cert(session));
}

namespace impl {

VerifyCallback &get_verify_callback() {
  static thread_local VerifyCallback callback;
  return callback;
}

VerifyCallback &get_mbedtls_verify_callback() {
  static thread_local VerifyCallback callback;
  return callback;
}

// Check if a string is an IPv4 address
bool is_ipv4_address(const std::string &str) {
  int dots = 0;
  for (char c : str) {
    if (c == '.') {
      dots++;
    } else if (!detail::is_ascii_digit(c)) {
      return false;
    }
  }
  return dots == 3;
}

// Parse IPv4 address string to bytes
bool parse_ipv4(const std::string &str, unsigned char *out) {
  const char *p = str.c_str();
  for (int i = 0; i < 4; i++) {
    if (i > 0) {
      if (*p != '.') { return false; }
      p++;
    }
    int val = 0;
    int digits = 0;
    while (detail::is_ascii_digit(*p)) {
      val = val * 10 + (*p - '0');
      if (val > 255) { return false; }
      p++;
      digits++;
    }
    if (digits == 0) { return false; }
    // Reject leading zeros (e.g., "01.002.03.04") to prevent ambiguity
    if (digits > 1 && *(p - digits) == '0') { return false; }
    out[i] = static_cast<unsigned char>(val);
  }
  return *p == '\0';
}

// Parse an IP literal (IPv4 or IPv6) into raw network-order bytes.
// `out` must have room for at least 16 bytes. Returns the address length
// (4 for IPv4, 16 for IPv6) on success, or 0 if the string is not an IP
// literal. Used to match a host against iPAddress SANs the same way the
// OpenSSL backend does via X509_check_ip.
size_t parse_ip_address(const std::string &str, unsigned char *out) {
  if (is_ipv4_address(str)) { return parse_ipv4(str, out) ? 4 : 0; }
  struct in6_addr addr6 = {};
  if (inet_pton(AF_INET6, str.c_str(), &addr6) == 1) {
    memcpy(out, &addr6, 16);
    return 16;
  }
  return 0;
}

#ifdef _WIN32
// Enumerate Windows system certificates and call callback with DER data
template <typename Callback>
bool enumerate_windows_system_certs(Callback cb) {
  bool loaded = false;
  static const wchar_t *store_names[] = {L"ROOT", L"CA"};
  for (auto store_name : store_names) {
    HCERTSTORE hStore = CertOpenSystemStoreW(0, store_name);
    if (hStore) {
      PCCERT_CONTEXT pContext = nullptr;
      while ((pContext = CertEnumCertificatesInStore(hStore, pContext)) !=
             nullptr) {
        if (cb(pContext->pbCertEncoded, pContext->cbCertEncoded)) {
          loaded = true;
        }
      }
      CertCloseStore(hStore, 0);
    }
  }
  return loaded;
}
#endif

#ifdef CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN
// Enumerate macOS Keychain certificates and call callback with DER data
template <typename Callback>
bool enumerate_macos_keychain_certs(Callback cb) {
  bool loaded = false;
  const SecTrustSettingsDomain domains[] = {
      kSecTrustSettingsDomainSystem,
      kSecTrustSettingsDomainAdmin,
      kSecTrustSettingsDomainUser,
  };
  for (auto domain : domains) {
    CFArrayRef certs = nullptr;
    OSStatus status = SecTrustSettingsCopyCertificates(domain, &certs);
    if (status != errSecSuccess || !certs) {
      if (certs) CFRelease(certs);
      continue;
    }
    CFIndex count = CFArrayGetCount(certs);
    for (CFIndex i = 0; i < count; i++) {
      SecCertificateRef cert =
          (SecCertificateRef)CFArrayGetValueAtIndex(certs, i);
      CFDataRef data = SecCertificateCopyData(cert);
      if (data) {
        if (cb(CFDataGetBytePtr(data),
               static_cast<size_t>(CFDataGetLength(data)))) {
          loaded = true;
        }
        CFRelease(data);
      }
    }
    CFRelease(certs);
  }
  return loaded;
}
#endif

#if !defined(_WIN32) && !(defined(__APPLE__) &&                                \
                          defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN))
// Common CA certificate file paths on Linux/Unix
const char **system_ca_paths() {
  static const char *paths[] = {
      "/etc/ssl/certs/ca-certificates.crt", // Debian/Ubuntu
      "/etc/pki/tls/certs/ca-bundle.crt",   // RHEL/CentOS
      "/etc/ssl/ca-bundle.pem",             // OpenSUSE
      "/etc/pki/tls/cacert.pem",            // OpenELEC
      "/etc/ssl/cert.pem",                  // Alpine, FreeBSD
      nullptr};
  return paths;
}

// Common CA certificate directory paths on Linux/Unix
const char **system_ca_dirs() {
  static const char *dirs[] = {"/etc/ssl/certs",             // Debian/Ubuntu
                               "/etc/pki/tls/certs",         // RHEL/CentOS
                               "/usr/share/ca-certificates", // Other
                               nullptr};
  return dirs;
}
#endif

} // namespace impl

bool set_client_ca_file(ctx_t ctx, const char *ca_file,
                               const char *ca_dir) {
  if (!ctx) { return false; }

  bool success = true;
  if (ca_file && *ca_file) {
    if (!load_ca_file(ctx, ca_file)) { success = false; }
  }
  if (ca_dir && *ca_dir) {
    if (!load_ca_dir(ctx, ca_dir)) { success = false; }
  }

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
  // Set CA list for client certificate request (CertificateRequest message)
  if (ca_file && *ca_file) {
    auto list = SSL_load_client_CA_file(ca_file);
    if (list) { SSL_CTX_set_client_CA_list(static_cast<SSL_CTX *>(ctx), list); }
  }
#endif

  return success;
}

bool set_server_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  return set_client_cert_pem(ctx, cert, key, password);
}

bool set_server_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  return set_client_cert_file(ctx, cert_path, key_path, password);
}

// PeerCert implementation
PeerCert::PeerCert() = default;

PeerCert::PeerCert(cert_t cert) : cert_(cert) {}

PeerCert::PeerCert(PeerCert &&other) noexcept : cert_(other.cert_) {
  other.cert_ = nullptr;
}

PeerCert &PeerCert::operator=(PeerCert &&other) noexcept {
  if (this != &other) {
    if (cert_) { free_cert(cert_); }
    cert_ = other.cert_;
    other.cert_ = nullptr;
  }
  return *this;
}

PeerCert::~PeerCert() {
  if (cert_) { free_cert(cert_); }
}

PeerCert::operator bool() const { return cert_ != nullptr; }

std::string PeerCert::subject_cn() const {
  return cert_ ? get_cert_subject_cn(cert_) : std::string();
}

std::string PeerCert::issuer_name() const {
  return cert_ ? get_cert_issuer_name(cert_) : std::string();
}

bool PeerCert::check_hostname(const char *hostname) const {
  return cert_ ? verify_hostname(cert_, hostname) : false;
}

std::vector<SanEntry> PeerCert::sans() const {
  std::vector<SanEntry> result;
  if (cert_) { get_cert_sans(cert_, result); }
  return result;
}

bool PeerCert::validity(time_t &not_before, time_t &not_after) const {
  return cert_ ? get_cert_validity(cert_, not_before, not_after) : false;
}

std::string PeerCert::serial() const {
  return cert_ ? get_cert_serial(cert_) : std::string();
}

// VerifyContext method implementations
std::string VerifyContext::subject_cn() const {
  return cert ? get_cert_subject_cn(cert) : std::string();
}

std::string VerifyContext::issuer_name() const {
  return cert ? get_cert_issuer_name(cert) : std::string();
}

bool VerifyContext::check_hostname(const char *hostname) const {
  return cert ? verify_hostname(cert, hostname) : false;
}

std::vector<SanEntry> VerifyContext::sans() const {
  std::vector<SanEntry> result;
  if (cert) { get_cert_sans(cert, result); }
  return result;
}

bool VerifyContext::validity(time_t &not_before,
                                    time_t &not_after) const {
  return cert ? get_cert_validity(cert, not_before, not_after) : false;
}

std::string VerifyContext::serial() const {
  return cert ? get_cert_serial(cert) : std::string();
}

// TlsError static method implementation
std::string TlsError::verify_error_to_string(long error_code) {
  return verify_error_string(error_code);
}

} // namespace tls

// Request::peer_cert() implementation
tls::PeerCert Request::peer_cert() const {
  return tls::get_peer_cert_from_session(ssl);
}

// Request::sni() implementation
std::string Request::sni() const {
  if (!ssl) { return std::string(); }
  const char *s = tls::get_sni(ssl);
  return s ? std::string(s) : std::string();
}

#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 8: TLS abstraction layer - OpenSSL backend
 */

/*
 * OpenSSL Backend Implementation
 */

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
namespace tls {

namespace impl {

// Helper to map OpenSSL SSL_get_error to ErrorCode
ErrorCode map_ssl_error(int ssl_error, int &out_errno) {
  switch (ssl_error) {
  case SSL_ERROR_NONE: return ErrorCode::Success;
  case SSL_ERROR_WANT_READ: return ErrorCode::WantRead;
  case SSL_ERROR_WANT_WRITE: return ErrorCode::WantWrite;
  case SSL_ERROR_ZERO_RETURN: return ErrorCode::PeerClosed;
  case SSL_ERROR_SYSCALL: out_errno = errno; return ErrorCode::SyscallError;
  case SSL_ERROR_SSL:
  default: return ErrorCode::Fatal;
  }
}

// Helper: Create client CA list from PEM string
// Returns a new STACK_OF(X509_NAME)* or nullptr on failure
// Caller takes ownership of returned list
STACK_OF(X509_NAME) *
    create_client_ca_list_from_pem(const char *ca_pem) {
  if (!ca_pem) { return nullptr; }

  auto ca_list = sk_X509_NAME_new_null();
  if (!ca_list) { return nullptr; }

  BIO *bio = BIO_new_mem_buf(ca_pem, -1);
  if (!bio) {
    sk_X509_NAME_pop_free(ca_list, X509_NAME_free);
    return nullptr;
  }

  X509 *cert = nullptr;
  while ((cert = PEM_read_bio_X509(bio, nullptr, nullptr, nullptr)) !=
         nullptr) {
    const X509_NAME *name = X509_get_subject_name(cert);
    if (name) {
      sk_X509_NAME_push(ca_list, X509_NAME_dup(const_cast<X509_NAME *>(name)));
    }
    X509_free(cert);
  }
  BIO_free(bio);

  return ca_list;
}

// OpenSSL verify callback wrapper
int openssl_verify_callback(int preverify_ok, X509_STORE_CTX *ctx) {
  auto &callback = get_verify_callback();
  if (!callback) { return preverify_ok; }

  // Get SSL object from X509_STORE_CTX
  auto ssl = static_cast<SSL *>(
      X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx()));
  if (!ssl) { return preverify_ok; }

  // Get current certificate and depth
  auto cert = X509_STORE_CTX_get_current_cert(ctx);
  int depth = X509_STORE_CTX_get_error_depth(ctx);
  int error = X509_STORE_CTX_get_error(ctx);

  // Build context
  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(ssl);
  verify_ctx.cert = static_cast<cert_t>(cert);
  verify_ctx.depth = depth;
  verify_ctx.preverify_ok = (preverify_ok != 0);
  verify_ctx.error_code = error;
  verify_ctx.error_string =
      (error != X509_V_OK) ? X509_verify_cert_error_string(error) : nullptr;

  return callback(verify_ctx) ? 1 : 0;
}

// X509_STORE_get0_objects is deprecated since OpenSSL 4.0 because it is not
// thread-safe; X509_STORE_get1_objects (OpenSSL 3.3+) returns a snapshot
// that must be released with release_store_objects
#if !defined(OPENSSL_IS_BORINGSSL) && !defined(LIBRESSL_VERSION_NUMBER) &&     \
    OPENSSL_VERSION_NUMBER >= 0x30300000L
#define CPPHTTPLIB_HAS_X509_STORE_GET1_OBJECTS
#endif

STACK_OF(X509_OBJECT) * get_store_objects(X509_STORE *store) {
#ifdef CPPHTTPLIB_HAS_X509_STORE_GET1_OBJECTS
  return X509_STORE_get1_objects(store);
#else
  return X509_STORE_get0_objects(store);
#endif
}

void release_store_objects(STACK_OF(X509_OBJECT) * objs) {
#ifdef CPPHTTPLIB_HAS_X509_STORE_GET1_OBJECTS
  sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free);
#else
  (void)objs; // get0 variant returns an internal pointer; nothing to free
#endif
}

} // namespace impl

ctx_t create_client_context() {
  SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
  if (ctx) {
    // Disable auto-retry to properly handle non-blocking I/O
    SSL_CTX_clear_mode(ctx, SSL_MODE_AUTO_RETRY);
    // Set minimum TLS version
    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
  }
  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { SSL_CTX_free(static_cast<SSL_CTX *>(ctx)); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) return false;
  return SSL_CTX_set_min_proto_version(static_cast<SSL_CTX *>(ctx),
                                       static_cast<int>(version)) == 1;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem || len == 0) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  auto bio = BIO_new_mem_buf(pem, static_cast<int>(len));
  if (!bio) return false;

  bool ok = true;
  X509 *cert = nullptr;
  while ((cert = PEM_read_bio_X509(bio, nullptr, nullptr, nullptr)) !=
         nullptr) {
    if (X509_STORE_add_cert(store, cert) != 1) {
      // Ignore duplicate errors
      auto err = ERR_peek_last_error();
      if (ERR_GET_REASON(err) != X509_R_CERT_ALREADY_IN_HASH_TABLE) {
        ok = false;
      }
    }
    X509_free(cert);
    if (!ok) break;
  }
  BIO_free(bio);

  // Clear any "no more certificates" errors
  ERR_clear_error();
  return ok;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) return false;
  return SSL_CTX_load_verify_locations(static_cast<SSL_CTX *>(ctx), file_path,
                                       nullptr) == 1;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) return false;
  return SSL_CTX_load_verify_locations(static_cast<SSL_CTX *>(ctx), nullptr,
                                       dir_path) == 1;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) return false;
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

#ifdef _WIN32
  // Windows: Load from system certificate store (ROOT and CA)
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  bool loaded_any = false;
  static const wchar_t *store_names[] = {L"ROOT", L"CA"};
  for (auto store_name : store_names) {
    auto hStore = CertOpenSystemStoreW(NULL, store_name);
    if (!hStore) continue;

    PCCERT_CONTEXT pContext = nullptr;
    while ((pContext = CertEnumCertificatesInStore(hStore, pContext)) !=
           nullptr) {
      const unsigned char *data = pContext->pbCertEncoded;
      auto x509 = d2i_X509(nullptr, &data, pContext->cbCertEncoded);
      if (x509) {
        if (X509_STORE_add_cert(store, x509) == 1) { loaded_any = true; }
        X509_free(x509);
      }
    }
    CertCloseStore(hStore, 0);
  }
  return loaded_any;

#elif defined(__APPLE__)
#ifdef CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN
  // macOS: Load from Keychain
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  bool loaded_any = false;
  const SecTrustSettingsDomain domains[] = {
      kSecTrustSettingsDomainSystem,
      kSecTrustSettingsDomainAdmin,
      kSecTrustSettingsDomainUser,
  };
  for (auto domain : domains) {
    CFArrayRef certs = nullptr;
    if (SecTrustSettingsCopyCertificates(domain, &certs) != errSecSuccess ||
        !certs) {
      if (certs) CFRelease(certs);
      continue;
    }
    auto count = CFArrayGetCount(certs);
    for (CFIndex i = 0; i < count; i++) {
      auto cert = reinterpret_cast<SecCertificateRef>(
          const_cast<void *>(CFArrayGetValueAtIndex(certs, i)));
      CFDataRef der = SecCertificateCopyData(cert);
      if (der) {
        const unsigned char *data = CFDataGetBytePtr(der);
        auto x509 = d2i_X509(nullptr, &data, CFDataGetLength(der));
        if (x509) {
          if (X509_STORE_add_cert(store, x509) == 1) { loaded_any = true; }
          X509_free(x509);
        }
        CFRelease(der);
      }
    }
    CFRelease(certs);
  }
  return loaded_any || SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#else
  return SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#endif

#else
  // Other Unix: use default verify paths
  return SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#endif
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Load certificate
  auto cert_bio = BIO_new_mem_buf(cert, -1);
  if (!cert_bio) return false;

  auto x509 = PEM_read_bio_X509(cert_bio, nullptr, nullptr, nullptr);
  BIO_free(cert_bio);
  if (!x509) return false;

  auto cert_ok = SSL_CTX_use_certificate(ssl_ctx, x509) == 1;
  X509_free(x509);
  if (!cert_ok) return false;

  // Load private key
  auto key_bio = BIO_new_mem_buf(key, -1);
  if (!key_bio) return false;

  auto pkey = PEM_read_bio_PrivateKey(key_bio, nullptr, nullptr,
                                      password ? const_cast<char *>(password)
                                               : nullptr);
  BIO_free(key_bio);
  if (!pkey) return false;

  auto key_ok = SSL_CTX_use_PrivateKey(ssl_ctx, pkey) == 1;
  EVP_PKEY_free(pkey);

  return key_ok && SSL_CTX_check_private_key(ssl_ctx) == 1;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  if (password && password[0] != '\0') {
    SSL_CTX_set_default_passwd_cb_userdata(
        ssl_ctx, reinterpret_cast<void *>(const_cast<char *>(password)));
  }

  return SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_path) == 1 &&
         SSL_CTX_use_PrivateKey_file(ssl_ctx, key_path, SSL_FILETYPE_PEM) == 1;
}

ctx_t create_server_context() {
  SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
  if (ctx) {
    SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION |
                                 SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
  }
  return static_cast<ctx_t>(ctx);
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) return;
  SSL_CTX_set_verify(static_cast<SSL_CTX *>(ctx),
                     require
                         ? (SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT)
                         : SSL_VERIFY_NONE,
                     nullptr);
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) return nullptr;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  SSL *ssl = SSL_new(ssl_ctx);
  if (!ssl) return nullptr;

  // Disable auto-retry for proper non-blocking I/O handling
  SSL_clear_mode(ssl, SSL_MODE_AUTO_RETRY);

  auto bio = BIO_new_socket(static_cast<int>(sock), BIO_NOCLOSE);
  if (!bio) {
    SSL_free(ssl);
    return nullptr;
  }

  SSL_set_bio(ssl, bio, bio);
  return static_cast<session_t>(ssl);
}

void free_session(session_t session) {
  if (session) { SSL_free(static_cast<SSL *>(session)); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) return false;

  auto ssl = static_cast<SSL *>(session);

  // Set SNI (Server Name Indication) only - does not enable verification
#if defined(OPENSSL_IS_BORINGSSL)
  return SSL_set_tlsext_host_name(ssl, hostname) == 1;
#else
  // Direct call instead of macro to suppress -Wold-style-cast warning
  return SSL_ctrl(ssl, SSL_CTRL_SET_TLSEXT_HOSTNAME, TLSEXT_NAMETYPE_host_name,
                  static_cast<void *>(const_cast<char *>(hostname))) == 1;
#endif
}

bool set_hostname(session_t session, const char *hostname) {
  if (!session || !hostname) return false;

  auto ssl = static_cast<SSL *>(session);

  // Enable hostname verification
  auto param = SSL_get0_param(ssl);
  if (!param) return false;

  if (detail::is_ip_address(hostname)) {
    // RFC 6066: SNI must not be set for IP addresses; verify against the
    // certificate's IP SANs instead of its DNS names
    if (X509_VERIFY_PARAM_set1_ip_asc(param, hostname) != 1) { return false; }
  } else {
    // Set SNI (Server Name Indication)
    if (!set_sni(session, hostname)) { return false; }

    X509_VERIFY_PARAM_set_hostflags(param,
                                    X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS);
    if (X509_VERIFY_PARAM_set1_host(param, hostname, 0) != 1) { return false; }
  }

  SSL_set_verify(ssl, SSL_VERIFY_PEER, nullptr);
  return true;
}

TlsError connect(session_t session) {
  if (!session) { return TlsError(); }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_connect(ssl);

  TlsError err;
  if (ret == 1) {
    err.code = ErrorCode::Success;
  } else {
    auto ssl_err = SSL_get_error(ssl, ret);
    err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
    err.backend_code = ERR_get_error();
  }
  return err;
}

TlsError accept(session_t session) {
  if (!session) { return TlsError(); }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_accept(ssl);

  TlsError err;
  if (ret == 1) {
    err.code = ErrorCode::Success;
  } else {
    auto ssl_err = SSL_get_error(ssl, ret);
    err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
    err.backend_code = ERR_get_error();
  }
  return err;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto ssl = static_cast<SSL *>(session);
  auto bio = SSL_get_rbio(ssl);

  // Set non-blocking mode for handshake
  detail::set_nonblocking(sock, true);
  if (bio) { BIO_set_nbio(bio, 1); }

  auto cleanup = detail::scope_exit([&]() {
    // Restore blocking mode after handshake
    if (bio) { BIO_set_nbio(bio, 0); }
    detail::set_nonblocking(sock, false);
  });

  auto res = 0;
  while ((res = SSL_connect(ssl)) != 1) {
    auto ssl_err = SSL_get_error(ssl, res);
    switch (ssl_err) {
    case SSL_ERROR_WANT_READ:
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    case SSL_ERROR_WANT_WRITE:
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    default: break;
    }
    if (err) {
      err->code = impl::map_ssl_error(ssl_err, err->sys_errno);
      err->backend_code = ERR_get_error();
    }
    return false;
  }
  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto ssl = static_cast<SSL *>(session);
  auto bio = SSL_get_rbio(ssl);

  // Set non-blocking mode for handshake
  detail::set_nonblocking(sock, true);
  if (bio) { BIO_set_nbio(bio, 1); }

  auto cleanup = detail::scope_exit([&]() {
    // Restore blocking mode after handshake
    if (bio) { BIO_set_nbio(bio, 0); }
    detail::set_nonblocking(sock, false);
  });

  auto res = 0;
  while ((res = SSL_accept(ssl)) != 1) {
    auto ssl_err = SSL_get_error(ssl, res);
    switch (ssl_err) {
    case SSL_ERROR_WANT_READ:
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    case SSL_ERROR_WANT_WRITE:
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    default: break;
    }
    if (err) {
      err->code = impl::map_ssl_error(ssl_err, err->sys_errno);
      err->backend_code = ERR_get_error();
    }
    return false;
  }
  if (err) { err->code = ErrorCode::Success; }
  return true;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto ssl = static_cast<SSL *>(session);
  constexpr auto max_len =
      static_cast<size_t>((std::numeric_limits<int>::max)());
  if (len > max_len) { len = max_len; }
  auto ret = SSL_read(ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return ret;
  }

  auto ssl_err = SSL_get_error(ssl, ret);
  err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
  if (err.code == ErrorCode::PeerClosed) {
    return 0;
  } // Gracefully handle the peer closed state.
  if (err.code == ErrorCode::Fatal) { err.backend_code = ERR_get_error(); }
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_write(ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return ret;
  }

  auto ssl_err = SSL_get_error(ssl, ret);
  err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
  if (err.code == ErrorCode::Fatal) { err.backend_code = ERR_get_error(); }
  return -1;
}

int pending(const_session_t session) {
  if (!session) return 0;
  return SSL_pending(static_cast<SSL *>(const_cast<void *>(session)));
}

void shutdown(session_t session, bool graceful) {
  if (!session) return;

  auto ssl = static_cast<SSL *>(session);
  if (graceful) {
    // First call sends close_notify
    if (SSL_shutdown(ssl) == 0) {
      // Second call waits for peer's close_notify
      SSL_shutdown(ssl);
    }
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session) return true;

  // Temporarily set socket to non-blocking to avoid blocking on SSL_peek
  detail::set_nonblocking(sock, true);
  auto se = detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  auto ssl = static_cast<SSL *>(session);
  char buf;
  auto ret = SSL_peek(ssl, &buf, 1);
  if (ret > 0) return false;

  auto err = SSL_get_error(ssl, ret);
  return err == SSL_ERROR_ZERO_RETURN;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) return nullptr;
  return static_cast<cert_t>(SSL_get1_peer_certificate(
      static_cast<SSL *>(const_cast<void *>(session))));
}

void free_cert(cert_t cert) {
  if (cert) { X509_free(static_cast<X509 *>(cert)); }
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) return false;

  auto x509 = static_cast<X509 *>(cert);

  // Use X509_check_ip_asc for IP addresses, X509_check_host for DNS names
  if (detail::is_ip_address(hostname)) {
    return X509_check_ip_asc(x509, hostname, 0) == 1;
  }
  return X509_check_host(x509, hostname, strlen(hostname), 0, nullptr) == 1;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(X509_V_ERR_HOSTNAME_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) return X509_V_ERR_UNSPECIFIED;
  return SSL_get_verify_result(static_cast<SSL *>(const_cast<void *>(session)));
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);
  auto subject_name = X509_get_subject_name(x509);
  if (!subject_name) return "";

  // X509_NAME_get_text_by_NID is deprecated since OpenSSL 4.0
  auto idx = X509_NAME_get_index_by_NID(subject_name, NID_commonName, -1);
  if (idx < 0) return "";

  auto entry = X509_NAME_get_entry(subject_name, idx);
  if (!entry) return "";

  auto data = X509_NAME_ENTRY_get_data(entry);
  if (!data) return "";

  return std::string(
      reinterpret_cast<const char *>(ASN1_STRING_get0_data(data)),
      static_cast<size_t>(ASN1_STRING_length(data)));
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);
  auto issuer_name = X509_get_issuer_name(x509);
  if (!issuer_name) return "";

  char buf[256];
  X509_NAME_oneline(issuer_name, buf, sizeof(buf));
  return std::string(buf);
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);

  auto names = static_cast<GENERAL_NAMES *>(
      X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));
  if (!names) return true; // No SANs is valid

  auto count = sk_GENERAL_NAME_num(names);
  for (decltype(count) i = 0; i < count; i++) {
    auto gen = sk_GENERAL_NAME_value(names, i);
    if (!gen) continue;

    SanEntry entry;
    switch (gen->type) {
    case GEN_DNS:
      entry.type = SanType::DNS;
      if (gen->d.dNSName) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.dNSName)),
            static_cast<size_t>(ASN1_STRING_length(gen->d.dNSName)));
      }
      break;
    case GEN_IPADD:
      entry.type = SanType::IP;
      if (gen->d.iPAddress) {
        auto data = ASN1_STRING_get0_data(gen->d.iPAddress);
        auto len = ASN1_STRING_length(gen->d.iPAddress);
        if (len == 4) {
          // IPv4
          char buf[INET_ADDRSTRLEN];
          inet_ntop(AF_INET, data, buf, sizeof(buf));
          entry.value = buf;
        } else if (len == 16) {
          // IPv6
          char buf[INET6_ADDRSTRLEN];
          inet_ntop(AF_INET6, data, buf, sizeof(buf));
          entry.value = buf;
        }
      }
      break;
    case GEN_EMAIL:
      entry.type = SanType::EMAIL;
      if (gen->d.rfc822Name) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.rfc822Name)),
            static_cast<size_t>(ASN1_STRING_length(gen->d.rfc822Name)));
      }
      break;
    case GEN_URI:
      entry.type = SanType::URI;
      if (gen->d.uniformResourceIdentifier) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.uniformResourceIdentifier)),
            static_cast<size_t>(
                ASN1_STRING_length(gen->d.uniformResourceIdentifier)));
      }
      break;
    default: entry.type = SanType::OTHER; break;
    }

    if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
  }

  GENERAL_NAMES_free(names);
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);

  auto nb = X509_get0_notBefore(x509);
  auto na = X509_get0_notAfter(x509);
  if (!nb || !na) return false;

  ASN1_TIME *epoch = ASN1_TIME_new();
  if (!epoch) return false;
  auto se = detail::scope_exit([&] { ASN1_TIME_free(epoch); });

  if (!ASN1_TIME_set(epoch, 0)) return false;

  int pday, psec;

  if (!ASN1_TIME_diff(&pday, &psec, epoch, nb)) return false;
  not_before = 86400 * (time_t)pday + psec;

  if (!ASN1_TIME_diff(&pday, &psec, epoch, na)) return false;
  not_after = 86400 * (time_t)pday + psec;

  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);

  auto serial = X509_get_serialNumber(x509);
  if (!serial) return "";

  auto bn = ASN1_INTEGER_to_BN(serial, nullptr);
  if (!bn) return "";

  auto hex = BN_bn2hex(bn);
  BN_free(bn);
  if (!hex) return "";

  std::string result(hex);
  OPENSSL_free(hex);
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);
  auto len = i2d_X509(x509, nullptr);
  if (len < 0) return false;
  der.resize(static_cast<size_t>(len));
  auto p = der.data();
  i2d_X509(x509, &p);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto ssl = static_cast<SSL *>(const_cast<void *>(session));
  return SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
}

uint64_t peek_error() { return ERR_peek_last_error(); }

uint64_t get_error() { return ERR_get_error(); }

std::string error_string(uint64_t code) {
  char buf[256];
  ERR_error_string_n(static_cast<unsigned long>(code), buf, sizeof(buf));
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  auto mem = BIO_new_mem_buf(pem, static_cast<int>(len));
  if (!mem) { return nullptr; }
  auto mem_guard = detail::scope_exit([&] { BIO_free_all(mem); });

  auto inf = PEM_X509_INFO_read_bio(mem, nullptr, nullptr, nullptr);
  if (!inf) { return nullptr; }

  auto store = X509_STORE_new();
  if (store) {
    for (auto i = 0; i < static_cast<int>(sk_X509_INFO_num(inf)); i++) {
      auto itmp = sk_X509_INFO_value(inf, i);
      if (!itmp) { continue; }
      if (itmp->x509) { X509_STORE_add_cert(store, itmp->x509); }
      if (itmp->crl) { X509_STORE_add_crl(store, itmp->crl); }
    }
  }

  sk_X509_INFO_pop_free(inf, X509_INFO_free);
  return static_cast<ca_store_t>(store);
}

void free_ca_store(ca_store_t store) {
  if (store) { X509_STORE_free(static_cast<X509_STORE *>(store)); }
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  auto x509_store = static_cast<X509_STORE *>(store);

  // Check if same store is already set
  if (SSL_CTX_get_cert_store(ssl_ctx) == x509_store) { return true; }

  // SSL_CTX_set_cert_store takes ownership and frees the old store
  SSL_CTX_set_cert_store(ssl_ctx, x509_store);
  return true;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) { return 0; }

  auto objs = impl::get_store_objects(store);
  if (!objs) { return 0; }
  auto se = detail::scope_exit([&] { impl::release_store_objects(objs); });

  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (!obj) { continue; }
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto x509 = X509_OBJECT_get0_X509(obj);
      if (x509) {
        // Increment reference count so caller can free it
        X509_up_ref(x509);
        certs.push_back(static_cast<cert_t>(x509));
      }
    }
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) { return names; }

  auto objs = impl::get_store_objects(store);
  if (!objs) { return names; }
  auto se = detail::scope_exit([&] { impl::release_store_objects(objs); });

  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (!obj) { continue; }
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto x509 = X509_OBJECT_get0_X509(obj);
      if (x509) {
        auto subject = X509_get_subject_name(x509);
        if (subject) {
          char buf[512];
          X509_NAME_oneline(subject, buf, sizeof(buf));
          names.push_back(buf);
        }
      }
    }
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Load certificate from PEM
  auto cert_bio = BIO_new_mem_buf(cert_pem, -1);
  if (!cert_bio) { return false; }
  auto cert = PEM_read_bio_X509(cert_bio, nullptr, nullptr, nullptr);
  BIO_free(cert_bio);
  if (!cert) { return false; }

  // Load private key from PEM
  auto key_bio = BIO_new_mem_buf(key_pem, -1);
  if (!key_bio) {
    X509_free(cert);
    return false;
  }
  auto key = PEM_read_bio_PrivateKey(key_bio, nullptr, nullptr,
                                     password ? const_cast<char *>(password)
                                              : nullptr);
  BIO_free(key_bio);
  if (!key) {
    X509_free(cert);
    return false;
  }

  // Update certificate and key
  auto ret = SSL_CTX_use_certificate(ssl_ctx, cert) == 1 &&
             SSL_CTX_use_PrivateKey(ssl_ctx, key) == 1;

  X509_free(cert);
  EVP_PKEY_free(key);
  return ret;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Create new X509_STORE from PEM
  auto store = create_ca_store(ca_pem, strlen(ca_pem));
  if (!store) { return false; }

  // SSL_CTX_set_cert_store takes ownership
  SSL_CTX_set_cert_store(ssl_ctx, static_cast<X509_STORE *>(store));

  // Set client CA list for client certificate request
  auto ca_list = impl::create_client_ca_list_from_pem(ca_pem);
  if (ca_list) {
    // SSL_CTX_set_client_CA_list takes ownership of ca_list
    SSL_CTX_set_client_CA_list(ssl_ctx, ca_list);
  }

  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  impl::get_verify_callback() = std::move(callback);

  if (impl::get_verify_callback()) {
    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, impl::openssl_verify_callback);
  } else {
    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto ssl = static_cast<SSL *>(const_cast<void *>(session));
  return SSL_get_verify_result(ssl);
}

std::string verify_error_string(long error_code) {
  if (error_code == X509_V_OK) { return ""; }
  const char *str = X509_verify_cert_error_string(static_cast<int>(error_code));
  return str ? str : "unknown error";
}

} // namespace tls

#endif // CPPHTTPLIB_OPENSSL_SUPPORT

/*
 * Group 9: TLS abstraction layer - Mbed TLS backend
 */

/*
 * Mbed TLS Backend Implementation
 */

#ifdef CPPHTTPLIB_MBEDTLS_SUPPORT
namespace tls {

namespace impl {

// Mbed TLS session wrapper
struct MbedTlsSession {
  mbedtls_ssl_context ssl;
  socket_t sock = INVALID_SOCKET;
  std::string hostname;     // For client: set via set_sni
  std::string sni_hostname; // For server: received from client via SNI callback

  // Mbed TLS has no SSL_peek() equivalent, so is_peer_closed() must probe with
  // a real 1-byte mbedtls_ssl_read(). If that probe lands on application data
  // (e.g. a response that arrived while this side was still in its post-write
  // check), the byte is pushed back here and served by the next read().
  unsigned char peeked_byte = 0;
  bool has_peeked_byte = false;

  MbedTlsSession() { mbedtls_ssl_init(&ssl); }

  ~MbedTlsSession() { mbedtls_ssl_free(&ssl); }

  MbedTlsSession(const MbedTlsSession &) = delete;
  MbedTlsSession &operator=(const MbedTlsSession &) = delete;
};

// Thread-local error code accessor for Mbed TLS (since it doesn't have an error
// queue)
int &mbedtls_last_error() {
  static thread_local int err = 0;
  return err;
}

// Helper to map Mbed TLS error to ErrorCode
ErrorCode map_mbedtls_error(int ret, int &out_errno) {
  if (ret == 0) { return ErrorCode::Success; }
  if (ret == MBEDTLS_ERR_SSL_WANT_READ) { return ErrorCode::WantRead; }
  if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) { return ErrorCode::WantWrite; }
  if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
    return ErrorCode::PeerClosed;
  }
  if (ret == MBEDTLS_ERR_NET_CONN_RESET || ret == MBEDTLS_ERR_NET_SEND_FAILED ||
      ret == MBEDTLS_ERR_NET_RECV_FAILED) {
    out_errno = errno;
    return ErrorCode::SyscallError;
  }
  if (ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED) {
    return ErrorCode::CertVerifyFailed;
  }
  return ErrorCode::Fatal;
}

// A TLS 1.3 NewSessionTicket (signaled by default on Mbed TLS 4.x) is a
// non-fatal notification delivered between records, not an error and not
// application data, so I/O calls that see it should just be retried. Kept in
// one helper so the retry loops keep an intact "do { } while (...)" instead of
// splitting the closing brace across an #if.
bool mbedtls_is_session_ticket(int ret) {
#if defined(MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET)
  return ret == MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET;
#else
  (void)ret;
  return false;
#endif
}

// BIO-like send callback for Mbed TLS
int mbedtls_net_send_cb(void *ctx, const unsigned char *buf,
                               size_t len) {
  auto sock = *static_cast<socket_t *>(ctx);
#ifdef _WIN32
  auto ret =
      send(sock, reinterpret_cast<const char *>(buf), static_cast<int>(len), 0);
  if (ret == SOCKET_ERROR) {
    int err = WSAGetLastError();
    if (err == WSAEWOULDBLOCK) { return MBEDTLS_ERR_SSL_WANT_WRITE; }
    return MBEDTLS_ERR_NET_SEND_FAILED;
  }
#else
  auto ret = send(sock, buf, len, 0);
  if (ret < 0) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) {
      return MBEDTLS_ERR_SSL_WANT_WRITE;
    }
    return MBEDTLS_ERR_NET_SEND_FAILED;
  }
#endif
  return static_cast<int>(ret);
}

// BIO-like recv callback for Mbed TLS
int mbedtls_net_recv_cb(void *ctx, unsigned char *buf, size_t len) {
  auto sock = *static_cast<socket_t *>(ctx);
#ifdef _WIN32
  auto ret =
      recv(sock, reinterpret_cast<char *>(buf), static_cast<int>(len), 0);
  if (ret == SOCKET_ERROR) {
    int err = WSAGetLastError();
    if (err == WSAEWOULDBLOCK) { return MBEDTLS_ERR_SSL_WANT_READ; }
    return MBEDTLS_ERR_NET_RECV_FAILED;
  }
#else
  auto ret = recv(sock, buf, len, 0);
  if (ret < 0) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) {
      return MBEDTLS_ERR_SSL_WANT_READ;
    }
    return MBEDTLS_ERR_NET_RECV_FAILED;
  }
#endif
  if (ret == 0) { return MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY; }
  return static_cast<int>(ret);
}

// MbedTlsContext constructor/destructor implementations
MbedTlsContext::MbedTlsContext() {
  mbedtls_ssl_config_init(&conf);
#ifndef CPPHTTPLIB_MBEDTLS_V4
  mbedtls_entropy_init(&entropy);
  mbedtls_ctr_drbg_init(&ctr_drbg);
#endif
  mbedtls_x509_crt_init(&ca_chain);
  mbedtls_x509_crt_init(&own_cert);
  mbedtls_pk_init(&own_key);
}

MbedTlsContext::~MbedTlsContext() {
  mbedtls_pk_free(&own_key);
  mbedtls_x509_crt_free(&own_cert);
  mbedtls_x509_crt_free(&ca_chain);
#ifndef CPPHTTPLIB_MBEDTLS_V4
  mbedtls_ctr_drbg_free(&ctr_drbg);
  mbedtls_entropy_free(&entropy);
#endif
  mbedtls_ssl_config_free(&conf);
}

// Thread-local storage for SNI captured during handshake
// This is needed because the SNI callback doesn't have a way to pass
// session-specific data before the session is fully set up
std::string &mbedpending_sni() {
  static thread_local std::string sni;
  return sni;
}

// SNI callback for Mbed TLS server to capture client's SNI hostname
int mbedtls_sni_callback(void *p_ctx, mbedtls_ssl_context *ssl,
                                const unsigned char *name, size_t name_len) {
  (void)p_ctx;
  (void)ssl;

  // Store SNI name in thread-local storage
  // It will be retrieved and stored in the session after handshake
  if (name && name_len > 0) {
    mbedpending_sni().assign(reinterpret_cast<const char *>(name), name_len);
  } else {
    mbedpending_sni().clear();
  }
  return 0; // Accept any SNI
}

int mbedtls_verify_callback(void *data, mbedtls_x509_crt *crt,
                                   int cert_depth, uint32_t *flags);

// MbedTLS verify callback wrapper
int mbedtls_verify_callback(void *data, mbedtls_x509_crt *crt,
                                   int cert_depth, uint32_t *flags) {
  auto &callback = get_verify_callback();
  if (!callback) { return 0; } // Continue with default verification

  // data points to the MbedTlsSession
  auto *session = static_cast<MbedTlsSession *>(data);

  // Build context
  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(session);
  verify_ctx.cert = static_cast<cert_t>(crt);
  verify_ctx.depth = cert_depth;
  verify_ctx.preverify_ok = (*flags == 0);
  verify_ctx.error_code = static_cast<long>(*flags);

  // Convert Mbed TLS flags to error string
  static thread_local char error_buf[256];
  if (*flags != 0) {
    mbedtls_x509_crt_verify_info(error_buf, sizeof(error_buf), "", *flags);
    verify_ctx.error_string = error_buf;
  } else {
    verify_ctx.error_string = nullptr;
  }

  bool accepted = callback(verify_ctx);

  if (accepted) {
    *flags = 0; // Clear all error flags
    return 0;
  }
  return MBEDTLS_ERR_X509_CERT_VERIFY_FAILED;
}

} // namespace impl

ctx_t create_client_context() {
  auto ctx = new (std::nothrow) impl::MbedTlsContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = false;

#ifdef CPPHTTPLIB_MBEDTLS_V4
  // Mbed TLS 4.x draws randomness from PSA Crypto; just ensure it is ready.
  if (!detail::ensure_mbedtls_psa_crypto()) {
    delete ctx;
    return nullptr;
  }
  int ret;
#else
  // Seed the random number generator
  const char *pers = "httplib_client";
  int ret = mbedtls_ctr_drbg_seed(
      &ctx->ctr_drbg, mbedtls_entropy_func, &ctx->entropy,
      reinterpret_cast<const unsigned char *>(pers), strlen(pers));
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }
#endif

  // Set up SSL config for client
  ret = mbedtls_ssl_config_defaults(&ctx->conf, MBEDTLS_SSL_IS_CLIENT,
                                    MBEDTLS_SSL_TRANSPORT_STREAM,
                                    MBEDTLS_SSL_PRESET_DEFAULT);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

#ifndef CPPHTTPLIB_MBEDTLS_V4
  // Set random number generator (Mbed TLS 4.x uses the PSA RNG implicitly)
  mbedtls_ssl_conf_rng(&ctx->conf, mbedtls_ctr_drbg_random, &ctx->ctr_drbg);
#endif

  // Default: verify peer certificate
  mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_REQUIRED);

  // Set minimum TLS version to 1.2
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_ssl_conf_min_tls_version(&ctx->conf, MBEDTLS_SSL_VERSION_TLS1_2);
#else
  mbedtls_ssl_conf_min_version(&ctx->conf, MBEDTLS_SSL_MAJOR_VERSION_3,
                               MBEDTLS_SSL_MINOR_VERSION_3);
#endif

  return static_cast<ctx_t>(ctx);
}

ctx_t create_server_context() {
  auto ctx = new (std::nothrow) impl::MbedTlsContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = true;

#ifdef CPPHTTPLIB_MBEDTLS_V4
  // Mbed TLS 4.x draws randomness from PSA Crypto; just ensure it is ready.
  if (!detail::ensure_mbedtls_psa_crypto()) {
    delete ctx;
    return nullptr;
  }
  int ret;
#else
  // Seed the random number generator
  const char *pers = "httplib_server";
  int ret = mbedtls_ctr_drbg_seed(
      &ctx->ctr_drbg, mbedtls_entropy_func, &ctx->entropy,
      reinterpret_cast<const unsigned char *>(pers), strlen(pers));
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }
#endif

  // Set up SSL config for server
  ret = mbedtls_ssl_config_defaults(&ctx->conf, MBEDTLS_SSL_IS_SERVER,
                                    MBEDTLS_SSL_TRANSPORT_STREAM,
                                    MBEDTLS_SSL_PRESET_DEFAULT);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

#ifndef CPPHTTPLIB_MBEDTLS_V4
  // Set random number generator (Mbed TLS 4.x uses the PSA RNG implicitly)
  mbedtls_ssl_conf_rng(&ctx->conf, mbedtls_ctr_drbg_random, &ctx->ctr_drbg);
#endif

  // Default: don't verify client
  mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_NONE);

  // Set minimum TLS version to 1.2
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_ssl_conf_min_tls_version(&ctx->conf, MBEDTLS_SSL_VERSION_TLS1_2);
#else
  mbedtls_ssl_conf_min_version(&ctx->conf, MBEDTLS_SSL_MAJOR_VERSION_3,
                               MBEDTLS_SSL_MINOR_VERSION_3);
#endif

  // Set SNI callback to capture client's SNI hostname
  mbedtls_ssl_conf_sni(&ctx->conf, impl::mbedtls_sni_callback, nullptr);

  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { delete static_cast<impl::MbedTlsContext *>(ctx); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

#ifdef CPPHTTPLIB_MBEDTLS_V3
  // Mbed TLS 3.x uses mbedtls_ssl_protocol_version enum
  mbedtls_ssl_protocol_version min_ver = MBEDTLS_SSL_VERSION_TLS1_2;
  if (version >= Version::TLS1_3) {
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    min_ver = MBEDTLS_SSL_VERSION_TLS1_3;
#endif
  }
  mbedtls_ssl_conf_min_tls_version(&mctx->conf, min_ver);
#else
  // Mbed TLS 2.x uses major/minor version numbers
  int major = MBEDTLS_SSL_MAJOR_VERSION_3;
  int minor = MBEDTLS_SSL_MINOR_VERSION_3; // TLS 1.2
  if (version >= Version::TLS1_3) {
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    minor = MBEDTLS_SSL_MINOR_VERSION_4; // TLS 1.3
#else
    minor = MBEDTLS_SSL_MINOR_VERSION_3; // Fall back to TLS 1.2
#endif
  }
  mbedtls_ssl_conf_min_version(&mctx->conf, major, minor);
#endif
  return true;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // mbedtls_x509_crt_parse expects null-terminated string for PEM
  // Add null terminator if not present
  std::string pem_str(pem, len);
  int ret = mbedtls_x509_crt_parse(
      &mctx->ca_chain, reinterpret_cast<const unsigned char *>(pem_str.c_str()),
      pem_str.size() + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  int ret = mbedtls_x509_crt_parse_file(&mctx->ca_chain, file_path);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  int ret = mbedtls_x509_crt_parse_path(&mctx->ca_chain, dir_path);
  if (ret < 0) { // Returns number of certs on success, negative on error
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);
  bool loaded = false;

#ifdef _WIN32
  loaded = impl::enumerate_windows_system_certs(
      [&](const unsigned char *data, size_t len) {
        return mbedtls_x509_crt_parse_der(&mctx->ca_chain, data, len) == 0;
      });
#elif defined(__APPLE__) && defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN)
  loaded = impl::enumerate_macos_keychain_certs(
      [&](const unsigned char *data, size_t len) {
        return mbedtls_x509_crt_parse_der(&mctx->ca_chain, data, len) == 0;
      });
#else
  for (auto path = impl::system_ca_paths(); *path; ++path) {
    if (mbedtls_x509_crt_parse_file(&mctx->ca_chain, *path) >= 0) {
      loaded = true;
      break;
    }
  }

  if (!loaded) {
    for (auto dir = impl::system_ca_dirs(); *dir; ++dir) {
      if (mbedtls_x509_crt_parse_path(&mctx->ca_chain, *dir) >= 0) {
        loaded = true;
        break;
      }
    }
  }
#endif

  if (loaded) {
    mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  }
  return loaded;
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Parse certificate
  std::string cert_str(cert);
  int ret = mbedtls_x509_crt_parse(
      &mctx->own_cert,
      reinterpret_cast<const unsigned char *>(cert_str.c_str()),
      cert_str.size() + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key
  std::string key_str(key);
  const unsigned char *pwd =
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr;
  size_t pwd_len = password ? strlen(password) : 0;

#if defined(CPPHTTPLIB_MBEDTLS_V3) && !defined(CPPHTTPLIB_MBEDTLS_V4)
  ret = mbedtls_pk_parse_key(
      &mctx->own_key, reinterpret_cast<const unsigned char *>(key_str.c_str()),
      key_str.size() + 1, pwd, pwd_len, mbedtls_ctr_drbg_random,
      &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_key(
      &mctx->own_key, reinterpret_cast<const unsigned char *>(key_str.c_str()),
      key_str.size() + 1, pwd, pwd_len);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Verify that the certificate and private key match.
  // Mbed TLS 4.x: mbedtls_pk_check_pair() reports a spurious mismatch for
  // PSA-backed keys, so skip it and let the handshake surface a real mismatch.
#ifndef CPPHTTPLIB_MBEDTLS_V4
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key,
                              mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }
#endif

  ret = mbedtls_ssl_conf_own_cert(&mctx->conf, &mctx->own_cert, &mctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Parse certificate file
  int ret = mbedtls_x509_crt_parse_file(&mctx->own_cert, cert_path);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key file
#if defined(CPPHTTPLIB_MBEDTLS_V3) && !defined(CPPHTTPLIB_MBEDTLS_V4)
  ret = mbedtls_pk_parse_keyfile(&mctx->own_key, key_path, password,
                                 mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_keyfile(&mctx->own_key, key_path, password);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Verify that the certificate and private key match.
  // Mbed TLS 4.x: see set_client_cert() — skip the spurious check_pair.
#ifndef CPPHTTPLIB_MBEDTLS_V4
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key,
                              mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }
#endif

  ret = mbedtls_ssl_conf_own_cert(&mctx->conf, &mctx->own_cert, &mctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) { return; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);
  mctx->verify_client = require;
  if (require) {
    mbedtls_ssl_conf_authmode(&mctx->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
  } else {
    // If a verify callback is set, use OPTIONAL mode to ensure the callback
    // is called (matching OpenSSL behavior). Otherwise use NONE.
    mbedtls_ssl_conf_authmode(&mctx->conf, mctx->has_verify_callback
                                               ? MBEDTLS_SSL_VERIFY_OPTIONAL
                                               : MBEDTLS_SSL_VERIFY_NONE);
  }
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) { return nullptr; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  auto session = new (std::nothrow) impl::MbedTlsSession();
  if (!session) { return nullptr; }

  session->sock = sock;

  int ret = mbedtls_ssl_setup(&session->ssl, &mctx->conf);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete session;
    return nullptr;
  }

  // Explicitly opt out of in-handshake hostname verification by default;
  // since Mbed TLS 3.6.4 a client handshake with certificate verification
  // fails outright when no hostname was set. set_sni() installs the real
  // hostname for DNS hosts; for IP hosts (where SNI must not be set) the
  // caller verifies the certificate identity post-handshake via
  // verify_hostname().
  mbedtls_ssl_set_hostname(&session->ssl, nullptr);

  // Set BIO callbacks
  mbedtls_ssl_set_bio(&session->ssl, &session->sock, impl::mbedtls_net_send_cb,
                      impl::mbedtls_net_recv_cb, nullptr);

  // Set per-session verify callback with session pointer if callback is
  // registered
  if (mctx->has_verify_callback) {
    mbedtls_ssl_set_verify(&session->ssl, impl::mbedtls_verify_callback,
                           session);
  }

  return static_cast<session_t>(session);
}

void free_session(session_t session) {
  if (session) { delete static_cast<impl::MbedTlsSession *>(session); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) { return false; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  int ret = mbedtls_ssl_set_hostname(&msession->ssl, hostname);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  msession->hostname = hostname;
  return true;
}

bool set_hostname(session_t session, const char *hostname) {
  // In Mbed TLS, set_hostname also sets up hostname verification
  return set_sni(session, hostname);
}

TlsError connect(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);
  int ret;
  do {
    ret = mbedtls_ssl_handshake(&msession->ssl);
  } while (impl::mbedtls_is_session_ticket(ret));

  if (ret == 0) {
    err.code = ErrorCode::Success;
  } else {
    err.code = impl::map_mbedtls_error(ret, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(-ret);
    impl::mbedtls_last_error() = ret;
  }

  return err;
}

TlsError accept(session_t session) {
  // Same as connect for Mbed TLS - handshake works for both client and server
  auto result = connect(session);

  // After successful handshake, capture SNI from thread-local storage
  if (result.code == ErrorCode::Success && session) {
    auto msession = static_cast<impl::MbedTlsSession *>(session);
    msession->sni_hostname = std::move(impl::mbedpending_sni());
    impl::mbedpending_sni().clear();
  }

  return result;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = mbedtls_ssl_handshake(&msession->ssl)) != 0) {
    // Non-fatal TLS 1.3 ticket; retry immediately.
    if (impl::mbedtls_is_session_ticket(ret)) { continue; }
    if (ret == MBEDTLS_ERR_SSL_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // TlsError or timeout
    if (err) {
      err->code = impl::map_mbedtls_error(ret, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(-ret);
    }
    impl::mbedtls_last_error() = ret;
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  // Same implementation as connect for Mbed TLS
  bool result =
      connect_nonblocking(session, sock, timeout_sec, timeout_usec, err);

  // After successful handshake, capture SNI from thread-local storage
  if (result && session) {
    auto msession = static_cast<impl::MbedTlsSession *>(session);
    msession->sni_hostname = std::move(impl::mbedpending_sni());
    impl::mbedpending_sni().clear();
  }

  return result;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);

  // Serve a byte consumed by the is_peer_closed() probe before reading more.
  if (msession->has_peeked_byte) {
    if (len == 0) { return 0; }
    auto p = static_cast<unsigned char *>(buf);
    p[0] = msession->peeked_byte;
    msession->has_peeked_byte = false;
    size_t n = 1;
    // Top up with any already-decrypted bytes without risking a block.
    if (len > 1 && mbedtls_ssl_get_bytes_avail(&msession->ssl) > 0) {
      int extra = mbedtls_ssl_read(&msession->ssl, p + 1, len - 1);
      if (extra > 0) { n += static_cast<size_t>(extra); }
    }
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(n);
  }

  int ret;
  do {
    ret = mbedtls_ssl_read(&msession->ssl, static_cast<unsigned char *>(buf),
                           len);
  } while (impl::mbedtls_is_session_ticket(ret));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  err.code = impl::map_mbedtls_error(ret, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(-ret);
  impl::mbedtls_last_error() = ret;
  // mbedTLS signals a clean close_notify via a negative error code rather
  // than 0; surface it as a clean EOF the way OpenSSL/wolfSSL do.
  if (err.code == ErrorCode::PeerClosed) { return 0; }
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);
  int ret;
  do {
    ret = mbedtls_ssl_write(&msession->ssl,
                            static_cast<const unsigned char *>(buf), len);
  } while (impl::mbedtls_is_session_ticket(ret));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  err.code = impl::map_mbedtls_error(ret, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(-ret);
  impl::mbedtls_last_error() = ret;
  return -1;
}

int pending(const_session_t session) {
  if (!session) { return 0; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  return static_cast<int>(mbedtls_ssl_get_bytes_avail(&msession->ssl)) +
         (msession->has_peeked_byte ? 1 : 0);
}

void shutdown(session_t session, bool graceful) {
  if (!session) { return; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  if (graceful) {
    // Try to send close_notify, but don't block forever
    int ret;
    int attempts = 0;
    while ((ret = mbedtls_ssl_close_notify(&msession->ssl)) != 0 &&
           attempts < 3) {
      if (ret != MBEDTLS_ERR_SSL_WANT_READ &&
          ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
        break;
      }
      attempts++;
    }
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session || sock == INVALID_SOCKET) { return true; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  // Check if there's already decrypted or pushed-back data available.
  // If so, the connection is definitely alive.
  if (msession->has_peeked_byte ||
      mbedtls_ssl_get_bytes_avail(&msession->ssl) > 0) {
    return false;
  }

  // Set socket to non-blocking to avoid blocking on read
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  // Probe with a 1-byte read (Mbed TLS has no peek API). If the probe lands
  // on application data — e.g. a response that already arrived — push the
  // byte back so the next read() delivers it instead of losing it.
  unsigned char buf;
  int ret;
  do {
    ret = mbedtls_ssl_read(&msession->ssl, &buf, 1);
  } while (impl::mbedtls_is_session_ticket(ret));

  // If we got data or WANT_READ (would block), connection is alive
  if (ret > 0) {
    msession->peeked_byte = buf;
    msession->has_peeked_byte = true;
    return false;
  }
  if (ret == MBEDTLS_ERR_SSL_WANT_READ) { return false; }

  // If we get a peer close notify or a connection reset, the peer is closed
  return ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY ||
         ret == MBEDTLS_ERR_NET_CONN_RESET || ret == 0;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) { return nullptr; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));

  // Mbed TLS returns a pointer to the internal peer cert chain.
  // WARNING: This pointer is only valid while the session is active.
  // Do not use the certificate after calling free_session().
  const mbedtls_x509_crt *cert = mbedtls_ssl_get_peer_cert(&msession->ssl);
  return const_cast<mbedtls_x509_crt *>(cert);
}

void free_cert(cert_t cert) {
  // Mbed TLS: peer certificate is owned by the SSL context.
  // No-op here, but callers should still call this for cross-backend
  // portability.
  (void)cert;
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) { return false; }
  auto mcert = static_cast<const mbedtls_x509_crt *>(cert);
  std::string host_str(hostname);

  // Check if hostname is an IP address (IPv4 or IPv6)
  unsigned char ip_bytes[16];
  auto ip_len = impl::parse_ip_address(host_str, ip_bytes);
  auto is_ip = ip_len > 0;

  // Check Subject Alternative Names (SAN)
  // In Mbed TLS 3.x, subject_alt_names contains raw values without ASN.1 tags
  // - DNS names: raw string bytes
  // - IP addresses: raw IP bytes (4 for IPv4, 16 for IPv6)
  const mbedtls_x509_sequence *san = &mcert->subject_alt_names;
  while (san != nullptr && san->buf.p != nullptr && san->buf.len > 0) {
    const unsigned char *p = san->buf.p;
    size_t len = san->buf.len;

    if (is_ip) {
      // For an IP host, only a matching iPAddress SAN of the same family
      // (4 bytes for IPv4, 16 bytes for IPv6) may authenticate it.
      if (len == ip_len && memcmp(p, ip_bytes, ip_len) == 0) { return true; }
    } else {
      // Check if this SAN is a DNS name (printable ASCII string)
      bool is_dns = len > 0;
      for (size_t i = 0; i < len && is_dns; i++) {
        if (p[i] < 32 || p[i] > 126) { is_dns = false; }
      }
      if (is_dns) {
        std::string san_name(reinterpret_cast<const char *>(p), len);
        if (detail::match_hostname(san_name, host_str)) { return true; }
      }
    }
    san = san->next;
  }

  // Fallback: Check Common Name (CN) in subject. Skipped for IP-literal hosts:
  // an IP identity is only valid via an iPAddress SAN, never the CN (RFC 9110;
  // the OpenSSL backend's X509_check_ip behaves the same way).
  if (!is_ip) {
    char cn[256];
    int ret = mbedtls_x509_dn_gets(cn, sizeof(cn), &mcert->subject);
    if (ret > 0) {
      std::string cn_str(cn);

      // Look for "CN=" in the DN string
      size_t cn_pos = cn_str.find("CN=");
      if (cn_pos != std::string::npos) {
        size_t start = cn_pos + 3;
        size_t end = cn_str.find(',', start);
        std::string cn_value =
            cn_str.substr(start, end == std::string::npos ? end : end - start);

        if (detail::match_hostname(cn_value, host_str)) { return true; }
      }
    }
  }

  return false;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(MBEDTLS_X509_BADCERT_CN_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) { return -1; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  uint32_t flags = mbedtls_ssl_get_verify_result(&msession->ssl);
  // Return 0 (X509_V_OK equivalent) if verification passed
  return flags == 0 ? 0 : static_cast<long>(flags);
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Find the CN in the subject
  const mbedtls_x509_name *name = &x509->subject;
  while (name != nullptr) {
    if (MBEDTLS_OID_CMP(MBEDTLS_OID_AT_CN, &name->oid) == 0) {
      return std::string(reinterpret_cast<const char *>(name->val.p),
                         name->val.len);
    }
    name = name->next;
  }
  return "";
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Build a human-readable issuer name string
  char buf[512];
  int ret = mbedtls_x509_dn_gets(buf, sizeof(buf), &x509->issuer);
  if (ret < 0) return "";
  return std::string(buf);
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Parse the Subject Alternative Name extension
  const mbedtls_x509_sequence *cur = &x509->subject_alt_names;
  while (cur != nullptr) {
    if (cur->buf.len > 0) {
      // Mbed TLS stores SAN as ASN.1 sequences
      // The tag byte indicates the type
      const unsigned char *p = cur->buf.p;
      size_t len = cur->buf.len;

      // First byte is the tag
      unsigned char tag = *p;
      p++;
      len--;

      // Parse length (simple single-byte length assumed)
      if (len > 0 && *p < 0x80) {
        size_t value_len = *p;
        p++;
        len--;

        if (value_len <= len) {
          SanEntry entry;
          // ASN.1 context tags for GeneralName
          switch (tag & 0x1F) {
          case 2: // dNSName
            entry.type = SanType::DNS;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          case 7: // iPAddress
            entry.type = SanType::IP;
            if (value_len == 4) {
              // IPv4
              char buf[16];
              snprintf(buf, sizeof(buf), "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
              entry.value = buf;
            } else if (value_len == 16) {
              // IPv6
              char buf[64];
              snprintf(buf, sizeof(buf),
                       "%02x%02x:%02x%02x:%02x%02x:%02x%02x:"
                       "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                       p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], p[8],
                       p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
              entry.value = buf;
            }
            break;
          case 1: // rfc822Name (email)
            entry.type = SanType::EMAIL;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          case 6: // uniformResourceIdentifier
            entry.type = SanType::URI;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          default: entry.type = SanType::OTHER; break;
          }

          if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
        }
      }
    }
    cur = cur->next;
  }
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Convert mbedtls_x509_time to time_t
  auto to_time_t = [](const mbedtls_x509_time &t) -> time_t {
    struct tm tm_time = {};
    tm_time.tm_year = t.year - 1900;
    tm_time.tm_mon = t.mon - 1;
    tm_time.tm_mday = t.day;
    tm_time.tm_hour = t.hour;
    tm_time.tm_min = t.min;
    tm_time.tm_sec = t.sec;
#ifdef _WIN32
    return _mkgmtime(&tm_time);
#else
    return timegm(&tm_time);
#endif
  };

  not_before = to_time_t(x509->valid_from);
  not_after = to_time_t(x509->valid_to);
  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Convert serial number to hex string
  std::string result;
  result.reserve(x509->serial.len * 2);
  for (size_t i = 0; i < x509->serial.len; i++) {
    char hex[3];
    snprintf(hex, sizeof(hex), "%02X", x509->serial.p[i]);
    result += hex;
  }
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto crt = static_cast<mbedtls_x509_crt *>(cert);
  if (!crt->raw.p || crt->raw.len == 0) return false;
  der.assign(crt->raw.p, crt->raw.p + crt->raw.len);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto msession = static_cast<const impl::MbedTlsSession *>(session);

  // For server: return SNI received from client during handshake
  if (!msession->sni_hostname.empty()) {
    return msession->sni_hostname.c_str();
  }

  // For client: return the hostname set via set_sni
  if (!msession->hostname.empty()) { return msession->hostname.c_str(); }

  return nullptr;
}

uint64_t peek_error() {
  // Mbed TLS doesn't have an error queue, return the last error
  return static_cast<uint64_t>(-impl::mbedtls_last_error());
}

uint64_t get_error() {
  // Mbed TLS doesn't have an error queue, return and clear the last error
  uint64_t err = static_cast<uint64_t>(-impl::mbedtls_last_error());
  impl::mbedtls_last_error() = 0;
  return err;
}

std::string error_string(uint64_t code) {
  char buf[256];
  mbedtls_strerror(-static_cast<int>(code), buf, sizeof(buf));
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  auto *ca_chain = new (std::nothrow) mbedtls_x509_crt;
  if (!ca_chain) { return nullptr; }

  mbedtls_x509_crt_init(ca_chain);

  // mbedtls_x509_crt_parse expects null-terminated PEM
  int ret = mbedtls_x509_crt_parse(ca_chain,
                                   reinterpret_cast<const unsigned char *>(pem),
                                   len + 1); // +1 for null terminator
  if (ret != 0) {
    // Try without +1 in case PEM is already null-terminated
    ret = mbedtls_x509_crt_parse(
        ca_chain, reinterpret_cast<const unsigned char *>(pem), len);
    if (ret != 0) {
      mbedtls_x509_crt_free(ca_chain);
      delete ca_chain;
      return nullptr;
    }
  }

  return static_cast<ca_store_t>(ca_chain);
}

void free_ca_store(ca_store_t store) {
  if (store) {
    auto *ca_chain = static_cast<mbedtls_x509_crt *>(store);
    mbedtls_x509_crt_free(ca_chain);
    delete ca_chain;
  }
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);
  auto *ca_chain = static_cast<mbedtls_x509_crt *>(store);

  // Free existing CA chain
  mbedtls_x509_crt_free(&mbed_ctx->ca_chain);
  mbedtls_x509_crt_init(&mbed_ctx->ca_chain);

  // Copy the CA chain (deep copy)
  // Parse from the raw data of the source cert
  mbedtls_x509_crt *src = ca_chain;
  while (src != nullptr) {
    int ret = mbedtls_x509_crt_parse_der(&mbed_ctx->ca_chain, src->raw.p,
                                         src->raw.len);
    if (ret != 0) {
      free_ca_store(store);
      return false;
    }
    src = src->next;
  }

  // This function takes ownership of the store; the chain was deep-copied
  // above, so release the source
  free_ca_store(store);

  // Update the SSL config to use the new CA chain
  mbedtls_ssl_conf_ca_chain(&mbed_ctx->conf, &mbed_ctx->ca_chain, nullptr);
  return true;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Iterate through the CA chain
  mbedtls_x509_crt *cert = &mbed_ctx->ca_chain;
  while (cert != nullptr && cert->raw.len > 0) {
    // Create a copy of the certificate for the caller
    auto *copy = new mbedtls_x509_crt;
    mbedtls_x509_crt_init(copy);
    int ret = mbedtls_x509_crt_parse_der(copy, cert->raw.p, cert->raw.len);
    if (ret == 0) {
      certs.push_back(static_cast<cert_t>(copy));
    } else {
      mbedtls_x509_crt_free(copy);
      delete copy;
    }
    cert = cert->next;
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Iterate through the CA chain
  mbedtls_x509_crt *cert = &mbed_ctx->ca_chain;
  while (cert != nullptr && cert->raw.len > 0) {
    char buf[512];
    int ret = mbedtls_x509_dn_gets(buf, sizeof(buf), &cert->subject);
    if (ret > 0) { names.push_back(buf); }
    cert = cert->next;
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Free existing certificate and key
  mbedtls_x509_crt_free(&mbed_ctx->own_cert);
  mbedtls_pk_free(&mbed_ctx->own_key);
  mbedtls_x509_crt_init(&mbed_ctx->own_cert);
  mbedtls_pk_init(&mbed_ctx->own_key);

  // Parse certificate PEM
  int ret = mbedtls_x509_crt_parse(
      &mbed_ctx->own_cert, reinterpret_cast<const unsigned char *>(cert_pem),
      strlen(cert_pem) + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key PEM
#if defined(CPPHTTPLIB_MBEDTLS_V3) && !defined(CPPHTTPLIB_MBEDTLS_V4)
  ret = mbedtls_pk_parse_key(
      &mbed_ctx->own_key, reinterpret_cast<const unsigned char *>(key_pem),
      strlen(key_pem) + 1,
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr,
      password ? strlen(password) : 0, mbedtls_ctr_drbg_random,
      &mbed_ctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_key(
      &mbed_ctx->own_key, reinterpret_cast<const unsigned char *>(key_pem),
      strlen(key_pem) + 1,
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr,
      password ? strlen(password) : 0);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Configure SSL to use the new certificate and key
  ret = mbedtls_ssl_conf_own_cert(&mbed_ctx->conf, &mbed_ctx->own_cert,
                                  &mbed_ctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Free existing CA chain
  mbedtls_x509_crt_free(&mbed_ctx->ca_chain);
  mbedtls_x509_crt_init(&mbed_ctx->ca_chain);

  // Parse CA PEM
  int ret = mbedtls_x509_crt_parse(
      &mbed_ctx->ca_chain, reinterpret_cast<const unsigned char *>(ca_pem),
      strlen(ca_pem) + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Update SSL config to use new CA chain
  mbedtls_ssl_conf_ca_chain(&mbed_ctx->conf, &mbed_ctx->ca_chain, nullptr);
  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  impl::get_verify_callback() = std::move(callback);
  mbed_ctx->has_verify_callback =
      static_cast<bool>(impl::get_verify_callback());

  if (mbed_ctx->has_verify_callback) {
    // Set OPTIONAL mode to ensure callback is called even when verification
    // is disabled (matching OpenSSL behavior where SSL_VERIFY_PEER is set)
    mbedtls_ssl_conf_authmode(&mbed_ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
    mbedtls_ssl_conf_verify(&mbed_ctx->conf, impl::mbedtls_verify_callback,
                            nullptr);
  } else {
    mbedtls_ssl_conf_verify(&mbed_ctx->conf, nullptr, nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto *msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  return static_cast<long>(mbedtls_ssl_get_verify_result(&msession->ssl));
}

std::string verify_error_string(long error_code) {
  if (error_code == 0) { return ""; }
  char buf[256];
  mbedtls_x509_crt_verify_info(buf, sizeof(buf), "",
                               static_cast<uint32_t>(error_code));
  // Remove trailing newline if present
  std::string result(buf);
  while (!result.empty() && (result.back() == '\n' || result.back() == ' ')) {
    result.pop_back();
  }
  return result;
}

} // namespace tls

#endif // CPPHTTPLIB_MBEDTLS_SUPPORT

/*
 * Group 10: TLS abstraction layer - wolfSSL backend
 */

/*
 * wolfSSL Backend Implementation
 */

#ifdef CPPHTTPLIB_WOLFSSL_SUPPORT
namespace tls {

namespace impl {

// wolfSSL session wrapper
struct WolfSSLSession {
  WOLFSSL *ssl = nullptr;
  socket_t sock = INVALID_SOCKET;
  std::string hostname;     // For client: set via set_sni
  std::string sni_hostname; // For server: received from client via SNI callback

  WolfSSLSession() = default;

  ~WolfSSLSession() {
    if (ssl) { wolfSSL_free(ssl); }
  }

  WolfSSLSession(const WolfSSLSession &) = delete;
  WolfSSLSession &operator=(const WolfSSLSession &) = delete;
};

// Thread-local error code accessor for wolfSSL
uint64_t &wolfssl_last_error() {
  static thread_local uint64_t err = 0;
  return err;
}

// Helper to map wolfSSL error to ErrorCode.
// ssl_error is the value from wolfSSL_get_error().
// raw_ret is the raw return value from the wolfSSL call (for low-level error).
ErrorCode map_wolfssl_error(WOLFSSL *ssl, int ssl_error,
                                   int &out_errno) {
  switch (ssl_error) {
  case SSL_ERROR_NONE: return ErrorCode::Success;
  case SSL_ERROR_WANT_READ: return ErrorCode::WantRead;
  case SSL_ERROR_WANT_WRITE: return ErrorCode::WantWrite;
  case SSL_ERROR_ZERO_RETURN: return ErrorCode::PeerClosed;
  case SSL_ERROR_SYSCALL: out_errno = errno; return ErrorCode::SyscallError;
  default:
    if (ssl) {
      // wolfSSL stores the low-level error code as a negative value.
      // DOMAIN_NAME_MISMATCH (-322) indicates hostname verification failure.
      int low_err = ssl_error; // wolfSSL_get_error returns the low-level code
      if (low_err == DOMAIN_NAME_MISMATCH) {
        return ErrorCode::HostnameMismatch;
      }
      // Check verify result to distinguish cert verification from generic SSL
      // errors.
      long vr = wolfSSL_get_verify_result(ssl);
      if (vr != 0) { return ErrorCode::CertVerifyFailed; }
    }
    return ErrorCode::Fatal;
  }
}

// WolfSSLContext constructor/destructor implementations
WolfSSLContext::WolfSSLContext() { wolfSSL_Init(); }

WolfSSLContext::~WolfSSLContext() {
  if (ctx) { wolfSSL_CTX_free(ctx); }
}

// Thread-local storage for SNI captured during handshake
std::string &wolfssl_pending_sni() {
  static thread_local std::string sni;
  return sni;
}

// SNI callback for wolfSSL server to capture client's SNI hostname
int wolfssl_sni_callback(WOLFSSL *ssl, int *ret, void *exArg) {
  (void)ret;
  (void)exArg;

  void *name_data = nullptr;
  unsigned short name_len =
      wolfSSL_SNI_GetRequest(ssl, WOLFSSL_SNI_HOST_NAME, &name_data);

  if (name_data && name_len > 0) {
    wolfssl_pending_sni().assign(static_cast<const char *>(name_data),
                                 name_len);
  } else {
    wolfssl_pending_sni().clear();
  }
  return 0; // Continue regardless
}

// wolfSSL verify callback wrapper
int wolfssl_verify_callback(int preverify_ok,
                                   WOLFSSL_X509_STORE_CTX *x509_ctx) {
  auto &callback = get_verify_callback();
  if (!callback) { return preverify_ok; }

  WOLFSSL_X509 *cert = wolfSSL_X509_STORE_CTX_get_current_cert(x509_ctx);
  int depth = wolfSSL_X509_STORE_CTX_get_error_depth(x509_ctx);
  int err = wolfSSL_X509_STORE_CTX_get_error(x509_ctx);

  // Get the WOLFSSL object from the X509_STORE_CTX
  WOLFSSL *ssl = static_cast<WOLFSSL *>(wolfSSL_X509_STORE_CTX_get_ex_data(
      x509_ctx, wolfSSL_get_ex_data_X509_STORE_CTX_idx()));

  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(ssl);
  verify_ctx.cert = static_cast<cert_t>(cert);
  verify_ctx.depth = depth;
  verify_ctx.preverify_ok = (preverify_ok != 0);
  verify_ctx.error_code = static_cast<long>(err);

  if (err != 0) {
    verify_ctx.error_string = wolfSSL_X509_verify_cert_error_string(err);
  } else {
    verify_ctx.error_string = nullptr;
  }

  bool accepted = callback(verify_ctx);
  return accepted ? 1 : 0;
}

void set_wolfssl_password_cb(WOLFSSL_CTX *ctx, const char *password) {
  wolfSSL_CTX_set_default_passwd_cb_userdata(ctx, const_cast<char *>(password));
  wolfSSL_CTX_set_default_passwd_cb(
      ctx, [](char *buf, int size, int /*rwflag*/, void *userdata) -> int {
        auto *pwd = static_cast<const char *>(userdata);
        if (!pwd) return 0;
        auto len = static_cast<int>(strlen(pwd));
        if (len > size) len = size;
        memcpy(buf, pwd, static_cast<size_t>(len));
        return len;
      });
}

} // namespace impl

ctx_t create_client_context() {
  auto ctx = new (std::nothrow) impl::WolfSSLContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = false;

  WOLFSSL_METHOD *method = wolfTLSv1_2_client_method();
  if (!method) {
    delete ctx;
    return nullptr;
  }

  ctx->ctx = wolfSSL_CTX_new(method);
  if (!ctx->ctx) {
    delete ctx;
    return nullptr;
  }

  // Default: verify peer certificate
  wolfSSL_CTX_set_verify(ctx->ctx, SSL_VERIFY_PEER, nullptr);

  return static_cast<ctx_t>(ctx);
}

ctx_t create_server_context() {
  auto ctx = new (std::nothrow) impl::WolfSSLContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = true;

  WOLFSSL_METHOD *method = wolfTLSv1_2_server_method();
  if (!method) {
    delete ctx;
    return nullptr;
  }

  ctx->ctx = wolfSSL_CTX_new(method);
  if (!ctx->ctx) {
    delete ctx;
    return nullptr;
  }

  // Default: don't verify client
  wolfSSL_CTX_set_verify(ctx->ctx, SSL_VERIFY_NONE, nullptr);

  // Enable SNI on server
  wolfSSL_CTX_SNI_SetOptions(ctx->ctx, WOLFSSL_SNI_HOST_NAME,
                             WOLFSSL_SNI_CONTINUE_ON_MISMATCH);
  wolfSSL_CTX_set_servername_callback(ctx->ctx, impl::wolfssl_sni_callback);

  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { delete static_cast<impl::WolfSSLContext *>(ctx); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int min_ver = WOLFSSL_TLSV1_2;
  if (version >= Version::TLS1_3) { min_ver = WOLFSSL_TLSV1_3; }

  return wolfSSL_CTX_SetMinVersion(wctx->ctx, min_ver) == WOLFSSL_SUCCESS;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(pem),
      static_cast<long>(len), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  wctx->ca_pem_data_.append(pem, len);
  return true;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_locations(wctx->ctx, file_path, nullptr);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  return true;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_locations(wctx->ctx, nullptr, dir_path);
  // wolfSSL may fail if the directory doesn't contain properly hashed certs.
  // Unlike OpenSSL which lazily loads certs from directories, wolfSSL scans
  // immediately. Return true even on failure since the CA file may have
  // already been loaded, matching OpenSSL's lenient behavior.
  (void)ret;
  return true;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);
  bool loaded = false;

#ifdef _WIN32
  loaded = impl::enumerate_windows_system_certs(
      [&](const unsigned char *data, size_t len) {
        return wolfSSL_CTX_load_verify_buffer(wctx->ctx, data,
                                              static_cast<long>(len),
                                              SSL_FILETYPE_ASN1) == SSL_SUCCESS;
      });
#elif defined(__APPLE__) && defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN)
  loaded = impl::enumerate_macos_keychain_certs(
      [&](const unsigned char *data, size_t len) {
        return wolfSSL_CTX_load_verify_buffer(wctx->ctx, data,
                                              static_cast<long>(len),
                                              SSL_FILETYPE_ASN1) == SSL_SUCCESS;
      });
#else
  for (auto path = impl::system_ca_paths(); *path; ++path) {
    if (wolfSSL_CTX_load_verify_locations(wctx->ctx, *path, nullptr) ==
        SSL_SUCCESS) {
      loaded = true;
      break;
    }
  }

  if (!loaded) {
    for (auto dir = impl::system_ca_dirs(); *dir; ++dir) {
      if (wolfSSL_CTX_load_verify_locations(wctx->ctx, nullptr, *dir) ==
          SSL_SUCCESS) {
        loaded = true;
        break;
      }
    }
  }
#endif

  return loaded;
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load certificate
  int ret = wolfSSL_CTX_use_certificate_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(cert),
      static_cast<long>(strlen(cert)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password callback if password is provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load private key
  ret = wolfSSL_CTX_use_PrivateKey_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(key),
      static_cast<long>(strlen(key)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Verify that the certificate and private key match
  return wolfSSL_CTX_check_private_key(wctx->ctx) == SSL_SUCCESS;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load certificate file
  int ret =
      wolfSSL_CTX_use_certificate_file(wctx->ctx, cert_path, SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password callback if password is provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load private key file
  ret = wolfSSL_CTX_use_PrivateKey_file(wctx->ctx, key_path, SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Verify that the certificate and private key match
  return wolfSSL_CTX_check_private_key(wctx->ctx) == SSL_SUCCESS;
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) { return; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);
  wctx->verify_client = require;
  if (require) {
    wolfSSL_CTX_set_verify(
        wctx->ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
        wctx->has_verify_callback ? impl::wolfssl_verify_callback : nullptr);
  } else {
    if (wctx->has_verify_callback) {
      wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_PEER,
                             impl::wolfssl_verify_callback);
    } else {
      wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_NONE, nullptr);
    }
  }
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) { return nullptr; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  auto session = new (std::nothrow) impl::WolfSSLSession();
  if (!session) { return nullptr; }

  session->sock = sock;
  session->ssl = wolfSSL_new(wctx->ctx);
  if (!session->ssl) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    delete session;
    return nullptr;
  }

  wolfSSL_set_fd(session->ssl, static_cast<int>(sock));

  return static_cast<session_t>(session);
}

void free_session(session_t session) {
  if (session) { delete static_cast<impl::WolfSSLSession *>(session); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) { return false; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  int ret = wolfSSL_UseSNI(wsession->ssl, WOLFSSL_SNI_HOST_NAME, hostname,
                           static_cast<word16>(strlen(hostname)));
  if (ret != WOLFSSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Also set hostname for verification
  wolfSSL_check_domain_name(wsession->ssl, hostname);

  wsession->hostname = hostname;
  return true;
}

bool set_hostname(session_t session, const char *hostname) {
  // In wolfSSL, set_hostname also sets up hostname verification
  return set_sni(session, hostname);
}

TlsError connect(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_connect(wsession->ssl);

  if (ret == SSL_SUCCESS) {
    err.code = ErrorCode::Success;
  } else {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(ssl_error);
    impl::wolfssl_last_error() = err.backend_code;
  }

  return err;
}

TlsError accept(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_accept(wsession->ssl);

  if (ret == SSL_SUCCESS) {
    err.code = ErrorCode::Success;
    // Capture SNI from thread-local storage after successful handshake
    wsession->sni_hostname = std::move(impl::wolfssl_pending_sni());
    impl::wolfssl_pending_sni().clear();
  } else {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(ssl_error);
    impl::wolfssl_last_error() = err.backend_code;
  }

  return err;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = wolfSSL_connect(wsession->ssl)) != SSL_SUCCESS) {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    if (ssl_error == SSL_ERROR_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ssl_error == SSL_ERROR_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // Error or timeout
    if (err) {
      err->code =
          impl::map_wolfssl_error(wsession->ssl, ssl_error, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(ssl_error);
    }
    impl::wolfssl_last_error() = static_cast<uint64_t>(ssl_error);
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = wolfSSL_accept(wsession->ssl)) != SSL_SUCCESS) {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    if (ssl_error == SSL_ERROR_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ssl_error == SSL_ERROR_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // Error or timeout
    if (err) {
      err->code =
          impl::map_wolfssl_error(wsession->ssl, ssl_error, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(ssl_error);
    }
    impl::wolfssl_last_error() = static_cast<uint64_t>(ssl_error);
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }

  // Capture SNI from thread-local storage after successful handshake
  wsession->sni_hostname = std::move(impl::wolfssl_pending_sni());
  impl::wolfssl_pending_sni().clear();

  return true;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_read(wsession->ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(ssl_error);
  impl::wolfssl_last_error() = err.backend_code;
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_write(wsession->ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  // wolfSSL_write returns 0 when the peer has sent a close_notify.
  // Treat this as an error (return -1) so callers don't spin in a
  // write loop adding zero to the offset.
  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return -1;
  }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(ssl_error);
  impl::wolfssl_last_error() = err.backend_code;
  return -1;
}

int pending(const_session_t session) {
  if (!session) { return 0; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  return wolfSSL_pending(wsession->ssl);
}

void shutdown(session_t session, bool graceful) {
  if (!session) { return; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  if (graceful) {
    int ret;
    int attempts = 0;
    while ((ret = wolfSSL_shutdown(wsession->ssl)) != SSL_SUCCESS &&
           attempts < 3) {
      int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
      if (ssl_error != SSL_ERROR_WANT_READ &&
          ssl_error != SSL_ERROR_WANT_WRITE) {
        break;
      }
      attempts++;
    }
  } else {
    wolfSSL_shutdown(wsession->ssl);
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session || sock == INVALID_SOCKET) { return true; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Check if there's already decrypted data available
  if (wolfSSL_pending(wsession->ssl) > 0) { return false; }

  // Set socket to non-blocking to avoid blocking on read
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  // Peek 1 byte to check connection status without consuming data
  unsigned char buf;
  int ret = wolfSSL_peek(wsession->ssl, &buf, 1);

  // If we got data or WANT_READ (would block), connection is alive
  if (ret > 0) { return false; }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  if (ssl_error == SSL_ERROR_WANT_READ) { return false; }

  return ssl_error == SSL_ERROR_ZERO_RETURN || ssl_error == SSL_ERROR_SYSCALL ||
         ret == 0;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) { return nullptr; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));

  WOLFSSL_X509 *cert = wolfSSL_get_peer_certificate(wsession->ssl);
  return static_cast<cert_t>(cert);
}

void free_cert(cert_t cert) {
  if (cert) { wolfSSL_X509_free(static_cast<WOLFSSL_X509 *>(cert)); }
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) { return false; }
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);
  std::string host_str(hostname);

  // Check if hostname is an IP address (IPv4 or IPv6)
  unsigned char ip_bytes[16];
  auto ip_len = impl::parse_ip_address(host_str, ip_bytes);
  auto is_ip = ip_len > 0;

  // Check Subject Alternative Names
  auto *san_names = static_cast<WOLF_STACK_OF(WOLFSSL_GENERAL_NAME) *>(
      wolfSSL_X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));

  if (san_names) {
    int san_count = wolfSSL_sk_num(san_names);
    for (int i = 0; i < san_count; i++) {
      auto *names =
          static_cast<WOLFSSL_GENERAL_NAME *>(wolfSSL_sk_value(san_names, i));
      if (!names) continue;

      if (!is_ip && names->type == WOLFSSL_GEN_DNS) {
        // DNS name
        unsigned char *dns_name = nullptr;
        int dns_len = wolfSSL_ASN1_STRING_to_UTF8(&dns_name, names->d.dNSName);
        if (dns_name && dns_len > 0) {
          std::string san_name(reinterpret_cast<char *>(dns_name),
                               static_cast<size_t>(dns_len));
          XFREE(dns_name, nullptr, DYNAMIC_TYPE_OPENSSL);
          if (detail::match_hostname(san_name, host_str)) {
            wolfSSL_sk_free(san_names);
            return true;
          }
        }
      } else if (is_ip && names->type == WOLFSSL_GEN_IPADD) {
        // IP address: only an iPAddress SAN of the same family (4 bytes for
        // IPv4, 16 bytes for IPv6) may authenticate the host.
        unsigned char *ip_data = wolfSSL_ASN1_STRING_data(names->d.iPAddress);
        auto san_ip_len = wolfSSL_ASN1_STRING_length(names->d.iPAddress);
        if (ip_data && san_ip_len == static_cast<int>(ip_len) &&
            memcmp(ip_data, ip_bytes, ip_len) == 0) {
          wolfSSL_sk_free(san_names);
          return true;
        }
      }
    }
    wolfSSL_sk_free(san_names);
  }

  // Fallback: Check Common Name (CN) in subject. Skipped for IP-literal hosts:
  // an IP identity is only valid via an iPAddress SAN, never the CN (RFC 9110;
  // the OpenSSL backend's X509_check_ip behaves the same way).
  auto subject = is_ip ? nullptr : wolfSSL_X509_get_subject_name(x509);
  if (subject) {
    char cn[256] = {};
    int cn_len = wolfSSL_X509_NAME_get_text_by_NID(subject, NID_commonName, cn,
                                                   sizeof(cn));
    if (cn_len > 0) {
      std::string cn_str(cn, static_cast<size_t>(cn_len));
      if (detail::match_hostname(cn_str, host_str)) { return true; }
    }
  }

  return false;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(DOMAIN_NAME_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) { return -1; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  long result = wolfSSL_get_verify_result(wsession->ssl);
  return result;
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_X509_NAME *subject = wolfSSL_X509_get_subject_name(x509);
  if (!subject) return "";

  char cn[256] = {};
  int cn_len = wolfSSL_X509_NAME_get_text_by_NID(subject, NID_commonName, cn,
                                                 sizeof(cn));
  if (cn_len <= 0) return "";
  return std::string(cn, static_cast<size_t>(cn_len));
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_X509_NAME *issuer = wolfSSL_X509_get_issuer_name(x509);
  if (!issuer) return "";

  char *name_str = wolfSSL_X509_NAME_oneline(issuer, nullptr, 0);
  if (!name_str) return "";

  std::string result(name_str);
  XFREE(name_str, nullptr, DYNAMIC_TYPE_OPENSSL);
  return result;
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  auto *san_names = static_cast<WOLF_STACK_OF(WOLFSSL_GENERAL_NAME) *>(
      wolfSSL_X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));
  if (!san_names) return true; // No SANs is not an error

  int count = wolfSSL_sk_num(san_names);
  for (int i = 0; i < count; i++) {
    auto *name =
        static_cast<WOLFSSL_GENERAL_NAME *>(wolfSSL_sk_value(san_names, i));
    if (!name) continue;

    SanEntry entry;
    switch (name->type) {
    case WOLFSSL_GEN_DNS: {
      entry.type = SanType::DNS;
      unsigned char *dns_name = nullptr;
      int dns_len = wolfSSL_ASN1_STRING_to_UTF8(&dns_name, name->d.dNSName);
      if (dns_name && dns_len > 0) {
        entry.value = std::string(reinterpret_cast<char *>(dns_name),
                                  static_cast<size_t>(dns_len));
        XFREE(dns_name, nullptr, DYNAMIC_TYPE_OPENSSL);
      }
      break;
    }
    case WOLFSSL_GEN_IPADD: {
      entry.type = SanType::IP;
      unsigned char *ip_data = wolfSSL_ASN1_STRING_data(name->d.iPAddress);
      int ip_len = wolfSSL_ASN1_STRING_length(name->d.iPAddress);
      if (ip_data && ip_len == 4) {
        char buf[16];
        snprintf(buf, sizeof(buf), "%d.%d.%d.%d", ip_data[0], ip_data[1],
                 ip_data[2], ip_data[3]);
        entry.value = buf;
      } else if (ip_data && ip_len == 16) {
        char buf[64];
        snprintf(buf, sizeof(buf),
                 "%02x%02x:%02x%02x:%02x%02x:%02x%02x:"
                 "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                 ip_data[0], ip_data[1], ip_data[2], ip_data[3], ip_data[4],
                 ip_data[5], ip_data[6], ip_data[7], ip_data[8], ip_data[9],
                 ip_data[10], ip_data[11], ip_data[12], ip_data[13],
                 ip_data[14], ip_data[15]);
        entry.value = buf;
      }
      break;
    }
    case WOLFSSL_GEN_EMAIL:
      entry.type = SanType::EMAIL;
      {
        unsigned char *email = nullptr;
        int email_len = wolfSSL_ASN1_STRING_to_UTF8(&email, name->d.rfc822Name);
        if (email && email_len > 0) {
          entry.value = std::string(reinterpret_cast<char *>(email),
                                    static_cast<size_t>(email_len));
          XFREE(email, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      break;
    case WOLFSSL_GEN_URI:
      entry.type = SanType::URI;
      {
        unsigned char *uri = nullptr;
        int uri_len = wolfSSL_ASN1_STRING_to_UTF8(
            &uri, name->d.uniformResourceIdentifier);
        if (uri && uri_len > 0) {
          entry.value = std::string(reinterpret_cast<char *>(uri),
                                    static_cast<size_t>(uri_len));
          XFREE(uri, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      break;
    default: entry.type = SanType::OTHER; break;
    }

    if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
  }
  wolfSSL_sk_free(san_names);
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  const WOLFSSL_ASN1_TIME *nb = wolfSSL_X509_get_notBefore(x509);
  const WOLFSSL_ASN1_TIME *na = wolfSSL_X509_get_notAfter(x509);

  if (!nb || !na) return false;

  // wolfSSL_ASN1_TIME_to_tm is available
  struct tm tm_nb = {}, tm_na = {};
  if (wolfSSL_ASN1_TIME_to_tm(nb, &tm_nb) != WOLFSSL_SUCCESS) return false;
  if (wolfSSL_ASN1_TIME_to_tm(na, &tm_na) != WOLFSSL_SUCCESS) return false;

#ifdef _WIN32
  not_before = _mkgmtime(&tm_nb);
  not_after = _mkgmtime(&tm_na);
#else
  not_before = timegm(&tm_nb);
  not_after = timegm(&tm_na);
#endif
  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_ASN1_INTEGER *serial_asn1 = wolfSSL_X509_get_serialNumber(x509);
  if (!serial_asn1) return "";

  // Get the serial number data
  int len = serial_asn1->length;
  unsigned char *data = serial_asn1->data;
  if (!data || len <= 0) return "";

  std::string result;
  result.reserve(static_cast<size_t>(len) * 2);
  for (int i = 0; i < len; i++) {
    char hex[3];
    snprintf(hex, sizeof(hex), "%02X", data[i]);
    result += hex;
  }
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  int der_len = 0;
  const unsigned char *der_data = wolfSSL_X509_get_der(x509, &der_len);
  if (!der_data || der_len <= 0) return false;

  der.assign(der_data, der_data + der_len);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto wsession = static_cast<const impl::WolfSSLSession *>(session);

  // For server: return SNI received from client during handshake
  if (!wsession->sni_hostname.empty()) {
    return wsession->sni_hostname.c_str();
  }

  // For client: return the hostname set via set_sni
  if (!wsession->hostname.empty()) { return wsession->hostname.c_str(); }

  return nullptr;
}

uint64_t peek_error() {
  return static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
}

uint64_t get_error() {
  uint64_t err = impl::wolfssl_last_error();
  impl::wolfssl_last_error() = 0;
  return err;
}

std::string error_string(uint64_t code) {
  char buf[256];
  wolfSSL_ERR_error_string(static_cast<unsigned long>(code), buf);
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  if (!pem || len == 0) { return nullptr; }
  // Validate by attempting to load into a temporary ctx
  WOLFSSL_CTX *tmp_ctx = wolfSSL_CTX_new(wolfTLSv1_2_client_method());
  if (!tmp_ctx) { return nullptr; }
  int ret = wolfSSL_CTX_load_verify_buffer(
      tmp_ctx, reinterpret_cast<const unsigned char *>(pem),
      static_cast<long>(len), SSL_FILETYPE_PEM);
  wolfSSL_CTX_free(tmp_ctx);
  if (ret != SSL_SUCCESS) { return nullptr; }
  return static_cast<ca_store_t>(
      new impl::WolfSSLCAStore{std::string(pem, len)});
}

void free_ca_store(ca_store_t store) {
  delete static_cast<impl::WolfSSLCAStore *>(store);
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  auto *ca = static_cast<impl::WolfSSLCAStore *>(store);
  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(ca->pem_data.data()),
      static_cast<long>(ca->pem_data.size()), SSL_FILETYPE_PEM);
  if (ret == SSL_SUCCESS) { wctx->ca_pem_data_ += ca->pem_data; }
  // This function takes ownership of the store; the PEM data was copied into
  // the context, so release the source
  free_ca_store(store);
  return ret == SSL_SUCCESS;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  if (wctx->ca_pem_data_.empty()) { return 0; }

  const std::string &pem = wctx->ca_pem_data_;
  const std::string begin_marker = "-----BEGIN CERTIFICATE-----";
  const std::string end_marker = "-----END CERTIFICATE-----";
  size_t pos = 0;
  while ((pos = pem.find(begin_marker, pos)) != std::string::npos) {
    size_t end_pos = pem.find(end_marker, pos);
    if (end_pos == std::string::npos) { break; }
    end_pos += end_marker.size();
    std::string cert_pem = pem.substr(pos, end_pos - pos);
    WOLFSSL_X509 *x509 = wolfSSL_X509_load_certificate_buffer(
        reinterpret_cast<const unsigned char *>(cert_pem.data()),
        static_cast<int>(cert_pem.size()), WOLFSSL_FILETYPE_PEM);
    if (x509) { certs.push_back(static_cast<cert_t>(x509)); }
    pos = end_pos;
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  if (wctx->ca_pem_data_.empty()) { return names; }

  const std::string &pem = wctx->ca_pem_data_;
  const std::string begin_marker = "-----BEGIN CERTIFICATE-----";
  const std::string end_marker = "-----END CERTIFICATE-----";
  size_t pos = 0;
  while ((pos = pem.find(begin_marker, pos)) != std::string::npos) {
    size_t end_pos = pem.find(end_marker, pos);
    if (end_pos == std::string::npos) { break; }
    end_pos += end_marker.size();
    std::string cert_pem = pem.substr(pos, end_pos - pos);
    WOLFSSL_X509 *x509 = wolfSSL_X509_load_certificate_buffer(
        reinterpret_cast<const unsigned char *>(cert_pem.data()),
        static_cast<int>(cert_pem.size()), WOLFSSL_FILETYPE_PEM);
    if (x509) {
      WOLFSSL_X509_NAME *subject = wolfSSL_X509_get_subject_name(x509);
      if (subject) {
        char *name_str = wolfSSL_X509_NAME_oneline(subject, nullptr, 0);
        if (name_str) {
          names.push_back(name_str);
          XFREE(name_str, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      wolfSSL_X509_free(x509);
    }
    pos = end_pos;
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load new certificate
  int ret = wolfSSL_CTX_use_certificate_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(cert_pem),
      static_cast<long>(strlen(cert_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password if provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load new private key
  ret = wolfSSL_CTX_use_PrivateKey_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(key_pem),
      static_cast<long>(strlen(key_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  return true;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(ca_pem),
      static_cast<long>(strlen(ca_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  impl::get_verify_callback() = std::move(callback);
  wctx->has_verify_callback = static_cast<bool>(impl::get_verify_callback());

  if (wctx->has_verify_callback) {
    wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_PEER,
                           impl::wolfssl_verify_callback);
  } else {
    wolfSSL_CTX_set_verify(
        wctx->ctx,
        wctx->verify_client
            ? (SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT)
            : SSL_VERIFY_NONE,
        nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto *wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  return wolfSSL_get_verify_result(wsession->ssl);
}

std::string verify_error_string(long error_code) {
  if (error_code == 0) { return ""; }
  const char *str =
      wolfSSL_X509_verify_cert_error_string(static_cast<int>(error_code));
  return str ? std::string(str) : std::string();
}

} // namespace tls

#endif // CPPHTTPLIB_WOLFSSL_SUPPORT

// WebSocket implementation
namespace ws {

bool WebSocket::send_frame(Opcode op, const char *data, size_t len,
                                  bool fin) {
  std::lock_guard<std::mutex> lock(write_mutex_);
  if (closed_) { return false; }
  return detail::write_websocket_frame(strm_, op, data, len, fin, !is_server_);
}

ReadResult WebSocket::read(std::string &msg) {
  while (!closed_) {
    Opcode opcode;
    std::string payload;
    bool fin;

    if (!impl::read_websocket_frame(strm_, opcode, payload, fin, is_server_,
                                    CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH)) {
      closed_ = true;
      return Fail;
    }

    switch (opcode) {
    case Opcode::Ping: {
      std::lock_guard<std::mutex> lock(write_mutex_);
      detail::write_websocket_frame(strm_, Opcode::Pong, payload.data(),
                                    payload.size(), true, !is_server_);
      continue;
    }
    case Opcode::Pong: {
      std::lock_guard<std::mutex> lock(ping_mutex_);
      unacked_pings_ = 0;
      continue;
    }
    case Opcode::Close: {
      if (!closed_.exchange(true)) {
        // Echo close frame back
        std::lock_guard<std::mutex> lock(write_mutex_);
        detail::write_websocket_frame(strm_, Opcode::Close, payload.data(),
                                      payload.size(), true, !is_server_);
      }
      return Fail;
    }
    case Opcode::Text:
    case Opcode::Binary: {
      auto result = opcode == Opcode::Text ? Text : Binary;
      msg = std::move(payload);

      // Handle fragmentation
      if (!fin) {
        while (true) {
          Opcode cont_opcode;
          std::string cont_payload;
          bool cont_fin;
          if (!impl::read_websocket_frame(
                  strm_, cont_opcode, cont_payload, cont_fin, is_server_,
                  CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH)) {
            closed_ = true;
            return Fail;
          }
          if (cont_opcode == Opcode::Ping) {
            std::lock_guard<std::mutex> lock(write_mutex_);
            detail::write_websocket_frame(
                strm_, Opcode::Pong, cont_payload.data(), cont_payload.size(),
                true, !is_server_);
            continue;
          }
          if (cont_opcode == Opcode::Pong) {
            std::lock_guard<std::mutex> lock(ping_mutex_);
            unacked_pings_ = 0;
            continue;
          }
          if (cont_opcode == Opcode::Close) {
            if (!closed_.exchange(true)) {
              std::lock_guard<std::mutex> lock(write_mutex_);
              detail::write_websocket_frame(
                  strm_, Opcode::Close, cont_payload.data(),
                  cont_payload.size(), true, !is_server_);
            }
            return Fail;
          }
          // RFC 6455: continuation frames must use opcode 0x0
          if (cont_opcode != Opcode::Continuation) {
            closed_ = true;
            return Fail;
          }
          msg += cont_payload;
          if (msg.size() > CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH) {
            closed_ = true;
            return Fail;
          }
          if (cont_fin) { break; }
        }
      }
      // RFC 6455 Section 5.6: text frames must contain valid UTF-8
      if (result == Text && !impl::is_valid_utf8(msg)) {
        close(CloseStatus::InvalidPayload, "invalid UTF-8");
        return Fail;
      }
      return result;
    }
    default: closed_ = true; return Fail;
    }
  }
  return Fail;
}

bool WebSocket::send(const std::string &data) {
  return send_frame(Opcode::Text, data.data(), data.size());
}

bool WebSocket::send(const char *data, size_t len) {
  return send_frame(Opcode::Binary, data, len);
}

void WebSocket::close(CloseStatus status, const std::string &reason) {
  if (closed_.exchange(true)) { return; }
  ping_cv_.notify_all();
  std::string payload;
  auto code = static_cast<uint16_t>(status);
  payload.push_back(static_cast<char>((code >> 8) & 0xFF));
  payload.push_back(static_cast<char>(code & 0xFF));
  // RFC 6455 Section 5.5: control frame payload must not exceed 125 bytes
  // Close frame has 2-byte status code, so reason is limited to 123 bytes
  payload += reason.substr(0, 123);
  {
    std::lock_guard<std::mutex> lock(write_mutex_);
    detail::write_websocket_frame(strm_, Opcode::Close, payload.data(),
                                  payload.size(), true, !is_server_);
  }

  // RFC 6455 Section 7.1.1: after sending a Close frame, wait for the peer's
  // Close response before closing the TCP connection. Use a short timeout to
  // avoid hanging if the peer doesn't respond.
  strm_.set_read_timeout(CPPHTTPLIB_WEBSOCKET_CLOSE_TIMEOUT_SECOND, 0);
  Opcode op;
  std::string resp;
  bool fin;
  while (impl::read_websocket_frame(strm_, op, resp, fin, is_server_, 125)) {
    if (op == Opcode::Close) { break; }
  }
}

WebSocket::~WebSocket() {
  {
    std::lock_guard<std::mutex> lock(ping_mutex_);
    closed_ = true;
  }
  ping_cv_.notify_all();
  if (ping_thread_.joinable()) { ping_thread_.join(); }
}

void WebSocket::start_heartbeat() {
  if (ping_interval_sec_ == 0) { return; }
  ping_thread_ = std::thread([this]() {
    std::unique_lock<std::mutex> lock(ping_mutex_);
    while (!closed_) {
      ping_cv_.wait_for(lock, std::chrono::seconds(ping_interval_sec_));
      if (closed_) { break; }
      // If the peer has failed to respond to the previous pings, give up.
      // RFC 6455 does not define a pong-timeout mechanism; this is an
      // opt-in liveness check controlled by max_missed_pongs_.
      if (max_missed_pongs_ > 0 && unacked_pings_ >= max_missed_pongs_) {
        lock.unlock();
        close(CloseStatus::GoingAway, "pong timeout");
        return;
      }
      lock.unlock();
      if (!send_frame(Opcode::Ping, nullptr, 0)) {
        lock.lock();
        closed_ = true;
        break;
      }
      lock.lock();
      unacked_pings_++;
    }
  });
}

const Request &WebSocket::request() const { return req_; }

bool WebSocket::is_open() const { return !closed_; }

// WebSocketClient implementation
WebSocketClient::WebSocketClient(
    const std::string &scheme_host_port_path, const Headers &headers)
    : headers_(headers) {
  detail::UrlComponents uc;
  if (detail::parse_url(scheme_host_port_path, uc) && !uc.scheme.empty() &&
      !uc.host.empty() && !uc.path.empty()) {
    auto &scheme = uc.scheme;

#ifdef CPPHTTPLIB_SSL_ENABLED
    if (scheme != "ws" && scheme != "wss") {
#else
    if (scheme != "ws") {
#endif
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
      std::string msg = "'" + scheme + "' scheme is not supported.";
      throw std::invalid_argument(msg);
#endif
      return;
    }

    auto is_ssl = scheme == "wss";

    host_ = std::move(uc.host);

    port_ = is_ssl ? 443 : 80;
    if (!uc.port.empty() && !detail::parse_port(uc.port, port_)) { return; }

    path_ = std::move(uc.path);
    if (!uc.query.empty()) { path_ += uc.query; }

#ifdef CPPHTTPLIB_SSL_ENABLED
    is_ssl_ = is_ssl;
    if (is_ssl_) {
      // The context lives as long as the client so that CA configuration
      // survives reconnects; sessions are created per connection.
      tls_ctx_ = tls::create_client_context();
      if (!tls_ctx_) { return; }
    }
#else
    if (is_ssl) { return; }
#endif

    is_valid_ = true;
  }
}

WebSocketClient::~WebSocketClient() {
  shutdown_and_close();
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (tls_ctx_) {
    tls::free_context(tls_ctx_);
    tls_ctx_ = nullptr;
  }
#endif
}

bool WebSocketClient::is_valid() const { return is_valid_; }

void WebSocketClient::shutdown_and_close() {
  // Send the close frame while the TLS session is still alive: ws_ holds an
  // SSLSocketStream that keeps a raw pointer to tls_session_, so the session
  // must outlive ws_->close() and ws_.reset() to avoid a use-after-free.
  if (ws_ && ws_->is_open()) { ws_->close(); }
  ws_.reset();
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl_) {
    if (tls_session_) {
      tls::shutdown(tls_session_, true);
      tls::free_session(tls_session_);
      tls_session_ = nullptr;
    }
  }
#endif
  if (sock_ != INVALID_SOCKET) {
    detail::shutdown_socket(sock_);
    detail::close_socket(sock_);
    sock_ = INVALID_SOCKET;
  }
}

bool WebSocketClient::create_stream(std::unique_ptr<Stream> &strm) {
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl_) {
    if (server_certificate_verification_ && !certs_loaded_) {
      uint64_t backend_error = 0;
      detail::load_client_ca_config(tls_ctx_, ca_cert_file_path_, std::string(),
                                    custom_ca_loaded_, system_ca_mode_,
                                    backend_error);
      certs_loaded_ = true;
    }

    if (!detail::setup_client_tls_session(host_, tls_ctx_, tls_session_, sock_,
                                          server_certificate_verification_,
                                          read_timeout_sec_,
                                          read_timeout_usec_)) {
      return false;
    }

    strm = std::unique_ptr<Stream>(new detail::SSLSocketStream(
        sock_, tls_session_, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_));
    return true;
  }
#endif
  strm = std::unique_ptr<Stream>(
      new detail::SocketStream(sock_, read_timeout_sec_, read_timeout_usec_,
                               write_timeout_sec_, write_timeout_usec_));
  return true;
}

bool WebSocketClient::connect() {
  if (!is_valid_) { return false; }
  shutdown_and_close();

  // Check is custom IP specified for host_
  std::string ip;
  auto it = addr_map_.find(host_);
  if (it != addr_map_.end()) { ip = it->second; }

  Error error;
  sock_ = detail::create_client_socket(
      host_, ip, port_, address_family_, tcp_nodelay_, ipv6_v6only_,
      socket_options_, connection_timeout_sec_, connection_timeout_usec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, interface_, error);

  if (sock_ == INVALID_SOCKET) { return false; }

  std::unique_ptr<Stream> strm;
  if (!create_stream(strm)) {
    shutdown_and_close();
    return false;
  }

#ifdef CPPHTTPLIB_SSL_ENABLED
  auto is_ssl = is_ssl_;
#else
  auto is_ssl = false;
#endif

  std::string selected_subprotocol;
  if (!detail::perform_websocket_handshake(*strm, host_, port_, is_ssl, path_,
                                           headers_, selected_subprotocol)) {
    shutdown_and_close();
    return false;
  }
  subprotocol_ = std::move(selected_subprotocol);

  Request req;
  req.method = "GET";
  req.path = path_;
  ws_ = std::unique_ptr<WebSocket>(new WebSocket(std::move(strm), req, false,
                                                 websocket_ping_interval_sec_,
                                                 websocket_max_missed_pongs_));
  return true;
}

ReadResult WebSocketClient::read(std::string &msg) {
  if (!ws_) { return Fail; }
  return ws_->read(msg);
}

bool WebSocketClient::send(const std::string &data) {
  if (!ws_) { return false; }
  return ws_->send(data);
}

bool WebSocketClient::send(const char *data, size_t len) {
  if (!ws_) { return false; }
  return ws_->send(data, len);
}

void WebSocketClient::close(CloseStatus status,
                                   const std::string &reason) {
  if (ws_) { ws_->close(status, reason); }
}

bool WebSocketClient::is_open() const { return ws_ && ws_->is_open(); }

const std::string &WebSocketClient::subprotocol() const {
  return subprotocol_;
}

void WebSocketClient::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

void WebSocketClient::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
}

void WebSocketClient::set_websocket_ping_interval(time_t sec) {
  websocket_ping_interval_sec_ = sec;
}

void WebSocketClient::set_websocket_max_missed_pongs(int count) {
  websocket_max_missed_pongs_ = count;
}

void WebSocketClient::set_tcp_nodelay(bool on) { tcp_nodelay_ = on; }

void WebSocketClient::set_address_family(int family) {
  address_family_ = family;
}

void WebSocketClient::set_ipv6_v6only(bool on) { ipv6_v6only_ = on; }

void WebSocketClient::set_socket_options(SocketOptions socket_options) {
  socket_options_ = std::move(socket_options);
}

void WebSocketClient::set_connection_timeout(time_t sec, time_t usec) {
  connection_timeout_sec_ = sec;
  connection_timeout_usec_ = usec;
}

void WebSocketClient::set_interface(const std::string &intf) {
  interface_ = intf;
}

void WebSocketClient::set_hostname_addr_map(
    std::map<std::string, std::string> addr_map) {
  addr_map_ = std::move(addr_map);
}

#ifdef CPPHTTPLIB_SSL_ENABLED

void WebSocketClient::set_ca_cert_path(const std::string &path) {
  ca_cert_file_path_ = path;
}

void WebSocketClient::set_ca_cert_store(tls::ca_store_t store) {
  if (store && tls_ctx_) {
    // set_ca_store takes ownership of store
    tls::set_ca_store(tls_ctx_, store);
    custom_ca_loaded_ = true;
  } else if (store) {
    tls::free_ca_store(store);
  }
}

void WebSocketClient::load_ca_cert_store(const char *ca_cert,
                                                std::size_t size) {
  if (tls_ctx_ && ca_cert && size > 0) {
    tls::load_ca_pem(tls_ctx_, ca_cert, size);
    custom_ca_loaded_ = true;
  }
}

void
WebSocketClient::enable_server_certificate_verification(bool enabled) {
  server_certificate_verification_ = enabled;
}

void WebSocketClient::enable_system_ca(bool enabled) {
  system_ca_mode_ = enabled ? SystemCAMode::Enabled : SystemCAMode::Disabled;
}

#endif // CPPHTTPLIB_SSL_ENABLED

} // namespace ws

} // namespace httplib
