Omit default port from WebSocket handshake Host header (Fix #2480)

The WebSocket upgrade request always appended ":port" to the Host
header, violating RFC 6455 Section 4.1 which says the port should be
included only when it is not the default (80 for ws, 443 for wss).
Some CDNs alter routing when the Host header carries an explicit
default port.

Build the Host header with detail::make_host_and_port_string, which
also brackets IPv6 literal hosts correctly.

Author: yhirose

httplib.h

@@ -8905,7 +8905,8 @@ inline bool is_field_value(const std::string &s) { return is_field_content(s); }
 } // namespace fields
 
 inline bool perform_websocket_handshake(Stream &strm, const std::string &host,
-                                        int port, const std::string &path,
+                                        int port, bool is_ssl,
+                                        const std::string &path,
                                         const Headers &headers,
                                         std::string &selected_subprotocol) {
   // Validate path and host
@@ -8931,7 +8932,7 @@ inline bool perform_websocket_handshake(Stream &strm, const std::string &host,
 
   // Build upgrade request
   std::string req_str = "GET " + path + " HTTP/1.1\r\n";
-  req_str += "Host: " + host + ":" + std::to_string(port) + "\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";
@@ -20570,9 +20571,15 @@ inline bool WebSocketClient::connect() {
     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_, path_, headers_,
-                                           selected_subprotocol)) {
+  if (!detail::perform_websocket_handshake(*strm, host_, port_, is_ssl, path_,
+                                           headers_, selected_subprotocol)) {
     shutdown_and_close();
     return false;
   }

test/test.cc

@@ -18975,6 +18975,47 @@ TEST(WebSocketTest, QueryStringInHandshake) {
   t.join();
 }
 
+TEST(WebSocketTest, HostHeaderInHandshake) {
+  Server svr;
+
+  std::mutex mtx;
+  std::string received_host;
+
+  svr.WebSocket("/ws", [&](const Request &req, ws::WebSocket &ws) {
+    {
+      std::lock_guard<std::mutex> lock(mtx);
+      received_host = req.get_header_value("Host");
+    }
+    std::string msg;
+    while (ws.read(msg)) {
+      ws.send(msg);
+    }
+  });
+
+  auto port = svr.bind_to_any_port("localhost");
+  std::thread t([&]() { svr.listen_after_bind(); });
+  svr.wait_until_ready();
+
+  ws::WebSocketClient client("ws://localhost:" + std::to_string(port) + "/ws");
+  ASSERT_TRUE(client.connect());
+  // Round-trip ensures the handler has run and captured the request.
+  ASSERT_TRUE(client.send("hello"));
+  std::string msg;
+  ASSERT_TRUE(client.read(msg));
+  client.close();
+
+  {
+    std::lock_guard<std::mutex> lock(mtx);
+    // Non-default port must be present in the Host header. Default ports
+    // (80/443) are omitted; that logic is covered by
+    // MakeHostAndPortStringTest.
+    EXPECT_EQ("localhost:" + std::to_string(port), received_host);
+  }
+
+  svr.stop();
+  t.join();
+}
+
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
 class WebSocketSSLIntegrationTest : public ::testing::Test {
 protected: