Support RFC 8441 upgrades over HTTP/2 CONNECT

See gh-34362

Signed-off-by: Jared Wiltshire <jazdw@users.noreply.github.com>

Author: jazdw

spring-webflux/src/main/java/org/springframework/web/reactive/socket/server/support/HandshakeWebSocketService.java

@@ -205,23 +205,25 @@ public Mono<Void> handleRequest(ServerWebExchange exchange, WebSocketHandler han
 		HttpMethod method = request.getMethod();
 		HttpHeaders headers = request.getHeaders();
 
-		if (HttpMethod.GET != method && CONNECT_METHOD != method) {
+		if (HttpMethod.GET != method && !CONNECT_METHOD.equals(method)) {
 			return Mono.error(new MethodNotAllowedException(
 					request.getMethod(), Set.of(HttpMethod.GET, CONNECT_METHOD)));
 		}
 
-		if (!"WebSocket".equalsIgnoreCase(headers.getUpgrade())) {
-			return handleBadRequest(exchange, "Invalid 'Upgrade' header: " + headers);
-		}
+		if (HttpMethod.GET == method) {
+			if (!"WebSocket".equalsIgnoreCase(headers.getUpgrade())) {
+				return handleBadRequest(exchange, "Invalid 'Upgrade' header: " + headers);
+			}
 
-		List<String> connectionValue = headers.getConnection();
-		if (!connectionValue.contains("Upgrade") && !connectionValue.contains("upgrade")) {
-			return handleBadRequest(exchange, "Invalid 'Connection' header: " + headers);
-		}
+			List<String> connectionValue = headers.getConnection();
+			if (!connectionValue.contains("Upgrade") && !connectionValue.contains("upgrade")) {
+				return handleBadRequest(exchange, "Invalid 'Connection' header: " + headers);
+			}
 
-		String key = headers.getFirst(SEC_WEBSOCKET_KEY);
-		if (key == null) {
-			return handleBadRequest(exchange, "Missing \"Sec-WebSocket-Key\" header");
+			String key = headers.getFirst(SEC_WEBSOCKET_KEY);
+			if (key == null) {
+				return handleBadRequest(exchange, "Missing \"Sec-WebSocket-Key\" header");
+			}
 		}
 
 		String protocol = selectProtocol(headers, handler);

spring-websocket/src/main/java/org/springframework/web/socket/WebSocketHttpHeaders.java

@@ -151,7 +151,7 @@ public void setSecWebSocketProtocol(List<String> secWebSocketProtocols) {
 	}
 
 	/**
-	 * Returns the value of the {@code Sec-WebSocket-Key} header.
+	 * Returns the value of the {@code Sec-WebSocket-Protocol} header.
 	 * @return the value of the header
 	 */
 	public List<String> getSecWebSocketProtocol() {

spring-websocket/src/main/java/org/springframework/web/socket/server/support/AbstractHandshakeHandler.java

@@ -215,21 +215,23 @@ public final boolean doHandshake(ServerHttpRequest request, ServerHttpResponse r
 		}
 		try {
 			HttpMethod httpMethod = request.getMethod();
-			if (HttpMethod.GET != httpMethod && CONNECT_METHOD != httpMethod) {
+			if (HttpMethod.GET != httpMethod && !CONNECT_METHOD.equals(httpMethod)) {
 				response.setStatusCode(HttpStatus.METHOD_NOT_ALLOWED);
 				response.getHeaders().setAllow(Set.of(HttpMethod.GET, CONNECT_METHOD));
 				if (logger.isErrorEnabled()) {
 					logger.error("Handshake failed due to unexpected HTTP method: " + httpMethod);
 				}
 				return false;
 			}
-			if (!"WebSocket".equalsIgnoreCase(headers.getUpgrade())) {
-				handleInvalidUpgradeHeader(request, response);
-				return false;
-			}
-			if (!headers.getConnection().contains("Upgrade") && !headers.getConnection().contains("upgrade")) {
-				handleInvalidConnectHeader(request, response);
-				return false;
+			if (HttpMethod.GET == httpMethod) {
+				if (!"WebSocket".equalsIgnoreCase(headers.getUpgrade())) {
+					handleInvalidUpgradeHeader(request, response);
+					return false;
+				}
+				if (!headers.getConnection().contains("Upgrade") && !headers.getConnection().contains("upgrade")) {
+					handleInvalidConnectHeader(request, response);
+					return false;
+				}
 			}
 			if (!isWebSocketVersionSupported(headers)) {
 				handleWebSocketVersionNotSupported(request, response);
@@ -239,13 +241,15 @@ public final boolean doHandshake(ServerHttpRequest request, ServerHttpResponse r
 				response.setStatusCode(HttpStatus.FORBIDDEN);
 				return false;
 			}
-			String wsKey = headers.getSecWebSocketKey();
-			if (wsKey == null) {
-				if (logger.isErrorEnabled()) {
-					logger.error("Missing \"Sec-WebSocket-Key\" header");
+			if (HttpMethod.GET == httpMethod) {
+				String wsKey = headers.getSecWebSocketKey();
+				if (wsKey == null) {
+					if (logger.isErrorEnabled()) {
+						logger.error("Missing \"Sec-WebSocket-Key\" header");
+					}
+					response.setStatusCode(HttpStatus.BAD_REQUEST);
+					return false;
 				}
-				response.setStatusCode(HttpStatus.BAD_REQUEST);
-				return false;
 			}
 		}
 		catch (IOException ex) {