add full WebSocket (RFC 6455) client/server support for zenhttp (#792)

* This branch adds full WebSocket (RFC 6455) support to the HTTP server layer, covering both transport backends, a client, and tests.

- **`websocket.h`** -- Core interfaces: `WebSocketOpcode`, `WebSocketMessage`, `WebSocketConnection` (ref-counted), and `IWebSocketHandler`. Services opt in to WebSocket support by implementing `IWebSocketHandler` alongside their existing `HttpService`.
- **`httpwsclient.h`** -- `HttpWsClient`: an ASIO-backed `ws://` client with both standalone (own thread) and shared `io_context` modes. Supports connect timeout and optional auth token injection via `IWsClientHandler` callbacks.

- **`wsasio.cpp/h`** -- `WsAsioConnection`: WebSocket over ASIO TCP. Takes over the socket after the HTTP 101 handshake and runs an async read/write loop with a queued write path (guarded by `RwLock`).
- **`wshttpsys.cpp/h`** -- `WsHttpSysConnection`: WebSocket over http.sys opaque-mode connections (Windows only). Uses `HttpReceiveRequestEntityBody` / `HttpSendResponseEntityBody` via IOCP, sharing the same threadpool as normal http.sys traffic. Self-ref lifetime management ensures graceful drain of outstanding async ops.
- **`httpsys_iocontext.h`** -- Tagged `OVERLAPPED` wrapper (`HttpSysIoContext`) used to distinguish normal HTTP transactions from WebSocket read/write completions in the single IOCP callback.

- **`wsframecodec.cpp/h`** -- `WsFrameCodec`: static helpers for parsing (unmasked and masked) and building (unmasked server frames and masked client frames) RFC 6455 frames across all three payload length encodings (7-bit, 16-bit, 64-bit). Also computes `Sec-WebSocket-Accept` keys.

- **`clients/httpwsclient.cpp`** -- `HttpWsClient::Impl`: ASIO-based client that performs the HTTP upgrade handshake, then hands off to the frame codec for the read loop. Manages its own `io_context` thread or plugs into an external one.

- **`httpasio.cpp`** -- ASIO server now detects `Upgrade: websocket` requests, checks the matching `HttpService` for `IWebSocketHandler` via `dynamic_cast`, performs the RFC 6455 handshake (101 response), and spins up a `WsAsioConnection`.
- **`httpsys.cpp`** -- Same upgrade detection and handshake logic for the http.sys backend, using `WsHttpSysConnection` and `HTTP_SEND_RESPONSE_FLAG_OPAQUE`.
- **`httpparser.cpp/h`** -- Extended to surface the `Upgrade` / `Connection` / `Sec-WebSocket-Key` headers needed by the handshake.
- **`httpcommon.h`** -- Minor additions (probably new header constants or response codes for the WS upgrade).
- **`httpserver.h`** -- Small interface changes to support WebSocket registration.
- **`zenhttp.cpp` / `xmake.lua`** -- New source files wired in; build config updated.

- **Unit tests** (`websocket.framecodec`): round-trip encode/decode for text, binary, close frames; all three payload sizes; masked and unmasked variants; RFC 6455 `Sec-WebSocket-Accept` test vector.
- **Integration tests** (`websocket.integration`): full ASIO server tests covering handshake (101), normal HTTP coexistence, echo, server-push broadcast, client close handshake, ping/pong auto-response, sequential messages, and rejection of upgrades on non-WS services.
- **Client tests** (`websocket.client`): `HttpWsClient` connect+echo+close, connection failure (bad port -> close code 1006), and server-initiated close.

* changed HttpRequestParser::ParseCurrentHeader to use switch instead of if/else chain

* remove spurious printf

---------

Co-authored-by: Stefan Boberg <[email protected]>

1 files changed, 104 insertions, 0 deletions

diff --git a/src/zenhttp/servers/wshttpsys.h b/src/zenhttp/servers/wshttpsys.h
new file mode 100644
index 000000000..ab0ca381a
--- /dev/null
+++ b/src/zenhttp/servers/wshttpsys.h
@@ -0,0 +1,104 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include <zenhttp/websocket.h>
+
+#include "httpsys_iocontext.h"
+
+#include <zencore/thread.h>
+
+#if ZEN_WITH_HTTPSYS
+#	define _WINSOCKAPI_
+#	include <zencore/windows.h>
+#	include <http.h>
+
+#	include <atomic>
+#	include <deque>
+#	include <vector>
+
+namespace zen {
+
+/**
+ * WebSocket connection over an http.sys opaque-mode connection
+ *
+ * After the 101 Switching Protocols response is sent with
+ * HTTP_SEND_RESPONSE_FLAG_OPAQUE, http.sys stops parsing HTTP on the
+ * connection.  Raw bytes are exchanged via HttpReceiveRequestEntityBody /
+ * HttpSendResponseEntityBody using the original RequestId.
+ *
+ * All I/O is performed asynchronously via the same IOCP threadpool used
+ * for normal http.sys traffic, eliminating per-connection threads.
+ *
+ * Lifetime is managed through intrusive reference counting (RefCounted).
+ * A self-reference (m_SelfRef) is held from Start() until all outstanding
+ * async operations have drained, preventing premature destruction.
+ */
+class WsHttpSysConnection : public WebSocketConnection
+{
+public:
+	WsHttpSysConnection(HANDLE RequestQueueHandle, HTTP_REQUEST_ID RequestId, IWebSocketHandler& Handler, PTP_IO Iocp);
+	~WsHttpSysConnection() override;
+
+	/**
+	 * Start the async read loop.  Must be called once after construction
+	 * and after the 101 response has been sent.
+	 */
+	void Start();
+
+	/**
+	 * Shut down the connection.  Cancels pending I/O; IOCP completions
+	 * will fire with ERROR_OPERATION_ABORTED and drain naturally.
+	 */
+	void Shutdown();
+
+	// WebSocketConnection interface
+	void SendText(std::string_view Text) override;
+	void SendBinary(std::span<const uint8_t> Data) override;
+	void Close(uint16_t Code, std::string_view Reason) override;
+	bool IsOpen() const override;
+
+	// Called from IoCompletionCallback via tagged dispatch
+	void OnReadCompletion(ULONG IoResult, ULONG_PTR NumberOfBytesTransferred);
+	void OnWriteCompletion(ULONG IoResult, ULONG_PTR NumberOfBytesTransferred);
+
+private:
+	void IssueAsyncRead();
+	void ProcessReceivedData();
+	void EnqueueWrite(std::vector<uint8_t> Frame);
+	void FlushWriteQueue();
+	void DoClose(uint16_t Code, std::string_view Reason);
+	void Disconnect();
+	void MaybeReleaseSelfRef();
+
+	HANDLE			   m_RequestQueueHandle;
+	HTTP_REQUEST_ID	   m_RequestId;
+	IWebSocketHandler& m_Handler;
+	PTP_IO			   m_Iocp;
+
+	// Tagged OVERLAPPED contexts for concurrent read and write
+	HttpSysIoContext m_ReadIoContext{};
+	HttpSysIoContext m_WriteIoContext{};
+
+	// Read state
+	std::vector<uint8_t> m_ReadBuffer;
+	std::vector<uint8_t> m_Accumulated;
+
+	// Write state
+	RwLock							 m_WriteLock;
+	std::deque<std::vector<uint8_t>> m_WriteQueue;
+	std::vector<uint8_t>			 m_CurrentWriteBuffer;
+	HTTP_DATA_CHUNK					 m_WriteChunk{};
+	bool							 m_IsWriting = false;
+
+	// Lifetime management
+	std::atomic<int32_t>	 m_OutstandingOps{0};
+	Ref<WsHttpSysConnection> m_SelfRef;
+	std::atomic<bool>		 m_ShutdownRequested{false};
+	std::atomic<bool>		 m_IsOpen{true};
+	bool					 m_CloseSent = false;
+};
+
+}  // namespace zen
+
+#endif	// ZEN_WITH_HTTPSYS