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, 94 insertions, 54 deletions

diff --git a/src/zenhttp/servers/httpparser.cpp b/src/zenhttp/servers/httpparser.cpp
index f0485aa25..3b1229375 100644
--- a/src/zenhttp/servers/httpparser.cpp
+++ b/src/zenhttp/servers/httpparser.cpp
@@ -12,14 +12,17 @@ namespace zen {
 
 using namespace std::literals;
 
-static constinit uint32_t HashContentLength = HashStringAsLowerDjb2("Content-Length"sv);
-static constinit uint32_t HashContentType	= HashStringAsLowerDjb2("Content-Type"sv);
-static constinit uint32_t HashAccept		= HashStringAsLowerDjb2("Accept"sv);
-static constinit uint32_t HashExpect		= HashStringAsLowerDjb2("Expect"sv);
-static constinit uint32_t HashSession		= HashStringAsLowerDjb2("UE-Session"sv);
-static constinit uint32_t HashRequest		= HashStringAsLowerDjb2("UE-Request"sv);
-static constinit uint32_t HashRange			= HashStringAsLowerDjb2("Range"sv);
-static constinit uint32_t HashAuthorization = HashStringAsLowerDjb2("Authorization"sv);
+static constexpr uint32_t HashContentLength		  = HashStringAsLowerDjb2("Content-Length"sv);
+static constexpr uint32_t HashContentType		  = HashStringAsLowerDjb2("Content-Type"sv);
+static constexpr uint32_t HashAccept			  = HashStringAsLowerDjb2("Accept"sv);
+static constexpr uint32_t HashExpect			  = HashStringAsLowerDjb2("Expect"sv);
+static constexpr uint32_t HashSession			  = HashStringAsLowerDjb2("UE-Session"sv);
+static constexpr uint32_t HashRequest			  = HashStringAsLowerDjb2("UE-Request"sv);
+static constexpr uint32_t HashRange				  = HashStringAsLowerDjb2("Range"sv);
+static constexpr uint32_t HashAuthorization		  = HashStringAsLowerDjb2("Authorization"sv);
+static constexpr uint32_t HashUpgrade			  = HashStringAsLowerDjb2("Upgrade"sv);
+static constexpr uint32_t HashSecWebSocketKey	  = HashStringAsLowerDjb2("Sec-WebSocket-Key"sv);
+static constexpr uint32_t HashSecWebSocketVersion = HashStringAsLowerDjb2("Sec-WebSocket-Version"sv);
 
 //////////////////////////////////////////////////////////////////////////
 //
@@ -143,45 +146,62 @@ HttpRequestParser::ParseCurrentHeader()
 	const uint32_t HeaderHash		  = HashStringAsLowerDjb2(HeaderName);
 	const int8_t   CurrentHeaderIndex = int8_t(CurrentHeaderCount - 1);
 
-	if (HeaderHash == HashContentLength)
+	switch (HeaderHash)
 	{
-		m_ContentLengthHeaderIndex = CurrentHeaderIndex;
-	}
-	else if (HeaderHash == HashAccept)
-	{
-		m_AcceptHeaderIndex = CurrentHeaderIndex;
-	}
-	else if (HeaderHash == HashContentType)
-	{
-		m_ContentTypeHeaderIndex = CurrentHeaderIndex;
-	}
-	else if (HeaderHash == HashAuthorization)
-	{
-		m_AuthorizationHeaderIndex = CurrentHeaderIndex;
-	}
-	else if (HeaderHash == HashSession)
-	{
-		m_SessionId = Oid::TryFromHexString(HeaderValue);
-	}
-	else if (HeaderHash == HashRequest)
-	{
-		std::from_chars(HeaderValue.data(), HeaderValue.data() + HeaderValue.size(), m_RequestId);
-	}
-	else if (HeaderHash == HashExpect)
-	{
-		if (HeaderValue == "100-continue"sv)
-		{
-			// We don't currently do anything with this
-			m_Expect100Continue = true;
-		}
-		else
-		{
-			ZEN_INFO("Unexpected expect - Expect: {}", HeaderValue);
-		}
-	}
-	else if (HeaderHash == HashRange)
-	{
-		m_RangeHeaderIndex = CurrentHeaderIndex;
+		case HashContentLength:
+			m_ContentLengthHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashAccept:
+			m_AcceptHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashContentType:
+			m_ContentTypeHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashAuthorization:
+			m_AuthorizationHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashSession:
+			m_SessionId = Oid::TryFromHexString(HeaderValue);
+			break;
+
+		case HashRequest:
+			std::from_chars(HeaderValue.data(), HeaderValue.data() + HeaderValue.size(), m_RequestId);
+			break;
+
+		case HashExpect:
+			if (HeaderValue == "100-continue"sv)
+			{
+				// We don't currently do anything with this
+				m_Expect100Continue = true;
+			}
+			else
+			{
+				ZEN_INFO("Unexpected expect - Expect: {}", HeaderValue);
+			}
+			break;
+
+		case HashRange:
+			m_RangeHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashUpgrade:
+			m_UpgradeHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashSecWebSocketKey:
+			m_SecWebSocketKeyHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		case HashSecWebSocketVersion:
+			m_SecWebSocketVersionHeaderIndex = CurrentHeaderIndex;
+			break;
+
+		default:
+			break;
 	}
 }
 
@@ -361,14 +381,17 @@ HttpRequestParser::ResetState()
 
 	m_HeaderEntries.clear();
 
-	m_ContentLengthHeaderIndex = -1;
-	m_AcceptHeaderIndex		   = -1;
-	m_ContentTypeHeaderIndex   = -1;
-	m_RangeHeaderIndex		   = -1;
-	m_AuthorizationHeaderIndex = -1;
-	m_Expect100Continue		   = false;
-	m_BodyBuffer			   = {};
-	m_BodyPosition			   = 0;
+	m_ContentLengthHeaderIndex		 = -1;
+	m_AcceptHeaderIndex				 = -1;
+	m_ContentTypeHeaderIndex		 = -1;
+	m_RangeHeaderIndex				 = -1;
+	m_AuthorizationHeaderIndex		 = -1;
+	m_UpgradeHeaderIndex			 = -1;
+	m_SecWebSocketKeyHeaderIndex	 = -1;
+	m_SecWebSocketVersionHeaderIndex = -1;
+	m_Expect100Continue				 = false;
+	m_BodyBuffer					 = {};
+	m_BodyPosition					 = 0;
 
 	m_HeaderData.clear();
 	m_NormalizedUrl.clear();
@@ -425,4 +448,21 @@ HttpRequestParser::OnMessageComplete()
 	}
 }
 
+bool
+HttpRequestParser::IsWebSocketUpgrade() const
+{
+	std::string_view Upgrade = GetHeaderValue(m_UpgradeHeaderIndex);
+	if (Upgrade.empty())
+	{
+		return false;
+	}
+
+	// Case-insensitive check for "websocket"
+	if (Upgrade.size() != 9)
+	{
+		return false;
+	}
+	return StrCaseCompare(Upgrade.data(), "websocket", 9) == 0;
+}
+
 }  // namespace zen