Websockets

apps/RenderCadenceCompositor/README.md

@@ -150,6 +150,7 @@ Current endpoints:
 
 - `GET /` and UI asset paths: serve the bundled control UI from `ui/dist`
 - `GET /api/state`: returns OpenAPI-shaped display data with cadence telemetry, supported shaders, output status, and a read-only current runtime layer
+- `GET /ws`: upgrades to a WebSocket and streams state snapshots when they change
 - `GET /docs/openapi.yaml` and `GET /openapi.yaml`: serves the OpenAPI document
 - `GET /docs`: serves Swagger UI
 - `POST /api/layers/add` and `POST /api/layers/remove` mutate the app-owned display layer model only

apps/RenderCadenceCompositor/control/HttpControlServer.cpp

@@ -6,9 +6,12 @@
 #include <ws2tcpip.h>
 
 #include <algorithm>
+#include <array>
 #include <cctype>
+#include <cstdint>
 #include <fstream>
 #include <sstream>
+#include <vector>
 
 namespace RenderCadenceCompositor
 {
@@ -41,6 +44,117 @@ bool IsKnownPostEndpoint(const std::string& path)
 		|| path == "/api/reload"
 		|| path == "/api/screenshot";
 }
+
+std::array<uint8_t, 20> Sha1(const std::string& input)
+{
+	auto leftRotate = [](uint32_t value, uint32_t bits) {
+		return (value << bits) | (value >> (32U - bits));
+	};
+
+	std::vector<uint8_t> data(input.begin(), input.end());
+	const uint64_t bitLength = static_cast<uint64_t>(data.size()) * 8ULL;
+	data.push_back(0x80);
+	while ((data.size() % 64) != 56)
+		data.push_back(0);
+	for (int shift = 56; shift >= 0; shift -= 8)
+		data.push_back(static_cast<uint8_t>((bitLength >> shift) & 0xff));
+
+	uint32_t h0 = 0x67452301;
+	uint32_t h1 = 0xefcdab89;
+	uint32_t h2 = 0x98badcfe;
+	uint32_t h3 = 0x10325476;
+	uint32_t h4 = 0xc3d2e1f0;
+
+	for (std::size_t offset = 0; offset < data.size(); offset += 64)
+	{
+		uint32_t words[80] = {};
+		for (std::size_t i = 0; i < 16; ++i)
+		{
+			const std::size_t index = offset + i * 4;
+			words[i] = (static_cast<uint32_t>(data[index]) << 24)
+				| (static_cast<uint32_t>(data[index + 1]) << 16)
+				| (static_cast<uint32_t>(data[index + 2]) << 8)
+				| static_cast<uint32_t>(data[index + 3]);
+		}
+		for (std::size_t i = 16; i < 80; ++i)
+			words[i] = leftRotate(words[i - 3] ^ words[i - 8] ^ words[i - 14] ^ words[i - 16], 1);
+
+		uint32_t a = h0;
+		uint32_t b = h1;
+		uint32_t c = h2;
+		uint32_t d = h3;
+		uint32_t e = h4;
+
+		for (std::size_t i = 0; i < 80; ++i)
+		{
+			uint32_t f = 0;
+			uint32_t k = 0;
+			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;
+			}
+
+			const uint32_t temp = leftRotate(a, 5) + f + e + k + words[i];
+			e = d;
+			d = c;
+			c = leftRotate(b, 30);
+			b = a;
+			a = temp;
+		}
+
+		h0 += a;
+		h1 += b;
+		h2 += c;
+		h3 += d;
+		h4 += e;
+	}
+
+	std::array<uint8_t, 20> digest = {};
+	const uint32_t parts[] = { h0, h1, h2, h3, h4 };
+	for (std::size_t i = 0; i < 5; ++i)
+	{
+		digest[i * 4] = static_cast<uint8_t>((parts[i] >> 24) & 0xff);
+		digest[i * 4 + 1] = static_cast<uint8_t>((parts[i] >> 16) & 0xff);
+		digest[i * 4 + 2] = static_cast<uint8_t>((parts[i] >> 8) & 0xff);
+		digest[i * 4 + 3] = static_cast<uint8_t>(parts[i] & 0xff);
+	}
+	return digest;
+}
+
+std::string Base64Encode(const uint8_t* data, std::size_t size)
+{
+	static constexpr char kAlphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+	std::string output;
+	output.reserve(((size + 2) / 3) * 4);
+	for (std::size_t i = 0; i < size; i += 3)
+	{
+		const uint32_t a = data[i];
+		const uint32_t b = i + 1 < size ? data[i + 1] : 0;
+		const uint32_t c = i + 2 < size ? data[i + 2] : 0;
+		const uint32_t triple = (a << 16) | (b << 8) | c;
+		output.push_back(kAlphabet[(triple >> 18) & 0x3f]);
+		output.push_back(kAlphabet[(triple >> 12) & 0x3f]);
+		output.push_back(i + 1 < size ? kAlphabet[(triple >> 6) & 0x3f] : '=');
+		output.push_back(i + 2 < size ? kAlphabet[triple & 0x3f] : '=');
+	}
+	return output;
+}
 }
 
 UniqueSocket::UniqueSocket(SOCKET socket) :
@@ -157,6 +271,20 @@ void HttpControlServer::Stop()
 	if (mThread.joinable())
 		mThread.join();
 
+	std::vector<std::thread> clientThreads;
+	{
+		std::lock_guard<std::mutex> lock(mClientThreadsMutex);
+		clientThreads.swap(mClientThreads);
+		for (std::thread& thread : mFinishedClientThreads)
+			clientThreads.push_back(std::move(thread));
+		mFinishedClientThreads.clear();
+	}
+	for (std::thread& thread : clientThreads)
+	{
+		if (thread.joinable())
+			thread.join();
+	}
+
 	if (mWinsockStarted)
 	{
 		WSACleanup();
@@ -185,6 +313,7 @@ void HttpControlServer::ThreadMain()
 {
 	while (mRunning.load(std::memory_order_acquire))
 	{
+		JoinFinishedClientThreads();
 		TryAcceptClient();
 		std::this_thread::sleep_for(mConfig.idleSleep);
 	}
@@ -212,9 +341,81 @@ bool HttpControlServer::HandleClient(UniqueSocket clientSocket)
 	if (!ParseHttpRequest(std::string(buffer, buffer + received), request))
 		return SendResponse(clientSocket.get(), TextResponse("400 Bad Request", "Bad Request"));
 
+	if (request.path == "/ws")
+		return HandleWebSocketClient(std::move(clientSocket), request);
+
 	return SendResponse(clientSocket.get(), RouteRequest(request));
 }
 
+bool HttpControlServer::HandleWebSocketClient(UniqueSocket clientSocket, const HttpRequest& request)
+{
+	const auto keyIt = request.headers.find("sec-websocket-key");
+	if (keyIt == request.headers.end() || keyIt->second.empty())
+		return SendResponse(clientSocket.get(), TextResponse("400 Bad Request", "Missing WebSocket key"));
+
+	std::ostringstream stream;
+	stream << "HTTP/1.1 101 Switching Protocols\r\n"
+		<< "Upgrade: websocket\r\n"
+		<< "Connection: Upgrade\r\n"
+		<< "Sec-WebSocket-Accept: " << WebSocketAcceptKey(keyIt->second) << "\r\n\r\n";
+	const std::string response = stream.str();
+	if (send(clientSocket.get(), response.c_str(), static_cast<int>(response.size()), 0) != static_cast<int>(response.size()))
+		return false;
+
+	u_long nonBlocking = 1;
+	ioctlsocket(clientSocket.get(), FIONBIO, &nonBlocking);
+
+	std::thread thread([this, socket = std::move(clientSocket)]() mutable {
+		WebSocketClientMain(std::move(socket));
+	});
+	{
+		std::lock_guard<std::mutex> lock(mClientThreadsMutex);
+		mClientThreads.push_back(std::move(thread));
+	}
+	return true;
+}
+
+void HttpControlServer::WebSocketClientMain(UniqueSocket clientSocket)
+{
+	std::string previousState;
+	while (mRunning.load(std::memory_order_acquire))
+	{
+		const std::string state = mCallbacks.getStateJson ? mCallbacks.getStateJson() : "{}";
+		if (state != previousState)
+		{
+			if (!SendWebSocketText(clientSocket.get(), state))
+				break;
+			previousState = state;
+		}
+		std::this_thread::sleep_for(std::chrono::milliseconds(250));
+	}
+
+	std::lock_guard<std::mutex> lock(mClientThreadsMutex);
+	const std::thread::id currentId = std::this_thread::get_id();
+	for (auto it = mClientThreads.begin(); it != mClientThreads.end(); ++it)
+	{
+		if (it->get_id() != currentId)
+			continue;
+		mFinishedClientThreads.push_back(std::move(*it));
+		mClientThreads.erase(it);
+		break;
+	}
+}
+
+void HttpControlServer::JoinFinishedClientThreads()
+{
+	std::vector<std::thread> finished;
+	{
+		std::lock_guard<std::mutex> lock(mClientThreadsMutex);
+		finished.swap(mFinishedClientThreads);
+	}
+	for (std::thread& thread : finished)
+	{
+		if (thread.joinable())
+			thread.join();
+	}
+}
+
 bool HttpControlServer::SendResponse(SOCKET clientSocket, const HttpResponse& response) const
 {
 	std::ostringstream stream;
@@ -360,6 +561,61 @@ std::string HttpControlServer::ActionResponse(bool ok, const std::string& error)
 	return writer.StringValue();
 }
 
+bool HttpControlServer::SendWebSocketText(SOCKET clientSocket, const std::string& text)
+{
+	if (clientSocket == INVALID_SOCKET)
+		return false;
+
+	std::vector<unsigned char> frame;
+	frame.reserve(text.size() + 16);
+	frame.push_back(0x81);
+	if (text.size() <= 125)
+	{
+		frame.push_back(static_cast<unsigned char>(text.size()));
+	}
+	else if (text.size() <= 0xffff)
+	{
+		frame.push_back(126);
+		frame.push_back(static_cast<unsigned char>((text.size() >> 8) & 0xff));
+		frame.push_back(static_cast<unsigned char>(text.size() & 0xff));
+	}
+	else
+	{
+		frame.push_back(127);
+		const uint64_t length = static_cast<uint64_t>(text.size());
+		for (int shift = 56; shift >= 0; shift -= 8)
+			frame.push_back(static_cast<unsigned char>((length >> shift) & 0xff));
+	}
+	frame.insert(frame.end(), text.begin(), text.end());
+
+	const char* data = reinterpret_cast<const char*>(frame.data());
+	int remaining = static_cast<int>(frame.size());
+	while (remaining > 0)
+	{
+		const int sent = send(clientSocket, data, remaining, 0);
+		if (sent <= 0)
+		{
+			const int error = WSAGetLastError();
+			if (error == WSAEWOULDBLOCK)
+			{
+				std::this_thread::sleep_for(std::chrono::milliseconds(2));
+				continue;
+			}
+			return false;
+		}
+		data += sent;
+		remaining -= sent;
+	}
+	return true;
+}
+
+std::string HttpControlServer::WebSocketAcceptKey(const std::string& clientKey)
+{
+	static constexpr const char* kWebSocketGuid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+	const std::array<uint8_t, 20> digest = Sha1(clientKey + kWebSocketGuid);
+	return Base64Encode(digest.data(), digest.size());
+}
+
 std::string HttpControlServer::GuessContentType(const std::filesystem::path& path)
 {
 	const std::string extension = ToLower(path.extension().string());

apps/RenderCadenceCompositor/control/HttpControlServer.h

@@ -9,8 +9,10 @@
 #include <filesystem>
 #include <functional>
 #include <map>
+#include <mutex>
 #include <string>
 #include <thread>
+#include <vector>
 
 namespace RenderCadenceCompositor
 {
@@ -89,11 +91,15 @@ public:
 	HttpResponse RouteRequestForTest(const HttpRequest& request) const;
 
 	static bool ParseHttpRequest(const std::string& rawRequest, HttpRequest& request);
+	static std::string WebSocketAcceptKey(const std::string& clientKey);
 
 private:
 	void ThreadMain();
 	bool TryAcceptClient();
 	bool HandleClient(UniqueSocket clientSocket);
+	bool HandleWebSocketClient(UniqueSocket clientSocket, const HttpRequest& request);
+	void WebSocketClientMain(UniqueSocket clientSocket);
+	void JoinFinishedClientThreads();
 	bool SendResponse(SOCKET clientSocket, const HttpResponse& response) const;
 	HttpResponse RouteRequest(const HttpRequest& request) const;
 	HttpResponse ServeGet(const HttpRequest& request) const;
@@ -107,6 +113,7 @@ private:
 	static HttpResponse TextResponse(const std::string& status, const std::string& body);
 	static HttpResponse HtmlResponse(const std::string& status, const std::string& body);
 	static std::string ActionResponse(bool ok, const std::string& error = std::string());
+	static bool SendWebSocketText(SOCKET clientSocket, const std::string& text);
 	static std::string GuessContentType(const std::filesystem::path& path);
 	static bool IsSafeRelativePath(const std::filesystem::path& path);
 	static std::string ToLower(std::string text);
@@ -117,6 +124,9 @@ private:
 	HttpControlServerCallbacks mCallbacks;
 	UniqueSocket mListenSocket;
 	std::thread mThread;
+	std::mutex mClientThreadsMutex;
+	std::vector<std::thread> mClientThreads;
+	std::vector<std::thread> mFinishedClientThreads;
 	std::atomic<bool> mRunning{ false };
 	unsigned short mPort = 0;
 	bool mWinsockStarted = false;

docs/openapi.yaml

@@ -8,8 +8,8 @@ info:
     The API is intended for local control tools and the bundled React UI. All mutating
     endpoints return a small action result object.
 
-    WebSocket state streaming is planned for the control UI but is not currently served
-    by RenderCadenceCompositor. Clients should poll `/api/state` until `/ws` is implemented.
+    RenderCadenceCompositor serves `/api/state` for snapshots and `/ws` for local
+    WebSocket state updates consumed by the bundled control UI.
 servers:
   - url: http://127.0.0.1:8080
     description: Default local control server
@@ -179,6 +179,24 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/RuntimeState"
+  /ws:
+    get:
+      tags: [State]
+      summary: Stream runtime state over WebSocket
+      description: |
+        Upgrades to a WebSocket connection. The server sends JSON runtime-state
+        snapshots using the same shape as `GET /api/state` whenever the serialized
+        state changes.
+      operationId: streamRuntimeState
+      responses:
+        "101":
+          description: WebSocket protocol upgrade accepted.
+        "400":
+          description: The request was not a valid WebSocket upgrade.
+          content:
+            text/plain:
+              schema:
+                type: string
   /api/layers/add:
     post:
       tags: [Layers]

tests/RenderCadenceCompositorHttpControlServerTests.cpp

@@ -63,6 +63,14 @@ void TestStateEndpointUsesCallback()
 	ExpectEquals(response.body, "{\"ok\":true}", "state endpoint returns callback JSON");
 }
 
+void TestWebSocketAcceptKey()
+{
+	using namespace RenderCadenceCompositor;
+
+	const std::string acceptKey = HttpControlServer::WebSocketAcceptKey("dGhlIHNhbXBsZSBub25jZQ==");
+	ExpectEquals(acceptKey, "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=", "WebSocket accept key matches RFC example");
+}
+
 void TestRootServesUiIndex()
 {
 	using namespace RenderCadenceCompositor;
@@ -157,6 +165,7 @@ int main()
 {
 	TestParsesHttpRequest();
 	TestStateEndpointUsesCallback();
+	TestWebSocketAcceptKey();
 	TestRootServesUiIndex();
 	TestKnownPostEndpointReturnsActionError();
 	TestLayerPostEndpointsUseCallbacks();