wip extension

browser-ext/proxy/proxy.js

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+/**
+ * DAP WebSocket-to-TCP Proxy
+ *
+ * Bridges WebSocket connections from browser extensions to the DAP TCP server.
+ * Handles DAP message framing (Content-Length headers).
+ *
+ * Usage: node proxy.js [--ws-port 4712] [--dap-host 127.0.0.1] [--dap-port 4711]
+ */
+
+const WebSocket = require('ws');
+const net = require('net');
+
+// Configuration (can be overridden via CLI args)
+const config = {
+  wsPort: parseInt(process.env.WS_PORT) || 4712,
+  dapHost: process.env.DAP_HOST || '127.0.0.1',
+  dapPort: parseInt(process.env.DAP_PORT) || 4711,
+};
+
+// Parse CLI arguments
+for (let i = 2; i < process.argv.length; i++) {
+  switch (process.argv[i]) {
+    case '--ws-port':
+      config.wsPort = parseInt(process.argv[++i]);
+      break;
+    case '--dap-host':
+      config.dapHost = process.argv[++i];
+      break;
+    case '--dap-port':
+      config.dapPort = parseInt(process.argv[++i]);
+      break;
+  }
+}
+
+console.log(`[Proxy] Starting WebSocket-to-TCP proxy`);
+console.log(`[Proxy] WebSocket: ws://localhost:${config.wsPort}`);
+console.log(`[Proxy] DAP Server: tcp://${config.dapHost}:${config.dapPort}`);
+
+const wss = new WebSocket.Server({ port: config.wsPort });
+
+console.log(`[Proxy] WebSocket server listening on port ${config.wsPort}`);
+
+wss.on('connection', (ws, req) => {
+  const clientId = `${req.socket.remoteAddress}:${req.socket.remotePort}`;
+  console.log(`[Proxy] WebSocket client connected: ${clientId}`);
+
+  // Connect to DAP TCP server
+  const tcp = net.createConnection({
+    host: config.dapHost,
+    port: config.dapPort,
+  });
+
+  let tcpBuffer = '';
+  let tcpConnected = false;
+
+  tcp.on('connect', () => {
+    tcpConnected = true;
+    console.log(`[Proxy] Connected to DAP server at ${config.dapHost}:${config.dapPort}`);
+  });
+
+  tcp.on('error', (err) => {
+    console.error(`[Proxy] TCP error: ${err.message}`);
+    if (ws.readyState === WebSocket.OPEN) {
+      ws.send(
+        JSON.stringify({
+          type: 'proxy-error',
+          message: `Failed to connect to DAP server: ${err.message}`,
+        })
+      );
+      ws.close(1011, 'DAP server connection failed');
+    }
+  });
+
+  tcp.on('close', () => {
+    console.log(`[Proxy] TCP connection closed`);
+    if (ws.readyState === WebSocket.OPEN) {
+      ws.close(1000, 'DAP server disconnected');
+    }
+  });
+
+  // WebSocket → TCP: Add Content-Length framing
+  ws.on('message', (data) => {
+    if (!tcpConnected) {
+      console.warn(`[Proxy] TCP not connected, dropping message`);
+      return;
+    }
+
+    const json = data.toString();
+    try {
+      // Validate it's valid JSON
+      const parsed = JSON.parse(json);
+      console.log(`[Proxy] WS→TCP: ${parsed.command || parsed.event || 'message'}`);
+
+      // Add DAP framing
+      const framed = `Content-Length: ${Buffer.byteLength(json)}\r\n\r\n${json}`;
+      tcp.write(framed);
+    } catch (err) {
+      console.error(`[Proxy] Invalid JSON from WebSocket: ${err.message}`);
+    }
+  });
+
+  // TCP → WebSocket: Parse Content-Length framing
+  tcp.on('data', (chunk) => {
+    tcpBuffer += chunk.toString();
+
+    // Process complete DAP messages from buffer
+    while (true) {
+      // Look for Content-Length header
+      const headerEnd = tcpBuffer.indexOf('\r\n\r\n');
+      if (headerEnd === -1) break;
+
+      const header = tcpBuffer.substring(0, headerEnd);
+      const match = header.match(/Content-Length:\s*(\d+)/i);
+      if (!match) {
+        console.error(`[Proxy] Invalid DAP header: ${header}`);
+        tcpBuffer = tcpBuffer.substring(headerEnd + 4);
+        continue;
+      }
+
+      const contentLength = parseInt(match[1]);
+      const messageStart = headerEnd + 4;
+      const messageEnd = messageStart + contentLength;
+
+      // Check if we have the complete message
+      if (tcpBuffer.length < messageEnd) break;
+
+      // Extract the JSON message
+      const json = tcpBuffer.substring(messageStart, messageEnd);
+      tcpBuffer = tcpBuffer.substring(messageEnd);
+
+      // Send to WebSocket
+      try {
+        const parsed = JSON.parse(json);
+        console.log(
+          `[Proxy] TCP→WS: ${parsed.type} ${parsed.command || parsed.event || ''} ${parsed.request_seq ? `(req_seq: ${parsed.request_seq})` : ''}`
+        );
+
+        if (ws.readyState === WebSocket.OPEN) {
+          ws.send(json);
+        }
+      } catch (err) {
+        console.error(`[Proxy] Invalid JSON from TCP: ${err.message}`);
+      }
+    }
+  });
+
+  // Handle WebSocket close
+  ws.on('close', (code, reason) => {
+    console.log(`[Proxy] WebSocket closed: ${code} ${reason}`);
+    tcp.end();
+  });
+
+  ws.on('error', (err) => {
+    console.error(`[Proxy] WebSocket error: ${err.message}`);
+    tcp.end();
+  });
+});
+
+wss.on('error', (err) => {
+  console.error(`[Proxy] WebSocket server error: ${err.message}`);
+});
+
+// Graceful shutdown
+process.on('SIGINT', () => {
+  console.log(`\n[Proxy] Shutting down...`);
+  wss.clients.forEach((ws) => ws.close(1001, 'Server shutting down'));
+  wss.close(() => {
+    console.log(`[Proxy] Goodbye!`);
+    process.exit(0);
+  });
+});