node-websocket-proxy.js

var http = require('http');
var express = require('express');
var WebSocketServer = require('ws').Server;
var Net = require('net');
var Protocol = require('_debugger').Protocol;

var config = {
  port: 9222,
  nodeDebugPort: 5858
}

function jsonAction(req, res) {
  res.json([{
    'description': 'Node.js app (powered by node-websocket-proxy)',
    'devtoolsFrontendUrl': 'http://example.com/not-supported',
    'id': process.pid,
    'title': process.title ||'',
    'type': 'page',
    'url': '',
    'webSocketDebuggerUrl': 'ws://localhost:' + config.port + '/'
  }]);
}

function jsonVersionAction(req, res) {
  res.json({
    'browser': 'Node ' + process.version,
    'protocol-version': '1.1',
    'user-agent': 'Node ' + process.version,
    // webKit-version is a dummy value as it's used to match compatible DevTools front-ends
    'webKit-version': '537.36 (@181352)'
  });
}

var noopCommands = [
  'Network.enable',
  'Network.setCacheDisabled',
  'Console.enable',
  'Console.setMonitoringXHREnabled',
  'Console.addInspectedHeapObject',
  'Database.enable',
  'DOMDebugger.setXHRBreakpoint',
  'DOMDebugger.removeXHRBreakpoint',
  'DOMDebugger.setInstrumentationBreakpoint',
  'DOMDebugger.removeInstrumentationBreakpoint',
  'DOMStorage.enable',
  'DOM.hideHighlight',
  'Inspector.enable',
  'Page.addScriptToEvaluateOnLoad',
  'Page.removeScriptToEvaluateOnLoad',
  'Page.setDeviceOrientationOverride',
  'Page.clearDeviceOrientationOverride',
  'Page.setGeolocationOverride',
  'Page.clearGeolocationOverride',
  'Page.setContinuousPaintingEnabled',
  'Page.setEmulatedMedia',
  'Page.setDeviceMetricsOverride',
  'Page.setScriptExecutionDisabled',
  'Page.setShowDebugBorders',
  'Page.setShowFPSCounter',
  'Page.setShowScrollBottleneckRects',
  'Page.setShowViewportSizeOnResize',
  'Page.setShowPaintRects',
  'Page.setForceCompositingMode',
  'CSS.enable',
  'CSS.disable',
  'DOM.enable',
  'DOM.disable',
  'Runtime.run',
  'IndexedDB.enable',
  'HeapProfiler.enable',
  'Debugger.setAsyncCallStackDepth',
  'Debugger.skipStackFrames',
  'Console.setTracingBasedTimeline',
  'Profiler.setSamplingInterval',
  'Worker.setAutoconnectToWorkers'
]

function handleConnection(server, socket) {
  var connection = Net.createConnection(config.nodeDebugPort);
  var protocol = new Protocol();
  var isConnected = false;
  var queuedMessages = [];

  function sendMessage(message) {
    // Some special commands must be ignored
    if(noopCommands.indexOf(message.method) !== -1) {
      socket.send(JSON.stringify({
        id: message.id,
        success: true
      }));
      return;
    }

    var outgoing = {
      seq: message.id,
      type: 'request',
      command: message.method
    }
    if(message.params) {
      Object.keys(message.params).forEach(function(key) {
        outgoing[key] = message.params[key];
      });
    }
    var str = JSON.stringify(outgoing);
    console.log('sending to server:', outgoing);
    connection.write(
      'Content-Length: ' + Buffer.byteLength(str, 'utf8') +
      '\r\n\r\n' + str
    );
  }

  socket.on('message', function(message) {
    message = JSON.parse(message);
    if(!isConnected) {
      queuedMessages.push(message);
      return;
    }

    sendMessage(message);
  });

  protocol.onResponse = function(message) {
    console.log('got from server:', message);
    socket.send(JSON.stringify(message.body));
    if(message.raw.indexOf('Type: connect') !== -1) {
      isConnected = true;
      queuedMessages.forEach(function(message) {
        sendMessage(message);
      });
      queuedMessages = [];
    }
  }

  connection.on('data', protocol.execute.bind(protocol));
  connection.on('error', function(err) { console.log('TCP error:', error); });
  connection.on('end', function() { console.log('TCP end') });
  connection.on('close', function() { console.log('TCP closed') });
  connection.setEncoding('utf8');
}

function createServer() {
  var app = express();
  var httpServer = http.createServer(app);
  var wsServer = new WebSocketServer({
    server: httpServer
  });
  var server = {
    http: httpServer,
    ws: wsServer
  };

  app.get('/json', jsonAction);
  app.get('/json/list', jsonAction);
  app.get('/json/version', jsonVersionAction);

  wsServer.on('connection', handleConnection.bind(null, server));

  httpServer.listen(config.port);
}

createServer();