Automatically join sockets to user-specific rooms using express.js sessions and socket.io

app.js

/**
 * Module dependencies.
 */

var express = require('express'),
    http = require('http'),
    RedisStore = require('connect-redis')(express),
    redis = require('redis'),
    cookie = require('cookie'),
    connect = require('connect'),
    app = express(),
    redisClient = redis.createClient(),
    sessionStore = new RedisStore({client: redisClient}),
    io;



app.configure(function(){
  app.set('port', process.env.PORT || 3010);
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.use(express.favicon());
  app.use(express.logger('dev'));
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(express.cookieParser());
  app.use(express.session({store: sessionStore, secret: 'my_secret', key: 'myapp.sid'}));
  app.use(app.router);
});

app.configure('development', function(){
  app.use(express.errorHandler());
});

app.get('/', routes.index);

var server = http.createServer(app).listen(app.get('port'), function(){
  console.log("Express server listening on port " + app.get('port'));
});

io = require('socket.io').listen(server);

io.set('authorization', function (handshakeData, accept) {

  if (handshakeData.headers.cookie) {

    var handshakeCookie = cookie.parse(handshakeData.headers.cookie);

    var sessionId = connect.utils.parseSignedCookie(handshakeCookie['myapp.sid'], 'my_secret');
    if (!sessionId) {
      return accept(new Error('Invalid cookie.'), false);
    }

    sessionStore.get(sessionId, function(err, data) { // Get user id set by req.session.userId = '<userid>'
      if (err) return accept(new Error('Unable to find session'), false);
      handshakeData.userId = data.userId;
      accept(null, true);
    });

  } else {
    return accept(new Error('No cookie available.'), false);
  }
});

io.sockets.on('connection', function(socket) {
  socket.join(socket.handshake.userId);
});