Socket.IO / Express / Connection sid parsing

sessions.js

  // Setup authorization for socket.io to ensure that the user actually has
  // access to this socket.io instance
  io.set('authorization', function authorization(handshake, done) {
    if (!handshake.headers.cookie) return done('No cookie transmitted', false);

    var sessionID = /connect.sid\=([^;]+)/g.exec(handshake.headers.cookie);
    if (sessionID && sessionID.length) handshake.sessionID = unescape(sessionID[1]).split('.')[0].slice(2);

    // Only allow connections that are logged in.
    sessions.get(handshake.sessionID, function (err, sess) {
      done(err, sess && sess.loggedIn, handshake);
    });
  });