lib/client/client.js
function connectSocket(cb) {
    cb = once(cb);

    function onResult(err, res) {
      if (err) {
        if (self.connectTimer) {
          clearTimeout(self.connectTimer);
          self.connectTimer = null;
        }
        self.emit('connectError', err);
      }
      cb(err, res);
    }
    function onConnect() {
      if (self.connectTimer) {
        clearTimeout(self.connectTimer);
        self.connectTimer = null;
      }
      socket.removeAllListeners('error')
        .removeAllListeners('connect')
        .removeAllListeners('secureConnect');

      tracker.id = nextClientId() + '__' + tracker.id;
      self.log = self.log.child({ldap_id: tracker.id}, true);

      // Move on to client setup
      setupClient(cb);
    }

    var port = (self.port || self.socketPath);
    if (self.secure) {
      socket = tls.connect(port, self.host, self.tlsOptions);
      socket.once('secureConnect', onConnect);
    } else {
      socket = net.connect(port, self.host);
      socket.once('connect', onConnect);
    }
    socket.once('error', onResult);
    initSocket();

    // Setup connection timeout handling, if desired
    if (self.connectTimeout) {
      self.connectTimer = setTimeout(function onConnectTimeout() {
        if (!socket || !socket.readable || !socket.writeable) {
          socket.destroy();
          self._socket = null;
          onResult(new ConnectionError('connection timeout'));
        }
      }, self.connectTimeout);
    }
  }
function connectSocket(cb) {
    cb = once(cb);

    function onResult(err, res) {
      if (err) {
        if (self.connectTimer) {
          clearTimeout(self.connectTimer);
          self.connectTimer = null;
        }
        self.emit('connectError', err);
      }
      cb(err, res);
    }
    function onConnect() {
      if (self.connectTimer) {
        clearTimeout(self.connectTimer);
        self.connectTimer = null;
      }
      socket.removeAllListeners('error')
        .removeAllListeners('connect')
        .removeAllListeners('secureConnect');

      tracker.id = nextClientId() + '__' + tracker.id;
      self.log = self.log.child({ldap_id: tracker.id}, true);

      // Move on to client setup
      setupClient(cb);
    }

    var port = (self.port || self.socketPath);
    if (self.secure) {
      socket = tls.connect(port, self.host, self.tlsOptions);
      socket.once('secureConnect', onConnect);
    } else {
      socket = net.connect(port, self.host);
      socket.once('connect', onConnect);
    }
    socket.once('error', onResult);
    initSocket();

    // Setup connection timeout handling, if desired
    if (self.connectTimeout) {
      self.connectTimer = setTimeout(function onConnectTimeout() {
        if (!socket || !socket.readable || !socket.writeable) {
          socket.destroy();
          self._socket = null;
          onResult(new ConnectionError('connection timeout'));
        }
      }, self.connectTimeout);
    }
  }
Establish basic socket connection