Method open

lib/connection.js:172–219

* Connects a socket and sends the startup protocol messages. * Note that when open() callbacks in error, the caller should immediately call Connection#close.

(callback)

   * Note that when open() callbacks in error, the caller should immediately call {@link Connection#close}.
   */
  open(callback) {
    const self = this;
    this.log('info', `Connecting to ${this.endpointFriendlyName}`);

    if (!this.options.sslOptions) {
      this.netClient = new net.Socket({ highWaterMark: this.options.socketOptions.coalescingThreshold });
      this.netClient.connect(this.port, this.address, function connectCallback() {
        self.log('verbose', `Socket connected to ${self.endpointFriendlyName}`);
        self.bindSocketListeners();
        self.startup(callback);
      });
    }
    else {
      // Use TLS
      const sslOptions = utils.extend({ rejectUnauthorized: false }, this.options.sslOptions);

      if (this.options.sni) {
        sslOptions.servername = this._serverName;
      }

      this.netClient = tls.connect(this.port, this.address, sslOptions, function tlsConnectCallback() {
        self.log('verbose', `Secure socket connected to ${self.endpointFriendlyName} with protocol ${self.netClient.getProtocol()}`);
        self.bindSocketListeners();
        self.startup(callback);
      });

      // TLSSocket will validate for values from 512 to 16K (depending on the SSL protocol version)
      this.netClient.setMaxSendFragment(this.options.socketOptions.coalescingThreshold);
    }

    this.netClient.once('error', function socketError(err) {
      self.errorConnecting(err, false, callback);
    });

    this.netClient.once('timeout', function connectTimedOut() {
      const err = new types.DriverError('Connection timeout');
      self.errorConnecting(err, true, callback);
    });

    this.netClient.setTimeout(this.options.socketOptions.connectTimeout);

    // Improve failure detection with TCP keep-alives
    if (this.options.socketOptions.keepAlive) {
      this.netClient.setKeepAlive(true, this.options.socketOptions.keepAliveDelay);
    }

    this.netClient.setNoDelay(!!this.options.socketOptions.tcpNoDelay);
  }

  /**
   * Determines the protocol version to use and sends the STARTUP request