Function performInitialHandshake

src/cmap/connect.ts:90–210

(
  conn: Connection,
  options: ConnectionOptions
)

}

export async function performInitialHandshake(
  conn: Connection,
  options: ConnectionOptions
): Promise<void> {
  const credentials = options.credentials;

  if (credentials) {
    if (
      !(credentials.mechanism === AuthMechanism.MONGODB_DEFAULT) &&
      !options.authProviders.getOrCreateProvider(
        credentials.mechanism,
        credentials.mechanismProperties
      )
    ) {
      throw new MongoInvalidArgumentError(`AuthMechanism '${credentials.mechanism}' not supported`);
    }
  }

  const authContext = new AuthContext(conn, credentials, options);
  conn.authContext = authContext;

  // If we encounter an error preparing the handshake document, do NOT apply backpressure labels.  Errors
  // encountered building the handshake document are all client-side, and do not indicate an overloaded server.
  const handshakeDoc = await prepareHandshakeDocument(authContext);

  // @ts-expect-error: TODO(NODE-5141): The options need to be filtered properly, Connection options differ from Command options
  const handshakeOptions: CommandOptions = { ...options, raw: false };
  if (typeof options.connectTimeoutMS === 'number') {
    // The handshake technically is a monitoring check, so its socket timeout should be connectTimeoutMS
    handshakeOptions.socketTimeoutMS = options.connectTimeoutMS;
  }

  const start = new Date().getTime();

  const response = await executeHandshake(handshakeDoc, handshakeOptions);

  if (!('isWritablePrimary' in response)) {
    // Provide hello-style response document.
    response.isWritablePrimary = response[LEGACY_HELLO_COMMAND];
  }

  if (response.helloOk) {
    conn.helloOk = true;
  }

  const supportedServerErr = checkSupportedServer(response, options);
  if (supportedServerErr) {
    throw supportedServerErr;
  }

  if (options.loadBalanced) {
    if (!response.serviceId) {
      throw new MongoCompatibilityError(
        'Driver attempted to initialize in load balancing mode, ' +
          'but the server does not support this mode.'
      );
    }
  }