Method _connect

src/mongo_client.ts:619–696

* Create a topology to open the connection, must be locked to avoid topology leaks in concurrency scenario. * Locking is enforced by the connect method. * * @internal

()

   * @internal
   */
  private async _connect(): Promise<this> {
    if (this.topology && this.topology.isConnected()) {
      return this;
    }

    const options = this.options;

    if (options.tls) {
      if (typeof options.tlsCAFile === 'string') {
        options.ca ??= await fs.readFile(options.tlsCAFile);
      }
      if (typeof options.tlsCRLFile === 'string') {
        options.crl ??= await fs.readFile(options.tlsCRLFile);
      }
      if (typeof options.tlsCertificateKeyFile === 'string') {
        if (!options.key || !options.cert) {
          const contents = await fs.readFile(options.tlsCertificateKeyFile);
          options.key ??= contents;
          options.cert ??= contents;
        }
      }
    }
    if (typeof options.srvHost === 'string') {
      const hosts = await resolveSRVRecord(options);

      for (const [index, host] of hosts.entries()) {
        options.hosts[index] = host;
      }
    }

    // It is important to perform validation of hosts AFTER SRV resolution, to check the real hostname,
    // but BEFORE we even attempt connecting with a potentially not allowed hostname
    if (options.credentials?.mechanism === AuthMechanism.MONGODB_OIDC) {
      const allowedHosts =
        options.credentials?.mechanismProperties?.ALLOWED_HOSTS || DEFAULT_ALLOWED_HOSTS;
      const isServiceAuth = !!options.credentials?.mechanismProperties?.ENVIRONMENT;
      if (!isServiceAuth) {
        for (const host of options.hosts) {
          if (!hostMatchesWildcards(host.toHostPort().host, allowedHosts)) {
            throw new MongoInvalidArgumentError(
              `Host '${host}' is not valid for OIDC authentication with ALLOWED_HOSTS of '${allowedHosts.join(
                ','
              )}'`
            );
          }
        }
      }
    }

    this.topology = new Topology(this, options.hosts, options);
    // Events can be emitted before initialization is complete so we have to
    // save the reference to the topology on the client ASAP if the event handlers need to access it

    this.topology.once(Topology.OPEN, () => this.emit('open', this));

    for (const event of MONGO_CLIENT_EVENTS) {
      this.topology.on(event, (...args: any[]) => this.emit(event, ...(args as any)));
    }