Function resolveSRVRecord

src/connection_string.ts:77–158

(options: MongoOptions)

 * @param options - Optional user provided connection string options
 */
export async function resolveSRVRecord(options: MongoOptions): Promise<HostAddress[]> {
  if (typeof options.srvHost !== 'string') {
    throw new MongoAPIError('Option "srvHost" must not be empty');
  }

  // Asynchronously start TXT resolution so that we do not have to wait until
  // the SRV record is resolved before starting a second DNS query.
  const lookupAddress = options.srvHost;
  const txtResolutionPromise = resolveTxt(lookupAddress);

  txtResolutionPromise.then(undefined, squashError); // rejections will be handled later

  const hostname = `_${options.srvServiceName}._tcp.${lookupAddress}`;
  // Resolve the SRV record and use the result as the list of hosts to connect to.
  const addresses = await resolveSrv(hostname);

  if (addresses.length === 0) {
    throw new MongoAPIError('No addresses found at host');
  }

  for (const { name } of addresses) {
    checkParentDomainMatch(name, lookupAddress);
  }

  const hostAddresses = addresses.map(r => HostAddress.fromString(`${r.name}:${r.port ?? 27017}`));

  validateLoadBalancedOptions(hostAddresses, options, true);

  // Use the result of resolving the TXT record and add options from there if they exist.
  let record;
  try {
    record = await txtResolutionPromise;
  } catch (error) {
    if (error.code !== 'ENODATA' && error.code !== 'ENOTFOUND') {
      throw error;
    }
    return hostAddresses;
  }

  if (record.length > 1) {
    throw new MongoParseError('Multiple text records not allowed');
  }

  const txtRecordOptions = new URLSearchParams(record[0].join(''));
  const txtRecordOptionKeys = [...txtRecordOptions.keys()];
  if (txtRecordOptionKeys.some(key => !VALID_TXT_RECORDS.includes(key))) {
    throw new MongoParseError(`Text record may only set any of: ${VALID_TXT_RECORDS.join(', ')}`);
  }

  if (VALID_TXT_RECORDS.some(option => txtRecordOptions.get(option) === '')) {
    throw new MongoParseError('Cannot have empty URI params in DNS TXT Record');
  }

  const source = txtRecordOptions.get('authSource') ?? undefined;
  const replicaSet = txtRecordOptions.get('replicaSet') ?? undefined;
  const loadBalanced = txtRecordOptions.get('loadBalanced') ?? undefined;

  if (