TNS lookup with LDAP for Oracle Database

oracle-ldap.ts

import ldap from 'ldapjs';

const makeLDAPURL = (server: string) => {
  const [domain, mainPort, altPort]  = server.split(':');

  return [mainPort, altPort].map(port => `ldap://${domain}:${port}`);
}

// Finds a TNS string from the LDAP source
// Adapted from https://github.com/oracle/python-oracledb/discussions/71#discussioncomment-3918181
export async function tnsLookupLDAP(dbName: string, directoryServers: string[], defaultContext?: string) {
  const client = ldap.createClient({
    url: directoryServers.flatMap(makeLDAPURL)
  });

  const directory = `cn=${dbName},cn=OracleContext${defaultContext ? ',' + defaultContext : ''}`;

  const results = await new Promise<ldap.SearchEntryObject[]>((resolve, reject) => {
    setTimeout(() => reject(new Error('Request timeout')), 10000);

    client.search(directory, {}, (err, res) => {
      if (err) return reject(err);

      const entries: ldap.SearchEntryObject[] = [];

      res.on('searchEntry', entry => {
        entries.push(entry.pojo);
      });

      res.on('end', result => {
        if (!result || result.status !== 0) {
          reject(new Error(`LDAP request failed${result ? ': ' + result.errorMessage : ''}`))
        }

        resolve(entries);
      })
    });
  });

  if (results.length !== 1 || results[0].objectName !== directory) {
    throw new Error('failed to find LDAP result');
  }

  const tnsAttr = results[0].attributes.find(attr => attr.type === 'orclNetDescString');

  if (!tnsAttr || tnsAttr.values.length !== 1) {
    throw new Error('failed to locate TNS address');
  }

  return tnsAttr.values[0];
}