anisail/tunnel/index.mjs

/**
 * anisail-tunnel: Bare-compatible Holesail client that binds a local port and
 * prints it to stdout for the Ansible connection plugin. Keeps running until
 * stdin closes or SIGTERM/SIGINT.
 *
 * Usage: anisail-tunnel --key <hs://...> [--remote-port 22] [--local-port 0] [--timeout 30000]
 * Output: exactly one JSON line to stdout: {"local_port": <number>, "ready": true}
 */

import 'bare-process/global';

const DEFAULT_REMOTE_PORT = 22;
const DEFAULT_LOCAL_PORT = 0;
const DEFAULT_TIMEOUT_MS = 30000;
const LOCAL_HOST = '127.0.0.1';

function parseArgs() {
  // slice(1): when run as a bundled binary, argv is [binaryPath, ...cliArgs]; slice(2) would drop --key
  const args = process.argv.slice(1);
  let key = null;
  let remotePort = DEFAULT_REMOTE_PORT;
  let localPort = DEFAULT_LOCAL_PORT;
  let timeoutMs = DEFAULT_TIMEOUT_MS;

  for (let i = 0; i < args.length; i++) {
    if (args[i] === '--key' && args[i + 1]) {
      key = args[++i].trim();
    } else if (args[i] === '--remote-port' && args[i + 1]) {
      remotePort = parseInt(args[++i], 10) || DEFAULT_REMOTE_PORT;
    } else if (args[i] === '--local-port' && args[i + 1]) {
      localPort = parseInt(args[++i], 10);
      if (isNaN(localPort) || localPort < 0) localPort = DEFAULT_LOCAL_PORT;
    } else if (args[i] === '--timeout' && args[i + 1]) {
      timeoutMs = parseInt(args[++i], 10) || DEFAULT_TIMEOUT_MS;
    }
  }

  return { key, remotePort, localPort, timeoutMs };
}

function emit(line) {
  try {
    process.stdout.write(line + '\n');
  } catch (_) {}
}

/**
 * Verify that the port is accepting TCP connections before we report it.
 * Tries to connect to host:port; resolves when connect succeeds (then we close the socket).
 * Rejects on error or after timeoutMs.
 */
function waitUntilPortAccepting(host, port, timeoutMs = 10000, intervalMs = 200) {
  const deadline = Date.now() + timeoutMs;
  return new Promise((resolve, reject) => {
    function tryConnect() {
      if (Date.now() >= deadline) {
        reject(new Error('Port did not accept connections within ' + timeoutMs + 'ms'));
        return;
      }
      import('net').then((net) => {
        const socket = net.createConnection(
          { port, host, allowHalfOpen: false },
          () => {
            socket.setTimeout(0);
            socket.destroy();
            resolve();
          }
        );
        socket.on('error', () => {
          socket.destroy();
          setTimeout(tryConnect, intervalMs);
        });
        socket.setTimeout(intervalMs, () => {
          socket.destroy();
          setTimeout(tryConnect, intervalMs);
        });
      }).catch(reject);
    }
    tryConnect();
  });
}

async function run() {
  const mod = await import('holesail');
  const Holesail = mod.default || mod;

  const { key, remotePort, localPort, timeoutMs } = parseArgs();

  if (!key || key.length === 0) {
    const msg = 'anisail-tunnel: --key <hs://...> is required';
    try {
      process.stderr.write(msg + '\n');
    } catch (_) {}
    process.exitCode = 1;
    return;
  }

  const portToUse = (localPort > 0 ? localPort : 19200 + Math.floor(Math.random() * 1000)) || 19200;

  const readyPromise = new Promise((resolve, reject) => {
    const t = timeoutMs > 0
      ? setTimeout(() => reject(new Error('Tunnel ready timeout after ' + timeoutMs + 'ms')), timeoutMs)
      : null;
    const done = (err, port) => {
      if (t) clearTimeout(t);
      if (err) reject(err);
      else resolve(port);
    };

    const opts = {
      client: true,
      key,
      host: LOCAL_HOST,
      port: portToUse
    };
    // If the Holesail API supports remotePort, tell it which port on the peer to use (e.g. 22 for SSH).
    if (remotePort > 0 && remotePort <= 65535) {
      opts.remotePort = remotePort;
    }
    const hs = new Holesail(opts);

    if (typeof hs.on === 'function') {
      hs.on('error', (err) => {
        done(err || new Error('Tunnel error'));
      });
    }

    hs.ready()
      .then(() => {
        const info = typeof hs.info === 'function' ? hs.info() : (hs.info || {});
        const boundPort = (info && typeof info.port === 'number')
          ? info.port
          : portToUse;
        if (boundPort == null || boundPort < 1 || boundPort > 65535) {
          done(new Error('Could not determine local tunnel port'));
          return;
        }
        done(null, boundPort);
        return hs;
      })
      .catch(done);

    run._hs = hs;
  });

  let hs;
  try {
    const port = await readyPromise;
    hs = run._hs;
    // Verify the port is actually accepting connections before reporting it
    await waitUntilPortAccepting(LOCAL_HOST, port, 10000, 200);
    emit(JSON.stringify({ local_port: port, ready: true }));
  } catch (err) {
    const msg = (err && err.message) ? err.message : String(err);
    try {
      process.stderr.write('anisail-tunnel: ' + msg + '\n');
    } catch (_) {}
    process.exitCode = 1;
    return;
  }

  const close = () => {
    if (hs && typeof hs.close === 'function') {
      try {
        hs.close();
      } catch (_) {}
      hs = null;
    }
    process.exitCode = 0;
    process.exit(0);
  };

  process.on('SIGTERM', close);
  process.on('SIGINT', close);

  process.stdin.on('close', () => {
    close();
  });
  process.stdin.on('end', () => {
    close();
  });

  process.stdin.resume();
}

run().catch((err) => {
  try {
    process.stderr.write('anisail-tunnel: ' + (err && err.message ? err.message : String(err)) + '\n');
  } catch (_) {}
  process.exitCode = 1;
});