!747

m {
  static int threads = 10;
  static int timeout = 500; // SHOULD be enough...
  static String ip = "127.0.0.1";
  
  p {
    final ExecutorService es = Executors.newFixedThreadPool(threads);
    print("Port scanning " + ip + " with timeout " + timeout + " ms in " + threads + " threads.");
    startTiming();
    new List<Future<Integer>> futures;
    for (int port = 1; port <= 65535; port++) {
      futures.add(portIsOpen(es, ip, port, timeout));
    }
    es.shutdown();
    new List<Integer> openPorts;
    for (final Future<Integer> f : futures) {
      int port = f.get();
      if (port != 0)
        openPorts.add(port);
    }
    stopTiming();
    System.out.println("There are " + openPorts.size() + " open ports on host " + ip + ": " + structure(openPorts));
  }

  public static Future<Integer> portIsOpen(final ExecutorService es, final String ip, final int port, final int timeout) {
    return es.submit(new Callable<Integer>() {
        @Override public Integer call() {
          try {
            Socket socket = new Socket();
            socket.connect(new InetSocketAddress(ip, port), timeout);
            print("Connected to " + ip + ":" + port);
            socket.close();
            return port;
          } catch (Exception ex) {
            return 0;
          }
        }
     });
  }
}