100 lines of PHP code to implement socks5 proxy server

Two days ago, I saw a guy on Station B trying to assemble a computer for 100 yuan to play LOL with smooth graphics. I suddenly thought that 100 lines of code could (simplely) achieve something fun. I mainly do PHP development, so I have this article.

Of course, since PHP (not counting swoole extension) itself is not good at network server programming, this proxy is just a toy, a little far away from daily use. If you want to use a stable and reliable encryption (so you can learn to surf the Internet) proxy, you can use this: https://github.com/momaer/asocks-go is also 100 lines of code and implemented using go.

During the writing process, I found that PHP multi-threading is still difficult. For example, I started to want to create a new thread for each connection. But this thread must be saved (for example, saved in an array), such as this one in the official example: https://github.com/krakjoe/pthreads/blob/master/examples/SocketServer.phpIt should be placed in the $clients array , otherwise, you can try (curl -L an address that requires 301) and you will know what happens.

This example says that in the real world, do something here to ensure clients not running are destroyed. However, it does not talk about how to destroy connections that are no longer running. kindness. I tried putting $clients into a class, passing the class to the thread class, and then unsetting the corresponding connection in $clients when the thread class was about to end, to no avail.

Then, the following is a proxy implemented using a thread pool. Logically speaking, the pool needs to be shutdown() when exiting, and the monitoring socket must also be shut down. But with hundreds of lines of code, there is no need to force it. With ctrl + c, it Let the operating system reclaim resources.

Why is PHP not good at network programming? First of all, I used the stream_socket_XXX related functions. Why not use socket extension? Because there is a problem with the socket extension, see: https://github.com/krakjoe/pthreads/issues/581 And stream_set_timeout does not work for advanced operations such as stream_socket_recvfrom, see: http://php.net/manual/en /function.stream-set-timeout.phpAnd these need to be considered when writing a proxy. For example, when connecting to a remote target server, there is no timeout control, and the thread pool can easily become full.

For testing, just use curl. By the way, currently only remote dns resolution is supported. Why? Because this toy will need to be used to access the Internet later: curl --socks5-hostname 127.0.0.1:1080http://ip.cn

Class Pipe extends Threaded
{
  private $client;
  private $remote;
  public function __construct($client, $remote) 
  {
    $this->client = $client;
    $this->remote = $remote; 
  }
  public function run()
  {
    for ( ; ; ) {
        $data = stream_socket_recvfrom($this->client, 4096);
        if ($data === false || strlen($data) === 0) {
          break;
        } 
        $sendBytes = stream_socket_sendto($this->remote, $data);
        if ($sendBytes <= 0) {
          break;
        }
    }
    stream_socket_shutdown($this->client, STREAM_SHUT_RD);
    stream_socket_shutdown($this->remote, STREAM_SHUT_WR);
  }
}

Class Client extends Threaded
{
  public $fd;
  public function __construct($fd)
  {
    $this->fd = $fd; 
  }

  public function run()
  {
    $data = stream_socket_recvfrom($this->fd, 2);
    $data = unpack('c*', $data);
    if ($data[1] !== 0x05) {
      stream_socket_shutdown($this->fd, STREAM_SHUT_RDWR);
      echo '协议不正确.', PHP_EOL;
      return;
    }
    $nmethods = $data[2];
    $data = stream_socket_recvfrom($this->fd, $nmethods);
    stream_socket_sendto($this->fd, "\x05\x00");
    $data = stream_socket_recvfrom($this->fd, 4);
    $data = unpack('c*', $data);
    $addressType = $data[4];
    if ($addressType === 0x03) { // domain
      $domainLength = unpack('c', stream_socket_recvfrom($this->fd, 1))[1];
      $data = stream_socket_recvfrom($this->fd, $domainLength + 2);
      $domain = substr($data, 0, $domainLength);
      $port = unpack("n", substr($data, -2))[1];
    } else {
      stream_socket_shutdown($this->fd, STREAM_SHUT_RDWR);
      echo '请使用远程dns解析.', PHP_EOL;
    }

    stream_socket_sendto($this->fd, "\x05\x00\x00\x01\x00\x00\x00\x00\x00\x00");
    echo "{$domain}:{$port}", PHP_EOL;
    $remote = stream_socket_client("tcp://{$domain}:{$port}");
    if ($remote === false) {
      stream_socket_shutdown($this->fd, STREAM_SHUT_RDWR);
      return;
    }

    $pool = $this->worker->pipePool;

    $pipe1 = new Pipe($remote, $this->fd);
    $pipe2 = new Pipe($this->fd, $remote);

    $pool->submit($pipe1);
    $pool->submit($pipe2);
  }
}

class ProxyWorker extends Worker
{
  public $pipePool;
  public function __construct($pipePool)
  {
    $this->pipePool = $pipePool;
  }
}

$server = stream_socket_server('tcp://0.0.0.0:1080', $errno, $errstr);
if ($server === false)
  exit($errstr);

$pipePool = new Pool(200, Worker::class);
$pool = new Pool(50, 'ProxyWorker', [$pipePool]);

for( ; ; ) {
  $fd = @stream_socket_accept($server, 60);
  if ($fd === false)
    continue;
  $pool->submit(new Client($fd));
}

The above introduces 100 lines of PHP code to implement socks5 proxy server, including all aspects. I hope it will be helpful to friends who are interested in PHP tutorials.