PHP简单实现socks5代理服务器

当然，由于php（不算swoole扩展）本身不擅长做网络服务端编程，所以这个代理，只是个玩具，离日常使用有点距离。

写的过程中发现php多线程还是难的。比如我开始想每个连接新建一个线程。但这个线程得保存起来（比如保存到数组） 要放到$clients这个数组里，不然，你试试(curl -L一个要301的地址)就知道出现什么情况了。

那，以下就是使用线程池来实现的代理，按道理讲，退出时池要shutdown()，监听socket也要shutdown的，但百行代码，就不勉强了，随着ctrl + c，就让操作系统来回收资源吧。

php不擅长网络编程体现在哪里呢？首先我用的是stream_socket_XXX相关的函数，为啥不用socket扩展呢？因为socket扩展有问题。而stream_set_timeout对stream_socket_recvfrom这些高级操作，不起作用。 而这些，在写代理时都需要考虑的。比如连接远程目标服务器时，没有超时控制，很容易就线程池跑满了。

测试的话，使用curl即可，对了，目前只支持远程dns解析，为啥呢？因为这个玩具后期可是要实现禾斗学上网的哟： curl --socks5-hostname 127.0.0.1:1080

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, "x05x00");
    $data = stream_socket_recvfrom($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($this->fd, "x05x00x00x01x00x00x00x00x00x00");
    echo "{$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));
}