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php实现websocket实时消息推送

php实现websocket实时消息推送

作者: 金星show | 来源:发表于2019-01-22 10:44 被阅读70次

    一、socket协议的简介

    WebSocket是什么,有什么优点

    WebSocket是一个持久化的协议,这是相对于http非持久化来说的。应用层协议

    举个简单的例子,http1.0的生命周期是以request作为界定的,也就是一个request,一个response,对于http来说,本次client与server的会话到此结束;而在http1.1中,稍微有所改进,即添加了keep-alive,也就是在一个http连接中可以进行多个request请求和多个response接受操作。然而在实时通信中,并没有多大的作用,http只能由client发起请求,server才能返回信息,即server不能主动向client推送信息,无法满足实时通信的要求。而WebSocket可以进行持久化连接,即client只需进行一次握手,成功后即可持续进行数据通信,值得关注的是WebSocket实现client与server之间全双工通信,即server端有数据更新时可以主动推送给client端。

    二、介绍client与server之间的socket连接原理

    1、下面是一个演示client和server之间建立WebSocket连接时握手部分

    image

    2、client与server建立socket时握手的会话内容,即request与response

    a、client建立WebSocket时向服务器端请求的信息

    GET /chat HTTP/1.1
      Host: server.example.com
      Upgrade: websocket //告诉服务器现在发送的是WebSocket协议
      Connection: Upgrade
      Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw== //是一个Base64 encode的值,这个是浏览器随机生成的,用于验证服务器端返回数据是否是WebSocket助理
      Sec-WebSocket-Protocol: chat, superchat
      Sec-WebSocket-Version: 13
      Origin: http://example.com

    b、服务器获取到client请求的信息后,根据WebSocket协议对数据进行处理并返回,其中要对Sec-WebSocket-Key进行加密等操作

    HTTP/1.1 101 Switching Protocols
      Upgrade: websocket //依然是固定的,告诉客户端即将升级的是Websocket协议,而不是mozillasocket,lurnarsocket或者shitsocket
      Connection: Upgrade
      Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk= //这个则是经过服务器确认,并且加密过后的 Sec-WebSocket-Key,也就是client要求建立WebSocket验证的凭证
      Sec-WebSocket-Protocol: chat

    3、socket建立连接原理图:

    image

    三、PHP中建立websocket的过程讲解
    SocketService.php:

    <?php
    class SocketService
    {
      private $address = '0.0.0.0';
      private $port = 8083;
      private $_sockets;
      public function __construct($address = '', $port='')
      {
          if(!empty($address)){
            $this->address = $address;
          }
          if(!empty($port)) {
            $this->port = $port;
          }
      }
    
      public function service(){
        //获取tcp协议号码。
        $tcp = getprotobyname("tcp");
        $sock = socket_create(AF_INET, SOCK_STREAM, $tcp);
        socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1);
        if($sock < 0)
        {
          throw new Exception("failed to create socket: ".socket_strerror($sock)."\n");
        }
        socket_bind($sock, $this->address, $this->port);
        socket_listen($sock, $this->port);
        echo "listen on $this->address $this->port ... \n";
        $this->_sockets = $sock;
      }
    
      public function run(){
        $this->service();
        $clients[] = $this->_sockets;
        while (true){
          $changes = $clients;
          $write = NULL;
          $except = NULL;
    //当select处于等待时,两个客户端中甲先发数据来,则socket_select会在$changes中保留甲的socket并往下运行,另一个客户端的socket就被丢弃了,所以再次循环时,变成只监听甲了,这个可以在新循环中把所有链接的客户端socket再次加进$changes中,则可以避免本程序的这个逻辑错误
          /** socket_select是阻塞,有数据请求才处理,否则一直阻塞
           * 此处$changes会读取到当前活动的连接
           * 比如执行socket_select前的数据如下(描述socket的资源ID):
           * $socket = Resource id #4
           * $changes = Array
           *       (
           *           [0] => Resource id #5 //客户端1
           *           [1] => Resource id #4 //server绑定的端口的socket资源
           *       )
           * 调用socket_select之后,此时有两种情况:
           * 情况一:如果是新客户端2连接,那么 $changes = array([1] => Resource id #4),此时用于接收新客户端2连接
           * 情况二:如果是客户端1(Resource id #5)发送消息,那么$changes = array([1] => Resource id #5),用户接收客户端1的数据
           *
           * 通过以上的描述可以看出,socket_select有两个作用,这也是实现了IO复用
           * 1、新客户端来了,通过 Resource id #4 介绍新连接,如情况一
           * 2、已有连接发送数据,那么实时切换到当前连接,接收数据,如情况二*/
          socket_select($changes, $write, $except, NULL);
          foreach ($changes as $key => $_sock){
            if($this->_sockets == $_sock){ //判断是不是新接入的socket
              if(($newClient = socket_accept($_sock)) === false){
                die('failed to accept socket: '.socket_strerror($_sock)."\n");
              }
              $line = trim(socket_read($newClient, 1024));
              if($line === false){
                 socket_shutdown($newClient);
                 socket_close($newClient);
                 continue;
              }  
              $this->handshaking($newClient, $line);
              //获取client ip
              socket_getpeername ($newClient, $ip);
              $clients[$ip] = $newClient;
              echo "Client ip:{$ip}  \n";
              echo "Client msg:{$line} \n";
            } else {
              $byte = socket_recv($_sock, $buffer, 2048, 0);
              if($byte < 7) continue;
              $msg = $this->message($buffer);
              //在这里业务代码
              echo "{$key} clinet msg:",$msg,"\n";
              fwrite(STDOUT, 'Please input a argument:');
              $response = trim(fgets(STDIN));
              $this->send($_sock, $response);
              echo "{$key} response to Client:".$response,"\n";
            }
          }
        }
      }
    
      /**
       * 握手处理
       * @param $newClient socket
       * @return int 接收到的信息
       */
      public function handshaking($newClient, $line){
    
        $headers = array();
        $lines = preg_split("/\r\n/", $line);
        foreach($lines as $line)
        {
          $line = rtrim($line);
          if(preg_match('/^(\S+): (.*)$/', $line, $matches))
          {
            $headers[$matches[1]] = $matches[2];
          }
        }
        $secKey = $headers['Sec-WebSocket-Key'];
        $secAccept = base64_encode(pack('H*', sha1($secKey . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11')));
        $upgrade = "HTTP/1.1 101 Web Socket Protocol Handshake\r\n" .
          "Upgrade: websocket\r\n" .
          "Connection: Upgrade\r\n" .
          "WebSocket-Origin: $this->address\r\n" .
          "WebSocket-Location: ws://$this->address:$this->port/websocket/websocket\r\n".
          "Sec-WebSocket-Accept:$secAccept\r\n\r\n";
        return socket_write($newClient, $upgrade, strlen($upgrade));
      }
    
      /**
       * 解析接收数据
       * @param $buffer
       * @return null|string
       */
      public function message($buffer){
        $len = $masks = $data = $decoded = null;
        $len = ord($buffer[1]) & 127;
        if ($len === 126) {
          $masks = substr($buffer, 4, 4);
          $data = substr($buffer, 8);
        } else if ($len === 127) {
          $masks = substr($buffer, 10, 4);
          $data = substr($buffer, 14);
        } else {
          $masks = substr($buffer, 2, 4);
          $data = substr($buffer, 6);
        }
        for ($index = 0; $index < strlen($data); $index++) {
          $decoded .= $data[$index] ^ $masks[$index % 4];
        }
        return $decoded;
      }
    
      /**
       * 发送数据
       * @param $newClinet 新接入的socket
       * @param $msg  要发送的数据
       * @return int|string
       */
      public function send($newClinet, $msg){
        $msg = $this->frame($msg);
        socket_write($newClinet, $msg, strlen($msg));
      }
    
      public function frame($s) {
        $a = str_split($s, 125);
        if (count($a) == 1) {
          return "\x81" . chr(strlen($a[0])) . $a[0];
        }
        $ns = "";
        foreach ($a as $o) {
          $ns .= "\x81" . chr(strlen($o)) . $o;
        }
        return $ns;
      }
    
      /**
       * 关闭socket
       */
      public function close(){
        return socket_close($this->_sockets);
      }
    }
    
    $sock = new SocketService();
    $sock->run();
    

    web.html:

    <!doctype html>
    <html lang="en">
     <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width,initial-scale=1, maximum-scale=1, user-scalable=no">
     <title>websocket</title>
     </head>
     <body>
     <input id="text" value="">
     <input type="submit" value="send" onclick="start()">
     <input type="submit" value="close" onclick="close()">
    <div id="msg"></div>
     <script>
     /**
    webSocket.readyState
     0:未连接
     1:连接成功,可通讯
     2:正在关闭
     3:连接已关闭或无法打开
    */
    
      //创建一个webSocket 实例
      var webSocket = new WebSocket("ws://192.168.31.152:8083");
    
    
      webSocket.onerror = function (event){
        onError(event);
      };
    
      // 打开websocket
      webSocket.onopen = function (event){
        onOpen(event);
      };
    
      //监听消息
      webSocket.onmessage = function (event){
        onMessage(event);
      };
    
    
      webSocket.onclose = function (event){  //服务端关闭后 触发
        onClose(event);
      }
    
      //关闭监听websocket
      function onError(event){
        document.getElementById("msg").innerHTML = "<p>close</p>";
        console.log("error"+event.data);
      };
    
      function onOpen(event){
        console.log("open:"+sockState());
        document.getElementById("msg").innerHTML = "<p>Connect to Service</p>";
      };
      function onMessage(event){
        console.log("onMessage");
        document.getElementById("msg").innerHTML += "<p>response:"+event.data+"</p>"
      };
    
      function onClose(event){
        document.getElementById("msg").innerHTML = "<p>close</p>";
        console.log("close:"+sockState());
        webSocket.close();
      }
    
      function sockState(){
        var status = ['未连接','连接成功,可通讯','正在关闭','连接已关闭或无法打开'];
          return status[webSocket.readyState];
      }
    
    
     function start(event){
        console.log(webSocket);
        var msg = document.getElementById('text').value;
        document.getElementById('text').value = '';
        console.log("send:"+sockState());
        console.log("msg="+msg);
        webSocket.send("msg="+msg);
        document.getElementById("msg").innerHTML += "<p>request"+msg+"</p>"
      };
    
      function close(event){
        webSocket.close();
      }
     </script>
     </body>
    </html>
    

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