如何在PHP中将接收的数据包转换为可读的十六进制字符串？

Question

<?php
    $port=4433;

    //create socket
    $sock=socket_create(AF_INET,SOCK_STREAM,0) or die("Could not create the socket\n");

    if (!socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1)) {
        echo socket_strerror(socket_last_error($sock));
        exit;
    }

    socket_bind($sock,gethostbyname(gethostname()),$port) or die("Could not bind to socket\n");
    echo "Server is ready!";
    //listening to the client
    socket_listen($sock,2);

    echo "Waiting for clients.......<br>";

    //accepting the request
    $csock=socket_accept($sock);
    echo "Client connected!";

    //read the request
    for($i=0;$i<5;$i++)
    {
        $req=socket_read($csock,4433);
        echo $req;
        $res="Thank you.....";
        //send/write the message to client socket
        socket_write($csock,$req);
    }

    //close the socket
    socket_close($csock);
?>

该计划的输出：

服务器准备就绪！等待客户.......
客户已连接！（322034287458; M01; BOT; Z04; 8991101806187113329F; 0; 00000; GPS设备已启动;; g2 4（ tX-9▒＆amp;）x＆gt;▒0▒+ h ## PuTTYPuTTY g2 4（tX。，）X`，▒0▒+ h ## PuTTYPuTTY g2 4（tX.9▒6）＆lt;▒7▒0▒* h ## PuTTYPuTTY g2 4（tX / :)▒@p0▒* h ## [root @ ip-172-31-22-221 html]＃PuTTYPuTTYPuTTYPuTTYPuTTYPuTTYPuTTYPuTTY