Detailed explanation of the steps to implement TCP server and client functions through PHP programming

<?php
//确保在连接客户端时不会超时
set_time_limit(0);
//设置IP和端口号
$address = "127.0.0.1";
$port = 3046;
/**
 * 创建一个SOCKET
 * AF_INET=是ipv4 如果用ipv6，则参数为 AF_INET6
 * SOCK_STREAM为socket的tcp类型，如果是UDP则使用SOCK_DGRAM
*/
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP) or die("socket_create() fail:" . socket_strerror(socket_last_error()) . "/n");
//阻塞模式
socket_set_block($sock) or die("socket_set_block() fail:" . socket_strerror(socket_last_error()) . "/n");
//绑定到socket端口
$result = socket_bind($sock, $address, $port) or die("socket_bind() fail:" . socket_strerror(socket_last_error()) . "/n");
//开始监听
$result = socket_listen($sock, 4) or die("socket_listen() fail:" . socket_strerror(socket_last_error()) . "/n");
echo "OK\nBinding the socket on $address:$port ... ";
echo "OK\nNow ready to accept connections.\nListening on the socket ... \n";
do { // never stop the daemon
  //它接收连接请求并调用一个子连接Socket来处理客户端和服务器间的信息
  $msgsock = socket_accept($sock) or die("socket_accept() failed: reason: " . socket_strerror(socket_last_error()) . "/n");
  while(1){
    //读取客户端数据
    echo "Read client data \n";
    //socket_read函数会一直读取客户端数据,直到遇见\n,\t或者\0字符.PHP脚本把这写字符看做是输入的结束符.
    $buf = socket_read($msgsock, 8192);
    echo "Received msg: $buf  \n";
    if($buf == "bye"){
      //接收到结束消息，关闭连接，等待下一个连接
      socket_close($msgsock);
      continue;
    }
    //数据传送 向客户端写入返回结果
    $msg = "welcome \n";
    socket_write($msgsock, $msg, strlen($msg)) or die("socket_write() failed: reason: " . socket_strerror(socket_last_error()) ."/n");
  }
} while (true);
socket_close($sock);
?>

<?php
set_time_limit(0);
$host = "127.0.0.1";
$port = 3046;
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)or die("Could not create socket\n");
$connection = socket_connect($socket, $host, $port) or die("Could not connet server\n");
socket_write($socket, "hello socket") or die("Write failed\n");
while ($buff = socket_read($socket, 1024, PHP_NORMAL_READ)) {
  echo("Response was:" . $buff . "\n");
  echo("input what you want to say to the server:\n");
  $text = fgets(STDIN);
  socket_write($socket, $text);
}
socket_close($socket);
?>