Getting Started with PHP Socket Programming

Let us start with a simple example---a TCP service that receives an input string, processes and returns this string to the client. Here is the corresponding code:

php Code:

<?
// 设置一些基本的变量
$host="192.168.1.99";
$port=1234;
// 设置超时时间
set_time_limit(0);
// 创建一个Socket
$socket=socket_create(AF_INET,SOCK_STREAM,0) or die("Could not create
socket\n");
//绑定Socket到端口
$result=socket_bind($socket,$host,$port) or die("Could not bind to
socket\n");
// 开始监听链接
$result=socket_listen($socket,3) or die("Could not set up socket
listener\n");
// accept incoming connections
// 另一个Socket来处理通信
$spawn=socket_accept($socket) or die("Could not accept incoming
connection\n");
// 获得客户端的输入
$input=socket_read($spawn,1024) or die("Could not read input\n");
// 清空输入字符串
$input=trim($input);
//处理客户端输入并返回结果
$output=strrev($input) ."\n";
socket_write($spawn,$output,strlen($output)) or die("Could not write
output\n");
// 关闭sockets
socket_close($spawn);
socket_close($socket);
?>

The following are each step Detailed instructions:

1. The first step is to create two variables to save the IP address and port of the server where the Socket is running. You can set it to your own server and port (this port can be a number between 1 and 65535 ), provided that this port is not in use.

<?
// 设置两个变量
$host="192.168.1.99";
$port=1234;
?>

2. You can use the set_time_out() function on the server side to ensure that PHP will not time out while waiting for the client to connect.

PHP code:

<?
// 超时时间
set_time_limit(0);
?>

3. Based on the previous ones, now it’s time to create a Socket using the socket_creat() function---this function returns a Socket handle, which will be used in all subsequent functions.

PHP code:

<?
// 创建Socket
$socket=socket_create(AF_INET,SOCK_STREAM,0) or die("Could not create socket\n");
?>

First parameter" AF_INET" is used to specify the domain name;
The second parameter "SOCK_STREM" tells the function what type of Socket will be created (in this case, TCP type)

So, if you want to create a UDP Socket, you can use the following Code:

PHP Code:

<?
// 创建 socket
$socket=socket_create(AF_INET,SOCK_DGRAM,0) or die("Could not create socket\n");
?>

4. Once a Socket handle is created, the next step is to specify or bind it to the specified address and port. This can be done through the socket_bind() function.

PHP code:

<?
// 绑定 socket to 指定地址和端口
$result=socket_bind($socket,$host,$port) or die("Could not bind to socket\n");
?>

5. After the Socket is created and bound to a port, you can start listening for external connections. PHP allows you to start a listening through the socket_listen() function, and you can specify a number. (In this case the second parameter: 3)

PHP code:

<?
// 开始监听连接
$result=socket_listen($socket,3) or die("Could not set up socket listener\n");
?>

6. By now, your server is basically doing nothing but waiting for a connection request from the client. Once a client When the connection is received, the socket_assept() function comes into play. It receives the connection request and calls another sub-Socket to handle the information between the client and the server.

PHP code:

<?
//接受请求链接
// 调用子socket 处理信息
$spawn=socket_accept($socket) or die("Could not accept incoming connection\n");
?>

This sub-socket is now It can be used for subsequent client-server communication.

7. When a connection is established, the server will wait for the client to send some input information. This information can be obtained by the socket_read() function, and It is assigned to the $input variable of PHP.

PHP code:

<?
// 读取客户端输入
$input=socket_read($spawn,1024) or die("Could not read input\n");
?>

The second parameter of socker_read is used to specify the number of bytes to be read, and you can use it to limit the size of data obtained from the client.

Note: The socket_read function will keep reading the shell client data until it encounters n, t or