A brief introduction to the socket communication principle of PHP

You are not familiar with the words TCP/IP, UDP, Socketprogramming, right? With the development of network technology, these words are flooding our ears. So I want to ask:
1. What are TCP/IP, UDP?
2. Where is Socket?
3. What is Socket?
4. Will you use them?
What are TCP/IP, UDP?

                                                                                                                                                           TCP/IP (Transmission Control Protocol/Internet Protocol) ) designed.                 UDP (User Data Protocol
, User Datagram Protocol) is the protocol corresponding to TCP. It is a member of the TCP/IP protocol family.表 There is a picture here that shows the relationship between these protocols. The TCP/IP protocol suite includes the transport layer, network layer, and link layer. Now you know the relationship between TCP/IP and UDP. Where is the Socket? 　In Figure 1, we don’t see the shadow of Socket, so where is it? Let’s let pictures speak for themselves.

It turns out that the Socket is here. What is Socket?

　 Socket is an intermediate software abstraction layer for communication between the application layer and the TCP/IP protocol family. It is a set of interfaces. In the design mode, Socket is actually a facade mode, which hides the complex TCP/IP protocol family behind the Socket interface. For users, a set of simple interfaces is all, allowing Socket to organize data to meet the specified requirements. protocol.

Can you use them? 　Predecessors have done a lot for us, and communication between networks has become much simpler, but after all, there is still a lot of work to be done. When I heard about Socket programming before, I thought it was relatively advanced programming knowledge, but as long as we understand the working principle of Socket programming, the mystery will be lifted. 　A scene from life. If you want to call a friend, dial the number first. The friend will pick up the phone after hearing the ringing tone. At this time, you and your friend will be connected and you can talk. When the communication is over, hang up the phone to end the conversation. Scenes in life explain how this works. Maybe the TCP/IP protocol family was born in life, but this is not necessarily the case.

Let’s start with the server side. The server first initializes the Socket, then binds to the port, listens to the port, calls accept to block, and waits for the client to connect. At this time, if a client initializes a Socket and then connects to the server (connect), if the connection is successful, the connection between the client and the server is established. The client sends a data request, the server receives the request and processes the request, then sends the response data to the client, the client reads the data, and finally closes the connection, and the interaction ends.

socket related functions:
------------------------------------------------- -------------------------------------------------- -
socket_accept() Accept a Socket connection
socket_bind() Bind the socket to an IP address and port
socket_clear_error() Clear the socket error or last error code
socket_close() Close a socket resource
socket_connect() Start A socket connection
socket_create_listen() opens a socket listening on the specified port
socket_create_pair() generates a pair of undifferentiated sockets into an array
socket_create() generates a socket, which is equivalent to generating a socket data structure
socket_get_option() obtains Socket options
socket_getpeername() Get the ip address of a remote similar host
socket_getsockname() Get the ip address of the local socket
socket_iovec_add() Add a new vector to a scatter/aggregate array
socket_iovec_alloc() This function creates a socket that can send and receive Read and write iovec data structure
socket_iovec_delete() Delete an allocated iovec
socket_iovec_fetch() Return the data of the specified iovec resource
socket_iovec_free() Release an iovec resource
socket_iovec_set() Set the new value of iovec data
socket_last_error() Get The last error code of the current socket
socket_listen() listens to all connections from the specified socket
socket_read() reads the data of the specified length
socket_readv() reads the data from the scatter/aggregate array
socket_recv() ends the data from the socket To the cache
socket_recvfrom() accepts data from the specified socket, if not specified, the current socket is defaulted
socket_recvmsg() Receives messages from iovec
socket_select() Multiple selection
socket_send() This function sends data to the connected socket
socket_sendmsg() Send a message to the socket
socket_sendto() Send a message to the socket at the specified address
socket_set_block() Set the socket to block mode
socket_set_nonblock() Set the socket to non-block mode
socket_set_option() Set the socket option
socket_shutdown( ) This function allows you to close reading, writing, or the specified socket
socket_strerror() returns the detailed error with the specified error number
socket_write() writes data to the socket cache
socket_writev() writes data to the scatter/aggregate array

Case 1: Socket communication demonstration

Server side:

<span><?php
//确保在连接客户端时不会超时
set_time_limit(0);

$ip = '127.0.0.1';
$port = 1935;

/*
 &#43;-------------------------------
 *    @socket通信整个过程
 &#43;-------------------------------
 *    @socket_create
 *    @socket_bind
 *    @socket_listen
 *    @socket_accept
 *    @socket_read
 *    @socket_write
 *    @socket_close
 &#43;--------------------------------
 */

/*----------------    以下操作都是手册上的    -------------------*/
if(($sock = socket_create(AF_INET,SOCK_STREAM,SOL_TCP)) < 0) {
    echo "socket_create() 失败的原因是:".socket_strerror($sock)."\n";
}

if(($ret = socket_bind($sock,$ip,$port)) < 0) {
    echo "socket_bind() 失败的原因是:".socket_strerror($ret)."\n";
}

if(($ret = socket_listen($sock,4)) < 0) {
    echo "socket_listen() 失败的原因是:".socket_strerror($ret)."\n";
}

$count = 0;

do {
    if (($msgsock = socket_accept($sock)) < 0) {
        echo "socket_accept() failed: reason: " . socket_strerror($msgsock) . "\n";
        break;
    } else {
        
        //发到客户端
        $msg ="测试成功！\n";
        socket_write($msgsock, $msg, strlen($msg));
        
        echo "测试成功了啊\n";
        $buf = socket_read($msgsock,8192);
        
        
        $talkback = "收到的信息:$buf\n";
        echo $talkback;
        
        if(&#43;&#43;$count >= 5){
            break;
        };
        
    
    }
    //echo $buf;
    socket_close($msgsock);

} while (true);

socket_close($sock);
?></span>

This is the server-side code of the socket. Then run cmd, pay attention to the storage path of your own program.

No reflection, now the server program has started running and the port has started listening. Run netstat -ano to check the port status. Mine is port 1935

Look, the port is already in the LISTENING state. Next we only need to run the client program to connect. Up code

<span><?php
error_reporting(E_ALL);
set_time_limit(0);
echo "<h2>TCP/IP Connection</h2>\n";

$port = 1935;
$ip = "127.0.0.1";

/*
 +-------------------------------
 *    @socket连接整个过程
 +-------------------------------
 *    @socket_create
 *    @socket_connect
 *    @socket_write
 *    @socket_read
 *    @socket_close
 +--------------------------------
 */

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket < 0) {
    echo "socket_create() failed: reason: " . socket_strerror($socket) . "\n";
}else {
    echo "OK.\n";
}

echo "试图连接 '$ip' 端口 '$port'...\n";
$result = socket_connect($socket, $ip, $port);
if ($result < 0) {
    echo "socket_connect() failed.\nReason: ($result) " . socket_strerror($result) . "\n";
}else {
    echo "连接OK\n";
}

$in = "Ho\r\n";
$in .= "first blood\r\n";
$out = '';

if(!socket_write($socket, $in, strlen($in))) {
    echo "socket_write() failed: reason: " . socket_strerror($socket) . "\n";
}else {
    echo "发送到服务器信息成功！\n";
    echo "发送的内容为:<font color='red'>$in</font> <br>";
}

while($out = socket_read($socket, 8192)) {
    echo "接收服务器回传信息成功！\n";
    echo "接受的内容为:",$out;
}


echo "关闭SOCKET...\n";
socket_close($socket);
echo "关闭OK\n";
?></span>

Now the client has connected to the server.

Case 2: Detailed code explanation

// Set some basic variables
$host = "192.168.1.99";
$port = 1234 ;
/ / Set timeout
set_time_limit(0);
// Create a Socket
$socket = socket_create (AF_INET, SOCK_STREAM, 0) or die("Could not createocketn");
//Bind Socket to port
$result = socket_bind( $socket, $host, $port) or die("Could not bind tosocketn");
// Start monitoring the link
$ result = socket_listen($socket, 3) or die("Could not set up socketlistenern");
// accept incoming connections
// Another Socket to handle communication
$spawn = socket_accept($socket) or die("Could not accept incomingconnectionn");
/ / Get input from the client
$input = socket_read($spawn, 1024) or die("Could not read inputn" );
//Clear the input string
$input =trim($input);
//Process client input and return the result
$output = strrev($input) . , $output,
strlen ($output)) or die("Could not writeoutputn");//Close socketssocket_close( $spawn

);socket_close
($socket);The following is a detailed description of each step:For example:
website design company,design company , Internet marketing,
Internet promotion,Internet optimizationwebsite promotion,website optimization,website operation, etc. are all produced similarly. steps. 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 as your own website designserver and building websiteport ( This port can be a number between 1 and 65535), provided that this port is not in use.
[Copy to clipboard]PHP CODE:

// Set two Variable

$host =

"192.168.1.99";

$port <span>= <br></span>1234<span></span>;<span></span><span></span> <span><br></span><span></span>2. You can use set_time_out on the server side ()<span></span> function<span></span> to ensure that PHP will not time out while waiting for the client to connect.<span></span><br>Building a website

[Copy to clipboard] PHP CODE:

// Timeout time

set_time_limit(

0);

<span><br></span><span>3. Based on the previous, it’s time to use sock et_creat() function creates A Socket - This function returns a Socket handle, which will be used in all future functions for building websites.<h5 id="span-PHP-CODE-span"><span>PHP CODE:</span></h5> <p><span><code><span>//Create Socket<br></span><span>$socket </span><span>= </span><span>socket_create</span><span>(</span><span>AF_INET</span><span>, </span><span>SOCK_STREAM</span><span>, </span><span>0</span><span>) or die( </span><span>"Could not create<br>socketn"</span><span>);</span><br>

The first parameter "AF_INET" is used to specify the domain name;
The second parameter "SOCK_STREM" tells the function what to create class type Socket (in this case TCP class type)
So, if you want to create a UDP Socket, you can use the following code:

[Copy to clipboard]

PHP CODE:

<span>// Create socket<br></span><span>$socket </span><span>= </span><span>socket_create</span><span>(</span> <span>AF_INET</span><span>, </span><span>SOCK_DGRAM</span><span>, </span> <span>0</span><span>) or die(</span><span>"Could not create<br>socketn"</span><span>);</span><br>

4. Once a Socket handle is created, the next step is to specify or bind it to the specified Website construction companyaddress and Enterprise website constructionport. This can be done through the socket_bind() function.

[Copy to clipboard]

PHP CODE:

<span>// Bind socket to specified address and port <br></span><span>$result </span><span>= </span><span>socket_bind</span><span>(</span><span>$socket</span><span>, </span> <span>$host</span><span>, </span><span>$port </span><span>) or die(</span><span>"Could not bind to<br>socketn"</span><span>);</span><br>

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

[Copy to clipboard]

PHP CODE:

<span>// Start listening for connections<br></span><span>$result </span><span>= </span><span>socket_listen</span><span>(</span> <span>$socket</span><span>, </span><span>3</span> <span>) or die(</span><span>"Could not set up socket<br>listenern"</span><span>);</span><br>

6. Until now, your server has basically done nothing except waiting for the connection request from the client. .Once a client connection is received, the socket_accept() function comes into play. It receives the connection request and calls another sub-Socket to handle the client-website productioninformation between servers.

[Copy to clipboard]

PHP CODE:

<span>//Accept request link<br>// Call subsocket to process information<br></span><span>$spawn </span> <span>= </span><span>socket_accept</span> <span>(</span><span>$socket</span><span>) or die(</span><span>"Could not accept incoming<br>connectionn"</span><span>);</span><br>

This sub-socket can now be used by subsequent Webpage Used to make 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 assigned to the $input variable of PHP.[Copy to clipboard]PHP CODE:

//Read client input

$input =

socket_read(

$spawn, <span><br>1024</span><span>) or die(</span><span>"Could not read inputn"</span><span>) ;</span>?&<span></span>gt<span></span>;<span></span><span></span><span>The second parameter of <p><span><span><span>socker_read is used to specify the number of bytes to be read. You can use it to limit the size of </span><span>data</span><span> obtained from the client. </span><br><span>Note: The socket_read function will always read the shell The client <span>APP</span><span> develops </span>data until it meets n,t or </span> The above has introduced a brief introduction to the socket communication principle of PHP, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials. <br> <span> <span></span></span></span></span></p></span>