You are not unfamiliar with the words TCP/IP, UDP, and Socket programming, are you? With the development of network technology, these words are flooding our ears. Then I want to ask:
1. What are TCP/IP and UDP?
2.Where is the Socket?
3.What is Socket?
4. Can you use them?
What are TCP/IP and UDP?
TCP/IP (Transmission Control Protocol/Internet Protocol) is an industrial standard protocol set designed for wide area networks (WANs).
UDP (User Data Protocol) is a protocol corresponding to TCP. It is a member of the TCP/IP protocol suite.
Here is a diagram showing 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?
Previous generations 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 in life. If you want to call a friend, dial the number first. After the friend hears the ringing tone, he picks up the phone. At this time, you and your friend are 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() accepts a Socket connection
socket_bind() binds the socket to an IP address and port
socket_clear_error() clears socket errors or last error code
socket_close() closes a socket resource
socket_connect() starts a socket connection
socket_create_listen() opens a socket listening on the specified port
socket_create_pair() generates a pair of indistinguishable sockets into an array
socket_create() generates a socket, which is equivalent to generating a socket data structure
socket_get_option() Get socket options
socket_getpeername() Gets the IP address of a remote similar host
socket_getsockname() gets the IP address of the local socket
socket_iovec_add() adds a new vector to a scatter/aggregate array
socket_iovec_alloc() This function creates an iovec data structure that can be sent, received, read and written
socket_iovec_delete() deletes an allocated iovec
socket_iovec_fetch() returns the data of the specified iovec resource
socket_iovec_free() releases an iovec resource
socket_iovec_set() sets the new value of iovec data
socket_last_error() gets the last error code of the current socket
socket_listen() listens to all connections from the specified socket
socket_read() reads data of specified length
socket_readv() reads 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, it defaults to the current socket
socket_recvmsg() receives messages from iovec
socket_select() multiple selection
socket_send() This function sends data to the connected socket
socket_sendmsg() sends a message to socket
socket_sendto() sends a message to the socket at the specified address
socket_set_block() sets the socket to block mode
socket_set_nonblock() Set the socket to non-block mode
socket_set_option() sets socket options
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 scatter/aggregate array
Case 1: socket communication demonstration
Server side:
<?php
//确保在连接客户端时不会超时
set_time_limit(0);
$ip = '127.0.0.1';
$port = 1935;
/*
+-------------------------------
* @socket通信整个过程
+-------------------------------
* @socket_create
* @socket_bind
* @socket_listen
* @socket_accept
* @socket_read
* @socket_write
* @socket_close
+--------------------------------
*/
/*---------------- 以下操作都是手册上的 -------------------*/
if(($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 $talkback;
if(++$count >= 5){
break;
};
}
//echo $buf;
socket_close($msgsock);
} while (true);
socket_close($sock);
?>
This is the server-side code of the socket. Then run cmd, pay attention to the storage path of your own program.
No response, 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 LISTENING state. Next we only need to run the client program to connect. Up code
<?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";
?>
Now the client has connected to the server.
Case 2: Detailed code explanation
// 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 createsocket\n");
//绑定Socket到端口
$result = socket_bind($socket, $host, $port) or die("Could not bind tosocket\n");
// 开始监听链接
$result = socket_listen($socket, 3) or die("Could not set up socketlistener\n");
// accept incoming connections
// 另一个Socket来处理通信
$spawn = socket_accept($socket) or die("Could not accept incomingconnection\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 is a detailed description of each step:
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 (the port can be a number between 1 and 65535), provided that This port is not in use.
Copy code The code is as follows:
// Set two variables
$host = "192.168.1.99";
$port = 1234;
2. You can use the set_time_out() function on the server side to ensure that PHP does not time out while waiting for the client to connect.
Copy code The code is as follows:
// Timeout
set_time_limit(0);
3. Based on the previous ones, it is now time to create a Socket using the socket_creat() function - this function returns a Socket handle, which will be used in all subsequent functions.
Copy code The code is as follows:
//Create Socket
$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die("Could not create
socketn");
The 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 (TCP type in this example)
So, if you want to create a UDP Socket, you can use the following code:
Copy code The code is as follows:
//Create socket
$socket = socket_create(AF_INET, SOCK_DGRAM, 0) or die("Could not create
socketn");
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.
Copy code The code is as follows:
// Bind socket to specified address and port
$result = socket_bind($socket, $host, $port) or die("Could not bind to
socketn");
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 example it is the Two parameters: 3)
Copy code The code is as follows:
// Start listening for connections
$result = socket_listen($socket, 3) or die("Could not set up socket
listenern");
6. Until now, your server has basically done nothing but wait for a 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 information between client and server.
Copy code The code is as follows:
//Accept request link
// Call subsocket to process information
$spawn = socket_accept($socket) or die("Could not accept incoming
connectionn");
This subsocket can now 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 assigned to the $input variable of PHP.
Copy code The code is as follows:
//Read client input
$input = socket_read($spawn, 1024) or die("Could not read inputn");
?>
The second parameter of socker_read is used to specify the number of bytes to be read. 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
8. Now the server must process the data sent by the client (in this example, the processing only includes the input and return of data to the client). This part can be completed by the socket_write() function (so that by It is possible for the communication socket to send back a data stream to the client)
Copy code The code is as follows:
// Process client input and return data
$output = strrev($input) . "n";
socket_write($spawn, $output, strlen ($output)) or die("Could not write
outputn");
9. Once the output is returned to the client, the parent/child socket should be terminated through the socket_close() function
Copy code The code is as follows:
// Close sockets
socket_close($spawn);
socket_close($socket);
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