In-depth explanation: the socket communication principle and socket communication principle of php

In-depth explanation: the socket communication principle and socket communication principle of php

Are you familiar with TCP/IP, UDP, and Socket programming? With the development of network technology, these words are filled with our ears. So I want to ask:

1. What are TCP/IP and UDP?

2. Where is the Socket?

3. What is Socket?

4. Will you use them?

What are TCP/IP and UDP?

TCP/IP (Transmission Control Protocol/Internet Protocol) is an industrial standard Protocol set designed for WANs.

User Data Protocol (UDP) is the Protocol corresponding to TCP. It belongs to the TCP/IP protocol family.

The following figure shows the relationship between these protocols.

TCP/IP protocol families include 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 Socket shadow, so where is it? You can still use graphs to speak clearly.

The original Socket is here.

What is Socket?

Socket is an intermediate software abstraction layer for communications between the application layer and the TCP/IP protocol family. It is a group 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 are all, let the Socket organize the data to conform to the specified protocol.

Will you use them?

Our predecessors have already done a lot for us, and the communication between networks is much simpler, but after all there is still a lot of work to do. I have heard about Socket programming before and think it is a relatively advanced programming knowledge. But as long as I understand the working principle of Socket programming, the mysterious veil will be uncovered.

A scenario in life. You need to call a friend to make a dial-up call. When a friend hears the ringtone and calls the phone, you and your friend can establish a connection to speak. After the communication is over, stop the call. The scenario in life explains this working principle. Maybe the TCP/IP protocol family is born in life, which is not necessarily true.

Start with the server. The server first initializes the Socket, then binds it to the port (bind), listens to the port (listen), calls accept, and waits for the client to connect. At this time, if a client initializes a Socket and 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, the response data is sent to the client. The client reads the data and closes the connection. The interaction ends.

Socket-related functions:

Bytes ----------------------------------------------------------------------------------------------

• Socket_accept () accepts a Socket connection
• Socket_bind () binds the socket to an IP address and port.
• Socket_clear_error () clears socket errors or the final error code
• Socket_close () closes a socket Resource
• Socket_connect () starts a socket connection
• Socket_create_listen () opens a socket listener on the specified port.
• Socket_create_pair () generates a pair of identical sockets into an array.
• Socket_create () generates a socket, which is equivalent to the data structure of a socket.
• Socket_get_option () obtain the socket option
• Socket_getpeername () obtains the IP address of a remote host similar to that of a remote host.
• Socket_getsockname () gets the IP address of the local socket
• Socket_iovec_add () Add a new vector to a scattered/aggregated Array
• Socket_iovec_alloc () This function creates an iovec data structure that can send and receive read/write data.
• 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 () obtains the final error code of the current socket.
• Socket_listen () listens to all connections from the specified socket
• Socket_read () reads data of the specified length
• Socket_readv () reads data from scattered/aggregate Arrays
• Socket_recv () ends data from the socket to the cache
• Socket_recvfrom () accepts data from the specified socket. If no value is specified, the current socket is used by default.
• Socket_recvmsg () receives messages from iovec
• Socket_select () multi-path selection
• Socket_send () This function sends data to the connected socket
• Socket_sendmsg () sends a message to the socket
• Socket_sendto () sends a message to the socket of the specified address
• Socket_set_block () is set to block mode in socket
• Set the socket in socket_set_nonblock () to non-block mode.
• Socket_set_option () sets socket options
• The socket_shutdown () function allows you to close the read, write, or specified socket
• Socket_strerror () returns a detailed error of the specified error number
• Socket_write () writes data to the socket Cache
• Socket_writev () writes data to a distributed/aggregate Array

Case 1: socket Communication demonstration

Server:

<? Php // make sure that the set_time_limit (0); $ ip = '100. 0.0.1 '; $ port = 1935; /* + ------------------------------- * @ socket communication throughout the process + ------------------------------- * @ socket_create * @ socket_bind * @ socket_listen * @ socket_accept * @ socket_read * @ socket_write * @ socket_close + --------------------------------*//*---------------- the following operations are all in the manual ----------------- */if ($ sock = socket_create (AF_INET, SOCK_STREAM, SOL _ TCP) <0) {echo "socket_create () failed because :". socket_strerror ($ sock ). "\ n";} if ($ ret = socket_bind ($ sock, $ ip, $ port) <0) {echo "socket_bind () causes of failure :". socket_strerror ($ ret ). "\ n";} if ($ ret = socket_listen ($ sock, 4) <0) {echo "socket_listen () failed because :". socket_strerror ($ ret ). "\ n" ;}$ count = 0; do {if ($ msgsock = socket_accept ($ sock) <0) {echo "socket_accept () failed: reason :". socket_strerror ($ Msgsock). "\ n"; break;} else {// sent to client $ msg = "test successful! \ N "; socket_write ($ msgsock, $ msg, strlen ($ msg); echo" test successful \ n "; $ buf = socket_read ($ msgsock, 8192 ); $ talkback = "received message: $ buf \ n"; echo $ talkback; if (++ $ count >=5) {break ;};// echo $ buf; socket_close ($ msgsock);} while (true); socket_close ($ sock);?>

This is the socket server code. Then run cmd. Note the path where your program is stored.

Not reflected. The current server-side program has started to run and the port has started to listen. Run netstat-ano to check the port status. My port number is port 1935.

Check that the port is already in the LISTENING status. Next, we only need to run the client program to connect. Code on

<? Phperror_reporting (E_ALL); set_time_limit (0); echo "


Now the client is connected to the server.
Case 2: Code details
// Set some basic variables $ host = "192.168.1.99"; $ port = 1234; // set the timeout value set_time_limit (0 ); // create a Socket $ socket = socket_create (AF_INET, SOCK_STREAM, 0) or die ("cocould not createsocket \ n "); // bind the Socket to the port $ result = socket_bind ($ socket, $ host, $ port) or die ("cocould not bind tosocket \ n "); // start listening link $ result = socket_listen ($ socket, 3) or die ("cocould not set up socketlistener \ n "); // accept incoming connections // another Socket to handle communication $ spawn = socket_accept ($ socket) or die ("cocould not accept incomingconnection \ n "); // obtain the client input $ input = socket_read ($ spawn, 1024) or die ("cocould not read input \ n "); // clear the input string $ input = trim ($ input); // process the client input and return the result $ output = strrev ($ input ). "\ n"; socket_write ($ spawn, $ output, strlen ($ output) or die ("cocould not writeoutput \ n"); // close socketssocket_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 running the Socket. you can set your own server and port (this port can be a number between 1 and 65535), provided that this port is not used.

// 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 will not time out while waiting for client connection.
// Timeout set_time_limit (0 );
3. On the basis of the above, we should use the socket_creat () function to create a Socket.-This function returns a Socket handle, which will be used in all future functions.
// Create Socket $ socket = socket_create (AF_INET, SOCK_STREAM, 0) or die ("cocould not createsocket \ n ");
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)
Therefore, if you want to create a UDP Socket, you can use the following code:
// Create socket $ socket = socket_create (AF_INET, SOCK_DGRAM, 0) or die ("cocould not createsocket \ 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.
// Bind a socket to specify the address and port $ result = socket_bind ($ socket, $ host, $ port) or die ("cocould not bind tosocket \ 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 listener using the socket_listen () function, and you can specify a number (in this example, the second parameter is 3)
// Start listening to connect $ result = socket_listen ($ socket, 3) or die ("cocould not set up socketlistener \ n ");
6. up to now, your server has not done anything except waiting for connection requests from clients. once a client connection is received, the socket_accept () function starts to take effect. It receives connection requests and calls another sub-Socket to process information between clients and servers.
// Accept request link // call the sub-socket processing information $ spawn = socket_accept ($ socket) or die ("cocould not accept incomingconnection \ n ");
This sub-socket can now be used by subsequent client-server communication.
7. after a connection is established, the server will wait for the client to send some input information, which can be obtained by the socket_read () function and assigned to the $ input variable of PHP.
// Read client input $ input = socket_read ($ spawn, 1024) or die ("cocould not read input \ n ");
The second parameter of socker_read is used to specify the number of bytes to read. You can use it to limit the size of data obtained from the client.
Note: The socket_read function reads the shell data until \ n, \ t, or \ 0 characters are met. The PHP script regards this write character as an input Terminator.
8. now the server must process the data sent from the client (in this example, only the data is input and returned to the client ). this part can be done by the socket_write () function (making it possible to send a data stream back to the client by the communication socket)
// Process client input and return data $ output = strrev ($ input ). "\ n"; socket_write ($ spawn, $ output, strlen ($ output) or die ("cocould not writeoutput \ n ");
9. Once the output is returned to the client, the parent/child socket should be terminated through the socket_close () function.
// Close socketssocket_close ($ spawn); socket_close ($ socket );
The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.