Socket communication in php

What is the socket communication between TCP/IP and UDP in php?

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 the middle, we didn't see the Socket shadow, so where is it? You can still use graphs to speak clearly.

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.

Working Principle

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:

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: socket communication demonstration server:

 = 5) {break ;};}// echo $ buf; socket_close ($ msgsock) ;}while (true); socket_close ($ sock);?>

Save and execute this file. Run netstat-ano to check the port status. my port number is Port 1935.

If the port is in LISTENING, it indicates that it has been listened. Next, we only need to run the client program to connect.

Client:

 ";}While ($ out = socket_read ($ socket, 8192) {echo" received the server's return message! \ N "; echo" accept the following content: ", $ out;} echo" close SOCKET... \ n "; socket_close ($ socket); echo" close OK \ n ";?>

Run the server and client to return information. now the client is connected to the server.

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 write output \ 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 create socket \ 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 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.

// Bind a socket to specify the address and port $ result = socket_bind ($ socket, $ host, $ port) or die ("cocould 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 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 socket listener \ 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 incoming connection \ 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 write output \ 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 );