PHP+Socket series realizes data transmission between client and server

This article brings you relevant knowledge about php socket. It mainly introduces what is socket? How does php socket realize client-server data transmission? Friends who are interested can take a look below. I hope it will be helpful to everyone.

Socket introduction

To achieve communication between network processes, almost all applications use sockets. Sockets are the intermediate communication between the application layer and the TCP/IP protocol family. Abstraction layer, which 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 the user, a set of simple interfaces is all, allowing the socket to organize the data to comply with the specified Protocol

The original meaning of socket in English is "hole" or "socket". It is also commonly called "socket" and is used to describe IP addresses and ports. It is a The handle of the communication chain can be used to implement communication between different virtual machines or different computers.

Three processes of socket link

• Server listening: IP port number

• Client request: Send to service End IP and port connection request

• Link confirmation: The server socket listens or receives the client socket connection request, and it will create a new process. Send the server's socket description to the client in response to the client's request. Once the client confirms this description, the connection is established. The server's socket continues to be in the listening state and continues to accept connection requests from other client sockets.

php implements socket

If you need to use socket in php, you need to add-- when compiling php enable-socketsconfiguration item to enable, you can use thephp -m|grep socketscommand to check the enabling status. For the specific compilation process, please refer tothis article

Quick Experience

The simplified codes for the server and client are as follows. After running, the server will block and wait for the client to connect. The client will ask for input content on the console. After input, the information will be displayed in the service The client prints, and the client displays the content converted to uppercase. This example server and client run on the same server:

Server listening

      
Client connection
      

      
Syntax explanation
      
socket_create
      
socket_create(int $domain,int $type, int $protocol): resource|false
      
Create and return a socket resource , also usually called a communication node. A typical socket consists of at least 2 sockets, one running on the client side and one running on the server side.
      
Parameters:
      

       
##domainSpecifies what protocol the current socket uses. The available protocols are as follows:
        

         
            Domain
            Description
            
            AF_INET
            IPv4 network protocol, both TCP and UDP are available Use this protocol
            
            AF_INET6
            IPv6 network protocol, both TCP and UDP can use this protocol
            
            AF_UNIX
            Local communication protocol, IPC with high performance and low cost
            
        
       
##type
User specifies the current set Type used by the interface
        

         
protocol设置指定 domain 套接字下的具体协议，如果所需协议是 TCP 或者 UDP，可以直接使用常量SOL_TCP或SOL_UDP，这个参数的具体值可通过getprotobyname()函数获取
         
返回值
         
socket_create()正确时返回一个套接字资源，失败时返回false。可以调用socket_last_error()获取错误码，错误码可以通过socket_strerror(int $err_no)转换为文字的错误说明。
         
socket_bind
         
socket_bind(resource $socket, string $address [, int $port]): bool
         
绑定一个地址与端口到套接字
         
参数：
         

          
socket使用socket_create()创建的套接字资源
          
address
如果套接字是AF_INET族，那么address必须是一个四点法的 IP 地址，例如127.0.0.1、0.0.0.0
如果套接字是AF_UNIX族，那么address是 Unix 套接字一部分（例如/tmp/my.sock）
          
port（可选）
该参数仅用于使用AF_INET族时，指定当前套接字监听的端口号
         
         
返回值：
         
绑定成功返回true，失败时则返回false，同socket_create，在绑定失败时可以调用socket_last_error()获取错误码，错误码可以通过socket_strerror(int $err_no)转换为文字的错误说明。
         
socket_listen
         
socket_listen(resource $socket [, int $backlog]): bool
         
在使用socket_create()创建套接字并使用socket_bind()将其绑定到名称之后，可能会告诉它侦听套接字上的传入连接。该函数仅适用于SOCK_STREAM或SOCK_SEQPACKET类型的套接字。
         
参数：
         

          
socket使用socket_create()创建的套接字资源
          
backlog最大数量的积压传入连接将排队等待处理，如果连接请求到达时队列已满，则客户端可能会收到指示为ECONNREFUSED的错误。或者，如果底层协议支持重传，则可能会忽略该请求，以便重试可能会成功。
         
         
返回值：
         
绑定成功返回true，失败时则返回false，可以调用socket_last_error()获取错误码，错误码可以通过socket_strerror(int $err_no)转换为文字的错误说明。
         
socket_accept
         
socket_accept(resource $socket): resource|false
         
当有新的客户端连接时，返回一个新的 socket 资源以用于与客户端通信，如有多个连接排队，则返回第一个连接，相反如果没有待处理的连接，该函数会默认阻塞当前进程，直至新的客户端连接、断开
         
参数：
         

          
socket使用socket_create()创建的套接字资源
         
         
返回值：
         
成功时返回一个新的套接字资源，错误时返回false，可以调用socket_last_error()获取错误码，错误码可以通过socket_strerror(int $err_no)转换为文字的错误说明。
         
socket_connect
         
socket_connect(resource $socket, string $address [, int $port = null]): bool
         
使用套接字实例发起到address的连接
         
参数：
         

          
socket该参数必须是由socket_create()创建的socket实例
          
address
如果套接字是AF_INET族，那么address必须是一个四点法的 IP 地址，例如127.0.0.1如果支持 IPv6 并且套接字是AF_INET6，那么address也可以是一个有效的 IPv6 地址（例如::1）
如果套接字是AF_UNIX族，那么address是 Unix 套接字一部分（例如/tmp/my.sock）
         
         
返回值：
         
成功时返回true， 或者在失败时返回false
         
socket_write
         
socket_write(resource $socket, string $data [, int $length = null]): int|false
         
传输数据至指定套接字
         
参数：
         

          
socket使用socket_create()或socket_accept()创建的套接字资源
          
data要发送的内容
          
length（可选）
可以指定发送套接字的替代字节长度。如果这个长度大于实际发送内容的长度，它将被静默地截断为实际发送内容的长度。
         
         
返回值：
         
成功时返回成功发送的字节数，或者在失败时返回false，可以调用socket_last_error()与socket_strerror(int $err_no)获取具体错误信息
         
socket_read
         
socket_read(resource $socket, int $length, int $mode = PHP_BINARY_READ): string|false
         
从套接字资源内读取数据
         
参数：
         

          
socket使用socket_create()或socket_accept()创建的套接字资源（服务端为socket_accept()客户端为socket_create()）
          
length指定最大能够读取的字节数。否则您可以使用\r、\n、\0结束读取（根据mode参数设置）
          
mode（可选）
PHP_BINARY_READ（默认）- 使用系统的recv()函数。二进制安全地读取数据。
PHP_NORMAL_READ- 读取到\n、\r时停止。
         
         
返回值：
         
socket_read()返回一个字符串，表示接收到的数据。如果发生了错误（包括远程主机关闭了连接），则返回false，可以调用socket_last_error()与socket_strerror(int $err_no)获取具体错误信息
         
socket_close
         
socket_close(resource $socket): void
         
关闭并销毁一个套接字资源
         
参数：
         

          
socket使用socket_create()或socket_accept()创建的套接字资源
         
         
返回值：
         
无
         
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           type
           
           SOCK_STREAM
           SOCK_DGRAM
           SOCK_SEQPACKET
           SOCK_RAW
           SOCK_RDM
           

          

            
Description
            

           
          
          

            
Sequential, reliable, full-duplex, link-based byte stream, supporting data transfer flow control mechanism. The TCP protocol is based on this streaming socket.
            

           

            
Support for data messages (connectionless, unreliable, fixed maximum length) UDP protocol is based on this message socket
            

           

            
Sequential, reliable, full-duplex, connection-oriented, fixed maximum length data communication, the data end reads the entire data segment by receiving each data segment Packet
            

           

            
Read the original network protocol. This special socket can be used to manually build any type of protocol. Generally, this socket is used To implement ICMP request
            

           

            
Reliable data layer, but the arrival order is not guaranteed. General operating systems do not implement this function