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In PHP, socket_getsockname and socket_cmsg_space are two commonly used functions when programming networks using sockets. They help developers get detailed information about sockets, especially when handling network communications. This article will introduce how to combine these two functions to obtain socket information.
The socket_getsockname function is used to obtain the local address information associated with a connected socket. This is very important for getting the connection status between the current host and the remote host. The function is defined as follows:
int socket_getsockname ( int $socket , string &$address , int &$port )
$socket : is a valid socket resource.
$address : Returns the socket's local address.
$port : Returns the socket's port number.
The socket_cmsg_space function is used to return the space required for the current message control data (CMSG). Its purpose is to calculate the size of message control data for a specific protocol in order to correctly allocate space for control messages.
int socket_cmsg_space ( int $level , int $type )
$level : Specifies the protocol layer, usually SOL_SOCKET .
$type : Controls message type, such as SO_RCVBUF .
To better understand how these two functions are used in combination, here is a simple PHP sample code that shows how to use socket_getsockname and socket_cmsg_space to get socket information.
<?php
// Create a TCP Sockets
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "Sockets创建失败: " . socket_strerror(socket_last_error()) . "\n";
exit();
}
// 绑定Sockets
$address = '127.0.0.1';
$port = 8080;
if (socket_bind($socket, $address, $port) === false) {
echo "Sockets绑定失败: " . socket_strerror(socket_last_error()) . "\n";
exit();
}
// 获取Sockets的本地地址和端口
if (socket_getsockname($socket, $localAddress, $localPort) === false) {
echo "获取Sockets信息失败: " . socket_strerror(socket_last_error()) . "\n";
} else {
echo "Sockets本地地址: $localAddress\n";
echo "Sockets本地端口: $localPort\n";
}
// Get control message space
$level = SOL_SOCKET;
$type = SO_RCVBUF;
$space = socket_cmsg_space($level, $type);
echo "Control the message space size: $space\n";
// 关闭Sockets
socket_close($socket);
?>
Create socket : First, create a TCP socket through socket_create . AF_INET means using IPv4 protocol, SOCK_STREAM means using stream sockets, and SOL_TCP is the transport layer protocol.
Bound socket : Use socket_bind to bind the socket to a specific local address and port (in this example, the address is 127.0.0.1 and the port is 8080 ).
Get socket information : Get the socket's local address and port through the socket_getsockname function and output it.
Calculate the control message space size : socket_cmsg_space calculates the required control message space and outputs its size. Here we use SO_RCVBUF to get the control message size of the receiving buffer.
Close socket : Use the socket_close function to close the socket.
This combination of socket_getsockname and socket_cmsg_space allows you to flexibly get detailed information about sockets in network programming, especially in the following scenarios:
Network debugging : It can be used to debug socket connections, obtain local addresses and ports, and help troubleshoot connection problems.
Data flow control : By calculating the space size of the control message, developers can effectively manage the receiving and sending buffers to ensure the efficiency and stability of data transmission.
When using socket_getsockname , make sure the socket has been successfully bound, otherwise the function will return an error.
When calculating the control message space, different space sizes may be required depending on different protocols and control message types, so make sure to use the correct level and type parameters.
