PHP Socket context options

Access to filesystem and various other stream wrappers can be customized by context options and parameters configured by stream_context_create() and stream_context_set_option() functions.

Following list shows various socket context options available for all wrappers that work over sockets, like tcp, http and ftp ?

Socket Context Options

Example

Here's how to bind to a specific IP address when making HTTP requests ?

<?php
// Connect to the internet using the '192.168.0.100' IP
$opts = array(
    'socket' => array(
        'bindto' => '192.168.0.100:0',
    ),
);

$context = stream_context_create($opts);

// Use the context to fetch data
echo file_get_contents('http://www.example.com', false, $context);
?>

Multiple Socket Options Example

You can combine multiple socket options for more advanced configurations ?

<?php
$opts = array(
    'socket' => array(
        'bindto' => '0:80',
        'backlog' => 128,
        'so_reuseport' => true,
        'tcp_nodelay' => true,
    ),
);

$context = stream_context_create($opts);
$server = stream_socket_server('tcp://localhost:8080', $errno, $errstr, 
                               STREAM_SERVER_BIND | STREAM_SERVER_LISTEN, $context);
?>

Conclusion

Socket context options provide fine-grained control over network connections in PHP. Use them to specify binding addresses, configure connection limits, and optimize TCP behavior for your specific use cases.