Socket context options

Socket context options — Socket context option listing

Description

Socket context options are available for all wrappers that work over sockets, like tcp, http and ftp.

Options

bindto: Used to specify the IP address (either IPv4 or IPv6) and/or the port number that PHP will use to access the network. The syntax is ip:port for IPv4 addresses, and [ip]:port for IPv6 addresses. Setting the IP or the port to 0 will let the system choose the IP and/or port.

Note:
As FTP creates two socket connections during normal operation, the port number cannot be specified using this option.
backlog: Used to limit the number of outstanding connections in the socket's listen queue.

Note:
This is only applicable to stream_socket_server().
ipv6_v6only: Overrides the OS default regarding mapping IPv4 into IPv6.

Note:
This is important in particular when trying to listen on IPv4 addresses separately while there exists a binding on [::].

This is only applicable to stream_socket_server().
so_reuseport: Allows multiple bindings to a same ip:port pair, even from separate processes.

Note:
This is only applicable to stream_socket_server().
so_broadcast: Enables sending and receiving data to/from broadcast addresses.

Note:
This is only applicable to stream_socket_server().
tcp_nodelay: Setting this option to true will set SOL_TCP,NO_DELAY=1 appropriately, thus disabling the TCP Nagle algorithm.

Changelog

Version	Description
7.1.0	Added `tcp_nodelay`.
7.0.1	Added `ipv6_v6only`.

Examples

Example #1 Basic bindto usage example

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

/ connect to the internet using the '192.168.0.100' IP and port '7000'
$opts = array(
    'socket' => array(
        'bindto' => '192.168.0.100:7000',
    ),
);

/ connect to the internet using the '2001:db8::1' IPv6 address
/ and port '7000'
$opts = array(
    'socket' => array(
        'bindto' => '[2001:db8::1]:7000',
    ),
);

/ connect to the internet using port '7000'
$opts = array(
    'socket' => array(
        'bindto' => '0:7000',
    ),
);

/ create the context...
$context = stream_context_create($opts);

/ ...and use it to fetch the data
echo file_get_contents('http://www.example.com', false, $context);

?>

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User Contributed Notes 2 notes

down

mix at ater dot me ¶

6 years ago

The right way for forcing IPv6 is 'bindto' => '[::]:0'

down

guru at jnt-finland dot fi ¶

9 years ago

You can set "bindto" to "0:0" to force use IPv4 instead of IPv6. And probably "[0]:0" to force use IPv6, thou this I couldn't test.

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