PHP RFC: Implement socket_getaddrinfo()

• Version: 0.1
• Date: 2016-08-08
• Author: David Walker (dave@mudsite.com)
• Status: Under Discussion
• First Published at: http://wiki.php.net/rfc/socket_getaddrinfo

This RFC targets a reported feature request in #72733. The request is that PHP expose the C level function getaddrinfo(). This is a missing nice piece to the current socket library. When dealing with variable networks it would be beneficial to allow libc to tell us what methods of connecting/listening would be most appropriate given a set of hints.

I'm starting this RFC with 2 proposed solutions, which are very similar, but I'm not sure which is preferable for implementation.

The implementation[1] I'm proposing implements 5 new socket_* functions. socket_getaddrinfo() will return an array of resources, with each resource corresponding to each returned addrinfo. The next two implemented methods socket_addrinfo_bind(), and socket_addrinfo_connect(), would be used to bind, or connect, to a given resource rather than make the user go through the process of creating the socket and connect/binding themselves. The fourth function is a free'r if you'd want to free the resources before end of script. And the last to pull info from the addrinfo resource.

socket_getaddrinfo(string node[, mixed service, array hints]) : array
socket_addrinfo_connect(resource $addrinfo) : resource
socket_addrinfo_bind(resource $addrinfo) : resource
socket_addrinfo(resource $addrinfo) : array
socket_addrinfo_close(sockaddrresource sockaddr) : null

<?php
$addrinfo = socket_getaddrinfo('127.0.0.1', 2000, array('ai_family' => AI_INET, 'ai_socktype' => SOCK_STREAM));
$sockaddr = reset($addrinfo);
if (!$sockaddr) die ("No Valid Socket Types");
$sock = socket_addrinfo_bind($sockaddr);
// ^^ $sock is a socket resource that is bound to 127.0.0.1:2000 using TCP/IP ready for reading
foreach ($addrinfo as $sockaddr) {
    socket_addrinfo_close($sockaddr);
}

Pro

• Doesn't change current functions

Con

• Adds duplicative functions
• Isn't very 'C' like in how it's used

This attempt [2] is similar to the first, and tries to be a hybrid approach. It alters the default signature of socket_(connect|bind) to change the second argument to mixed. This method is the most C-like of the 3. After playing with all three, this is my preferred, but changing default signatures is not always the best idea.

socket_getaddrinfo(string $node[, mixed $service, array $hints]) : array
socket_connect(resource $sock, mixed $address_or_addrinfo[, int $port = 0]) : bool
socket_bind(resource $sock, string $address_or_addrinfo[, int port = 0]) : bool
socket_addrinfo_close(resourece $addrinfo) : null

<?php
$addrinfo = socket_getaddrinfo('127.0.0.1', 2000, array('ai_family' => AI_INET, 'ai_socktype' => SOCK_STREAM));
$sockaddr = reset($addrinfo);
if (!$sockaddr) die ("No Valid Socket Types");
$sock = socket_create($sockaddr['ai_family'], $sockaddr['ai_socktype'], $sockaddr['ai_protocol']);
$sock = socket_bind($sock, $sockaddr);
// ^^ $sock is a socket resource that is bound to 127.0.0.1:2000 using TCP/IP ready for reading
foreach ($addrinfo as $sockaddr) {
    socket_addrinfo_close($sockaddr);
}

Pro

• Used much more like how C implements socket()/bind()/connect()

Con

• Changes default signatures of socket_bind()/socket_connect()

New functionality; BC problems in changing default socket function signatures for Proposal 2. Although code that exists today ought not to have BC issues.

Next PHP 7.x (currently 7.2)

None

Socket acquired new functionality

None

Exposing the AI_* family of constants.

Vote to implement the new functions, would require a 2/3 majority.

• [1] - Proposed #1 Implementation
• [2] - Proposed #2 Implementation