1<?php
2/**
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 * http://www.gnu.org/copyleft/gpl.html
17 *
18 * @file
19 */
20
21use Wikimedia\IPUtils;
22
23/**
24 * A generic class to send a message over UDP
25 *
26 * If a message prefix is provided to the constructor or via
27 * UDPTransport::newFromString(), the payload of the UDP datagrams emitted
28 * will be formatted with the prefix and a single space at the start of each
29 * line. This is the payload format expected by the udp2log service.
30 *
31 * @since 1.25
32 */
33class UDPTransport {
34	// Limit to 64KB
35	public const MAX_PAYLOAD_SIZE = 65507;
36	private $host, $port, $prefix, $domain;
37
38	/**
39	 * @param string $host IP address to send to
40	 * @param int $port port number
41	 * @param int $domain AF_INET or AF_INET6 constant
42	 * @param string|bool $prefix Prefix to use, false for no prefix
43	 */
44	public function __construct( $host, $port, $domain, $prefix = false ) {
45		$this->host = $host;
46		$this->port = $port;
47		$this->domain = $domain;
48		$this->prefix = $prefix;
49	}
50
51	/**
52	 * @param string $info In the format of "udp://host:port/prefix"
53	 * @return UDPTransport
54	 * @throws InvalidArgumentException
55	 */
56	public static function newFromString( $info ) {
57		if ( preg_match( '!^udp:(?://)?\[([0-9a-fA-F:]+)\]:(\d+)(?:/(.*))?$!', $info, $m ) ) {
58			// IPv6 bracketed host
59			$host = $m[1];
60			$port = intval( $m[2] );
61			$prefix = $m[3] ?? false;
62			$domain = AF_INET6;
63		} elseif ( preg_match( '!^udp:(?://)?([a-zA-Z0-9.-]+):(\d+)(?:/(.*))?$!', $info, $m ) ) {
64			$host = $m[1];
65			if ( !IPUtils::isIPv4( $host ) ) {
66				$host = gethostbyname( $host );
67			}
68			$port = intval( $m[2] );
69			$prefix = $m[3] ?? false;
70			$domain = AF_INET;
71		} else {
72			throw new InvalidArgumentException( __METHOD__ . ': Invalid UDP specification' );
73		}
74
75		return new self( $host, $port, $domain, $prefix );
76	}
77
78	/**
79	 * @param string $text
80	 */
81	public function emit( $text ) : void {
82		// Clean it up for the multiplexer
83		if ( $this->prefix !== false ) {
84			$text = preg_replace( '/^/m', $this->prefix . ' ', $text );
85
86			if ( strlen( $text ) > self::MAX_PAYLOAD_SIZE - 1 ) {
87				$text = substr( $text, 0, self::MAX_PAYLOAD_SIZE - 1 );
88			}
89
90			if ( substr( $text, -1 ) != "\n" ) {
91				$text .= "\n";
92			}
93		} elseif ( strlen( $text ) > self::MAX_PAYLOAD_SIZE ) {
94			$text = substr( $text, 0, self::MAX_PAYLOAD_SIZE );
95		}
96
97		$sock = socket_create( $this->domain, SOCK_DGRAM, SOL_UDP );
98		if ( !$sock ) { // @todo should this throw an exception?
99			return;
100		}
101
102		socket_sendto( $sock, $text, strlen( $text ), 0, $this->host, $this->port );
103		socket_close( $sock );
104	}
105}
106