108 lines
2.4 KiB
PHP
108 lines
2.4 KiB
PHP
<?php
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/**
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* Service discovery using DNS SRV records
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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/**
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* @since 1.29
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*/
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class DnsSrvDiscoverer {
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/**
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* @var string
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*/
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private $domain;
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/**
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* @param string $domain
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*/
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public function __construct( $domain ) {
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$this->domain = $domain;
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}
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/**
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* Fetch the servers with a DNS SRV request
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*
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* @return array
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*/
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public function getServers() {
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$result = [];
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foreach ( $this->getDnsRecords() as $record ) {
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$result[] = [
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'target' => $record['target'],
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'port' => $record['port'],
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'pri' => $record['pri'],
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'weight' => $record['weight'],
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];
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}
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return $result;
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}
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/**
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* Pick a server according to the priority fields.
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* Note that weight is currently ignored.
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*
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* @param array $servers from getServers
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* @return array|bool
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*/
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public function pickServer( array $servers ) {
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if ( !$servers ) {
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return false;
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}
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$srvsByPrio = [];
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foreach ( $servers as $server ) {
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$srvsByPrio[$server['pri']][] = $server;
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}
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$min = min( array_keys( $srvsByPrio ) );
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if ( count( $srvsByPrio[$min] ) == 1 ) {
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return $srvsByPrio[$min][0];
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} else {
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// Choose randomly
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$rand = mt_rand( 0, count( $srvsByPrio[$min] ) - 1 );
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return $srvsByPrio[$min][$rand];
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}
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}
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/**
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* @param array $server
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* @param array[] $servers
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* @return array[]
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*/
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public function removeServer( $server, array $servers ) {
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foreach ( $servers as $i => $srv ) {
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if ( $srv['target'] === $server['target'] && $srv['port'] === $server['port'] ) {
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unset( $servers[$i] );
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break;
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}
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}
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return array_values( $servers );
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}
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/**
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* @return array[]
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*/
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protected function getDnsRecords() {
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return dns_get_record( $this->domain, DNS_SRV );
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}
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}
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