MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / libs / DnsSrvDiscoverer.php

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