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<?php
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namespace React\Dns\Query;
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use React\Dns\Config\HostsFile;
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use React\Dns\Model\Message;
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use React\Dns\Model\Record;
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use React\Promise;
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/**
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* Resolves hosts from the given HostsFile or falls back to another executor
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*
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* If the host is found in the hosts file, it will not be passed to the actual
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* DNS executor. If the host is not found in the hosts file, it will be passed
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* to the DNS executor as a fallback.
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*/
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final class HostsFileExecutor implements ExecutorInterface
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{
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private $hosts;
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private $fallback;
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public function __construct(HostsFile $hosts, ExecutorInterface $fallback)
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{
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$this->hosts = $hosts;
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$this->fallback = $fallback;
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}
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public function query(Query $query)
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{
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if ($query->class === Message::CLASS_IN && ($query->type === Message::TYPE_A || $query->type === Message::TYPE_AAAA)) {
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// forward lookup for type A or AAAA
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$records = array();
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$expectsColon = $query->type === Message::TYPE_AAAA;
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foreach ($this->hosts->getIpsForHost($query->name) as $ip) {
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// ensure this is an IPv4/IPV6 address according to query type
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if ((strpos($ip, ':') !== false) === $expectsColon) {
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$records[] = new Record($query->name, $query->type, $query->class, 0, $ip);
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}
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}
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if ($records) {
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return Promise\resolve(
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Message::createResponseWithAnswersForQuery($query, $records)
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);
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}
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} elseif ($query->class === Message::CLASS_IN && $query->type === Message::TYPE_PTR) {
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// reverse lookup: extract IPv4 or IPv6 from special `.arpa` domain
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$ip = $this->getIpFromHost($query->name);
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if ($ip !== null) {
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$records = array();
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foreach ($this->hosts->getHostsForIp($ip) as $host) {
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$records[] = new Record($query->name, $query->type, $query->class, 0, $host);
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}
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if ($records) {
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return Promise\resolve(
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Message::createResponseWithAnswersForQuery($query, $records)
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);
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}
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}
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}
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return $this->fallback->query($query);
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}
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private function getIpFromHost($host)
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{
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if (substr($host, -13) === '.in-addr.arpa') {
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// IPv4: read as IP and reverse bytes
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$ip = @inet_pton(substr($host, 0, -13));
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if ($ip === false || isset($ip[4])) {
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return null;
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}
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return inet_ntop(strrev($ip));
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} elseif (substr($host, -9) === '.ip6.arpa') {
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// IPv6: replace dots, reverse nibbles and interpret as hexadecimal string
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$ip = @inet_ntop(pack('H*', strrev(str_replace('.', '', substr($host, 0, -9)))));
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if ($ip === false) {
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return null;
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}
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return $ip;
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} else {
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return null;
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}
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}
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}
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