mirror of
https://github.com/danog/dns.git
synced 2024-11-30 04:29:06 +01:00
611 lines
22 KiB
PHP
611 lines
22 KiB
PHP
<?php
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namespace Amp\Dns;
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use Amp\Cache\ArrayCache;
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use Amp\CombinatorException;
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use Amp\CoroutineResult;
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use Amp\Deferred;
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use Amp\Failure;
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use Amp\File\FilesystemException;
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use Amp\Success;
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use LibDNS\Decoder\DecoderFactory;
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use LibDNS\Encoder\EncoderFactory;
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use LibDNS\Messages\MessageFactory;
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use LibDNS\Messages\MessageTypes;
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use LibDNS\Records\QuestionFactory;
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class DefaultResolver implements Resolver {
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private $messageFactory;
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private $questionFactory;
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private $encoder;
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private $decoder;
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private $arrayCache;
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private $requestIdCounter;
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private $pendingRequests;
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private $serverIdMap;
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private $serverUriMap;
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private $serverIdTimeoutMap;
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private $now;
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private $serverTimeoutWatcher;
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private $config;
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public function __construct() {
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$this->messageFactory = new MessageFactory;
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$this->questionFactory = new QuestionFactory;
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$this->encoder = (new EncoderFactory)->create();
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$this->decoder = (new DecoderFactory)->create();
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$this->arrayCache = new ArrayCache;
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$this->requestIdCounter = 1;
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$this->pendingRequests = [];
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$this->serverIdMap = [];
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$this->serverUriMap = [];
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$this->serverIdTimeoutMap = [];
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$this->now = \time();
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$this->serverTimeoutWatcher = \Amp\repeat(function ($watcherId) {
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$this->now = $now = \time();
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foreach ($this->serverIdTimeoutMap as $id => $expiry) {
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if ($now > $expiry) {
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$this->unloadServer($id);
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}
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}
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if (empty($this->serverIdMap)) {
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\Amp\disable($watcherId);
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}
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}, 1000, $options = [
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"enable" => true,
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"keep_alive" => false,
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]);
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}
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/**
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* {@inheritdoc}
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*/
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public function resolve($name, array $options = []) {
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if (!$inAddr = @\inet_pton($name)) {
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if ($this->isValidHostName($name)) {
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$types = empty($options["types"]) ? [Record::A, Record::AAAA] : (array) $options["types"];
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return $this->pipeResult($this->recurseWithHosts($name, $types, $options), $types);
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} else {
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return new Failure(new ResolutionException("Cannot resolve; invalid host name"));
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}
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} else {
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return new Success([[$name, isset($inAddr[4]) ? Record::AAAA : Record::A, $ttl = null]]);
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}
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}
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/**
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* {$inheritdoc}
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*/
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public function query($name, $type, array $options = []) {
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$handler = [$this, empty($options["recurse"]) ? "doResolve" : "doRecurse"];
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$types = (array) $type;
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return $this->pipeResult(\Amp\resolve($handler($name, $types, $options)), $types);
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}
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private function isValidHostName($name) {
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$pattern = "/^(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9]){0,1})(?:\\.[a-z0-9][a-z0-9-]{0,61}[a-z0-9])*$/i";
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return !isset($name[253]) && \preg_match($pattern, $name);
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}
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// flatten $result while preserving order according to $types (append unspecified types for e.g. Record::ALL queries)
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private function pipeResult($promise, array $types) {
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return \Amp\pipe($promise, function (array $result) use ($types) {
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$retval = [];
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foreach ($types as $type) {
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if (isset($result[$type])) {
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$retval = \array_merge($retval, $result[$type]);
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unset($result[$type]);
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}
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}
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return $result ? \array_merge($retval, \call_user_func_array("array_merge", $result)) : $retval;
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});
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}
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private function recurseWithHosts($name, array $types, $options) {
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// Check for hosts file matches
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if (!isset($options["hosts"]) || $options["hosts"]) {
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static $hosts = null;
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if ($hosts === null || !empty($options["reload_hosts"])) {
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return \Amp\pipe(\Amp\resolve($this->loadHostsFile()), function ($value) use (&$hosts, $name, $types, $options) {
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unset($options["reload_hosts"]); // avoid recursion
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$hosts = $value;
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return $this->recurseWithHosts($name, $types, $options);
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});
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}
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$result = [];
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if (in_array(Record::A, $types) && isset($hosts[Record::A][$name])) {
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$result[Record::A] = [[$hosts[Record::A][$name], Record::A, $ttl = null]];
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}
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if (in_array(Record::AAAA, $types) && isset($hosts[Record::AAAA][$name])) {
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$result[Record::AAAA] = [[$hosts[Record::AAAA][$name], Record::AAAA, $ttl = null]];
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}
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if ($result) {
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return new Success($result);
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}
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}
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return \Amp\resolve($this->doRecurse($name, $types, $options));
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}
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private function doRecurse($name, array $types, $options) {
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if (array_intersect($types, [Record::CNAME, Record::DNAME])) {
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throw new ResolutionException("Cannot use recursion for CNAME and DNAME records");
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}
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$types = array_merge($types, [Record::CNAME, Record::DNAME]);
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$lookupName = $name;
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for ($i = 0; $i < 30; $i++) {
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$result = (yield \Amp\resolve($this->doResolve($lookupName, $types, $options)));
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if (count($result) > isset($result[Record::CNAME]) + isset($result[Record::DNAME])) {
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unset($result[Record::CNAME], $result[Record::DNAME]);
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yield new CoroutineResult($result);
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return;
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}
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// @TODO check for potentially using recursion and iterate over *all* CNAME/DNAME
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// @FIXME check higher level for CNAME?
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foreach ([Record::CNAME, Record::DNAME] as $type) {
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if (isset($result[$type])) {
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list($lookupName) = $result[$type][0];
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}
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}
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}
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throw new ResolutionException("CNAME or DNAME chain too long (possible recursion?)");
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}
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private function doRequest($uri, $name, $type) {
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$server = $this->loadExistingServer($uri) ?: $this->loadNewServer($uri);
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// Get the next available request ID
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do {
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$requestId = $this->requestIdCounter++;
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if ($this->requestIdCounter >= MAX_REQUEST_ID) {
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$this->requestIdCounter = 1;
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}
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} while (isset($this->pendingRequests[$requestId]));
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// Create question record
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$question = $this->questionFactory->create($type);
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$question->setName($name);
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// Create request message
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$request = $this->messageFactory->create(MessageTypes::QUERY);
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$request->getQuestionRecords()->add($question);
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$request->isRecursionDesired(true);
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$request->setID($requestId);
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// Encode request message
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$requestPacket = $this->encoder->encode($request);
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if (substr($uri, 0, 6) == "tcp://") {
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$requestPacket = pack("n", strlen($requestPacket)) . $requestPacket;
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}
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// Send request
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$bytesWritten = \fwrite($server->socket, $requestPacket);
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if ($bytesWritten === false || isset($packet[$bytesWritten])) {
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throw new ResolutionException(
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"Request send failed"
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);
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}
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$promisor = new Deferred;
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$server->pendingRequests[$requestId] = true;
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$this->pendingRequests[$requestId] = [$promisor, $name, $type, $uri];
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return $promisor->promise();
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}
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private function doResolve($name, array $types, $options) {
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if (!$this->config) {
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$this->config = (yield \Amp\resolve($this->loadResolvConf()));
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}
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if (empty($types)) {
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yield new CoroutineResult([]);
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return;
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}
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assert(array_reduce($types, function ($result, $val) { return $result && \is_int($val); }, true), 'The $types passed to DNS functions must all be integers (from \Amp\Dns\Record class)');
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$name = \strtolower($name);
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$result = [];
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// Check for cache hits
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if (!isset($options["cache"]) || $options["cache"]) {
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foreach ($types as $k => $type) {
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$cacheKey = "$name#$type";
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$cacheValue = (yield $this->arrayCache->get($cacheKey));
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if ($cacheValue !== null) {
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$result[$type] = $cacheValue;
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unset($types[$k]);
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}
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}
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if (empty($types)) {
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if (empty(array_filter($result))) {
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throw new NoRecordException("No records returned for {$name} (cached result)");
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} else {
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yield new CoroutineResult($result);
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return;
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}
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}
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}
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$timeout = empty($options["timeout"]) ? $this->config["timeout"] : (int) $options["timeout"];
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if (empty($options["server"])) {
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if (empty($this->config["nameservers"])) {
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throw new ResolutionException("No nameserver specified in system config");
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}
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$uri = "udp://" . $this->config["nameservers"][0];
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} else {
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$uri = $this->parseCustomServerUri($options["server"]);
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}
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foreach ($types as $type) {
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$promises[] = $this->doRequest($uri, $name, $type);
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}
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try {
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list( , $resultArr) = (yield \Amp\timeout(\Amp\some($promises), $timeout));
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foreach ($resultArr as $value) {
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$result += $value;
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}
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} catch (\Amp\TimeoutException $e) {
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if (substr($uri, 0, 6) == "tcp://") {
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throw new TimeoutException(
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"Name resolution timed out for {$name}"
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);
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} else {
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$options["server"] = \preg_replace("#[a-z.]+://#", "tcp://", $uri);
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yield new CoroutineResult(\Amp\resolve($this->doResolve($name, $types, $options)));
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return;
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}
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} catch (ResolutionException $e) {
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if (empty($result)) { // if we have no cached results
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throw $e;
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}
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} catch (CombinatorException $e) { // if all promises in Amp\some fail
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if (empty($result)) { // if we have no cached results
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foreach ($e->getExceptions() as $ex) {
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if ($ex instanceof NoRecordException) {
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throw new NoRecordException("No records returned for {$name}", 0, $e);
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}
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}
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throw new ResolutionException("All name resolution requests failed", 0, $e);
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}
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}
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yield new CoroutineResult($result);
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}
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/** @link http://man7.org/linux/man-pages/man5/resolv.conf.5.html */
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private function loadResolvConf($path = null) {
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$result = [
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"nameservers" => [
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"8.8.8.8:53",
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"8.8.4.4:53",
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],
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"timeout" => 3000,
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"attempts" => 2,
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];
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if (\stripos(PHP_OS, "win") !== 0 || $path !== null) {
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$path = $path ?: "/etc/resolv.conf";
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try {
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$lines = explode("\n", (yield \Amp\File\get($path)));
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$result["nameservers"] = [];
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foreach ($lines as $line) {
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$line = \preg_split('#\s+#', $line, 2);
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if (\count($line) !== 2) {
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continue;
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}
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list($type, $value) = $line;
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if ($type === "nameserver") {
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$line[1] = trim($line[1]);
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$ip = @\inet_pton($line[1]);
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if ($ip === false) {
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continue;
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}
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if (isset($ip[15])) {
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$result["nameservers"][] = "[" . $line[1] . "]:53";
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} else {
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$result["nameservers"][] = $line[1] . ":53";
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}
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} elseif ($type === "options") {
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$optline = preg_split('#\s+#', $value, 2);
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if (\count($optline) !== 2) {
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continue;
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}
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// TODO: Respect the contents of the attempts setting during resolution
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list($option, $value) = $optline;
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if (in_array($option, ["timeout", "attempts"])) {
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$result[$option] = (int) $value;
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}
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}
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}
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} catch (FilesystemException $e) {
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// use default
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}
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}
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yield new CoroutineResult($result);
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}
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private function loadHostsFile($path = null) {
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$data = [];
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if (empty($path)) {
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$path = \stripos(PHP_OS, "win") === 0
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? 'C:\Windows\system32\drivers\etc\hosts'
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: '/etc/hosts';
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}
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try {
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$contents = (yield \Amp\File\get($path));
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} catch (\Exception $e) {
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yield new CoroutineResult($data);
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return;
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}
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$lines = \array_filter(\array_map("trim", \explode("\n", $contents)));
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foreach ($lines as $line) {
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if ($line[0] === "#") {
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continue;
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}
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$parts = \preg_split('/\s+/', $line);
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if (!($ip = @\inet_pton($parts[0]))) {
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continue;
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} elseif (isset($ip[4])) {
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$key = Record::AAAA;
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} else {
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$key = Record::A;
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}
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for ($i = 1, $l = \count($parts); $i < $l; $i++) {
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if ($this->isValidHostName($parts[$i])) {
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$data[$key][strtolower($parts[$i])] = $parts[0];
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}
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}
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}
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// Windows does not include localhost in its host file. Fetch it from the system instead
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if (!isset($data[Record::A]["localhost"]) && !isset($data[Record::AAAA]["localhost"])) {
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// PHP currently provides no way to **resolve** IPv6 hostnames (not even with fallback)
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$local = gethostbyname("localhost");
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if ($local !== "localhost") {
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$data[Record::A]["localhost"] = $local;
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} else {
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$data[Record::AAAA]["localhost"] = "::1";
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}
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}
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yield new CoroutineResult($data);
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}
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private function parseCustomServerUri($uri) {
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if (!\is_string($uri)) {
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throw new ResolutionException(
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'Invalid server address ($uri must be a string IP address, ' . gettype($uri) . " given)"
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);
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}
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if (strpos($uri, "://") !== false) {
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return $uri;
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}
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if (($colonPos = strrpos(":", $uri)) !== false) {
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$addr = \substr($uri, 0, $colonPos);
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$port = \substr($uri, $colonPos);
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} else {
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$addr = $uri;
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$port = 53;
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}
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$addr = trim($addr, "[]");
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if (!$inAddr = @\inet_pton($addr)) {
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throw new ResolutionException(
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'Invalid server $uri; string IP address required'
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);
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}
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return isset($inAddr[4]) ? "udp://[{$addr}]:{$port}" : "udp://{$addr}:{$port}";
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}
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private function loadExistingServer($uri) {
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if (empty($this->serverUriMap[$uri])) {
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return null;
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}
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$server = $this->serverUriMap[$uri];
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if (\is_resource($server->socket)) {
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unset($this->serverIdTimeoutMap[$server->id]);
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\Amp\enable($server->watcherId);
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return $server;
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}
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$this->unloadServer($server->id);
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return null;
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}
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private function loadNewServer($uri) {
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if (!$socket = @\stream_socket_client($uri, $errno, $errstr)) {
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throw new ResolutionException(sprintf(
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"Connection to %s failed: [Error #%d] %s",
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$uri,
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$errno,
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$errstr
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));
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}
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\stream_set_blocking($socket, false);
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$id = (int) $socket;
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$server = new \StdClass;
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$server->id = $id;
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$server->uri = $uri;
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$server->socket = $socket;
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$server->buffer = "";
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$server->length = INF;
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$server->pendingRequests = [];
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$server->watcherId = \Amp\onReadable($socket, $this->makePrivateCallable("onReadable"), [
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"enable" => true,
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"keep_alive" => true,
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]);
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$this->serverIdMap[$id] = $server;
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$this->serverUriMap[$uri] = $server;
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return $server;
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}
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private function unloadServer($serverId, $error = null) {
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// Might already have been unloaded (especially if multiple requests happen)
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if (!isset($this->serverIdMap[$serverId])) {
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return;
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}
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$server = $this->serverIdMap[$serverId];
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\Amp\cancel($server->watcherId);
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unset(
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$this->serverIdMap[$serverId],
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$this->serverUriMap[$server->uri]
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);
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if (\is_resource($server->socket)) {
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@\fclose($server->socket);
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}
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if ($error && $server->pendingRequests) {
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foreach (array_keys($server->pendingRequests) as $requestId) {
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list($promisor) = $this->pendingRequests[$requestId];
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$promisor->fail($error);
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}
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}
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}
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private function onReadable($watcherId, $socket) {
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$serverId = (int) $socket;
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$packet = @\fread($socket, 512);
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if ($packet != "") {
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$server = $this->serverIdMap[$serverId];
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if (\substr($server->uri, 0, 6) == "tcp://") {
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if ($server->length == INF) {
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$server->length = unpack("n", $packet)[1];
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$packet = substr($packet, 2);
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}
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$server->buffer .= $packet;
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while ($server->length <= \strlen($server->buffer)) {
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$this->decodeResponsePacket($serverId, substr($server->buffer, 0, $server->length));
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$server->buffer = substr($server->buffer, $server->length);
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if (\strlen($server->buffer) >= 2 + $server->length) {
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$server->length = unpack("n", $server->buffer)[1];
|
|
$server->buffer = substr($server->buffer, 2);
|
|
} else {
|
|
$server->length = INF;
|
|
}
|
|
}
|
|
} else {
|
|
$this->decodeResponsePacket($serverId, $packet);
|
|
}
|
|
} else {
|
|
$this->unloadServer($serverId, new ResolutionException(
|
|
"Server connection failed"
|
|
));
|
|
}
|
|
}
|
|
|
|
private function decodeResponsePacket($serverId, $packet) {
|
|
try {
|
|
$response = $this->decoder->decode($packet);
|
|
$requestId = $response->getID();
|
|
$responseCode = $response->getResponseCode();
|
|
$responseType = $response->getType();
|
|
|
|
if ($responseCode !== 0) {
|
|
$this->finalizeResult($serverId, $requestId, new ResolutionException(
|
|
"Server returned error code: {$responseCode}"
|
|
));
|
|
} elseif ($responseType !== MessageTypes::RESPONSE) {
|
|
$this->unloadServer($serverId, new ResolutionException(
|
|
"Invalid server reply; expected RESPONSE but received QUERY"
|
|
));
|
|
} else {
|
|
$this->processDecodedResponse($serverId, $requestId, $response);
|
|
}
|
|
} catch (\Exception $e) {
|
|
$this->unloadServer($serverId, new ResolutionException(
|
|
"Response decode error", 0, $e
|
|
));
|
|
}
|
|
}
|
|
|
|
private function processDecodedResponse($serverId, $requestId, $response) {
|
|
list($promisor, $name, $type, $uri) = $this->pendingRequests[$requestId];
|
|
|
|
// Retry via tcp if message has been truncated
|
|
if ($response->isTruncated()) {
|
|
if (\substr($uri, 0, 6) != "tcp://") {
|
|
$uri = \preg_replace("#[a-z.]+://#", "tcp://", $uri);
|
|
$promisor->succeed($this->doRequest($uri, $name, $type));
|
|
} else {
|
|
$this->finalizeResult($serverId, $requestId, new ResolutionException(
|
|
"Server returned truncated response"
|
|
));
|
|
}
|
|
return;
|
|
}
|
|
|
|
$answers = $response->getAnswerRecords();
|
|
foreach ($answers as $record) {
|
|
$result[$record->getType()][] = [(string) $record->getData(), $record->getType(), $record->getTTL()];
|
|
}
|
|
if (empty($result)) {
|
|
$this->arrayCache->set("$name#$type", [], 300); // "it MUST NOT cache it for longer than five (5) minutes" per RFC 2308 section 7.1
|
|
$this->finalizeResult($serverId, $requestId, new NoRecordException(
|
|
"No records returned for {$name}"
|
|
));
|
|
} else {
|
|
$this->finalizeResult($serverId, $requestId, $error = null, $result);
|
|
}
|
|
}
|
|
|
|
private function finalizeResult($serverId, $requestId, $error = null, $result = null) {
|
|
if (empty($this->pendingRequests[$requestId])) {
|
|
return;
|
|
}
|
|
|
|
list($promisor, $name) = $this->pendingRequests[$requestId];
|
|
$server = $this->serverIdMap[$serverId];
|
|
unset(
|
|
$this->pendingRequests[$requestId],
|
|
$server->pendingRequests[$requestId]
|
|
);
|
|
if (empty($server->pendingRequests)) {
|
|
$this->serverIdTimeoutMap[$server->id] = $this->now + IDLE_TIMEOUT;
|
|
\Amp\disable($server->watcherId);
|
|
\Amp\enable($this->serverTimeoutWatcher);
|
|
}
|
|
if ($error) {
|
|
$promisor->fail($error);
|
|
} else {
|
|
foreach ($result as $type => $records) {
|
|
$minttl = INF;
|
|
foreach ($records as list( , $ttl)) {
|
|
if ($ttl && $minttl > $ttl) {
|
|
$minttl = $ttl;
|
|
}
|
|
}
|
|
$this->arrayCache->set("$name#$type", $records, $minttl);
|
|
}
|
|
$promisor->succeed($result);
|
|
}
|
|
}
|
|
|
|
private function makePrivateCallable($method) {
|
|
return (new \ReflectionClass($this))->getMethod($method)->getClosure($this);
|
|
}
|
|
}
|