Use default nameservers (support /etc/resolv.conf) about dns HOT 11 CLOSED

<?php
namespace React\Dns\Query;

use React\Dns\RecordNotFoundException;
use React\Dns\Model\Message;
use React\Dns\Model\Record;
use React\Dns\Query\ExecutorInterface;
use React\Dns\Query\Query;
use React\EventLoop\LoopInterface;
use React\Promise\Deferred;

class LocalResolverExecutor implements ExecutorInterface
{
    private $loop;
    private $executor;

    public function __construct(LoopInterface $loop, ExecutorInterface $executor, $timeout = 5)
    {
        $this->loop = $loop;
        $this->executor = $executor;
    $this->timeout = $timeout;
    }

    public function query($nameserver, Query $query)
    {
        $executor = $this->executor;
        return $this
        ->doQuery($query)
            ->then(null, function () use ($query, $nameserver, $executor) {
                return $executor->query($nameserver, $query);
            });
    }

    public function doQuery($query)
    {

        $that = $this;
    $name = $query->name;

        $deferred = new Deferred(function ($resolve, $reject) use (&$timer, $name) {
            $reject(new CancellationException(sprintf('DNS query for %s has been cancelled', $name)));
            $timer->cancel();
        });

        $timer = $this->loop->addTimer($this->timeout, function () use ($name, $deferred) {
            $deferred->reject(new TimeoutException(sprintf("DNS query for %s timed out", $name)));
        });

        $this->loop->addTimer(0, function () use ($that, $query, $deferred, $timer) {

        $record = gethostbyname($query->name);

            $timer->cancel();

            if ($record == $query->name) {
                $deferred->reject(new RecordNotFoundException(sprintf('Unable to resolve %s', $query->name)));
            }

        $response = $that->buildResponse($query, [ new Record($query->name, $query->type, $query->class, 5, $record) ]);

            $deferred->resolve($response);
        });

        return $deferred->promise();

    }

    public function buildResponse(Query $query, array $records)
    {
        $response = new Message();
        $response->header->set('id', $this->generateId());
        $response->header->set('qr', 1);
        $response->header->set('opcode', Message::OPCODE_QUERY);
        $response->header->set('rd', 1);
        $response->header->set('rcode', Message::RCODE_OK);
        $response->questions[] = new Record($query->name, $query->type, $query->class);
        $response->answers = $records;
        $response->prepare();
        return $response;
    }

    protected function generateId()
    {
        return mt_rand(0, 0xffff);
    }
}