Async DNS resolver and name server.
The main point of the DNS component is to provide async DNS resolution. However, it is really a toolkit for working with DNS messages, and could easily be used to create a DNS server.
The most basic usage is to just create a resolver through the resolver factory. All you need to give it is a nameserver, then you can start resolving names, baby!
$loop = React\EventLoop\Factory::create();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->create('8.8.8.8', $loop);
$dns->resolve('igor.io')->then(function ($ip) {
echo "Host: $ip\n";
});To get more detailed response (in a dig like fashion) about DNS
$loop = React\EventLoop\Factory::create();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->create('8.8.8.8', $loop);
$dns->lookup('igor.io')->then(function ($response) {
echo $response->explain();
});To resolve an IPv4/IPv4 to a hostname
$loop = React\EventLoop\Factory::create();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->create('8.8.8.8', $loop);
$ipAddress = ''; // IPv4/IPv6
$dns->reverse($ipAddress)->then(function ($response) {
if (count($response->answers))
{
$hostname = $response->answers[0]->data;
echo $response->explain();
}
});But there's more.
You can cache results by configuring the resolver to use a CachedExecutor:
$loop = React\EventLoop\Factory::create();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->createCached('8.8.8.8', $loop);
$dns->resolve('igor.io')->then(function ($ip) {
echo "Host: $ip\n";
});
...
$dns->resolve('igor.io')->then(function ($ip) {
echo "Host: $ip\n";
});If the first call returns before the second, only one query will be executed. The second result will be served from cache.
- A
- AAAA
- ANY
- CNAME
- MX
- NS
- PTR
- TXT
- SOA
- Respect /etc/hosts
Want to write your own DNS server? No problem.
$loop = React\EventLoop\Factory::create();
$server = new React\Dns\Server\Server($loop);
$server->listen(53, '0.0.0.0');
$server->ready();
$server->on('query', function($question, $clientIP, $response, $deferred)
{
/**
@var $question React\Dns\Query\Query
@var $request React\Dns\Model\Message
@var $deferred React\Promise\Deferred
*/
// Add records to answer
// $response->answers[] = new \React\Dns\Model\Record($question->name, $question->type, $question->class,
// rand(1,9999), 'DATA BASED ON TYPE GOES HERE');
// or add records to authority and additional
// $response->authority[] = new \React\Dns\Model\Record(....)
// $response->additional[] = new \React\Dns\Model\Record(....)
$deferred->resolve($response);
// or reject this
// $deferred->reject($response);
});
// print some stats as well
$loop->addPeriodicTimer(60, function() use($server)
{
echo "DNS Server stats:\n";
$server->stats();
});
$loop->run();If you are curious about DNS data send over the wire between client and name server then the following might be helpful.
$dumper = new \React\Dns\Protocol\BinaryDumper();
$query = new \React\Dns\Query\Query('igor.io',
\React\Dns\Model\Message::TYPE_A,
\React\Dns\Model\Message::CLASS_IN, time());
$request = new \React\Dns\Model\Message();
$request->header->set('id', mt_rand(0, 0xffff));
$request->header->set('rd', 1);
$request->questions[] = $query;
$request->prepare();
// or view dump when querying in TCP mode
//$request->transport = 'tcp';
// data send over wire
$queryData = $dumper->toBinary($request);
\React\Dns\Protocol\HumanParser::dumpHex($queryData);The output would be:
0 : b2 43 01 00 00 01 00 00 00 00 00 00 04 69 67 6f [.C...........igo]
10 : 72 02 69 6f 00 00 01 00 01 [r.io.....]
$loop = React\EventLoop\Factory::create();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->create('8.8.8.8', $loop);
$dns->lookup('ipv6.google.com', 'AAAA')->then(function($response)
{
\React\Dns\Protocol\HumanParser::dumpHex($response->data);
});
$loop->run();The output would be something like:
0 : 9c be 81 80 00 01 00 02 00 00 00 00 04 69 70 76 [.............ipv]
10 : 36 06 67 6f 6f 67 6c 65 03 63 6f 6d 00 00 1c 00 [6.google.com....]
20 : 01 c0 0c 00 05 00 01 00 00 53 f7 00 09 04 69 70 [.........S....ip]
30 : 76 36 01 6c c0 11 c0 2d 00 1c 00 01 00 00 00 c3 [v6.l...-........]
40 : 00 10 26 07 f8 b0 40 00 08 04 00 00 00 00 00 00 [..&...@.........]
50 : 10 00 [..]
To debug Header flags of RFC 1035 @ 4.1.1. Header section format try the following:
$request = new \React\Dns\Model\Message();
$request->header->set('id', 0x7262);
$request->header->set('qr', 0);
$request->header->set('tc', 1);
$request->header->set('rd', 1);
$dumper = new \React\Dns\Protocol\BinaryDumper();
$data = $dumper->toBinary($request);
// header flags is octet 3-4
list($fields) = array_values(unpack('n', substr($data, 2, 2)));
echo \React\Dns\Protocol\HumanParser::explainHeaderFlagsBinary($fields);The output would be: Flags Value: 300 16 Bit Binary: 0000001100000000
Flag: Binary Value [Explanation]
QR: 0 [0 = Query, 1 = Response]
Opcode: 0000 [Decimal value 0 = standard query]
AA: 0 [1 = Authoritative Answer]
TC: 1 [1 = Message truncated]
RD: 1 [1 = Recursion Desired]
RA: 0 [1 = Recursion Available]
Z: 000 [Future use]
RCODE: 0000 [Human value = OK]