[Dns] Initial dns resolving code

Author: igorw

BinaryDumper.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace React\Dns;
+
+class BinaryDumper
+{
+    public function toBinary(Message $message)
+    {
+    }
+}

Message.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace React\Dns;
+
+class Message
+{
+    const TYPE_A = 1;
+    const TYPE_NS = 2;
+    const TYPE_CNAME = 5;
+    const TYPE_SOA = 6;
+    const TYPE_PTR = 12;
+    const TYPE_MX = 15;
+    const TYPE_TXT = 16;
+
+    const CLASS_IN = 1;
+
+    const OPCODE_QUERY = 0;
+    const OPCODE_IQUERY = 1; // inverse query
+    const OPCODE_STATUS = 2;
+
+    public $data = '';
+
+    public $header = array();
+    public $question = array();
+    public $answer = array();
+    public $authority = array();
+    public $additional = array();
+
+    public function getId()
+    {
+        return $this->header['id'];
+    }
+
+    public function isQuery()
+    {
+        return 0 === $this->header['qr'];
+    }
+
+    public function isResponse()
+    {
+        return 1 === $this->header['qr'];
+    }
+}

Parser.php

@@ -0,0 +1,105 @@
+<?php
+
+namespace React\Dns;
+
+/**
+ * DNS protocol parser
+ *
+ * Obsolete and uncommon types and classes are not implemented.
+ */
+class Parser
+{
+    public function parseChunk($data, Message $message)
+    {
+        $message->data .= $data;
+
+        if (!$message->header) {
+            if (!$this->parseHeader($message)) {
+                return;
+            }
+        }
+
+        if ($message->header['qdCount'] != count($message->question)) {
+            if (!$this->parseQuestion($message)) {
+                return;
+            }
+        }
+    }
+
+    private function parseHeader(Message $message)
+    {
+        if (strlen($message->data) < 12) {
+            return;
+        }
+
+        $header = substr($message->data, 0, 12);
+        $message->data = substr($message->data, 12);
+
+        list($id, $fields, $qdCount, $anCount, $nsCount, $arCount) = array_merge(unpack('n*', $header));
+
+        $rcode = $fields & chr(bindec('1111'));
+        $z = ($fields >> 4) & chr(bindec('111'));
+        $ra = ($fields >> 7) & 1;
+        $rd = ($fields >> 8) & 1;
+        $tc = ($fields >> 9) & 1;
+        $aa = ($fields >> 10) & 1;
+        $opcode = ($fields >> 11) & chr(bindec('1111'));
+        $qr = ($fields >> 15) & 1;
+
+        $message->header = compact('id', 'qdCount', 'anCount', 'nsCount', 'arCount',
+                                    'qr', 'opcode', 'aa', 'tc', 'rd', 'ra', 'z', 'rcode');
+
+        return $message;
+    }
+
+    private function parseQuestion(Message $message)
+    {
+        if (strlen($message->data) < 2) {
+            return;
+        }
+
+        $labels = array();
+
+        $consumed = 0;
+
+        $length = ord(substr($message->data, $consumed, 1));
+        $consumed += 1;
+
+        if (strlen($message->data) - $consumed < $length) {
+            return;
+        }
+
+        while ($length !== 0) {
+            $labels[] = substr($message->data, $consumed, $length);
+            $consumed += $length;
+
+            $length = ord(substr($message->data, $consumed, 1));
+            $consumed += 1;
+
+            if (strlen($message->data) - $consumed < $length) {
+                return;
+            }
+        }
+
+        list($type, $class) = array_merge(unpack('n*', substr($message->data, $consumed, 4)));
+        $consumed += 4;
+
+        $message->data = substr($message->data, 0, $consumed);
+
+        $message->question[] = array(
+            'name' => implode('.', $labels),
+            'type' => $type,
+            'class' => $class,
+        );
+
+        if ($message->header['qdCount'] != count($message->question)) {
+            return $this->parseQuestion($message);
+        }
+
+        return $message;
+    }
+
+    public function toBinary(Message $message)
+    {
+    }
+}

Query.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace React\Dns;
+
+class Query
+{
+    public $name;
+    public $type;
+    public $class;
+}

Record.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace React\Dns;
+
+class Record
+{
+    public $name;
+    public $type;
+    public $class;
+    public $ttl;
+    public $data;
+}

Resolver.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace React\Dns;
+
+use React\Socket\Connection;
+
+class Resolver
+{
+    public function resolve($domain, $callback)
+    {
+        $nameserver = '8.8.8.8';
+        $query = new Query($domain, 'A', 'IN');
+
+        $this->query($nameserver, $query, function (Message $response) use ($callback) {
+            $answer = $response->answer[array_rand($response->answer)]->data->address;
+            $callback($address);
+        });
+    }
+
+    public function query($nameserver, Query $query, $callback)
+    {
+        $dumper = new BinaryDumper();
+        $parser = new Parser();
+
+        $message = new Message();
+        $message->header = array(
+            $query...
+        );
+        $message->question = array(
+            $query...
+        );
+
+        $response = new Message();
+
+        $conn = new Connection(fopen("udp://$nameserver:53"), $this->loop);
+        $conn->on('data', function ($data) use ($conn, $response, $callback) {
+            if ($parser->parseChunk($data, $response)) {
+                $conn->end();
+                $callback($response);
+            }
+        });
+        $conn->write($dumper->toBinary($message));
+    }
+}

composer.json

@@ -0,0 +1,14 @@
+{
+    "name": "react/dns",
+    "description": "Async DNS resolver.",
+    "keywords": ["dns", "dns-resolver"],
+    "license": "MIT",
+    "require": {
+        "php": ">=5.3.2",
+        "react/socket": "dev-master"
+    },
+    "autoload": {
+        "psr-0": { "React\\Dns": "" }
+    },
+    "target-dir": "React/Dns"
+}