Google DNS over HTTPS resolver

composer.json

@@ -25,13 +25,14 @@
         }
     ],
     "require": {
-        "react/socket": "^0.8.10",
-        "react/datagram": "^1.4",
-        "php": "~7.1",
+        "ext-curl": "*",
         "ext-json": "~1.0",
         "ext-simplexml": "*",
-        "symfony/event-dispatcher": "~4.0",
-        "psr/log": "^1.0"
+        "php": "~7.1",
+        "psr/log": "^1.0",
+        "react/datagram": "^1.4",
+        "react/socket": "^0.8.10",
+        "symfony/event-dispatcher": "~4.0"
     },
     "autoload": {
         "psr-4": {

docs/Google-DNS.md

@@ -0,0 +1,12 @@
+# Google DNS
+
+Resolver class `GoogleDns.php` uses Google's DNS-over-HTTPS service to
+resolve records. GoogleDNS resolver could be used as a drop in replacement
+instead of `SystemResolver` to avoid eavesdropping on DNS requests.
+
+Upon DNS query server will issue HTTPS request to Google service and obtain
+information on query, information will further be delivered to client in form of DNS response.
+
+Resolver at the moment supports `A` and `AAAA` type records.
+
+For more information refer to: https://developers.google.com/speed/public-dns/docs/dns-over-https

example/google-dns-example.php

@@ -0,0 +1,14 @@
+<?php
+
+require_once __DIR__.'/../vendor/autoload.php';
+
+$stackableResolver = new yswery\DNS\Resolver\StackableResolver([
+    new yswery\DNS\Resolver\GoogleDnsResolver()
+]);
+
+$eventDispatcher = new \Symfony\Component\EventDispatcher\EventDispatcher();
+$eventDispatcher->addSubscriber(new \yswery\DNS\EchoLogger());
+
+$server = new yswery\DNS\Server($stackableResolver, $eventDispatcher);
+
+$server->start();

src/Resolver/GoogleDnsResolver.php

@@ -0,0 +1,130 @@
+<?php
+
+namespace yswery\DNS\Resolver;
+
+use yswery\DNS\RecordTypeEnum;
+use yswery\DNS\ResourceRecord;
+
+class GoogleDnsResolver extends AbstractResolver
+{
+    private const API_ENDPOINT = 'https://dns.google.com/resolve';
+
+    private const ANSWER_FIELD_NAME = 'Answer';
+
+    private const NAME_QUERY_PARAM = 'name';
+    private const TYPE_QUERY_PARAM = 'type';
+    private const TTL_FIELD_NAME = 'TTL';
+    private const DATA_FIELD_NAME = 'data';
+
+    /** @var int */
+    private $defaultTtl;
+
+    public function __construct($defaultTtl = 300)
+    {
+        $this->allowRecursion = true;
+        $this->isAuthoritative = true;
+        $this->defaultTtl = $defaultTtl;
+    }
+
+    /**
+     * @param ResourceRecord[] $queries
+     *
+     * @return ResourceRecord[]
+     */
+    public function getAnswer(array $queries): array
+    {
+        $answers = [];
+        foreach ($queries as $query) {
+            $response = $this->request($query->getName(), $query->getType());
+            $answers[] = $this->createAnswer($query, $response);
+        }
+
+        return array_merge(...$answers);
+    }
+
+    /**
+     * @param ResourceRecord $query
+     *
+     * @param array|null     $response
+     *
+     * @return ResourceRecord[]
+     */
+    public function createAnswer(ResourceRecord $query, ?array $response): array
+    {
+        $answers = [];
+
+        if (!is_array($response)) {
+            return [$this->getEmptyAnswer($query)];
+        }
+
+        if (!isset($response[self::ANSWER_FIELD_NAME]) || empty($response[self::ANSWER_FIELD_NAME])) {
+            return [$this->getEmptyAnswer($query)];
+        }
+
+        foreach ($response[self::ANSWER_FIELD_NAME] as $item) {
+            $answer = $this->getEmptyAnswer($query);
+
+            $answer->setTtl($item[self::TTL_FIELD_NAME] ?? $this->defaultTtl);
+
+            if ($query->getType() === RecordTypeEnum::TYPE_A && isset($item[self::DATA_FIELD_NAME])) {
+                $answer->setRdata($item[self::DATA_FIELD_NAME]);
+            }
+
+            if ($query->getType() === RecordTypeEnum::TYPE_AAAA && isset($item[self::DATA_FIELD_NAME])) {
+                $answer->setRdata($item[self::DATA_FIELD_NAME]);
+            }
+
+            $answers[] = $answer;
+        }
+
+        return $answers;
+    }
+
+    /**
+     * @param string $name
+     * @param string $type
+     *
+     * @return array|null
+     */
+    private function request(string $name, string $type): ?array
+    {
+        $session = curl_init();
+
+        $query = [
+            self::NAME_QUERY_PARAM => $name,
+            self::TYPE_QUERY_PARAM => $type,
+        ];
+
+        $url = self::API_ENDPOINT.'?'.http_build_query($query);
+
+        curl_setopt($session, CURLOPT_RETURNTRANSFER, true);
+        curl_setopt($session, CURLOPT_URL, $url);
+
+        $response = curl_exec($session);
+
+        curl_close($session);
+
+        $response = json_decode($response, true);
+
+        if (json_last_error() !== JSON_ERROR_NONE) {
+            return null;
+        }
+
+        return $response;
+    }
+
+    /**
+     * @param ResourceRecord $query
+     *
+     * @return ResourceRecord
+     */
+    private function getEmptyAnswer(ResourceRecord $query): ResourceRecord
+    {
+        $answer = new ResourceRecord();
+        $answer->setName($query->getName());
+        $answer->setType($query->getType());
+        $answer->setTtl($this->defaultTtl);
+
+        return $answer;
+    }
+}

src/Server.php

@@ -95,7 +95,7 @@ public function start(): void
      * @param string          $address
      * @param SocketInterface $socket
      */
-    public function onMessage(string $message, string $address, SocketInterface $socket)
+    public function onMessage(string $message, string $address, SocketInterface $socket): void
     {
         try {
             $this->dispatcher->dispatch(Events::MESSAGE, new MessageEvent($socket, $address, $message));

src/Tests/Resolver/GoogleDnsResolveTest.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace yswery\DNS\Tests\Resolver;
+
+use PHPUnit\Framework\TestCase;
+use yswery\DNS\RecordTypeEnum;
+use yswery\DNS\Resolver\GoogleDnsResolver;
+use yswery\DNS\ResourceRecord;
+
+class GoogleDnsResolveTest extends TestCase
+{
+    private const EXAMPLE_QUERY = 'apple.com.';
+
+    /**
+     * @var GoogleDnsResolver
+     */
+    protected $resolver;
+
+    /**
+     * @var array
+     */
+    protected $successResponse;
+
+    /**
+     * @var array
+     */
+    protected $failureResponse;
+
+    public function setUp()
+    {
+        $this->resolver = new GoogleDnsResolver(300);
+
+        $this->failureResponse = json_decode(
+            file_get_contents(__DIR__.'/../Resources/google-dns-query-failure.json'),
+            true
+        );
+        $this->successResponse = json_decode(
+            file_get_contents(__DIR__.'/../Resources/google-dns-query-success.json'),
+            true
+        );
+    }
+
+    public function testRecordResolve(): void
+    {
+        $query = (new ResourceRecord())
+            ->setName(self::EXAMPLE_QUERY)
+            ->setType(RecordTypeEnum::TYPE_A)
+            ->setQuestion(true);
+
+        $answers = $this->resolver->createAnswer($query, $this->successResponse);
+
+        static::assertArrayHasKey(0, $answers);
+
+        $answer = $answers[0];
+
+        static::assertEquals('apple.com.', $answer->getName());
+        static::assertEquals(RecordTypeEnum::TYPE_A, $answer->getType());
+        static::assertEquals(3599, $answer->getTtl());
+        static::assertEquals('17.178.96.59', $answer->getRdata());
+    }
+
+    public function testRecordFailedToResolve() {
+        $query = (new ResourceRecord())
+            ->setName(self::EXAMPLE_QUERY)
+            ->setType(RecordTypeEnum::TYPE_A)
+            ->setQuestion(true);
+
+        $answers = $this->resolver->createAnswer($query, $this->failureResponse);
+
+        static::assertArrayHasKey(0, $answers);
+
+        $answer = $answers[0];
+
+        static::assertEquals(self::EXAMPLE_QUERY, $answer->getName());
+        static::assertEquals(RecordTypeEnum::TYPE_A, $answer->getType());
+        static::assertEquals(300, $answer->getTtl());
+        static::assertEquals(null, $answer->getRdata());
+    }
+}

src/Tests/Resources/google-dns-query-failure.json

@@ -0,0 +1,16 @@
+{
+  "Status": 2,
+  "TC": false,
+  "RD": true,
+  "RA": true,
+  "AD": false,
+  "CD": false,
+  "Question":
+  [
+    {
+      "name": "dnssec-failed.org.",
+      "type": 1
+    }
+  ],
+  "Comment": "DNSSEC validation failure. Please check http://dnsviz.net/d/dnssec-failed.org/dnssec/."
+}

src/Tests/Resources/google-dns-query-success.json

@@ -0,0 +1,38 @@
+{
+  "Status": 0,
+  "TC": false,
+  "RD": true,
+  "RA": true,
+  "AD": false,
+  "CD": false,
+  "Question":
+  [
+    {
+      "name": "apple.com.",
+      "type": 1
+    }
+  ],
+  "Answer":
+  [
+    {
+      "name": "apple.com.",
+      "type": 1,
+      "TTL": 3599,
+      "data": "17.178.96.59"
+    },
+    {
+      "name": "apple.com.",
+      "type": 1,
+      "TTL": 3599,
+      "data": "17.172.224.47"
+    },
+    {
+      "name": "apple.com.",
+      "type": 1,
+      "TTL": 3599,
+      "data": "17.142.160.59"
+    }
+  ],
+  "Additional": [ ],
+  "edns_client_subnet": "12.34.56.78/0"
+}