From 2c8133a7b4267ba570f473abe4b08b01a0c8238a Mon Sep 17 00:00:00 2001
From: Niklas Keller <me@kelunik.com>
Date: Wed, 10 Jan 2018 17:26:11 +0100
Subject: [PATCH] Allow empty domain names to be decoded

This is a rather long standing issue. LibDNS didn't allow to decode empty domain names. Empty domain names were previously only observed with PTR records, but were now also observed in regular queries in authoritative records that include the root nameservers.

LibDNS 2.0 mainly adds scalar types has just a few breaking changes. We don't expose it anywhere, so an upgrade is perfectly fine.

Fixes #53.
---
 composer.json           |  2 +-
 lib/Internal/Socket.php |  2 +-
 test/DecodeTest.php     | 21 +++++++++++++++++++++
 3 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 test/DecodeTest.php

diff --git a/composer.json b/composer.json
index db074ff..77ced0c 100644
--- a/composer.json
+++ b/composer.json
@@ -42,7 +42,7 @@
         "amphp/parser": "^1",
         "amphp/uri": "^0.1",
         "amphp/windows-registry": "^0.3",
-        "daverandom/libdns": "^1"
+        "daverandom/libdns": "^2.0.1"
     },
     "require-dev": {
         "amphp/phpunit-util": "^1",
diff --git a/lib/Internal/Socket.php b/lib/Internal/Socket.php
index dc5e7cd..f17ce52 100644
--- a/lib/Internal/Socket.php
+++ b/lib/Internal/Socket.php
@@ -237,7 +237,7 @@ abstract class Socket {
             return false;
         }
 
-        $questionRecord = $questionRecords->current();
+        $questionRecord = $questionRecords->getIterator()->current();
 
         if ($questionRecord->getClass() !== $question->getClass()) {
             return false;
diff --git a/test/DecodeTest.php b/test/DecodeTest.php
new file mode 100644
index 0000000..05ffe14
--- /dev/null
+++ b/test/DecodeTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Amp\Dns\Test;
+
+use Amp\PHPUnit\TestCase;
+use LibDNS\Decoder\DecoderFactory;
+use LibDNS\Messages\Message;
+
+class DecodeTest extends TestCase {
+    /**
+     * Regression test for https://github.com/amphp/dns/issues/53 and other reported issues.
+     */
+    public function testDecodesEmptyDomains() {
+        $message = hex2bin("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");
+
+        $decoder = (new DecoderFactory)->create();
+        $response = $decoder->decode($message);
+
+        $this->assertInstanceOf(Message::class, $response);
+    }
+}