Support parsing MX records

examples/11-query-any.php

@@ -43,6 +43,11 @@
                 $type = 'TXT';
                 $data = implode('', $data);
                 break;
+            case Message::TYPE_MX:
+                // MX records contain "priority" and "target", only dump its values here
+                $type = 'MX';
+                $data = implode(' ', $data);
+                break;
             default:
                 // unknown type uses HEX format
                 $type = 'Type ' . $answer->type;

src/Model/Record.php

@@ -48,6 +48,14 @@ class Record
      *   suggests using key-value pairs such as `["name=test","version=1"]`, but
      *   interpretation of this is not enforced and left up to consumers of this
      *   library (used for DNS-SD/Zeroconf and others).
+     * - MX:
+     *   Mail server priority (UINT16) and target hostname without trailing dot,
+     *   for example `{"priority":10,"target":"mx.example.com"}`.
+     *   The payload data uses an associative array with fixed keys "priority"
+     *   (also commonly referred to as weight or preference) and "target" (also
+     *   referred to as exchange). If a response message contains multiple
+     *   records of this type, targets should be sorted by priority (lowest
+     *   first) - this is left up to consumers of this library (used for SMTP).
      * - Any other unknown type:
      *   An opaque binary string containing the RDATA as transported in the DNS
      *   record. For forwards compatibility, you should not rely on this format
@@ -56,7 +64,7 @@ class Record
      *   considered a BC break. See the format definition of known types above
      *   for more details.
      *
-     * @var string|string[]
+     * @var string|string[]|array
      */
     public $data;
 

src/Protocol/Parser.php

@@ -177,6 +177,14 @@ public function parseAnswer(Message $message)
                 $consumed += $len + 1;
                 $remaining -= $len + 1;
             }
+        } elseif (Message::TYPE_MX === $type) {
+            list($priority) = array_values(unpack('n', substr($message->data, $consumed, 2)));
+            list($bodyLabels, $consumed) = $this->readLabels($message->data, $consumed + 2);
+
+            $rdata = array(
+                'priority' => $priority,
+                'target' => implode('.', $bodyLabels)
+            );
         } else {
             // unknown types simply parse rdata as an opaque binary string
             $rdata = substr($message->data, $consumed, $rdLength);

tests/Protocol/ParserTest.php

@@ -306,6 +306,31 @@ public function testParseTXTResponseMultiple()
         $this->assertSame(array('hello', 'world'), $response->answers[0]->data);
     }
 
+    public function testParseMXResponse()
+    {
+        $data = "";
+        $data .= "04 69 67 6f 72 02 69 6f 00";          // answer: igor.io
+        $data .= "00 0f 00 01";                         // answer: type MX, class IN
+        $data .= "00 01 51 80";                         // answer: ttl 86400
+        $data .= "00 09";                               // answer: rdlength 9
+        $data .= "00 0a 05 68 65 6c 6c 6f 00";          // answer: rdata priority 10: hello
+
+        $data = $this->convertTcpDumpToBinary($data);
+
+        $response = new Message();
+        $response->header->set('anCount', 1);
+        $response->data = $data;
+
+        $this->parser->parseAnswer($response);
+
+        $this->assertCount(1, $response->answers);
+        $this->assertSame('igor.io', $response->answers[0]->name);
+        $this->assertSame(Message::TYPE_MX, $response->answers[0]->type);
+        $this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
+        $this->assertSame(86400, $response->answers[0]->ttl);
+        $this->assertSame(array('priority' => 10, 'target' => 'hello'), $response->answers[0]->data);
+    }
+
     public function testParseResponseWithTwoAnswers()
     {
         $data = "";