Merge pull request #105 from clue-labs/txt

Support parsing TXT records

Author: WyriHaximus

examples/11-query-any.php

@@ -37,6 +37,12 @@
             case Message::TYPE_CNAME:
                 $type = 'CNAME';
                 break;
+            case Message::TYPE_TXT:
+                // TXT records can contain a list of (binary) strings for each record.
+                // here, we assume this is printable ASCII and simply concatenate output
+                $type = 'TXT';
+                $data = implode('', $data);
+                break;
             default:
                 // unknown type uses HEX format
                 $type = 'Type ' . $answer->type;

src/Model/Record.php

@@ -37,6 +37,17 @@ class Record
      *   IPv6 address string, for example "::1".
      * - CNAME / PTR / NS:
      *   The hostname without trailing dot, for example "reactphp.org".
+     * - TXT:
+     *   List of string values, for example `["v=spf1 include:example.com"]`.
+     *   This is commonly a list with only a single string value, but this
+     *   technically allows multiple strings (0-255 bytes each) in a single
+     *   record. This is rarely used and depending on application you may want
+     *   to join these together or handle them separately. Each string can
+     *   transport any binary data, its character encoding is not defined (often
+     *   ASCII/UTF-8 in practice). [RFC 1464](https://tools.ietf.org/html/rfc1464)
+     *   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).
      * - 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
@@ -45,7 +56,7 @@ class Record
      *   considered a BC break. See the format definition of known types above
      *   for more details.
      *
-     * @var string
+     * @var string|string[]
      */
     public $data;
 

src/Protocol/Parser.php

@@ -168,6 +168,15 @@ public function parseAnswer(Message $message)
             list($bodyLabels, $consumed) = $this->readLabels($message->data, $consumed);
 
             $rdata = implode('.', $bodyLabels);
+        } elseif (Message::TYPE_TXT === $type) {
+            $rdata = array();
+            $remaining = $rdLength;
+            while ($remaining) {
+                $len = ord($message->data[$consumed]);
+                $rdata[] = substr($message->data, $consumed + 1, $len);
+                $consumed += $len + 1;
+                $remaining -= $len + 1;
+            }
         } else {
             // unknown types simply parse rdata as an opaque binary string
             $rdata = substr($message->data, $consumed, $rdLength);

tests/Protocol/ParserTest.php

@@ -256,6 +256,56 @@ public function testParseAAAAResponse()
         $this->assertSame('2a00:1450:4009:809::200e', $response->answers[0]->data);
     }
 
+    public function testParseTXTResponse()
+    {
+        $data = "";
+        $data .= "04 69 67 6f 72 02 69 6f 00";          // answer: igor.io
+        $data .= "00 10 00 01";                         // answer: type TXT, class IN
+        $data .= "00 01 51 80";                         // answer: ttl 86400
+        $data .= "00 06";                               // answer: rdlength 6
+        $data .= "05 68 65 6c 6c 6f";                   // answer: rdata length 5: 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_TXT, $response->answers[0]->type);
+        $this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
+        $this->assertSame(86400, $response->answers[0]->ttl);
+        $this->assertSame(array('hello'), $response->answers[0]->data);
+    }
+
+    public function testParseTXTResponseMultiple()
+    {
+        $data = "";
+        $data .= "04 69 67 6f 72 02 69 6f 00";          // answer: igor.io
+        $data .= "00 10 00 01";                         // answer: type TXT, class IN
+        $data .= "00 01 51 80";                         // answer: ttl 86400
+        $data .= "00 0C";                               // answer: rdlength 12
+        $data .= "05 68 65 6c 6c 6f 05 77 6f 72 6c 64"; // answer: rdata length 5: hello, length 5: world
+
+        $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_TXT, $response->answers[0]->type);
+        $this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
+        $this->assertSame(86400, $response->answers[0]->ttl);
+        $this->assertSame(array('hello', 'world'), $response->answers[0]->data);
+    }
+
     public function testParseResponseWithTwoAnswers()
     {
         $data = "";