Support serializing legacy SPF type

Author: clue

src/Model/Message.php

@@ -34,7 +34,16 @@ final class Message
      * The OPT record uses the "ttl" field to store additional flags.
      */
     const TYPE_OPT = 41;
-    const TYPE_SPF = 99; // Sender Policy Framework (SPF) - https://tools.ietf.org/html/rfc4408#section-3.1.1
+
+    /**
+     * Sender Policy Framework (SPF) had a dedicated SPF type which has been
+     * deprecated in favor of reusing the existing TXT type.
+     *
+     * @deprecated https://datatracker.ietf.org/doc/html/rfc7208#section-3.1
+     * @see self::TYPE_TXT
+     */
+    const TYPE_SPF = 99;
+
     const TYPE_ANY = 255;
     const TYPE_CAA = 257;
 

src/Protocol/BinaryDumper.php

@@ -92,6 +92,7 @@ private function recordsToBinary(array $records)
                     $binary = $this->domainNameToBinary($record->data);
                     break;
                 case Message::TYPE_TXT:
+                case Message::TYPE_SPF:
                     $binary = $this->textsToBinary($record->data);
                     break;
                 case Message::TYPE_MX:

tests/Protocol/BinaryDumperTest.php

@@ -385,7 +385,7 @@ public function testToBinaryForResponseWithPTRRecordWithSpecialCharactersEscaped
     public function testToBinaryForResponseWithMultipleAnswerRecords()
     {
         $data = "";
-        $data .= "72 62 01 00 00 01 00 06 00 00 00 00"; // header
+        $data .= "72 62 01 00 00 01 00 07 00 00 00 00"; // header
         $data .= "04 69 67 6f 72 02 69 6f 00";          // question: igor.io
         $data .= "00 ff 00 01";                         // question: type ANY, class IN
 
@@ -401,6 +401,10 @@ public function testToBinaryForResponseWithMultipleAnswerRecords()
         $data .= "00 10 00 01 00 00 00 00 00 0c";       // answer: type TXT, class IN, TTL 0, 12 bytes
         $data .= "05 68 65 6c 6c 6f 05 77 6f 72 6c 64"; // answer: hello, world
 
+        $data .= "04 69 67 6f 72 02 69 6f 00";          // answer: igor.io
+        $data .= "00 63 00 01 00 00 00 00 00 0c";       // answer: type SPF, class IN, TTL 0, 12 bytes
+        $data .= "0b 76 3d 73 70 66 31 20 2d 61 6c 6c"; // answer: v=spf1 -all
+
         $data .= "04 69 67 6f 72 02 69 6f 00";          // answer: igor.io
         $data .= "00 0f 00 01 00 00 00 00 00 03";       // answer: type MX, class IN, TTL 0, 3 bytes
         $data .= "00 00 00";                            // answer: … priority 0, no target
@@ -430,6 +434,7 @@ public function testToBinaryForResponseWithMultipleAnswerRecords()
         $response->answers[] = new Record('igor.io', Message::TYPE_A, Message::CLASS_IN, 0, '127.0.0.1');
         $response->answers[] = new Record('igor.io', Message::TYPE_AAAA, Message::CLASS_IN, 0, '::1');
         $response->answers[] = new Record('igor.io', Message::TYPE_TXT, Message::CLASS_IN, 0, array('hello', 'world'));
+        $response->answers[] = new Record('igor.io', Message::TYPE_SPF, Message::CLASS_IN, 0, array('v=spf1 -all'));
         $response->answers[] = new Record('igor.io', Message::TYPE_MX, Message::CLASS_IN, 0, array('priority' => 0, 'target' => ''));
         $response->answers[] = new Record('igor.io', Message::TYPE_CAA, Message::CLASS_IN, 0, array('flag' => 0, 'tag' => 'issue', 'value' => 'letsencrypt.org'));
         $response->answers[] = new Record('igor.io', Message::TYPE_SSHFP, Message::CLASS_IN, 0, array('algorithm' => 1, 'type' => '1', 'fingerprint' => '69ac090c'));