Enable parsing of answers without question for mDNS

README.md

@@ -31,6 +31,10 @@ var Packet = function () {
 
 ## History
 
+###### 0.1.1 - October 5, 2014
+
+- Fixing NPM tagging issue...
+
 ###### 0.1.0 - October 2, 2014
 
 - Added TLSA support

package.json

@@ -1,6 +1,6 @@
 {
   "name": "native-dns-packet",
-  "version": "0.1.0",
+  "version": "0.1.1",
   "authors": [
     "Timothy J Fontaine <[email protected]> (http://atxconsulting.com)",
     "Greg Slepak <[email protected]> (https://twitter.com/taoeffect)",

packet.js

@@ -169,9 +169,8 @@ function writeHeader(buff, packet) {
   val += (packet.header.res3 << 4) & 0x10;
   val += packet.header.rcode & 0xF;
   buff.writeUInt16BE(val & 0xFFFF);
-  assert(packet.question.length == 1, 'DNS requires one question');
-  // aren't used
-  buff.writeUInt16BE(1);
+  // question offset 4
+  buff.writeUInt16BE(packet.question.length & 0xFFFF);
   // answer offset 6
   buff.writeUInt16BE(packet.answer.length & 0xFFFF);
   // authority offset 8
@@ -233,7 +232,6 @@ function writeQuestion(buff, val, label_index) {
   namePack(val.name, buff, label_index);
   buff.writeUInt16BE(val.type & 0xFFFF);
   buff.writeUInt16BE(val.class & 0xFFFF);
-  return WRITE_RESOURCE_RECORD;
 }
 
 function writeResource(buff, val, label_index, rdata) {
@@ -411,14 +409,21 @@ Packet.write = function(buff, packet) {
       switch (state) {
         case WRITE_HEADER:
           state = writeHeader(buff, packet);
+          count = 0;
           break;
         case WRITE_TRUNCATE:
           state = writeTruncate(buff, packet, section, last_resource);
           break;
         case WRITE_QUESTION:
-          state = writeQuestion(buff, packet.question[0], label_index);
-          section = 'answer';
-          count = 0;
+          if(count === packet.question.length) {
+            state = WRITE_RESOURCE_RECORD;
+            section = 'answer';
+            count = 0;
+          }
+          else {
+            writeQuestion(buff, packet.question[count], label_index);
+            count += 1
+          }
           break;
         case WRITE_RESOURCE_RECORD:
           last_resource = buff.tell();
@@ -521,13 +526,20 @@ function parseHeader(msg, packet) {
 }
 
 function parseQuestion(msg, packet) {
-  var val = {};
-  val.name = nameUnpack(msg);
-  val.type = msg.readUInt16BE();
-  val.class = msg.readUInt16BE();
-  packet.question[0] = val;
-  assert(packet.question.length === 1);
-  // TODO handle qdcount > 1 in practice no one sends this
+  if (packet.header.opcode === 0 && // Standard query
+    packet.header.qr === 1 && // Response
+    packet.question.length === 0) { // Empty question can occur in mDNS
+    return PARSE_RESOURCE_RECORD;
+  }
+  var qnum = packet.question.length;
+  while (qnum > 0) {
+    var val = {};
+    val.name = nameUnpack(msg);
+    val.type = msg.readUInt16BE();
+    val.class = msg.readUInt16BE();
+    packet.question[packet.question.length - qnum] = val;
+    qnum -= 1;
+  }
   return PARSE_RESOURCE_RECORD;
 }
 
@@ -678,7 +690,7 @@ var
   PARSE_OPT   = consts.NAME_TO_QTYPE.OPT,
   PARSE_SPF   = consts.NAME_TO_QTYPE.SPF,
   PARSE_TLSA  = consts.NAME_TO_QTYPE.TLSA;
-  
+
 
 Packet.parse = function(msg) {
   var state,

test/fixtures/chromecast.js

@@ -0,0 +1,45 @@
+{ header: 
+   { id: 0,
+     qr: 0,
+     opcode: 0,
+     aa: 0,
+     tc: 0,
+     rd: 0,
+     ra: 0,
+     res1: 0,
+     res2: 0,
+     res3: 0,
+     rcode: 0 },
+  question: 
+   [ { name: '_googlecast._tcp.local', type: 12, class: 32769 },
+     { name: 'TV i Vardagsrummet._googlecast._tcp.local',
+       type: 33,
+       class: 32769 },
+     { name: 'TV i Vardagsrummet._googlecast._tcp.local',
+       type: 16,
+       class: 32769 },
+     { name: 'SkC$rm i GC$strummet._googlecast._tcp.local',
+       type: 33,
+       class: 32769 },
+     { name: 'SkC$rm i GC$strummet._googlecast._tcp.local',
+       type: 16,
+       class: 32769 },
+     { name: 'TV i Vardagsrummet.local', type: 1, class: 32769 },
+     { name: 'TV i Vardagsrummet.local', type: 28, class: 32769 },
+     { name: 'SkC$rm i GC$strummet.local', type: 1, class: 32769 },
+     { name: 'SkC$rm i GC$strummet.local', type: 28, class: 32769 } ],
+  answer: 
+   [ { name: '_googlecast._tcp.local',
+       type: 12,
+       class: 1,
+       ttl: 2477,
+       data: 'TV i Vardagsrummet._googlecast._tcp.local' },
+     { name: '_googlecast._tcp.local',
+       type: 12,
+       class: 1,
+       ttl: 2473,
+       data: 'SkC$rm i GC$strummet._googlecast._tcp.local' } ],
+  authority: [],
+  additional: [],
+  edns_options: [],
+  payload: undefined }

test/fixtures/mdns.readynas.js

@@ -0,0 +1,83 @@
+{ header: 
+   { id: 0,
+     qr: 1,
+     opcode: 0,
+     aa: 1,
+     tc: 0,
+     rd: 0,
+     ra: 0,
+     res1: 0,
+     res2: 0,
+     res3: 0,
+     rcode: 0 },
+  question: [],
+  answer: 
+   [ { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_transmissionserver._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_ssh._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_https._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_workstation._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_afpovertcp._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_readynas._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_ftp._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_pdl-datastream._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_sftp-ssh._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_googlecast._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_smb._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_udisks-ssh._tcp.local' },
+     { name: '_services._dns-sd._udp.local',
+       type: 12,
+       class: 1,
+       ttl: 3599,
+       data: '_http._tcp.local' } ],
+  authority: [],
+  additional: [],
+  edns_options: [],
+  payload: undefined }