Packer works!

dns.packer.js

@@ -47,7 +47,17 @@ var dnspack = exports.DNS_PACKER = {
       }
     }
 
-    function packLabel(sequence, terminates) {
+    function packLabelSequence(sequence, terminates) {
+      console.log('sequence:', sequence);
+      if (labelsMap[sequence]) {
+        console.log('cached sequence:', sequence);
+        // minimal compression pointer 0xc0 (192)
+        dv.setUint8(total, 0xc0, false);
+        total += 1;
+        dv.setUint8(total, labelsMap[sequence].total, false);
+        total += 1;
+        return;
+      }
       if (terminates) {
         // we don't want non-terminating rdata cached, just terminating names
         labelsMap[total] = { total: total, name: sequence };
@@ -62,19 +72,22 @@ var dnspack = exports.DNS_PACKER = {
           total += 1;
         });
       });
+      if (terminates) {
+        // trailing 0 (null) as label sequence terminator
+        dv.setUint8(total, 0, false);
+        total += 1;
+      }
     }
 
     function packQuestion(q) {
       lint(q);
 
-      packLabel(q.name);
-      // trailing 0 (null) as label sequence terminator
-      dv.setUint8(total, 0, false);
-      total += 1;
+      packLabelSequence(q.name, true);
 
       dv.setUint16(total, q.type, false);
-      dv.setUint16(total + 2, q.class, false);
-      total += 4; // two bytes type two bytes class
+      total += 2;
+      dv.setUint16(total, q.class, false);
+      total += 2;
     }
 
     function packAnswer(a) {

dns.packer.type.a.js

@@ -8,8 +8,12 @@ exports.DNS_PACKER_TYPE_A = function (ab, dv, total, record) {
     throw new Error("no address on A record");
   }
 
+  // RDLENGTH
+  dv.setUint16(total, 4, false);
+  total += 2;
+
+  // RDATA
   // i.e. 127.0.0.1 => 0x7F, 0x00, 0x00, 0x01
-  //record.rdlength = 4;
   record.address.split('.').forEach(function (octet) {
     dv.setUint8(total, parseInt(octet, 10), false);
     total += 1;

dns.packer.type.aaaa.js

@@ -23,6 +23,12 @@ exports.DNS_PACKER_TYPE_AAAA = function (ab, dv, total, record) {
       }
     }
   });
+
+  // RDLENGTH
+  dv.setUint16(total, 16, false);
+  total += 2;
+
+  // RDATA
   parts.forEach(function (sedectet) {
     dv.setUint16(total, parseInt(sedectet, 16), false);
     total += 2;