more helpful error

dns.parser.js

@@ -58,11 +58,11 @@ pdns.unpack = function (ab) {
   // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView
   var dv = new DataView(ab);
   var id = dv.getUint16(0, false);
-      packet.header = pdns.unpackHeader(dv.getUint16(2, false));
+  packet.header = pdns.unpackHeader(dv.getUint16(2, false));
-  var qdcount = dv.getUint16(4, false);  // query count
+  packet.qdcount = dv.getUint16(4, false);  // query count
-  var ancount = dv.getUint16(6, false);  // answer count
+  packet.ancount = dv.getUint16(6, false);  // answer count
-  var nscount = dv.getUint16(8, false);  // authority count
+  packet.nscount = dv.getUint16(8, false);  // authority count
-  var arcount = dv.getUint16(10, false); // additional count
+  packet.arcount = dv.getUint16(10, false); // additional count
   var total = 12;
   var i;
   var rec;
@@ -114,6 +114,7 @@ pdns.unpack = function (ab) {
 
   function unpackAnswer(ab, dv, ui8, total) {
     var ototal = total;
+    var err;
     var q = pdns._unpackLabels(ui8, total, {
       name: ''
     , type: 0
@@ -136,10 +137,15 @@ pdns.unpack = function (ab) {
 
     if (ab.byteLength - total < 10) {
       // console.error(str.join(''));
-      throw new Error(
+      //console.error(JSON.stringify(packet, null, 1));
+      //console.error(JSON.stringify(q, null, 1));
+      err = new Error(
         "Expected a 2-byte QTYPE, 2-byte QCLASS, 4-byte TTL, and 2-byte RDLENGTH following " + total + "-byte QNAME"
           + " but packet itself has " + (ab.byteLength - total) + " bytes remaining"
       );
+      err.packet = packet;
+      err.record = q;
+      throw err;
     }
 
     q.type = dv.getUint16(total, false);
@@ -171,33 +177,33 @@ pdns.unpack = function (ab) {
   packet.header.id = id;
 
 
-  console.log('qdcount', qdcount);
+  console.log('qdcount', packet.qdcount);
   packet.question = [];
-  for (i = 0; i < qdcount; i += 1) {
+  for (i = 0; i < packet.qdcount; i += 1) {
     rec = unpackQuestion(ab, dv, ui8, total);
     total += rec.byteLength;
     packet.question.push(rec);
   }
 
-  console.log('ancount', ancount);
+  console.log('ancount', packet.ancount);
   packet.answer = [];
-  for (i = 0; i < ancount; i += 1) {
+  for (i = 0; i < packet.ancount; i += 1) {
     rec = unpackAnswer(ab, dv, ui8, total);
     total += rec.byteLength;
     packet.answer.push(rec);
   }
 
-  console.log('nscount', nscount);
+  console.log('nscount', packet.nscount);
   packet.authority = [];
-  for (i = 0; i < nscount; i += 1) {
+  for (i = 0; i < packet.nscount; i += 1) {
     rec = unpackAnswer(ab, dv, ui8, total);
     total += rec.byteLength;
     packet.authority.push(rec);
   }
 
-  console.log('arcount', arcount);
+  console.log('arcount', packet.arcount);
   packet.additional = [];
-  for (i = 0; i < arcount; i += 1) {
+  for (i = 0; i < packet.arcount; i += 1) {
     rec = unpackAnswer(ab, dv, ui8, total);
     total += rec.byteLength;
     packet.additional.push(rec);

test/parser.js

@@ -8,6 +8,7 @@
   var path = require('path');
   var dnsjs = require('../').DNSPacket;
   var expected; // shim
+  var onefile = process.argv[2];
 
   var dirname = path.join(__dirname, 'fixtures');
 
@@ -42,6 +43,9 @@
   }
 
   fs.readdirSync(dirname).forEach(function (name) {
+    if (onefile && !onefile.split(',').some(function (f) { return name.match(onefile); })) {
+      return;
+    }
     if (!/\.bin$/.test(name)) {
       return;
     }
@@ -58,8 +62,11 @@
     try {
       result = dnsjs.parse(ab);
     } catch(e) {
+      console.error('[Error] parse error');
       console.log(ab);
-      console.error('[Error] ' + e.message);
+      console.error(e.packet);
+      console.error(e.record);
+      console.error(e.stack);
       console.error('');
       //console.error(e.stack);
       return;