#!/usr/bin/env node

// node bin/debug.js ../dig.js/blar.DOEsNteXiST.AJ.OnEal.DAplIE.me.any.0.bin
// node bin/debugd.js ../dig.js/blar.DOEsNteXiST.AJ.OnEal.DAplIE.me.any.0.bin
// dig @localhost -p 65053 ANY DOEsNteXiST.AJ.OnEal.DAplIE.me
// dd if=../dig.js/blar.DOEsNteXiST.AJ.OnEal.DAplIE.me.any.0.bin of=blar.DOEsNteXiST.AJ.OnEal.DAplIE.me.any.0.trunc.bin bs=1 count=78
(function () {
'use strict';

var input = process.argv[2];
var fs = require('fs');
var nb = fs.readFileSync(input, null);

var ab = nb.buffer.slice(nb.byteOffset, nb.byteOffset + nb.byteLength);
var dv = new DataView(ab);

//
// read header
//
console.log('');
console.log('//////////////////');
console.log('//    HEADER    //');
console.log('//////////////////');
console.log('');

console.log('');
console.log('byte index 0x00');
console.log('');

console.log('id (int)', dv.getUint16(0));

var flags = dv.getUint16(2, false);
console.log('header 0x', flags.toString(16));
var flagsstr = ''
	+ 'qr ' + ((flags & 0x8000) >> 15) + ', '
  + 'opcode ' + ((flags & 0x7800) >> 11) + ', '
  + 'aa ' + ((flags &  0x400) >> 10) + ', '
  + 'tc ' + ((flags &  0x200) >>  9) + ', '
  + 'rd ' + ((flags &  0x100) >>  8) + ', '
  + 'ra ' + ((flags &   0x80) >>  7) + ', '
  + 'res1 ' + ((flags &   0x40) >>  6) + ', '
  + 'res2 ' + ((flags &   0x20) >>  5) + ', '
  + 'res3 ' + ((flags &   0x10) >>  4) + ', '
  + 'rcode ' + ((flags &    0xF));
console.log('(flags: ' + flagsstr);

var qdcount = dv.getUint16(4, false);  // query count
var ancount = dv.getUint16(6, false);  // answer count
var nscount = dv.getUint16(8, false);  // authority count
var arcount = dv.getUint16(10, false); // additional count
var count;

console.log('qdcount', qdcount);
console.log('ancount', ancount);
console.log('nscount', nscount);
console.log('arcount', arcount);

function unpackQuestionLabels(opts) {
  var dv = opts.dv;
  //var origTotal = opts.total;
  var total = opts.total;
  var len = opts.len;
  var qnames = [];
  var labelLen;

  while (true) {
    if (total >= len) {
      opts.trunc = true;
      console.warn('');
      console.warn('[WARNING] The label was truncated by byte length of message or rdata.');
      console.warn('[WARNING] Depending on the Resource Record type, that may be a parse error.');
      console.warn('');
      break;
    }
    labelLen = dv.getUint8(total, false); // additional count
    total += 1;
    if (!labelLen) {
      break;
    }
    if (labelLen >= 0xc0) {
      // (11 000000 & whatever) signifies pointer
      // (00 111111 & whatever) bitmask for potentially large pointer
      // (00 000001   11111111) largest realistic pointer value (512 byte message size)
      var pointer = ((labelLen & 0x3f) << 8) | dv.getUint8(total, false);
      console.log('Found a pointer to'
        + ' 0x' + pointer.toString(16) + ' (' + pointer + ')'
        + ' at byte index'
        + ' 0x' + leftPad(total.toString(16)) + ' (' + total + ')'
        //+ ' which back-references:'
      );
      /*
      console.log('-4', dv.getUint8(pointer - 4, false));
      console.log('-3', dv.getUint8(pointer - 3, false));
      console.log('-2', dv.getUint8(pointer - 2, false));
      console.log('-1', dv.getUint8(pointer - 1, false));
      console.log(' 0', dv.getUint8(pointer + 0, false));
      console.log('+1', dv.getUint8(pointer + 1, false));
      console.log('+2', dv.getUint8(pointer + 2, false));
      console.log('bytes near the pointer itself (not what it points to) are:');
      console.log('-2', dv.getUint8(total - 2, false));
      console.log('-1', dv.getUint8(total - 1, false));
      console.log(' 0', dv.getUint8(total + 0, false));
      console.log('+1', dv.getUint8(total + 1, false));
      console.log('+2', dv.getUint8(total + 2, false));
      console.log('+3', dv.getUint8(total + 3, false));
      console.log('+4', dv.getUint8(total + 4, false));
      */
      //total += 1;
      opts.cp = true;
      qnames.push(unpackQuestionLabels({ dv: dv, total: pointer, len: len }).qname);
      total += 1;
      break;
    } else {
      var i;
      var label = '';
      console.log('label len', labelLen);
      for (i = 0; i < labelLen; i += 1) {
        //console.log('total:', total, i);
        label += String.fromCharCode(dv.getUint8(total + i, false));
      }
      total += label.length;
      console.log('label:', label);
      qnames.push(label);
    }
  }

  return {
    total: total
  , qname: qnames.join('.')
  };
}

function unpackQuestion(dv, total, len) {

  var result = unpackQuestionLabels({ dv: dv, total: total, len: len });

  // leading length and (potentially) trailing null
  console.log('QNAME (len ' + (result.total - total) + '):', result.qname, result.cp ? '(pointer)' : '');
  console.log('QTYPE (len 2):', dv.getUint16(result.total, false));
  result.total += 2;
  console.log('QCLASS (len 2):', dv.getUint16(result.total, false));
  result.total += 2;

  return result;
}

var q = { total: 12 };
function mapChar(ch) { return JSON.stringify(String.fromCharCode(ch)) + '(' + ch + ')'; }
function leftPad(ch) { ch = ch.toString(); while (ch.length < 2) { ch = '0' + ch; } return ch; }


console.log('');
console.log('//////////////////');
console.log('//   QUESTION   //');
console.log('//////////////////');
console.log('');
for (count = 0; count < qdcount; count += 1) {
  console.log('');
  console.log('Question ' + (count + 1) + ' of ' + qdcount + ' (byte index: 0x' + leftPad(q.total.toString(16)) + ' ' + q.total + ')');
  q = unpackQuestion(dv, q.total, ab.byteLength);
  console.log('');
}

function unpackResourceRecord(dv, q, ab) {
  var _q = unpackQuestion(dv, q.total, ab.byteLength);
  q.total = _q.total;
  console.log('ttl (len 4):', dv.getUint32(q.total, false));
  q.total += 4;
  q.rdlength = dv.getUint16(q.total, false);
  console.log('rdlen (len 2):', q.rdlength);
  q.total += 2;
  console.log('rrdata (len ' + q.rdlength + '):');
  console.log([].slice.call(new Uint8Array(ab), q.total, q.total + q.rdlength).map(mapChar).join(' '));
  q.total += q.rdlength;
  console.log('');
}

console.log('');
console.log('//////////////////');
console.log('//    ANSWER    //');
console.log('//////////////////');
console.log('');
for (count = 0; count < ancount; count += 1) {
  console.log('');
  console.log('Answer', count + 1, 'of', ancount + ' (byte index: 0x' + q.total.toString(16) + ' ' + q.total + ')');
  unpackResourceRecord(dv, q, ab);
  console.log('');
}

console.log('');
console.log('//////////////////');
console.log('//   AUTHORITY  //');
console.log('//////////////////');
console.log('');
for (count = 0; count < nscount; count += 1) {
  console.log('');
  console.log('Authority', count + 1, 'of', nscount + ' (byte index: 0x' + q.total.toString(16) + ' ' + q.total + ')');
  unpackResourceRecord(dv, q, ab);
  console.log('');
}

console.log('');
console.log('//////////////////');
console.log('//  ADDITIONAL  //');
console.log('//////////////////');
console.log('');
for (count = 0; count < arcount; count += 1) {
  console.log('');
  console.log('Additional', count + 1, 'of', arcount + ' (byte index: 0x' + q.total.toString(16) + ' ' + q.total + ')');
  unpackResourceRecord(dv, q, ab);
  console.log('');
}

console.log('');
console.log('total bytes', dv.byteLength);
console.log('total bytes read', q.total);
console.log('');

}());