dns-suite.js/dns.parser.js

;(function (exports) {
'use strict';

var pdns = exports.DNS_PARSER = {};

var classes = exports.DNS_CLASSES || require('./dns.classes.js').DNS_CLASSES;
var types = exports.DNS_TYPES || require('./dns.types.js').DNS_TYPES;

// Order http://www.zytrax.com/books/dns/ch15/
var packet = {};
pdns.unpackHeader = function (i) {
  // i is one element from a Uint16Array (as a 16-bit unsigned integer)

  var header = {
    id:     0                   // added here to preserve console.log order

  , qr:     (i & 0x8000) >> 15  // Query Response (0 is question, 1 is response)
  , opcode: (i & 0x7800) >> 11  // 0 is question
  , aa:     (i &  0x400) >> 10  // Authoritative Answer (response-only)
  , tc:     (i &  0x200) >>  9  // TrunCated - expect another packet with same (?) id
  , rd:     (i &  0x100) >>  8  // Recursion Desired

  , ra:     (i &   0x80) >>  7
  , res1:   (i &   0x40) >>  6  // z
  , res2:   (i &   0x20) >>  5  // ad
  , res3:   (i &   0x10) >>  4  // cd
  , rcode:  (i &    0xF)        // Error Code (response-only)
  };

  return header;
};

pdns._unpackLabels = exports.DNS_UNPACK_LABELS || require('./dns.unpack-labels.js').DNS_UNPACK_LABELS;

pdns.unpack = function (ab) {
  if (ab.buffer) {
    ab = ab.buffer;
  }

  // SANITY Check
  if (ab.byteLength < 12) {
    throw new Error(
      "A DNS header has a minimum length of 12 bytes but this packet has only " + ab.byteLength + "bytes."
    );
  }

  // DO: new Uint8Array(arrayBuffer);
  // DO NOT: Uint8Array.from(arrayBuffer); // WILL NOT WORK

  // DO: new DataView(arrayBuffer).getUint16(7, false);
  // DO NOT: arrayBuffer.slice();
  //
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer
  // https://developer.mozilla.org/en-US/docs/Web/API/ArrayBufferView
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice

  // 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.qdcount = dv.getUint16(4, false);  // query count
  packet.ancount = dv.getUint16(6, false);  // answer count
  packet.nscount = dv.getUint16(8, false);  // authority count
  packet.arcount = dv.getUint16(10, false); // additional count
  var total = 12;
  var i;
  var rec;
  var ui8 = new Uint8Array(ab);

  // TODO move to pdns.unpackQuestion to make testable
  function unpackQuestion(ab, dv, ui8, total) {
    var ototal = total;
    var q = pdns._unpackLabels(ui8, total, {
      name: ''        // ex: daplie.com
    , type: 0         // ex: 1
    , typeName: ''    // ex: A
    , class: 0        // ex: 1
    , className: ''   // ex: IN
    , byteLength: 0   // the total byte length (including pointers, but not their labels)
    , labels: []      // an array of the labels individually
    , cpcount: 0      // the number of compression pointers traversed
    });
    //console.log('unpackQuestion QNAME:');
    //console.log(q);
    total += q.byteLength;





    if (ab.byteLength - total < 4) {
      // console.error(str.join(''));
      throw new Error(
        "Expected a 2-byte QTYPE and 2-byte QCLASS following " + total + "-byte QNAME"
          + " but packet itself has " + (ab.byteLength - total) + " bytes remaining"
      );
    }

    q.type = dv.getUint16(total, false);
    total += 2;
    q.class = dv.getUint16(total, false);
    total += 2;
    q.byteLength = total - ototal;

    q.className = classes[q.class];
    q.typeName = types[q.type];

    return q;
  }

  function unpackAnswer(ab, dv, ui8, total) {
    var ototal = total;
    var err;
    var q = pdns._unpackLabels(ui8, total, {
      name: ''
    , type: 0
    , typeName: ''
    , class: 0
    , className: ''
    , byteLength: 0
    , labels: []
    , cpcount: 0

    , rdstart: 0
    //, rdata: 0
    , rdlength: 0
    });
    //console.log('unpackAnswer [Q]NAME:');
    //console.log(q);
    total += q.byteLength;
    q.className = classes[q.class];
    q.typeName = types[q.type];

    if (ab.byteLength - total < 10) {
      // console.error(str.join(''));
      //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);
    total += 2;
    q.class = dv.getUint16(total, false);
    total += 2;
    q.ttl = dv.getUint32(total, false);
    total += 4;
    q.rdlength = dv.getUint16(total, false);
    total += 2;

    q.className = classes[q.class];
    q.typeName = types[q.type];


    // TODO actually parse RDATA
    q.rdstart = total;
    // console.log('q.rdata', q.rdlength, 'bytes:');
    // console.log(new Uint8Array(ab).slice(total, total + q.rdlength));
    //q.rdata = Array.prototype.slice.apply(q.rdata);

    //q.rdend = q.rdstart + q.rdlength;

    total += q.rdlength;
    q.byteLength = total - ototal;

    return q;
  }

  packet.header.id = id;


  console.log('qdcount', packet.qdcount);
  packet.question = [];
  for (i = 0; i < packet.qdcount; i += 1) {
    rec = unpackQuestion(ab, dv, ui8, total);
    total += rec.byteLength;
    packet.question.push(rec);
  }

  console.log('ancount', packet.ancount);
  packet.answer = [];
  for (i = 0; i < packet.ancount; i += 1) {
    rec = unpackAnswer(ab, dv, ui8, total);
    total += rec.byteLength;
    packet.answer.push(rec);
  }

  console.log('nscount', packet.nscount);
  packet.authority = [];
  for (i = 0; i < packet.nscount; i += 1) {
    rec = unpackAnswer(ab, dv, ui8, total);
    total += rec.byteLength;
    packet.authority.push(rec);
  }

  console.log('arcount', packet.arcount);
  packet.additional = [];
  for (i = 0; i < packet.arcount; i += 1) {
    rec = unpackAnswer(ab, dv, ui8, total);
    total += rec.byteLength;
    packet.additional.push(rec);
  }

  if (ab.byteLength !== total) {
    throw new Error(
      "Parsed " + total + " bytes, but packet is " + ab.byteLength + " bytes."
    );
  }
  packet.byteLength = total;
  return packet;
};
pdns.unpackRdata = exports.DNS_RDATA_PARSE || require('./dns.rdata.parse.js').DNS_RDATA_PARSE;

}('undefined' !== typeof window ? window : exports));