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/
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;

var optWarned = false;
pdns.unpackOpt = function (ab, packet, rec) {
  var dv;

  // https://tools.ietf.org/html/rfc6891#section-6
  if (!optWarned) {
    console.warn('OPT is not yet supported');
    optWarned = true;
  }
  if ('undefined' !== typeof packet.edns_version) {
    console.warn("More that one OPT, should respond with FORMERR, but not implemented");
  }
  if (packet.name) {
    console.warn("name '" + packet.name + "' should not exist for type OPT 0x29 41");
  }
  packet.payload = rec.class;
  // TODO index into the correct place in the ArrayBuffer
  dv = new DataView(new ArrayBuffer(4));
  // rec.ttl is actually 1 (extended_rcode), 1 (edns_version), 2:1 (DO), 2:7 (Z)
  dv.setUint32(0, packet.ttl, false);
  // is xrcode this edns_options?
  packet.xrcode = '0x' + dv.getUint8(0, false).toString(16);
  if ('0x0' === packet.xrcode) {
    // use 4-bit rcode instead of 12-bit rcode
  }
  else {
    // shift xrcode up by 4 bits (8 bits + 4 trailing 0s)
    // OR with existing rcode (now 12-bits total)
    console.warn('extended_rcode not supported yet');
  }
  packet.edns_version = dv.getUint8(1, false);
  packet.do = dv.getUint8(2, false) & 0x8000; // 1000 0000
  packet.z = dv.getUint16(2, false) & 0x7FFF; // 0111 1111
  /*
  "edns_options": [],
  "payload": 4096,
  "edns_version": 0,
  "do": 0
  */
};
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);
  var packet = {};
  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;


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

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

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

  packet.edns_options = [];
  packet.additional = [];
  for (i = 0; i < packet.arcount; i += 1) {
    rec = unpackAnswer(ab, dv, ui8, total);
    total += rec.byteLength;
    if (0x29 === rec.type) {
      // OPT 41 (0x29)
      pdns.unpackOpt(ab, packet, rec);
      continue;
    }
    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));