asn1-parser.js/asn1-parser.js

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

if (!exports.ASN1) { exports.ASN1 = {}; }
if (!exports.Enc) { exports.Enc = {}; }
if (!exports.PEM) { exports.PEM = {}; }

var ASN1 = exports.ASN1;
var Enc = exports.Enc;
var PEM = exports.PEM;

//
// Parser
//

ASN1.ELOOP = "uASN1.js Error: iterated over 15+ elements (probably a malformed file)";
ASN1.EDEEP = "uASN1.js Error: element nested 20+ layers deep (probably a malformed file)";
// Container Types are Sequence 0x30, Octect String 0x04, Array? (0xA0, 0xA1)
// Value Types are Integer 0x02, Bit String 0x03, Null 0x05, Object ID 0x06,
// Sometimes Bit String is used as a container (RSA Pub Spki)
ASN1.CTYPES = [ 0x30, 0x31, 0xa0, 0xa1 ];
ASN1.parse = function parseAsn1(buf, depth, ws) {
  if (!ws) { ws = ''; }
  if (!depth) { depth = 0; }
  if (depth >= 20) { throw new Error(ASN1.EDEEP); }

  var index = 2; // we know, at minimum, data starts after type (0) and lengthSize (1)
  var asn1 = { type: buf[0], lengthSize: 0, length: buf[1] };
  var child;
  var iters = 0;
  var adjust = 0;
  var adjustedLen;

  // Determine how many bytes the length uses, and what it is
  if (0x80 & asn1.length) {
    asn1.lengthSize = 0x7f & asn1.length;
    // I think that buf->hex->int solves the problem of Endianness... not sure
    asn1.length = parseInt(Enc.bufToHex(buf.slice(index, index + asn1.lengthSize)), 16);
    index += asn1.lengthSize;
  }

  // High-order bit Integers have a leading 0x00 to signify that they are positive.
  // Bit Streams use the first byte to signify padding, which x.509 doesn't use.
  if (0x00 === buf[index] && (0x02 === asn1.type || 0x03 === asn1.type)) {
    // However, 0x00 on its own is a valid number
    if (asn1.length > 1) {
      index += 1;
      adjust = -1;
    }
  }
  adjustedLen = asn1.length + adjust;

  //console.warn(ws + '0x' + Enc.numToHex(asn1.type), index, 'len:', asn1.length, asn1);

  function parseChildren(eager) {
    asn1.children = [];
    //console.warn('1 len:', (2 + asn1.lengthSize + asn1.length), 'idx:', index, 'clen:', 0);
    while (iters < 15 && index < (2 + asn1.length + asn1.lengthSize)) {
      iters += 1;
      child = ASN1.parse(buf.slice(index, index + adjustedLen), (depth || 0) + 1, ws + '  ');
      // The numbers don't match up exactly and I don't remember why...
      // probably something with adjustedLen or some such, but the tests pass
      index += (2 + child.lengthSize + child.length);
      //console.warn('2 len:', (2 + asn1.lengthSize + asn1.length), 'idx:', index, 'clen:', (2 + child.lengthSize + child.length));
      if (index > (2 + asn1.lengthSize + asn1.length)) {
        if (!eager) { console.error(JSON.stringify(asn1, ASN1._replacer, 2)); }
        throw new Error("Parse error: child value length (" + child.length
          + ") is greater than remaining parent length (" + (asn1.length - index)
          + " = " + asn1.length + " - " + index + ")");
      }
      asn1.children.push(child);
      //console.warn(ws + '0x' + Enc.numToHex(asn1.type), index, 'len:', asn1.length, asn1);
    }
    if (index !== (2 + asn1.lengthSize + asn1.length)) {
      //console.warn('index:', index, 'length:', (2 + asn1.lengthSize + asn1.length));
      throw new Error("premature end-of-file");
    }
    if (iters >= 15) { throw new Error(ASN1.ELOOP); }

    delete asn1.value;
    return asn1;
  }

  // We want to fail if we know for sure that it's bad
  if (-1 !== ASN1.CTYPES.indexOf(asn1.type)) {
    return parseChildren();
  }

  asn1.value = buf.slice(index, index + adjustedLen);
  try {
    return parseChildren(true);
  } catch(e) {
    // leaving iterable array as a matter of convenience
    asn1.children = [];
    return asn1;
  }
};
ASN1._replacer = function (k, v) {
  if ('type' === k) { return '0x' + Enc.numToHex(v); }
  if ('value' === k) { return '0x' + Enc.bufToHex(v.data || v); }
  return v;
};

// don't replace the full parseBlock, if it exists
PEM.parseBlock = PEM.parseBlock || function (str) {
  var der = str.split(/\n/).filter(function (line) {
    return !/-----/.test(line);
  }).join('');
  return { der: Enc.base64ToBuf(der) };
};

Enc.base64ToBuf = function (b64) {
  return Enc.binToBuf(atob(b64));
};
Enc.binToBuf = function (bin) {
  var arr = bin.split('').map(function (ch) {
    return ch.charCodeAt(0);
  });
  return 'undefined' !== typeof Uint8Array ? new Uint8Array(arr) : arr;
};
Enc.bufToHex = function (u8) {
  var hex = [];
  var i, h;
  var len = (u8.byteLength || u8.length);

  for (i = 0; i < len; i += 1) {
    h = u8[i].toString(16);
    if (h.length % 2) { h = '0' + h; }
    hex.push(h);
  }

  return hex.join('').toLowerCase();
};
Enc.numToHex = function (d) {
  d = d.toString(16);
  if (d.length % 2) {
    return '0' + d;
  }
  return d;
};

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