asn1.js
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;(function () {
'use strict';
var ASN1 = window.ASN1 = {};
var Enc = window.Encoding;
// Copyright 2018 AJ ONeal. All rights reserved
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//
// Parser
//
// Although I've only seen 9 max in https certificates themselves,
// but each domain list could have up to 100
ASN1.ELOOPN = 102;
ASN1.ELOOP =
'uASN1.js Error: iterated over ' +
ASN1.ELOOPN +
'+ elements (probably a malformed file)';
// I've seen https certificates go 29 deep
ASN1.EDEEPN = 60;
ASN1.EDEEP =
'uASN1.js Error: element nested ' +
ASN1.EDEEPN +
'+ layers deep (probably a malformed file)';
// Container Types are Sequence 0x30, Container Array? (0xA0, 0xA1)
// Value Types are Boolean 0x01, Integer 0x02, Null 0x05, Object ID 0x06, String 0x0C, 0x16, 0x13, 0x1e Value Array? (0x82)
// Bit String (0x03) and Octet String (0x04) may be values or containers
// Sometimes Bit String is used as a container (RSA Pub Spki)
ASN1.CTYPES = [0x30, 0x31, 0xa0, 0xa1];
ASN1.VTYPES = [0x01, 0x02, 0x05, 0x06, 0x0c, 0x82];
ASN1.parseVerbose = function parseAsn1Helper(buf, opts) {
if (!opts) {
opts = {};
}
//var ws = ' ';
function parseAsn1(buf, depth, eager) {
if (depth.length >= ASN1.EDEEPN) {
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(depth.join(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 < ASN1.ELOOPN &&
index < 2 + asn1.length + asn1.lengthSize
) {
iters += 1;
depth.length += 1;
child = parseAsn1(
buf.slice(index, index + adjustedLen),
depth,
eager
);
depth.length -= 1;
// 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(depth.join(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 >= ASN1.ELOOPN) {
throw new Error(ASN1.ELOOP);
}
delete asn1.value;
return asn1;
}
// Recurse into types that are _always_ containers
if (-1 !== ASN1.CTYPES.indexOf(asn1.type)) {
return parseChildren(eager);
}
// Return types that are _always_ values
asn1.value = buf.slice(index, index + adjustedLen);
if (opts.json) {
asn1.value = Enc.bufToHex(asn1.value);
}
if (-1 !== ASN1.VTYPES.indexOf(asn1.type)) {
return asn1;
}
// For ambigious / unknown types, recurse and return on failure
// (and return child array size to zero)
try {
return parseChildren(true);
} catch (e) {
asn1.children.length = 0;
return asn1;
}
}
var asn1 = parseAsn1(buf, []);
var len = buf.byteLength || buf.length;
if (len !== 2 + asn1.lengthSize + asn1.length) {
throw new Error(
'Length of buffer does not match length of ASN.1 sequence.'
);
}
return asn1;
};
ASN1._toArray = function toArray(next, opts) {
var typ = opts.json ? Enc.numToHex(next.type) : next.type;
var val = next.value;
if (val) {
if ('string' !== typeof val && opts.json) {
val = Enc.bufToHex(val);
}
return [typ, val];
}
return [
typ,
next.children.map(function(child) {
return toArray(child, opts);
})
];
};
ASN1.parse = function(opts) {
var opts2 = { json: false !== opts.json };
var verbose = ASN1.parseVerbose(opts.der, opts2);
if (opts.verbose) {
return verbose;
}
return ASN1._toArray(verbose, opts2);
};
ASN1._replacer = function(k, v) {
if ('type' === k) {
return '0x' + Enc.numToHex(v);
}
if (v && 'value' === k) {
return '0x' + Enc.bufToHex(v.data || v);
}
return v;
};
//
// Packer
//
// Almost every ASN.1 type that's important for CSR
// can be represented generically with only a few rules.
function Any(/*type, hexstrings...*/) {
var args = Array.prototype.slice.call(arguments);
var typ = args.shift();
var str = args
.join('')
.replace(/\s+/g, '')
.toLowerCase();
var len = str.length / 2;
var lenlen = 0;
var hex = typ;
if ('number' === typeof hex) {
hex = Enc.numToHex(hex);
}
// We can't have an odd number of hex chars
if (len !== Math.round(len)) {
throw new Error('invalid hex');
}
// The first byte of any ASN.1 sequence is the type (Sequence, Integer, etc)
// The second byte is either the size of the value, or the size of its size
// 1. If the second byte is < 0x80 (128) it is considered the size
// 2. If it is > 0x80 then it describes the number of bytes of the size
// ex: 0x82 means the next 2 bytes describe the size of the value
// 3. The special case of exactly 0x80 is "indefinite" length (to end-of-file)
if (len > 127) {
lenlen += 1;
while (len > 255) {
lenlen += 1;
len = len >> 8;
}
}
if (lenlen) {
hex += Enc.numToHex(0x80 + lenlen);
}
return hex + Enc.numToHex(str.length / 2) + str;
}
ASN1.Any = Any;
// The Integer type has some special rules
ASN1.UInt = function UINT() {
var str = Array.prototype.slice.call(arguments).join('');
var first = parseInt(str.slice(0, 2), 16);
// If the first byte is 0x80 or greater, the number is considered negative
// Therefore we add a '00' prefix if the 0x80 bit is set
if (0x80 & first) {
str = '00' + str;
}
return Any('02', str);
};
// The Bit String type also has a special rule
ASN1.BitStr = function BITSTR() {
var str = Array.prototype.slice.call(arguments).join('');
// '00' is a mask of how many bits of the next byte to ignore
return Any('03', '00' + str);
};
ASN1._toArray = function toArray(next, opts) {
var typ = opts.json ? Enc.numToHex(next.type) : next.type;
var val = next.value;
if (val) {
if ('string' !== typeof val && opts.json) {
val = Enc.bufToHex(val);
}
return [typ, val];
}
return [
typ,
next.children.map(function(child) {
return toArray(child, opts);
})
];
};
ASN1._pack = function(arr) {
var typ = arr[0];
if ('number' === typeof arr[0]) {
typ = Enc.numToHex(arr[0]);
}
var str = '';
if (Array.isArray(arr[1])) {
arr[1].forEach(function(a) {
str += ASN1._pack(a);
});
} else if ('string' === typeof arr[1]) {
str = arr[1];
} else if (arr[1].byteLength) {
str = Enc.bufToHex(arr[1]);
} else {
throw new Error('unexpected array');
}
if ('03' === typ) {
return ASN1.BitStr(str);
} else if ('02' === typ) {
return ASN1.UInt(str);
} else {
return Any(typ, str);
}
};
// TODO should this return a buffer?
ASN1.pack = function(asn1, opts) {
if (!opts) {
opts = {};
}
if (!Array.isArray(asn1)) {
asn1 = ASN1._toArray(asn1, { json: true });
}
var result = ASN1._pack(asn1);
if (opts.json) {
return result;
}
return Enc.hexToBuf(result);
};
}());