acme.js/lib/asn1/parser.js

160 lines
4.8 KiB
JavaScript

// 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/. */
'use strict';
var ASN1 = module.exports;
var Enc = require('@root/encoding/hex');
//
// 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.parse = function parseAsn1Helper(buf) {
//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 (-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._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;
};