From 0d4db1bb19b7904c6ab5d458e28505f97168de41 Mon Sep 17 00:00:00 2001 From: AJ ONeal Date: Mon, 17 Dec 2018 20:58:53 -0700 Subject: [PATCH] add ASN.1 parser --- lib/asn1-parser.js | 147 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 147 insertions(+) create mode 100644 lib/asn1-parser.js diff --git a/lib/asn1-parser.js b/lib/asn1-parser.js new file mode 100644 index 0000000..63a7c93 --- /dev/null +++ b/lib/asn1-parser.js @@ -0,0 +1,147 @@ +// Copyright 2016-2018 AJ ONeal. All rights reserved +// https://git.coolaj86.com/coolaj86/asn1-parser.js +/* 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/. */ +;(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 = require('./encoding.js'); +var PEM = exports.PEM; + +// +// Parser +// + +ASN1.ELOOPN = 20; // I've seen 9 max in https certificates +ASN1.ELOOP = "uASN1.js Error: iterated over " + ASN1.ELOOPN + "+ elements (probably a malformed file)"; +ASN1.EDEEPN = 60; // I've seen 29 deep in https certificates +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; +}; + +// don't replace the full parseBlock, if it exists +PEM.parseBlock = PEM.parseBlock || function (str) { + var b64 = str.split(/\n/).filter(function (line) { + return !/-----/.test(line); + }).join(''); + var der = Enc.base64ToBuf(b64); + return { bytes: der }; +}; + +Enc.base64ToBuf = function (b64) { + return Buffer.from(b64, 'base64'); +}; +Enc.binToBuf = function (bin) { + return Buffer.from(bin, 'binary'); +}; +Enc.bufToHex = function (u8) { + return Buffer.from(u8).toString('hex'); +}; +Enc.numToHex = function (d) { + d = d.toString(16); + if (d.length % 2) { + return '0' + d; + } + return d; +}; + +}('undefined' !== typeof window ? window : module.exports));