-
Notifications
You must be signed in to change notification settings - Fork 161
/
asn1.js
627 lines (616 loc) · 23.9 KB
/
asn1.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
// ASN.1 JavaScript decoder
// Copyright (c) 2008-2024 Lapo Luchini <[email protected]>
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
import { Int10 } from './int10.js';
import { oids } from './oids.js';
const
ellipsis = '\u2026',
reTimeS = /^(\d\d)(0[1-9]|1[0-2])(0[1-9]|[12]\d|3[01])([01]\d|2[0-3])(?:([0-5]\d)(?:([0-5]\d)(?:[.,](\d{1,3}))?)?)?(Z|(-(?:0\d|1[0-2])|[+](?:0\d|1[0-4]))([0-5]\d)?)?$/,
reTimeL = /^(\d\d\d\d)(0[1-9]|1[0-2])(0[1-9]|[12]\d|3[01])([01]\d|2[0-3])(?:([0-5]\d)(?:([0-5]\d)(?:[.,](\d{1,3}))?)?)?(Z|(-(?:0\d|1[0-2])|[+](?:0\d|1[0-4]))([0-5]\d)?)?$/,
hexDigits = '0123456789ABCDEF',
b64Safe = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_',
tableT61 = [
['', ''],
['AEIOUaeiou', 'ÀÈÌÒÙàèìòù'], // Grave
['ACEILNORSUYZacegilnorsuyz', 'ÁĆÉÍĹŃÓŔŚÚÝŹáćéģíĺńóŕśúýź'], // Acute
['ACEGHIJOSUWYaceghijosuwy', 'ÂĈÊĜĤÎĴÔŜÛŴŶâĉêĝĥîĵôŝûŵŷ'], // Circumflex
['AINOUainou', 'ÃĨÑÕŨãĩñõũ'], // Tilde
['AEIOUaeiou', 'ĀĒĪŌŪāēīōū'], // Macron
['AGUagu', 'ĂĞŬăğŭ'], // Breve
['CEGIZcegz', 'ĊĖĠİŻċėġż'], // Dot
['AEIOUYaeiouy', 'ÄËÏÖÜŸäëïöüÿ'], // Umlaut or diæresis
['', ''],
['AUau', 'ÅŮåů'], // Ring
['CGKLNRSTcklnrst', 'ÇĢĶĻŅŖŞŢçķļņŗşţ'], // Cedilla
['', ''],
['OUou', 'ŐŰőű'], // Double Acute
['AEIUaeiu', 'ĄĘĮŲąęįų'], // Ogonek
['CDELNRSTZcdelnrstz', 'ČĎĚĽŇŘŠŤŽčďěľňřšťž'], // Caron
];
function stringCut(str, len) {
if (str.length > len)
str = str.substring(0, len) + ellipsis;
return str;
}
function checkPrintable(s) {
let i, v;
for (i = 0; i < s.length; ++i) {
v = s.charCodeAt(i);
if (v < 32 && v != 9 && v != 10 && v != 13) // [\t\r\n] are (kinda) printable
throw new Error('Unprintable character at index ' + i + ' (code ' + s.str.charCodeAt(i) + ')');
}
}
class Stream {
constructor(enc, pos) {
if (enc instanceof Stream) {
this.enc = enc.enc;
this.pos = enc.pos;
} else {
// enc should be an array or a binary string
this.enc = enc;
this.pos = pos;
}
}
get(pos) {
if (pos === undefined)
pos = this.pos++;
if (pos >= this.enc.length)
throw new Error('Requesting byte offset ' + pos + ' on a stream of length ' + this.enc.length);
return (typeof this.enc == 'string') ? this.enc.charCodeAt(pos) : this.enc[pos];
}
hexByte(b) {
return hexDigits.charAt((b >> 4) & 0xF) + hexDigits.charAt(b & 0xF);
}
/** Hexadecimal dump.
* @param type 'raw', 'byte' or 'dump' */
hexDump(start, end, type = 'dump') {
let s = '';
for (let i = start; i < end; ++i) {
if (type == 'byte' && i > start)
s += ' ';
s += this.hexByte(this.get(i));
if (type == 'dump')
switch (i & 0xF) {
case 0x7: s += ' '; break;
case 0xF: s += '\n'; break;
default: s += ' ';
}
}
return s;
}
b64Dump(start, end) {
let extra = (end - start) % 3,
s = '',
i, c;
for (i = start; i + 2 < end; i += 3) {
c = this.get(i) << 16 | this.get(i + 1) << 8 | this.get(i + 2);
s += b64Safe.charAt(c >> 18 & 0x3F);
s += b64Safe.charAt(c >> 12 & 0x3F);
s += b64Safe.charAt(c >> 6 & 0x3F);
s += b64Safe.charAt(c & 0x3F);
}
if (extra > 0) {
c = this.get(i) << 16;
if (extra > 1) c |= this.get(i + 1) << 8;
s += b64Safe.charAt(c >> 18 & 0x3F);
s += b64Safe.charAt(c >> 12 & 0x3F);
if (extra == 2) s += b64Safe.charAt(c >> 6 & 0x3F);
}
return s;
}
isASCII(start, end) {
for (let i = start; i < end; ++i) {
let c = this.get(i);
if (c < 32 || c > 176)
return false;
}
return true;
}
parseStringISO(start, end, maxLength) {
let s = '';
for (let i = start; i < end; ++i)
s += String.fromCharCode(this.get(i));
return { size: s.length, str: stringCut(s, maxLength) };
}
parseStringT61(start, end, maxLength) {
// warning: this code is not very well tested so far
function merge(c, d) {
let t = tableT61[c - 0xC0];
let i = t[0].indexOf(String.fromCharCode(d));
return (i < 0) ? '\0' : t[1].charAt(i);
}
let s = '', c;
for (let i = start; i < end; ++i) {
c = this.get(i);
if (c >= 0xA4 && c <= 0xBF)
s += '$¥#§¤\0\0«\0\0\0\0°±²³×µ¶·÷\0\0»¼½¾¿'.charAt(c - 0xA4);
else if (c >= 0xE0 && c <= 0xFF)
s += 'ΩÆЪĦ\0IJĿŁØŒºÞŦŊʼnĸæđðħıijŀłøœßþŧŋ\0'.charAt(c - 0xE0);
else if (c >= 0xC0 && c <= 0xCF)
s += merge(c, this.get(++i));
else // using ISO 8859-1 for characters undefined (or equal) in T.61
s += String.fromCharCode(c);
}
return { size: s.length, str: stringCut(s, maxLength) };
}
parseStringUTF(start, end, maxLength) {
function ex(c) { // must be 10xxxxxx
if ((c < 0x80) || (c >= 0xC0))
throw new Error('Invalid UTF-8 continuation byte: ' + c);
return (c & 0x3F);
}
function surrogate(cp) {
if (cp < 0x10000)
throw new Error('UTF-8 overlong encoding, codepoint encoded in 4 bytes: ' + cp);
// we could use String.fromCodePoint(cp) but let's be nice to older browsers and use surrogate pairs
cp -= 0x10000;
return String.fromCharCode((cp >> 10) + 0xD800, (cp & 0x3FF) + 0xDC00);
}
let s = '';
for (let i = start; i < end; ) {
let c = this.get(i++);
if (c < 0x80) // 0xxxxxxx (7 bit)
s += String.fromCharCode(c);
else if (c < 0xC0)
throw new Error('Invalid UTF-8 starting byte: ' + c);
else if (c < 0xE0) // 110xxxxx 10xxxxxx (11 bit)
s += String.fromCharCode(((c & 0x1F) << 6) | ex(this.get(i++)));
else if (c < 0xF0) // 1110xxxx 10xxxxxx 10xxxxxx (16 bit)
s += String.fromCharCode(((c & 0x0F) << 12) | (ex(this.get(i++)) << 6) | ex(this.get(i++)));
else if (c < 0xF8) // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx (21 bit)
s += surrogate(((c & 0x07) << 18) | (ex(this.get(i++)) << 12) | (ex(this.get(i++)) << 6) | ex(this.get(i++)));
else
throw new Error('Invalid UTF-8 starting byte (since 2003 it is restricted to 4 bytes): ' + c);
}
return { size: s.length, str: stringCut(s, maxLength) };
}
parseStringBMP(start, end, maxLength) {
let s = '', hi, lo;
for (let i = start; i < end; ) {
hi = this.get(i++);
lo = this.get(i++);
s += String.fromCharCode((hi << 8) | lo);
}
return { size: s.length, str: stringCut(s, maxLength) };
}
parseTime(start, end, shortYear) {
let s = this.parseStringISO(start, end).str,
m = (shortYear ? reTimeS : reTimeL).exec(s);
if (!m)
throw new Error('Unrecognized time: ' + s);
if (shortYear) {
// to avoid querying the timer, use the fixed range [1970, 2069]
// it will conform with ITU X.400 [-10, +40] sliding window until 2030
m[1] = +m[1];
m[1] += (m[1] < 70) ? 2000 : 1900;
}
s = m[1] + '-' + m[2] + '-' + m[3] + ' ' + m[4];
if (m[5]) {
s += ':' + m[5];
if (m[6]) {
s += ':' + m[6];
if (m[7])
s += '.' + m[7];
}
}
if (m[8]) {
s += ' UTC';
if (m[9])
s += m[9] + ':' + (m[10] || '00');
}
return s;
}
parseInteger(start, end) {
let v = this.get(start),
neg = (v > 127),
pad = neg ? 255 : 0,
len,
s = '';
// skip unuseful bits (not allowed in DER)
while (v == pad && ++start < end)
v = this.get(start);
len = end - start;
if (len === 0)
return neg ? '-1' : '0';
// show bit length of huge integers
if (len > 4) {
s = v;
len <<= 3;
while (((s ^ pad) & 0x80) == 0) {
s <<= 1;
--len;
}
s = '(' + len + ' bit)\n';
}
// decode the integer
if (neg) v = v - 256;
let n = new Int10(v);
for (let i = start + 1; i < end; ++i)
n.mulAdd(256, this.get(i));
return s + n.toString();
}
parseBitString(start, end, maxLength) {
let unusedBits = this.get(start);
if (unusedBits > 7)
throw new Error('Invalid BitString with unusedBits=' + unusedBits);
let lenBit = ((end - start - 1) << 3) - unusedBits,
s = '';
for (let i = start + 1; i < end; ++i) {
let b = this.get(i),
skip = (i == end - 1) ? unusedBits : 0;
for (let j = 7; j >= skip; --j)
s += (b >> j) & 1 ? '1' : '0';
if (s.length > maxLength)
s = stringCut(s, maxLength);
}
return { size: lenBit, str: s };
}
parseOctetString(start, end, maxLength) {
let len = end - start,
s;
try {
s = this.parseStringUTF(start, end, maxLength);
checkPrintable(s.str);
return { size: end - start, str: s.str };
} catch (e) {
// ignore
}
maxLength /= 2; // we work in bytes
if (len > maxLength)
end = start + maxLength;
s = '';
for (let i = start; i < end; ++i)
s += this.hexByte(this.get(i));
if (len > maxLength)
s += ellipsis;
return { size: len, str: s };
}
parseOID(start, end, maxLength, isRelative) {
let s = '',
n = new Int10(),
bits = 0;
for (let i = start; i < end; ++i) {
let v = this.get(i);
n.mulAdd(128, v & 0x7F);
bits += 7;
if (!(v & 0x80)) { // finished
if (s === '') {
n = n.simplify();
if (isRelative) {
s = (n instanceof Int10) ? n.toString() : '' + n;
} else if (n instanceof Int10) {
n.sub(80);
s = '2.' + n.toString();
} else {
let m = n < 80 ? n < 40 ? 0 : 1 : 2;
s = m + '.' + (n - m * 40);
}
} else
s += '.' + n.toString();
if (s.length > maxLength)
return stringCut(s, maxLength);
n = new Int10();
bits = 0;
}
}
if (bits > 0)
s += '.incomplete';
if (typeof oids === 'object' && !isRelative) {
let oid = oids[s];
if (oid) {
if (oid.d) s += '\n' + oid.d;
if (oid.c) s += '\n' + oid.c;
if (oid.w) s += '\n(warning!)';
}
}
return s;
}
parseRelativeOID(start, end, maxLength) {
return this.parseOID(start, end, maxLength, true);
}
}
function recurse(el, parser, maxLength) {
let avoidRecurse = true;
if (el.tag.tagConstructed && el.sub) {
avoidRecurse = false;
el.sub.forEach(function (e1) {
if (e1.tag.tagClass != el.tag.tagClass || e1.tag.tagNumber != el.tag.tagNumber)
avoidRecurse = true;
});
}
if (avoidRecurse)
return el.stream[parser](el.posContent(), el.posContent() + Math.abs(el.length), maxLength);
let d = { size: 0, str: '' };
el.sub.forEach(function (el) {
let d1 = recurse(el, parser, maxLength - d.str.length);
d.size += d1.size;
d.str += d1.str;
});
return d;
}
class ASN1Tag {
constructor(stream) {
let buf = stream.get();
this.tagClass = buf >> 6;
this.tagConstructed = ((buf & 0x20) !== 0);
this.tagNumber = buf & 0x1F;
if (this.tagNumber == 0x1F) { // long tag
let n = new Int10();
do {
buf = stream.get();
n.mulAdd(128, buf & 0x7F);
} while (buf & 0x80);
this.tagNumber = n.simplify();
}
}
isUniversal() {
return this.tagClass === 0x00;
}
isEOC() {
return this.tagClass === 0x00 && this.tagNumber === 0x00;
}
}
export class ASN1 {
constructor(stream, header, length, tag, tagLen, sub) {
if (!(tag instanceof ASN1Tag)) throw new Error('Invalid tag value.');
this.stream = stream;
this.header = header;
this.length = length;
this.tag = tag;
this.tagLen = tagLen;
this.sub = sub;
}
typeName() {
switch (this.tag.tagClass) {
case 0: // universal
switch (this.tag.tagNumber) {
case 0x00: return 'EOC';
case 0x01: return 'BOOLEAN';
case 0x02: return 'INTEGER';
case 0x03: return 'BIT_STRING';
case 0x04: return 'OCTET_STRING';
case 0x05: return 'NULL';
case 0x06: return 'OBJECT_IDENTIFIER';
case 0x07: return 'ObjectDescriptor';
case 0x08: return 'EXTERNAL';
case 0x09: return 'REAL';
case 0x0A: return 'ENUMERATED';
case 0x0B: return 'EMBEDDED_PDV';
case 0x0C: return 'UTF8String';
case 0x0D: return 'RELATIVE_OID';
case 0x10: return 'SEQUENCE';
case 0x11: return 'SET';
case 0x12: return 'NumericString';
case 0x13: return 'PrintableString'; // ASCII subset
case 0x14: return 'TeletexString'; // aka T61String
case 0x15: return 'VideotexString';
case 0x16: return 'IA5String'; // ASCII
case 0x17: return 'UTCTime';
case 0x18: return 'GeneralizedTime';
case 0x19: return 'GraphicString';
case 0x1A: return 'VisibleString'; // ASCII subset
case 0x1B: return 'GeneralString';
case 0x1C: return 'UniversalString';
case 0x1E: return 'BMPString';
}
return 'Universal_' + this.tag.tagNumber.toString();
case 1: return 'Application_' + this.tag.tagNumber.toString();
case 2: return '[' + this.tag.tagNumber.toString() + ']'; // Context
case 3: return 'Private_' + this.tag.tagNumber.toString();
}
}
/** A string preview of the content (intended for humans). */
content(maxLength) {
if (this.tag === undefined)
return null;
if (maxLength === undefined)
maxLength = Infinity;
let content = this.posContent(),
len = Math.abs(this.length);
if (!this.tag.isUniversal()) {
if (this.sub !== null)
return '(' + this.sub.length + ' elem)';
let d1 = this.stream.parseOctetString(content, content + len, maxLength);
return '(' + d1.size + ' byte)\n' + d1.str;
}
switch (this.tag.tagNumber) {
case 0x01: // BOOLEAN
return (this.stream.get(content) === 0) ? 'false' : 'true';
case 0x02: // INTEGER
return this.stream.parseInteger(content, content + len);
case 0x03: { // BIT_STRING
let d = recurse(this, 'parseBitString', maxLength);
return '(' + d.size + ' bit)\n' + d.str;
}
case 0x04: { // OCTET_STRING
let d = recurse(this, 'parseOctetString', maxLength);
return '(' + d.size + ' byte)\n' + d.str;
}
//case 0x05: // NULL
case 0x06: // OBJECT_IDENTIFIER
return this.stream.parseOID(content, content + len, maxLength);
//case 0x07: // ObjectDescriptor
//case 0x08: // EXTERNAL
//case 0x09: // REAL
case 0x0A: // ENUMERATED
return this.stream.parseInteger(content, content + len);
//case 0x0B: // EMBEDDED_PDV
case 0x0D: // RELATIVE-OID
return this.stream.parseRelativeOID(content, content + len, maxLength);
case 0x10: // SEQUENCE
case 0x11: // SET
if (this.sub !== null)
return '(' + this.sub.length + ' elem)';
else
return '(no elem)';
case 0x0C: // UTF8String
return recurse(this, 'parseStringUTF', maxLength).str;
case 0x14: // TeletexString
return recurse(this, 'parseStringT61', maxLength).str;
case 0x12: // NumericString
case 0x13: // PrintableString
case 0x15: // VideotexString
case 0x16: // IA5String
case 0x1A: // VisibleString
case 0x1B: // GeneralString
//case 0x19: // GraphicString
//case 0x1C: // UniversalString
return recurse(this, 'parseStringISO', maxLength).str;
case 0x1E: // BMPString
return recurse(this, 'parseStringBMP', maxLength).str;
case 0x17: // UTCTime
case 0x18: // GeneralizedTime
return this.stream.parseTime(content, content + len, (this.tag.tagNumber == 0x17));
}
return null;
}
toString() {
return this.typeName() + '@' + this.stream.pos + '[header:' + this.header + ',length:' + this.length + ',sub:' + ((this.sub === null) ? 'null' : this.sub.length) + ']';
}
toPrettyString(indent) {
if (indent === undefined) indent = '';
let s = indent;
if (this.def) {
if (this.def.id)
s += this.def.id + ' ';
if (this.def.name && this.def.name != this.typeName().replace(/_/g, ' '))
s+= this.def.name + ' ';
if (this.def.mismatch)
s += '[?] ';
}
s += this.typeName() + ' @' + this.stream.pos;
if (this.length >= 0)
s += '+';
s += this.length;
if (this.tag.tagConstructed)
s += ' (constructed)';
else if ((this.tag.isUniversal() && ((this.tag.tagNumber == 0x03) || (this.tag.tagNumber == 0x04))) && (this.sub !== null))
s += ' (encapsulates)';
let content = this.content();
if (content)
s += ': ' + content.replace(/\n/g, '|');
s += '\n';
if (this.sub !== null) {
indent += ' ';
for (let i = 0, max = this.sub.length; i < max; ++i)
s += this.sub[i].toPrettyString(indent);
}
return s;
}
posStart() {
return this.stream.pos;
}
posContent() {
return this.stream.pos + this.header;
}
posEnd() {
return this.stream.pos + this.header + Math.abs(this.length);
}
/** Position of the length. */
posLen() {
return this.stream.pos + this.tagLen;
}
/** Hexadecimal dump of the node.
* @param type 'raw', 'byte' or 'dump' */
toHexString(type = 'raw') {
return this.stream.hexDump(this.posStart(), this.posEnd(), type);
}
/** Base64 dump of the node. */
toB64String() {
return this.stream.b64Dump(this.posStart(), this.posEnd());
}
static decodeLength(stream) {
let buf = stream.get(),
len = buf & 0x7F;
if (len == buf) // first bit was 0, short form
return len;
if (len === 0) // long form with length 0 is a special case
return null; // undefined length
if (len > 6) // no reason to use Int10, as it would be a huge buffer anyways
throw new Error('Length over 48 bits not supported at position ' + (stream.pos - 1));
buf = 0;
for (let i = 0; i < len; ++i)
buf = (buf * 256) + stream.get();
return buf;
}
static decode(stream, offset, type = ASN1) {
if (!(type == ASN1 || type.prototype instanceof ASN1))
throw new Error('Must pass a class that extends ASN1');
if (!(stream instanceof Stream))
stream = new Stream(stream, offset || 0);
let streamStart = new Stream(stream),
tag = new ASN1Tag(stream),
tagLen = stream.pos - streamStart.pos,
len = ASN1.decodeLength(stream),
start = stream.pos,
header = start - streamStart.pos,
sub = null,
getSub = function () {
sub = [];
if (len !== null) {
// definite length
let end = start + len;
if (end > stream.enc.length)
throw new Error('Container at offset ' + start + ' has a length of ' + len + ', which is past the end of the stream');
while (stream.pos < end)
sub[sub.length] = type.decode(stream);
if (stream.pos != end)
throw new Error('Content size is not correct for container at offset ' + start);
} else {
// undefined length
try {
for (;;) {
let s = type.decode(stream);
if (s.tag.isEOC())
break;
sub[sub.length] = s;
}
len = start - stream.pos; // undefined lengths are represented as negative values
} catch (e) {
throw new Error('Exception while decoding undefined length content at offset ' + start + ': ' + e);
}
}
};
if (tag.tagConstructed) {
// must have valid content
getSub();
} else if (tag.isUniversal() && ((tag.tagNumber == 0x03) || (tag.tagNumber == 0x04))) {
// sometimes BitString and OctetString are used to encapsulate ASN.1
try {
if (tag.tagNumber == 0x03)
if (stream.get() != 0)
throw new Error('BIT STRINGs with unused bits cannot encapsulate.');
getSub();
for (let s of sub) {
if (s.tag.isEOC())
throw new Error('EOC is not supposed to be actual content.');
try {
s.content();
} catch (e) {
throw new Error('Unable to parse content: ' + e);
}
}
} catch (e) {
// but silently ignore when they don't
sub = null;
//DEBUG console.log('Could not decode structure at ' + start + ':', e);
}
}
if (sub === null) {
if (len === null)
throw new Error("We can't skip over an invalid tag with undefined length at offset " + start);
stream.pos = start + Math.abs(len);
}
return new type(streamStart, header, len, tag, tagLen, sub);
}
}