2 * Routines for ASN.1 BER dissection
4 * $Id: asn1.c,v 1.7 2001/04/15 07:30:02 guy Exp $
6 * Ethereal - Network traffic analyzer
7 * By Gerald Combs <gerald@zing.org>
9 * Based on "g_asn1.c" from:
11 * GXSNMP -- An snmp mangament application
12 * Copyright (C) 1998 Gregory McLean & Jochen Friedrich
13 * Beholder RMON ethernet network monitor, Copyright (C) 1993 DNPAP group
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
35 * SYSTEM NAME: ASN1 Basic Encoding
36 * ORIGINAL AUTHOR(S): Dirk Wisse
38 * CREATION DATE: 1990/11/22
40 * DESCRIPTION: ASN1 Basic Encoding Rules.
42 * To decode this we must do:
44 * asn1_open (asn1, tvb, offset);
45 * asn1_header_decode (asn1, &end_of_seq, cls, con, tag, def, len);
46 * asn1_header_decode (asn1, &end_of_octs, cls, con, tag, def, len);
47 * asn1_octets_decode (asn1, end_of_octs, str, len);
48 * asn1_header_decode (asn1, &end_of_int, cls, con, tag);
49 * asn1_int_decode (asn1, end_of_int, &integer);
50 * asn1_eoc_decode (asn1, end_of_seq);
51 * asn1_close (asn1, &offset);
53 * For indefinite encoding end_of_seq and &end_of_seq in the
54 * example above should be replaced by NULL.
55 * For indefinite decoding nothing has to be changed.
56 * This can be very useful if you want to decode both
57 * definite and indefinite encodings.
64 #ifdef HAVE_SYS_TYPES_H
65 # include <sys/types.h>
77 * NAME: asn1_open [API]
78 * SYNOPSIS: void asn1_open
84 * DESCRIPTION: Opens an ASN1 socket.
86 * asn1: pointer to ASN1 socket.
87 * tvb: Tvbuff for encoding.
88 * offset: Current offset in tvbuff.
89 * Encoding starts at the end of the buffer, and
90 * proceeds to the beginning.
95 asn1_open(ASN1_SCK *asn1, tvbuff_t *tvb, int offset)
98 asn1->offset = offset;
102 * NAME: asn1_close [API]
103 * SYNOPSIS: void asn1_close
108 * DESCRIPTION: Closes an ASN1 socket.
110 * asn1: pointer to ASN1 socket.
111 * offset: pointer to variable into which current offset is
117 asn1_close(ASN1_SCK *asn1, int *offset)
119 *offset = asn1->offset;
123 * NAME: asn1_octet_decode
124 * SYNOPSIS: int asn1_octet_decode
129 * DESCRIPTION: Decodes an octet.
130 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
133 asn1_octet_decode(ASN1_SCK *asn1, guchar *ch)
135 *ch = tvb_get_guint8(asn1->tvb, asn1->offset);
137 return ASN1_ERR_NOERROR;
141 * NAME: asn1_tag_decode
142 * SYNOPSIS: int asn1_tag_decode
147 * DESCRIPTION: Decodes a tag.
148 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
151 asn1_tag_decode(ASN1_SCK *asn1, guint *tag)
158 ret = asn1_octet_decode (asn1, &ch);
159 if (ret != ASN1_ERR_NOERROR)
163 } while ((ch & 0x80) == 0x80);
164 return ASN1_ERR_NOERROR;
168 * NAME: asn1_id_decode
169 * SYNOPSIS: int asn1_id_decode
176 * DESCRIPTION: Decodes an identifier.
177 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
180 asn1_id_decode(ASN1_SCK *asn1, guint *cls, guint *con, guint *tag)
185 ret = asn1_octet_decode (asn1, &ch);
186 if (ret != ASN1_ERR_NOERROR)
188 *cls = (ch & 0xC0) >> 6;
189 *con = (ch & 0x20) >> 5;
192 ret = asn1_tag_decode (asn1, tag);
193 if (ret != ASN1_ERR_NOERROR)
196 return ASN1_ERR_NOERROR;
200 * NAME: asn1_length_decode
201 * SYNOPSIS: int asn1_length_decode
207 * DESCRIPTION: Decodes an ASN1 length.
209 * asn1: pointer to ASN1 socket.
210 * def: Boolean - TRUE if length definite, FALSE if not
211 * len: length, if length is definite
212 * DESCRIPTION: Decodes a definite or indefinite length.
213 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
216 asn1_length_decode(ASN1_SCK *asn1, gboolean *def, guint *len)
221 ret = asn1_octet_decode (asn1, &ch);
222 if (ret != ASN1_ERR_NOERROR)
225 *def = FALSE; /* indefinite length */
227 *def = TRUE; /* definite length */
231 cnt = (guchar) (ch & 0x7F);
234 ret = asn1_octet_decode (asn1, &ch);
235 if (ret != ASN1_ERR_NOERROR)
243 return ASN1_ERR_NOERROR;
247 * NAME: asn1_header_decode [API]
248 * SYNOPSIS: int asn1_header_decode
257 * DESCRIPTION: Decodes an ASN1 header.
259 * asn1: pointer to ASN1 socket.
260 * cls: Class (see asn1.h)
261 * con: Primitive, Constructed (ASN1_PRI, ASN1_CON)
262 * tag: Tag (see asn1.h)
263 * defp: Boolean - TRUE if length definite, FALSE if not
264 * lenp: length, if length is definite
265 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
268 asn1_header_decode(ASN1_SCK *asn1, guint *cls, guint *con, guint *tag,
269 gboolean *defp, guint *lenp)
274 ret = asn1_id_decode (asn1, cls, con, tag);
275 if (ret != ASN1_ERR_NOERROR)
277 ret = asn1_length_decode (asn1, &def, &len);
278 if (ret != ASN1_ERR_NOERROR)
282 return ASN1_ERR_NOERROR;
287 * NAME: asn1_eoc [API]
288 * SYNOPSIS: gboolean asn1_eoc
293 * DESCRIPTION: Checks if decoding is at End Of Contents.
295 * asn1: pointer to ASN1 socket.
296 * eoc: offset of end of encoding, or -1 if indefinite.
297 * RETURNS: gboolean success
300 asn1_eoc ( ASN1_SCK *asn1, int eoc)
303 return (tvb_get_guint8(asn1->tvb, asn1->offset) == 0x00
304 && tvb_get_guint8(asn1->tvb, asn1->offset + 1) == 0x00);
306 return (asn1->offset >= eoc);
310 * NAME: asn1_eoc_decode [API]
311 * SYNOPSIS: int asn1_eoc_decode
316 * DESCRIPTION: Decodes End Of Contents.
318 * asn1: pointer to ASN1 socket.
319 * eoc: offset of end of encoding, or -1 if indefinite.
320 * If eoc is -1 it decodes an ASN1 End Of
321 * Contents (0x00 0x00), so it has to be an
322 * indefinite length encoding. If eoc is a non-negative
323 * integer, it probably was filled by asn1_header_decode,
324 * and should refer to the octet after the last of the encoding.
325 * It is checked if this offset refers to the octet to be
326 * decoded. This only takes place in decoding a
327 * definite length encoding.
328 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
331 asn1_eoc_decode (ASN1_SCK *asn1, int eoc)
337 ret = asn1_octet_decode (asn1, &ch);
338 if (ret != ASN1_ERR_NOERROR)
341 return ASN1_ERR_EOC_MISMATCH;
342 ret = asn1_octet_decode (asn1, &ch);
343 if (ret != ASN1_ERR_NOERROR)
346 return ASN1_ERR_EOC_MISMATCH;
347 return ASN1_ERR_NOERROR;
349 if (asn1->offset != eoc)
350 return ASN1_ERR_LENGTH_MISMATCH;
351 return ASN1_ERR_NOERROR;
356 * NAME: asn1_null_decode [API]
357 * SYNOPSIS: int asn1_null_decode
362 * DESCRIPTION: Decodes Null.
364 * asn1: pointer to ASN1 socket.
365 * enc_len: length of encoding of value.
366 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
369 asn1_null_decode ( ASN1_SCK *asn1, int enc_len)
371 asn1->offset += enc_len;
372 return ASN1_ERR_NOERROR;
376 * NAME: asn1_bool_decode [API]
377 * SYNOPSIS: int asn1_bool_decode
383 * DESCRIPTION: Decodes Boolean.
385 * asn1: pointer to ASN1 socket.
386 * enc_len: length of encoding of value.
387 * bool: False, True (0, !0).
388 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
391 asn1_bool_decode ( ASN1_SCK *asn1, int enc_len, gboolean *bool)
397 return ASN1_ERR_LENGTH_MISMATCH;
398 ret = asn1_octet_decode (asn1, &ch);
399 if (ret != ASN1_ERR_NOERROR)
401 *bool = ch ? TRUE : FALSE;
402 return ASN1_ERR_NOERROR;
406 * NAME: asn1_int32_value_decode [API]
407 * SYNOPSIS: int asn1_int32_value_decode
413 * DESCRIPTION: Decodes value portion of Integer (which must be no more
416 * asn1: pointer to ASN1 socket.
417 * enc_len: length of encoding of value.
419 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
422 asn1_int32_value_decode ( ASN1_SCK *asn1, int enc_len, gint32 *integer)
429 eoc = asn1->offset + enc_len;
430 ret = asn1_octet_decode (asn1, &ch);
431 if (ret != ASN1_ERR_NOERROR)
433 *integer = (gint) ch;
435 while (asn1->offset < eoc) {
436 if (++len > sizeof (gint32))
437 return ASN1_ERR_WRONG_LENGTH_FOR_TYPE;
438 ret = asn1_octet_decode (asn1, &ch);
439 if (ret != ASN1_ERR_NOERROR)
444 return ASN1_ERR_NOERROR;
448 * NAME: asn1_int32_decode [API]
449 * SYNOPSIS: int asn1_int32_decode
455 * DESCRIPTION: Decodes Integer (which must be no more than 32 bits).
457 * asn1: pointer to ASN1 socket.
459 * nbytes: number of bytes used to encode it.
460 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
463 asn1_int32_decode ( ASN1_SCK *asn1, gint32 *integer, guint *nbytes)
473 start = asn1->offset;
474 ret = asn1_header_decode (asn1, &cls, &con, &tag, &def, &enc_len);
475 if (ret != ASN1_ERR_NOERROR)
477 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) {
478 ret = ASN1_ERR_WRONG_TYPE;
482 ret = ASN1_ERR_LENGTH_NOT_DEFINITE;
485 ret = asn1_int32_value_decode (asn1, enc_len, integer);
488 *nbytes = asn1->offset - start;
493 * NAME: asn1_uint32_value_decode [API]
494 * SYNOPSIS: int asn1_uint32_value_decode
500 * DESCRIPTION: Decodes value part of Unsigned Integer (which must be no
501 * more than 32 bits).
503 * asn1: pointer to ASN1 socket.
504 * enc_len: length of encoding of value.
506 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
509 asn1_uint32_value_decode ( ASN1_SCK *asn1, int enc_len, guint *integer)
516 eoc = asn1->offset + enc_len;
517 ret = asn1_octet_decode (asn1, &ch);
518 if (ret != ASN1_ERR_NOERROR)
525 while (asn1->offset < eoc) {
526 if (++len > sizeof (guint32))
527 return ASN1_ERR_WRONG_LENGTH_FOR_TYPE;
528 ret = asn1_octet_decode (asn1, &ch);
529 if (ret != ASN1_ERR_NOERROR)
534 return ASN1_ERR_NOERROR;
538 * NAME: asn1_uint32_decode [API]
539 * SYNOPSIS: int asn1_uint32_decode
545 * DESCRIPTION: Decodes Unsigned Integer (which must be no more than 32 bits).
547 * asn1: pointer to ASN1 socket.
549 * nbytes: number of bytes used to encode it.
550 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
553 asn1_uint32_decode ( ASN1_SCK *asn1, guint32 *integer, guint *nbytes)
563 start = asn1->offset;
564 ret = asn1_header_decode (asn1, &cls, &con, &tag, &def, &enc_len);
565 if (ret != ASN1_ERR_NOERROR)
567 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT) {
568 ret = ASN1_ERR_WRONG_TYPE;
572 ret = ASN1_ERR_LENGTH_NOT_DEFINITE;
575 ret = asn1_uint32_value_decode (asn1, enc_len, integer);
578 *nbytes = asn1->offset - start;
583 * NAME: asn1_bits_decode [API]
584 * SYNOPSIS: int asn1_bits_decode
593 * DESCRIPTION: Decodes Bit String.
595 * asn1: pointer to ASN1 socket.
596 * eoc: offset of end of encoding, or -1 if indefinite.
597 * bits: pointer to begin of Bit String.
598 * size: Size of Bit String in characters.
599 * len: Length of Bit String in characters.
600 * unused: Number of unused bits in last character.
601 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
604 asn1_bits_decode ( ASN1_SCK *asn1, int eoc, guchar **bits,
605 guint *len, guchar *unused)
611 ret = asn1_octet_decode (asn1, unused);
612 if (ret != ASN1_ERR_NOERROR)
615 *bits = g_malloc(eoc - asn1->offset);
616 while (asn1->offset < eoc) {
617 ret = asn1_octet_decode (asn1, (guchar *)bits++);
618 if (ret != ASN1_ERR_NOERROR) {
624 return ASN1_ERR_NOERROR;
628 * NAME: asn1_string_value_decode [API]
629 * SYNOPSIS: int asn1_string_value_decode
635 * DESCRIPTION: Decodes value portion of string (Octet String, various
636 * character string types)
638 * asn1: pointer to ASN1 socket.
639 * enc_len: length of encoding of value.
640 * octets: pointer to variable we set to point to string.
641 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
644 asn1_string_value_decode ( ASN1_SCK *asn1, int enc_len, guchar **octets)
650 eoc = asn1->offset + enc_len;
651 *octets = g_malloc (enc_len);
653 while (asn1->offset < eoc) {
654 ret = asn1_octet_decode (asn1, (guchar *)ptr++);
655 if (ret != ASN1_ERR_NOERROR) {
661 return ASN1_ERR_NOERROR;
665 * NAME: asn1_string_decode [API]
666 * SYNOPSIS: int asn1_string_decode
674 * DESCRIPTION: Decodes string (Octet String, various character string
677 * asn1: pointer to ASN1 socket.
678 * octets: pointer to variable we set to point to string.
679 * str_len: length of octet_string.
680 * nbytes: number of bytes used to encode.
681 * expected_tag: tag expected for this type of string.
682 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
685 asn1_string_decode ( ASN1_SCK *asn1, guchar **octets, guint *str_len,
686 guint *nbytes, guint expected_tag)
696 start = asn1->offset;
697 ret = asn1_header_decode (asn1, &cls, &con, &tag, &def, &enc_len);
698 if (ret != ASN1_ERR_NOERROR)
700 if (cls != ASN1_UNI || con != ASN1_PRI || tag != expected_tag) {
701 /* XXX - handle the constructed encoding? */
702 ret = ASN1_ERR_WRONG_TYPE;
706 ret = ASN1_ERR_LENGTH_NOT_DEFINITE;
710 ret = asn1_string_value_decode (asn1, enc_len, octets);
714 *nbytes = asn1->offset - start;
719 * NAME: asn1_octet_string_decode [API]
720 * SYNOPSIS: int asn1_octet_string_decode
727 * DESCRIPTION: Decodes Octet String.
729 * asn1: pointer to ASN1 socket.
730 * octets: pointer to variable we set to point to string.
731 * str_len: length of octet_string.
732 * nbytes: number of bytes used to encode.
733 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
736 asn1_octet_string_decode ( ASN1_SCK *asn1, guchar **octets, guint *str_len,
739 return asn1_string_decode(asn1, octets, str_len, nbytes, ASN1_OTS);
743 * NAME: asn1_subid_decode
744 * SYNOPSIS: int asn1_subid_decode
749 * DESCRIPTION: Decodes Sub Identifier.
751 * asn1: pointer to ASN1 socket.
752 * subid: Sub Identifier.
753 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
756 asn1_subid_decode ( ASN1_SCK *asn1, subid_t *subid)
763 ret = asn1_octet_decode(asn1, &ch);
764 if (ret != ASN1_ERR_NOERROR)
768 } while ((ch & 0x80) == 0x80);
769 return ASN1_ERR_NOERROR;
773 * NAME: asn1_oid_value_decode [API]
774 * SYNOPSIS: int asn1_oid_value_decode
781 * DESCRIPTION: Decodes value portion of Object Identifier.
783 * asn1: pointer to ASN1 socket.
784 * enc_len: length of encoding of value.
785 * oid: pointer to variable we set to Object Identifier.
786 * len: Length of Object Identifier in gulongs.
787 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
790 asn1_oid_value_decode ( ASN1_SCK *asn1, int enc_len, subid_t **oid, guint *len)
798 eoc = asn1->offset + enc_len;
800 *oid = g_malloc(size * sizeof(gulong));
803 ret = asn1_subid_decode (asn1, &subid);
804 if (ret != ASN1_ERR_NOERROR) {
812 } else if (subid < 80) {
814 optr[1] = subid - 40;
817 optr[1] = subid - 80;
821 while (asn1->offset < eoc) {
822 if (++(*len) > size) {
825 return ASN1_ERR_WRONG_LENGTH_FOR_TYPE;
827 ret = asn1_subid_decode (asn1, optr++);
828 if (ret != ASN1_ERR_NOERROR) {
834 return ASN1_ERR_NOERROR;
838 * NAME: asn1_oid_decode [API]
839 * SYNOPSIS: int asn1_oid_decode
846 * DESCRIPTION: Decodes Object Identifier.
848 * asn1: pointer to ASN1 socket.
849 * oid: pointer to variable we set to Object Identifier.
850 * len: Length of Object Identifier in gulongs.
851 * nbytes: number of bytes used to encode.
852 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
855 asn1_oid_decode ( ASN1_SCK *asn1, subid_t **oid, guint *len, guint *nbytes)
865 start = asn1->offset;
866 ret = asn1_header_decode (asn1, &cls, &con, &tag, &def, &enc_len);
867 if (ret != ASN1_ERR_NOERROR)
869 if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI) {
870 ret = ASN1_ERR_WRONG_TYPE;
874 ret = ASN1_ERR_LENGTH_NOT_DEFINITE;
878 ret = asn1_oid_value_decode (asn1, enc_len, oid, len);
881 *nbytes = asn1->offset - start;
886 * NAME: asn1_sequence_decode [API]
887 * SYNOPSIS: int asn1_sequence_decode
893 * DESCRIPTION: Decodes header for SEQUENCE.
895 * asn1: pointer to ASN1 socket.
896 * seq_len: length of sequence.
897 * nbytes: number of bytes used to encode header.
898 * RETURNS: ASN1_ERR value (ASN1_ERR_NOERROR on success)
901 asn1_sequence_decode ( ASN1_SCK *asn1, guint *seq_len, guint *nbytes)
910 start = asn1->offset;
911 ret = asn1_header_decode(asn1, &cls, &con, &tag,
913 if (ret != ASN1_ERR_NOERROR)
915 if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ) {
916 ret = ASN1_ERR_WRONG_TYPE;
920 /* XXX - might some sequences have an indefinite length? */
921 ret = ASN1_ERR_LENGTH_NOT_DEFINITE;
924 ret = ASN1_ERR_NOERROR;
927 *nbytes = asn1->offset - start;