1/*
2 * src/lib/krb5/asn.1/asn1_decode.c
3 *
4 * Copyright 1994, 2003 by the Massachusetts Institute of Technology.
5 * All Rights Reserved.
6 *
7 * Export of this software from the United States of America may
8 *   require a specific license from the United States Government.
9 *   It is the responsibility of any person or organization contemplating
10 *   export to obtain such a license before exporting.
11 *
12 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13 * distribute this software and its documentation for any purpose and
14 * without fee is hereby granted, provided that the above copyright
15 * notice appear in all copies and that both that copyright notice and
16 * this permission notice appear in supporting documentation, and that
17 * the name of M.I.T. not be used in advertising or publicity pertaining
18 * to distribution of the software without specific, written prior
19 * permission.  Furthermore if you modify this software you must label
20 * your software as modified software and not distribute it in such a
21 * fashion that it might be confused with the original M.I.T. software.
22 * M.I.T. makes no representations about the suitability of
23 * this software for any purpose.  It is provided "as is" without express
24 * or implied warranty.
25 */
26
27/* ASN.1 primitive decoders */
28#include "asn1_decode.h"
29#include "asn1_get.h"
30#include <stdio.h>
31#ifdef HAVE_SYS_TIME_H
32#include <sys/time.h>
33#ifdef TIME_WITH_SYS_TIME
34#include <time.h>
35#endif
36#else
37#include <time.h>
38#endif
39
40#define setup()\
41asn1_error_code retval;\
42taginfo tinfo
43
44#define asn1class	(tinfo.asn1class)
45#define construction	(tinfo.construction)
46#define tagnum		(tinfo.tagnum)
47#define length		(tinfo.length)
48
49#define tag(type)\
50retval = asn1_get_tag_2(buf,&tinfo);\
51if(retval) return retval;\
52if(asn1class != UNIVERSAL || construction != PRIMITIVE || tagnum != type)\
53  return ASN1_BAD_ID
54
55#define cleanup()\
56return 0
57
58extern time_t krb5int_gmt_mktime (struct tm *);
59
60asn1_error_code asn1_decode_integer(asn1buf *buf, long int *val)
61{
62  setup();
63  asn1_octet o;
64  long n = 0; /* initialize to keep gcc happy */
65  int i;
66
67  tag(ASN1_INTEGER);
68
69  for (i = 0; i < length; i++) {
70    retval = asn1buf_remove_octet(buf, &o);
71    if (retval) return retval;
72    if (!i) {
73      n = (0x80 & o) ? -1 : 0;	/* grab sign bit */
74      if (n < 0 && length > sizeof (long))
75	return ASN1_OVERFLOW;
76      else if (length > sizeof (long) + 1) /* allow extra octet for positive */
77	return ASN1_OVERFLOW;
78    }
79    n = (n << 8) | o;
80  }
81  *val = n;
82  cleanup();
83}
84
85asn1_error_code asn1_decode_unsigned_integer(asn1buf *buf, long unsigned int *val)
86{
87  setup();
88  asn1_octet o;
89  unsigned long n;
90  int i;
91
92  tag(ASN1_INTEGER);
93
94  for (i = 0, n = 0; i < length; i++) {
95    retval = asn1buf_remove_octet(buf, &o);
96    if(retval) return retval;
97    if (!i) {
98      if (0x80 & o)
99	return ASN1_OVERFLOW;
100      else if (length > sizeof (long) + 1)
101	return ASN1_OVERFLOW;
102    }
103    n = (n << 8) | o;
104  }
105  *val = n;
106  cleanup();
107}
108
109/*
110 * asn1_decode_maybe_unsigned
111 *
112 * This is needed because older releases of MIT krb5 have signed
113 * sequence numbers.  We want to accept both signed and unsigned
114 * sequence numbers, in the range -2^31..2^32-1, mapping negative
115 * numbers into their positive equivalents in the same way that C's
116 * normal integer conversions do, i.e., would preserve bits on a
117 * two's-complement architecture.
118 */
119asn1_error_code asn1_decode_maybe_unsigned(asn1buf *buf, unsigned long *val)
120{
121  setup();
122  asn1_octet o;
123  unsigned long n, bitsremain;
124  unsigned int i;
125
126  tag(ASN1_INTEGER);
127  o = 0;
128  n = 0;
129  bitsremain = ~0UL;
130  for (i = 0; i < length; i++) {
131    /* Accounts for u_long width not being a multiple of 8. */
132    if (bitsremain < 0xff) return ASN1_OVERFLOW;
133    retval = asn1buf_remove_octet(buf, &o);
134    if (retval) return retval;
135    if (bitsremain == ~0UL) {
136      if (i == 0)
137	n = (o & 0x80) ? ~0UL : 0UL; /* grab sign bit */
138      /*
139       * Skip leading zero or 0xFF octets to humor non-compliant encoders.
140       */
141      if (n == 0 && o == 0)
142	continue;
143      if (n == ~0UL && o == 0xff)
144	continue;
145    }
146    n = (n << 8) | o;
147    bitsremain >>= 8;
148  }
149  *val = n;
150  cleanup();
151}
152
153asn1_error_code asn1_decode_oid(asn1buf *buf, unsigned int *retlen, asn1_octet **val)
154{
155  setup();
156  tag(ASN1_OBJECTIDENTIFIER);
157  retval = asn1buf_remove_octetstring(buf, length, val);
158  if (retval) return retval;
159  *retlen = length;
160  cleanup();
161}
162
163asn1_error_code asn1_decode_octetstring(asn1buf *buf, unsigned int *retlen, asn1_octet **val)
164{
165  setup();
166  tag(ASN1_OCTETSTRING);
167  retval = asn1buf_remove_octetstring(buf,length,val);
168  if(retval) return retval;
169  *retlen = length;
170  cleanup();
171}
172
173asn1_error_code asn1_decode_charstring(asn1buf *buf, unsigned int *retlen, char **val)
174{
175  setup();
176  tag(ASN1_OCTETSTRING);
177  retval = asn1buf_remove_charstring(buf,length,val);
178  if(retval) return retval;
179  *retlen = length;
180  cleanup();
181}
182
183
184asn1_error_code asn1_decode_generalstring(asn1buf *buf, unsigned int *retlen, char **val)
185{
186  setup();
187  tag(ASN1_GENERALSTRING);
188  retval = asn1buf_remove_charstring(buf,length,val);
189  if(retval) return retval;
190  *retlen = length;
191  cleanup();
192}
193
194
195asn1_error_code asn1_decode_null(asn1buf *buf)
196{
197  setup();
198  tag(ASN1_NULL);
199  if(length != 0) return ASN1_BAD_LENGTH;
200  cleanup();
201}
202
203asn1_error_code asn1_decode_printablestring(asn1buf *buf, int *retlen, char **val)
204{
205  setup();
206  tag(ASN1_PRINTABLESTRING);
207  retval = asn1buf_remove_charstring(buf,length,val);
208  if(retval) return retval;
209  *retlen = length;
210  cleanup();
211}
212
213asn1_error_code asn1_decode_ia5string(asn1buf *buf, int *retlen, char **val)
214{
215  setup();
216  tag(ASN1_IA5STRING);
217  retval = asn1buf_remove_charstring(buf,length,val);
218  if(retval) return retval;
219  *retlen = length;
220  cleanup();
221}
222
223asn1_error_code asn1_decode_generaltime(asn1buf *buf, time_t *val)
224{
225  setup();
226  char *s;
227  struct tm ts;
228  time_t t;
229
230  tag(ASN1_GENERALTIME);
231
232  if(length != 15) return ASN1_BAD_LENGTH;
233  retval = asn1buf_remove_charstring(buf,15,&s);
234  if (retval) return retval;
235  /* Time encoding: YYYYMMDDhhmmssZ */
236  if(s[14] != 'Z') {
237      free(s);
238      return ASN1_BAD_FORMAT;
239  }
240  if(s[0] == '1' && !memcmp("19700101000000Z", s, 15)) {
241      t = 0;
242      free(s);
243      goto done;
244  }
245#define c2i(c) ((c)-'0')
246  ts.tm_year = 1000*c2i(s[0]) + 100*c2i(s[1]) + 10*c2i(s[2]) + c2i(s[3])
247    - 1900;
248  ts.tm_mon = 10*c2i(s[4]) + c2i(s[5]) - 1;
249  ts.tm_mday = 10*c2i(s[6]) + c2i(s[7]);
250  ts.tm_hour = 10*c2i(s[8]) + c2i(s[9]);
251  ts.tm_min = 10*c2i(s[10]) + c2i(s[11]);
252  ts.tm_sec = 10*c2i(s[12]) + c2i(s[13]);
253  ts.tm_isdst = -1;
254  t = krb5int_gmt_mktime(&ts);
255  free(s);
256
257  if(t == -1) return ASN1_BAD_TIMEFORMAT;
258
259done:
260  *val = t;
261  cleanup();
262}
263