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()\
41 asn1_error_code retval;\
42 taginfo 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)\
50 retval = asn1_get_tag_2(buf,&tinfo);\
51 if(retval) return retval;\
52 if(asn1class != UNIVERSAL || construction != PRIMITIVE || tagnum != type)\
53 return ASN1_BAD_ID
54
55 #define cleanup()\
56 return 0
57
58 extern time_t krb5int_gmt_mktime (struct tm *);
59
asn1_decode_integer(asn1buf * buf,long int * val)60 asn1_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
asn1_decode_unsigned_integer(asn1buf * buf,long unsigned int * val)85 asn1_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 */
asn1_decode_maybe_unsigned(asn1buf * buf,unsigned long * val)119 asn1_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
asn1_decode_oid(asn1buf * buf,unsigned int * retlen,asn1_octet ** val)153 asn1_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
asn1_decode_octetstring(asn1buf * buf,unsigned int * retlen,asn1_octet ** val)163 asn1_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
asn1_decode_charstring(asn1buf * buf,unsigned int * retlen,char ** val)173 asn1_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
asn1_decode_generalstring(asn1buf * buf,unsigned int * retlen,char ** val)184 asn1_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
asn1_decode_null(asn1buf * buf)195 asn1_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
asn1_decode_printablestring(asn1buf * buf,int * retlen,char ** val)203 asn1_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
asn1_decode_ia5string(asn1buf * buf,int * retlen,char ** val)213 asn1_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
asn1_decode_generaltime(asn1buf * buf,time_t * val)223 asn1_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
259 done:
260 *val = t;
261 cleanup();
262 }
263