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 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 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 */ 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 } 152 153 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 } 162 163 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 } 172 173 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 } 182 183 184 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 } 193 194 195 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 } 202 203 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 } 212 213 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 } 222 223 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