source/libsmb/asn1.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    simple SPNEGO routines
   4    Copyright (C) Andrew Tridgell 2001
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 /* free an asn1 structure */
  24 void asn1_free(ASN1_DATA *data)
  25 {
  26         SAFE_FREE(data->data);
  27 }
  28
  29 /* write to the ASN1 buffer, advancing the buffer pointer */
  30 BOOL asn1_write(ASN1_DATA *data, const void *p, int len)
  31 {
  32         if (data->has_error) return False;
  33         if (data->length < data->ofs+len) {
  34                 data->data = SMB_REALLOC(data->data, data->ofs+len);
  35                 if (!data->data) {
  36                         data->has_error = True;
  37                         return False;
  38                 }
  39                 data->length = data->ofs+len;
  40         }
  41         memcpy(data->data + data->ofs, p, len);
  42         data->ofs += len;
  43         return True;
  44 }
  45
  46 /* useful fn for writing a uint8 */
  47 BOOL asn1_write_uint8(ASN1_DATA *data, uint8 v)
  48 {
  49         return asn1_write(data, &v, 1);
  50 }
  51
  52 /* push a tag onto the asn1 data buffer. Used for nested structures */
  53 BOOL asn1_push_tag(ASN1_DATA *data, uint8 tag)
  54 {
  55         struct nesting *nesting;
  56
  57         asn1_write_uint8(data, tag);
  58         nesting = SMB_MALLOC_P(struct nesting);
  59         if (!nesting) {
  60                 data->has_error = True;
  61                 return False;
  62         }
  63
  64         nesting->start = data->ofs;
  65         nesting->next = data->nesting;
  66         data->nesting = nesting;
  67         return asn1_write_uint8(data, 0xff);
  68 }
  69
  70 /* pop a tag */
  71 BOOL asn1_pop_tag(ASN1_DATA *data)
  72 {
  73         struct nesting *nesting;
  74         size_t len;
  75
  76         nesting = data->nesting;
  77
  78         if (!nesting) {
  79                 data->has_error = True;
  80                 return False;
  81         }
  82         len = data->ofs - (nesting->start+1);
  83         /* yes, this is ugly. We don't know in advance how many bytes the length
  84            of a tag will take, so we assumed 1 byte. If we were wrong then we
  85            need to correct our mistake */
  86         if (len > 0xFFFF) {
  87                 data->data[nesting->start] = 0x83;
  88                 if (!asn1_write_uint8(data, 0)) return False;
  89                 if (!asn1_write_uint8(data, 0)) return False;
  90                 if (!asn1_write_uint8(data, 0)) return False;
  91                 memmove(data->data+nesting->start+4, data->data+nesting->start+1, len);
  92                 data->data[nesting->start+1] = (len>>16) & 0xFF;
  93                 data->data[nesting->start+2] = (len>>8) & 0xFF;
  94                 data->data[nesting->start+3] = len&0xff;
  95         } else if (len > 255) {
  96                 data->data[nesting->start] = 0x82;
  97                 if (!asn1_write_uint8(data, 0)) return False;
  98                 if (!asn1_write_uint8(data, 0)) return False;
  99                 memmove(data->data+nesting->start+3, data->data+nesting->start+1, len);
 100                 data->data[nesting->start+1] = len>>8;
 101                 data->data[nesting->start+2] = len&0xff;
 102         } else if (len > 127) {
 103                 data->data[nesting->start] = 0x81;
 104                 if (!asn1_write_uint8(data, 0)) return False;
 105                 memmove(data->data+nesting->start+2, data->data+nesting->start+1, len);
 106                 data->data[nesting->start+1] = len;
 107         } else {
 108                 data->data[nesting->start] = len;
 109         }
 110
 111         data->nesting = nesting->next;
 112         free(nesting);
 113         return True;
 114 }
 115
 116
 117 /* write an integer */
 118 BOOL asn1_write_Integer(ASN1_DATA *data, int i)
 119 {
 120         if (!asn1_push_tag(data, ASN1_INTEGER)) return False;
 121         do {
 122                 asn1_write_uint8(data, i);
 123                 i = i >> 8;
 124         } while (i);
 125         return asn1_pop_tag(data);
 126 }
 127
 128 /* write an object ID to a ASN1 buffer */
 129 BOOL asn1_write_OID(ASN1_DATA *data, const char *OID)
 130 {
 131         unsigned v, v2;
 132         const char *p = (const char *)OID;
 133         char *newp;
 134
 135         if (!asn1_push_tag(data, ASN1_OID))
 136                 return False;
 137         v = strtol(p, &newp, 10);
 138         p = newp;
 139         v2 = strtol(p, &newp, 10);
 140         p = newp;
 141         if (!asn1_write_uint8(data, 40*v + v2))
 142                 return False;
 143
 144         while (*p) {
 145                 v = strtol(p, &newp, 10);
 146                 p = newp;
 147                 if (v >= (1<<28)) asn1_write_uint8(data, 0x80 | ((v>>28)&0xff));
 148                 if (v >= (1<<21)) asn1_write_uint8(data, 0x80 | ((v>>21)&0xff));
 149                 if (v >= (1<<14)) asn1_write_uint8(data, 0x80 | ((v>>14)&0xff));
 150                 if (v >= (1<<7)) asn1_write_uint8(data, 0x80 | ((v>>7)&0xff));
 151                 if (!asn1_write_uint8(data, v&0x7f))
 152                         return False;
 153         }
 154         return asn1_pop_tag(data);
 155 }
 156
 157 /* write an octet string */
 158 BOOL asn1_write_OctetString(ASN1_DATA *data, const void *p, size_t length)
 159 {
 160         asn1_push_tag(data, ASN1_OCTET_STRING);
 161         asn1_write(data, p, length);
 162         asn1_pop_tag(data);
 163         return !data->has_error;
 164 }
 165
 166 /* write a general string */
 167 BOOL asn1_write_GeneralString(ASN1_DATA *data, const char *s)
 168 {
 169         asn1_push_tag(data, ASN1_GENERAL_STRING);
 170         asn1_write(data, s, strlen(s));
 171         asn1_pop_tag(data);
 172         return !data->has_error;
 173 }
 174
 175 /* write a BOOLEAN */
 176 BOOL asn1_write_BOOLEAN(ASN1_DATA *data, BOOL v)
 177 {
 178         asn1_write_uint8(data, ASN1_BOOLEAN);
 179         asn1_write_uint8(data, v);
 180         return !data->has_error;
 181 }
 182
 183 /* write a BOOLEAN - hmm, I suspect this one is the correct one, and the
 184    above boolean is bogus. Need to check */
 185 BOOL asn1_write_BOOLEAN2(ASN1_DATA *data, BOOL v)
 186 {
 187         asn1_push_tag(data, ASN1_BOOLEAN);
 188         asn1_write_uint8(data, v);
 189         asn1_pop_tag(data);
 190         return !data->has_error;
 191 }
 192
 193 /* check a BOOLEAN */
 194 BOOL asn1_check_BOOLEAN(ASN1_DATA *data, BOOL v)
 195 {
 196         uint8 b = 0;
 197
 198         asn1_read_uint8(data, &b);
 199         if (b != ASN1_BOOLEAN) {
 200                 data->has_error = True;
 201                 return False;
 202         }
 203         asn1_read_uint8(data, &b);
 204         if (b != v) {
 205                 data->has_error = True;
 206                 return False;
 207         }
 208         return !data->has_error;
 209 }
 210
 211
 212 /* load a ASN1_DATA structure with a lump of data, ready to be parsed */
 213 BOOL asn1_load(ASN1_DATA *data, DATA_BLOB blob)
 214 {
 215         ZERO_STRUCTP(data);
 216         data->data = memdup(blob.data, blob.length);
 217         if (!data->data) {
 218                 data->has_error = True;
 219                 return False;
 220         }
 221         data->length = blob.length;
 222         return True;
 223 }
 224
 225 /* read from a ASN1 buffer, advancing the buffer pointer */
 226 BOOL asn1_read(ASN1_DATA *data, void *p, int len)
 227 {
 228         if (data->has_error)
 229                 return False;
 230
 231         if (len < 0 || data->ofs + len < data->ofs || data->ofs + len < len) {
 232                 data->has_error = True;
 233                 return False;
 234         }
 235
 236         if (data->ofs + len > data->length) {
 237                 data->has_error = True;
 238                 return False;
 239         }
 240         memcpy(p, data->data + data->ofs, len);
 241         data->ofs += len;
 242         return True;
 243 }
 244
 245 /* read a uint8 from a ASN1 buffer */
 246 BOOL asn1_read_uint8(ASN1_DATA *data, uint8 *v)
 247 {
 248         return asn1_read(data, v, 1);
 249 }
 250
 251 /* start reading a nested asn1 structure */
 252 BOOL asn1_start_tag(ASN1_DATA *data, uint8 tag)
 253 {
 254         uint8 b;
 255         struct nesting *nesting;
 256
 257         if (!asn1_read_uint8(data, &b))
 258                 return False;
 259
 260         if (b != tag) {
 261                 data->has_error = True;
 262                 return False;
 263         }
 264         nesting = SMB_MALLOC_P(struct nesting);
 265         if (!nesting) {
 266                 data->has_error = True;
 267                 return False;
 268         }
 269
 270         if (!asn1_read_uint8(data, &b)) {
 271                 return False;
 272         }
 273
 274         if (b & 0x80) {
 275                 int n = b & 0x7f;
 276                 if (!asn1_read_uint8(data, &b))
 277                         return False;
 278                 nesting->taglen = b;
 279                 while (n > 1) {
 280                         if (!asn1_read_uint8(data, &b))
 281                                 return False;
 282                         nesting->taglen = (nesting->taglen << 8) | b;
 283                         n--;
 284                 }
 285         } else {
 286                 nesting->taglen = b;
 287         }
 288         nesting->start = data->ofs;
 289         nesting->next = data->nesting;
 290         data->nesting = nesting;
 291         return !data->has_error;
 292 }
 293
 294
 295 /* stop reading a tag */
 296 BOOL asn1_end_tag(ASN1_DATA *data)
 297 {
 298         struct nesting *nesting;
 299
 300         /* make sure we read it all */
 301         if (asn1_tag_remaining(data) != 0) {
 302                 data->has_error = True;
 303                 return False;
 304         }
 305
 306         nesting = data->nesting;
 307
 308         if (!nesting) {
 309                 data->has_error = True;
 310                 return False;
 311         }
 312
 313         data->nesting = nesting->next;
 314         free(nesting);
 315         return True;
 316 }
 317
 318 /* work out how many bytes are left in this nested tag */
 319 int asn1_tag_remaining(ASN1_DATA *data)
 320 {
 321         if (data->has_error)
 322                 return 0;
 323
 324         if (!data->nesting) {
 325                 data->has_error = True;
 326                 return -1;
 327         }
 328         return data->nesting->taglen - (data->ofs - data->nesting->start);
 329 }
 330
 331 /* read an object ID from a ASN1 buffer */
 332 BOOL asn1_read_OID(ASN1_DATA *data, char **OID)
 333 {
 334         uint8 b;
 335         pstring oid_str;
 336         fstring el;
 337
 338         if (!asn1_start_tag(data, ASN1_OID)) return False;
 339         asn1_read_uint8(data, &b);
 340
 341         oid_str[0] = 0;
 342         fstr_sprintf(el, "%u",  b/40);
 343         pstrcat(oid_str, el);
 344         fstr_sprintf(el, " %u",  b%40);
 345         pstrcat(oid_str, el);
 346
 347         while (asn1_tag_remaining(data) > 0) {
 348                 unsigned v = 0;
 349                 do {
 350                         asn1_read_uint8(data, &b);
 351                         v = (v<<7) | (b&0x7f);
 352                 } while (!data->has_error && b & 0x80);
 353                 fstr_sprintf(el, " %u",  v);
 354                 pstrcat(oid_str, el);
 355         }
 356
 357         asn1_end_tag(data);
 358
 359         *OID = SMB_STRDUP(oid_str);
 360
 361         return !data->has_error;
 362 }
 363
 364 /* check that the next object ID is correct */
 365 BOOL asn1_check_OID(ASN1_DATA *data, const char *OID)
 366 {
 367         char *id;
 368
 369         if (!asn1_read_OID(data, &id)) return False;
 370
 371         if (strcmp(id, OID) != 0) {
 372                 data->has_error = True;
 373                 return False;
 374         }
 375         free(id);
 376         return True;
 377 }
 378
 379 /* read a GeneralString from a ASN1 buffer */
 380 BOOL asn1_read_GeneralString(ASN1_DATA *data, char **s)
 381 {
 382         int len;
 383         if (!asn1_start_tag(data, ASN1_GENERAL_STRING)) return False;
 384         len = asn1_tag_remaining(data);
 385         if (len < 0) {
 386                 data->has_error = True;
 387                 return False;
 388         }
 389         *s = SMB_MALLOC(len+1);
 390         if (! *s) {
 391                 data->has_error = True;
 392                 return False;
 393         }
 394         asn1_read(data, *s, len);
 395         (*s)[len] = 0;
 396         asn1_end_tag(data);
 397         return !data->has_error;
 398 }
 399
 400 /* read a octet string blob */
 401 BOOL asn1_read_OctetString(ASN1_DATA *data, DATA_BLOB *blob)
 402 {
 403         int len;
 404         ZERO_STRUCTP(blob);
 405         if (!asn1_start_tag(data, ASN1_OCTET_STRING)) return False;
 406         len = asn1_tag_remaining(data);
 407         if (len < 0) {
 408                 data->has_error = True;
 409                 return False;
 410         }
 411         *blob = data_blob(NULL, len);
 412         asn1_read(data, blob->data, len);
 413         asn1_end_tag(data);
 414         return !data->has_error;
 415 }
 416
 417 /* read an interger */
 418 BOOL asn1_read_Integer(ASN1_DATA *data, int *i)
 419 {
 420         uint8 b;
 421         *i = 0;
 422
 423         if (!asn1_start_tag(data, ASN1_INTEGER)) return False;
 424         while (asn1_tag_remaining(data)>0) {
 425                 asn1_read_uint8(data, &b);
 426                 *i = (*i << 8) + b;
 427         }
 428         return asn1_end_tag(data);
 429
 430 }
 431
 432 /* check a enumarted value is correct */
 433 BOOL asn1_check_enumerated(ASN1_DATA *data, int v)
 434 {
 435         uint8 b;
 436         if (!asn1_start_tag(data, ASN1_ENUMERATED)) return False;
 437         asn1_read_uint8(data, &b);
 438         asn1_end_tag(data);
 439
 440         if (v != b)
 441                 data->has_error = False;
 442
 443         return !data->has_error;
 444 }
 445
 446 /* write an enumarted value to the stream */
 447 BOOL asn1_write_enumerated(ASN1_DATA *data, uint8 v)
 448 {
 449         if (!asn1_push_tag(data, ASN1_ENUMERATED)) return False;
 450         asn1_write_uint8(data, v);
 451         asn1_pop_tag(data);
 452         return !data->has_error;
 453 }