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_ARRAY(data->data, unsigned char,
  35                                                data->ofs+len);
  36                 if (!data->data) {
  37                         data->has_error = True;
  38                         return False;
  39                 }
  40                 data->length = data->ofs+len;
  41         }
  42         memcpy(data->data + data->ofs, p, len);
  43         data->ofs += len;
  44         return True;
  45 }
  46
  47 /* useful fn for writing a uint8 */
  48 BOOL asn1_write_uint8(ASN1_DATA *data, uint8 v)
  49 {
  50         return asn1_write(data, &v, 1);
  51 }
  52
  53 /* push a tag onto the asn1 data buffer. Used for nested structures */
  54 BOOL asn1_push_tag(ASN1_DATA *data, uint8 tag)
  55 {
  56         struct nesting *nesting;
  57
  58         asn1_write_uint8(data, tag);
  59         nesting = SMB_MALLOC_P(struct nesting);
  60         if (!nesting) {
  61                 data->has_error = True;
  62                 return False;
  63         }
  64
  65         nesting->start = data->ofs;
  66         nesting->next = data->nesting;
  67         data->nesting = nesting;
  68         return asn1_write_uint8(data, 0xff);
  69 }
  70
  71 /* pop a tag */
  72 BOOL asn1_pop_tag(ASN1_DATA *data)
  73 {
  74         struct nesting *nesting;
  75         size_t len;
  76
  77         nesting = data->nesting;
  78
  79         if (!nesting) {
  80                 data->has_error = True;
  81                 return False;
  82         }
  83         len = data->ofs - (nesting->start+1);
  84         /* yes, this is ugly. We don't know in advance how many bytes the length
  85            of a tag will take, so we assumed 1 byte. If we were wrong then we
  86            need to correct our mistake */
  87         if (len > 0xFFFF) {
  88                 data->data[nesting->start] = 0x83;
  89                 if (!asn1_write_uint8(data, 0)) return False;
  90                 if (!asn1_write_uint8(data, 0)) return False;
  91                 if (!asn1_write_uint8(data, 0)) return False;
  92                 memmove(data->data+nesting->start+4, data->data+nesting->start+1, len);
  93                 data->data[nesting->start+1] = (len>>16) & 0xFF;
  94                 data->data[nesting->start+2] = (len>>8) & 0xFF;
  95                 data->data[nesting->start+3] = len&0xff;
  96         } else if (len > 255) {
  97                 data->data[nesting->start] = 0x82;
  98                 if (!asn1_write_uint8(data, 0)) return False;
  99                 if (!asn1_write_uint8(data, 0)) return False;
 100                 memmove(data->data+nesting->start+3, data->data+nesting->start+1, len);
 101                 data->data[nesting->start+1] = len>>8;
 102                 data->data[nesting->start+2] = len&0xff;
 103         } else if (len > 127) {
 104                 data->data[nesting->start] = 0x81;
 105                 if (!asn1_write_uint8(data, 0)) return False;
 106                 memmove(data->data+nesting->start+2, data->data+nesting->start+1, len);
 107                 data->data[nesting->start+1] = len;
 108         } else {
 109                 data->data[nesting->start] = len;
 110         }
 111
 112         data->nesting = nesting->next;
 113         free(nesting);
 114         return True;
 115 }
 116
 117
 118 /* write an integer */
 119 BOOL asn1_write_Integer(ASN1_DATA *data, int i)
 120 {
 121         if (!asn1_push_tag(data, ASN1_INTEGER)) return False;
 122         do {
 123                 asn1_write_uint8(data, i);
 124                 i = i >> 8;
 125         } while (i);
 126         return asn1_pop_tag(data);
 127 }
 128
 129 /* write an object ID to a ASN1 buffer */
 130 BOOL asn1_write_OID(ASN1_DATA *data, const char *OID)
 131 {
 132         unsigned v, v2;
 133         const char *p = (const char *)OID;
 134         char *newp;
 135
 136         if (!asn1_push_tag(data, ASN1_OID))
 137                 return False;
 138         v = strtol(p, &newp, 10);
 139         p = newp;
 140         v2 = strtol(p, &newp, 10);
 141         p = newp;
 142         if (!asn1_write_uint8(data, 40*v + v2))
 143                 return False;
 144
 145         while (*p) {
 146                 v = strtol(p, &newp, 10);
 147                 p = newp;
 148                 if (v >= (1<<28)) asn1_write_uint8(data, 0x80 | ((v>>28)&0xff));
 149                 if (v >= (1<<21)) asn1_write_uint8(data, 0x80 | ((v>>21)&0xff));
 150                 if (v >= (1<<14)) asn1_write_uint8(data, 0x80 | ((v>>14)&0xff));
 151                 if (v >= (1<<7)) asn1_write_uint8(data, 0x80 | ((v>>7)&0xff));
 152                 if (!asn1_write_uint8(data, v&0x7f))
 153                         return False;
 154         }
 155         return asn1_pop_tag(data);
 156 }
 157
 158 /* write an octet string */
 159 BOOL asn1_write_OctetString(ASN1_DATA *data, const void *p, size_t length)
 160 {
 161         asn1_push_tag(data, ASN1_OCTET_STRING);
 162         asn1_write(data, p, length);
 163         asn1_pop_tag(data);
 164         return !data->has_error;
 165 }
 166
 167 /* write a general string */
 168 BOOL asn1_write_GeneralString(ASN1_DATA *data, const char *s)
 169 {
 170         asn1_push_tag(data, ASN1_GENERAL_STRING);
 171         asn1_write(data, s, strlen(s));
 172         asn1_pop_tag(data);
 173         return !data->has_error;
 174 }
 175
 176 /* write a BOOLEAN */
 177 BOOL asn1_write_BOOLEAN(ASN1_DATA *data, BOOL v)
 178 {
 179         asn1_write_uint8(data, ASN1_BOOLEAN);
 180         asn1_write_uint8(data, v);
 181         return !data->has_error;
 182 }
 183
 184 /* write a BOOLEAN - hmm, I suspect this one is the correct one, and the
 185    above boolean is bogus. Need to check */
 186 BOOL asn1_write_BOOLEAN2(ASN1_DATA *data, BOOL v)
 187 {
 188         asn1_push_tag(data, ASN1_BOOLEAN);
 189         asn1_write_uint8(data, v);
 190         asn1_pop_tag(data);
 191         return !data->has_error;
 192 }
 193
 194 /* check a BOOLEAN */
 195 BOOL asn1_check_BOOLEAN(ASN1_DATA *data, BOOL v)
 196 {
 197         uint8 b = 0;
 198
 199         asn1_read_uint8(data, &b);
 200         if (b != ASN1_BOOLEAN) {
 201                 data->has_error = True;
 202                 return False;
 203         }
 204         asn1_read_uint8(data, &b);
 205         if (b != v) {
 206                 data->has_error = True;
 207                 return False;
 208         }
 209         return !data->has_error;
 210 }
 211
 212
 213 /* load a ASN1_DATA structure with a lump of data, ready to be parsed */
 214 BOOL asn1_load(ASN1_DATA *data, DATA_BLOB blob)
 215 {
 216         ZERO_STRUCTP(data);
 217         data->data = (unsigned char *)memdup(blob.data, blob.length);
 218         if (!data->data) {
 219                 data->has_error = True;
 220                 return False;
 221         }
 222         data->length = blob.length;
 223         return True;
 224 }
 225
 226 /* read from a ASN1 buffer, advancing the buffer pointer */
 227 BOOL asn1_read(ASN1_DATA *data, void *p, int len)
 228 {
 229         if (data->has_error)
 230                 return False;
 231
 232         if (len < 0 || data->ofs + len < data->ofs || data->ofs + len < len) {
 233                 data->has_error = True;
 234                 return False;
 235         }
 236
 237         if (data->ofs + len > data->length) {
 238                 data->has_error = True;
 239                 return False;
 240         }
 241         memcpy(p, data->data + data->ofs, len);
 242         data->ofs += len;
 243         return True;
 244 }
 245
 246 /* read a uint8 from a ASN1 buffer */
 247 BOOL asn1_read_uint8(ASN1_DATA *data, uint8 *v)
 248 {
 249         return asn1_read(data, v, 1);
 250 }
 251
 252 /* start reading a nested asn1 structure */
 253 BOOL asn1_start_tag(ASN1_DATA *data, uint8 tag)
 254 {
 255         uint8 b;
 256         struct nesting *nesting;
 257
 258         if (!asn1_read_uint8(data, &b))
 259                 return False;
 260
 261         if (b != tag) {
 262                 data->has_error = True;
 263                 return False;
 264         }
 265         nesting = SMB_MALLOC_P(struct nesting);
 266         if (!nesting) {
 267                 data->has_error = True;
 268                 return False;
 269         }
 270
 271         if (!asn1_read_uint8(data, &b)) {
 272                 SAFE_FREE(nesting);
 273                 return False;
 274         }
 275
 276         if (b & 0x80) {
 277                 int n = b & 0x7f;
 278                 if (!asn1_read_uint8(data, &b)) {
 279                         SAFE_FREE(nesting);
 280                         return False;
 281                 }
 282                 nesting->taglen = b;
 283                 while (n > 1) {
 284                         if (!asn1_read_uint8(data, &b)) {
 285                                 SAFE_FREE(nesting);
 286                                 return False;
 287                         }
 288                         nesting->taglen = (nesting->taglen << 8) | b;
 289                         n--;
 290                 }
 291         } else {
 292                 nesting->taglen = b;
 293         }
 294         nesting->start = data->ofs;
 295         nesting->next = data->nesting;
 296         data->nesting = nesting;
 297         return !data->has_error;
 298 }
 299
 300
 301 /* stop reading a tag */
 302 BOOL asn1_end_tag(ASN1_DATA *data)
 303 {
 304         struct nesting *nesting;
 305
 306         /* make sure we read it all */
 307         if (asn1_tag_remaining(data) != 0) {
 308                 data->has_error = True;
 309                 return False;
 310         }
 311
 312         nesting = data->nesting;
 313
 314         if (!nesting) {
 315                 data->has_error = True;
 316                 return False;
 317         }
 318
 319         data->nesting = nesting->next;
 320         free(nesting);
 321         return True;
 322 }
 323
 324 /* work out how many bytes are left in this nested tag */
 325 int asn1_tag_remaining(ASN1_DATA *data)
 326 {
 327         if (data->has_error)
 328                 return 0;
 329
 330         if (!data->nesting) {
 331                 data->has_error = True;
 332                 return -1;
 333         }
 334         return data->nesting->taglen - (data->ofs - data->nesting->start);
 335 }
 336
 337 /* read an object ID from a ASN1 buffer */
 338 BOOL asn1_read_OID(ASN1_DATA *data, char **OID)
 339 {
 340         uint8 b;
 341         pstring oid_str;
 342         fstring el;
 343
 344         *OID = NULL;
 345
 346         if (!asn1_start_tag(data, ASN1_OID)) {
 347                 return False;
 348         }
 349         asn1_read_uint8(data, &b);
 350
 351         oid_str[0] = 0;
 352         fstr_sprintf(el, "%u",  b/40);
 353         pstrcat(oid_str, el);
 354         fstr_sprintf(el, " %u",  b%40);
 355         pstrcat(oid_str, el);
 356
 357         while (asn1_tag_remaining(data) > 0) {
 358                 unsigned v = 0;
 359                 do {
 360                         asn1_read_uint8(data, &b);
 361                         v = (v<<7) | (b&0x7f);
 362                 } while (!data->has_error && b & 0x80);
 363                 fstr_sprintf(el, " %u",  v);
 364                 pstrcat(oid_str, el);
 365         }
 366
 367         asn1_end_tag(data);
 368
 369         if (!data->has_error) {
 370                 *OID = SMB_STRDUP(oid_str);
 371         }
 372
 373         return !data->has_error;
 374 }
 375
 376 /* check that the next object ID is correct */
 377 BOOL asn1_check_OID(ASN1_DATA *data, const char *OID)
 378 {
 379         char *id;
 380
 381         if (!asn1_read_OID(data, &id)) {
 382                 return False;
 383         }
 384
 385         if (strcmp(id, OID) != 0) {
 386                 data->has_error = True;
 387                 return False;
 388         }
 389         free(id);
 390         return True;
 391 }
 392
 393 /* read a GeneralString from a ASN1 buffer */
 394 BOOL asn1_read_GeneralString(ASN1_DATA *data, char **s)
 395 {
 396         int len;
 397         char *str;
 398
 399         *s = NULL;
 400
 401         if (!asn1_start_tag(data, ASN1_GENERAL_STRING)) {
 402                 return False;
 403         }
 404         len = asn1_tag_remaining(data);
 405         if (len < 0) {
 406                 data->has_error = True;
 407                 return False;
 408         }
 409         str = SMB_MALLOC_ARRAY(char, len+1);
 410         if (!str) {
 411                 data->has_error = True;
 412                 return False;
 413         }
 414         asn1_read(data, str, len);
 415         str[len] = 0;
 416         asn1_end_tag(data);
 417
 418         if (!data->has_error) {
 419                 *s = str;
 420         }
 421         return !data->has_error;
 422 }
 423
 424 /* read a octet string blob */
 425 BOOL asn1_read_OctetString(ASN1_DATA *data, DATA_BLOB *blob)
 426 {
 427         int len;
 428         ZERO_STRUCTP(blob);
 429         if (!asn1_start_tag(data, ASN1_OCTET_STRING)) return False;
 430         len = asn1_tag_remaining(data);
 431         if (len < 0) {
 432                 data->has_error = True;
 433                 return False;
 434         }
 435         *blob = data_blob(NULL, len);
 436         asn1_read(data, blob->data, len);
 437         asn1_end_tag(data);
 438         return !data->has_error;
 439 }
 440
 441 /* read an interger */
 442 BOOL asn1_read_Integer(ASN1_DATA *data, int *i)
 443 {
 444         uint8 b;
 445         *i = 0;
 446
 447         if (!asn1_start_tag(data, ASN1_INTEGER)) return False;
 448         while (asn1_tag_remaining(data)>0) {
 449                 asn1_read_uint8(data, &b);
 450                 *i = (*i << 8) + b;
 451         }
 452         return asn1_end_tag(data);
 453
 454 }
 455
 456 /* check a enumarted value is correct */
 457 BOOL asn1_check_enumerated(ASN1_DATA *data, int v)
 458 {
 459         uint8 b;
 460         if (!asn1_start_tag(data, ASN1_ENUMERATED)) return False;
 461         asn1_read_uint8(data, &b);
 462         asn1_end_tag(data);
 463
 464         if (v != b)
 465                 data->has_error = False;
 466
 467         return !data->has_error;
 468 }
 469
 470 /* write an enumarted value to the stream */
 471 BOOL asn1_write_enumerated(ASN1_DATA *data, uint8 v)
 472 {
 473         if (!asn1_push_tag(data, ASN1_ENUMERATED)) return False;
 474         asn1_write_uint8(data, v);
 475         asn1_pop_tag(data);
 476         return !data->has_error;
 477 }