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