lib/ldb/common/ldb_match.c

   1 /*
   2    ldb database library
   3
   4    Copyright (C) Andrew Tridgell  2004-2005
   5    Copyright (C) Simo Sorce            2005
   6
   7      ** NOTE! The following LGPL license applies to the ldb
   8      ** library. This does NOT imply that all of Samba is released
   9      ** under the LGPL
  10
  11    This library is free software; you can redistribute it and/or
  12    modify it under the terms of the GNU Lesser General Public
  13    License as published by the Free Software Foundation; either
  14    version 3 of the License, or (at your option) any later version.
  15
  16    This library is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Lesser General Public License for more details.
  20
  21    You should have received a copy of the GNU Lesser General Public
  22    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 /*
  26  *  Name: ldb
  27  *
  28  *  Component: ldb expression matching
  29  *
  30  *  Description: ldb expression matching
  31  *
  32  *  Author: Andrew Tridgell
  33  */
  34
  35 #include "ldb_private.h"
  36 #include "dlinklist.h"
  37
  38 /*
  39   check if the scope matches in a search result
  40 */
  41 static int ldb_match_scope(struct ldb_context *ldb,
  42                            struct ldb_dn *base,
  43                            struct ldb_dn *dn,
  44                            enum ldb_scope scope)
  45 {
  46         int ret = 0;
  47
  48         if (base == NULL || dn == NULL) {
  49                 return 1;
  50         }
  51
  52         switch (scope) {
  53         case LDB_SCOPE_BASE:
  54                 if (ldb_dn_compare(base, dn) == 0) {
  55                         ret = 1;
  56                 }
  57                 break;
  58
  59         case LDB_SCOPE_ONELEVEL:
  60                 if (ldb_dn_get_comp_num(dn) == (ldb_dn_get_comp_num(base) + 1)) {
  61                         if (ldb_dn_compare_base(base, dn) == 0) {
  62                                 ret = 1;
  63                         }
  64                 }
  65                 break;
  66
  67         case LDB_SCOPE_SUBTREE:
  68         default:
  69                 if (ldb_dn_compare_base(base, dn) == 0) {
  70                         ret = 1;
  71                 }
  72                 break;
  73         }
  74
  75         return ret;
  76 }
  77
  78
  79 /*
  80   match if node is present
  81 */
  82 static int ldb_match_present(struct ldb_context *ldb,
  83                              const struct ldb_message *msg,
  84                              const struct ldb_parse_tree *tree,
  85                              enum ldb_scope scope, bool *matched)
  86 {
  87         const struct ldb_schema_attribute *a;
  88         struct ldb_message_element *el;
  89
  90         if (ldb_attr_dn(tree->u.present.attr) == 0) {
  91                 *matched = true;
  92                 return LDB_SUCCESS;
  93         }
  94
  95         el = ldb_msg_find_element(msg, tree->u.present.attr);
  96         if (el == NULL) {
  97                 *matched = false;
  98                 return LDB_SUCCESS;
  99         }
 100
 101         a = ldb_schema_attribute_by_name(ldb, el->name);
 102         if (!a) {
 103                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 104         }
 105
 106         if (a->syntax->operator_fn) {
 107                 unsigned int i;
 108                 for (i = 0; i < el->num_values; i++) {
 109                         int ret = a->syntax->operator_fn(ldb, LDB_OP_PRESENT, a, &el->values[i], NULL, matched);
 110                         if (ret != LDB_SUCCESS) return ret;
 111                         if (*matched) return LDB_SUCCESS;
 112                 }
 113                 *matched = false;
 114                 return LDB_SUCCESS;
 115         }
 116
 117         *matched = true;
 118         return LDB_SUCCESS;
 119 }
 120
 121 static int ldb_match_comparison(struct ldb_context *ldb,
 122                                 const struct ldb_message *msg,
 123                                 const struct ldb_parse_tree *tree,
 124                                 enum ldb_scope scope,
 125                                 enum ldb_parse_op comp_op, bool *matched)
 126 {
 127         unsigned int i;
 128         struct ldb_message_element *el;
 129         const struct ldb_schema_attribute *a;
 130
 131         /* FIXME: APPROX comparison not handled yet */
 132         if (comp_op == LDB_OP_APPROX) {
 133                 return LDB_ERR_INAPPROPRIATE_MATCHING;
 134         }
 135
 136         el = ldb_msg_find_element(msg, tree->u.comparison.attr);
 137         if (el == NULL) {
 138                 *matched = false;
 139                 return LDB_SUCCESS;
 140         }
 141
 142         a = ldb_schema_attribute_by_name(ldb, el->name);
 143         if (!a) {
 144                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 145         }
 146
 147         for (i = 0; i < el->num_values; i++) {
 148                 if (a->syntax->operator_fn) {
 149                         int ret;
 150                         ret = a->syntax->operator_fn(ldb, comp_op, a, &el->values[i], &tree->u.comparison.value, matched);
 151                         if (ret != LDB_SUCCESS) return ret;
 152                         if (*matched) return LDB_SUCCESS;
 153                 } else {
 154                         int ret = a->syntax->comparison_fn(ldb, ldb, &el->values[i], &tree->u.comparison.value);
 155
 156                         if (ret == 0) {
 157                                 *matched = true;
 158                                 return LDB_SUCCESS;
 159                         }
 160                         if (ret > 0 && comp_op == LDB_OP_GREATER) {
 161                                 *matched = true;
 162                                 return LDB_SUCCESS;
 163                         }
 164                         if (ret < 0 && comp_op == LDB_OP_LESS) {
 165                                 *matched = true;
 166                                 return LDB_SUCCESS;
 167                         }
 168                 }
 169         }
 170
 171         *matched = false;
 172         return LDB_SUCCESS;
 173 }
 174
 175 /*
 176   match a simple leaf node
 177 */
 178 static int ldb_match_equality(struct ldb_context *ldb,
 179                               const struct ldb_message *msg,
 180                               const struct ldb_parse_tree *tree,
 181                               enum ldb_scope scope,
 182                               bool *matched)
 183 {
 184         unsigned int i;
 185         struct ldb_message_element *el;
 186         const struct ldb_schema_attribute *a;
 187         struct ldb_dn *valuedn;
 188         int ret;
 189
 190         if (ldb_attr_dn(tree->u.equality.attr) == 0) {
 191                 valuedn = ldb_dn_from_ldb_val(ldb, ldb, &tree->u.equality.value);
 192                 if (valuedn == NULL) {
 193                         return LDB_ERR_INVALID_DN_SYNTAX;
 194                 }
 195
 196                 ret = ldb_dn_compare(msg->dn, valuedn);
 197
 198                 talloc_free(valuedn);
 199
 200                 *matched = (ret == 0);
 201                 return LDB_SUCCESS;
 202         }
 203
 204         /* TODO: handle the "*" case derived from an extended search
 205            operation without the attibute type defined */
 206         el = ldb_msg_find_element(msg, tree->u.equality.attr);
 207         if (el == NULL) {
 208                 *matched = false;
 209                 return LDB_SUCCESS;
 210         }
 211
 212         a = ldb_schema_attribute_by_name(ldb, el->name);
 213         if (a == NULL) {
 214                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 215         }
 216
 217         for (i=0;i<el->num_values;i++) {
 218                 if (a->syntax->operator_fn) {
 219                         ret = a->syntax->operator_fn(ldb, LDB_OP_EQUALITY, a,
 220                                                      &tree->u.equality.value, &el->values[i], matched);
 221                         if (ret != LDB_SUCCESS) return ret;
 222                         if (*matched) return LDB_SUCCESS;
 223                 } else {
 224                         if (a->syntax->comparison_fn(ldb, ldb, &tree->u.equality.value,
 225                                                      &el->values[i]) == 0) {
 226                                 *matched = true;
 227                                 return LDB_SUCCESS;
 228                         }
 229                 }
 230         }
 231
 232         *matched = false;
 233         return LDB_SUCCESS;
 234 }
 235
 236 static int ldb_wildcard_compare(struct ldb_context *ldb,
 237                                 const struct ldb_parse_tree *tree,
 238                                 const struct ldb_val value, bool *matched)
 239 {
 240         const struct ldb_schema_attribute *a;
 241         struct ldb_val val;
 242         struct ldb_val cnk;
 243         struct ldb_val *chunk;
 244         uint8_t *save_p = NULL;
 245         unsigned int c = 0;
 246
 247         a = ldb_schema_attribute_by_name(ldb, tree->u.substring.attr);
 248         if (!a) {
 249                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 250         }
 251
 252         if (tree->u.substring.chunks == NULL) {
 253                 *matched = false;
 254                 return LDB_SUCCESS;
 255         }
 256
 257         if (a->syntax->canonicalise_fn(ldb, ldb, &value, &val) != 0) {
 258                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 259         }
 260
 261         save_p = val.data;
 262         cnk.data = NULL;
 263
 264         if ( ! tree->u.substring.start_with_wildcard ) {
 265
 266                 chunk = tree->u.substring.chunks[c];
 267                 if (a->syntax->canonicalise_fn(ldb, ldb, chunk, &cnk) != 0) goto mismatch;
 268
 269                 /* This deals with wildcard prefix searches on binary attributes (eg objectGUID) */
 270                 if (cnk.length > val.length) {
 271                         goto mismatch;
 272                 }
 273                 /*
 274                  * Empty strings are returned as length 0. Ensure
 275                  * we can cope with this.
 276                  */
 277                 if (cnk.length == 0) {
 278                         goto mismatch;
 279                 }
 280
 281                 if (memcmp((char *)val.data, (char *)cnk.data, cnk.length) != 0) goto mismatch;
 282                 val.length -= cnk.length;
 283                 val.data += cnk.length;
 284                 c++;
 285                 talloc_free(cnk.data);
 286                 cnk.data = NULL;
 287         }
 288
 289         while (tree->u.substring.chunks[c]) {
 290                 uint8_t *p;
 291
 292                 chunk = tree->u.substring.chunks[c];
 293                 if(a->syntax->canonicalise_fn(ldb, ldb, chunk, &cnk) != 0) goto mismatch;
 294
 295                 /*
 296                  * Empty strings are returned as length 0. Ensure
 297                  * we can cope with this.
 298                  */
 299                 if (cnk.length == 0) {
 300                         goto mismatch;
 301                 }
 302                 /*
 303                  * Values might be binary blobs. Don't use string
 304                  * search, but memory search instead.
 305                  */
 306                 p = memmem((const void *)val.data,val.length,
 307                            (const void *)cnk.data, cnk.length);
 308                 if (p == NULL) goto mismatch;
 309                 if ( (! tree->u.substring.chunks[c + 1]) && (! tree->u.substring.end_with_wildcard) ) {
 310                         uint8_t *g;
 311                         do { /* greedy */
 312                                 g = memmem(p + cnk.length,
 313                                         val.length - (p - val.data),
 314                                         (const uint8_t *)cnk.data,
 315                                         cnk.length);
 316                                 if (g) p = g;
 317                         } while(g);
 318                 }
 319                 val.length = val.length - (p - (uint8_t *)(val.data)) - cnk.length;
 320                 val.data = (uint8_t *)(p + cnk.length);
 321                 c++;
 322                 talloc_free(cnk.data);
 323                 cnk.data = NULL;
 324         }
 325
 326         /* last chunk may not have reached end of string */
 327         if ( (! tree->u.substring.end_with_wildcard) && (*(val.data) != 0) ) goto mismatch;
 328         talloc_free(save_p);
 329         *matched = true;
 330         return LDB_SUCCESS;
 331
 332 mismatch:
 333         *matched = false;
 334         talloc_free(save_p);
 335         talloc_free(cnk.data);
 336         return LDB_SUCCESS;
 337 }
 338
 339 /*
 340   match a simple leaf node
 341 */
 342 static int ldb_match_substring(struct ldb_context *ldb,
 343                                const struct ldb_message *msg,
 344                                const struct ldb_parse_tree *tree,
 345                                enum ldb_scope scope, bool *matched)
 346 {
 347         unsigned int i;
 348         struct ldb_message_element *el;
 349
 350         el = ldb_msg_find_element(msg, tree->u.substring.attr);
 351         if (el == NULL) {
 352                 *matched = false;
 353                 return LDB_SUCCESS;
 354         }
 355
 356         for (i = 0; i < el->num_values; i++) {
 357                 int ret;
 358                 ret = ldb_wildcard_compare(ldb, tree, el->values[i], matched);
 359                 if (ret != LDB_SUCCESS) return ret;
 360                 if (*matched) return LDB_SUCCESS;
 361         }
 362
 363         *matched = false;
 364         return LDB_SUCCESS;
 365 }
 366
 367
 368 /*
 369   bitwise and/or comparator depending on oid
 370 */
 371 static int ldb_comparator_bitmask(const char *oid, const struct ldb_val *v1, const struct ldb_val *v2,
 372                                   bool *matched)
 373 {
 374         uint64_t i1, i2;
 375         char ibuf[100];
 376         char *endptr = NULL;
 377
 378         if (v1->length >= sizeof(ibuf)-1) {
 379                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 380         }
 381         memcpy(ibuf, (char *)v1->data, v1->length);
 382         ibuf[v1->length] = 0;
 383         i1 = strtoull(ibuf, &endptr, 0);
 384         if (endptr != NULL) {
 385                 if (endptr == ibuf || *endptr != 0) {
 386                         return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 387                 }
 388         }
 389
 390         if (v2->length >= sizeof(ibuf)-1) {
 391                 return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 392         }
 393         endptr = NULL;
 394         memcpy(ibuf, (char *)v2->data, v2->length);
 395         ibuf[v2->length] = 0;
 396         i2 = strtoull(ibuf, &endptr, 0);
 397         if (endptr != NULL) {
 398                 if (endptr == ibuf || *endptr != 0) {
 399                         return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
 400                 }
 401         }
 402         if (strcmp(LDB_OID_COMPARATOR_AND, oid) == 0) {
 403                 *matched = ((i1 & i2) == i2);
 404         } else if (strcmp(LDB_OID_COMPARATOR_OR, oid) == 0) {
 405                 *matched = ((i1 & i2) != 0);
 406         } else {
 407                 return LDB_ERR_INAPPROPRIATE_MATCHING;
 408         }
 409         return LDB_SUCCESS;
 410 }
 411
 412 static int ldb_match_bitmask(struct ldb_context *ldb,
 413                              const char *oid,
 414                              const struct ldb_message *msg,
 415                              const char *attribute_to_match,
 416                              const struct ldb_val *value_to_match,
 417                              bool *matched)
 418 {
 419         unsigned int i;
 420         struct ldb_message_element *el;
 421
 422         /* find the message element */
 423         el = ldb_msg_find_element(msg, attribute_to_match);
 424         if (el == NULL) {
 425                 *matched = false;
 426                 return LDB_SUCCESS;
 427         }
 428
 429         for (i=0;i<el->num_values;i++) {
 430                 int ret;
 431                 struct ldb_val *v = &el->values[i];
 432
 433                 ret = ldb_comparator_bitmask(oid, v, value_to_match, matched);
 434                 if (ret != LDB_SUCCESS) {
 435                         return ret;
 436                 }
 437                 if (*matched) {
 438                         return LDB_SUCCESS;
 439                 }
 440         }
 441
 442         *matched = false;
 443         return LDB_SUCCESS;
 444 }
 445
 446 /*
 447   always return false
 448 */
 449 static int ldb_comparator_false(struct ldb_context *ldb,
 450                                 const char *oid,
 451                                 const struct ldb_message *msg,
 452                                 const char *attribute_to_match,
 453                                 const struct ldb_val *value_to_match,
 454                                 bool *matched)
 455 {
 456         *matched = false;
 457         return LDB_SUCCESS;
 458 }
 459
 460
 461 static const struct ldb_extended_match_rule *ldb_find_extended_match_rule(struct ldb_context *ldb,
 462                                                                           const char *oid)
 463 {
 464         struct ldb_extended_match_entry *extended_match_rule;
 465
 466         for (extended_match_rule = ldb->extended_match_rules;
 467              extended_match_rule;
 468              extended_match_rule = extended_match_rule->next) {
 469                 if (strcmp(extended_match_rule->rule->oid, oid) == 0) {
 470                         return extended_match_rule->rule;
 471                 }
 472         }
 473
 474         return NULL;
 475 }
 476
 477
 478 /*
 479   extended match, handles things like bitops
 480 */
 481 static int ldb_match_extended(struct ldb_context *ldb,
 482                               const struct ldb_message *msg,
 483                               const struct ldb_parse_tree *tree,
 484                               enum ldb_scope scope, bool *matched)
 485 {
 486         const struct ldb_extended_match_rule *rule;
 487
 488         if (tree->u.extended.dnAttributes) {
 489                 /* FIXME: We really need to find out what this ":dn" part in
 490                  * an extended match means and how to handle it. For now print
 491                  * only a warning to have s3 winbind and other tools working
 492                  * against us. - Matthias */
 493                 ldb_debug(ldb, LDB_DEBUG_WARNING, "ldb: dnAttributes extended match not supported yet");
 494         }
 495         if (tree->u.extended.rule_id == NULL) {
 496                 ldb_debug(ldb, LDB_DEBUG_ERROR, "ldb: no-rule extended matches not supported yet");
 497                 return LDB_ERR_INAPPROPRIATE_MATCHING;
 498         }
 499         if (tree->u.extended.attr == NULL) {
 500                 ldb_debug(ldb, LDB_DEBUG_ERROR, "ldb: no-attribute extended matches not supported yet");
 501                 return LDB_ERR_INAPPROPRIATE_MATCHING;
 502         }
 503
 504         rule = ldb_find_extended_match_rule(ldb, tree->u.extended.rule_id);
 505         if (rule == NULL) {
 506                 *matched = false;
 507                 ldb_debug(ldb, LDB_DEBUG_ERROR, "ldb: unknown extended rule_id %s",
 508                           tree->u.extended.rule_id);
 509                 return LDB_SUCCESS;
 510         }
 511
 512         return rule->callback(ldb, rule->oid, msg,
 513                               tree->u.extended.attr,
 514                               &tree->u.extended.value, matched);
 515 }
 516
 517 /*
 518   return 0 if the given parse tree matches the given message. Assumes
 519   the message is in sorted order
 520
 521   return 1 if it matches, and 0 if it doesn't match
 522
 523   this is a recursive function, and does short-circuit evaluation
 524  */
 525 static int ldb_match_message(struct ldb_context *ldb,
 526                              const struct ldb_message *msg,
 527                              const struct ldb_parse_tree *tree,
 528                              enum ldb_scope scope, bool *matched)
 529 {
 530         unsigned int i;
 531         int ret;
 532
 533         *matched = false;
 534
 535         if (scope != LDB_SCOPE_BASE && ldb_dn_is_special(msg->dn)) {
 536                 /* don't match special records except on base searches */
 537                 return LDB_SUCCESS;
 538         }
 539
 540         switch (tree->operation) {
 541         case LDB_OP_AND:
 542                 for (i=0;i<tree->u.list.num_elements;i++) {
 543                         ret = ldb_match_message(ldb, msg, tree->u.list.elements[i], scope, matched);
 544                         if (ret != LDB_SUCCESS) return ret;
 545                         if (!*matched) return LDB_SUCCESS;
 546                 }
 547                 *matched = true;
 548                 return LDB_SUCCESS;
 549
 550         case LDB_OP_OR:
 551                 for (i=0;i<tree->u.list.num_elements;i++) {
 552                         ret = ldb_match_message(ldb, msg, tree->u.list.elements[i], scope, matched);
 553                         if (ret != LDB_SUCCESS) return ret;
 554                         if (*matched) return LDB_SUCCESS;
 555                 }
 556                 *matched = false;
 557                 return LDB_SUCCESS;
 558
 559         case LDB_OP_NOT:
 560                 ret = ldb_match_message(ldb, msg, tree->u.isnot.child, scope, matched);
 561                 if (ret != LDB_SUCCESS) return ret;
 562                 *matched = ! *matched;
 563                 return LDB_SUCCESS;
 564
 565         case LDB_OP_EQUALITY:
 566                 return ldb_match_equality(ldb, msg, tree, scope, matched);
 567
 568         case LDB_OP_SUBSTRING:
 569                 return ldb_match_substring(ldb, msg, tree, scope, matched);
 570
 571         case LDB_OP_GREATER:
 572                 return ldb_match_comparison(ldb, msg, tree, scope, LDB_OP_GREATER, matched);
 573
 574         case LDB_OP_LESS:
 575                 return ldb_match_comparison(ldb, msg, tree, scope, LDB_OP_LESS, matched);
 576
 577         case LDB_OP_PRESENT:
 578                 return ldb_match_present(ldb, msg, tree, scope, matched);
 579
 580         case LDB_OP_APPROX:
 581                 return ldb_match_comparison(ldb, msg, tree, scope, LDB_OP_APPROX, matched);
 582
 583         case LDB_OP_EXTENDED:
 584                 return ldb_match_extended(ldb, msg, tree, scope, matched);
 585         }
 586
 587         return LDB_ERR_INAPPROPRIATE_MATCHING;
 588 }
 589
 590 int ldb_match_msg(struct ldb_context *ldb,
 591                   const struct ldb_message *msg,
 592                   const struct ldb_parse_tree *tree,
 593                   struct ldb_dn *base,
 594                   enum ldb_scope scope)
 595 {
 596         bool matched;
 597         int ret;
 598
 599         if ( ! ldb_match_scope(ldb, base, msg->dn, scope) ) {
 600                 return 0;
 601         }
 602
 603         ret = ldb_match_message(ldb, msg, tree, scope, &matched);
 604         if (ret != LDB_SUCCESS) {
 605                 /* to match the old API, we need to consider this a
 606                    failure to match */
 607                 return 0;
 608         }
 609         return matched?1:0;
 610 }
 611
 612 int ldb_match_msg_error(struct ldb_context *ldb,
 613                         const struct ldb_message *msg,
 614                         const struct ldb_parse_tree *tree,
 615                         struct ldb_dn *base,
 616                         enum ldb_scope scope,
 617                         bool *matched)
 618 {
 619         if ( ! ldb_match_scope(ldb, base, msg->dn, scope) ) {
 620                 *matched = false;
 621                 return LDB_SUCCESS;
 622         }
 623
 624         return ldb_match_message(ldb, msg, tree, scope, matched);
 625 }
 626
 627 int ldb_match_msg_objectclass(const struct ldb_message *msg,
 628                               const char *objectclass)
 629 {
 630         unsigned int i;
 631         struct ldb_message_element *el = ldb_msg_find_element(msg, "objectClass");
 632         if (!el) {
 633                 return 0;
 634         }
 635         for (i=0; i < el->num_values; i++) {
 636                 if (ldb_attr_cmp((const char *)el->values[i].data, objectclass) == 0) {
 637                         return 1;
 638                 }
 639         }
 640         return 0;
 641 }
 642
 643 _PRIVATE_ int ldb_register_extended_match_rules(struct ldb_context *ldb)
 644 {
 645         struct ldb_extended_match_rule *bitmask_and;
 646         struct ldb_extended_match_rule *bitmask_or;
 647         struct ldb_extended_match_rule *always_false;
 648         int ret;
 649
 650         /* Register bitmask-and match */
 651         bitmask_and = talloc_zero(ldb, struct ldb_extended_match_rule);
 652         if (bitmask_and == NULL) {
 653                 return LDB_ERR_OPERATIONS_ERROR;
 654         }
 655
 656         bitmask_and->oid = LDB_OID_COMPARATOR_AND;
 657         bitmask_and->callback = ldb_match_bitmask;
 658
 659         ret = ldb_register_extended_match_rule(ldb, bitmask_and);
 660         if (ret != LDB_SUCCESS) {
 661                 return ret;
 662         }
 663
 664         /* Register bitmask-or match */
 665         bitmask_or = talloc_zero(ldb, struct ldb_extended_match_rule);
 666         if (bitmask_or == NULL) {
 667                 return LDB_ERR_OPERATIONS_ERROR;
 668         }
 669
 670         bitmask_or->oid = LDB_OID_COMPARATOR_OR;
 671         bitmask_or->callback = ldb_match_bitmask;
 672
 673         ret = ldb_register_extended_match_rule(ldb, bitmask_or);
 674         if (ret != LDB_SUCCESS) {
 675                 return ret;
 676         }
 677
 678         /* Register always-false match */
 679         always_false = talloc_zero(ldb, struct ldb_extended_match_rule);
 680         if (always_false == NULL) {
 681                 return LDB_ERR_OPERATIONS_ERROR;
 682         }
 683
 684         always_false->oid = SAMBA_LDAP_MATCH_ALWAYS_FALSE;
 685         always_false->callback = ldb_comparator_false;
 686
 687         ret = ldb_register_extended_match_rule(ldb, always_false);
 688         if (ret != LDB_SUCCESS) {
 689                 return ret;
 690         }
 691
 692         return LDB_SUCCESS;
 693 }
 694
 695 /*
 696   register a new ldb backend
 697
 698   if override is true, then override any existing backend for this prefix
 699 */
 700 int ldb_register_extended_match_rule(struct ldb_context *ldb,
 701                                      const struct ldb_extended_match_rule *rule)
 702 {
 703         const struct ldb_extended_match_rule *lookup_rule;
 704         struct ldb_extended_match_entry *entry;
 705
 706         lookup_rule = ldb_find_extended_match_rule(ldb, rule->oid);
 707         if (lookup_rule) {
 708                 return LDB_ERR_ENTRY_ALREADY_EXISTS;
 709         }
 710
 711         entry = talloc_zero(ldb, struct ldb_extended_match_entry);
 712         if (!entry) {
 713                 return LDB_ERR_OPERATIONS_ERROR;
 714         }
 715         entry->rule = rule;
 716         DLIST_ADD_END(ldb->extended_match_rules, entry);
 717
 718         return LDB_SUCCESS;
 719 }
 720