contrib/bind9/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2014  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id$ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <stdlib.h>
  25
  26 #include <isc/mem.h>
  27 #include <isc/region.h>
  28 #include <isc/string.h>         /* Required for HP/UX (and others?) */
  29 #include <isc/util.h>
  30
  31 #include <dns/result.h>
  32 #include <dns/rdata.h>
  33 #include <dns/rdataset.h>
  34 #include <dns/rdataslab.h>
  35
  36 /*
  37  * The rdataslab structure allows iteration to occur in both load order
  38  * and DNSSEC order.  The structure is as follows:
  39  *
  40  *      header          (reservelen bytes)
  41  *      record count    (2 bytes)
  42  *      offset table    (4 x record count bytes in load order)
  43  *      data records
  44  *              data length     (2 bytes)
  45  *              order           (2 bytes)
  46  *              meta data       (1 byte for RRSIG's)
  47  *              data            (data length bytes)
  48  *
  49  * If DNS_RDATASET_FIXED is defined to be zero (0) the format of a
  50  * rdataslab is as follows:
  51  *
  52  *      header          (reservelen bytes)
  53  *      record count    (2 bytes)
  54  *      data records
  55  *              data length     (2 bytes)
  56  *              meta data       (1 byte for RRSIG's)
  57  *              data            (data length bytes)
  58  *
  59  * Offsets are from the end of the header.
  60  *
  61  * Load order traversal is performed by walking the offset table to find
  62  * the start of the record (DNS_RDATASET_FIXED = 1).
  63  *
  64  * DNSSEC order traversal is performed by walking the data records.
  65  *
  66  * The order is stored with record to allow for efficient reconstruction
  67  * of the offset table following a merge or subtraction.
  68  *
  69  * The iterator methods here currently only support DNSSEC order iteration.
  70  *
  71  * The iterator methods in rbtdb support both load order and DNSSEC order
  72  * iteration.
  73  *
  74  * WARNING:
  75  *      rbtdb.c directly interacts with the slab's raw structures.  If the
  76  *      structure changes then rbtdb.c also needs to be updated to reflect
  77  *      the changes.  See the areas tagged with "RDATASLAB".
  78  */
  79
  80 struct xrdata {
  81         dns_rdata_t     rdata;
  82         unsigned int    order;
  83 };
  84
  85 /*% Note: the "const void *" are just to make qsort happy.  */
  86 static int
  87 compare_rdata(const void *p1, const void *p2) {
  88         const struct xrdata *x1 = p1;
  89         const struct xrdata *x2 = p2;
  90         return (dns_rdata_compare(&x1->rdata, &x2->rdata));
  91 }
  92
  93 #if DNS_RDATASET_FIXED
  94 static void
  95 fillin_offsets(unsigned char *offsetbase, unsigned int *offsettable,
  96                unsigned length)
  97 {
  98         unsigned int i, j;
  99         unsigned char *raw;
 100
 101         for (i = 0, j = 0; i < length; i++) {
 102
 103                 if (offsettable[i] == 0)
 104                         continue;
 105
 106                 /*
 107                  * Fill in offset table.
 108                  */
 109                 raw = &offsetbase[j*4 + 2];
 110                 *raw++ = (offsettable[i] & 0xff000000) >> 24;
 111                 *raw++ = (offsettable[i] & 0xff0000) >> 16;
 112                 *raw++ = (offsettable[i] & 0xff00) >> 8;
 113                 *raw = offsettable[i] & 0xff;
 114
 115                 /*
 116                  * Fill in table index.
 117                  */
 118                 raw = offsetbase + offsettable[i] + 2;
 119                 *raw++ = (j & 0xff00) >> 8;
 120                 *raw = j++ & 0xff;
 121         }
 122 }
 123 #endif
 124
 125 isc_result_t
 126 dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
 127                            isc_region_t *region, unsigned int reservelen)
 128 {
 129         /*
 130          * Use &removed as a sentinal pointer for duplicate
 131          * rdata as rdata.data == NULL is valid.
 132          */
 133         static unsigned char removed;
 134         struct xrdata  *x;
 135         unsigned char  *rawbuf;
 136 #if DNS_RDATASET_FIXED
 137         unsigned char  *offsetbase;
 138 #endif
 139         unsigned int    buflen;
 140         isc_result_t    result;
 141         unsigned int    nitems;
 142         unsigned int    nalloc;
 143         unsigned int    i;
 144 #if DNS_RDATASET_FIXED
 145         unsigned int   *offsettable;
 146 #endif
 147         unsigned int    length;
 148
 149         buflen = reservelen + 2;
 150
 151         nitems = dns_rdataset_count(rdataset);
 152
 153         /*
 154          * If there are no rdata then we can just need to allocate a header
 155          * with zero a record count.
 156          */
 157         if (nitems == 0) {
 158                 if (rdataset->type != 0)
 159                         return (ISC_R_FAILURE);
 160                 rawbuf = isc_mem_get(mctx, buflen);
 161                 if (rawbuf == NULL)
 162                         return (ISC_R_NOMEMORY);
 163                 region->base = rawbuf;
 164                 region->length = buflen;
 165                 rawbuf += reservelen;
 166                 *rawbuf++ = 0;
 167                 *rawbuf = 0;
 168                 return (ISC_R_SUCCESS);
 169         }
 170
 171         if (nitems > 0xffff)
 172                 return (ISC_R_NOSPACE);
 173
 174         /*
 175          * Remember the original number of items.
 176          */
 177         nalloc = nitems;
 178         x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 179         if (x == NULL)
 180                 return (ISC_R_NOMEMORY);
 181
 182         /*
 183          * Save all of the rdata members into an array.
 184          */
 185         result = dns_rdataset_first(rdataset);
 186         if (result != ISC_R_SUCCESS && result != ISC_R_NOMORE)
 187                 goto free_rdatas;
 188         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 189                 INSIST(result == ISC_R_SUCCESS);
 190                 dns_rdata_init(&x[i].rdata);
 191                 dns_rdataset_current(rdataset, &x[i].rdata);
 192                 INSIST(x[i].rdata.data != &removed);
 193 #if DNS_RDATASET_FIXED
 194                 x[i].order = i;
 195 #endif
 196                 result = dns_rdataset_next(rdataset);
 197         }
 198         if (i != nalloc || result != ISC_R_NOMORE) {
 199                 /*
 200                  * Somehow we iterated over fewer rdatas than
 201                  * dns_rdataset_count() said there were or there
 202                  * were more items than dns_rdataset_count said
 203                  * there were.
 204                  */
 205                 result = ISC_R_FAILURE;
 206                 goto free_rdatas;
 207         }
 208
 209         /*
 210          * Put into DNSSEC order.
 211          */
 212         if (nalloc > 1U)
 213                 qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 214
 215         /*
 216          * Remove duplicates and compute the total storage required.
 217          *
 218          * If an rdata is not a duplicate, accumulate the storage size
 219          * required for the rdata.  We do not store the class, type, etc,
 220          * just the rdata, so our overhead is 2 bytes for the number of
 221          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 222          * and then the rdata itself.
 223          */
 224         for (i = 1; i < nalloc; i++) {
 225                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 226                         x[i-1].rdata.data = &removed;
 227 #if DNS_RDATASET_FIXED
 228                         /*
 229                          * Preserve the least order so A, B, A -> A, B
 230                          * after duplicate removal.
 231                          */
 232                         if (x[i-1].order < x[i].order)
 233                                 x[i].order = x[i-1].order;
 234 #endif
 235                         nitems--;
 236                 } else {
 237 #if DNS_RDATASET_FIXED
 238                         buflen += (8 + x[i-1].rdata.length);
 239 #else
 240                         buflen += (2 + x[i-1].rdata.length);
 241 #endif
 242                         /*
 243                          * Provide space to store the per RR meta data.
 244                          */
 245                         if (rdataset->type == dns_rdatatype_rrsig)
 246                                 buflen++;
 247                 }
 248         }
 249
 250         /*
 251          * Don't forget the last item!
 252          */
 253 #if DNS_RDATASET_FIXED
 254         buflen += (8 + x[i-1].rdata.length);
 255 #else
 256         buflen += (2 + x[i-1].rdata.length);
 257 #endif
 258         /*
 259          * Provide space to store the per RR meta data.
 260          */
 261         if (rdataset->type == dns_rdatatype_rrsig)
 262                 buflen++;
 263
 264         /*
 265          * Ensure that singleton types are actually singletons.
 266          */
 267         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 268                 /*
 269                  * We have a singleton type, but there's more than one
 270                  * RR in the rdataset.
 271                  */
 272                 result = DNS_R_SINGLETON;
 273                 goto free_rdatas;
 274         }
 275
 276         /*
 277          * Allocate the memory, set up a buffer, start copying in
 278          * data.
 279          */
 280         rawbuf = isc_mem_get(mctx, buflen);
 281         if (rawbuf == NULL) {
 282                 result = ISC_R_NOMEMORY;
 283                 goto free_rdatas;
 284         }
 285
 286 #if DNS_RDATASET_FIXED
 287         /* Allocate temporary offset table. */
 288         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 289         if (offsettable == NULL) {
 290                 isc_mem_put(mctx, rawbuf, buflen);
 291                 result = ISC_R_NOMEMORY;
 292                 goto free_rdatas;
 293         }
 294         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 295 #endif
 296
 297         region->base = rawbuf;
 298         region->length = buflen;
 299
 300         rawbuf += reservelen;
 301 #if DNS_RDATASET_FIXED
 302         offsetbase = rawbuf;
 303 #endif
 304
 305         *rawbuf++ = (nitems & 0xff00) >> 8;
 306         *rawbuf++ = (nitems & 0x00ff);
 307
 308 #if DNS_RDATASET_FIXED
 309         /* Skip load order table.  Filled in later. */
 310         rawbuf += nitems * 4;
 311 #endif
 312
 313         for (i = 0; i < nalloc; i++) {
 314                 if (x[i].rdata.data == &removed)
 315                         continue;
 316 #if DNS_RDATASET_FIXED
 317                 offsettable[x[i].order] = rawbuf - offsetbase;
 318 #endif
 319                 length = x[i].rdata.length;
 320                 if (rdataset->type == dns_rdatatype_rrsig)
 321                         length++;
 322                 INSIST(length <= 0xffff);
 323                 *rawbuf++ = (length & 0xff00) >> 8;
 324                 *rawbuf++ = (length & 0x00ff);
 325 #if DNS_RDATASET_FIXED
 326                 rawbuf += 2;    /* filled in later */
 327 #endif
 328                 /*
 329                  * Store the per RR meta data.
 330                  */
 331                 if (rdataset->type == dns_rdatatype_rrsig) {
 332                         *rawbuf++ |= (x[i].rdata.flags & DNS_RDATA_OFFLINE) ?
 333                                             DNS_RDATASLAB_OFFLINE : 0;
 334                 }
 335                 memmove(rawbuf, x[i].rdata.data, x[i].rdata.length);
 336                 rawbuf += x[i].rdata.length;
 337         }
 338
 339 #if DNS_RDATASET_FIXED
 340         fillin_offsets(offsetbase, offsettable, nalloc);
 341         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 342 #endif
 343
 344         result = ISC_R_SUCCESS;
 345
 346  free_rdatas:
 347         isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 348         return (result);
 349 }
 350
 351 static void
 352 rdataset_disassociate(dns_rdataset_t *rdataset) {
 353         UNUSED(rdataset);
 354 }
 355
 356 static isc_result_t
 357 rdataset_first(dns_rdataset_t *rdataset) {
 358         unsigned char *raw = rdataset->private3;
 359         unsigned int count;
 360
 361         count = raw[0] * 256 + raw[1];
 362         if (count == 0) {
 363                 rdataset->private5 = NULL;
 364                 return (ISC_R_NOMORE);
 365         }
 366 #if DNS_RDATASET_FIXED
 367         raw += 2 + (4 * count);
 368 #else
 369         raw += 2;
 370 #endif
 371         /*
 372          * The privateuint4 field is the number of rdata beyond the cursor
 373          * position, so we decrement the total count by one before storing
 374          * it.
 375          */
 376         count--;
 377         rdataset->privateuint4 = count;
 378         rdataset->private5 = raw;
 379
 380         return (ISC_R_SUCCESS);
 381 }
 382
 383 static isc_result_t
 384 rdataset_next(dns_rdataset_t *rdataset) {
 385         unsigned int count;
 386         unsigned int length;
 387         unsigned char *raw;
 388
 389         count = rdataset->privateuint4;
 390         if (count == 0)
 391                 return (ISC_R_NOMORE);
 392         count--;
 393         rdataset->privateuint4 = count;
 394         raw = rdataset->private5;
 395         length = raw[0] * 256 + raw[1];
 396 #if DNS_RDATASET_FIXED
 397         raw += length + 4;
 398 #else
 399         raw += length + 2;
 400 #endif
 401         rdataset->private5 = raw;
 402
 403         return (ISC_R_SUCCESS);
 404 }
 405
 406 static void
 407 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 408         unsigned char *raw = rdataset->private5;
 409         isc_region_t r;
 410         unsigned int length;
 411         unsigned int flags = 0;
 412
 413         REQUIRE(raw != NULL);
 414
 415         length = raw[0] * 256 + raw[1];
 416 #if DNS_RDATASET_FIXED
 417         raw += 4;
 418 #else
 419         raw += 2;
 420 #endif
 421         if (rdataset->type == dns_rdatatype_rrsig) {
 422                 if (*raw & DNS_RDATASLAB_OFFLINE)
 423                         flags |= DNS_RDATA_OFFLINE;
 424                 length--;
 425                 raw++;
 426         }
 427         r.length = length;
 428         r.base = raw;
 429         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 430         rdata->flags |= flags;
 431 }
 432
 433 static void
 434 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 435         *target = *source;
 436
 437         /*
 438          * Reset iterator state.
 439          */
 440         target->privateuint4 = 0;
 441         target->private5 = NULL;
 442 }
 443
 444 static unsigned int
 445 rdataset_count(dns_rdataset_t *rdataset) {
 446         unsigned char *raw = rdataset->private3;
 447         unsigned int count;
 448
 449         count = raw[0] * 256 + raw[1];
 450
 451         return (count);
 452 }
 453
 454 static dns_rdatasetmethods_t rdataset_methods = {
 455         rdataset_disassociate,
 456         rdataset_first,
 457         rdataset_next,
 458         rdataset_current,
 459         rdataset_clone,
 460         rdataset_count,
 461         NULL,
 462         NULL,
 463         NULL,
 464         NULL,
 465         NULL,
 466         NULL,
 467         NULL,
 468         NULL,
 469         NULL
 470 };
 471
 472 void
 473 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 474                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 475                          dns_rdatatype_t covers, dns_ttl_t ttl,
 476                          dns_rdataset_t *rdataset)
 477 {
 478         REQUIRE(slab != NULL);
 479         REQUIRE(!dns_rdataset_isassociated(rdataset));
 480
 481         rdataset->methods = &rdataset_methods;
 482         rdataset->rdclass = rdclass;
 483         rdataset->type = rdtype;
 484         rdataset->covers = covers;
 485         rdataset->ttl = ttl;
 486         rdataset->trust = 0;
 487         rdataset->private1 = NULL;
 488         rdataset->private2 = NULL;
 489         rdataset->private3 = slab + reservelen;
 490
 491         /*
 492          * Reset iterator state.
 493          */
 494         rdataset->privateuint4 = 0;
 495         rdataset->private5 = NULL;
 496 }
 497
 498 unsigned int
 499 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 500         unsigned int count, length;
 501         unsigned char *current;
 502
 503         REQUIRE(slab != NULL);
 504
 505         current = slab + reservelen;
 506         count = *current++ * 256;
 507         count += *current++;
 508 #if DNS_RDATASET_FIXED
 509         current += (4 * count);
 510 #endif
 511         while (count > 0) {
 512                 count--;
 513                 length = *current++ * 256;
 514                 length += *current++;
 515 #if DNS_RDATASET_FIXED
 516                 current += length + 2;
 517 #else
 518                 current += length;
 519 #endif
 520         }
 521
 522         return ((unsigned int)(current - slab));
 523 }
 524
 525 /*
 526  * Make the dns_rdata_t 'rdata' refer to the slab item
 527  * beginning at '*current', which is part of a slab of type
 528  * 'type' and class 'rdclass', and advance '*current' to
 529  * point to the next item in the slab.
 530  */
 531 static inline void
 532 rdata_from_slab(unsigned char **current,
 533               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 534               dns_rdata_t *rdata)
 535 {
 536         unsigned char *tcurrent = *current;
 537         isc_region_t region;
 538         unsigned int length;
 539         isc_boolean_t offline = ISC_FALSE;
 540
 541         length = *tcurrent++ * 256;
 542         length += *tcurrent++;
 543
 544         if (type == dns_rdatatype_rrsig) {
 545                 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0)
 546                         offline = ISC_TRUE;
 547                 length--;
 548                 tcurrent++;
 549         }
 550         region.length = length;
 551 #if DNS_RDATASET_FIXED
 552         tcurrent += 2;
 553 #endif
 554         region.base = tcurrent;
 555         tcurrent += region.length;
 556         dns_rdata_fromregion(rdata, rdclass, type, &region);
 557         if (offline)
 558                 rdata->flags |= DNS_RDATA_OFFLINE;
 559         *current = tcurrent;
 560 }
 561
 562 /*
 563  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 564  * contains an rdata identical to 'rdata'.  This does case insensitive
 565  * comparisons per DNSSEC.
 566  */
 567 static inline isc_boolean_t
 568 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 569               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 570               dns_rdata_t *rdata)
 571 {
 572         unsigned int count, i;
 573         unsigned char *current;
 574         dns_rdata_t trdata = DNS_RDATA_INIT;
 575         int n;
 576
 577         current = slab + reservelen;
 578         count = *current++ * 256;
 579         count += *current++;
 580
 581 #if DNS_RDATASET_FIXED
 582         current += (4 * count);
 583 #endif
 584
 585         for (i = 0; i < count; i++) {
 586                 rdata_from_slab(&current, rdclass, type, &trdata);
 587
 588                 n = dns_rdata_compare(&trdata, rdata);
 589                 if (n == 0)
 590                         return (ISC_TRUE);
 591                 if (n > 0)      /* In DNSSEC order. */
 592                         break;
 593                 dns_rdata_reset(&trdata);
 594         }
 595         return (ISC_FALSE);
 596 }
 597
 598 isc_result_t
 599 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 600                     unsigned int reservelen, isc_mem_t *mctx,
 601                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 602                     unsigned int flags, unsigned char **tslabp)
 603 {
 604         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
 605         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 606         dns_rdata_t ordata = DNS_RDATA_INIT;
 607         dns_rdata_t nrdata = DNS_RDATA_INIT;
 608         isc_boolean_t added_something = ISC_FALSE;
 609         unsigned int oadded = 0;
 610         unsigned int nadded = 0;
 611         unsigned int nncount = 0;
 612 #if DNS_RDATASET_FIXED
 613         unsigned int oncount;
 614         unsigned int norder = 0;
 615         unsigned int oorder = 0;
 616         unsigned char *offsetbase;
 617         unsigned int *offsettable;
 618 #endif
 619
 620         /*
 621          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 622          * or perhaps another merge routine for this purpose.
 623          */
 624
 625         REQUIRE(tslabp != NULL && *tslabp == NULL);
 626         REQUIRE(oslab != NULL && nslab != NULL);
 627
 628         ocurrent = oslab + reservelen;
 629         ocount = *ocurrent++ * 256;
 630         ocount += *ocurrent++;
 631 #if DNS_RDATASET_FIXED
 632         ocurrent += (4 * ocount);
 633 #endif
 634         ostart = ocurrent;
 635         ncurrent = nslab + reservelen;
 636         ncount = *ncurrent++ * 256;
 637         ncount += *ncurrent++;
 638 #if DNS_RDATASET_FIXED
 639         ncurrent += (4 * ncount);
 640 #endif
 641         INSIST(ocount > 0 && ncount > 0);
 642
 643 #if DNS_RDATASET_FIXED
 644         oncount = ncount;
 645 #endif
 646
 647         /*
 648          * Yes, this is inefficient!
 649          */
 650
 651         /*
 652          * Figure out the length of the old slab's data.
 653          */
 654         olength = 0;
 655         for (count = 0; count < ocount; count++) {
 656                 length = *ocurrent++ * 256;
 657                 length += *ocurrent++;
 658 #if DNS_RDATASET_FIXED
 659                 olength += length + 8;
 660                 ocurrent += length + 2;
 661 #else
 662                 olength += length + 2;
 663                 ocurrent += length;
 664 #endif
 665         }
 666
 667         /*
 668          * Start figuring out the target length and count.
 669          */
 670         tlength = reservelen + 2 + olength;
 671         tcount = ocount;
 672
 673         /*
 674          * Add in the length of rdata in the new slab that aren't in
 675          * the old slab.
 676          */
 677         do {
 678                 dns_rdata_init(&nrdata);
 679                 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 680                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 681                 {
 682                         /*
 683                          * This rdata isn't in the old slab.
 684                          */
 685 #if DNS_RDATASET_FIXED
 686                         tlength += nrdata.length + 8;
 687 #else
 688                         tlength += nrdata.length + 2;
 689 #endif
 690                         if (type == dns_rdatatype_rrsig)
 691                                 tlength++;
 692                         tcount++;
 693                         nncount++;
 694                         added_something = ISC_TRUE;
 695                 }
 696                 ncount--;
 697         } while (ncount > 0);
 698         ncount = nncount;
 699
 700         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 701             (tcount != ncount + ocount))
 702                 return (DNS_R_NOTEXACT);
 703
 704         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 705                 return (DNS_R_UNCHANGED);
 706
 707         /*
 708          * Ensure that singleton types are actually singletons.
 709          */
 710         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 711                 /*
 712                  * We have a singleton type, but there's more than one
 713                  * RR in the rdataset.
 714                  */
 715                 return (DNS_R_SINGLETON);
 716         }
 717
 718         if (tcount > 0xffff)
 719                 return (ISC_R_NOSPACE);
 720
 721         /*
 722          * Copy the reserved area from the new slab.
 723          */
 724         tstart = isc_mem_get(mctx, tlength);
 725         if (tstart == NULL)
 726                 return (ISC_R_NOMEMORY);
 727         memmove(tstart, nslab, reservelen);
 728         tcurrent = tstart + reservelen;
 729 #if DNS_RDATASET_FIXED
 730         offsetbase = tcurrent;
 731 #endif
 732
 733         /*
 734          * Write the new count.
 735          */
 736         *tcurrent++ = (tcount & 0xff00) >> 8;
 737         *tcurrent++ = (tcount & 0x00ff);
 738
 739 #if DNS_RDATASET_FIXED
 740         /*
 741          * Skip offset table.
 742          */
 743         tcurrent += (tcount * 4);
 744
 745         offsettable = isc_mem_get(mctx,
 746                                   (ocount + oncount) * sizeof(unsigned int));
 747         if (offsettable == NULL) {
 748                 isc_mem_put(mctx, tstart, tlength);
 749                 return (ISC_R_NOMEMORY);
 750         }
 751         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 752 #endif
 753
 754         /*
 755          * Merge the two slabs.
 756          */
 757         ocurrent = ostart;
 758         INSIST(ocount != 0);
 759 #if DNS_RDATASET_FIXED
 760         oorder = ocurrent[2] * 256 + ocurrent[3];
 761         INSIST(oorder < ocount);
 762 #endif
 763         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 764
 765         ncurrent = nslab + reservelen + 2;
 766 #if DNS_RDATASET_FIXED
 767         ncurrent += (4 * oncount);
 768 #endif
 769
 770         if (ncount > 0) {
 771                 do {
 772                         dns_rdata_reset(&nrdata);
 773 #if DNS_RDATASET_FIXED
 774                         norder = ncurrent[2] * 256 + ncurrent[3];
 775
 776                         INSIST(norder < oncount);
 777 #endif
 778                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 779                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 780                                        type, &nrdata));
 781         }
 782
 783         while (oadded < ocount || nadded < ncount) {
 784                 isc_boolean_t fromold;
 785                 if (oadded == ocount)
 786                         fromold = ISC_FALSE;
 787                 else if (nadded == ncount)
 788                         fromold = ISC_TRUE;
 789                 else
 790                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 791                 if (fromold) {
 792 #if DNS_RDATASET_FIXED
 793                         offsettable[oorder] = tcurrent - offsetbase;
 794 #endif
 795                         length = ordata.length;
 796                         data = ordata.data;
 797                         if (type == dns_rdatatype_rrsig) {
 798                                 length++;
 799                                 data--;
 800                         }
 801                         *tcurrent++ = (length & 0xff00) >> 8;
 802                         *tcurrent++ = (length & 0x00ff);
 803 #if DNS_RDATASET_FIXED
 804                         tcurrent += 2;  /* fill in later */
 805 #endif
 806                         memmove(tcurrent, data, length);
 807                         tcurrent += length;
 808                         oadded++;
 809                         if (oadded < ocount) {
 810                                 dns_rdata_reset(&ordata);
 811 #if DNS_RDATASET_FIXED
 812                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 813                                 INSIST(oorder < ocount);
 814 #endif
 815                                 rdata_from_slab(&ocurrent, rdclass, type,
 816                                                 &ordata);
 817                         }
 818                 } else {
 819 #if DNS_RDATASET_FIXED
 820                         offsettable[ocount + norder] = tcurrent - offsetbase;
 821 #endif
 822                         length = nrdata.length;
 823                         data = nrdata.data;
 824                         if (type == dns_rdatatype_rrsig) {
 825                                 length++;
 826                                 data--;
 827                         }
 828                         *tcurrent++ = (length & 0xff00) >> 8;
 829                         *tcurrent++ = (length & 0x00ff);
 830 #if DNS_RDATASET_FIXED
 831                         tcurrent += 2;  /* fill in later */
 832 #endif
 833                         memmove(tcurrent, data, length);
 834                         tcurrent += length;
 835                         nadded++;
 836                         if (nadded < ncount) {
 837                                 do {
 838                                         dns_rdata_reset(&nrdata);
 839 #if DNS_RDATASET_FIXED
 840                                         norder = ncurrent[2] * 256 + ncurrent[3];
 841                                         INSIST(norder < oncount);
 842 #endif
 843                                         rdata_from_slab(&ncurrent, rdclass,
 844                                                         type, &nrdata);
 845                                 } while (rdata_in_slab(oslab, reservelen,
 846                                                        rdclass, type,
 847                                                        &nrdata));
 848                         }
 849                 }
 850         }
 851
 852 #if DNS_RDATASET_FIXED
 853         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 854
 855         isc_mem_put(mctx, offsettable,
 856                     (ocount + oncount) * sizeof(unsigned int));
 857 #endif
 858
 859         INSIST(tcurrent == tstart + tlength);
 860
 861         *tslabp = tstart;
 862
 863         return (ISC_R_SUCCESS);
 864 }
 865
 866 isc_result_t
 867 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 868                        unsigned int reservelen, isc_mem_t *mctx,
 869                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 870                        unsigned int flags, unsigned char **tslabp)
 871 {
 872         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 873         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 874         dns_rdata_t srdata = DNS_RDATA_INIT;
 875         dns_rdata_t mrdata = DNS_RDATA_INIT;
 876 #if DNS_RDATASET_FIXED
 877         unsigned char *offsetbase;
 878         unsigned int *offsettable;
 879         unsigned int order;
 880 #endif
 881
 882         REQUIRE(tslabp != NULL && *tslabp == NULL);
 883         REQUIRE(mslab != NULL && sslab != NULL);
 884
 885         mcurrent = mslab + reservelen;
 886         mcount = *mcurrent++ * 256;
 887         mcount += *mcurrent++;
 888         scurrent = sslab + reservelen;
 889         scount = *scurrent++ * 256;
 890         scount += *scurrent++;
 891         INSIST(mcount > 0 && scount > 0);
 892
 893         /*
 894          * Yes, this is inefficient!
 895          */
 896
 897         /*
 898          * Start figuring out the target length and count.
 899          */
 900         tlength = reservelen + 2;
 901         tcount = 0;
 902         rcount = 0;
 903
 904 #if DNS_RDATASET_FIXED
 905         mcurrent += 4 * mcount;
 906         scurrent += 4 * scount;
 907 #endif
 908         sstart = scurrent;
 909
 910         /*
 911          * Add in the length of rdata in the mslab that aren't in
 912          * the sslab.
 913          */
 914         for (i = 0; i < mcount; i++) {
 915                 unsigned char *mrdatabegin = mcurrent;
 916                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 917                 scurrent = sstart;
 918                 for (count = 0; count < scount; count++) {
 919                         dns_rdata_reset(&srdata);
 920                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 921                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 922                                 break;
 923                 }
 924                 if (count == scount) {
 925                         /*
 926                          * This rdata isn't in the sslab, and thus isn't
 927                          * being subtracted.
 928                          */
 929                         tlength += (unsigned int)(mcurrent - mrdatabegin);
 930                         tcount++;
 931                 } else
 932                         rcount++;
 933                 dns_rdata_reset(&mrdata);
 934         }
 935
 936 #if DNS_RDATASET_FIXED
 937         tlength += (4 * tcount);
 938 #endif
 939
 940         /*
 941          * Check that all the records originally existed.  The numeric
 942          * check only works as rdataslabs do not contain duplicates.
 943          */
 944         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 945                 return (DNS_R_NOTEXACT);
 946
 947         /*
 948          * Don't continue if the new rdataslab would be empty.
 949          */
 950         if (tcount == 0)
 951                 return (DNS_R_NXRRSET);
 952
 953         /*
 954          * If nothing is going to change, we can stop.
 955          */
 956         if (rcount == 0)
 957                 return (DNS_R_UNCHANGED);
 958
 959         /*
 960          * Copy the reserved area from the mslab.
 961          */
 962         tstart = isc_mem_get(mctx, tlength);
 963         if (tstart == NULL)
 964                 return (ISC_R_NOMEMORY);
 965         memmove(tstart, mslab, reservelen);
 966         tcurrent = tstart + reservelen;
 967 #if DNS_RDATASET_FIXED
 968         offsetbase = tcurrent;
 969
 970         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 971         if (offsettable == NULL) {
 972                 isc_mem_put(mctx, tstart, tlength);
 973                 return (ISC_R_NOMEMORY);
 974         }
 975         memset(offsettable, 0, mcount * sizeof(unsigned int));
 976 #endif
 977
 978         /*
 979          * Write the new count.
 980          */
 981         *tcurrent++ = (tcount & 0xff00) >> 8;
 982         *tcurrent++ = (tcount & 0x00ff);
 983
 984 #if DNS_RDATASET_FIXED
 985         tcurrent += (4 * tcount);
 986 #endif
 987
 988         /*
 989          * Copy the parts of mslab not in sslab.
 990          */
 991         mcurrent = mslab + reservelen;
 992         mcount = *mcurrent++ * 256;
 993         mcount += *mcurrent++;
 994 #if DNS_RDATASET_FIXED
 995         mcurrent += (4 * mcount);
 996 #endif
 997         for (i = 0; i < mcount; i++) {
 998                 unsigned char *mrdatabegin = mcurrent;
 999 #if DNS_RDATASET_FIXED
1000                 order = mcurrent[2] * 256 + mcurrent[3];
1001                 INSIST(order < mcount);
1002 #endif
1003                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
1004                 scurrent = sstart;
1005                 for (count = 0; count < scount; count++) {
1006                         dns_rdata_reset(&srdata);
1007                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
1008                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
1009                                 break;
1010                 }
1011                 if (count == scount) {
1012                         /*
1013                          * This rdata isn't in the sslab, and thus should be
1014                          * copied to the tslab.
1015                          */
1016                         unsigned int length;
1017                         length = (unsigned int)(mcurrent - mrdatabegin);
1018 #if DNS_RDATASET_FIXED
1019                         offsettable[order] = tcurrent - offsetbase;
1020 #endif
1021                         memmove(tcurrent, mrdatabegin, length);
1022                         tcurrent += length;
1023                 }
1024                 dns_rdata_reset(&mrdata);
1025         }
1026
1027 #if DNS_RDATASET_FIXED
1028         fillin_offsets(offsetbase, offsettable, mcount);
1029
1030         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
1031 #endif
1032
1033         INSIST(tcurrent == tstart + tlength);
1034
1035         *tslabp = tstart;
1036
1037         return (ISC_R_SUCCESS);
1038 }
1039
1040 isc_boolean_t
1041 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
1042                     unsigned int reservelen)
1043 {
1044         unsigned char *current1, *current2;
1045         unsigned int count1, count2;
1046         unsigned int length1, length2;
1047
1048         current1 = slab1 + reservelen;
1049         count1 = *current1++ * 256;
1050         count1 += *current1++;
1051
1052         current2 = slab2 + reservelen;
1053         count2 = *current2++ * 256;
1054         count2 += *current2++;
1055
1056         if (count1 != count2)
1057                 return (ISC_FALSE);
1058
1059 #if DNS_RDATASET_FIXED
1060         current1 += (4 * count1);
1061         current2 += (4 * count2);
1062 #endif
1063
1064         while (count1 > 0) {
1065                 length1 = *current1++ * 256;
1066                 length1 += *current1++;
1067
1068                 length2 = *current2++ * 256;
1069                 length2 += *current2++;
1070
1071 #if DNS_RDATASET_FIXED
1072                 current1 += 2;
1073                 current2 += 2;
1074 #endif
1075
1076                 if (length1 != length2 ||
1077                     memcmp(current1, current2, length1) != 0)
1078                         return (ISC_FALSE);
1079
1080                 current1 += length1;
1081                 current2 += length1;
1082
1083                 count1--;
1084         }
1085         return (ISC_TRUE);
1086 }
1087
1088 isc_boolean_t
1089 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1090                      unsigned int reservelen, dns_rdataclass_t rdclass,
1091                      dns_rdatatype_t type)
1092 {
1093         unsigned char *current1, *current2;
1094         unsigned int count1, count2;
1095         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1096         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1097
1098         current1 = slab1 + reservelen;
1099         count1 = *current1++ * 256;
1100         count1 += *current1++;
1101
1102         current2 = slab2 + reservelen;
1103         count2 = *current2++ * 256;
1104         count2 += *current2++;
1105
1106         if (count1 != count2)
1107                 return (ISC_FALSE);
1108
1109 #if DNS_RDATASET_FIXED
1110         current1 += (4 * count1);
1111         current2 += (4 * count2);
1112 #endif
1113
1114         while (count1-- > 0) {
1115                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1116                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1117                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1118                         return (ISC_FALSE);
1119                 dns_rdata_reset(&rdata1);
1120                 dns_rdata_reset(&rdata2);
1121         }
1122         return (ISC_TRUE);
1123 }