contrib/bind9/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2012  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         nalloc = dns_rdataset_count(rdataset);
 152         nitems = nalloc;
 153         if (nitems == 0)
 154                 return (ISC_R_FAILURE);
 155
 156         if (nalloc > 0xffff)
 157                 return (ISC_R_NOSPACE);
 158
 159         x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 160         if (x == NULL)
 161                 return (ISC_R_NOMEMORY);
 162
 163         /*
 164          * Save all of the rdata members into an array.
 165          */
 166         result = dns_rdataset_first(rdataset);
 167         if (result != ISC_R_SUCCESS)
 168                 goto free_rdatas;
 169         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 170                 INSIST(result == ISC_R_SUCCESS);
 171                 dns_rdata_init(&x[i].rdata);
 172                 dns_rdataset_current(rdataset, &x[i].rdata);
 173                 INSIST(x[i].rdata.data != &removed);
 174 #if DNS_RDATASET_FIXED
 175                 x[i].order = i;
 176 #endif
 177                 result = dns_rdataset_next(rdataset);
 178         }
 179         if (result != ISC_R_NOMORE)
 180                 goto free_rdatas;
 181         if (i != nalloc) {
 182                 /*
 183                  * Somehow we iterated over fewer rdatas than
 184                  * dns_rdataset_count() said there were!
 185                  */
 186                 result = ISC_R_FAILURE;
 187                 goto free_rdatas;
 188         }
 189
 190         /*
 191          * Put into DNSSEC order.
 192          */
 193         qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 194
 195         /*
 196          * Remove duplicates and compute the total storage required.
 197          *
 198          * If an rdata is not a duplicate, accumulate the storage size
 199          * required for the rdata.  We do not store the class, type, etc,
 200          * just the rdata, so our overhead is 2 bytes for the number of
 201          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 202          * and then the rdata itself.
 203          */
 204         for (i = 1; i < nalloc; i++) {
 205                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 206                         x[i-1].rdata.data = &removed;
 207 #if DNS_RDATASET_FIXED
 208                         /*
 209                          * Preserve the least order so A, B, A -> A, B
 210                          * after duplicate removal.
 211                          */
 212                         if (x[i-1].order < x[i].order)
 213                                 x[i].order = x[i-1].order;
 214 #endif
 215                         nitems--;
 216                 } else {
 217 #if DNS_RDATASET_FIXED
 218                         buflen += (8 + x[i-1].rdata.length);
 219 #else
 220                         buflen += (2 + x[i-1].rdata.length);
 221 #endif
 222                         /*
 223                          * Provide space to store the per RR meta data.
 224                          */
 225                         if (rdataset->type == dns_rdatatype_rrsig)
 226                                 buflen++;
 227                 }
 228         }
 229         /*
 230          * Don't forget the last item!
 231          */
 232 #if DNS_RDATASET_FIXED
 233         buflen += (8 + x[i-1].rdata.length);
 234 #else
 235         buflen += (2 + x[i-1].rdata.length);
 236 #endif
 237         /*
 238          * Provide space to store the per RR meta data.
 239          */
 240         if (rdataset->type == dns_rdatatype_rrsig)
 241                 buflen++;
 242
 243         /*
 244          * Ensure that singleton types are actually singletons.
 245          */
 246         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 247                 /*
 248                  * We have a singleton type, but there's more than one
 249                  * RR in the rdataset.
 250                  */
 251                 result = DNS_R_SINGLETON;
 252                 goto free_rdatas;
 253         }
 254
 255         /*
 256          * Allocate the memory, set up a buffer, start copying in
 257          * data.
 258          */
 259         rawbuf = isc_mem_get(mctx, buflen);
 260         if (rawbuf == NULL) {
 261                 result = ISC_R_NOMEMORY;
 262                 goto free_rdatas;
 263         }
 264
 265 #if DNS_RDATASET_FIXED
 266         /* Allocate temporary offset table. */
 267         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 268         if (offsettable == NULL) {
 269                 isc_mem_put(mctx, rawbuf, buflen);
 270                 result = ISC_R_NOMEMORY;
 271                 goto free_rdatas;
 272         }
 273         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 274 #endif
 275
 276         region->base = rawbuf;
 277         region->length = buflen;
 278
 279         rawbuf += reservelen;
 280 #if DNS_RDATASET_FIXED
 281         offsetbase = rawbuf;
 282 #endif
 283
 284         *rawbuf++ = (nitems & 0xff00) >> 8;
 285         *rawbuf++ = (nitems & 0x00ff);
 286
 287 #if DNS_RDATASET_FIXED
 288         /* Skip load order table.  Filled in later. */
 289         rawbuf += nitems * 4;
 290 #endif
 291
 292         for (i = 0; i < nalloc; i++) {
 293                 if (x[i].rdata.data == &removed)
 294                         continue;
 295 #if DNS_RDATASET_FIXED
 296                 offsettable[x[i].order] = rawbuf - offsetbase;
 297 #endif
 298                 length = x[i].rdata.length;
 299                 if (rdataset->type == dns_rdatatype_rrsig)
 300                         length++;
 301                 INSIST(length <= 0xffff);
 302                 *rawbuf++ = (length & 0xff00) >> 8;
 303                 *rawbuf++ = (length & 0x00ff);
 304 #if DNS_RDATASET_FIXED
 305                 rawbuf += 2;    /* filled in later */
 306 #endif
 307                 /*
 308                  * Store the per RR meta data.
 309                  */
 310                 if (rdataset->type == dns_rdatatype_rrsig) {
 311                         *rawbuf++ |= (x[i].rdata.flags & DNS_RDATA_OFFLINE) ?
 312                                             DNS_RDATASLAB_OFFLINE : 0;
 313                 }
 314                 memcpy(rawbuf, x[i].rdata.data, x[i].rdata.length);
 315                 rawbuf += x[i].rdata.length;
 316         }
 317
 318 #if DNS_RDATASET_FIXED
 319         fillin_offsets(offsetbase, offsettable, nalloc);
 320         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 321 #endif
 322
 323         result = ISC_R_SUCCESS;
 324
 325  free_rdatas:
 326         isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 327         return (result);
 328 }
 329
 330 static void
 331 rdataset_disassociate(dns_rdataset_t *rdataset) {
 332         UNUSED(rdataset);
 333 }
 334
 335 static isc_result_t
 336 rdataset_first(dns_rdataset_t *rdataset) {
 337         unsigned char *raw = rdataset->private3;
 338         unsigned int count;
 339
 340         count = raw[0] * 256 + raw[1];
 341         if (count == 0) {
 342                 rdataset->private5 = NULL;
 343                 return (ISC_R_NOMORE);
 344         }
 345 #if DNS_RDATASET_FIXED
 346         raw += 2 + (4 * count);
 347 #else
 348         raw += 2;
 349 #endif
 350         /*
 351          * The privateuint4 field is the number of rdata beyond the cursor
 352          * position, so we decrement the total count by one before storing
 353          * it.
 354          */
 355         count--;
 356         rdataset->privateuint4 = count;
 357         rdataset->private5 = raw;
 358
 359         return (ISC_R_SUCCESS);
 360 }
 361
 362 static isc_result_t
 363 rdataset_next(dns_rdataset_t *rdataset) {
 364         unsigned int count;
 365         unsigned int length;
 366         unsigned char *raw;
 367
 368         count = rdataset->privateuint4;
 369         if (count == 0)
 370                 return (ISC_R_NOMORE);
 371         count--;
 372         rdataset->privateuint4 = count;
 373         raw = rdataset->private5;
 374         length = raw[0] * 256 + raw[1];
 375 #if DNS_RDATASET_FIXED
 376         raw += length + 4;
 377 #else
 378         raw += length + 2;
 379 #endif
 380         rdataset->private5 = raw;
 381
 382         return (ISC_R_SUCCESS);
 383 }
 384
 385 static void
 386 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 387         unsigned char *raw = rdataset->private5;
 388         isc_region_t r;
 389         unsigned int length;
 390         unsigned int flags = 0;
 391
 392         REQUIRE(raw != NULL);
 393
 394         length = raw[0] * 256 + raw[1];
 395 #if DNS_RDATASET_FIXED
 396         raw += 4;
 397 #else
 398         raw += 2;
 399 #endif
 400         if (rdataset->type == dns_rdatatype_rrsig) {
 401                 if (*raw & DNS_RDATASLAB_OFFLINE)
 402                         flags |= DNS_RDATA_OFFLINE;
 403                 length--;
 404                 raw++;
 405         }
 406         r.length = length;
 407         r.base = raw;
 408         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 409         rdata->flags |= flags;
 410 }
 411
 412 static void
 413 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 414         *target = *source;
 415
 416         /*
 417          * Reset iterator state.
 418          */
 419         target->privateuint4 = 0;
 420         target->private5 = NULL;
 421 }
 422
 423 static unsigned int
 424 rdataset_count(dns_rdataset_t *rdataset) {
 425         unsigned char *raw = rdataset->private3;
 426         unsigned int count;
 427
 428         count = raw[0] * 256 + raw[1];
 429
 430         return (count);
 431 }
 432
 433 static dns_rdatasetmethods_t rdataset_methods = {
 434         rdataset_disassociate,
 435         rdataset_first,
 436         rdataset_next,
 437         rdataset_current,
 438         rdataset_clone,
 439         rdataset_count,
 440         NULL,
 441         NULL,
 442         NULL,
 443         NULL,
 444         NULL,
 445         NULL,
 446         NULL,
 447         NULL,
 448         NULL
 449 };
 450
 451 void
 452 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 453                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 454                          dns_rdatatype_t covers, dns_ttl_t ttl,
 455                          dns_rdataset_t *rdataset)
 456 {
 457         REQUIRE(slab != NULL);
 458         REQUIRE(!dns_rdataset_isassociated(rdataset));
 459
 460         rdataset->methods = &rdataset_methods;
 461         rdataset->rdclass = rdclass;
 462         rdataset->type = rdtype;
 463         rdataset->covers = covers;
 464         rdataset->ttl = ttl;
 465         rdataset->trust = 0;
 466         rdataset->private1 = NULL;
 467         rdataset->private2 = NULL;
 468         rdataset->private3 = slab + reservelen;
 469
 470         /*
 471          * Reset iterator state.
 472          */
 473         rdataset->privateuint4 = 0;
 474         rdataset->private5 = NULL;
 475 }
 476
 477 unsigned int
 478 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 479         unsigned int count, length;
 480         unsigned char *current;
 481
 482         REQUIRE(slab != NULL);
 483
 484         current = slab + reservelen;
 485         count = *current++ * 256;
 486         count += *current++;
 487 #if DNS_RDATASET_FIXED
 488         current += (4 * count);
 489 #endif
 490         while (count > 0) {
 491                 count--;
 492                 length = *current++ * 256;
 493                 length += *current++;
 494 #if DNS_RDATASET_FIXED
 495                 current += length + 2;
 496 #else
 497                 current += length;
 498 #endif
 499         }
 500
 501         return ((unsigned int)(current - slab));
 502 }
 503
 504 /*
 505  * Make the dns_rdata_t 'rdata' refer to the slab item
 506  * beginning at '*current', which is part of a slab of type
 507  * 'type' and class 'rdclass', and advance '*current' to
 508  * point to the next item in the slab.
 509  */
 510 static inline void
 511 rdata_from_slab(unsigned char **current,
 512               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 513               dns_rdata_t *rdata)
 514 {
 515         unsigned char *tcurrent = *current;
 516         isc_region_t region;
 517         unsigned int length;
 518         isc_boolean_t offline = ISC_FALSE;
 519
 520         length = *tcurrent++ * 256;
 521         length += *tcurrent++;
 522
 523         if (type == dns_rdatatype_rrsig) {
 524                 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0)
 525                         offline = ISC_TRUE;
 526                 length--;
 527                 tcurrent++;
 528         }
 529         region.length = length;
 530 #if DNS_RDATASET_FIXED
 531         tcurrent += 2;
 532 #endif
 533         region.base = tcurrent;
 534         tcurrent += region.length;
 535         dns_rdata_fromregion(rdata, rdclass, type, &region);
 536         if (offline)
 537                 rdata->flags |= DNS_RDATA_OFFLINE;
 538         *current = tcurrent;
 539 }
 540
 541 /*
 542  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 543  * contains an rdata identical to 'rdata'.  This does case insensitive
 544  * comparisons per DNSSEC.
 545  */
 546 static inline isc_boolean_t
 547 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 548               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 549               dns_rdata_t *rdata)
 550 {
 551         unsigned int count, i;
 552         unsigned char *current;
 553         dns_rdata_t trdata = DNS_RDATA_INIT;
 554         int n;
 555
 556         current = slab + reservelen;
 557         count = *current++ * 256;
 558         count += *current++;
 559
 560 #if DNS_RDATASET_FIXED
 561         current += (4 * count);
 562 #endif
 563
 564         for (i = 0; i < count; i++) {
 565                 rdata_from_slab(&current, rdclass, type, &trdata);
 566
 567                 n = dns_rdata_compare(&trdata, rdata);
 568                 if (n == 0)
 569                         return (ISC_TRUE);
 570                 if (n > 0)      /* In DNSSEC order. */
 571                         break;
 572                 dns_rdata_reset(&trdata);
 573         }
 574         return (ISC_FALSE);
 575 }
 576
 577 isc_result_t
 578 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 579                     unsigned int reservelen, isc_mem_t *mctx,
 580                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 581                     unsigned int flags, unsigned char **tslabp)
 582 {
 583         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
 584         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 585         dns_rdata_t ordata = DNS_RDATA_INIT;
 586         dns_rdata_t nrdata = DNS_RDATA_INIT;
 587         isc_boolean_t added_something = ISC_FALSE;
 588         unsigned int oadded = 0;
 589         unsigned int nadded = 0;
 590         unsigned int nncount = 0;
 591 #if DNS_RDATASET_FIXED
 592         unsigned int oncount;
 593         unsigned int norder = 0;
 594         unsigned int oorder = 0;
 595         unsigned char *offsetbase;
 596         unsigned int *offsettable;
 597 #endif
 598
 599         /*
 600          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 601          * or perhaps another merge routine for this purpose.
 602          */
 603
 604         REQUIRE(tslabp != NULL && *tslabp == NULL);
 605         REQUIRE(oslab != NULL && nslab != NULL);
 606
 607         ocurrent = oslab + reservelen;
 608         ocount = *ocurrent++ * 256;
 609         ocount += *ocurrent++;
 610 #if DNS_RDATASET_FIXED
 611         ocurrent += (4 * ocount);
 612 #endif
 613         ostart = ocurrent;
 614         ncurrent = nslab + reservelen;
 615         ncount = *ncurrent++ * 256;
 616         ncount += *ncurrent++;
 617 #if DNS_RDATASET_FIXED
 618         ncurrent += (4 * ncount);
 619 #endif
 620         INSIST(ocount > 0 && ncount > 0);
 621
 622 #if DNS_RDATASET_FIXED
 623         oncount = ncount;
 624 #endif
 625
 626         /*
 627          * Yes, this is inefficient!
 628          */
 629
 630         /*
 631          * Figure out the length of the old slab's data.
 632          */
 633         olength = 0;
 634         for (count = 0; count < ocount; count++) {
 635                 length = *ocurrent++ * 256;
 636                 length += *ocurrent++;
 637 #if DNS_RDATASET_FIXED
 638                 olength += length + 8;
 639                 ocurrent += length + 2;
 640 #else
 641                 olength += length + 2;
 642                 ocurrent += length;
 643 #endif
 644         }
 645
 646         /*
 647          * Start figuring out the target length and count.
 648          */
 649         tlength = reservelen + 2 + olength;
 650         tcount = ocount;
 651
 652         /*
 653          * Add in the length of rdata in the new slab that aren't in
 654          * the old slab.
 655          */
 656         do {
 657                 dns_rdata_init(&nrdata);
 658                 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 659                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 660                 {
 661                         /*
 662                          * This rdata isn't in the old slab.
 663                          */
 664 #if DNS_RDATASET_FIXED
 665                         tlength += nrdata.length + 8;
 666 #else
 667                         tlength += nrdata.length + 2;
 668 #endif
 669                         if (type == dns_rdatatype_rrsig)
 670                                 tlength++;
 671                         tcount++;
 672                         nncount++;
 673                         added_something = ISC_TRUE;
 674                 }
 675                 ncount--;
 676         } while (ncount > 0);
 677         ncount = nncount;
 678
 679         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 680             (tcount != ncount + ocount))
 681                 return (DNS_R_NOTEXACT);
 682
 683         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 684                 return (DNS_R_UNCHANGED);
 685
 686         /*
 687          * Ensure that singleton types are actually singletons.
 688          */
 689         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 690                 /*
 691                  * We have a singleton type, but there's more than one
 692                  * RR in the rdataset.
 693                  */
 694                 return (DNS_R_SINGLETON);
 695         }
 696
 697         if (tcount > 0xffff)
 698                 return (ISC_R_NOSPACE);
 699
 700         /*
 701          * Copy the reserved area from the new slab.
 702          */
 703         tstart = isc_mem_get(mctx, tlength);
 704         if (tstart == NULL)
 705                 return (ISC_R_NOMEMORY);
 706         memcpy(tstart, nslab, reservelen);
 707         tcurrent = tstart + reservelen;
 708 #if DNS_RDATASET_FIXED
 709         offsetbase = tcurrent;
 710 #endif
 711
 712         /*
 713          * Write the new count.
 714          */
 715         *tcurrent++ = (tcount & 0xff00) >> 8;
 716         *tcurrent++ = (tcount & 0x00ff);
 717
 718 #if DNS_RDATASET_FIXED
 719         /*
 720          * Skip offset table.
 721          */
 722         tcurrent += (tcount * 4);
 723
 724         offsettable = isc_mem_get(mctx,
 725                                   (ocount + oncount) * sizeof(unsigned int));
 726         if (offsettable == NULL) {
 727                 isc_mem_put(mctx, tstart, tlength);
 728                 return (ISC_R_NOMEMORY);
 729         }
 730         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 731 #endif
 732
 733         /*
 734          * Merge the two slabs.
 735          */
 736         ocurrent = ostart;
 737         INSIST(ocount != 0);
 738 #if DNS_RDATASET_FIXED
 739         oorder = ocurrent[2] * 256 + ocurrent[3];
 740         INSIST(oorder < ocount);
 741 #endif
 742         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 743
 744         ncurrent = nslab + reservelen + 2;
 745 #if DNS_RDATASET_FIXED
 746         ncurrent += (4 * oncount);
 747 #endif
 748
 749         if (ncount > 0) {
 750                 do {
 751                         dns_rdata_reset(&nrdata);
 752 #if DNS_RDATASET_FIXED
 753                         norder = ncurrent[2] * 256 + ncurrent[3];
 754
 755                         INSIST(norder < oncount);
 756 #endif
 757                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 758                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 759                                        type, &nrdata));
 760         }
 761
 762         while (oadded < ocount || nadded < ncount) {
 763                 isc_boolean_t fromold;
 764                 if (oadded == ocount)
 765                         fromold = ISC_FALSE;
 766                 else if (nadded == ncount)
 767                         fromold = ISC_TRUE;
 768                 else
 769                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 770                 if (fromold) {
 771 #if DNS_RDATASET_FIXED
 772                         offsettable[oorder] = tcurrent - offsetbase;
 773 #endif
 774                         length = ordata.length;
 775                         data = ordata.data;
 776                         if (type == dns_rdatatype_rrsig) {
 777                                 length++;
 778                                 data--;
 779                         }
 780                         *tcurrent++ = (length & 0xff00) >> 8;
 781                         *tcurrent++ = (length & 0x00ff);
 782 #if DNS_RDATASET_FIXED
 783                         tcurrent += 2;  /* fill in later */
 784 #endif
 785                         memcpy(tcurrent, data, length);
 786                         tcurrent += length;
 787                         oadded++;
 788                         if (oadded < ocount) {
 789                                 dns_rdata_reset(&ordata);
 790 #if DNS_RDATASET_FIXED
 791                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 792                                 INSIST(oorder < ocount);
 793 #endif
 794                                 rdata_from_slab(&ocurrent, rdclass, type,
 795                                                 &ordata);
 796                         }
 797                 } else {
 798 #if DNS_RDATASET_FIXED
 799                         offsettable[ocount + norder] = tcurrent - offsetbase;
 800 #endif
 801                         length = nrdata.length;
 802                         data = nrdata.data;
 803                         if (type == dns_rdatatype_rrsig) {
 804                                 length++;
 805                                 data--;
 806                         }
 807                         *tcurrent++ = (length & 0xff00) >> 8;
 808                         *tcurrent++ = (length & 0x00ff);
 809 #if DNS_RDATASET_FIXED
 810                         tcurrent += 2;  /* fill in later */
 811 #endif
 812                         memcpy(tcurrent, data, length);
 813                         tcurrent += length;
 814                         nadded++;
 815                         if (nadded < ncount) {
 816                                 do {
 817                                         dns_rdata_reset(&nrdata);
 818 #if DNS_RDATASET_FIXED
 819                                         norder = ncurrent[2] * 256 + ncurrent[3];
 820                                         INSIST(norder < oncount);
 821 #endif
 822                                         rdata_from_slab(&ncurrent, rdclass,
 823                                                         type, &nrdata);
 824                                 } while (rdata_in_slab(oslab, reservelen,
 825                                                        rdclass, type,
 826                                                        &nrdata));
 827                         }
 828                 }
 829         }
 830
 831 #if DNS_RDATASET_FIXED
 832         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 833
 834         isc_mem_put(mctx, offsettable,
 835                     (ocount + oncount) * sizeof(unsigned int));
 836 #endif
 837
 838         INSIST(tcurrent == tstart + tlength);
 839
 840         *tslabp = tstart;
 841
 842         return (ISC_R_SUCCESS);
 843 }
 844
 845 isc_result_t
 846 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 847                        unsigned int reservelen, isc_mem_t *mctx,
 848                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 849                        unsigned int flags, unsigned char **tslabp)
 850 {
 851         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 852         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 853         dns_rdata_t srdata = DNS_RDATA_INIT;
 854         dns_rdata_t mrdata = DNS_RDATA_INIT;
 855 #if DNS_RDATASET_FIXED
 856         unsigned char *offsetbase;
 857         unsigned int *offsettable;
 858         unsigned int order;
 859 #endif
 860
 861         REQUIRE(tslabp != NULL && *tslabp == NULL);
 862         REQUIRE(mslab != NULL && sslab != NULL);
 863
 864         mcurrent = mslab + reservelen;
 865         mcount = *mcurrent++ * 256;
 866         mcount += *mcurrent++;
 867         scurrent = sslab + reservelen;
 868         scount = *scurrent++ * 256;
 869         scount += *scurrent++;
 870         INSIST(mcount > 0 && scount > 0);
 871
 872         /*
 873          * Yes, this is inefficient!
 874          */
 875
 876         /*
 877          * Start figuring out the target length and count.
 878          */
 879         tlength = reservelen + 2;
 880         tcount = 0;
 881         rcount = 0;
 882
 883 #if DNS_RDATASET_FIXED
 884         mcurrent += 4 * mcount;
 885         scurrent += 4 * scount;
 886 #endif
 887         sstart = scurrent;
 888
 889         /*
 890          * Add in the length of rdata in the mslab that aren't in
 891          * the sslab.
 892          */
 893         for (i = 0; i < mcount; i++) {
 894                 unsigned char *mrdatabegin = mcurrent;
 895                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 896                 scurrent = sstart;
 897                 for (count = 0; count < scount; count++) {
 898                         dns_rdata_reset(&srdata);
 899                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 900                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 901                                 break;
 902                 }
 903                 if (count == scount) {
 904                         /*
 905                          * This rdata isn't in the sslab, and thus isn't
 906                          * being subtracted.
 907                          */
 908                         tlength += mcurrent - mrdatabegin;
 909                         tcount++;
 910                 } else
 911                         rcount++;
 912                 dns_rdata_reset(&mrdata);
 913         }
 914
 915 #if DNS_RDATASET_FIXED
 916         tlength += (4 * tcount);
 917 #endif
 918
 919         /*
 920          * Check that all the records originally existed.  The numeric
 921          * check only works as rdataslabs do not contain duplicates.
 922          */
 923         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 924                 return (DNS_R_NOTEXACT);
 925
 926         /*
 927          * Don't continue if the new rdataslab would be empty.
 928          */
 929         if (tcount == 0)
 930                 return (DNS_R_NXRRSET);
 931
 932         /*
 933          * If nothing is going to change, we can stop.
 934          */
 935         if (rcount == 0)
 936                 return (DNS_R_UNCHANGED);
 937
 938         /*
 939          * Copy the reserved area from the mslab.
 940          */
 941         tstart = isc_mem_get(mctx, tlength);
 942         if (tstart == NULL)
 943                 return (ISC_R_NOMEMORY);
 944         memcpy(tstart, mslab, reservelen);
 945         tcurrent = tstart + reservelen;
 946 #if DNS_RDATASET_FIXED
 947         offsetbase = tcurrent;
 948
 949         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 950         if (offsettable == NULL) {
 951                 isc_mem_put(mctx, tstart, tlength);
 952                 return (ISC_R_NOMEMORY);
 953         }
 954         memset(offsettable, 0, mcount * sizeof(unsigned int));
 955 #endif
 956
 957         /*
 958          * Write the new count.
 959          */
 960         *tcurrent++ = (tcount & 0xff00) >> 8;
 961         *tcurrent++ = (tcount & 0x00ff);
 962
 963 #if DNS_RDATASET_FIXED
 964         tcurrent += (4 * tcount);
 965 #endif
 966
 967         /*
 968          * Copy the parts of mslab not in sslab.
 969          */
 970         mcurrent = mslab + reservelen;
 971         mcount = *mcurrent++ * 256;
 972         mcount += *mcurrent++;
 973 #if DNS_RDATASET_FIXED
 974         mcurrent += (4 * mcount);
 975 #endif
 976         for (i = 0; i < mcount; i++) {
 977                 unsigned char *mrdatabegin = mcurrent;
 978 #if DNS_RDATASET_FIXED
 979                 order = mcurrent[2] * 256 + mcurrent[3];
 980                 INSIST(order < mcount);
 981 #endif
 982                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 983                 scurrent = sstart;
 984                 for (count = 0; count < scount; count++) {
 985                         dns_rdata_reset(&srdata);
 986                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 987                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 988                                 break;
 989                 }
 990                 if (count == scount) {
 991                         /*
 992                          * This rdata isn't in the sslab, and thus should be
 993                          * copied to the tslab.
 994                          */
 995                         unsigned int length = mcurrent - mrdatabegin;
 996 #if DNS_RDATASET_FIXED
 997                         offsettable[order] = tcurrent - offsetbase;
 998 #endif
 999                         memcpy(tcurrent, mrdatabegin, length);
1000                         tcurrent += length;
1001                 }
1002                 dns_rdata_reset(&mrdata);
1003         }
1004
1005 #if DNS_RDATASET_FIXED
1006         fillin_offsets(offsetbase, offsettable, mcount);
1007
1008         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
1009 #endif
1010
1011         INSIST(tcurrent == tstart + tlength);
1012
1013         *tslabp = tstart;
1014
1015         return (ISC_R_SUCCESS);
1016 }
1017
1018 isc_boolean_t
1019 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
1020                     unsigned int reservelen)
1021 {
1022         unsigned char *current1, *current2;
1023         unsigned int count1, count2;
1024         unsigned int length1, length2;
1025
1026         current1 = slab1 + reservelen;
1027         count1 = *current1++ * 256;
1028         count1 += *current1++;
1029
1030         current2 = slab2 + reservelen;
1031         count2 = *current2++ * 256;
1032         count2 += *current2++;
1033
1034         if (count1 != count2)
1035                 return (ISC_FALSE);
1036
1037 #if DNS_RDATASET_FIXED
1038         current1 += (4 * count1);
1039         current2 += (4 * count2);
1040 #endif
1041
1042         while (count1 > 0) {
1043                 length1 = *current1++ * 256;
1044                 length1 += *current1++;
1045
1046                 length2 = *current2++ * 256;
1047                 length2 += *current2++;
1048
1049 #if DNS_RDATASET_FIXED
1050                 current1 += 2;
1051                 current2 += 2;
1052 #endif
1053
1054                 if (length1 != length2 ||
1055                     memcmp(current1, current2, length1) != 0)
1056                         return (ISC_FALSE);
1057
1058                 current1 += length1;
1059                 current2 += length1;
1060
1061                 count1--;
1062         }
1063         return (ISC_TRUE);
1064 }
1065
1066 isc_boolean_t
1067 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1068                      unsigned int reservelen, dns_rdataclass_t rdclass,
1069                      dns_rdatatype_t type)
1070 {
1071         unsigned char *current1, *current2;
1072         unsigned int count1, count2;
1073         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1074         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1075
1076         current1 = slab1 + reservelen;
1077         count1 = *current1++ * 256;
1078         count1 += *current1++;
1079
1080         current2 = slab2 + reservelen;
1081         count2 = *current2++ * 256;
1082         count2 += *current2++;
1083
1084         if (count1 != count2)
1085                 return (ISC_FALSE);
1086
1087 #if DNS_RDATASET_FIXED
1088         current1 += (4 * count1);
1089         current2 += (4 * count2);
1090 #endif
1091
1092         while (count1-- > 0) {
1093                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1094                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1095                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1096                         return (ISC_FALSE);
1097                 dns_rdata_reset(&rdata1);
1098                 dns_rdata_reset(&rdata2);
1099         }
1100         return (ISC_TRUE);
1101 }