contrib/bind9/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2010  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: rdataslab.c,v 1.48.50.2.24.1 2010/03/03 22:06:39 marka Exp $ */
  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  *              data            (data length bytes)
  57  *
  58  * Offsets are from the end of the header.
  59  *
  60  * Load order traversal is performed by walking the offset table to find
  61  * the start of the record (DNS_RDATASET_FIXED = 1).
  62  *
  63  * DNSSEC order traversal is performed by walking the data records.
  64  *
  65  * The order is stored with record to allow for efficient reconstruction
  66  * of the offset table following a merge or subtraction.
  67  *
  68  * The iterator methods here currently only support DNSSEC order iteration.
  69  *
  70  * The iterator methods in rbtdb support both load order and DNSSEC order
  71  * iteration.
  72  *
  73  * WARNING:
  74  *      rbtdb.c directly interacts with the slab's raw structures.  If the
  75  *      structure changes then rbtdb.c also needs to be updated to reflect
  76  *      the changes.  See the areas tagged with "RDATASLAB".
  77  */
  78
  79 struct xrdata {
  80         dns_rdata_t     rdata;
  81         unsigned int    order;
  82 };
  83
  84 /*% Note: the "const void *" are just to make qsort happy.  */
  85 static int
  86 compare_rdata(const void *p1, const void *p2) {
  87         const struct xrdata *x1 = p1;
  88         const struct xrdata *x2 = p2;
  89         return (dns_rdata_compare(&x1->rdata, &x2->rdata));
  90 }
  91
  92 #if DNS_RDATASET_FIXED
  93 static void
  94 fillin_offsets(unsigned char *offsetbase, unsigned int *offsettable,
  95                unsigned length)
  96 {
  97         unsigned int i, j;
  98         unsigned char *raw;
  99
 100         for (i = 0, j = 0; i < length; i++) {
 101
 102                 if (offsettable[i] == 0)
 103                         continue;
 104
 105                 /*
 106                  * Fill in offset table.
 107                  */
 108                 raw = &offsetbase[j*4 + 2];
 109                 *raw++ = (offsettable[i] & 0xff000000) >> 24;
 110                 *raw++ = (offsettable[i] & 0xff0000) >> 16;
 111                 *raw++ = (offsettable[i] & 0xff00) >> 8;
 112                 *raw = offsettable[i] & 0xff;
 113
 114                 /*
 115                  * Fill in table index.
 116                  */
 117                 raw = offsetbase + offsettable[i] + 2;
 118                 *raw++ = (j & 0xff00) >> 8;
 119                 *raw = j++ & 0xff;
 120         }
 121 }
 122 #endif
 123
 124 isc_result_t
 125 dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
 126                            isc_region_t *region, unsigned int reservelen)
 127 {
 128         /*
 129          * Use &removed as a sentinal pointer for duplicate
 130          * rdata as rdata.data == NULL is valid.
 131          */
 132         static unsigned char removed;
 133         struct xrdata  *x;
 134         unsigned char  *rawbuf;
 135 #if DNS_RDATASET_FIXED
 136         unsigned char  *offsetbase;
 137 #endif
 138         unsigned int    buflen;
 139         isc_result_t    result;
 140         unsigned int    nitems;
 141         unsigned int    nalloc;
 142         unsigned int    i;
 143 #if DNS_RDATASET_FIXED
 144         unsigned int   *offsettable;
 145 #endif
 146         unsigned int    length;
 147
 148         buflen = reservelen + 2;
 149
 150         nalloc = dns_rdataset_count(rdataset);
 151         nitems = nalloc;
 152         if (nitems == 0)
 153                 return (ISC_R_FAILURE);
 154
 155         if (nalloc > 0xffff)
 156                 return (ISC_R_NOSPACE);
 157
 158         x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 159         if (x == NULL)
 160                 return (ISC_R_NOMEMORY);
 161
 162         /*
 163          * Save all of the rdata members into an array.
 164          */
 165         result = dns_rdataset_first(rdataset);
 166         if (result != ISC_R_SUCCESS)
 167                 goto free_rdatas;
 168         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 169                 INSIST(result == ISC_R_SUCCESS);
 170                 dns_rdata_init(&x[i].rdata);
 171                 dns_rdataset_current(rdataset, &x[i].rdata);
 172                 INSIST(x[i].rdata.data != &removed);
 173 #if DNS_RDATASET_FIXED
 174                 x[i].order = i;
 175 #endif
 176                 result = dns_rdataset_next(rdataset);
 177         }
 178         if (result != ISC_R_NOMORE)
 179                 goto free_rdatas;
 180         if (i != nalloc) {
 181                 /*
 182                  * Somehow we iterated over fewer rdatas than
 183                  * dns_rdataset_count() said there were!
 184                  */
 185                 result = ISC_R_FAILURE;
 186                 goto free_rdatas;
 187         }
 188
 189         /*
 190          * Put into DNSSEC order.
 191          */
 192         qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 193
 194         /*
 195          * Remove duplicates and compute the total storage required.
 196          *
 197          * If an rdata is not a duplicate, accumulate the storage size
 198          * required for the rdata.  We do not store the class, type, etc,
 199          * just the rdata, so our overhead is 2 bytes for the number of
 200          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 201          * and then the rdata itself.
 202          */
 203         for (i = 1; i < nalloc; i++) {
 204                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 205                         x[i-1].rdata.data = &removed;
 206 #if DNS_RDATASET_FIXED
 207                         /*
 208                          * Preserve the least order so A, B, A -> A, B
 209                          * after duplicate removal.
 210                          */
 211                         if (x[i-1].order < x[i].order)
 212                                 x[i].order = x[i-1].order;
 213 #endif
 214                         nitems--;
 215                 } else {
 216 #if DNS_RDATASET_FIXED
 217                         buflen += (8 + x[i-1].rdata.length);
 218 #else
 219                         buflen += (2 + x[i-1].rdata.length);
 220 #endif
 221                         /*
 222                          * Provide space to store the per RR meta data.
 223                          */
 224                         if (rdataset->type == dns_rdatatype_rrsig)
 225                                 buflen++;
 226                 }
 227         }
 228         /*
 229          * Don't forget the last item!
 230          */
 231 #if DNS_RDATASET_FIXED
 232         buflen += (8 + x[i-1].rdata.length);
 233 #else
 234         buflen += (2 + x[i-1].rdata.length);
 235 #endif
 236         /*
 237          * Provide space to store the per RR meta data.
 238          */
 239         if (rdataset->type == dns_rdatatype_rrsig)
 240                 buflen++;
 241
 242         /*
 243          * Ensure that singleton types are actually singletons.
 244          */
 245         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 246                 /*
 247                  * We have a singleton type, but there's more than one
 248                  * RR in the rdataset.
 249                  */
 250                 result = DNS_R_SINGLETON;
 251                 goto free_rdatas;
 252         }
 253
 254         /*
 255          * Allocate the memory, set up a buffer, start copying in
 256          * data.
 257          */
 258         rawbuf = isc_mem_get(mctx, buflen);
 259         if (rawbuf == NULL) {
 260                 result = ISC_R_NOMEMORY;
 261                 goto free_rdatas;
 262         }
 263
 264 #if DNS_RDATASET_FIXED
 265         /* Allocate temporary offset table. */
 266         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 267         if (offsettable == NULL) {
 268                 isc_mem_put(mctx, rawbuf, buflen);
 269                 result = ISC_R_NOMEMORY;
 270                 goto free_rdatas;
 271         }
 272         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 273 #endif
 274
 275         region->base = rawbuf;
 276         region->length = buflen;
 277
 278         rawbuf += reservelen;
 279 #if DNS_RDATASET_FIXED
 280         offsetbase = rawbuf;
 281 #endif
 282
 283         *rawbuf++ = (nitems & 0xff00) >> 8;
 284         *rawbuf++ = (nitems & 0x00ff);
 285
 286 #if DNS_RDATASET_FIXED
 287         /* Skip load order table.  Filled in later. */
 288         rawbuf += nitems * 4;
 289 #endif
 290
 291         for (i = 0; i < nalloc; i++) {
 292                 if (x[i].rdata.data == &removed)
 293                         continue;
 294 #if DNS_RDATASET_FIXED
 295                 offsettable[x[i].order] = rawbuf - offsetbase;
 296 #endif
 297                 length = x[i].rdata.length;
 298                 if (rdataset->type == dns_rdatatype_rrsig)
 299                         length++;
 300                 *rawbuf++ = (length & 0xff00) >> 8;
 301                 *rawbuf++ = (length & 0x00ff);
 302 #if DNS_RDATASET_FIXED
 303                 rawbuf += 2;    /* filled in later */
 304 #endif
 305                 /*
 306                  * Store the per RR meta data.
 307                  */
 308                 if (rdataset->type == dns_rdatatype_rrsig) {
 309                         *rawbuf++ |= (x[i].rdata.flags & DNS_RDATA_OFFLINE) ?
 310                                             DNS_RDATASLAB_OFFLINE : 0;
 311                 }
 312                 memcpy(rawbuf, x[i].rdata.data, x[i].rdata.length);
 313                 rawbuf += x[i].rdata.length;
 314         }
 315
 316 #if DNS_RDATASET_FIXED
 317         fillin_offsets(offsetbase, offsettable, nalloc);
 318         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 319 #endif
 320
 321         result = ISC_R_SUCCESS;
 322
 323  free_rdatas:
 324         isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 325         return (result);
 326 }
 327
 328 static void
 329 rdataset_disassociate(dns_rdataset_t *rdataset) {
 330         UNUSED(rdataset);
 331 }
 332
 333 static isc_result_t
 334 rdataset_first(dns_rdataset_t *rdataset) {
 335         unsigned char *raw = rdataset->private3;
 336         unsigned int count;
 337
 338         count = raw[0] * 256 + raw[1];
 339         if (count == 0) {
 340                 rdataset->private5 = NULL;
 341                 return (ISC_R_NOMORE);
 342         }
 343 #if DNS_RDATASET_FIXED
 344         raw += 2 + (4 * count);
 345 #else
 346         raw += 2;
 347 #endif
 348         /*
 349          * The privateuint4 field is the number of rdata beyond the cursor
 350          * position, so we decrement the total count by one before storing
 351          * it.
 352          */
 353         count--;
 354         rdataset->privateuint4 = count;
 355         rdataset->private5 = raw;
 356
 357         return (ISC_R_SUCCESS);
 358 }
 359
 360 static isc_result_t
 361 rdataset_next(dns_rdataset_t *rdataset) {
 362         unsigned int count;
 363         unsigned int length;
 364         unsigned char *raw;
 365
 366         count = rdataset->privateuint4;
 367         if (count == 0)
 368                 return (ISC_R_NOMORE);
 369         count--;
 370         rdataset->privateuint4 = count;
 371         raw = rdataset->private5;
 372         length = raw[0] * 256 + raw[1];
 373 #if DNS_RDATASET_FIXED
 374         raw += length + 4;
 375 #else
 376         raw += length + 2;
 377 #endif
 378         rdataset->private5 = raw;
 379
 380         return (ISC_R_SUCCESS);
 381 }
 382
 383 static void
 384 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 385         unsigned char *raw = rdataset->private5;
 386         isc_region_t r;
 387         unsigned int length;
 388         unsigned int flags = 0;
 389
 390         REQUIRE(raw != NULL);
 391
 392         length = raw[0] * 256 + raw[1];
 393 #if DNS_RDATASET_FIXED
 394         raw += 4;
 395 #else
 396         raw += 2;
 397 #endif
 398         if (rdataset->type == dns_rdatatype_rrsig) {
 399                 if (*raw & DNS_RDATASLAB_OFFLINE)
 400                         flags |= DNS_RDATA_OFFLINE;
 401                 length--;
 402                 raw++;
 403         }
 404         r.length = length;
 405         r.base = raw;
 406         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 407         rdata->flags |= flags;
 408 }
 409
 410 static void
 411 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 412         *target = *source;
 413
 414         /*
 415          * Reset iterator state.
 416          */
 417         target->privateuint4 = 0;
 418         target->private5 = NULL;
 419 }
 420
 421 static unsigned int
 422 rdataset_count(dns_rdataset_t *rdataset) {
 423         unsigned char *raw = rdataset->private3;
 424         unsigned int count;
 425
 426         count = raw[0] * 256 + raw[1];
 427
 428         return (count);
 429 }
 430
 431 static dns_rdatasetmethods_t rdataset_methods = {
 432         rdataset_disassociate,
 433         rdataset_first,
 434         rdataset_next,
 435         rdataset_current,
 436         rdataset_clone,
 437         rdataset_count,
 438         NULL,
 439         NULL,
 440         NULL,
 441         NULL,
 442         NULL,
 443         NULL,
 444         NULL,
 445         NULL,
 446         NULL
 447 };
 448
 449 void
 450 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 451                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 452                          dns_rdatatype_t covers, dns_ttl_t ttl,
 453                          dns_rdataset_t *rdataset)
 454 {
 455         REQUIRE(slab != NULL);
 456         REQUIRE(!dns_rdataset_isassociated(rdataset));
 457
 458         rdataset->methods = &rdataset_methods;
 459         rdataset->rdclass = rdclass;
 460         rdataset->type = rdtype;
 461         rdataset->covers = covers;
 462         rdataset->ttl = ttl;
 463         rdataset->trust = 0;
 464         rdataset->private1 = NULL;
 465         rdataset->private2 = NULL;
 466         rdataset->private3 = slab + reservelen;
 467
 468         /*
 469          * Reset iterator state.
 470          */
 471         rdataset->privateuint4 = 0;
 472         rdataset->private5 = NULL;
 473 }
 474
 475 unsigned int
 476 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 477         unsigned int count, length;
 478         unsigned char *current;
 479
 480         REQUIRE(slab != NULL);
 481
 482         current = slab + reservelen;
 483         count = *current++ * 256;
 484         count += *current++;
 485 #if DNS_RDATASET_FIXED
 486         current += (4 * count);
 487 #endif
 488         while (count > 0) {
 489                 count--;
 490                 length = *current++ * 256;
 491                 length += *current++;
 492 #if DNS_RDATASET_FIXED
 493                 current += length + 2;
 494 #else
 495                 current += length;
 496 #endif
 497         }
 498
 499         return ((unsigned int)(current - slab));
 500 }
 501
 502 /*
 503  * Make the dns_rdata_t 'rdata' refer to the slab item
 504  * beginning at '*current', which is part of a slab of type
 505  * 'type' and class 'rdclass', and advance '*current' to
 506  * point to the next item in the slab.
 507  */
 508 static inline void
 509 rdata_from_slab(unsigned char **current,
 510               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 511               dns_rdata_t *rdata)
 512 {
 513         unsigned char *tcurrent = *current;
 514         isc_region_t region;
 515         unsigned int length;
 516         isc_boolean_t offline = ISC_FALSE;
 517
 518         length = *tcurrent++ * 256;
 519         length += *tcurrent++;
 520
 521         if (type == dns_rdatatype_rrsig) {
 522                 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0)
 523                         offline = ISC_TRUE;
 524                 length--;
 525                 tcurrent++;
 526         }
 527         region.length = length;
 528 #if DNS_RDATASET_FIXED
 529         tcurrent += 2;
 530 #endif
 531         region.base = tcurrent;
 532         tcurrent += region.length;
 533         dns_rdata_fromregion(rdata, rdclass, type, &region);
 534         if (offline)
 535                 rdata->flags |= DNS_RDATA_OFFLINE;
 536         *current = tcurrent;
 537 }
 538
 539 /*
 540  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 541  * contains an rdata identical to 'rdata'.  This does case insensitive
 542  * comparisons per DNSSEC.
 543  */
 544 static inline isc_boolean_t
 545 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 546               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 547               dns_rdata_t *rdata)
 548 {
 549         unsigned int count, i;
 550         unsigned char *current;
 551         dns_rdata_t trdata = DNS_RDATA_INIT;
 552         int n;
 553
 554         current = slab + reservelen;
 555         count = *current++ * 256;
 556         count += *current++;
 557
 558 #if DNS_RDATASET_FIXED
 559         current += (4 * count);
 560 #endif
 561
 562         for (i = 0; i < count; i++) {
 563                 rdata_from_slab(&current, rdclass, type, &trdata);
 564
 565                 n = dns_rdata_compare(&trdata, rdata);
 566                 if (n == 0)
 567                         return (ISC_TRUE);
 568                 if (n > 0)      /* In DNSSEC order. */
 569                         break;
 570                 dns_rdata_reset(&trdata);
 571         }
 572         return (ISC_FALSE);
 573 }
 574
 575 isc_result_t
 576 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 577                     unsigned int reservelen, isc_mem_t *mctx,
 578                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 579                     unsigned int flags, unsigned char **tslabp)
 580 {
 581         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
 582         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 583         dns_rdata_t ordata = DNS_RDATA_INIT;
 584         dns_rdata_t nrdata = DNS_RDATA_INIT;
 585         isc_boolean_t added_something = ISC_FALSE;
 586         unsigned int oadded = 0;
 587         unsigned int nadded = 0;
 588         unsigned int nncount = 0;
 589 #if DNS_RDATASET_FIXED
 590         unsigned int oncount;
 591         unsigned int norder = 0;
 592         unsigned int oorder = 0;
 593         unsigned char *offsetbase;
 594         unsigned int *offsettable;
 595 #endif
 596
 597         /*
 598          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 599          * or perhaps another merge routine for this purpose.
 600          */
 601
 602         REQUIRE(tslabp != NULL && *tslabp == NULL);
 603         REQUIRE(oslab != NULL && nslab != NULL);
 604
 605         ocurrent = oslab + reservelen;
 606         ocount = *ocurrent++ * 256;
 607         ocount += *ocurrent++;
 608 #if DNS_RDATASET_FIXED
 609         ocurrent += (4 * ocount);
 610 #endif
 611         ostart = ocurrent;
 612         ncurrent = nslab + reservelen;
 613         ncount = *ncurrent++ * 256;
 614         ncount += *ncurrent++;
 615 #if DNS_RDATASET_FIXED
 616         ncurrent += (4 * ncount);
 617 #endif
 618         INSIST(ocount > 0 && ncount > 0);
 619
 620 #if DNS_RDATASET_FIXED
 621         oncount = ncount;
 622 #endif
 623
 624         /*
 625          * Yes, this is inefficient!
 626          */
 627
 628         /*
 629          * Figure out the length of the old slab's data.
 630          */
 631         olength = 0;
 632         for (count = 0; count < ocount; count++) {
 633                 length = *ocurrent++ * 256;
 634                 length += *ocurrent++;
 635 #if DNS_RDATASET_FIXED
 636                 olength += length + 8;
 637                 ocurrent += length + 2;
 638 #else
 639                 olength += length + 2;
 640                 ocurrent += length;
 641 #endif
 642         }
 643
 644         /*
 645          * Start figuring out the target length and count.
 646          */
 647         tlength = reservelen + 2 + olength;
 648         tcount = ocount;
 649
 650         /*
 651          * Add in the length of rdata in the new slab that aren't in
 652          * the old slab.
 653          */
 654         do {
 655                 dns_rdata_init(&nrdata);
 656                 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 657                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 658                 {
 659                         /*
 660                          * This rdata isn't in the old slab.
 661                          */
 662 #if DNS_RDATASET_FIXED
 663                         tlength += nrdata.length + 8;
 664 #else
 665                         tlength += nrdata.length + 2;
 666 #endif
 667                         if (type == dns_rdatatype_rrsig)
 668                                 tlength++;
 669                         tcount++;
 670                         nncount++;
 671                         added_something = ISC_TRUE;
 672                 }
 673                 ncount--;
 674         } while (ncount > 0);
 675         ncount = nncount;
 676
 677         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 678             (tcount != ncount + ocount))
 679                 return (DNS_R_NOTEXACT);
 680
 681         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 682                 return (DNS_R_UNCHANGED);
 683
 684         /*
 685          * Ensure that singleton types are actually singletons.
 686          */
 687         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 688                 /*
 689                  * We have a singleton type, but there's more than one
 690                  * RR in the rdataset.
 691                  */
 692                 return (DNS_R_SINGLETON);
 693         }
 694
 695         if (tcount > 0xffff)
 696                 return (ISC_R_NOSPACE);
 697
 698         /*
 699          * Copy the reserved area from the new slab.
 700          */
 701         tstart = isc_mem_get(mctx, tlength);
 702         if (tstart == NULL)
 703                 return (ISC_R_NOMEMORY);
 704         memcpy(tstart, nslab, reservelen);
 705         tcurrent = tstart + reservelen;
 706 #if DNS_RDATASET_FIXED
 707         offsetbase = tcurrent;
 708 #endif
 709
 710         /*
 711          * Write the new count.
 712          */
 713         *tcurrent++ = (tcount & 0xff00) >> 8;
 714         *tcurrent++ = (tcount & 0x00ff);
 715
 716 #if DNS_RDATASET_FIXED
 717         /*
 718          * Skip offset table.
 719          */
 720         tcurrent += (tcount * 4);
 721
 722         offsettable = isc_mem_get(mctx,
 723                                   (ocount + oncount) * sizeof(unsigned int));
 724         if (offsettable == NULL) {
 725                 isc_mem_put(mctx, tstart, tlength);
 726                 return (ISC_R_NOMEMORY);
 727         }
 728         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 729 #endif
 730
 731         /*
 732          * Merge the two slabs.
 733          */
 734         ocurrent = ostart;
 735         INSIST(ocount != 0);
 736 #if DNS_RDATASET_FIXED
 737         oorder = ocurrent[2] * 256 + ocurrent[3];
 738         INSIST(oorder < ocount);
 739 #endif
 740         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 741
 742         ncurrent = nslab + reservelen + 2;
 743 #if DNS_RDATASET_FIXED
 744         ncurrent += (4 * oncount);
 745 #endif
 746
 747         if (ncount > 0) {
 748                 do {
 749                         dns_rdata_reset(&nrdata);
 750 #if DNS_RDATASET_FIXED
 751                         norder = ncurrent[2] * 256 + ncurrent[3];
 752
 753                         INSIST(norder < oncount);
 754 #endif
 755                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 756                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 757                                        type, &nrdata));
 758         }
 759
 760         while (oadded < ocount || nadded < ncount) {
 761                 isc_boolean_t fromold;
 762                 if (oadded == ocount)
 763                         fromold = ISC_FALSE;
 764                 else if (nadded == ncount)
 765                         fromold = ISC_TRUE;
 766                 else
 767                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 768                 if (fromold) {
 769 #if DNS_RDATASET_FIXED
 770                         offsettable[oorder] = tcurrent - offsetbase;
 771 #endif
 772                         length = ordata.length;
 773                         data = ordata.data;
 774                         if (type == dns_rdatatype_rrsig) {
 775                                 length++;
 776                                 data--;
 777                         }
 778                         *tcurrent++ = (length & 0xff00) >> 8;
 779                         *tcurrent++ = (length & 0x00ff);
 780 #if DNS_RDATASET_FIXED
 781                         tcurrent += 2;  /* fill in later */
 782 #endif
 783                         memcpy(tcurrent, data, length);
 784                         tcurrent += length;
 785                         oadded++;
 786                         if (oadded < ocount) {
 787                                 dns_rdata_reset(&ordata);
 788 #if DNS_RDATASET_FIXED
 789                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 790                                 INSIST(oorder < ocount);
 791 #endif
 792                                 rdata_from_slab(&ocurrent, rdclass, type,
 793                                                 &ordata);
 794                         }
 795                 } else {
 796 #if DNS_RDATASET_FIXED
 797                         offsettable[ocount + norder] = tcurrent - offsetbase;
 798 #endif
 799                         length = nrdata.length;
 800                         data = nrdata.data;
 801                         if (type == dns_rdatatype_rrsig) {
 802                                 length++;
 803                                 data--;
 804                         }
 805                         *tcurrent++ = (length & 0xff00) >> 8;
 806                         *tcurrent++ = (length & 0x00ff);
 807 #if DNS_RDATASET_FIXED
 808                         tcurrent += 2;  /* fill in later */
 809 #endif
 810                         memcpy(tcurrent, data, length);
 811                         tcurrent += length;
 812                         nadded++;
 813                         if (nadded < ncount) {
 814                                 do {
 815                                         dns_rdata_reset(&nrdata);
 816 #if DNS_RDATASET_FIXED
 817                                         norder = ncurrent[2] * 256 + ncurrent[3];
 818                                         INSIST(norder < oncount);
 819 #endif
 820                                         rdata_from_slab(&ncurrent, rdclass,
 821                                                         type, &nrdata);
 822                                 } while (rdata_in_slab(oslab, reservelen,
 823                                                        rdclass, type,
 824                                                        &nrdata));
 825                         }
 826                 }
 827         }
 828
 829 #if DNS_RDATASET_FIXED
 830         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 831
 832         isc_mem_put(mctx, offsettable,
 833                     (ocount + oncount) * sizeof(unsigned int));
 834 #endif
 835
 836         INSIST(tcurrent == tstart + tlength);
 837
 838         *tslabp = tstart;
 839
 840         return (ISC_R_SUCCESS);
 841 }
 842
 843 isc_result_t
 844 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 845                        unsigned int reservelen, isc_mem_t *mctx,
 846                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 847                        unsigned int flags, unsigned char **tslabp)
 848 {
 849         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 850         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 851         dns_rdata_t srdata = DNS_RDATA_INIT;
 852         dns_rdata_t mrdata = DNS_RDATA_INIT;
 853 #if DNS_RDATASET_FIXED
 854         unsigned char *offsetbase;
 855         unsigned int *offsettable;
 856         unsigned int order;
 857 #endif
 858
 859         REQUIRE(tslabp != NULL && *tslabp == NULL);
 860         REQUIRE(mslab != NULL && sslab != NULL);
 861
 862         mcurrent = mslab + reservelen;
 863         mcount = *mcurrent++ * 256;
 864         mcount += *mcurrent++;
 865         scurrent = sslab + reservelen;
 866         scount = *scurrent++ * 256;
 867         scount += *scurrent++;
 868         INSIST(mcount > 0 && scount > 0);
 869
 870         /*
 871          * Yes, this is inefficient!
 872          */
 873
 874         /*
 875          * Start figuring out the target length and count.
 876          */
 877         tlength = reservelen + 2;
 878         tcount = 0;
 879         rcount = 0;
 880
 881 #if DNS_RDATASET_FIXED
 882         mcurrent += 4 * mcount;
 883         scurrent += 4 * scount;
 884 #endif
 885         sstart = scurrent;
 886
 887         /*
 888          * Add in the length of rdata in the mslab that aren't in
 889          * the sslab.
 890          */
 891         for (i = 0; i < mcount; i++) {
 892                 unsigned char *mrdatabegin = mcurrent;
 893                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 894                 scurrent = sstart;
 895                 for (count = 0; count < scount; count++) {
 896                         dns_rdata_reset(&srdata);
 897                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 898                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 899                                 break;
 900                 }
 901                 if (count == scount) {
 902                         /*
 903                          * This rdata isn't in the sslab, and thus isn't
 904                          * being subtracted.
 905                          */
 906                         tlength += mcurrent - mrdatabegin;
 907                         tcount++;
 908                 } else
 909                         rcount++;
 910                 dns_rdata_reset(&mrdata);
 911         }
 912
 913 #if DNS_RDATASET_FIXED
 914         tlength += (4 * tcount);
 915 #endif
 916
 917         /*
 918          * Check that all the records originally existed.  The numeric
 919          * check only works as rdataslabs do not contain duplicates.
 920          */
 921         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 922                 return (DNS_R_NOTEXACT);
 923
 924         /*
 925          * Don't continue if the new rdataslab would be empty.
 926          */
 927         if (tcount == 0)
 928                 return (DNS_R_NXRRSET);
 929
 930         /*
 931          * If nothing is going to change, we can stop.
 932          */
 933         if (rcount == 0)
 934                 return (DNS_R_UNCHANGED);
 935
 936         /*
 937          * Copy the reserved area from the mslab.
 938          */
 939         tstart = isc_mem_get(mctx, tlength);
 940         if (tstart == NULL)
 941                 return (ISC_R_NOMEMORY);
 942         memcpy(tstart, mslab, reservelen);
 943         tcurrent = tstart + reservelen;
 944 #if DNS_RDATASET_FIXED
 945         offsetbase = tcurrent;
 946
 947         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 948         if (offsettable == NULL) {
 949                 isc_mem_put(mctx, tstart, tlength);
 950                 return (ISC_R_NOMEMORY);
 951         }
 952         memset(offsettable, 0, mcount * sizeof(unsigned int));
 953 #endif
 954
 955         /*
 956          * Write the new count.
 957          */
 958         *tcurrent++ = (tcount & 0xff00) >> 8;
 959         *tcurrent++ = (tcount & 0x00ff);
 960
 961 #if DNS_RDATASET_FIXED
 962         tcurrent += (4 * tcount);
 963 #endif
 964
 965         /*
 966          * Copy the parts of mslab not in sslab.
 967          */
 968         mcurrent = mslab + reservelen;
 969         mcount = *mcurrent++ * 256;
 970         mcount += *mcurrent++;
 971 #if DNS_RDATASET_FIXED
 972         mcurrent += (4 * mcount);
 973 #endif
 974         for (i = 0; i < mcount; i++) {
 975                 unsigned char *mrdatabegin = mcurrent;
 976 #if DNS_RDATASET_FIXED
 977                 order = mcurrent[2] * 256 + mcurrent[3];
 978                 INSIST(order < mcount);
 979 #endif
 980                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 981                 scurrent = sstart;
 982                 for (count = 0; count < scount; count++) {
 983                         dns_rdata_reset(&srdata);
 984                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 985                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 986                                 break;
 987                 }
 988                 if (count == scount) {
 989                         /*
 990                          * This rdata isn't in the sslab, and thus should be
 991                          * copied to the tslab.
 992                          */
 993                         unsigned int length = mcurrent - mrdatabegin;
 994 #if DNS_RDATASET_FIXED
 995                         offsettable[order] = tcurrent - offsetbase;
 996 #endif
 997                         memcpy(tcurrent, mrdatabegin, length);
 998                         tcurrent += length;
 999                 }
1000                 dns_rdata_reset(&mrdata);
1001         }
1002
1003 #if DNS_RDATASET_FIXED
1004         fillin_offsets(offsetbase, offsettable, mcount);
1005
1006         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
1007 #endif
1008
1009         INSIST(tcurrent == tstart + tlength);
1010
1011         *tslabp = tstart;
1012
1013         return (ISC_R_SUCCESS);
1014 }
1015
1016 isc_boolean_t
1017 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
1018                     unsigned int reservelen)
1019 {
1020         unsigned char *current1, *current2;
1021         unsigned int count1, count2;
1022         unsigned int length1, length2;
1023
1024         current1 = slab1 + reservelen;
1025         count1 = *current1++ * 256;
1026         count1 += *current1++;
1027
1028         current2 = slab2 + reservelen;
1029         count2 = *current2++ * 256;
1030         count2 += *current2++;
1031
1032         if (count1 != count2)
1033                 return (ISC_FALSE);
1034
1035 #if DNS_RDATASET_FIXED
1036         current1 += (4 * count1);
1037         current2 += (4 * count2);
1038 #endif
1039
1040         while (count1 > 0) {
1041                 length1 = *current1++ * 256;
1042                 length1 += *current1++;
1043
1044                 length2 = *current2++ * 256;
1045                 length2 += *current2++;
1046
1047 #if DNS_RDATASET_FIXED
1048                 current1 += 2;
1049                 current2 += 2;
1050 #endif
1051
1052                 if (length1 != length2 ||
1053                     memcmp(current1, current2, length1) != 0)
1054                         return (ISC_FALSE);
1055
1056                 current1 += length1;
1057                 current2 += length1;
1058
1059                 count1--;
1060         }
1061         return (ISC_TRUE);
1062 }
1063
1064 isc_boolean_t
1065 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1066                      unsigned int reservelen, dns_rdataclass_t rdclass,
1067                      dns_rdatatype_t type)
1068 {
1069         unsigned char *current1, *current2;
1070         unsigned int count1, count2;
1071         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1072         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1073
1074         current1 = slab1 + reservelen;
1075         count1 = *current1++ * 256;
1076         count1 += *current1++;
1077
1078         current2 = slab2 + reservelen;
1079         count2 = *current2++ * 256;
1080         count2 += *current2++;
1081
1082         if (count1 != count2)
1083                 return (ISC_FALSE);
1084
1085 #if DNS_RDATASET_FIXED
1086         current1 += (4 * count1);
1087         current2 += (4 * count2);
1088 #endif
1089
1090         while (count1-- > 0) {
1091                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1092                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1093                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1094                         return (ISC_FALSE);
1095                 dns_rdata_reset(&rdata1);
1096                 dns_rdata_reset(&rdata2);
1097         }
1098         return (ISC_TRUE);
1099 }