contrib/bind-9.5.2/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2009  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 1.43.128.4 2009/01/19 23:47:02 tbox 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  *              data            (data length bytes)
  47  *
  48  * If DNS_RDATASET_FIXED is defined to be zero (0) the format of a
  49  * rdataslab is as follows:
  50  *
  51  *      header          (reservelen bytes)
  52  *      record count    (2 bytes)
  53  *      data records
  54  *              data length     (2 bytes)
  55  *              data            (data length bytes)
  56  *
  57  * Offsets are from the end of the header.
  58  *
  59  * Load order traversal is performed by walking the offset table to find
  60  * the start of the record (DNS_RDATASET_FIXED = 1).
  61  *
  62  * DNSSEC order traversal is performed by walking the data records.
  63  *
  64  * The order is stored with record to allow for efficient reconstruction
  65  * of the offset table following a merge or subtraction.
  66  *
  67  * The iterator methods here currently only support DNSSEC order iteration.
  68  *
  69  * The iterator methods in rbtdb support both load order and DNSSEC order
  70  * iteration.
  71  *
  72  * WARNING:
  73  *      rbtdb.c directly interacts with the slab's raw structures.  If the
  74  *      structure changes then rbtdb.c also needs to be updated to reflect
  75  *      the changes.  See the areas tagged with "RDATASLAB".
  76  */
  77
  78 struct xrdata {
  79         dns_rdata_t     rdata;
  80         unsigned int    order;
  81 };
  82
  83 /*% Note: the "const void *" are just to make qsort happy.  */
  84 static int
  85 compare_rdata(const void *p1, const void *p2) {
  86         const struct xrdata *x1 = p1;
  87         const struct xrdata *x2 = p2;
  88         return (dns_rdata_compare(&x1->rdata, &x2->rdata));
  89 }
  90
  91 #if DNS_RDATASET_FIXED
  92 static void
  93 fillin_offsets(unsigned char *offsetbase, unsigned int *offsettable,
  94                unsigned length)
  95 {
  96         unsigned int i, j;
  97         unsigned char *raw;
  98
  99         for (i = 0, j = 0; i < length; i++) {
 100
 101                 if (offsettable[i] == 0)
 102                         continue;
 103
 104                 /*
 105                  * Fill in offset table.
 106                  */
 107                 raw = &offsetbase[j*4 + 2];
 108                 *raw++ = (offsettable[i] & 0xff000000) >> 24;
 109                 *raw++ = (offsettable[i] & 0xff0000) >> 16;
 110                 *raw++ = (offsettable[i] & 0xff00) >> 8;
 111                 *raw = offsettable[i] & 0xff;
 112
 113                 /*
 114                  * Fill in table index.
 115                  */
 116                 raw = offsetbase + offsettable[i] + 2;
 117                 *raw++ = (j & 0xff00) >> 8;
 118                 *raw = j++ & 0xff;
 119         }
 120 }
 121 #endif
 122
 123 isc_result_t
 124 dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
 125                            isc_region_t *region, unsigned int reservelen)
 126 {
 127         struct xrdata  *x;
 128         unsigned char  *rawbuf;
 129 #if DNS_RDATASET_FIXED
 130         unsigned char  *offsetbase;
 131 #endif
 132         unsigned int    buflen;
 133         isc_result_t    result;
 134         unsigned int    nitems;
 135         unsigned int    nalloc;
 136         unsigned int    i;
 137 #if DNS_RDATASET_FIXED
 138         unsigned int   *offsettable;
 139 #endif
 140
 141         buflen = reservelen + 2;
 142
 143         nalloc = dns_rdataset_count(rdataset);
 144         nitems = nalloc;
 145         if (nitems == 0)
 146                 return (ISC_R_FAILURE);
 147
 148         if (nalloc > 0xffff)
 149                 return (ISC_R_NOSPACE);
 150
 151         x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 152         if (x == NULL)
 153                 return (ISC_R_NOMEMORY);
 154
 155         /*
 156          * Save all of the rdata members into an array.
 157          */
 158         result = dns_rdataset_first(rdataset);
 159         if (result != ISC_R_SUCCESS)
 160                 goto free_rdatas;
 161         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 162                 INSIST(result == ISC_R_SUCCESS);
 163                 dns_rdata_init(&x[i].rdata);
 164                 dns_rdataset_current(rdataset, &x[i].rdata);
 165 #if DNS_RDATASET_FIXED
 166                 x[i].order = i;
 167 #endif
 168                 result = dns_rdataset_next(rdataset);
 169         }
 170         if (result != ISC_R_NOMORE)
 171                 goto free_rdatas;
 172         if (i != nalloc) {
 173                 /*
 174                  * Somehow we iterated over fewer rdatas than
 175                  * dns_rdataset_count() said there were!
 176                  */
 177                 result = ISC_R_FAILURE;
 178                 goto free_rdatas;
 179         }
 180
 181         /*
 182          * Put into DNSSEC order.
 183          */
 184         qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 185
 186         /*
 187          * Remove duplicates and compute the total storage required.
 188          *
 189          * If an rdata is not a duplicate, accumulate the storage size
 190          * required for the rdata.  We do not store the class, type, etc,
 191          * just the rdata, so our overhead is 2 bytes for the number of
 192          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 193          * and then the rdata itself.
 194          */
 195         for (i = 1; i < nalloc; i++) {
 196                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 197                         x[i-1].rdata.data = NULL;
 198                         x[i-1].rdata.length = 0;
 199 #if DNS_RDATASET_FIXED
 200                         /*
 201                          * Preserve the least order so A, B, A -> A, B
 202                          * after duplicate removal.
 203                          */
 204                         if (x[i-1].order < x[i].order)
 205                                 x[i].order = x[i-1].order;
 206 #endif
 207                         nitems--;
 208                 } else
 209 #if DNS_RDATASET_FIXED
 210                         buflen += (8 + x[i-1].rdata.length);
 211 #else
 212                         buflen += (2 + x[i-1].rdata.length);
 213 #endif
 214         }
 215         /*
 216          * Don't forget the last item!
 217          */
 218 #if DNS_RDATASET_FIXED
 219         buflen += (8 + x[i-1].rdata.length);
 220 #else
 221         buflen += (2 + x[i-1].rdata.length);
 222 #endif
 223
 224         /*
 225          * Ensure that singleton types are actually singletons.
 226          */
 227         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 228                 /*
 229                  * We have a singleton type, but there's more than one
 230                  * RR in the rdataset.
 231                  */
 232                 result = DNS_R_SINGLETON;
 233                 goto free_rdatas;
 234         }
 235
 236         /*
 237          * Allocate the memory, set up a buffer, start copying in
 238          * data.
 239          */
 240         rawbuf = isc_mem_get(mctx, buflen);
 241         if (rawbuf == NULL) {
 242                 result = ISC_R_NOMEMORY;
 243                 goto free_rdatas;
 244         }
 245
 246 #if DNS_RDATASET_FIXED
 247         /* Allocate temporary offset table. */
 248         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 249         if (offsettable == NULL) {
 250                 isc_mem_put(mctx, rawbuf, buflen);
 251                 result = ISC_R_NOMEMORY;
 252                 goto free_rdatas;
 253         }
 254         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 255 #endif
 256
 257         region->base = rawbuf;
 258         region->length = buflen;
 259
 260         rawbuf += reservelen;
 261 #if DNS_RDATASET_FIXED
 262         offsetbase = rawbuf;
 263 #endif
 264
 265         *rawbuf++ = (nitems & 0xff00) >> 8;
 266         *rawbuf++ = (nitems & 0x00ff);
 267
 268 #if DNS_RDATASET_FIXED
 269         /* Skip load order table.  Filled in later. */
 270         rawbuf += nitems * 4;
 271 #endif
 272
 273         for (i = 0; i < nalloc; i++) {
 274                 if (x[i].rdata.data == NULL)
 275                         continue;
 276 #if DNS_RDATASET_FIXED
 277                 offsettable[x[i].order] = rawbuf - offsetbase;
 278 #endif
 279                 *rawbuf++ = (x[i].rdata.length & 0xff00) >> 8;
 280                 *rawbuf++ = (x[i].rdata.length & 0x00ff);
 281 #if DNS_RDATASET_FIXED
 282                 rawbuf += 2;    /* filled in later */
 283 #endif
 284                 memcpy(rawbuf, x[i].rdata.data, x[i].rdata.length);
 285                 rawbuf += x[i].rdata.length;
 286         }
 287
 288 #if DNS_RDATASET_FIXED
 289         fillin_offsets(offsetbase, offsettable, nalloc);
 290         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 291 #endif
 292
 293         result = ISC_R_SUCCESS;
 294
 295  free_rdatas:
 296         isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 297         return (result);
 298 }
 299
 300 static void
 301 rdataset_disassociate(dns_rdataset_t *rdataset) {
 302         UNUSED(rdataset);
 303 }
 304
 305 static isc_result_t
 306 rdataset_first(dns_rdataset_t *rdataset) {
 307         unsigned char *raw = rdataset->private3;
 308         unsigned int count;
 309
 310         count = raw[0] * 256 + raw[1];
 311         if (count == 0) {
 312                 rdataset->private5 = NULL;
 313                 return (ISC_R_NOMORE);
 314         }
 315 #if DNS_RDATASET_FIXED
 316         raw += 2 + (4 * count);
 317 #else
 318         raw += 2;
 319 #endif
 320         /*
 321          * The privateuint4 field is the number of rdata beyond the cursor
 322          * position, so we decrement the total count by one before storing
 323          * it.
 324          */
 325         count--;
 326         rdataset->privateuint4 = count;
 327         rdataset->private5 = raw;
 328
 329         return (ISC_R_SUCCESS);
 330 }
 331
 332 static isc_result_t
 333 rdataset_next(dns_rdataset_t *rdataset) {
 334         unsigned int count;
 335         unsigned int length;
 336         unsigned char *raw;
 337
 338         count = rdataset->privateuint4;
 339         if (count == 0)
 340                 return (ISC_R_NOMORE);
 341         count--;
 342         rdataset->privateuint4 = count;
 343         raw = rdataset->private5;
 344         length = raw[0] * 256 + raw[1];
 345 #if DNS_RDATASET_FIXED
 346         raw += length + 4;
 347 #else
 348         raw += length + 2;
 349 #endif
 350         rdataset->private5 = raw;
 351
 352         return (ISC_R_SUCCESS);
 353 }
 354
 355 static void
 356 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 357         unsigned char *raw = rdataset->private5;
 358         isc_region_t r;
 359
 360         REQUIRE(raw != NULL);
 361
 362         r.length = raw[0] * 256 + raw[1];
 363 #if DNS_RDATASET_FIXED
 364         raw += 4;
 365 #else
 366         raw += 2;
 367 #endif
 368         r.base = raw;
 369         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 370 }
 371
 372 static void
 373 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 374         *target = *source;
 375
 376         /*
 377          * Reset iterator state.
 378          */
 379         target->privateuint4 = 0;
 380         target->private5 = NULL;
 381 }
 382
 383 static unsigned int
 384 rdataset_count(dns_rdataset_t *rdataset) {
 385         unsigned char *raw = rdataset->private3;
 386         unsigned int count;
 387
 388         count = raw[0] * 256 + raw[1];
 389
 390         return (count);
 391 }
 392
 393 static dns_rdatasetmethods_t rdataset_methods = {
 394         rdataset_disassociate,
 395         rdataset_first,
 396         rdataset_next,
 397         rdataset_current,
 398         rdataset_clone,
 399         rdataset_count,
 400         NULL,
 401         NULL,
 402         NULL,
 403         NULL,
 404         NULL
 405 };
 406
 407 void
 408 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 409                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 410                          dns_rdatatype_t covers, dns_ttl_t ttl,
 411                          dns_rdataset_t *rdataset)
 412 {
 413         REQUIRE(slab != NULL);
 414         REQUIRE(!dns_rdataset_isassociated(rdataset));
 415
 416         rdataset->methods = &rdataset_methods;
 417         rdataset->rdclass = rdclass;
 418         rdataset->type = rdtype;
 419         rdataset->covers = covers;
 420         rdataset->ttl = ttl;
 421         rdataset->trust = 0;
 422         rdataset->private1 = NULL;
 423         rdataset->private2 = NULL;
 424         rdataset->private3 = slab + reservelen;
 425
 426         /*
 427          * Reset iterator state.
 428          */
 429         rdataset->privateuint4 = 0;
 430         rdataset->private5 = NULL;
 431 }
 432
 433 unsigned int
 434 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 435         unsigned int count, length;
 436         unsigned char *current;
 437
 438         REQUIRE(slab != NULL);
 439
 440         current = slab + reservelen;
 441         count = *current++ * 256;
 442         count += *current++;
 443 #if DNS_RDATASET_FIXED
 444         current += (4 * count);
 445 #endif
 446         while (count > 0) {
 447                 count--;
 448                 length = *current++ * 256;
 449                 length += *current++;
 450 #if DNS_RDATASET_FIXED
 451                 current += length + 2;
 452 #else
 453                 current += length;
 454 #endif
 455         }
 456
 457         return ((unsigned int)(current - slab));
 458 }
 459
 460 /*
 461  * Make the dns_rdata_t 'rdata' refer to the slab item
 462  * beginning at '*current', which is part of a slab of type
 463  * 'type' and class 'rdclass', and advance '*current' to
 464  * point to the next item in the slab.
 465  */
 466 static inline void
 467 rdata_from_slab(unsigned char **current,
 468               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 469               dns_rdata_t *rdata)
 470 {
 471         unsigned char *tcurrent = *current;
 472         isc_region_t region;
 473
 474         region.length = *tcurrent++ * 256;
 475         region.length += *tcurrent++;
 476 #if DNS_RDATASET_FIXED
 477         tcurrent += 2;
 478 #endif
 479         region.base = tcurrent;
 480         tcurrent += region.length;
 481         dns_rdata_fromregion(rdata, rdclass, type, &region);
 482         *current = tcurrent;
 483 }
 484
 485 /*
 486  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 487  * contains an rdata identical to 'rdata'.  This does case insensitive
 488  * comparisons per DNSSEC.
 489  */
 490 static inline isc_boolean_t
 491 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 492               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 493               dns_rdata_t *rdata)
 494 {
 495         unsigned int count, i;
 496         unsigned char *current;
 497         dns_rdata_t trdata = DNS_RDATA_INIT;
 498         int n;
 499
 500         current = slab + reservelen;
 501         count = *current++ * 256;
 502         count += *current++;
 503
 504 #if DNS_RDATASET_FIXED
 505         current += (4 * count);
 506 #endif
 507
 508         for (i = 0; i < count; i++) {
 509                 rdata_from_slab(&current, rdclass, type, &trdata);
 510
 511                 n = dns_rdata_compare(&trdata, rdata);
 512                 if (n == 0)
 513                         return (ISC_TRUE);
 514                 if (n > 0)      /* In DNSSEC order. */
 515                         break;
 516                 dns_rdata_reset(&trdata);
 517         }
 518         return (ISC_FALSE);
 519 }
 520
 521 isc_result_t
 522 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 523                     unsigned int reservelen, isc_mem_t *mctx,
 524                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 525                     unsigned int flags, unsigned char **tslabp)
 526 {
 527         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent;
 528         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 529         isc_region_t nregion;
 530         dns_rdata_t ordata = DNS_RDATA_INIT;
 531         dns_rdata_t nrdata = DNS_RDATA_INIT;
 532         isc_boolean_t added_something = ISC_FALSE;
 533         unsigned int oadded = 0;
 534         unsigned int nadded = 0;
 535         unsigned int nncount = 0;
 536 #if DNS_RDATASET_FIXED
 537         unsigned int oncount;
 538         unsigned int norder = 0;
 539         unsigned int oorder = 0;
 540         unsigned char *offsetbase;
 541         unsigned int *offsettable;
 542 #endif
 543
 544         /*
 545          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 546          * or perhaps another merge routine for this purpose.
 547          */
 548
 549         REQUIRE(tslabp != NULL && *tslabp == NULL);
 550         REQUIRE(oslab != NULL && nslab != NULL);
 551
 552         ocurrent = oslab + reservelen;
 553         ocount = *ocurrent++ * 256;
 554         ocount += *ocurrent++;
 555 #if DNS_RDATASET_FIXED
 556         ocurrent += (4 * ocount);
 557 #endif
 558         ostart = ocurrent;
 559         ncurrent = nslab + reservelen;
 560         ncount = *ncurrent++ * 256;
 561         ncount += *ncurrent++;
 562 #if DNS_RDATASET_FIXED
 563         ncurrent += (4 * ncount);
 564 #endif
 565         INSIST(ocount > 0 && ncount > 0);
 566
 567 #if DNS_RDATASET_FIXED
 568         oncount = ncount;
 569 #endif
 570
 571         /*
 572          * Yes, this is inefficient!
 573          */
 574
 575         /*
 576          * Figure out the length of the old slab's data.
 577          */
 578         olength = 0;
 579         for (count = 0; count < ocount; count++) {
 580                 length = *ocurrent++ * 256;
 581                 length += *ocurrent++;
 582 #if DNS_RDATASET_FIXED
 583                 olength += length + 8;
 584                 ocurrent += length + 2;
 585 #else
 586                 olength += length + 2;
 587                 ocurrent += length;
 588 #endif
 589         }
 590
 591         /*
 592          * Start figuring out the target length and count.
 593          */
 594         tlength = reservelen + 2 + olength;
 595         tcount = ocount;
 596
 597         /*
 598          * Add in the length of rdata in the new slab that aren't in
 599          * the old slab.
 600          */
 601         do {
 602                 nregion.length = *ncurrent++ * 256;
 603                 nregion.length += *ncurrent++;
 604 #if DNS_RDATASET_FIXED
 605                 ncurrent += 2;                  /* Skip order. */
 606 #endif
 607                 nregion.base = ncurrent;
 608                 dns_rdata_init(&nrdata);
 609                 dns_rdata_fromregion(&nrdata, rdclass, type, &nregion);
 610                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 611                 {
 612                         /*
 613                          * This rdata isn't in the old slab.
 614                          */
 615 #if DNS_RDATASET_FIXED
 616                         tlength += nregion.length + 8;
 617 #else
 618                         tlength += nregion.length + 2;
 619 #endif
 620                         tcount++;
 621                         nncount++;
 622                         added_something = ISC_TRUE;
 623                 }
 624                 ncurrent += nregion.length;
 625                 ncount--;
 626         } while (ncount > 0);
 627         ncount = nncount;
 628
 629         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 630             (tcount != ncount + ocount))
 631                 return (DNS_R_NOTEXACT);
 632
 633         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 634                 return (DNS_R_UNCHANGED);
 635
 636         /*
 637          * Ensure that singleton types are actually singletons.
 638          */
 639         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 640                 /*
 641                  * We have a singleton type, but there's more than one
 642                  * RR in the rdataset.
 643                  */
 644                 return (DNS_R_SINGLETON);
 645         }
 646
 647         if (tcount > 0xffff)
 648                 return (ISC_R_NOSPACE);
 649
 650         /*
 651          * Copy the reserved area from the new slab.
 652          */
 653         tstart = isc_mem_get(mctx, tlength);
 654         if (tstart == NULL)
 655                 return (ISC_R_NOMEMORY);
 656         memcpy(tstart, nslab, reservelen);
 657         tcurrent = tstart + reservelen;
 658 #if DNS_RDATASET_FIXED
 659         offsetbase = tcurrent;
 660 #endif
 661
 662         /*
 663          * Write the new count.
 664          */
 665         *tcurrent++ = (tcount & 0xff00) >> 8;
 666         *tcurrent++ = (tcount & 0x00ff);
 667
 668 #if DNS_RDATASET_FIXED
 669         /*
 670          * Skip offset table.
 671          */
 672         tcurrent += (tcount * 4);
 673
 674         offsettable = isc_mem_get(mctx,
 675                                   (ocount + oncount) * sizeof(unsigned int));
 676         if (offsettable == NULL) {
 677                 isc_mem_put(mctx, tstart, tlength);
 678                 return (ISC_R_NOMEMORY);
 679         }
 680         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 681 #endif
 682
 683         /*
 684          * Merge the two slabs.
 685          */
 686         ocurrent = ostart;
 687         INSIST(ocount != 0);
 688 #if DNS_RDATASET_FIXED
 689         oorder = ocurrent[2] * 256 + ocurrent[3];
 690         INSIST(oorder < ocount);
 691 #endif
 692         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 693
 694         ncurrent = nslab + reservelen + 2;
 695 #if DNS_RDATASET_FIXED
 696         ncurrent += (4 * oncount);
 697 #endif
 698
 699         if (ncount > 0) {
 700                 do {
 701                         dns_rdata_reset(&nrdata);
 702 #if DNS_RDATASET_FIXED
 703                         norder = ncurrent[2] * 256 + ncurrent[3];
 704
 705                         INSIST(norder < oncount);
 706 #endif
 707                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 708                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 709                                        type, &nrdata));
 710         }
 711
 712         while (oadded < ocount || nadded < ncount) {
 713                 isc_boolean_t fromold;
 714                 if (oadded == ocount)
 715                         fromold = ISC_FALSE;
 716                 else if (nadded == ncount)
 717                         fromold = ISC_TRUE;
 718                 else
 719                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 720                 if (fromold) {
 721 #if DNS_RDATASET_FIXED
 722                         offsettable[oorder] = tcurrent - offsetbase;
 723 #endif
 724                         length = ordata.length;
 725                         *tcurrent++ = (length & 0xff00) >> 8;
 726                         *tcurrent++ = (length & 0x00ff);
 727 #if DNS_RDATASET_FIXED
 728                         tcurrent += 2;  /* fill in later */
 729 #endif
 730                         memcpy(tcurrent, ordata.data, length);
 731                         tcurrent += length;
 732                         oadded++;
 733                         if (oadded < ocount) {
 734                                 dns_rdata_reset(&ordata);
 735 #if DNS_RDATASET_FIXED
 736                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 737                                 INSIST(oorder < ocount);
 738 #endif
 739                                 rdata_from_slab(&ocurrent, rdclass, type,
 740                                                 &ordata);
 741                         }
 742                 } else {
 743 #if DNS_RDATASET_FIXED
 744                         offsettable[ocount + norder] = tcurrent - offsetbase;
 745 #endif
 746                         length = nrdata.length;
 747                         *tcurrent++ = (length & 0xff00) >> 8;
 748                         *tcurrent++ = (length & 0x00ff);
 749 #if DNS_RDATASET_FIXED
 750                         tcurrent += 2;  /* fill in later */
 751 #endif
 752                         memcpy(tcurrent, nrdata.data, length);
 753                         tcurrent += length;
 754                         nadded++;
 755                         if (nadded < ncount) {
 756                                 do {
 757                                         dns_rdata_reset(&nrdata);
 758 #if DNS_RDATASET_FIXED
 759                                         norder = ncurrent[2] * 256 + ncurrent[3];
 760                                         INSIST(norder < oncount);
 761 #endif
 762                                         rdata_from_slab(&ncurrent, rdclass,
 763                                                         type, &nrdata);
 764                                 } while (rdata_in_slab(oslab, reservelen,
 765                                                        rdclass, type,
 766                                                        &nrdata));
 767                         }
 768                 }
 769         }
 770
 771 #if DNS_RDATASET_FIXED
 772         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 773
 774         isc_mem_put(mctx, offsettable,
 775                     (ocount + oncount) * sizeof(unsigned int));
 776 #endif
 777
 778         INSIST(tcurrent == tstart + tlength);
 779
 780         *tslabp = tstart;
 781
 782         return (ISC_R_SUCCESS);
 783 }
 784
 785 isc_result_t
 786 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 787                        unsigned int reservelen, isc_mem_t *mctx,
 788                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 789                        unsigned int flags, unsigned char **tslabp)
 790 {
 791         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 792         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 793         dns_rdata_t srdata = DNS_RDATA_INIT;
 794         dns_rdata_t mrdata = DNS_RDATA_INIT;
 795 #if DNS_RDATASET_FIXED
 796         unsigned char *offsetbase;
 797         unsigned int *offsettable;
 798         unsigned int order;
 799 #endif
 800
 801         REQUIRE(tslabp != NULL && *tslabp == NULL);
 802         REQUIRE(mslab != NULL && sslab != NULL);
 803
 804         mcurrent = mslab + reservelen;
 805         mcount = *mcurrent++ * 256;
 806         mcount += *mcurrent++;
 807         scurrent = sslab + reservelen;
 808         scount = *scurrent++ * 256;
 809         scount += *scurrent++;
 810         INSIST(mcount > 0 && scount > 0);
 811
 812         /*
 813          * Yes, this is inefficient!
 814          */
 815
 816         /*
 817          * Start figuring out the target length and count.
 818          */
 819         tlength = reservelen + 2;
 820         tcount = 0;
 821         rcount = 0;
 822
 823 #if DNS_RDATASET_FIXED
 824         mcurrent += 4 * mcount;
 825         scurrent += 4 * scount;
 826 #endif
 827         sstart = scurrent;
 828
 829         /*
 830          * Add in the length of rdata in the mslab that aren't in
 831          * the sslab.
 832          */
 833         for (i = 0; i < mcount; i++) {
 834                 unsigned char *mrdatabegin = mcurrent;
 835                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 836                 scurrent = sstart;
 837                 for (count = 0; count < scount; count++) {
 838                         dns_rdata_reset(&srdata);
 839                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 840                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 841                                 break;
 842                 }
 843                 if (count == scount) {
 844                         /*
 845                          * This rdata isn't in the sslab, and thus isn't
 846                          * being subtracted.
 847                          */
 848                         tlength += mcurrent - mrdatabegin;
 849                         tcount++;
 850                 } else
 851                         rcount++;
 852                 dns_rdata_reset(&mrdata);
 853         }
 854
 855 #if DNS_RDATASET_FIXED
 856         tlength += (4 * tcount);
 857 #endif
 858
 859         /*
 860          * Check that all the records originally existed.  The numeric
 861          * check only works as rdataslabs do not contain duplicates.
 862          */
 863         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 864                 return (DNS_R_NOTEXACT);
 865
 866         /*
 867          * Don't continue if the new rdataslab would be empty.
 868          */
 869         if (tcount == 0)
 870                 return (DNS_R_NXRRSET);
 871
 872         /*
 873          * If nothing is going to change, we can stop.
 874          */
 875         if (rcount == 0)
 876                 return (DNS_R_UNCHANGED);
 877
 878         /*
 879          * Copy the reserved area from the mslab.
 880          */
 881         tstart = isc_mem_get(mctx, tlength);
 882         if (tstart == NULL)
 883                 return (ISC_R_NOMEMORY);
 884         memcpy(tstart, mslab, reservelen);
 885         tcurrent = tstart + reservelen;
 886 #if DNS_RDATASET_FIXED
 887         offsetbase = tcurrent;
 888
 889         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 890         if (offsettable == NULL) {
 891                 isc_mem_put(mctx, tstart, tlength);
 892                 return (ISC_R_NOMEMORY);
 893         }
 894         memset(offsettable, 0, mcount * sizeof(unsigned int));
 895 #endif
 896
 897         /*
 898          * Write the new count.
 899          */
 900         *tcurrent++ = (tcount & 0xff00) >> 8;
 901         *tcurrent++ = (tcount & 0x00ff);
 902
 903 #if DNS_RDATASET_FIXED
 904         tcurrent += (4 * tcount);
 905 #endif
 906
 907         /*
 908          * Copy the parts of mslab not in sslab.
 909          */
 910         mcurrent = mslab + reservelen;
 911         mcount = *mcurrent++ * 256;
 912         mcount += *mcurrent++;
 913 #if DNS_RDATASET_FIXED
 914         mcurrent += (4 * mcount);
 915 #endif
 916         for (i = 0; i < mcount; i++) {
 917                 unsigned char *mrdatabegin = mcurrent;
 918 #if DNS_RDATASET_FIXED
 919                 order = mcurrent[2] * 256 + mcurrent[3];
 920                 INSIST(order < mcount);
 921 #endif
 922                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 923                 scurrent = sstart;
 924                 for (count = 0; count < scount; count++) {
 925                         dns_rdata_reset(&srdata);
 926                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 927                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 928                                 break;
 929                 }
 930                 if (count == scount) {
 931                         /*
 932                          * This rdata isn't in the sslab, and thus should be
 933                          * copied to the tslab.
 934                          */
 935                         unsigned int length = mcurrent - mrdatabegin;
 936 #if DNS_RDATASET_FIXED
 937                         offsettable[order] = tcurrent - offsetbase;
 938 #endif
 939                         memcpy(tcurrent, mrdatabegin, length);
 940                         tcurrent += length;
 941                 }
 942                 dns_rdata_reset(&mrdata);
 943         }
 944
 945 #if DNS_RDATASET_FIXED
 946         fillin_offsets(offsetbase, offsettable, mcount);
 947
 948         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
 949 #endif
 950
 951         INSIST(tcurrent == tstart + tlength);
 952
 953         *tslabp = tstart;
 954
 955         return (ISC_R_SUCCESS);
 956 }
 957
 958 isc_boolean_t
 959 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
 960                     unsigned int reservelen)
 961 {
 962         unsigned char *current1, *current2;
 963         unsigned int count1, count2;
 964         unsigned int length1, length2;
 965
 966         current1 = slab1 + reservelen;
 967         count1 = *current1++ * 256;
 968         count1 += *current1++;
 969
 970         current2 = slab2 + reservelen;
 971         count2 = *current2++ * 256;
 972         count2 += *current2++;
 973
 974         if (count1 != count2)
 975                 return (ISC_FALSE);
 976
 977 #if DNS_RDATASET_FIXED
 978         current1 += (4 * count1);
 979         current2 += (4 * count2);
 980 #endif
 981
 982         while (count1 > 0) {
 983                 length1 = *current1++ * 256;
 984                 length1 += *current1++;
 985
 986                 length2 = *current2++ * 256;
 987                 length2 += *current2++;
 988
 989 #if DNS_RDATASET_FIXED
 990                 current1 += 2;
 991                 current2 += 2;
 992 #endif
 993
 994                 if (length1 != length2 ||
 995                     memcmp(current1, current2, length1) != 0)
 996                         return (ISC_FALSE);
 997
 998                 current1 += length1;
 999                 current2 += length1;
1000
1001                 count1--;
1002         }
1003         return (ISC_TRUE);
1004 }
1005
1006 isc_boolean_t
1007 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1008                      unsigned int reservelen, dns_rdataclass_t rdclass,
1009                      dns_rdatatype_t type)
1010 {
1011         unsigned char *current1, *current2;
1012         unsigned int count1, count2;
1013         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1014         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1015
1016         current1 = slab1 + reservelen;
1017         count1 = *current1++ * 256;
1018         count1 += *current1++;
1019
1020         current2 = slab2 + reservelen;
1021         count2 = *current2++ * 256;
1022         count2 += *current2++;
1023
1024         if (count1 != count2)
1025                 return (ISC_FALSE);
1026
1027 #if DNS_RDATASET_FIXED
1028         current1 += (4 * count1);
1029         current2 += (4 * count2);
1030 #endif
1031
1032         while (count1-- > 0) {
1033                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1034                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1035                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1036                         return (ISC_FALSE);
1037                 dns_rdata_reset(&rdata1);
1038                 dns_rdata_reset(&rdata2);
1039         }
1040         return (ISC_TRUE);
1041 }