contrib/bind/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 1.43.128.4.2.2 2010/02/25 10:56:01 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         NULL,
 406         NULL
 407 };
 408
 409 void
 410 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 411                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 412                          dns_rdatatype_t covers, dns_ttl_t ttl,
 413                          dns_rdataset_t *rdataset)
 414 {
 415         REQUIRE(slab != NULL);
 416         REQUIRE(!dns_rdataset_isassociated(rdataset));
 417
 418         rdataset->methods = &rdataset_methods;
 419         rdataset->rdclass = rdclass;
 420         rdataset->type = rdtype;
 421         rdataset->covers = covers;
 422         rdataset->ttl = ttl;
 423         rdataset->trust = 0;
 424         rdataset->private1 = NULL;
 425         rdataset->private2 = NULL;
 426         rdataset->private3 = slab + reservelen;
 427
 428         /*
 429          * Reset iterator state.
 430          */
 431         rdataset->privateuint4 = 0;
 432         rdataset->private5 = NULL;
 433 }
 434
 435 unsigned int
 436 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 437         unsigned int count, length;
 438         unsigned char *current;
 439
 440         REQUIRE(slab != NULL);
 441
 442         current = slab + reservelen;
 443         count = *current++ * 256;
 444         count += *current++;
 445 #if DNS_RDATASET_FIXED
 446         current += (4 * count);
 447 #endif
 448         while (count > 0) {
 449                 count--;
 450                 length = *current++ * 256;
 451                 length += *current++;
 452 #if DNS_RDATASET_FIXED
 453                 current += length + 2;
 454 #else
 455                 current += length;
 456 #endif
 457         }
 458
 459         return ((unsigned int)(current - slab));
 460 }
 461
 462 /*
 463  * Make the dns_rdata_t 'rdata' refer to the slab item
 464  * beginning at '*current', which is part of a slab of type
 465  * 'type' and class 'rdclass', and advance '*current' to
 466  * point to the next item in the slab.
 467  */
 468 static inline void
 469 rdata_from_slab(unsigned char **current,
 470               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 471               dns_rdata_t *rdata)
 472 {
 473         unsigned char *tcurrent = *current;
 474         isc_region_t region;
 475
 476         region.length = *tcurrent++ * 256;
 477         region.length += *tcurrent++;
 478 #if DNS_RDATASET_FIXED
 479         tcurrent += 2;
 480 #endif
 481         region.base = tcurrent;
 482         tcurrent += region.length;
 483         dns_rdata_fromregion(rdata, rdclass, type, &region);
 484         *current = tcurrent;
 485 }
 486
 487 /*
 488  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 489  * contains an rdata identical to 'rdata'.  This does case insensitive
 490  * comparisons per DNSSEC.
 491  */
 492 static inline isc_boolean_t
 493 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 494               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 495               dns_rdata_t *rdata)
 496 {
 497         unsigned int count, i;
 498         unsigned char *current;
 499         dns_rdata_t trdata = DNS_RDATA_INIT;
 500         int n;
 501
 502         current = slab + reservelen;
 503         count = *current++ * 256;
 504         count += *current++;
 505
 506 #if DNS_RDATASET_FIXED
 507         current += (4 * count);
 508 #endif
 509
 510         for (i = 0; i < count; i++) {
 511                 rdata_from_slab(&current, rdclass, type, &trdata);
 512
 513                 n = dns_rdata_compare(&trdata, rdata);
 514                 if (n == 0)
 515                         return (ISC_TRUE);
 516                 if (n > 0)      /* In DNSSEC order. */
 517                         break;
 518                 dns_rdata_reset(&trdata);
 519         }
 520         return (ISC_FALSE);
 521 }
 522
 523 isc_result_t
 524 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 525                     unsigned int reservelen, isc_mem_t *mctx,
 526                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 527                     unsigned int flags, unsigned char **tslabp)
 528 {
 529         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent;
 530         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 531         isc_region_t nregion;
 532         dns_rdata_t ordata = DNS_RDATA_INIT;
 533         dns_rdata_t nrdata = DNS_RDATA_INIT;
 534         isc_boolean_t added_something = ISC_FALSE;
 535         unsigned int oadded = 0;
 536         unsigned int nadded = 0;
 537         unsigned int nncount = 0;
 538 #if DNS_RDATASET_FIXED
 539         unsigned int oncount;
 540         unsigned int norder = 0;
 541         unsigned int oorder = 0;
 542         unsigned char *offsetbase;
 543         unsigned int *offsettable;
 544 #endif
 545
 546         /*
 547          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 548          * or perhaps another merge routine for this purpose.
 549          */
 550
 551         REQUIRE(tslabp != NULL && *tslabp == NULL);
 552         REQUIRE(oslab != NULL && nslab != NULL);
 553
 554         ocurrent = oslab + reservelen;
 555         ocount = *ocurrent++ * 256;
 556         ocount += *ocurrent++;
 557 #if DNS_RDATASET_FIXED
 558         ocurrent += (4 * ocount);
 559 #endif
 560         ostart = ocurrent;
 561         ncurrent = nslab + reservelen;
 562         ncount = *ncurrent++ * 256;
 563         ncount += *ncurrent++;
 564 #if DNS_RDATASET_FIXED
 565         ncurrent += (4 * ncount);
 566 #endif
 567         INSIST(ocount > 0 && ncount > 0);
 568
 569 #if DNS_RDATASET_FIXED
 570         oncount = ncount;
 571 #endif
 572
 573         /*
 574          * Yes, this is inefficient!
 575          */
 576
 577         /*
 578          * Figure out the length of the old slab's data.
 579          */
 580         olength = 0;
 581         for (count = 0; count < ocount; count++) {
 582                 length = *ocurrent++ * 256;
 583                 length += *ocurrent++;
 584 #if DNS_RDATASET_FIXED
 585                 olength += length + 8;
 586                 ocurrent += length + 2;
 587 #else
 588                 olength += length + 2;
 589                 ocurrent += length;
 590 #endif
 591         }
 592
 593         /*
 594          * Start figuring out the target length and count.
 595          */
 596         tlength = reservelen + 2 + olength;
 597         tcount = ocount;
 598
 599         /*
 600          * Add in the length of rdata in the new slab that aren't in
 601          * the old slab.
 602          */
 603         do {
 604                 nregion.length = *ncurrent++ * 256;
 605                 nregion.length += *ncurrent++;
 606 #if DNS_RDATASET_FIXED
 607                 ncurrent += 2;                  /* Skip order. */
 608 #endif
 609                 nregion.base = ncurrent;
 610                 dns_rdata_init(&nrdata);
 611                 dns_rdata_fromregion(&nrdata, rdclass, type, &nregion);
 612                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 613                 {
 614                         /*
 615                          * This rdata isn't in the old slab.
 616                          */
 617 #if DNS_RDATASET_FIXED
 618                         tlength += nregion.length + 8;
 619 #else
 620                         tlength += nregion.length + 2;
 621 #endif
 622                         tcount++;
 623                         nncount++;
 624                         added_something = ISC_TRUE;
 625                 }
 626                 ncurrent += nregion.length;
 627                 ncount--;
 628         } while (ncount > 0);
 629         ncount = nncount;
 630
 631         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 632             (tcount != ncount + ocount))
 633                 return (DNS_R_NOTEXACT);
 634
 635         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 636                 return (DNS_R_UNCHANGED);
 637
 638         /*
 639          * Ensure that singleton types are actually singletons.
 640          */
 641         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 642                 /*
 643                  * We have a singleton type, but there's more than one
 644                  * RR in the rdataset.
 645                  */
 646                 return (DNS_R_SINGLETON);
 647         }
 648
 649         if (tcount > 0xffff)
 650                 return (ISC_R_NOSPACE);
 651
 652         /*
 653          * Copy the reserved area from the new slab.
 654          */
 655         tstart = isc_mem_get(mctx, tlength);
 656         if (tstart == NULL)
 657                 return (ISC_R_NOMEMORY);
 658         memcpy(tstart, nslab, reservelen);
 659         tcurrent = tstart + reservelen;
 660 #if DNS_RDATASET_FIXED
 661         offsetbase = tcurrent;
 662 #endif
 663
 664         /*
 665          * Write the new count.
 666          */
 667         *tcurrent++ = (tcount & 0xff00) >> 8;
 668         *tcurrent++ = (tcount & 0x00ff);
 669
 670 #if DNS_RDATASET_FIXED
 671         /*
 672          * Skip offset table.
 673          */
 674         tcurrent += (tcount * 4);
 675
 676         offsettable = isc_mem_get(mctx,
 677                                   (ocount + oncount) * sizeof(unsigned int));
 678         if (offsettable == NULL) {
 679                 isc_mem_put(mctx, tstart, tlength);
 680                 return (ISC_R_NOMEMORY);
 681         }
 682         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 683 #endif
 684
 685         /*
 686          * Merge the two slabs.
 687          */
 688         ocurrent = ostart;
 689         INSIST(ocount != 0);
 690 #if DNS_RDATASET_FIXED
 691         oorder = ocurrent[2] * 256 + ocurrent[3];
 692         INSIST(oorder < ocount);
 693 #endif
 694         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 695
 696         ncurrent = nslab + reservelen + 2;
 697 #if DNS_RDATASET_FIXED
 698         ncurrent += (4 * oncount);
 699 #endif
 700
 701         if (ncount > 0) {
 702                 do {
 703                         dns_rdata_reset(&nrdata);
 704 #if DNS_RDATASET_FIXED
 705                         norder = ncurrent[2] * 256 + ncurrent[3];
 706
 707                         INSIST(norder < oncount);
 708 #endif
 709                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 710                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 711                                        type, &nrdata));
 712         }
 713
 714         while (oadded < ocount || nadded < ncount) {
 715                 isc_boolean_t fromold;
 716                 if (oadded == ocount)
 717                         fromold = ISC_FALSE;
 718                 else if (nadded == ncount)
 719                         fromold = ISC_TRUE;
 720                 else
 721                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 722                 if (fromold) {
 723 #if DNS_RDATASET_FIXED
 724                         offsettable[oorder] = tcurrent - offsetbase;
 725 #endif
 726                         length = ordata.length;
 727                         *tcurrent++ = (length & 0xff00) >> 8;
 728                         *tcurrent++ = (length & 0x00ff);
 729 #if DNS_RDATASET_FIXED
 730                         tcurrent += 2;  /* fill in later */
 731 #endif
 732                         memcpy(tcurrent, ordata.data, length);
 733                         tcurrent += length;
 734                         oadded++;
 735                         if (oadded < ocount) {
 736                                 dns_rdata_reset(&ordata);
 737 #if DNS_RDATASET_FIXED
 738                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 739                                 INSIST(oorder < ocount);
 740 #endif
 741                                 rdata_from_slab(&ocurrent, rdclass, type,
 742                                                 &ordata);
 743                         }
 744                 } else {
 745 #if DNS_RDATASET_FIXED
 746                         offsettable[ocount + norder] = tcurrent - offsetbase;
 747 #endif
 748                         length = nrdata.length;
 749                         *tcurrent++ = (length & 0xff00) >> 8;
 750                         *tcurrent++ = (length & 0x00ff);
 751 #if DNS_RDATASET_FIXED
 752                         tcurrent += 2;  /* fill in later */
 753 #endif
 754                         memcpy(tcurrent, nrdata.data, length);
 755                         tcurrent += length;
 756                         nadded++;
 757                         if (nadded < ncount) {
 758                                 do {
 759                                         dns_rdata_reset(&nrdata);
 760 #if DNS_RDATASET_FIXED
 761                                         norder = ncurrent[2] * 256 + ncurrent[3];
 762                                         INSIST(norder < oncount);
 763 #endif
 764                                         rdata_from_slab(&ncurrent, rdclass,
 765                                                         type, &nrdata);
 766                                 } while (rdata_in_slab(oslab, reservelen,
 767                                                        rdclass, type,
 768                                                        &nrdata));
 769                         }
 770                 }
 771         }
 772
 773 #if DNS_RDATASET_FIXED
 774         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 775
 776         isc_mem_put(mctx, offsettable,
 777                     (ocount + oncount) * sizeof(unsigned int));
 778 #endif
 779
 780         INSIST(tcurrent == tstart + tlength);
 781
 782         *tslabp = tstart;
 783
 784         return (ISC_R_SUCCESS);
 785 }
 786
 787 isc_result_t
 788 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 789                        unsigned int reservelen, isc_mem_t *mctx,
 790                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 791                        unsigned int flags, unsigned char **tslabp)
 792 {
 793         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 794         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 795         dns_rdata_t srdata = DNS_RDATA_INIT;
 796         dns_rdata_t mrdata = DNS_RDATA_INIT;
 797 #if DNS_RDATASET_FIXED
 798         unsigned char *offsetbase;
 799         unsigned int *offsettable;
 800         unsigned int order;
 801 #endif
 802
 803         REQUIRE(tslabp != NULL && *tslabp == NULL);
 804         REQUIRE(mslab != NULL && sslab != NULL);
 805
 806         mcurrent = mslab + reservelen;
 807         mcount = *mcurrent++ * 256;
 808         mcount += *mcurrent++;
 809         scurrent = sslab + reservelen;
 810         scount = *scurrent++ * 256;
 811         scount += *scurrent++;
 812         INSIST(mcount > 0 && scount > 0);
 813
 814         /*
 815          * Yes, this is inefficient!
 816          */
 817
 818         /*
 819          * Start figuring out the target length and count.
 820          */
 821         tlength = reservelen + 2;
 822         tcount = 0;
 823         rcount = 0;
 824
 825 #if DNS_RDATASET_FIXED
 826         mcurrent += 4 * mcount;
 827         scurrent += 4 * scount;
 828 #endif
 829         sstart = scurrent;
 830
 831         /*
 832          * Add in the length of rdata in the mslab that aren't in
 833          * the sslab.
 834          */
 835         for (i = 0; i < mcount; i++) {
 836                 unsigned char *mrdatabegin = mcurrent;
 837                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 838                 scurrent = sstart;
 839                 for (count = 0; count < scount; count++) {
 840                         dns_rdata_reset(&srdata);
 841                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 842                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 843                                 break;
 844                 }
 845                 if (count == scount) {
 846                         /*
 847                          * This rdata isn't in the sslab, and thus isn't
 848                          * being subtracted.
 849                          */
 850                         tlength += mcurrent - mrdatabegin;
 851                         tcount++;
 852                 } else
 853                         rcount++;
 854                 dns_rdata_reset(&mrdata);
 855         }
 856
 857 #if DNS_RDATASET_FIXED
 858         tlength += (4 * tcount);
 859 #endif
 860
 861         /*
 862          * Check that all the records originally existed.  The numeric
 863          * check only works as rdataslabs do not contain duplicates.
 864          */
 865         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 866                 return (DNS_R_NOTEXACT);
 867
 868         /*
 869          * Don't continue if the new rdataslab would be empty.
 870          */
 871         if (tcount == 0)
 872                 return (DNS_R_NXRRSET);
 873
 874         /*
 875          * If nothing is going to change, we can stop.
 876          */
 877         if (rcount == 0)
 878                 return (DNS_R_UNCHANGED);
 879
 880         /*
 881          * Copy the reserved area from the mslab.
 882          */
 883         tstart = isc_mem_get(mctx, tlength);
 884         if (tstart == NULL)
 885                 return (ISC_R_NOMEMORY);
 886         memcpy(tstart, mslab, reservelen);
 887         tcurrent = tstart + reservelen;
 888 #if DNS_RDATASET_FIXED
 889         offsetbase = tcurrent;
 890
 891         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 892         if (offsettable == NULL) {
 893                 isc_mem_put(mctx, tstart, tlength);
 894                 return (ISC_R_NOMEMORY);
 895         }
 896         memset(offsettable, 0, mcount * sizeof(unsigned int));
 897 #endif
 898
 899         /*
 900          * Write the new count.
 901          */
 902         *tcurrent++ = (tcount & 0xff00) >> 8;
 903         *tcurrent++ = (tcount & 0x00ff);
 904
 905 #if DNS_RDATASET_FIXED
 906         tcurrent += (4 * tcount);
 907 #endif
 908
 909         /*
 910          * Copy the parts of mslab not in sslab.
 911          */
 912         mcurrent = mslab + reservelen;
 913         mcount = *mcurrent++ * 256;
 914         mcount += *mcurrent++;
 915 #if DNS_RDATASET_FIXED
 916         mcurrent += (4 * mcount);
 917 #endif
 918         for (i = 0; i < mcount; i++) {
 919                 unsigned char *mrdatabegin = mcurrent;
 920 #if DNS_RDATASET_FIXED
 921                 order = mcurrent[2] * 256 + mcurrent[3];
 922                 INSIST(order < mcount);
 923 #endif
 924                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 925                 scurrent = sstart;
 926                 for (count = 0; count < scount; count++) {
 927                         dns_rdata_reset(&srdata);
 928                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 929                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 930                                 break;
 931                 }
 932                 if (count == scount) {
 933                         /*
 934                          * This rdata isn't in the sslab, and thus should be
 935                          * copied to the tslab.
 936                          */
 937                         unsigned int length = mcurrent - mrdatabegin;
 938 #if DNS_RDATASET_FIXED
 939                         offsettable[order] = tcurrent - offsetbase;
 940 #endif
 941                         memcpy(tcurrent, mrdatabegin, length);
 942                         tcurrent += length;
 943                 }
 944                 dns_rdata_reset(&mrdata);
 945         }
 946
 947 #if DNS_RDATASET_FIXED
 948         fillin_offsets(offsetbase, offsettable, mcount);
 949
 950         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
 951 #endif
 952
 953         INSIST(tcurrent == tstart + tlength);
 954
 955         *tslabp = tstart;
 956
 957         return (ISC_R_SUCCESS);
 958 }
 959
 960 isc_boolean_t
 961 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
 962                     unsigned int reservelen)
 963 {
 964         unsigned char *current1, *current2;
 965         unsigned int count1, count2;
 966         unsigned int length1, length2;
 967
 968         current1 = slab1 + reservelen;
 969         count1 = *current1++ * 256;
 970         count1 += *current1++;
 971
 972         current2 = slab2 + reservelen;
 973         count2 = *current2++ * 256;
 974         count2 += *current2++;
 975
 976         if (count1 != count2)
 977                 return (ISC_FALSE);
 978
 979 #if DNS_RDATASET_FIXED
 980         current1 += (4 * count1);
 981         current2 += (4 * count2);
 982 #endif
 983
 984         while (count1 > 0) {
 985                 length1 = *current1++ * 256;
 986                 length1 += *current1++;
 987
 988                 length2 = *current2++ * 256;
 989                 length2 += *current2++;
 990
 991 #if DNS_RDATASET_FIXED
 992                 current1 += 2;
 993                 current2 += 2;
 994 #endif
 995
 996                 if (length1 != length2 ||
 997                     memcmp(current1, current2, length1) != 0)
 998                         return (ISC_FALSE);
 999
1000                 current1 += length1;
1001                 current2 += length1;
1002
1003                 count1--;
1004         }
1005         return (ISC_TRUE);
1006 }
1007
1008 isc_boolean_t
1009 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1010                      unsigned int reservelen, dns_rdataclass_t rdclass,
1011                      dns_rdatatype_t type)
1012 {
1013         unsigned char *current1, *current2;
1014         unsigned int count1, count2;
1015         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1016         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1017
1018         current1 = slab1 + reservelen;
1019         count1 = *current1++ * 256;
1020         count1 += *current1++;
1021
1022         current2 = slab2 + reservelen;
1023         count2 = *current2++ * 256;
1024         count2 += *current2++;
1025
1026         if (count1 != count2)
1027                 return (ISC_FALSE);
1028
1029 #if DNS_RDATASET_FIXED
1030         current1 += (4 * count1);
1031         current2 += (4 * count2);
1032 #endif
1033
1034         while (count1-- > 0) {
1035                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1036                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1037                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1038                         return (ISC_FALSE);
1039                 dns_rdata_reset(&rdata1);
1040                 dns_rdata_reset(&rdata2);
1041         }
1042         return (ISC_TRUE);
1043 }