contrib/bind9/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2011  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 1.52.148.2 2011-02-28 01:20:02 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  *              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         struct xrdata  *x;
 129         unsigned char  *rawbuf;
 130 #if DNS_RDATASET_FIXED
 131         unsigned char  *offsetbase;
 132 #endif
 133         unsigned int    buflen;
 134         isc_result_t    result;
 135         unsigned int    nitems;
 136         unsigned int    nalloc;
 137         unsigned int    i;
 138 #if DNS_RDATASET_FIXED
 139         unsigned int   *offsettable;
 140 #endif
 141         unsigned int    length;
 142
 143         buflen = reservelen + 2;
 144
 145         nalloc = dns_rdataset_count(rdataset);
 146         nitems = nalloc;
 147         if (nitems == 0 && rdataset->type != 0)
 148                 return (ISC_R_FAILURE);
 149
 150         if (nalloc > 0xffff)
 151                 return (ISC_R_NOSPACE);
 152
 153
 154         if (nalloc != 0) {
 155                 x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 156                 if (x == NULL)
 157                         return (ISC_R_NOMEMORY);
 158         } else
 159                 x = NULL;
 160
 161         /*
 162          * Save all of the rdata members into an array.
 163          */
 164         result = dns_rdataset_first(rdataset);
 165         if (result != ISC_R_SUCCESS && result != ISC_R_NOMORE)
 166                 goto free_rdatas;
 167         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 168                 INSIST(result == ISC_R_SUCCESS);
 169                 dns_rdata_init(&x[i].rdata);
 170                 dns_rdataset_current(rdataset, &x[i].rdata);
 171 #if DNS_RDATASET_FIXED
 172                 x[i].order = i;
 173 #endif
 174                 result = dns_rdataset_next(rdataset);
 175         }
 176         if (result != ISC_R_NOMORE)
 177                 goto free_rdatas;
 178         if (i != nalloc) {
 179                 /*
 180                  * Somehow we iterated over fewer rdatas than
 181                  * dns_rdataset_count() said there were!
 182                  */
 183                 result = ISC_R_FAILURE;
 184                 goto free_rdatas;
 185         }
 186
 187         /*
 188          * Put into DNSSEC order.
 189          */
 190         qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 191
 192         /*
 193          * Remove duplicates and compute the total storage required.
 194          *
 195          * If an rdata is not a duplicate, accumulate the storage size
 196          * required for the rdata.  We do not store the class, type, etc,
 197          * just the rdata, so our overhead is 2 bytes for the number of
 198          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 199          * and then the rdata itself.
 200          */
 201         for (i = 1; i < nalloc; i++) {
 202                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 203                         x[i-1].rdata.data = NULL;
 204                         x[i-1].rdata.length = 0;
 205 #if DNS_RDATASET_FIXED
 206                         /*
 207                          * Preserve the least order so A, B, A -> A, B
 208                          * after duplicate removal.
 209                          */
 210                         if (x[i-1].order < x[i].order)
 211                                 x[i].order = x[i-1].order;
 212 #endif
 213                         nitems--;
 214                 } else {
 215 #if DNS_RDATASET_FIXED
 216                         buflen += (8 + x[i-1].rdata.length);
 217 #else
 218                         buflen += (2 + x[i-1].rdata.length);
 219 #endif
 220                         /*
 221                          * Provide space to store the per RR meta data.
 222                          */
 223                         if (rdataset->type == dns_rdatatype_rrsig)
 224                                 buflen++;
 225                 }
 226         }
 227         /*
 228          * Don't forget the last item!
 229          */
 230         if (nalloc != 0) {
 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
 238         /*
 239          * Provide space to store the per RR meta data.
 240          */
 241         if (rdataset->type == dns_rdatatype_rrsig)
 242                 buflen++;
 243
 244         /*
 245          * Ensure that singleton types are actually singletons.
 246          */
 247         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 248                 /*
 249                  * We have a singleton type, but there's more than one
 250                  * RR in the rdataset.
 251                  */
 252                 result = DNS_R_SINGLETON;
 253                 goto free_rdatas;
 254         }
 255
 256         /*
 257          * Allocate the memory, set up a buffer, start copying in
 258          * data.
 259          */
 260         rawbuf = isc_mem_get(mctx, buflen);
 261         if (rawbuf == NULL) {
 262                 result = ISC_R_NOMEMORY;
 263                 goto free_rdatas;
 264         }
 265
 266 #if DNS_RDATASET_FIXED
 267         /* Allocate temporary offset table. */
 268         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 269         if (offsettable == NULL) {
 270                 isc_mem_put(mctx, rawbuf, buflen);
 271                 result = ISC_R_NOMEMORY;
 272                 goto free_rdatas;
 273         }
 274         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 275 #endif
 276
 277         region->base = rawbuf;
 278         region->length = buflen;
 279
 280         rawbuf += reservelen;
 281 #if DNS_RDATASET_FIXED
 282         offsetbase = rawbuf;
 283 #endif
 284
 285         *rawbuf++ = (nitems & 0xff00) >> 8;
 286         *rawbuf++ = (nitems & 0x00ff);
 287
 288 #if DNS_RDATASET_FIXED
 289         /* Skip load order table.  Filled in later. */
 290         rawbuf += nitems * 4;
 291 #endif
 292
 293         for (i = 0; i < nalloc; i++) {
 294                 if (x[i].rdata.data == NULL)
 295                         continue;
 296 #if DNS_RDATASET_FIXED
 297                 offsettable[x[i].order] = rawbuf - offsetbase;
 298 #endif
 299                 length = x[i].rdata.length;
 300                 if (rdataset->type == dns_rdatatype_rrsig)
 301                         length++;
 302                 *rawbuf++ = (length & 0xff00) >> 8;
 303                 *rawbuf++ = (length & 0x00ff);
 304 #if DNS_RDATASET_FIXED
 305                 rawbuf += 2;    /* filled in later */
 306 #endif
 307                 /*
 308                  * Store the per RR meta data.
 309                  */
 310                 if (rdataset->type == dns_rdatatype_rrsig) {
 311                         *rawbuf++ |= (x[i].rdata.flags & DNS_RDATA_OFFLINE) ?
 312                                             DNS_RDATASLAB_OFFLINE : 0;
 313                 }
 314                 memcpy(rawbuf, x[i].rdata.data, x[i].rdata.length);
 315                 rawbuf += x[i].rdata.length;
 316         }
 317
 318 #if DNS_RDATASET_FIXED
 319         fillin_offsets(offsetbase, offsettable, nalloc);
 320         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 321 #endif
 322
 323         result = ISC_R_SUCCESS;
 324
 325  free_rdatas:
 326         if (x != NULL)
 327                 isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 328         return (result);
 329 }
 330
 331 static void
 332 rdataset_disassociate(dns_rdataset_t *rdataset) {
 333         UNUSED(rdataset);
 334 }
 335
 336 static isc_result_t
 337 rdataset_first(dns_rdataset_t *rdataset) {
 338         unsigned char *raw = rdataset->private3;
 339         unsigned int count;
 340
 341         count = raw[0] * 256 + raw[1];
 342         if (count == 0) {
 343                 rdataset->private5 = NULL;
 344                 return (ISC_R_NOMORE);
 345         }
 346 #if DNS_RDATASET_FIXED
 347         raw += 2 + (4 * count);
 348 #else
 349         raw += 2;
 350 #endif
 351         /*
 352          * The privateuint4 field is the number of rdata beyond the cursor
 353          * position, so we decrement the total count by one before storing
 354          * it.
 355          */
 356         count--;
 357         rdataset->privateuint4 = count;
 358         rdataset->private5 = raw;
 359
 360         return (ISC_R_SUCCESS);
 361 }
 362
 363 static isc_result_t
 364 rdataset_next(dns_rdataset_t *rdataset) {
 365         unsigned int count;
 366         unsigned int length;
 367         unsigned char *raw;
 368
 369         count = rdataset->privateuint4;
 370         if (count == 0)
 371                 return (ISC_R_NOMORE);
 372         count--;
 373         rdataset->privateuint4 = count;
 374         raw = rdataset->private5;
 375         length = raw[0] * 256 + raw[1];
 376 #if DNS_RDATASET_FIXED
 377         raw += length + 4;
 378 #else
 379         raw += length + 2;
 380 #endif
 381         rdataset->private5 = raw;
 382
 383         return (ISC_R_SUCCESS);
 384 }
 385
 386 static void
 387 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 388         unsigned char *raw = rdataset->private5;
 389         isc_region_t r;
 390         unsigned int length;
 391         unsigned int flags = 0;
 392
 393         REQUIRE(raw != NULL);
 394
 395         length = raw[0] * 256 + raw[1];
 396 #if DNS_RDATASET_FIXED
 397         raw += 4;
 398 #else
 399         raw += 2;
 400 #endif
 401         if (rdataset->type == dns_rdatatype_rrsig) {
 402                 if (*raw & DNS_RDATASLAB_OFFLINE)
 403                         flags |= DNS_RDATA_OFFLINE;
 404                 length--;
 405                 raw++;
 406         }
 407         r.length = length;
 408         r.base = raw;
 409         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 410         rdata->flags |= flags;
 411 }
 412
 413 static void
 414 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 415         *target = *source;
 416
 417         /*
 418          * Reset iterator state.
 419          */
 420         target->privateuint4 = 0;
 421         target->private5 = NULL;
 422 }
 423
 424 static unsigned int
 425 rdataset_count(dns_rdataset_t *rdataset) {
 426         unsigned char *raw = rdataset->private3;
 427         unsigned int count;
 428
 429         count = raw[0] * 256 + raw[1];
 430
 431         return (count);
 432 }
 433
 434 static dns_rdatasetmethods_t rdataset_methods = {
 435         rdataset_disassociate,
 436         rdataset_first,
 437         rdataset_next,
 438         rdataset_current,
 439         rdataset_clone,
 440         rdataset_count,
 441         NULL,
 442         NULL,
 443         NULL,
 444         NULL,
 445         NULL,
 446         NULL,
 447         NULL,
 448         NULL,
 449         NULL
 450 };
 451
 452 void
 453 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 454                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 455                          dns_rdatatype_t covers, dns_ttl_t ttl,
 456                          dns_rdataset_t *rdataset)
 457 {
 458         REQUIRE(slab != NULL);
 459         REQUIRE(!dns_rdataset_isassociated(rdataset));
 460
 461         rdataset->methods = &rdataset_methods;
 462         rdataset->rdclass = rdclass;
 463         rdataset->type = rdtype;
 464         rdataset->covers = covers;
 465         rdataset->ttl = ttl;
 466         rdataset->trust = 0;
 467         rdataset->private1 = NULL;
 468         rdataset->private2 = NULL;
 469         rdataset->private3 = slab + reservelen;
 470
 471         /*
 472          * Reset iterator state.
 473          */
 474         rdataset->privateuint4 = 0;
 475         rdataset->private5 = NULL;
 476 }
 477
 478 unsigned int
 479 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 480         unsigned int count, length;
 481         unsigned char *current;
 482
 483         REQUIRE(slab != NULL);
 484
 485         current = slab + reservelen;
 486         count = *current++ * 256;
 487         count += *current++;
 488 #if DNS_RDATASET_FIXED
 489         current += (4 * count);
 490 #endif
 491         while (count > 0) {
 492                 count--;
 493                 length = *current++ * 256;
 494                 length += *current++;
 495 #if DNS_RDATASET_FIXED
 496                 current += length + 2;
 497 #else
 498                 current += length;
 499 #endif
 500         }
 501
 502         return ((unsigned int)(current - slab));
 503 }
 504
 505 /*
 506  * Make the dns_rdata_t 'rdata' refer to the slab item
 507  * beginning at '*current', which is part of a slab of type
 508  * 'type' and class 'rdclass', and advance '*current' to
 509  * point to the next item in the slab.
 510  */
 511 static inline void
 512 rdata_from_slab(unsigned char **current,
 513               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 514               dns_rdata_t *rdata)
 515 {
 516         unsigned char *tcurrent = *current;
 517         isc_region_t region;
 518         unsigned int length;
 519         isc_boolean_t offline = ISC_FALSE;
 520
 521         length = *tcurrent++ * 256;
 522         length += *tcurrent++;
 523
 524         if (type == dns_rdatatype_rrsig) {
 525                 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0)
 526                         offline = ISC_TRUE;
 527                 length--;
 528                 tcurrent++;
 529         }
 530         region.length = length;
 531 #if DNS_RDATASET_FIXED
 532         tcurrent += 2;
 533 #endif
 534         region.base = tcurrent;
 535         tcurrent += region.length;
 536         dns_rdata_fromregion(rdata, rdclass, type, &region);
 537         if (offline)
 538                 rdata->flags |= DNS_RDATA_OFFLINE;
 539         *current = tcurrent;
 540 }
 541
 542 /*
 543  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 544  * contains an rdata identical to 'rdata'.  This does case insensitive
 545  * comparisons per DNSSEC.
 546  */
 547 static inline isc_boolean_t
 548 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 549               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 550               dns_rdata_t *rdata)
 551 {
 552         unsigned int count, i;
 553         unsigned char *current;
 554         dns_rdata_t trdata = DNS_RDATA_INIT;
 555         int n;
 556
 557         current = slab + reservelen;
 558         count = *current++ * 256;
 559         count += *current++;
 560
 561 #if DNS_RDATASET_FIXED
 562         current += (4 * count);
 563 #endif
 564
 565         for (i = 0; i < count; i++) {
 566                 rdata_from_slab(&current, rdclass, type, &trdata);
 567
 568                 n = dns_rdata_compare(&trdata, rdata);
 569                 if (n == 0)
 570                         return (ISC_TRUE);
 571                 if (n > 0)      /* In DNSSEC order. */
 572                         break;
 573                 dns_rdata_reset(&trdata);
 574         }
 575         return (ISC_FALSE);
 576 }
 577
 578 isc_result_t
 579 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 580                     unsigned int reservelen, isc_mem_t *mctx,
 581                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 582                     unsigned int flags, unsigned char **tslabp)
 583 {
 584         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
 585         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 586         dns_rdata_t ordata = DNS_RDATA_INIT;
 587         dns_rdata_t nrdata = DNS_RDATA_INIT;
 588         isc_boolean_t added_something = ISC_FALSE;
 589         unsigned int oadded = 0;
 590         unsigned int nadded = 0;
 591         unsigned int nncount = 0;
 592 #if DNS_RDATASET_FIXED
 593         unsigned int oncount;
 594         unsigned int norder = 0;
 595         unsigned int oorder = 0;
 596         unsigned char *offsetbase;
 597         unsigned int *offsettable;
 598 #endif
 599
 600         /*
 601          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 602          * or perhaps another merge routine for this purpose.
 603          */
 604
 605         REQUIRE(tslabp != NULL && *tslabp == NULL);
 606         REQUIRE(oslab != NULL && nslab != NULL);
 607
 608         ocurrent = oslab + reservelen;
 609         ocount = *ocurrent++ * 256;
 610         ocount += *ocurrent++;
 611 #if DNS_RDATASET_FIXED
 612         ocurrent += (4 * ocount);
 613 #endif
 614         ostart = ocurrent;
 615         ncurrent = nslab + reservelen;
 616         ncount = *ncurrent++ * 256;
 617         ncount += *ncurrent++;
 618 #if DNS_RDATASET_FIXED
 619         ncurrent += (4 * ncount);
 620 #endif
 621         INSIST(ocount > 0 && ncount > 0);
 622
 623 #if DNS_RDATASET_FIXED
 624         oncount = ncount;
 625 #endif
 626
 627         /*
 628          * Yes, this is inefficient!
 629          */
 630
 631         /*
 632          * Figure out the length of the old slab's data.
 633          */
 634         olength = 0;
 635         for (count = 0; count < ocount; count++) {
 636                 length = *ocurrent++ * 256;
 637                 length += *ocurrent++;
 638 #if DNS_RDATASET_FIXED
 639                 olength += length + 8;
 640                 ocurrent += length + 2;
 641 #else
 642                 olength += length + 2;
 643                 ocurrent += length;
 644 #endif
 645         }
 646
 647         /*
 648          * Start figuring out the target length and count.
 649          */
 650         tlength = reservelen + 2 + olength;
 651         tcount = ocount;
 652
 653         /*
 654          * Add in the length of rdata in the new slab that aren't in
 655          * the old slab.
 656          */
 657         do {
 658                 dns_rdata_init(&nrdata);
 659                 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 660                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 661                 {
 662                         /*
 663                          * This rdata isn't in the old slab.
 664                          */
 665 #if DNS_RDATASET_FIXED
 666                         tlength += nrdata.length + 8;
 667 #else
 668                         tlength += nrdata.length + 2;
 669 #endif
 670                         if (type == dns_rdatatype_rrsig)
 671                                 tlength++;
 672                         tcount++;
 673                         nncount++;
 674                         added_something = ISC_TRUE;
 675                 }
 676                 ncount--;
 677         } while (ncount > 0);
 678         ncount = nncount;
 679
 680         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 681             (tcount != ncount + ocount))
 682                 return (DNS_R_NOTEXACT);
 683
 684         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 685                 return (DNS_R_UNCHANGED);
 686
 687         /*
 688          * Ensure that singleton types are actually singletons.
 689          */
 690         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 691                 /*
 692                  * We have a singleton type, but there's more than one
 693                  * RR in the rdataset.
 694                  */
 695                 return (DNS_R_SINGLETON);
 696         }
 697
 698         if (tcount > 0xffff)
 699                 return (ISC_R_NOSPACE);
 700
 701         /*
 702          * Copy the reserved area from the new slab.
 703          */
 704         tstart = isc_mem_get(mctx, tlength);
 705         if (tstart == NULL)
 706                 return (ISC_R_NOMEMORY);
 707         memcpy(tstart, nslab, reservelen);
 708         tcurrent = tstart + reservelen;
 709 #if DNS_RDATASET_FIXED
 710         offsetbase = tcurrent;
 711 #endif
 712
 713         /*
 714          * Write the new count.
 715          */
 716         *tcurrent++ = (tcount & 0xff00) >> 8;
 717         *tcurrent++ = (tcount & 0x00ff);
 718
 719 #if DNS_RDATASET_FIXED
 720         /*
 721          * Skip offset table.
 722          */
 723         tcurrent += (tcount * 4);
 724
 725         offsettable = isc_mem_get(mctx,
 726                                   (ocount + oncount) * sizeof(unsigned int));
 727         if (offsettable == NULL) {
 728                 isc_mem_put(mctx, tstart, tlength);
 729                 return (ISC_R_NOMEMORY);
 730         }
 731         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 732 #endif
 733
 734         /*
 735          * Merge the two slabs.
 736          */
 737         ocurrent = ostart;
 738         INSIST(ocount != 0);
 739 #if DNS_RDATASET_FIXED
 740         oorder = ocurrent[2] * 256 + ocurrent[3];
 741         INSIST(oorder < ocount);
 742 #endif
 743         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 744
 745         ncurrent = nslab + reservelen + 2;
 746 #if DNS_RDATASET_FIXED
 747         ncurrent += (4 * oncount);
 748 #endif
 749
 750         if (ncount > 0) {
 751                 do {
 752                         dns_rdata_reset(&nrdata);
 753 #if DNS_RDATASET_FIXED
 754                         norder = ncurrent[2] * 256 + ncurrent[3];
 755
 756                         INSIST(norder < oncount);
 757 #endif
 758                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 759                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 760                                        type, &nrdata));
 761         }
 762
 763         while (oadded < ocount || nadded < ncount) {
 764                 isc_boolean_t fromold;
 765                 if (oadded == ocount)
 766                         fromold = ISC_FALSE;
 767                 else if (nadded == ncount)
 768                         fromold = ISC_TRUE;
 769                 else
 770                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 771                 if (fromold) {
 772 #if DNS_RDATASET_FIXED
 773                         offsettable[oorder] = tcurrent - offsetbase;
 774 #endif
 775                         length = ordata.length;
 776                         data = ordata.data;
 777                         if (type == dns_rdatatype_rrsig) {
 778                                 length++;
 779                                 data--;
 780                         }
 781                         *tcurrent++ = (length & 0xff00) >> 8;
 782                         *tcurrent++ = (length & 0x00ff);
 783 #if DNS_RDATASET_FIXED
 784                         tcurrent += 2;  /* fill in later */
 785 #endif
 786                         memcpy(tcurrent, data, length);
 787                         tcurrent += length;
 788                         oadded++;
 789                         if (oadded < ocount) {
 790                                 dns_rdata_reset(&ordata);
 791 #if DNS_RDATASET_FIXED
 792                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 793                                 INSIST(oorder < ocount);
 794 #endif
 795                                 rdata_from_slab(&ocurrent, rdclass, type,
 796                                                 &ordata);
 797                         }
 798                 } else {
 799 #if DNS_RDATASET_FIXED
 800                         offsettable[ocount + norder] = tcurrent - offsetbase;
 801 #endif
 802                         length = nrdata.length;
 803                         data = nrdata.data;
 804                         if (type == dns_rdatatype_rrsig) {
 805                                 length++;
 806                                 data--;
 807                         }
 808                         *tcurrent++ = (length & 0xff00) >> 8;
 809                         *tcurrent++ = (length & 0x00ff);
 810 #if DNS_RDATASET_FIXED
 811                         tcurrent += 2;  /* fill in later */
 812 #endif
 813                         memcpy(tcurrent, data, length);
 814                         tcurrent += length;
 815                         nadded++;
 816                         if (nadded < ncount) {
 817                                 do {
 818                                         dns_rdata_reset(&nrdata);
 819 #if DNS_RDATASET_FIXED
 820                                         norder = ncurrent[2] * 256 + ncurrent[3];
 821                                         INSIST(norder < oncount);
 822 #endif
 823                                         rdata_from_slab(&ncurrent, rdclass,
 824                                                         type, &nrdata);
 825                                 } while (rdata_in_slab(oslab, reservelen,
 826                                                        rdclass, type,
 827                                                        &nrdata));
 828                         }
 829                 }
 830         }
 831
 832 #if DNS_RDATASET_FIXED
 833         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 834
 835         isc_mem_put(mctx, offsettable,
 836                     (ocount + oncount) * sizeof(unsigned int));
 837 #endif
 838
 839         INSIST(tcurrent == tstart + tlength);
 840
 841         *tslabp = tstart;
 842
 843         return (ISC_R_SUCCESS);
 844 }
 845
 846 isc_result_t
 847 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 848                        unsigned int reservelen, isc_mem_t *mctx,
 849                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 850                        unsigned int flags, unsigned char **tslabp)
 851 {
 852         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 853         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 854         dns_rdata_t srdata = DNS_RDATA_INIT;
 855         dns_rdata_t mrdata = DNS_RDATA_INIT;
 856 #if DNS_RDATASET_FIXED
 857         unsigned char *offsetbase;
 858         unsigned int *offsettable;
 859         unsigned int order;
 860 #endif
 861
 862         REQUIRE(tslabp != NULL && *tslabp == NULL);
 863         REQUIRE(mslab != NULL && sslab != NULL);
 864
 865         mcurrent = mslab + reservelen;
 866         mcount = *mcurrent++ * 256;
 867         mcount += *mcurrent++;
 868         scurrent = sslab + reservelen;
 869         scount = *scurrent++ * 256;
 870         scount += *scurrent++;
 871         INSIST(mcount > 0 && scount > 0);
 872
 873         /*
 874          * Yes, this is inefficient!
 875          */
 876
 877         /*
 878          * Start figuring out the target length and count.
 879          */
 880         tlength = reservelen + 2;
 881         tcount = 0;
 882         rcount = 0;
 883
 884 #if DNS_RDATASET_FIXED
 885         mcurrent += 4 * mcount;
 886         scurrent += 4 * scount;
 887 #endif
 888         sstart = scurrent;
 889
 890         /*
 891          * Add in the length of rdata in the mslab that aren't in
 892          * the sslab.
 893          */
 894         for (i = 0; i < mcount; i++) {
 895                 unsigned char *mrdatabegin = mcurrent;
 896                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 897                 scurrent = sstart;
 898                 for (count = 0; count < scount; count++) {
 899                         dns_rdata_reset(&srdata);
 900                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 901                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 902                                 break;
 903                 }
 904                 if (count == scount) {
 905                         /*
 906                          * This rdata isn't in the sslab, and thus isn't
 907                          * being subtracted.
 908                          */
 909                         tlength += mcurrent - mrdatabegin;
 910                         tcount++;
 911                 } else
 912                         rcount++;
 913                 dns_rdata_reset(&mrdata);
 914         }
 915
 916 #if DNS_RDATASET_FIXED
 917         tlength += (4 * tcount);
 918 #endif
 919
 920         /*
 921          * Check that all the records originally existed.  The numeric
 922          * check only works as rdataslabs do not contain duplicates.
 923          */
 924         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 925                 return (DNS_R_NOTEXACT);
 926
 927         /*
 928          * Don't continue if the new rdataslab would be empty.
 929          */
 930         if (tcount == 0)
 931                 return (DNS_R_NXRRSET);
 932
 933         /*
 934          * If nothing is going to change, we can stop.
 935          */
 936         if (rcount == 0)
 937                 return (DNS_R_UNCHANGED);
 938
 939         /*
 940          * Copy the reserved area from the mslab.
 941          */
 942         tstart = isc_mem_get(mctx, tlength);
 943         if (tstart == NULL)
 944                 return (ISC_R_NOMEMORY);
 945         memcpy(tstart, mslab, reservelen);
 946         tcurrent = tstart + reservelen;
 947 #if DNS_RDATASET_FIXED
 948         offsetbase = tcurrent;
 949
 950         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 951         if (offsettable == NULL) {
 952                 isc_mem_put(mctx, tstart, tlength);
 953                 return (ISC_R_NOMEMORY);
 954         }
 955         memset(offsettable, 0, mcount * sizeof(unsigned int));
 956 #endif
 957
 958         /*
 959          * Write the new count.
 960          */
 961         *tcurrent++ = (tcount & 0xff00) >> 8;
 962         *tcurrent++ = (tcount & 0x00ff);
 963
 964 #if DNS_RDATASET_FIXED
 965         tcurrent += (4 * tcount);
 966 #endif
 967
 968         /*
 969          * Copy the parts of mslab not in sslab.
 970          */
 971         mcurrent = mslab + reservelen;
 972         mcount = *mcurrent++ * 256;
 973         mcount += *mcurrent++;
 974 #if DNS_RDATASET_FIXED
 975         mcurrent += (4 * mcount);
 976 #endif
 977         for (i = 0; i < mcount; i++) {
 978                 unsigned char *mrdatabegin = mcurrent;
 979 #if DNS_RDATASET_FIXED
 980                 order = mcurrent[2] * 256 + mcurrent[3];
 981                 INSIST(order < mcount);
 982 #endif
 983                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 984                 scurrent = sstart;
 985                 for (count = 0; count < scount; count++) {
 986                         dns_rdata_reset(&srdata);
 987                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 988                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 989                                 break;
 990                 }
 991                 if (count == scount) {
 992                         /*
 993                          * This rdata isn't in the sslab, and thus should be
 994                          * copied to the tslab.
 995                          */
 996                         unsigned int length = mcurrent - mrdatabegin;
 997 #if DNS_RDATASET_FIXED
 998                         offsettable[order] = tcurrent - offsetbase;
 999 #endif
1000                         memcpy(tcurrent, mrdatabegin, length);
1001                         tcurrent += length;
1002                 }
1003                 dns_rdata_reset(&mrdata);
1004         }
1005
1006 #if DNS_RDATASET_FIXED
1007         fillin_offsets(offsetbase, offsettable, mcount);
1008
1009         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
1010 #endif
1011
1012         INSIST(tcurrent == tstart + tlength);
1013
1014         *tslabp = tstart;
1015
1016         return (ISC_R_SUCCESS);
1017 }
1018
1019 isc_boolean_t
1020 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
1021                     unsigned int reservelen)
1022 {
1023         unsigned char *current1, *current2;
1024         unsigned int count1, count2;
1025         unsigned int length1, length2;
1026
1027         current1 = slab1 + reservelen;
1028         count1 = *current1++ * 256;
1029         count1 += *current1++;
1030
1031         current2 = slab2 + reservelen;
1032         count2 = *current2++ * 256;
1033         count2 += *current2++;
1034
1035         if (count1 != count2)
1036                 return (ISC_FALSE);
1037
1038 #if DNS_RDATASET_FIXED
1039         current1 += (4 * count1);
1040         current2 += (4 * count2);
1041 #endif
1042
1043         while (count1 > 0) {
1044                 length1 = *current1++ * 256;
1045                 length1 += *current1++;
1046
1047                 length2 = *current2++ * 256;
1048                 length2 += *current2++;
1049
1050 #if DNS_RDATASET_FIXED
1051                 current1 += 2;
1052                 current2 += 2;
1053 #endif
1054
1055                 if (length1 != length2 ||
1056                     memcmp(current1, current2, length1) != 0)
1057                         return (ISC_FALSE);
1058
1059                 current1 += length1;
1060                 current2 += length1;
1061
1062                 count1--;
1063         }
1064         return (ISC_TRUE);
1065 }
1066
1067 isc_boolean_t
1068 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1069                      unsigned int reservelen, dns_rdataclass_t rdclass,
1070                      dns_rdatatype_t type)
1071 {
1072         unsigned char *current1, *current2;
1073         unsigned int count1, count2;
1074         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1075         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1076
1077         current1 = slab1 + reservelen;
1078         count1 = *current1++ * 256;
1079         count1 += *current1++;
1080
1081         current2 = slab2 + reservelen;
1082         count2 = *current2++ * 256;
1083         count2 += *current2++;
1084
1085         if (count1 != count2)
1086                 return (ISC_FALSE);
1087
1088 #if DNS_RDATASET_FIXED
1089         current1 += (4 * count1);
1090         current2 += (4 * count2);
1091 #endif
1092
1093         while (count1-- > 0) {
1094                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1095                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1096                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1097                         return (ISC_FALSE);
1098                 dns_rdata_reset(&rdata1);
1099                 dns_rdata_reset(&rdata2);
1100         }
1101         return (ISC_TRUE);
1102 }