contrib/bind9/lib/dns/ncache.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007, 2008, 2010-2012  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id$ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <isc/buffer.h>
  25 #include <isc/util.h>
  26
  27 #include <dns/db.h>
  28 #include <dns/message.h>
  29 #include <dns/ncache.h>
  30 #include <dns/rdata.h>
  31 #include <dns/rdatalist.h>
  32 #include <dns/rdataset.h>
  33 #include <dns/rdatastruct.h>
  34
  35 #define DNS_NCACHE_RDATA 20U
  36
  37 /*
  38  * The format of an ncache rdata is a sequence of zero or more records of
  39  * the following format:
  40  *
  41  *      owner name
  42  *      type
  43  *      trust
  44  *      rdata count
  45  *              rdata length                    These two occur 'rdata count'
  46  *              rdata                           times.
  47  *
  48  */
  49
  50 static inline isc_result_t
  51 copy_rdataset(dns_rdataset_t *rdataset, isc_buffer_t *buffer) {
  52         isc_result_t result;
  53         unsigned int count;
  54         isc_region_t ar, r;
  55         dns_rdata_t rdata = DNS_RDATA_INIT;
  56
  57         /*
  58          * Copy the rdataset count to the buffer.
  59          */
  60         isc_buffer_availableregion(buffer, &ar);
  61         if (ar.length < 2)
  62                 return (ISC_R_NOSPACE);
  63         count = dns_rdataset_count(rdataset);
  64         INSIST(count <= 65535);
  65         isc_buffer_putuint16(buffer, (isc_uint16_t)count);
  66
  67         result = dns_rdataset_first(rdataset);
  68         while (result == ISC_R_SUCCESS) {
  69                 dns_rdataset_current(rdataset, &rdata);
  70                 dns_rdata_toregion(&rdata, &r);
  71                 INSIST(r.length <= 65535);
  72                 isc_buffer_availableregion(buffer, &ar);
  73                 if (ar.length < 2)
  74                         return (ISC_R_NOSPACE);
  75                 /*
  76                  * Copy the rdata length to the buffer.
  77                  */
  78                 isc_buffer_putuint16(buffer, (isc_uint16_t)r.length);
  79                 /*
  80                  * Copy the rdata to the buffer.
  81                  */
  82                 result = isc_buffer_copyregion(buffer, &r);
  83                 if (result != ISC_R_SUCCESS)
  84                         return (result);
  85                 dns_rdata_reset(&rdata);
  86                 result = dns_rdataset_next(rdataset);
  87         }
  88         if (result != ISC_R_NOMORE)
  89                 return (result);
  90
  91         return (ISC_R_SUCCESS);
  92 }
  93
  94 isc_result_t
  95 dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
  96                dns_rdatatype_t covers, isc_stdtime_t now, dns_ttl_t maxttl,
  97                dns_rdataset_t *addedrdataset)
  98 {
  99         return (dns_ncache_addoptout(message, cache, node, covers, now, maxttl,
 100                                     ISC_FALSE, addedrdataset));
 101 }
 102
 103 isc_result_t
 104 dns_ncache_addoptout(dns_message_t *message, dns_db_t *cache,
 105                      dns_dbnode_t *node, dns_rdatatype_t covers,
 106                      isc_stdtime_t now, dns_ttl_t maxttl,
 107                      isc_boolean_t optout, dns_rdataset_t *addedrdataset)
 108 {
 109         isc_result_t result;
 110         isc_buffer_t buffer;
 111         isc_region_t r;
 112         dns_rdataset_t *rdataset;
 113         dns_rdatatype_t type;
 114         dns_name_t *name;
 115         dns_ttl_t ttl;
 116         dns_trust_t trust;
 117         dns_rdata_t rdata[DNS_NCACHE_RDATA];
 118         dns_rdataset_t ncrdataset;
 119         dns_rdatalist_t ncrdatalist;
 120         unsigned char data[4096];
 121         unsigned int next = 0;
 122
 123         /*
 124          * Convert the authority data from 'message' into a negative cache
 125          * rdataset, and store it in 'cache' at 'node'.
 126          */
 127
 128         REQUIRE(message != NULL);
 129
 130         /*
 131          * We assume that all data in the authority section has been
 132          * validated by the caller.
 133          */
 134
 135         /*
 136          * Initialize the list.
 137          */
 138         ncrdatalist.rdclass = dns_db_class(cache);
 139         ncrdatalist.type = 0;
 140         ncrdatalist.covers = covers;
 141         ncrdatalist.ttl = maxttl;
 142         ISC_LIST_INIT(ncrdatalist.rdata);
 143         ISC_LINK_INIT(&ncrdatalist, link);
 144
 145         /*
 146          * Build an ncache rdatas into buffer.
 147          */
 148         ttl = maxttl;
 149         trust = 0xffff;
 150         isc_buffer_init(&buffer, data, sizeof(data));
 151         if (message->counts[DNS_SECTION_AUTHORITY])
 152                 result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
 153         else
 154                 result = ISC_R_NOMORE;
 155         while (result == ISC_R_SUCCESS) {
 156                 name = NULL;
 157                 dns_message_currentname(message, DNS_SECTION_AUTHORITY,
 158                                         &name);
 159                 if ((name->attributes & DNS_NAMEATTR_NCACHE) != 0) {
 160                         for (rdataset = ISC_LIST_HEAD(name->list);
 161                              rdataset != NULL;
 162                              rdataset = ISC_LIST_NEXT(rdataset, link)) {
 163                                 if ((rdataset->attributes &
 164                                      DNS_RDATASETATTR_NCACHE) == 0)
 165                                         continue;
 166                                 type = rdataset->type;
 167                                 if (type == dns_rdatatype_rrsig)
 168                                         type = rdataset->covers;
 169                                 if (type == dns_rdatatype_soa ||
 170                                     type == dns_rdatatype_nsec ||
 171                                     type == dns_rdatatype_nsec3) {
 172                                         if (ttl > rdataset->ttl)
 173                                                 ttl = rdataset->ttl;
 174                                         if (trust > rdataset->trust)
 175                                                 trust = rdataset->trust;
 176                                         /*
 177                                          * Copy the owner name to the buffer.
 178                                          */
 179                                         dns_name_toregion(name, &r);
 180                                         result = isc_buffer_copyregion(&buffer,
 181                                                                        &r);
 182                                         if (result != ISC_R_SUCCESS)
 183                                                 return (result);
 184                                         /*
 185                                          * Copy the type to the buffer.
 186                                          */
 187                                         isc_buffer_availableregion(&buffer,
 188                                                                    &r);
 189                                         if (r.length < 3)
 190                                                 return (ISC_R_NOSPACE);
 191                                         isc_buffer_putuint16(&buffer,
 192                                                              rdataset->type);
 193                                         isc_buffer_putuint8(&buffer,
 194                                                (unsigned char)rdataset->trust);
 195                                         /*
 196                                          * Copy the rdataset into the buffer.
 197                                          */
 198                                         result = copy_rdataset(rdataset,
 199                                                                &buffer);
 200                                         if (result != ISC_R_SUCCESS)
 201                                                 return (result);
 202
 203                                         if (next >= DNS_NCACHE_RDATA)
 204                                                 return (ISC_R_NOSPACE);
 205                                         dns_rdata_init(&rdata[next]);
 206                                         isc_buffer_remainingregion(&buffer, &r);
 207                                         rdata[next].data = r.base;
 208                                         rdata[next].length = r.length;
 209                                         rdata[next].rdclass =
 210                                                 ncrdatalist.rdclass;
 211                                         rdata[next].type = 0;
 212                                         rdata[next].flags = 0;
 213                                         ISC_LIST_APPEND(ncrdatalist.rdata,
 214                                                         &rdata[next], link);
 215                                         isc_buffer_forward(&buffer, r.length);
 216                                         next++;
 217                                 }
 218                         }
 219                 }
 220                 result = dns_message_nextname(message, DNS_SECTION_AUTHORITY);
 221         }
 222         if (result != ISC_R_NOMORE)
 223                 return (result);
 224
 225         if (trust == 0xffff) {
 226                 if ((message->flags & DNS_MESSAGEFLAG_AA) != 0 &&
 227                     message->counts[DNS_SECTION_ANSWER] == 0) {
 228                         /*
 229                          * The response has aa set and we haven't followed
 230                          * any CNAME or DNAME chains.
 231                          */
 232                         trust = dns_trust_authauthority;
 233                 } else
 234                         trust = dns_trust_additional;
 235                 ttl = 0;
 236         }
 237
 238         INSIST(trust != 0xffff);
 239
 240         ncrdatalist.ttl = ttl;
 241
 242         dns_rdataset_init(&ncrdataset);
 243         RUNTIME_CHECK(dns_rdatalist_tordataset(&ncrdatalist, &ncrdataset)
 244                       == ISC_R_SUCCESS);
 245         ncrdataset.trust = trust;
 246         ncrdataset.attributes |= DNS_RDATASETATTR_NEGATIVE;
 247         if (message->rcode == dns_rcode_nxdomain)
 248                 ncrdataset.attributes |= DNS_RDATASETATTR_NXDOMAIN;
 249         if (optout)
 250                 ncrdataset.attributes |= DNS_RDATASETATTR_OPTOUT;
 251
 252         return (dns_db_addrdataset(cache, node, NULL, now, &ncrdataset,
 253                                    0, addedrdataset));
 254 }
 255
 256 isc_result_t
 257 dns_ncache_towire(dns_rdataset_t *rdataset, dns_compress_t *cctx,
 258                   isc_buffer_t *target, unsigned int options,
 259                   unsigned int *countp)
 260 {
 261         dns_rdata_t rdata = DNS_RDATA_INIT;
 262         isc_result_t result;
 263         isc_region_t remaining, tavailable;
 264         isc_buffer_t source, savedbuffer, rdlen;
 265         dns_name_t name;
 266         dns_rdatatype_t type;
 267         unsigned int i, rcount, count;
 268
 269         /*
 270          * Convert the negative caching rdataset 'rdataset' to wire format,
 271          * compressing names as specified in 'cctx', and storing the result in
 272          * 'target'.
 273          */
 274
 275         REQUIRE(rdataset != NULL);
 276         REQUIRE(rdataset->type == 0);
 277         REQUIRE((rdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0);
 278
 279         savedbuffer = *target;
 280         count = 0;
 281
 282         result = dns_rdataset_first(rdataset);
 283         while (result == ISC_R_SUCCESS) {
 284                 dns_rdataset_current(rdataset, &rdata);
 285                 isc_buffer_init(&source, rdata.data, rdata.length);
 286                 isc_buffer_add(&source, rdata.length);
 287                 dns_name_init(&name, NULL);
 288                 isc_buffer_remainingregion(&source, &remaining);
 289                 dns_name_fromregion(&name, &remaining);
 290                 INSIST(remaining.length >= name.length);
 291                 isc_buffer_forward(&source, name.length);
 292                 remaining.length -= name.length;
 293
 294                 INSIST(remaining.length >= 5);
 295                 type = isc_buffer_getuint16(&source);
 296                 isc_buffer_forward(&source, 1);
 297                 rcount = isc_buffer_getuint16(&source);
 298
 299                 for (i = 0; i < rcount; i++) {
 300                         /*
 301                          * Get the length of this rdata and set up an
 302                          * rdata structure for it.
 303                          */
 304                         isc_buffer_remainingregion(&source, &remaining);
 305                         INSIST(remaining.length >= 2);
 306                         dns_rdata_reset(&rdata);
 307                         rdata.length = isc_buffer_getuint16(&source);
 308                         isc_buffer_remainingregion(&source, &remaining);
 309                         rdata.data = remaining.base;
 310                         rdata.type = type;
 311                         rdata.rdclass = rdataset->rdclass;
 312                         INSIST(remaining.length >= rdata.length);
 313                         isc_buffer_forward(&source, rdata.length);
 314
 315                         if ((options & DNS_NCACHETOWIRE_OMITDNSSEC) != 0 &&
 316                             dns_rdatatype_isdnssec(type))
 317                                 continue;
 318
 319                         /*
 320                          * Write the name.
 321                          */
 322                         dns_compress_setmethods(cctx, DNS_COMPRESS_GLOBAL14);
 323                         result = dns_name_towire(&name, cctx, target);
 324                         if (result != ISC_R_SUCCESS)
 325                                 goto rollback;
 326
 327                         /*
 328                          * See if we have space for type, class, ttl, and
 329                          * rdata length.  Write the type, class, and ttl.
 330                          */
 331                         isc_buffer_availableregion(target, &tavailable);
 332                         if (tavailable.length < 10) {
 333                                 result = ISC_R_NOSPACE;
 334                                 goto rollback;
 335                         }
 336                         isc_buffer_putuint16(target, type);
 337                         isc_buffer_putuint16(target, rdataset->rdclass);
 338                         isc_buffer_putuint32(target, rdataset->ttl);
 339
 340                         /*
 341                          * Save space for rdata length.
 342                          */
 343                         rdlen = *target;
 344                         isc_buffer_add(target, 2);
 345
 346                         /*
 347                          * Write the rdata.
 348                          */
 349                         result = dns_rdata_towire(&rdata, cctx, target);
 350                         if (result != ISC_R_SUCCESS)
 351                                 goto rollback;
 352
 353                         /*
 354                          * Set the rdata length field to the compressed
 355                          * length.
 356                          */
 357                         INSIST((target->used >= rdlen.used + 2) &&
 358                                (target->used - rdlen.used - 2 < 65536));
 359                         isc_buffer_putuint16(&rdlen,
 360                                              (isc_uint16_t)(target->used -
 361                                                             rdlen.used - 2));
 362
 363                         count++;
 364                 }
 365                 INSIST(isc_buffer_remaininglength(&source) == 0);
 366                 result = dns_rdataset_next(rdataset);
 367                 dns_rdata_reset(&rdata);
 368         }
 369         if (result != ISC_R_NOMORE)
 370                 goto rollback;
 371
 372         *countp = count;
 373
 374         return (ISC_R_SUCCESS);
 375
 376  rollback:
 377         INSIST(savedbuffer.used < 65536);
 378         dns_compress_rollback(cctx, (isc_uint16_t)savedbuffer.used);
 379         *countp = 0;
 380         *target = savedbuffer;
 381
 382         return (result);
 383 }
 384
 385 static void
 386 rdataset_disassociate(dns_rdataset_t *rdataset) {
 387         UNUSED(rdataset);
 388 }
 389
 390 static isc_result_t
 391 rdataset_first(dns_rdataset_t *rdataset) {
 392         unsigned char *raw = rdataset->private3;
 393         unsigned int count;
 394
 395         count = raw[0] * 256 + raw[1];
 396         if (count == 0) {
 397                 rdataset->private5 = NULL;
 398                 return (ISC_R_NOMORE);
 399         }
 400         raw += 2;
 401         /*
 402          * The privateuint4 field is the number of rdata beyond the cursor
 403          * position, so we decrement the total count by one before storing
 404          * it.
 405          */
 406         count--;
 407         rdataset->privateuint4 = count;
 408         rdataset->private5 = raw;
 409
 410         return (ISC_R_SUCCESS);
 411 }
 412
 413 static isc_result_t
 414 rdataset_next(dns_rdataset_t *rdataset) {
 415         unsigned int count;
 416         unsigned int length;
 417         unsigned char *raw;
 418
 419         count = rdataset->privateuint4;
 420         if (count == 0)
 421                 return (ISC_R_NOMORE);
 422         count--;
 423         rdataset->privateuint4 = count;
 424         raw = rdataset->private5;
 425         length = raw[0] * 256 + raw[1];
 426         raw += length + 2;
 427         rdataset->private5 = raw;
 428
 429         return (ISC_R_SUCCESS);
 430 }
 431
 432 static void
 433 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 434         unsigned char *raw = rdataset->private5;
 435         isc_region_t r;
 436
 437         REQUIRE(raw != NULL);
 438
 439         r.length = raw[0] * 256 + raw[1];
 440         raw += 2;
 441         r.base = raw;
 442         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 443 }
 444
 445 static void
 446 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 447         *target = *source;
 448
 449         /*
 450          * Reset iterator state.
 451          */
 452         target->privateuint4 = 0;
 453         target->private5 = NULL;
 454 }
 455
 456 static unsigned int
 457 rdataset_count(dns_rdataset_t *rdataset) {
 458         unsigned char *raw = rdataset->private3;
 459         unsigned int count;
 460
 461         count = raw[0] * 256 + raw[1];
 462
 463         return (count);
 464 }
 465
 466 static void
 467 rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
 468         unsigned char *raw = rdataset->private3;
 469
 470         raw[-1] = (unsigned char)trust;
 471 }
 472
 473 static dns_rdatasetmethods_t rdataset_methods = {
 474         rdataset_disassociate,
 475         rdataset_first,
 476         rdataset_next,
 477         rdataset_current,
 478         rdataset_clone,
 479         rdataset_count,
 480         NULL,
 481         NULL,
 482         NULL,
 483         NULL,
 484         NULL,
 485         NULL,
 486         NULL,
 487         rdataset_settrust,
 488         NULL
 489 };
 490
 491 isc_result_t
 492 dns_ncache_getrdataset(dns_rdataset_t *ncacherdataset, dns_name_t *name,
 493                        dns_rdatatype_t type, dns_rdataset_t *rdataset)
 494 {
 495         isc_result_t result;
 496         dns_rdata_t rdata = DNS_RDATA_INIT;
 497         isc_region_t remaining;
 498         isc_buffer_t source;
 499         dns_name_t tname;
 500         dns_rdatatype_t ttype;
 501         dns_trust_t trust = dns_trust_none;
 502         dns_rdataset_t clone;
 503
 504         REQUIRE(ncacherdataset != NULL);
 505         REQUIRE(ncacherdataset->type == 0);
 506         REQUIRE((ncacherdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0);
 507         REQUIRE(name != NULL);
 508         REQUIRE(!dns_rdataset_isassociated(rdataset));
 509         REQUIRE(type != dns_rdatatype_rrsig);
 510
 511         dns_rdataset_init(&clone);
 512         dns_rdataset_clone(ncacherdataset, &clone);
 513         result = dns_rdataset_first(&clone);
 514         while (result == ISC_R_SUCCESS) {
 515                 dns_rdataset_current(&clone, &rdata);
 516                 isc_buffer_init(&source, rdata.data, rdata.length);
 517                 isc_buffer_add(&source, rdata.length);
 518                 dns_name_init(&tname, NULL);
 519                 isc_buffer_remainingregion(&source, &remaining);
 520                 dns_name_fromregion(&tname, &remaining);
 521                 INSIST(remaining.length >= tname.length);
 522                 isc_buffer_forward(&source, tname.length);
 523                 remaining.length -= tname.length;
 524
 525                 INSIST(remaining.length >= 3);
 526                 ttype = isc_buffer_getuint16(&source);
 527
 528                 if (ttype == type && dns_name_equal(&tname, name)) {
 529                         trust = isc_buffer_getuint8(&source);
 530                         INSIST(trust <= dns_trust_ultimate);
 531                         isc_buffer_remainingregion(&source, &remaining);
 532                         break;
 533                 }
 534                 result = dns_rdataset_next(&clone);
 535                 dns_rdata_reset(&rdata);
 536         }
 537         dns_rdataset_disassociate(&clone);
 538         if (result == ISC_R_NOMORE)
 539                 return (ISC_R_NOTFOUND);
 540         if (result != ISC_R_SUCCESS)
 541                 return (result);
 542
 543         INSIST(remaining.length != 0);
 544
 545         rdataset->methods = &rdataset_methods;
 546         rdataset->rdclass = ncacherdataset->rdclass;
 547         rdataset->type = type;
 548         rdataset->covers = 0;
 549         rdataset->ttl = ncacherdataset->ttl;
 550         rdataset->trust = trust;
 551         rdataset->private1 = NULL;
 552         rdataset->private2 = NULL;
 553
 554         rdataset->private3 = remaining.base;
 555
 556         /*
 557          * Reset iterator state.
 558          */
 559         rdataset->privateuint4 = 0;
 560         rdataset->private5 = NULL;
 561         rdataset->private6 = NULL;
 562         return (ISC_R_SUCCESS);
 563 }
 564
 565 isc_result_t
 566 dns_ncache_getsigrdataset(dns_rdataset_t *ncacherdataset, dns_name_t *name,
 567                           dns_rdatatype_t covers, dns_rdataset_t *rdataset)
 568 {
 569         dns_name_t tname;
 570         dns_rdata_rrsig_t rrsig;
 571         dns_rdata_t rdata = DNS_RDATA_INIT;
 572         dns_rdataset_t clone;
 573         dns_rdatatype_t type;
 574         dns_trust_t trust = dns_trust_none;
 575         isc_buffer_t source;
 576         isc_region_t remaining, sigregion;
 577         isc_result_t result;
 578         unsigned char *raw;
 579         unsigned int count;
 580
 581         REQUIRE(ncacherdataset != NULL);
 582         REQUIRE(ncacherdataset->type == 0);
 583         REQUIRE((ncacherdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0);
 584         REQUIRE(name != NULL);
 585         REQUIRE(!dns_rdataset_isassociated(rdataset));
 586
 587         dns_rdataset_init(&clone);
 588         dns_rdataset_clone(ncacherdataset, &clone);
 589         result = dns_rdataset_first(&clone);
 590         while (result == ISC_R_SUCCESS) {
 591                 dns_rdataset_current(&clone, &rdata);
 592                 isc_buffer_init(&source, rdata.data, rdata.length);
 593                 isc_buffer_add(&source, rdata.length);
 594                 dns_name_init(&tname, NULL);
 595                 isc_buffer_remainingregion(&source, &remaining);
 596                 dns_name_fromregion(&tname, &remaining);
 597                 INSIST(remaining.length >= tname.length);
 598                 isc_buffer_forward(&source, tname.length);
 599                 remaining.length -= tname.length;
 600                 remaining.base += tname.length;
 601
 602                 INSIST(remaining.length >= 2);
 603                 type = isc_buffer_getuint16(&source);
 604                 remaining.length -= 2;
 605                 remaining.base += 2;
 606
 607                 if (type != dns_rdatatype_rrsig ||
 608                     !dns_name_equal(&tname, name)) {
 609                         result = dns_rdataset_next(&clone);
 610                         dns_rdata_reset(&rdata);
 611                         continue;
 612                 }
 613
 614                 INSIST(remaining.length >= 1);
 615                 trust = isc_buffer_getuint8(&source);
 616                 INSIST(trust <= dns_trust_ultimate);
 617                 remaining.length -= 1;
 618                 remaining.base += 1;
 619
 620                 raw = remaining.base;
 621                 count = raw[0] * 256 + raw[1];
 622                 INSIST(count > 0);
 623                 raw += 2;
 624                 sigregion.length = raw[0] * 256 + raw[1];
 625                 raw += 2;
 626                 sigregion.base = raw;
 627                 dns_rdata_reset(&rdata);
 628                 dns_rdata_fromregion(&rdata, rdataset->rdclass,
 629                                      dns_rdatatype_rrsig, &sigregion);
 630                 (void)dns_rdata_tostruct(&rdata, &rrsig, NULL);
 631                 if (rrsig.covered == covers) {
 632                         isc_buffer_remainingregion(&source, &remaining);
 633                         break;
 634                 }
 635
 636                 result = dns_rdataset_next(&clone);
 637                 dns_rdata_reset(&rdata);
 638         }
 639         dns_rdataset_disassociate(&clone);
 640         if (result == ISC_R_NOMORE)
 641                 return (ISC_R_NOTFOUND);
 642         if (result != ISC_R_SUCCESS)
 643                 return (result);
 644
 645         INSIST(remaining.length != 0);
 646
 647         rdataset->methods = &rdataset_methods;
 648         rdataset->rdclass = ncacherdataset->rdclass;
 649         rdataset->type = dns_rdatatype_rrsig;
 650         rdataset->covers = covers;
 651         rdataset->ttl = ncacherdataset->ttl;
 652         rdataset->trust = trust;
 653         rdataset->private1 = NULL;
 654         rdataset->private2 = NULL;
 655
 656         rdataset->private3 = remaining.base;
 657
 658         /*
 659          * Reset iterator state.
 660          */
 661         rdataset->privateuint4 = 0;
 662         rdataset->private5 = NULL;
 663         rdataset->private6 = NULL;
 664         return (ISC_R_SUCCESS);
 665 }
 666
 667 void
 668 dns_ncache_current(dns_rdataset_t *ncacherdataset, dns_name_t *found,
 669                    dns_rdataset_t *rdataset)
 670 {
 671         dns_rdata_t rdata = DNS_RDATA_INIT;
 672         dns_trust_t trust;
 673         isc_region_t remaining, sigregion;
 674         isc_buffer_t source;
 675         dns_name_t tname;
 676         dns_rdatatype_t type;
 677         unsigned int count;
 678         dns_rdata_rrsig_t rrsig;
 679         unsigned char *raw;
 680
 681         REQUIRE(ncacherdataset != NULL);
 682         REQUIRE(ncacherdataset->type == 0);
 683         REQUIRE((ncacherdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0);
 684         REQUIRE(found != NULL);
 685         REQUIRE(!dns_rdataset_isassociated(rdataset));
 686
 687         dns_rdataset_current(ncacherdataset, &rdata);
 688         isc_buffer_init(&source, rdata.data, rdata.length);
 689         isc_buffer_add(&source, rdata.length);
 690
 691         dns_name_init(&tname, NULL);
 692         isc_buffer_remainingregion(&source, &remaining);
 693         dns_name_fromregion(found, &remaining);
 694         INSIST(remaining.length >= found->length);
 695         isc_buffer_forward(&source, found->length);
 696         remaining.length -= found->length;
 697
 698         INSIST(remaining.length >= 5);
 699         type = isc_buffer_getuint16(&source);
 700         trust = isc_buffer_getuint8(&source);
 701         INSIST(trust <= dns_trust_ultimate);
 702         isc_buffer_remainingregion(&source, &remaining);
 703
 704         rdataset->methods = &rdataset_methods;
 705         rdataset->rdclass = ncacherdataset->rdclass;
 706         rdataset->type = type;
 707         if (type == dns_rdatatype_rrsig) {
 708                 /*
 709                  * Extract covers from RRSIG.
 710                  */
 711                 raw = remaining.base;
 712                 count = raw[0] * 256 + raw[1];
 713                 INSIST(count > 0);
 714                 raw += 2;
 715                 sigregion.length = raw[0] * 256 + raw[1];
 716                 raw += 2;
 717                 sigregion.base = raw;
 718                 dns_rdata_reset(&rdata);
 719                 dns_rdata_fromregion(&rdata, rdataset->rdclass,
 720                                      rdataset->type, &sigregion);
 721                 (void)dns_rdata_tostruct(&rdata, &rrsig, NULL);
 722                 rdataset->covers = rrsig.covered;
 723         } else
 724                 rdataset->covers = 0;
 725         rdataset->ttl = ncacherdataset->ttl;
 726         rdataset->trust = trust;
 727         rdataset->private1 = NULL;
 728         rdataset->private2 = NULL;
 729
 730         rdataset->private3 = remaining.base;
 731
 732         /*
 733          * Reset iterator state.
 734          */
 735         rdataset->privateuint4 = 0;
 736         rdataset->private5 = NULL;
 737         rdataset->private6 = NULL;
 738 }