contrib/bind/lib/dns/ncache.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007  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: ncache.c,v 1.41 2007/06/19 23:47:16 tbox Exp $ */
  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
  34 /*
  35  * The format of an ncache rdata is a sequence of one or more records of
  36  * the following format:
  37  *
  38  *      owner name
  39  *      type
  40  *      rdata count
  41  *              rdata length                    These two occur 'rdata count'
  42  *              rdata                           times.
  43  *
  44  */
  45
  46 static inline isc_result_t
  47 copy_rdataset(dns_rdataset_t *rdataset, isc_buffer_t *buffer) {
  48         isc_result_t result;
  49         unsigned int count;
  50         isc_region_t ar, r;
  51         dns_rdata_t rdata = DNS_RDATA_INIT;
  52
  53         /*
  54          * Copy the rdataset count to the buffer.
  55          */
  56         isc_buffer_availableregion(buffer, &ar);
  57         if (ar.length < 2)
  58                 return (ISC_R_NOSPACE);
  59         count = dns_rdataset_count(rdataset);
  60         INSIST(count <= 65535);
  61         isc_buffer_putuint16(buffer, (isc_uint16_t)count);
  62
  63         result = dns_rdataset_first(rdataset);
  64         while (result == ISC_R_SUCCESS) {
  65                 dns_rdataset_current(rdataset, &rdata);
  66                 dns_rdata_toregion(&rdata, &r);
  67                 INSIST(r.length <= 65535);
  68                 isc_buffer_availableregion(buffer, &ar);
  69                 if (ar.length < 2)
  70                         return (ISC_R_NOSPACE);
  71                 /*
  72                  * Copy the rdata length to the buffer.
  73                  */
  74                 isc_buffer_putuint16(buffer, (isc_uint16_t)r.length);
  75                 /*
  76                  * Copy the rdata to the buffer.
  77                  */
  78                 result = isc_buffer_copyregion(buffer, &r);
  79                 if (result != ISC_R_SUCCESS)
  80                         return (result);
  81                 dns_rdata_reset(&rdata);
  82                 result = dns_rdataset_next(rdataset);
  83         }
  84         if (result != ISC_R_NOMORE)
  85                 return (result);
  86
  87         return (ISC_R_SUCCESS);
  88 }
  89
  90 isc_result_t
  91 dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
  92                dns_rdatatype_t covers, isc_stdtime_t now, dns_ttl_t maxttl,
  93                dns_rdataset_t *addedrdataset)
  94 {
  95         isc_result_t result;
  96         isc_buffer_t buffer;
  97         isc_region_t r;
  98         dns_rdataset_t *rdataset;
  99         dns_rdatatype_t type;
 100         dns_name_t *name;
 101         dns_ttl_t ttl;
 102         dns_trust_t trust;
 103         dns_rdata_t rdata = DNS_RDATA_INIT;
 104         dns_rdataset_t ncrdataset;
 105         dns_rdatalist_t ncrdatalist;
 106         unsigned char data[4096];
 107
 108         /*
 109          * Convert the authority data from 'message' into a negative cache
 110          * rdataset, and store it in 'cache' at 'node'.
 111          */
 112
 113         REQUIRE(message != NULL);
 114
 115         /*
 116          * We assume that all data in the authority section has been
 117          * validated by the caller.
 118          */
 119
 120         /*
 121          * First, build an ncache rdata in buffer.
 122          */
 123         ttl = maxttl;
 124         trust = 0xffff;
 125         isc_buffer_init(&buffer, data, sizeof(data));
 126         if (message->counts[DNS_SECTION_AUTHORITY])
 127                 result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
 128         else
 129                 result = ISC_R_NOMORE;
 130         while (result == ISC_R_SUCCESS) {
 131                 name = NULL;
 132                 dns_message_currentname(message, DNS_SECTION_AUTHORITY,
 133                                         &name);
 134                 if ((name->attributes & DNS_NAMEATTR_NCACHE) != 0) {
 135                         for (rdataset = ISC_LIST_HEAD(name->list);
 136                              rdataset != NULL;
 137                              rdataset = ISC_LIST_NEXT(rdataset, link)) {
 138                                 if ((rdataset->attributes &
 139                                      DNS_RDATASETATTR_NCACHE) == 0)
 140                                         continue;
 141                                 type = rdataset->type;
 142                                 if (type == dns_rdatatype_rrsig)
 143                                         type = rdataset->covers;
 144                                 if (type == dns_rdatatype_soa ||
 145                                     type == dns_rdatatype_nsec) {
 146                                         if (ttl > rdataset->ttl)
 147                                                 ttl = rdataset->ttl;
 148                                         if (trust > rdataset->trust)
 149                                                 trust = rdataset->trust;
 150                                         /*
 151                                          * Copy the owner name to the buffer.
 152                                          */
 153                                         dns_name_toregion(name, &r);
 154                                         result = isc_buffer_copyregion(&buffer,
 155                                                                        &r);
 156                                         if (result != ISC_R_SUCCESS)
 157                                                 return (result);
 158                                         /*
 159                                          * Copy the type to the buffer.
 160                                          */
 161                                         isc_buffer_availableregion(&buffer,
 162                                                                    &r);
 163                                         if (r.length < 2)
 164                                                 return (ISC_R_NOSPACE);
 165                                         isc_buffer_putuint16(&buffer,
 166                                                              rdataset->type);
 167                                         /*
 168                                          * Copy the rdataset into the buffer.
 169                                          */
 170                                         result = copy_rdataset(rdataset,
 171                                                                &buffer);
 172                                         if (result != ISC_R_SUCCESS)
 173                                                 return (result);
 174                                 }
 175                         }
 176                 }
 177                 result = dns_message_nextname(message, DNS_SECTION_AUTHORITY);
 178         }
 179         if (result != ISC_R_NOMORE)
 180                 return (result);
 181
 182         if (trust == 0xffff) {
 183                 /*
 184                  * We didn't find any authority data from which to create a
 185                  * negative cache rdataset.  In particular, we have no SOA.
 186                  *
 187                  * We trust that the caller wants negative caching, so this
 188                  * means we have a "type 3 nxdomain" or "type 3 nodata"
 189                  * response (see RFC2308 for details).
 190                  *
 191                  * We will now build a suitable negative cache rdataset that
 192                  * will cause zero bytes to be emitted when converted to
 193                  * wire format.
 194                  */
 195
 196                 /*
 197                  * The ownername must exist, but it doesn't matter what value
 198                  * it has.  We use the root name.
 199                  */
 200                 dns_name_toregion(dns_rootname, &r);
 201                 result = isc_buffer_copyregion(&buffer, &r);
 202                 if (result != ISC_R_SUCCESS)
 203                         return (result);
 204                 /*
 205                  * Copy the type and a zero rdata count to the buffer.
 206                  */
 207                 isc_buffer_availableregion(&buffer, &r);
 208                 if (r.length < 4)
 209                         return (ISC_R_NOSPACE);
 210                 isc_buffer_putuint16(&buffer, 0);
 211                 isc_buffer_putuint16(&buffer, 0);
 212                 /*
 213                  * RFC2308, section 5, says that negative answers without
 214                  * SOAs should not be cached.
 215                  */
 216                 ttl = 0;
 217                 /*
 218                  * Set trust.
 219                  */
 220                 if ((message->flags & DNS_MESSAGEFLAG_AA) != 0 &&
 221                     message->counts[DNS_SECTION_ANSWER] == 0) {
 222                         /*
 223                          * The response has aa set and we haven't followed
 224                          * any CNAME or DNAME chains.
 225                          */
 226                         trust = dns_trust_authauthority;
 227                 } else
 228                         trust = dns_trust_additional;
 229         }
 230
 231         /*
 232          * Now add it to the cache.
 233          */
 234         INSIST(trust != 0xffff);
 235         isc_buffer_usedregion(&buffer, &r);
 236         rdata.data = r.base;
 237         rdata.length = r.length;
 238         rdata.rdclass = dns_db_class(cache);
 239         rdata.type = 0;
 240         rdata.flags = 0;
 241
 242         ncrdatalist.rdclass = rdata.rdclass;
 243         ncrdatalist.type = 0;
 244         ncrdatalist.covers = covers;
 245         ncrdatalist.ttl = ttl;
 246         ISC_LIST_INIT(ncrdatalist.rdata);
 247         ISC_LINK_INIT(&ncrdatalist, link);
 248
 249         ISC_LIST_APPEND(ncrdatalist.rdata, &rdata, link);
 250
 251         dns_rdataset_init(&ncrdataset);
 252         RUNTIME_CHECK(dns_rdatalist_tordataset(&ncrdatalist, &ncrdataset)
 253                       == ISC_R_SUCCESS);
 254         ncrdataset.trust = trust;
 255         if (message->rcode == dns_rcode_nxdomain)
 256                 ncrdataset.attributes |= DNS_RDATASETATTR_NXDOMAIN;
 257
 258         return (dns_db_addrdataset(cache, node, NULL, now, &ncrdataset,
 259                                    0, addedrdataset));
 260 }
 261
 262 isc_result_t
 263 dns_ncache_towire(dns_rdataset_t *rdataset, dns_compress_t *cctx,
 264                   isc_buffer_t *target, unsigned int options,
 265                   unsigned int *countp)
 266 {
 267         dns_rdata_t rdata = DNS_RDATA_INIT;
 268         isc_result_t result;
 269         isc_region_t remaining, tavailable;
 270         isc_buffer_t source, savedbuffer, rdlen;
 271         dns_name_t name;
 272         dns_rdatatype_t type;
 273         unsigned int i, rcount, count;
 274
 275         /*
 276          * Convert the negative caching rdataset 'rdataset' to wire format,
 277          * compressing names as specified in 'cctx', and storing the result in
 278          * 'target'.
 279          */
 280
 281         REQUIRE(rdataset != NULL);
 282         REQUIRE(rdataset->type == 0);
 283
 284         result = dns_rdataset_first(rdataset);
 285         if (result != ISC_R_SUCCESS)
 286                 return (result);
 287         dns_rdataset_current(rdataset, &rdata);
 288         INSIST(dns_rdataset_next(rdataset) == ISC_R_NOMORE);
 289         isc_buffer_init(&source, rdata.data, rdata.length);
 290         isc_buffer_add(&source, rdata.length);
 291
 292         savedbuffer = *target;
 293
 294         count = 0;
 295         do {
 296                 dns_name_init(&name, NULL);
 297                 isc_buffer_remainingregion(&source, &remaining);
 298                 dns_name_fromregion(&name, &remaining);
 299                 INSIST(remaining.length >= name.length);
 300                 isc_buffer_forward(&source, name.length);
 301                 remaining.length -= name.length;
 302
 303                 INSIST(remaining.length >= 4);
 304                 type = isc_buffer_getuint16(&source);
 305                 rcount = isc_buffer_getuint16(&source);
 306
 307                 for (i = 0; i < rcount; i++) {
 308                         /*
 309                          * Get the length of this rdata and set up an
 310                          * rdata structure for it.
 311                          */
 312                         isc_buffer_remainingregion(&source, &remaining);
 313                         INSIST(remaining.length >= 2);
 314                         dns_rdata_reset(&rdata);
 315                         rdata.length = isc_buffer_getuint16(&source);
 316                         isc_buffer_remainingregion(&source, &remaining);
 317                         rdata.data = remaining.base;
 318                         rdata.type = type;
 319                         rdata.rdclass = rdataset->rdclass;
 320                         INSIST(remaining.length >= rdata.length);
 321                         isc_buffer_forward(&source, rdata.length);
 322
 323                         if ((options & DNS_NCACHETOWIRE_OMITDNSSEC) != 0 &&
 324                             dns_rdatatype_isdnssec(type))
 325                                 continue;
 326
 327                         /*
 328                          * Write the name.
 329                          */
 330                         dns_compress_setmethods(cctx, DNS_COMPRESS_GLOBAL14);
 331                         result = dns_name_towire(&name, cctx, target);
 332                         if (result != ISC_R_SUCCESS)
 333                                 goto rollback;
 334
 335                         /*
 336                          * See if we have space for type, class, ttl, and
 337                          * rdata length.  Write the type, class, and ttl.
 338                          */
 339                         isc_buffer_availableregion(target, &tavailable);
 340                         if (tavailable.length < 10) {
 341                                 result = ISC_R_NOSPACE;
 342                                 goto rollback;
 343                         }
 344                         isc_buffer_putuint16(target, type);
 345                         isc_buffer_putuint16(target, rdataset->rdclass);
 346                         isc_buffer_putuint32(target, rdataset->ttl);
 347
 348                         /*
 349                          * Save space for rdata length.
 350                          */
 351                         rdlen = *target;
 352                         isc_buffer_add(target, 2);
 353
 354                         /*
 355                          * Write the rdata.
 356                          */
 357                         result = dns_rdata_towire(&rdata, cctx, target);
 358                         if (result != ISC_R_SUCCESS)
 359                                 goto rollback;
 360
 361                         /*
 362                          * Set the rdata length field to the compressed
 363                          * length.
 364                          */
 365                         INSIST((target->used >= rdlen.used + 2) &&
 366                                (target->used - rdlen.used - 2 < 65536));
 367                         isc_buffer_putuint16(&rdlen,
 368                                              (isc_uint16_t)(target->used -
 369                                                             rdlen.used - 2));
 370
 371                         count++;
 372                 }
 373                 isc_buffer_remainingregion(&source, &remaining);
 374         } while (remaining.length > 0);
 375
 376         *countp = count;
 377
 378         return (ISC_R_SUCCESS);
 379
 380  rollback:
 381         INSIST(savedbuffer.used < 65536);
 382         dns_compress_rollback(cctx, (isc_uint16_t)savedbuffer.used);
 383         *countp = 0;
 384         *target = savedbuffer;
 385
 386         return (result);
 387 }
 388
 389 static void
 390 rdataset_disassociate(dns_rdataset_t *rdataset) {
 391         UNUSED(rdataset);
 392 }
 393
 394 static isc_result_t
 395 rdataset_first(dns_rdataset_t *rdataset) {
 396         unsigned char *raw = rdataset->private3;
 397         unsigned int count;
 398
 399         count = raw[0] * 256 + raw[1];
 400         if (count == 0) {
 401                 rdataset->private5 = NULL;
 402                 return (ISC_R_NOMORE);
 403         }
 404         raw += 2;
 405         /*
 406          * The privateuint4 field is the number of rdata beyond the cursor
 407          * position, so we decrement the total count by one before storing
 408          * it.
 409          */
 410         count--;
 411         rdataset->privateuint4 = count;
 412         rdataset->private5 = raw;
 413
 414         return (ISC_R_SUCCESS);
 415 }
 416
 417 static isc_result_t
 418 rdataset_next(dns_rdataset_t *rdataset) {
 419         unsigned int count;
 420         unsigned int length;
 421         unsigned char *raw;
 422
 423         count = rdataset->privateuint4;
 424         if (count == 0)
 425                 return (ISC_R_NOMORE);
 426         count--;
 427         rdataset->privateuint4 = count;
 428         raw = rdataset->private5;
 429         length = raw[0] * 256 + raw[1];
 430         raw += length + 2;
 431         rdataset->private5 = raw;
 432
 433         return (ISC_R_SUCCESS);
 434 }
 435
 436 static void
 437 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 438         unsigned char *raw = rdataset->private5;
 439         isc_region_t r;
 440
 441         REQUIRE(raw != NULL);
 442
 443         r.length = raw[0] * 256 + raw[1];
 444         raw += 2;
 445         r.base = raw;
 446         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 447 }
 448
 449 static void
 450 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 451         *target = *source;
 452
 453         /*
 454          * Reset iterator state.
 455          */
 456         target->privateuint4 = 0;
 457         target->private5 = NULL;
 458 }
 459
 460 static unsigned int
 461 rdataset_count(dns_rdataset_t *rdataset) {
 462         unsigned char *raw = rdataset->private3;
 463         unsigned int count;
 464
 465         count = raw[0] * 256 + raw[1];
 466
 467         return (count);
 468 }
 469
 470 static dns_rdatasetmethods_t rdataset_methods = {
 471         rdataset_disassociate,
 472         rdataset_first,
 473         rdataset_next,
 474         rdataset_current,
 475         rdataset_clone,
 476         rdataset_count,
 477         NULL,
 478         NULL,
 479         NULL,
 480         NULL,
 481         NULL
 482 };
 483
 484 isc_result_t
 485 dns_ncache_getrdataset(dns_rdataset_t *ncacherdataset, dns_name_t *name,
 486                        dns_rdatatype_t type, dns_rdataset_t *rdataset)
 487 {
 488         isc_result_t result;
 489         dns_rdata_t rdata = DNS_RDATA_INIT;
 490         isc_region_t remaining;
 491         isc_buffer_t source;
 492         dns_name_t tname;
 493         dns_rdatatype_t ttype;
 494         unsigned int i, rcount;
 495         isc_uint16_t length;
 496
 497         REQUIRE(ncacherdataset != NULL);
 498         REQUIRE(ncacherdataset->type == 0);
 499         REQUIRE(name != NULL);
 500         REQUIRE(!dns_rdataset_isassociated(rdataset));
 501         REQUIRE(type != dns_rdatatype_rrsig);
 502
 503         result = dns_rdataset_first(ncacherdataset);
 504         if (result != ISC_R_SUCCESS)
 505                 return (result);
 506         dns_rdataset_current(ncacherdataset, &rdata);
 507         INSIST(dns_rdataset_next(ncacherdataset) == ISC_R_NOMORE);
 508         isc_buffer_init(&source, rdata.data, rdata.length);
 509         isc_buffer_add(&source, rdata.length);
 510
 511         do {
 512                 dns_name_init(&tname, NULL);
 513                 isc_buffer_remainingregion(&source, &remaining);
 514                 dns_name_fromregion(&tname, &remaining);
 515                 INSIST(remaining.length >= tname.length);
 516                 isc_buffer_forward(&source, tname.length);
 517                 remaining.length -= tname.length;
 518
 519                 INSIST(remaining.length >= 4);
 520                 ttype = isc_buffer_getuint16(&source);
 521
 522                 if (ttype == type && dns_name_equal(&tname, name)) {
 523                         isc_buffer_remainingregion(&source, &remaining);
 524                         break;
 525                 }
 526
 527                 rcount = isc_buffer_getuint16(&source);
 528                 for (i = 0; i < rcount; i++) {
 529                         isc_buffer_remainingregion(&source, &remaining);
 530                         INSIST(remaining.length >= 2);
 531                         length = isc_buffer_getuint16(&source);
 532                         isc_buffer_remainingregion(&source, &remaining);
 533                         INSIST(remaining.length >= length);
 534                         isc_buffer_forward(&source, length);
 535                 }
 536                 isc_buffer_remainingregion(&source, &remaining);
 537         } while (remaining.length > 0);
 538
 539         if (remaining.length == 0)
 540                 return (ISC_R_NOTFOUND);
 541
 542         rdataset->methods = &rdataset_methods;
 543         rdataset->rdclass = ncacherdataset->rdclass;
 544         rdataset->type = type;
 545         rdataset->covers = 0;
 546         rdataset->ttl = ncacherdataset->ttl;
 547         rdataset->trust = ncacherdataset->trust;
 548         rdataset->private1 = NULL;
 549         rdataset->private2 = NULL;
 550
 551         rdataset->private3 = remaining.base;
 552
 553         /*
 554          * Reset iterator state.
 555          */
 556         rdataset->privateuint4 = 0;
 557         rdataset->private5 = NULL;
 558         return (ISC_R_SUCCESS);
 559 }