contrib/bind-9.2.4rc7/lib/dns/ncache.c

   1 /*
   2  * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and 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 1.24.2.6 2004/03/09 06:11:04 marka Exp $ */
  19
  20 #include <config.h>
  21
  22 #include <isc/buffer.h>
  23 #include <isc/util.h>
  24
  25 #include <dns/db.h>
  26 #include <dns/message.h>
  27 #include <dns/ncache.h>
  28 #include <dns/rdata.h>
  29 #include <dns/rdatalist.h>
  30 #include <dns/rdataset.h>
  31
  32 /*
  33  * The format of an ncache rdata is a sequence of one or more records of
  34  * the following format:
  35  *
  36  *      owner name
  37  *      type
  38  *      rdata count
  39  *              rdata length                    These two occur 'rdata count'
  40  *              rdata                           times.
  41  *
  42  */
  43
  44 static inline isc_result_t
  45 copy_rdataset(dns_rdataset_t *rdataset, isc_buffer_t *buffer) {
  46         isc_result_t result;
  47         unsigned int count;
  48         isc_region_t ar, r;
  49         dns_rdata_t rdata = DNS_RDATA_INIT;
  50
  51         /*
  52          * Copy the rdataset count to the buffer.
  53          */
  54         isc_buffer_availableregion(buffer, &ar);
  55         if (ar.length < 2)
  56                 return (ISC_R_NOSPACE);
  57         count = dns_rdataset_count(rdataset);
  58         INSIST(count <= 65535);
  59         isc_buffer_putuint16(buffer, (isc_uint16_t)count);
  60
  61         result = dns_rdataset_first(rdataset);
  62         while (result == ISC_R_SUCCESS) {
  63                 dns_rdataset_current(rdataset, &rdata);
  64                 dns_rdata_toregion(&rdata, &r);
  65                 INSIST(r.length <= 65535);
  66                 isc_buffer_availableregion(buffer, &ar);
  67                 if (ar.length < 2)
  68                         return (ISC_R_NOSPACE);
  69                 /*
  70                  * Copy the rdata length to the buffer.
  71                  */
  72                 isc_buffer_putuint16(buffer, (isc_uint16_t)r.length);
  73                 /*
  74                  * Copy the rdata to the buffer.
  75                  */
  76                 result = isc_buffer_copyregion(buffer, &r);
  77                 if (result != ISC_R_SUCCESS)
  78                         return (result);
  79                 dns_rdata_reset(&rdata);
  80                 result = dns_rdataset_next(rdataset);
  81         }
  82         if (result != ISC_R_NOMORE)
  83                 return (result);
  84
  85         return (ISC_R_SUCCESS);
  86 }
  87
  88 isc_result_t
  89 dns_ncache_add(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
  90                dns_rdatatype_t covers, isc_stdtime_t now, dns_ttl_t maxttl,
  91                dns_rdataset_t *addedrdataset)
  92 {
  93         isc_result_t result;
  94         isc_buffer_t buffer;
  95         isc_region_t r;
  96         dns_rdataset_t *rdataset;
  97         dns_rdatatype_t type;
  98         dns_name_t *name;
  99         dns_ttl_t ttl;
 100         dns_trust_t trust;
 101         dns_rdata_t rdata = DNS_RDATA_INIT;
 102         dns_rdataset_t ncrdataset;
 103         dns_rdatalist_t ncrdatalist;
 104         unsigned char data[4096];
 105
 106         /*
 107          * Convert the authority data from 'message' into a negative cache
 108          * rdataset, and store it in 'cache' at 'node'.
 109          */
 110
 111         REQUIRE(message != NULL);
 112
 113         /*
 114          * We assume that all data in the authority section has been
 115          * validated by the caller.
 116          */
 117
 118         /*
 119          * First, build an ncache rdata in buffer.
 120          */
 121         ttl = maxttl;
 122         trust = 0xffff;
 123         isc_buffer_init(&buffer, data, sizeof(data));
 124         if (message->counts[DNS_SECTION_AUTHORITY])
 125                 result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
 126         else
 127                 result = ISC_R_NOMORE;
 128         while (result == ISC_R_SUCCESS) {
 129                 name = NULL;
 130                 dns_message_currentname(message, DNS_SECTION_AUTHORITY,
 131                                         &name);
 132                 if ((name->attributes & DNS_NAMEATTR_NCACHE) != 0) {
 133                         for (rdataset = ISC_LIST_HEAD(name->list);
 134                              rdataset != NULL;
 135                              rdataset = ISC_LIST_NEXT(rdataset, link)) {
 136                                 if ((rdataset->attributes &
 137                                      DNS_RDATASETATTR_NCACHE) == 0)
 138                                         continue;
 139                                 type = rdataset->type;
 140                                 if (type == dns_rdatatype_sig)
 141                                         type = rdataset->covers;
 142                                 if (type == dns_rdatatype_soa ||
 143                                     type == dns_rdatatype_nxt) {
 144                                         if (ttl > rdataset->ttl)
 145                                                 ttl = rdataset->ttl;
 146                                         if (trust > rdataset->trust)
 147                                                 trust = rdataset->trust;
 148                                         /*
 149                                          * Copy the owner name to the buffer.
 150                                          */
 151                                         dns_name_toregion(name, &r);
 152                                         result = isc_buffer_copyregion(&buffer,
 153                                                                        &r);
 154                                         if (result != ISC_R_SUCCESS)
 155                                                 return (result);
 156                                         /*
 157                                          * Copy the type to the buffer.
 158                                          */
 159                                         isc_buffer_availableregion(&buffer,
 160                                                                    &r);
 161                                         if (r.length < 2)
 162                                                 return (ISC_R_NOSPACE);
 163                                         isc_buffer_putuint16(&buffer,
 164                                                              rdataset->type);
 165                                         /*
 166                                          * Copy the rdataset into the buffer.
 167                                          */
 168                                         result = copy_rdataset(rdataset,
 169                                                                &buffer);
 170                                         if (result != ISC_R_SUCCESS)
 171                                                 return (result);
 172                                 }
 173                         }
 174                 }
 175                 result = dns_message_nextname(message, DNS_SECTION_AUTHORITY);
 176         }
 177         if (result != ISC_R_NOMORE)
 178                 return (result);
 179
 180         if (trust == 0xffff) {
 181                 /*
 182                  * We didn't find any authority data from which to create a
 183                  * negative cache rdataset.  In particular, we have no SOA.
 184                  *
 185                  * We trust that the caller wants negative caching, so this
 186                  * means we have a "type 3 nxdomain" or "type 3 nodata"
 187                  * response (see RFC 2308 for details).
 188                  *
 189                  * We will now build a suitable negative cache rdataset that
 190                  * will cause zero bytes to be emitted when converted to
 191                  * wire format.
 192                  */
 193
 194                 /*
 195                  * The ownername must exist, but it doesn't matter what value
 196                  * it has.  We use the root name.
 197                  */
 198                 dns_name_toregion(dns_rootname, &r);
 199                 result = isc_buffer_copyregion(&buffer, &r);
 200                 if (result != ISC_R_SUCCESS)
 201                         return (result);
 202                 /*
 203                  * Copy the type and a zero rdata count to the buffer.
 204                  */
 205                 isc_buffer_availableregion(&buffer, &r);
 206                 if (r.length < 4)
 207                         return (ISC_R_NOSPACE);
 208                 isc_buffer_putuint16(&buffer, 0);
 209                 isc_buffer_putuint16(&buffer, 0);
 210                 /*
 211                  * RFC 2308, section 5, says that negative answers without
 212                  * SOAs should not be cached.
 213                  */
 214                 ttl = 0;
 215                 /*
 216                  * Set trust.
 217                  */
 218                 if ((message->flags & DNS_MESSAGEFLAG_AA) != 0 &&
 219                     message->counts[DNS_SECTION_ANSWER] == 0) {
 220                         /*
 221                          * The response has aa set and we haven't followed
 222                          * any CNAME or DNAME chains.
 223                          */
 224                         trust = dns_trust_authauthority;
 225                 } else
 226                         trust = dns_trust_additional;
 227         }
 228
 229         /*
 230          * Now add it to the cache.
 231          */
 232         INSIST(trust != 0xffff);
 233         isc_buffer_usedregion(&buffer, &r);
 234         rdata.data = r.base;
 235         rdata.length = r.length;
 236         rdata.rdclass = dns_db_class(cache);
 237         rdata.type = 0;
 238         rdata.flags = 0;
 239
 240         ncrdatalist.rdclass = rdata.rdclass;
 241         ncrdatalist.type = 0;
 242         ncrdatalist.covers = covers;
 243         ncrdatalist.ttl = ttl;
 244         ISC_LIST_INIT(ncrdatalist.rdata);
 245         ISC_LINK_INIT(&ncrdatalist, link);
 246
 247         ISC_LIST_APPEND(ncrdatalist.rdata, &rdata, link);
 248
 249         dns_rdataset_init(&ncrdataset);
 250         dns_rdatalist_tordataset(&ncrdatalist, &ncrdataset);
 251         ncrdataset.trust = trust;
 252         if (message->rcode == dns_rcode_nxdomain)
 253                 ncrdataset.attributes |= DNS_RDATASETATTR_NXDOMAIN;
 254
 255         return (dns_db_addrdataset(cache, node, NULL, now, &ncrdataset,
 256                                    0, addedrdataset));
 257 }
 258
 259 isc_result_t
 260 dns_ncache_towire(dns_rdataset_t *rdataset, dns_compress_t *cctx,
 261                   isc_buffer_t *target, unsigned int *countp)
 262 {
 263         dns_rdata_t rdata = DNS_RDATA_INIT;
 264         isc_result_t result;
 265         isc_region_t remaining, tavailable;
 266         isc_buffer_t source, savedbuffer, rdlen;
 267         dns_name_t name;
 268         dns_rdatatype_t type;
 269         unsigned int i, rcount, count;
 270
 271         /*
 272          * Convert the negative caching rdataset 'rdataset' to wire format,
 273          * compressing names as specified in 'cctx', and storing the result in
 274          * 'target'.
 275          */
 276
 277         REQUIRE(rdataset != NULL);
 278         REQUIRE(rdataset->type == 0);
 279
 280         result = dns_rdataset_first(rdataset);
 281         if (result != ISC_R_SUCCESS)
 282                 return (result);
 283         dns_rdataset_current(rdataset, &rdata);
 284         INSIST(dns_rdataset_next(rdataset) == ISC_R_NOMORE);
 285         isc_buffer_init(&source, rdata.data, rdata.length);
 286         isc_buffer_add(&source, rdata.length);
 287
 288         savedbuffer = *target;
 289
 290         count = 0;
 291         do {
 292                 dns_name_init(&name, NULL);
 293                 isc_buffer_remainingregion(&source, &remaining);
 294                 dns_name_fromregion(&name, &remaining);
 295                 INSIST(remaining.length >= name.length);
 296                 isc_buffer_forward(&source, name.length);
 297                 remaining.length -= name.length;
 298
 299                 INSIST(remaining.length >= 4);
 300                 type = isc_buffer_getuint16(&source);
 301                 rcount = isc_buffer_getuint16(&source);
 302
 303                 for (i = 0; i < rcount; i++) {
 304                         /*
 305                          * Get the length of this rdata and set up an
 306                          * rdata structure for it.
 307                          */
 308                         isc_buffer_remainingregion(&source, &remaining);
 309                         INSIST(remaining.length >= 2);
 310                         dns_rdata_reset(&rdata);
 311                         rdata.length = isc_buffer_getuint16(&source);
 312                         isc_buffer_remainingregion(&source, &remaining);
 313                         rdata.data = remaining.base;
 314                         rdata.type = type;
 315                         rdata.rdclass = rdataset->rdclass;
 316                         INSIST(remaining.length >= rdata.length);
 317                         isc_buffer_forward(&source, rdata.length);
 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                 isc_buffer_remainingregion(&source, &remaining);
 366         } while (remaining.length > 0);
 367
 368         *countp = count;
 369
 370         return (ISC_R_SUCCESS);
 371
 372  rollback:
 373         INSIST(savedbuffer.used < 65536);
 374         dns_compress_rollback(cctx, (isc_uint16_t)savedbuffer.used);
 375         *countp = 0;
 376         *target = savedbuffer;
 377
 378         return (result);
 379 }