contrib/bind/lib/dns/nsec.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001, 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: nsec.c,v 1.9.128.2 2009/01/06 23:46:47 tbox Exp $ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <isc/string.h>
  25 #include <isc/util.h>
  26
  27 #include <dns/db.h>
  28 #include <dns/nsec.h>
  29 #include <dns/rdata.h>
  30 #include <dns/rdatalist.h>
  31 #include <dns/rdataset.h>
  32 #include <dns/rdatasetiter.h>
  33 #include <dns/rdatastruct.h>
  34 #include <dns/result.h>
  35
  36 #define RETERR(x) do { \
  37         result = (x); \
  38         if (result != ISC_R_SUCCESS) \
  39                 goto failure; \
  40         } while (0)
  41
  42 static void
  43 set_bit(unsigned char *array, unsigned int index, unsigned int bit) {
  44         unsigned int shift, mask;
  45
  46         shift = 7 - (index % 8);
  47         mask = 1 << shift;
  48
  49         if (bit != 0)
  50                 array[index / 8] |= mask;
  51         else
  52                 array[index / 8] &= (~mask & 0xFF);
  53 }
  54
  55 static unsigned int
  56 bit_isset(unsigned char *array, unsigned int index) {
  57         unsigned int byte, shift, mask;
  58
  59         byte = array[index / 8];
  60         shift = 7 - (index % 8);
  61         mask = 1 << shift;
  62
  63         return ((byte & mask) != 0);
  64 }
  65
  66 isc_result_t
  67 dns_nsec_buildrdata(dns_db_t *db, dns_dbversion_t *version,
  68                     dns_dbnode_t *node, dns_name_t *target,
  69                     unsigned char *buffer, dns_rdata_t *rdata)
  70 {
  71         isc_result_t result;
  72         dns_rdataset_t rdataset;
  73         isc_region_t r;
  74         unsigned int i, window;
  75         int octet;
  76
  77         unsigned char *nsec_bits, *bm;
  78         unsigned int max_type;
  79         dns_rdatasetiter_t *rdsiter;
  80
  81         memset(buffer, 0, DNS_NSEC_BUFFERSIZE);
  82         dns_name_toregion(target, &r);
  83         memcpy(buffer, r.base, r.length);
  84         r.base = buffer;
  85         /*
  86          * Use the end of the space for a raw bitmap leaving enough
  87          * space for the window identifiers and length octets.
  88          */
  89         bm = r.base + r.length + 512;
  90         nsec_bits = r.base + r.length;
  91         set_bit(bm, dns_rdatatype_nsec, 1);
  92         max_type = dns_rdatatype_nsec;
  93         dns_rdataset_init(&rdataset);
  94         rdsiter = NULL;
  95         result = dns_db_allrdatasets(db, node, version, 0, &rdsiter);
  96         if (result != ISC_R_SUCCESS)
  97                 return (result);
  98         for (result = dns_rdatasetiter_first(rdsiter);
  99              result == ISC_R_SUCCESS;
 100              result = dns_rdatasetiter_next(rdsiter))
 101         {
 102                 dns_rdatasetiter_current(rdsiter, &rdataset);
 103                 if (rdataset.type != dns_rdatatype_nsec) {
 104                         if (rdataset.type > max_type)
 105                                 max_type = rdataset.type;
 106                         set_bit(bm, rdataset.type, 1);
 107                 }
 108                 dns_rdataset_disassociate(&rdataset);
 109         }
 110
 111         /*
 112          * At zone cuts, deny the existence of glue in the parent zone.
 113          */
 114         if (bit_isset(bm, dns_rdatatype_ns) &&
 115             ! bit_isset(bm, dns_rdatatype_soa)) {
 116                 for (i = 0; i <= max_type; i++) {
 117                         if (bit_isset(bm, i) &&
 118                             ! dns_rdatatype_iszonecutauth((dns_rdatatype_t)i))
 119                                 set_bit(bm, i, 0);
 120                 }
 121         }
 122
 123         dns_rdatasetiter_destroy(&rdsiter);
 124         if (result != ISC_R_NOMORE)
 125                 return (result);
 126
 127         for (window = 0; window < 256; window++) {
 128                 if (window * 256 > max_type)
 129                         break;
 130                 for (octet = 31; octet >= 0; octet--)
 131                         if (bm[window * 32 + octet] != 0)
 132                                 break;
 133                 if (octet < 0)
 134                         continue;
 135                 nsec_bits[0] = window;
 136                 nsec_bits[1] = octet + 1;
 137                 /*
 138                  * Note: potential overlapping move.
 139                  */
 140                 memmove(&nsec_bits[2], &bm[window * 32], octet + 1);
 141                 nsec_bits += 3 + octet;
 142         }
 143         r.length = nsec_bits - r.base;
 144         INSIST(r.length <= DNS_NSEC_BUFFERSIZE);
 145         dns_rdata_fromregion(rdata,
 146                              dns_db_class(db),
 147                              dns_rdatatype_nsec,
 148                              &r);
 149
 150         return (ISC_R_SUCCESS);
 151 }
 152
 153
 154 isc_result_t
 155 dns_nsec_build(dns_db_t *db, dns_dbversion_t *version, dns_dbnode_t *node,
 156                dns_name_t *target, dns_ttl_t ttl)
 157 {
 158         isc_result_t result;
 159         dns_rdata_t rdata = DNS_RDATA_INIT;
 160         unsigned char data[DNS_NSEC_BUFFERSIZE];
 161         dns_rdatalist_t rdatalist;
 162         dns_rdataset_t rdataset;
 163
 164         dns_rdataset_init(&rdataset);
 165         dns_rdata_init(&rdata);
 166
 167         RETERR(dns_nsec_buildrdata(db, version, node, target, data, &rdata));
 168
 169         rdatalist.rdclass = dns_db_class(db);
 170         rdatalist.type = dns_rdatatype_nsec;
 171         rdatalist.covers = 0;
 172         rdatalist.ttl = ttl;
 173         ISC_LIST_INIT(rdatalist.rdata);
 174         ISC_LIST_APPEND(rdatalist.rdata, &rdata, link);
 175         RETERR(dns_rdatalist_tordataset(&rdatalist, &rdataset));
 176         result = dns_db_addrdataset(db, node, version, 0, &rdataset,
 177                                     0, NULL);
 178         if (result == DNS_R_UNCHANGED)
 179                 result = ISC_R_SUCCESS;
 180         RETERR(result);
 181  failure:
 182         if (dns_rdataset_isassociated(&rdataset))
 183                 dns_rdataset_disassociate(&rdataset);
 184         return (result);
 185 }
 186
 187 isc_boolean_t
 188 dns_nsec_typepresent(dns_rdata_t *nsec, dns_rdatatype_t type) {
 189         dns_rdata_nsec_t nsecstruct;
 190         isc_result_t result;
 191         isc_boolean_t present;
 192         unsigned int i, len, window;
 193
 194         REQUIRE(nsec != NULL);
 195         REQUIRE(nsec->type == dns_rdatatype_nsec);
 196
 197         /* This should never fail */
 198         result = dns_rdata_tostruct(nsec, &nsecstruct, NULL);
 199         INSIST(result == ISC_R_SUCCESS);
 200
 201         present = ISC_FALSE;
 202         for (i = 0; i < nsecstruct.len; i += len) {
 203                 INSIST(i + 2 <= nsecstruct.len);
 204                 window = nsecstruct.typebits[i];
 205                 len = nsecstruct.typebits[i + 1];
 206                 INSIST(len > 0 && len <= 32);
 207                 i += 2;
 208                 INSIST(i + len <= nsecstruct.len);
 209                 if (window * 256 > type)
 210                         break;
 211                 if ((window + 1) * 256 <= type)
 212                         continue;
 213                 if (type < (window * 256) + len * 8)
 214                         present = ISC_TF(bit_isset(&nsecstruct.typebits[i],
 215                                                    type % 256));
 216                 break;
 217         }
 218         dns_rdata_freestruct(&nsecstruct);
 219         return (present);
 220 }