contrib/bind-9.2.4rc7/lib/dns/a6.c

   1 /*
   2  * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001  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: a6.c,v 1.20.2.1 2004/03/09 06:10:59 marka Exp $ */
  19
  20 #include <config.h>
  21
  22 #include <isc/util.h>
  23
  24 #include <dns/a6.h>
  25 #include <dns/name.h>
  26 #include <dns/rdata.h>
  27 #include <dns/rdataset.h>
  28
  29 #define A6CONTEXT_MAGIC         ISC_MAGIC('A', '6', 'X', 'X')
  30 #define VALID_A6CONTEXT(ac)     ISC_MAGIC_VALID(ac, A6CONTEXT_MAGIC)
  31
  32 #define MAX_CHAINS      8
  33 #define MAX_DEPTH       16
  34
  35 static inline void
  36 maybe_disassociate(dns_rdataset_t *rdataset) {
  37         if (dns_rdataset_isassociated(rdataset))
  38                 dns_rdataset_disassociate(rdataset);
  39 }
  40
  41 static isc_result_t
  42 foreach(dns_a6context_t *a6ctx, dns_rdataset_t *parent, unsigned int depth,
  43         unsigned int oprefixlen)
  44 {
  45         dns_rdata_t rdata = DNS_RDATA_INIT;
  46         isc_region_t r;
  47         dns_name_t name;
  48         dns_rdataset_t child;
  49         dns_rdataset_t childsig;
  50         isc_result_t result;
  51         isc_uint8_t prefixlen, octets;
  52         isc_bitstring_t bitstring;
  53         isc_stdtime_t expiration;
  54
  55         expiration = a6ctx->now + parent->ttl;
  56         if (expiration < a6ctx->expiration || a6ctx->expiration == 0)
  57                 a6ctx->expiration = expiration;
  58
  59         depth++;
  60         result = dns_rdataset_first(parent);
  61         while (result == ISC_R_SUCCESS) {
  62                 dns_rdataset_current(parent, &rdata);
  63                 dns_rdata_toregion(&rdata, &r);
  64                 prefixlen = r.base[0];
  65                 if (prefixlen > oprefixlen) {
  66                         /*
  67                          * Trying to go to a longer prefix is illegal.
  68                          */
  69                         goto next_a6;
  70                 }
  71                 if (prefixlen < 128) {
  72                         isc_bitstring_init(&bitstring, &r.base[1],
  73                                            128 - prefixlen, 128 - prefixlen,
  74                                            ISC_TRUE);
  75                         isc_bitstring_copy(&bitstring, 128 - oprefixlen,
  76                                            &a6ctx->bitstring, 128 - oprefixlen,
  77                                            oprefixlen - prefixlen);
  78                 }
  79                 octets = 16 - prefixlen / 8;
  80                 if (prefixlen != 0) {
  81                         if (depth < MAX_DEPTH) {
  82                                 isc_region_consume(&r, octets + 1);
  83                                 dns_name_init(&name, NULL);
  84                                 dns_name_fromregion(&name, &r);
  85                                 dns_rdataset_init(&child);
  86                                 dns_rdataset_init(&childsig);
  87                                 result = (a6ctx->find)(a6ctx->arg, &name,
  88                                                        dns_rdatatype_a6,
  89                                                        a6ctx->now,
  90                                                        &child, &childsig);
  91                                 if (result == ISC_R_SUCCESS) {
  92                                         /*
  93                                          * We've found a new A6 rrset.
  94                                          */
  95                                         if (a6ctx->rrset != NULL)
  96                                                 (a6ctx->rrset)(a6ctx->arg,
  97                                                                &name,
  98                                                                &child,
  99                                                                &childsig);
 100                                         /*
 101                                          * Keep following the chain.
 102                                          */
 103                                         result = foreach(a6ctx, &child, depth,
 104                                                          prefixlen);
 105                                         dns_rdataset_disassociate(&child);
 106                                         maybe_disassociate(&childsig);
 107                                         if (result != ISC_R_SUCCESS)
 108                                                 break;
 109                                 } else if (result == ISC_R_NOTFOUND &&
 110                                            a6ctx->missing != NULL) {
 111                                         /*
 112                                          * We can't follow this chain, because
 113                                          * we don't know the next link.
 114                                          *
 115                                          * We update the 'depth' and
 116                                          * 'prefixlen' values so that the
 117                                          * missing function can make a copy
 118                                          * of the a6context and resume
 119                                          * processing after it has found the
 120                                          * missing a6 context.
 121                                          */
 122                                         a6ctx->depth = depth;
 123                                         a6ctx->prefixlen = prefixlen;
 124                                         (a6ctx->missing)(a6ctx, &name);
 125                                 } else {
 126                                         /*
 127                                          * Either something went wrong, or
 128                                          * we got a negative cache response.
 129                                          * In either case, we can't follow
 130                                          * this chain further, and we don't
 131                                          * want to call the 'missing'
 132                                          * function.
 133                                          *
 134                                          * Note that we currently require that
 135                                          * the target of an A6 record is
 136                                          * a canonical domain name.  If the
 137                                          * find routine returns DNS_R_CNAME or
 138                                          * DNS_R_DNAME, we do NOT follow the
 139                                          * chain.
 140                                          *
 141                                          * We do want to clean up...
 142                                          */
 143                                         maybe_disassociate(&child);
 144                                         maybe_disassociate(&childsig);
 145                                 }
 146                         }
 147                 } else {
 148                         /*
 149                          * We have a complete chain.
 150                          */
 151                         if (a6ctx->address != NULL)
 152                                 (a6ctx->address)(a6ctx);
 153                 }
 154         next_a6:
 155                 dns_rdata_reset(&rdata);
 156                 result = dns_rdataset_next(parent);
 157                 if (result == ISC_R_SUCCESS) {
 158                         a6ctx->chains++;
 159                         if (a6ctx->chains > MAX_CHAINS)
 160                                 return (ISC_R_QUOTA);
 161                 }
 162         }
 163         if (result != ISC_R_NOMORE)
 164                 return (result);
 165         return (ISC_R_SUCCESS);
 166 }
 167
 168 void
 169 dns_a6_init(dns_a6context_t *a6ctx, dns_findfunc_t find, dns_rrsetfunc_t rrset,
 170             dns_in6addrfunc_t address, dns_a6missingfunc_t missing, void *arg)
 171 {
 172         REQUIRE(a6ctx != NULL);
 173         REQUIRE(find != NULL);
 174
 175         a6ctx->magic = A6CONTEXT_MAGIC;
 176         a6ctx->find = find;
 177         a6ctx->rrset = rrset;
 178         a6ctx->missing = missing;
 179         a6ctx->address = address;
 180         a6ctx->arg = arg;
 181         a6ctx->chains = 1;
 182         a6ctx->depth = 0;
 183         a6ctx->now = 0;
 184         a6ctx->expiration = 0;
 185         a6ctx->prefixlen = 128;
 186         isc_bitstring_init(&a6ctx->bitstring,
 187                            (unsigned char *)a6ctx->in6addr.s6_addr,
 188                            128, 128, ISC_TRUE);
 189 }
 190
 191 void
 192 dns_a6_reset(dns_a6context_t *a6ctx) {
 193         REQUIRE(VALID_A6CONTEXT(a6ctx));
 194
 195         a6ctx->chains = 1;
 196         a6ctx->depth = 0;
 197         a6ctx->expiration = 0;
 198         a6ctx->prefixlen = 128;
 199 }
 200
 201 void
 202 dns_a6_invalidate(dns_a6context_t *a6ctx) {
 203         REQUIRE(VALID_A6CONTEXT(a6ctx));
 204
 205         a6ctx->magic = 0;
 206 }
 207
 208 void
 209 dns_a6_copy(dns_a6context_t *source, dns_a6context_t *target) {
 210         REQUIRE(VALID_A6CONTEXT(source));
 211         REQUIRE(VALID_A6CONTEXT(target));
 212
 213         *target = *source;
 214         isc_bitstring_init(&target->bitstring,
 215                            (unsigned char *)target->in6addr.s6_addr,
 216                            128, 128, ISC_TRUE);
 217 }
 218
 219 isc_result_t
 220 dns_a6_foreach(dns_a6context_t *a6ctx, dns_rdataset_t *rdataset,
 221                isc_stdtime_t now)
 222 {
 223         isc_result_t result;
 224
 225         REQUIRE(VALID_A6CONTEXT(a6ctx));
 226         REQUIRE(rdataset->type == dns_rdatatype_a6);
 227
 228         if (now == 0)
 229                 isc_stdtime_get(&now);
 230         a6ctx->now = now;
 231
 232         result = foreach(a6ctx, rdataset, a6ctx->depth, a6ctx->prefixlen);
 233         if (result == ISC_R_QUOTA)
 234                 result = ISC_R_SUCCESS;
 235
 236         return (result);
 237 }