unbound/iterator/iter_utils.h

   1 /*
   2  * iterator/iter_utils.h - iterative resolver module utility functions.
   3  *
   4  * Copyright (c) 2007, NLnet Labs. All rights reserved.
   5  *
   6  * This software is open source.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice,
  13  * this list of conditions and the following disclaimer.
  14  *
  15  * Redistributions in binary form must reproduce the above copyright notice,
  16  * this list of conditions and the following disclaimer in the documentation
  17  * and/or other materials provided with the distribution.
  18  *
  19  * Neither the name of the NLNET LABS nor the names of its contributors may
  20  * be used to endorse or promote products derived from this software without
  21  * specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 /**
  37  * \file
  38  *
  39  * This file contains functions to assist the iterator module.
  40  * Configuration options. Forward zones.
  41  */
  42
  43 #ifndef ITERATOR_ITER_UTILS_H
  44 #define ITERATOR_ITER_UTILS_H
  45 #include "iterator/iter_resptype.h"
  46 struct sldns_buffer;
  47 struct iter_env;
  48 struct iter_hints;
  49 struct iter_forwards;
  50 struct config_file;
  51 struct module_env;
  52 struct delegpt_addr;
  53 struct delegpt;
  54 struct regional;
  55 struct msg_parse;
  56 struct ub_randstate;
  57 struct query_info;
  58 struct reply_info;
  59 struct module_qstate;
  60 struct sock_list;
  61 struct ub_packed_rrset_key;
  62
  63 /**
  64  * Process config options and set iterator module state.
  65  * Sets default values if no config is found.
  66  * @param iter_env: iterator module state.
  67  * @param cfg: config options.
  68  * @return 0 on error.
  69  */
  70 int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg);
  71
  72 /**
  73  * Select a valid, nice target to send query to.
  74  * Sorting and removing unsuitable targets is combined.
  75  *
  76  * @param iter_env: iterator module global state, with ip6 enabled and
  77  *      do-not-query-addresses.
  78  * @param env: environment with infra cache (lameness, rtt info).
  79  * @param dp: delegation point with result list.
  80  * @param name: zone name (for lameness check).
  81  * @param namelen: length of name.
  82  * @param qtype: query type that we want to send.
  83  * @param dnssec_lame: set to 1, if a known dnssec-lame server is selected
  84  *      these are not preferred, but are used as a last resort.
  85  * @param chase_to_rd: set to 1 if a known recursion lame server is selected
  86  *      these are not preferred, but are used as a last resort.
  87  * @param open_target: number of currently outstanding target queries.
  88  *      If we wait for these, perhaps more server addresses become available.
  89  * @param blacklist: the IP blacklist to use.
  90  * @return best target or NULL if no target.
  91  *      if not null, that target is removed from the result list in the dp.
  92  */
  93 struct delegpt_addr* iter_server_selection(struct iter_env* iter_env,
  94         struct module_env* env, struct delegpt* dp, uint8_t* name,
  95         size_t namelen, uint16_t qtype, int* dnssec_lame,
  96         int* chase_to_rd, int open_target, struct sock_list* blacklist);
  97
  98 /**
  99  * Allocate dns_msg from parsed msg, in regional.
 100  * @param pkt: packet.
 101  * @param msg: parsed message (cleaned and ready for regional allocation).
 102  * @param regional: regional to use for allocation.
 103  * @return newly allocated dns_msg, or NULL on memory error.
 104  */
 105 struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg,
 106         struct regional* regional);
 107
 108 /**
 109  * Copy a dns_msg to this regional.
 110  * @param from: dns message, also in regional.
 111  * @param regional: regional to use for allocation.
 112  * @return newly allocated dns_msg, or NULL on memory error.
 113  */
 114 struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
 115
 116 /**
 117  * Allocate a dns_msg with malloc/alloc structure and store in dns cache.
 118  * @param env: environment, with alloc structure and dns cache.
 119  * @param qinf: query info, the query for which answer is stored.
 120  * @param rep: reply in dns_msg from dns_alloc_msg for example.
 121  * @param is_referral: If true, then the given message to be stored is a
 122  *      referral. The cache implementation may use this as a hint.
 123  * @param leeway: prefetch TTL leeway to expire old rrsets quicker.
 124  * @param pside: true if dp is parentside, thus message is 'fresh' and NS
 125  *      can be prefetch-updates.
 126  * @param region: to copy modified (cache is better) rrs back to.
 127  * @param flags: with BIT_CD for dns64 AAAA translated queries.
 128  * @return void, because we are not interested in alloc errors,
 129  *      the iterator and validator can operate on the results in their
 130  *      scratch space (the qstate.region) and are not dependent on the cache.
 131  *      It is useful to log the alloc failure (for the server operator),
 132  *      but the query resolution can continue without cache storage.
 133  */
 134 void iter_dns_store(struct module_env* env, struct query_info* qinf,
 135         struct reply_info* rep, int is_referral, time_t leeway, int pside,
 136         struct regional* region, uint16_t flags);
 137
 138 /**
 139  * Select randomly with n/m probability.
 140  * For shuffle NS records for address fetching.
 141  * @param rnd: random table
 142  * @param n: probability.
 143  * @param m: divisor for probability.
 144  * @return true with n/m probability.
 145  */
 146 int iter_ns_probability(struct ub_randstate* rnd, int n, int m);
 147
 148 /**
 149  * Mark targets that result in a dependency cycle as done, so they
 150  * will not get selected as targets.
 151  * @param qstate: query state.
 152  * @param dp: delegpt to mark ns in.
 153  */
 154 void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp);
 155
 156 /**
 157  * Mark targets that result in a dependency cycle as done, so they
 158  * will not get selected as targets.  For the parent-side lookups.
 159  * @param qstate: query state.
 160  * @param dp: delegpt to mark ns in.
 161  */
 162 void iter_mark_pside_cycle_targets(struct module_qstate* qstate,
 163         struct delegpt* dp);
 164
 165 /**
 166  * See if delegation is useful or offers immediately no targets for
 167  * further recursion.
 168  * @param qinfo: query name and type
 169  * @param qflags: query flags with RD flag
 170  * @param dp: delegpt to check.
 171  * @return true if dp is useless.
 172  */
 173 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
 174         struct delegpt* dp);
 175
 176 /**
 177  * See if delegation is expected to have DNSSEC information (RRSIGs) in
 178  * its answers, or not. Inspects delegation point (name), trust anchors,
 179  * and delegation message (DS RRset) to determine this.
 180  * @param env: module env with trust anchors.
 181  * @param dp: delegation point.
 182  * @param msg: delegation message, with DS if a secure referral.
 183  * @param dclass: class of query.
 184  * @return 1 if dnssec is expected, 0 if not.
 185  */
 186 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
 187         struct dns_msg* msg, uint16_t dclass);
 188
 189 /**
 190  * See if a message contains DNSSEC.
 191  * This is examined by looking for RRSIGs. With DNSSEC a valid answer,
 192  * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth
 193  * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records.
 194  * @param msg: message to examine.
 195  * @return true if DNSSEC information was found.
 196  */
 197 int iter_msg_has_dnssec(struct dns_msg* msg);
 198
 199 /**
 200  * See if a message is known to be from a certain zone.
 201  * This looks for SOA or NS rrsets, for answers.
 202  * For referrals, when one label is delegated, the zone is detected.
 203  * Does not look at signatures.
 204  * @param msg: the message to inspect.
 205  * @param dp: delegation point with zone name to look for.
 206  * @param type: type of message.
 207  * @param dclass: class of query.
 208  * @return true if message is certain to be from zone in dp->name.
 209  *      false if not sure (empty msg), or not from the zone.
 210  */
 211 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
 212         enum response_type type, uint16_t dclass);
 213
 214 /**
 215  * Check if two replies are equal
 216  * For fallback procedures
 217  * @param p: reply one. The reply has rrset data pointers in region.
 218  *      Does not check rrset-IDs
 219  * @param q: reply two
 220  * @param region: scratch buffer.
 221  * @return if one and two are equal.
 222  */
 223 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region);
 224
 225 /**
 226  * Store parent-side rrset in seperate rrset cache entries for later
 227  * last-resort * lookups in case the child-side versions of this information
 228  * fails.
 229  * @param env: environment with cache, time, ...
 230  * @param rrset: the rrset to store (copied).
 231  * Failure to store is logged, but otherwise ignored.
 232  */
 233 void iter_store_parentside_rrset(struct module_env* env,
 234         struct ub_packed_rrset_key* rrset);
 235
 236 /**
 237  * Store parent-side NS records from a referral message
 238  * @param env: environment with cache, time, ...
 239  * @param rep: response with NS rrset.
 240  * Failure to store is logged, but otherwise ignored.
 241  */
 242 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep);
 243
 244 /**
 245  * Store parent-side negative element, the parentside rrset does not exist,
 246  * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag.
 247  * @param env: environment with cache, time, ...
 248  * @param qinfo: the identity of the rrset that is missing.
 249  * @param rep: delegation response or answer response, to glean TTL from.
 250  * (malloc) failure is logged but otherwise ignored.
 251  */
 252 void iter_store_parentside_neg(struct module_env* env,
 253         struct query_info* qinfo, struct reply_info* rep);
 254
 255 /**
 256  * Add parent NS record if that exists in the cache.  This is both new
 257  * information and acts like a timeout throttle on retries.
 258  * @param env: query env with rrset cache and time.
 259  * @param dp: delegation point to store result in.  Also this dp is used to
 260  *      see which NS name is needed.
 261  * @param region: region to alloc result in.
 262  * @param qinfo: pertinent information, the qclass.
 263  * @return false on malloc failure.
 264  *      if true, the routine worked and if such cached information
 265  *      existed dp->has_parent_side_NS is set true.
 266  */
 267 int iter_lookup_parent_NS_from_cache(struct module_env* env,
 268         struct delegpt* dp, struct regional* region, struct query_info* qinfo);
 269
 270 /**
 271  * Add parent-side glue if that exists in the cache.  This is both new
 272  * information and acts like a timeout throttle on retries to fetch them.
 273  * @param env: query env with rrset cache and time.
 274  * @param dp: delegation point to store result in.  Also this dp is used to
 275  *      see which NS name is needed.
 276  * @param region: region to alloc result in.
 277  * @param qinfo: pertinent information, the qclass.
 278  * @return: true, it worked, no malloc failures, and new addresses (lame)
 279  *      have been added, giving extra options as query targets.
 280  */
 281 int iter_lookup_parent_glue_from_cache(struct module_env* env,
 282         struct delegpt* dp, struct regional* region, struct query_info* qinfo);
 283
 284 /**
 285  * Lookup next root-hint or root-forward entry.
 286  * @param hints: the hints.
 287  * @param fwd: the forwards.
 288  * @param c: the class to start searching at. 0 means find first one.
 289  * @return false if no classes found, true if found and returned in c.
 290  */
 291 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
 292         uint16_t* c);
 293
 294 /**
 295  * Remove DS records that are inappropriate before they are cached.
 296  * @param msg: the response to scrub.
 297  * @param ns: RRSET that is the NS record for the referral.
 298  *      if NULL, then all DS records are removed from the authority section.
 299  * @param z: zone name that the response is from.
 300  */
 301 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns,
 302         uint8_t* z);
 303
 304 /**
 305  * Remove query attempts from all available ips. For 0x20.
 306  * @param dp: delegpt.
 307  * @param d: decrease.
 308  */
 309 void iter_dec_attempts(struct delegpt* dp, int d);
 310
 311 /**
 312  * Add retry counts from older delegpt to newer delegpt.
 313  * Does not waste time on timeout'd (or other failing) addresses.
 314  * @param dp: new delegationpoint.
 315  * @param old: old delegationpoint.
 316  */
 317 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old);
 318
 319 /**
 320  * See if a DS response (type ANSWER) is too low: a nodata answer with
 321  * a SOA record in the authority section at-or-below the qchase.qname.
 322  * Also returns true if we are not sure (i.e. empty message, CNAME nosig).
 323  * @param msg: the response.
 324  * @param dp: the dp name is used to check if the RRSIG gives a clue that
 325  *      it was originated from the correct nameserver.
 326  * @return true if too low.
 327  */
 328 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp);
 329
 330 /**
 331  * See if delegpt can go down a step to the qname or not
 332  * @param qinfo: the query name looked up.
 333  * @param dp: checked if the name can go lower to the qname
 334  * @return true if can go down, false if that would not be possible.
 335  * the current response seems to be the one and only, best possible, response.
 336  */
 337 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp);
 338
 339 #endif /* ITERATOR_ITER_UTILS_H */