2 * iterator/iter_utils.h - iterative resolver module utility functions.
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
6 * This software is open source.
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39 * This file contains functions to assist the iterator module.
40 * Configuration options. Forward zones.
43 #ifndef ITERATOR_ITER_UTILS_H
44 #define ITERATOR_ITER_UTILS_H
45 #include "iterator/iter_resptype.h"
61 struct ub_packed_rrset_key;
63 struct outside_network;
66 * Process config options and set iterator module state.
67 * Sets default values if no config is found.
68 * @param iter_env: iterator module state.
69 * @param cfg: config options.
72 int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg);
75 * Select a valid, nice target to send query to.
76 * Sorting and removing unsuitable targets is combined.
78 * @param iter_env: iterator module global state, with ip6 enabled and
79 * do-not-query-addresses.
80 * @param env: environment with infra cache (lameness, rtt info).
81 * @param dp: delegation point with result list.
82 * @param name: zone name (for lameness check).
83 * @param namelen: length of name.
84 * @param qtype: query type that we want to send.
85 * @param dnssec_lame: set to 1, if a known dnssec-lame server is selected
86 * these are not preferred, but are used as a last resort.
87 * @param chase_to_rd: set to 1 if a known recursion lame server is selected
88 * these are not preferred, but are used as a last resort.
89 * @param open_target: number of currently outstanding target queries.
90 * If we wait for these, perhaps more server addresses become available.
91 * @param blacklist: the IP blacklist to use.
92 * @param prefetch: if not 0, prefetch is in use for this query.
93 * This means the query can have different timing, because prefetch is
94 * not waited upon by the downstream client, and thus a good time to
95 * perform exploration of other targets.
96 * @return best target or NULL if no target.
97 * if not null, that target is removed from the result list in the dp.
99 struct delegpt_addr* iter_server_selection(struct iter_env* iter_env,
100 struct module_env* env, struct delegpt* dp, uint8_t* name,
101 size_t namelen, uint16_t qtype, int* dnssec_lame,
102 int* chase_to_rd, int open_target, struct sock_list* blacklist,
106 * Allocate dns_msg from parsed msg, in regional.
107 * @param pkt: packet.
108 * @param msg: parsed message (cleaned and ready for regional allocation).
109 * @param regional: regional to use for allocation.
110 * @return newly allocated dns_msg, or NULL on memory error.
112 struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg,
113 struct regional* regional);
116 * Copy a dns_msg to this regional.
117 * @param from: dns message, also in regional.
118 * @param regional: regional to use for allocation.
119 * @return newly allocated dns_msg, or NULL on memory error.
121 struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
124 * Allocate a dns_msg with malloc/alloc structure and store in dns cache.
125 * @param env: environment, with alloc structure and dns cache.
126 * @param qinf: query info, the query for which answer is stored.
127 * @param rep: reply in dns_msg from dns_alloc_msg for example.
128 * @param is_referral: If true, then the given message to be stored is a
129 * referral. The cache implementation may use this as a hint.
130 * @param leeway: prefetch TTL leeway to expire old rrsets quicker.
131 * @param pside: true if dp is parentside, thus message is 'fresh' and NS
132 * can be prefetch-updates.
133 * @param region: to copy modified (cache is better) rrs back to.
134 * @param flags: with BIT_CD for dns64 AAAA translated queries.
135 * @param qstarttime: time of query start.
136 * return void, because we are not interested in alloc errors,
137 * the iterator and validator can operate on the results in their
138 * scratch space (the qstate.region) and are not dependent on the cache.
139 * It is useful to log the alloc failure (for the server operator),
140 * but the query resolution can continue without cache storage.
142 void iter_dns_store(struct module_env* env, struct query_info* qinf,
143 struct reply_info* rep, int is_referral, time_t leeway, int pside,
144 struct regional* region, uint16_t flags, time_t qstarttime);
147 * Select randomly with n/m probability.
148 * For shuffle NS records for address fetching.
149 * @param rnd: random table
150 * @param n: probability.
151 * @param m: divisor for probability.
152 * @return true with n/m probability.
154 int iter_ns_probability(struct ub_randstate* rnd, int n, int m);
157 * Mark targets that result in a dependency cycle as done, so they
158 * will not get selected as targets.
159 * @param qstate: query state.
160 * @param dp: delegpt to mark ns in.
162 void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp);
165 * Mark targets that result in a dependency cycle as done, so they
166 * will not get selected as targets. For the parent-side lookups.
167 * @param qstate: query state.
168 * @param dp: delegpt to mark ns in.
170 void iter_mark_pside_cycle_targets(struct module_qstate* qstate,
174 * See if delegation is useful or offers immediately no targets for
176 * @param qinfo: query name and type
177 * @param qflags: query flags with RD flag
178 * @param dp: delegpt to check.
179 * @param supports_ipv4: if we support ipv4 for lookups to the target.
180 * if not, then the IPv4 addresses are useless.
181 * @param supports_ipv6: if we support ipv6 for lookups to the target.
182 * if not, then the IPv6 addresses are useless.
183 * @return true if dp is useless.
185 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
186 struct delegpt* dp, int supports_ipv4, int supports_ipv6);
189 * See if qname has DNSSEC needs. This is true if there is a trust anchor above
190 * it. Whether there is an insecure delegation to the data is unknown.
191 * @param env: environment with anchors.
192 * @param qinfo: query name and class.
193 * @return true if trust anchor above qname, false if no anchor or insecure
196 int iter_qname_indicates_dnssec(struct module_env* env,
197 struct query_info *qinfo);
200 * See if delegation is expected to have DNSSEC information (RRSIGs) in
201 * its answers, or not. Inspects delegation point (name), trust anchors,
202 * and delegation message (DS RRset) to determine this.
203 * @param env: module env with trust anchors.
204 * @param dp: delegation point.
205 * @param msg: delegation message, with DS if a secure referral.
206 * @param dclass: class of query.
207 * @return 1 if dnssec is expected, 0 if not or insecure point above qname.
209 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
210 struct dns_msg* msg, uint16_t dclass);
213 * See if a message contains DNSSEC.
214 * This is examined by looking for RRSIGs. With DNSSEC a valid answer,
215 * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth
216 * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records.
217 * @param msg: message to examine.
218 * @return true if DNSSEC information was found.
220 int iter_msg_has_dnssec(struct dns_msg* msg);
223 * See if a message is known to be from a certain zone.
224 * This looks for SOA or NS rrsets, for answers.
225 * For referrals, when one label is delegated, the zone is detected.
226 * Does not look at signatures.
227 * @param msg: the message to inspect.
228 * @param dp: delegation point with zone name to look for.
229 * @param type: type of message.
230 * @param dclass: class of query.
231 * @return true if message is certain to be from zone in dp->name.
232 * false if not sure (empty msg), or not from the zone.
234 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
235 enum response_type type, uint16_t dclass);
238 * Check if two replies are equal
239 * For fallback procedures
240 * @param p: reply one. The reply has rrset data pointers in region.
241 * Does not check rrset-IDs
242 * @param q: reply two
243 * @param region: scratch buffer.
244 * @return if one and two are equal.
246 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region);
249 * Remove unused bits from the reply if possible.
250 * So that caps-for-id (0x20) fallback is more likely to be successful.
251 * This removes like, the additional section, and NS record in the authority
252 * section if those records are gratuitous (not for a referral).
253 * @param rep: the reply to strip stuff out of.
255 void caps_strip_reply(struct reply_info* rep);
258 * see if reply has a 'useful' rcode for capsforid comparison, so
259 * not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN.
260 * @param rep: reply to check.
261 * @return true if the rcode is a bad type of message.
263 int caps_failed_rcode(struct reply_info* rep);
266 * Store parent-side rrset in separate rrset cache entries for later
267 * last-resort * lookups in case the child-side versions of this information
269 * @param env: environment with cache, time, ...
270 * @param rrset: the rrset to store (copied).
271 * Failure to store is logged, but otherwise ignored.
273 void iter_store_parentside_rrset(struct module_env* env,
274 struct ub_packed_rrset_key* rrset);
277 * Store parent-side NS records from a referral message
278 * @param env: environment with cache, time, ...
279 * @param rep: response with NS rrset.
280 * Failure to store is logged, but otherwise ignored.
282 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep);
285 * Store parent-side negative element, the parentside rrset does not exist,
286 * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag.
287 * @param env: environment with cache, time, ...
288 * @param qinfo: the identity of the rrset that is missing.
289 * @param rep: delegation response or answer response, to glean TTL from.
290 * (malloc) failure is logged but otherwise ignored.
292 void iter_store_parentside_neg(struct module_env* env,
293 struct query_info* qinfo, struct reply_info* rep);
296 * Add parent NS record if that exists in the cache. This is both new
297 * information and acts like a timeout throttle on retries.
298 * @param env: query env with rrset cache and time.
299 * @param dp: delegation point to store result in. Also this dp is used to
300 * see which NS name is needed.
301 * @param region: region to alloc result in.
302 * @param qinfo: pertinent information, the qclass.
303 * @return false on malloc failure.
304 * if true, the routine worked and if such cached information
305 * existed dp->has_parent_side_NS is set true.
307 int iter_lookup_parent_NS_from_cache(struct module_env* env,
308 struct delegpt* dp, struct regional* region, struct query_info* qinfo);
311 * Add parent-side glue if that exists in the cache. This is both new
312 * information and acts like a timeout throttle on retries to fetch them.
313 * @param env: query env with rrset cache and time.
314 * @param dp: delegation point to store result in. Also this dp is used to
315 * see which NS name is needed.
316 * @param region: region to alloc result in.
317 * @param qinfo: pertinent information, the qclass.
318 * @return: true, it worked, no malloc failures, and new addresses (lame)
319 * have been added, giving extra options as query targets.
321 int iter_lookup_parent_glue_from_cache(struct module_env* env,
322 struct delegpt* dp, struct regional* region, struct query_info* qinfo);
325 * Lookup next root-hint or root-forward entry.
326 * @param hints: the hints.
327 * @param fwd: the forwards.
328 * @param c: the class to start searching at. 0 means find first one.
329 * @return false if no classes found, true if found and returned in c.
331 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
335 * Remove DS records that are inappropriate before they are cached.
336 * @param msg: the response to scrub.
337 * @param ns: RRSET that is the NS record for the referral.
338 * if NULL, then all DS records are removed from the authority section.
339 * @param z: zone name that the response is from.
341 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns,
345 * Prepare an NXDOMAIN message to be used for a subdomain answer by removing all
346 * RRs from the ANSWER section.
347 * @param msg: the response to scrub.
349 void iter_scrub_nxdomain(struct dns_msg* msg);
352 * Remove query attempts from all available ips. For 0x20.
353 * @param dp: delegpt.
354 * @param d: decrease.
355 * @param outbound_msg_retry: number of retries of outgoing queries
357 void iter_dec_attempts(struct delegpt* dp, int d, int outbound_msg_retry);
360 * Add retry counts from older delegpt to newer delegpt.
361 * Does not waste time on timeout'd (or other failing) addresses.
362 * @param dp: new delegationpoint.
363 * @param old: old delegationpoint.
364 * @param outbound_msg_retry: number of retries of outgoing queries
366 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old,
367 int outbound_msg_retry);
370 * See if a DS response (type ANSWER) is too low: a nodata answer with
371 * a SOA record in the authority section at-or-below the qchase.qname.
372 * Also returns true if we are not sure (i.e. empty message, CNAME nosig).
373 * @param msg: the response.
374 * @param dp: the dp name is used to check if the RRSIG gives a clue that
375 * it was originated from the correct nameserver.
376 * @return true if too low.
378 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp);
381 * See if delegpt can go down a step to the qname or not
382 * @param qinfo: the query name looked up.
383 * @param dp: checked if the name can go lower to the qname
384 * @return true if can go down, false if that would not be possible.
385 * the current response seems to be the one and only, best possible, response.
387 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp);
390 * Lookup if no_cache is set in stub or fwd.
391 * @param qstate: query state with env with hints and fwds.
392 * @param qinf: query name to lookup for.
393 * @param retdpname: returns NULL or the deepest enclosing name of fwd or stub.
394 * This is the name under which the closest lookup is going to happen.
395 * Used for NXDOMAIN checks, above that it is an nxdomain from a
396 * different server and zone. You can pass NULL to not get it.
397 * @param retdpnamelen: returns the length of the dpname.
398 * @return true if no_cache is set in stub or fwd.
400 int iter_stub_fwd_no_cache(struct module_qstate *qstate,
401 struct query_info *qinf, uint8_t** retdpname, size_t* retdpnamelen);
404 * Set support for IP4 and IP6 depending on outgoing interfaces
405 * in the outside network. If none, no support, so no use to lookup
406 * the AAAA and then attempt to use it if there is no outgoing-interface
408 * @param mods: modstack to find iterator module in.
409 * @param env: module env, find iterator module (if one) in there.
410 * @param outnet: outside network structure.
412 void iterator_set_ip46_support(struct module_stack* mods,
413 struct module_env* env, struct outside_network* outnet);
415 #endif /* ITERATOR_ITER_UTILS_H */