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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.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
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.
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.
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.
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
;
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.
70 int iter_apply_cfg(struct iter_env
* iter_env
, struct config_file
* cfg
);
73 * Select a valid, nice target to send query to.
74 * Sorting and removing unsuitable targets is combined.
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.
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
);
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.
105 struct dns_msg
* dns_alloc_msg(struct sldns_buffer
* pkt
, struct msg_parse
* msg
,
106 struct regional
* regional
);
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.
114 struct dns_msg
* dns_copy_msg(struct dns_msg
* from
, struct regional
* regional
);
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.
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
);
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.
146 int iter_ns_probability(struct ub_randstate
* rnd
, int n
, int m
);
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.
154 void iter_mark_cycle_targets(struct module_qstate
* qstate
, struct delegpt
* dp
);
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.
162 void iter_mark_pside_cycle_targets(struct module_qstate
* qstate
,
166 * See if delegation is useful or offers immediately no targets for
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.
173 int iter_dp_is_useless(struct query_info
* qinfo
, uint16_t qflags
,
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.
186 int iter_indicates_dnssec(struct module_env
* env
, struct delegpt
* dp
,
187 struct dns_msg
* msg
, uint16_t dclass
);
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.
197 int iter_msg_has_dnssec(struct dns_msg
* msg
);
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.
211 int iter_msg_from_zone(struct dns_msg
* msg
, struct delegpt
* dp
,
212 enum response_type type
, uint16_t dclass
);
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.
223 int reply_equal(struct reply_info
* p
, struct reply_info
* q
, struct regional
* region
);
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
229 * @param env: environment with cache, time, ...
230 * @param rrset: the rrset to store (copied).
231 * Failure to store is logged, but otherwise ignored.
233 void iter_store_parentside_rrset(struct module_env
* env
,
234 struct ub_packed_rrset_key
* rrset
);
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.
242 void iter_store_parentside_NS(struct module_env
* env
, struct reply_info
* rep
);
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.
252 void iter_store_parentside_neg(struct module_env
* env
,
253 struct query_info
* qinfo
, struct reply_info
* rep
);
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.
267 int iter_lookup_parent_NS_from_cache(struct module_env
* env
,
268 struct delegpt
* dp
, struct regional
* region
, struct query_info
* qinfo
);
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.
281 int iter_lookup_parent_glue_from_cache(struct module_env
* env
,
282 struct delegpt
* dp
, struct regional
* region
, struct query_info
* qinfo
);
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.
291 int iter_get_next_root(struct iter_hints
* hints
, struct iter_forwards
* fwd
,
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.
301 void iter_scrub_ds(struct dns_msg
* msg
, struct ub_packed_rrset_key
* ns
,
305 * Remove query attempts from all available ips. For 0x20.
306 * @param dp: delegpt.
307 * @param d: decrease.
309 void iter_dec_attempts(struct delegpt
* dp
, int d
);
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.
317 void iter_merge_retry_counts(struct delegpt
* dp
, struct delegpt
* old
);
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.
328 int iter_ds_toolow(struct dns_msg
* msg
, struct delegpt
* dp
);
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.
337 int iter_dp_cangodown(struct query_info
* qinfo
, struct delegpt
* dp
);
339 #endif /* ITERATOR_ITER_UTILS_H */