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 * @param prefetch: if not 0, prefetch is in use for this query. 91 * This means the query can have different timing, because prefetch is 92 * not waited upon by the downstream client, and thus a good time to 93 * perform exploration of other targets. 94 * @return best target or NULL if no target. 95 * if not null, that target is removed from the result list in the dp. 96 */ 97 struct delegpt_addr* iter_server_selection(struct iter_env* iter_env, 98 struct module_env* env, struct delegpt* dp, uint8_t* name, 99 size_t namelen, uint16_t qtype, int* dnssec_lame, 100 int* chase_to_rd, int open_target, struct sock_list* blacklist, 101 time_t prefetch); 102 103 /** 104 * Allocate dns_msg from parsed msg, in regional. 105 * @param pkt: packet. 106 * @param msg: parsed message (cleaned and ready for regional allocation). 107 * @param regional: regional to use for allocation. 108 * @return newly allocated dns_msg, or NULL on memory error. 109 */ 110 struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg, 111 struct regional* regional); 112 113 /** 114 * Copy a dns_msg to this regional. 115 * @param from: dns message, also in regional. 116 * @param regional: regional to use for allocation. 117 * @return newly allocated dns_msg, or NULL on memory error. 118 */ 119 struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional); 120 121 /** 122 * Allocate a dns_msg with malloc/alloc structure and store in dns cache. 123 * @param env: environment, with alloc structure and dns cache. 124 * @param qinf: query info, the query for which answer is stored. 125 * @param rep: reply in dns_msg from dns_alloc_msg for example. 126 * @param is_referral: If true, then the given message to be stored is a 127 * referral. The cache implementation may use this as a hint. 128 * @param leeway: prefetch TTL leeway to expire old rrsets quicker. 129 * @param pside: true if dp is parentside, thus message is 'fresh' and NS 130 * can be prefetch-updates. 131 * @param region: to copy modified (cache is better) rrs back to. 132 * @param flags: with BIT_CD for dns64 AAAA translated queries. 133 * @return void, because we are not interested in alloc errors, 134 * the iterator and validator can operate on the results in their 135 * scratch space (the qstate.region) and are not dependent on the cache. 136 * It is useful to log the alloc failure (for the server operator), 137 * but the query resolution can continue without cache storage. 138 */ 139 void iter_dns_store(struct module_env* env, struct query_info* qinf, 140 struct reply_info* rep, int is_referral, time_t leeway, int pside, 141 struct regional* region, uint16_t flags); 142 143 /** 144 * Select randomly with n/m probability. 145 * For shuffle NS records for address fetching. 146 * @param rnd: random table 147 * @param n: probability. 148 * @param m: divisor for probability. 149 * @return true with n/m probability. 150 */ 151 int iter_ns_probability(struct ub_randstate* rnd, int n, int m); 152 153 /** 154 * Mark targets that result in a dependency cycle as done, so they 155 * will not get selected as targets. 156 * @param qstate: query state. 157 * @param dp: delegpt to mark ns in. 158 */ 159 void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp); 160 161 /** 162 * Mark targets that result in a dependency cycle as done, so they 163 * will not get selected as targets. For the parent-side lookups. 164 * @param qstate: query state. 165 * @param dp: delegpt to mark ns in. 166 */ 167 void iter_mark_pside_cycle_targets(struct module_qstate* qstate, 168 struct delegpt* dp); 169 170 /** 171 * See if delegation is useful or offers immediately no targets for 172 * further recursion. 173 * @param qinfo: query name and type 174 * @param qflags: query flags with RD flag 175 * @param dp: delegpt to check. 176 * @return true if dp is useless. 177 */ 178 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags, 179 struct delegpt* dp); 180 181 /** 182 * See if qname has DNSSEC needs. This is true if there is a trust anchor above 183 * it. Whether there is an insecure delegation to the data is unknown. 184 * @param env: environment with anchors. 185 * @param qinfo: query name and class. 186 * @return true if trust anchor above qname, false if no anchor or insecure 187 * point above qname. 188 */ 189 int iter_qname_indicates_dnssec(struct module_env* env, 190 struct query_info *qinfo); 191 192 /** 193 * See if delegation is expected to have DNSSEC information (RRSIGs) in 194 * its answers, or not. Inspects delegation point (name), trust anchors, 195 * and delegation message (DS RRset) to determine this. 196 * @param env: module env with trust anchors. 197 * @param dp: delegation point. 198 * @param msg: delegation message, with DS if a secure referral. 199 * @param dclass: class of query. 200 * @return 1 if dnssec is expected, 0 if not or insecure point above qname. 201 */ 202 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp, 203 struct dns_msg* msg, uint16_t dclass); 204 205 /** 206 * See if a message contains DNSSEC. 207 * This is examined by looking for RRSIGs. With DNSSEC a valid answer, 208 * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth 209 * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records. 210 * @param msg: message to examine. 211 * @return true if DNSSEC information was found. 212 */ 213 int iter_msg_has_dnssec(struct dns_msg* msg); 214 215 /** 216 * See if a message is known to be from a certain zone. 217 * This looks for SOA or NS rrsets, for answers. 218 * For referrals, when one label is delegated, the zone is detected. 219 * Does not look at signatures. 220 * @param msg: the message to inspect. 221 * @param dp: delegation point with zone name to look for. 222 * @param type: type of message. 223 * @param dclass: class of query. 224 * @return true if message is certain to be from zone in dp->name. 225 * false if not sure (empty msg), or not from the zone. 226 */ 227 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp, 228 enum response_type type, uint16_t dclass); 229 230 /** 231 * Check if two replies are equal 232 * For fallback procedures 233 * @param p: reply one. The reply has rrset data pointers in region. 234 * Does not check rrset-IDs 235 * @param q: reply two 236 * @param region: scratch buffer. 237 * @return if one and two are equal. 238 */ 239 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region); 240 241 /** 242 * Remove unused bits from the reply if possible. 243 * So that caps-for-id (0x20) fallback is more likely to be successful. 244 * This removes like, the additional section, and NS record in the authority 245 * section if those records are gratuitous (not for a referral). 246 * @param rep: the reply to strip stuff out of. 247 */ 248 void caps_strip_reply(struct reply_info* rep); 249 250 /** 251 * see if reply has a 'useful' rcode for capsforid comparison, so 252 * not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN. 253 * @param rep: reply to check. 254 * @return true if the rcode is a bad type of message. 255 */ 256 int caps_failed_rcode(struct reply_info* rep); 257 258 /** 259 * Store parent-side rrset in separate rrset cache entries for later 260 * last-resort * lookups in case the child-side versions of this information 261 * fails. 262 * @param env: environment with cache, time, ... 263 * @param rrset: the rrset to store (copied). 264 * Failure to store is logged, but otherwise ignored. 265 */ 266 void iter_store_parentside_rrset(struct module_env* env, 267 struct ub_packed_rrset_key* rrset); 268 269 /** 270 * Store parent-side NS records from a referral message 271 * @param env: environment with cache, time, ... 272 * @param rep: response with NS rrset. 273 * Failure to store is logged, but otherwise ignored. 274 */ 275 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep); 276 277 /** 278 * Store parent-side negative element, the parentside rrset does not exist, 279 * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag. 280 * @param env: environment with cache, time, ... 281 * @param qinfo: the identity of the rrset that is missing. 282 * @param rep: delegation response or answer response, to glean TTL from. 283 * (malloc) failure is logged but otherwise ignored. 284 */ 285 void iter_store_parentside_neg(struct module_env* env, 286 struct query_info* qinfo, struct reply_info* rep); 287 288 /** 289 * Add parent NS record if that exists in the cache. This is both new 290 * information and acts like a timeout throttle on retries. 291 * @param env: query env with rrset cache and time. 292 * @param dp: delegation point to store result in. Also this dp is used to 293 * see which NS name is needed. 294 * @param region: region to alloc result in. 295 * @param qinfo: pertinent information, the qclass. 296 * @return false on malloc failure. 297 * if true, the routine worked and if such cached information 298 * existed dp->has_parent_side_NS is set true. 299 */ 300 int iter_lookup_parent_NS_from_cache(struct module_env* env, 301 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 302 303 /** 304 * Add parent-side glue if that exists in the cache. This is both new 305 * information and acts like a timeout throttle on retries to fetch them. 306 * @param env: query env with rrset cache and time. 307 * @param dp: delegation point to store result in. Also this dp is used to 308 * see which NS name is needed. 309 * @param region: region to alloc result in. 310 * @param qinfo: pertinent information, the qclass. 311 * @return: true, it worked, no malloc failures, and new addresses (lame) 312 * have been added, giving extra options as query targets. 313 */ 314 int iter_lookup_parent_glue_from_cache(struct module_env* env, 315 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 316 317 /** 318 * Lookup next root-hint or root-forward entry. 319 * @param hints: the hints. 320 * @param fwd: the forwards. 321 * @param c: the class to start searching at. 0 means find first one. 322 * @return false if no classes found, true if found and returned in c. 323 */ 324 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd, 325 uint16_t* c); 326 327 /** 328 * Remove DS records that are inappropriate before they are cached. 329 * @param msg: the response to scrub. 330 * @param ns: RRSET that is the NS record for the referral. 331 * if NULL, then all DS records are removed from the authority section. 332 * @param z: zone name that the response is from. 333 */ 334 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, 335 uint8_t* z); 336 337 /** 338 * Remove query attempts from all available ips. For 0x20. 339 * @param dp: delegpt. 340 * @param d: decrease. 341 */ 342 void iter_dec_attempts(struct delegpt* dp, int d); 343 344 /** 345 * Add retry counts from older delegpt to newer delegpt. 346 * Does not waste time on timeout'd (or other failing) addresses. 347 * @param dp: new delegationpoint. 348 * @param old: old delegationpoint. 349 */ 350 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old); 351 352 /** 353 * See if a DS response (type ANSWER) is too low: a nodata answer with 354 * a SOA record in the authority section at-or-below the qchase.qname. 355 * Also returns true if we are not sure (i.e. empty message, CNAME nosig). 356 * @param msg: the response. 357 * @param dp: the dp name is used to check if the RRSIG gives a clue that 358 * it was originated from the correct nameserver. 359 * @return true if too low. 360 */ 361 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp); 362 363 /** 364 * See if delegpt can go down a step to the qname or not 365 * @param qinfo: the query name looked up. 366 * @param dp: checked if the name can go lower to the qname 367 * @return true if can go down, false if that would not be possible. 368 * the current response seems to be the one and only, best possible, response. 369 */ 370 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp); 371 372 #endif /* ITERATOR_ITER_UTILS_H */ 373