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 struct module_stack; 63 struct outside_network; 64 65 /** 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. 70 * @return 0 on error. 71 */ 72 int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg); 73 74 /** 75 * Select a valid, nice target to send query to. 76 * Sorting and removing unsuitable targets is combined. 77 * 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. 98 */ 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, 103 time_t prefetch); 104 105 /** 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. 111 */ 112 struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg, 113 struct regional* regional); 114 115 /** 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. 120 */ 121 struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional); 122 123 /** 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 * return void, because we are not interested in alloc errors, 136 * the iterator and validator can operate on the results in their 137 * scratch space (the qstate.region) and are not dependent on the cache. 138 * It is useful to log the alloc failure (for the server operator), 139 * but the query resolution can continue without cache storage. 140 */ 141 void iter_dns_store(struct module_env* env, struct query_info* qinf, 142 struct reply_info* rep, int is_referral, time_t leeway, int pside, 143 struct regional* region, uint16_t flags); 144 145 /** 146 * Select randomly with n/m probability. 147 * For shuffle NS records for address fetching. 148 * @param rnd: random table 149 * @param n: probability. 150 * @param m: divisor for probability. 151 * @return true with n/m probability. 152 */ 153 int iter_ns_probability(struct ub_randstate* rnd, int n, int m); 154 155 /** 156 * Mark targets that result in a dependency cycle as done, so they 157 * will not get selected as targets. 158 * @param qstate: query state. 159 * @param dp: delegpt to mark ns in. 160 */ 161 void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp); 162 163 /** 164 * Mark targets that result in a dependency cycle as done, so they 165 * will not get selected as targets. For the parent-side lookups. 166 * @param qstate: query state. 167 * @param dp: delegpt to mark ns in. 168 */ 169 void iter_mark_pside_cycle_targets(struct module_qstate* qstate, 170 struct delegpt* dp); 171 172 /** 173 * See if delegation is useful or offers immediately no targets for 174 * further recursion. 175 * @param qinfo: query name and type 176 * @param qflags: query flags with RD flag 177 * @param dp: delegpt to check. 178 * @return true if dp is useless. 179 */ 180 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags, 181 struct delegpt* dp); 182 183 /** 184 * See if qname has DNSSEC needs. This is true if there is a trust anchor above 185 * it. Whether there is an insecure delegation to the data is unknown. 186 * @param env: environment with anchors. 187 * @param qinfo: query name and class. 188 * @return true if trust anchor above qname, false if no anchor or insecure 189 * point above qname. 190 */ 191 int iter_qname_indicates_dnssec(struct module_env* env, 192 struct query_info *qinfo); 193 194 /** 195 * See if delegation is expected to have DNSSEC information (RRSIGs) in 196 * its answers, or not. Inspects delegation point (name), trust anchors, 197 * and delegation message (DS RRset) to determine this. 198 * @param env: module env with trust anchors. 199 * @param dp: delegation point. 200 * @param msg: delegation message, with DS if a secure referral. 201 * @param dclass: class of query. 202 * @return 1 if dnssec is expected, 0 if not or insecure point above qname. 203 */ 204 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp, 205 struct dns_msg* msg, uint16_t dclass); 206 207 /** 208 * See if a message contains DNSSEC. 209 * This is examined by looking for RRSIGs. With DNSSEC a valid answer, 210 * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth 211 * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records. 212 * @param msg: message to examine. 213 * @return true if DNSSEC information was found. 214 */ 215 int iter_msg_has_dnssec(struct dns_msg* msg); 216 217 /** 218 * See if a message is known to be from a certain zone. 219 * This looks for SOA or NS rrsets, for answers. 220 * For referrals, when one label is delegated, the zone is detected. 221 * Does not look at signatures. 222 * @param msg: the message to inspect. 223 * @param dp: delegation point with zone name to look for. 224 * @param type: type of message. 225 * @param dclass: class of query. 226 * @return true if message is certain to be from zone in dp->name. 227 * false if not sure (empty msg), or not from the zone. 228 */ 229 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp, 230 enum response_type type, uint16_t dclass); 231 232 /** 233 * Check if two replies are equal 234 * For fallback procedures 235 * @param p: reply one. The reply has rrset data pointers in region. 236 * Does not check rrset-IDs 237 * @param q: reply two 238 * @param region: scratch buffer. 239 * @return if one and two are equal. 240 */ 241 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region); 242 243 /** 244 * Remove unused bits from the reply if possible. 245 * So that caps-for-id (0x20) fallback is more likely to be successful. 246 * This removes like, the additional section, and NS record in the authority 247 * section if those records are gratuitous (not for a referral). 248 * @param rep: the reply to strip stuff out of. 249 */ 250 void caps_strip_reply(struct reply_info* rep); 251 252 /** 253 * see if reply has a 'useful' rcode for capsforid comparison, so 254 * not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN. 255 * @param rep: reply to check. 256 * @return true if the rcode is a bad type of message. 257 */ 258 int caps_failed_rcode(struct reply_info* rep); 259 260 /** 261 * Store parent-side rrset in separate rrset cache entries for later 262 * last-resort * lookups in case the child-side versions of this information 263 * fails. 264 * @param env: environment with cache, time, ... 265 * @param rrset: the rrset to store (copied). 266 * Failure to store is logged, but otherwise ignored. 267 */ 268 void iter_store_parentside_rrset(struct module_env* env, 269 struct ub_packed_rrset_key* rrset); 270 271 /** 272 * Store parent-side NS records from a referral message 273 * @param env: environment with cache, time, ... 274 * @param rep: response with NS rrset. 275 * Failure to store is logged, but otherwise ignored. 276 */ 277 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep); 278 279 /** 280 * Store parent-side negative element, the parentside rrset does not exist, 281 * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag. 282 * @param env: environment with cache, time, ... 283 * @param qinfo: the identity of the rrset that is missing. 284 * @param rep: delegation response or answer response, to glean TTL from. 285 * (malloc) failure is logged but otherwise ignored. 286 */ 287 void iter_store_parentside_neg(struct module_env* env, 288 struct query_info* qinfo, struct reply_info* rep); 289 290 /** 291 * Add parent NS record if that exists in the cache. This is both new 292 * information and acts like a timeout throttle on retries. 293 * @param env: query env with rrset cache and time. 294 * @param dp: delegation point to store result in. Also this dp is used to 295 * see which NS name is needed. 296 * @param region: region to alloc result in. 297 * @param qinfo: pertinent information, the qclass. 298 * @return false on malloc failure. 299 * if true, the routine worked and if such cached information 300 * existed dp->has_parent_side_NS is set true. 301 */ 302 int iter_lookup_parent_NS_from_cache(struct module_env* env, 303 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 304 305 /** 306 * Add parent-side glue if that exists in the cache. This is both new 307 * information and acts like a timeout throttle on retries to fetch them. 308 * @param env: query env with rrset cache and time. 309 * @param dp: delegation point to store result in. Also this dp is used to 310 * see which NS name is needed. 311 * @param region: region to alloc result in. 312 * @param qinfo: pertinent information, the qclass. 313 * @return: true, it worked, no malloc failures, and new addresses (lame) 314 * have been added, giving extra options as query targets. 315 */ 316 int iter_lookup_parent_glue_from_cache(struct module_env* env, 317 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 318 319 /** 320 * Lookup next root-hint or root-forward entry. 321 * @param hints: the hints. 322 * @param fwd: the forwards. 323 * @param c: the class to start searching at. 0 means find first one. 324 * @return false if no classes found, true if found and returned in c. 325 */ 326 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd, 327 uint16_t* c); 328 329 /** 330 * Remove DS records that are inappropriate before they are cached. 331 * @param msg: the response to scrub. 332 * @param ns: RRSET that is the NS record for the referral. 333 * if NULL, then all DS records are removed from the authority section. 334 * @param z: zone name that the response is from. 335 */ 336 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, 337 uint8_t* z); 338 339 /** 340 * Prepare an NXDOMAIN message to be used for a subdomain answer by removing all 341 * RRs from the ANSWER section. 342 * @param msg: the response to scrub. 343 */ 344 void iter_scrub_nxdomain(struct dns_msg* msg); 345 346 /** 347 * Remove query attempts from all available ips. For 0x20. 348 * @param dp: delegpt. 349 * @param d: decrease. 350 * @param outbound_msg_retry: number of retries of outgoing queries 351 */ 352 void iter_dec_attempts(struct delegpt* dp, int d, int outbound_msg_retry); 353 354 /** 355 * Add retry counts from older delegpt to newer delegpt. 356 * Does not waste time on timeout'd (or other failing) addresses. 357 * @param dp: new delegationpoint. 358 * @param old: old delegationpoint. 359 * @param outbound_msg_retry: number of retries of outgoing queries 360 */ 361 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old, 362 int outbound_msg_retry); 363 364 /** 365 * See if a DS response (type ANSWER) is too low: a nodata answer with 366 * a SOA record in the authority section at-or-below the qchase.qname. 367 * Also returns true if we are not sure (i.e. empty message, CNAME nosig). 368 * @param msg: the response. 369 * @param dp: the dp name is used to check if the RRSIG gives a clue that 370 * it was originated from the correct nameserver. 371 * @return true if too low. 372 */ 373 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp); 374 375 /** 376 * See if delegpt can go down a step to the qname or not 377 * @param qinfo: the query name looked up. 378 * @param dp: checked if the name can go lower to the qname 379 * @return true if can go down, false if that would not be possible. 380 * the current response seems to be the one and only, best possible, response. 381 */ 382 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp); 383 384 /** 385 * Lookup if no_cache is set in stub or fwd. 386 * @param qstate: query state with env with hints and fwds. 387 * @param qinf: query name to lookup for. 388 * @param retdpname: returns NULL or the deepest enclosing name of fwd or stub. 389 * This is the name under which the closest lookup is going to happen. 390 * Used for NXDOMAIN checks, above that it is an nxdomain from a 391 * different server and zone. You can pass NULL to not get it. 392 * @param retdpnamelen: returns the length of the dpname. 393 * @return true if no_cache is set in stub or fwd. 394 */ 395 int iter_stub_fwd_no_cache(struct module_qstate *qstate, 396 struct query_info *qinf, uint8_t** retdpname, size_t* retdpnamelen); 397 398 /** 399 * Set support for IP4 and IP6 depending on outgoing interfaces 400 * in the outside network. If none, no support, so no use to lookup 401 * the AAAA and then attempt to use it if there is no outgoing-interface 402 * for it. 403 * @param mods: modstack to find iterator module in. 404 * @param env: module env, find iterator module (if one) in there. 405 * @param outnet: outside network structure. 406 */ 407 void iterator_set_ip46_support(struct module_stack* mods, 408 struct module_env* env, struct outside_network* outnet); 409 410 #endif /* ITERATOR_ITER_UTILS_H */ 411