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 /* max number of lookups in the cache for target nameserver names. 66 * This stops, for large delegations, N*N lookups in the cache. */ 67 #define ITERATOR_NAME_CACHELOOKUP_MAX 3 68 /* max number of lookups in the cache for parentside glue for nameserver names 69 * This stops, for larger delegations, N*N lookups in the cache. 70 * It is a little larger than the nonpside max, so it allows a couple extra 71 * lookups of parent side glue. */ 72 #define ITERATOR_NAME_CACHELOOKUP_MAX_PSIDE 5 73 74 /** 75 * Process config options and set iterator module state. 76 * Sets default values if no config is found. 77 * @param iter_env: iterator module state. 78 * @param cfg: config options. 79 * @return 0 on error. 80 */ 81 int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg); 82 83 /** 84 * Select a valid, nice target to send query to. 85 * Sorting and removing unsuitable targets is combined. 86 * 87 * @param iter_env: iterator module global state, with ip6 enabled and 88 * do-not-query-addresses. 89 * @param env: environment with infra cache (lameness, rtt info). 90 * @param dp: delegation point with result list. 91 * @param name: zone name (for lameness check). 92 * @param namelen: length of name. 93 * @param qtype: query type that we want to send. 94 * @param dnssec_lame: set to 1, if a known dnssec-lame server is selected 95 * these are not preferred, but are used as a last resort. 96 * @param chase_to_rd: set to 1 if a known recursion lame server is selected 97 * these are not preferred, but are used as a last resort. 98 * @param open_target: number of currently outstanding target queries. 99 * If we wait for these, perhaps more server addresses become available. 100 * @param blacklist: the IP blacklist to use. 101 * @param prefetch: if not 0, prefetch is in use for this query. 102 * This means the query can have different timing, because prefetch is 103 * not waited upon by the downstream client, and thus a good time to 104 * perform exploration of other targets. 105 * @return best target or NULL if no target. 106 * if not null, that target is removed from the result list in the dp. 107 */ 108 struct delegpt_addr* iter_server_selection(struct iter_env* iter_env, 109 struct module_env* env, struct delegpt* dp, uint8_t* name, 110 size_t namelen, uint16_t qtype, int* dnssec_lame, 111 int* chase_to_rd, int open_target, struct sock_list* blacklist, 112 time_t prefetch); 113 114 /** 115 * Allocate dns_msg from parsed msg, in regional. 116 * @param pkt: packet. 117 * @param msg: parsed message (cleaned and ready for regional allocation). 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_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg, 122 struct regional* regional); 123 124 /** 125 * Copy a dns_msg to this regional. 126 * @param from: dns message, also in regional. 127 * @param regional: regional to use for allocation. 128 * @return newly allocated dns_msg, or NULL on memory error. 129 */ 130 struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional); 131 132 /** 133 * Allocate a dns_msg with malloc/alloc structure and store in dns cache. 134 * @param env: environment, with alloc structure and dns cache. 135 * @param qinf: query info, the query for which answer is stored. 136 * @param rep: reply in dns_msg from dns_alloc_msg for example. 137 * @param is_referral: If true, then the given message to be stored is a 138 * referral. The cache implementation may use this as a hint. 139 * @param leeway: prefetch TTL leeway to expire old rrsets quicker. 140 * @param pside: true if dp is parentside, thus message is 'fresh' and NS 141 * can be prefetch-updates. 142 * @param region: to copy modified (cache is better) rrs back to. 143 * @param flags: with BIT_CD for dns64 AAAA translated queries. 144 * @param qstarttime: time of query start. 145 * return void, because we are not interested in alloc errors, 146 * the iterator and validator can operate on the results in their 147 * scratch space (the qstate.region) and are not dependent on the cache. 148 * It is useful to log the alloc failure (for the server operator), 149 * but the query resolution can continue without cache storage. 150 */ 151 void iter_dns_store(struct module_env* env, struct query_info* qinf, 152 struct reply_info* rep, int is_referral, time_t leeway, int pside, 153 struct regional* region, uint16_t flags, time_t qstarttime); 154 155 /** 156 * Select randomly with n/m probability. 157 * For shuffle NS records for address fetching. 158 * @param rnd: random table 159 * @param n: probability. 160 * @param m: divisor for probability. 161 * @return true with n/m probability. 162 */ 163 int iter_ns_probability(struct ub_randstate* rnd, int n, int m); 164 165 /** 166 * Mark targets that result in a dependency cycle as done, so they 167 * will not get selected as targets. 168 * @param qstate: query state. 169 * @param dp: delegpt to mark ns in. 170 */ 171 void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp); 172 173 /** 174 * Mark targets that result in a dependency cycle as done, so they 175 * will not get selected as targets. For the parent-side lookups. 176 * @param qstate: query state. 177 * @param dp: delegpt to mark ns in. 178 */ 179 void iter_mark_pside_cycle_targets(struct module_qstate* qstate, 180 struct delegpt* dp); 181 182 /** 183 * See if delegation is useful or offers immediately no targets for 184 * further recursion. 185 * @param qinfo: query name and type 186 * @param qflags: query flags with RD flag 187 * @param dp: delegpt to check. 188 * @param supports_ipv4: if we support ipv4 for lookups to the target. 189 * if not, then the IPv4 addresses are useless. 190 * @param supports_ipv6: if we support ipv6 for lookups to the target. 191 * if not, then the IPv6 addresses are useless. 192 * @return true if dp is useless. 193 */ 194 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags, 195 struct delegpt* dp, int supports_ipv4, int supports_ipv6); 196 197 /** 198 * See if qname has DNSSEC needs. This is true if there is a trust anchor above 199 * it. Whether there is an insecure delegation to the data is unknown. 200 * @param env: environment with anchors. 201 * @param qinfo: query name and class. 202 * @return true if trust anchor above qname, false if no anchor or insecure 203 * point above qname. 204 */ 205 int iter_qname_indicates_dnssec(struct module_env* env, 206 struct query_info *qinfo); 207 208 /** 209 * See if delegation is expected to have DNSSEC information (RRSIGs) in 210 * its answers, or not. Inspects delegation point (name), trust anchors, 211 * and delegation message (DS RRset) to determine this. 212 * @param env: module env with trust anchors. 213 * @param dp: delegation point. 214 * @param msg: delegation message, with DS if a secure referral. 215 * @param dclass: class of query. 216 * @return 1 if dnssec is expected, 0 if not or insecure point above qname. 217 */ 218 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp, 219 struct dns_msg* msg, uint16_t dclass); 220 221 /** 222 * See if a message contains DNSSEC. 223 * This is examined by looking for RRSIGs. With DNSSEC a valid answer, 224 * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth 225 * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records. 226 * @param msg: message to examine. 227 * @return true if DNSSEC information was found. 228 */ 229 int iter_msg_has_dnssec(struct dns_msg* msg); 230 231 /** 232 * See if a message is known to be from a certain zone. 233 * This looks for SOA or NS rrsets, for answers. 234 * For referrals, when one label is delegated, the zone is detected. 235 * Does not look at signatures. 236 * @param msg: the message to inspect. 237 * @param dp: delegation point with zone name to look for. 238 * @param type: type of message. 239 * @param dclass: class of query. 240 * @return true if message is certain to be from zone in dp->name. 241 * false if not sure (empty msg), or not from the zone. 242 */ 243 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp, 244 enum response_type type, uint16_t dclass); 245 246 /** 247 * Check if two replies are equal 248 * For fallback procedures 249 * @param p: reply one. The reply has rrset data pointers in region. 250 * Does not check rrset-IDs 251 * @param q: reply two 252 * @param region: scratch buffer. 253 * @return if one and two are equal. 254 */ 255 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region); 256 257 /** 258 * Remove unused bits from the reply if possible. 259 * So that caps-for-id (0x20) fallback is more likely to be successful. 260 * This removes like, the additional section, and NS record in the authority 261 * section if those records are gratuitous (not for a referral). 262 * @param rep: the reply to strip stuff out of. 263 */ 264 void caps_strip_reply(struct reply_info* rep); 265 266 /** 267 * see if reply has a 'useful' rcode for capsforid comparison, so 268 * not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN. 269 * @param rep: reply to check. 270 * @return true if the rcode is a bad type of message. 271 */ 272 int caps_failed_rcode(struct reply_info* rep); 273 274 /** 275 * Store parent-side rrset in separate rrset cache entries for later 276 * last-resort * lookups in case the child-side versions of this information 277 * fails. 278 * @param env: environment with cache, time, ... 279 * @param rrset: the rrset to store (copied). 280 * Failure to store is logged, but otherwise ignored. 281 */ 282 void iter_store_parentside_rrset(struct module_env* env, 283 struct ub_packed_rrset_key* rrset); 284 285 /** 286 * Store parent-side NS records from a referral message 287 * @param env: environment with cache, time, ... 288 * @param rep: response with NS rrset. 289 * Failure to store is logged, but otherwise ignored. 290 */ 291 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep); 292 293 /** 294 * Store parent-side negative element, the parentside rrset does not exist, 295 * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag. 296 * @param env: environment with cache, time, ... 297 * @param qinfo: the identity of the rrset that is missing. 298 * @param rep: delegation response or answer response, to glean TTL from. 299 * (malloc) failure is logged but otherwise ignored. 300 */ 301 void iter_store_parentside_neg(struct module_env* env, 302 struct query_info* qinfo, struct reply_info* rep); 303 304 /** 305 * Add parent NS record if that exists in the cache. This is both new 306 * information and acts like a timeout throttle on retries. 307 * @param env: query env with rrset cache and time. 308 * @param dp: delegation point to store result in. Also this dp is used to 309 * see which NS name is needed. 310 * @param region: region to alloc result in. 311 * @param qinfo: pertinent information, the qclass. 312 * @return false on malloc failure. 313 * if true, the routine worked and if such cached information 314 * existed dp->has_parent_side_NS is set true. 315 */ 316 int iter_lookup_parent_NS_from_cache(struct module_env* env, 317 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 318 319 /** 320 * Add parent-side glue if that exists in the cache. This is both new 321 * information and acts like a timeout throttle on retries to fetch them. 322 * @param env: query env with rrset cache and time. 323 * @param dp: delegation point to store result in. Also this dp is used to 324 * see which NS name is needed. 325 * @param region: region to alloc result in. 326 * @param qinfo: pertinent information, the qclass. 327 * @return: true, it worked, no malloc failures, and new addresses (lame) 328 * have been added, giving extra options as query targets. 329 */ 330 int iter_lookup_parent_glue_from_cache(struct module_env* env, 331 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 332 333 /** 334 * Lookup next root-hint or root-forward entry. 335 * @param hints: the hints. 336 * @param fwd: the forwards. 337 * @param c: the class to start searching at. 0 means find first one. 338 * @return false if no classes found, true if found and returned in c. 339 */ 340 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd, 341 uint16_t* c); 342 343 /** 344 * Remove DS records that are inappropriate before they are cached. 345 * @param msg: the response to scrub. 346 * @param ns: RRSET that is the NS record for the referral. 347 * if NULL, then all DS records are removed from the authority section. 348 * @param z: zone name that the response is from. 349 */ 350 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, 351 uint8_t* z); 352 353 /** 354 * Prepare an NXDOMAIN message to be used for a subdomain answer by removing all 355 * RRs from the ANSWER section. 356 * @param msg: the response to scrub. 357 */ 358 void iter_scrub_nxdomain(struct dns_msg* msg); 359 360 /** 361 * Remove query attempts from all available ips. For 0x20. 362 * @param dp: delegpt. 363 * @param d: decrease. 364 * @param outbound_msg_retry: number of retries of outgoing queries 365 */ 366 void iter_dec_attempts(struct delegpt* dp, int d, int outbound_msg_retry); 367 368 /** 369 * Add retry counts from older delegpt to newer delegpt. 370 * Does not waste time on timeout'd (or other failing) addresses. 371 * @param dp: new delegationpoint. 372 * @param old: old delegationpoint. 373 * @param outbound_msg_retry: number of retries of outgoing queries 374 */ 375 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old, 376 int outbound_msg_retry); 377 378 /** 379 * See if a DS response (type ANSWER) is too low: a nodata answer with 380 * a SOA record in the authority section at-or-below the qchase.qname. 381 * Also returns true if we are not sure (i.e. empty message, CNAME nosig). 382 * @param msg: the response. 383 * @param dp: the dp name is used to check if the RRSIG gives a clue that 384 * it was originated from the correct nameserver. 385 * @return true if too low. 386 */ 387 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp); 388 389 /** 390 * See if delegpt can go down a step to the qname or not 391 * @param qinfo: the query name looked up. 392 * @param dp: checked if the name can go lower to the qname 393 * @return true if can go down, false if that would not be possible. 394 * the current response seems to be the one and only, best possible, response. 395 */ 396 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp); 397 398 /** 399 * Lookup if no_cache is set in stub or fwd. 400 * @param qstate: query state with env with hints and fwds. 401 * @param qinf: query name to lookup for. 402 * @param retdpname: returns NULL or the deepest enclosing name of fwd or stub. 403 * This is the name under which the closest lookup is going to happen. 404 * Used for NXDOMAIN checks, above that it is an nxdomain from a 405 * different server and zone. You can pass NULL to not get it. 406 * @param retdpnamelen: returns the length of the dpname. 407 * @return true if no_cache is set in stub or fwd. 408 */ 409 int iter_stub_fwd_no_cache(struct module_qstate *qstate, 410 struct query_info *qinf, uint8_t** retdpname, size_t* retdpnamelen); 411 412 /** 413 * Set support for IP4 and IP6 depending on outgoing interfaces 414 * in the outside network. If none, no support, so no use to lookup 415 * the AAAA and then attempt to use it if there is no outgoing-interface 416 * for it. 417 * @param mods: modstack to find iterator module in. 418 * @param env: module env, find iterator module (if one) in there. 419 * @param outnet: outside network structure. 420 */ 421 void iterator_set_ip46_support(struct module_stack* mods, 422 struct module_env* env, struct outside_network* outnet); 423 424 #endif /* ITERATOR_ITER_UTILS_H */ 425