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 * @param supports_ipv4: if we support ipv4 for lookups to the target. 179 * if not, then the IPv4 addresses are useless. 180 * @param supports_ipv6: if we support ipv6 for lookups to the target. 181 * if not, then the IPv6 addresses are useless. 182 * @return true if dp is useless. 183 */ 184 int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags, 185 struct delegpt* dp, int supports_ipv4, int supports_ipv6); 186 187 /** 188 * See if qname has DNSSEC needs. This is true if there is a trust anchor above 189 * it. Whether there is an insecure delegation to the data is unknown. 190 * @param env: environment with anchors. 191 * @param qinfo: query name and class. 192 * @return true if trust anchor above qname, false if no anchor or insecure 193 * point above qname. 194 */ 195 int iter_qname_indicates_dnssec(struct module_env* env, 196 struct query_info *qinfo); 197 198 /** 199 * See if delegation is expected to have DNSSEC information (RRSIGs) in 200 * its answers, or not. Inspects delegation point (name), trust anchors, 201 * and delegation message (DS RRset) to determine this. 202 * @param env: module env with trust anchors. 203 * @param dp: delegation point. 204 * @param msg: delegation message, with DS if a secure referral. 205 * @param dclass: class of query. 206 * @return 1 if dnssec is expected, 0 if not or insecure point above qname. 207 */ 208 int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp, 209 struct dns_msg* msg, uint16_t dclass); 210 211 /** 212 * See if a message contains DNSSEC. 213 * This is examined by looking for RRSIGs. With DNSSEC a valid answer, 214 * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth 215 * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records. 216 * @param msg: message to examine. 217 * @return true if DNSSEC information was found. 218 */ 219 int iter_msg_has_dnssec(struct dns_msg* msg); 220 221 /** 222 * See if a message is known to be from a certain zone. 223 * This looks for SOA or NS rrsets, for answers. 224 * For referrals, when one label is delegated, the zone is detected. 225 * Does not look at signatures. 226 * @param msg: the message to inspect. 227 * @param dp: delegation point with zone name to look for. 228 * @param type: type of message. 229 * @param dclass: class of query. 230 * @return true if message is certain to be from zone in dp->name. 231 * false if not sure (empty msg), or not from the zone. 232 */ 233 int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp, 234 enum response_type type, uint16_t dclass); 235 236 /** 237 * Check if two replies are equal 238 * For fallback procedures 239 * @param p: reply one. The reply has rrset data pointers in region. 240 * Does not check rrset-IDs 241 * @param q: reply two 242 * @param region: scratch buffer. 243 * @return if one and two are equal. 244 */ 245 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region); 246 247 /** 248 * Remove unused bits from the reply if possible. 249 * So that caps-for-id (0x20) fallback is more likely to be successful. 250 * This removes like, the additional section, and NS record in the authority 251 * section if those records are gratuitous (not for a referral). 252 * @param rep: the reply to strip stuff out of. 253 */ 254 void caps_strip_reply(struct reply_info* rep); 255 256 /** 257 * see if reply has a 'useful' rcode for capsforid comparison, so 258 * not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN. 259 * @param rep: reply to check. 260 * @return true if the rcode is a bad type of message. 261 */ 262 int caps_failed_rcode(struct reply_info* rep); 263 264 /** 265 * Store parent-side rrset in separate rrset cache entries for later 266 * last-resort * lookups in case the child-side versions of this information 267 * fails. 268 * @param env: environment with cache, time, ... 269 * @param rrset: the rrset to store (copied). 270 * Failure to store is logged, but otherwise ignored. 271 */ 272 void iter_store_parentside_rrset(struct module_env* env, 273 struct ub_packed_rrset_key* rrset); 274 275 /** 276 * Store parent-side NS records from a referral message 277 * @param env: environment with cache, time, ... 278 * @param rep: response with NS rrset. 279 * Failure to store is logged, but otherwise ignored. 280 */ 281 void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep); 282 283 /** 284 * Store parent-side negative element, the parentside rrset does not exist, 285 * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag. 286 * @param env: environment with cache, time, ... 287 * @param qinfo: the identity of the rrset that is missing. 288 * @param rep: delegation response or answer response, to glean TTL from. 289 * (malloc) failure is logged but otherwise ignored. 290 */ 291 void iter_store_parentside_neg(struct module_env* env, 292 struct query_info* qinfo, struct reply_info* rep); 293 294 /** 295 * Add parent NS record if that exists in the cache. This is both new 296 * information and acts like a timeout throttle on retries. 297 * @param env: query env with rrset cache and time. 298 * @param dp: delegation point to store result in. Also this dp is used to 299 * see which NS name is needed. 300 * @param region: region to alloc result in. 301 * @param qinfo: pertinent information, the qclass. 302 * @return false on malloc failure. 303 * if true, the routine worked and if such cached information 304 * existed dp->has_parent_side_NS is set true. 305 */ 306 int iter_lookup_parent_NS_from_cache(struct module_env* env, 307 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 308 309 /** 310 * Add parent-side glue if that exists in the cache. This is both new 311 * information and acts like a timeout throttle on retries to fetch them. 312 * @param env: query env with rrset cache and time. 313 * @param dp: delegation point to store result in. Also this dp is used to 314 * see which NS name is needed. 315 * @param region: region to alloc result in. 316 * @param qinfo: pertinent information, the qclass. 317 * @return: true, it worked, no malloc failures, and new addresses (lame) 318 * have been added, giving extra options as query targets. 319 */ 320 int iter_lookup_parent_glue_from_cache(struct module_env* env, 321 struct delegpt* dp, struct regional* region, struct query_info* qinfo); 322 323 /** 324 * Lookup next root-hint or root-forward entry. 325 * @param hints: the hints. 326 * @param fwd: the forwards. 327 * @param c: the class to start searching at. 0 means find first one. 328 * @return false if no classes found, true if found and returned in c. 329 */ 330 int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd, 331 uint16_t* c); 332 333 /** 334 * Remove DS records that are inappropriate before they are cached. 335 * @param msg: the response to scrub. 336 * @param ns: RRSET that is the NS record for the referral. 337 * if NULL, then all DS records are removed from the authority section. 338 * @param z: zone name that the response is from. 339 */ 340 void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, 341 uint8_t* z); 342 343 /** 344 * Prepare an NXDOMAIN message to be used for a subdomain answer by removing all 345 * RRs from the ANSWER section. 346 * @param msg: the response to scrub. 347 */ 348 void iter_scrub_nxdomain(struct dns_msg* msg); 349 350 /** 351 * Remove query attempts from all available ips. For 0x20. 352 * @param dp: delegpt. 353 * @param d: decrease. 354 * @param outbound_msg_retry: number of retries of outgoing queries 355 */ 356 void iter_dec_attempts(struct delegpt* dp, int d, int outbound_msg_retry); 357 358 /** 359 * Add retry counts from older delegpt to newer delegpt. 360 * Does not waste time on timeout'd (or other failing) addresses. 361 * @param dp: new delegationpoint. 362 * @param old: old delegationpoint. 363 * @param outbound_msg_retry: number of retries of outgoing queries 364 */ 365 void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old, 366 int outbound_msg_retry); 367 368 /** 369 * See if a DS response (type ANSWER) is too low: a nodata answer with 370 * a SOA record in the authority section at-or-below the qchase.qname. 371 * Also returns true if we are not sure (i.e. empty message, CNAME nosig). 372 * @param msg: the response. 373 * @param dp: the dp name is used to check if the RRSIG gives a clue that 374 * it was originated from the correct nameserver. 375 * @return true if too low. 376 */ 377 int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp); 378 379 /** 380 * See if delegpt can go down a step to the qname or not 381 * @param qinfo: the query name looked up. 382 * @param dp: checked if the name can go lower to the qname 383 * @return true if can go down, false if that would not be possible. 384 * the current response seems to be the one and only, best possible, response. 385 */ 386 int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp); 387 388 /** 389 * Lookup if no_cache is set in stub or fwd. 390 * @param qstate: query state with env with hints and fwds. 391 * @param qinf: query name to lookup for. 392 * @param retdpname: returns NULL or the deepest enclosing name of fwd or stub. 393 * This is the name under which the closest lookup is going to happen. 394 * Used for NXDOMAIN checks, above that it is an nxdomain from a 395 * different server and zone. You can pass NULL to not get it. 396 * @param retdpnamelen: returns the length of the dpname. 397 * @return true if no_cache is set in stub or fwd. 398 */ 399 int iter_stub_fwd_no_cache(struct module_qstate *qstate, 400 struct query_info *qinf, uint8_t** retdpname, size_t* retdpnamelen); 401 402 /** 403 * Set support for IP4 and IP6 depending on outgoing interfaces 404 * in the outside network. If none, no support, so no use to lookup 405 * the AAAA and then attempt to use it if there is no outgoing-interface 406 * for it. 407 * @param mods: modstack to find iterator module in. 408 * @param env: module env, find iterator module (if one) in there. 409 * @param outnet: outside network structure. 410 */ 411 void iterator_set_ip46_support(struct module_stack* mods, 412 struct module_env* env, struct outside_network* outnet); 413 414 #endif /* ITERATOR_ITER_UTILS_H */ 415