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Diffstat (limited to 'iterator/iter_utils.h')
| -rw-r--r-- | iterator/iter_utils.h | 334 |
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diff --git a/iterator/iter_utils.h b/iterator/iter_utils.h new file mode 100644 index 000000000000..4fb8b005c197 --- /dev/null +++ b/iterator/iter_utils.h @@ -0,0 +1,334 @@ +/* + * iterator/iter_utils.h - iterative resolver module utility functions. + * + * Copyright (c) 2007, NLnet Labs. All rights reserved. + * + * This software is open source. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * Neither the name of the NLNET LABS nor the names of its contributors may + * be used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +/** + * \file + * + * This file contains functions to assist the iterator module. + * Configuration options. Forward zones. + */ + +#ifndef ITERATOR_ITER_UTILS_H +#define ITERATOR_ITER_UTILS_H +#include "iterator/iter_resptype.h" +#include <ldns/buffer.h> +struct iter_env; +struct iter_hints; +struct iter_forwards; +struct config_file; +struct module_env; +struct delegpt_addr; +struct delegpt; +struct regional; +struct msg_parse; +struct ub_randstate; +struct query_info; +struct reply_info; +struct module_qstate; +struct sock_list; +struct ub_packed_rrset_key; + +/** + * Process config options and set iterator module state. + * Sets default values if no config is found. + * @param iter_env: iterator module state. + * @param cfg: config options. + * @return 0 on error. + */ +int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg); + +/** + * Select a valid, nice target to send query to. + * Sorting and removing unsuitable targets is combined. + * + * @param iter_env: iterator module global state, with ip6 enabled and + * do-not-query-addresses. + * @param env: environment with infra cache (lameness, rtt info). + * @param dp: delegation point with result list. + * @param name: zone name (for lameness check). + * @param namelen: length of name. + * @param qtype: query type that we want to send. + * @param dnssec_lame: set to 1, if a known dnssec-lame server is selected + * these are not preferred, but are used as a last resort. + * @param chase_to_rd: set to 1 if a known recursion lame server is selected + * these are not preferred, but are used as a last resort. + * @param open_target: number of currently outstanding target queries. + * If we wait for these, perhaps more server addresses become available. + * @param blacklist: the IP blacklist to use. + * @return best target or NULL if no target. + * if not null, that target is removed from the result list in the dp. + */ +struct delegpt_addr* iter_server_selection(struct iter_env* iter_env, + struct module_env* env, struct delegpt* dp, uint8_t* name, + size_t namelen, uint16_t qtype, int* dnssec_lame, + int* chase_to_rd, int open_target, struct sock_list* blacklist); + +/** + * Allocate dns_msg from parsed msg, in regional. + * @param pkt: packet. + * @param msg: parsed message (cleaned and ready for regional allocation). + * @param regional: regional to use for allocation. + * @return newly allocated dns_msg, or NULL on memory error. + */ +struct dns_msg* dns_alloc_msg(ldns_buffer* pkt, struct msg_parse* msg, + struct regional* regional); + +/** + * Copy a dns_msg to this regional. + * @param from: dns message, also in regional. + * @param regional: regional to use for allocation. + * @return newly allocated dns_msg, or NULL on memory error. + */ +struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional); + +/** + * Allocate a dns_msg with malloc/alloc structure and store in dns cache. + * @param env: environment, with alloc structure and dns cache. + * @param qinf: query info, the query for which answer is stored. + * @param rep: reply in dns_msg from dns_alloc_msg for example. + * @param is_referral: If true, then the given message to be stored is a + * referral. The cache implementation may use this as a hint. + * @param leeway: prefetch TTL leeway to expire old rrsets quicker. + * @param pside: true if dp is parentside, thus message is 'fresh' and NS + * can be prefetch-updates. + * @param region: to copy modified (cache is better) rrs back to. + * @return 0 on alloc error (out of memory). + */ +int iter_dns_store(struct module_env* env, struct query_info* qinf, + struct reply_info* rep, int is_referral, uint32_t leeway, int pside, + struct regional* region); + +/** + * Select randomly with n/m probability. + * For shuffle NS records for address fetching. + * @param rnd: random table + * @param n: probability. + * @param m: divisor for probability. + * @return true with n/m probability. + */ +int iter_ns_probability(struct ub_randstate* rnd, int n, int m); + +/** + * Mark targets that result in a dependency cycle as done, so they + * will not get selected as targets. + * @param qstate: query state. + * @param dp: delegpt to mark ns in. + */ +void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp); + +/** + * Mark targets that result in a dependency cycle as done, so they + * will not get selected as targets. For the parent-side lookups. + * @param qstate: query state. + * @param dp: delegpt to mark ns in. + */ +void iter_mark_pside_cycle_targets(struct module_qstate* qstate, + struct delegpt* dp); + +/** + * See if delegation is useful or offers immediately no targets for + * further recursion. + * @param qinfo: query name and type + * @param qflags: query flags with RD flag + * @param dp: delegpt to check. + * @return true if dp is useless. + */ +int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags, + struct delegpt* dp); + +/** + * See if delegation is expected to have DNSSEC information (RRSIGs) in + * its answers, or not. Inspects delegation point (name), trust anchors, + * and delegation message (DS RRset) to determine this. + * @param env: module env with trust anchors. + * @param dp: delegation point. + * @param msg: delegation message, with DS if a secure referral. + * @param dclass: class of query. + * @return 1 if dnssec is expected, 0 if not. + */ +int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp, + struct dns_msg* msg, uint16_t dclass); + +/** + * See if a message contains DNSSEC. + * This is examined by looking for RRSIGs. With DNSSEC a valid answer, + * nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth + * sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records. + * @param msg: message to examine. + * @return true if DNSSEC information was found. + */ +int iter_msg_has_dnssec(struct dns_msg* msg); + +/** + * See if a message is known to be from a certain zone. + * This looks for SOA or NS rrsets, for answers. + * For referrals, when one label is delegated, the zone is detected. + * Does not look at signatures. + * @param msg: the message to inspect. + * @param dp: delegation point with zone name to look for. + * @param type: type of message. + * @param dclass: class of query. + * @return true if message is certain to be from zone in dp->name. + * false if not sure (empty msg), or not from the zone. + */ +int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp, + enum response_type type, uint16_t dclass); + +/** + * Check if two replies are equal + * For fallback procedures + * @param p: reply one. The reply has rrset data pointers in region. + * Does not check rrset-IDs + * @param q: reply two + * @param buf: scratch buffer. + * @return if one and two are equal. + */ +int reply_equal(struct reply_info* p, struct reply_info* q, ldns_buffer* buf); + +/** + * Store parent-side rrset in seperate rrset cache entries for later + * last-resort * lookups in case the child-side versions of this information + * fails. + * @param env: environment with cache, time, ... + * @param rrset: the rrset to store (copied). + * Failure to store is logged, but otherwise ignored. + */ +void iter_store_parentside_rrset(struct module_env* env, + struct ub_packed_rrset_key* rrset); + +/** + * Store parent-side NS records from a referral message + * @param env: environment with cache, time, ... + * @param rep: response with NS rrset. + * Failure to store is logged, but otherwise ignored. + */ +void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep); + +/** + * Store parent-side negative element, the parentside rrset does not exist, + * creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag. + * @param env: environment with cache, time, ... + * @param qinfo: the identity of the rrset that is missing. + * @param rep: delegation response or answer response, to glean TTL from. + * (malloc) failure is logged but otherwise ignored. + */ +void iter_store_parentside_neg(struct module_env* env, + struct query_info* qinfo, struct reply_info* rep); + +/** + * Add parent NS record if that exists in the cache. This is both new + * information and acts like a timeout throttle on retries. + * @param env: query env with rrset cache and time. + * @param dp: delegation point to store result in. Also this dp is used to + * see which NS name is needed. + * @param region: region to alloc result in. + * @param qinfo: pertinent information, the qclass. + * @return false on malloc failure. + * if true, the routine worked and if such cached information + * existed dp->has_parent_side_NS is set true. + */ +int iter_lookup_parent_NS_from_cache(struct module_env* env, + struct delegpt* dp, struct regional* region, struct query_info* qinfo); + +/** + * Add parent-side glue if that exists in the cache. This is both new + * information and acts like a timeout throttle on retries to fetch them. + * @param env: query env with rrset cache and time. + * @param dp: delegation point to store result in. Also this dp is used to + * see which NS name is needed. + * @param region: region to alloc result in. + * @param qinfo: pertinent information, the qclass. + * @return: true, it worked, no malloc failures, and new addresses (lame) + * have been added, giving extra options as query targets. + */ +int iter_lookup_parent_glue_from_cache(struct module_env* env, + struct delegpt* dp, struct regional* region, struct query_info* qinfo); + +/** + * Lookup next root-hint or root-forward entry. + * @param hints: the hints. + * @param fwd: the forwards. + * @param c: the class to start searching at. 0 means find first one. + * @return false if no classes found, true if found and returned in c. + */ +int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd, + uint16_t* c); + +/** + * Remove DS records that are inappropriate before they are cached. + * @param msg: the response to scrub. + * @param ns: RRSET that is the NS record for the referral. + * if NULL, then all DS records are removed from the authority section. + * @param z: zone name that the response is from. + */ +void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns, + uint8_t* z); + +/** + * Remove query attempts from all available ips. For 0x20. + * @param dp: delegpt. + * @param d: decrease. + */ +void iter_dec_attempts(struct delegpt* dp, int d); + +/** + * Add retry counts from older delegpt to newer delegpt. + * Does not waste time on timeout'd (or other failing) addresses. + * @param dp: new delegationpoint. + * @param old: old delegationpoint. + */ +void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old); + +/** + * See if a DS response (type ANSWER) is too low: a nodata answer with + * a SOA record in the authority section at-or-below the qchase.qname. + * Also returns true if we are not sure (i.e. empty message, CNAME nosig). + * @param msg: the response. + * @param dp: the dp name is used to check if the RRSIG gives a clue that + * it was originated from the correct nameserver. + * @return true if too low. + */ +int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp); + +/** + * See if delegpt can go down a step to the qname or not + * @param qinfo: the query name looked up. + * @param dp: checked if the name can go lower to the qname + * @return true if can go down, false if that would not be possible. + * the current response seems to be the one and only, best possible, response. + */ +int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp); + +#endif /* ITERATOR_ITER_UTILS_H */ |