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357 lines
14 KiB
357 lines
14 KiB
/*
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* iterator/iter_utils.h - iterative resolver module utility functions.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file contains functions to assist the iterator module.
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* Configuration options. Forward zones.
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*/
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#ifndef ITERATOR_ITER_UTILS_H
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#define ITERATOR_ITER_UTILS_H
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#include "iterator/iter_resptype.h"
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struct sldns_buffer;
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struct iter_env;
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struct iter_hints;
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struct iter_forwards;
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struct config_file;
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struct module_env;
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struct delegpt_addr;
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struct delegpt;
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struct regional;
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struct msg_parse;
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struct ub_randstate;
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struct query_info;
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struct reply_info;
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struct module_qstate;
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struct sock_list;
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struct ub_packed_rrset_key;
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/**
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* Process config options and set iterator module state.
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* Sets default values if no config is found.
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* @param iter_env: iterator module state.
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* @param cfg: config options.
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* @return 0 on error.
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*/
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int iter_apply_cfg(struct iter_env* iter_env, struct config_file* cfg);
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/**
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* Select a valid, nice target to send query to.
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* Sorting and removing unsuitable targets is combined.
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*
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* @param iter_env: iterator module global state, with ip6 enabled and
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* do-not-query-addresses.
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* @param env: environment with infra cache (lameness, rtt info).
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* @param dp: delegation point with result list.
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* @param name: zone name (for lameness check).
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* @param namelen: length of name.
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* @param qtype: query type that we want to send.
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* @param dnssec_lame: set to 1, if a known dnssec-lame server is selected
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* these are not preferred, but are used as a last resort.
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* @param chase_to_rd: set to 1 if a known recursion lame server is selected
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* these are not preferred, but are used as a last resort.
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* @param open_target: number of currently outstanding target queries.
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* If we wait for these, perhaps more server addresses become available.
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* @param blacklist: the IP blacklist to use.
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* @return best target or NULL if no target.
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* if not null, that target is removed from the result list in the dp.
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*/
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struct delegpt_addr* iter_server_selection(struct iter_env* iter_env,
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struct module_env* env, struct delegpt* dp, uint8_t* name,
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size_t namelen, uint16_t qtype, int* dnssec_lame,
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int* chase_to_rd, int open_target, struct sock_list* blacklist);
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/**
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* Allocate dns_msg from parsed msg, in regional.
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* @param pkt: packet.
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* @param msg: parsed message (cleaned and ready for regional allocation).
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* @param regional: regional to use for allocation.
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* @return newly allocated dns_msg, or NULL on memory error.
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*/
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struct dns_msg* dns_alloc_msg(struct sldns_buffer* pkt, struct msg_parse* msg,
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struct regional* regional);
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/**
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* Copy a dns_msg to this regional.
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* @param from: dns message, also in regional.
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* @param regional: regional to use for allocation.
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* @return newly allocated dns_msg, or NULL on memory error.
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*/
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struct dns_msg* dns_copy_msg(struct dns_msg* from, struct regional* regional);
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/**
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* Allocate a dns_msg with malloc/alloc structure and store in dns cache.
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* @param env: environment, with alloc structure and dns cache.
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* @param qinf: query info, the query for which answer is stored.
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* @param rep: reply in dns_msg from dns_alloc_msg for example.
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* @param is_referral: If true, then the given message to be stored is a
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* referral. The cache implementation may use this as a hint.
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* @param leeway: prefetch TTL leeway to expire old rrsets quicker.
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* @param pside: true if dp is parentside, thus message is 'fresh' and NS
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* can be prefetch-updates.
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* @param region: to copy modified (cache is better) rrs back to.
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* @param flags: with BIT_CD for dns64 AAAA translated queries.
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* @return void, because we are not interested in alloc errors,
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* the iterator and validator can operate on the results in their
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* scratch space (the qstate.region) and are not dependent on the cache.
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* It is useful to log the alloc failure (for the server operator),
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* but the query resolution can continue without cache storage.
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*/
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void iter_dns_store(struct module_env* env, struct query_info* qinf,
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struct reply_info* rep, int is_referral, time_t leeway, int pside,
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struct regional* region, uint16_t flags);
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/**
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* Select randomly with n/m probability.
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* For shuffle NS records for address fetching.
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* @param rnd: random table
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* @param n: probability.
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* @param m: divisor for probability.
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* @return true with n/m probability.
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*/
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int iter_ns_probability(struct ub_randstate* rnd, int n, int m);
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/**
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* Mark targets that result in a dependency cycle as done, so they
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* will not get selected as targets.
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* @param qstate: query state.
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* @param dp: delegpt to mark ns in.
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*/
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void iter_mark_cycle_targets(struct module_qstate* qstate, struct delegpt* dp);
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/**
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* Mark targets that result in a dependency cycle as done, so they
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* will not get selected as targets. For the parent-side lookups.
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* @param qstate: query state.
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* @param dp: delegpt to mark ns in.
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*/
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void iter_mark_pside_cycle_targets(struct module_qstate* qstate,
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struct delegpt* dp);
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/**
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* See if delegation is useful or offers immediately no targets for
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* further recursion.
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* @param qinfo: query name and type
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* @param qflags: query flags with RD flag
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* @param dp: delegpt to check.
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* @return true if dp is useless.
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*/
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int iter_dp_is_useless(struct query_info* qinfo, uint16_t qflags,
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struct delegpt* dp);
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/**
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* See if delegation is expected to have DNSSEC information (RRSIGs) in
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* its answers, or not. Inspects delegation point (name), trust anchors,
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* and delegation message (DS RRset) to determine this.
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* @param env: module env with trust anchors.
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* @param dp: delegation point.
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* @param msg: delegation message, with DS if a secure referral.
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* @param dclass: class of query.
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* @return 1 if dnssec is expected, 0 if not.
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*/
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int iter_indicates_dnssec(struct module_env* env, struct delegpt* dp,
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struct dns_msg* msg, uint16_t dclass);
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/**
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* See if a message contains DNSSEC.
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* This is examined by looking for RRSIGs. With DNSSEC a valid answer,
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* nxdomain, nodata, referral or cname reply has RRSIGs in answer or auth
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* sections, sigs on answer data, SOA, DS, or NSEC/NSEC3 records.
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* @param msg: message to examine.
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* @return true if DNSSEC information was found.
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*/
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int iter_msg_has_dnssec(struct dns_msg* msg);
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/**
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* See if a message is known to be from a certain zone.
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* This looks for SOA or NS rrsets, for answers.
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* For referrals, when one label is delegated, the zone is detected.
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* Does not look at signatures.
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* @param msg: the message to inspect.
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* @param dp: delegation point with zone name to look for.
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* @param type: type of message.
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* @param dclass: class of query.
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* @return true if message is certain to be from zone in dp->name.
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* false if not sure (empty msg), or not from the zone.
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*/
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int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
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enum response_type type, uint16_t dclass);
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/**
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* Check if two replies are equal
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* For fallback procedures
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* @param p: reply one. The reply has rrset data pointers in region.
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* Does not check rrset-IDs
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* @param q: reply two
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* @param region: scratch buffer.
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* @return if one and two are equal.
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*/
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int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region);
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/**
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* Remove unused bits from the reply if possible.
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* So that caps-for-id (0x20) fallback is more likely to be successful.
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* This removes like, the additional section, and NS record in the authority
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* section if those records are gratuitous (not for a referral).
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* @param rep: the reply to strip stuff out of.
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*/
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void caps_strip_reply(struct reply_info* rep);
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/**
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* see if reply has a 'useful' rcode for capsforid comparison, so
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* not SERVFAIL or REFUSED, and thus NOERROR or NXDOMAIN.
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* @param rep: reply to check.
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* @return true if the rcode is a bad type of message.
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*/
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int caps_failed_rcode(struct reply_info* rep);
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/**
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* Store parent-side rrset in seperate rrset cache entries for later
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* last-resort * lookups in case the child-side versions of this information
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* fails.
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* @param env: environment with cache, time, ...
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* @param rrset: the rrset to store (copied).
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* Failure to store is logged, but otherwise ignored.
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*/
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void iter_store_parentside_rrset(struct module_env* env,
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struct ub_packed_rrset_key* rrset);
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/**
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* Store parent-side NS records from a referral message
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* @param env: environment with cache, time, ...
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* @param rep: response with NS rrset.
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* Failure to store is logged, but otherwise ignored.
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*/
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void iter_store_parentside_NS(struct module_env* env, struct reply_info* rep);
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/**
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* Store parent-side negative element, the parentside rrset does not exist,
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* creates an rrset with empty rdata in the rrset cache with PARENTSIDE flag.
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* @param env: environment with cache, time, ...
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* @param qinfo: the identity of the rrset that is missing.
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* @param rep: delegation response or answer response, to glean TTL from.
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* (malloc) failure is logged but otherwise ignored.
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*/
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void iter_store_parentside_neg(struct module_env* env,
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struct query_info* qinfo, struct reply_info* rep);
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/**
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* Add parent NS record if that exists in the cache. This is both new
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* information and acts like a timeout throttle on retries.
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* @param env: query env with rrset cache and time.
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* @param dp: delegation point to store result in. Also this dp is used to
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* see which NS name is needed.
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* @param region: region to alloc result in.
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* @param qinfo: pertinent information, the qclass.
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* @return false on malloc failure.
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* if true, the routine worked and if such cached information
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* existed dp->has_parent_side_NS is set true.
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*/
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int iter_lookup_parent_NS_from_cache(struct module_env* env,
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struct delegpt* dp, struct regional* region, struct query_info* qinfo);
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/**
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* Add parent-side glue if that exists in the cache. This is both new
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* information and acts like a timeout throttle on retries to fetch them.
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* @param env: query env with rrset cache and time.
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* @param dp: delegation point to store result in. Also this dp is used to
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* see which NS name is needed.
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* @param region: region to alloc result in.
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* @param qinfo: pertinent information, the qclass.
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* @return: true, it worked, no malloc failures, and new addresses (lame)
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* have been added, giving extra options as query targets.
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*/
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int iter_lookup_parent_glue_from_cache(struct module_env* env,
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struct delegpt* dp, struct regional* region, struct query_info* qinfo);
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/**
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* Lookup next root-hint or root-forward entry.
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* @param hints: the hints.
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* @param fwd: the forwards.
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* @param c: the class to start searching at. 0 means find first one.
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* @return false if no classes found, true if found and returned in c.
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*/
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int iter_get_next_root(struct iter_hints* hints, struct iter_forwards* fwd,
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uint16_t* c);
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/**
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* Remove DS records that are inappropriate before they are cached.
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* @param msg: the response to scrub.
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* @param ns: RRSET that is the NS record for the referral.
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* if NULL, then all DS records are removed from the authority section.
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* @param z: zone name that the response is from.
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*/
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void iter_scrub_ds(struct dns_msg* msg, struct ub_packed_rrset_key* ns,
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uint8_t* z);
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/**
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* Remove query attempts from all available ips. For 0x20.
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* @param dp: delegpt.
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* @param d: decrease.
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*/
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void iter_dec_attempts(struct delegpt* dp, int d);
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/**
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* Add retry counts from older delegpt to newer delegpt.
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* Does not waste time on timeout'd (or other failing) addresses.
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* @param dp: new delegationpoint.
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* @param old: old delegationpoint.
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*/
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void iter_merge_retry_counts(struct delegpt* dp, struct delegpt* old);
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/**
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* See if a DS response (type ANSWER) is too low: a nodata answer with
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* a SOA record in the authority section at-or-below the qchase.qname.
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* Also returns true if we are not sure (i.e. empty message, CNAME nosig).
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* @param msg: the response.
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* @param dp: the dp name is used to check if the RRSIG gives a clue that
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* it was originated from the correct nameserver.
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* @return true if too low.
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*/
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int iter_ds_toolow(struct dns_msg* msg, struct delegpt* dp);
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/**
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* See if delegpt can go down a step to the qname or not
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* @param qinfo: the query name looked up.
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* @param dp: checked if the name can go lower to the qname
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* @return true if can go down, false if that would not be possible.
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* the current response seems to be the one and only, best possible, response.
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*/
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int iter_dp_cangodown(struct query_info* qinfo, struct delegpt* dp);
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#endif /* ITERATOR_ITER_UTILS_H */
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