271 lines
11 KiB
C
271 lines
11 KiB
C
/*
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* services/cache/dns.h - Cache services for DNS using msg and rrset caches.
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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 the DNS cache.
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*/
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#ifndef SERVICES_CACHE_DNS_H
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#define SERVICES_CACHE_DNS_H
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#include "util/storage/lruhash.h"
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#include "util/data/msgreply.h"
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struct module_env;
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struct query_info;
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struct reply_info;
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struct regional;
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struct delegpt;
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/** Flags to control behavior of dns_cache_store() and dns_cache_store_msg().
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* Must be an unsigned 32-bit value larger than 0xffff */
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/** Allow caching a DNS message with a zero TTL. */
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#define DNSCACHE_STORE_ZEROTTL 0x100000
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/**
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* Region allocated message reply
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*/
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struct dns_msg {
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/** query info */
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struct query_info qinfo;
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/** reply info - ptr to packed repinfo structure */
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struct reply_info *rep;
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};
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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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*
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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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* this is allocated in a region, and will be copied to malloc area
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* before insertion.
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* @param rep: reply in dns_msg from dns_alloc_msg for example.
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* this is allocated in a region, and will be copied to malloc area
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* before insertion.
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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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* It will store only the RRsets, not the message.
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* @param leeway: TTL value, if not 0, other rrsets are considered expired
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* that many seconds before actual TTL expiry.
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* @param pside: if true, information came from a server which was fetched
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* from the parentside of the zonecut. This means that the type NS
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* can be updated to full TTL even in prefetch situations.
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* @param region: region to allocate better entries from cache into.
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* (used when is_referral is false).
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* @param flags: flags with BIT_CD for AAAA queries in dns64 translation.
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* The higher 16 bits are used internally to customize the cache policy.
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* (See DNSCACHE_STORE_xxx flags).
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* @param qstarttime: time when the query was started, and thus when the
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* delegations were looked up.
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* @return 0 on alloc error (out of memory).
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*/
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int dns_cache_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, uint32_t flags, time_t qstarttime);
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/**
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* Store message in the cache. Stores in message cache and rrset cache.
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* Both qinfo and rep should be malloced and are put in the cache.
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* They should not be used after this call, as they are then in shared cache.
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* Does not return errors, they are logged and only lead to less cache.
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*
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* @param env: module environment with the DNS cache.
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* @param qinfo: query info
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* @param hash: hash over qinfo.
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* @param rep: reply info, together with qinfo makes up the message.
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* Adjusts the reply info TTLs to absolute time.
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* @param leeway: TTL value, if not 0, other rrsets are considered expired
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* that many seconds before actual TTL expiry.
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* @param pside: if true, information came from a server which was fetched
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* from the parentside of the zonecut. This means that the type NS
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* can be updated to full TTL even in prefetch situations.
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* @param qrep: message that can be altered with better rrs from cache.
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* @param flags: customization flags for the cache policy.
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* @param qstarttime: time when the query was started, and thus when the
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* delegations were looked up.
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* @param region: to allocate into for qmsg.
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*/
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void dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
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hashvalue_type hash, struct reply_info* rep, time_t leeway, int pside,
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struct reply_info* qrep, uint32_t flags, struct regional* region,
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time_t qstarttime);
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/**
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* Find a delegation from the cache.
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* @param env: module environment with the DNS cache.
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* @param qname: query name.
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* @param qnamelen: length of qname.
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* @param qtype: query type.
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* @param qclass: query class.
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* @param region: where to allocate result delegation.
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* @param msg: if not NULL, delegation message is returned here, synthesized
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* from the cache.
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* @param timenow: the time now, for checking if TTL on cache entries is OK.
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* @param noexpiredabove: if set, no expired NS rrsets above the one found
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* are tolerated. It only returns delegations where the delegations above
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* it are valid.
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* @param expiretop: if not NULL, name where check for expiry ends for
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* noexpiredabove.
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* @param expiretoplen: length of expiretop dname.
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* @return new delegation or NULL on error or if not found in cache.
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*/
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struct delegpt* dns_cache_find_delegation(struct module_env* env,
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uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
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struct regional* region, struct dns_msg** msg, time_t timenow,
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int noexpiredabove, uint8_t* expiretop, size_t expiretoplen);
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/**
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* generate dns_msg from cached message
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* @param env: module environment with the DNS cache. NULL if the LRU from cache
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* does not need to be touched.
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* @param q: query info, contains qname that will make up the dns message.
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* @param r: reply info that, together with qname, will make up the dns message.
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* @param region: where to allocate dns message.
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* @param now: the time now, for check if TTL on cache entry is ok.
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* @param allow_expired: if true and serve-expired is enabled, it will allow
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* for expired dns_msg to be generated based on the configured serve-expired
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* logic.
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* @param scratch: where to allocate temporary data.
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* */
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struct dns_msg* tomsg(struct module_env* env, struct query_info* q,
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struct reply_info* r, struct regional* region, time_t now,
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int allow_expired, struct regional* scratch);
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/**
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* Find cached message
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* @param env: module environment with the DNS cache.
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* @param qname: query name.
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* @param qnamelen: length of qname.
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* @param qtype: query type.
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* @param qclass: query class.
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* @param flags: flags with BIT_CD for AAAA queries in dns64 translation.
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* @param region: where to allocate result.
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* @param scratch: where to allocate temporary data.
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* @param no_partial: if true, only complete messages and not a partial
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* one (with only the start of the CNAME chain and not the rest).
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* @param dpname: if not NULL, do not return NXDOMAIN above this name.
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* @param dpnamelen: length of dpname.
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* @return new response message (alloced in region, rrsets do not have IDs).
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* or NULL on error or if not found in cache.
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* TTLs are made relative to the current time.
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*/
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struct dns_msg* dns_cache_lookup(struct module_env* env,
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uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
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uint16_t flags, struct regional* region, struct regional* scratch,
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int no_partial, uint8_t* dpname, size_t dpnamelen);
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/**
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* find and add A and AAAA records for missing nameservers in delegpt
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* @param env: module environment with rrset cache
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* @param qclass: which class to look in.
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* @param region: where to store new dp info.
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* @param dp: delegation point to fill missing entries.
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* @return false on alloc failure.
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*/
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int cache_fill_missing(struct module_env* env, uint16_t qclass,
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struct regional* region, struct delegpt* dp);
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/**
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* Utility, create new, unpacked data structure for cache response.
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* QR bit set, no AA. Query set as indicated. Space for number of rrsets.
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* @param qname: query section name
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* @param qnamelen: len of qname
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* @param qtype: query section type
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* @param qclass: query section class
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* @param region: where to alloc.
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* @param capacity: number of rrsets space to create in the array.
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* @return new dns_msg struct or NULL on mem fail.
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*/
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struct dns_msg* dns_msg_create(uint8_t* qname, size_t qnamelen, uint16_t qtype,
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uint16_t qclass, struct regional* region, size_t capacity);
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/**
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* Add rrset to authority section in unpacked dns_msg message. Must have enough
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* space left, does not grow the array.
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* @param msg: msg to put it in.
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* @param region: region to alloc in
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* @param rrset: to add in authority section
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* @param now: now.
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* @return true if worked, false on fail
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*/
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int dns_msg_authadd(struct dns_msg* msg, struct regional* region,
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struct ub_packed_rrset_key* rrset, time_t now);
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/**
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* Add rrset to authority section in unpacked dns_msg message. Must have enough
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* space left, does not grow the array.
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* @param msg: msg to put it in.
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* @param region: region to alloc in
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* @param rrset: to add in authority section
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* @param now: now.
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* @return true if worked, false on fail
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*/
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int dns_msg_ansadd(struct dns_msg* msg, struct regional* region,
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struct ub_packed_rrset_key* rrset, time_t now);
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/**
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* Adjust the prefetch_ttl for a cached message. This adds a value to the
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* prefetch ttl - postponing the time when it will be prefetched for future
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* incoming queries.
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* @param env: module environment with caches and time.
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* @param qinfo: query info for the query that needs adjustment.
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* @param adjust: time in seconds to add to the prefetch_leeway.
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* @param flags: flags with BIT_CD for AAAA queries in dns64 translation.
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* @return false if not in cache. true if added.
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*/
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int dns_cache_prefetch_adjust(struct module_env* env, struct query_info* qinfo,
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time_t adjust, uint16_t flags);
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/** lookup message in message cache
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* the returned nonNULL entry is locked and has to be unlocked by the caller */
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struct msgreply_entry* msg_cache_lookup(struct module_env* env,
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uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
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uint16_t flags, time_t now, int wr);
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/**
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* Remove entry from the message cache. For unwanted entries.
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* @param env: with message cache.
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* @param qname: query name, in wireformat
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* @param qnamelen: length of qname, including terminating 0.
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* @param qtype: query type, host order.
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* @param qclass: query class, host order.
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* @param flags: flags
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*/
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void msg_cache_remove(struct module_env* env, uint8_t* qname, size_t qnamelen,
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uint16_t qtype, uint16_t qclass, uint16_t flags);
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#endif /* SERVICES_CACHE_DNS_H */
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