1/* 2 * services/cache/dns.h - Cache services for DNS using msg and rrset caches. 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 the DNS cache. 40 */ 41 42#ifndef SERVICES_CACHE_DNS_H 43#define SERVICES_CACHE_DNS_H 44#include "util/storage/lruhash.h" 45#include "util/data/msgreply.h" 46struct module_env; 47struct query_info; 48struct reply_info; 49struct regional; 50struct delegpt; 51 52/** Flags to control behavior of dns_cache_store() and dns_cache_store_msg(). 53 * Must be an unsigned 32-bit value larger than 0xffff */ 54 55/** Allow caching a DNS message with a zero TTL. */ 56#define DNSCACHE_STORE_ZEROTTL 0x100000 57 58/** 59 * Region allocated message reply 60 */ 61struct dns_msg { 62 /** query info */ 63 struct query_info qinfo; 64 /** reply info - ptr to packed repinfo structure */ 65 struct reply_info *rep; 66}; 67 68/** 69 * Allocate a dns_msg with malloc/alloc structure and store in dns cache. 70 * 71 * @param env: environment, with alloc structure and dns cache. 72 * @param qinf: query info, the query for which answer is stored. 73 * this is allocated in a region, and will be copied to malloc area 74 * before insertion. 75 * @param rep: reply in dns_msg from dns_alloc_msg for example. 76 * this is allocated in a region, and will be copied to malloc area 77 * before insertion. 78 * @param is_referral: If true, then the given message to be stored is a 79 * referral. The cache implementation may use this as a hint. 80 * It will store only the RRsets, not the message. 81 * @param leeway: TTL value, if not 0, other rrsets are considered expired 82 * that many seconds before actual TTL expiry. 83 * @param pside: if true, information came from a server which was fetched 84 * from the parentside of the zonecut. This means that the type NS 85 * can be updated to full TTL even in prefetch situations. 86 * @param region: region to allocate better entries from cache into. 87 * (used when is_referral is false). 88 * @param flags: flags with BIT_CD for AAAA queries in dns64 translation. 89 * The higher 16 bits are used internally to customize the cache policy. 90 * (See DNSCACHE_STORE_xxx flags). 91 * @return 0 on alloc error (out of memory). 92 */ 93int dns_cache_store(struct module_env* env, struct query_info* qinf, 94 struct reply_info* rep, int is_referral, time_t leeway, int pside, 95 struct regional* region, uint32_t flags); 96 97/** 98 * Store message in the cache. Stores in message cache and rrset cache. 99 * Both qinfo and rep should be malloced and are put in the cache. 100 * They should not be used after this call, as they are then in shared cache. 101 * Does not return errors, they are logged and only lead to less cache. 102 * 103 * @param env: module environment with the DNS cache. 104 * @param qinfo: query info 105 * @param hash: hash over qinfo. 106 * @param rep: reply info, together with qinfo makes up the message. 107 * Adjusts the reply info TTLs to absolute time. 108 * @param leeway: TTL value, if not 0, other rrsets are considered expired 109 * that many seconds before actual TTL expiry. 110 * @param pside: if true, information came from a server which was fetched 111 * from the parentside of the zonecut. This means that the type NS 112 * can be updated to full TTL even in prefetch situations. 113 * @param qrep: message that can be altered with better rrs from cache. 114 * @param flags: customization flags for the cache policy. 115 * @param region: to allocate into for qmsg. 116 */ 117void dns_cache_store_msg(struct module_env* env, struct query_info* qinfo, 118 hashvalue_type hash, struct reply_info* rep, time_t leeway, int pside, 119 struct reply_info* qrep, uint32_t flags, struct regional* region); 120 121/** 122 * Find a delegation from the cache. 123 * @param env: module environment with the DNS cache. 124 * @param qname: query name. 125 * @param qnamelen: length of qname. 126 * @param qtype: query type. 127 * @param qclass: query class. 128 * @param region: where to allocate result delegation. 129 * @param msg: if not NULL, delegation message is returned here, synthesized 130 * from the cache. 131 * @param timenow: the time now, for checking if TTL on cache entries is OK. 132 * @return new delegation or NULL on error or if not found in cache. 133 */ 134struct delegpt* dns_cache_find_delegation(struct module_env* env, 135 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 136 struct regional* region, struct dns_msg** msg, time_t timenow); 137 138/** 139 * generate dns_msg from cached message 140 * @param env: module environment with the DNS cache. NULL if the LRU from cache 141 * does not need to be touched. 142 * @param q: query info, contains qname that will make up the dns message. 143 * @param r: reply info that, together with qname, will make up the dns message. 144 * @param region: where to allocate dns message. 145 * @param now: the time now, for check if TTL on cache entry is ok. 146 * @param allow_expired: if true and serve-expired is enabled, it will allow 147 * for expired dns_msg to be generated based on the configured serve-expired 148 * logic. 149 * @param scratch: where to allocate temporary data. 150 * */ 151struct dns_msg* tomsg(struct module_env* env, struct query_info* q, 152 struct reply_info* r, struct regional* region, time_t now, 153 int allow_expired, struct regional* scratch); 154 155/** 156 * Find cached message 157 * @param env: module environment with the DNS cache. 158 * @param qname: query name. 159 * @param qnamelen: length of qname. 160 * @param qtype: query type. 161 * @param qclass: query class. 162 * @param flags: flags with BIT_CD for AAAA queries in dns64 translation. 163 * @param region: where to allocate result. 164 * @param scratch: where to allocate temporary data. 165 * @param no_partial: if true, only complete messages and not a partial 166 * one (with only the start of the CNAME chain and not the rest). 167 * @return new response message (alloced in region, rrsets do not have IDs). 168 * or NULL on error or if not found in cache. 169 * TTLs are made relative to the current time. 170 */ 171struct dns_msg* dns_cache_lookup(struct module_env* env, 172 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 173 uint16_t flags, struct regional* region, struct regional* scratch, 174 int no_partial); 175 176/** 177 * find and add A and AAAA records for missing nameservers in delegpt 178 * @param env: module environment with rrset cache 179 * @param qclass: which class to look in. 180 * @param region: where to store new dp info. 181 * @param dp: delegation point to fill missing entries. 182 * @return false on alloc failure. 183 */ 184int cache_fill_missing(struct module_env* env, uint16_t qclass, 185 struct regional* region, struct delegpt* dp); 186 187/** 188 * Utility, create new, unpacked data structure for cache response. 189 * QR bit set, no AA. Query set as indicated. Space for number of rrsets. 190 * @param qname: query section name 191 * @param qnamelen: len of qname 192 * @param qtype: query section type 193 * @param qclass: query section class 194 * @param region: where to alloc. 195 * @param capacity: number of rrsets space to create in the array. 196 * @return new dns_msg struct or NULL on mem fail. 197 */ 198struct dns_msg* dns_msg_create(uint8_t* qname, size_t qnamelen, uint16_t qtype, 199 uint16_t qclass, struct regional* region, size_t capacity); 200 201/** 202 * Add rrset to authority section in unpacked dns_msg message. Must have enough 203 * space left, does not grow the array. 204 * @param msg: msg to put it in. 205 * @param region: region to alloc in 206 * @param rrset: to add in authority section 207 * @param now: now. 208 * @return true if worked, false on fail 209 */ 210int dns_msg_authadd(struct dns_msg* msg, struct regional* region, 211 struct ub_packed_rrset_key* rrset, time_t now); 212 213/** 214 * Add rrset to authority section in unpacked dns_msg message. Must have enough 215 * space left, does not grow the array. 216 * @param msg: msg to put it in. 217 * @param region: region to alloc in 218 * @param rrset: to add in authority section 219 * @param now: now. 220 * @return true if worked, false on fail 221 */ 222int dns_msg_ansadd(struct dns_msg* msg, struct regional* region, 223 struct ub_packed_rrset_key* rrset, time_t now); 224 225/** 226 * Adjust the prefetch_ttl for a cached message. This adds a value to the 227 * prefetch ttl - postponing the time when it will be prefetched for future 228 * incoming queries. 229 * @param env: module environment with caches and time. 230 * @param qinfo: query info for the query that needs adjustment. 231 * @param adjust: time in seconds to add to the prefetch_leeway. 232 * @param flags: flags with BIT_CD for AAAA queries in dns64 translation. 233 * @return false if not in cache. true if added. 234 */ 235int dns_cache_prefetch_adjust(struct module_env* env, struct query_info* qinfo, 236 time_t adjust, uint16_t flags); 237 238/** lookup message in message cache 239 * the returned nonNULL entry is locked and has to be unlocked by the caller */ 240struct msgreply_entry* msg_cache_lookup(struct module_env* env, 241 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 242 uint16_t flags, time_t now, int wr); 243 244/** 245 * Remove entry from the message cache. For unwanted entries. 246 * @param env: with message cache. 247 * @param qname: query name, in wireformat 248 * @param qnamelen: length of qname, including terminating 0. 249 * @param qtype: query type, host order. 250 * @param qclass: query class, host order. 251 * @param flags: flags 252 */ 253void msg_cache_remove(struct module_env* env, uint8_t* qname, size_t qnamelen, 254 uint16_t qtype, uint16_t qclass, uint16_t flags); 255 256#endif /* SERVICES_CACHE_DNS_H */ 257