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" 46 struct module_env; 47 struct query_info; 48 struct reply_info; 49 struct regional; 50 struct 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 */ 61 struct 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 * @param qstarttime: time when the query was started, and thus when the 92 * delegations were looked up. 93 * @return 0 on alloc error (out of memory). 94 */ 95 int dns_cache_store(struct module_env* env, struct query_info* qinf, 96 struct reply_info* rep, int is_referral, time_t leeway, int pside, 97 struct regional* region, uint32_t flags, time_t qstarttime); 98 99 /** 100 * Store message in the cache. Stores in message cache and rrset cache. 101 * Both qinfo and rep should be malloced and are put in the cache. 102 * They should not be used after this call, as they are then in shared cache. 103 * Does not return errors, they are logged and only lead to less cache. 104 * 105 * @param env: module environment with the DNS cache. 106 * @param qinfo: query info 107 * @param hash: hash over qinfo. 108 * @param rep: reply info, together with qinfo makes up the message. 109 * Adjusts the reply info TTLs to absolute time. 110 * @param leeway: TTL value, if not 0, other rrsets are considered expired 111 * that many seconds before actual TTL expiry. 112 * @param pside: if true, information came from a server which was fetched 113 * from the parentside of the zonecut. This means that the type NS 114 * can be updated to full TTL even in prefetch situations. 115 * @param qrep: message that can be altered with better rrs from cache. 116 * @param flags: customization flags for the cache policy. 117 * @param qstarttime: time when the query was started, and thus when the 118 * delegations were looked up. 119 * @param region: to allocate into for qmsg. 120 */ 121 void dns_cache_store_msg(struct module_env* env, struct query_info* qinfo, 122 hashvalue_type hash, struct reply_info* rep, time_t leeway, int pside, 123 struct reply_info* qrep, uint32_t flags, struct regional* region, 124 time_t qstarttime); 125 126 /** 127 * Find a delegation from the cache. 128 * @param env: module environment with the DNS cache. 129 * @param qname: query name. 130 * @param qnamelen: length of qname. 131 * @param qtype: query type. 132 * @param qclass: query class. 133 * @param region: where to allocate result delegation. 134 * @param msg: if not NULL, delegation message is returned here, synthesized 135 * from the cache. 136 * @param timenow: the time now, for checking if TTL on cache entries is OK. 137 * @param noexpiredabove: if set, no expired NS rrsets above the one found 138 * are tolerated. It only returns delegations where the delegations above 139 * it are valid. 140 * @param expiretop: if not NULL, name where check for expiry ends for 141 * noexpiredabove. 142 * @param expiretoplen: length of expiretop dname. 143 * @return new delegation or NULL on error or if not found in cache. 144 */ 145 struct delegpt* dns_cache_find_delegation(struct module_env* env, 146 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 147 struct regional* region, struct dns_msg** msg, time_t timenow, 148 int noexpiredabove, uint8_t* expiretop, size_t expiretoplen); 149 150 /** 151 * generate dns_msg from cached message 152 * @param env: module environment with the DNS cache. NULL if the LRU from cache 153 * does not need to be touched. 154 * @param q: query info, contains qname that will make up the dns message. 155 * @param r: reply info that, together with qname, will make up the dns message. 156 * @param region: where to allocate dns message. 157 * @param now: the time now, for check if TTL on cache entry is ok. 158 * @param allow_expired: if true and serve-expired is enabled, it will allow 159 * for expired dns_msg to be generated based on the configured serve-expired 160 * logic. 161 * @param scratch: where to allocate temporary data. 162 * */ 163 struct dns_msg* tomsg(struct module_env* env, struct query_info* q, 164 struct reply_info* r, struct regional* region, time_t now, 165 int allow_expired, struct regional* scratch); 166 167 /** 168 * Find cached message 169 * @param env: module environment with the DNS cache. 170 * @param qname: query name. 171 * @param qnamelen: length of qname. 172 * @param qtype: query type. 173 * @param qclass: query class. 174 * @param flags: flags with BIT_CD for AAAA queries in dns64 translation. 175 * @param region: where to allocate result. 176 * @param scratch: where to allocate temporary data. 177 * @param no_partial: if true, only complete messages and not a partial 178 * one (with only the start of the CNAME chain and not the rest). 179 * @param dpname: if not NULL, do not return NXDOMAIN above this name. 180 * @param dpnamelen: length of dpname. 181 * @return new response message (alloced in region, rrsets do not have IDs). 182 * or NULL on error or if not found in cache. 183 * TTLs are made relative to the current time. 184 */ 185 struct dns_msg* dns_cache_lookup(struct module_env* env, 186 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 187 uint16_t flags, struct regional* region, struct regional* scratch, 188 int no_partial, uint8_t* dpname, size_t dpnamelen); 189 190 /** 191 * find and add A and AAAA records for missing nameservers in delegpt 192 * @param env: module environment with rrset cache 193 * @param qclass: which class to look in. 194 * @param region: where to store new dp info. 195 * @param dp: delegation point to fill missing entries. 196 * @return false on alloc failure. 197 */ 198 int cache_fill_missing(struct module_env* env, uint16_t qclass, 199 struct regional* region, struct delegpt* dp); 200 201 /** 202 * Utility, create new, unpacked data structure for cache response. 203 * QR bit set, no AA. Query set as indicated. Space for number of rrsets. 204 * @param qname: query section name 205 * @param qnamelen: len of qname 206 * @param qtype: query section type 207 * @param qclass: query section class 208 * @param region: where to alloc. 209 * @param capacity: number of rrsets space to create in the array. 210 * @return new dns_msg struct or NULL on mem fail. 211 */ 212 struct dns_msg* dns_msg_create(uint8_t* qname, size_t qnamelen, uint16_t qtype, 213 uint16_t qclass, struct regional* region, size_t capacity); 214 215 /** 216 * Add rrset to authority section in unpacked dns_msg message. Must have enough 217 * space left, does not grow the array. 218 * @param msg: msg to put it in. 219 * @param region: region to alloc in 220 * @param rrset: to add in authority section 221 * @param now: now. 222 * @return true if worked, false on fail 223 */ 224 int dns_msg_authadd(struct dns_msg* msg, struct regional* region, 225 struct ub_packed_rrset_key* rrset, time_t now); 226 227 /** 228 * Add rrset to authority section in unpacked dns_msg message. Must have enough 229 * space left, does not grow the array. 230 * @param msg: msg to put it in. 231 * @param region: region to alloc in 232 * @param rrset: to add in authority section 233 * @param now: now. 234 * @return true if worked, false on fail 235 */ 236 int dns_msg_ansadd(struct dns_msg* msg, struct regional* region, 237 struct ub_packed_rrset_key* rrset, time_t now); 238 239 /** 240 * Adjust the prefetch_ttl for a cached message. This adds a value to the 241 * prefetch ttl - postponing the time when it will be prefetched for future 242 * incoming queries. 243 * @param env: module environment with caches and time. 244 * @param qinfo: query info for the query that needs adjustment. 245 * @param adjust: time in seconds to add to the prefetch_leeway. 246 * @param flags: flags with BIT_CD for AAAA queries in dns64 translation. 247 * @return false if not in cache. true if added. 248 */ 249 int dns_cache_prefetch_adjust(struct module_env* env, struct query_info* qinfo, 250 time_t adjust, uint16_t flags); 251 252 /** lookup message in message cache 253 * the returned nonNULL entry is locked and has to be unlocked by the caller */ 254 struct msgreply_entry* msg_cache_lookup(struct module_env* env, 255 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass, 256 uint16_t flags, time_t now, int wr); 257 258 /** 259 * Remove entry from the message cache. For unwanted entries. 260 * @param env: with message cache. 261 * @param qname: query name, in wireformat 262 * @param qnamelen: length of qname, including terminating 0. 263 * @param qtype: query type, host order. 264 * @param qclass: query class, host order. 265 * @param flags: flags 266 */ 267 void msg_cache_remove(struct module_env* env, uint8_t* qname, size_t qnamelen, 268 uint16_t qtype, uint16_t qclass, uint16_t flags); 269 270 #endif /* SERVICES_CACHE_DNS_H */ 271