1 /* 2 * validator/val_neg.h - validator aggressive negative caching functions. 3 * 4 * Copyright (c) 2008, 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 helper functions for the validator module. 40 * The functions help with aggressive negative caching. 41 * This creates new denials of existence, and proofs for absence of types 42 * from cached NSEC records. 43 */ 44 45 #ifndef VALIDATOR_VAL_NEG_H 46 #define VALIDATOR_VAL_NEG_H 47 #include "util/locks.h" 48 #include "util/rbtree.h" 49 struct sldns_buffer; 50 struct val_neg_data; 51 struct config_file; 52 struct reply_info; 53 struct rrset_cache; 54 struct regional; 55 struct query_info; 56 struct dns_msg; 57 struct ub_packed_rrset_key; 58 59 /** 60 * The negative cache. It is shared between the threads, so locked. 61 * Kept as validator-environ-state. It refers back to the rrset cache for 62 * data elements. It can be out of date and contain conflicting data 63 * from zone content changes. 64 * It contains a tree of zones, every zone has a tree of data elements. 65 * The data elements are part of one big LRU list, with one memory counter. 66 */ 67 struct val_neg_cache { 68 /** the big lock on the negative cache. Because we use a rbtree 69 * for the data (quick lookup), we need a big lock */ 70 lock_basic_t lock; 71 /** The zone rbtree. contents sorted canonical, type val_neg_zone */ 72 rbtree_t tree; 73 /** the first in linked list of LRU of val_neg_data */ 74 struct val_neg_data* first; 75 /** last in lru (least recently used element) */ 76 struct val_neg_data* last; 77 /** current memory in use (bytes) */ 78 size_t use; 79 /** max memory to use (bytes) */ 80 size_t max; 81 /** max nsec3 iterations allowed */ 82 size_t nsec3_max_iter; 83 }; 84 85 /** 86 * Per Zone aggressive negative caching data. 87 */ 88 struct val_neg_zone { 89 /** rbtree node element, key is this struct: the name, class */ 90 rbnode_t node; 91 /** name; the key */ 92 uint8_t* name; 93 /** length of name */ 94 size_t len; 95 /** labels in name */ 96 int labs; 97 98 /** pointer to parent zone in the negative cache */ 99 struct val_neg_zone* parent; 100 101 /** the number of elements, including this one and the ones whose 102 * parents (-parents) include this one, that are in_use 103 * No elements have a count of zero, those are removed. */ 104 int count; 105 106 /** if 0: NSEC zone, else NSEC3 hash algorithm in use */ 107 int nsec3_hash; 108 /** nsec3 iteration count in use */ 109 size_t nsec3_iter; 110 /** nsec3 salt in use */ 111 uint8_t* nsec3_salt; 112 /** length of salt in bytes */ 113 size_t nsec3_saltlen; 114 115 /** tree of NSEC data for this zone, sorted canonical 116 * by NSEC owner name */ 117 rbtree_t tree; 118 119 /** class of node; host order */ 120 uint16_t dclass; 121 /** if this element is in use, boolean */ 122 uint8_t in_use; 123 }; 124 125 /** 126 * Data element for aggressive negative caching. 127 * The tree of these elements acts as an index onto the rrset cache. 128 * It shows the NSEC records that (may) exist and are (possibly) secure. 129 * The rbtree allows for logN search for a covering NSEC record. 130 * To make tree insertion and deletion logN too, all the parent (one label 131 * less than the name) data elements are also in the rbtree, with a usage 132 * count for every data element. 133 * There is no actual data stored in this data element, if it is in_use, 134 * then the data can (possibly) be found in the rrset cache. 135 */ 136 struct val_neg_data { 137 /** rbtree node element, key is this struct: the name */ 138 rbnode_t node; 139 /** name; the key */ 140 uint8_t* name; 141 /** length of name */ 142 size_t len; 143 /** labels in name */ 144 int labs; 145 146 /** pointer to parent node in the negative cache */ 147 struct val_neg_data* parent; 148 149 /** the number of elements, including this one and the ones whose 150 * parents (-parents) include this one, that are in use 151 * No elements have a count of zero, those are removed. */ 152 int count; 153 154 /** the zone that this denial is part of */ 155 struct val_neg_zone* zone; 156 157 /** previous in LRU */ 158 struct val_neg_data* prev; 159 /** next in LRU (next element was less recently used) */ 160 struct val_neg_data* next; 161 162 /** if this element is in use, boolean */ 163 uint8_t in_use; 164 }; 165 166 /** 167 * Create negative cache 168 * @param cfg: config options. 169 * @param maxiter: max nsec3 iterations allowed. 170 * @return neg cache, empty or NULL on failure. 171 */ 172 struct val_neg_cache* val_neg_create(struct config_file* cfg, size_t maxiter); 173 174 /** 175 * see how much memory is in use by the negative cache. 176 * @param neg: negative cache 177 * @return number of bytes in use. 178 */ 179 size_t val_neg_get_mem(struct val_neg_cache* neg); 180 181 /** 182 * Destroy negative cache. There must no longer be any other threads. 183 * @param neg: negative cache. 184 */ 185 void neg_cache_delete(struct val_neg_cache* neg); 186 187 /** 188 * Comparison function for rbtree val neg data elements 189 */ 190 int val_neg_data_compare(const void* a, const void* b); 191 192 /** 193 * Comparison function for rbtree val neg zone elements 194 */ 195 int val_neg_zone_compare(const void* a, const void* b); 196 197 /** 198 * Insert NSECs from this message into the negative cache for reference. 199 * @param neg: negative cache 200 * @param rep: reply with NSECs. 201 * Errors are ignored, means that storage is omitted. 202 */ 203 void val_neg_addreply(struct val_neg_cache* neg, struct reply_info* rep); 204 205 /** 206 * Insert NSECs from this referral into the negative cache for reference. 207 * @param neg: negative cache 208 * @param rep: referral reply with NS, NSECs. 209 * @param zone: bailiwick for the referral. 210 * Errors are ignored, means that storage is omitted. 211 */ 212 void val_neg_addreferral(struct val_neg_cache* neg, struct reply_info* rep, 213 uint8_t* zone); 214 215 /** 216 * Perform a DLV style lookup 217 * During the lookup, we could find out that data has expired. In that 218 * case the neg_cache entries are removed, and lookup fails. 219 * 220 * @param neg: negative cache. 221 * @param qname: name to look for 222 * @param len: length of qname. 223 * @param qclass: class to look in. 224 * @param rrset_cache: the rrset cache, for NSEC lookups. 225 * @param now: current time for ttl checks. 226 * @return 227 * 0 on error 228 * 0 if no proof of negative 229 * 1 if indeed negative was proven 230 * thus, qname DLV qclass does not exist. 231 */ 232 int val_neg_dlvlookup(struct val_neg_cache* neg, uint8_t* qname, size_t len, 233 uint16_t qclass, struct rrset_cache* rrset_cache, time_t now); 234 235 /** 236 * For the given query, try to get a reply out of the negative cache. 237 * The reply still needs to be validated. 238 * @param neg: negative cache. 239 * @param qinfo: query 240 * @param region: where to allocate reply. 241 * @param rrset_cache: rrset cache. 242 * @param buf: temporary buffer. 243 * @param now: to check TTLs against. 244 * @param addsoa: if true, produce result for external consumption. 245 * if false, do not add SOA - for unbound-internal consumption. 246 * @param topname: do not look higher than this name, 247 * so that the result cannot be taken from a zone above the current 248 * trust anchor. Which could happen with multiple islands of trust. 249 * if NULL, then no trust anchor is used, but also the algorithm becomes 250 * more conservative, especially for opt-out zones, since the receiver 251 * may have a trust-anchor below the optout and thus the optout cannot 252 * be used to create a proof from the negative cache. 253 * @return a reply message if something was found. 254 * This reply may still need validation. 255 * NULL if nothing found (or out of memory). 256 */ 257 struct dns_msg* val_neg_getmsg(struct val_neg_cache* neg, 258 struct query_info* qinfo, struct regional* region, 259 struct rrset_cache* rrset_cache, struct sldns_buffer* buf, time_t now, 260 int addsoa, uint8_t* topname); 261 262 263 /**** functions exposed for unit test ****/ 264 /** 265 * Insert data into the data tree of a zone 266 * Does not do locking. 267 * @param neg: negative cache 268 * @param zone: zone to insert into 269 * @param nsec: record to insert. 270 */ 271 void neg_insert_data(struct val_neg_cache* neg, 272 struct val_neg_zone* zone, struct ub_packed_rrset_key* nsec); 273 274 /** 275 * Delete a data element from the negative cache. 276 * May delete other data elements to keep tree coherent, or 277 * only mark the element as 'not in use'. 278 * Does not do locking. 279 * @param neg: negative cache. 280 * @param el: data element to delete. 281 */ 282 void neg_delete_data(struct val_neg_cache* neg, struct val_neg_data* el); 283 284 /** 285 * Find the given zone, from the SOA owner name and class 286 * Does not do locking. 287 * @param neg: negative cache 288 * @param nm: what to look for. 289 * @param len: length of nm 290 * @param dclass: class to look for. 291 * @return zone or NULL if not found. 292 */ 293 struct val_neg_zone* neg_find_zone(struct val_neg_cache* neg, 294 uint8_t* nm, size_t len, uint16_t dclass); 295 296 /** 297 * Create a new zone. 298 * Does not do locking. 299 * @param neg: negative cache 300 * @param nm: what to look for. 301 * @param nm_len: length of name. 302 * @param dclass: class of zone, host order. 303 * @return zone or NULL if out of memory. 304 */ 305 struct val_neg_zone* neg_create_zone(struct val_neg_cache* neg, 306 uint8_t* nm, size_t nm_len, uint16_t dclass); 307 308 /** 309 * take a zone into use. increases counts of parents. 310 * Does not do locking. 311 * @param zone: zone to take into use. 312 */ 313 void val_neg_zone_take_inuse(struct val_neg_zone* zone); 314 315 #endif /* VALIDATOR_VAL_NEG_H */ 316