1238106Sdes/* 2238106Sdes * iterator/iterator.h - iterative resolver DNS query response module 3238106Sdes * 4238106Sdes * Copyright (c) 2007, NLnet Labs. All rights reserved. 5238106Sdes * 6238106Sdes * This software is open source. 7238106Sdes * 8238106Sdes * Redistribution and use in source and binary forms, with or without 9238106Sdes * modification, are permitted provided that the following conditions 10238106Sdes * are met: 11238106Sdes * 12238106Sdes * Redistributions of source code must retain the above copyright notice, 13238106Sdes * this list of conditions and the following disclaimer. 14238106Sdes * 15238106Sdes * Redistributions in binary form must reproduce the above copyright notice, 16238106Sdes * this list of conditions and the following disclaimer in the documentation 17238106Sdes * and/or other materials provided with the distribution. 18238106Sdes * 19238106Sdes * Neither the name of the NLNET LABS nor the names of its contributors may 20238106Sdes * be used to endorse or promote products derived from this software without 21238106Sdes * specific prior written permission. 22238106Sdes * 23238106Sdes * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24269257Sdes * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25269257Sdes * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 26269257Sdes * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 27269257Sdes * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28269257Sdes * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 29269257Sdes * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 30269257Sdes * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 31269257Sdes * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 32269257Sdes * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 33269257Sdes * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34238106Sdes */ 35238106Sdes 36238106Sdes/** 37238106Sdes * \file 38238106Sdes * 39238106Sdes * This file contains a module that performs recusive iterative DNS query 40238106Sdes * processing. 41238106Sdes */ 42238106Sdes 43238106Sdes#ifndef ITERATOR_ITERATOR_H 44238106Sdes#define ITERATOR_ITERATOR_H 45238106Sdes#include "services/outbound_list.h" 46238106Sdes#include "util/data/msgreply.h" 47238106Sdes#include "util/module.h" 48238106Sdesstruct delegpt; 49238106Sdesstruct iter_hints; 50238106Sdesstruct iter_forwards; 51238106Sdesstruct iter_donotq; 52238106Sdesstruct iter_prep_list; 53238106Sdesstruct iter_priv; 54291767Sdesstruct rbtree_t; 55238106Sdes 56275853Sdelphij/** max number of targets spawned for a query and its subqueries */ 57291767Sdes#define MAX_TARGET_COUNT 64 58238106Sdes/** max number of query restarts. Determines max number of CNAME chain. */ 59238106Sdes#define MAX_RESTART_COUNT 8 60238106Sdes/** max number of referrals. Makes sure resolver does not run away */ 61238106Sdes#define MAX_REFERRAL_COUNT 130 62238106Sdes/** max number of queries-sent-out. Make sure large NS set does not loop */ 63285206Sdes#define MAX_SENT_COUNT 32 64238106Sdes/** at what query-sent-count to stop target fetch policy */ 65238106Sdes#define TARGET_FETCH_STOP 3 66238106Sdes/** how nice is a server without further information, in msec 67238106Sdes * Equals rtt initial timeout value. 68238106Sdes */ 69238106Sdes#define UNKNOWN_SERVER_NICENESS 376 70238106Sdes/** maximum timeout before a host is deemed unsuitable, in msec. 71238106Sdes * After host_ttl this will be timed out and the host will be tried again. 72238106Sdes * Equals RTT_MAX_TIMEOUT 73238106Sdes */ 74238106Sdes#define USEFUL_SERVER_TOP_TIMEOUT 120000 75238106Sdes/** number of retries on outgoing queries */ 76238106Sdes#define OUTBOUND_MSG_RETRY 5 77238106Sdes/** RTT band, within this amount from the best, servers are chosen randomly. 78238106Sdes * Chosen so that the UNKNOWN_SERVER_NICENESS falls within the band of a 79238106Sdes * fast server, this causes server exploration as a side benefit. msec. */ 80238106Sdes#define RTT_BAND 400 81238106Sdes/** Start value for blacklisting a host, 2*USEFUL_SERVER_TOP_TIMEOUT in sec */ 82238106Sdes#define INFRA_BACKOFF_INITIAL 240 83238106Sdes 84238106Sdes/** 85238106Sdes * Global state for the iterator. 86238106Sdes */ 87238106Sdesstruct iter_env { 88238106Sdes /** A flag to indicate whether or not we have an IPv6 route */ 89238106Sdes int supports_ipv6; 90238106Sdes 91238106Sdes /** A flag to indicate whether or not we have an IPv4 route */ 92238106Sdes int supports_ipv4; 93238106Sdes 94238106Sdes /** A set of inetaddrs that should never be queried. */ 95238106Sdes struct iter_donotq* donotq; 96238106Sdes 97238106Sdes /** private address space and private domains */ 98238106Sdes struct iter_priv* priv; 99238106Sdes 100291767Sdes /** whitelist for capsforid names */ 101291767Sdes struct rbtree_t* caps_white; 102291767Sdes 103238106Sdes /** The maximum dependency depth that this resolver will pursue. */ 104238106Sdes int max_dependency_depth; 105238106Sdes 106238106Sdes /** 107238106Sdes * The target fetch policy for each dependency level. This is 108238106Sdes * described as a simple number (per dependency level): 109238106Sdes * negative numbers (usually just -1) mean fetch-all, 110238106Sdes * 0 means only fetch on demand, and 111238106Sdes * positive numbers mean to fetch at most that many targets. 112238106Sdes * array of max_dependency_depth+1 size. 113238106Sdes */ 114238106Sdes int* target_fetch_policy; 115294190Sdes 116294190Sdes /** ip6.arpa dname in wireformat, used for qname-minimisation */ 117294190Sdes uint8_t* ip6arpa_dname; 118238106Sdes}; 119238106Sdes 120238106Sdes/** 121294190Sdes * QNAME minimisation state 122294190Sdes */ 123294190Sdesenum minimisation_state { 124294190Sdes /** 125294190Sdes * (Re)start minimisation. Outgoing QNAME should be set to dp->name. 126294190Sdes * State entered on new query or after following refferal or CNAME. 127294190Sdes */ 128294190Sdes INIT_MINIMISE_STATE = 0, 129294190Sdes /** 130294190Sdes * QNAME minimisataion ongoing. Increase QNAME on every iteration. 131294190Sdes */ 132294190Sdes MINIMISE_STATE, 133294190Sdes /** 134294190Sdes * Don't increment QNAME this iteration 135294190Sdes */ 136294190Sdes SKIP_MINIMISE_STATE, 137294190Sdes /** 138294190Sdes * Send out full QNAME + original QTYPE 139294190Sdes */ 140294190Sdes DONOT_MINIMISE_STATE, 141294190Sdes}; 142294190Sdes 143294190Sdes/** 144238106Sdes * State of the iterator for a query. 145238106Sdes */ 146238106Sdesenum iter_state { 147238106Sdes /** 148238106Sdes * Externally generated queries start at this state. Query restarts are 149238106Sdes * reset to this state. 150238106Sdes */ 151238106Sdes INIT_REQUEST_STATE = 0, 152238106Sdes 153238106Sdes /** 154238106Sdes * Root priming events reactivate here, most other events pass 155238106Sdes * through this naturally as the 2nd part of the INIT_REQUEST_STATE. 156238106Sdes */ 157238106Sdes INIT_REQUEST_2_STATE, 158238106Sdes 159238106Sdes /** 160238106Sdes * Stub priming events reactivate here, most other events pass 161238106Sdes * through this naturally as the 3rd part of the INIT_REQUEST_STATE. 162238106Sdes */ 163238106Sdes INIT_REQUEST_3_STATE, 164238106Sdes 165238106Sdes /** 166238106Sdes * Each time a delegation point changes for a given query or a 167238106Sdes * query times out and/or wakes up, this state is (re)visited. 168238106Sdes * This state is reponsible for iterating through a list of 169238106Sdes * nameserver targets. 170238106Sdes */ 171238106Sdes QUERYTARGETS_STATE, 172238106Sdes 173238106Sdes /** 174238106Sdes * Responses to queries start at this state. This state handles 175238106Sdes * the decision tree associated with handling responses. 176238106Sdes */ 177238106Sdes QUERY_RESP_STATE, 178238106Sdes 179238106Sdes /** Responses to priming queries finish at this state. */ 180238106Sdes PRIME_RESP_STATE, 181238106Sdes 182238106Sdes /** Collecting query class information, for qclass=ANY, when 183238106Sdes * it spawns off queries for every class, it returns here. */ 184238106Sdes COLLECT_CLASS_STATE, 185238106Sdes 186238106Sdes /** Find NS record to resolve DS record from, walking to the right 187238106Sdes * NS spot until we find it */ 188238106Sdes DSNS_FIND_STATE, 189238106Sdes 190238106Sdes /** Responses that are to be returned upstream end at this state. 191238106Sdes * As well as responses to target queries. */ 192238106Sdes FINISHED_STATE 193238106Sdes}; 194238106Sdes 195238106Sdes/** 196238106Sdes * Per query state for the iterator module. 197238106Sdes */ 198238106Sdesstruct iter_qstate { 199238106Sdes /** 200238106Sdes * State of the iterator module. 201238106Sdes * This is the state that event is in or should sent to -- all 202238106Sdes * requests should start with the INIT_REQUEST_STATE. All 203238106Sdes * responses should start with QUERY_RESP_STATE. Subsequent 204238106Sdes * processing of the event will change this state. 205238106Sdes */ 206238106Sdes enum iter_state state; 207238106Sdes 208238106Sdes /** 209238106Sdes * Final state for the iterator module. 210238106Sdes * This is the state that responses should be routed to once the 211238106Sdes * response is final. For externally initiated queries, this 212238106Sdes * will be FINISHED_STATE, locally initiated queries will have 213238106Sdes * different final states. 214238106Sdes */ 215238106Sdes enum iter_state final_state; 216238106Sdes 217238106Sdes /** 218238106Sdes * The depth of this query, this means the depth of recursion. 219238106Sdes * This address is needed for another query, which is an address 220238106Sdes * needed for another query, etc. Original client query has depth 0. 221238106Sdes */ 222238106Sdes int depth; 223238106Sdes 224238106Sdes /** 225238106Sdes * The response 226238106Sdes */ 227238106Sdes struct dns_msg* response; 228238106Sdes 229238106Sdes /** 230238106Sdes * This is a list of RRsets that must be prepended to the 231238106Sdes * ANSWER section of a response before being sent upstream. 232238106Sdes */ 233238106Sdes struct iter_prep_list* an_prepend_list; 234238106Sdes /** Last element of the prepend list */ 235238106Sdes struct iter_prep_list* an_prepend_last; 236238106Sdes 237238106Sdes /** 238238106Sdes * This is the list of RRsets that must be prepended to the 239238106Sdes * AUTHORITY section of the response before being sent upstream. 240238106Sdes */ 241238106Sdes struct iter_prep_list* ns_prepend_list; 242238106Sdes /** Last element of the authority prepend list */ 243238106Sdes struct iter_prep_list* ns_prepend_last; 244238106Sdes 245238106Sdes /** query name used for chasing the results. Initially the same as 246238106Sdes * the state qinfo, but after CNAMEs this will be different. 247238106Sdes * The query info used to elicit the results needed. */ 248238106Sdes struct query_info qchase; 249238106Sdes /** query flags to use when chasing the answer (i.e. RD flag) */ 250238106Sdes uint16_t chase_flags; 251238106Sdes /** true if we set RD bit because of last resort recursion lame query*/ 252238106Sdes int chase_to_rd; 253238106Sdes 254238106Sdes /** 255238106Sdes * This is the current delegation point for an in-progress query. This 256238106Sdes * object retains state as to which delegation targets need to be 257238106Sdes * (sub)queried for vs which ones have already been visited. 258238106Sdes */ 259238106Sdes struct delegpt* dp; 260238106Sdes 261238106Sdes /** state for 0x20 fallback when capsfail happens, 0 not a fallback */ 262238106Sdes int caps_fallback; 263238106Sdes /** state for capsfail: current server number to try */ 264238106Sdes size_t caps_server; 265285206Sdes /** state for capsfail: stored query for comparisons. Can be NULL if 266285206Sdes * no response had been seen prior to starting the fallback. */ 267238106Sdes struct reply_info* caps_reply; 268291767Sdes struct dns_msg* caps_response; 269238106Sdes 270238106Sdes /** Current delegation message - returned for non-RD queries */ 271238106Sdes struct dns_msg* deleg_msg; 272238106Sdes 273238106Sdes /** number of outstanding target sub queries */ 274238106Sdes int num_target_queries; 275238106Sdes 276238106Sdes /** outstanding direct queries */ 277238106Sdes int num_current_queries; 278238106Sdes 279238106Sdes /** the number of times this query has been restarted. */ 280238106Sdes int query_restart_count; 281238106Sdes 282238106Sdes /** the number of times this query as followed a referral. */ 283238106Sdes int referral_count; 284238106Sdes 285238106Sdes /** number of queries fired off */ 286238106Sdes int sent_count; 287275853Sdelphij 288275853Sdelphij /** number of target queries spawned in [1], for this query and its 289275853Sdelphij * subqueries, the malloced-array is shared, [0] refcount. */ 290275853Sdelphij int* target_count; 291238106Sdes 292291767Sdes /** if true, already tested for ratelimiting and passed the test */ 293291767Sdes int ratelimit_ok; 294291767Sdes 295238106Sdes /** 296238106Sdes * The query must store NS records from referrals as parentside RRs 297238106Sdes * Enabled once it hits resolution problems, to throttle retries. 298238106Sdes * If enabled it is the pointer to the old delegation point with 299238106Sdes * the old retry counts for bad-nameserver-addresses. 300238106Sdes */ 301238106Sdes struct delegpt* store_parent_NS; 302238106Sdes 303238106Sdes /** 304238106Sdes * The query is for parent-side glue(A or AAAA) for a nameserver. 305238106Sdes * If the item is seen as glue in a referral, and pside_glue is NULL, 306238106Sdes * then it is stored in pside_glue for later. 307238106Sdes * If it was never seen, at the end, then a negative caching element 308238106Sdes * must be created. 309238106Sdes * The (data or negative) RR cache element then throttles retries. 310238106Sdes */ 311238106Sdes int query_for_pside_glue; 312238106Sdes /** the parent-side-glue element (NULL if none, its first match) */ 313238106Sdes struct ub_packed_rrset_key* pside_glue; 314238106Sdes 315238106Sdes /** If nonNULL we are walking upwards from DS query to find NS */ 316238106Sdes uint8_t* dsns_point; 317238106Sdes /** length of the dname in dsns_point */ 318238106Sdes size_t dsns_point_len; 319238106Sdes 320238106Sdes /** 321238106Sdes * expected dnssec information for this iteration step. 322238106Sdes * If dnssec rrsigs are expected and not given, the server is marked 323238106Sdes * lame (dnssec-lame). 324238106Sdes */ 325238106Sdes int dnssec_expected; 326238106Sdes 327238106Sdes /** 328238106Sdes * We are expecting dnssec information, but we also know the server 329238106Sdes * is DNSSEC lame. The response need not be marked dnssec-lame again. 330238106Sdes */ 331238106Sdes int dnssec_lame_query; 332238106Sdes 333238106Sdes /** 334238106Sdes * This is flag that, if true, means that this event is 335238106Sdes * waiting for a stub priming query. 336238106Sdes */ 337238106Sdes int wait_priming_stub; 338238106Sdes 339238106Sdes /** 340238106Sdes * This is a flag that, if true, means that this query is 341238106Sdes * for (re)fetching glue from a zone. Since the address should 342238106Sdes * have been glue, query again to the servers that should have 343238106Sdes * been returning it as glue. 344238106Sdes * The delegation point must be set to the one that should *not* 345238106Sdes * be used when creating the state. A higher one will be attempted. 346238106Sdes */ 347238106Sdes int refetch_glue; 348238106Sdes 349238106Sdes /** list of pending queries to authoritative servers. */ 350238106Sdes struct outbound_list outlist; 351294190Sdes 352294190Sdes /** QNAME minimisation state */ 353294190Sdes enum minimisation_state minimisation_state; 354294190Sdes 355294190Sdes /** 356294190Sdes * The query info that is sent upstream. Will be a subset of qchase 357294190Sdes * when qname minimisation is enabled. 358294190Sdes */ 359294190Sdes struct query_info qinfo_out; 360238106Sdes}; 361238106Sdes 362238106Sdes/** 363238106Sdes * List of prepend items 364238106Sdes */ 365238106Sdesstruct iter_prep_list { 366238106Sdes /** next in list */ 367238106Sdes struct iter_prep_list* next; 368238106Sdes /** rrset */ 369238106Sdes struct ub_packed_rrset_key* rrset; 370238106Sdes}; 371238106Sdes 372238106Sdes/** 373238106Sdes * Get the iterator function block. 374238106Sdes * @return: function block with function pointers to iterator methods. 375238106Sdes */ 376238106Sdesstruct module_func_block* iter_get_funcblock(void); 377238106Sdes 378238106Sdes/** 379238106Sdes * Get iterator state as a string 380238106Sdes * @param state: to convert 381238106Sdes * @return constant string that is printable. 382238106Sdes */ 383238106Sdesconst char* iter_state_to_string(enum iter_state state); 384238106Sdes 385238106Sdes/** 386238106Sdes * See if iterator state is a response state 387238106Sdes * @param s: to inspect 388238106Sdes * @return true if response state. 389238106Sdes */ 390238106Sdesint iter_state_is_responsestate(enum iter_state s); 391238106Sdes 392238106Sdes/** iterator init */ 393238106Sdesint iter_init(struct module_env* env, int id); 394238106Sdes 395238106Sdes/** iterator deinit */ 396238106Sdesvoid iter_deinit(struct module_env* env, int id); 397238106Sdes 398238106Sdes/** iterator operate on a query */ 399238106Sdesvoid iter_operate(struct module_qstate* qstate, enum module_ev event, int id, 400238106Sdes struct outbound_entry* outbound); 401238106Sdes 402238106Sdes/** 403238106Sdes * Return priming query results to interestes super querystates. 404238106Sdes * 405238106Sdes * Sets the delegation point and delegation message (not nonRD queries). 406238106Sdes * This is a callback from walk_supers. 407238106Sdes * 408238106Sdes * @param qstate: query state that finished. 409238106Sdes * @param id: module id. 410238106Sdes * @param super: the qstate to inform. 411238106Sdes */ 412238106Sdesvoid iter_inform_super(struct module_qstate* qstate, int id, 413238106Sdes struct module_qstate* super); 414238106Sdes 415238106Sdes/** iterator cleanup query state */ 416238106Sdesvoid iter_clear(struct module_qstate* qstate, int id); 417238106Sdes 418238106Sdes/** iterator alloc size routine */ 419238106Sdessize_t iter_get_mem(struct module_env* env, int id); 420238106Sdes 421238106Sdes#endif /* ITERATOR_ITERATOR_H */ 422