iterator.h revision 269257
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; 54238106Sdes 55238106Sdes/** max number of query restarts. Determines max number of CNAME chain. */ 56238106Sdes#define MAX_RESTART_COUNT 8 57238106Sdes/** max number of referrals. Makes sure resolver does not run away */ 58238106Sdes#define MAX_REFERRAL_COUNT 130 59238106Sdes/** max number of queries-sent-out. Make sure large NS set does not loop */ 60238106Sdes#define MAX_SENT_COUNT 16 61238106Sdes/** at what query-sent-count to stop target fetch policy */ 62238106Sdes#define TARGET_FETCH_STOP 3 63238106Sdes/** how nice is a server without further information, in msec 64238106Sdes * Equals rtt initial timeout value. 65238106Sdes */ 66238106Sdes#define UNKNOWN_SERVER_NICENESS 376 67238106Sdes/** maximum timeout before a host is deemed unsuitable, in msec. 68238106Sdes * After host_ttl this will be timed out and the host will be tried again. 69238106Sdes * Equals RTT_MAX_TIMEOUT 70238106Sdes */ 71238106Sdes#define USEFUL_SERVER_TOP_TIMEOUT 120000 72238106Sdes/** Number of lost messages in a row that get a host blacklisted. 73238106Sdes * With 16, a couple different queries have to time out and no working 74238106Sdes * queries are happening */ 75238106Sdes#define USEFUL_SERVER_MAX_LOST 16 76238106Sdes/** number of retries on outgoing queries */ 77238106Sdes#define OUTBOUND_MSG_RETRY 5 78238106Sdes/** RTT band, within this amount from the best, servers are chosen randomly. 79238106Sdes * Chosen so that the UNKNOWN_SERVER_NICENESS falls within the band of a 80238106Sdes * fast server, this causes server exploration as a side benefit. msec. */ 81238106Sdes#define RTT_BAND 400 82238106Sdes/** Start value for blacklisting a host, 2*USEFUL_SERVER_TOP_TIMEOUT in sec */ 83238106Sdes#define INFRA_BACKOFF_INITIAL 240 84238106Sdes 85238106Sdes/** 86238106Sdes * Global state for the iterator. 87238106Sdes */ 88238106Sdesstruct iter_env { 89238106Sdes /** A flag to indicate whether or not we have an IPv6 route */ 90238106Sdes int supports_ipv6; 91238106Sdes 92238106Sdes /** A flag to indicate whether or not we have an IPv4 route */ 93238106Sdes int supports_ipv4; 94238106Sdes 95238106Sdes /** A set of inetaddrs that should never be queried. */ 96238106Sdes struct iter_donotq* donotq; 97238106Sdes 98238106Sdes /** private address space and private domains */ 99238106Sdes struct iter_priv* priv; 100238106Sdes 101238106Sdes /** The maximum dependency depth that this resolver will pursue. */ 102238106Sdes int max_dependency_depth; 103238106Sdes 104238106Sdes /** 105238106Sdes * The target fetch policy for each dependency level. This is 106238106Sdes * described as a simple number (per dependency level): 107238106Sdes * negative numbers (usually just -1) mean fetch-all, 108238106Sdes * 0 means only fetch on demand, and 109238106Sdes * positive numbers mean to fetch at most that many targets. 110238106Sdes * array of max_dependency_depth+1 size. 111238106Sdes */ 112238106Sdes int* target_fetch_policy; 113238106Sdes}; 114238106Sdes 115238106Sdes/** 116238106Sdes * State of the iterator for a query. 117238106Sdes */ 118238106Sdesenum iter_state { 119238106Sdes /** 120238106Sdes * Externally generated queries start at this state. Query restarts are 121238106Sdes * reset to this state. 122238106Sdes */ 123238106Sdes INIT_REQUEST_STATE = 0, 124238106Sdes 125238106Sdes /** 126238106Sdes * Root priming events reactivate here, most other events pass 127238106Sdes * through this naturally as the 2nd part of the INIT_REQUEST_STATE. 128238106Sdes */ 129238106Sdes INIT_REQUEST_2_STATE, 130238106Sdes 131238106Sdes /** 132238106Sdes * Stub priming events reactivate here, most other events pass 133238106Sdes * through this naturally as the 3rd part of the INIT_REQUEST_STATE. 134238106Sdes */ 135238106Sdes INIT_REQUEST_3_STATE, 136238106Sdes 137238106Sdes /** 138238106Sdes * Each time a delegation point changes for a given query or a 139238106Sdes * query times out and/or wakes up, this state is (re)visited. 140238106Sdes * This state is reponsible for iterating through a list of 141238106Sdes * nameserver targets. 142238106Sdes */ 143238106Sdes QUERYTARGETS_STATE, 144238106Sdes 145238106Sdes /** 146238106Sdes * Responses to queries start at this state. This state handles 147238106Sdes * the decision tree associated with handling responses. 148238106Sdes */ 149238106Sdes QUERY_RESP_STATE, 150238106Sdes 151238106Sdes /** Responses to priming queries finish at this state. */ 152238106Sdes PRIME_RESP_STATE, 153238106Sdes 154238106Sdes /** Collecting query class information, for qclass=ANY, when 155238106Sdes * it spawns off queries for every class, it returns here. */ 156238106Sdes COLLECT_CLASS_STATE, 157238106Sdes 158238106Sdes /** Find NS record to resolve DS record from, walking to the right 159238106Sdes * NS spot until we find it */ 160238106Sdes DSNS_FIND_STATE, 161238106Sdes 162238106Sdes /** Responses that are to be returned upstream end at this state. 163238106Sdes * As well as responses to target queries. */ 164238106Sdes FINISHED_STATE 165238106Sdes}; 166238106Sdes 167238106Sdes/** 168238106Sdes * Per query state for the iterator module. 169238106Sdes */ 170238106Sdesstruct iter_qstate { 171238106Sdes /** 172238106Sdes * State of the iterator module. 173238106Sdes * This is the state that event is in or should sent to -- all 174238106Sdes * requests should start with the INIT_REQUEST_STATE. All 175238106Sdes * responses should start with QUERY_RESP_STATE. Subsequent 176238106Sdes * processing of the event will change this state. 177238106Sdes */ 178238106Sdes enum iter_state state; 179238106Sdes 180238106Sdes /** 181238106Sdes * Final state for the iterator module. 182238106Sdes * This is the state that responses should be routed to once the 183238106Sdes * response is final. For externally initiated queries, this 184238106Sdes * will be FINISHED_STATE, locally initiated queries will have 185238106Sdes * different final states. 186238106Sdes */ 187238106Sdes enum iter_state final_state; 188238106Sdes 189238106Sdes /** 190238106Sdes * The depth of this query, this means the depth of recursion. 191238106Sdes * This address is needed for another query, which is an address 192238106Sdes * needed for another query, etc. Original client query has depth 0. 193238106Sdes */ 194238106Sdes int depth; 195238106Sdes 196238106Sdes /** 197238106Sdes * The response 198238106Sdes */ 199238106Sdes struct dns_msg* response; 200238106Sdes 201238106Sdes /** 202238106Sdes * This is a list of RRsets that must be prepended to the 203238106Sdes * ANSWER section of a response before being sent upstream. 204238106Sdes */ 205238106Sdes struct iter_prep_list* an_prepend_list; 206238106Sdes /** Last element of the prepend list */ 207238106Sdes struct iter_prep_list* an_prepend_last; 208238106Sdes 209238106Sdes /** 210238106Sdes * This is the list of RRsets that must be prepended to the 211238106Sdes * AUTHORITY section of the response before being sent upstream. 212238106Sdes */ 213238106Sdes struct iter_prep_list* ns_prepend_list; 214238106Sdes /** Last element of the authority prepend list */ 215238106Sdes struct iter_prep_list* ns_prepend_last; 216238106Sdes 217238106Sdes /** query name used for chasing the results. Initially the same as 218238106Sdes * the state qinfo, but after CNAMEs this will be different. 219238106Sdes * The query info used to elicit the results needed. */ 220238106Sdes struct query_info qchase; 221238106Sdes /** query flags to use when chasing the answer (i.e. RD flag) */ 222238106Sdes uint16_t chase_flags; 223238106Sdes /** true if we set RD bit because of last resort recursion lame query*/ 224238106Sdes int chase_to_rd; 225238106Sdes 226238106Sdes /** 227238106Sdes * This is the current delegation point for an in-progress query. This 228238106Sdes * object retains state as to which delegation targets need to be 229238106Sdes * (sub)queried for vs which ones have already been visited. 230238106Sdes */ 231238106Sdes struct delegpt* dp; 232238106Sdes 233238106Sdes /** state for 0x20 fallback when capsfail happens, 0 not a fallback */ 234238106Sdes int caps_fallback; 235238106Sdes /** state for capsfail: current server number to try */ 236238106Sdes size_t caps_server; 237238106Sdes /** state for capsfail: stored query for comparisons */ 238238106Sdes struct reply_info* caps_reply; 239238106Sdes 240238106Sdes /** Current delegation message - returned for non-RD queries */ 241238106Sdes struct dns_msg* deleg_msg; 242238106Sdes 243238106Sdes /** number of outstanding target sub queries */ 244238106Sdes int num_target_queries; 245238106Sdes 246238106Sdes /** outstanding direct queries */ 247238106Sdes int num_current_queries; 248238106Sdes 249238106Sdes /** the number of times this query has been restarted. */ 250238106Sdes int query_restart_count; 251238106Sdes 252238106Sdes /** the number of times this query as followed a referral. */ 253238106Sdes int referral_count; 254238106Sdes 255238106Sdes /** number of queries fired off */ 256238106Sdes int sent_count; 257238106Sdes 258238106Sdes /** 259238106Sdes * The query must store NS records from referrals as parentside RRs 260238106Sdes * Enabled once it hits resolution problems, to throttle retries. 261238106Sdes * If enabled it is the pointer to the old delegation point with 262238106Sdes * the old retry counts for bad-nameserver-addresses. 263238106Sdes */ 264238106Sdes struct delegpt* store_parent_NS; 265238106Sdes 266238106Sdes /** 267238106Sdes * The query is for parent-side glue(A or AAAA) for a nameserver. 268238106Sdes * If the item is seen as glue in a referral, and pside_glue is NULL, 269238106Sdes * then it is stored in pside_glue for later. 270238106Sdes * If it was never seen, at the end, then a negative caching element 271238106Sdes * must be created. 272238106Sdes * The (data or negative) RR cache element then throttles retries. 273238106Sdes */ 274238106Sdes int query_for_pside_glue; 275238106Sdes /** the parent-side-glue element (NULL if none, its first match) */ 276238106Sdes struct ub_packed_rrset_key* pside_glue; 277238106Sdes 278238106Sdes /** If nonNULL we are walking upwards from DS query to find NS */ 279238106Sdes uint8_t* dsns_point; 280238106Sdes /** length of the dname in dsns_point */ 281238106Sdes size_t dsns_point_len; 282238106Sdes 283238106Sdes /** 284238106Sdes * expected dnssec information for this iteration step. 285238106Sdes * If dnssec rrsigs are expected and not given, the server is marked 286238106Sdes * lame (dnssec-lame). 287238106Sdes */ 288238106Sdes int dnssec_expected; 289238106Sdes 290238106Sdes /** 291238106Sdes * We are expecting dnssec information, but we also know the server 292238106Sdes * is DNSSEC lame. The response need not be marked dnssec-lame again. 293238106Sdes */ 294238106Sdes int dnssec_lame_query; 295238106Sdes 296238106Sdes /** 297238106Sdes * This is flag that, if true, means that this event is 298238106Sdes * waiting for a stub priming query. 299238106Sdes */ 300238106Sdes int wait_priming_stub; 301238106Sdes 302238106Sdes /** 303238106Sdes * This is a flag that, if true, means that this query is 304238106Sdes * for (re)fetching glue from a zone. Since the address should 305238106Sdes * have been glue, query again to the servers that should have 306238106Sdes * been returning it as glue. 307238106Sdes * The delegation point must be set to the one that should *not* 308238106Sdes * be used when creating the state. A higher one will be attempted. 309238106Sdes */ 310238106Sdes int refetch_glue; 311238106Sdes 312238106Sdes /** list of pending queries to authoritative servers. */ 313238106Sdes struct outbound_list outlist; 314238106Sdes}; 315238106Sdes 316238106Sdes/** 317238106Sdes * List of prepend items 318238106Sdes */ 319238106Sdesstruct iter_prep_list { 320238106Sdes /** next in list */ 321238106Sdes struct iter_prep_list* next; 322238106Sdes /** rrset */ 323238106Sdes struct ub_packed_rrset_key* rrset; 324238106Sdes}; 325238106Sdes 326238106Sdes/** 327238106Sdes * Get the iterator function block. 328238106Sdes * @return: function block with function pointers to iterator methods. 329238106Sdes */ 330238106Sdesstruct module_func_block* iter_get_funcblock(void); 331238106Sdes 332238106Sdes/** 333238106Sdes * Get iterator state as a string 334238106Sdes * @param state: to convert 335238106Sdes * @return constant string that is printable. 336238106Sdes */ 337238106Sdesconst char* iter_state_to_string(enum iter_state state); 338238106Sdes 339238106Sdes/** 340238106Sdes * See if iterator state is a response state 341238106Sdes * @param s: to inspect 342238106Sdes * @return true if response state. 343238106Sdes */ 344238106Sdesint iter_state_is_responsestate(enum iter_state s); 345238106Sdes 346238106Sdes/** iterator init */ 347238106Sdesint iter_init(struct module_env* env, int id); 348238106Sdes 349238106Sdes/** iterator deinit */ 350238106Sdesvoid iter_deinit(struct module_env* env, int id); 351238106Sdes 352238106Sdes/** iterator operate on a query */ 353238106Sdesvoid iter_operate(struct module_qstate* qstate, enum module_ev event, int id, 354238106Sdes struct outbound_entry* outbound); 355238106Sdes 356238106Sdes/** 357238106Sdes * Return priming query results to interestes super querystates. 358238106Sdes * 359238106Sdes * Sets the delegation point and delegation message (not nonRD queries). 360238106Sdes * This is a callback from walk_supers. 361238106Sdes * 362238106Sdes * @param qstate: query state that finished. 363238106Sdes * @param id: module id. 364238106Sdes * @param super: the qstate to inform. 365238106Sdes */ 366238106Sdesvoid iter_inform_super(struct module_qstate* qstate, int id, 367238106Sdes struct module_qstate* super); 368238106Sdes 369238106Sdes/** iterator cleanup query state */ 370238106Sdesvoid iter_clear(struct module_qstate* qstate, int id); 371238106Sdes 372238106Sdes/** iterator alloc size routine */ 373238106Sdessize_t iter_get_mem(struct module_env* env, int id); 374238106Sdes 375238106Sdes#endif /* ITERATOR_ITERATOR_H */ 376