2 * iterator/iterator.h - iterative resolver DNS query response module
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39 * This file contains a module that performs recusive iterative DNS query
43 #ifndef ITERATOR_ITERATOR_H
44 #define ITERATOR_ITERATOR_H
45 #include "services/outbound_list.h"
46 #include "util/data/msgreply.h"
47 #include "util/module.h"
52 struct iter_prep_list;
56 /** max number of targets spawned for a query and its subqueries */
57 #define MAX_TARGET_COUNT 64
58 /** max number of query restarts. Determines max number of CNAME chain. */
59 #define MAX_RESTART_COUNT 8
60 /** max number of referrals. Makes sure resolver does not run away */
61 #define MAX_REFERRAL_COUNT 130
62 /** max number of queries-sent-out. Make sure large NS set does not loop */
63 #define MAX_SENT_COUNT 32
64 /** at what query-sent-count to stop target fetch policy */
65 #define TARGET_FETCH_STOP 3
66 /** how nice is a server without further information, in msec
67 * Equals rtt initial timeout value.
69 #define UNKNOWN_SERVER_NICENESS 376
70 /** maximum timeout before a host is deemed unsuitable, in msec.
71 * After host_ttl this will be timed out and the host will be tried again.
72 * Equals RTT_MAX_TIMEOUT
74 #define USEFUL_SERVER_TOP_TIMEOUT 120000
75 /** number of retries on outgoing queries */
76 #define OUTBOUND_MSG_RETRY 5
77 /** RTT band, within this amount from the best, servers are chosen randomly.
78 * Chosen so that the UNKNOWN_SERVER_NICENESS falls within the band of a
79 * fast server, this causes server exploration as a side benefit. msec. */
81 /** Start value for blacklisting a host, 2*USEFUL_SERVER_TOP_TIMEOUT in sec */
82 #define INFRA_BACKOFF_INITIAL 240
85 * Global state for the iterator.
88 /** A flag to indicate whether or not we have an IPv6 route */
91 /** A flag to indicate whether or not we have an IPv4 route */
94 /** A set of inetaddrs that should never be queried. */
95 struct iter_donotq* donotq;
97 /** private address space and private domains */
98 struct iter_priv* priv;
100 /** whitelist for capsforid names */
101 struct rbtree_t* caps_white;
103 /** The maximum dependency depth that this resolver will pursue. */
104 int max_dependency_depth;
107 * The target fetch policy for each dependency level. This is
108 * described as a simple number (per dependency level):
109 * negative numbers (usually just -1) mean fetch-all,
110 * 0 means only fetch on demand, and
111 * positive numbers mean to fetch at most that many targets.
112 * array of max_dependency_depth+1 size.
114 int* target_fetch_policy;
116 /** ip6.arpa dname in wireformat, used for qname-minimisation */
117 uint8_t* ip6arpa_dname;
121 * QNAME minimisation state
123 enum minimisation_state {
125 * (Re)start minimisation. Outgoing QNAME should be set to dp->name.
126 * State entered on new query or after following refferal or CNAME.
128 INIT_MINIMISE_STATE = 0,
130 * QNAME minimisataion ongoing. Increase QNAME on every iteration.
134 * Don't increment QNAME this iteration
138 * Send out full QNAME + original QTYPE
140 DONOT_MINIMISE_STATE,
144 * State of the iterator for a query.
148 * Externally generated queries start at this state. Query restarts are
149 * reset to this state.
151 INIT_REQUEST_STATE = 0,
154 * Root priming events reactivate here, most other events pass
155 * through this naturally as the 2nd part of the INIT_REQUEST_STATE.
157 INIT_REQUEST_2_STATE,
160 * Stub priming events reactivate here, most other events pass
161 * through this naturally as the 3rd part of the INIT_REQUEST_STATE.
163 INIT_REQUEST_3_STATE,
166 * Each time a delegation point changes for a given query or a
167 * query times out and/or wakes up, this state is (re)visited.
168 * This state is reponsible for iterating through a list of
169 * nameserver targets.
174 * Responses to queries start at this state. This state handles
175 * the decision tree associated with handling responses.
179 /** Responses to priming queries finish at this state. */
182 /** Collecting query class information, for qclass=ANY, when
183 * it spawns off queries for every class, it returns here. */
186 /** Find NS record to resolve DS record from, walking to the right
187 * NS spot until we find it */
190 /** Responses that are to be returned upstream end at this state.
191 * As well as responses to target queries. */
196 * Per query state for the iterator module.
200 * State of the iterator module.
201 * This is the state that event is in or should sent to -- all
202 * requests should start with the INIT_REQUEST_STATE. All
203 * responses should start with QUERY_RESP_STATE. Subsequent
204 * processing of the event will change this state.
206 enum iter_state state;
209 * Final state for the iterator module.
210 * This is the state that responses should be routed to once the
211 * response is final. For externally initiated queries, this
212 * will be FINISHED_STATE, locally initiated queries will have
213 * different final states.
215 enum iter_state final_state;
218 * The depth of this query, this means the depth of recursion.
219 * This address is needed for another query, which is an address
220 * needed for another query, etc. Original client query has depth 0.
227 struct dns_msg* response;
230 * This is a list of RRsets that must be prepended to the
231 * ANSWER section of a response before being sent upstream.
233 struct iter_prep_list* an_prepend_list;
234 /** Last element of the prepend list */
235 struct iter_prep_list* an_prepend_last;
238 * This is the list of RRsets that must be prepended to the
239 * AUTHORITY section of the response before being sent upstream.
241 struct iter_prep_list* ns_prepend_list;
242 /** Last element of the authority prepend list */
243 struct iter_prep_list* ns_prepend_last;
245 /** query name used for chasing the results. Initially the same as
246 * the state qinfo, but after CNAMEs this will be different.
247 * The query info used to elicit the results needed. */
248 struct query_info qchase;
249 /** query flags to use when chasing the answer (i.e. RD flag) */
250 uint16_t chase_flags;
251 /** true if we set RD bit because of last resort recursion lame query*/
255 * This is the current delegation point for an in-progress query. This
256 * object retains state as to which delegation targets need to be
257 * (sub)queried for vs which ones have already been visited.
261 /** state for 0x20 fallback when capsfail happens, 0 not a fallback */
263 /** state for capsfail: current server number to try */
265 /** state for capsfail: stored query for comparisons. Can be NULL if
266 * no response had been seen prior to starting the fallback. */
267 struct reply_info* caps_reply;
268 struct dns_msg* caps_response;
270 /** Current delegation message - returned for non-RD queries */
271 struct dns_msg* deleg_msg;
273 /** number of outstanding target sub queries */
274 int num_target_queries;
276 /** outstanding direct queries */
277 int num_current_queries;
279 /** the number of times this query has been restarted. */
280 int query_restart_count;
282 /** the number of times this query as followed a referral. */
285 /** number of queries fired off */
288 /** number of target queries spawned in [1], for this query and its
289 * subqueries, the malloced-array is shared, [0] refcount. */
292 /** if true, already tested for ratelimiting and passed the test */
296 * The query must store NS records from referrals as parentside RRs
297 * Enabled once it hits resolution problems, to throttle retries.
298 * If enabled it is the pointer to the old delegation point with
299 * the old retry counts for bad-nameserver-addresses.
301 struct delegpt* store_parent_NS;
304 * The query is for parent-side glue(A or AAAA) for a nameserver.
305 * If the item is seen as glue in a referral, and pside_glue is NULL,
306 * then it is stored in pside_glue for later.
307 * If it was never seen, at the end, then a negative caching element
309 * The (data or negative) RR cache element then throttles retries.
311 int query_for_pside_glue;
312 /** the parent-side-glue element (NULL if none, its first match) */
313 struct ub_packed_rrset_key* pside_glue;
315 /** If nonNULL we are walking upwards from DS query to find NS */
317 /** length of the dname in dsns_point */
318 size_t dsns_point_len;
321 * expected dnssec information for this iteration step.
322 * If dnssec rrsigs are expected and not given, the server is marked
323 * lame (dnssec-lame).
328 * We are expecting dnssec information, but we also know the server
329 * is DNSSEC lame. The response need not be marked dnssec-lame again.
331 int dnssec_lame_query;
334 * This is flag that, if true, means that this event is
335 * waiting for a stub priming query.
337 int wait_priming_stub;
340 * This is a flag that, if true, means that this query is
341 * for (re)fetching glue from a zone. Since the address should
342 * have been glue, query again to the servers that should have
343 * been returning it as glue.
344 * The delegation point must be set to the one that should *not*
345 * be used when creating the state. A higher one will be attempted.
349 /** list of pending queries to authoritative servers. */
350 struct outbound_list outlist;
352 /** QNAME minimisation state */
353 enum minimisation_state minimisation_state;
356 * The query info that is sent upstream. Will be a subset of qchase
357 * when qname minimisation is enabled.
359 struct query_info qinfo_out;
363 * List of prepend items
365 struct iter_prep_list {
367 struct iter_prep_list* next;
369 struct ub_packed_rrset_key* rrset;
373 * Get the iterator function block.
374 * @return: function block with function pointers to iterator methods.
376 struct module_func_block* iter_get_funcblock(void);
379 * Get iterator state as a string
380 * @param state: to convert
381 * @return constant string that is printable.
383 const char* iter_state_to_string(enum iter_state state);
386 * See if iterator state is a response state
387 * @param s: to inspect
388 * @return true if response state.
390 int iter_state_is_responsestate(enum iter_state s);
393 int iter_init(struct module_env* env, int id);
395 /** iterator deinit */
396 void iter_deinit(struct module_env* env, int id);
398 /** iterator operate on a query */
399 void iter_operate(struct module_qstate* qstate, enum module_ev event, int id,
400 struct outbound_entry* outbound);
403 * Return priming query results to interestes super querystates.
405 * Sets the delegation point and delegation message (not nonRD queries).
406 * This is a callback from walk_supers.
408 * @param qstate: query state that finished.
409 * @param id: module id.
410 * @param super: the qstate to inform.
412 void iter_inform_super(struct module_qstate* qstate, int id,
413 struct module_qstate* super);
415 /** iterator cleanup query state */
416 void iter_clear(struct module_qstate* qstate, int id);
418 /** iterator alloc size routine */
419 size_t iter_get_mem(struct module_env* env, int id);
421 #endif /* ITERATOR_ITERATOR_H */