2 * Copyright (C) 2004-2010 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2001, 2003 Internet Software Consortium.
5 * Permission to use, copy, modify, and/or distribute this software for any
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18 /* $Id: resolver.h,v 1.60.56.3.22.2 2010/02/25 10:57:12 tbox Exp $ */
20 #ifndef DNS_RESOLVER_H
21 #define DNS_RESOLVER_H 1
27 /*! \file dns/resolver.h
30 * This is the BIND 9 resolver, the module responsible for resolving DNS
31 * requests by iteratively querying authoritative servers and following
32 * referrals. This is a "full resolver", not to be confused with
33 * the stub resolvers most people associate with the word "resolver".
34 * The full resolver is part of the caching name server or resolver
35 * daemon the stub resolver talks to.
38 *\li The module ensures appropriate synchronization of data structures it
39 * creates and manipulates.
42 *\li No anticipated impact.
48 *\li No anticipated impact.
51 *\li RFCs: 1034, 1035, 2181, TBS
56 #include <isc/socket.h>
58 #include <dns/types.h>
59 #include <dns/fixedname.h>
64 * A dns_fetchevent_t is sent when a 'fetch' completes. Any of 'db',
65 * 'node', 'rdataset', and 'sigrdataset' may be bound. It is the
66 * receiver's responsibility to detach before freeing the event.
68 * 'rdataset', 'sigrdataset', 'client' and 'id' are the values that were
69 * supplied when dns_resolver_createfetch() was called. They are returned
70 * to the caller so that they may be freed.
72 typedef struct dns_fetchevent {
73 ISC_EVENT_COMMON(struct dns_fetchevent);
76 dns_rdatatype_t qtype;
79 dns_rdataset_t * rdataset;
80 dns_rdataset_t * sigrdataset;
81 dns_fixedname_t foundname;
82 isc_sockaddr_t * client;
87 * Options that modify how a 'fetch' is done.
89 #define DNS_FETCHOPT_TCP 0x01 /*%< Use TCP. */
90 #define DNS_FETCHOPT_UNSHARED 0x02 /*%< See below. */
91 #define DNS_FETCHOPT_RECURSIVE 0x04 /*%< Set RD? */
92 #define DNS_FETCHOPT_NOEDNS0 0x08 /*%< Do not use EDNS. */
93 #define DNS_FETCHOPT_FORWARDONLY 0x10 /*%< Only use forwarders. */
94 #define DNS_FETCHOPT_NOVALIDATE 0x20 /*%< Disable validation. */
95 #define DNS_FETCHOPT_EDNS512 0x40 /*%< Advertise a 512 byte
97 #define DNS_FETCHOPT_WANTNSID 0x80 /*%< Request NSID */
99 #define DNS_FETCHOPT_EDNSVERSIONSET 0x00800000
100 #define DNS_FETCHOPT_EDNSVERSIONMASK 0xff000000
101 #define DNS_FETCHOPT_EDNSVERSIONSHIFT 24
104 * Upper bounds of class of query RTT (ms). Corresponds to
105 * dns_resstatscounter_queryrttX statistics counters.
107 #define DNS_RESOLVER_QRYRTTCLASS0 10
108 #define DNS_RESOLVER_QRYRTTCLASS0STR "10"
109 #define DNS_RESOLVER_QRYRTTCLASS1 100
110 #define DNS_RESOLVER_QRYRTTCLASS1STR "100"
111 #define DNS_RESOLVER_QRYRTTCLASS2 500
112 #define DNS_RESOLVER_QRYRTTCLASS2STR "500"
113 #define DNS_RESOLVER_QRYRTTCLASS3 800
114 #define DNS_RESOLVER_QRYRTTCLASS3STR "800"
115 #define DNS_RESOLVER_QRYRTTCLASS4 1600
116 #define DNS_RESOLVER_QRYRTTCLASS4STR "1600"
119 * XXXRTH Should this API be made semi-private? (I.e.
120 * _dns_resolver_create()).
123 #define DNS_RESOLVER_CHECKNAMES 0x01
124 #define DNS_RESOLVER_CHECKNAMESFAIL 0x02
127 dns_resolver_create(dns_view_t *view,
128 isc_taskmgr_t *taskmgr, unsigned int ntasks,
129 isc_socketmgr_t *socketmgr,
130 isc_timermgr_t *timermgr,
131 unsigned int options,
132 dns_dispatchmgr_t *dispatchmgr,
133 dns_dispatch_t *dispatchv4,
134 dns_dispatch_t *dispatchv6,
135 dns_resolver_t **resp);
142 *\li Generally, applications should not create a resolver directly, but
143 * should instead call dns_view_createresolver().
147 *\li 'view' is a valid view.
149 *\li 'taskmgr' is a valid task manager.
153 *\li 'socketmgr' is a valid socket manager.
155 *\li 'timermgr' is a valid timer manager.
157 *\li 'dispatchv4' is a valid dispatcher with an IPv4 UDP socket, or is NULL.
159 *\li 'dispatchv6' is a valid dispatcher with an IPv6 UDP socket, or is NULL.
161 *\li resp != NULL && *resp == NULL.
165 *\li #ISC_R_SUCCESS On success.
167 *\li Anything else Failure.
171 dns_resolver_freeze(dns_resolver_t *res);
177 *\li Certain configuration changes cannot be made after the resolver
178 * is frozen. Fetches cannot be created until the resolver is frozen.
182 *\li 'res' is a valid, unfrozen resolver.
186 *\li 'res' is frozen.
190 dns_resolver_prime(dns_resolver_t *res);
196 *\li Resolvers which have a forwarding policy other than dns_fwdpolicy_only
197 * need to be primed with the root nameservers, otherwise the root
198 * nameserver hints data may be used indefinitely. This function requests
199 * that the resolver start a priming fetch, if it isn't already priming.
203 *\li 'res' is a valid, frozen resolver.
208 dns_resolver_whenshutdown(dns_resolver_t *res, isc_task_t *task,
209 isc_event_t **eventp);
211 * Send '*eventp' to 'task' when 'res' has completed shutdown.
215 *\li It is not safe to detach the last reference to 'res' until
216 * shutdown is complete.
220 *\li 'res' is a valid resolver.
222 *\li 'task' is a valid task.
224 *\li *eventp is a valid event.
228 *\li *eventp == NULL.
232 dns_resolver_shutdown(dns_resolver_t *res);
234 * Start the shutdown process for 'res'.
238 *\li This call has no effect if the resolver is already shutting down.
242 *\li 'res' is a valid resolver.
246 dns_resolver_attach(dns_resolver_t *source, dns_resolver_t **targetp);
249 dns_resolver_detach(dns_resolver_t **resp);
252 dns_resolver_createfetch(dns_resolver_t *res, dns_name_t *name,
253 dns_rdatatype_t type,
254 dns_name_t *domain, dns_rdataset_t *nameservers,
255 dns_forwarders_t *forwarders,
256 unsigned int options, isc_task_t *task,
257 isc_taskaction_t action, void *arg,
258 dns_rdataset_t *rdataset,
259 dns_rdataset_t *sigrdataset,
260 dns_fetch_t **fetchp);
263 dns_resolver_createfetch2(dns_resolver_t *res, dns_name_t *name,
264 dns_rdatatype_t type,
265 dns_name_t *domain, dns_rdataset_t *nameservers,
266 dns_forwarders_t *forwarders,
267 isc_sockaddr_t *client, isc_uint16_t id,
268 unsigned int options, isc_task_t *task,
269 isc_taskaction_t action, void *arg,
270 dns_rdataset_t *rdataset,
271 dns_rdataset_t *sigrdataset,
272 dns_fetch_t **fetchp);
274 * Recurse to answer a question.
278 *\li This call starts a query for 'name', type 'type'.
280 *\li The 'domain' is a parent domain of 'name' for which
281 * a set of name servers 'nameservers' is known. If no
282 * such name server information is available, set
283 * 'domain' and 'nameservers' to NULL.
285 *\li 'forwarders' is unimplemented, and subject to change when
286 * we figure out how selective forwarding will work.
288 *\li When the fetch completes (successfully or otherwise), a
289 * #DNS_EVENT_FETCHDONE event with action 'action' and arg 'arg' will be
292 *\li The values of 'rdataset' and 'sigrdataset' will be returned in
293 * the FETCHDONE event.
295 *\li 'client' and 'id' are used for duplicate query detection. '*client'
296 * must remain stable until after 'action' has been called or
297 * dns_resolver_cancelfetch() is called.
301 *\li 'res' is a valid resolver that has been frozen.
303 *\li 'name' is a valid name.
305 *\li 'type' is not a meta type other than ANY.
307 *\li 'domain' is a valid name or NULL.
309 *\li 'nameservers' is a valid NS rdataset (whose owner name is 'domain')
310 * iff. 'domain' is not NULL.
312 *\li 'forwarders' is NULL.
314 *\li 'client' is a valid sockaddr or NULL.
316 *\li 'options' contains valid options.
318 *\li 'rdataset' is a valid, disassociated rdataset.
320 *\li 'sigrdataset' is NULL, or is a valid, disassociated rdataset.
322 *\li fetchp != NULL && *fetchp == NULL.
326 *\li #ISC_R_SUCCESS Success
327 *\li #DNS_R_DUPLICATE
330 *\li Many other values are possible, all of which indicate failure.
334 dns_resolver_cancelfetch(dns_fetch_t *fetch);
340 *\li If 'fetch' has not completed, post its FETCHDONE event with a
341 * result code of #ISC_R_CANCELED.
345 *\li 'fetch' is a valid fetch.
349 dns_resolver_destroyfetch(dns_fetch_t **fetchp);
355 *\li '*fetchp' is a valid fetch.
357 *\li The caller has received the FETCHDONE event (either because the
358 * fetch completed or because dns_resolver_cancelfetch() was called).
362 *\li *fetchp == NULL.
366 dns_resolver_logfetch(dns_fetch_t *fetch, isc_log_t *lctx,
367 isc_logcategory_t *category, isc_logmodule_t *module,
368 int level, isc_boolean_t duplicateok);
370 * Dump a log message on internal state at the completion of given 'fetch'.
371 * 'lctx', 'category', 'module', and 'level' are used to write the log message.
372 * By default, only one log message is written even if the corresponding fetch
373 * context serves multiple clients; if 'duplicateok' is true the suppression
374 * is disabled and the message can be written every time this function is
379 *\li 'fetch' is a valid fetch, and has completed.
383 dns_resolver_dispatchmgr(dns_resolver_t *resolver);
386 dns_resolver_dispatchv4(dns_resolver_t *resolver);
389 dns_resolver_dispatchv6(dns_resolver_t *resolver);
392 dns_resolver_socketmgr(dns_resolver_t *resolver);
395 dns_resolver_taskmgr(dns_resolver_t *resolver);
398 dns_resolver_getlamettl(dns_resolver_t *resolver);
400 * Get the resolver's lame-ttl. zero => no lame processing.
403 *\li 'resolver' to be valid.
407 dns_resolver_setlamettl(dns_resolver_t *resolver, isc_uint32_t lame_ttl);
409 * Set the resolver's lame-ttl. zero => no lame processing.
412 *\li 'resolver' to be valid.
416 dns_resolver_nrunning(dns_resolver_t *resolver);
418 * Return the number of currently running resolutions in this
419 * resolver. This is may be less than the number of outstanding
420 * fetches due to multiple identical fetches, or more than the
421 * number of of outstanding fetches due to the fact that resolution
422 * can continue even though a fetch has been canceled.
426 dns_resolver_addalternate(dns_resolver_t *resolver, isc_sockaddr_t *alt,
427 dns_name_t *name, in_port_t port);
429 * Add alternate addresses to be tried in the event that the nameservers
430 * for a zone are not available in the address families supported by the
434 * \li only one of 'name' or 'alt' to be valid.
438 dns_resolver_setudpsize(dns_resolver_t *resolver, isc_uint16_t udpsize);
440 * Set the EDNS UDP buffer size advertised by the server.
444 dns_resolver_getudpsize(dns_resolver_t *resolver);
446 * Get the current EDNS UDP buffer size.
450 dns_resolver_reset_algorithms(dns_resolver_t *resolver);
452 * Clear the disabled DNSSEC algorithms.
456 dns_resolver_disable_algorithm(dns_resolver_t *resolver, dns_name_t *name,
459 * Mark the give DNSSEC algorithm as disabled and below 'name'.
460 * Valid algorithms are less than 256.
469 dns_resolver_algorithm_supported(dns_resolver_t *resolver, dns_name_t *name,
472 * Check if the given algorithm is supported by this resolver.
473 * This checks if the algorithm has been disabled via
474 * dns_resolver_disable_algorithm() then the underlying
475 * crypto libraries if not specifically disabled.
479 dns_resolver_digest_supported(dns_resolver_t *resolver, unsigned int digest_type);
481 * Is this digest type supported.
485 dns_resolver_resetmustbesecure(dns_resolver_t *resolver);
488 dns_resolver_setmustbesecure(dns_resolver_t *resolver, dns_name_t *name,
489 isc_boolean_t value);
492 dns_resolver_getmustbesecure(dns_resolver_t *resolver, dns_name_t *name);
495 dns_resolver_setclientsperquery(dns_resolver_t *resolver,
496 isc_uint32_t min, isc_uint32_t max);
499 dns_resolver_getclientsperquery(dns_resolver_t *resolver, isc_uint32_t *cur,
500 isc_uint32_t *min, isc_uint32_t *max);
503 dns_resolver_getzeronosoattl(dns_resolver_t *resolver);
506 dns_resolver_setzeronosoattl(dns_resolver_t *resolver, isc_boolean_t state);
509 dns_resolver_getoptions(dns_resolver_t *resolver);
512 dns_resolver_addbadcache(dns_resolver_t *resolver, dns_name_t *name,
513 dns_rdatatype_t type, isc_time_t *expire);
515 * Add a entry to the bad cache for <name,type> that will expire at 'expire'.
518 * \li resolver to be valid.
519 * \li name to be valid.
523 dns_resolver_getbadcache(dns_resolver_t *resolver, dns_name_t *name,
524 dns_rdatatype_t type, isc_time_t *now);
526 * Check to see if there is a unexpired entry in the bad cache for
530 * \li resolver to be valid.
531 * \li name to be valid.
535 dns_resolver_flushbadcache(dns_resolver_t *resolver, dns_name_t *name);
537 * Flush the bad cache of all entries at 'name' if 'name' is non NULL.
538 * Flush the entire bad cache if 'name' is NULL.
541 * \li resolver to be valid.
545 dns_resolver_printbadcache(dns_resolver_t *resolver, FILE *fp);
547 * Print out the contents of the bad cache to 'fp'.
550 * \li resolver to be valid.
555 #endif /* DNS_RESOLVER_H */