2 * Copyright (C) 2004-2012 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
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
18 /* $Id: resolver.h,v 1.72 2011/12/05 17:10:51 each 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;
89 * Options that modify how a 'fetch' is done.
91 #define DNS_FETCHOPT_TCP 0x01 /*%< Use TCP. */
92 #define DNS_FETCHOPT_UNSHARED 0x02 /*%< See below. */
93 #define DNS_FETCHOPT_RECURSIVE 0x04 /*%< Set RD? */
94 #define DNS_FETCHOPT_NOEDNS0 0x08 /*%< Do not use EDNS. */
95 #define DNS_FETCHOPT_FORWARDONLY 0x10 /*%< Only use forwarders. */
96 #define DNS_FETCHOPT_NOVALIDATE 0x20 /*%< Disable validation. */
97 #define DNS_FETCHOPT_EDNS512 0x40 /*%< Advertise a 512 byte
99 #define DNS_FETCHOPT_WANTNSID 0x80 /*%< Request NSID */
101 #define DNS_FETCHOPT_EDNSVERSIONSET 0x00800000
102 #define DNS_FETCHOPT_EDNSVERSIONMASK 0xff000000
103 #define DNS_FETCHOPT_EDNSVERSIONSHIFT 24
106 * Upper bounds of class of query RTT (ms). Corresponds to
107 * dns_resstatscounter_queryrttX statistics counters.
109 #define DNS_RESOLVER_QRYRTTCLASS0 10
110 #define DNS_RESOLVER_QRYRTTCLASS0STR "10"
111 #define DNS_RESOLVER_QRYRTTCLASS1 100
112 #define DNS_RESOLVER_QRYRTTCLASS1STR "100"
113 #define DNS_RESOLVER_QRYRTTCLASS2 500
114 #define DNS_RESOLVER_QRYRTTCLASS2STR "500"
115 #define DNS_RESOLVER_QRYRTTCLASS3 800
116 #define DNS_RESOLVER_QRYRTTCLASS3STR "800"
117 #define DNS_RESOLVER_QRYRTTCLASS4 1600
118 #define DNS_RESOLVER_QRYRTTCLASS4STR "1600"
121 * XXXRTH Should this API be made semi-private? (I.e.
122 * _dns_resolver_create()).
125 #define DNS_RESOLVER_CHECKNAMES 0x01
126 #define DNS_RESOLVER_CHECKNAMESFAIL 0x02
129 dns_resolver_create(dns_view_t *view,
130 isc_taskmgr_t *taskmgr,
131 unsigned int ntasks, unsigned int ndisp,
132 isc_socketmgr_t *socketmgr,
133 isc_timermgr_t *timermgr,
134 unsigned int options,
135 dns_dispatchmgr_t *dispatchmgr,
136 dns_dispatch_t *dispatchv4,
137 dns_dispatch_t *dispatchv6,
138 dns_resolver_t **resp);
145 *\li Generally, applications should not create a resolver directly, but
146 * should instead call dns_view_createresolver().
150 *\li 'view' is a valid view.
152 *\li 'taskmgr' is a valid task manager.
156 *\li 'socketmgr' is a valid socket manager.
158 *\li 'timermgr' is a valid timer manager.
160 *\li 'dispatchv4' is a dispatch with an IPv4 UDP socket, or is NULL.
161 * If not NULL, 'ndisp' clones of it will be created by the resolver.
163 *\li 'dispatchv6' is a dispatch with an IPv6 UDP socket, or is NULL.
164 * If not NULL, 'ndisp' clones of it will be created by the resolver.
166 *\li resp != NULL && *resp == NULL.
170 *\li #ISC_R_SUCCESS On success.
172 *\li Anything else Failure.
176 dns_resolver_freeze(dns_resolver_t *res);
182 *\li Certain configuration changes cannot be made after the resolver
183 * is frozen. Fetches cannot be created until the resolver is frozen.
187 *\li 'res' is a valid resolver.
191 *\li 'res' is frozen.
195 dns_resolver_prime(dns_resolver_t *res);
201 *\li Resolvers which have a forwarding policy other than dns_fwdpolicy_only
202 * need to be primed with the root nameservers, otherwise the root
203 * nameserver hints data may be used indefinitely. This function requests
204 * that the resolver start a priming fetch, if it isn't already priming.
208 *\li 'res' is a valid, frozen resolver.
213 dns_resolver_whenshutdown(dns_resolver_t *res, isc_task_t *task,
214 isc_event_t **eventp);
216 * Send '*eventp' to 'task' when 'res' has completed shutdown.
220 *\li It is not safe to detach the last reference to 'res' until
221 * shutdown is complete.
225 *\li 'res' is a valid resolver.
227 *\li 'task' is a valid task.
229 *\li *eventp is a valid event.
233 *\li *eventp == NULL.
237 dns_resolver_shutdown(dns_resolver_t *res);
239 * Start the shutdown process for 'res'.
243 *\li This call has no effect if the resolver is already shutting down.
247 *\li 'res' is a valid resolver.
251 dns_resolver_attach(dns_resolver_t *source, dns_resolver_t **targetp);
254 dns_resolver_detach(dns_resolver_t **resp);
257 dns_resolver_createfetch(dns_resolver_t *res, dns_name_t *name,
258 dns_rdatatype_t type,
259 dns_name_t *domain, dns_rdataset_t *nameservers,
260 dns_forwarders_t *forwarders,
261 unsigned int options, isc_task_t *task,
262 isc_taskaction_t action, void *arg,
263 dns_rdataset_t *rdataset,
264 dns_rdataset_t *sigrdataset,
265 dns_fetch_t **fetchp);
268 dns_resolver_createfetch2(dns_resolver_t *res, dns_name_t *name,
269 dns_rdatatype_t type,
270 dns_name_t *domain, dns_rdataset_t *nameservers,
271 dns_forwarders_t *forwarders,
272 isc_sockaddr_t *client, isc_uint16_t id,
273 unsigned int options, isc_task_t *task,
274 isc_taskaction_t action, void *arg,
275 dns_rdataset_t *rdataset,
276 dns_rdataset_t *sigrdataset,
277 dns_fetch_t **fetchp);
279 dns_resolver_createfetch3(dns_resolver_t *res, dns_name_t *name,
280 dns_rdatatype_t type,
281 dns_name_t *domain, dns_rdataset_t *nameservers,
282 dns_forwarders_t *forwarders,
283 isc_sockaddr_t *client, isc_uint16_t id,
284 unsigned int options, unsigned int depth,
286 isc_taskaction_t action, void *arg,
287 dns_rdataset_t *rdataset,
288 dns_rdataset_t *sigrdataset,
289 dns_fetch_t **fetchp);
291 * Recurse to answer a question.
295 *\li This call starts a query for 'name', type 'type'.
297 *\li The 'domain' is a parent domain of 'name' for which
298 * a set of name servers 'nameservers' is known. If no
299 * such name server information is available, set
300 * 'domain' and 'nameservers' to NULL.
302 *\li 'forwarders' is unimplemented, and subject to change when
303 * we figure out how selective forwarding will work.
305 *\li When the fetch completes (successfully or otherwise), a
306 * #DNS_EVENT_FETCHDONE event with action 'action' and arg 'arg' will be
309 *\li The values of 'rdataset' and 'sigrdataset' will be returned in
310 * the FETCHDONE event.
312 *\li 'client' and 'id' are used for duplicate query detection. '*client'
313 * must remain stable until after 'action' has been called or
314 * dns_resolver_cancelfetch() is called.
318 *\li 'res' is a valid resolver that has been frozen.
320 *\li 'name' is a valid name.
322 *\li 'type' is not a meta type other than ANY.
324 *\li 'domain' is a valid name or NULL.
326 *\li 'nameservers' is a valid NS rdataset (whose owner name is 'domain')
327 * iff. 'domain' is not NULL.
329 *\li 'forwarders' is NULL.
331 *\li 'client' is a valid sockaddr or NULL.
333 *\li 'options' contains valid options.
335 *\li 'rdataset' is a valid, disassociated rdataset.
337 *\li 'sigrdataset' is NULL, or is a valid, disassociated rdataset.
339 *\li fetchp != NULL && *fetchp == NULL.
343 *\li #ISC_R_SUCCESS Success
344 *\li #DNS_R_DUPLICATE
347 *\li Many other values are possible, all of which indicate failure.
351 dns_resolver_cancelfetch(dns_fetch_t *fetch);
357 *\li If 'fetch' has not completed, post its FETCHDONE event with a
358 * result code of #ISC_R_CANCELED.
362 *\li 'fetch' is a valid fetch.
366 dns_resolver_destroyfetch(dns_fetch_t **fetchp);
372 *\li '*fetchp' is a valid fetch.
374 *\li The caller has received the FETCHDONE event (either because the
375 * fetch completed or because dns_resolver_cancelfetch() was called).
379 *\li *fetchp == NULL.
383 dns_resolver_logfetch(dns_fetch_t *fetch, isc_log_t *lctx,
384 isc_logcategory_t *category, isc_logmodule_t *module,
385 int level, isc_boolean_t duplicateok);
387 * Dump a log message on internal state at the completion of given 'fetch'.
388 * 'lctx', 'category', 'module', and 'level' are used to write the log message.
389 * By default, only one log message is written even if the corresponding fetch
390 * context serves multiple clients; if 'duplicateok' is true the suppression
391 * is disabled and the message can be written every time this function is
396 *\li 'fetch' is a valid fetch, and has completed.
400 dns_resolver_dispatchmgr(dns_resolver_t *resolver);
403 dns_resolver_dispatchv4(dns_resolver_t *resolver);
406 dns_resolver_dispatchv6(dns_resolver_t *resolver);
409 dns_resolver_socketmgr(dns_resolver_t *resolver);
412 dns_resolver_taskmgr(dns_resolver_t *resolver);
415 dns_resolver_getlamettl(dns_resolver_t *resolver);
417 * Get the resolver's lame-ttl. zero => no lame processing.
420 *\li 'resolver' to be valid.
424 dns_resolver_setlamettl(dns_resolver_t *resolver, isc_uint32_t lame_ttl);
426 * Set the resolver's lame-ttl. zero => no lame processing.
429 *\li 'resolver' to be valid.
433 dns_resolver_nrunning(dns_resolver_t *resolver);
435 * Return the number of currently running resolutions in this
436 * resolver. This is may be less than the number of outstanding
437 * fetches due to multiple identical fetches, or more than the
438 * number of of outstanding fetches due to the fact that resolution
439 * can continue even though a fetch has been canceled.
443 dns_resolver_addalternate(dns_resolver_t *resolver, isc_sockaddr_t *alt,
444 dns_name_t *name, in_port_t port);
446 * Add alternate addresses to be tried in the event that the nameservers
447 * for a zone are not available in the address families supported by the
451 * \li only one of 'name' or 'alt' to be valid.
455 dns_resolver_setudpsize(dns_resolver_t *resolver, isc_uint16_t udpsize);
457 * Set the EDNS UDP buffer size advertised by the server.
461 dns_resolver_getudpsize(dns_resolver_t *resolver);
463 * Get the current EDNS UDP buffer size.
467 dns_resolver_reset_algorithms(dns_resolver_t *resolver);
469 * Clear the disabled DNSSEC algorithms.
473 dns_resolver_disable_algorithm(dns_resolver_t *resolver, dns_name_t *name,
476 * Mark the give DNSSEC algorithm as disabled and below 'name'.
477 * Valid algorithms are less than 256.
486 dns_resolver_algorithm_supported(dns_resolver_t *resolver, dns_name_t *name,
489 * Check if the given algorithm is supported by this resolver.
490 * This checks if the algorithm has been disabled via
491 * dns_resolver_disable_algorithm() then the underlying
492 * crypto libraries if not specifically disabled.
496 dns_resolver_digest_supported(dns_resolver_t *resolver, unsigned int digest_type);
498 * Is this digest type supported.
502 dns_resolver_resetmustbesecure(dns_resolver_t *resolver);
505 dns_resolver_setmustbesecure(dns_resolver_t *resolver, dns_name_t *name,
506 isc_boolean_t value);
509 dns_resolver_getmustbesecure(dns_resolver_t *resolver, dns_name_t *name);
513 dns_resolver_settimeout(dns_resolver_t *resolver, unsigned int seconds);
515 * Set the length of time the resolver will work on a query, in seconds.
517 * If timeout is 0, the default timeout will be applied.
520 * \li resolver to be valid.
524 dns_resolver_gettimeout(dns_resolver_t *resolver);
526 * Get the current length of time the resolver will work on a query, in seconds.
529 * \li resolver to be valid.
533 dns_resolver_setclientsperquery(dns_resolver_t *resolver,
534 isc_uint32_t min, isc_uint32_t max);
537 dns_resolver_getclientsperquery(dns_resolver_t *resolver, isc_uint32_t *cur,
538 isc_uint32_t *min, isc_uint32_t *max);
541 dns_resolver_getzeronosoattl(dns_resolver_t *resolver);
544 dns_resolver_setzeronosoattl(dns_resolver_t *resolver, isc_boolean_t state);
547 dns_resolver_getoptions(dns_resolver_t *resolver);
550 dns_resolver_addbadcache(dns_resolver_t *resolver, dns_name_t *name,
551 dns_rdatatype_t type, isc_time_t *expire);
553 * Add a entry to the bad cache for <name,type> that will expire at 'expire'.
556 * \li resolver to be valid.
557 * \li name to be valid.
561 dns_resolver_getbadcache(dns_resolver_t *resolver, dns_name_t *name,
562 dns_rdatatype_t type, isc_time_t *now);
564 * Check to see if there is a unexpired entry in the bad cache for
568 * \li resolver to be valid.
569 * \li name to be valid.
573 dns_resolver_flushbadcache(dns_resolver_t *resolver, dns_name_t *name);
575 * Flush the bad cache of all entries at 'name' if 'name' is non NULL.
576 * Flush the entire bad cache if 'name' is NULL.
579 * \li resolver to be valid.
583 dns_resolver_printbadcache(dns_resolver_t *resolver, FILE *fp);
585 * Print out the contents of the bad cache to 'fp'.
588 * \li resolver to be valid.
592 dns_resolver_setmaxdepth(dns_resolver_t *resolver, unsigned int maxdepth);
594 dns_resolver_getmaxdepth(dns_resolver_t *resolver);
596 * Get and set how many NS indirections will be followed when looking for
597 * nameserver addresses.
600 * \li resolver to be valid.
605 #endif /* DNS_RESOLVER_H */