2 * Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2003 Internet Software Consortium.
5 * Permission to use, copy, modify, and 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: adb.h,v 1.66.2.6 2004/03/09 06:11:13 marka Exp $ */
28 * DNS Address Database
30 * This module implements an address database (ADB) for mapping a name
31 * to an isc_sockaddr_t. It also provides statistical information on
32 * how good that address might be.
34 * A client will pass in a dns_name_t, and the ADB will walk through
35 * the rdataset looking up addresses associated with the name. If it
36 * is found on the internal lists, a structure is filled in with the
37 * address information and stats for found addresses.
39 * If the name cannot be found on the internal lists, a new entry will
40 * be created for a name if all the information needed can be found
41 * in the zone table or cache. This new address will then be returned.
43 * If a request must be made to remote servers to satisfy a name lookup,
44 * this module will start fetches to try to complete these addresses. When
45 * at least one more completes, an event is sent to the caller. If none of
46 * them resolve before the fetch times out, an event indicating this is
49 * Records are stored internally until a timer expires. The timer is the
50 * smaller of the TTL or signature validity period. For A6 records, the timer
51 * is the smallest of all the TTL or signature validity periods in the A6
54 * Lameness is stored per-zone, and this data hangs off each address field.
55 * When an address is marked lame for a given zone the address will not
56 * be returned to a caller.
61 * The ADB takes care of all necessary locking.
63 * Only the task which initiated the name lookup can cancel the lookup.
68 * None, since all data stored is required to be pre-filtered.
69 * (Cache needs to be sane, fetches return bounds-checked and sanity-
70 * checked data, caller passes a good dns_name_t for the zone, etc)
78 #include <isc/magic.h>
80 #include <isc/sockaddr.h>
82 #include <dns/types.h>
88 *** Magic number checks
91 #define DNS_ADBFIND_MAGIC ISC_MAGIC('a','d','b','H')
92 #define DNS_ADBFIND_VALID(x) ISC_MAGIC_VALID(x, DNS_ADBFIND_MAGIC)
93 #define DNS_ADBADDRINFO_MAGIC ISC_MAGIC('a','d','A','I')
94 #define DNS_ADBADDRINFO_VALID(x) ISC_MAGIC_VALID(x, DNS_ADBADDRINFO_MAGIC)
101 typedef struct dns_adbname dns_adbname_t;
105 * Represents a lookup for a single name.
107 * On return, the client can safely use "list", and can reorder the list.
108 * Items may not be _deleted_ from this list, however, or added to it
109 * other than by using the dns_adb_*() API.
113 unsigned int magic; /* RO: magic */
114 dns_adbaddrinfolist_t list; /* RO: list of addrs */
115 unsigned int query_pending; /* RO: partial list */
116 unsigned int partial_result; /* RO: addrs missing */
117 unsigned int options; /* RO: options */
118 isc_result_t result_v4; /* RO: v4 result */
119 isc_result_t result_v6; /* RO: v6 result */
120 ISC_LINK(dns_adbfind_t) publink; /* RW: client use */
123 isc_mutex_t lock; /* locks all below */
127 dns_adbname_t *adbname;
130 ISC_LINK(dns_adbfind_t) plink;
136 * return addresses of that type.
139 * Only schedule an event if no addresses are known.
140 * Must set _WANTEVENT for this to be meaningful.
143 * An event is desired. Check this bit in the returned find to see
144 * if one will actually be generated.
147 * If set, fetches will not be generated unless no addresses are
148 * available in any of the address families requested.
151 * Fetches will start using the closest zone data or use the root servers.
152 * This is useful for reestablishing glue that has expired.
156 * Glue or hints are ok. These are used when matching names already
157 * in the adb, and when dns databases are searched.
160 * Return lame servers in a find, so that all addresses are returned.
163 * At least one address was omitted from the list because it was lame.
164 * This bit will NEVER be set if _RETURNLAME is set in the createfind().
166 #define DNS_ADBFIND_INET 0x00000001
167 #define DNS_ADBFIND_INET6 0x00000002
168 #define DNS_ADBFIND_ADDRESSMASK 0x00000003
170 #define DNS_ADBFIND_EMPTYEVENT 0x00000004
171 #define DNS_ADBFIND_WANTEVENT 0x00000008
172 #define DNS_ADBFIND_AVOIDFETCHES 0x00000010
173 #define DNS_ADBFIND_STARTATZONE 0x00000020
174 #define DNS_ADBFIND_GLUEOK 0x00000040
175 #define DNS_ADBFIND_HINTOK 0x00000080
176 #define DNS_ADBFIND_RETURNLAME 0x00000100
177 #define DNS_ADBFIND_LAMEPRUNED 0x00000200
181 * The answers to queries come back as a list of these.
183 struct dns_adbaddrinfo {
184 unsigned int magic; /* private */
186 isc_sockaddr_t sockaddr; /* [rw] */
187 unsigned int srtt; /* [rw] microseconds */
188 unsigned int flags; /* [rw] */
189 dns_adbentry_t *entry; /* private */
190 ISC_LINK(dns_adbaddrinfo_t) publink;
194 * The event sent to the caller task is just a plain old isc_event_t. It
195 * contains no data other than a simple status, passed in the "type" field
196 * to indicate that another address resolved, or all partially resolved
197 * addresses have failed to resolve.
199 * "sender" is the dns_adbfind_t used to issue this query.
201 * This is simply a standard event, with the "type" set to:
203 * DNS_EVENT_ADBMOREADDRESSES -- another address resolved.
204 * DNS_EVENT_ADBNOMOREADDRESSES -- all pending addresses failed,
205 * were canceled, or otherwise will
207 * DNS_EVENT_ADBCANCELED -- The request was canceled by a
209 * DNS_EVENT_ADBNAMEDELETED -- The name was deleted, so this request
212 * In each of these cases, the addresses returned by the initial call
213 * to dns_adb_createfind() can still be used until they are no longer needed.
222 dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *tmgr,
223 isc_taskmgr_t *taskmgr, dns_adb_t **newadb);
229 * Generally, applications should not create an ADB directly, but
230 * should instead call dns_view_createresolver().
234 * 'mem' must be a valid memory context.
236 * 'view' be a pointer to a valid view.
238 * 'tmgr' be a pointer to a valid timer manager.
240 * 'taskmgr' be a pointer to a valid task manager.
242 * 'newadb' != NULL && '*newadb' == NULL.
246 * ISC_R_SUCCESS after happiness.
247 * ISC_R_NOMEMORY after resource allocation failure.
251 dns_adb_attach(dns_adb_t *adb, dns_adb_t **adbp);
253 * Attach to an 'adb' to 'adbp'.
256 * 'adb' to be a valid dns_adb_t, created via dns_adb_create().
257 * 'adbp' to be a valid pointer to a *dns_adb_t which is initialized
262 dns_adb_detach(dns_adb_t **adb);
264 * Delete the ADB. Sets *ADB to NULL. Cancels any outstanding requests.
268 * 'adb' be non-NULL and '*adb' be a valid dns_adb_t, created via
273 dns_adb_whenshutdown(dns_adb_t *adb, isc_task_t *task, isc_event_t **eventp);
275 * Send '*eventp' to 'task' when 'adb' has shutdown.
279 * '*adb' is a valid dns_adb_t.
281 * eventp != NULL && *eventp is a valid event.
287 * The event's sender field is set to the value of adb when the event
292 dns_adb_shutdown(dns_adb_t *adb);
298 * '*adb' is a valid dns_adb_t.
302 dns_adb_createfind(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action,
303 void *arg, dns_name_t *name, dns_name_t *zone,
304 unsigned int options, isc_stdtime_t now, dns_name_t *target,
305 in_port_t port, dns_adbfind_t **find);
307 * Main interface for clients. The adb will look up the name given in
308 * "name" and will build up a list of found addresses, and perhaps start
309 * internal fetches to resolve names that are unknown currently.
311 * If other addresses resolve after this call completes, an event will
312 * be sent to the <task, taskaction, arg> with the sender of that event
313 * set to a pointer to the dns_adbfind_t returned by this function.
315 * If no events will be generated, the *find->result_v4 and/or result_v6
316 * members may be examined for address lookup status. The usual ISC_R_SUCCESS,
317 * ISC_R_FAILURE, and DNS_R_NX{DOMAIN,RRSET} are returned, along with
318 * ISC_R_NOTFOUND meaning the ADB has not _yet_ found the values. In this
319 * latter case, retrying may produce more addresses.
321 * If events will be returned, the result_v[46] members are only valid
322 * when that event is actually returned.
324 * The list of addresses returned is unordered. The caller must impose
325 * any ordering required. The list will not contain "known bad" addresses,
326 * however. For instance, it will not return hosts that are known to be
327 * lame for the zone in question.
329 * The caller cannot (directly) modify the contents of the address list's
330 * fields other than the "link" field. All values can be read at any
333 * The "now" parameter is used only for determining which entries that
334 * have a specific time to live or expire time should be removed from
335 * the running database. If specified as zero, the current time will
336 * be retrieved and used.
338 * If 'target' is not NULL and 'name' is an alias (i.e. the name is
339 * CNAME'd or DNAME'd to another name), then 'target' will be updated with
340 * the domain name that 'name' is aliased to.
342 * All addresses returned will have the sockaddr's port set to 'port.'
343 * The caller may change them directly in the dns_adbaddrinfo_t since
344 * they are copies of the internal address only.
346 * XXXMLG Document options, especially the flags which control how
351 * *adb be a valid isc_adb_t object.
353 * If events are to be sent, *task be a valid task,
354 * and isc_taskaction_t != NULL.
356 * *name is a valid dns_name_t.
358 * zone != NULL and *zone be a valid dns_name_t.
360 * target == NULL or target is a valid name with a buffer.
362 * find != NULL && *find == NULL.
366 * ISC_R_SUCCESS Addresses might have been returned, and events will be
367 * delivered for unresolved addresses.
368 * ISC_R_NOMORE Addresses might have been returned, but no events
369 * will ever be posted for this context. This is only
370 * returned if task != NULL.
371 * ISC_R_NOMEMORY insufficient resources
372 * DNS_R_ALIAS 'name' is an alias for another name.
374 * Calls, and returns error codes from:
380 * No internal reference to "name" exists after this function
385 dns_adb_cancelfind(dns_adbfind_t *find);
387 * Cancels the find, and sends the event off to the caller.
389 * It is an error to call dns_adb_cancelfind() on a find where
390 * no event is wanted, or will ever be sent.
394 * It is possible that the real completion event was posted just
395 * before the dns_adb_cancelfind() call was made. In this case,
396 * dns_adb_cancelfind() will do nothing. The event callback needs
397 * to be prepared to find this situation (i.e. result is valid but
398 * the caller expects it to be canceled).
402 * 'find' be a valid dns_adbfind_t pointer.
404 * events would have been posted to the task. This can be checked
405 * with (find->options & DNS_ADBFIND_WANTEVENT).
409 * The event was posted to the task.
413 dns_adb_destroyfind(dns_adbfind_t **find);
415 * Destroys the find reference.
419 * This can only be called after the event was delivered for a
420 * find. Additionally, the event MUST have been freed via
421 * isc_event_free() BEFORE this function is called.
425 * 'find' != NULL and *find be valid dns_adbfind_t pointer.
429 * No "address found" events will be posted to the originating task
430 * after this function returns.
434 dns_adb_dump(dns_adb_t *adb, FILE *f);
436 * This function is only used for debugging. It will dump as much of the
437 * state of the running system as possible.
443 * f != NULL, and is a file open for writing.
447 dns_adb_dumpfind(dns_adbfind_t *find, FILE *f);
449 * This function is only used for debugging. Dump the data associated
456 * f != NULL, and is a file open for writing.
460 dns_adb_marklame(dns_adb_t *adb, dns_adbaddrinfo_t *addr, dns_name_t *zone,
461 isc_stdtime_t expire_time);
463 * Mark the given address as lame for the zone "zone". expire_time should
464 * be set to the time when the entry should expire. That is, if it is to
465 * expire 10 minutes in the future, it should set it to (now + 10 * 60).
473 * zone be the zone used in the dns_adb_createfind() call.
477 * ISC_R_SUCCESS -- all is well.
478 * ISC_R_NOMEMORY -- could not mark address as lame.
482 * A reasonable default for RTT adjustments
484 #define DNS_ADB_RTTADJDEFAULT 7 /* default scale */
485 #define DNS_ADB_RTTADJREPLACE 0 /* replace with our rtt */
486 #define DNS_ADB_RTTADJAGE 10 /* age this rtt */
489 dns_adb_adjustsrtt(dns_adb_t *adb, dns_adbaddrinfo_t *addr,
490 unsigned int rtt, unsigned int factor);
492 * Mix the round trip time into the existing smoothed rtt. The formula used
493 * (where srtt is the existing rtt value, and rtt and factor are arguments to
496 * new_srtt = (old_srtt / 10 * factor) + (rtt / 10 * (10 - factor));
498 * XXXRTH Do we want to publish the formula? What if we want to change how
499 * this works later on? Recommend/require that the units are
512 * The srtt in addr will be updated to reflect the new global
513 * srtt value. This may include changes made by others.
517 dns_adb_changeflags(dns_adb_t *adb, dns_adbaddrinfo_t *addr,
518 unsigned int bits, unsigned int mask);
520 * Set the flags as given by:
522 * newflags = (oldflags & ~mask) | (bits & mask);
532 dns_adb_findaddrinfo(dns_adb_t *adb, isc_sockaddr_t *sa,
533 dns_adbaddrinfo_t **addrp, isc_stdtime_t now);
535 * Return a dns_adbaddrinfo_t that is associated with address 'sa'.
543 * addrp != NULL && *addrp == NULL
552 dns_adb_freeaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **addrp);
554 * Free a dns_adbaddrinfo_t allocated by dns_adb_findaddrinfo().
560 * *addrp is a valid dns_adbaddrinfo_t *.
564 dns_adb_flush(dns_adb_t *adb);
566 * Flushes all cached data from the adb.
574 #endif /* DNS_ADB_H */