/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#ifndef DNS_CACHE_H
#define DNS_CACHE_H 1
/*****
***** Module Info
*****/
/*! \file dns/cache.h
* \brief
* Defines dns_cache_t, the cache object.
*
* Notes:
*\li A cache object contains DNS data of a single class.
* Multiple classes will be handled by creating multiple
* views, each with a different class and its own cache.
*
* MP:
*\li See notes at the individual functions.
*
* Reliability:
*
* Resources:
*
* Security:
*
* Standards:
*/
/***
*** Imports
***/
#include <stdbool.h>
#include <isc/lang.h>
#include <isc/stats.h>
#include <isc/stdtime.h>
#include <dns/types.h>
ISC_LANG_BEGINDECLS
/***
*** Functions
***/
isc_result_t
dns_cache_create(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr,
isc_timermgr_t *timermgr, dns_rdataclass_t rdclass,
const char *cachename, const char *db_type,
unsigned int db_argc, char **db_argv, dns_cache_t **cachep);
/*%<
* Create a new DNS cache.
*
* dns_cache_create2() will create a named cache.
*
* dns_cache_create3() will create a named cache using two separate memory
* contexts, one for cache data which can be cleaned and a separate one for
* memory allocated for the heap (which can grow without an upper limit and
* has no mechanism for shrinking).
*
* dns_cache_create() is a backward compatible version that internally
* specifies an empty cache name and a single memory context.
*
* Requires:
*
*\li 'cmctx' (and 'hmctx' if applicable) is a valid memory context.
*
*\li 'taskmgr' is a valid task manager and 'timermgr' is a valid timer
* manager, or both are NULL. If NULL, no periodic cleaning of the
* cache will take place.
*
*\li 'cachename' is a valid string. This must not be NULL.
*
*\li 'cachep' is a valid pointer, and *cachep == NULL
*
* Ensures:
*
*\li '*cachep' is attached to the newly created cache
*
* Returns:
*
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*/
void
dns_cache_attach(dns_cache_t *cache, dns_cache_t **targetp);
/*%<
* Attach *targetp to cache.
*
* Requires:
*
*\li 'cache' is a valid cache.
*
*\li 'targetp' points to a NULL dns_cache_t *.
*
* Ensures:
*
*\li *targetp is attached to cache.
*/
void
dns_cache_detach(dns_cache_t **cachep);
/*%<
* Detach *cachep from its cache.
*
* Requires:
*
*\li 'cachep' points to a valid cache.
*
* Ensures:
*
*\li *cachep is NULL.
*
*\li If '*cachep' is the last reference to the cache,
* all resources used by the cache will be freed
*/
void
dns_cache_attachdb(dns_cache_t *cache, dns_db_t **dbp);
/*%<
* Attach *dbp to the cache's database.
*
* Notes:
*
*\li This may be used to get a reference to the database for
* the purpose of cache lookups (XXX currently it is also
* the way to add data to the cache, but having a
* separate dns_cache_add() interface instead would allow
* more control over memory usage).
* The caller should call dns_db_detach() on the reference
* when it is no longer needed.
*
* Requires:
*
*\li 'cache' is a valid cache.
*
*\li 'dbp' points to a NULL dns_db *.
*
* Ensures:
*
*\li *dbp is attached to the database.
*/
isc_result_t
dns_cache_setfilename(dns_cache_t *cache, const char *filename);
/*%<
* If 'filename' is non-NULL, make the cache persistent.
* The cache's data will be stored in the given file.
* If 'filename' is NULL, make the cache non-persistent.
* Files that are no longer used are not unlinked automatically.
*
* Returns:
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*\li Various file-related failures
*/
isc_result_t
dns_cache_load(dns_cache_t *cache);
/*%<
* If the cache has a file name, load the cache contents from the file.
* Previous cache contents are not discarded.
* If no file name has been set, do nothing and return success.
*
* MT:
*\li Multiple simultaneous attempts to load or dump the cache
* will be serialized with respect to one another, but
* the cache may be read and updated while the dump is
* in progress. Updates performed during loading
* may or may not be preserved, and reads may return
* either the old or the newly loaded data.
*
* Returns:
*
*\li #ISC_R_SUCCESS
* \li Various failures depending on the database implementation type
*/
isc_result_t
dns_cache_dump(dns_cache_t *cache);
/*%<
* If the cache has a file name, write the cache contents to disk,
* overwriting any preexisting file. If no file name has been set,
* do nothing and return success.
*
* MT:
*\li Multiple simultaneous attempts to load or dump the cache
* will be serialized with respect to one another, but
* the cache may be read and updated while the dump is
* in progress. Updates performed during the dump may
* or may not be reflected in the dumped file.
*
* Returns:
*
*\li #ISC_R_SUCCESS
* \li Various failures depending on the database implementation type
*/
isc_result_t
dns_cache_clean(dns_cache_t *cache, isc_stdtime_t now);
/*%<
* Force immediate cleaning of the cache, freeing all rdatasets
* whose TTL has expired as of 'now' and that have no pending
* references.
*/
const char *
dns_cache_getname(dns_cache_t *cache);
/*%<
* Get the cache name.
*/
void
dns_cache_setcachesize(dns_cache_t *cache, size_t size);
/*%<
* Set the maximum cache size. 0 means unlimited.
*/
size_t
dns_cache_getcachesize(dns_cache_t *cache);
/*%<
* Get the maximum cache size.
*/
void
dns_cache_setservestalettl(dns_cache_t *cache, dns_ttl_t ttl);
/*%<
* Sets the maximum length of time that cached answers may be retained
* past their normal TTL. Default value for the library is 0, disabling
* the use of stale data.
*
* Requires:
*\li 'cache' to be valid.
*/
dns_ttl_t
dns_cache_getservestalettl(dns_cache_t *cache);
/*%<
* Gets the maximum length of time that cached answers may be kept past
* normal expiry.
*
* Requires:
*\li 'cache' to be valid.
*/
void
dns_cache_setservestalerefresh(dns_cache_t *cache, dns_ttl_t interval);
/*%<
* Sets the length of time to wait before attempting to refresh a rrset
* if a previous attempt in doing so has failed.
* During this time window if stale rrset are available in cache they
* will be directly returned to client.
*
* Requires:
*\li 'cache' to be valid.
*/
dns_ttl_t
dns_cache_getservestalerefresh(dns_cache_t *cache);
/*%<
* Gets the 'stale-refresh-time' value, set by a previous call to
* 'dns_cache_setservestalerefresh'.
*
* Requires:
*\li 'cache' to be valid.
*/
isc_result_t
dns_cache_flush(dns_cache_t *cache);
/*%<
* Flushes all data from the cache.
*
* Returns:
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*/
isc_result_t
dns_cache_flushnode(dns_cache_t *cache, const dns_name_t *name, bool tree);
/*
* Flush a given name from the cache. If 'tree' is true, then
* also flush all names under 'name'.
*
* Requires:
*\li 'cache' to be valid.
*\li 'name' to be valid.
*
* Returns:
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*\li other error returns.
*/
isc_result_t
dns_cache_flushname(dns_cache_t *cache, const dns_name_t *name);
/*
* Flush a given name from the cache. Equivalent to
* dns_cache_flushpartial(cache, name, false).
*
* Requires:
*\li 'cache' to be valid.
*\li 'name' to be valid.
*
* Returns:
*\li #ISC_R_SUCCESS
*\li #ISC_R_NOMEMORY
*\li other error returns.
*/
isc_stats_t *
dns_cache_getstats(dns_cache_t *cache);
/*
* Return a pointer to the stats collection object for 'cache'
*/
void
dns_cache_dumpstats(dns_cache_t *cache, FILE *fp);
/*
* Dump cache statistics and status in text to 'fp'
*/
void
dns_cache_updatestats(dns_cache_t *cache, isc_result_t result);
/*
* Update cache statistics based on result code in 'result'
*/
void
dns_cache_setmaxrrperset(dns_cache_t *cache, uint32_t value);
/*%<
* Set the maximum resource records per RRSet that can be cached.
*/
void
dns_cache_setmaxtypepername(dns_cache_t *cache, uint32_t value);
/*%<
* Set the maximum resource record types per owner name that can be cached.
*/
#ifdef HAVE_LIBXML2
int
dns_cache_renderxml(dns_cache_t *cache, void *writer0);
/*
* Render cache statistics and status in XML for 'writer'.
*/
#endif /* HAVE_LIBXML2 */
#ifdef HAVE_JSON_C
isc_result_t
dns_cache_renderjson(dns_cache_t *cache, void *cstats0);
/*
* Render cache statistics and status in JSON
*/
#endif /* HAVE_JSON_C */
ISC_LANG_ENDDECLS
#endif /* DNS_CACHE_H */
