badcache.h

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/*
 * Copyright (C) 2014  Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef DNS_BADCACHE_H
#define DNS_BADCACHE_H 1

/*****
 ***** Module Info
 *****/

/*! \file dns/badcache.h
 * \brief
 * Defines dns_badcache_t, the "bad cache" object.
 *
 * Notes:
 *\li   A bad cache object is a hash table of name/type tuples,
 *      indicating whether a given tuple known to be "bad" in some
 *      sense (e.g., queries for that name and type have been
 *      returning SERVFAIL). This is used for both the "bad server
 *      cache" in the resolver and for the "servfail cache" in
 *      the view.
 *
 * Reliability:
 *
 * Resources:
 *
 * Security:
 *
 * Standards:
 */

/***
 ***    Imports
 ***/

#include <dns/types.h>

ISC_LANG_BEGINDECLS

/***
 ***    Functions
 ***/

isc_result_t
dns_badcache_init(isc_mem_t *mctx, unsigned int size, dns_badcache_t **bcp);
/*%
 * Allocate and initialize a badcache and store it in '*bcp'.
 *
 * Requires:
 * \li  mctx != NULL
 * \li  bcp != NULL
 * \li  *bcp == NULL
 */

void
dns_badcache_destroy(dns_badcache_t **bcp);
/*%
 * Flush and then free badcache in 'bcp'. '*bcp' is set to NULL on return.
 *
 * Requires:
 * \li  '*bcp' to be a valid badcache
 */

void
dns_badcache_add(dns_badcache_t *bc, dns_name_t *name,
                 dns_rdatatype_t type, isc_boolean_t update,
                 isc_uint32_t flags, isc_time_t *expire);
/*%
 * Adds a badcache entry to the badcache 'bc' for name 'name' and
 * type 'type'.  If an entry already exists, then it will be updated if
 * 'update' is ISC_TRUE.  The entry will be stored with flags 'flags'
 * and expiration date 'expire'.
 *
 * Requires:
 * \li  bc to be a valid badcache.
 * \li  name != NULL
 * \li  expire != NULL
 */

isc_boolean_t
dns_badcache_find(dns_badcache_t *bc, dns_name_t *name,
                  dns_rdatatype_t type, isc_uint32_t *flagp,
                  isc_time_t *now);
/*%
 * Returns ISC_TRUE if a record is found in the badcache 'bc' matching
 * 'name' and 'type', with an expiration date later than 'now'.
 * If 'flagp' is not NULL, then '*flagp' is updated to the flags
 * that were stored in the badcache entry.  Returns ISC_FALSE if
 * no matching record is found.
 *
 * Requires:
 * \li  bc to be a valid badcache.
 * \li  name != NULL
 * \li  now != NULL
 */

void
dns_badcache_flush(dns_badcache_t *bc);
/*%
 * Flush the entire bad cache.
 *
 * Requires:
 * \li  bc to be a valid badcache
 */

void
dns_badcache_flushname(dns_badcache_t *bc, dns_name_t *name);
/*%
 * Flush the bad cache of all entries at 'name'.
 *
 * Requires:
 * \li  bc to be a valid badcache
 * \li  name != NULL
 */

void
dns_badcache_flushtree(dns_badcache_t *bc, dns_name_t *name);
/*%
 * Flush the bad cache of all entries at or below 'name'.
 *
 * Requires:
 * \li  bc to be a valid badcache
 * \li  name != NULL
 */

void
dns_badcache_print(dns_badcache_t *bc, const char *cachename, FILE *fp);
/*%
 * Print the contents of badcache 'bc' (headed by the title 'cachename')
 * to file pointer 'fp'.
 *
 * Requires:
 * \li  bc to be a valid badcache
 * \li  cachename != NULL
 * \li  fp != NULL
 */

ISC_LANG_ENDDECLS

#endif /* DNS_BADCACHE_H */

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