platform_bionic/libc/dns/include/resolv_cache.h
Paul Jensen 41d9a50371 Add support for deleting per-network DNS resolver caches.
This is required when the possible range of NetIds is large to
prevent netd consuming excessive amounts of memory.
This required replacing the per-cache locks in favor of a single
global lock to prevent accesses to deleted caches.

Change-Id: I99d058bafea5de743e56075dbed74031da4df63f
2014-05-14 04:16:18 -07:00

76 lines
3 KiB
C

/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _RESOLV_CACHE_H_
#define _RESOLV_CACHE_H_
#include <stddef.h>
#include <sys/cdefs.h>
struct __res_state;
/* sets the name server addresses to the provided res_state structure. The
* name servers are retrieved from the cache which is associated
* with the network to which the res_state structure is associated */
__LIBC_HIDDEN__
extern void _resolv_populate_res_for_net(struct __res_state* statp);
typedef enum {
RESOLV_CACHE_UNSUPPORTED, /* the cache can't handle that kind of queries */
/* or the answer buffer is too small */
RESOLV_CACHE_NOTFOUND, /* the cache doesn't know about this query */
RESOLV_CACHE_FOUND /* the cache found the answer */
} ResolvCacheStatus;
__LIBC_HIDDEN__
extern ResolvCacheStatus
_resolv_cache_lookup( unsigned netid,
const void* query,
int querylen,
void* answer,
int answersize,
int *answerlen );
/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
* did return RESOLV_CACHE_NOTFOUND
*/
__LIBC_HIDDEN__
extern void
_resolv_cache_add( unsigned netid,
const void* query,
int querylen,
const void* answer,
int answerlen );
/* Notify the cache a request failed */
__LIBC_HIDDEN__
extern void
_resolv_cache_query_failed( unsigned netid,
const void* query,
int querylen);
#endif /* _RESOLV_CACHE_H_ */