resolv_cache.h revision 1dc9e472e19acfe6dc7f41e429236e7eef7ceda1 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28#ifndef _RESOLV_CACHE_H_
29#define _RESOLV_CACHE_H_
30
31struct resolv_cache;  /* forward */
32
33/* get cache instance, can be NULL if cache is disabled
34 * (e.g. through an environment variable) */
35extern struct resolv_cache*  __get_res_cache(void);
36
37/* this gets called everytime we detect some changes in the DNS configuration
38 * and will flush the cache */
39extern void   _resolv_cache_reset( unsigned  generation );
40
41typedef enum {
42    RESOLV_CACHE_UNSUPPORTED,  /* the cache can't handle that kind of queries */
43                               /* or the answer buffer is too small */
44    RESOLV_CACHE_NOTFOUND,     /* the cache doesn't know about this query */
45    RESOLV_CACHE_FOUND         /* the cache found the answer */
46} ResolvCacheStatus;
47
48extern ResolvCacheStatus
49_resolv_cache_lookup( struct resolv_cache*  cache,
50                      const void*           query,
51                      int                   querylen,
52                      void*                 answer,
53                      int                   answersize,
54                      int                  *answerlen );
55
56/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
57 * did return RESOLV_CACHE_NOTFOUND
58 */
59extern void
60_resolv_cache_add( struct resolv_cache*  cache,
61                   const void*           query,
62                   int                   querylen,
63                   const void*           answer,
64                   int                   answerlen );
65
66#endif /* _RESOLV_CACHE_H_ */
67