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
31#include <stddef.h>
32#include <sys/cdefs.h>
33
34struct __res_state;
35struct resolv_cache;  /* forward */
36
37/* gets the cache for an interface. Set ifname argument to NULL or
38 * empty buffer ('\0') to get cache for default interface.
39 * returned cache might be NULL*/
40__LIBC_HIDDEN__
41extern struct resolv_cache*  __get_res_cache(const char* ifname);
42
43/* this gets called everytime we detect some changes in the DNS configuration
44 * and will flush the cache */
45__LIBC_HIDDEN__
46extern void  _resolv_cache_reset( unsigned  generation );
47
48/* Gets the address of the n:th name server for the default interface
49 * Return length of address on success else 0.
50 * Note: The first name server is at n = 1 */
51__LIBC_HIDDEN__
52extern int _resolv_cache_get_nameserver(int n, char* addr, int addrLen);
53
54/* Gets the address of the n:th name server for a certain interface
55 * Return length of address on success else 0.
56 * Note: The first name server is at n = 1 */
57__LIBC_HIDDEN__
58extern int _resolv_cache_get_nameserver_for_iface(const char* ifname, int n,
59        char* addr, int addrLen);
60
61/* Gets addrinfo of the n:th name server associated with an interface.
62 * NULL is returned if no address if found.
63 * Note: The first name server is at n = 1. */
64__LIBC_HIDDEN__
65extern struct addrinfo* _resolv_cache_get_nameserver_addr_for_iface(const char* ifname, int n);
66
67/* Gets addrinfo of the n:th name server associated with the default interface
68 * NULL is returned if no address if found.
69 * Note: The first name server is at n = 1. */
70__LIBC_HIDDEN__
71extern struct addrinfo* _resolv_cache_get_nameserver_addr(int n);
72
73/* gets the address associated with the default interface */
74__LIBC_HIDDEN__
75extern struct in_addr* _resolv_get_addr_of_default_iface();
76
77/* gets the address associated with the specified interface */
78__LIBC_HIDDEN__
79extern struct in_addr* _resolv_get_addr_of_iface(const char* ifname);
80
81/* Copy the name of the default interface to the provided buffer.
82 * Returns the string length of the default interface,
83 * be that less or more than the buffLen, or 0 if nothing had been written */
84__LIBC_HIDDEN__
85 extern size_t _resolv_get_default_iface(char* buff, size_t buffLen);
86
87/* sets the name server addresses to the provided res_state structure. The
88 * name servers are retrieved from the cache which is associated
89 * with the interface to which the res_state structure is associated */
90__LIBC_HIDDEN__
91extern void _resolv_populate_res_for_iface(struct __res_state* statp);
92
93typedef enum {
94    RESOLV_CACHE_UNSUPPORTED,  /* the cache can't handle that kind of queries */
95                               /* or the answer buffer is too small */
96    RESOLV_CACHE_NOTFOUND,     /* the cache doesn't know about this query */
97    RESOLV_CACHE_FOUND         /* the cache found the answer */
98} ResolvCacheStatus;
99
100__LIBC_HIDDEN__
101extern ResolvCacheStatus
102_resolv_cache_lookup( struct resolv_cache*  cache,
103                      const void*           query,
104                      int                   querylen,
105                      void*                 answer,
106                      int                   answersize,
107                      int                  *answerlen );
108
109/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
110 * did return RESOLV_CACHE_NOTFOUND
111 */
112__LIBC_HIDDEN__
113extern void
114_resolv_cache_add( struct resolv_cache*  cache,
115                   const void*           query,
116                   int                   querylen,
117                   const void*           answer,
118                   int                   answerlen );
119
120/* Notify the cache a request failed */
121__LIBC_HIDDEN__
122extern void
123_resolv_cache_query_failed( struct resolv_cache* cache,
124                   const void* query,
125                   int         querylen);
126
127#endif /* _RESOLV_CACHE_H_ */
128