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 <sys/cdefs.h>
32
33struct __res_state;
34struct resolv_cache;  /* forward */
35
36/* gets the cache for an interface. Set ifname argument to NULL or
37 * empty buffer ('\0') to get cache for default interface.
38 * returned cache might be NULL*/
39__LIBC_HIDDEN__
40extern struct resolv_cache*  __get_res_cache(const char* ifname);
41
42/* this gets called everytime we detect some changes in the DNS configuration
43 * and will flush the cache */
44__LIBC_HIDDEN__
45extern void  _resolv_cache_reset( unsigned  generation );
46
47/* Gets the address of the n:th name server for the default interface
48 * Return length of address on success else 0.
49 * Note: The first name server is at n = 1 */
50__LIBC_HIDDEN__
51extern int _resolv_cache_get_nameserver(int n, char* addr, int addrLen);
52
53/* Gets the address of the n:th name server for a certain interface
54 * Return length of address on success else 0.
55 * Note: The first name server is at n = 1 */
56__LIBC_HIDDEN__
57extern int _resolv_cache_get_nameserver_for_iface(const char* ifname, int n,
58        char* addr, int addrLen);
59
60/* Gets addrinfo of the n:th name server associated with an interface.
61 * NULL is returned if no address if found.
62 * Note: The first name server is at n = 1. */
63__LIBC_HIDDEN__
64extern struct addrinfo* _resolv_cache_get_nameserver_addr_for_iface(const char* ifname, int n);
65
66/* Gets addrinfo of the n:th name server associated with the default interface
67 * NULL is returned if no address if found.
68 * Note: The first name server is at n = 1. */
69__LIBC_HIDDEN__
70extern struct addrinfo* _resolv_cache_get_nameserver_addr(int n);
71
72/* gets the address associated with the default interface */
73__LIBC_HIDDEN__
74extern struct in_addr* _resolv_get_addr_of_default_iface();
75
76/* gets the address associated with the specified interface */
77__LIBC_HIDDEN__
78extern struct in_addr* _resolv_get_addr_of_iface(const char* ifname);
79
80/* Copy the name of the default interface to provided buffer.
81 * Return length of buffer on success on failure -1 is returned */
82__LIBC_HIDDEN__
83extern int _resolv_get_default_iface(char* buff, int buffLen);
84
85/* sets the name server addresses to the provided res_state structure. The
86 * name servers are retrieved from the cache which is associated
87 * with the interface to which the res_state structure is associated */
88__LIBC_HIDDEN__
89extern int _resolv_populate_res_for_iface(struct __res_state* statp);
90
91typedef enum {
92    RESOLV_CACHE_UNSUPPORTED,  /* the cache can't handle that kind of queries */
93                               /* or the answer buffer is too small */
94    RESOLV_CACHE_NOTFOUND,     /* the cache doesn't know about this query */
95    RESOLV_CACHE_FOUND         /* the cache found the answer */
96} ResolvCacheStatus;
97
98__LIBC_HIDDEN__
99extern ResolvCacheStatus
100_resolv_cache_lookup( struct resolv_cache*  cache,
101                      const void*           query,
102                      int                   querylen,
103                      void*                 answer,
104                      int                   answersize,
105                      int                  *answerlen );
106
107/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
108 * did return RESOLV_CACHE_NOTFOUND
109 */
110__LIBC_HIDDEN__
111extern void
112_resolv_cache_add( struct resolv_cache*  cache,
113                   const void*           query,
114                   int                   querylen,
115                   const void*           answer,
116                   int                   answerlen );
117
118/* Notify the cache a request failed */
119__LIBC_HIDDEN__
120extern void
121_resolv_cache_query_failed( struct resolv_cache* cache,
122                   const void* query,
123                   int         querylen);
124
125#endif /* _RESOLV_CACHE_H_ */
126