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 34 struct __res_state; 35 struct 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__ 41 extern 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__ 46 extern 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__ 52 extern 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__ 58 extern 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__ 65 extern 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__ 71 extern struct addrinfo* _resolv_cache_get_nameserver_addr(int n); 72 73 /* gets the address associated with the default interface */ 74 __LIBC_HIDDEN__ 75 extern struct in_addr* _resolv_get_addr_of_default_iface(); 76 77 /* gets the address associated with the specified interface */ 78 __LIBC_HIDDEN__ 79 extern 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__ 91 extern void _resolv_populate_res_for_iface(struct __res_state* statp); 92 93 typedef 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__ 101 extern 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__ 113 extern 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__ 122 extern void 123 _resolv_cache_query_failed( struct resolv_cache* cache, 124 const void* query, 125 int querylen); 126 127 #endif /* _RESOLV_CACHE_H_ */ 128