Merge "Add support for a dns cache per interface"
This commit is contained in:
Robert Greenwalt
Android Code Review
commit
cc32fbc305
3 changed files with 480 additions and 21 deletions
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@ -34,6 +34,7 @@
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#include <sys/socket.h>
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#include <stdio.h>
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#include <arpa/nameser.h>
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#include <netinet/in.h>
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__BEGIN_DECLS
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@ -49,6 +50,21 @@ extern struct __res_state *__res_state(void);
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extern int b64_ntop(u_char const *, size_t, char *, size_t);
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extern int b64_pton(char const *, u_char *, size_t);
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/* Set name of default interface */
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extern void _resolv_set_default_iface(const char* ifname);
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/* set name servers for an interface */
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extern void _resolv_set_nameservers_for_iface(const char* ifname, char** servers, int numservers);
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/* tell resolver of the address of an interface */
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extern void _resolv_set_addr_of_iface(const char* ifname, struct in_addr* addr);
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/* flush the cache associated with the default interface */
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extern void _resolv_flush_cache_for_default_iface();
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/* flush the cache associated with a certain interface */
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extern void _resolv_flush_cache_for_iface(const char* ifname);
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__END_DECLS
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#endif /* _RESOLV_H_ */
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@ -27,6 +27,7 @@
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*/
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#include "resolv_cache.h"
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#include <resolv.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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@ -35,6 +36,12 @@
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#include <errno.h>
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#include "arpa_nameser.h"
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#include <sys/system_properties.h>
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#include <net/if.h>
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#include <netdb.h>
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#include <linux/if.h>
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#include <arpa/inet.h>
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#include "resolv_private.h"
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/* This code implements a small and *simple* DNS resolver cache.
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*
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@ -159,9 +166,6 @@
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#include <stdio.h>
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#include <stdarg.h>
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#include <arpa/inet.h>
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#include "resolv_private.h"
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/** BOUNDED BUFFER FORMATTING
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**/
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@ -1165,6 +1169,14 @@ typedef struct resolv_cache {
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Entry* entries;
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} Cache;
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typedef struct resolv_cache_info {
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char ifname[IF_NAMESIZE + 1];
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struct in_addr ifaddr;
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Cache* cache;
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struct resolv_cache_info* next;
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char* nameservers[MAXNS +1];
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struct addrinfo* nsaddrinfo[MAXNS + 1];
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} CacheInfo;
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#define HTABLE_VALID(x) ((x) != NULL && (x) != HTABLE_DELETED)
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@ -1543,11 +1555,47 @@ Exit:
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/****************************************************************************/
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/****************************************************************************/
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static struct resolv_cache* _res_cache;
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static pthread_once_t _res_cache_once;
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// Head of the list of caches. Protected by _res_cache_list_lock.
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static struct resolv_cache_info _res_cache_list;
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// name of the current default inteface
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static char _res_default_ifname[IF_NAMESIZE + 1];
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// lock protecting everything in the _resolve_cache_info structs (next ptr, etc)
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static pthread_mutex_t _res_cache_list_lock;
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/* lookup the default interface name */
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static char *_get_default_iface_locked();
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/* insert resolv_cache_info into the list of resolv_cache_infos */
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static void _insert_cache_info_locked(struct resolv_cache_info* cache_info);
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/* creates a resolv_cache_info */
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static struct resolv_cache_info* _create_cache_info( void );
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/* gets cache associated with an interface name, or NULL if none exists */
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static struct resolv_cache* _find_named_cache_locked(const char* ifname);
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/* gets a resolv_cache_info associated with an interface name, or NULL if not found */
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static struct resolv_cache_info* _find_cache_info_locked(const char* ifname);
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/* free dns name server list of a resolv_cache_info structure */
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static void _free_nameservers(struct resolv_cache_info* cache_info);
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/* look up the named cache, and creates one if needed */
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static struct resolv_cache* _get_res_cache_for_iface_locked(const char* ifname);
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/* empty the named cache */
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static void _flush_cache_for_iface_locked(const char* ifname);
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/* empty the nameservers set for the named cache */
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static void _free_nameservers_locked(struct resolv_cache_info* cache_info);
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/* lookup the namserver for the name interface */
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static int _get_nameserver_locked(const char* ifname, int n, char* addr, int addrLen);
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/* lookup the addr of the nameserver for the named interface */
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static struct addrinfo* _get_nameserver_addr_locked(const char* ifname, int n);
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/* lookup the inteface's address */
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static struct in_addr* _get_addr_locked(const char * ifname);
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static void
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_res_cache_init( void )
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_res_cache_init(void)
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{
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const char* env = getenv(CONFIG_ENV);
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@ -1556,29 +1604,392 @@ _res_cache_init( void )
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return;
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}
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_res_cache = _resolv_cache_create();
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memset(&_res_default_ifname, 0, sizeof(_res_default_ifname));
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memset(&_res_cache_list, 0, sizeof(_res_cache_list));
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pthread_mutex_init(&_res_cache_list_lock, NULL);
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}
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struct resolv_cache*
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__get_res_cache( void )
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__get_res_cache(void)
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{
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pthread_once( &_res_cache_once, _res_cache_init );
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return _res_cache;
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struct resolv_cache *cache;
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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char* ifname = _get_default_iface_locked();
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// if default interface not set then use the first cache
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// associated with an interface as the default one.
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if (ifname[0] == '\0') {
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struct resolv_cache_info* cache_info = _res_cache_list.next;
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while (cache_info) {
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if (cache_info->ifname[0] != '\0') {
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ifname = cache_info->ifname;
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}
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cache_info = cache_info->next;
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}
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}
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cache = _get_res_cache_for_iface_locked(ifname);
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pthread_mutex_unlock(&_res_cache_list_lock);
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XLOG("_get_res_cache. default_ifname = %s\n", ifname);
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return cache;
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}
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static struct resolv_cache*
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_get_res_cache_for_iface_locked(const char* ifname)
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{
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if (ifname == NULL)
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return NULL;
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struct resolv_cache* cache = _find_named_cache_locked(ifname);
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if (!cache) {
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struct resolv_cache_info* cache_info = _create_cache_info();
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if (cache_info) {
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cache = _resolv_cache_create();
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if (cache) {
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int len = sizeof(cache_info->ifname);
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cache_info->cache = cache;
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strncpy(cache_info->ifname, ifname, len - 1);
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cache_info->ifname[len - 1] = '\0';
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_insert_cache_info_locked(cache_info);
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} else {
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free(cache_info);
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}
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}
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}
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return cache;
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}
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void
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_resolv_cache_reset( unsigned generation )
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_resolv_cache_reset(unsigned generation)
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{
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XLOG("%s: generation=%d", __FUNCTION__, generation);
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if (_res_cache == NULL)
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return;
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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pthread_mutex_lock( &_res_cache->lock );
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if (_res_cache->generation != generation) {
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_cache_flush_locked(_res_cache);
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_res_cache->generation = generation;
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char* ifname = _get_default_iface_locked();
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// if default interface not set then use the first cache
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// associated with an interface as the default one.
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// Note: Copied the code from __get_res_cache since this
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// method will be deleted/obsolete when cache per interface
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// implemented all over
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if (ifname[0] == '\0') {
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struct resolv_cache_info* cache_info = _res_cache_list.next;
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while (cache_info) {
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if (cache_info->ifname[0] != '\0') {
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ifname = cache_info->ifname;
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}
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cache_info = cache_info->next;
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}
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}
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pthread_mutex_unlock( &_res_cache->lock );
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struct resolv_cache* cache = _get_res_cache_for_iface_locked(ifname);
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if (cache == NULL) {
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pthread_mutex_unlock(&_res_cache_list_lock);
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return;
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}
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pthread_mutex_lock( &cache->lock );
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if (cache->generation != generation) {
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_cache_flush_locked(cache);
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cache->generation = generation;
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}
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pthread_mutex_unlock( &cache->lock );
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pthread_mutex_unlock(&_res_cache_list_lock);
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}
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void
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_resolv_flush_cache_for_default_iface(void)
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{
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char* ifname;
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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ifname = _get_default_iface_locked();
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_flush_cache_for_iface_locked(ifname);
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pthread_mutex_unlock(&_res_cache_list_lock);
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}
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void
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_resolv_flush_cache_for_iface(const char* ifname)
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{
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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_flush_cache_for_iface_locked(ifname);
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pthread_mutex_unlock(&_res_cache_list_lock);
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}
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static void
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_flush_cache_for_iface_locked(const char* ifname)
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{
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struct resolv_cache* cache = _find_named_cache_locked(ifname);
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if (cache) {
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pthread_mutex_lock(&cache->lock);
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_cache_flush_locked(cache);
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pthread_mutex_unlock(&cache->lock);
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}
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}
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static struct resolv_cache_info*
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_create_cache_info(void)
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{
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struct resolv_cache_info* cache_info;
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cache_info = calloc(sizeof(*cache_info), 1);
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return cache_info;
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}
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static void
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_insert_cache_info_locked(struct resolv_cache_info* cache_info)
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{
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struct resolv_cache_info* last;
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for (last = &_res_cache_list; last->next; last = last->next);
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last->next = cache_info;
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}
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static struct resolv_cache*
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_find_named_cache_locked(const char* ifname) {
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struct resolv_cache_info* info = _find_cache_info_locked(ifname);
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if (info != NULL) return info->cache;
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return NULL;
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}
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static struct resolv_cache_info*
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_find_cache_info_locked(const char* ifname)
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{
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if (ifname == NULL)
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return NULL;
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struct resolv_cache_info* cache_info = _res_cache_list.next;
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while (cache_info) {
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if (strcmp(cache_info->ifname, ifname) == 0) {
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break;
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}
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cache_info = cache_info->next;
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}
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return cache_info;
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}
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static char*
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_get_default_iface_locked(void)
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{
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char* iface = _res_default_ifname;
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return iface;
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}
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void
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_resolv_set_default_iface(const char* ifname)
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{
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XLOG("_resolv_set_default_if ifname %s\n",ifname);
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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int size = sizeof(_res_default_ifname);
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memset(_res_default_ifname, 0, size);
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strncpy(_res_default_ifname, ifname, size - 1);
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_res_default_ifname[size - 1] = '\0';
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pthread_mutex_unlock(&_res_cache_list_lock);
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}
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void
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_resolv_set_nameservers_for_iface(const char* ifname, char** servers, int numservers)
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{
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int i, rt, index;
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struct addrinfo hints;
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char sbuf[NI_MAXSERV];
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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// creates the cache if not created
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_get_res_cache_for_iface_locked(ifname);
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struct resolv_cache_info* cache_info = _find_cache_info_locked(ifname);
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if (cache_info != NULL) {
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// free current before adding new
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_free_nameservers_locked(cache_info);
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = PF_UNSPEC;
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hints.ai_socktype = SOCK_DGRAM; /*dummy*/
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hints.ai_flags = AI_NUMERICHOST;
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sprintf(sbuf, "%u", NAMESERVER_PORT);
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index = 0;
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for (i = 0; i < numservers && i < MAXNS; i++) {
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rt = getaddrinfo(servers[i], sbuf, &hints, &cache_info->nsaddrinfo[index]);
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if (rt == 0) {
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cache_info->nameservers[index] = strdup(servers[i]);
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index++;
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} else {
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cache_info->nsaddrinfo[index] = NULL;
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}
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}
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}
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pthread_mutex_unlock(&_res_cache_list_lock);
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}
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static void
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_free_nameservers_locked(struct resolv_cache_info* cache_info)
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{
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int i;
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for (i = 0; i <= MAXNS; i++) {
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free(cache_info->nameservers[i]);
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cache_info->nameservers[i] = NULL;
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freeaddrinfo(cache_info->nsaddrinfo[i]);
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cache_info->nsaddrinfo[i] = NULL;
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}
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}
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int
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_resolv_cache_get_nameserver(int n, char* addr, int addrLen)
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{
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char *ifname;
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int result = 0;
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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ifname = _get_default_iface_locked();
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result = _get_nameserver_locked(ifname, n, addr, addrLen);
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pthread_mutex_unlock(&_res_cache_list_lock);
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return result;
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}
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static int
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_get_nameserver_locked(const char* ifname, int n, char* addr, int addrLen)
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{
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int len = 0;
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char* ns;
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struct resolv_cache_info* cache_info;
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if (n < 1 || n > MAXNS || !addr)
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return 0;
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cache_info = _find_cache_info_locked(ifname);
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if (cache_info) {
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ns = cache_info->nameservers[n - 1];
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if (ns) {
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len = strlen(ns);
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if (len < addrLen) {
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strncpy(addr, ns, len);
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addr[len] = '\0';
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} else {
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len = 0;
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}
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}
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}
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return len;
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}
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struct addrinfo*
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_cache_get_nameserver_addr(int n)
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{
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struct addrinfo *result;
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char* ifname;
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pthread_once(&_res_cache_once, _res_cache_init);
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pthread_mutex_lock(&_res_cache_list_lock);
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ifname = _get_default_iface_locked();
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result = _get_nameserver_addr_locked(ifname, n);
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pthread_mutex_unlock(&_res_cache_list_lock);
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return result;
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}
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static struct addrinfo*
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_get_nameserver_addr_locked(const char* ifname, int n)
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{
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struct addrinfo* ai = NULL;
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struct resolv_cache_info* cache_info;
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if (n < 1 || n > MAXNS)
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return NULL;
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cache_info = _find_cache_info_locked(ifname);
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if (cache_info) {
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ai = cache_info->nsaddrinfo[n - 1];
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}
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return ai;
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}
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void
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_resolv_set_addr_of_iface(const char* ifname, struct in_addr* addr)
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{
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pthread_once(&_res_cache_once, _res_cache_init);
|
||||
pthread_mutex_lock(&_res_cache_list_lock);
|
||||
struct resolv_cache_info* cache_info = _find_cache_info_locked(ifname);
|
||||
if (cache_info) {
|
||||
memcpy(&cache_info->ifaddr, addr, sizeof(*addr));
|
||||
|
||||
if (DEBUG) {
|
||||
char* addr_s = inet_ntoa(cache_info->ifaddr);
|
||||
XLOG("address of interface %s is %s\n", ifname, addr_s);
|
||||
}
|
||||
}
|
||||
pthread_mutex_unlock(&_res_cache_list_lock);
|
||||
}
|
||||
|
||||
struct in_addr*
|
||||
_resolv_get_addr_of_default_iface(void)
|
||||
{
|
||||
struct in_addr* ai = NULL;
|
||||
char* ifname;
|
||||
|
||||
pthread_once(&_res_cache_once, _res_cache_init);
|
||||
pthread_mutex_lock(&_res_cache_list_lock);
|
||||
ifname = _get_default_iface_locked();
|
||||
ai = _get_addr_locked(ifname);
|
||||
pthread_mutex_unlock(&_res_cache_list_lock);
|
||||
|
||||
return ai;
|
||||
}
|
||||
|
||||
struct in_addr*
|
||||
_resolv_get_addr_of_iface(const char* ifname)
|
||||
{
|
||||
struct in_addr* ai = NULL;
|
||||
|
||||
pthread_once(&_res_cache_once, _res_cache_init);
|
||||
pthread_mutex_lock(&_res_cache_list_lock);
|
||||
ai =_get_addr_locked(ifname);
|
||||
pthread_mutex_unlock(&_res_cache_list_lock);
|
||||
return ai;
|
||||
}
|
||||
|
||||
static struct in_addr*
|
||||
_get_addr_locked(const char * ifname)
|
||||
{
|
||||
struct resolv_cache_info* cache_info = _find_cache_info_locked(ifname);
|
||||
if (cache_info) {
|
||||
return &cache_info->ifaddr;
|
||||
}
|
||||
return NULL;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -30,13 +30,45 @@
|
|||
|
||||
struct resolv_cache; /* forward */
|
||||
|
||||
/* get cache instance, can be NULL if cache is disabled
|
||||
* (e.g. through an environment variable) */
|
||||
/* gets the cache for the default interface. Might be NULL*/
|
||||
extern struct resolv_cache* __get_res_cache(void);
|
||||
|
||||
/* get the cache for a specified interface. Can be NULL*/
|
||||
extern struct resolv_cache* __get_res_cache_for_iface(const char* ifname);
|
||||
|
||||
/* this gets called everytime we detect some changes in the DNS configuration
|
||||
* and will flush the cache */
|
||||
extern void _resolv_cache_reset( unsigned generation );
|
||||
extern void _resolv_cache_reset( unsigned generation );
|
||||
|
||||
/* Gets the address of the n:th name server for the default interface
|
||||
* Return length of address on success else 0.
|
||||
* Note: The first name server is at n = 1 */
|
||||
extern int _resolv_cache_get_nameserver(int n, char* addr, int addrLen);
|
||||
|
||||
/* Gets the address of the n:th name server for a certain interface
|
||||
* Return length of address on success else 0.
|
||||
* Note: The first name server is at n = 1 */
|
||||
extern int _resolv_cache_get_nameserver_for_iface(const char* ifname, int n,
|
||||
char* addr, int addrLen);
|
||||
|
||||
/* Gets addrinfo of the n:th name server associated with an interface.
|
||||
* NULL is returned if no address if found.
|
||||
* Note: The first name server is at n = 1. */
|
||||
extern struct addrinfo* _resolv_cache_get_nameserver_addr_for_iface(const char* ifname, int n);
|
||||
|
||||
/* Gets addrinfo of the n:th name server associated with the default interface
|
||||
* NULL is returned if no address if found.
|
||||
* Note: The first name server is at n = 1. */
|
||||
extern struct addrinfo* _resolv_cache_get_nameserver_addr(int n);
|
||||
|
||||
/* gets the address associated with the default interface */
|
||||
extern struct in_addr* _resolv_get_addr_of_default_iface();
|
||||
|
||||
/* gets the address associated with the specified interface */
|
||||
extern struct in_addr* _resolv_get_addr_of_iface(const char* ifname);
|
||||
|
||||
/* Get name of default interface */
|
||||
extern char* _resolv_get_default_iface();
|
||||
|
||||
typedef enum {
|
||||
RESOLV_CACHE_UNSUPPORTED, /* the cache can't handle that kind of queries */
|
||||
|
|
|
|||
Loading…
Reference in a new issue