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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include "resolv_private.h"
#include "resolv_cache.h"
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
/* Set to 1 to enable debug traces */
#define DEBUG 0
#if DEBUG
# include <async_safe/log.h>
# include <unistd.h> /* for gettid() */
# define D(...) async_safe_format_log(ANDROID_LOG_DEBUG,"libc", __VA_ARGS__)
#else
# define D(...) do{}while(0)
#endif
typedef struct {
int _h_errno;
// TODO: Have one __res_state per network so we don't have to repopulate frequently.
struct __res_state _nres[1];
struct res_static _rstatic[1];
} _res_thread;
static _res_thread*
_res_thread_alloc(void)
{
_res_thread* rt = calloc(1, sizeof(*rt));
if (rt) {
rt->_h_errno = 0;
memset(rt->_rstatic, 0, sizeof rt->_rstatic);
}
return rt;
}
static void
_res_static_done( res_static rs )
{
/* fortunately, there is nothing to do here, since the
* points in h_addr_ptrs and host_aliases should all
* point to 'hostbuf'
*/
if (rs->hostf) { /* should not happen in theory, but just be safe */
fclose(rs->hostf);
rs->hostf = NULL;
}
free(rs->servent.s_aliases);
}
static void
_res_thread_free( void* _rt )
{
_res_thread* rt = _rt;
D("%s: rt=%p for thread=%d", __FUNCTION__, rt, gettid());
_res_static_done(rt->_rstatic);
res_ndestroy(rt->_nres);
free(rt);
}
static pthread_key_t _res_key;
__attribute__((constructor)) static void __res_key_init() {
pthread_key_create(&_res_key, _res_thread_free);
}
static _res_thread*
_res_thread_get(void)
{
_res_thread* rt;
rt = pthread_getspecific( _res_key );
if (rt != NULL) {
return rt;
}
/* It is the first time this function is called in this thread,
* we need to create a new thread-specific DNS resolver state. */
rt = _res_thread_alloc();
if (rt == NULL) {
return NULL;
}
pthread_setspecific( _res_key, rt );
D("%s: tid=%d Created new DNS state rt=%p",
__FUNCTION__, gettid(), rt);
/* Reset the state, note that res_ninit() can now properly reset
* an existing state without leaking memory.
*/
D("%s: tid=%d, rt=%p, setting DNS state (options RES_INIT=%d)",
__FUNCTION__, gettid(), rt, (rt->_nres->options & RES_INIT) != 0);
if ( res_ninit( rt->_nres ) < 0 ) {
/* This should not happen */
D("%s: tid=%d rt=%p, woot, res_ninit() returned < 0",
__FUNCTION__, gettid(), rt);
_res_thread_free(rt);
pthread_setspecific( _res_key, NULL );
return NULL;
}
return rt;
}
__LIBC_HIDDEN__
struct __res_state _nres;
#if 0
struct resolv_cache*
__get_res_cache(void)
{
_res_thread* rt = _res_thread_get();
if (!rt)
return NULL;
if (!rt->_cache) {
rt->_cache = _resolv_cache_create();
}
return rt->_cache;
}
#endif
int*
__get_h_errno(void)
{
_res_thread* rt = _res_thread_get();
static int panic = NETDB_INTERNAL;
return rt ? &rt->_h_errno : &panic;
}
res_state
__res_get_state(void)
{
_res_thread* rt = _res_thread_get();
return rt ? rt->_nres : NULL;
}
void
__res_put_state(res_state res __unused)
{
/* nothing to do */
}
res_static
__res_get_static(void)
{
_res_thread* rt = _res_thread_get();
return rt ? rt->_rstatic : NULL;
}
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