/*
* 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>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
/* Set to 1 to enable debug traces */
#define DEBUG 0
#if DEBUG
# include "libc_logging.h"
# include <unistd.h> /* for gettid() */
# define D(...) __libc_format_log(ANDROID_LOG_DEBUG,"libc", __VA_ARGS__)
#else
# define D(...) do{}while(0)
#endif
static pthread_key_t _res_key;
static pthread_once_t _res_once = PTHREAD_ONCE_INIT;
typedef struct {
int _h_errno;
struct __res_state _nres[1];
unsigned _serial;
struct prop_info* _pi;
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;
/* Special system property which tracks any changes to 'net.*'. */
rt->_serial = 0;
rt->_pi = (struct prop_info*) __system_property_find("net.change");
if (rt->_pi) {
rt->_serial = __system_property_serial(rt->_pi);
}
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 void
_res_init_key( void )
{
pthread_key_create( &_res_key, _res_thread_free );
}
static _res_thread*
_res_thread_get(void)
{
_res_thread* rt;
pthread_once( &_res_once, _res_init_key );
rt = pthread_getspecific( _res_key );
if (rt != NULL) {
/* We already have one thread-specific DNS state object.
* Check the serial value for any changes to net.* properties */
D("%s: Called for tid=%d rt=%p rt->pi=%p rt->serial=%d",
__FUNCTION__, gettid(), rt, rt->_pi, rt->_serial);
if (rt->_pi == NULL) {
/* The property wasn't created when _res_thread_get() was
* called the last time. This should only happen very
* early during the boot sequence. First, let's try to see if it
* is here now. */
rt->_pi = (struct prop_info*) __system_property_find("net.change");
if (rt->_pi == NULL) {
/* Still nothing, return current state */
D("%s: exiting for tid=%d rt=%d since system property not found",
__FUNCTION__, gettid(), rt);
return rt;
}
}
if (rt->_serial == __system_property_serial(rt->_pi)) {
/* Nothing changed, so return the current state */
D("%s: tid=%d rt=%p nothing changed, returning",
__FUNCTION__, gettid(), rt);
return rt;
}
/* Update the recorded serial number, and go reset the state */
rt->_serial = __system_property_serial(rt->_pi);
goto RESET_STATE;
}
/* 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_STATE:
/* Reset the state, note that res_ninit() can now properly reset
* an existing state without leaking memory.
*/
D("%s: tid=%d, rt=%p, resetting 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)
{
/* nothing to do */
res=res;
}
res_static
__res_get_static(void)
{
_res_thread* rt = _res_thread_get();
return rt ? rt->_rstatic : NULL;
}