bionic/libc/netbsd/resolv/res_state.c
Mattias Falk c63e59039d dns cache per interface iteration 2
name server addresses are read from the dns
cache associated wih the interface on which
the request shall be done.

processes which has requested to issue dns request
using specific interface are now proxied to netd.

added methods to attach/detach a process to a specific
dns cache/interface.

added getaddrinfoforinface method which takes an
interface as an argument.

bug:4815099
bug:5465296
Change-Id: I7a8fe1980cdf99d4d296ddc5c6411f0c72162263
2013-02-07 09:40:16 -08:00

226 lines
6.4 KiB
C

/*
* 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 <logd.h>
# include <unistd.h> /* for gettid() */
# define D(...) __libc_android_log_print(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 = rt->_pi->serial;
}
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 == rt->_pi->serial) {
/* 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 = rt->_pi->serial;
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;
}