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