| /* |
| * 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. |
| */ |
| |
| #define LOG_TAG "res_state" |
| |
| #include <arpa/inet.h> |
| #include <arpa/nameser.h> |
| #include <netdb.h> |
| #include <pthread.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/types.h> |
| #include <unistd.h> /* for gettid() */ |
| |
| #include <android-base/logging.h> |
| |
| #include "resolv_cache.h" |
| #include "resolv_private.h" |
| |
| typedef struct { |
| // 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 = (_res_thread*) calloc(1, sizeof(*rt)); |
| |
| if (rt) { |
| memset(rt->_rstatic, 0, sizeof rt->_rstatic); |
| } |
| return rt; |
| } |
| |
| static void res_static_done(struct 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 = (_res_thread*) _rt; |
| |
| LOG(VERBOSE) << __func__ << ": rt=" << rt << " for thread=" << 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 = (_res_thread*) 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); |
| |
| /* Reset the state, note that res_ninit() can now properly reset |
| * an existing state without leaking memory. |
| */ |
| LOG(VERBOSE) << __func__ << ": tid=" << gettid() << ", rt=" << rt |
| << " setting DNS state (options=" << rt->_nres->options << ")"; |
| if (res_ninit(rt->_nres) < 0) { |
| /* This should not happen */ |
| LOG(VERBOSE) << __func__ << ": tid=" << gettid() << " rt=" << rt |
| << ", res_ninit() returned < 0"; |
| res_thread_free(rt); |
| pthread_setspecific(_res_key, NULL); |
| return NULL; |
| } |
| return rt; |
| } |
| |
| struct __res_state _nres; |
| |
| res_state res_get_state(void) { |
| _res_thread* rt = res_thread_get(); |
| |
| return rt ? rt->_nres : NULL; |
| } |
| |
| res_static* res_get_static(void) { |
| _res_thread* rt = res_thread_get(); |
| |
| return rt ? rt->_rstatic : NULL; |
| } |