/* * 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 "private/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 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; }