mirror of
https://github.com/curl/curl.git
synced 2024-12-03 06:20:31 +08:00
889d1e973f
"if(a)" is our style, not "if( a )"
727 lines
21 KiB
C
727 lines
21 KiB
C
/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at http://curl.haxx.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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***************************************************************************/
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#include "setup.h"
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#include <string.h>
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#ifdef HAVE_SYS_SOCKET_H
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#include <sys/socket.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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#include <netinet/in.h>
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#endif
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#ifdef HAVE_NETDB_H
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#include <netdb.h>
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#endif
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#ifdef HAVE_ARPA_INET_H
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#include <arpa/inet.h>
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h> /* required for free() prototypes */
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h> /* for the close() proto */
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#endif
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#ifdef __VMS
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#include <in.h>
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#include <inet.h>
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#include <stdlib.h>
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#endif
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#ifdef HAVE_SETJMP_H
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#include <setjmp.h>
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#endif
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#ifdef HAVE_SIGNAL_H
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#include <signal.h>
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#endif
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#ifdef HAVE_PROCESS_H
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#include <process.h>
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#endif
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#include "urldata.h"
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#include "sendf.h"
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#include "hostip.h"
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#include "hash.h"
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#include "share.h"
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#include "strerror.h"
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#include "url.h"
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#include "inet_ntop.h"
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#include "warnless.h"
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#define _MPRINTF_REPLACE /* use our functions only */
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#include <curl/mprintf.h>
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#include "curl_memory.h"
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/* The last #include file should be: */
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#include "memdebug.h"
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#if defined(CURLRES_SYNCH) && \
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defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
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/* alarm-based timeouts can only be used with all the dependencies satisfied */
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#define USE_ALARM_TIMEOUT
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#endif
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/*
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* hostip.c explained
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* ==================
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*
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* The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
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* source file are these:
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*
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* CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
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* that. The host may not be able to resolve IPv6, but we don't really have to
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* take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
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* defined.
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*
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* CURLRES_ARES - is defined if libcurl is built to use c-ares for
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* asynchronous name resolves. This can be Windows or *nix.
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*
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* CURLRES_THREADED - is defined if libcurl is built to run under (native)
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* Windows, and then the name resolve will be done in a new thread, and the
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* supported API will be the same as for ares-builds.
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*
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* If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
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* libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
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* defined.
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*
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* The host*.c sources files are split up like this:
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*
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* hostip.c - method-independent resolver functions and utility functions
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* hostasyn.c - functions for asynchronous name resolves
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* hostsyn.c - functions for synchronous name resolves
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* hostip4.c - ipv4-specific functions
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* hostip6.c - ipv6-specific functions
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*
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* The two asynchronous name resolver backends are implemented in:
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* asyn-ares.c - functions for ares-using name resolves
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* asyn-thread.c - functions for threaded name resolves
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* The hostip.h is the united header file for all this. It defines the
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* CURLRES_* defines based on the config*.h and setup.h defines.
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*/
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/* These two symbols are for the global DNS cache */
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static struct curl_hash hostname_cache;
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static int host_cache_initialized;
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static void freednsentry(void *freethis);
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/*
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* Curl_global_host_cache_init() initializes and sets up a global DNS cache.
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* Global DNS cache is general badness. Do not use. This will be removed in
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* a future version. Use the share interface instead!
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*
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* Returns a struct curl_hash pointer on success, NULL on failure.
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*/
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struct curl_hash *Curl_global_host_cache_init(void)
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{
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int rc = 0;
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if(!host_cache_initialized) {
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rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str,
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Curl_str_key_compare, freednsentry);
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if(!rc)
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host_cache_initialized = 1;
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}
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return rc?NULL:&hostname_cache;
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}
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/*
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* Destroy and cleanup the global DNS cache
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*/
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void Curl_global_host_cache_dtor(void)
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{
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if(host_cache_initialized) {
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Curl_hash_clean(&hostname_cache);
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host_cache_initialized = 0;
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}
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}
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/*
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* Return # of adresses in a Curl_addrinfo struct
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*/
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int Curl_num_addresses(const Curl_addrinfo *addr)
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{
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int i = 0;
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while(addr) {
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addr = addr->ai_next;
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i++;
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}
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return i;
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}
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/*
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* Curl_printable_address() returns a printable version of the 1st address
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* given in the 'ai' argument. The result will be stored in the buf that is
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* bufsize bytes big.
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*
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* If the conversion fails, it returns NULL.
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*/
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const char *
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Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
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{
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const struct sockaddr_in *sa4;
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const struct in_addr *ipaddr4;
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#ifdef ENABLE_IPV6
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const struct sockaddr_in6 *sa6;
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const struct in6_addr *ipaddr6;
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#endif
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switch (ai->ai_family) {
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case AF_INET:
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sa4 = (const void *)ai->ai_addr;
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ipaddr4 = &sa4->sin_addr;
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return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf,
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bufsize);
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#ifdef ENABLE_IPV6
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case AF_INET6:
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sa6 = (const void *)ai->ai_addr;
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ipaddr6 = &sa6->sin6_addr;
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return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf,
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bufsize);
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#endif
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default:
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break;
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}
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return NULL;
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}
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/*
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* Return a hostcache id string for the providing host + port, to be used by
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* the DNS caching.
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*/
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static char *
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create_hostcache_id(const char *server, int port)
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{
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/* create and return the new allocated entry */
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return aprintf("%s:%d", server, port);
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}
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struct hostcache_prune_data {
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long cache_timeout;
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time_t now;
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};
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/*
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* This function is set as a callback to be called for every entry in the DNS
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* cache when we want to prune old unused entries.
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*
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* Returning non-zero means remove the entry, return 0 to keep it in the
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* cache.
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*/
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static int
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hostcache_timestamp_remove(void *datap, void *hc)
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{
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struct hostcache_prune_data *data =
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(struct hostcache_prune_data *) datap;
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struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
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return (data->now - c->timestamp >= data->cache_timeout);
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}
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/*
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* Prune the DNS cache. This assumes that a lock has already been taken.
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*/
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static void
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hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
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{
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struct hostcache_prune_data user;
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user.cache_timeout = cache_timeout;
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user.now = now;
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Curl_hash_clean_with_criterium(hostcache,
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(void *) &user,
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hostcache_timestamp_remove);
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}
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/*
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* Library-wide function for pruning the DNS cache. This function takes and
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* returns the appropriate locks.
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*/
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void Curl_hostcache_prune(struct SessionHandle *data)
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{
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time_t now;
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if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
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/* cache forever means never prune, and NULL hostcache means
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we can't do it */
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return;
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if(data->share)
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Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
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time(&now);
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/* Remove outdated and unused entries from the hostcache */
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hostcache_prune(data->dns.hostcache,
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data->set.dns_cache_timeout,
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now);
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if(data->share)
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Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
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}
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/*
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* Check if the entry should be pruned. Assumes a locked cache.
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*/
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static int
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remove_entry_if_stale(struct SessionHandle *data, struct Curl_dns_entry *dns)
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{
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struct hostcache_prune_data user;
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if(!dns || (data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
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/* cache forever means never prune, and NULL hostcache means
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we can't do it */
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return 0;
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time(&user.now);
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user.cache_timeout = data->set.dns_cache_timeout;
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if(!hostcache_timestamp_remove(&user,dns) )
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return 0;
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Curl_hash_clean_with_criterium(data->dns.hostcache,
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(void *) &user,
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hostcache_timestamp_remove);
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return 1;
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}
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#ifdef HAVE_SIGSETJMP
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/* Beware this is a global and unique instance. This is used to store the
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return address that we can jump back to from inside a signal handler. This
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is not thread-safe stuff. */
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sigjmp_buf curl_jmpenv;
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#endif
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/*
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* Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
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*
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* When calling Curl_resolv() has resulted in a response with a returned
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* address, we call this function to store the information in the dns
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* cache etc
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*
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* Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
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*/
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struct Curl_dns_entry *
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Curl_cache_addr(struct SessionHandle *data,
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Curl_addrinfo *addr,
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const char *hostname,
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int port)
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{
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char *entry_id;
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size_t entry_len;
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struct Curl_dns_entry *dns;
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struct Curl_dns_entry *dns2;
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/* Create an entry id, based upon the hostname and port */
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entry_id = create_hostcache_id(hostname, port);
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/* If we can't create the entry id, fail */
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if(!entry_id)
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return NULL;
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entry_len = strlen(entry_id);
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/* Create a new cache entry */
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dns = calloc(1, sizeof(struct Curl_dns_entry));
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if(!dns) {
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free(entry_id);
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return NULL;
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}
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dns->inuse = 0; /* init to not used */
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dns->addr = addr; /* this is the address(es) */
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time(&dns->timestamp);
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if(dns->timestamp == 0)
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dns->timestamp = 1; /* zero indicates that entry isn't in hash table */
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/* Store the resolved data in our DNS cache. */
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dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
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(void *)dns);
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if(!dns2) {
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free(dns);
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free(entry_id);
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return NULL;
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}
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dns = dns2;
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dns->inuse++; /* mark entry as in-use */
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/* free the allocated entry_id */
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free(entry_id);
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return dns;
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}
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/*
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* Curl_resolv() is the main name resolve function within libcurl. It resolves
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* a name and returns a pointer to the entry in the 'entry' argument (if one
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* is provided). This function might return immediately if we're using asynch
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* resolves. See the return codes.
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*
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* The cache entry we return will get its 'inuse' counter increased when this
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* function is used. You MUST call Curl_resolv_unlock() later (when you're
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* done using this struct) to decrease the counter again.
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*
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* In debug mode, we specifically test for an interface name "LocalHost"
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* and resolve "localhost" instead as a means to permit test cases
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* to connect to a local test server with any host name.
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*
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* Return codes:
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*
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* CURLRESOLV_ERROR (-1) = error, no pointer
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* CURLRESOLV_RESOLVED (0) = OK, pointer provided
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* CURLRESOLV_PENDING (1) = waiting for response, no pointer
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*/
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int Curl_resolv(struct connectdata *conn,
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const char *hostname,
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int port,
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struct Curl_dns_entry **entry)
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{
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char *entry_id = NULL;
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struct Curl_dns_entry *dns = NULL;
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size_t entry_len;
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struct SessionHandle *data = conn->data;
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CURLcode result;
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int rc = CURLRESOLV_ERROR; /* default to failure */
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*entry = NULL;
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/* Create an entry id, based upon the hostname and port */
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entry_id = create_hostcache_id(hostname, port);
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/* If we can't create the entry id, fail */
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if(!entry_id)
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return rc;
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entry_len = strlen(entry_id);
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if(data->share)
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Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
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/* See if its already in our dns cache */
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dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
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/* free the allocated entry_id again */
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free(entry_id);
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/* See whether the returned entry is stale. Done before we release lock */
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if(remove_entry_if_stale(data, dns))
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dns = NULL; /* the memory deallocation is being handled by the hash */
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if(dns) {
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dns->inuse++; /* we use it! */
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rc = CURLRESOLV_RESOLVED;
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}
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if(data->share)
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Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
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if(!dns) {
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/* The entry was not in the cache. Resolve it to IP address */
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Curl_addrinfo *addr;
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int respwait;
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/* Check what IP specifics the app has requested and if we can provide it.
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* If not, bail out. */
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if(!Curl_ipvalid(conn))
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return CURLRESOLV_ERROR;
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/* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
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non-zero value indicating that we need to wait for the response to the
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resolve call */
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addr = Curl_getaddrinfo(conn,
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#ifdef DEBUGBUILD
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(data->set.str[STRING_DEVICE]
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&& !strcmp(data->set.str[STRING_DEVICE],
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"LocalHost"))?"localhost":
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#endif
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hostname, port, &respwait);
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if(!addr) {
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if(respwait) {
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/* the response to our resolve call will come asynchronously at
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a later time, good or bad */
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/* First, check that we haven't received the info by now */
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result = Curl_resolver_is_resolved(conn, &dns);
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if(result) /* error detected */
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return CURLRESOLV_ERROR;
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if(dns)
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rc = CURLRESOLV_RESOLVED; /* pointer provided */
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else
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rc = CURLRESOLV_PENDING; /* no info yet */
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}
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}
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else {
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if(data->share)
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Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
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/* we got a response, store it in the cache */
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dns = Curl_cache_addr(data, addr, hostname, port);
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if(data->share)
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Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
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if(!dns)
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/* returned failure, bail out nicely */
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Curl_freeaddrinfo(addr);
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else
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rc = CURLRESOLV_RESOLVED;
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}
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}
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*entry = dns;
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return rc;
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}
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#ifdef USE_ALARM_TIMEOUT
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/*
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* This signal handler jumps back into the main libcurl code and continues
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* execution. This effectively causes the remainder of the application to run
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* within a signal handler which is nonportable and could lead to problems.
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*/
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static
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RETSIGTYPE alarmfunc(int sig)
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{
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/* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
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(void)sig;
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siglongjmp(curl_jmpenv, 1);
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return;
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}
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#endif /* USE_ALARM_TIMEOUT */
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/*
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* Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
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* timeout. This function might return immediately if we're using asynch
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* resolves. See the return codes.
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|
*
|
|
* The cache entry we return will get its 'inuse' counter increased when this
|
|
* function is used. You MUST call Curl_resolv_unlock() later (when you're
|
|
* done using this struct) to decrease the counter again.
|
|
*
|
|
* If built with a synchronous resolver and use of signals is not
|
|
* disabled by the application, then a nonzero timeout will cause a
|
|
* timeout after the specified number of milliseconds. Otherwise, timeout
|
|
* is ignored.
|
|
*
|
|
* Return codes:
|
|
*
|
|
* CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
|
|
* CURLRESOLV_ERROR (-1) = error, no pointer
|
|
* CURLRESOLV_RESOLVED (0) = OK, pointer provided
|
|
* CURLRESOLV_PENDING (1) = waiting for response, no pointer
|
|
*/
|
|
|
|
int Curl_resolv_timeout(struct connectdata *conn,
|
|
const char *hostname,
|
|
int port,
|
|
struct Curl_dns_entry **entry,
|
|
long timeoutms)
|
|
{
|
|
#ifdef USE_ALARM_TIMEOUT
|
|
#ifdef HAVE_SIGACTION
|
|
struct sigaction keep_sigact; /* store the old struct here */
|
|
volatile bool keep_copysig = FALSE; /* wether old sigact has been saved */
|
|
struct sigaction sigact;
|
|
#else
|
|
#ifdef HAVE_SIGNAL
|
|
void (*keep_sigact)(int); /* store the old handler here */
|
|
#endif /* HAVE_SIGNAL */
|
|
#endif /* HAVE_SIGACTION */
|
|
volatile long timeout;
|
|
volatile unsigned int prev_alarm = 0;
|
|
struct SessionHandle *data = conn->data;
|
|
#endif /* USE_ALARM_TIMEOUT */
|
|
int rc;
|
|
|
|
*entry = NULL;
|
|
|
|
#ifdef USE_ALARM_TIMEOUT
|
|
if(data->set.no_signal)
|
|
/* Ignore the timeout when signals are disabled */
|
|
timeout = 0;
|
|
else
|
|
timeout = timeoutms;
|
|
|
|
if(!timeout)
|
|
/* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
|
|
return Curl_resolv(conn, hostname, port, entry);
|
|
|
|
if(timeout < 1000)
|
|
/* The alarm() function only provides integer second resolution, so if
|
|
we want to wait less than one second we must bail out already now. */
|
|
return CURLRESOLV_TIMEDOUT;
|
|
|
|
/*************************************************************
|
|
* Set signal handler to catch SIGALRM
|
|
* Store the old value to be able to set it back later!
|
|
*************************************************************/
|
|
#ifdef HAVE_SIGACTION
|
|
sigaction(SIGALRM, NULL, &sigact);
|
|
keep_sigact = sigact;
|
|
keep_copysig = TRUE; /* yes, we have a copy */
|
|
sigact.sa_handler = alarmfunc;
|
|
#ifdef SA_RESTART
|
|
/* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
|
|
sigact.sa_flags &= ~SA_RESTART;
|
|
#endif
|
|
/* now set the new struct */
|
|
sigaction(SIGALRM, &sigact, NULL);
|
|
#else /* HAVE_SIGACTION */
|
|
/* no sigaction(), revert to the much lamer signal() */
|
|
#ifdef HAVE_SIGNAL
|
|
keep_sigact = signal(SIGALRM, alarmfunc);
|
|
#endif
|
|
#endif /* HAVE_SIGACTION */
|
|
|
|
/* alarm() makes a signal get sent when the timeout fires off, and that
|
|
will abort system calls */
|
|
prev_alarm = alarm(curlx_sltoui(timeout/1000L));
|
|
|
|
/* This allows us to time-out from the name resolver, as the timeout
|
|
will generate a signal and we will siglongjmp() from that here.
|
|
This technique has problems (see alarmfunc).
|
|
This should be the last thing we do before calling Curl_resolv(),
|
|
as otherwise we'd have to worry about variables that get modified
|
|
before we invoke Curl_resolv() (and thus use "volatile"). */
|
|
if(sigsetjmp(curl_jmpenv, 1)) {
|
|
/* this is coming from a siglongjmp() after an alarm signal */
|
|
failf(data, "name lookup timed out");
|
|
rc = CURLRESOLV_ERROR;
|
|
goto clean_up;
|
|
}
|
|
|
|
#else
|
|
#ifndef CURLRES_ASYNCH
|
|
if(timeoutms)
|
|
infof(conn->data, "timeout on name lookup is not supported\n");
|
|
#else
|
|
(void)timeoutms; /* timeoutms not used with an async resolver */
|
|
#endif
|
|
#endif /* USE_ALARM_TIMEOUT */
|
|
|
|
/* Perform the actual name resolution. This might be interrupted by an
|
|
* alarm if it takes too long.
|
|
*/
|
|
rc = Curl_resolv(conn, hostname, port, entry);
|
|
|
|
#ifdef USE_ALARM_TIMEOUT
|
|
clean_up:
|
|
|
|
if(!prev_alarm)
|
|
/* deactivate a possibly active alarm before uninstalling the handler */
|
|
alarm(0);
|
|
|
|
#ifdef HAVE_SIGACTION
|
|
if(keep_copysig) {
|
|
/* we got a struct as it looked before, now put that one back nice
|
|
and clean */
|
|
sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
|
|
}
|
|
#else
|
|
#ifdef HAVE_SIGNAL
|
|
/* restore the previous SIGALRM handler */
|
|
signal(SIGALRM, keep_sigact);
|
|
#endif
|
|
#endif /* HAVE_SIGACTION */
|
|
|
|
/* switch back the alarm() to either zero or to what it was before minus
|
|
the time we spent until now! */
|
|
if(prev_alarm) {
|
|
/* there was an alarm() set before us, now put it back */
|
|
unsigned long elapsed_ms = Curl_tvdiff(Curl_tvnow(), conn->created);
|
|
|
|
/* the alarm period is counted in even number of seconds */
|
|
unsigned long alarm_set = prev_alarm - elapsed_ms/1000;
|
|
|
|
if(!alarm_set ||
|
|
((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
|
|
/* if the alarm time-left reached zero or turned "negative" (counted
|
|
with unsigned values), we should fire off a SIGALRM here, but we
|
|
won't, and zero would be to switch it off so we never set it to
|
|
less than 1! */
|
|
alarm(1);
|
|
rc = CURLRESOLV_TIMEDOUT;
|
|
failf(data, "Previous alarm fired off!");
|
|
}
|
|
else
|
|
alarm((unsigned int)alarm_set);
|
|
}
|
|
#endif /* USE_ALARM_TIMEOUT */
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
|
|
* made, the struct may be destroyed due to pruning. It is important that only
|
|
* one unlock is made for each Curl_resolv() call.
|
|
*/
|
|
void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns)
|
|
{
|
|
DEBUGASSERT(dns && (dns->inuse>0));
|
|
|
|
if(data->share)
|
|
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
|
|
|
|
dns->inuse--;
|
|
/* only free if nobody is using AND it is not in hostcache (timestamp ==
|
|
0) */
|
|
if(dns->inuse == 0 && dns->timestamp == 0) {
|
|
Curl_freeaddrinfo(dns->addr);
|
|
free(dns);
|
|
}
|
|
|
|
if(data->share)
|
|
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
|
|
}
|
|
|
|
/*
|
|
* File-internal: free a cache dns entry.
|
|
*/
|
|
static void freednsentry(void *freethis)
|
|
{
|
|
struct Curl_dns_entry *p = (struct Curl_dns_entry *) freethis;
|
|
|
|
/* mark the entry as not in hostcache */
|
|
p->timestamp = 0;
|
|
if(p->inuse == 0) {
|
|
Curl_freeaddrinfo(p->addr);
|
|
free(p);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Curl_mk_dnscache() creates a new DNS cache and returns the handle for it.
|
|
*/
|
|
struct curl_hash *Curl_mk_dnscache(void)
|
|
{
|
|
return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);
|
|
}
|
|
|
|
|