mirror of
https://github.com/moparisthebest/curl
synced 2024-11-05 00:55:04 -05:00
1b24b89cca
CURLOPT_RESOLVE is a new option that sends along a curl_slist with name:port:address sets that will populate the DNS cache with entries so that request can be "fooled" to use another host than what otherwise would've been used. Previously we've encouraged the use of Host: for that when dealing with HTTP, but this new feature has the added bonus that it allows the name from the URL to be used for TLS SNI and server certificate name checks as well. This is a first change. Surely more will follow to make it decent.
724 lines
21 KiB
C
724 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 - 2010, 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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#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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* hostares.c - functions for ares-using name resolves
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* hostthre.c - functions for threaded 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 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 again */
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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(data))
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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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|
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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_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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|
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#ifdef USE_ALARM_TIMEOUT
|
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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
|
|
* within a signal handler which is nonportable and could lead to problems.
|
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*/
|
|
static
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RETSIGTYPE alarmfunc(int sig)
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{
|
|
/* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
|
|
(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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/*
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* Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
|
|
* timeout. This function might return immediately if we're using asynch
|
|
* resolves. See the return codes.
|
|
*
|
|
* 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((unsigned int) (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);
|
|
}
|
|
|
|
|