1 /***************************************************************************
3 * Project ___| | | | _ \| |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
8 * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at http://curl.haxx.se/docs/copyright.html.
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
21 ***************************************************************************/
25 #ifdef HAVE_SYS_SOCKET_H
26 #include <sys/socket.h>
28 #ifdef HAVE_NETINET_IN_H
29 #include <netinet/in.h>
34 #ifdef HAVE_ARPA_INET_H
35 #include <arpa/inet.h>
38 #include <unistd.h> /* for the close() proto */
63 #include "inet_ntop.h"
66 #define _MPRINTF_REPLACE /* use our functions only */
67 #include <curl/mprintf.h>
69 #include "curl_memory.h"
70 /* The last #include file should be: */
73 #if defined(CURLRES_SYNCH) && \
74 defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
75 /* alarm-based timeouts can only be used with all the dependencies satisfied */
76 #define USE_ALARM_TIMEOUT
83 * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
84 * source file are these:
86 * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
87 * that. The host may not be able to resolve IPv6, but we don't really have to
88 * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
91 * CURLRES_ARES - is defined if libcurl is built to use c-ares for
92 * asynchronous name resolves. This can be Windows or *nix.
94 * CURLRES_THREADED - is defined if libcurl is built to run under (native)
95 * Windows, and then the name resolve will be done in a new thread, and the
96 * supported API will be the same as for ares-builds.
98 * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
99 * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
102 * The host*.c sources files are split up like this:
104 * hostip.c - method-independent resolver functions and utility functions
105 * hostasyn.c - functions for asynchronous name resolves
106 * hostsyn.c - functions for synchronous name resolves
107 * hostip4.c - ipv4-specific functions
108 * hostip6.c - ipv6-specific functions
110 * The two asynchronous name resolver backends are implemented in:
111 * asyn-ares.c - functions for ares-using name resolves
112 * asyn-thread.c - functions for threaded name resolves
114 * The hostip.h is the united header file for all this. It defines the
115 * CURLRES_* defines based on the config*.h and setup.h defines.
118 /* These two symbols are for the global DNS cache */
119 static struct curl_hash hostname_cache;
120 static int host_cache_initialized;
122 static void freednsentry(void *freethis);
125 * Curl_global_host_cache_init() initializes and sets up a global DNS cache.
126 * Global DNS cache is general badness. Do not use. This will be removed in
127 * a future version. Use the share interface instead!
129 * Returns a struct curl_hash pointer on success, NULL on failure.
131 struct curl_hash *Curl_global_host_cache_init(void)
134 if(!host_cache_initialized) {
135 rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str,
136 Curl_str_key_compare, freednsentry);
138 host_cache_initialized = 1;
140 return rc?NULL:&hostname_cache;
144 * Destroy and cleanup the global DNS cache
146 void Curl_global_host_cache_dtor(void)
148 if(host_cache_initialized) {
149 Curl_hash_clean(&hostname_cache);
150 host_cache_initialized = 0;
155 * Return # of adresses in a Curl_addrinfo struct
157 int Curl_num_addresses(const Curl_addrinfo *addr)
161 addr = addr->ai_next;
168 * Curl_printable_address() returns a printable version of the 1st address
169 * given in the 'ai' argument. The result will be stored in the buf that is
172 * If the conversion fails, it returns NULL.
175 Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
177 const struct sockaddr_in *sa4;
178 const struct in_addr *ipaddr4;
180 const struct sockaddr_in6 *sa6;
181 const struct in6_addr *ipaddr6;
184 switch (ai->ai_family) {
186 sa4 = (const void *)ai->ai_addr;
187 ipaddr4 = &sa4->sin_addr;
188 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf,
192 sa6 = (const void *)ai->ai_addr;
193 ipaddr6 = &sa6->sin6_addr;
194 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf,
204 * Return a hostcache id string for the providing host + port, to be used by
208 create_hostcache_id(const char *server, int port)
210 /* create and return the new allocated entry */
211 return aprintf("%s:%d", server, port);
214 struct hostcache_prune_data {
220 * This function is set as a callback to be called for every entry in the DNS
221 * cache when we want to prune old unused entries.
223 * Returning non-zero means remove the entry, return 0 to keep it in the
227 hostcache_timestamp_remove(void *datap, void *hc)
229 struct hostcache_prune_data *data =
230 (struct hostcache_prune_data *) datap;
231 struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
233 return (data->now - c->timestamp >= data->cache_timeout);
237 * Prune the DNS cache. This assumes that a lock has already been taken.
240 hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
242 struct hostcache_prune_data user;
244 user.cache_timeout = cache_timeout;
247 Curl_hash_clean_with_criterium(hostcache,
249 hostcache_timestamp_remove);
253 * Library-wide function for pruning the DNS cache. This function takes and
254 * returns the appropriate locks.
256 void Curl_hostcache_prune(struct SessionHandle *data)
260 if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
261 /* cache forever means never prune, and NULL hostcache means
266 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
270 /* Remove outdated and unused entries from the hostcache */
271 hostcache_prune(data->dns.hostcache,
272 data->set.dns_cache_timeout,
276 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
280 * Check if the entry should be pruned. Assumes a locked cache.
283 remove_entry_if_stale(struct SessionHandle *data, struct Curl_dns_entry *dns)
285 struct hostcache_prune_data user;
287 if(!dns || (data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
288 /* cache forever means never prune, and NULL hostcache means
293 user.cache_timeout = data->set.dns_cache_timeout;
295 if(!hostcache_timestamp_remove(&user,dns) )
298 Curl_hash_clean_with_criterium(data->dns.hostcache,
300 hostcache_timestamp_remove);
306 #ifdef HAVE_SIGSETJMP
307 /* Beware this is a global and unique instance. This is used to store the
308 return address that we can jump back to from inside a signal handler. This
309 is not thread-safe stuff. */
310 sigjmp_buf curl_jmpenv;
315 * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
317 * When calling Curl_resolv() has resulted in a response with a returned
318 * address, we call this function to store the information in the dns
321 * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
323 struct Curl_dns_entry *
324 Curl_cache_addr(struct SessionHandle *data,
326 const char *hostname,
331 struct Curl_dns_entry *dns;
332 struct Curl_dns_entry *dns2;
334 /* Create an entry id, based upon the hostname and port */
335 entry_id = create_hostcache_id(hostname, port);
336 /* If we can't create the entry id, fail */
339 entry_len = strlen(entry_id);
341 /* Create a new cache entry */
342 dns = calloc(1, sizeof(struct Curl_dns_entry));
348 dns->inuse = 0; /* init to not used */
349 dns->addr = addr; /* this is the address(es) */
350 time(&dns->timestamp);
351 if(dns->timestamp == 0)
352 dns->timestamp = 1; /* zero indicates that entry isn't in hash table */
354 /* Store the resolved data in our DNS cache. */
355 dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
364 dns->inuse++; /* mark entry as in-use */
366 /* free the allocated entry_id */
373 * Curl_resolv() is the main name resolve function within libcurl. It resolves
374 * a name and returns a pointer to the entry in the 'entry' argument (if one
375 * is provided). This function might return immediately if we're using asynch
376 * resolves. See the return codes.
378 * The cache entry we return will get its 'inuse' counter increased when this
379 * function is used. You MUST call Curl_resolv_unlock() later (when you're
380 * done using this struct) to decrease the counter again.
382 * In debug mode, we specifically test for an interface name "LocalHost"
383 * and resolve "localhost" instead as a means to permit test cases
384 * to connect to a local test server with any host name.
388 * CURLRESOLV_ERROR (-1) = error, no pointer
389 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
390 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
393 int Curl_resolv(struct connectdata *conn,
394 const char *hostname,
396 struct Curl_dns_entry **entry)
398 char *entry_id = NULL;
399 struct Curl_dns_entry *dns = NULL;
401 struct SessionHandle *data = conn->data;
403 int rc = CURLRESOLV_ERROR; /* default to failure */
407 /* Create an entry id, based upon the hostname and port */
408 entry_id = create_hostcache_id(hostname, port);
409 /* If we can't create the entry id, fail */
413 entry_len = strlen(entry_id);
416 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
418 /* See if its already in our dns cache */
419 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
421 /* free the allocated entry_id again */
424 /* See whether the returned entry is stale. Done before we release lock */
425 if(remove_entry_if_stale(data, dns))
426 dns = NULL; /* the memory deallocation is being handled by the hash */
429 dns->inuse++; /* we use it! */
430 rc = CURLRESOLV_RESOLVED;
434 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
437 /* The entry was not in the cache. Resolve it to IP address */
442 /* Check what IP specifics the app has requested and if we can provide it.
443 * If not, bail out. */
444 if(!Curl_ipvalid(conn))
445 return CURLRESOLV_ERROR;
447 /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
448 non-zero value indicating that we need to wait for the response to the
450 addr = Curl_getaddrinfo(conn,
452 (data->set.str[STRING_DEVICE]
453 && !strcmp(data->set.str[STRING_DEVICE],
454 "LocalHost"))?"localhost":
456 hostname, port, &respwait);
460 /* the response to our resolve call will come asynchronously at
461 a later time, good or bad */
462 /* First, check that we haven't received the info by now */
463 result = Curl_resolver_is_resolved(conn, &dns);
464 if(result) /* error detected */
465 return CURLRESOLV_ERROR;
467 rc = CURLRESOLV_RESOLVED; /* pointer provided */
469 rc = CURLRESOLV_PENDING; /* no info yet */
474 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
476 /* we got a response, store it in the cache */
477 dns = Curl_cache_addr(data, addr, hostname, port);
480 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
483 /* returned failure, bail out nicely */
484 Curl_freeaddrinfo(addr);
486 rc = CURLRESOLV_RESOLVED;
495 #ifdef USE_ALARM_TIMEOUT
497 * This signal handler jumps back into the main libcurl code and continues
498 * execution. This effectively causes the remainder of the application to run
499 * within a signal handler which is nonportable and could lead to problems.
502 RETSIGTYPE alarmfunc(int sig)
504 /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
506 siglongjmp(curl_jmpenv, 1);
509 #endif /* USE_ALARM_TIMEOUT */
512 * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
513 * timeout. This function might return immediately if we're using asynch
514 * resolves. See the return codes.
516 * The cache entry we return will get its 'inuse' counter increased when this
517 * function is used. You MUST call Curl_resolv_unlock() later (when you're
518 * done using this struct) to decrease the counter again.
520 * If built with a synchronous resolver and use of signals is not
521 * disabled by the application, then a nonzero timeout will cause a
522 * timeout after the specified number of milliseconds. Otherwise, timeout
527 * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
528 * CURLRESOLV_ERROR (-1) = error, no pointer
529 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
530 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
533 int Curl_resolv_timeout(struct connectdata *conn,
534 const char *hostname,
536 struct Curl_dns_entry **entry,
539 #ifdef USE_ALARM_TIMEOUT
540 #ifdef HAVE_SIGACTION
541 struct sigaction keep_sigact; /* store the old struct here */
542 volatile bool keep_copysig = FALSE; /* wether old sigact has been saved */
543 struct sigaction sigact;
546 void (*keep_sigact)(int); /* store the old handler here */
547 #endif /* HAVE_SIGNAL */
548 #endif /* HAVE_SIGACTION */
549 volatile long timeout;
550 volatile unsigned int prev_alarm = 0;
551 struct SessionHandle *data = conn->data;
552 #endif /* USE_ALARM_TIMEOUT */
558 /* got an already expired timeout */
559 return CURLRESOLV_TIMEDOUT;
561 #ifdef USE_ALARM_TIMEOUT
562 if(data->set.no_signal)
563 /* Ignore the timeout when signals are disabled */
569 /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
570 return Curl_resolv(conn, hostname, port, entry);
573 /* The alarm() function only provides integer second resolution, so if
574 we want to wait less than one second we must bail out already now. */
575 return CURLRESOLV_TIMEDOUT;
577 /*************************************************************
578 * Set signal handler to catch SIGALRM
579 * Store the old value to be able to set it back later!
580 *************************************************************/
581 #ifdef HAVE_SIGACTION
582 sigaction(SIGALRM, NULL, &sigact);
583 keep_sigact = sigact;
584 keep_copysig = TRUE; /* yes, we have a copy */
585 sigact.sa_handler = alarmfunc;
587 /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
588 sigact.sa_flags &= ~SA_RESTART;
590 /* now set the new struct */
591 sigaction(SIGALRM, &sigact, NULL);
592 #else /* HAVE_SIGACTION */
593 /* no sigaction(), revert to the much lamer signal() */
595 keep_sigact = signal(SIGALRM, alarmfunc);
597 #endif /* HAVE_SIGACTION */
599 /* alarm() makes a signal get sent when the timeout fires off, and that
600 will abort system calls */
601 prev_alarm = alarm(curlx_sltoui(timeout/1000L));
603 /* This allows us to time-out from the name resolver, as the timeout
604 will generate a signal and we will siglongjmp() from that here.
605 This technique has problems (see alarmfunc).
606 This should be the last thing we do before calling Curl_resolv(),
607 as otherwise we'd have to worry about variables that get modified
608 before we invoke Curl_resolv() (and thus use "volatile"). */
609 if(sigsetjmp(curl_jmpenv, 1)) {
610 /* this is coming from a siglongjmp() after an alarm signal */
611 failf(data, "name lookup timed out");
612 rc = CURLRESOLV_ERROR;
617 #ifndef CURLRES_ASYNCH
619 infof(conn->data, "timeout on name lookup is not supported\n");
621 (void)timeoutms; /* timeoutms not used with an async resolver */
623 #endif /* USE_ALARM_TIMEOUT */
625 /* Perform the actual name resolution. This might be interrupted by an
626 * alarm if it takes too long.
628 rc = Curl_resolv(conn, hostname, port, entry);
630 #ifdef USE_ALARM_TIMEOUT
634 /* deactivate a possibly active alarm before uninstalling the handler */
637 #ifdef HAVE_SIGACTION
639 /* we got a struct as it looked before, now put that one back nice
641 sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
645 /* restore the previous SIGALRM handler */
646 signal(SIGALRM, keep_sigact);
648 #endif /* HAVE_SIGACTION */
650 /* switch back the alarm() to either zero or to what it was before minus
651 the time we spent until now! */
653 /* there was an alarm() set before us, now put it back */
654 unsigned long elapsed_ms = Curl_tvdiff(Curl_tvnow(), conn->created);
656 /* the alarm period is counted in even number of seconds */
657 unsigned long alarm_set = prev_alarm - elapsed_ms/1000;
660 ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
661 /* if the alarm time-left reached zero or turned "negative" (counted
662 with unsigned values), we should fire off a SIGALRM here, but we
663 won't, and zero would be to switch it off so we never set it to
666 rc = CURLRESOLV_TIMEDOUT;
667 failf(data, "Previous alarm fired off!");
670 alarm((unsigned int)alarm_set);
672 #endif /* USE_ALARM_TIMEOUT */
678 * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
679 * made, the struct may be destroyed due to pruning. It is important that only
680 * one unlock is made for each Curl_resolv() call.
682 void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns)
684 DEBUGASSERT(dns && (dns->inuse>0));
687 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
690 /* only free if nobody is using AND it is not in hostcache (timestamp ==
692 if(dns->inuse == 0 && dns->timestamp == 0) {
693 Curl_freeaddrinfo(dns->addr);
698 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
702 * File-internal: free a cache dns entry.
704 static void freednsentry(void *freethis)
706 struct Curl_dns_entry *p = (struct Curl_dns_entry *) freethis;
708 /* mark the entry as not in hostcache */
711 Curl_freeaddrinfo(p->addr);
717 * Curl_mk_dnscache() creates a new DNS cache and returns the handle for it.
719 struct curl_hash *Curl_mk_dnscache(void)
721 return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);