1 /***************************************************************************
3 * Project ___| | | | _ \| |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
8 * Copyright (C) 1998 - 2009, 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.
22 ***************************************************************************/
28 #ifdef HAVE_SYS_SOCKET_H
29 #include <sys/socket.h>
31 #ifdef HAVE_NETINET_IN_H
32 #include <netinet/in.h>
37 #ifdef HAVE_ARPA_INET_H
38 #include <arpa/inet.h>
41 #include <stdlib.h> /* required for free() prototypes */
44 #include <unistd.h> /* for the close() proto */
70 #include "inet_ntop.h"
72 #define _MPRINTF_REPLACE /* use our functions only */
73 #include <curl/mprintf.h>
75 #include "curl_memory.h"
76 /* The last #include file should be: */
79 #if defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP) \
81 /* alarm-based timeouts can only be used with all the dependencies satisfied */
82 #define USE_ALARM_TIMEOUT
89 * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
90 * source file are these:
92 * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
93 * that. The host may not be able to resolve IPv6, but we don't really have to
94 * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
97 * CURLRES_ARES - is defined if libcurl is built to use c-ares for
98 * asynchronous name resolves. This can be Windows or *nix.
100 * CURLRES_THREADED - is defined if libcurl is built to run under (native)
101 * Windows, and then the name resolve will be done in a new thread, and the
102 * supported API will be the same as for ares-builds.
104 * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
105 * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
108 * The host*.c sources files are split up like this:
110 * hostip.c - method-independent resolver functions and utility functions
111 * hostasyn.c - functions for asynchronous name resolves
112 * hostsyn.c - functions for synchronous name resolves
113 * hostares.c - functions for ares-using name resolves
114 * hostthre.c - functions for threaded name resolves
115 * hostip4.c - ipv4-specific functions
116 * hostip6.c - ipv6-specific functions
118 * The hostip.h is the united header file for all this. It defines the
119 * CURLRES_* defines based on the config*.h and setup.h defines.
122 /* These two symbols are for the global DNS cache */
123 static struct curl_hash hostname_cache;
124 static int host_cache_initialized;
126 static void freednsentry(void *freethis);
129 * Curl_global_host_cache_init() initializes and sets up a global DNS cache.
130 * Global DNS cache is general badness. Do not use. This will be removed in
131 * a future version. Use the share interface instead!
133 * Returns a struct curl_hash pointer on success, NULL on failure.
135 struct curl_hash *Curl_global_host_cache_init(void)
138 if(!host_cache_initialized) {
139 rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str,
140 Curl_str_key_compare, freednsentry);
142 host_cache_initialized = 1;
144 return rc?NULL:&hostname_cache;
148 * Destroy and cleanup the global DNS cache
150 void Curl_global_host_cache_dtor(void)
152 if(host_cache_initialized) {
153 Curl_hash_clean(&hostname_cache);
154 host_cache_initialized = 0;
159 * Return # of adresses in a Curl_addrinfo struct
161 int Curl_num_addresses(const Curl_addrinfo *addr)
165 addr = addr->ai_next;
172 * Curl_printable_address() returns a printable version of the 1st address
173 * given in the 'ai' argument. The result will be stored in the buf that is
176 * If the conversion fails, it returns NULL.
179 Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
181 const struct sockaddr_in *sa4;
182 const struct in_addr *ipaddr4;
184 const struct sockaddr_in6 *sa6;
185 const struct in6_addr *ipaddr6;
188 switch (ai->ai_family) {
190 sa4 = (const void *)ai->ai_addr;
191 ipaddr4 = &sa4->sin_addr;
192 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf, bufsize);
195 sa6 = (const void *)ai->ai_addr;
196 ipaddr6 = &sa6->sin6_addr;
197 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf, bufsize);
206 * Return a hostcache id string for the providing host + port, to be used by
210 create_hostcache_id(const char *server, int port)
212 /* create and return the new allocated entry */
213 return aprintf("%s:%d", server, port);
216 struct hostcache_prune_data {
222 * This function is set as a callback to be called for every entry in the DNS
223 * cache when we want to prune old unused entries.
225 * Returning non-zero means remove the entry, return 0 to keep it in the
229 hostcache_timestamp_remove(void *datap, void *hc)
231 struct hostcache_prune_data *data =
232 (struct hostcache_prune_data *) datap;
233 struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
235 return (data->now - c->timestamp >= data->cache_timeout);
239 * Prune the DNS cache. This assumes that a lock has already been taken.
242 hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
244 struct hostcache_prune_data user;
246 user.cache_timeout = cache_timeout;
249 Curl_hash_clean_with_criterium(hostcache,
251 hostcache_timestamp_remove);
255 * Library-wide function for pruning the DNS cache. This function takes and
256 * returns the appropriate locks.
258 void Curl_hostcache_prune(struct SessionHandle *data)
262 if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
263 /* cache forever means never prune, and NULL hostcache means
268 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
272 /* Remove outdated and unused entries from the hostcache */
273 hostcache_prune(data->dns.hostcache,
274 data->set.dns_cache_timeout,
278 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
282 * Check if the entry should be pruned. Assumes a locked cache.
285 remove_entry_if_stale(struct SessionHandle *data, struct Curl_dns_entry *dns)
287 struct hostcache_prune_data user;
289 if( !dns || (data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
290 /* cache forever means never prune, and NULL hostcache means
295 user.cache_timeout = data->set.dns_cache_timeout;
297 if( !hostcache_timestamp_remove(&user,dns) )
300 Curl_hash_clean_with_criterium(data->dns.hostcache,
302 hostcache_timestamp_remove);
308 #ifdef HAVE_SIGSETJMP
309 /* Beware this is a global and unique instance. This is used to store the
310 return address that we can jump back to from inside a signal handler. This
311 is not thread-safe stuff. */
312 sigjmp_buf curl_jmpenv;
317 * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
319 * When calling Curl_resolv() has resulted in a response with a returned
320 * address, we call this function to store the information in the dns
323 * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
325 struct Curl_dns_entry *
326 Curl_cache_addr(struct SessionHandle *data,
328 const char *hostname,
333 struct Curl_dns_entry *dns;
334 struct Curl_dns_entry *dns2;
336 /* Create an entry id, based upon the hostname and port */
337 entry_id = create_hostcache_id(hostname, port);
338 /* If we can't create the entry id, fail */
341 entry_len = strlen(entry_id);
343 /* Create a new cache entry */
344 dns = calloc(1, sizeof(struct Curl_dns_entry));
350 dns->inuse = 0; /* init to not used */
351 dns->addr = addr; /* this is the address(es) */
352 time(&dns->timestamp);
353 if(dns->timestamp == 0)
354 dns->timestamp = 1; /* zero indicates that entry isn't in hash table */
356 /* Store the resolved data in our DNS cache. */
357 dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
366 dns->inuse++; /* mark entry as in-use */
368 /* free the allocated entry_id again */
375 * Curl_resolv() is the main name resolve function within libcurl. It resolves
376 * a name and returns a pointer to the entry in the 'entry' argument (if one
377 * is provided). This function might return immediately if we're using asynch
378 * resolves. See the return codes.
380 * The cache entry we return will get its 'inuse' counter increased when this
381 * function is used. You MUST call Curl_resolv_unlock() later (when you're
382 * done using this struct) to decrease the counter again.
384 * In debug mode, we specifically test for an interface name "LocalHost"
385 * and resolve "localhost" instead as a means to permit test cases
386 * to connect to a local test server with any host name.
390 * CURLRESOLV_ERROR (-1) = error, no pointer
391 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
392 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
395 int Curl_resolv(struct connectdata *conn,
396 const char *hostname,
398 struct Curl_dns_entry **entry)
400 char *entry_id = NULL;
401 struct Curl_dns_entry *dns = NULL;
403 struct SessionHandle *data = conn->data;
405 int rc = CURLRESOLV_ERROR; /* default to failure */
409 /* Create an entry id, based upon the hostname and port */
410 entry_id = create_hostcache_id(hostname, port);
411 /* If we can't create the entry id, fail */
415 entry_len = strlen(entry_id);
418 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
420 /* See if its already in our dns cache */
421 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
423 /* See whether the returned entry is stale. Done before we release lock */
424 if( remove_entry_if_stale(data, dns) )
425 dns = NULL; /* the memory deallocation is being handled by the hash */
428 dns->inuse++; /* we use it! */
429 rc = CURLRESOLV_RESOLVED;
433 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
435 /* free the allocated entry_id again */
439 /* The entry was not in the cache. Resolve it to IP address */
444 /* Check what IP specifics the app has requested and if we can provide it.
445 * If not, bail out. */
446 if(!Curl_ipvalid(data))
447 return CURLRESOLV_ERROR;
449 /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
450 non-zero value indicating that we need to wait for the response to the
452 addr = Curl_getaddrinfo(conn,
454 (data->set.str[STRING_DEVICE]
455 && !strcmp(data->set.str[STRING_DEVICE],
456 "LocalHost"))?"localhost":
458 hostname, port, &respwait);
462 /* the response to our resolve call will come asynchronously at
463 a later time, good or bad */
464 /* First, check that we haven't received the info by now */
465 result = Curl_is_resolved(conn, &dns);
466 if(result) /* error detected */
467 return CURLRESOLV_ERROR;
469 rc = CURLRESOLV_RESOLVED; /* pointer provided */
471 rc = CURLRESOLV_PENDING; /* no info yet */
476 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
478 /* we got a response, store it in the cache */
479 dns = Curl_cache_addr(data, addr, hostname, port);
482 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
485 /* returned failure, bail out nicely */
486 Curl_freeaddrinfo(addr);
488 rc = CURLRESOLV_RESOLVED;
497 #ifdef USE_ALARM_TIMEOUT
499 * This signal handler jumps back into the main libcurl code and continues
500 * execution. This effectively causes the remainder of the application to run
501 * within a signal handler which is nonportable and could lead to problems.
504 RETSIGTYPE alarmfunc(int sig)
506 /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
508 siglongjmp(curl_jmpenv, 1);
511 #endif /* USE_ALARM_TIMEOUT */
514 * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
515 * timeout. This function might return immediately if we're using asynch
516 * resolves. See the return codes.
518 * The cache entry we return will get its 'inuse' counter increased when this
519 * function is used. You MUST call Curl_resolv_unlock() later (when you're
520 * done using this struct) to decrease the counter again.
522 * If built with a synchronous resolver and use of signals is not
523 * disabled by the application, then a nonzero timeout will cause a
524 * timeout after the specified number of milliseconds. Otherwise, timeout
529 * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
530 * CURLRESOLV_ERROR (-1) = error, no pointer
531 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
532 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
535 int Curl_resolv_timeout(struct connectdata *conn,
536 const char *hostname,
538 struct Curl_dns_entry **entry,
541 #ifdef USE_ALARM_TIMEOUT
542 #ifdef HAVE_SIGACTION
543 struct sigaction keep_sigact; /* store the old struct here */
544 bool keep_copysig=FALSE; /* did copy it? */
545 struct sigaction sigact;
548 void (*keep_sigact)(int); /* store the old handler here */
549 #endif /* HAVE_SIGNAL */
550 #endif /* HAVE_SIGACTION */
551 volatile long timeout;
552 unsigned int prev_alarm=0;
553 struct SessionHandle *data = conn->data;
554 #endif /* USE_ALARM_TIMEOUT */
559 #ifdef USE_ALARM_TIMEOUT
560 if (data->set.no_signal)
561 /* Ignore the timeout when signals are disabled */
566 if(timeout && timeout < 1000)
567 /* The alarm() function only provides integer second resolution, so if
568 we want to wait less than one second we must bail out already now. */
569 return CURLRESOLV_TIMEDOUT;
572 /* This allows us to time-out from the name resolver, as the timeout
573 will generate a signal and we will siglongjmp() from that here.
574 This technique has problems (see alarmfunc). */
575 if(sigsetjmp(curl_jmpenv, 1)) {
576 /* this is coming from a siglongjmp() after an alarm signal */
577 failf(data, "name lookup timed out");
578 return CURLRESOLV_ERROR;
581 /*************************************************************
582 * Set signal handler to catch SIGALRM
583 * Store the old value to be able to set it back later!
584 *************************************************************/
585 #ifdef HAVE_SIGACTION
586 sigaction(SIGALRM, NULL, &sigact);
587 keep_sigact = sigact;
588 keep_copysig = TRUE; /* yes, we have a copy */
589 sigact.sa_handler = alarmfunc;
591 /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
592 sigact.sa_flags &= ~SA_RESTART;
594 /* now set the new struct */
595 sigaction(SIGALRM, &sigact, NULL);
596 #else /* HAVE_SIGACTION */
597 /* no sigaction(), revert to the much lamer signal() */
599 keep_sigact = signal(SIGALRM, alarmfunc);
601 #endif /* HAVE_SIGACTION */
603 /* alarm() makes a signal get sent when the timeout fires off, and that
604 will abort system calls */
605 prev_alarm = alarm((unsigned int) (timeout/1000L));
609 #ifndef CURLRES_ASYNCH
611 infof(conn->data, "timeout on name lookup is not supported\n");
613 (void)timeoutms; /* timeoutms not used with an async resolver */
615 #endif /* USE_ALARM_TIMEOUT */
617 /* Perform the actual name resolution. This might be interrupted by an
618 * alarm if it takes too long.
620 rc = Curl_resolv(conn, hostname, port, entry);
622 #ifdef USE_ALARM_TIMEOUT
625 #ifdef HAVE_SIGACTION
627 /* we got a struct as it looked before, now put that one back nice
629 sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
633 /* restore the previous SIGALRM handler */
634 signal(SIGALRM, keep_sigact);
636 #endif /* HAVE_SIGACTION */
638 /* switch back the alarm() to either zero or to what it was before minus
639 the time we spent until now! */
641 /* there was an alarm() set before us, now put it back */
642 unsigned long elapsed_ms = Curl_tvdiff(Curl_tvnow(), conn->created);
644 /* the alarm period is counted in even number of seconds */
645 unsigned long alarm_set = prev_alarm - elapsed_ms/1000;
648 ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
649 /* if the alarm time-left reached zero or turned "negative" (counted
650 with unsigned values), we should fire off a SIGALRM here, but we
651 won't, and zero would be to switch it off so we never set it to
654 rc = CURLRESOLV_TIMEDOUT;
655 failf(data, "Previous alarm fired off!");
658 alarm((unsigned int)alarm_set);
661 alarm(0); /* just shut it off */
663 #endif /* USE_ALARM_TIMEOUT */
669 * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
670 * made, the struct may be destroyed due to pruning. It is important that only
671 * one unlock is made for each Curl_resolv() call.
673 void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns)
675 DEBUGASSERT(dns && (dns->inuse>0));
678 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
681 /* only free if nobody is using AND it is not in hostcache (timestamp ==
683 if (dns->inuse == 0 && dns->timestamp == 0) {
684 Curl_freeaddrinfo(dns->addr);
689 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
693 * File-internal: free a cache dns entry.
695 static void freednsentry(void *freethis)
697 struct Curl_dns_entry *p = (struct Curl_dns_entry *) freethis;
699 /* mark the entry as not in hostcache */
702 Curl_freeaddrinfo(p->addr);
708 * Curl_mk_dnscache() creates a new DNS cache and returns the handle for it.
710 struct curl_hash *Curl_mk_dnscache(void)
712 return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);
715 #ifdef CURLRES_ADDRINFO_COPY
717 /* align on even 64bit boundaries */
718 #define MEMALIGN(x) ((x)+(8-(((unsigned long)(x))&0x7)))
721 * Curl_addrinfo_copy() performs a "deep" copy of a hostent into a buffer and
722 * returns a pointer to the malloc()ed copy. You need to call free() on the
723 * returned buffer when you're done with it.
725 Curl_addrinfo *Curl_addrinfo_copy(const void *org, int port)
727 const struct hostent *orig = org;
729 return Curl_he2ai(orig, port);
731 #endif /* CURLRES_ADDRINFO_COPY */