1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
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 https://curl.haxx.se/docs/copyright.html.
13 *
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.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 ***************************************************************************/
22
23 #include "curl_setup.h"
24
25 #ifdef HAVE_NETINET_IN_H
26 #include <netinet/in.h>
27 #endif
28 #ifdef HAVE_NETDB_H
29 #include <netdb.h>
30 #endif
31 #ifdef HAVE_ARPA_INET_H
32 #include <arpa/inet.h>
33 #endif
34 #ifdef __VMS
35 #include <in.h>
36 #include <inet.h>
37 #endif
38
39 #ifdef HAVE_SETJMP_H
40 #include <setjmp.h>
41 #endif
42 #ifdef HAVE_SIGNAL_H
43 #include <signal.h>
44 #endif
45
46 #ifdef HAVE_PROCESS_H
47 #include <process.h>
48 #endif
49
50 #include "urldata.h"
51 #include "sendf.h"
52 #include "hostip.h"
53 #include "hash.h"
54 #include "share.h"
55 #include "strerror.h"
56 #include "url.h"
57 #include "inet_ntop.h"
58 #include "warnless.h"
59 /* The last 3 #include files should be in this order */
60 #include "curl_printf.h"
61 #include "curl_memory.h"
62 #include "memdebug.h"
63
64 #if defined(CURLRES_SYNCH) && \
65 defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
66 /* alarm-based timeouts can only be used with all the dependencies satisfied */
67 #define USE_ALARM_TIMEOUT
68 #endif
69
70 /*
71 * hostip.c explained
72 * ==================
73 *
74 * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
75 * source file are these:
76 *
77 * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
78 * that. The host may not be able to resolve IPv6, but we don't really have to
79 * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
80 * defined.
81 *
82 * CURLRES_ARES - is defined if libcurl is built to use c-ares for
83 * asynchronous name resolves. This can be Windows or *nix.
84 *
85 * CURLRES_THREADED - is defined if libcurl is built to run under (native)
86 * Windows, and then the name resolve will be done in a new thread, and the
87 * supported API will be the same as for ares-builds.
88 *
89 * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
90 * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
91 * defined.
92 *
93 * The host*.c sources files are split up like this:
94 *
95 * hostip.c - method-independent resolver functions and utility functions
96 * hostasyn.c - functions for asynchronous name resolves
97 * hostsyn.c - functions for synchronous name resolves
98 * hostip4.c - IPv4 specific functions
99 * hostip6.c - IPv6 specific functions
100 *
101 * The two asynchronous name resolver backends are implemented in:
102 * asyn-ares.c - functions for ares-using name resolves
103 * asyn-thread.c - functions for threaded name resolves
104
105 * The hostip.h is the united header file for all this. It defines the
106 * CURLRES_* defines based on the config*.h and curl_setup.h defines.
107 */
108
109 /* These two symbols are for the global DNS cache */
110 static struct curl_hash hostname_cache;
111 static int host_cache_initialized;
112
113 static void freednsentry(void *freethis);
114
115 /*
116 * Curl_global_host_cache_init() initializes and sets up a global DNS cache.
117 * Global DNS cache is general badness. Do not use. This will be removed in
118 * a future version. Use the share interface instead!
119 *
120 * Returns a struct curl_hash pointer on success, NULL on failure.
121 */
Curl_global_host_cache_init(void)122 struct curl_hash *Curl_global_host_cache_init(void)
123 {
124 int rc = 0;
125 if(!host_cache_initialized) {
126 rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str,
127 Curl_str_key_compare, freednsentry);
128 if(!rc)
129 host_cache_initialized = 1;
130 }
131 return rc?NULL:&hostname_cache;
132 }
133
134 /*
135 * Destroy and cleanup the global DNS cache
136 */
Curl_global_host_cache_dtor(void)137 void Curl_global_host_cache_dtor(void)
138 {
139 if(host_cache_initialized) {
140 Curl_hash_destroy(&hostname_cache);
141 host_cache_initialized = 0;
142 }
143 }
144
145 /*
146 * Return # of adresses in a Curl_addrinfo struct
147 */
Curl_num_addresses(const Curl_addrinfo * addr)148 int Curl_num_addresses(const Curl_addrinfo *addr)
149 {
150 int i = 0;
151 while(addr) {
152 addr = addr->ai_next;
153 i++;
154 }
155 return i;
156 }
157
158 /*
159 * Curl_printable_address() returns a printable version of the 1st address
160 * given in the 'ai' argument. The result will be stored in the buf that is
161 * bufsize bytes big.
162 *
163 * If the conversion fails, it returns NULL.
164 */
165 const char *
Curl_printable_address(const Curl_addrinfo * ai,char * buf,size_t bufsize)166 Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
167 {
168 const struct sockaddr_in *sa4;
169 const struct in_addr *ipaddr4;
170 #ifdef ENABLE_IPV6
171 const struct sockaddr_in6 *sa6;
172 const struct in6_addr *ipaddr6;
173 #endif
174
175 switch (ai->ai_family) {
176 case AF_INET:
177 sa4 = (const void *)ai->ai_addr;
178 ipaddr4 = &sa4->sin_addr;
179 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf,
180 bufsize);
181 #ifdef ENABLE_IPV6
182 case AF_INET6:
183 sa6 = (const void *)ai->ai_addr;
184 ipaddr6 = &sa6->sin6_addr;
185 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf,
186 bufsize);
187 #endif
188 default:
189 break;
190 }
191 return NULL;
192 }
193
194 /*
195 * Return a hostcache id string for the provided host + port, to be used by
196 * the DNS caching.
197 */
198 static char *
create_hostcache_id(const char * name,int port)199 create_hostcache_id(const char *name, int port)
200 {
201 /* create and return the new allocated entry */
202 char *id = aprintf("%s:%d", name, port);
203 char *ptr = id;
204 if(ptr) {
205 /* lower case the name part */
206 while(*ptr && (*ptr != ':')) {
207 *ptr = (char)TOLOWER(*ptr);
208 ptr++;
209 }
210 }
211 return id;
212 }
213
214 struct hostcache_prune_data {
215 long cache_timeout;
216 time_t now;
217 };
218
219 /*
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.
222 *
223 * Returning non-zero means remove the entry, return 0 to keep it in the
224 * cache.
225 */
226 static int
hostcache_timestamp_remove(void * datap,void * hc)227 hostcache_timestamp_remove(void *datap, void *hc)
228 {
229 struct hostcache_prune_data *data =
230 (struct hostcache_prune_data *) datap;
231 struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
232
233 return (0 != c->timestamp)
234 && (data->now - c->timestamp >= data->cache_timeout);
235 }
236
237 /*
238 * Prune the DNS cache. This assumes that a lock has already been taken.
239 */
240 static void
hostcache_prune(struct curl_hash * hostcache,long cache_timeout,time_t now)241 hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
242 {
243 struct hostcache_prune_data user;
244
245 user.cache_timeout = cache_timeout;
246 user.now = now;
247
248 Curl_hash_clean_with_criterium(hostcache,
249 (void *) &user,
250 hostcache_timestamp_remove);
251 }
252
253 /*
254 * Library-wide function for pruning the DNS cache. This function takes and
255 * returns the appropriate locks.
256 */
Curl_hostcache_prune(struct Curl_easy * data)257 void Curl_hostcache_prune(struct Curl_easy *data)
258 {
259 time_t now;
260
261 if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
262 /* cache forever means never prune, and NULL hostcache means
263 we can't do it */
264 return;
265
266 if(data->share)
267 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
268
269 time(&now);
270
271 /* Remove outdated and unused entries from the hostcache */
272 hostcache_prune(data->dns.hostcache,
273 data->set.dns_cache_timeout,
274 now);
275
276 if(data->share)
277 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
278 }
279
280 #ifdef HAVE_SIGSETJMP
281 /* Beware this is a global and unique instance. This is used to store the
282 return address that we can jump back to from inside a signal handler. This
283 is not thread-safe stuff. */
284 sigjmp_buf curl_jmpenv;
285 #endif
286
287 /* lookup address, returns entry if found and not stale */
288 static struct Curl_dns_entry *
fetch_addr(struct connectdata * conn,const char * hostname,int port)289 fetch_addr(struct connectdata *conn,
290 const char *hostname,
291 int port)
292 {
293 char *entry_id = NULL;
294 struct Curl_dns_entry *dns = NULL;
295 size_t entry_len;
296 struct Curl_easy *data = conn->data;
297
298 /* Create an entry id, based upon the hostname and port */
299 entry_id = create_hostcache_id(hostname, port);
300 /* If we can't create the entry id, fail */
301 if(!entry_id)
302 return dns;
303
304 entry_len = strlen(entry_id);
305
306 /* See if its already in our dns cache */
307 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
308
309 if(dns && (data->set.dns_cache_timeout != -1)) {
310 /* See whether the returned entry is stale. Done before we release lock */
311 struct hostcache_prune_data user;
312
313 time(&user.now);
314 user.cache_timeout = data->set.dns_cache_timeout;
315
316 if(hostcache_timestamp_remove(&user, dns)) {
317 infof(data, "Hostname in DNS cache was stale, zapped\n");
318 dns = NULL; /* the memory deallocation is being handled by the hash */
319 Curl_hash_delete(data->dns.hostcache, entry_id, entry_len+1);
320 }
321 }
322
323 /* free the allocated entry_id again */
324 free(entry_id);
325
326 return dns;
327 }
328
329 /*
330 * Curl_fetch_addr() fetches a 'Curl_dns_entry' already in the DNS cache.
331 *
332 * Curl_resolv() checks initially and multi_runsingle() checks each time
333 * it discovers the handle in the state WAITRESOLVE whether the hostname
334 * has already been resolved and the address has already been stored in
335 * the DNS cache. This short circuits waiting for a lot of pending
336 * lookups for the same hostname requested by different handles.
337 *
338 * Returns the Curl_dns_entry entry pointer or NULL if not in the cache.
339 *
340 * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after
341 * use, or we'll leak memory!
342 */
343 struct Curl_dns_entry *
Curl_fetch_addr(struct connectdata * conn,const char * hostname,int port)344 Curl_fetch_addr(struct connectdata *conn,
345 const char *hostname,
346 int port)
347 {
348 struct Curl_easy *data = conn->data;
349 struct Curl_dns_entry *dns = NULL;
350
351 if(data->share)
352 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
353
354 dns = fetch_addr(conn, hostname, port);
355
356 if(dns)
357 dns->inuse++; /* we use it! */
358
359 if(data->share)
360 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
361
362 return dns;
363 }
364
365 /*
366 * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
367 *
368 * When calling Curl_resolv() has resulted in a response with a returned
369 * address, we call this function to store the information in the dns
370 * cache etc
371 *
372 * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
373 */
374 struct Curl_dns_entry *
Curl_cache_addr(struct Curl_easy * data,Curl_addrinfo * addr,const char * hostname,int port)375 Curl_cache_addr(struct Curl_easy *data,
376 Curl_addrinfo *addr,
377 const char *hostname,
378 int port)
379 {
380 char *entry_id;
381 size_t entry_len;
382 struct Curl_dns_entry *dns;
383 struct Curl_dns_entry *dns2;
384
385 /* Create an entry id, based upon the hostname and port */
386 entry_id = create_hostcache_id(hostname, port);
387 /* If we can't create the entry id, fail */
388 if(!entry_id)
389 return NULL;
390 entry_len = strlen(entry_id);
391
392 /* Create a new cache entry */
393 dns = calloc(1, sizeof(struct Curl_dns_entry));
394 if(!dns) {
395 free(entry_id);
396 return NULL;
397 }
398
399 dns->inuse = 1; /* the cache has the first reference */
400 dns->addr = addr; /* this is the address(es) */
401 time(&dns->timestamp);
402 if(dns->timestamp == 0)
403 dns->timestamp = 1; /* zero indicates CURLOPT_RESOLVE entry */
404
405 /* Store the resolved data in our DNS cache. */
406 dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
407 (void *)dns);
408 if(!dns2) {
409 free(dns);
410 free(entry_id);
411 return NULL;
412 }
413
414 dns = dns2;
415 dns->inuse++; /* mark entry as in-use */
416
417 /* free the allocated entry_id */
418 free(entry_id);
419
420 return dns;
421 }
422
423 /*
424 * Curl_resolv() is the main name resolve function within libcurl. It resolves
425 * a name and returns a pointer to the entry in the 'entry' argument (if one
426 * is provided). This function might return immediately if we're using asynch
427 * resolves. See the return codes.
428 *
429 * The cache entry we return will get its 'inuse' counter increased when this
430 * function is used. You MUST call Curl_resolv_unlock() later (when you're
431 * done using this struct) to decrease the counter again.
432 *
433 * In debug mode, we specifically test for an interface name "LocalHost"
434 * and resolve "localhost" instead as a means to permit test cases
435 * to connect to a local test server with any host name.
436 *
437 * Return codes:
438 *
439 * CURLRESOLV_ERROR (-1) = error, no pointer
440 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
441 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
442 */
443
Curl_resolv(struct connectdata * conn,const char * hostname,int port,struct Curl_dns_entry ** entry)444 int Curl_resolv(struct connectdata *conn,
445 const char *hostname,
446 int port,
447 struct Curl_dns_entry **entry)
448 {
449 struct Curl_dns_entry *dns = NULL;
450 struct Curl_easy *data = conn->data;
451 CURLcode result;
452 int rc = CURLRESOLV_ERROR; /* default to failure */
453
454 *entry = NULL;
455
456 if(data->share)
457 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
458
459 dns = fetch_addr(conn, hostname, port);
460
461 if(dns) {
462 infof(data, "Hostname %s was found in DNS cache\n", hostname);
463 dns->inuse++; /* we use it! */
464 rc = CURLRESOLV_RESOLVED;
465 }
466
467 if(data->share)
468 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
469
470 if(!dns) {
471 /* The entry was not in the cache. Resolve it to IP address */
472
473 Curl_addrinfo *addr;
474 int respwait;
475
476 /* Check what IP specifics the app has requested and if we can provide it.
477 * If not, bail out. */
478 if(!Curl_ipvalid(conn))
479 return CURLRESOLV_ERROR;
480
481 /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
482 non-zero value indicating that we need to wait for the response to the
483 resolve call */
484 addr = Curl_getaddrinfo(conn,
485 #ifdef DEBUGBUILD
486 (data->set.str[STRING_DEVICE]
487 && !strcmp(data->set.str[STRING_DEVICE],
488 "LocalHost"))?"localhost":
489 #endif
490 hostname, port, &respwait);
491
492 if(!addr) {
493 if(respwait) {
494 /* the response to our resolve call will come asynchronously at
495 a later time, good or bad */
496 /* First, check that we haven't received the info by now */
497 result = Curl_resolver_is_resolved(conn, &dns);
498 if(result) /* error detected */
499 return CURLRESOLV_ERROR;
500 if(dns)
501 rc = CURLRESOLV_RESOLVED; /* pointer provided */
502 else
503 rc = CURLRESOLV_PENDING; /* no info yet */
504 }
505 }
506 else {
507 if(data->share)
508 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
509
510 /* we got a response, store it in the cache */
511 dns = Curl_cache_addr(data, addr, hostname, port);
512
513 if(data->share)
514 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
515
516 if(!dns)
517 /* returned failure, bail out nicely */
518 Curl_freeaddrinfo(addr);
519 else
520 rc = CURLRESOLV_RESOLVED;
521 }
522 }
523
524 *entry = dns;
525
526 return rc;
527 }
528
529 #ifdef USE_ALARM_TIMEOUT
530 /*
531 * This signal handler jumps back into the main libcurl code and continues
532 * execution. This effectively causes the remainder of the application to run
533 * within a signal handler which is nonportable and could lead to problems.
534 */
535 static
alarmfunc(int sig)536 RETSIGTYPE alarmfunc(int sig)
537 {
538 /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
539 (void)sig;
540 siglongjmp(curl_jmpenv, 1);
541 return;
542 }
543 #endif /* USE_ALARM_TIMEOUT */
544
545 /*
546 * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
547 * timeout. This function might return immediately if we're using asynch
548 * resolves. See the return codes.
549 *
550 * The cache entry we return will get its 'inuse' counter increased when this
551 * function is used. You MUST call Curl_resolv_unlock() later (when you're
552 * done using this struct) to decrease the counter again.
553 *
554 * If built with a synchronous resolver and use of signals is not
555 * disabled by the application, then a nonzero timeout will cause a
556 * timeout after the specified number of milliseconds. Otherwise, timeout
557 * is ignored.
558 *
559 * Return codes:
560 *
561 * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
562 * CURLRESOLV_ERROR (-1) = error, no pointer
563 * CURLRESOLV_RESOLVED (0) = OK, pointer provided
564 * CURLRESOLV_PENDING (1) = waiting for response, no pointer
565 */
566
Curl_resolv_timeout(struct connectdata * conn,const char * hostname,int port,struct Curl_dns_entry ** entry,time_t timeoutms)567 int Curl_resolv_timeout(struct connectdata *conn,
568 const char *hostname,
569 int port,
570 struct Curl_dns_entry **entry,
571 time_t timeoutms)
572 {
573 #ifdef USE_ALARM_TIMEOUT
574 #ifdef HAVE_SIGACTION
575 struct sigaction keep_sigact; /* store the old struct here */
576 volatile bool keep_copysig = FALSE; /* wether old sigact has been saved */
577 struct sigaction sigact;
578 #else
579 #ifdef HAVE_SIGNAL
580 void (*keep_sigact)(int); /* store the old handler here */
581 #endif /* HAVE_SIGNAL */
582 #endif /* HAVE_SIGACTION */
583 volatile long timeout;
584 volatile unsigned int prev_alarm = 0;
585 struct Curl_easy *data = conn->data;
586 #endif /* USE_ALARM_TIMEOUT */
587 int rc;
588
589 *entry = NULL;
590
591 if(timeoutms < 0)
592 /* got an already expired timeout */
593 return CURLRESOLV_TIMEDOUT;
594
595 #ifdef USE_ALARM_TIMEOUT
596 if(data->set.no_signal)
597 /* Ignore the timeout when signals are disabled */
598 timeout = 0;
599 else
600 timeout = timeoutms;
601
602 if(!timeout)
603 /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
604 return Curl_resolv(conn, hostname, port, entry);
605
606 if(timeout < 1000) {
607 /* The alarm() function only provides integer second resolution, so if
608 we want to wait less than one second we must bail out already now. */
609 failf(data,
610 "remaining timeout of %ld too small to resolve via SIGALRM method",
611 timeout);
612 return CURLRESOLV_TIMEDOUT;
613 }
614 /* This allows us to time-out from the name resolver, as the timeout
615 will generate a signal and we will siglongjmp() from that here.
616 This technique has problems (see alarmfunc).
617 This should be the last thing we do before calling Curl_resolv(),
618 as otherwise we'd have to worry about variables that get modified
619 before we invoke Curl_resolv() (and thus use "volatile"). */
620 if(sigsetjmp(curl_jmpenv, 1)) {
621 /* this is coming from a siglongjmp() after an alarm signal */
622 failf(data, "name lookup timed out");
623 rc = CURLRESOLV_ERROR;
624 goto clean_up;
625 }
626 else {
627 /*************************************************************
628 * Set signal handler to catch SIGALRM
629 * Store the old value to be able to set it back later!
630 *************************************************************/
631 #ifdef HAVE_SIGACTION
632 sigaction(SIGALRM, NULL, &sigact);
633 keep_sigact = sigact;
634 keep_copysig = TRUE; /* yes, we have a copy */
635 sigact.sa_handler = alarmfunc;
636 #ifdef SA_RESTART
637 /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
638 sigact.sa_flags &= ~SA_RESTART;
639 #endif
640 /* now set the new struct */
641 sigaction(SIGALRM, &sigact, NULL);
642 #else /* HAVE_SIGACTION */
643 /* no sigaction(), revert to the much lamer signal() */
644 #ifdef HAVE_SIGNAL
645 keep_sigact = signal(SIGALRM, alarmfunc);
646 #endif
647 #endif /* HAVE_SIGACTION */
648
649 /* alarm() makes a signal get sent when the timeout fires off, and that
650 will abort system calls */
651 prev_alarm = alarm(curlx_sltoui(timeout/1000L));
652 }
653
654 #else
655 #ifndef CURLRES_ASYNCH
656 if(timeoutms)
657 infof(conn->data, "timeout on name lookup is not supported\n");
658 #else
659 (void)timeoutms; /* timeoutms not used with an async resolver */
660 #endif
661 #endif /* USE_ALARM_TIMEOUT */
662
663 /* Perform the actual name resolution. This might be interrupted by an
664 * alarm if it takes too long.
665 */
666 rc = Curl_resolv(conn, hostname, port, entry);
667
668 #ifdef USE_ALARM_TIMEOUT
669 clean_up:
670
671 if(!prev_alarm)
672 /* deactivate a possibly active alarm before uninstalling the handler */
673 alarm(0);
674
675 #ifdef HAVE_SIGACTION
676 if(keep_copysig) {
677 /* we got a struct as it looked before, now put that one back nice
678 and clean */
679 sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
680 }
681 #else
682 #ifdef HAVE_SIGNAL
683 /* restore the previous SIGALRM handler */
684 signal(SIGALRM, keep_sigact);
685 #endif
686 #endif /* HAVE_SIGACTION */
687
688 /* switch back the alarm() to either zero or to what it was before minus
689 the time we spent until now! */
690 if(prev_alarm) {
691 /* there was an alarm() set before us, now put it back */
692 unsigned long elapsed_ms = Curl_tvdiff(Curl_tvnow(), conn->created);
693
694 /* the alarm period is counted in even number of seconds */
695 unsigned long alarm_set = prev_alarm - elapsed_ms/1000;
696
697 if(!alarm_set ||
698 ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
699 /* if the alarm time-left reached zero or turned "negative" (counted
700 with unsigned values), we should fire off a SIGALRM here, but we
701 won't, and zero would be to switch it off so we never set it to
702 less than 1! */
703 alarm(1);
704 rc = CURLRESOLV_TIMEDOUT;
705 failf(data, "Previous alarm fired off!");
706 }
707 else
708 alarm((unsigned int)alarm_set);
709 }
710 #endif /* USE_ALARM_TIMEOUT */
711
712 return rc;
713 }
714
715 /*
716 * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
717 * made, the struct may be destroyed due to pruning. It is important that only
718 * one unlock is made for each Curl_resolv() call.
719 *
720 * May be called with 'data' == NULL for global cache.
721 */
Curl_resolv_unlock(struct Curl_easy * data,struct Curl_dns_entry * dns)722 void Curl_resolv_unlock(struct Curl_easy *data, struct Curl_dns_entry *dns)
723 {
724 if(data && data->share)
725 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
726
727 freednsentry(dns);
728
729 if(data && data->share)
730 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
731 }
732
733 /*
734 * File-internal: release cache dns entry reference, free if inuse drops to 0
735 */
freednsentry(void * freethis)736 static void freednsentry(void *freethis)
737 {
738 struct Curl_dns_entry *dns = (struct Curl_dns_entry *) freethis;
739 DEBUGASSERT(dns && (dns->inuse>0));
740
741 dns->inuse--;
742 if(dns->inuse == 0) {
743 Curl_freeaddrinfo(dns->addr);
744 free(dns);
745 }
746 }
747
748 /*
749 * Curl_mk_dnscache() inits a new DNS cache and returns success/failure.
750 */
Curl_mk_dnscache(struct curl_hash * hash)751 int Curl_mk_dnscache(struct curl_hash *hash)
752 {
753 return Curl_hash_init(hash, 7, Curl_hash_str, Curl_str_key_compare,
754 freednsentry);
755 }
756
757 /*
758 * Curl_hostcache_clean()
759 *
760 * This _can_ be called with 'data' == NULL but then of course no locking
761 * can be done!
762 */
763
Curl_hostcache_clean(struct Curl_easy * data,struct curl_hash * hash)764 void Curl_hostcache_clean(struct Curl_easy *data,
765 struct curl_hash *hash)
766 {
767 if(data && data->share)
768 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
769
770 Curl_hash_clean(hash);
771
772 if(data && data->share)
773 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
774 }
775
776
Curl_loadhostpairs(struct Curl_easy * data)777 CURLcode Curl_loadhostpairs(struct Curl_easy *data)
778 {
779 struct curl_slist *hostp;
780 char hostname[256];
781 char address[256];
782 int port;
783
784 for(hostp = data->change.resolve; hostp; hostp = hostp->next) {
785 if(!hostp->data)
786 continue;
787 if(hostp->data[0] == '-') {
788 char *entry_id;
789 size_t entry_len;
790
791 if(2 != sscanf(hostp->data + 1, "%255[^:]:%d", hostname, &port)) {
792 infof(data, "Couldn't parse CURLOPT_RESOLVE removal entry '%s'!\n",
793 hostp->data);
794 continue;
795 }
796
797 /* Create an entry id, based upon the hostname and port */
798 entry_id = create_hostcache_id(hostname, port);
799 /* If we can't create the entry id, fail */
800 if(!entry_id) {
801 return CURLE_OUT_OF_MEMORY;
802 }
803
804 entry_len = strlen(entry_id);
805
806 if(data->share)
807 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
808
809 /* delete entry, ignore if it didn't exist */
810 Curl_hash_delete(data->dns.hostcache, entry_id, entry_len+1);
811
812 if(data->share)
813 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
814
815 /* free the allocated entry_id again */
816 free(entry_id);
817 }
818 else {
819 struct Curl_dns_entry *dns;
820 Curl_addrinfo *addr;
821 char *entry_id;
822 size_t entry_len;
823
824 if(3 != sscanf(hostp->data, "%255[^:]:%d:%255s", hostname, &port,
825 address)) {
826 infof(data, "Couldn't parse CURLOPT_RESOLVE entry '%s'!\n",
827 hostp->data);
828 continue;
829 }
830
831 addr = Curl_str2addr(address, port);
832 if(!addr) {
833 infof(data, "Address in '%s' found illegal!\n", hostp->data);
834 continue;
835 }
836
837 /* Create an entry id, based upon the hostname and port */
838 entry_id = create_hostcache_id(hostname, port);
839 /* If we can't create the entry id, fail */
840 if(!entry_id) {
841 Curl_freeaddrinfo(addr);
842 return CURLE_OUT_OF_MEMORY;
843 }
844
845 entry_len = strlen(entry_id);
846
847 if(data->share)
848 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
849
850 /* See if its already in our dns cache */
851 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
852
853 /* free the allocated entry_id again */
854 free(entry_id);
855
856 if(!dns) {
857 /* if not in the cache already, put this host in the cache */
858 dns = Curl_cache_addr(data, addr, hostname, port);
859 if(dns) {
860 dns->timestamp = 0; /* mark as added by CURLOPT_RESOLVE */
861 /* release the returned reference; the cache itself will keep the
862 * entry alive: */
863 dns->inuse--;
864 }
865 }
866 else
867 /* this is a duplicate, free it again */
868 Curl_freeaddrinfo(addr);
869
870 if(data->share)
871 Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
872
873 if(!dns) {
874 Curl_freeaddrinfo(addr);
875 return CURLE_OUT_OF_MEMORY;
876 }
877 infof(data, "Added %s:%d:%s to DNS cache\n",
878 hostname, port, address);
879 }
880 }
881 data->change.resolve = NULL; /* dealt with now */
882
883 return CURLE_OK;
884 }
885