1: /***************************************************************************
2: * _ _ ____ _
3: * Project ___| | | | _ \| |
4: * / __| | | | |_) | |
5: * | (__| |_| | _ <| |___
6: * \___|\___/|_| \_\_____|
7: *
8: * Copyright (C) 1998 - 2020, 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_NETINET_IN6_H
29: #include <netinet/in6.h>
30: #endif
31: #ifdef HAVE_NETDB_H
32: #include <netdb.h>
33: #endif
34: #ifdef HAVE_ARPA_INET_H
35: #include <arpa/inet.h>
36: #endif
37: #ifdef __VMS
38: #include <in.h>
39: #include <inet.h>
40: #endif
41:
42: #ifdef HAVE_SETJMP_H
43: #include <setjmp.h>
44: #endif
45: #ifdef HAVE_SIGNAL_H
46: #include <signal.h>
47: #endif
48:
49: #ifdef HAVE_PROCESS_H
50: #include <process.h>
51: #endif
52:
53: #include "urldata.h"
54: #include "sendf.h"
55: #include "hostip.h"
56: #include "hash.h"
57: #include "rand.h"
58: #include "share.h"
59: #include "strerror.h"
60: #include "url.h"
61: #include "inet_ntop.h"
62: #include "inet_pton.h"
63: #include "multiif.h"
64: #include "doh.h"
65: #include "warnless.h"
66: /* The last 3 #include files should be in this order */
67: #include "curl_printf.h"
68: #include "curl_memory.h"
69: #include "memdebug.h"
70:
71: #if defined(CURLRES_SYNCH) && \
72: defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
73: /* alarm-based timeouts can only be used with all the dependencies satisfied */
74: #define USE_ALARM_TIMEOUT
75: #endif
76:
77: #define MAX_HOSTCACHE_LEN (255 + 7) /* max FQDN + colon + port number + zero */
78:
79: /*
80: * hostip.c explained
81: * ==================
82: *
83: * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
84: * source file are these:
85: *
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
89: * defined.
90: *
91: * CURLRES_ARES - is defined if libcurl is built to use c-ares for
92: * asynchronous name resolves. This can be Windows or *nix.
93: *
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.
97: *
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
100: * defined.
101: *
102: * The host*.c sources files are split up like this:
103: *
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
109: *
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
113:
114: * The hostip.h is the united header file for all this. It defines the
115: * CURLRES_* defines based on the config*.h and curl_setup.h defines.
116: */
117:
118: static void freednsentry(void *freethis);
119:
120: /*
121: * Return # of addresses in a Curl_addrinfo struct
122: */
123: int Curl_num_addresses(const Curl_addrinfo *addr)
124: {
125: int i = 0;
126: while(addr) {
127: addr = addr->ai_next;
128: i++;
129: }
130: return i;
131: }
132:
133: /*
134: * Curl_printable_address() returns a printable version of the 1st address
135: * given in the 'ai' argument. The result will be stored in the buf that is
136: * bufsize bytes big.
137: *
138: * If the conversion fails, it returns NULL.
139: */
140: const char *
141: Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
142: {
143: const struct sockaddr_in *sa4;
144: const struct in_addr *ipaddr4;
145: #ifdef ENABLE_IPV6
146: const struct sockaddr_in6 *sa6;
147: const struct in6_addr *ipaddr6;
148: #endif
149:
150: switch(ai->ai_family) {
151: case AF_INET:
152: sa4 = (const void *)ai->ai_addr;
153: ipaddr4 = &sa4->sin_addr;
154: return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf,
155: bufsize);
156: #ifdef ENABLE_IPV6
157: case AF_INET6:
158: sa6 = (const void *)ai->ai_addr;
159: ipaddr6 = &sa6->sin6_addr;
160: return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf,
161: bufsize);
162: #endif
163: default:
164: break;
165: }
166: return NULL;
167: }
168:
169: /*
170: * Create a hostcache id string for the provided host + port, to be used by
171: * the DNS caching. Without alloc.
172: */
173: static void
174: create_hostcache_id(const char *name, int port, char *ptr, size_t buflen)
175: {
176: size_t len = strlen(name);
177: if(len > (buflen - 7))
178: len = buflen - 7;
179: /* store and lower case the name */
180: while(len--)
181: *ptr++ = (char)TOLOWER(*name++);
182: msnprintf(ptr, 7, ":%u", port);
183: }
184:
185: struct hostcache_prune_data {
186: long cache_timeout;
187: time_t now;
188: };
189:
190: /*
191: * This function is set as a callback to be called for every entry in the DNS
192: * cache when we want to prune old unused entries.
193: *
194: * Returning non-zero means remove the entry, return 0 to keep it in the
195: * cache.
196: */
197: static int
198: hostcache_timestamp_remove(void *datap, void *hc)
199: {
200: struct hostcache_prune_data *data =
201: (struct hostcache_prune_data *) datap;
202: struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
203:
204: return (0 != c->timestamp)
205: && (data->now - c->timestamp >= data->cache_timeout);
206: }
207:
208: /*
209: * Prune the DNS cache. This assumes that a lock has already been taken.
210: */
211: static void
212: hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
213: {
214: struct hostcache_prune_data user;
215:
216: user.cache_timeout = cache_timeout;
217: user.now = now;
218:
219: Curl_hash_clean_with_criterium(hostcache,
220: (void *) &user,
221: hostcache_timestamp_remove);
222: }
223:
224: /*
225: * Library-wide function for pruning the DNS cache. This function takes and
226: * returns the appropriate locks.
227: */
228: void Curl_hostcache_prune(struct Curl_easy *data)
229: {
230: time_t now;
231:
232: if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
233: /* cache forever means never prune, and NULL hostcache means
234: we can't do it */
235: return;
236:
237: if(data->share)
238: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
239:
240: time(&now);
241:
242: /* Remove outdated and unused entries from the hostcache */
243: hostcache_prune(data->dns.hostcache,
244: data->set.dns_cache_timeout,
245: now);
246:
247: if(data->share)
248: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
249: }
250:
251: #ifdef HAVE_SIGSETJMP
252: /* Beware this is a global and unique instance. This is used to store the
253: return address that we can jump back to from inside a signal handler. This
254: is not thread-safe stuff. */
255: sigjmp_buf curl_jmpenv;
256: #endif
257:
258: /* lookup address, returns entry if found and not stale */
259: static struct Curl_dns_entry *
260: fetch_addr(struct connectdata *conn,
261: const char *hostname,
262: int port)
263: {
264: struct Curl_dns_entry *dns = NULL;
265: size_t entry_len;
266: struct Curl_easy *data = conn->data;
267: char entry_id[MAX_HOSTCACHE_LEN];
268:
269: /* Create an entry id, based upon the hostname and port */
270: create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
271: entry_len = strlen(entry_id);
272:
273: /* See if its already in our dns cache */
274: dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
275:
276: /* No entry found in cache, check if we might have a wildcard entry */
277: if(!dns && data->change.wildcard_resolve) {
278: create_hostcache_id("*", port, entry_id, sizeof(entry_id));
279: entry_len = strlen(entry_id);
280:
281: /* See if it's already in our dns cache */
282: dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
283: }
284:
285: if(dns && (data->set.dns_cache_timeout != -1)) {
286: /* See whether the returned entry is stale. Done before we release lock */
287: struct hostcache_prune_data user;
288:
289: time(&user.now);
290: user.cache_timeout = data->set.dns_cache_timeout;
291:
292: if(hostcache_timestamp_remove(&user, dns)) {
293: infof(data, "Hostname in DNS cache was stale, zapped\n");
294: dns = NULL; /* the memory deallocation is being handled by the hash */
295: Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
296: }
297: }
298:
299: return dns;
300: }
301:
302: /*
303: * Curl_fetch_addr() fetches a 'Curl_dns_entry' already in the DNS cache.
304: *
305: * Curl_resolv() checks initially and multi_runsingle() checks each time
306: * it discovers the handle in the state WAITRESOLVE whether the hostname
307: * has already been resolved and the address has already been stored in
308: * the DNS cache. This short circuits waiting for a lot of pending
309: * lookups for the same hostname requested by different handles.
310: *
311: * Returns the Curl_dns_entry entry pointer or NULL if not in the cache.
312: *
313: * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after
314: * use, or we'll leak memory!
315: */
316: struct Curl_dns_entry *
317: Curl_fetch_addr(struct connectdata *conn,
318: const char *hostname,
319: int port)
320: {
321: struct Curl_easy *data = conn->data;
322: struct Curl_dns_entry *dns = NULL;
323:
324: if(data->share)
325: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
326:
327: dns = fetch_addr(conn, hostname, port);
328:
329: if(dns)
330: dns->inuse++; /* we use it! */
331:
332: if(data->share)
333: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
334:
335: return dns;
336: }
337:
338: #ifndef CURL_DISABLE_SHUFFLE_DNS
339: UNITTEST CURLcode Curl_shuffle_addr(struct Curl_easy *data,
340: Curl_addrinfo **addr);
341: /*
342: * Curl_shuffle_addr() shuffles the order of addresses in a 'Curl_addrinfo'
343: * struct by re-linking its linked list.
344: *
345: * The addr argument should be the address of a pointer to the head node of a
346: * `Curl_addrinfo` list and it will be modified to point to the new head after
347: * shuffling.
348: *
349: * Not declared static only to make it easy to use in a unit test!
350: *
351: * @unittest: 1608
352: */
353: UNITTEST CURLcode Curl_shuffle_addr(struct Curl_easy *data,
354: Curl_addrinfo **addr)
355: {
356: CURLcode result = CURLE_OK;
357: const int num_addrs = Curl_num_addresses(*addr);
358:
359: if(num_addrs > 1) {
360: Curl_addrinfo **nodes;
361: infof(data, "Shuffling %i addresses", num_addrs);
362:
363: nodes = malloc(num_addrs*sizeof(*nodes));
364: if(nodes) {
365: int i;
366: unsigned int *rnd;
367: const size_t rnd_size = num_addrs * sizeof(*rnd);
368:
369: /* build a plain array of Curl_addrinfo pointers */
370: nodes[0] = *addr;
371: for(i = 1; i < num_addrs; i++) {
372: nodes[i] = nodes[i-1]->ai_next;
373: }
374:
375: rnd = malloc(rnd_size);
376: if(rnd) {
377: /* Fisher-Yates shuffle */
378: if(Curl_rand(data, (unsigned char *)rnd, rnd_size) == CURLE_OK) {
379: Curl_addrinfo *swap_tmp;
380: for(i = num_addrs - 1; i > 0; i--) {
381: swap_tmp = nodes[rnd[i] % (i + 1)];
382: nodes[rnd[i] % (i + 1)] = nodes[i];
383: nodes[i] = swap_tmp;
384: }
385:
386: /* relink list in the new order */
387: for(i = 1; i < num_addrs; i++) {
388: nodes[i-1]->ai_next = nodes[i];
389: }
390:
391: nodes[num_addrs-1]->ai_next = NULL;
392: *addr = nodes[0];
393: }
394: free(rnd);
395: }
396: else
397: result = CURLE_OUT_OF_MEMORY;
398: free(nodes);
399: }
400: else
401: result = CURLE_OUT_OF_MEMORY;
402: }
403: return result;
404: }
405: #endif
406:
407: /*
408: * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
409: *
410: * When calling Curl_resolv() has resulted in a response with a returned
411: * address, we call this function to store the information in the dns
412: * cache etc
413: *
414: * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
415: */
416: struct Curl_dns_entry *
417: Curl_cache_addr(struct Curl_easy *data,
418: Curl_addrinfo *addr,
419: const char *hostname,
420: int port)
421: {
422: char entry_id[MAX_HOSTCACHE_LEN];
423: size_t entry_len;
424: struct Curl_dns_entry *dns;
425: struct Curl_dns_entry *dns2;
426:
427: #ifndef CURL_DISABLE_SHUFFLE_DNS
428: /* shuffle addresses if requested */
429: if(data->set.dns_shuffle_addresses) {
430: CURLcode result = Curl_shuffle_addr(data, &addr);
431: if(result)
432: return NULL;
433: }
434: #endif
435:
436: /* Create a new cache entry */
437: dns = calloc(1, sizeof(struct Curl_dns_entry));
438: if(!dns) {
439: return NULL;
440: }
441:
442: /* Create an entry id, based upon the hostname and port */
443: create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
444: entry_len = strlen(entry_id);
445:
446: dns->inuse = 1; /* the cache has the first reference */
447: dns->addr = addr; /* this is the address(es) */
448: time(&dns->timestamp);
449: if(dns->timestamp == 0)
450: dns->timestamp = 1; /* zero indicates CURLOPT_RESOLVE entry */
451:
452: /* Store the resolved data in our DNS cache. */
453: dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len + 1,
454: (void *)dns);
455: if(!dns2) {
456: free(dns);
457: return NULL;
458: }
459:
460: dns = dns2;
461: dns->inuse++; /* mark entry as in-use */
462: return dns;
463: }
464:
465: /*
466: * Curl_resolv() is the main name resolve function within libcurl. It resolves
467: * a name and returns a pointer to the entry in the 'entry' argument (if one
468: * is provided). This function might return immediately if we're using asynch
469: * resolves. See the return codes.
470: *
471: * The cache entry we return will get its 'inuse' counter increased when this
472: * function is used. You MUST call Curl_resolv_unlock() later (when you're
473: * done using this struct) to decrease the counter again.
474: *
475: * In debug mode, we specifically test for an interface name "LocalHost"
476: * and resolve "localhost" instead as a means to permit test cases
477: * to connect to a local test server with any host name.
478: *
479: * Return codes:
480: *
481: * CURLRESOLV_ERROR (-1) = error, no pointer
482: * CURLRESOLV_RESOLVED (0) = OK, pointer provided
483: * CURLRESOLV_PENDING (1) = waiting for response, no pointer
484: */
485:
486: enum resolve_t Curl_resolv(struct connectdata *conn,
487: const char *hostname,
488: int port,
489: bool allowDOH,
490: struct Curl_dns_entry **entry)
491: {
492: struct Curl_dns_entry *dns = NULL;
493: struct Curl_easy *data = conn->data;
494: CURLcode result;
495: enum resolve_t rc = CURLRESOLV_ERROR; /* default to failure */
496:
497: *entry = NULL;
498:
499: if(data->share)
500: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
501:
502: dns = fetch_addr(conn, hostname, port);
503:
504: if(dns) {
505: infof(data, "Hostname %s was found in DNS cache\n", hostname);
506: dns->inuse++; /* we use it! */
507: rc = CURLRESOLV_RESOLVED;
508: }
509:
510: if(data->share)
511: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
512:
513: if(!dns) {
514: /* The entry was not in the cache. Resolve it to IP address */
515:
516: Curl_addrinfo *addr = NULL;
517: int respwait = 0;
518: #ifndef USE_RESOLVE_ON_IPS
519: struct in_addr in;
520: #endif
521:
522: /* notify the resolver start callback */
523: if(data->set.resolver_start) {
524: int st;
525: Curl_set_in_callback(data, true);
526: st = data->set.resolver_start(data->state.resolver, NULL,
527: data->set.resolver_start_client);
528: Curl_set_in_callback(data, false);
529: if(st)
530: return CURLRESOLV_ERROR;
531: }
532:
533: #ifndef USE_RESOLVE_ON_IPS
534: /* First check if this is an IPv4 address string */
535: if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
536: /* This is a dotted IP address 123.123.123.123-style */
537: addr = Curl_ip2addr(AF_INET, &in, hostname, port);
538: #ifdef ENABLE_IPV6
539: if(!addr) {
540: struct in6_addr in6;
541: /* check if this is an IPv6 address string */
542: if(Curl_inet_pton(AF_INET6, hostname, &in6) > 0)
543: /* This is an IPv6 address literal */
544: addr = Curl_ip2addr(AF_INET6, &in6, hostname, port);
545: }
546: #endif /* ENABLE_IPV6 */
547: #endif /* !USE_RESOLVE_ON_IPS */
548:
549: if(!addr) {
550: /* Check what IP specifics the app has requested and if we can provide
551: * it. If not, bail out. */
552: if(!Curl_ipvalid(conn))
553: return CURLRESOLV_ERROR;
554:
555: if(allowDOH && data->set.doh) {
556: addr = Curl_doh(conn, hostname, port, &respwait);
557: }
558: else {
559: /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
560: non-zero value indicating that we need to wait for the response to
561: the resolve call */
562: addr = Curl_getaddrinfo(conn,
563: #ifdef DEBUGBUILD
564: (data->set.str[STRING_DEVICE]
565: && !strcmp(data->set.str[STRING_DEVICE],
566: "LocalHost"))?"localhost":
567: #endif
568: hostname, port, &respwait);
569: }
570: }
571: if(!addr) {
572: if(respwait) {
573: /* the response to our resolve call will come asynchronously at
574: a later time, good or bad */
575: /* First, check that we haven't received the info by now */
576: result = Curl_resolv_check(conn, &dns);
577: if(result) /* error detected */
578: return CURLRESOLV_ERROR;
579: if(dns)
580: rc = CURLRESOLV_RESOLVED; /* pointer provided */
581: else
582: rc = CURLRESOLV_PENDING; /* no info yet */
583: }
584: }
585: else {
586: if(data->share)
587: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
588:
589: /* we got a response, store it in the cache */
590: dns = Curl_cache_addr(data, addr, hostname, port);
591:
592: if(data->share)
593: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
594:
595: if(!dns)
596: /* returned failure, bail out nicely */
597: Curl_freeaddrinfo(addr);
598: else
599: rc = CURLRESOLV_RESOLVED;
600: }
601: }
602:
603: *entry = dns;
604:
605: return rc;
606: }
607:
608: #ifdef USE_ALARM_TIMEOUT
609: /*
610: * This signal handler jumps back into the main libcurl code and continues
611: * execution. This effectively causes the remainder of the application to run
612: * within a signal handler which is nonportable and could lead to problems.
613: */
614: static
615: RETSIGTYPE alarmfunc(int sig)
616: {
617: /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
618: (void)sig;
619: siglongjmp(curl_jmpenv, 1);
620: }
621: #endif /* USE_ALARM_TIMEOUT */
622:
623: /*
624: * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
625: * timeout. This function might return immediately if we're using asynch
626: * resolves. See the return codes.
627: *
628: * The cache entry we return will get its 'inuse' counter increased when this
629: * function is used. You MUST call Curl_resolv_unlock() later (when you're
630: * done using this struct) to decrease the counter again.
631: *
632: * If built with a synchronous resolver and use of signals is not
633: * disabled by the application, then a nonzero timeout will cause a
634: * timeout after the specified number of milliseconds. Otherwise, timeout
635: * is ignored.
636: *
637: * Return codes:
638: *
639: * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
640: * CURLRESOLV_ERROR (-1) = error, no pointer
641: * CURLRESOLV_RESOLVED (0) = OK, pointer provided
642: * CURLRESOLV_PENDING (1) = waiting for response, no pointer
643: */
644:
645: enum resolve_t Curl_resolv_timeout(struct connectdata *conn,
646: const char *hostname,
647: int port,
648: struct Curl_dns_entry **entry,
649: timediff_t timeoutms)
650: {
651: #ifdef USE_ALARM_TIMEOUT
652: #ifdef HAVE_SIGACTION
653: struct sigaction keep_sigact; /* store the old struct here */
654: volatile bool keep_copysig = FALSE; /* whether old sigact has been saved */
655: struct sigaction sigact;
656: #else
657: #ifdef HAVE_SIGNAL
658: void (*keep_sigact)(int); /* store the old handler here */
659: #endif /* HAVE_SIGNAL */
660: #endif /* HAVE_SIGACTION */
661: volatile long timeout;
662: volatile unsigned int prev_alarm = 0;
663: struct Curl_easy *data = conn->data;
664: #endif /* USE_ALARM_TIMEOUT */
665: enum resolve_t rc;
666:
667: *entry = NULL;
668:
669: if(timeoutms < 0)
670: /* got an already expired timeout */
671: return CURLRESOLV_TIMEDOUT;
672:
673: #ifdef USE_ALARM_TIMEOUT
674: if(data->set.no_signal)
675: /* Ignore the timeout when signals are disabled */
676: timeout = 0;
677: else
678: timeout = (timeoutms > LONG_MAX) ? LONG_MAX : (long)timeoutms;
679:
680: if(!timeout)
681: /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
682: return Curl_resolv(conn, hostname, port, TRUE, entry);
683:
684: if(timeout < 1000) {
685: /* The alarm() function only provides integer second resolution, so if
686: we want to wait less than one second we must bail out already now. */
687: failf(data,
688: "remaining timeout of %ld too small to resolve via SIGALRM method",
689: timeout);
690: return CURLRESOLV_TIMEDOUT;
691: }
692: /* This allows us to time-out from the name resolver, as the timeout
693: will generate a signal and we will siglongjmp() from that here.
694: This technique has problems (see alarmfunc).
695: This should be the last thing we do before calling Curl_resolv(),
696: as otherwise we'd have to worry about variables that get modified
697: before we invoke Curl_resolv() (and thus use "volatile"). */
698: if(sigsetjmp(curl_jmpenv, 1)) {
699: /* this is coming from a siglongjmp() after an alarm signal */
700: failf(data, "name lookup timed out");
701: rc = CURLRESOLV_ERROR;
702: goto clean_up;
703: }
704: else {
705: /*************************************************************
706: * Set signal handler to catch SIGALRM
707: * Store the old value to be able to set it back later!
708: *************************************************************/
709: #ifdef HAVE_SIGACTION
710: sigaction(SIGALRM, NULL, &sigact);
711: keep_sigact = sigact;
712: keep_copysig = TRUE; /* yes, we have a copy */
713: sigact.sa_handler = alarmfunc;
714: #ifdef SA_RESTART
715: /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
716: sigact.sa_flags &= ~SA_RESTART;
717: #endif
718: /* now set the new struct */
719: sigaction(SIGALRM, &sigact, NULL);
720: #else /* HAVE_SIGACTION */
721: /* no sigaction(), revert to the much lamer signal() */
722: #ifdef HAVE_SIGNAL
723: keep_sigact = signal(SIGALRM, alarmfunc);
724: #endif
725: #endif /* HAVE_SIGACTION */
726:
727: /* alarm() makes a signal get sent when the timeout fires off, and that
728: will abort system calls */
729: prev_alarm = alarm(curlx_sltoui(timeout/1000L));
730: }
731:
732: #else
733: #ifndef CURLRES_ASYNCH
734: if(timeoutms)
735: infof(conn->data, "timeout on name lookup is not supported\n");
736: #else
737: (void)timeoutms; /* timeoutms not used with an async resolver */
738: #endif
739: #endif /* USE_ALARM_TIMEOUT */
740:
741: /* Perform the actual name resolution. This might be interrupted by an
742: * alarm if it takes too long.
743: */
744: rc = Curl_resolv(conn, hostname, port, TRUE, entry);
745:
746: #ifdef USE_ALARM_TIMEOUT
747: clean_up:
748:
749: if(!prev_alarm)
750: /* deactivate a possibly active alarm before uninstalling the handler */
751: alarm(0);
752:
753: #ifdef HAVE_SIGACTION
754: if(keep_copysig) {
755: /* we got a struct as it looked before, now put that one back nice
756: and clean */
757: sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
758: }
759: #else
760: #ifdef HAVE_SIGNAL
761: /* restore the previous SIGALRM handler */
762: signal(SIGALRM, keep_sigact);
763: #endif
764: #endif /* HAVE_SIGACTION */
765:
766: /* switch back the alarm() to either zero or to what it was before minus
767: the time we spent until now! */
768: if(prev_alarm) {
769: /* there was an alarm() set before us, now put it back */
770: timediff_t elapsed_secs = Curl_timediff(Curl_now(),
771: conn->created) / 1000;
772:
773: /* the alarm period is counted in even number of seconds */
774: unsigned long alarm_set = (unsigned long)(prev_alarm - elapsed_secs);
775:
776: if(!alarm_set ||
777: ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
778: /* if the alarm time-left reached zero or turned "negative" (counted
779: with unsigned values), we should fire off a SIGALRM here, but we
780: won't, and zero would be to switch it off so we never set it to
781: less than 1! */
782: alarm(1);
783: rc = CURLRESOLV_TIMEDOUT;
784: failf(data, "Previous alarm fired off!");
785: }
786: else
787: alarm((unsigned int)alarm_set);
788: }
789: #endif /* USE_ALARM_TIMEOUT */
790:
791: return rc;
792: }
793:
794: /*
795: * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
796: * made, the struct may be destroyed due to pruning. It is important that only
797: * one unlock is made for each Curl_resolv() call.
798: *
799: * May be called with 'data' == NULL for global cache.
800: */
801: void Curl_resolv_unlock(struct Curl_easy *data, struct Curl_dns_entry *dns)
802: {
803: if(data && data->share)
804: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
805:
806: freednsentry(dns);
807:
808: if(data && data->share)
809: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
810: }
811:
812: /*
813: * File-internal: release cache dns entry reference, free if inuse drops to 0
814: */
815: static void freednsentry(void *freethis)
816: {
817: struct Curl_dns_entry *dns = (struct Curl_dns_entry *) freethis;
818: DEBUGASSERT(dns && (dns->inuse>0));
819:
820: dns->inuse--;
821: if(dns->inuse == 0) {
822: Curl_freeaddrinfo(dns->addr);
823: free(dns);
824: }
825: }
826:
827: /*
828: * Curl_mk_dnscache() inits a new DNS cache and returns success/failure.
829: */
830: int Curl_mk_dnscache(struct curl_hash *hash)
831: {
832: return Curl_hash_init(hash, 7, Curl_hash_str, Curl_str_key_compare,
833: freednsentry);
834: }
835:
836: /*
837: * Curl_hostcache_clean()
838: *
839: * This _can_ be called with 'data' == NULL but then of course no locking
840: * can be done!
841: */
842:
843: void Curl_hostcache_clean(struct Curl_easy *data,
844: struct curl_hash *hash)
845: {
846: if(data && data->share)
847: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
848:
849: Curl_hash_clean(hash);
850:
851: if(data && data->share)
852: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
853: }
854:
855:
856: CURLcode Curl_loadhostpairs(struct Curl_easy *data)
857: {
858: struct curl_slist *hostp;
859: char hostname[256];
860: int port = 0;
861:
862: /* Default is no wildcard found */
863: data->change.wildcard_resolve = false;
864:
865: for(hostp = data->change.resolve; hostp; hostp = hostp->next) {
866: char entry_id[MAX_HOSTCACHE_LEN];
867: if(!hostp->data)
868: continue;
869: if(hostp->data[0] == '-') {
870: size_t entry_len;
871:
872: if(2 != sscanf(hostp->data + 1, "%255[^:]:%d", hostname, &port)) {
873: infof(data, "Couldn't parse CURLOPT_RESOLVE removal entry '%s'!\n",
874: hostp->data);
875: continue;
876: }
877:
878: /* Create an entry id, based upon the hostname and port */
879: create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
880: entry_len = strlen(entry_id);
881:
882: if(data->share)
883: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
884:
885: /* delete entry, ignore if it didn't exist */
886: Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
887:
888: if(data->share)
889: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
890: }
891: else {
892: struct Curl_dns_entry *dns;
893: Curl_addrinfo *head = NULL, *tail = NULL;
894: size_t entry_len;
895: char address[64];
896: #if !defined(CURL_DISABLE_VERBOSE_STRINGS)
897: char *addresses = NULL;
898: #endif
899: char *addr_begin;
900: char *addr_end;
901: char *port_ptr;
902: char *end_ptr;
903: char *host_end;
904: unsigned long tmp_port;
905: bool error = true;
906:
907: host_end = strchr(hostp->data, ':');
908: if(!host_end ||
909: ((host_end - hostp->data) >= (ptrdiff_t)sizeof(hostname)))
910: goto err;
911:
912: memcpy(hostname, hostp->data, host_end - hostp->data);
913: hostname[host_end - hostp->data] = '\0';
914:
915: port_ptr = host_end + 1;
916: tmp_port = strtoul(port_ptr, &end_ptr, 10);
917: if(tmp_port > USHRT_MAX || end_ptr == port_ptr || *end_ptr != ':')
918: goto err;
919:
920: port = (int)tmp_port;
921: #if !defined(CURL_DISABLE_VERBOSE_STRINGS)
922: addresses = end_ptr + 1;
923: #endif
924:
925: while(*end_ptr) {
926: size_t alen;
927: Curl_addrinfo *ai;
928:
929: addr_begin = end_ptr + 1;
930: addr_end = strchr(addr_begin, ',');
931: if(!addr_end)
932: addr_end = addr_begin + strlen(addr_begin);
933: end_ptr = addr_end;
934:
935: /* allow IP(v6) address within [brackets] */
936: if(*addr_begin == '[') {
937: if(addr_end == addr_begin || *(addr_end - 1) != ']')
938: goto err;
939: ++addr_begin;
940: --addr_end;
941: }
942:
943: alen = addr_end - addr_begin;
944: if(!alen)
945: continue;
946:
947: if(alen >= sizeof(address))
948: goto err;
949:
950: memcpy(address, addr_begin, alen);
951: address[alen] = '\0';
952:
953: #ifndef ENABLE_IPV6
954: if(strchr(address, ':')) {
955: infof(data, "Ignoring resolve address '%s', missing IPv6 support.\n",
956: address);
957: continue;
958: }
959: #endif
960:
961: ai = Curl_str2addr(address, port);
962: if(!ai) {
963: infof(data, "Resolve address '%s' found illegal!\n", address);
964: goto err;
965: }
966:
967: if(tail) {
968: tail->ai_next = ai;
969: tail = tail->ai_next;
970: }
971: else {
972: head = tail = ai;
973: }
974: }
975:
976: if(!head)
977: goto err;
978:
979: error = false;
980: err:
981: if(error) {
982: infof(data, "Couldn't parse CURLOPT_RESOLVE entry '%s'!\n",
983: hostp->data);
984: Curl_freeaddrinfo(head);
985: continue;
986: }
987:
988: /* Create an entry id, based upon the hostname and port */
989: create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
990: entry_len = strlen(entry_id);
991:
992: if(data->share)
993: Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
994:
995: /* See if its already in our dns cache */
996: dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
997:
998: if(dns) {
999: infof(data, "RESOLVE %s:%d is - old addresses discarded!\n",
1000: hostname, port);
1001: /* delete old entry entry, there are two reasons for this
1002: 1. old entry may have different addresses.
1003: 2. even if entry with correct addresses is already in the cache,
1004: but if it is close to expire, then by the time next http
1005: request is made, it can get expired and pruned because old
1006: entry is not necessarily marked as added by CURLOPT_RESOLVE. */
1007:
1008: Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
1009: }
1010:
1011: /* put this new host in the cache */
1012: dns = Curl_cache_addr(data, head, hostname, port);
1013: if(dns) {
1014: dns->timestamp = 0; /* mark as added by CURLOPT_RESOLVE */
1015: /* release the returned reference; the cache itself will keep the
1016: * entry alive: */
1017: dns->inuse--;
1018: }
1019:
1020: if(data->share)
1021: Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
1022:
1023: if(!dns) {
1024: Curl_freeaddrinfo(head);
1025: return CURLE_OUT_OF_MEMORY;
1026: }
1027: infof(data, "Added %s:%d:%s to DNS cache\n",
1028: hostname, port, addresses);
1029:
1030: /* Wildcard hostname */
1031: if(hostname[0] == '*' && hostname[1] == '\0') {
1032: infof(data, "RESOLVE %s:%d is wildcard, enabling wildcard checks\n",
1033: hostname, port);
1034: data->change.wildcard_resolve = true;
1035: }
1036: }
1037: }
1038: data->change.resolve = NULL; /* dealt with now */
1039:
1040: return CURLE_OK;
1041: }
1042:
1043: CURLcode Curl_resolv_check(struct connectdata *conn,
1044: struct Curl_dns_entry **dns)
1045: {
1046: #if defined(CURL_DISABLE_DOH) && !defined(CURLRES_ASYNCH)
1047: (void)dns;
1048: #endif
1049:
1050: if(conn->data->set.doh)
1051: return Curl_doh_is_resolved(conn, dns);
1052: return Curl_resolver_is_resolved(conn, dns);
1053: }
1054:
1055: int Curl_resolv_getsock(struct connectdata *conn,
1056: curl_socket_t *socks)
1057: {
1058: #ifdef CURLRES_ASYNCH
1059: if(conn->data->set.doh)
1060: /* nothing to wait for during DOH resolve, those handles have their own
1061: sockets */
1062: return GETSOCK_BLANK;
1063: return Curl_resolver_getsock(conn, socks);
1064: #else
1065: (void)conn;
1066: (void)socks;
1067: return GETSOCK_BLANK;
1068: #endif
1069: }
1070:
1071: /* Call this function after Curl_connect() has returned async=TRUE and
1072: then a successful name resolve has been received.
1073:
1074: Note: this function disconnects and frees the conn data in case of
1075: resolve failure */
1076: CURLcode Curl_once_resolved(struct connectdata *conn,
1077: bool *protocol_done)
1078: {
1079: CURLcode result;
1080:
1081: if(conn->async.dns) {
1082: conn->dns_entry = conn->async.dns;
1083: conn->async.dns = NULL;
1084: }
1085:
1086: result = Curl_setup_conn(conn, protocol_done);
1087:
1088: if(result)
1089: /* We're not allowed to return failure with memory left allocated
1090: in the connectdata struct, free those here */
1091: Curl_disconnect(conn->data, conn, TRUE); /* close the connection */
1092:
1093: return result;
1094: }
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