1 /*************************************************************************** 2 * _ _ ____ _ 3 * Project ___| | | | _ \| | 4 * / __| | | | |_) | | 5 * | (__| |_| | _ <| |___ 6 * \___|\___/|_| \_\_____| 7 * 8 * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel (at) 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 "share.h" 58 #include "strerror.h" 59 #include "url.h" 60 #include "inet_ntop.h" 61 #include "warnless.h" 62 /* The last 3 #include files should be in this order */ 63 #include "curl_printf.h" 64 #include "curl_memory.h" 65 #include "memdebug.h" 66 67 #if defined(CURLRES_SYNCH) && \ 68 defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP) 69 /* alarm-based timeouts can only be used with all the dependencies satisfied */ 70 #define USE_ALARM_TIMEOUT 71 #endif 72 73 /* 74 * hostip.c explained 75 * ================== 76 * 77 * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c 78 * source file are these: 79 * 80 * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use 81 * that. The host may not be able to resolve IPv6, but we don't really have to 82 * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4 83 * defined. 84 * 85 * CURLRES_ARES - is defined if libcurl is built to use c-ares for 86 * asynchronous name resolves. This can be Windows or *nix. 87 * 88 * CURLRES_THREADED - is defined if libcurl is built to run under (native) 89 * Windows, and then the name resolve will be done in a new thread, and the 90 * supported API will be the same as for ares-builds. 91 * 92 * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If 93 * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is 94 * defined. 95 * 96 * The host*.c sources files are split up like this: 97 * 98 * hostip.c - method-independent resolver functions and utility functions 99 * hostasyn.c - functions for asynchronous name resolves 100 * hostsyn.c - functions for synchronous name resolves 101 * hostip4.c - IPv4 specific functions 102 * hostip6.c - IPv6 specific functions 103 * 104 * The two asynchronous name resolver backends are implemented in: 105 * asyn-ares.c - functions for ares-using name resolves 106 * asyn-thread.c - functions for threaded name resolves 107 108 * The hostip.h is the united header file for all this. It defines the 109 * CURLRES_* defines based on the config*.h and curl_setup.h defines. 110 */ 111 112 /* These two symbols are for the global DNS cache */ 113 static struct curl_hash hostname_cache; 114 static int host_cache_initialized; 115 116 static void freednsentry(void *freethis); 117 118 /* 119 * Curl_global_host_cache_init() initializes and sets up a global DNS cache. 120 * Global DNS cache is general badness. Do not use. This will be removed in 121 * a future version. Use the share interface instead! 122 * 123 * Returns a struct curl_hash pointer on success, NULL on failure. 124 */ 125 struct curl_hash *Curl_global_host_cache_init(void) 126 { 127 int rc = 0; 128 if(!host_cache_initialized) { 129 rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str, 130 Curl_str_key_compare, freednsentry); 131 if(!rc) 132 host_cache_initialized = 1; 133 } 134 return rc?NULL:&hostname_cache; 135 } 136 137 /* 138 * Destroy and cleanup the global DNS cache 139 */ 140 void Curl_global_host_cache_dtor(void) 141 { 142 if(host_cache_initialized) { 143 Curl_hash_destroy(&hostname_cache); 144 host_cache_initialized = 0; 145 } 146 } 147 148 /* 149 * Return # of addresses in a Curl_addrinfo struct 150 */ 151 int Curl_num_addresses(const Curl_addrinfo *addr) 152 { 153 int i = 0; 154 while(addr) { 155 addr = addr->ai_next; 156 i++; 157 } 158 return i; 159 } 160 161 /* 162 * Curl_printable_address() returns a printable version of the 1st address 163 * given in the 'ai' argument. The result will be stored in the buf that is 164 * bufsize bytes big. 165 * 166 * If the conversion fails, it returns NULL. 167 */ 168 const char * 169 Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize) 170 { 171 const struct sockaddr_in *sa4; 172 const struct in_addr *ipaddr4; 173 #ifdef ENABLE_IPV6 174 const struct sockaddr_in6 *sa6; 175 const struct in6_addr *ipaddr6; 176 #endif 177 178 switch(ai->ai_family) { 179 case AF_INET: 180 sa4 = (const void *)ai->ai_addr; 181 ipaddr4 = &sa4->sin_addr; 182 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf, 183 bufsize); 184 #ifdef ENABLE_IPV6 185 case AF_INET6: 186 sa6 = (const void *)ai->ai_addr; 187 ipaddr6 = &sa6->sin6_addr; 188 return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf, 189 bufsize); 190 #endif 191 default: 192 break; 193 } 194 return NULL; 195 } 196 197 /* 198 * Return a hostcache id string for the provided host + port, to be used by 199 * the DNS caching. 200 */ 201 static char * 202 create_hostcache_id(const char *name, int port) 203 { 204 /* create and return the new allocated entry */ 205 char *id = aprintf("%s:%d", name, port); 206 char *ptr = id; 207 if(ptr) { 208 /* lower case the name part */ 209 while(*ptr && (*ptr != ':')) { 210 *ptr = (char)TOLOWER(*ptr); 211 ptr++; 212 } 213 } 214 return id; 215 } 216 217 struct hostcache_prune_data { 218 long cache_timeout; 219 time_t now; 220 }; 221 222 /* 223 * This function is set as a callback to be called for every entry in the DNS 224 * cache when we want to prune old unused entries. 225 * 226 * Returning non-zero means remove the entry, return 0 to keep it in the 227 * cache. 228 */ 229 static int 230 hostcache_timestamp_remove(void *datap, void *hc) 231 { 232 struct hostcache_prune_data *data = 233 (struct hostcache_prune_data *) datap; 234 struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc; 235 236 return (0 != c->timestamp) 237 && (data->now - c->timestamp >= data->cache_timeout); 238 } 239 240 /* 241 * Prune the DNS cache. This assumes that a lock has already been taken. 242 */ 243 static void 244 hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now) 245 { 246 struct hostcache_prune_data user; 247 248 user.cache_timeout = cache_timeout; 249 user.now = now; 250 251 Curl_hash_clean_with_criterium(hostcache, 252 (void *) &user, 253 hostcache_timestamp_remove); 254 } 255 256 /* 257 * Library-wide function for pruning the DNS cache. This function takes and 258 * returns the appropriate locks. 259 */ 260 void Curl_hostcache_prune(struct Curl_easy *data) 261 { 262 time_t now; 263 264 if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache) 265 /* cache forever means never prune, and NULL hostcache means 266 we can't do it */ 267 return; 268 269 if(data->share) 270 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 271 272 time(&now); 273 274 /* Remove outdated and unused entries from the hostcache */ 275 hostcache_prune(data->dns.hostcache, 276 data->set.dns_cache_timeout, 277 now); 278 279 if(data->share) 280 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 281 } 282 283 #ifdef HAVE_SIGSETJMP 284 /* Beware this is a global and unique instance. This is used to store the 285 return address that we can jump back to from inside a signal handler. This 286 is not thread-safe stuff. */ 287 sigjmp_buf curl_jmpenv; 288 #endif 289 290 /* lookup address, returns entry if found and not stale */ 291 static struct Curl_dns_entry * 292 fetch_addr(struct connectdata *conn, 293 const char *hostname, 294 int port) 295 { 296 char *entry_id = NULL; 297 struct Curl_dns_entry *dns = NULL; 298 size_t entry_len; 299 struct Curl_easy *data = conn->data; 300 301 /* Create an entry id, based upon the hostname and port */ 302 entry_id = create_hostcache_id(hostname, port); 303 /* If we can't create the entry id, fail */ 304 if(!entry_id) 305 return dns; 306 307 entry_len = strlen(entry_id); 308 309 /* See if its already in our dns cache */ 310 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1); 311 312 if(dns && (data->set.dns_cache_timeout != -1)) { 313 /* See whether the returned entry is stale. Done before we release lock */ 314 struct hostcache_prune_data user; 315 316 time(&user.now); 317 user.cache_timeout = data->set.dns_cache_timeout; 318 319 if(hostcache_timestamp_remove(&user, dns)) { 320 infof(data, "Hostname in DNS cache was stale, zapped\n"); 321 dns = NULL; /* the memory deallocation is being handled by the hash */ 322 Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1); 323 } 324 } 325 326 /* free the allocated entry_id again */ 327 free(entry_id); 328 329 return dns; 330 } 331 332 /* 333 * Curl_fetch_addr() fetches a 'Curl_dns_entry' already in the DNS cache. 334 * 335 * Curl_resolv() checks initially and multi_runsingle() checks each time 336 * it discovers the handle in the state WAITRESOLVE whether the hostname 337 * has already been resolved and the address has already been stored in 338 * the DNS cache. This short circuits waiting for a lot of pending 339 * lookups for the same hostname requested by different handles. 340 * 341 * Returns the Curl_dns_entry entry pointer or NULL if not in the cache. 342 * 343 * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after 344 * use, or we'll leak memory! 345 */ 346 struct Curl_dns_entry * 347 Curl_fetch_addr(struct connectdata *conn, 348 const char *hostname, 349 int port) 350 { 351 struct Curl_easy *data = conn->data; 352 struct Curl_dns_entry *dns = NULL; 353 354 if(data->share) 355 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 356 357 dns = fetch_addr(conn, hostname, port); 358 359 if(dns) 360 dns->inuse++; /* we use it! */ 361 362 if(data->share) 363 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 364 365 return dns; 366 } 367 368 /* 369 * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache. 370 * 371 * When calling Curl_resolv() has resulted in a response with a returned 372 * address, we call this function to store the information in the dns 373 * cache etc 374 * 375 * Returns the Curl_dns_entry entry pointer or NULL if the storage failed. 376 */ 377 struct Curl_dns_entry * 378 Curl_cache_addr(struct Curl_easy *data, 379 Curl_addrinfo *addr, 380 const char *hostname, 381 int port) 382 { 383 char *entry_id; 384 size_t entry_len; 385 struct Curl_dns_entry *dns; 386 struct Curl_dns_entry *dns2; 387 388 /* Create an entry id, based upon the hostname and port */ 389 entry_id = create_hostcache_id(hostname, port); 390 /* If we can't create the entry id, fail */ 391 if(!entry_id) 392 return NULL; 393 entry_len = strlen(entry_id); 394 395 /* Create a new cache entry */ 396 dns = calloc(1, sizeof(struct Curl_dns_entry)); 397 if(!dns) { 398 free(entry_id); 399 return NULL; 400 } 401 402 dns->inuse = 1; /* the cache has the first reference */ 403 dns->addr = addr; /* this is the address(es) */ 404 time(&dns->timestamp); 405 if(dns->timestamp == 0) 406 dns->timestamp = 1; /* zero indicates CURLOPT_RESOLVE entry */ 407 408 /* Store the resolved data in our DNS cache. */ 409 dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len + 1, 410 (void *)dns); 411 if(!dns2) { 412 free(dns); 413 free(entry_id); 414 return NULL; 415 } 416 417 dns = dns2; 418 dns->inuse++; /* mark entry as in-use */ 419 420 /* free the allocated entry_id */ 421 free(entry_id); 422 423 return dns; 424 } 425 426 /* 427 * Curl_resolv() is the main name resolve function within libcurl. It resolves 428 * a name and returns a pointer to the entry in the 'entry' argument (if one 429 * is provided). This function might return immediately if we're using asynch 430 * resolves. See the return codes. 431 * 432 * The cache entry we return will get its 'inuse' counter increased when this 433 * function is used. You MUST call Curl_resolv_unlock() later (when you're 434 * done using this struct) to decrease the counter again. 435 * 436 * In debug mode, we specifically test for an interface name "LocalHost" 437 * and resolve "localhost" instead as a means to permit test cases 438 * to connect to a local test server with any host name. 439 * 440 * Return codes: 441 * 442 * CURLRESOLV_ERROR (-1) = error, no pointer 443 * CURLRESOLV_RESOLVED (0) = OK, pointer provided 444 * CURLRESOLV_PENDING (1) = waiting for response, no pointer 445 */ 446 447 int Curl_resolv(struct connectdata *conn, 448 const char *hostname, 449 int port, 450 struct Curl_dns_entry **entry) 451 { 452 struct Curl_dns_entry *dns = NULL; 453 struct Curl_easy *data = conn->data; 454 CURLcode result; 455 int rc = CURLRESOLV_ERROR; /* default to failure */ 456 457 *entry = NULL; 458 459 if(data->share) 460 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 461 462 dns = fetch_addr(conn, hostname, port); 463 464 if(dns) { 465 infof(data, "Hostname %s was found in DNS cache\n", hostname); 466 dns->inuse++; /* we use it! */ 467 rc = CURLRESOLV_RESOLVED; 468 } 469 470 if(data->share) 471 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 472 473 if(!dns) { 474 /* The entry was not in the cache. Resolve it to IP address */ 475 476 Curl_addrinfo *addr; 477 int respwait; 478 479 /* Check what IP specifics the app has requested and if we can provide it. 480 * If not, bail out. */ 481 if(!Curl_ipvalid(conn)) 482 return CURLRESOLV_ERROR; 483 484 /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a 485 non-zero value indicating that we need to wait for the response to the 486 resolve call */ 487 addr = Curl_getaddrinfo(conn, 488 #ifdef DEBUGBUILD 489 (data->set.str[STRING_DEVICE] 490 && !strcmp(data->set.str[STRING_DEVICE], 491 "LocalHost"))?"localhost": 492 #endif 493 hostname, port, &respwait); 494 495 if(!addr) { 496 if(respwait) { 497 /* the response to our resolve call will come asynchronously at 498 a later time, good or bad */ 499 /* First, check that we haven't received the info by now */ 500 result = Curl_resolver_is_resolved(conn, &dns); 501 if(result) /* error detected */ 502 return CURLRESOLV_ERROR; 503 if(dns) 504 rc = CURLRESOLV_RESOLVED; /* pointer provided */ 505 else 506 rc = CURLRESOLV_PENDING; /* no info yet */ 507 } 508 } 509 else { 510 if(data->share) 511 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 512 513 /* we got a response, store it in the cache */ 514 dns = Curl_cache_addr(data, addr, hostname, port); 515 516 if(data->share) 517 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 518 519 if(!dns) 520 /* returned failure, bail out nicely */ 521 Curl_freeaddrinfo(addr); 522 else 523 rc = CURLRESOLV_RESOLVED; 524 } 525 } 526 527 *entry = dns; 528 529 return rc; 530 } 531 532 #ifdef USE_ALARM_TIMEOUT 533 /* 534 * This signal handler jumps back into the main libcurl code and continues 535 * execution. This effectively causes the remainder of the application to run 536 * within a signal handler which is nonportable and could lead to problems. 537 */ 538 static 539 RETSIGTYPE alarmfunc(int sig) 540 { 541 /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */ 542 (void)sig; 543 siglongjmp(curl_jmpenv, 1); 544 } 545 #endif /* USE_ALARM_TIMEOUT */ 546 547 /* 548 * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a 549 * timeout. This function might return immediately if we're using asynch 550 * resolves. See the return codes. 551 * 552 * The cache entry we return will get its 'inuse' counter increased when this 553 * function is used. You MUST call Curl_resolv_unlock() later (when you're 554 * done using this struct) to decrease the counter again. 555 * 556 * If built with a synchronous resolver and use of signals is not 557 * disabled by the application, then a nonzero timeout will cause a 558 * timeout after the specified number of milliseconds. Otherwise, timeout 559 * is ignored. 560 * 561 * Return codes: 562 * 563 * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired 564 * CURLRESOLV_ERROR (-1) = error, no pointer 565 * CURLRESOLV_RESOLVED (0) = OK, pointer provided 566 * CURLRESOLV_PENDING (1) = waiting for response, no pointer 567 */ 568 569 int Curl_resolv_timeout(struct connectdata *conn, 570 const char *hostname, 571 int port, 572 struct Curl_dns_entry **entry, 573 time_t timeoutms) 574 { 575 #ifdef USE_ALARM_TIMEOUT 576 #ifdef HAVE_SIGACTION 577 struct sigaction keep_sigact; /* store the old struct here */ 578 volatile bool keep_copysig = FALSE; /* whether old sigact has been saved */ 579 struct sigaction sigact; 580 #else 581 #ifdef HAVE_SIGNAL 582 void (*keep_sigact)(int); /* store the old handler here */ 583 #endif /* HAVE_SIGNAL */ 584 #endif /* HAVE_SIGACTION */ 585 volatile long timeout; 586 volatile unsigned int prev_alarm = 0; 587 struct Curl_easy *data = conn->data; 588 #endif /* USE_ALARM_TIMEOUT */ 589 int rc; 590 591 *entry = NULL; 592 593 if(timeoutms < 0) 594 /* got an already expired timeout */ 595 return CURLRESOLV_TIMEDOUT; 596 597 #ifdef USE_ALARM_TIMEOUT 598 if(data->set.no_signal) 599 /* Ignore the timeout when signals are disabled */ 600 timeout = 0; 601 else 602 timeout = (timeoutms > LONG_MAX) ? LONG_MAX : (long)timeoutms; 603 604 if(!timeout) 605 /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */ 606 return Curl_resolv(conn, hostname, port, entry); 607 608 if(timeout < 1000) { 609 /* The alarm() function only provides integer second resolution, so if 610 we want to wait less than one second we must bail out already now. */ 611 failf(data, 612 "remaining timeout of %ld too small to resolve via SIGALRM method", 613 timeout); 614 return CURLRESOLV_TIMEDOUT; 615 } 616 /* This allows us to time-out from the name resolver, as the timeout 617 will generate a signal and we will siglongjmp() from that here. 618 This technique has problems (see alarmfunc). 619 This should be the last thing we do before calling Curl_resolv(), 620 as otherwise we'd have to worry about variables that get modified 621 before we invoke Curl_resolv() (and thus use "volatile"). */ 622 if(sigsetjmp(curl_jmpenv, 1)) { 623 /* this is coming from a siglongjmp() after an alarm signal */ 624 failf(data, "name lookup timed out"); 625 rc = CURLRESOLV_ERROR; 626 goto clean_up; 627 } 628 else { 629 /************************************************************* 630 * Set signal handler to catch SIGALRM 631 * Store the old value to be able to set it back later! 632 *************************************************************/ 633 #ifdef HAVE_SIGACTION 634 sigaction(SIGALRM, NULL, &sigact); 635 keep_sigact = sigact; 636 keep_copysig = TRUE; /* yes, we have a copy */ 637 sigact.sa_handler = alarmfunc; 638 #ifdef SA_RESTART 639 /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */ 640 sigact.sa_flags &= ~SA_RESTART; 641 #endif 642 /* now set the new struct */ 643 sigaction(SIGALRM, &sigact, NULL); 644 #else /* HAVE_SIGACTION */ 645 /* no sigaction(), revert to the much lamer signal() */ 646 #ifdef HAVE_SIGNAL 647 keep_sigact = signal(SIGALRM, alarmfunc); 648 #endif 649 #endif /* HAVE_SIGACTION */ 650 651 /* alarm() makes a signal get sent when the timeout fires off, and that 652 will abort system calls */ 653 prev_alarm = alarm(curlx_sltoui(timeout/1000L)); 654 } 655 656 #else 657 #ifndef CURLRES_ASYNCH 658 if(timeoutms) 659 infof(conn->data, "timeout on name lookup is not supported\n"); 660 #else 661 (void)timeoutms; /* timeoutms not used with an async resolver */ 662 #endif 663 #endif /* USE_ALARM_TIMEOUT */ 664 665 /* Perform the actual name resolution. This might be interrupted by an 666 * alarm if it takes too long. 667 */ 668 rc = Curl_resolv(conn, hostname, port, entry); 669 670 #ifdef USE_ALARM_TIMEOUT 671 clean_up: 672 673 if(!prev_alarm) 674 /* deactivate a possibly active alarm before uninstalling the handler */ 675 alarm(0); 676 677 #ifdef HAVE_SIGACTION 678 if(keep_copysig) { 679 /* we got a struct as it looked before, now put that one back nice 680 and clean */ 681 sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */ 682 } 683 #else 684 #ifdef HAVE_SIGNAL 685 /* restore the previous SIGALRM handler */ 686 signal(SIGALRM, keep_sigact); 687 #endif 688 #endif /* HAVE_SIGACTION */ 689 690 /* switch back the alarm() to either zero or to what it was before minus 691 the time we spent until now! */ 692 if(prev_alarm) { 693 /* there was an alarm() set before us, now put it back */ 694 timediff_t elapsed_secs = Curl_timediff(Curl_now(), 695 conn->created) / 1000; 696 697 /* the alarm period is counted in even number of seconds */ 698 unsigned long alarm_set = prev_alarm - elapsed_secs; 699 700 if(!alarm_set || 701 ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) { 702 /* if the alarm time-left reached zero or turned "negative" (counted 703 with unsigned values), we should fire off a SIGALRM here, but we 704 won't, and zero would be to switch it off so we never set it to 705 less than 1! */ 706 alarm(1); 707 rc = CURLRESOLV_TIMEDOUT; 708 failf(data, "Previous alarm fired off!"); 709 } 710 else 711 alarm((unsigned int)alarm_set); 712 } 713 #endif /* USE_ALARM_TIMEOUT */ 714 715 return rc; 716 } 717 718 /* 719 * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been 720 * made, the struct may be destroyed due to pruning. It is important that only 721 * one unlock is made for each Curl_resolv() call. 722 * 723 * May be called with 'data' == NULL for global cache. 724 */ 725 void Curl_resolv_unlock(struct Curl_easy *data, struct Curl_dns_entry *dns) 726 { 727 if(data && data->share) 728 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 729 730 freednsentry(dns); 731 732 if(data && data->share) 733 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 734 } 735 736 /* 737 * File-internal: release cache dns entry reference, free if inuse drops to 0 738 */ 739 static void freednsentry(void *freethis) 740 { 741 struct Curl_dns_entry *dns = (struct Curl_dns_entry *) freethis; 742 DEBUGASSERT(dns && (dns->inuse>0)); 743 744 dns->inuse--; 745 if(dns->inuse == 0) { 746 Curl_freeaddrinfo(dns->addr); 747 free(dns); 748 } 749 } 750 751 /* 752 * Curl_mk_dnscache() inits a new DNS cache and returns success/failure. 753 */ 754 int Curl_mk_dnscache(struct curl_hash *hash) 755 { 756 return Curl_hash_init(hash, 7, Curl_hash_str, Curl_str_key_compare, 757 freednsentry); 758 } 759 760 /* 761 * Curl_hostcache_clean() 762 * 763 * This _can_ be called with 'data' == NULL but then of course no locking 764 * can be done! 765 */ 766 767 void Curl_hostcache_clean(struct Curl_easy *data, 768 struct curl_hash *hash) 769 { 770 if(data && data->share) 771 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 772 773 Curl_hash_clean(hash); 774 775 if(data && data->share) 776 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 777 } 778 779 780 CURLcode Curl_loadhostpairs(struct Curl_easy *data) 781 { 782 struct curl_slist *hostp; 783 char hostname[256]; 784 int port; 785 786 for(hostp = data->change.resolve; hostp; hostp = hostp->next) { 787 if(!hostp->data) 788 continue; 789 if(hostp->data[0] == '-') { 790 char *entry_id; 791 size_t entry_len; 792 793 if(2 != sscanf(hostp->data + 1, "%255[^:]:%d", hostname, &port)) { 794 infof(data, "Couldn't parse CURLOPT_RESOLVE removal entry '%s'!\n", 795 hostp->data); 796 continue; 797 } 798 799 /* Create an entry id, based upon the hostname and port */ 800 entry_id = create_hostcache_id(hostname, port); 801 /* If we can't create the entry id, fail */ 802 if(!entry_id) { 803 return CURLE_OUT_OF_MEMORY; 804 } 805 806 entry_len = strlen(entry_id); 807 808 if(data->share) 809 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 810 811 /* delete entry, ignore if it didn't exist */ 812 Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1); 813 814 if(data->share) 815 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 816 817 /* free the allocated entry_id again */ 818 free(entry_id); 819 } 820 else { 821 struct Curl_dns_entry *dns; 822 Curl_addrinfo *addr; 823 char *entry_id; 824 size_t entry_len; 825 char buffer[256]; 826 char *address = &buffer[0]; 827 828 if(3 != sscanf(hostp->data, "%255[^:]:%d:%255s", hostname, &port, 829 address)) { 830 infof(data, "Couldn't parse CURLOPT_RESOLVE entry '%s'!\n", 831 hostp->data); 832 continue; 833 } 834 835 /* allow IP(v6) address within [brackets] */ 836 if(address[0] == '[') { 837 size_t alen = strlen(address); 838 if(address[alen-1] != ']') 839 /* it needs to also end with ] to be valid */ 840 continue; 841 address[alen-1] = 0; /* zero terminate there */ 842 address++; /* pass the open bracket */ 843 } 844 845 addr = Curl_str2addr(address, port); 846 if(!addr) { 847 infof(data, "Address in '%s' found illegal!\n", hostp->data); 848 continue; 849 } 850 851 /* Create an entry id, based upon the hostname and port */ 852 entry_id = create_hostcache_id(hostname, port); 853 /* If we can't create the entry id, fail */ 854 if(!entry_id) { 855 Curl_freeaddrinfo(addr); 856 return CURLE_OUT_OF_MEMORY; 857 } 858 859 entry_len = strlen(entry_id); 860 861 if(data->share) 862 Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); 863 864 /* See if its already in our dns cache */ 865 dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1); 866 867 /* free the allocated entry_id again */ 868 free(entry_id); 869 870 if(!dns) { 871 /* if not in the cache already, put this host in the cache */ 872 dns = Curl_cache_addr(data, addr, hostname, port); 873 if(dns) { 874 dns->timestamp = 0; /* mark as added by CURLOPT_RESOLVE */ 875 /* release the returned reference; the cache itself will keep the 876 * entry alive: */ 877 dns->inuse--; 878 } 879 } 880 else { 881 /* this is a duplicate, free it again */ 882 infof(data, "RESOLVE %s:%d is already cached, %s not stored!\n", 883 hostname, port, address); 884 Curl_freeaddrinfo(addr); 885 } 886 887 if(data->share) 888 Curl_share_unlock(data, CURL_LOCK_DATA_DNS); 889 890 if(!dns) { 891 Curl_freeaddrinfo(addr); 892 return CURLE_OUT_OF_MEMORY; 893 } 894 infof(data, "Added %s:%d:%s to DNS cache\n", 895 hostname, port, address); 896 } 897 } 898 data->change.resolve = NULL; /* dealt with now */ 899 900 return CURLE_OK; 901 } 902