/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 1998 - 2009, Daniel Stenberg, <daniel@haxx.se>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at http://curl.haxx.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * * $Id: hostip.c,v 1.217 2009-09-01 14:27:01 bagder Exp $ ***************************************************************************/ #include "setup.h" #include <string.h> #ifdef HAVE_SYS_SOCKET_H #include <sys/socket.h> #endif #ifdef HAVE_NETINET_IN_H #include <netinet/in.h> #endif #ifdef HAVE_NETDB_H #include <netdb.h> #endif #ifdef HAVE_ARPA_INET_H #include <arpa/inet.h> #endif #ifdef HAVE_STDLIB_H #include <stdlib.h> /* required for free() prototypes */ #endif #ifdef HAVE_UNISTD_H #include <unistd.h> /* for the close() proto */ #endif #ifdef VMS #include <in.h> #include <inet.h> #include <stdlib.h> #endif #ifdef HAVE_SETJMP_H #include <setjmp.h> #endif #ifdef HAVE_SIGNAL_H #include <signal.h> #endif #ifdef HAVE_PROCESS_H #include <process.h> #endif #include "urldata.h" #include "sendf.h" #include "hostip.h" #include "hash.h" #include "share.h" #include "strerror.h" #include "url.h" #include "inet_ntop.h" #define _MPRINTF_REPLACE /* use our functions only */ #include <curl/mprintf.h> #include "curl_memory.h" /* The last #include file should be: */ #include "memdebug.h" #if defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP) \ && !defined(USE_ARES) /* alarm-based timeouts can only be used with all the dependencies satisfied */ #define USE_ALARM_TIMEOUT #endif /* * hostip.c explained * ================== * * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c * source file are these: * * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use * that. The host may not be able to resolve IPv6, but we don't really have to * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4 * defined. * * CURLRES_ARES - is defined if libcurl is built to use c-ares for * asynchronous name resolves. This can be Windows or *nix. * * CURLRES_THREADED - is defined if libcurl is built to run under (native) * Windows, and then the name resolve will be done in a new thread, and the * supported API will be the same as for ares-builds. * * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is * defined. * * The host*.c sources files are split up like this: * * hostip.c - method-independent resolver functions and utility functions * hostasyn.c - functions for asynchronous name resolves * hostsyn.c - functions for synchronous name resolves * hostares.c - functions for ares-using name resolves * hostthre.c - functions for threaded name resolves * hostip4.c - ipv4-specific functions * hostip6.c - ipv6-specific functions * * The hostip.h is the united header file for all this. It defines the * CURLRES_* defines based on the config*.h and setup.h defines. */ /* These two symbols are for the global DNS cache */ static struct curl_hash hostname_cache; static int host_cache_initialized; static void freednsentry(void *freethis); /* * Curl_global_host_cache_init() initializes and sets up a global DNS cache. * Global DNS cache is general badness. Do not use. This will be removed in * a future version. Use the share interface instead! * * Returns a struct curl_hash pointer on success, NULL on failure. */ struct curl_hash *Curl_global_host_cache_init(void) { int rc = 0; if(!host_cache_initialized) { rc = Curl_hash_init(&hostname_cache, 7, Curl_hash_str, Curl_str_key_compare, freednsentry); if(!rc) host_cache_initialized = 1; } return rc?NULL:&hostname_cache; } /* * Destroy and cleanup the global DNS cache */ void Curl_global_host_cache_dtor(void) { if(host_cache_initialized) { Curl_hash_clean(&hostname_cache); host_cache_initialized = 0; } } /* * Return # of adresses in a Curl_addrinfo struct */ int Curl_num_addresses(const Curl_addrinfo *addr) { int i = 0; while(addr) { addr = addr->ai_next; i++; } return i; } /* * Curl_printable_address() returns a printable version of the 1st address * given in the 'ai' argument. The result will be stored in the buf that is * bufsize bytes big. * * If the conversion fails, it returns NULL. */ const char * Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize) { const struct sockaddr_in *sa4; const struct in_addr *ipaddr4; #ifdef ENABLE_IPV6 const struct sockaddr_in6 *sa6; const struct in6_addr *ipaddr6; #endif switch (ai->ai_family) { case AF_INET: sa4 = (const void *)ai->ai_addr; ipaddr4 = &sa4->sin_addr; return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf, bufsize); #ifdef ENABLE_IPV6 case AF_INET6: sa6 = (const void *)ai->ai_addr; ipaddr6 = &sa6->sin6_addr; return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf, bufsize); #endif default: break; } return NULL; } /* * Return a hostcache id string for the providing host + port, to be used by * the DNS caching. */ static char * create_hostcache_id(const char *server, int port) { /* create and return the new allocated entry */ return aprintf("%s:%d", server, port); } struct hostcache_prune_data { long cache_timeout; time_t now; }; /* * This function is set as a callback to be called for every entry in the DNS * cache when we want to prune old unused entries. * * Returning non-zero means remove the entry, return 0 to keep it in the * cache. */ static int hostcache_timestamp_remove(void *datap, void *hc) { struct hostcache_prune_data *data = (struct hostcache_prune_data *) datap; struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc; if((data->now - c->timestamp < data->cache_timeout) || c->inuse) { /* please don't remove */ return 0; } /* fine, remove */ return 1; } /* * Prune the DNS cache. This assumes that a lock has already been taken. */ static void hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now) { struct hostcache_prune_data user; user.cache_timeout = cache_timeout; user.now = now; Curl_hash_clean_with_criterium(hostcache, (void *) &user, hostcache_timestamp_remove); } /* * Library-wide function for pruning the DNS cache. This function takes and * returns the appropriate locks. */ void Curl_hostcache_prune(struct SessionHandle *data) { time_t now; if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache) /* cache forever means never prune, and NULL hostcache means we can't do it */ return; if(data->share) Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); time(&now); /* Remove outdated and unused entries from the hostcache */ hostcache_prune(data->dns.hostcache, data->set.dns_cache_timeout, now); if(data->share) Curl_share_unlock(data, CURL_LOCK_DATA_DNS); } /* * Check if the entry should be pruned. Assumes a locked cache. */ static int remove_entry_if_stale(struct SessionHandle *data, struct Curl_dns_entry *dns) { struct hostcache_prune_data user; if( !dns || (data->set.dns_cache_timeout == -1) || !data->dns.hostcache) /* cache forever means never prune, and NULL hostcache means we can't do it */ return 0; time(&user.now); user.cache_timeout = data->set.dns_cache_timeout; if( !hostcache_timestamp_remove(&user,dns) ) return 0; Curl_hash_clean_with_criterium(data->dns.hostcache, (void *) &user, hostcache_timestamp_remove); return 1; } #ifdef HAVE_SIGSETJMP /* Beware this is a global and unique instance. This is used to store the return address that we can jump back to from inside a signal handler. This is not thread-safe stuff. */ sigjmp_buf curl_jmpenv; #endif /* * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache. * * When calling Curl_resolv() has resulted in a response with a returned * address, we call this function to store the information in the dns * cache etc * * Returns the Curl_dns_entry entry pointer or NULL if the storage failed. */ struct Curl_dns_entry * Curl_cache_addr(struct SessionHandle *data, Curl_addrinfo *addr, const char *hostname, int port) { char *entry_id; size_t entry_len; struct Curl_dns_entry *dns; struct Curl_dns_entry *dns2; time_t now; /* Create an entry id, based upon the hostname and port */ entry_id = create_hostcache_id(hostname, port); /* If we can't create the entry id, fail */ if(!entry_id) return NULL; entry_len = strlen(entry_id); /* Create a new cache entry */ dns = calloc(sizeof(struct Curl_dns_entry), 1); if(!dns) { free(entry_id); return NULL; } dns->inuse = 0; /* init to not used */ dns->addr = addr; /* this is the address(es) */ /* Store the resolved data in our DNS cache. This function may return a pointer to an existing struct already present in the hash, and it may return the same argument we pass in. Make no assumptions. */ dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1, (void *)dns); if(!dns2) { /* Major badness, run away. */ free(dns); free(entry_id); return NULL; } time(&now); dns = dns2; dns->timestamp = now; /* used now */ dns->inuse++; /* mark entry as in-use */ /* free the allocated entry_id again */ free(entry_id); return dns; } /* * Curl_resolv() is the main name resolve function within libcurl. It resolves * a name and returns a pointer to the entry in the 'entry' argument (if one * is provided). This function might return immediately if we're using asynch * resolves. See the return codes. * * The cache entry we return will get its 'inuse' counter increased when this * function is used. You MUST call Curl_resolv_unlock() later (when you're * done using this struct) to decrease the counter again. * * In debug mode, we specifically test for an interface name "LocalHost" * and resolve "localhost" instead as a means to permit test cases * to connect to a local test server with any host name. * * Return codes: * * CURLRESOLV_ERROR (-1) = error, no pointer * CURLRESOLV_RESOLVED (0) = OK, pointer provided * CURLRESOLV_PENDING (1) = waiting for response, no pointer */ int Curl_resolv(struct connectdata *conn, const char *hostname, int port, struct Curl_dns_entry **entry) { char *entry_id = NULL; struct Curl_dns_entry *dns = NULL; size_t entry_len; struct SessionHandle *data = conn->data; CURLcode result; int rc = CURLRESOLV_ERROR; /* default to failure */ *entry = NULL; /* Create an entry id, based upon the hostname and port */ entry_id = create_hostcache_id(hostname, port); /* If we can't create the entry id, fail */ if(!entry_id) return rc; entry_len = strlen(entry_id); if(data->share) Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); /* See if its already in our dns cache */ dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1); /* See whether the returned entry is stale. Done before we release lock */ if( remove_entry_if_stale(data, dns) ) dns = NULL; /* the memory deallocation is being handled by the hash */ if(dns) { dns->inuse++; /* we use it! */ rc = CURLRESOLV_RESOLVED; } if(data->share) Curl_share_unlock(data, CURL_LOCK_DATA_DNS); /* free the allocated entry_id again */ free(entry_id); if(!dns) { /* The entry was not in the cache. Resolve it to IP address */ Curl_addrinfo *addr; int respwait; /* Check what IP specifics the app has requested and if we can provide it. * If not, bail out. */ if(!Curl_ipvalid(data)) return CURLRESOLV_ERROR; /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a non-zero value indicating that we need to wait for the response to the resolve call */ addr = Curl_getaddrinfo(conn, #ifdef DEBUGBUILD (data->set.str[STRING_DEVICE] && !strcmp(data->set.str[STRING_DEVICE], "LocalHost"))?"localhost": #endif hostname, port, &respwait); if(!addr) { if(respwait) { /* the response to our resolve call will come asynchronously at a later time, good or bad */ /* First, check that we haven't received the info by now */ result = Curl_is_resolved(conn, &dns); if(result) /* error detected */ return CURLRESOLV_ERROR; if(dns) rc = CURLRESOLV_RESOLVED; /* pointer provided */ else rc = CURLRESOLV_PENDING; /* no info yet */ } } else { if(data->share) Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); /* we got a response, store it in the cache */ dns = Curl_cache_addr(data, addr, hostname, port); if(data->share) Curl_share_unlock(data, CURL_LOCK_DATA_DNS); if(!dns) /* returned failure, bail out nicely */ Curl_freeaddrinfo(addr); else rc = CURLRESOLV_RESOLVED; } } *entry = dns; return rc; } #ifdef USE_ALARM_TIMEOUT /* * This signal handler jumps back into the main libcurl code and continues * execution. This effectively causes the remainder of the application to run * within a signal handler which is nonportable and could lead to problems. */ static RETSIGTYPE alarmfunc(int sig) { /* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */ (void)sig; siglongjmp(curl_jmpenv, 1); return; } #endif /* USE_ALARM_TIMEOUT */ /* * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a * timeout. This function might return immediately if we're using asynch * resolves. See the return codes. * * The cache entry we return will get its 'inuse' counter increased when this * function is used. You MUST call Curl_resolv_unlock() later (when you're * done using this struct) to decrease the counter again. * * If built with a synchronous resolver and use of signals is not * disabled by the application, then a nonzero timeout will cause a * timeout after the specified number of milliseconds. Otherwise, timeout * is ignored. * * Return codes: * * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired * CURLRESOLV_ERROR (-1) = error, no pointer * CURLRESOLV_RESOLVED (0) = OK, pointer provided * CURLRESOLV_PENDING (1) = waiting for response, no pointer */ int Curl_resolv_timeout(struct connectdata *conn, const char *hostname, int port, struct Curl_dns_entry **entry, long timeoutms) { #ifdef USE_ALARM_TIMEOUT #ifdef HAVE_SIGACTION struct sigaction keep_sigact; /* store the old struct here */ bool keep_copysig=FALSE; /* did copy it? */ struct sigaction sigact; #else #ifdef HAVE_SIGNAL void (*keep_sigact)(int); /* store the old handler here */ #endif /* HAVE_SIGNAL */ #endif /* HAVE_SIGACTION */ volatile long timeout; unsigned int prev_alarm=0; struct SessionHandle *data = conn->data; #endif /* USE_ALARM_TIMEOUT */ int rc; *entry = NULL; #ifdef USE_ALARM_TIMEOUT if (data->set.no_signal) /* Ignore the timeout when signals are disabled */ timeout = 0; else timeout = timeoutms; if(timeout && timeout < 1000) /* The alarm() function only provides integer second resolution, so if we want to wait less than one second we must bail out already now. */ return CURLRESOLV_TIMEDOUT; if (timeout > 0) { /* This allows us to time-out from the name resolver, as the timeout will generate a signal and we will siglongjmp() from that here. This technique has problems (see alarmfunc). */ if(sigsetjmp(curl_jmpenv, 1)) { /* this is coming from a siglongjmp() after an alarm signal */ failf(data, "name lookup timed out"); return CURLRESOLV_ERROR; } /************************************************************* * Set signal handler to catch SIGALRM * Store the old value to be able to set it back later! *************************************************************/ #ifdef HAVE_SIGACTION sigaction(SIGALRM, NULL, &sigact); keep_sigact = sigact; keep_copysig = TRUE; /* yes, we have a copy */ sigact.sa_handler = alarmfunc; #ifdef SA_RESTART /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */ sigact.sa_flags &= ~SA_RESTART; #endif /* now set the new struct */ sigaction(SIGALRM, &sigact, NULL); #else /* HAVE_SIGACTION */ /* no sigaction(), revert to the much lamer signal() */ #ifdef HAVE_SIGNAL keep_sigact = signal(SIGALRM, alarmfunc); #endif #endif /* HAVE_SIGACTION */ /* alarm() makes a signal get sent when the timeout fires off, and that will abort system calls */ prev_alarm = alarm((unsigned int) (timeout/1000L)); } #else #ifndef CURLRES_ASYNCH if(timeoutms) infof(conn->data, "timeout on name lookup is not supported\n"); #else (void)timeoutms; /* timeoutms not used with an async resolver */ #endif #endif /* USE_ALARM_TIMEOUT */ /* Perform the actual name resolution. This might be interrupted by an * alarm if it takes too long. */ rc = Curl_resolv(conn, hostname, port, entry); #ifdef USE_ALARM_TIMEOUT if (timeout > 0) { #ifdef HAVE_SIGACTION if(keep_copysig) { /* we got a struct as it looked before, now put that one back nice and clean */ sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */ } #else #ifdef HAVE_SIGNAL /* restore the previous SIGALRM handler */ signal(SIGALRM, keep_sigact); #endif #endif /* HAVE_SIGACTION */ /* switch back the alarm() to either zero or to what it was before minus the time we spent until now! */ if(prev_alarm) { /* there was an alarm() set before us, now put it back */ unsigned long elapsed_ms = Curl_tvdiff(Curl_tvnow(), conn->created); /* the alarm period is counted in even number of seconds */ unsigned long alarm_set = prev_alarm - elapsed_ms/1000; if(!alarm_set || ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) { /* if the alarm time-left reached zero or turned "negative" (counted with unsigned values), we should fire off a SIGALRM here, but we won't, and zero would be to switch it off so we never set it to less than 1! */ alarm(1); rc = CURLRESOLV_TIMEDOUT; failf(data, "Previous alarm fired off!"); } else alarm((unsigned int)alarm_set); } else alarm(0); /* just shut it off */ } #endif /* USE_ALARM_TIMEOUT */ return rc; } /* * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been * made, the struct may be destroyed due to pruning. It is important that only * one unlock is made for each Curl_resolv() call. */ void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns) { DEBUGASSERT(dns && (dns->inuse>0)); if(data->share) Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE); dns->inuse--; if(data->share) Curl_share_unlock(data, CURL_LOCK_DATA_DNS); } /* * File-internal: free a cache dns entry. */ static void freednsentry(void *freethis) { struct Curl_dns_entry *p = (struct Curl_dns_entry *) freethis; if(p) { Curl_freeaddrinfo(p->addr); free(p); } } /* * Curl_mk_dnscache() creates a new DNS cache and returns the handle for it. */ struct curl_hash *Curl_mk_dnscache(void) { return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry); } #ifdef CURLRES_ADDRINFO_COPY /* align on even 64bit boundaries */ #define MEMALIGN(x) ((x)+(8-(((unsigned long)(x))&0x7))) /* * Curl_addrinfo_copy() performs a "deep" copy of a hostent into a buffer and * returns a pointer to the malloc()ed copy. You need to call free() on the * returned buffer when you're done with it. */ Curl_addrinfo *Curl_addrinfo_copy(const void *org, int port) { const struct hostent *orig = org; return Curl_he2ai(orig, port); } #endif /* CURLRES_ADDRINFO_COPY */