diff options
Diffstat (limited to 'libcurl/src/lib/hostip.c')
| -rw-r--r-- | libcurl/src/lib/hostip.c | 879 |
1 files changed, 879 insertions, 0 deletions
diff --git a/libcurl/src/lib/hostip.c b/libcurl/src/lib/hostip.c new file mode 100644 index 0000000..b58eedd --- /dev/null +++ b/libcurl/src/lib/hostip.c @@ -0,0 +1,879 @@ +/***************************************************************************
+ * _ _ ____ _
+ * Project ___| | | | _ \| |
+ * / __| | | | |_) | |
+ * | (__| |_| | _ <| |___
+ * \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2015, 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.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#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 __VMS
+#include <in.h>
+#include <inet.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"
+#include "warnless.h"
+#include "curl_printf.h"
+#include "curl_memory.h"
+/* The last #include file should be: */
+#include "memdebug.h"
+
+#if defined(CURLRES_SYNCH) && \
+ defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
+/* 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
+ * hostip4.c - IPv4 specific functions
+ * hostip6.c - IPv6 specific functions
+ *
+ * The two asynchronous name resolver backends are implemented in:
+ * asyn-ares.c - functions for ares-using name resolves
+ * asyn-thread.c - functions for threaded name resolves
+
+ * The hostip.h is the united header file for all this. It defines the
+ * CURLRES_* defines based on the config*.h and curl_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.
+ */
+CURL_STATIC 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
+ */
+CURL_STATIC 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
+ */
+CURL_STATIC 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.
+ */
+CURL_STATIC 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 provided host + port, to be used by
+ * the DNS caching.
+ */
+static char *
+create_hostcache_id(const char *name, int port)
+{
+ /* create and return the new allocated entry */
+ char *id = aprintf("%s:%d", name, port);
+ char *ptr = id;
+ if(ptr) {
+ /* lower case the name part */
+ while(*ptr && (*ptr != ':')) {
+ *ptr = (char)TOLOWER(*ptr);
+ ptr++;
+ }
+ }
+ return id;
+}
+
+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;
+
+ return (0 != c->timestamp)
+ && (data->now - c->timestamp >= data->cache_timeout);
+}
+
+/*
+ * 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.
+ */
+CURL_STATIC 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);
+}
+
+#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
+
+/* lookup address, returns entry if found and not stale */
+static struct Curl_dns_entry *
+fetch_addr(struct connectdata *conn,
+ const char *hostname,
+ int port)
+{
+ char *entry_id = NULL;
+ struct Curl_dns_entry *dns = NULL;
+ size_t entry_len;
+ struct SessionHandle *data = conn->data;
+
+ /* 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 dns;
+
+ entry_len = strlen(entry_id);
+
+ /* See if its already in our dns cache */
+ dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len+1);
+
+ if(dns && (data->set.dns_cache_timeout != -1)) {
+ /* See whether the returned entry is stale. Done before we release lock */
+ struct hostcache_prune_data user;
+
+ time(&user.now);
+ user.cache_timeout = data->set.dns_cache_timeout;
+
+ if(hostcache_timestamp_remove(&user, dns)) {
+ infof(data, "Hostname in DNS cache was stale, zapped\n");
+ dns = NULL; /* the memory deallocation is being handled by the hash */
+ Curl_hash_delete(data->dns.hostcache, entry_id, entry_len+1);
+ }
+ }
+
+ /* free the allocated entry_id again */
+ free(entry_id);
+
+ return dns;
+}
+
+/*
+ * Curl_fetch_addr() fetches a 'Curl_dns_entry' already in the DNS cache.
+ *
+ * Curl_resolv() checks initially and multi_runsingle() checks each time
+ * it discovers the handle in the state WAITRESOLVE whether the hostname
+ * has already been resolved and the address has already been stored in
+ * the DNS cache. This short circuits waiting for a lot of pending
+ * lookups for the same hostname requested by different handles.
+ *
+ * Returns the Curl_dns_entry entry pointer or NULL if not in the cache.
+ *
+ * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after
+ * use, or we'll leak memory!
+ */
+CURL_STATIC struct Curl_dns_entry *
+Curl_fetch_addr(struct connectdata *conn,
+ const char *hostname,
+ int port)
+{
+ struct SessionHandle *data = conn->data;
+ struct Curl_dns_entry *dns = NULL;
+
+ if(data->share)
+ Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+ dns = fetch_addr(conn, hostname, port);
+
+ if(dns) dns->inuse++; /* we use it! */
+
+ if(data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+ return dns;
+}
+
+/*
+ * 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.
+ */
+CURL_STATIC 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;
+
+ /* 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(1, sizeof(struct Curl_dns_entry));
+ if(!dns) {
+ free(entry_id);
+ return NULL;
+ }
+
+ dns->inuse = 1; /* the cache has the first reference */
+ dns->addr = addr; /* this is the address(es) */
+ time(&dns->timestamp);
+ if(dns->timestamp == 0)
+ dns->timestamp = 1; /* zero indicates CURLOPT_RESOLVE entry */
+
+ /* Store the resolved data in our DNS cache. */
+ dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len+1,
+ (void *)dns);
+ if(!dns2) {
+ free(dns);
+ free(entry_id);
+ return NULL;
+ }
+
+ dns = dns2;
+ dns->inuse++; /* mark entry as in-use */
+
+ /* free the allocated entry_id */
+ 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
+ */
+
+CURL_STATIC int Curl_resolv(struct connectdata *conn,
+ const char *hostname,
+ int port,
+ struct Curl_dns_entry **entry)
+{
+ struct Curl_dns_entry *dns = NULL;
+ struct SessionHandle *data = conn->data;
+ CURLcode result;
+ int rc = CURLRESOLV_ERROR; /* default to failure */
+
+ *entry = NULL;
+
+ if(data->share)
+ Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+ dns = fetch_addr(conn, hostname, port);
+
+ if(dns) {
+ infof(data, "Hostname %s was found in DNS cache\n", hostname);
+ dns->inuse++; /* we use it! */
+ rc = CURLRESOLV_RESOLVED;
+ }
+
+ if(data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+ 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(conn))
+ 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_resolver_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
+ */
+
+CURL_STATIC 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 */
+ volatile bool keep_copysig = FALSE; /* wether old sigact has been saved */
+ 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;
+ volatile unsigned int prev_alarm = 0;
+ struct SessionHandle *data = conn->data;
+#endif /* USE_ALARM_TIMEOUT */
+ int rc;
+
+ *entry = NULL;
+
+ if(timeoutms < 0)
+ /* got an already expired timeout */
+ return CURLRESOLV_TIMEDOUT;
+
+#ifdef USE_ALARM_TIMEOUT
+ if(data->set.no_signal)
+ /* Ignore the timeout when signals are disabled */
+ timeout = 0;
+ else
+ timeout = timeoutms;
+
+ if(!timeout)
+ /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
+ return Curl_resolv(conn, hostname, port, entry);
+
+ if(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;
+
+ /* 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).
+ This should be the last thing we do before calling Curl_resolv(),
+ as otherwise we'd have to worry about variables that get modified
+ before we invoke Curl_resolv() (and thus use "volatile"). */
+ if(sigsetjmp(curl_jmpenv, 1)) {
+ /* this is coming from a siglongjmp() after an alarm signal */
+ failf(data, "name lookup timed out");
+ rc = CURLRESOLV_ERROR;
+ goto clean_up;
+ }
+ else {
+ /*************************************************************
+ * 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(curlx_sltoui(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
+clean_up:
+
+ if(!prev_alarm)
+ /* deactivate a possibly active alarm before uninstalling the handler */
+ alarm(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);
+ }
+#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.
+ *
+ * May be called with 'data' == NULL for global cache.
+ */
+CURL_STATIC void Curl_resolv_unlock(struct SessionHandle *data, struct Curl_dns_entry *dns)
+{
+ if(data && data->share)
+ Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+ freednsentry(dns);
+
+ if(data && data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+}
+
+/*
+ * File-internal: release cache dns entry reference, free if inuse drops to 0
+ */
+static void freednsentry(void *freethis)
+{
+ struct Curl_dns_entry *dns = (struct Curl_dns_entry *) freethis;
+ DEBUGASSERT(dns && (dns->inuse>0));
+
+ dns->inuse--;
+ if(dns->inuse == 0) {
+ Curl_freeaddrinfo(dns->addr);
+ free(dns);
+ }
+}
+
+/*
+ * Curl_mk_dnscache() creates a new DNS cache and returns the handle for it.
+ */
+CURL_STATIC struct curl_hash *Curl_mk_dnscache(void)
+{
+ return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);
+}
+
+/*
+ * Curl_hostcache_clean()
+ *
+ * This _can_ be called with 'data' == NULL but then of course no locking
+ * can be done!
+ */
+
+CURL_STATIC void Curl_hostcache_clean(struct SessionHandle *data,
+ struct curl_hash *hash)
+{
+ if(data && data->share)
+ Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+ Curl_hash_clean(hash);
+
+ if(data && data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+}
+
+
+CURL_STATIC CURLcode Curl_loadhostpairs(struct SessionHandle *data)
+{
+ struct curl_slist *hostp;
+ char hostname[256];
+ char address[256];
+ int port;
+
+ for(hostp = data->change.resolve; hostp; hostp = hostp->next ) {
+ if(!hostp->data)
+ continue;
+ if(hostp->data[0] == '-') {
+ char *entry_id;
+ size_t entry_len;
+
+ if(2 != sscanf(hostp->data + 1, "%255[^:]:%d", hostname, &port)) {
+ infof(data, "Couldn't parse CURLOPT_RESOLVE removal entry '%s'!\n",
+ hostp->data);
+ continue;
+ }
+
+ /* 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 CURLE_OUT_OF_MEMORY;
+ }
+
+ entry_len = strlen(entry_id);
+
+ if(data->share)
+ Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+ /* delete entry, ignore if it didn't exist */
+ Curl_hash_delete(data->dns.hostcache, entry_id, entry_len+1);
+
+ if(data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+ /* free the allocated entry_id again */
+ free(entry_id);
+ }
+ else {
+ struct Curl_dns_entry *dns;
+ Curl_addrinfo *addr;
+ char *entry_id;
+ size_t entry_len;
+
+ if(3 != sscanf(hostp->data, "%255[^:]:%d:%255s", hostname, &port,
+ address)) {
+ infof(data, "Couldn't parse CURLOPT_RESOLVE entry '%s'!\n",
+ hostp->data);
+ continue;
+ }
+
+ addr = Curl_str2addr(address, port);
+ if(!addr) {
+ infof(data, "Address in '%s' found illegal!\n", hostp->data);
+ continue;
+ }
+
+ /* 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) {
+ Curl_freeaddrinfo(addr);
+ return CURLE_OUT_OF_MEMORY;
+ }
+
+ 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);
+
+ /* free the allocated entry_id again */
+ free(entry_id);
+
+ if(!dns) {
+ /* if not in the cache already, put this host in the cache */
+ dns = Curl_cache_addr(data, addr, hostname, port);
+ if(dns) {
+ dns->timestamp = 0; /* mark as added by CURLOPT_RESOLVE */
+ /* release the returned reference; the cache itself will keep the
+ * entry alive: */
+ dns->inuse--;
+ }
+ }
+ else
+ /* this is a duplicate, free it again */
+ Curl_freeaddrinfo(addr);
+
+ if(data->share)
+ Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+ if(!dns) {
+ Curl_freeaddrinfo(addr);
+ return CURLE_OUT_OF_MEMORY;
+ }
+ infof(data, "Added %s:%d:%s to DNS cache\n",
+ hostname, port, address);
+ }
+ }
+ data->change.resolve = NULL; /* dealt with now */
+
+ return CURLE_OK;
+}
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