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curl/lib/asyn-ares.c
Maxim Prohorov 97386c3c84 resolve with c-ares: don't resolve IPv6 when not working 
If the Curl_ipv6works() function says no, there is no reason to try AAAA
names even if libcurl was built with IPv6 support enabled.

Bug: http://curl.haxx.se/mail/lib-2012-03/0045.html
2012-03-13 22:52:39 +01:00

644 lines
18 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2011, 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 "setup.h"
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#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_UNISTD_H
#include <unistd.h> /* for the close() proto */
#endif
#ifdef __VMS
#include <in.h>
#include <inet.h>
#endif
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif
#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif
/***********************************************************************
* Only for ares-enabled builds
* And only for functions that fulfill the asynch resolver backend API
* as defined in asyn.h, nothing else belongs in this file!
**********************************************************************/
#ifdef CURLRES_ARES
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.h"
#include "multiif.h"
#include "inet_pton.h"
#include "connect.h"
#include "select.h"
#include "progress.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
# if defined(CURL_STATICLIB) && !defined(CARES_STATICLIB) && \
(defined(WIN32) || defined(_WIN32) || defined(__SYMBIAN32__))
# define CARES_STATICLIB
# endif
# include <ares.h>
#if ARES_VERSION >= 0x010500
/* c-ares 1.5.0 or later, the callback proto is modified */
#define HAVE_CARES_CALLBACK_TIMEOUTS 1
#endif
#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"
struct ResolverResults {
int num_pending; /* number of ares_gethostbyname() requests */
Curl_addrinfo *temp_ai; /* intermediary result while fetching c-ares parts */
int last_status;
};
/*
* Curl_resolver_global_init() - the generic low-level asynchronous name
* resolve API. Called from curl_global_init() to initialize global resolver
* environment. Initializes ares library.
*/
int Curl_resolver_global_init(void)
{
#ifdef CARES_HAVE_ARES_LIBRARY_INIT
if(ares_library_init(ARES_LIB_INIT_ALL)) {
return CURLE_FAILED_INIT;
}
#endif
return CURLE_OK;
}
/*
* Curl_resolver_global_cleanup()
*
* Called from curl_global_cleanup() to destroy global resolver environment.
* Deinitializes ares library.
*/
void Curl_resolver_global_cleanup(void)
{
#ifdef CARES_HAVE_ARES_LIBRARY_CLEANUP
ares_library_cleanup();
#endif
}
/*
* Curl_resolver_init()
*
* Called from curl_easy_init() -> Curl_open() to initialize resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure). Fills the passed pointer by the initialized ares_channel.
*/
CURLcode Curl_resolver_init(void **resolver)
{
int status = ares_init((ares_channel*)resolver);
if(status != ARES_SUCCESS) {
if(status == ARES_ENOMEM)
return CURLE_OUT_OF_MEMORY;
else
return CURLE_FAILED_INIT;
}
return CURLE_OK;
/* make sure that all other returns from this function should destroy the
ares channel before returning error! */
}
/*
* Curl_resolver_cleanup()
*
* Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure). Destroys the ares channel.
*/
void Curl_resolver_cleanup(void *resolver)
{
ares_destroy((ares_channel)resolver);
}
/*
* Curl_resolver_duphandle()
*
* Called from curl_easy_duphandle() to duplicate resolver URL-state specific
* environment ('resolver' member of the UrlState structure). Duplicates the
* 'from' ares channel and passes the resulting channel to the 'to' pointer.
*/
int Curl_resolver_duphandle(void **to, void *from)
{
/* Clone the ares channel for the new handle */
if(ARES_SUCCESS != ares_dup((ares_channel*)to,(ares_channel)from))
return CURLE_FAILED_INIT;
return CURLE_OK;
}
static void destroy_async_data (struct Curl_async *async);
/*
* Cancel all possibly still on-going resolves for this connection.
*/
void Curl_resolver_cancel(struct connectdata *conn)
{
if(conn && conn->data && conn->data->state.resolver)
ares_cancel((ares_channel)conn->data->state.resolver);
destroy_async_data(&conn->async);
}
/*
* destroy_async_data() cleans up async resolver data.
*/
static void destroy_async_data (struct Curl_async *async)
{
if(async->hostname)
free(async->hostname);
if(async->os_specific) {
struct ResolverResults *res = (struct ResolverResults *)async->os_specific;
if(res) {
if(res->temp_ai) {
Curl_freeaddrinfo(res->temp_ai);
res->temp_ai = NULL;
}
free(res);
}
async->os_specific = NULL;
}
async->hostname = NULL;
}
/*
* Curl_resolver_fdset() is called when someone from the outside world (using
* curl_multi_fdset()) wants to get our fd_set setup and we're talking with
* ares. The caller must make sure that this function is only called when we
* have a working ares channel.
*
* Returns: CURLE_OK always!
*/
int Curl_resolver_getsock(struct connectdata *conn,
curl_socket_t *socks,
int numsocks)
{
struct timeval maxtime;
struct timeval timebuf;
struct timeval *timeout;
long milli;
int max = ares_getsock((ares_channel)conn->data->state.resolver,
(ares_socket_t *)socks, numsocks);
maxtime.tv_sec = CURL_TIMEOUT_RESOLVE;
maxtime.tv_usec = 0;
timeout = ares_timeout((ares_channel)conn->data->state.resolver, &maxtime,
&timebuf);
milli = (timeout->tv_sec * 1000) + (timeout->tv_usec/1000);
if(milli == 0)
milli += 10;
Curl_expire(conn->data, milli);
return max;
}
/*
* waitperform()
*
* 1) Ask ares what sockets it currently plays with, then
* 2) wait for the timeout period to check for action on ares' sockets.
* 3) tell ares to act on all the sockets marked as "with action"
*
* return number of sockets it worked on
*/
static int waitperform(struct connectdata *conn, int timeout_ms)
{
struct SessionHandle *data = conn->data;
int nfds;
int bitmask;
ares_socket_t socks[ARES_GETSOCK_MAXNUM];
struct pollfd pfd[ARES_GETSOCK_MAXNUM];
int i;
int num = 0;
bitmask = ares_getsock((ares_channel)data->state.resolver, socks,
ARES_GETSOCK_MAXNUM);
for(i=0; i < ARES_GETSOCK_MAXNUM; i++) {
pfd[i].events = 0;
pfd[i].revents = 0;
if(ARES_GETSOCK_READABLE(bitmask, i)) {
pfd[i].fd = socks[i];
pfd[i].events |= POLLRDNORM|POLLIN;
}
if(ARES_GETSOCK_WRITABLE(bitmask, i)) {
pfd[i].fd = socks[i];
pfd[i].events |= POLLWRNORM|POLLOUT;
}
if(pfd[i].events != 0)
num++;
else
break;
}
if(num)
nfds = Curl_poll(pfd, num, timeout_ms);
else
nfds = 0;
if(!nfds)
/* Call ares_process() unconditonally here, even if we simply timed out
above, as otherwise the ares name resolve won't timeout! */
ares_process_fd((ares_channel)data->state.resolver, ARES_SOCKET_BAD,
ARES_SOCKET_BAD);
else {
/* move through the descriptors and ask for processing on them */
for(i=0; i < num; i++)
ares_process_fd((ares_channel)data->state.resolver,
pfd[i].revents & (POLLRDNORM|POLLIN)?
pfd[i].fd:ARES_SOCKET_BAD,
pfd[i].revents & (POLLWRNORM|POLLOUT)?
pfd[i].fd:ARES_SOCKET_BAD);
}
return nfds;
}
/*
* Curl_resolver_is_resolved() is called repeatedly to check if a previous
* name resolve request has completed. It should also make sure to time-out if
* the operation seems to take too long.
*
* Returns normal CURLcode errors.
*/
CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
struct Curl_dns_entry **dns)
{
struct SessionHandle *data = conn->data;
struct ResolverResults *res = (struct ResolverResults *)
conn->async.os_specific;
*dns = NULL;
waitperform(conn, 0);
if(res && !res->num_pending) {
(void)Curl_addrinfo_callback(conn, res->last_status, res->temp_ai);
/* temp_ai ownership is moved to the connection, so we need not free-up
them */
res->temp_ai = NULL;
destroy_async_data(&conn->async);
if(!conn->async.dns) {
failf(data, "Could not resolve %s: %s (%s)",
conn->bits.proxy?"proxy":"host",
conn->host.dispname,
ares_strerror(conn->async.status));
return conn->bits.proxy?CURLE_COULDNT_RESOLVE_PROXY:
CURLE_COULDNT_RESOLVE_HOST;
}
*dns = conn->async.dns;
}
return CURLE_OK;
}
/*
* Curl_resolver_wait_resolv()
*
* waits for a resolve to finish. This function should be avoided since using
* this risk getting the multi interface to "hang".
*
* If 'entry' is non-NULL, make it point to the resolved dns entry
*
* Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved, and
* CURLE_OPERATION_TIMEDOUT if a time-out occurred.
*/
CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
struct Curl_dns_entry **entry)
{
CURLcode rc=CURLE_OK;
struct SessionHandle *data = conn->data;
long timeout;
struct timeval now = Curl_tvnow();
struct Curl_dns_entry *temp_entry;
timeout = Curl_timeleft(data, &now, TRUE);
if(!timeout)
timeout = CURL_TIMEOUT_RESOLVE * 1000; /* default name resolve timeout */
/* Wait for the name resolve query to complete. */
for(;;) {
struct timeval *tvp, tv, store;
long timediff;
int itimeout;
int timeout_ms;
itimeout = (timeout > (long)INT_MAX) ? INT_MAX : (int)timeout;
store.tv_sec = itimeout/1000;
store.tv_usec = (itimeout%1000)*1000;
tvp = ares_timeout((ares_channel)data->state.resolver, &store, &tv);
/* use the timeout period ares returned to us above if less than one
second is left, otherwise just use 1000ms to make sure the progress
callback gets called frequent enough */
if(!tvp->tv_sec)
timeout_ms = (int)(tvp->tv_usec/1000);
else
timeout_ms = 1000;
waitperform(conn, timeout_ms);
Curl_resolver_is_resolved(conn,&temp_entry);
if(conn->async.done)
break;
if(Curl_pgrsUpdate(conn)) {
rc = CURLE_ABORTED_BY_CALLBACK;
timeout = -1; /* trigger the cancel below */
}
else {
struct timeval now2 = Curl_tvnow();
timediff = Curl_tvdiff(now2, now); /* spent time */
timeout -= timediff?timediff:1; /* always deduct at least 1 */
now = now2; /* for next loop */
}
if(timeout < 0) {
/* our timeout, so we cancel the ares operation */
ares_cancel((ares_channel)data->state.resolver);
break;
}
}
/* Operation complete, if the lookup was successful we now have the entry
in the cache. */
if(entry)
*entry = conn->async.dns;
if(!conn->async.dns) {
/* a name was not resolved */
if((timeout < 0) || (conn->async.status == ARES_ETIMEOUT)) {
if(conn->bits.proxy) {
failf(data, "Resolving proxy timed out: %s", conn->proxy.dispname);
rc = CURLE_COULDNT_RESOLVE_PROXY;
}
else {
failf(data, "Resolving host timed out: %s", conn->host.dispname);
rc = CURLE_COULDNT_RESOLVE_HOST;
}
}
else if(conn->async.done) {
if(conn->bits.proxy) {
failf(data, "Could not resolve proxy: %s (%s)", conn->proxy.dispname,
ares_strerror(conn->async.status));
rc = CURLE_COULDNT_RESOLVE_PROXY;
}
else {
failf(data, "Could not resolve host: %s (%s)", conn->host.dispname,
ares_strerror(conn->async.status));
rc = CURLE_COULDNT_RESOLVE_HOST;
}
}
else
rc = CURLE_OPERATION_TIMEDOUT;
/* close the connection, since we can't return failure here without
cleaning up this connection properly */
conn->bits.close = TRUE;
}
return rc;
}
/* Connects results to the list */
static void compound_results(struct ResolverResults *res,
Curl_addrinfo *ai)
{
Curl_addrinfo *ai_tail;
if(!ai)
return;
ai_tail = ai;
while(ai_tail->ai_next)
ai_tail = ai_tail->ai_next;
/* Add the new results to the list of old results. */
ai_tail->ai_next = res->temp_ai;
res->temp_ai = ai;
}
/*
* ares_query_completed_cb() is the callback that ares will call when
* the host query initiated by ares_gethostbyname() from Curl_getaddrinfo(),
* when using ares, is completed either successfully or with failure.
*/
static void query_completed_cb(void *arg, /* (struct connectdata *) */
int status,
#ifdef HAVE_CARES_CALLBACK_TIMEOUTS
int timeouts,
#endif
struct hostent *hostent)
{
struct connectdata *conn = (struct connectdata *)arg;
struct ResolverResults *res;
#ifdef HAVE_CARES_CALLBACK_TIMEOUTS
(void)timeouts; /* ignored */
#endif
if(ARES_EDESTRUCTION == status)
/* when this ares handle is getting destroyed, the 'arg' pointer may not
be valid so only defer it when we know the 'status' says its fine! */
return;
res = (struct ResolverResults *)conn->async.os_specific;
res->num_pending--;
if(CURL_ASYNC_SUCCESS == status) {
Curl_addrinfo *ai = Curl_he2ai(hostent, conn->async.port);
if(ai) {
compound_results(res, ai);
}
}
/* A successful result overwrites any previous error */
if(res->last_status != ARES_SUCCESS)
res->last_status = status;
}
/*
* Curl_resolver_getaddrinfo() - when using ares
*
* Returns name information about the given hostname and port number. If
* successful, the 'hostent' is returned and the forth argument will point to
* memory we need to free after use. That memory *MUST* be freed with
* Curl_freeaddrinfo(), nothing else.
*/
Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
const char *hostname,
int port,
int *waitp)
{
char *bufp;
struct SessionHandle *data = conn->data;
struct in_addr in;
int family = PF_INET;
#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
struct in6_addr in6;
#endif /* CURLRES_IPV6 */
*waitp = 0; /* default to synchronous response */
/* First check if this is an IPv4 address string */
if(Curl_inet_pton(AF_INET, hostname, &in) > 0) {
/* This is a dotted IP address 123.123.123.123-style */
return Curl_ip2addr(AF_INET, &in, hostname, port);
}
#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
/* Otherwise, check if this is an IPv6 address string */
if(Curl_inet_pton (AF_INET6, hostname, &in6) > 0)
/* This must be an IPv6 address literal. */
return Curl_ip2addr(AF_INET6, &in6, hostname, port);
switch(conn->ip_version) {
default:
#if ARES_VERSION >= 0x010601
family = PF_UNSPEC; /* supported by c-ares since 1.6.1, so for older
c-ares versions this just falls through and defaults
to PF_INET */
break;
#endif
case CURL_IPRESOLVE_V4:
family = PF_INET;
break;
case CURL_IPRESOLVE_V6:
family = PF_INET6;
break;
}
#endif /* CURLRES_IPV6 */
bufp = strdup(hostname);
if(bufp) {
struct ResolverResults *res = NULL;
Curl_safefree(conn->async.hostname);
conn->async.hostname = bufp;
conn->async.port = port;
conn->async.done = FALSE; /* not done */
conn->async.status = 0; /* clear */
conn->async.dns = NULL; /* clear */
res = calloc(sizeof(struct ResolverResults),1);
if(!res) {
Curl_safefree(conn->async.hostname);
conn->async.hostname = NULL;
return NULL;
}
conn->async.os_specific = res;
/* initial status - failed */
res->last_status = ARES_ENOTFOUND;
#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
if(family == PF_UNSPEC) {
if(Curl_ipv6works()) {
res->num_pending = 2;
/* areschannel is already setup in the Curl_open() function */
ares_gethostbyname((ares_channel)data->state.resolver, hostname,
PF_INET, query_completed_cb, conn);
ares_gethostbyname((ares_channel)data->state.resolver, hostname,
PF_INET6, query_completed_cb, conn);
}
else {
res->num_pending = 1;
/* areschannel is already setup in the Curl_open() function */
ares_gethostbyname((ares_channel)data->state.resolver, hostname,
PF_INET, query_completed_cb, conn);
}
}
else
#endif /* CURLRES_IPV6 */
{
res->num_pending = 1;
/* areschannel is already setup in the Curl_open() function */
ares_gethostbyname((ares_channel)data->state.resolver, hostname, family,
query_completed_cb, conn);
}
*waitp = 1; /* expect asynchronous response */
}
return NULL; /* no struct yet */
}
CURLcode Curl_set_dns_servers(struct SessionHandle *data,
char *servers)
{
CURLcode result = CURLE_NOT_BUILT_IN;
#if (ARES_VERSION >= 0x010704)
int ares_result = ares_set_servers_csv(data->state.resolver, servers);
switch(ares_result) {
case ARES_SUCCESS:
result = CURLE_OK;
break;
case ARES_ENOMEM:
result = CURLE_OUT_OF_MEMORY;
break;
case ARES_ENOTINITIALIZED:
case ARES_ENODATA:
case ARES_EBADSTR:
default:
result = CURLE_BAD_FUNCTION_ARGUMENT;
break;
}
#else /* too old c-ares version! */
(void)data;
(void)servers;
#endif
return result;
}
#endif /* CURLRES_ARES */
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