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curl/lib/asyn-thread.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2021, 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 https://curl.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"
#include "socketpair.h"
/***********************************************************************
* Only for threaded name resolves builds
**********************************************************************/
#ifdef CURLRES_THREADED
#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
#if defined(USE_THREADS_POSIX)
# ifdef HAVE_PTHREAD_H
# include <pthread.h>
# endif
#elif defined(USE_THREADS_WIN32)
# ifdef HAVE_PROCESS_H
# include <process.h>
# endif
#endif
#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif
#ifdef HAVE_GETADDRINFO
# define RESOLVER_ENOMEM EAI_MEMORY
#else
# define RESOLVER_ENOMEM ENOMEM
#endif
#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "url.h"
#include "multiif.h"
#include "inet_ntop.h"
#include "curl_threads.h"
#include "connect.h"
#include "socketpair.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
struct resdata {
struct curltime start;
};
/*
* Curl_resolver_global_init()
* Called from curl_global_init() to initialize global resolver environment.
* Does nothing here.
*/
int Curl_resolver_global_init(void)
{
return CURLE_OK;
}
/*
* Curl_resolver_global_cleanup()
* Called from curl_global_cleanup() to destroy global resolver environment.
* Does nothing here.
*/
void Curl_resolver_global_cleanup(void)
{
}
/*
* Curl_resolver_init()
* Called from curl_easy_init() -> Curl_open() to initialize resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure).
*/
CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver)
{
(void)easy;
*resolver = calloc(1, sizeof(struct resdata));
if(!*resolver)
return CURLE_OUT_OF_MEMORY;
return CURLE_OK;
}
/*
* Curl_resolver_cleanup()
* Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure).
*/
void Curl_resolver_cleanup(void *resolver)
{
free(resolver);
}
/*
* Curl_resolver_duphandle()
* Called from curl_easy_duphandle() to duplicate resolver URL state-specific
* environment ('resolver' member of the UrlState structure).
*/
CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to, void *from)
{
(void)from;
return Curl_resolver_init(easy, to);
}
static void destroy_async_data(struct Curl_async *);
/*
* Cancel all possibly still on-going resolves for this connection.
*/
void Curl_resolver_cancel(struct Curl_easy *data)
{
destroy_async_data(&data->state.async);
}
/* This function is used to init a threaded resolve */
static bool init_resolve_thread(struct Curl_easy *data,
const char *hostname, int port,
const struct addrinfo *hints);
/* Data for synchronization between resolver thread and its parent */
struct thread_sync_data {
curl_mutex_t *mtx;
int done;
int port;
char *hostname; /* hostname to resolve, Curl_async.hostname
duplicate */
#ifndef CURL_DISABLE_SOCKETPAIR
struct Curl_easy *data;
curl_socket_t sock_pair[2]; /* socket pair */
#endif
int sock_error;
struct Curl_addrinfo *res;
#ifdef HAVE_GETADDRINFO
struct addrinfo hints;
#endif
struct thread_data *td; /* for thread-self cleanup */
};
struct thread_data {
curl_thread_t thread_hnd;
unsigned int poll_interval;
timediff_t interval_end;
struct thread_sync_data tsd;
};
static struct thread_sync_data *conn_thread_sync_data(struct Curl_easy *data)
{
return &(data->state.async.tdata->tsd);
}
/* Destroy resolver thread synchronization data */
static
void destroy_thread_sync_data(struct thread_sync_data *tsd)
{
if(tsd->mtx) {
Curl_mutex_destroy(tsd->mtx);
free(tsd->mtx);
}
free(tsd->hostname);
if(tsd->res)
Curl_freeaddrinfo(tsd->res);
#ifndef CURL_DISABLE_SOCKETPAIR
/*
* close one end of the socket pair (may be done in resolver thread);
* the other end (for reading) is always closed in the parent thread.
*/
if(tsd->sock_pair[1] != CURL_SOCKET_BAD) {
sclose(tsd->sock_pair[1]);
}
#endif
memset(tsd, 0, sizeof(*tsd));
}
/* Initialize resolver thread synchronization data */
static
int init_thread_sync_data(struct thread_data *td,
const char *hostname,
int port,
const struct addrinfo *hints)
{
struct thread_sync_data *tsd = &td->tsd;
memset(tsd, 0, sizeof(*tsd));
tsd->td = td;
tsd->port = port;
/* Treat the request as done until the thread actually starts so any early
* cleanup gets done properly.
*/
tsd->done = 1;
#ifdef HAVE_GETADDRINFO
DEBUGASSERT(hints);
tsd->hints = *hints;
#else
(void) hints;
#endif
tsd->mtx = malloc(sizeof(curl_mutex_t));
if(!tsd->mtx)
goto err_exit;
Curl_mutex_init(tsd->mtx);
#ifndef CURL_DISABLE_SOCKETPAIR
/* create socket pair, avoid AF_LOCAL since it doesn't build on Solaris */
if(Curl_socketpair(AF_UNIX, SOCK_STREAM, 0, &tsd->sock_pair[0]) < 0) {
tsd->sock_pair[0] = CURL_SOCKET_BAD;
tsd->sock_pair[1] = CURL_SOCKET_BAD;
goto err_exit;
}
#endif
tsd->sock_error = CURL_ASYNC_SUCCESS;
/* Copying hostname string because original can be destroyed by parent
* thread during gethostbyname execution.
*/
tsd->hostname = strdup(hostname);
if(!tsd->hostname)
goto err_exit;
return 1;
err_exit:
/* Memory allocation failed */
destroy_thread_sync_data(tsd);
return 0;
}
static int getaddrinfo_complete(struct Curl_easy *data)
{
struct thread_sync_data *tsd = conn_thread_sync_data(data);
int rc;
rc = Curl_addrinfo_callback(data, tsd->sock_error, tsd->res);
/* The tsd->res structure has been copied to async.dns and perhaps the DNS
cache. Set our copy to NULL so destroy_thread_sync_data doesn't free it.
*/
tsd->res = NULL;
return rc;
}
#ifdef HAVE_GETADDRINFO
/*
* getaddrinfo_thread() resolves a name and then exits.
*
* For builds without ARES, but with ENABLE_IPV6, create a resolver thread
* and wait on it.
*/
static unsigned int CURL_STDCALL getaddrinfo_thread(void *arg)
{
struct thread_sync_data *tsd = (struct thread_sync_data *)arg;
struct thread_data *td = tsd->td;
char service[12];
int rc;
#ifndef CURL_DISABLE_SOCKETPAIR
char buf[1];
#endif
msnprintf(service, sizeof(service), "%d", tsd->port);
rc = Curl_getaddrinfo_ex(tsd->hostname, service, &tsd->hints, &tsd->res);
if(rc) {
tsd->sock_error = SOCKERRNO?SOCKERRNO:rc;
if(tsd->sock_error == 0)
tsd->sock_error = RESOLVER_ENOMEM;
}
else {
Curl_addrinfo_set_port(tsd->res, tsd->port);
}
Curl_mutex_acquire(tsd->mtx);
if(tsd->done) {
/* too late, gotta clean up the mess */
Curl_mutex_release(tsd->mtx);
destroy_thread_sync_data(tsd);
free(td);
}
else {
#ifndef CURL_DISABLE_SOCKETPAIR
if(tsd->sock_pair[1] != CURL_SOCKET_BAD) {
/* DNS has been resolved, signal client task */
buf[0] = 1;
if(swrite(tsd->sock_pair[1], buf, sizeof(buf)) < 0) {
/* update sock_erro to errno */
tsd->sock_error = SOCKERRNO;
}
}
#endif
tsd->done = 1;
Curl_mutex_release(tsd->mtx);
}
return 0;
}
#else /* HAVE_GETADDRINFO */
/*
* gethostbyname_thread() resolves a name and then exits.
*/
static unsigned int CURL_STDCALL gethostbyname_thread(void *arg)
{
struct thread_sync_data *tsd = (struct thread_sync_data *)arg;
struct thread_data *td = tsd->td;
tsd->res = Curl_ipv4_resolve_r(tsd->hostname, tsd->port);
if(!tsd->res) {
tsd->sock_error = SOCKERRNO;
if(tsd->sock_error == 0)
tsd->sock_error = RESOLVER_ENOMEM;
}
Curl_mutex_acquire(tsd->mtx);
if(tsd->done) {
/* too late, gotta clean up the mess */
Curl_mutex_release(tsd->mtx);
destroy_thread_sync_data(tsd);
free(td);
}
else {
tsd->done = 1;
Curl_mutex_release(tsd->mtx);
}
return 0;
}
#endif /* HAVE_GETADDRINFO */
/*
* destroy_async_data() cleans up async resolver data and thread handle.
*/
static void destroy_async_data(struct Curl_async *async)
{
if(async->tdata) {
struct thread_data *td = async->tdata;
int done;
#ifndef CURL_DISABLE_SOCKETPAIR
curl_socket_t sock_rd = td->tsd.sock_pair[0];
struct Curl_easy *data = td->tsd.data;
#endif
/*
* if the thread is still blocking in the resolve syscall, detach it and
* let the thread do the cleanup...
*/
Curl_mutex_acquire(td->tsd.mtx);
done = td->tsd.done;
td->tsd.done = 1;
Curl_mutex_release(td->tsd.mtx);
if(!done) {
Curl_thread_destroy(td->thread_hnd);
}
else {
if(td->thread_hnd != curl_thread_t_null)
Curl_thread_join(&td->thread_hnd);
destroy_thread_sync_data(&td->tsd);
free(async->tdata);
}
#ifndef CURL_DISABLE_SOCKETPAIR
/*
* ensure CURLMOPT_SOCKETFUNCTION fires CURL_POLL_REMOVE
* before the FD is invalidated to avoid EBADF on EPOLL_CTL_DEL
*/
Curl_multi_closed(data, sock_rd);
sclose(sock_rd);
#endif
}
async->tdata = NULL;
free(async->hostname);
async->hostname = NULL;
}
/*
* init_resolve_thread() starts a new thread that performs the actual
* resolve. This function returns before the resolve is done.
*
* Returns FALSE in case of failure, otherwise TRUE.
*/
static bool init_resolve_thread(struct Curl_easy *data,
const char *hostname, int port,
const struct addrinfo *hints)
{
struct thread_data *td = calloc(1, sizeof(struct thread_data));
int err = ENOMEM;
struct Curl_async *asp = &data->state.async;
data->state.async.tdata = td;
if(!td)
goto errno_exit;
asp->port = port;
asp->done = FALSE;
asp->status = 0;
asp->dns = NULL;
td->thread_hnd = curl_thread_t_null;
if(!init_thread_sync_data(td, hostname, port, hints)) {
asp->tdata = NULL;
free(td);
goto errno_exit;
}
free(asp->hostname);
asp->hostname = strdup(hostname);
if(!asp->hostname)
goto err_exit;
/* The thread will set this to 1 when complete. */
td->tsd.done = 0;
#ifdef HAVE_GETADDRINFO
td->thread_hnd = Curl_thread_create(getaddrinfo_thread, &td->tsd);
#else
td->thread_hnd = Curl_thread_create(gethostbyname_thread, &td->tsd);
#endif
if(!td->thread_hnd) {
/* The thread never started, so mark it as done here for proper cleanup. */
td->tsd.done = 1;
err = errno;
goto err_exit;
}
return TRUE;
err_exit:
destroy_async_data(asp);
errno_exit:
errno = err;
return FALSE;
}
/*
* 'entry' may be NULL and then no data is returned
*/
static CURLcode thread_wait_resolv(struct Curl_easy *data,
struct Curl_dns_entry **entry,
bool report)
{
struct thread_data *td;
CURLcode result = CURLE_OK;
DEBUGASSERT(data);
td = data->state.async.tdata;
DEBUGASSERT(td);
DEBUGASSERT(td->thread_hnd != curl_thread_t_null);
/* wait for the thread to resolve the name */
if(Curl_thread_join(&td->thread_hnd)) {
if(entry)
result = getaddrinfo_complete(data);
}
else
DEBUGASSERT(0);
data->state.async.done = TRUE;
if(entry)
*entry = data->state.async.dns;
if(!data->state.async.dns && report)
/* a name was not resolved, report error */
result = Curl_resolver_error(data);
destroy_async_data(&data->state.async);
if(!data->state.async.dns && report)
connclose(data->conn, "asynch resolve failed");
return result;
}
/*
* Until we gain a way to signal the resolver threads to stop early, we must
* simply wait for them and ignore their results.
*/
void Curl_resolver_kill(struct Curl_easy *data)
{
struct thread_data *td = data->state.async.tdata;
/* If we're still resolving, we must wait for the threads to fully clean up,
unfortunately. Otherwise, we can simply cancel to clean up any resolver
data. */
if(td && td->thread_hnd != curl_thread_t_null)
(void)thread_wait_resolv(data, NULL, FALSE);
else
Curl_resolver_cancel(data);
}
/*
* 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,
* CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
*
* This is the version for resolves-in-a-thread.
*/
CURLcode Curl_resolver_wait_resolv(struct Curl_easy *data,
struct Curl_dns_entry **entry)
{
return thread_wait_resolv(data, entry, TRUE);
}
/*
* 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.
*/
CURLcode Curl_resolver_is_resolved(struct Curl_easy *data,
struct Curl_dns_entry **entry)
{
struct thread_data *td = data->state.async.tdata;
int done = 0;
DEBUGASSERT(entry);
*entry = NULL;
if(!td) {
DEBUGASSERT(td);
return CURLE_COULDNT_RESOLVE_HOST;
}
Curl_mutex_acquire(td->tsd.mtx);
done = td->tsd.done;
Curl_mutex_release(td->tsd.mtx);
if(done) {
getaddrinfo_complete(data);
if(!data->state.async.dns) {
CURLcode result = Curl_resolver_error(data);
destroy_async_data(&data->state.async);
return result;
}
destroy_async_data(&data->state.async);
*entry = data->state.async.dns;
}
else {
/* poll for name lookup done with exponential backoff up to 250ms */
/* should be fine even if this converts to 32 bit */
timediff_t elapsed = Curl_timediff(Curl_now(),
data->progress.t_startsingle);
if(elapsed < 0)
elapsed = 0;
if(td->poll_interval == 0)
/* Start at 1ms poll interval */
td->poll_interval = 1;
else if(elapsed >= td->interval_end)
/* Back-off exponentially if last interval expired */
td->poll_interval *= 2;
if(td->poll_interval > 250)
td->poll_interval = 250;
td->interval_end = elapsed + td->poll_interval;
Curl_expire(data, td->poll_interval, EXPIRE_ASYNC_NAME);
}
return CURLE_OK;
}
int Curl_resolver_getsock(struct Curl_easy *data, curl_socket_t *socks)
{
int ret_val = 0;
timediff_t milli;
timediff_t ms;
struct resdata *reslv = (struct resdata *)data->state.async.resolver;
#ifndef CURL_DISABLE_SOCKETPAIR
struct thread_data *td = data->state.async.tdata;
#else
(void)socks;
#endif
#ifndef CURL_DISABLE_SOCKETPAIR
if(td) {
/* return read fd to client for polling the DNS resolution status */
socks[0] = td->tsd.sock_pair[0];
td->tsd.data = data;
ret_val = GETSOCK_READSOCK(0);
}
else {
#endif
ms = Curl_timediff(Curl_now(), reslv->start);
if(ms < 3)
milli = 0;
else if(ms <= 50)
milli = ms/3;
else if(ms <= 250)
milli = 50;
else
milli = 200;
Curl_expire(data, milli, EXPIRE_ASYNC_NAME);
#ifndef CURL_DISABLE_SOCKETPAIR
}
#endif
return ret_val;
}
#ifndef HAVE_GETADDRINFO
/*
* Curl_getaddrinfo() - for platforms without getaddrinfo
*/
struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct Curl_easy *data,
const char *hostname,
int port,
int *waitp)
{
struct resdata *reslv = (struct resdata *)data->state.async.resolver;
*waitp = 0; /* default to synchronous response */
reslv->start = Curl_now();
/* fire up a new resolver thread! */
if(init_resolve_thread(data, hostname, port, NULL)) {
*waitp = 1; /* expect asynchronous response */
return NULL;
}
failf(data, "getaddrinfo() thread failed");
return NULL;
}
#else /* !HAVE_GETADDRINFO */
/*
* Curl_resolver_getaddrinfo() - for getaddrinfo
*/
struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct Curl_easy *data,
const char *hostname,
int port,
int *waitp)
{
struct addrinfo hints;
int pf = PF_INET;
struct resdata *reslv = (struct resdata *)data->state.async.resolver;
*waitp = 0; /* default to synchronous response */
#ifdef CURLRES_IPV6
if(Curl_ipv6works(data))
/* The stack seems to be IPv6-enabled */
pf = PF_UNSPEC;
#endif /* CURLRES_IPV6 */
memset(&hints, 0, sizeof(hints));
hints.ai_family = pf;
hints.ai_socktype = (data->conn->transport == TRNSPRT_TCP)?
SOCK_STREAM : SOCK_DGRAM;
reslv->start = Curl_now();
/* fire up a new resolver thread! */
if(init_resolve_thread(data, hostname, port, &hints)) {
*waitp = 1; /* expect asynchronous response */
return NULL;
}
failf(data, "getaddrinfo() thread failed to start");
return NULL;
}
#endif /* !HAVE_GETADDRINFO */
CURLcode Curl_set_dns_servers(struct Curl_easy *data,
char *servers)
{
(void)data;
(void)servers;
return CURLE_NOT_BUILT_IN;
}
CURLcode Curl_set_dns_interface(struct Curl_easy *data,
const char *interf)
{
(void)data;
(void)interf;
return CURLE_NOT_BUILT_IN;
}
CURLcode Curl_set_dns_local_ip4(struct Curl_easy *data,
const char *local_ip4)
{
(void)data;
(void)local_ip4;
return CURLE_NOT_BUILT_IN;
}
CURLcode Curl_set_dns_local_ip6(struct Curl_easy *data,
const char *local_ip6)
{
(void)data;
(void)local_ip6;
return CURLE_NOT_BUILT_IN;
}
#endif /* CURLRES_THREADED */
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