ares: remove fd from multi fd set when ares is about to close the fd

When using c-ares for asyn dns, the dns socket fd was silently closed
by c-ares without curl being aware. curl would then 'realize' the fd
has been removed at next call of Curl_resolver_getsock, and only then
notify the CURLMOPT_SOCKETFUNCTION to remove fd from its poll set with
CURL_POLL_REMOVE. At this point the fd is already closed.

By using ares socket state callback (ARES_OPT_SOCK_STATE_CB), this
patch allows curl to be notified that the fd is not longer needed
for neither for write nor read. At this point by calling
Curl_multi_closed we are able to notify multi with CURL_POLL_REMOVE
before the fd is actually closed by ares.

In asyn-ares.c Curl_resolver_duphandle we can't use ares_dup anymore
since it does not allow passing a different sock_state_cb_data

Closes #3238
This commit is contained in:
Romain Fliedel 2018-11-05 11:01:19 +01:00 committed by Daniel Stenberg
parent 47ccb2d204
commit 6765e6d9e6
No known key found for this signature in database
GPG Key ID: 5CC908FDB71E12C2
8 changed files with 45 additions and 23 deletions

View File

@ -119,6 +119,17 @@ void Curl_resolver_global_cleanup(void)
#endif
}
static void Curl_ares_sock_state_cb(void *data, ares_socket_t socket_fd,
int readable, int writable)
{
struct Curl_easy *easy = data;
if(!readable && !writable) {
DEBUGASSERT(easy);
Curl_multi_closed(easy, socket_fd);
}
}
/*
* Curl_resolver_init()
*
@ -126,9 +137,14 @@ void Curl_resolver_global_cleanup(void)
* 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)
CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver)
{
int status = ares_init((ares_channel*)resolver);
int status;
struct ares_options options;
int optmask = ARES_OPT_SOCK_STATE_CB;
options.sock_state_cb = Curl_ares_sock_state_cb;
options.sock_state_cb_data = easy;
status = ares_init_options((ares_channel*)resolver, &options, optmask);
if(status != ARES_SUCCESS) {
if(status == ARES_ENOMEM)
return CURLE_OUT_OF_MEMORY;
@ -159,12 +175,15 @@ void Curl_resolver_cleanup(void *resolver)
* 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)
CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, 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;
(void)from;
/*
* it would be better to call ares_dup instead, but right now
* it is not possible to set 'sock_state_cb_data' outside of
* ares_init_options
*/
return Curl_resolver_init(easy, to);
}
static void destroy_async_data(struct Curl_async *async);

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@ -108,8 +108,9 @@ void Curl_resolver_global_cleanup(void)
* URL-state specific environment ('resolver' member of the UrlState
* structure).
*/
CURLcode Curl_resolver_init(void **resolver)
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;
@ -132,10 +133,10 @@ void Curl_resolver_cleanup(void *resolver)
* Called from curl_easy_duphandle() to duplicate resolver URL state-specific
* environment ('resolver' member of the UrlState structure).
*/
int Curl_resolver_duphandle(void **to, void *from)
CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to, void *from)
{
(void)from;
return Curl_resolver_init(to);
return Curl_resolver_init(easy, to);
}
static void destroy_async_data(struct Curl_async *);

View File

@ -60,7 +60,7 @@ void Curl_resolver_global_cleanup(void);
* Returning anything else than CURLE_OK fails curl_easy_init() with the
* correspondent code.
*/
CURLcode Curl_resolver_init(void **resolver);
CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver);
/*
* Curl_resolver_cleanup()
@ -79,7 +79,8 @@ void Curl_resolver_cleanup(void *resolver);
* pointer. Returning anything else than CURLE_OK causes failed
* curl_easy_duphandle() call.
*/
int Curl_resolver_duphandle(void **to, void *from);
CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to,
void *from);
/*
* Curl_resolver_cancel().
@ -150,8 +151,8 @@ Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
#define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST
#define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST
#define Curl_resolver_getsock(x,y,z) 0
#define Curl_resolver_duphandle(x,y) CURLE_OK
#define Curl_resolver_init(x) CURLE_OK
#define Curl_resolver_duphandle(x,y,z) CURLE_OK
#define Curl_resolver_init(x,y) CURLE_OK
#define Curl_resolver_global_init() CURLE_OK
#define Curl_resolver_global_cleanup() Curl_nop_stmt
#define Curl_resolver_cleanup(x) Curl_nop_stmt

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@ -1314,7 +1314,7 @@ int Curl_closesocket(struct connectdata *conn,
conn->sock_accepted[SECONDARYSOCKET] = FALSE;
else {
int rc;
Curl_multi_closed(conn, sock);
Curl_multi_closed(conn->data, sock);
Curl_set_in_callback(conn->data, true);
rc = conn->fclosesocket(conn->closesocket_client, sock);
Curl_set_in_callback(conn->data, false);
@ -1324,7 +1324,7 @@ int Curl_closesocket(struct connectdata *conn,
if(conn)
/* tell the multi-socket code about this */
Curl_multi_closed(conn, sock);
Curl_multi_closed(conn->data, sock);
sclose(sock);

View File

@ -966,7 +966,8 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
}
/* Clone the resolver handle, if present, for the new handle */
if(Curl_resolver_duphandle(&outcurl->state.resolver,
if(Curl_resolver_duphandle(outcurl,
&outcurl->state.resolver,
data->state.resolver))
goto fail;

View File

@ -2466,11 +2466,11 @@ void Curl_updatesocket(struct Curl_easy *data)
* socket again and it gets the same file descriptor number.
*/
void Curl_multi_closed(struct connectdata *conn, curl_socket_t s)
void Curl_multi_closed(struct Curl_easy *data, curl_socket_t s)
{
if(conn->data) {
if(data) {
/* if there's still an easy handle associated with this connection */
struct Curl_multi *multi = conn->data->multi;
struct Curl_multi *multi = data->multi;
if(multi) {
/* this is set if this connection is part of a handle that is added to
a multi handle, and only then this is necessary */
@ -2478,7 +2478,7 @@ void Curl_multi_closed(struct connectdata *conn, curl_socket_t s)
if(entry) {
if(multi->socket_cb)
multi->socket_cb(conn->data, s, CURL_POLL_REMOVE,
multi->socket_cb(data, s, CURL_POLL_REMOVE,
multi->socket_userp,
entry->socketp);

View File

@ -89,7 +89,7 @@ void Curl_multi_connchanged(struct Curl_multi *multi);
* socket again and it gets the same file descriptor number.
*/
void Curl_multi_closed(struct connectdata *conn, curl_socket_t s);
void Curl_multi_closed(struct Curl_easy *data, curl_socket_t s);
/*
* Add a handle and move it into PERFORM state at once. For pushed streams.

View File

@ -570,7 +570,7 @@ CURLcode Curl_open(struct Curl_easy **curl)
data->magic = CURLEASY_MAGIC_NUMBER;
result = Curl_resolver_init(&data->state.resolver);
result = Curl_resolver_init(data, &data->state.resolver);
if(result) {
DEBUGF(fprintf(stderr, "Error: resolver_init failed\n"));
free(data);