Unverified Commit 6765e6d9 authored by Romain Fliedel's avatar Romain Fliedel Committed by Daniel Stenberg
Browse files

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
parent 47ccb2d2

lib/asyn-ares.c

+26 −7
Original line number Diff line number Diff line
@@ -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);

lib/asyn-thread.c

+4 −3
Original line number Diff line number Diff line
@@ -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 *);

lib/asyn.h

+5 −4
Original line number Diff line number Diff line
@@ -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

lib/connect.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

lib/easy.c

+2 −1
Original line number Diff line number Diff line
@@ -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;