From 6765e6d9e6a32bb4fc666d744cb57e2d55d4e13b Mon Sep 17 00:00:00 2001 From: Romain Fliedel Date: Mon, 5 Nov 2018 11:01:19 +0100 Subject: 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 --- lib/asyn-ares.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) (limited to 'lib/asyn-ares.c') diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c index 5cfb2602d..6a49566c8 100644 --- a/lib/asyn-ares.c +++ b/lib/asyn-ares.c @@ -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); -- cgit v1.2.3