multi: CURLINFO_LASTSOCKET doesn't work after remove_handle

When curl_multi_remove_handle() is called and an easy handle is returned
to the connection cache held in the multi handle, then we cannot allow
CURLINFO_LASTSOCKET to extract it since that will more or less encourage
that the user uses the socket while it can get used by libcurl again.

Without this fix, we'd get a segfault in Curl_getconnectinfo() trying to
dereference the NULL pointer in 'data->state.connc'.

Bug: http://curl.haxx.se/bug/view.cgi?id=3023840

diff --git a/lib/multi.c b/lib/multi.c
index ea284b3..9273f8d 100644 (file)
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -656,6 +656,10 @@ CURLMcode curl_multi_remove_handle(CURLM *multi_handle,
          to that since we're not part of that handle anymore */
       easy->easy_handle->state.connc = NULL;
 
+      /* Since we return the connection back to the communal connection pool
+         we mark the last connection as inaccessible */
+      easy->easy_handle->state.lastconnect = -1;
+
       /* Modify the connectindex since this handle can't point to the
          connection cache anymore.