multi: conn goes bad when data change

Within multi_socket when conn is used as a shorthand, data could be
changed and multi_runsingle could modify the connectdata struct to deal
with. This bug has not been included in a public release.

Using 'conn' like that turned out to be ugly. This change is a partial
revert of commit f1c6cd42f474df59.

Reported by: Miroslav Spousta
Bug: http://curl.haxx.se/bug/view.cgi?id=3265485

1 files changed, 11 insertions, 15 deletions

diff --git a/lib/multi.c b/lib/multi.c
index 8172d061d..82453f848 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -2105,41 +2105,37 @@ static CURLMcode multi_socket(struct Curl_multi *multi,
          and just move on. */
       ;
     else {
-      struct connectdata *conn;
       data = entry->easy;
 
       if(data->magic != CURLEASY_MAGIC_NUMBER)
         /* bad bad bad bad bad bad bad */
         return CURLM_INTERNAL_ERROR;
 
-      /* note that this can possibly be NULL at this point */
-      conn = data->set.one_easy->easy_conn;
-
       /* If the pipeline is enabled, take the handle which is in the head of
          the pipeline. If we should write into the socket, take the send_pipe
          head.  If we should read from the socket, take the recv_pipe head. */
-      if(conn) {
+      if(data->set.one_easy->easy_conn) {
         if ((ev_bitmask & CURL_POLL_OUT) &&
-            conn->send_pipe &&
-            conn->send_pipe->head)
-          data = conn->send_pipe->head->ptr;
+            data->set.one_easy->easy_conn->send_pipe &&
+            data->set.one_easy->easy_conn->send_pipe->head)
+          data = data->set.one_easy->easy_conn->send_pipe->head->ptr;
         else if ((ev_bitmask & CURL_POLL_IN) &&
-                 conn->recv_pipe &&
-                 conn->recv_pipe->head)
-          data = conn->recv_pipe->head->ptr;
+                 data->set.one_easy->easy_conn->recv_pipe &&
+                 data->set.one_easy->easy_conn->recv_pipe->head)
+          data = data->set.one_easy->easy_conn->recv_pipe->head->ptr;
       }
 
-      if(conn && !(conn->handler->flags & PROTOPT_DIRLOCK))
+      if(data->set.one_easy->easy_conn && !(data->set.one_easy->easy_conn->handler->flags & PROTOPT_DIRLOCK))
         /* set socket event bitmask if they're not locked */
-        conn->cselect_bits = ev_bitmask;
+        data->set.one_easy->easy_conn->cselect_bits = ev_bitmask;
 
       do
         result = multi_runsingle(multi, now, data->set.one_easy);
       while (CURLM_CALL_MULTI_PERFORM == result);
 
-      if(conn && !(conn->handler->flags & PROTOPT_DIRLOCK))
+      if(data->set.one_easy->easy_conn && !(data->set.one_easy->easy_conn->handler->flags & PROTOPT_DIRLOCK))
         /* clear the bitmask only if not locked */
-        conn->cselect_bits = 0;
+        data->set.one_easy->easy_conn->cselect_bits = 0;
 
       if(CURLM_OK >= result)
         /* get the socket(s) and check if the state has been changed since