BUG/MEDIUM: backend: never reuse a connection for tcp mode

The reuse of idle connections should only happen for a proxy with the
http mode. In case of a backend with the tcp mode, the reuse selection
and insertion in session list are skipped.

This behavior is present since commit :
MEDIUM: connection: Add private connections synchronously in session server list
It could also be further exagerated by :
MEDIUM: backend: add reused conn to sess if mux marked as HOL blocking

It can be backported up to 2.3.

diff --git a/src/backend.c b/src/backend.c
index 0d0447d7bc52321d2ca4edc529ba6f1e47cab85b..f3f42230bbadca40a5babad0d6b67ac57081a858 100644 (file)
--- a/src/backend.c
+++ b/src/backend.c
@@ -1248,13 +1248,16 @@ int connect_server(struct stream *s)
         */
        si_release_endpoint(&s->si[1]);
 
+       srv = objt_server(s->target);
+
+       if (s->be->mode != PR_MODE_HTTP)
+               goto skip_reuse;
+
        /* first, search for a matching connection in the session's idle conns */
        srv_conn = session_get_conn(s->sess, s->target);
        if (srv_conn)
                reuse = 1;
 
-       srv = objt_server(s->target);
-
        if (srv && !reuse && reuse_mode != PR_O_REUSE_NEVR) {
                /* Below we pick connections from the safe, idle  or
                 * available (which are safe too) lists based
@@ -1391,6 +1394,7 @@ int connect_server(struct stream *s)
        else
                srv_conn = NULL;
 
+skip_reuse:
        /* no reuse or failed to reuse the connection above, pick a new one */
        if (!srv_conn) {
                srv_conn = conn_new(s->target);
@@ -1541,21 +1545,26 @@ int connect_server(struct stream *s)
                        conn_full_close(srv_conn);
                        return SF_ERR_INTERNAL;
                }
-               /* If we're doing http-reuse always, and the connection is not
-                * private with available streams (an http2 connection), add it
-                * to the available list, so that others can use it right
-                * away. If the connection is private or we're doing http-reuse
-                * safe and the mux protocol supports multiplexing, add it in
-                * the session server list.
-                */
-               if (srv && reuse_mode == PR_O_REUSE_ALWS &&
-                   !(srv_conn->flags & CO_FL_PRIVATE) && srv_conn->mux->avail_streams(srv_conn) > 0)
-                       LIST_ADDQ(&srv->available_conns[tid], mt_list_to_list(&srv_conn->list));
-               else if (srv_conn->flags & CO_FL_PRIVATE ||
-                        (reuse_mode == PR_O_REUSE_SAFE &&
-                         srv_conn->mux->flags & MX_FL_HOL_RISK)) {
-                       /* If it fail now, the same will be done in mux->detach() callback */
-                       session_add_conn(s->sess, srv_conn, srv_conn->target);
+               if (s->be->mode != PR_MODE_HTTP) {
+                       /* If we're doing http-reuse always, and the connection
+                        * is not private with available streams (an http2
+                        * connection), add it to the available list, so that
+                        * others can use it right away. If the connection is
+                        * private or we're doing http-reuse safe and the mux
+                        * protocol supports multiplexing, add it in the
+                        * session server list.
+                        */
+                       if (srv && reuse_mode == PR_O_REUSE_ALWS &&
+                           !(srv_conn->flags & CO_FL_PRIVATE) &&
+                           srv_conn->mux->avail_streams(srv_conn) > 0) {
+                               LIST_ADDQ(&srv->available_conns[tid], mt_list_to_list(&srv_conn->list));
+                       }
+                       else if (srv_conn->flags & CO_FL_PRIVATE ||
+                                (reuse_mode == PR_O_REUSE_SAFE &&
+                                 srv_conn->mux->flags & MX_FL_HOL_RISK)) {
+                               /* If it fail now, the same will be done in mux->detach() callback */
+                               session_add_conn(s->sess, srv_conn, srv_conn->target);
+                       }
                }
        }