Treat label=0 as an invalid next-hop-via-label
@@ -794,7 +794,13 @@ add_del_route_t_handler (u8 is_multipath,
fib_route_path_t *paths = NULL;
fib_entry_flag_t entry_flags = FIB_ENTRY_FLAG_NONE;
- if (MPLS_LABEL_INVALID != next_hop_via_label)
+ /*
+ * the special INVALID label meams we are not recursing via a
+ * label. Exp-null value is never a valid via-label so that
+ * also means it's not a via-label and means clients that set
+ * it to 0 by default get the expected behaviour
+ */
+ if ((MPLS_LABEL_INVALID != next_hop_via_label) && (0 != next_hop_via_label))
{
path.frp_proto = DPO_PROTO_MPLS;
path.frp_local_label = next_hop_via_label;
