[interface] Ignore any attempts to plug in the null interface

Allow intf_plug() and intf_plug_plug() to be called safely on
interfaces that may be the null interface.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/interface.c b/src/core/interface.c
index 402aa45415059b009e4fbc5e8bfd325cece691de..05e7e4777b1d213cb96a692ea0f2da92b849c926 100644 (file)
--- a/src/core/interface.c
+++ b/src/core/interface.c
@@ -81,9 +81,14 @@ struct interface null_intf = INTF_INIT ( null_intf_desc );
  * interface is updated to point to the new destination interface.
  */
 void intf_plug ( struct interface *intf, struct interface *dest ) {
+
+       if ( intf == &null_intf )
+               return;
+
        DBGC ( INTF_COL ( intf ),
               "INTF " INTF_INTF_FMT " replug to " INTF_FMT "\n",
               INTF_INTF_DBG ( intf, intf->dest ), INTF_DBG ( dest ) );
+
        intf_get ( dest );
        intf_put ( intf->dest );
        intf->dest = dest;