[netdevice] Avoid using zero as a network device index

Avoid using zero as a network device index, so that a zero
sin6_scope_id can be used to mean "unspecified" (rather than
unintentionally meaning "net0").

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

diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index 889b00c1a471f048335d7c365ea41b1a6e8ab6d9..7c40a2ac87d247c860efcce21be49fefe6ecb13d 100644 (file)
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -676,11 +676,11 @@ int register_netdev ( struct net_device *netdev ) {
        }
 
        /* Record device index and create device name */
-       netdev->index = netdev_index++;
        if ( netdev->name[0] == '\0' ) {
                snprintf ( netdev->name, sizeof ( netdev->name ), "net%d",
-                          netdev->index );
+                          netdev_index );
        }
+       netdev->index = ++netdev_index;
 
        /* Use least significant bits of the link-layer address to
         * improve the randomness of the (non-cryptographic) random