netlink: add interface notification on link status / flags change.

* Add link-state change notifications by subscribing to ifnet_link_event.
 In the Linux netlink model, link state is reported in 2 places: first is
 the IFLA_OPERSTATE, which stores state per RFC2863.
 The second is an IFF_LOWER_UP interface flag. As many applications rely
 on the latter, reserve 1 bit from if_flags, named as IFF_NETLINK_1.
 This flag is mapped to IFF_LOWER_UP in the netlink headers. This is done
 to avoid making applications think this flag is actually
 supported / presented in non-netlink outputs.
* Add flag change notifications, by hooking into rt_ifmsg().
 In the netlink model, notification should include the bitmask for the
 change flags. Update rt_ifmsg() to include such bitmask.

Differential Revision: https://reviews.freebsd.org/D37597

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/net/route/route_ctl.h b/sys/net/route/route_ctl.h
index d150da6264d4..e8560e681ddb 100644
--- a/sys/net/route/route_ctl.h
+++ b/sys/net/route/route_ctl.h
@@ -191,8 +191,10 @@ void rib_notify(struct rib_head *rnh, enum rib_subscription_type type,
 
 /* Event bridge */
 typedef void route_event_f(uint32_t fibnum, const struct rib_cmd_info *rc);
+typedef void ifmsg_event_f(struct ifnet *ifp, int if_flags_mask);
 struct rtbridge{
 	route_event_f	*route_f;
+	ifmsg_event_f	*ifmsg_f;
 };
 extern struct rtbridge *rtsock_callback_p;
 extern struct rtbridge *netlink_callback_p;