This patch provides prototype of subsystem that can be used by tunneling interfaces. It depends on D17100.
The idea is that the tunneling interface driver registers handler for ifaddr_event_ex event. When the event occurs, the handler can check, that given address is used by tunneling interface as ingress address. If so, the driver clears IFF_DRV_RUNNING flag and this will prevent from sending packets from IP address, that we do not own.
When IP address appears, the handler sets IFF_DRV_RUNNING flag and interface goes into working state.