ospfd: passive p2p interfaces don't work

[Stefan Sperling]

I want to announce a host-route to the address of a tun0 interface
over OSPF. The config snippet I use for this looks like:

        interface tun0:217.197.85.96 {
                passive
                depend on carp0
        }

With this configuration, the tun interface is permanently marked DOWN
and the route is not announced:

Interface   Address            State  HelloTimer Linkstate  Uptime    nc  ac
tun0        217.197.85.96/32   DOWN   -          active     00:00:00   0   0

If I omit 'passive' it works as expected:

        interface tun0:217.197.85.96 {
                depend on carp0
        }

Interface   Address            State  HelloTimer Linkstate  Uptime    nc  ac
tun0        217.197.85.96/32   P2P    00:00:06   active     00:02:13   0   0

However, osfpd now sends useless OSPF packets, and my logs are being
spammed with the message:
send_packet: error sending packet on interface tun0: Permission denied

I believe this is a bug. I expect to be able to announce the address
of a passive point-to-point interface with ospfd.