BIRD 1.4.0 bugfixes [1/2]

[Tore Anderson]

* Pierluigi Rolando

> This patch fixes a situation where an interface enters TMPDOWN state
> and doesn't leave it until a device scan is triggered by timer.
> 
> This seems to happen whenever the interface is up but with no IP
> address configured. BIRD will then put the interface in TMPDOWN state
> (correctly)

Hi,

I question the correctness of putting an interface in any form of DOWN
state even though there are no addresses assigned. There exists no
requirement that an interface has addresses, even if it doesn't, it may
still be UP and have active routes pointing to it. I therefore would ask
you to consider fixing this in another way, by simply not requiring any
IP addresses on the interface in order for it to be considered active.

FWIW, here's my use case for unnumbered interfaces:

$ ip a l dev nat64
3: nat64: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 500
    link/none 
    inet 192.0.2.0/32 scope global nat64
    inet6 2001:db8::/128 scope global 
       valid_lft forever preferred_lft forever
$ ip r l dev nat64
87.238.33.15  proto bird 
100.64.0.0/10  proto bird 
$ ip -6 r l dev nat64
2001:db8::  proto kernel  metric 256 
2a02:c0:0:0:64::/96  proto bird  metric 1024 

The "nat64" interface is a tun interface with a TAYGA process in the
other end. The two addresses assigned to the interface (192.0.2.0/32 and
2001:db8::/128) serve absolutely no purpose except to persuade BIRD to
consider the interface active - I'd rather get rid of them, if possible.

Tore