[patch] interface routes

[Andre Oppermann]

On 07.03.2013 07:34, Alexander V. Chernikov wrote:
> Hello list!
>
> There is a known long-lived issue with interface routes addition/deletion:
>
> ifconfig iface inet 1.2.3.4/24 can fail if given prefix is already in kernel route table (for
> example, advertised by IGP like OSPF).
>
> Interface route can be deleted via route(8) or any route socket user (sometimes this happens with
> popular opensource daemons like bird/quagga).
>
> Problem is reported at least in kern/106722 and kern/155772.

You patch is a welcome addition.

> This can be fixed the following way:
> Immutable route flag (RTM_PINNED, added in 19995 with 'for future use' comment) is utilised to mark
> route 'immutable'.
> rtrequest1_fib refuses to delete routes with given flag unless RTM_PINNED is set in rti_flags.

How do the routing daemons react to being unable to change/delete
such a route?

EADDRINUSE would likely be a more descriptive error instead of EPERM?

> Every interface address manupulation is done via rtinit[1], so
> rtinit1() sets this flag (and behavior does not change here).
 >
> Adding interface address is handled via atomically deleting old prefix and adding interface one.

This brings up a long standing sore point of our routing code
which this patch makes more pronounced.  When an interface link
state is down I don't want the route to it to persist but to
become inactive so another path can be chosen.  This the very
point of running a routing daemon.  So on the link-down event
the installed interface routes should be removed from the routing
table.  The configured addresses though should persist and the
interface routes re-installed on a link-up event.  What's your
opinion on it?

Other than these points I think your code is fine and can go
into the tree.

-- 
Andre