[BIRD 2.0.x] Netlink: ignore dead routes

[Alexander Zubkov]

I made a patch for that. It works at least for my test case. I had to
add additional parameter to nl_parse_multipath() function to pass
information about this exception for dead routes. But may be there are
better ways to do that. For example to set "s->krt_src" earlier, but I
do not know if it will not break something else. Or may be it is even
better to add additional field to "struct nl_parse_state" for that.

On Mon, Dec 27, 2021 at 5:35 PM Ondrej Zajicek <santiago at crfreenet.org> wrote:
>
> On Mon, Dec 27, 2021 at 02:51:34PM +0100, Alexander Zubkov wrote:
> > Hi all,
> >
> > I'll pop up this old discussion. I've found a bug with bird handling
> > its routes when ignore_routes_with_linkdown is enabled. And I suspect
> > it is related to this patch.
> > The problem is that bird does not replace or delete the routes it
> > installed when they are marked as dead. For example if we stop it with
> > "graceful restart", the routes are left in the table and after we
> > start bird again with updated config, this old route remains in the
> > table. I can reproduce it with bird compiled from master branch now.
> > Now, that I have found this thread, I suppose, that this changes blind
> > bird for all such routes during the scan. As a result bird also
> > ignores its own routes (proto bird), which causes problems. I think
> > there should be an exception for the routes that are installed by bird
> > itself.
>
> Hi
>
> You are right, it makes sense to apply dead-flag handling only to
> to non-bird routes. Will fix that.
>
> --
> Elen sila lumenn' omentielvo
>
> Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."
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