system/2400: GRE tunnel config fails without default route at startup

[Gnats <gnats@cvs.openbsd.org>]

>Number:         2400
>Category:       system
>Synopsis:       /etc/netstart tries to config hostname.gre* files before a default route exists
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 14 09:10:01 MST 2002
>Last-Modified:
>Originator:     Peter Galbavy
>Organization:
Knowtion Ltd.
>Release:        -current
>Environment:
	System      : OpenBSD 3.0
	Architecture: OpenBSD.i386
	Machine     : i386
>Description:
From: Peter Galbavy <peter@office.london.knowtion.net>
Message-Id: <E16bOOy-00015Q-00@mx-30.mail.knowledge.com>
Date: Thu, 14 Feb 2002 16:06:28 +0000

Trying to use a hostname.gre0 file to auto-config a GRE tunnel fails
because the route to the destination has not yet been installed.
>How-To-Repeat:
/etc/hostname.gre0:
inet 1.1.1.1 255.255.255.252 NONE link0 up
dest 2.2.2.2

reboot.
>Fix:
I can think of two potential fixes:

1. Alter /etc/netstart to be more aware of IP-in-IP tunnels

2. Change the gre(4) driver to allow unrouted destinations, and simply
return an appropriate destination unreachable when the remote end of
the tunnel is unreachable. I am not sure what the RFCs or Cisco etc.
implemenations do in this case.

>Audit-Trail:
>Unformatted: