Support default route with non-default attributes

[Shaheed Haque]

[ This report concerns a defect originally reported at
https://bugs.launchpad.net/ubuntu/+source/vpnc-scripts/+bug/1544802 ]

Bug Description

The /usr/share/vpnc-scripts/vpnc-script handles updates to the default
route using two different codepaths. In one codepath, the command "ip
route replace" is used to update the original default route with new
one (and to restore it later). The replace command in the update case
does not work if the original route default route has non-standard
attributes. For example, an original default route like this:

$ sudo ip route
default via 192.168.1.254 dev wlp3s0 proto static metric 600
169.254.0.0/16 dev wlp3s0 scope link metric 1000
192.168.1.0/24 dev wlp3s0 proto kernel scope link src 192.168.1.85 metric 600

cannot be simply "ip route replace"d by a command of the form "ip
route replace dev <foo>". Also, the present logic to save and then
restore the original rute is broken because not all the route
attributes are preserved AND the replacement attributes don't match
the attributes of the new default route.

The attached patch addresses both these problems.

The software versions in use are up-to-date Wily with:

$ dpkg-query -l | egrep 'vpnc-scripts|iproute'
ii iproute 1:4.1.1-1ubuntu1 all transitional dummy package for iproute2
ii iproute2 4.1.1-1ubuntu1 amd64 networking and traffic control tools
ii vpnc-scripts 0.1~git20140806-1 all Network configuration scripts
for VPNC and OpenConnect

As requested at http://www.infradead.org/openconnect/contribute.html,
this patch is hereby:

Signed-off-by: Shaheed R. Haque <srhaque at theiet.org>

Thanks, Shaheed
-------------- next part --------------
232,233c232,234
< 		$IPROUTE route | grep '^default' | fix_ip_get_output > "$DEFAULT_ROUTE_FILE"
< 		$IPROUTE route replace default dev "$TUNDEV"
---
> 		$IPROUTE route | grep '^default' > "$DEFAULT_ROUTE_FILE"
> 		$IPROUTE route delete `cat "$DEFAULT_ROUTE_FILE"`
> 		$IPROUTE route add default via "$NETWORK" dev "$TUNDEV"
247c248,249
< 			$IPROUTE route replace `cat "$DEFAULT_ROUTE_FILE"`
---
> 			$IPROUTE route delete default dev "$TUNDEV"
> 			$IPROUTE route add `cat "$DEFAULT_ROUTE_FILE"`