[Patch: preserve attributes of default route] [was: Support default route with non-default attributes]

[Shaheed Haque]

Here is an improved patch: this explicitly preserves any proto or
metric settings when the new default route is set.

However, there is definitely a timing issue such that neither the
previous patch nor this work reliably, at least on my Ubuntu wily
kernel+userspace combination.

On 12 February 2016 at 20:43, Shaheed Haque <srhaque at theiet.org> wrote:
> [ 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 --------------
--- /usr/share/vpnc-scripts/vpnc-script.saved	2014-10-26 00:38:13.000000000 +0100
+++ /usr/share/vpnc-scripts/vpnc-script	2016-03-02 23:53:50.547478197 +0000
@@ -229,8 +229,10 @@
 	}
 
 	set_default_route() {
-		$IPROUTE route | grep '^default' | fix_ip_get_output > "$DEFAULT_ROUTE_FILE"
-		$IPROUTE route replace default dev "$TUNDEV"
+		$IPROUTE route | grep '^default' > "$DEFAULT_ROUTE_FILE"
+                proto=$($IPROUTE route | grep '^default' | sed -r '/proto\s+\S+/s/.*(proto\s+\S+).*/\1/p;d')
+                metric=$($IPROUTE route | grep '^default' | sed -r '/metric\s+[0-9]+/s/.*(metric\s+[0-9]+).*/\1/p;d')
+		$IPROUTE route replace default dev "$TUNDEV" $proto $metric
 		$IPROUTE route flush cache
 	}