# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1367343719 -7200
# Node ID de10f57af91deba3f6c965cf6318b2fe02e1aaeb
# Parent  8190cadff984ef84990e1a10f009d6f1c1780dd8
Added error handling when setting up network tunnelling.

diff -r 8190cadff984 -r de10f57af91d uml-net
--- a/uml-net	Tue Apr 30 17:52:07 2013 +0200
+++ b/uml-net	Tue Apr 30 19:41:59 2013 +0200
@@ -28,21 +28,33 @@
 
 PROGNAME=`basename "$0"`
 
-if [ "$1" = "--start" ]; then
-        chgrp adm /dev/net/tun
-        tunctl -u "$2" -t "$TUNDEVICE"
-        ifconfig "$TUNDEVICE" "$HOSTADDRESS" up
-        bash -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
+OPERATION=$1
+USER=$2
+
+if [ "$OPERATION" = "--start" ] && [ "$USER" ]; then
+        if ! chgrp adm /dev/net/tun ; then
+                echo "Cannot change group permission on tunnel device." 1>&2
+                exit 1
+        fi
+        if ! tunctl -u "$USER" -t "$TUNDEVICE" ; then
+                echo "Cannot configure a tunnel device for user $USER." 1>&2
+                exit 1
+        fi
+        if ! ifconfig "$TUNDEVICE" "$HOSTADDRESS" up ; then
+                echo "Could not start the tunnel device." 1>&2
+                exit 1
+        fi
+        sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
         iptables -t nat -I POSTROUTING -o "$NETDEVICE" -j MASQUERADE
         iptables -I FORWARD -i "$TUNDEVICE" -j ACCEPT
         iptables -I FORWARD -o "$TUNDEVICE" -j ACCEPT
 
-elif [ "$1" = "--stop" ]; then
+elif [ "$OPERATION" = "--stop" ]; then
         iptables -t nat -D POSTROUTING 1
         iptables -D FORWARD 1
         iptables -D FORWARD 1
         tunctl -d "$TUNDEVICE"
 else
-	echo "Usage: $PROGNAME --start <username> | --stop" 1>&2
-	exit 1
+        echo "Usage: $PROGNAME --start <username> | --stop" 1>&2
+        exit 1
 fi