#!/bin/bash
INTERFACE=eth0       # Set to name of VPN interface
shopt -s nullglob

# Test whether gateway is connected to the outer world via VPN
ping -q -I $INTERFACE 8.8.8.8 -c 4 -i 1 -W 5 >/dev/null 2>&1

if test $? -eq 0; then
    NEW_STATE=server
else
    NEW_STATE=off
fi

# Iterate through network interfaces in sys file system
for MESH in /sys/class/net/*/mesh; do
# Check whether gateway modus needs to be changed
OLD_STATE="$(cat $MESH/gw_mode)"
[ "$OLD_STATE" == "$NEW_STATE" ] && continue
   echo $NEW_STATE > $MESH/gw_mode
   echo 92MBit/92MBit > $MESH/gw_bandwidth
   logger "batman gateway mode changed to $NEW_STATE"

   # Check whether gateway modus has been deactivated
   if [ "$NEW_STATE" == "off" ]; then
       # Shutdown DHCP server to prevent renewal of leases
       /usr/sbin/service isc-dhcp-server stop
   fi

   # Check whether gateway modus has been activated
   if [ "$NEW_STATE" == "server" ]; then
       # Restart DHCP server
       /usr/sbin/service isc-dhcp-server start
   fi
   exit 0
done

if [ "$NEW_STATE" == "server" ]; then
   /usr/sbin/service isc-dhcp-server status 2>&1> /dev/null
   if  $? -ne 0 
   then
       /usr/sbin/service isc-dhcp-server restart
   fi
fi
if [ "$NEW_STATE" == "off" ]; then
   /usr/sbin/service isc-dhcp-server status 2>&1> /dev/null
   if  $? -eq 0 
   then
       /usr/sbin/service isc-dhcp-server stop
   fi
fi