#this script will be called by dhclient whenever one of the DHCP configurations changes
#for further information, see `man dhclient-script`.

# received values
# $interface
#       Name of the interface
# $reason
#       Reason of the invocation of the call
#               MEDIUM
#               PREINIT
#               BIND
#               RENEW
#               REBIND
#               REBOOT
#               EXPIRE
#               FAIL
#               TIMEOUT
# $new_ip_address
#       new IP ADDRESS
# $new_routers
#       new routers

#Check wether this interface matters to us.
# it must be listed in the file /etc/dhep/interfaces
echo DHEP Interface: $interface
echo DHEP Reason: $reason

# If the interface is not listed, get out!
pattern=^$interface
showsup=$(grep $pattern /etc/dhep/interfaces | wc -l)
if [ $showsup = 0 ]; then
        echo This interface is not important to us
        echo Goint out
        exit
else
        echo This interface DOES matter
fi

#file with this interface's configuration
config=/etc/dhep/$interface.cfg

case $reason in
PREINIT | EXPIRE | FAIL)
        # We clean up the interface's configuration file
        echo Cleaning up interface's configuration file
        echo date $(date) > $config
        ;;
REBOOT | BIND | RENEW | REBIND)
        # we have grabbed an address from the DHCP server
        echo date $(date) > $config
        echo IP $new_ip_address >> $config
        echo GW $new_routers >> $config
        ;;
esac

#let's process the routes
grep '^[ \t]*[a-zA-Z]' /etc/dhep/interfaces | while read an_interface_line; do
#for an_interface in $(grep '^[ \t]*[a-zA-Z]' /etc/dhep/interfaces); do
        # let's look for the interface's line in the interfaces file
        length=$(expr length "$an_interface_line")
        interfacestart=$(expr index "$an_interface_line" abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ])
        interfaceend=$(expr index "$an_interface_line" ' ')
        if [ $interfaceend = 0 ]; then
                # no options
                interfacelength=$(($length-$interfacestart+1))
                interface=$(expr substr $an_interface_line $interfacestart $interfacelength)
                options=""
        else
                # interface and options
                interfacelength=$(($interfaceend-$interfacestart))
                interface=$(expr substr "$an_interface_line" $interfacestart $interfacelength)
                optionslength=$(($length-$interfaceend+1))
                options=$(expr substr "$an_interface_line" $(($interfaceend+1)) $optionslength
        fi
        echo Interface: $interface
        echo Options: $options

        # Let's get this interface's configuration
        config=/etc/dhep/$interface.cfg
        if [ $(grep IP $config | wc -l ) != 0 ]; then
                echo This card is configured as nexthop
                # IP?
                oneline=$(cat $config | grep IP)
                ip=$(expr substr "$oneline" 4 15)
                echo IP $ip
                oneline=$(cat $config | grep GW)
                gw=$(expr substr "$oneline" 4 15)
                echo GW $gw
                nexthop=$nexthop\ nexthop\ via\ $gw\ dev\ $interface\ $options
        fi
done
#removing default GWs
ip route del default
# let's set the route
ip route add scope global default $nexthop
# let's flush teh route cache
ip route flush cache