#!/bin/bash
#
# Script to automatically set up 6to4-tunnel
# Usage: 6to4tunnel-control {start|stop} ipv4address
#
# Author:	Roshan Revankar <rrevankar (at) yahoo.com>
#			http://www.geocities.com/rosh98
#			http://roshweb.blogspot.com
#
#			All the commands(including the comments accompanying them;)) for setting
#			up the ipv6 tunnel are from Peter Bieringer's
#			excellent Linux IPv6 HOWTO at http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/
#
# This script can be called from /etc/ppp/ip-up to set up the tunnel and
# from /etc/ppp/ip-down to bring down the tunnel
# eg., The following can be used in /etc/ppp/ip-up to set up the tunnel
#			6to4tunnel-control start $4
# 	   The following in /etc/ppp/ip-down brings down the tunnel
#			6to4tunnel-control stop


LOGFILE=/etc/ppp/ipv6-log
IS_IPV6_LOADED=0
IPV4_ADDR=$2
IS_SUCCESS=0

function check_cmd_status(){
	 if [ $IS_SUCCESS != 1 ]; then exit 0; fi
	 IS_SUCCESS=0
}

function setup_6to4_tunnel(){
	 echo Setting up 6to4 tunnel >> $LOGFILE
	# Create a new tunnel device
	/sbin/ip tunnel add tun6to4 mode sit remote any local $IPV4_ADDR >> $LOGFILE 2>&1 && IS_SUCCESS=1
	check_cmd_status
	# Bring interface up
	/sbin/ip link set dev tun6to4 up >> $LOGFILE 2>&1 && IS_SUCCESS=1
	check_cmd_status
	# Add local 6to4 address to interface (note: prefix length 16 is imporant!)
	/sbin/ip -6 addr add $IPV6_ADDR/16 dev tun6to4 >> $LOGFILE 2>&1 && IS_SUCCESS=1
	check_cmd_status
	# Add (default) route to the global IPv6 network using the all-6to4-routers IPv4 anycast address
	/sbin/ip -6 route add 2000::/3 via ::192.88.99.1 dev tun6to4 metric 1 >> $LOGFILE 2>&1	&& IS_SUCCESS=1
	check_cmd_status
}

function remove_6to4_tunnel(){
	echo Removing 6to4 tunnel >> $LOGFILE
	# Remove all routes through this dedicated tunnel device
	/sbin/ip -6 route flush dev tun6to4
	# Shut down interface
	/sbin/ip link set dev tun6to4 down
	# Remove created tunnel device
	/sbin/ip tunnel del tun6to4
}

function is_tunnel_up(){
	IS_TUNNEL_UP=`/sbin/ip -6 tunnel show tun6to4`
	if [ "$IS_TUNNEL_UP" != "" ]; then
		echo "Check 6to4 tunnel status:6to4 tunnel is up" >> $LOGFILE
		echo IS_TUNNEL_UP >> $LOGFILE	
		return 1
	else
		echo "Check 6to4 tunnel status:6to4 tunnel is not up" >> $LOGFILE
		return 0
	fi
}

function start() {
	# Setup IPv6
	date > $LOGFILE
	echo Bringing up IPv6 >> $LOGFILE
	echo IPv4 address is $IPV4_ADDR >> $LOGFILE

	# Test if ipv6 was loaded into the kernel
	test -f /proc/net/if_inet6 && IS_IPV6_LOADED = 1
	echo $IS_IPV6_LOADED >> $LOGFILE
	if [ $IS_IPV6_LOADED = 0 ]; then
		# its not loaded, so attempt to load it
		/sbin/modprobe ipv6 >> $LOGFILE 2>&1 && IS_SUCCESS=1
		check_cmd_status
	fi

	# First generate the IPv6 address from IPv4 address
	TMP_ADDR=`echo $IPV4_ADDR | tr "." " "`
	IPV6_ADDR=`printf "2002:%02x%02x:%02x%02x::1" $TMP_ADDR`
	echo IPV6 address is $IPV6_ADDR >> $LOGFILE

	is_tunnel_up
	if [ $? = 1 ] ; then
		remove_6to4_tunnel
	fi
	setup_6to4_tunnel
}

function stop() {
	    is_tunnel_up
		if [ $? = 1 ] ; then
			remove_6to4_tunnel
		fi
}

 
  
case "$1" in
	start)
		start
		;;
			 
	stop)
	    stop
	    ;;
	*)
	    echo $"Usage: $0 {start|stop} ipv4address"
	    exit 1
esac