#!/bin/bash

INTERFACE_1="rl0"
I1ROUTE="0.0.0.0"
INTERFACE_2="rl1"
I2ROUTE="0.0.0.0"

# redirection is setup as [primary outside]:[secoundary outside]:[inside]
IP_REDIRECT=""

# port redirection is setup as [inside]:[port]:[outside]:[port]
PORT_REDIRECT=""

######################
### END USER EDITS ###
######################

setup_nat()
	{
	for ADDY in `echo $IP_REDIRECT`; do
		if [ "$OTHER_INTERFACE" = "$INTERFACE_1" ] ; then
			IP_OUTSIDE=`echo $ADDY | awk -F : '{ print $1 }'`
		elif [ "$OTHER_INTERFACE" = "$INTERFACE_2" ] ; then
			IP_OUTSIDE=`echo $ADDY | awk -F : '{ print $2 }'`
		else
			echo "redirect interface not found" >> /var/log/netfix
		fi
	IP_INSIDE=`echo $ADDY | awk -F : '{ print $3 }'`
	REDIRECT="$REDIRECT -redirect_address $IP_INSIDE $IP_OUTSIDE"
	if [ "$OTHER_INTERFACE" = "$INTERFACE_1" ] ; then
		for PORT_ADDY in `echo $PORT_REDIRECT`; do
			IP_OUTSIDE=`echo $PORT_ADDY | awk -F : '{ print $3":"$4 }'`
			IP_INSIDE=`echo $PORT_ADDY | awk -F : '{ print $1":"$2 }'`
			REDIRECT="$REDIRECT -redirect_port tcp $IP_INSIDE $IP_OUTSIDE"
		done
	fi
	done
	}

ping_test()
	{
	if [ "$CURR_INTERFACE" = "$INTERFACE_2" ] ; then
		ifconfig $INTERFACE_1 up
		route add 128.9.0.107 $I1ROUTE > /dev/null
		route add 198.41.0.4 $I1ROUTE > /dev/null
		route add 192.33.4.12 $I1ROUTE > /dev/null
	fi

	TEST=0
	HINT1=""
	HINT1=`ping -c 1 -t 3 128.9.0.107 | grep "bytes from"`
	HINT2=""
	HINT2=`ping -c 1 -t 3 198.41.0.4 | grep "bytes from"`
	HINT3=""
	HINT3=`ping -c 1 -t 3 192.33.4.12 | grep "bytes from"`

	if [ "$HINT1" = "" ] ; then TEST=`echo 1+$TEST | bc`; fi
	if [ "$HINT2" = "" ] ; then TEST=`echo 1+$TEST | bc`; fi
	if [ "$HINT3" = "" ] ; then TEST=`echo 1+$TEST | bc`; fi

	if [ "$CURR_INTERFACE" = "$INTERFACE_2" ] ; then
		ifconfig $INTERFACE_1 down
		route delete 128.9.0.107 > /dev/null
		route delete 198.41.0.4 > /dev/null
		route delete 192.33.4.12 > /dev/null
	fi
	}

switch()
	{
	echo "$DATE changing from interface $CURR_INTERFACE to $OTHER_INTERFACE">> /var/log/netfix
	# wipe out old interface
	kill -TERM `cat /var/run/natd.pid`
	route delete default > /dev/null
	ipfw delete 50
	ifconfig $CURR_INTERFACE down
	# set up new interface
	ifconfig $OTHER_INTERFACE up
	ipfw add 50 divert natd all from any to any via $OTHER_INTERFACE >> /dev/null 2>> /var/log/netfix
	route add default $OTHER_ROUTE >> /dev/null 2>> /var/log/netfix
	sleep 10
	setup_nat
	natd -n $OTHER_INTERFACE $REDIRECT >> /dev/null 2>> /var/log/netfix
	}

####
# set your variables
####

DATE=`date`
CURR_INTERFACE=`ps -ax | awk '$5 ~ /^natd/ { print $7 }'`
if [ "$CURR_INTERFACE" = "$INTERFACE_1" ] ; then
	OTHER_INTERFACE=`echo "$INTERFACE_2"`
	CURR_ROUTE=`echo "$I1ROUTE"`
	OTHER_ROUTE=`echo "$I2ROUTE"`
elif [ "$CURR_INTERFACE" = "$INTERFACE_2" ] ; then
	OTHER_INTERFACE=`echo "$INTERFACE_1"`
	CURR_ROUTE=`echo "$I2ROUTE"`
	OTHER_ROUTE=`echo "$I1ROUTE"`
else
	echo "$date $CURR_INTERFACE interface unknown" >> /var/log/netfix
	exit
fi


#####
# test and switch if nessassary
#####


ping_test
if [ "$CURR_INTERFACE" = "$INTERFACE_2" ] ; then
	if [ "$TEST" = "0" ] ; then
		switch
	fi
else

	if [ "$TEST" = "3" ] ; then
	switch
	fi
fi