#!/bin/bash
nat_rules(){
        local rc
        rc=0
        iptables -t nat -${OPTION} POSTROUTING -o $NET_EXT_IFACE -j MASQUERADE || rc=$?
        for AUX_IFACE in $NET_INT_IFACE ; do
                iptables -${OPTION} FORWARD -i $NET_EXT_IFACE -o $AUX_IFACE -m state --state RELATED,ESTABLISHED -j ACCEPT || rc=$?
                iptables -${OPTION} FORWARD -i $AUX_IFACE -o $NET_EXT_IFACE -j ACCEPT || rc=$?
        done
        #return $rc
}

nat_replication(){
	REPLICATIONIP=$(/usr/bin/netplan-query $NET_EXT_IFACE replication_ip)
	REPLICATIONNETWORK=$(/usr/bin/netplan-query $NET_EXT_IFACE replication_network)
	for AUX_IFACE in $NET_INT_IFACE; do
		AUXNETWORK=$(/usr/bin/netplan-query $AUX_IFACE network)
		iptables -${OPTION} FORWARD -i $AUX_IFACE -o $NET_EXT_IFACE -j ACCEPT
		iptables -${OPTION} FORWARD -i $NET_EXT_IFACE -o $AUX_IFACE -j ACCEPT
		if [ "${OPTION}" = "A" ]; then
			iptables -I POSTROUTING -t nat -o $NET_EXT_IFACE -s $AUXNETWORK -d $REPLICATIONNETWORK -j SNAT --to $REPLICATIONIP
		else
			iptables -D POSTROUTING -t nat -o $NET_EXT_IFACE -s $AUXNETWORK -d $REPLICATIONNETWORK -j SNAT --to $REPLICATIONIP
		fi
	done
}


check_arguments(){
  if [ "$#" -lt "2" ]; then
  	exit 0 
  fi
}

parse_arguments(){
  if [ -z "$IFACE" ]; then
    if [ -z "$2" ]; then
    	exit 0
    fi
    IFACE=$2
  fi
  OPTION=$1
  NET_EXT_IFACE=$IFACE
  NET_INT_IFACE=`$PATH_INTERNAL_INTERFACES`
  if [ -z "$NET_INT_IFACE" ]; then
	echo "script to get internal interfaces is void"
  	exit 0
  fi

}

load_default_settings(){
	PATH_INTERNAL_INTERFACES=""
	[ ! -e /etc/nat_enabler.conf ] || . /etc/nat_enabler.conf

}
#####################
##		   ##
##	Main	   ##
##		   ##
#####################

check_arguments $@
load_default_settings
parse_arguments $@
case $OPTION in
"deactivate" )
	if `iptables-save -t nat | grep "\-A POSTROUTING \-o $NET_EXT_IFACE \-j MASQUERADE" 1>/dev/null 2>&1` ; then  
		OPTION="D"
                nat_rules 
	fi

	;;
"activate" )
	if ! `iptables-save -t nat | grep "\-A POSTROUTING \-o $NET_EXT_IFACE \-j MASQUERADE" 1>/dev/null 2>&1` ; then 
		OPTION="A"
		nat_rules
	fi
	;;

"activate_replication_nat" )
	if ! `iptables-save -t nat | grep "\-A POSTROUTING" | grep  "\-o $NET_EXT_IFACE \-j SNAT" 1>/dev/null 2>&1` ; then 
		OPTION="A"
		nat_replication
	fi

	;;

"deactivate_replication_nat" )
	if `iptables-save -t nat | grep "\-A POSTROUTING" | grep  "\-o $NET_EXT_IFACE \-j SNAT" 1>/dev/null 2>&1` ; then  
		OPTION="D"
                nat_replication
	fi

	;;

esac

sleep infinity