#!/bin/sh
# -------
# File:        llxcfg-net
# Description: LliureX net tool
# Author:      Luis Garcia Gisbert <garcia_luigis@gva.es>
# 
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along 
# with this program; if not, write to the Free Software Foundation, Inc., 
# 51 Franklin St, Fifth Floor, Boston MA 02110-1301 USA
# --------

set -e

PATH="/usr/sbin:/usr/bin:/sbin:/bin"

# library

die(){
	echo "$1" >&2
	exit 1
}

usage(){
	die "Usage: $(basename "$0") update\n\
       $(basename "$0") ACTION {enable|disable|test|status} [PARAMETERS]\n\
       ACTIONS: routing\n\
                persistence\n\
		services\n\
                nat (requires NET_EXT_IFACE and NET_INT_IFACE)"
}

fwd_change(){
	echo $1 > $PROC_NET_FWD
}

fwd_test(){
	[ $(cat $PROC_NET_FWD) -eq 0 ] || return 0
	return 1
}

nat_rules(){
	local rc
	rc=0
	iptables -t nat -${1} POSTROUTING -o $NET_EXT_IFACE -j MASQUERADE || rc=$?
	for IFACE in $NET_INT_IFACE ; do
		iptables -${1} FORWARD -i $NET_EXT_IFACE -o $IFACE -m state --state RELATED,ESTABLISHED -j ACCEPT || rc=$?
		iptables -${1} FORWARD -i $IFACE -o $NET_EXT_IFACE -j ACCEPT || rc=$?
	done
	return $rc
}

nat_disable(){
	nat_test_vars || return 0
	nat_rules D >/dev/null 2>/dev/null || true
	rm -f $NAT_FLAG_FILE
}

nat_enable(){
	nat_test_vars || return 0
	nat_rules D >/dev/null 2>/dev/null || true
	if nat_rules A ; then
		fwd_change 1
		mkdir -p $NAT_FLAG_DIR
		touch $NAT_FLAG_FILE
	else
		nat_disable
		die "Error enabling nat"
	fi
}

nat_test(){
	[ -r "$NAT_FLAG_FILE" ] || return 1
	return 0
}

nat_test_vars(){
	[ "$NET_EXT_IFACE" -a "$NET_INT_IFACE" ] || return 1
	return 0
}

persistence_test(){
	eval "$(llxcfg-showvars NET_PERSISTENCE)"
	[ "$NET_PERSISTENCE" != "ENABLED" ] || return 0
	return 1
}

save_status(){
	if nat_test ; then
		NET_NAT_STATUS="ENABLED"
	else
		NET_NAT_STATUS="DISABLED"
	fi
	if fwd_test ; then
		NET_FWD_STATUS="ENABLED"
	else
		NET_FWD_STATUS="DISABLED"
	fi
	# NET_..._STATUS vars are for internal use only, so we use systemvars
	llxcfg-systemvars add NET_NAT_STATUS="$NET_NAT_STATUS" NET_FWD_STATUS="$NET_FWD_STATUS"
	return 0
}

PROC_NET_FWD="/proc/sys/net/ipv4/ip_forward"
NAT_FLAG_DIR="/var/run/llxcfg-net"
NAT_FLAG_FILE="$NAT_FLAG_DIR/NAT"

# main
NET_ACTION="$1"
NET_CMD="$2"

[ "$NET_ACTION" -a "$NET_CMD" ] || usage
shift 2

case $NET_CMD in
	enable|disable|test|status)
	;;
	*)
		usage
	;;
esac

eval "$(llxcfg-showvars NET_EXT_IFACE NET_INT_IFACE)"

case $NET_ACTION in
	routing)
		case $NET_CMD in
			enable)
				fwd_change 1
				;;
			disable)
				fwd_change 0
				;;
			test)
				rc=0
				fwd_test || rc=$?
				exit $rc
				;;
			status)
				if fwd_test ; then
					echo "routing is ENABLED"
				else
					echo "routing is DISABLED"
				fi
				;;
		esac
		;;
	nat)
		nat_test_vars || die "Invalid values for NET_EXT_IFACE NET_INT_IFACE"
		case $NET_CMD in
			enable)
				nat_enable
				;;
			disable)
				nat_disable
				;;
			test)
				rc=0
				nat_test || rc=$?
				exit $rc
				;;
			status)
				if nat_test ; then
					echo "nat is ENABLED"
				else
					echo "nat is DISABLED"
				fi
				;;
		esac
		;;
	persistence)
		case $NET_CMD in
			enable)
				llxcfg-setvars NET_PERSISTENCE="ENABLED"
				save_status
				;;
			disable)
				llxcfg-setvars NET_PERSISTENCE="DISABLED"
				save_status
				;;
			test)
				rc=0
				persistence_test || rc=$?
				exit $rc
				;;
			status)
				if persistence_test ; then
					echo "persistence is ENABLED"
				else
					echo "persistence is DISABLED"
				fi
				;;
		esac
		;;
	services)
		case $NET_CMD in
			enable)
				eval "$(llxcfg-showvars NET_EXT_IFACE NET_INT_IFACE NET_PERSISTENCE NET_NAT_STATUS NET_FWD_STATUS)"
				if persistence_test ; then
					if [ "$NET_NAT_STATUS" = "ENABLED" ] ; then
						nat_enable
					else
						nat_disable
						if [ "$NET_FWD_STATUS" = "ENABLED" ] ; then
							fwd_change 1
						else
							fwd_change 0
						fi
					fi
				fi
				;;
			disable)
				nat_disable
				fwd_change 0
				;;
			test)
				fwd_test || persistence_test || exit 1
				exit 0
				;;
			status)
				for s in routing nat ; do
					$0 $s status
				done
				;;
		esac
		;;
	*)
		usage
		;;
esac

exit 0