#!/bin/sh
# June/06 - Wayne Collins wayneco@dades.ca - changes for OpenWRT
# 1) Replaced c-style "for" loop with "while". Script can now we run with
# simple bourne shell or ash.
# 2) Added start_vpn_nat and stop_vpn_nat to handle NAT sharing of vpn
# connection.
# 3) Added vpn_led_pending, vpn_led_connected and vpn_led_disconnected to
# provide a visual indicator of VPN status
# Note - S99done should be changed so it won't clear the indicator
# try this one: http://www.dades.ca/openwrt/S99done
# 

#* reason                       -- why this script was called, one of: pre-init connect disconnect
#* VPNGATEWAY                   -- vpn gateway address (always present)
#* TUNDEV                       -- tunnel device (always present)
#* INTERNAL_IP4_ADDRESS         -- address (always present)
#* INTERNAL_IP4_NETMASK         -- netmask (often unset)
#* INTERNAL_IP4_DNS             -- list of dns serverss
#* INTERNAL_IP4_NBNS            -- list of wins servers
#* CISCO_DEF_DOMAIN             -- default domain name
#* CISCO_BANNER                 -- banner from server
#* CISCO_SPLIT_INC              -- number of networks in split-network-list
#* CISCO_SPLIT_INC_%d_ADDR      -- network address
#* CISCO_SPLIT_INC_%d_MASK      -- subnet mask (for example: 255.255.255.0)
#* CISCO_SPLIT_INC_%d_MASKLEN   -- subnet masklen (for example: 24)
#* CISCO_SPLIT_INC_%d_PROTOCOL  -- protocol (often just 0)
#* CISCO_SPLIT_INC_%d_SPORT     -- source port (often just 0)
#* CISCO_SPLIT_INC_%d_DPORT     -- destination port (often just 0)

#set -x

OS="`uname -s`"
DEFAULT_ROUTE_FILE=/var/run/vpnc/defaultroute
RESOLV_CONF_BACKUP=/var/run/vpnc/resolv.conf-backup

IPROUTE="`which ip 2> /dev/null`"

if [ "$OS" = "Linux" ]; then
	ifconfig_syntax_ptp="pointopoint"
	route_syntax_gw="gw"
	route_syntax_del="del"
	route_syntax_netmask="netmask"
else
	ifconfig_syntax_ptp=""
	route_syntax_gw=""
	route_syntax_del="delete"
	route_syntax_netmask="-netmask"
fi

####

do_pre_init() {
	if [ "$OS" = "Linux" ]; then
		if (exec 6<> /dev/net/tun) > /dev/null 2>&1 ; then
			:
		else # can't open /dev/net/tun
			test -e /proc/sys/kernel/modprobe && `cat /proc/sys/kernel/modprobe` tun 2>/dev/null
			# fix for broken devfs in kernel 2.6.x
			if [ "`readlink /dev/net/tun`" = misc/net/tun \
				-a ! -e /dev/net/misc/net/tun -a -e /dev/misc/net/tun ] ; then
				ln -sf /dev/misc/net/tun /dev/net/tun
			fi
			# make sure tun device exists
			if [ ! -e /dev/net/tun ]; then
				mkdir -p /dev/net
				mknod -m 0640 /dev/net/tun c 10 200
			fi
		fi
	elif [ "$OS" = "FreeBSD" ]; then
		:
	elif [ "$OS" = "NetBSD" ]; then
		:
	elif [ "$OS" = "OpenBSD" ]; then
		:
	elif [ "$OS" = "SunOS" ]; then
		:
	fi
}

do_ifconfig() {
	ifconfig "$TUNDEV" "$INTERNAL_IP4_ADDRESS" $ifconfig_syntax_ptp "$INTERNAL_IP4_ADDRESS" netmask 255.255.255.255 mtu 1412 up
}

if [ -n "$IPROUTE" ]; then
	fix_ip_get_output () {
		sed 's/cache//;s/metric[0-9]\+ [0-9]\+//g'
	}

	set_vpngateway_route() {
		$IPROUTE route add `ip route get "$VPNGATEWAY" | fix_ip_get_output`
		$IPROUTE route flush cache
	}
	
	del_vpngateway_route() {
		$IPROUTE route del "$VPNGATEWAY"
		$IPROUTE route flush cache
	}
	
	set_default_route() {
		$IPROUTE route | grep '^default' | fix_ip_get_output > "$DEFAULT_ROUTE_FILE"
		$IPROUTE route del default
		$IPROUTE route add default dev "$TUNDEV"
		$IPROUTE route flush cache
	}
	
	set_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		$IPROUTE route add "$NETWORK/$NETMASKLEN" dev "$TUNDEV"
		$IPROUTE route flush cache
	}
	
	reset_default_route() {
		$IPROUTE route del default > /dev/null 2>&1
		$IPROUTE route add `cat "$DEFAULT_ROUTE_FILE"`
		$IPROUTE route flush cache
	}
	
	del_network_route() {
		# linux deletes routes automatically if the device is shut down
		return
		#NETWORK="$1"
		#NETMASK="$2"
		#NETMASKLEN="$3"
		#$IPROUTE route del "$NETWORK/$NETMASKLEN" dev "$TUNDEV" 
		#$IPROUTE route flush cache
	}
else
	get_default_gw() {
		netstat -r -n | grep '^0.0.0.0' | awk '{print $2}'
	}
	
	set_vpngateway_route() {
		route add -host "$VPNGATEWAY" $route_syntax_gw "`get_default_gw`"
	}

	del_vpngateway_route() {
		route $route_syntax_del -host "$VPNGATEWAY"
	}
	
	set_default_route() {
		DEFAULTGW="`get_default_gw`"
		echo "$DEFAULTGW" > "$DEFAULT_ROUTE_FILE"
		route $route_syntax_del default
		route add default $route_syntax_gw "$INTERNAL_IP4_ADDRESS"
	}
	
	set_network_route() {
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		route add -net "$NETWORK" $route_syntax_netmask "$NETMASK" $route_syntax_gw "$INTERNAL_IP4_ADDRESS"
	}
	
	reset_default_route() {
		route $route_syntax_del default
		route add default $route_syntax_gw `cat "$DEFAULT_ROUTE_FILE"`
	}
	
	del_network_route() {
		if [ "$OS" = "Linux" ]; then
			# linux deletes routes automatically if the device is shut down
			return
		fi
		NETWORK="$1"
		NETMASK="$2"
		NETMASKLEN="$3"
		route $route_syntax_del -net "$NETWORK" $route_syntax_netmask "$NETMASK" $route_syntax_gw "$INTERNAL_IP4_ADDRESS"
	}
fi

write_resolvconf() {
	grep '^#@VPNC_GENERATED@' /etc/resolv.conf > /dev/null 2>&1 || cp -- /etc/resolv.conf "$RESOLV_CONF_BACKUP"
	NEW_RESOLVCONF="#@VPNC_GENERATED@ -- this file is generated by vpnc
# and will be overwritten by vpnc
# as long as the above mark is intact"
	
	exec 6< /etc/resolv.conf
	while read LINE <&6 ; do
		case "$LINE" in
			nameserver*)
				if [ -n "$INTERNAL_IP4_DNS" ]; then
					read ONE_NAMESERVER INTERNAL_IP4_DNS <<-EOF
	$INTERNAL_IP4_DNS
EOF
					LINE="nameserver $ONE_NAMESERVER"
				else
					LINE=""
				fi
				;;
			domain*|search*)
				if [ -n "$CISCO_DEF_DOMAIN" ]; then
					LINE="$LINE $CISCO_DEF_DOMAIN"
					CISCO_DEF_DOMAIN=""
				fi
				;;
		esac
		NEW_RESOLVCONF="$NEW_RESOLVCONF
$LINE"
	done
	exec 6<&-
	
	for i in $INTERNAL_IP4_DNS ; do
		NEW_RESOLVCONF="$NEW_RESOLVCONF
nameserver $i"
	done
	if [ -n "$CISCO_DEF_DOMAIN" ]; then
		NEW_RESOLVCONF="$NEW_RESOLVCONF
search $CISCO_DEF_DOMAIN"
	fi
	echo "$NEW_RESOLVCONF" > /etc/resolv.conf
}

reset_resolvconf() {
	if [ ! -e "$RESOLV_CONF_BACKUP" ]; then
		return
	fi
	grep '^#@VPNC_GENERATED@' /etc/resolv.conf > /dev/null 2>&1 && cat "$RESOLV_CONF_BACKUP" > /etc/resolv.conf
	rm -f -- "$RESOLV_CONF_BACKUP"
}

do_connect() {
	if [ -n "$CISCO_BANNER" ]; then
		echo "Connect Banner:"
		echo "$CISCO_BANNER" | while read LINE ; do echo "|" "$LINE" ; done
		echo
	fi
	
	do_ifconfig
	set_vpngateway_route
	if [ -n "$CISCO_SPLIT_INC" ]; then
		i=0 ; while [ "$i" -lt "$CISCO_SPLIT_INC" ] ; do
			eval NETWORK="\${CISCO_SPLIT_INC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_INC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_INC_${i}_MASKLEN}"
			set_network_route "$NETWORK" "$NETMASK" "$NETMASKLEN"
			i=$(($i + 1))
		done
		for i in $INTERNAL_IP4_DNS ; do
			set_network_route "$i" "255.255.255.255" "32"
		done
	else
		set_default_route
	fi
	
	if [ -n "$INTERNAL_IP4_DNS" ]; then
		write_resolvconf
	fi
}

do_disconnect() {
	if [ -n "$CISCO_SPLIT_INC" ]; then
		i=0 ; while [ "$i" -lt "$CISCO_SPLIT_INC" ] ; do
			eval NETWORK="\${CISCO_SPLIT_INC_${i}_ADDR}"
			eval NETMASK="\${CISCO_SPLIT_INC_${i}_MASK}"
			eval NETMASKLEN="\${CISCO_SPLIT_INC_${i}_MASKLEN}"
			del_network_route "$NETWORK" "$NETMASK" "$NETMASKLEN"
			i=$(($i + 1))
		done
		for i in $INTERNAL_IP4_DNS ; do
			del_network_route "$i" "255.255.255.255" "32"
		done
	else
		if [ -s "$DEFAULT_ROUTE_FILE" ]; then
			reset_default_route
			rm -f -- "$DEFAULT_ROUTE_FILE"
		fi
	fi
	
	del_vpngateway_route
	
	if [ -n "$INTERNAL_IP4_DNS" ]; then
		reset_resolvconf
	fi
}

start_vpn_nat() {
	iptables -A forwarding_rule -o tun0 -j ACCEPT
	iptables -A forwarding_rule -i tun0 -j ACCEPT
	iptables -t nat -A postrouting_rule -o tun0 -j MASQUERADE
}

stop_vpn_nat() {
	iptables -t nat -D postrouting_rule -o tun0 -j MASQUERADE
	iptables -D forwarding_rule -i tun0 -j ACCEPT
	iptables -D forwarding_rule -o tun0 -j ACCEPT
}

vpn_led_pending() {
	echo 1 > /proc/diag/led/ses
	echo 0 > /proc/diag/led/bridge
}

vpn_led_connected() {
	echo 0 > /proc/diag/led/ses
	echo 1 > /proc/diag/led/bridge
}

vpn_led_disconnected() {
	echo 0 > /proc/diag/led/ses
	echo 0 > /proc/diag/led/bridge
}

####

if [ -z "$reason" ]; then
	echo "this script must be called from vpnc" 1>&2
	exit 1
fi

case "$reason" in
	pre-init)
		vpn_led_pending
		do_pre_init
		;;
	connect)
		do_connect
		start_vpn_nat
		vpn_led_connected
		;;
	disconnect)
		stop_vpn_nat
		do_disconnect
		vpn_led_disconnected
		;;
	*)
		echo "unknown reason '$reason'. Maybe vpnc-script is out of date" 1>&2
		exit 1
		;;
esac

exit 0