#!/bin/bash
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2015 IPFire Team                                              #
#                                                                             #
# 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 3 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, see <http://www.gnu.org/licenses/>.       #
#                                                                             #
###############################################################################

shopt -s nullglob

VPN_CONFIG="/var/ipfire/vpn/config"

eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings)
eval $(/usr/local/bin/readhash /var/ipfire/vpn/settings)

VARS=(
	id status name lefthost type ctype psk local local_id leftsubnets
	remote_id remote rightsubnets x3 x4 x5 x6 x7 x8 x9 x10 x11 x12
	x13 x14 x15 x16 x17 x18 x19 proto x20 x21 x22
	route x23 mode interface_mode interface_address interface_mtu rest
)

log() {
	logger -t ipsec "$@"
}

resolve_hostname() {
	local hostname="${1}"

	dig +short A "${hostname}" | tail -n1
}

main() {
	# Register local variables
	local "${VARS[@]}"
	local action

	local interfaces=()

	# We are done when IPsec is not enabled
	if [ "${ENABLED}" = "on" ]; then
		while IFS="," read -r "${VARS[@]}"; do
			# Check if the connection is enabled
			[ "${status}" = "on" ] || continue

			# Check if this a net-to-net connection
			[ "${type}" = "net" ] || continue

			# Determine the interface name
			case "${interface_mode}" in
				gre|vti)
					local intf="${interface_mode}${id}"
					;;
				*)
					continue
					;;
			esac

			# Add the interface to the list of all interfaces
			interfaces+=( "${intf}" )

			# Compat for older connections
			if [ "${local}" = "off" ]; then
				if [ "${VPN_IP}" = "%defaultroute" ]; then
					local=""
				else
					local="${VPN_IP}"
				fi
			fi

			# Handle %defaultroute
			if [ -z "${local}" ]; then
				if [ -r "/var/ipfire/red/local-ipaddress" ]; then
					local="$(</var/ipfire/red/local-ipaddress)"

				elif [ "${RED_TYPE}" = "STATIC" -a -n "${RED_ADDRESS}" ]; then
					local="${RED_ADDRESS}"
				fi
			fi

			# Resolve any hostnames
			if [[ ! ${remote} =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
				remote="$(resolve_hostname "${remote}")"
			fi

			local args=(
				"local" "${local}"
				"remote" "${remote}"
			)

			case "${interface_mode}" in
				gre)
					# Add TTL
					args+=( "ttl" "255" )
					;;

				vti)
					# Add key for VTI
					args+=( "key" "${id}" )
					;;
			esac

			# Update the settings when the interface already exists
			if [ -d "/sys/class/net/${intf}" ]; then
				ip link change dev "${intf}" \
					type "${interface_mode}" "${args[@]}" &>/dev/null

			# Create a new interface and bring it up
			else
				log "Creating interface ${intf}"
				if ! ip link add name "${intf}" type "${interface_mode}" "${args[@]}"; then
					log "Could not create interface ${intf}"
					continue
				fi
			fi

			# Add an IP address
			ip addr flush dev "${intf}"
			ip addr add "${interface_address}" dev "${intf}"

			# Set MTU
			ip link set dev "${intf}" mtu "${interface_mtu}"

			# Bring up the interface
			ip link set dev "${intf}" up
		done < "${VPN_CONFIG}"
	fi

	# Delete all other interfaces
	local intf
	for intf in /sys/class/net/gre[0-9]* /sys/class/net/vti[0-9]*; do
		intf="$(basename "${intf}")"

		# Ignore a couple of interfaces that cannot be deleted
		case "${intf}" in
			gre0|gretap0)
				continue
				;;
		esac

		# Check if interface is on the list
		local i found="false"
		for i in ${interfaces[@]}; do
			if [ "${intf}" = "${i}" ]; then
				found="true"
				break
			fi
		done

		# Nothing to do if interface was found
		${found} && continue

		# Delete the interface
		log "Deleting interface ${intf}"
		ip link del "${intf}" &>/dev/null
	done

	# (Re-)Apply all static routes
	/etc/init.d/static-routes start
}

main || exit $?