#!/bin/sh

# Copyright(C) 2018, Rafal Kupiec <belliash@codingworkshop.eu.org>

source /lib/functions/network.sh

DAEMONIZE=0
LOGGER_ALERT=1
LOGGER_CRITICAL=2
LOGGER_ERROR=3
LOGGER_WARNING=4
LOGGER_NOTICE=5
LOGGER_INFO=6
LOGGER_DEBUG=7

function initialize() {
	/usr/bin/logger -t $0 -p ${LOGGER_NOTICE} "Starting WAN Monitor ..."
	sleep 60
	/usr/bin/logger -t $0 -p ${LOGGER_NOTICE} "Initializing WAN Monitor & Failover Connection Manager"

	CHECK_HOST=$(/sbin/uci -q get wanmonitor.@wanmonitor[0].check_host)
	INTERVAL=$(/sbin/uci -q get wanmonitor.@wanmonitor[0].interval)
	WAN_PRIMARY=$(/sbin/uci -q get wanmonitor.@wanmonitor[0].wan_primary)
	WAN_SECONDARY=$(/sbin/uci -q get wanmonitor.@wanmonitor[0].wan_secondary)

	network_get_device IFNAME_WAN_PRIMARY ${WAN_PRIMARY}
	network_get_gateway GATEWAY_WAN_PRIMARY ${WAN_PRIMARY}
	network_get_device IFNAME_WAN_SECONDARY ${WAN_SECONDARY}
	network_get_gateway GATEWAY_WAN_SECONDARY ${WAN_SECONDARY}

	if [ "x${IFNAME_WAN_PRIMARY}" = "x" ]; then
		IFNAME_WAN_PRIMARY=$(/sbin/uci -q -P /var/state get network.${WAN_PRIMARY}.ifname)
	fi

	if [ "x${GATEWAY_WAN_PRIMARY}" = "x" ]; then
		GATEWAY_WAN_PRIMARY=$(uci -q -P /var/state get network.${WAN_PRIMARY}.gateway)
	fi
	if [ "x${GATEWAY_WAN_PRIMARY}" = "x" ]; then
		GATEWAY_WAN_PRIMARY=$(ifstatus ${WAN_PRIMARY} | grep -A 2 "\"target\": \"0.0.0.0\"," | awk '/nexthop/ {gsub(/[",]/, "");print $2}')
	fi
		
	if [ "x${IFNAME_WAN_SECONDARY}" = "x" ]; then
		IFNAME_WAN_SECONDARY=$(/sbin/uci -q -P /var/state get network.${WAN_SECONDARY}.ifname)
	fi

	if [ "x${GATEWAY_WAN_SECONDARY}" = "x" ]; then
		GATEWAY_WAN_SECONDARY=$(uci -q -P /var/state get network.${WAN_SECONDARY}.gateway)
	fi
	if [ "x${GATEWAY_WAN_SECONDARY}" = "x" ]; then
		GATEWAY_WAN_SECONDARY=$(ifstatus ${WAN_SECONDARY} | grep -A 2 "\"target\": \"0.0.0.0\"," | awk '/nexthop/ {gsub(/[",]/, "");print $2}')
	fi

	for IFNAME_WAN in ${IFNAME_WAN_PRIMARY} ${IFNAME_WAN_SECONDARY}; do
		if [ "x${IFNAME_WAN}" = "x" ]; then
			/usr/bin/logger -t $0 -p ${LOGGER_CRITICAL} "Lack of logical interface for one of WAN connections!"
			exit 1
		fi	
	done

	for GATEWAY_WAN in ${GATEWAY_WAN_PRIMARY} ${GATEWAY_WAN_SECONDARY}; do
		if [ "x${GATEWAY_WAN}" = "x" ]; then
			/usr/bin/logger -t $0 -p ${LOGGER_CRITICAL} "Lack of gateway on logical interface for one of WAN connections!"
			exit 2
		fi
	done

	/usr/bin/logger -t $0 -p ${LOGGER_DEBUG} "Primary WAN Interface: ${IFNAME_WAN_PRIMARY}, Gateway: ${GATEWAY_WAN_PRIMARY}"
	/usr/bin/logger -t $0 -p ${LOGGER_DEBUG} "Secondary WAN Interface: ${IFNAME_WAN_SECONDARY}, Gateway: ${GATEWAY_WAN_SECONDARY}"
	/usr/bin/logger -t $0 -p ${LOGGER_DEBUG} "Checking host: ${CHECK_HOST} every ${INTERVAL} seconds interval"
}

until [[ -z "${1}" ]]; do
	case "${1}" in
		-d|--daemon)
			DAEMONIZE=1
			;;
		*)
			echo "Unknown option: ${1}"
			;;
	
	esac
	shift
done

if [ "x${DAEMONIZE}" = "x0" ]; then
	echo "This program can be running only as daemon. Please use init script."
	exit 0
fi

initialize
/usr/bin/logger -t $0 -p ${LOGGER_NOTICE} "Entering link monitoring loop ..."
WAN=0
while true; do
	WAN_PRIMARY_STATUS=$(ifstatus ${WAN_PRIMARY} | grep \"up\" | awk '{gsub(/[",]/, ""); print $2}')
	if [ "x${WAN_PRIMARY_STATUS}" = "xtrue" ]; then
		CHECK_ROUTE=$(route | grep ${CHECK_HOST} | grep ${IFNAME_WAN_PRIMARY} | wc -l)
		if [ "x${CHECK_ROUTE}" = "x0" ]; then
			/sbin/route add -host ${CHECK_HOST} gateway ${GATEWAY_WAN_PRIMARY} ${IFNAME_WAN_PRIMARY} &>/dev/null
		fi
		WAN_PRIMARY_PING=$(ping -I ${IFNAME_WAN_PRIMARY} -w 3 -c 3 ${CHECK_HOST} 2>/dev/null | awk '/packets received/ {print $4}')
	fi
	if [ "x${WAN_PRIMARY_STATUS}" = "xfalse" ] || [ "x${WAN_PRIMARY_PING}" = "x0" ]; then
		if [ "${WAN}" = "0" ] || [ "${WAN}" = "1" ]; then
			/usr/bin/logger -t $0 -p ${LOGGER_ALERT} "Primary WAN Interface is DOWN! Switching traffic to ${WAN_SECONDARY}."
			/sbin/route del default gw ${GATEWAY_WAN_PRIMARY} ${IFNAME_WAN_PRIMARY} &>/dev/null
			/sbin/route add default gw ${GATEWAY_WAN_SECONDARY} ${IFNAME_WAN_SECONDARY} &>/dev/null
			WAN=2
		fi
	else
		if [ "${WAN}" = "0" ] || [ "${WAN}" = "2" ]; then
			/usr/bin/logger -t $0 -p ${LOGGER_ALERT} "Primary WAN Interface is UP! Switching traffic to ${WAN_PRIMARY}."
			/sbin/route del default gw ${GATEWAY_WAN_SECONDARY} ${IFNAME_WAN_SECONDARY} &>/dev/null
			/sbin/route add default gw ${GATEWAY_WAN_PRIMARY} ${IFNAME_WAN_PRIMARY} &>/dev/null
			WAN=1
		fi
	fi
	sleep ${INTERVAL}
done