#!/bin/sh

. /lib/functions.sh
. /lib/mwan3/common.sh

LOG="logger -t $(basename "$0")[$$] -p"
INTERFACE=""
DEVICE=""

IFDOWN_EVENT=0

clean_up() {
	$LOG notice "Stopping mwan3track for interface \"${INTERFACE}\""
	exit 0
}

if_down() {
	$LOG info "Detect ifdown event on interface ${INTERFACE} (${DEVICE})"
	IFDOWN_EVENT=1
}

validate_track_method() {
	case "$1" in
		ping)
			which ping 1>/dev/null 2>&1 || {
				$LOG warn "Missing ping. Please install iputils-ping package or enable ping util and recompile busybox."
				return 1
			}
			;;
		arping)
			which arping 1>/dev/null 2>&1 || {
				$LOG warn "Missing arping. Please install iputils-arping package."
				return 1
			}
			;;
		httping)
			which httping 1>/dev/null 2>&1 || {
				$LOG warn "Missing httping. Please install httping package."
				return 1
			}
			[ -n "$2" -a "$2" != "0.0.0.0" -a "$2" != "::" ] || {
				$LOG warn "Cannot determine source IP for the interface which is required by httping."
				return 1
			}
			;;
		nping-*)
			which nping 1>/dev/null 2>&1 || {
				$LOG warn "Missing nping. Please install nping package."
				return 1
			}
			;;
		*)
			$LOG warn "Unsupported tracking method: $track_method"
			return 2
			;;
	esac
}

main() {
	local reliability count timeout interval failure_interval
	local recovery_interval down up size
	local keep_failure_interval check_quality failure_latency
	local recovery_latency failure_loss recovery_loss
	local max_ttl httping_ssl

	[ -z "$5" ] && echo "Error: should not be started manually" && exit 0

	INTERFACE=$1
	DEVICE=$2
	STATUS=$3
	SRC_IP=$4
	mkdir -p /var/run/mwan3track/$1
	trap clean_up TERM
	trap if_down USR1

	config_load mwan3
	config_get track_method $1 track_method ping
	config_get_bool httping_ssl $1 httping_ssl 0
	validate_track_method $track_method $SRC_IP || {
		track_method=ping
		if validate_track_method $track_method; then
			$LOG warn "Using ping to track interface $INTERFACE avaliability"
		else
			$LOG err "No track method avaliable"
			exit 1
		fi
	}
	config_get reliability $1 reliability 1
	config_get count $1 count 1
	config_get timeout $1 timeout 4
	config_get interval $1 interval 10
	config_get down $1 down 5
	config_get up $1 up 5
	config_get size $1 size 56
	config_get max_ttl $1 max_ttl 60
	config_get failure_interval $1 failure_interval $interval
	config_get_bool keep_failure_interval $1 keep_failure_interval 0
	config_get recovery_interval $1 recovery_interval $interval
	config_get_bool check_quality $1 check_quality 0
	config_get failure_latency $1 failure_latency 1000
	config_get recovery_latency $1 recovery_latency 500
	config_get failure_loss $1 failure_loss 40
	config_get recovery_loss $1 recovery_loss 10

	local score=$(($down+$up))
	local track_ips=$(echo $* | cut -d ' ' -f 5-99)
	local host_up_count=0
	local lost=0
	local sleep_time=0
	local turn=0
	local result
	local ping_result
	local loss=0
	local latency=0

	if [ "$STATUS" = "offline" ]; then
		echo "offline" > /var/run/mwan3track/$1/STATUS
		echo "0" > /var/run/mwan3track/$1/ONLINE
		echo "$(get_uptime)" > /var/run/mwan3track/$1/OFFLINE
		score=0
	else
		echo "online" > /var/run/mwan3track/$1/STATUS
		echo "0" > /var/run/mwan3track/$1/OFFLINE
		echo "$(get_uptime)" > /var/run/mwan3track/$1/ONLINE
		env -i ACTION="connected" INTERFACE="$1" DEVICE="$2" /sbin/hotplug-call iface
	fi
	while true; do

		sleep_time=$interval

		for track_ip in $track_ips; do
			if [ $host_up_count -lt $reliability ]; then
				case "$track_method" in
					ping)
						# pinging IPv6 hosts with an interface is troublesome
						# https://bugs.openwrt.org/index.php?do=details&task_id=2897
						# so get the IP address of the interface and use that instead				   
						if echo $track_ip | grep -q ':'; then
							ADDR=$(ip -6 addr ls dev "$DEVICE" | sed -ne 's/ *inet6 \([^ \/]*\).* scope global.*/\1/p')
						fi
						if [ $check_quality -eq 0 ]; then
							ping -I ${ADDR:-$DEVICE} -c $count -W $timeout -s $size -t $max_ttl -q $track_ip &> /dev/null
							result=$?
						else
							ping_result="$(ping -I ${ADDR:-$DEVICE} -c $count -W $timeout -s $size -t $max_ttl -q $track_ip | tail -2)"
							loss="$(echo "$ping_result" | grep "packet loss" |  cut -d "," -f3 | awk '{print $1}' | sed -e 's/%//')"
							if [ "$loss" -eq 100 ]; then
								latency=999999
							else
								latency="$(echo "$ping_result" | grep -E 'rtt|round-trip' | cut -d "=" -f2 | cut -d "/" -f2 | cut -d "." -f1)"
							fi
						fi
					;;
					arping)
						arping -I $DEVICE -c $count -w $timeout -q $track_ip &> /dev/null
						result=$?
					;;
					httping)
						if [ "$httping_ssl" -eq 1 ]; then
							httping -y $SRC_IP -c $count -t $timeout -q "https://$track_ip" &> /dev/null
						else
							httping -y $SRC_IP -c $count -t $timeout -q "http://$track_ip" &> /dev/null
						fi
						result=$?
					;;
					nping-tcp)
						result=$(nping -e $DEVICE -c $count $track_ip --tcp | grep Lost | awk '{print $12}')
					;;
					nping-udp)
						result=$(nping -e $DEVICE -c $count $track_ip --udp | grep Lost | awk '{print $12}')
					;;
					nping-icmp)
						result=$(nping -e $DEVICE -c $count $track_ip --icmp | grep Lost | awk '{print $12}')
					;;
					nping-arp)
						result=$(nping -e $DEVICE -c $count $track_ip --arp | grep Lost | awk '{print $12}')
					;;
				esac
				if [ $check_quality -eq 0 ]; then
					if [ $result -eq 0 ]; then
						let host_up_count++
						echo "up" > /var/run/mwan3track/$1/TRACK_${track_ip}
						if [ $score -le $up ]; then
							$LOG info "Check ($track_method) success for target \"$track_ip\" on interface $1 ($2)"
						fi
					else
						let lost++
						echo "down" > /var/run/mwan3track/$1/TRACK_${track_ip}
						if [ $score -gt $up ]; then
							$LOG info "Check ($track_method) failed for target \"$track_ip\" on interface $1 ($2)"
						fi
					fi
				else
					if [ "$loss" -ge "$failure_loss" -o "$latency" -ge "$failure_latency" ]; then
						let lost++
						echo "down" > /var/run/mwan3track/$1/TRACK_${track_ip}
						echo "$latency" > /var/run/mwan3track/$1/LATENCY_${track_ip}
						echo "$loss" > /var/run/mwan3track/$1/LOSS_${track_ip}

						if [ $score -gt $up ]; then
							$LOG info "Check (${track_method}: latency=${latency}ms loss=${loss}%) failed for target \"$track_ip\" on interface $1 ($2)"
						fi
					elif [ "$loss" -le "$recovery_loss" -a "$latency" -le "$recovery_latency" ]; then
						let host_up_count++
						echo "up" > /var/run/mwan3track/$1/TRACK_${track_ip}
						echo "$latency" > /var/run/mwan3track/$1/LATENCY_${track_ip}
						echo "$loss" > /var/run/mwan3track/$1/LOSS_${track_ip}

						if [ $score -le $up ]; then
							$LOG info "Check (${track_method}: latency=${latency}ms loss=${loss}%) success for target \"$track_ip\" on interface $1 ($2)"
						fi
					else
						echo "skipped" > /var/run/mwan3track/$1/TRACK_${track_ip}
					fi
				fi
			else
				echo "skipped" > /var/run/mwan3track/$1/TRACK_${track_ip}
			fi
		done

		if [ $host_up_count -lt $reliability ]; then
			let score--

			if [ $score -lt $up ]; then
				score=0
				[ ${keep_failure_interval} -eq 1 ] && {
					sleep_time=$failure_interval
				}
			else
				sleep_time=$failure_interval
			fi

			if [ $score -eq $up ]; then
				echo "offline" > /var/run/mwan3track/$1/STATUS
				env -i ACTION=ifdown INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				score=0
			fi
		else
			if [ $score -lt $(($down+$up)) ] && [ $lost -gt 0 ]; then
				$LOG info "Lost $(($lost*$count)) ping(s) on interface $1 ($2)"
			fi

			let score++
			lost=0

			if [ $score -gt $up ]; then
				echo "online" > /var/run/mwan3track/$1/STATUS
				score=$(($down+$up))
			elif [ $score -le $up ]; then
				sleep_time=$recovery_interval
			fi

			if [ $score -eq $up ]; then
				$LOG notice "Interface $1 ($2) is online"
				echo "online" > /var/run/mwan3track/$1/STATUS
				env -i ACTION=ifup INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				exit 0
			fi
		fi

		let turn++
		mkdir -p "/var/run/mwan3track/${1}"
		echo "${lost}" > /var/run/mwan3track/$1/LOST
		echo "${score}" > /var/run/mwan3track/$1/SCORE
		echo "${turn}" > /var/run/mwan3track/$1/TURN
		echo "$(get_uptime)" > /var/run/mwan3track/$1/TIME

		host_up_count=0
		sleep "${sleep_time}" &
		wait

		if [ "${IFDOWN_EVENT}" -eq 1 ]; then
			echo "offline" > /var/run/mwan3track/$1/STATUS
			echo "$(get_uptime)" > /var/run/mwan3track/$1/OFFLINE
			echo "0" > /var/run/mwan3track/$1/ONLINE
			$LOG notice "Interface $1 ($2) is offline"
			env -i ACTION="disconnected" INTERFACE="$1" DEVICE="$2" /sbin/hotplug-call iface
			score=0
			IFDOWN_EVENT=0
		fi
	done
}

main "$@"