#!/bin/sh

mwan3_get_iface_id()
{
	let iface_count++
	[ "$1" == "$INTERFACE" ] && iface_id=$iface_count
}

mwan3_set_general_iptables()
{
	if ! $IPT -S mwan3_ifaces &> /dev/null; then
		$IPT -N mwan3_ifaces
	fi

	if ! $IPT -S mwan3_connected &> /dev/null; then
		$IPT -N mwan3_connected
		$IPS create mwan3_connected hash:net
		$IPT -A mwan3_connected -m set --match-set mwan3_connected dst -j MARK --set-xmark 0xff00/0xff00
	fi

	if ! $IPT -S mwan3_track &> /dev/null; then
		$IPT -N mwan3_track
	fi

	if ! $IPT -S mwan3_rules &> /dev/null; then
		$IPT -N mwan3_rules
	fi

	if ! $IPT -S mwan3_hook &> /dev/null; then
		$IPT -N mwan3_hook
		$IPT -A mwan3_hook -j CONNMARK --restore-mark --nfmask 0xff00 --ctmask 0xff00
		$IPT -A mwan3_hook -m mark --mark 0x0/0xff00 -j mwan3_ifaces
		$IPT -A mwan3_hook -m mark --mark 0x0/0xff00 -j mwan3_connected
		$IPT -A mwan3_hook -m mark --mark 0x0/0xff00 -j mwan3_track
		$IPT -A mwan3_hook -m mark --mark 0x0/0xff00 -j mwan3_rules
		$IPT -A mwan3_hook -j CONNMARK --save-mark --nfmask 0xff00 --ctmask 0xff00
		$IPT -A mwan3_hook -m mark ! --mark 0xff00/0xff00 -j mwan3_connected
	fi

	if ! $IPT -S PREROUTING | grep mwan3_hook &> /dev/null; then
		$IPT -A PREROUTING -j mwan3_hook
	fi

	if ! $IPT -S OUTPUT | grep mwan3_hook &> /dev/null; then
		$IPT -A OUTPUT -j mwan3_hook
	fi

	$IPT -F mwan3_rules
}

mwan3_set_general_rules()
{
	if [ -z "$($IP rule list | awk '$1 == "2253:"')" ]; then
		$IP rule add pref 2253 fwmark 0xfd00/0xff00 blackhole
	fi

	if [ -z "$($IP rule list | awk '$1 == "2254:"')" ]; then
		$IP rule add pref 2254 fwmark 0xfe00/0xff00 unreachable
	fi
}

mwan3_set_connected_iptables()
{
	local connected_network

	if $IPT -S mwan3_connected &> /dev/null; then

		$IPS create mwan3_connected_temp hash:net

		for connected_network in $($IP route | awk '{print $1}' | egrep '[0-9]{1,3}(\.[0-9]{1,3}){3}'); do
			$IPS -! add mwan3_connected_temp $connected_network
		done

		for connected_network in $($IP route list table 0 | awk '{print $2}' | egrep '[0-9]{1,3}(\.[0-9]{1,3}){3}'); do
			$IPS -! add mwan3_connected_temp $connected_network
		done

		$IPS add mwan3_connected_temp 224.0.0.0/3
		$IPS swap mwan3_connected_temp mwan3_connected
		$IPS destroy mwan3_connected_temp

	fi
}

mwan3_set_iface_iptables()
{
	if ! $IPT -S mwan3_iface_$INTERFACE &> /dev/null; then
		$IPT -N mwan3_iface_$INTERFACE
	fi

	$IPT -F mwan3_iface_$INTERFACE
	$IPT -D mwan3_ifaces -m mark --mark 0x0/0xff00 -j mwan3_iface_$INTERFACE &> /dev/null

	if [ $ACTION == "ifup" ]; then
		$IPT -I mwan3_iface_$INTERFACE -i $DEVICE -m set --match-set mwan3_connected src -m mark --mark 0x0/0xff00 -m comment --comment "default" -j MARK --set-xmark 0xff00/0xff00
		$IPT -A mwan3_iface_$INTERFACE -i $DEVICE -m mark --mark 0x0/0xff00 -m comment --comment "$INTERFACE" -j MARK --set-xmark $(($iface_id*256))/0xff00
		$IPT -A mwan3_ifaces -m mark --mark 0x0/0xff00 -j mwan3_iface_$INTERFACE
	fi

	if [ $ACTION == "ifdown" ]; then
		$IPT -X mwan3_iface_$INTERFACE
	fi
}

mwan3_set_iface_route()
{
	$IP route flush table $iface_id
	[ $ACTION == "ifup" ] && $IP route add table $iface_id default $route_args
}

mwan3_set_iface_rules()
{
	while [ -n "$($IP rule list | awk '$1 == "'$(($iface_id+1000)):'"')" ]; do
		$IP rule del pref $(($iface_id+1000))
	done

	while [ -n "$($IP rule list | awk '$1 == "'$(($iface_id+2000)):'"')" ]; do
		$IP rule del pref $(($iface_id+2000))
	done

	[ $ACTION == "ifup" ] && $IP rule add pref $(($iface_id+1000)) iif $DEVICE lookup main
	[ $ACTION == "ifup" ] && $IP rule add pref $(($iface_id+2000)) fwmark $(($iface_id*256))/0xff00 lookup $iface_id
}

mwan3_set_iface_ipset()
{
	local setname entry

	for setname in $(ipset -n list | grep ^mwan3_sticky_); do
		for entry in $(ipset list $setname | grep "$(echo $(($iface_id*256)) | awk '{ printf "0x%08x", $1; }')" | cut -d ' ' -f 1); do
			$IPS del $setname $entry
		done
	done
}

mwan3_track()
{
	local track_ip track_ips reliability count timeout interval down up

	mwan3_list_track_ips()
	{
		track_ips="$1 $track_ips"
	}
	config_list_foreach $INTERFACE track_ip mwan3_list_track_ips

	if [ -e /var/run/mwan3track-$INTERFACE.pid ] ; then
		kill $(cat /var/run/mwan3track-$INTERFACE.pid) &> /dev/null
		rm /var/run/mwan3track-$INTERFACE.pid &> /dev/null
	fi

	if [ -n "$track_ips" ]; then
		config_get reliability $INTERFACE reliability 1
		config_get count $INTERFACE count 1
		config_get timeout $INTERFACE timeout 4
		config_get interval $INTERFACE interval 10
		config_get down $INTERFACE down 5
		config_get up $INTERFACE up 5

		$IPS -! create mwan3_track_$INTERFACE hash:ip
		$IPS create mwan3_track_temp_$INTERFACE hash:ip

		for track_ip in $track_ips; do
			$IPS -! add mwan3_track_temp_$INTERFACE $track_ip
		done

		$IPS swap mwan3_track_temp_$INTERFACE mwan3_track_$INTERFACE
		$IPS destroy mwan3_track_temp_$INTERFACE

		$IPT -D mwan3_track -p icmp -m set --match-set mwan3_track_$INTERFACE dst -m icmp --icmp-type 8 -m length --length 32 -j MARK --set-xmark 0xff00/0xff00 &> /dev/null
		$IPT -A mwan3_track -p icmp -m set --match-set mwan3_track_$INTERFACE dst -m icmp --icmp-type 8 -m length --length 32 -j MARK --set-xmark 0xff00/0xff00

		[ -x /usr/sbin/mwan3track ] && /usr/sbin/mwan3track $INTERFACE $DEVICE $reliability $count $timeout $interval $down $up $track_ips &
	else
		$IPT -D mwan3_track -p icmp -m set --match-set mwan3_track_$INTERFACE dst -m icmp --icmp-type 8 -m length --length 32 -j MARK --set-xmark 0xff00/0xff00 &> /dev/null
		$IPS destroy mwan3_track_$INTERFACE
	fi
}

mwan3_set_policy()
{
	local iface_count iface_id INTERFACE metric probability weight

	config_get INTERFACE $1 interface
	config_get metric $1 metric 1
	config_get weight $1 weight 1

	[ -n "$INTERFACE" ] || return 0

	config_foreach mwan3_get_iface_id interface

	[ -n "$iface_id" ] || return 0

	if $IPT -S mwan3_iface_$INTERFACE &> /dev/null; then
		if [ "$metric" -lt "$lowest_metric" ]; then

			total_weight=$weight
			$IPT -F mwan3_policy_$policy
			$IPT -A mwan3_policy_$policy -m mark --mark 0x0/0xff00 -m comment --comment "$INTERFACE $weight $weight" -j MARK --set-xmark $(($iface_id*256))/0xff00

			lowest_metric=$metric

		elif [ "$metric" -eq "$lowest_metric" ]; then

			total_weight=$(($total_weight+$weight))
			probability=$(($weight*1000/$total_weight))

			if [ "$probability" -lt 10 ]; then
				probability="0.00$probability"
			elif [ $probability -lt 100 ]; then
				probability="0.0$probability"
			elif [ $probability -lt 1000 ]; then
				probability="0.$probability"
			else
				probability="1"
			fi

			probability="-m statistic --mode random --probability $probability"

			$IPT -I mwan3_policy_$policy -m mark --mark 0x0/0xff00 $probability -m comment --comment "$INTERFACE $weight $total_weight" -j MARK --set-xmark $(($iface_id*256))/0xff00
		fi
	fi
}

mwan3_set_policies_iptables()
{
	local last_resort lowest_metric policy total_weight

	policy=$1

	config_get last_resort $1 last_resort unreachable

	if [ "$policy" != $(echo "$policy" | cut -c1-15) ]; then
		$LOG warn "Policy $policy exceeds max of 15 chars. Not setting policy" && return 0
	fi

	if ! $IPT -S mwan3_policy_$policy &> /dev/null; then
		$IPT -N mwan3_policy_$policy
	fi

	$IPT -F mwan3_policy_$policy

	case "$last_resort" in
		blackhole)
			$IPT -A mwan3_policy_$policy -m mark --mark 0x0/0xff00 -m comment --comment "blackhole" -j MARK --set-xmark 0xfd00/0xff00
		;;
		default)
			$IPT -A mwan3_policy_$policy -m mark --mark 0x0/0xff00 -m comment --comment "default" -j MARK --set-xmark 0xff00/0xff00
		;;
		*)
			$IPT -A mwan3_policy_$policy -m mark --mark 0x0/0xff00 -m comment --comment "unreachable" -j MARK --set-xmark 0xfe00/0xff00
		;;
	esac

	lowest_metric=256
	total_weight=0

	config_list_foreach $policy use_member mwan3_set_policy
}

mwan3_set_sticky_iptables()
{
	local INTERFACE iface_count iface_id

	INTERFACE="$1"

	config_foreach mwan3_get_iface_id interface
	unset iface_count

	$IPS -! create mwan3_sticky_$rule hash:ip,mark markmask 0xff00 timeout $timeout

	if [ -n "$iface_id" ]; then
		if [ -n "$($IPT -S mwan3_iface_$1 2> /dev/null)" ]; then
			$IPT -I mwan3_rule_$rule -m set ! --match-set mwan3_sticky_$rule src,src -j MARK --set-xmark 0x0/0xff00
			$IPT -I mwan3_rule_$rule -m mark --mark 0/0xff00 -j MARK --set-xmark $(($iface_id*256))/0xff00
		fi
	fi

	unset iface_id
}

mwan3_set_user_rules_iptables()
{
	local ipset proto src_ip src_port sticky dest_ip dest_port use_policy rule timeout

	config_get sticky $1 sticky 0
	config_get timeout $1 timeout 600
	config_get ipset $1 ipset
	config_get proto $1 proto all
	config_get src_ip $1 src_ip 0.0.0.0/0
	config_get src_port $1 src_port 0:65535
	config_get dest_ip $1 dest_ip 0.0.0.0/0
	config_get dest_port $1 dest_port 0:65535
	config_get use_policy $1 use_policy

	rule="$1"

	if [ "$rule" != $(echo "$rule" | cut -c1-15) ]; then
		$LOG warn "Rule $rule exceeds max of 15 chars. Not setting rule" && return 0
	fi

	if [ -n "$ipset" ]; then
		if [ -z "$($IPS -n list $ipset)" ]; then
			$IPS create $ipset hash:ip timeout 3600
		fi

		ipset="-m set --match-set $ipset dst"
	fi

	if [ -n "$use_policy" ]; then
		if [ "$use_policy" == "default" ]; then
			use_policy="MARK --set-xmark 0xff00/0xff00"
		elif [ "$use_policy" == "unreachable" ]; then
			use_policy="MARK --set-xmark 0xfe00/0xff00"
		elif [ "$use_policy" == "blackhole" ]; then
			use_policy="MARK --set-xmark 0xfd00/0xff00"
		else
			if [ "$sticky" -eq 1 ]; then

				if ! $IPT -S mwan3_rule_$rule &> /dev/null; then
					$IPT -N mwan3_rule_$rule
				fi

				$IPT -F mwan3_rule_$rule

				config_foreach mwan3_set_sticky_iptables interface

				$IPT -A mwan3_rule_$rule -m mark --mark 0/0xff00 -j mwan3_policy_$use_policy
				$IPT -A mwan3_rule_$rule -m mark ! --mark 0xfc00/0xfc00 -j SET --del-set mwan3_sticky_$rule src,src
				$IPT -A mwan3_rule_$rule -m mark ! --mark 0xfc00/0xfc00 -j SET --add-set mwan3_sticky_$rule src,src

				use_policy="mwan3_rule_$rule"
			else
				use_policy="mwan3_policy_$use_policy"
			fi
		fi

		case $proto in
			tcp|udp)
			$IPT -A mwan3_rules -p $proto -s $src_ip -d $dest_ip $ipset -m multiport --sports $src_port -m multiport --dports $dest_port -m mark --mark 0/0xff00 -m comment --comment "$1" -j $use_policy &> /dev/null
			;;
			*)
			$IPT -A mwan3_rules -p $proto -s $src_ip -d $dest_ip $ipset -m mark --mark 0/0xff00 -m comment --comment "$1" -j $use_policy &> /dev/null
			;;
		esac
	fi
}

mwan3_ifupdown()
{
	local counter enabled iface_count iface_id route_args wan_metric

	config_load mwan3
	config_foreach mwan3_get_iface_id interface

	[ -n "$iface_id" ] || return 0
	[ "$iface_count" -le 250 ] || return 0
	unset iface_count

	config_get enabled $INTERFACE enabled 0

	counter=0

	if [ $ACTION == "ifup" ]; then
		[ "$enabled" -eq 1 ] || return 0

		while [ -z "$($IP route list dev $DEVICE default | head -1)" -a "$counter" -lt 10 ]; do
			sleep 1
			let counter++
			if [ "$counter" -ge 10 ]; then
				$LOG warn "Could not find gateway for interface $INTERFACE ($DEVICE)" && return 0
			fi
		done

		route_args=$($IP route list dev $DEVICE default | head -1 | sed '/.*via \([^ ]*\) .*$/!d;s//via \1/;q' | egrep '[0-9]{1,3}(\.[0-9]{1,3}){3}')
		route_args="$route_args dev $DEVICE"
	fi

	while [ "$(pgrep -f -o hotplug-call)" -ne $$ -a "$counter" -lt 60 ]; do
		sleep 1
		let counter++
		if [ "$counter" -ge 60 ]; then
			$LOG warn "Timeout waiting for older hotplug processes to finish. $ACTION interface $INTERFACE (${DEVICE:-unknown}) aborted" && return 0
		fi
	done

	$LOG notice "$ACTION interface $INTERFACE (${DEVICE:-unknown})"

	mwan3_set_general_iptables
	mwan3_set_general_rules
	mwan3_set_iface_iptables
	mwan3_set_iface_route
	mwan3_set_iface_rules

	[ $ACTION == "ifdown" ] && mwan3_set_iface_ipset
	[ $ACTION == "ifup" ] && mwan3_track

	config_foreach mwan3_set_policies_iptables policy
	config_foreach mwan3_set_user_rules_iptables rule
}

[ -n "$ACTION" ] || exit 0
[ -n "$INTERFACE" ] || exit 0

if [ $ACTION == "ifup" ]; then
	[ -n "$DEVICE" ] || exit 0
fi

[ -x /usr/sbin/ip ] || exit 1
[ -x /usr/sbin/ipset ] || exit 1
[ -x /usr/sbin/iptables ] || exit 1
[ -x /usr/bin/logger ] || exit 1

local IP IPS IPT LOG

IP="/usr/sbin/ip -4"
IPS="/usr/sbin/ipset"
IPT="/usr/sbin/iptables -t mangle -w"
LOG="/usr/bin/logger -t mwan3 -p"

case "$ACTION" in
	ifup|ifdown)
		mwan3_ifupdown
		mwan3_set_connected_iptables
	;;
esac

exit 0