#!/bin/sh

. /usr/share/libubox/jshn.sh
. /usr/share/wginstaller/wg.sh

wg_key_exists () {
	local key=$1

	wg show | grep -q "$key"
}

wg_timeout () {
	local int=$1

	handshake=$(wg show "$int" latest-handshakes | awk '{print $2}')
	timeout=$(uci get wgserver.@server[0].timeout_handshake)

	if [ "$handshake" -ge "$timeout" ]; then
		echo "1"
	else
		echo "0"
	fi
}

wg_check_interface () {
	local int=$1
	if [ "$(wg_timeout "$int")" -eq "1" ]; then
		ip link del dev "$int"
	fi
}

wg_check_interfaces () {
	wg_interfaces=$(wg show interfaces)
	for interface in $wg_interfaces; do
		wg_check_interface "$interface"
	done
}

wg_get_usage () {
	num_interfaces=$(wg show interfaces | wc -w)
	json_init
	json_add_int "num_interfaces" "$num_interfaces"
	json_dump
}

wg_register () {
	local uplink_bw=$1
	local mtu=$2
	local public_key=$3

	if wg_key_exists $public_key; then
		logger -t "wginstaller" "Rejecting request since the public key is already used!" "$public_key"
		json_init
		json_add_int "response_code" 1
		json_dump
		return 1
	fi

	base_prefix_ipv6=$(uci get wgserver.@server[0].base_prefix_ipv6)
	port_start=$(uci get wgserver.@server[0].port_start)
	port_end=$(uci get wgserver.@server[0].port_end)

	port=$(next_port "$port_start" "$port_end")
	ifname="wg_$port"

	offset=$((port - port_start))
	gw_ipv6=$(owipcalc "$base_prefix_ipv6" add "$offset" next 128) # gateway ip
	gw_ipv6_assign="${gw_ipv6}/128"

	gw_key=$(uci get wgserver.@server[0].wg_key)
	gw_pub=$(uci get wgserver.@server[0].wg_pub)

	if [ "$(uci get wgserver.@server[0].wg_tmp_key)" -eq 1 ]; then
		[ -d "/tmp/run/wgserver" ] || mkdir -p /tmp/run/wgserver
		gw_key="/tmp/run/wgserver/${ifname}.key"
		gw_pub="/tmp/run/wgserver/${ifname}.pub"
		wg genkey | tee "$gw_key" | wg pubkey > "$gw_pub"
	else
		[ -d "$(dirname $gw_key)" ] || mkdir -p "$(dirname $gw_key)"
		[ -f "$gw_key" ] || wg genkey | tee "$gw_key" | wg pubkey > "$gw_pub"
	fi
	wg_server_pubkey=$(cat "$gw_pub")

	# create wg tunnel
	ip link add dev "$ifname" type wireguard
	wg set "$ifname" listen-port "$port" private-key "$gw_key" peer "$public_key" allowed-ips 0.0.0.0/0,::0/0
	ip -6 addr add "$gw_ipv6_assign" dev "$ifname"
	ip -6 addr add fe80::1/64 dev "$ifname"

	base_prefix_ipv4=$(uci get wgserver.@server[0].base_prefix_ipv4)
	if [ $? -eq 0 ]; then
		gw_ipv4=$(owipcalc "$base_prefix_ipv4" add "$offset" next 32) # gateway ip
		gw_ipv4_assign="${gw_ipv4}/32"
		ip addr add "$gw_ipv4_assign" broadcast 255.255.255.255 dev "$ifname"
	fi

	ip link set up dev "$ifname"
	ip link set mtu "$mtu" dev "$ifname"

	# craft return address
	json_init
	json_add_int "response_code" 0
	json_add_string "gw_pubkey" "$wg_server_pubkey"
	if test -n "${gw_ipv4_assign-}"; then
		json_add_string "gw_ipv4" "$gw_ipv4_assign"
	fi
	json_add_string "gw_ipv6" "$gw_ipv6_assign"
	json_add_int "gw_port" "$port"

	json_dump
}