#!/bin/sh
# vpn switch for travelmate
# Copyright (c) 2020-2021 Dirk Brenken (dev@brenken.org)
# This is free software, licensed under the GNU General Public License v3.

# set (s)hellcheck exceptions
# shellcheck disable=1091,3040,3043

# Please note: you have to setup the package 'wireguard' or 'openvpn' before using this script

export LC_ALL=C
export PATH="/usr/sbin:/usr/bin:/sbin:/bin"
set -o pipefail

# source function library if necessary
#
if [ -z "${_C}" ]; then
	. "/lib/functions.sh"
fi

vpn="${1}"
vpn_action="${2}"
vpn_service="${3}"
vpn_iface="${4}"
trm_maxwait="$(uci_get travelmate global trm_maxwait "30")"
trm_captiveurl="$(uci_get travelmate global trm_captiveurl "http://detectportal.firefox.com")"
trm_useragent="$(uci_get travelmate global trm_useragent "Mozilla/5.0 (Linux x86_64; rv:90.0) Gecko/20100101 Firefox/90.0")"
trm_logger="$(command -v logger)"
trm_fetch="$(command -v curl)"

f_net() {
	local json_rc result="net nok"

	json_rc="$(${trm_fetch} --user-agent "${trm_useragent}" --referer "http://www.example.com" --connect-timeout $((trm_maxwait / 10)) --header "Cache-Control: no-cache, no-store, must-revalidate" --header "Pragma: no-cache" --header "Expires: 0" --write-out "%{response_code}" --silent --output /dev/null "${trm_captiveurl}")"
	if [ "${json_rc}" = "200" ] || [ "${json_rc}" = "204" ]; then
		result="net ok"
	fi
	printf "%s" "${result}"
}

vpn_status="$(ubus -S call network.interface."${vpn_iface}" status 2>/dev/null | jsonfilter -q -l1 -e '@.up')"
case "${vpn_service}" in
	"wireguard")
		if [ "${vpn_action}" = "enable" ] && [ "${vpn_status:-"false"}" != "true" ]; then
			ubus call network.interface."${vpn_iface}" up
		fi
		if { [ "${vpn}" = "0" ] && [ "${vpn_action}" = "enable" ]; } || { [ "${vpn_action}" = "disable" ] && [ "${vpn_status}" = "true" ]; }; then
			ubus call network.interface."${vpn_iface}" down
			"${trm_logger}" -p "info" -t "trm-vpn  [${$}]" "${vpn_service} client connection disabled" 2>/dev/null
		fi
		;;
	"openvpn")
		if [ "${vpn_action}" = "enable" ] && [ "${vpn_status:-"false"}" != "true" ]; then
			ubus call network.interface."${vpn_iface}" up
			/etc/init.d/openvpn restart >/dev/null 2>&1
		fi
		if { [ "${vpn}" = "0" ] && [ "${vpn_action}" = "enable" ]; } || { [ "${vpn_action}" = "disable" ] && [ "${vpn_status}" = "true" ]; }; then
			ubus call network.interface."${vpn_iface}" down
			/etc/init.d/openvpn stop >/dev/null 2>&1
			"${trm_logger}" -p "info" -t "trm-vpn  [${$}]" "${vpn_service} client connection disabled" 2>/dev/null
		fi
		;;
esac

if [ "${vpn}" = "1" ] && [ "${vpn_action}" = "enable" ] && [ "${vpn_status:-"false"}" != "true" ]; then
	cnt=0
	while true; do
		vpn_status="$(ubus -S call network.interface."${vpn_iface}" status 2>/dev/null | jsonfilter -q -l1 -e '@.up')"
		if [ "${vpn_status}" = "true" ]; then
			net_status="$(f_net)"
			if [ "${net_status}" = "net ok" ]; then
				"${trm_logger}" -p "info" -t "trm-vpn  [${$}]" "${vpn_service} client connection enabled" 2>/dev/null
				break
			fi
		fi
		if [ "${cnt}" -ge "$((trm_maxwait / 6))" ]; then
			"${trm_logger}" -p "info" -t "trm-vpn  [${$}]" "${vpn_service} client connection can't be established" 2>/dev/null
			ubus call network.interface."${vpn_iface}" down
			exit 1
		fi
		sleep 1
		cnt="$((cnt + 1))"
	done
fi
if [ "${vpn_action}" = "enable" ] && [ "${vpn_status}" = "true" ]; then
	if [ -f "/etc/init.d/sysntpd" ]; then
		/etc/init.d/sysntpd restart >/dev/null 2>&1
	fi
fi