#!/bin/sh
# Get DNS, Domain Search via OpenVPN client hotplug script
# Written by Konstantine Shevlakov at <shevlakov@132lan.ru> 2022
# OpenWrt 21 file location: /etc/hotplug.d/openvpn


# Get NameServers and Domain search
get_ns(){
	DNS=$(env |  awk '/dhcp-option DNS/{gsub("'\''", "");print $NF}')
	DOMAIN=$(env |  awk '/dhcp-option DOMAIN/{gsub("'\''", "");print $NF}')
}

# Setting up NameServers and Domain
set_ns(){
	if [ "x$CFGIFACE" != "x" ]; then
		for ns in $DNS; do
			if [ "x$ns" != "x" ]; then
				uci -q add_list network.$CFGIFACE.dns=$ns
			fi
		done
		for dn in $DOMAIN; do
			if [ "x$dn" != "x" ]; then
				uci -q add_list network.$CFGIFACE.dns_search=$dn
			fi
		done
	fi
	uci -q commit network
}

# Delete NameServers and Domain
unset_ns(){
	if [ "x$CFGIFACE" != "x" ]; then
		uci -q delete network.$CFGIFACE.dns
		uci -q delete network.$CFGIFACE.dns_search
	fi
	uci -q commit network
}


# Get interface name in uci 
UCI_conf=$(uci show openvpn | awk -F [\/=] '/config/{gsub("'\''", "");print $NF}')
for cfg in $UCI_conf; do
	if [ $config = $cfg ]; then
		CFGIFACE=$(uci show network | awk -F [.] -v device=$dev '$0 ~ device {print $2}')
		PROTO=$(ifstatus $CFGIFACE | jsonfilter -e '@["proto"]')
		get_ns
	fi
done

# Hotplug action
case $PROTO in 
	none)
		# Check peerdns option in uci interface section
		PEERDNS=$(uci -q get network.$CFGIFACE.dns)
		case $ACTION in
			up)
				if [ "x${PEERDNS}" != "x" ]; then
					exit 0
				fi
				if  [ "$DNS" ]; then
					unset_ns
					set_ns
					reload_config
					logger -t "`basename $0`" "OpenVPN: adding DNS: $DNS from $INSTANCE" 
				fi
			;;
			down)
				unset_ns
				reload_config
				logger -t "`basename $0`" "OpenVPN: remove NS attributes from $INSTANCE"
			;;
		esac
	;;
esac