#!/bin/sh

set -e

action_enable() {
	if [ ! -e /etc/resolv.conf.default ] && ! grep -q 'nameserver[[:space:]]\+127\.0\.0\.253' /etc/resolv.conf; then
		cp -a -f /etc/resolv.conf /etc/resolv.conf.default
	fi
	{
		echo "nameserver 127.0.0.253"
		echo "options edns0 trust-ad"
	} > /etc/resolv.conf.new
	mv -f -T /etc/resolv.conf.new /etc/resolv.conf
}

action_disable() {
	if [ -e /etc/resolv.conf.default ]; then
		mv -f -T /etc/resolv.conf.default /etc/resolv.conf
	fi
}

case "$1" in
	enable)	action_enable ;;
	disable) action_disable ;;
	*)
		echo "Usage:"
		echo "	$0 enable"
		echo "	$0 disable"
esac