#!/bin/bash
# 
# Parses DHCP options from openvpn to update resolv.conf
# To use set as 'up' and 'down' script in your openvpn *.conf:
# up /etc/openvpn/update-resolv-conf
# down /etc/openvpn/update-resolv-conf
#
# Used snippets of resolvconf script by Thomas Hood and Chris Hanson.
# Licensed under the GNU GPL.  See /usr/share/common-licenses/GPL. 
# 
# Example envs set from openvpn:
#
#     foreign_option_1='dhcp-option DNS 193.43.27.132'
#     foreign_option_2='dhcp-option DNS 193.43.27.133'
#     foreign_option_3='dhcp-option DOMAIN be.bnc.ch'
#

[ -x /sbin/resolvconf ] || exit 0
[ "$script_type" ] || exit 0
[ "$dev" ] || exit 0

resolvconf_iface_prefix() {
	[[ -f /etc/resolvconf/interface-order ]] || return 0
	local iface
	while read -r iface; do
		[[ $iface =~ ^([A-Za-z0-9-]+)\*$ ]] || continue
		echo "${BASH_REMATCH[1]}." && return 0
	done < /etc/resolvconf/interface-order
}

split_into_parts()
{
	part1="$1"
	part2="$2"
	part3="$3"
}


SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
DNS_LEAK_SCRIPT=$SCRIPT_DIR/dns-leak-protect

case "$script_type" in
  up)
	NMSRVRS=""
	SRCHS=""
	for optionvarname in ${!foreign_option_*} ; do
		option="${!optionvarname}"
		echo "$option"
		split_into_parts $option
		if [ "$part1" = "dhcp-option" ] ; then
			if [ "$part2" = "DNS" ] ; then
				NMSRVRS="${NMSRVRS:+$NMSRVRS }$part3"
			elif [ "$part2" = "DOMAIN" ] ; then
				SRCHS="${SRCHS:+$SRCHS }$part3"
			fi
		fi
	done
	R=""
	[ "$SRCHS" ] && R="search $SRCHS
"
	for NS in $NMSRVRS ; do
        	R="${R}nameserver $NS
"
	done

	if [[ -z "${is_wireguard}" ]]; then
		echo -n "$R" | /sbin/resolvconf -a "${dev}.openvpn"
	else
		echo -n "$R" | /sbin/resolvconf -a "$(resolvconf_iface_prefix)${dev}" -m 0 -x
	fi

  "$DNS_LEAK_SCRIPT" "up" ${dev}

	;;
  down)
	if [[ -z "${is_wireguard}" ]]; then
  		/sbin/resolvconf -d "${dev}.openvpn"
	else
  		/sbin/resolvconf -d "$(resolvconf_iface_prefix)${dev}" -f
	fi

	"$DNS_LEAK_SCRIPT" "down"

	;;
esac


