Script which helps to configure resolv.conf based on information pushed by the OpenVPN server.

resolv_conf.sh

#!/bin/bash

###
#
# Description
# -----------
#
# Script which helps to configure resolv.conf based on information pushed by
# the OpenVPN server.
#
# Usage
# -----
#
# Put this file into /etc/openvpn/resolv_conf.sh and configure the client to
# use it by adding the following into the config file:
#
# script-security 2
# up /etc/openvpn/resolv_conf.sh
# down /etc/openvpn/resolv_conf.sh
#
# Requirements
# ------------
#
# Bash v4.0+
#
###


PATH='/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin'


function up() {
    echo 'Running resolv.conf UP script...' >&2

    domain=''
    search=''
    nameserver=''

    for opt in ${!foreign_option_*} ; do
        opt="${!opt}"

        if [[ ${opt:0:12} == 'dhcp-option ' ]]; then
            opt="${opt:12}"
            key="${opt%% *}"
            val="${opt#* }"

            if [[ $key == 'DNS' ]]; then
                nameserver+="nameserver $val\n"
            elif [[ $key == 'DOMAIN' ]]; then
                if [[ -z $search ]]; then
                    search='search'
                fi

                search+=" $val"
            elif [[ $key == 'ADAPTER_DOMAIN_SUFFIX' ]]; then
                domain="domain $val\n"
            fi
        fi
    done

    if [ -n "$domain$nameserver$search" ]; then
        if [ -e /etc/resolv.conf ]; then
            cp /etc/resolv.conf{,.ovpnsave}
        fi

        echo -e "$domain$nameserver$search" > /etc/resolv.conf
    fi
}


function down() {
    echo 'Running resolv.conf DOWN script...' >&2

    if [ -e /etc/resolv.conf.ovpnsave ]; then
        cp /etc/resolv.conf{.ovpnsave,}
        rm -f /etc/resolv.conf.ovpnsave
    fi
}


function main() {
    if [[ $script_type == 'up' ]]; then
        up
    elif [[ $script_type == 'down' ]]; then
        down
    fi
}


main