#!/bin/bash

# -------------------------------------------------------------------------- #
# Copyright 2010-2016, OpenNebula Systems                                    #
#                                                                            #
# Licensed under the Apache License, Version 2.0 (the "License"); you may    #
# not use this file except in compliance with the License. You may obtain    #
# a copy of the License at                                                   #
#                                                                            #
# http://www.apache.org/licenses/LICENSE-2.0                                 #
#                                                                            #
# Unless required by applicable law or agreed to in writing, software        #
# distributed under the License is distributed on an "AS IS" BASIS,          #
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   #
# See the License for the specific language governing permissions and        #
# limitations under the License.                                             #
#--------------------------------------------------------------------------- #

export DNS_VARIABLES="DNS $(env | sed 's/=.*$//' | grep -E '^ETH[0-9]+_DNS$' | sort)"

export SEARCH_VARIABLES="SEARCH_DOMAIN $(env | sed 's/=.*$//' | grep -E '^ETH[0-9]+_SEARCH_DOMAIN$' | sort)"

nameservers=$(
    for var in ${DNS_VARIABLES}; do
        value=$(eval "echo \"\${$var}\"")
        if [ -n "$value" ]; then
            echo "$value"
        fi
    done
)

searchdomains=$(
    for var in ${SEARCH_VARIABLES}; do
        value=$(eval "echo \"\${$var}\"")
        if [ -n "$value" ]; then
            echo "$value"
        fi
    done
)

[ -z "$nameservers" ] && exit 0

echo -n '' > /etc/resolv.conf

for nameserver in $nameservers; do
    echo nameserver $nameserver >> /etc/resolv.conf
done

[ -z "$searchdomains" ] && exit 0

echo search $searchdomains >> /etc/resolv.conf