#!/bin/bash

# -------------------------------------------------------------------------- #
# Copyright 2010-2014, C12G Labs S.L.                                        #
#                                                                            #
# 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.                                             #
#--------------------------------------------------------------------------- #

# Gets IP address from a given MAC
mac2ip() {
    mac=$1

    let ip_a=0x`echo $mac | cut -d: -f 3`
    let ip_b=0x`echo $mac | cut -d: -f 4`
    let ip_c=0x`echo $mac | cut -d: -f 5`
    let ip_d=0x`echo $mac | cut -d: -f 6`

    ip="$ip_a.$ip_b.$ip_c.$ip_d"

    echo $ip
}

# Gets the network part of an IP
get_network() {
    network=$(get_iface_var "NETWORK")

    if [ -z "$network" ]; then
        network="$(echo $IP | cut -d'.' -f1,2,3).0"
    fi

    echo $network
}

# Gets the network mask
get_mask() {
    mask=$(get_iface_var "MASK")

    if [ -z "$mask" ]; then
        mask="255.255.255.0"
    fi

    echo $mask
}

# Gets device MTU
get_mtu() {
    mtu=$(get_iface_var "MTU")

    echo $mtu
}

is_gateway() {
    if [ -z "$GATEWAY_IFACE_NUM" ]; then
        true
    else
        [ "$IFACE_NUM" = "$GATEWAY_IFACE_NUM" ]
    fi
}

# Gets the network gateway
get_gateway() {
    if is_gateway; then
        gateway=$(get_iface_var "GATEWAY")

        if [ -z "$gateway" ]; then
            if [ "$DEV" = "eth0" ]; then
                net_prefix=$(echo $NETWORK | cut -d'.' -f1,2,3)
                gateway="${net_prefix}.1"
            fi
        fi

        echo $gateway
    fi
}

# Gets the network gateway6
get_gateway6() {
    if is_gateway; then
        get_iface_var "GATEWAY6"
    fi
}

get_ip() {
    ip=$(get_iface_var "IP")

    if [ -z "$ip" ]; then
        ip=$(mac2ip $MAC)
    fi

    echo $ip
}

get_iface_var() {
    var_name="${UPCASE_DEV}_$1"
    var=$(eval "echo \"\${$var_name}\"")

    echo $var
}

gen_iface_conf() {
    cat <<EOT
iface $DEV inet static
  address $IP
  network $NETWORK
  netmask $MASK
EOT

    if [ -n "$MTU" ]; then
        echo "  mtu $MTU"
    fi

    if [ -n "$GATEWAY" ]; then
        echo "  gateway $GATEWAY"
    fi

    echo ""
}

gen_iface6_conf() {
    cat <<EOT
iface $DEV inet6 static
  address $IPV6
  netmask 64
EOT

    if [ -n "$MTU" ]; then
        echo "  mtu $MTU"
    fi

    if [ -n "$GATEWAY6" ]; then
        echo "  gateway $GATEWAY6"
    fi

    echo ""
}

get_interface_mac()
{
    ip link show | awk '/^[0-9]+: [A-Za-z0-9]+:/ { device=$2; gsub(/:/, "",device)} /link\/ether/ { print device " " $2 }'
}

get_context_interfaces()
{
    env | grep -E "^ETH[0-9]+_MAC=" | sed 's/_.*$//' | sort
}

get_dev()
{
    list="$1"
    mac="$2"

    echo "$list" | grep "$mac" | cut -d' ' -f1 | tail -n1
}

gen_network_configuration()
{
    cat <<EOT
auto lo
iface lo inet loopback

EOT

    INTERFACE_MAC=$(get_interface_mac)
    CONTEXT_INTERFACES=$(get_context_interfaces)
    GATEWAY_IFACE_NUM=$(echo "$GATEWAY_IFACE" | sed 's/^ETH//')

    for interface in $CONTEXT_INTERFACES; do
        UPCASE_DEV=$interface
        MAC=$(get_iface_var "MAC")
        DEV=$(get_dev "$INTERFACE_MAC" "$MAC")
        IFACE_NUM=$(echo "$UPCASE_DEV" | sed 's/^ETH//')

        IP=$(get_ip)
        NETWORK=$(get_network)
        MASK=$(get_mask)
        MTU=$(get_mtu)
        GATEWAY=$(get_gateway)

        IPV6=$(get_iface_var "IPV6")
        [[ -z $IPV6 ]] && IPV6=$(get_iface_var "IP6")
        GATEWAY6=$(get_gateway6)
        CONTEXT_FORCE_IPV4=$(get_iface_var "CONTEXT_FORCE_IPV4")

        echo "auto $DEV"

        [[ -z $IPV6 || -n $CONTEXT_FORCE_IPV4 ]] && gen_iface_conf
        [[ -n $IPV6 ]] && gen_iface6_conf

    done
}

configure_network()
{
    gen_network_configuration > /etc/network/interfaces
    echo "source /etc/network/interfaces.d/*.cfg" >> /etc/network/interfaces
}

deactivate_network()
{
    . /etc/os-release
    if [ $ID = "ubuntu" ]; then
        IFACES=`/sbin/ifquery -la`

        for i in $IFACES; do
            if [ $i != 'lo' ]; then
                /sbin/ifdown $i
                /sbin/ip addr flush dev $i
            fi
        done
    else
        service networking stop
    fi
}

activate_network()
{
    . /etc/os-release
    if [ $ID = "ubuntu" ]; then
        IFACES=`/sbin/ifquery -la`

        for i in $IFACES; do
            /sbin/ifup $i
        done
    else
        service networking stop
        sleep 1
        service networking start
    fi

    sleep 2
}

deactivate_network
configure_network
activate_network