00-network

#!/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 the network gateway
get_gateway() {
    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
}

get_interfaces() {
    IFCMD="/sbin/ifconfig -a"

    $IFCMD | grep ^eth | sed 's/ *Link encap:Ethernet.*HWaddr /-/g'
}

get_dev() {
    echo $1 | cut -d'-' -f 1
}

get_mac() {
    echo $1 | cut -d'-' -f 2
}

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
}

upcase() {
    echo "$*" | tr '[:lower:]' '[:upper:]'
}

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

    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 "$GATEWAY6" ]; then
      echo "  gateway $GATEWAY6"
    fi

    echo ""
}

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

EOT

    IFACES=`get_interfaces`

    for i in $IFACES; do
        MAC=`get_mac $i`
        DEV=`get_dev $i`
        UPCASE_DEV=`upcase $DEV`

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

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

    service networking stop
    sleep 1
    service networking start

    sleep 2
}

configure_network