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#!/bin/bash

# Copyright (C) 2010 ORSoC AB

# Copyright (C) 2010 Embecosm Limited

# Contributor Julius Baxter <julius.baxter@orsoc.se>

# Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

# This file is a superuser script to set up an Ethernet bridge that can be

# used with Or1ksim via the TUN/TAP interface.

# This program is free software; you can redistribute it and/or modify it

# under the terms of the GNU General Public License as published by the Free

# Software Foundation; either version 3 of the License, or (at your option)

# any later version.

# This program is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

# more details.

# You should have received a copy of the GNU General Public License along

# with this program.  If not, see <http://www.gnu.org/licenses/>.

# ------------------------------------------------------------------------------

# Pre-requisites: bridge-utils must be installed.

# Usage: ./brstart.sh <username> <groupname> <bridge> <eth> <tap>

# - <bridge> is the bridge interface to use, e.g. br0

# - <eth> is the hardware ethernet interface to use, e.g. eth0

# - <tap> is/are the persistent TAP interface(s)

# Check we have the right number of arguments

if [ "x$#" != "x5" ]

then

    echo "Usage: ./brstart.sh <username> <groupname> <bridge> <eth> <tap>"

    exit 1

fi

# Check we are root

euid=`id -un`

if [ "x${euid}" != "xroot" ]

then

    echo "Must run as root"

    exit 1

fi

# Break out the arguments

username=$1

groupname=$2

br=$3

eth=$4

tap=$5

# Determine the IP address, netmask and broadcast of the current Ethernet

# interface. This is used if the bridge is set up manually, rather than using

# DHCP.

eth_ip=`ifconfig $eth | \

        grep "inet addr" | \

        head -1 | \

        sed -e 's/^.*inet addr:\([^ \t]*\).*$/\1/'`

eth_netmask=`ifconfig $eth | \

        grep "Mask" | \

        head -1 | \

        sed -e 's/^.*Mask:\([^ \t]*\).*$/\1/'`

eth_broadcast=`ifconfig $eth | \

        grep "Bcast" | \

        head -1 | \

        sed -e 's/^.*Bcast:\([^ \t]*\).*$/\1/'`

# Create the TAP interface

openvpn --mktun --dev ${tap} --user ${username} --group ${groupname}

if [ $? != 0 ]

then

    echo "Failed to create ${tap}"

    exit 1

fi

# Create the bridge

brctl addbr ${br}

if [ $? != 0 ]

then

    echo "Failed to create ${br}"

    exit 1

fi

# Add the host Ethernet and TAP interfaces, removing the IP addresses of the

# underlying interfaces.

for i in ${eth} ${tap}

do

    # Add the interface

    brctl addif ${br} ${i}

    if [ $? != 0 ]

    then

        echo "Failed to create ${i}"

        exit 1

    fi

    # Remove the IP address

    ifconfig ${i} 0.0.0.0 promisc up

    if [ $? != 0 ]

    then

        echo "Failed to remove IP interface of ${i}"

        exit 1

    fi

done

# Reconfigure the bridge to have the appropriate Ethernet address. This uses

# dhclient to get the information from DHCP, but we could instead use

# ifconfig and the data about the original IP address, netmask and broadcast

# mask as follows:

#   ifconfig ${br} ${eth_ip} netmask ${eth_netmask} broadcast ${eth_broadcast}

dhclient ${br}

# Open up firewall to the tap and bridge. We have a generic reject at the end

# of the chain, so we insert these at the start.

iptables -I INPUT 1 -i ${tap} -j ACCEPT

iptables -I INPUT 1 -i ${br} -j ACCEPT

iptables -I FORWARD 1 -i ${br} -j ACCEPT