#!/bin/bash

# Establishment of a runtime environment for a
# virtual  machine  under QEMU, This script allows the host box
# to share its network connection with qemu-based guests
#
# Author: Amine chaoui
#

COMMAND=$(basename $0)
cd $(dirname $0)

# constant
INTERFACE_BRIDGE=br0
# Default Value
INTERFACE_LAN=eth0

# Fonction de mise en place du pont
start () {

    # take extra arg for ifname, if provided
    [ -n "$1" ] && { INTERFACE_LAN=$1; shift ; }

    ### Checking
    type -p brctl &> /dev/null || { echo "brctl not found, please install bridge-utils" ; exit 1 ; }

    #if we have already configured the same host_box no need to do it again
    /sbin/ifconfig $INTERFACE_BRIDGE &> /dev/null && {
	echo "Interface bridge $INTERFACE_BRIDGE already exist."
	exit 0
    }
    /sbin/ifconfig $INTERFACE_LAN &>/dev/null || {
	echo "Cannot use interface $INTERFACE_LAN - exiting"
	exit 1
    }

    #Getting host IP/masklen
    address=$(/sbin/ip addr show $INTERFACE_LAN | grep -v inet6 | grep inet | awk '{print $2;}')
    [ -z "$address" ] && { echo "ERROR: Could not determine IP address for $INTERFACE_LAN" ; exit 1 ; }
    
    broadcast=$(/sbin/ip addr show $INTERFACE_LAN | grep -v inet6 | grep inet | awk '{print $4;}')
    [ -z "$broadcast" ] && echo "WARNING: Could not determine broadcast address for $INTERFACE_LAN"

    gateway=$(netstat -rn | grep '^0.0.0.0' | awk '{print $2;}')
    [ -z "$gateway" ] && echo "WARNING: Could not determine gateway IP"

    ### do it
    #Restarting udev
    echo "Starting udev ..."
    /sbin/udevd restart
    if modprobe kqemu ; then
	echo "kqemu loadded"
    else
	echo "WARNING : Could not modprobe kqemu"
    fi
    #Loding the tun/tap model
    if modprobe tun ; then
	echo "tun loaded"
        # Giving read/write access
	echo "Granting read/write acces to the tun device"
	chmod 666 /dev/net/tun
    else
	echo "Could not modprobe tun - exiting"
	exit 1
    fi

    # creating the bridge
    echo "Creating bridge $INTERFACE_BRIDGE"
    brctl addbr $INTERFACE_BRIDGE
    #brctl stp $INTERFACE_BRIDGE yes
    brctl addif $INTERFACE_BRIDGE $INTERFACE_LAN
    echo "Activating promiscuous mode  $INTERFACE_LAN..."
    /sbin/ifconfig $INTERFACE_LAN 0.0.0.0 promisc up
    sleep 2
    echo "Setting bridge $address $broadcast"
    # static
    /sbin/ifconfig $INTERFACE_BRIDGE $address broadcast $broadcast up
    sleep 1
	
    #Reconfigure the routing table
    echo "Configuring  the IP  Gateway @:" $gateway
    route add default gw $gateway

}

#Adding a new interface to the bridge: this is used by qemu-ifup 
add () {

    [[ -z "$@" ]] && { echo "Usage: $COMMAND add ifname" ; exit 1 ; }
    INTERFACE_LAN=$1; shift

    echo "Activating link for $INTERFACE_LAN..."
    /sbin/ip link set $INTERFACE_LAN up
    sleep 1
    echo "Adding $INTERFACE_LAN to $INTERFACE_BRIDGE"
    brctl addif $INTERFACE_BRIDGE $INTERFACE_LAN

    # turn off filtering on this interface
    ########## from the test environment
    # expected vars are MACADDR, NODE_ISO, HOSTNAME, IP and TARGET_ARCH
    CONFIG=qemu.conf
    [ -f "$CONFIG" ] || { echo "Config file for qemu $CONFIG not found in $(pwd)" ; exit 1 ; }
    . $CONFIG

    echo "Tweaking iptables"
    iptables-save > iptables.pre
    # rewrite a new config - quick and dirty
    ./iptables.py iptables.pre iptables.post $IP
    iptables-restore < iptables.post
    
}

#Stop the bridge and restore the original setting
stop () {
    # take extra arg for ifname, if provided
    [ -n "$1" ] && { INTERFACE_LAN=$1; shift ; }

    ### Checking
    type -p brctl &> /dev/null || { echo "brctl not found, please install bridge-utils" ; exit 1 ; }

    /sbin/ifconfig $INTERFACE_BRIDGE &> /dev/null || {
	echo "Interface bridge $INTERFACE_BRIDGE does not exist."
	exit 0
    }
    brctl delif $INTERFACE_BRIDGE $INTERFACE_LAN
    /sbin/ifconfig $INTERFACE_BRIDGE down
    brctl delbr $INTERFACE_BRIDGE
    /sbin/service network restart
    /sbin/service iptables restart
}

# 
case "$1" in
    start)
	shift; start "$@" ;;
    stop)
	shift; stop "$@" ;;
    add)
        shift; add "$@" ;;
    *)
        echo $"Usage: env-qemu {start|add|stop} [interface]" ; exit 1 ;;
esac

exit 0