#!/bin/bash

# Thierry Parmentelat <thierry.parmentelat@inria.fr>
# Copyright (C) 2010 INRIA
#
# 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
#

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

# turn on verbosity
set -x

# constant
INTERFACE_BRIDGE=br0

#################### compute INTERFACE_LAN
# use /proc/net/dev instead of a hard-wired list
function gather_interfaces () {
    python <<EOF
for line in file("/proc/net/dev"):
    if ':' not in line: continue
    ifname=line.replace(" ","").split(":")[0]
    if ifname.find("lo")==0: continue
    if ifname.find("br")==0: continue
    if ifname.find("virbr")==0: continue
    if ifname.find("tap")==0: continue
    print ifname
EOF
}

function discover_interface () {
    for ifname in $(gather_interfaces); do
	ip link show $ifname | grep -qi 'state UP' && { echo $ifname; return; }
    done
    # still not found ? that's bad
    echo unknown
}
INTERFACE_LAN=$(discover_interface)
echo Using physical interface $INTERFACE_LAN

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

    echo "========== $COMMAND: entering start - beg"
    hostname
    uname -a
    ip address show
    ip route show
    echo "========== $COMMAND: entering start - end"

    # disable netfilter calls for bridge interface (they cause panick on 2.6.35 anyway)
    #
    # another option would be to accept the all forward packages for
    # bridged interface like: -A FORWARD -m physdev --physdev-is-bridged -j ACCEPT
    sysctl net.bridge.bridge-nf-call-iptables=0
    sysctl net.bridge.bridge-nf-call-ip6tables=0
    sysctl net.bridge.bridge-nf-call-arptables=0

    # 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
    ip address show $INTERFACE_BRIDGE &> /dev/null && {
	echo "Bridge interface $INTERFACE_BRIDGE already set up - $COMMAND start exiting"
	exit 0
    }
    ip address show $INTERFACE_LAN &> /dev/null || {
	echo "Cannot use interface $INTERFACE_LAN - exiting"
	exit 1
    }

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

    broadcast=$(/sbin/ip address show $INTERFACE_LAN | grep -v inet6 | grep inet | head --lines=1 | awk '{print $4;}')
    [ -z "$broadcast" ] && echo "WARNING: Could not determine broadcast address for $INTERFACE_LAN"

    gateway=$(ip route show | grep default | awk '{print $3;}')
    [ -z "$gateway" ] && echo "WARNING: Could not determine gateway IP"

    ### do it
    #Restarting udev
    #echo "Starting udev ..."
    #/sbin/udevd restart
    #if modprobe kqemu &> /dev/null ; then
    #    echo "(bridge-init) kqemu loaded"
    #else
    #	echo "(bridge-init) WARNING : Could not modprobe kqemu"
    #fi
    #Loading 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=$INTERFACE_BRIDGE"
    brctl addbr $INTERFACE_BRIDGE
    #brctl stp $INTERFACE_BRIDGE yes
    brctl addif $INTERFACE_BRIDGE $INTERFACE_LAN
    echo "Activating promiscuous mode INTERFACE_LAN=$INTERFACE_LAN"
    ip link set dev $INTERFACE_LAN promisc on
    sleep 2
    echo "Setting bridge address=$address broadcast=$broadcast"
    # static
    ip address add $address broadcast $broadcast dev $INTERFACE_BRIDGE
    # turn on bridge interface
    ip link set dev $INTERFACE_BRIDGE up
    ip address del $address dev $INTERFACE_LAN
    sleep 1

    #Reconfigure the routing table
    echo "Adding default route via gateway=$gateway on dev $INTERFACE_LAN"
    ip route add 0.0.0.0/0 via $gateway dev $INTERFACE_BRIDGE

    echo "========== $COMMAND: exiting start - beg"
    ip address show
    ip route show
    echo "========== $COMMAND: exiting start - end"
}

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

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

    echo "========== $COMMAND: entering add - beg"
    ip address show
    ip route show
    echo "========== $COMMAND: entering add - end"

    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

    echo "========== $COMMAND: exiting add - beg"

    ip address show
    ip route show

    echo "Installed iptables"
    iptables-save

    echo "========== $COMMAND: exiting add - end"
}

#Stop the bridge and restore the original setting
function 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 ; }

    ip address show $INTERFACE_BRIDGE &> /dev/null || {
	echo "Bridge interface $INTERFACE_BRIDGE does not exist - $COMMAND stop exiting"
	exit 0
    }
    address=$(/sbin/ip address show $INTERFACE_BRIDGE | grep -v inet6 | grep inet | head --lines=1 | awk '{print $2;}')
    brctl delif $INTERFACE_BRIDGE $INTERFACE_LAN
    ip address del $address dev $INTERFACE_BRIDGE
    brctl delbr $INTERFACE_BRIDGE
    systemctl NetworkManager restart
}

function main () {

    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
}

# redirect stderr as well
main "$@" 2>&1