Laboratoire de l'Informatique et du Parallélisme » CIAB

#!/bin/bash

#============================================================================

# Based on the default Xen network start/stop script.

# Xend calls a network script when it starts.

# The script name to use is defined in ${XEN_CONFIG_DIR}/xend-config.sxp

# in the network-script field.

#

# Below, this is what the default script does:

# This script creates a bridge (default ${netdev}), adds a device

# (defaults to the device on the default gateway route) to it, copies

# the IP addresses from the device to the bridge and adjusts the routes

# accordingly.

#

# If all goes well, this should ensure that networking stays up.

# However, some configurations are upset by this, especially

# NFS roots. If the bridged setup does not meet your needs,

# configure a different script, for example using routing instead.

#

# What we add to create an internal bridge called "internal" is:

# just add a line in the op_start (to create) and in the op_stop

# to (delete) the internal bridge.

#

# Usage:

#

# network-bridge (start|stop|status) {VAR=VAL}*

#

# Vars:

#

# bridge     The bridge to use (default ${netdev}).

# netdev     The interface to add to the bridge (default gateway device).

# antispoof  Whether to use iptables to prevent spoofing (default no).

#

# Internal Vars:

# pdev="p${netdev}"

# tdev=tmpbridge

#

# start:

# Creates the bridge as tdev

# Copies the IP and MAC addresses from pdev to bridge

# Renames netdev to be pdev 

# Renames tdev to bridge

# Enslaves pdev to bridge

#

# stop:

# Removes pdev from the bridge

# Transfers addresses, routes from bridge to pdev

# Renames bridge to tdev

# Renames pdev to netdev 

# Deletes tdev

#

# status:

# Print addresses, interfaces, routes

#

#============================================================================

dir=$(dirname "$0")

. "$dir/logging.sh"

. "$dir/xen-script-common.sh"

. "$dir/xen-network-common.sh"

. "$dir/locking.sh"

findCommand "$@"

evalVariables "$@"

is_network_root () {

    local rootfs=$(awk '{ if ($1 !~ /^[ \t]*#/ && $2 == "/") { print $3; }}' /etc/mtab)

    local rootopts=$(awk '{ if ($1 !~ /^[ \t]*#/ && $2 == "/") { print $4; }}' /etc/mtab)

    [[ "$rootfs" =~ "^nfs" ]] || [[ "$rootopts" =~ "_netdev" ]] && has_nfsroot=1 || has_nfsroot=0

    if [ $has_nfsroot -eq 1 ]; then

        local bparms=$(cat /proc/cmdline)

        for p in $bparms; do

            local ipaddr=$(echo $p | awk /nfsroot=/'{ print substr($1,9,index($1,":")-9) }')

            if [ "$ipaddr" != "" ]; then

                local nfsdev=$(ip route get $ipaddr | awk /$ipaddr/'{ print $3 }')

                [[ "$nfsdev" == "$netdev" ]] && return 0 || return 1

            fi

        done

    fi

    return 1

}

find_alt_device () {

    local interf=$1

    local prefix=${interf%[[:digit:]]}

    local ifs=$(ip link show | grep " $prefix" |\

                gawk '{ printf ("%s",substr($2,1,length($2)-1)) }' |\

                sed s/$interf//)

    echo "$ifs"

}

netdev=${netdev:-$(ip route list 0.0.0.0/0  | \

                   sed 's/.*dev \([a-z]\+[0-9]\+\).*$/\1/')}

if is_network_root ; then

    altdevs=$(find_alt_device $netdev)

    for netdev in $altdevs; do break; done

    if [ -z "$netdev" ]; then

        [ -x /usr/bin/logger ] && /usr/bin/logger "network-bridge: bridging not supported on network root; not starting"

        exit

    fi

fi

netdev=${netdev:-eth0}

bridge=${bridge:-${netdev}}

antispoof=${antispoof:-no}

pdev="p${netdev}"

tdev=tmpbridge

get_ip_info() {

    addr_pfx=`ip addr show dev $1 | egrep '^ *inet' | sed -e 's/ *inet //' -e 's/ .*//'`

    gateway=`ip route show dev $1 | fgrep default | sed 's/default via //'`

}

do_ifup() {

    if [ $1 != "${netdev}" ] || ! ifup $1 ; then

        if [ -n "$addr_pfx" ] ; then

            # use the info from get_ip_info()

            ip addr flush $1

            ip addr add ${addr_pfx} dev $1

        fi

        ip link set dev $1 up

        [ -n "$gateway" ] && ip route add default via ${gateway}

    fi

}

# Usage: transfer_addrs src dst

# Copy all IP addresses (including aliases) from device $src to device $dst.

transfer_addrs () {

    local src=$1

    local dst=$2

    # Don't bother if $dst already has IP addresses.

    if ip addr show dev ${dst} | egrep -q '^ *inet ' ; then

        return

    fi

    # Address lines start with 'inet' and have the device in them.

    # Replace 'inet' with 'ip addr add' and change the device name $src

    # to 'dev $src'.

    ip addr show dev ${src} | egrep '^ *inet ' | sed -e "

s/inet/ip addr add/

s@\([0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+/[0-9]\+\)@\1@

s/${src}/dev ${dst} label ${dst}/

s/secondary//

" | sh -e

    # Remove automatic routes on destination device

    ip route list | sed -ne "

/dev ${dst}\( \|$\)/ {

  s/^/ip route del /

  p

}" | sh -e

}

# Usage: transfer_routes src dst

# Get all IP routes to device $src, delete them, and

# add the same routes to device $dst.

# The original routes have to be deleted, otherwise adding them

# for $dst fails (duplicate routes).

transfer_routes () {

    local src=$1

    local dst=$2

    # List all routes and grep the ones with $src in.

    # Stick 'ip route del' on the front to delete.

    # Change $src to $dst and use 'ip route add' to add.

    ip route list | sed -ne "

/dev ${src}\( \|$\)/ {

  h

  s/^/ip route del /

  P

  g

  s/${src}/${dst}/

  s/^/ip route add /

  P

  d

}" | sh -e

}

##

# link_exists interface

#

# Returns 0 if the interface named exists (whether up or down), 1 otherwise.

#

link_exists()

{

    if ip link show "$1" >/dev/null 2>/dev/null

    then

        return 0

    else

        return 1

    fi

}

# Set the default forwarding policy for $dev to drop.

# Allow forwarding to the bridge.

antispoofing () {

    iptables -P FORWARD DROP

    iptables -F FORWARD

    iptables -A FORWARD -m physdev --physdev-in ${pdev} -j ACCEPT

}

# Usage: show_status dev bridge

# Print ifconfig and routes.

show_status () {

    local dev=$1

    local bridge=$2

    echo '============================================================'

    ip addr show ${dev}

    ip addr show ${bridge}

    echo ' '

    brctl show ${bridge}

    echo ' '

    ip route list

    echo ' '

    route -n

    echo '============================================================'

}

op_start () {

    if [ "${bridge}" = "null" ] ; then

	return

    fi

    if link_exists "$pdev"; then

        # The device is already up.

        return

    fi

    claim_lock "network-bridge"

    create_bridge ${tdev}

    preiftransfer ${netdev}

    transfer_addrs ${netdev} ${tdev}

    # Remember slaves for bonding interface.

    if [ -e /sys/class/net/${netdev}/bonding/slaves ]; then

	slaves=`cat /sys/class/net/${netdev}/bonding/slaves`

    fi

    # Remember the IP details for do_ifup.

    get_ip_info ${netdev}

    if ! ifdown ${netdev}; then

	ip link set ${netdev} down

	ip addr flush ${netdev}

    fi

    ip link set ${netdev} name ${pdev}

    ip link set ${tdev} name ${bridge}

    setup_bridge_port ${pdev}

    # Restore slaves

    if [ -n "${slaves}" ]; then

	ip link set ${pdev} up

	ifenslave ${pdev} ${slaves}

    fi

    add_to_bridge2 ${bridge} ${pdev}

    do_ifup ${bridge}

    if [ ${antispoof} = 'yes' ] ; then

	antispoofing

    fi

    # ST-2011-02-28: for the internal bridge

    create_bridge internal

    brctl stp internal off

    brctl setfd internal 0

    ip link set internal up

    # End internal bridge

    release_lock "network-bridge"

}

op_stop () {

    if [ "${bridge}" = "null" ]; then

	return

    fi

    if ! link_exists "$bridge"; then

	return

    fi

    claim_lock "network-bridge"

    transfer_addrs ${bridge} ${pdev}

    if ! ifdown ${bridge}; then

	get_ip_info ${bridge}

    fi

    ip link set ${pdev} down

    ip addr flush ${bridge}

    brctl delif ${bridge} ${pdev}

    ip link set ${bridge} down

    ip link set ${bridge} name ${tdev}

    ip link set ${pdev} name ${netdev}

    do_ifup ${netdev}

    brctl delbr ${tdev}

    # ST-2011-02-28: for the internal bridge

    brctl delbr internal

    # End internal bridge

    release_lock "network-bridge"

}

# adds $dev to $bridge but waits for $dev to be in running state first

add_to_bridge2() {

    local bridge=$1

    local dev=$2

    local maxtries=10

    echo -n "Waiting for ${dev} to negotiate link."

    ip link set ${dev} up

    for i in `seq ${maxtries}` ; do

	if ifconfig ${dev} | grep -q RUNNING ; then

	    break

	else

	    echo -n '.'

	    sleep 1

	fi

    done

    if [ ${i} -eq ${maxtries} ] ; then echo -n '(link isnt in running state)' ; fi

    echo

    add_to_bridge ${bridge} ${dev}

}

case "$command" in

    start)

	op_start

	;;

    stop)

	op_stop

	;;

    status)

	show_status ${netdev} ${bridge}

	;;

    *)

	echo "Unknown command: $command" >&2

	echo 'Valid commands are: start, stop, status' >&2

	exit 1

esac