#!/bin/bash
#============================================================================
# Default Xen network start/stop script.
# Xend calls a network script when it starts.
# The script name to use is defined in /etc/xen/xend-config.sxp
# in the network-script field.
#
# 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.
#
# 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/xen-script-common.sh"
. "$dir/xen-network-common.sh"
findCommand "$@"
evalVariables "$@"
netdev=${netdev:-$(ip route list | awk '/^default / { print $NF }' |
sed 's/.* dev //')}
bridge=${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 ! ifup $1 ; then
if [ ${addr_pfx} ] ; then
# use the info from get_ip_info()
ip addr flush $1
ip addr add ${addr_pfx} dev $1
ip link set dev $1 up
[ ${gateway} ] && ip route add default via ${gateway}
fi
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}/
" | 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
create_bridge ${tdev}
preiftransfer ${netdev}
transfer_addrs ${netdev} ${tdev}
if ! ifdown ${netdev}; then
# If ifdown fails, remember the IP details.
get_ip_info ${netdev}
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}
add_to_bridge2 ${bridge} ${pdev}
do_ifup ${bridge}
if [ ${antispoof} = 'yes' ] ; then
antispoofing
fi
}
op_stop () {
if [ "${bridge}" = "null" ]; then
return
fi
if ! link_exists "$bridge"; then
return
fi
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}
}
# 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 '(link isnt in running state)' ; fi
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
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