core-agent-linux/network/vif-route-qubes-nat

#!/bin/bash                              
#============================================================================
# /etc/xen/vif-route-qubes-nat                                               
#                                                                            
# Script for configuring a vif in routed mode.                               
# The hotplugging system will call this script if it is specified either in  
# the device configuration given to Xend, or the default Xend configuration  
# in /etc/xen/xend-config.sxp.  If the script is specified in neither of those
# places, then vif-bridge is the default.                                     
#                                                                             
# Usage:                                                                      
# vif-route (add|remove|online|offline)                                       
#                                                                             
# Environment vars:                                                           
# vif         vif interface name (required).                                  
# XENBUS_PATH path to this device's details in the XenStore (required).       
#                                                                             
# Read from the store:                                                        
# ip      list of IP networks for the vif, space-separated (default given in  
#         this script).                                                       
#============================================================================ 

appvm_gw_ip="$1"
netvm_ip="$2"
shift 2

dir=$(dirname "$0")
. "$dir/vif-common.sh"

if [ "${ip}" ]; then
	appvm_ip="$ip"
	netvm_gw_ip=`qubesdb-read /qubes-netvm-gateway`
	netvm_dns2_ip=`qubesdb-read /qubes-netvm-secondary-dns`

        ip="$netvm_ip"
        back_ip="$netvm_gw_ip"
fi

#echo "$appvm_ip $appvm_gw_ip $netvm_ip $netvm_gw_ip" >> /var/log/qubes-nat.log

#main_ip=$(dom0_ip)
lockfile=/var/run/xen-hotplug/vif-lock

if [ "${ip}" ]; then
	if test "$command" == online; then
		echo 1 >/proc/sys/net/ipv4/conf/${vif}/proxy_arp
	fi

	. "$dir/vif-qubes-nat.sh"
fi

case "$command" in
	online)
		ifconfig ${vif} up
		echo 1 >/proc/sys/net/ipv4/conf/${vif}/proxy_arp
		ipcmd='add'
		iptables_cmd='-I PREROUTING 1'
		cmdprefix=''
		;;
	offline)
		do_without_error ifdown ${vif}
		ipcmd='del'
		iptables_cmd='-D PREROUTING'
		cmdprefix='do_without_error'
		;;
esac

domid=${vif/vif/}
domid=${domid/.*/}
# metric must be possitive, but prefer later interface
#  32752 is max XID aka domid
metric=$[ 32752 - $domid ]

if [ "${ip}" ] ; then
	# If we've been given a list of IP addresses, then add routes from dom0 to
	# the guest using those addresses.
	for addr in ${ip} ; do
		${cmdprefix} ip route ${ipcmd} ${addr} dev ${vif} metric $metric
	done
	echo -e "*raw\n$iptables_cmd -i ${vif} ! -s ${ip} -j DROP\nCOMMIT" | \
		${cmdprefix} flock $lockfile iptables-restore --noflush
	${cmdprefix} ip addr ${ipcmd} ${back_ip}/32 dev ${vif}
fi

log debug "Successful vif-route-qubes-nat $command for $vif."
if [ "$command" = "online" ]
then
  # disable tx checksumming offload, apparently it doesn't work with our ancient qemu in stubdom
  do_without_error ethtool -K $vif tx off
  success
fi