[libvirt] Get disk size for disk type="network"

Hi, In the output of "virsh dumpxml" command the disk section is as follows: <disk type='network' device='disk'> <driver name='qemu' type='raw' cache='writeback'/> <auth username='svl-cc1-cinder-user'> <secret type='ceph' uuid='e80afa94-a64c-486c-9e34-d55e85f26406'/> </auth> <source protocol='rbd' name='svl-cc1-cinder-volume-1/volume-0a4cdeab-863d-4394-845f-008b993bc4e9'> <host name='10.34.114.211' port='6789'/> <host name='10.34.114.212' port='6789'/> <host name='10.34.114.213' port='6789'/> </source> <target dev='vda' bus='virtio'/> <serial>0a4cdeab-863d-4394-845f-008b993bc4e9</serial> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </disk> In this case how can I use libvirt to get the disk/volume size information? Thanks, Bruce