Libvirt APIs for creating virtual networks

I am using the Libvirt APIs to create the virtual networks to use the dnsmasq capabilities. I want to understand the APIs how to set the lease time in XML to control the dnsmasq lease time. Also, I need some DHCP statistics on the virtual network. Is there any API available to fetch the statistics ? Please let me know if any ? Thanks & Regards Santhosh Kumar Gunturu