This function fetches leases info of guests in the specified network.
If the optional parameter
mac is specified, the returned list will contain only lease info about a specific guest interface with
mac. There can be multiple leases for a single
mac because this API supports DHCPv6 too.
The optional ASCII formatted MAC address of an interface
placeholder for flags, must be 0
the list of network leases. Each object in the returned list should be unreffed with unref and the list itself using g_list_free, when no longer needed.