from django.db import transaction from django.db.models import Count, F from .models import * def get_suitable_pools(subnetwork_mask): """ Find suitable pools for a certain network size. First, filter for all pools that offer the requested subnetwork_size. Then find those pools that are not fully exhausted: The number of available networks in a pool is 2^(subnetwork_size-network_size. The number of available networks in a pool is given by the number of VPNNetworkreservations. """ return WireGuardVPNPool.objects.annotate( num_reservations=Count('wireguardvpn'), max_reservations=2**(F('subnetwork_mask')-F('network_mask'))).filter( num_reservations__lt=F('max_reservations'), subnetwork_mask=subnetwork_mask) def allowed_vpn_network_reservation_size(): """ Find all possible sizes of subnetworks that are available. Select all pools with free networks. Get their subnetwork sizes, reduce to a set """ pools = WireGuardVPNPool.objects.annotate(num_reservations=Count('wireguardvpn'), max_reservations=2**(F('subnetwork_mask')-F('network_mask'))).filter( num_reservations__lt=F('max_reservations')) # Need to return set of tuples, see # https://docs.djangoproject.com/en/3.1/ref/models/fields/#field-choices # return set([ (pool.subnetwork_mask, pool.subnetwork_mask) for pool in pools ]) return set([pool.subnetwork_mask for pool in pools ])