2020-12-13 10:38:41 +00:00
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from django.db import transaction
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from django.db.models import Count, F
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2020-12-09 20:20:33 +00:00
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from .models import *
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def get_suitable_pool(subnetwork_size):
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"""
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Find suitable pools for a certain network size.
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First, filter for all pools that offer the requested subnetwork_size.
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Then find those pools that are not fully exhausted:
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The number of available networks in a pool is 2^(subnetwork_size-network_size.
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The number of available networks in a pool is given by the number of VPNNetworkreservations.
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"""
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return VPNPool.objects.annotate(
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num_reservations=Count('vpnnetworkreservation'),
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max_reservations=2**(F('subnetwork_size')-F('network_size'))).filter(
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num_reservations__lt=F('max_reservations'),
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subnetwork_size=subnetwork_size)
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2020-12-13 10:38:41 +00:00
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def allowed_vpn_network_reservation_size():
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"""
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Find all possible sizes of subnetworks that are available.
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Select all pools with free networks.
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Get their subnetwork sizes, reduce to a set
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"""
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pools = VPNPool.objects.annotate(num_reservations=Count('vpnnetworkreservation'),
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max_reservations=2**(F('subnetwork_size')-F('network_size'))).filter(
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num_reservations__lt=F('max_reservations'))
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return set([ pool.subnetwork_size for pool in pools ])
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