subnet squeeze

subnets_collapse.py

from typing import List
import ipaddress


lst = ['10.10.20.0/24',
       '10.10.30.0/25',
       '10.10.30.128/25',
       '10.10.31.0/24',
       '10.10.32.0/24'
       ]

filtered_lst = list(filter(lambda x: '/3' not in x, lst))
network_list = [ipaddress.IPv4Network(x) for x in filtered_lst]
network_list.sort()


def adjacent_network(net1: ipaddress.IPv4Network, net2: ipaddress.IPv4Network):
    if net2 <= net1:
        net1, net2 = net2, net1
    if (net1.broadcast_address == net2.network_address - 1
            and net1.prefixlen == net2.prefixlen
            and int(net1.network_address) == int(net1.network_address) & int(net2.broadcast_address)):
        return True


def compress_contiguous(net_lst: List[ipaddress.IPv4Network]):
    work = True
    while work:
        work = False
        for idx in range(len(net_lst)-1):
            if adjacent_network(net_lst[idx], net_lst[idx+1]):
                work = True
                net_lst[idx] = ipaddress.IPv4Network(f'{net_lst[idx].network_address.compressed}/{net_lst[idx].prefixlen-1}')
                del net_lst[idx+1]
                break
    return net_lst


print()
print(network_list)
print()
compress_contiguous(network_list)
print(network_list)