cidr.py

import struct
import re

ipfile = open("scanner_uniq.dat", 'r')

print('# CIDR, Number_of_prefixes')

for cidr in range(1, 33):
    prefixes = dict()

    ipfile.seek(0)

    for line in ipfile:
        parts = line.rstrip().split('.')

        addr = (int(parts[0]) << 24) + (int(parts[1]) << 16) + (int(parts[2]) << 8) + int(parts[3])
        mask = (0xffffffff >> (32 - cidr)) << (32 - cidr)
        # print(hex(addr & mask), hex(addr), hex(mask))

        pfx = hex(addr & mask)
        if pfx not in prefixes.keys():
            prefixes[pfx] = 0

        prefixes[pfx] += 1

    print(cidr, "\t", len(prefixes.keys()))

ipfile.close()