39 lines
1.0 KiB
Python
39 lines
1.0 KiB
Python
"""Canonicalize CIDR"""
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DIGITS = (24, 16, 8, 0)
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def dotted_to_int(dotted: str) -> int:
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digits = [int(digit) for digit in dotted.split(".")]
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return sum(a << b for a, b in zip(digits, DIGITS))
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def int_to_dotted(ip: int) -> str:
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digits = [(ip & (255 << d)) >> d for d in DIGITS]
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return ".".join(str(d) for d in digits)
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def network_mask(number_of_bits: int) -> int:
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return ((1 << number_of_bits) - 1) << (32 - number_of_bits)
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def canonicalize(ip: str) -> str:
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dotted, network_bits = ip.split("/")
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i = dotted_to_int(dotted)
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mask = network_mask(int(network_bits))
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return int_to_dotted(i & mask) + "/" + network_bits
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TEST_CASES = [
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("36.18.154.103/12", "36.16.0.0/12"),
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("62.62.197.11/29", "62.62.197.8/29"),
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("67.137.119.181/4", "64.0.0.0/4"),
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("161.214.74.21/24", "161.214.74.0/24"),
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("184.232.176.184/18", "184.232.128.0/18"),
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]
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if __name__ == "__main__":
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for ip, expect in TEST_CASES:
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rv = canonicalize(ip)
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print(f"{ip:<18} -> {rv}")
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assert rv == expect
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