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rinsuki/weird_way_of_convert_ipv6_net_mask_to_prefix_length.py

Created December 27, 2024 05:40
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weird_way_of_convert_ipv6_net_mask_to_prefix_length.py
import ipaddress
import re
def convert_ipv6_netmask_to_prefixlen(addr: str):
addr = ipaddress.IPv6Interface(addr)
addr = "".join([f"{byte:08b}" for byte in addr.packed])
return len(re.match("^(1*)(0*)$", addr).group(1))
assert convert_ipv6_netmask_to_prefixlen("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff") == 128
assert convert_ipv6_netmask_to_prefixlen("ffff:ffff:ffff:ffff::") == 64
assert convert_ipv6_netmask_to_prefixlen("ffff:ffff::") == 32
assert convert_ipv6_netmask_to_prefixlen("::") == 0
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