George Shuklin さんが Wildcard masks operations in Python という記事で「Python でワイルドカードを操作する方法」をまとめてくださっています。 ワイルドカードが関連しないケースも含め、「プリフィックス長」「ネットマスク」「ワイルドカード」を相互変換する Python サンプルコードをメモしておきます。
サンプルコード
#!/usr/bin/env python3
from ipaddress import IPv4Address
def prefixlen_to_netmask(prefixlen: int) -> str:
return str(IPv4Address(int(IPv4Address._make_netmask(prefixlen)[0])))
def prefixlen_to_wildcard(prefixlen: int) -> str:
return str(
IPv4Address(int(IPv4Address._make_netmask(prefixlen)[0]) ^ (2**32 - 1))
)
def netmask_to_prefixlen(netmask: str) -> int:
return IPv4Address._prefix_from_ip_int(int(IPv4Address(netmask)))
def netmask_to_wildcard(netmask: str) -> str:
return str(IPv4Address(int(IPv4Address(netmask)) ^ (2**32 - 1)))
def wildcard_to_netmask(wildcard: str) -> str:
return str(IPv4Address(int(IPv4Address(wildcard)) ^ (2**32 - 1)))
def wildcard_to_prefixlen(wildcard: str) -> int:
return IPv4Address._prefix_from_ip_int(int(IPv4Address(wildcard)) ^ (2**32 - 1))
print(prefixlen_to_netmask(24))
print(prefixlen_to_wildcard(24))
print(netmask_to_prefixlen("255.255.255.0"))
print(netmask_to_wildcard("255.255.255.0"))
print(wildcard_to_netmask("0.0.0.255"))
print(wildcard_to_prefixlen("0.0.0.255"))実行例
# ./sample.py
255.255.255.0
0.0.0.255
24
0.0.0.255
255.255.255.0
24ユニットテスト
サンプルコード
#!/usr/bin/env python3
import unittest
import sample
PREFIXLEN = 0
NETMASK = 1
WILDCARD = 2
values = [
[0, "0.0.0.0", "255.255.255.255"],
[1, "128.0.0.0", "127.255.255.255"],
[2, "192.0.0.0", "63.255.255.255"],
[3, "224.0.0.0", "31.255.255.255"],
[4, "240.0.0.0", "15.255.255.255"],
[5, "248.0.0.0", "7.255.255.255"],
[6, "252.0.0.0", "3.255.255.255"],
[7, "254.0.0.0", "1.255.255.255"],
[8, "255.0.0.0", "0.255.255.255"],
[9, "255.128.0.0", "0.127.255.255"],
[10, "255.192.0.0", "0.63.255.255"],
[11, "255.224.0.0", "0.31.255.255"],
[12, "255.240.0.0", "0.15.255.255"],
[13, "255.248.0.0", "0.7.255.255"],
[14, "255.252.0.0", "0.3.255.255"],
[15, "255.254.0.0", "0.1.255.255"],
[16, "255.255.0.0", "0.0.255.255"],
[17, "255.255.128.0", "0.0.127.255"],
[18, "255.255.192.0", "0.0.63.255"],
[19, "255.255.224.0", "0.0.31.255"],
[20, "255.255.240.0", "0.0.15.255"],
[21, "255.255.248.0", "0.0.7.255"],
[22, "255.255.252.0", "0.0.3.255"],
[23, "255.255.254.0", "0.0.1.255"],
[24, "255.255.255.0", "0.0.0.255"],
[25, "255.255.255.128", "0.0.0.127"],
[26, "255.255.255.192", "0.0.0.63"],
[27, "255.255.255.224", "0.0.0.31"],
[28, "255.255.255.240", "0.0.0.15"],
[29, "255.255.255.248", "0.0.0.7"],
[30, "255.255.255.252", "0.0.0.3"],
[31, "255.255.255.254", "0.0.0.1"],
[32, "255.255.255.255", "0.0.0.0"],
]
class TestSample(unittest.TestCase):
def test_prefixlen_to_netmask(self):
for value in values:
self.assertEqual(
sample.prefixlen_to_netmask(value[PREFIXLEN]), value[NETMASK]
)
def test_prefixlen_to_wildcard(self):
for value in values:
self.assertEqual(
sample.prefixlen_to_wildcard(value[PREFIXLEN]), value[WILDCARD]
)
def test_netmask_to_prefixlen(self):
for value in values:
self.assertEqual(
sample.netmask_to_prefixlen(value[NETMASK]), value[PREFIXLEN]
)
def test_netmask_to_wildcard(self):
for value in values:
self.assertEqual(
sample.netmask_to_wildcard(value[NETMASK]), value[WILDCARD]
)
def test_wildcard_to_netmask(self):
for value in values:
self.assertEqual(
sample.wildcard_to_netmask(value[WILDCARD]), value[NETMASK]
)
def test_wildcard_to_prefixlen(self):
for value in values:
self.assertEqual(
sample.wildcard_to_prefixlen(value[WILDCARD]), value[PREFIXLEN]
)実行例
# python3 -m unittest test_sample.py
......
----------------------------------------------------------------------
Ran 6 tests in 0.002s
OK
コメント