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bpo-41004: Resolve hash collisions for IPv4Interface and IPv6Interface (GH-21033) 

The __hash__() methods of classes IPv4Interface and IPv6Interface had issue
of generating constant hash values of 32 and 128 respectively causing hash collisions.
The fix uses the hash() function to generate hash values for the objects
instead of XOR operation
This commit is contained in:
Ravi Teja P 2020-06-29 23:09:29 +05:30 committed by GitHub
parent a3ad95dd21
commit b30ee26e36
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 15 additions and 2 deletions
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4
Lib/ipaddress.py
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@ -1420,7 +1420,7 @@ class IPv4Interface(IPv4Address):
return False return False
def __hash__(self): def __hash__(self):
return self._ip ^ self._prefixlen ^ int(self.network.network_address) return hash((self._ip, self._prefixlen, int(self.network.network_address)))
__reduce__ = _IPAddressBase.__reduce__ __reduce__ = _IPAddressBase.__reduce__
@ -2120,7 +2120,7 @@ class IPv6Interface(IPv6Address):
return False return False
def __hash__(self): def __hash__(self):
return self._ip ^ self._prefixlen ^ int(self.network.network_address) return hash((self._ip, self._prefixlen, int(self.network.network_address)))
__reduce__ = _IPAddressBase.__reduce__ __reduce__ = _IPAddressBase.__reduce__

12
Lib/test/test_ipaddress.py
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@ -2548,6 +2548,18 @@ class IpaddrUnitTest(unittest.TestCase):
sixtofouraddr.sixtofour) sixtofouraddr.sixtofour)
self.assertFalse(bad_addr.sixtofour) self.assertFalse(bad_addr.sixtofour)
# issue41004 Hash collisions in IPv4Interface and IPv6Interface
def testV4HashIsNotConstant(self):
ipv4_address1 = ipaddress.IPv4Interface("1.2.3.4")
ipv4_address2 = ipaddress.IPv4Interface("2.3.4.5")
self.assertNotEqual(ipv4_address1.__hash__(), ipv4_address2.__hash__())
# issue41004 Hash collisions in IPv4Interface and IPv6Interface
def testV6HashIsNotConstant(self):
ipv6_address1 = ipaddress.IPv6Interface("2001:658:22a:cafe:200:0:0:1")
ipv6_address2 = ipaddress.IPv6Interface("2001:658:22a:cafe:200:0:0:2")
self.assertNotEqual(ipv6_address1.__hash__(), ipv6_address2.__hash__())
if __name__ == '__main__': if __name__ == '__main__':
unittest.main() unittest.main()

1
Misc/NEWS.d/next/Security/2020-06-29-16-02-29.bpo-41004.ovF0KZ.rst Normal file
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@ -0,0 +1 @@
The __hash__() methods of ipaddress.IPv4Interface and ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and 128 respectively. This resulted in always causing hash collisions. The fix uses hash() to generate hash values for the tuple of (address, mask length, network address).