commit dc8ce8ead182de46584cc1ed8a8c51d48240cbd5
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Mon Jun 29 11:12:50 2020 -0700
committer GitHub <noreply@github.com> Mon Jun 29 11:12:50 2020 -0700
tree 1db73719f1165dddb6c97a759fdd45bb3f776e49
parent 7731139b7af655b9f5df6d1b5493f8dfdf41d569

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
(cherry picked from commit b30ee26e366bf509b7538d79bfec6c6d38d53f28)

Co-authored-by: Ravi Teja P <rvteja92@gmail.com>

Lib/ipaddress.py

diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index 873c764..a3a04f7 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1370,7 +1370,7 @@
             return False
 
     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__
 
@@ -2017,7 +2017,7 @@
             return False
 
     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__
 

Lib/test/test_ipaddress.py

diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index de77111..2eba740 100644
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -2053,6 +2053,18 @@
                          sixtofouraddr.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__':
     unittest.main()