[3.9] gh-134062: Fix hash collisions in IPv4Network and IPv6Network (GH-134063) (GH-134481)

(cherry picked from commit f3fc0c1)

Co-authored-by: Mike Salvatore <[email protected]>

Author: miss-islington

Lib/ipaddress.py

@@ -733,7 +733,7 @@ def __eq__(self, other):
             return NotImplemented
 
     def __hash__(self):
-        return hash(int(self.network_address) ^ int(self.netmask))
+        return hash((int(self.network_address), int(self.netmask)))
 
     def __contains__(self, other):
         # always false if one is v4 and the other is v6.

Lib/test/test_ipaddress.py

@@ -2679,6 +2679,34 @@ def testV6HashIsNotConstant(self):
         ipv6_address2 = ipaddress.IPv6Interface("2001:658:22a:cafe:200:0:0:2")
         self.assertNotEqual(ipv6_address1.__hash__(), ipv6_address2.__hash__())
 
+    # issue 134062 Hash collisions in IPv4Network and IPv6Network
+    def testNetworkV4HashCollisions(self):
+        self.assertNotEqual(
+            ipaddress.IPv4Network("192.168.1.255/32").__hash__(),
+            ipaddress.IPv4Network("192.168.1.0/24").__hash__()
+        )
+        self.assertNotEqual(
+            ipaddress.IPv4Network("172.24.255.0/24").__hash__(),
+            ipaddress.IPv4Network("172.24.0.0/16").__hash__()
+        )
+        self.assertNotEqual(
+            ipaddress.IPv4Network("192.168.1.87/32").__hash__(),
+            ipaddress.IPv4Network("192.168.1.86/31").__hash__()
+        )
+
+    # issue 134062 Hash collisions in IPv4Network and IPv6Network
+    def testNetworkV6HashCollisions(self):
+        self.assertNotEqual(
+            ipaddress.IPv6Network("fe80::/64").__hash__(),
+            ipaddress.IPv6Network("fe80::ffff:ffff:ffff:0/112").__hash__()
+        )
+        self.assertNotEqual(
+            ipaddress.IPv4Network("10.0.0.0/8").__hash__(),
+            ipaddress.IPv6Network(
+                "ffff:ffff:ffff:ffff:ffff:ffff:aff:0/112"
+            ).__hash__()
+        )
+
 
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2025-05-15-14-27-01.gh-issue-134062.fRbJet.rst

@@ -0,0 +1,3 @@
+:mod:`ipaddress`: fix collisions in :meth:`~object.__hash__` for
+:class:`~ipaddress.IPv4Network` and :class:`~ipaddress.IPv6Network`
+objects.