gh-82836: fix private network check (GH-97733)

Fixes private checks for network objects. The previous method would incorrectly return True for a private check in cases such as "0.0.0.0/0".
(cherry picked from commit ed39109)

Co-authored-by: Pete Wicken <2273100+JamoBox@users.noreply.github.com>

Lib/ipaddress.py

@@ -1077,15 +1077,16 @@ def is_link_local(self):
 
     @property
     def is_private(self):
-        """Test if this address is allocated for private networks.
+        """Test if this network belongs to a private range.
 
         Returns:
-            A boolean, True if the address is reserved per
+            A boolean, True if the network is reserved per
             iana-ipv4-special-registry or iana-ipv6-special-registry.
 
         """
-        return (self.network_address.is_private and
-                self.broadcast_address.is_private)
+        return any(self.network_address in priv_network and
+                   self.broadcast_address in priv_network
+                   for priv_network in self._constants._private_networks)
 
     @property
     def is_global(self):
@@ -1122,6 +1123,15 @@ def is_loopback(self):
         return (self.network_address.is_loopback and
                 self.broadcast_address.is_loopback)
 
+
+class _BaseConstants:
+
+    _private_networks = []
+
+
+_BaseNetwork._constants = _BaseConstants
+
+
 class _BaseV4:
 
     """Base IPv4 object.
@@ -1561,6 +1571,7 @@ class _IPv4Constants:
 
 
 IPv4Address._constants = _IPv4Constants
+IPv4Network._constants = _IPv4Constants
 
 
 class _BaseV6:
@@ -2285,3 +2296,4 @@ class _IPv6Constants:
 
 
 IPv6Address._constants = _IPv6Constants
+IPv6Network._constants = _IPv6Constants

Lib/test/test_ipaddress.py

@@ -2277,6 +2277,39 @@ def testReservedIpv4(self):
         self.assertEqual(False, ipaddress.ip_address('128.0.0.0').is_loopback)
         self.assertEqual(True, ipaddress.ip_network('0.0.0.0').is_unspecified)
 
+    def testPrivateNetworks(self):
+        self.assertEqual(False, ipaddress.ip_network("0.0.0.0/0").is_private)
+        self.assertEqual(False, ipaddress.ip_network("1.0.0.0/8").is_private)
+
+        self.assertEqual(True, ipaddress.ip_network("0.0.0.0/8").is_private)
+        self.assertEqual(True, ipaddress.ip_network("10.0.0.0/8").is_private)
+        self.assertEqual(True, ipaddress.ip_network("127.0.0.0/8").is_private)
+        self.assertEqual(True, ipaddress.ip_network("169.254.0.0/16").is_private)
+        self.assertEqual(True, ipaddress.ip_network("172.16.0.0/12").is_private)
+        self.assertEqual(True, ipaddress.ip_network("192.0.0.0/29").is_private)
+        self.assertEqual(True, ipaddress.ip_network("192.0.0.170/31").is_private)
+        self.assertEqual(True, ipaddress.ip_network("192.0.2.0/24").is_private)
+        self.assertEqual(True, ipaddress.ip_network("192.168.0.0/16").is_private)
+        self.assertEqual(True, ipaddress.ip_network("198.18.0.0/15").is_private)
+        self.assertEqual(True, ipaddress.ip_network("198.51.100.0/24").is_private)
+        self.assertEqual(True, ipaddress.ip_network("203.0.113.0/24").is_private)
+        self.assertEqual(True, ipaddress.ip_network("240.0.0.0/4").is_private)
+        self.assertEqual(True, ipaddress.ip_network("255.255.255.255/32").is_private)
+
+        self.assertEqual(False, ipaddress.ip_network("::/0").is_private)
+        self.assertEqual(False, ipaddress.ip_network("::ff/128").is_private)
+
+        self.assertEqual(True, ipaddress.ip_network("::1/128").is_private)
+        self.assertEqual(True, ipaddress.ip_network("::/128").is_private)
+        self.assertEqual(True, ipaddress.ip_network("::ffff:0:0/96").is_private)
+        self.assertEqual(True, ipaddress.ip_network("100::/64").is_private)
+        self.assertEqual(True, ipaddress.ip_network("2001::/23").is_private)
+        self.assertEqual(True, ipaddress.ip_network("2001:2::/48").is_private)
+        self.assertEqual(True, ipaddress.ip_network("2001:db8::/32").is_private)
+        self.assertEqual(True, ipaddress.ip_network("2001:10::/28").is_private)
+        self.assertEqual(True, ipaddress.ip_network("fc00::/7").is_private)
+        self.assertEqual(True, ipaddress.ip_network("fe80::/10").is_private)
+
     def testReservedIpv6(self):
 
         self.assertEqual(True, ipaddress.ip_network('ffff::').is_multicast)

Misc/NEWS.d/next/Library/2022-10-02-12-38-22.gh-issue-82836.OvYLmC.rst

@@ -0,0 +1 @@
+Fix :attr:`~ipaddress.IPv4Address.is_private` properties in the :mod:`ipaddress` module. Previously non-private networks (0.0.0.0/0) would return True from this method; now they correctly return False.