GH-113171: Fix "private" (non-global) IP address ranges (GH-113179)

* GH-113171: Fix "private" (really non-global) IP address ranges

The _private_networks variables, used by various is_private
implementations, were missing some ranges and at the same time had
overly strict ranges (where there are more specific ranges considered
globally reachable by the IANA registries).

This patch updates the ranges with what was missing or otherwise
incorrect.

I left 100.64.0.0/10 alone, for now, as it's been made special in [1]
and I'm not sure if we want to undo that as I don't quite understand the
motivation behind it.

The _address_exclude_many() call returns 8 networks for IPv4, 121
networks for IPv6.

[1] https://github.com/python/cpython/issues/61602

5 files changed, 82 insertions, 7 deletions

diff --git a/Doc/library/ipaddress.rst b/Doc/library/ipaddress.rst
index 73f4960..8f090b5 100644
--- a/Doc/library/ipaddress.rst
+++ b/Doc/library/ipaddress.rst
@@ -192,6 +192,18 @@ write code that handles both IP versions correctly.  Address objects are
       ``is_private`` has value opposite to :attr:`is_global`, except for the shared address space
       (``100.64.0.0/10`` range) where they are both ``False``.
 
+      .. versionchanged:: 3.13
+
+         Fixed some false positives and false negatives.
+
+         * ``192.0.0.0/24`` is considered private with the exception of ``192.0.0.9/32`` and
+           ``192.0.0.10/32`` (previously: only the ``192.0.0.0/29`` sub-range was considered private).
+         * ``64:ff9b:1::/48`` is considered private.
+         * ``2002::/16`` is considered private.
+         * There are exceptions within ``2001::/23`` (otherwise considered private): ``2001:1::1/128``,
+           ``2001:1::2/128``, ``2001:3::/32``, ``2001:4:112::/48``, ``2001:20::/28``, ``2001:30::/28``.
+           The exceptions are not considered private.
+
    .. attribute:: is_global
 
       ``True`` if the address is defined as globally reachable by
@@ -209,6 +221,10 @@ write code that handles both IP versions correctly.  Address objects are
 
       .. versionadded:: 3.4
 
+      .. versionchanged:: 3.13
+
+         Fixed some false positives and false negatives, see :attr:`is_private` for details.
+
    .. attribute:: is_unspecified
 
       ``True`` if the address is unspecified.  See :RFC:`5735` (for IPv4)
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index 7e6c79d..bec788e 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -401,6 +401,8 @@ ipaddress
 
 * Add the :attr:`ipaddress.IPv4Address.ipv6_mapped` property, which returns the IPv4-mapped IPv6 address.
   (Contributed by Charles Machalow in :gh:`109466`.)
+* Fix ``is_global`` and ``is_private`` behavior in ``IPv4Address``, ``IPv6Address``, ``IPv4Network``
+  and ``IPv6Network``.
 
 itertools
 ---------
diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index 7d6edcf..22cdfc9 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1086,7 +1086,11 @@ class _BaseNetwork(_IPAddressBase):
         """
         return any(self.network_address in priv_network and
                    self.broadcast_address in priv_network
-                   for priv_network in self._constants._private_networks)
+                   for priv_network in self._constants._private_networks) and all(
+                    self.network_address not in network and
+                    self.broadcast_address not in network
+                    for network in self._constants._private_networks_exceptions
+                )
 
     @property
     def is_global(self):
@@ -1347,7 +1351,10 @@ class IPv4Address(_BaseV4, _BaseAddress):
         ``is_private`` has value opposite to :attr:`is_global`, except for the ``100.64.0.0/10``
         IPv4 range where they are both ``False``.
         """
-        return any(self in net for net in self._constants._private_networks)
+        return (
+            any(self in net for net in self._constants._private_networks)
+            and all(self not in net for net in self._constants._private_networks_exceptions)
+        )
 
     @property
     @functools.lru_cache()
@@ -1578,13 +1585,15 @@ class _IPv4Constants:
 
     _public_network = IPv4Network('100.64.0.0/10')
 
+    # Not globally reachable address blocks listed on
+    # https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
     _private_networks = [
         IPv4Network('0.0.0.0/8'),
         IPv4Network('10.0.0.0/8'),
         IPv4Network('127.0.0.0/8'),
         IPv4Network('169.254.0.0/16'),
         IPv4Network('172.16.0.0/12'),
-        IPv4Network('192.0.0.0/29'),
+        IPv4Network('192.0.0.0/24'),
         IPv4Network('192.0.0.170/31'),
         IPv4Network('192.0.2.0/24'),
         IPv4Network('192.168.0.0/16'),
@@ -1595,6 +1604,11 @@ class _IPv4Constants:
         IPv4Network('255.255.255.255/32'),
         ]
 
+    _private_networks_exceptions = [
+        IPv4Network('192.0.0.9/32'),
+        IPv4Network('192.0.0.10/32'),
+    ]
+
     _reserved_network = IPv4Network('240.0.0.0/4')
 
     _unspecified_address = IPv4Address('0.0.0.0')
@@ -2086,7 +2100,10 @@ class IPv6Address(_BaseV6, _BaseAddress):
         ipv4_mapped = self.ipv4_mapped
         if ipv4_mapped is not None:
             return ipv4_mapped.is_private
-        return any(self in net for net in self._constants._private_networks)
+        return (
+            any(self in net for net in self._constants._private_networks)
+            and all(self not in net for net in self._constants._private_networks_exceptions)
+        )
 
     @property
     def is_global(self):
@@ -2342,19 +2359,31 @@ class _IPv6Constants:
 
     _multicast_network = IPv6Network('ff00::/8')
 
+    # Not globally reachable address blocks listed on
+    # https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml
     _private_networks = [
         IPv6Network('::1/128'),
         IPv6Network('::/128'),
         IPv6Network('::ffff:0:0/96'),
+        IPv6Network('64:ff9b:1::/48'),
         IPv6Network('100::/64'),
         IPv6Network('2001::/23'),
-        IPv6Network('2001:2::/48'),
         IPv6Network('2001:db8::/32'),
-        IPv6Network('2001:10::/28'),
+        # IANA says N/A, let's consider it not globally reachable to be safe
+        IPv6Network('2002::/16'),
         IPv6Network('fc00::/7'),
         IPv6Network('fe80::/10'),
         ]
 
+    _private_networks_exceptions = [
+        IPv6Network('2001:1::1/128'),
+        IPv6Network('2001:1::2/128'),
+        IPv6Network('2001:3::/32'),
+        IPv6Network('2001:4:112::/48'),
+        IPv6Network('2001:20::/28'),
+        IPv6Network('2001:30::/28'),
+    ]
+
     _reserved_networks = [
         IPv6Network('::/8'), IPv6Network('100::/8'),
         IPv6Network('200::/7'), IPv6Network('400::/6'),
diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index b4952ac..f1519df 100644
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -2288,6 +2288,10 @@ class IpaddrUnitTest(unittest.TestCase):
         self.assertEqual(True, ipaddress.ip_address(
                 '172.31.255.255').is_private)
         self.assertEqual(False, ipaddress.ip_address('172.32.0.0').is_private)
+        self.assertFalse(ipaddress.ip_address('192.0.0.0').is_global)
+        self.assertTrue(ipaddress.ip_address('192.0.0.9').is_global)
+        self.assertTrue(ipaddress.ip_address('192.0.0.10').is_global)
+        self.assertFalse(ipaddress.ip_address('192.0.0.255').is_global)
 
         self.assertEqual(True,
                          ipaddress.ip_address('169.254.100.200').is_link_local)
@@ -2313,6 +2317,7 @@ class IpaddrUnitTest(unittest.TestCase):
         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(False, ipaddress.ip_network("192.0.0.9/32").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)
@@ -2329,8 +2334,8 @@ class IpaddrUnitTest(unittest.TestCase):
         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(False, ipaddress.ip_network("2001:3::/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)
@@ -2409,6 +2414,20 @@ class IpaddrUnitTest(unittest.TestCase):
         self.assertEqual(True, ipaddress.ip_address('0::0').is_unspecified)
         self.assertEqual(False, ipaddress.ip_address('::1').is_unspecified)
 
+        self.assertFalse(ipaddress.ip_address('64:ff9b:1::').is_global)
+        self.assertFalse(ipaddress.ip_address('2001::').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:1::1').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:1::2').is_global)
+        self.assertFalse(ipaddress.ip_address('2001:2::').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:3::').is_global)
+        self.assertFalse(ipaddress.ip_address('2001:4::').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:4:112::').is_global)
+        self.assertFalse(ipaddress.ip_address('2001:10::').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:20::').is_global)
+        self.assertTrue(ipaddress.ip_address('2001:30::').is_global)
+        self.assertFalse(ipaddress.ip_address('2001:40::').is_global)
+        self.assertFalse(ipaddress.ip_address('2002::').is_global)
+
         # some generic IETF reserved addresses
         self.assertEqual(True, ipaddress.ip_address('100::').is_reserved)
         self.assertEqual(True, ipaddress.ip_network('4000::1/128').is_reserved)
diff --git a/Misc/NEWS.d/next/Library/2024-03-14-01-38-44.gh-issue-113171.VFnObz.rst b/Misc/NEWS.d/next/Library/2024-03-14-01-38-44.gh-issue-113171.VFnObz.rst
new file mode 100644
index 0000000..f9a7247
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-03-14-01-38-44.gh-issue-113171.VFnObz.rst
@@ -0,0 +1,9 @@
+Fixed various false positives and false negatives in
+
+* :attr:`ipaddress.IPv4Address.is_private` (see these docs for details)
+* :attr:`ipaddress.IPv4Address.is_global`
+* :attr:`ipaddress.IPv6Address.is_private`
+* :attr:`ipaddress.IPv6Address.is_global`
+
+Also in the corresponding :class:`ipaddress.IPv4Network` and :class:`ipaddress.IPv6Network`
+attributes.