From: Petr Viktorin <encukou@gmail.com>
Date: Tue, 7 May 2024 11:57:58 +0200
Subject: gh-113171: gh-65056: Fix "private" (non-global) IP address ranges
 (GH-113179) (GH-113186) (GH-118177) (GH-118472)

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.

100.64.0.0/10 is left alone, for now, as it's been made special in [1].

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

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

In 3.10 and below, is_private checks whether the network and broadcast
address are both private.
In later versions (where the test wss backported from), it checks
whether they both are in the same private network.

For 0.0.0.0/0, both 0.0.0.0 and 255.225.255.255 are private,
but one is in 0.0.0.0/8 ("This network") and the other in
255.255.255.255/32 ("Limited broadcast").

---------

Co-authored-by: Jakub Stasiak <jakub@stasiak.at>

Origin: cpython, https://github.com/python/cpython/commit/22adf29da8d99933ffed8647d3e0726edd16f7f8
---
 lib-python/3/ipaddress.py           | 95 ++++++++++++++++++++++++++++++-------
 lib-python/3/test/test_ipaddress.py | 52 ++++++++++++++++++++
 2 files changed, 130 insertions(+), 17 deletions(-)

diff --git a/lib-python/3/ipaddress.py b/lib-python/3/ipaddress.py
index 25f373a..9b35340 100644
--- a/lib-python/3/ipaddress.py
+++ b/lib-python/3/ipaddress.py
@@ -1322,18 +1322,41 @@ class IPv4Address(_BaseV4, _BaseAddress):
     @property
     @functools.lru_cache()
     def is_private(self):
-        """Test if this address is allocated for private networks.
+        """``True`` if the address is defined as not globally reachable by
+        iana-ipv4-special-registry_ (for IPv4) or iana-ipv6-special-registry_
+        (for IPv6) with the following exceptions:
 
-        Returns:
-            A boolean, True if the address is reserved per
-            iana-ipv4-special-registry.
+        * ``is_private`` is ``False`` for ``100.64.0.0/10``
+        * For IPv4-mapped IPv6-addresses the ``is_private`` value is determined by the
+            semantics of the underlying IPv4 addresses and the following condition holds
+            (see :attr:`IPv6Address.ipv4_mapped`)::
+
+                address.is_private == address.ipv4_mapped.is_private
 
+        ``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()
     def is_global(self):
+        """``True`` if the address is defined as globally reachable by
+        iana-ipv4-special-registry_ (for IPv4) or iana-ipv6-special-registry_
+        (for IPv6) with the following exception:
+
+        For IPv4-mapped IPv6-addresses the ``is_private`` value is determined by the
+        semantics of the underlying IPv4 addresses and the following condition holds
+        (see :attr:`IPv6Address.ipv4_mapped`)::
+
+            address.is_global == address.ipv4_mapped.is_global
+
+        ``is_global`` has value opposite to :attr:`is_private`, except for the ``100.64.0.0/10``
+        IPv4 range where they are both ``False``.
+        """
         return self not in self._constants._public_network and not self.is_private
 
     @property
@@ -1537,13 +1560,15 @@ 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'),
@@ -1554,6 +1579,11 @@ 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')
@@ -1995,23 +2025,42 @@ class IPv6Address(_BaseV6, _BaseAddress):
     @property
     @functools.lru_cache()
     def is_private(self):
-        """Test if this address is allocated for private networks.
+        """``True`` if the address is defined as not globally reachable by
+        iana-ipv4-special-registry_ (for IPv4) or iana-ipv6-special-registry_
+        (for IPv6) with the following exceptions:
 
-        Returns:
-            A boolean, True if the address is reserved per
-            iana-ipv6-special-registry.
+        * ``is_private`` is ``False`` for ``100.64.0.0/10``
+        * For IPv4-mapped IPv6-addresses the ``is_private`` value is determined by the
+            semantics of the underlying IPv4 addresses and the following condition holds
+            (see :attr:`IPv6Address.ipv4_mapped`)::
+
+                address.is_private == address.ipv4_mapped.is_private
 
+        ``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)
+        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)
+            and all(self not in net for net in self._constants._private_networks_exceptions)
+        )
 
     @property
     def is_global(self):
-        """Test if this address is allocated for public networks.
+        """``True`` if the address is defined as globally reachable by
+        iana-ipv4-special-registry_ (for IPv4) or iana-ipv6-special-registry_
+        (for IPv6) with the following exception:
 
-        Returns:
-            A boolean, true if the address is not reserved per
-            iana-ipv6-special-registry.
+        For IPv4-mapped IPv6-addresses the ``is_private`` value is determined by the
+        semantics of the underlying IPv4 addresses and the following condition holds
+        (see :attr:`IPv6Address.ipv4_mapped`)::
+
+            address.is_global == address.ipv4_mapped.is_global
 
+        ``is_global`` has value opposite to :attr:`is_private`, except for the ``100.64.0.0/10``
+        IPv4 range where they are both ``False``.
         """
         return not self.is_private
 
@@ -2252,19 +2301,31 @@ 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-python/3/test/test_ipaddress.py b/lib-python/3/test/test_ipaddress.py
index 90897f6..bd14f04 100644
--- a/lib-python/3/test/test_ipaddress.py
+++ b/lib-python/3/test/test_ipaddress.py
@@ -2263,6 +2263,10 @@ 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)
@@ -2278,6 +2282,40 @@ class IpaddrUnitTest(unittest.TestCase):
         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(True, 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(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)
+        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("2001:2::/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)
+        self.assertEqual(True, ipaddress.ip_network("fe80::/10").is_private)
+
     def testReservedIpv6(self):
 
         self.assertEqual(True, ipaddress.ip_network('ffff::').is_multicast)
@@ -2351,6 +2389,20 @@ 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)
