René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ipaddress considers some not globally reachable addresses global and vice versa","articleBody":"# Bug report\r\n\r\n### Bug description:\r\n\r\nJudging by what the `is_private` and `is_global` implementations in the `ipaddress` module do[1], everything that IANA special-purpose address registries[2][3] considers globally reachable should result in `is_global == True`, the rest should be `is_global = True`. \r\n\r\n`is_private` is almost always the opposite of `is_global` (`100.64.0.0/10` is special).\r\n\r\nThe problem is the ranges present in the code (in the `_private_networks` variables) are not quite right:\r\n\r\n* There are some ranges missing (so we incorrectly treat them as globally reachable)\r\n* Some of the ranges fail to account for more specific allocations defined as globally reachable (so we incorrectly treat them as not globally reachable)\r\n\r\nThis is what I have right now and I'll submit that as a PR:\r\n\r\n```diff\r\ndiff --git a/Lib/ipaddress.py b/Lib/ipaddress.py\r\nindex 5b5520b92bde..3ee565bcd30b 100644\r\n--- a/Lib/ipaddress.py\r\n+++ b/Lib/ipaddress.py\r\n@@ -1558,13 +1558,18 @@ class _IPv4Constants:\r\n \r\n     _public_network = IPv4Network('100.64.0.0/10')\r\n \r\n+    # Not globally reachable address blocks listed on\r\n+    # https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml\r\n     _private_networks = [\r\n         IPv4Network('0.0.0.0/8'),\r\n         IPv4Network('10.0.0.0/8'),\r\n+        # 100.64.0.0/10 missing\r\n         IPv4Network('127.0.0.0/8'),\r\n         IPv4Network('169.254.0.0/16'),\r\n         IPv4Network('172.16.0.0/12'),\r\n+        # Incomplete. Should be 192.0.0.0/24 - (192.0.0.9/32 + 192.0.0.10/32)\r\n         IPv4Network('192.0.0.0/29'),\r\n+        # 192.0.0.8/32 missing\r\n         IPv4Network('192.0.0.170/31'),\r\n         IPv4Network('192.0.2.0/24'),\r\n         IPv4Network('192.168.0.0/16'),\r\n@@ -2306,15 +2311,31 @@ class _IPv6Constants:\r\n \r\n     _multicast_network = IPv6Network('ff00::/8')\r\n \r\n+    # Not globally reachable address blocks listed on\r\n+    # https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml\r\n     _private_networks = [\r\n         IPv6Network('::1/128'),\r\n         IPv6Network('::/128'),\r\n         IPv6Network('::ffff:0:0/96'),\r\n+        # 64:ff9b:1::/48 missing\r\n         IPv6Network('100::/64'),\r\n+        # Not quite right as there are multiple more specific allocations that are globally\r\n+        # reachable. Should be:\r\n+        # 2001::/23 - (\r\n+        #     2001:1::1/128\r\n+        #     + 2001:1::2/128\r\n+        #     + 2001:3::/32\r\n+        #     + 2001:4:112::/48\r\n+        #     + 2001:20::/28\r\n+        #     + 2001:30::/28\r\n+        # )\r\n         IPv6Network('2001::/23'),\r\n+        # Unnecessary, covered by 2001::/23\r\n         IPv6Network('2001:2::/48'),\r\n         IPv6Network('2001:db8::/32'),\r\n+        # Unnecessary, covered by 2001::/23\r\n         IPv6Network('2001:10::/28'),\r\n+        # Potentially 2002::/16 missing? IANA says N/A, there is no true/false value\r\n         IPv6Network('fc00::/7'),\r\n         IPv6Network('fe80::/10'),\r\n         ]\r\n```\r\n\r\n[1] And which should really be documented per #65056 – a separate issue though\r\n[2] https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml\r\n[3] https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml\r\n\r\n### CPython versions tested on:\r\n\r\nCPython main branch\r\n\r\n### Operating systems tested on:\r\n\r\n_No response_\r\n\r\n\u003c!-- gh-linked-prs --\u003e\r\n### Linked PRs\r\n* gh-113179\r\n* gh-118177\n* gh-118227\n* gh-118229\n* gh-118472\n* gh-118479\n\u003c!-- /gh-linked-prs --\u003e\r\n","author":{"url":"https://github.com/jstasiak","@type":"Person","name":"jstasiak"},"datePublished":"2023-12-15T13:58:56.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/113171/cpython/issues/113171"}