util/network: cleanup, further alignment with stdlib

* Remove the constants LINK_LOCAL_NETWORKS and LOOPBACK_NETWORKS, as
  they are currently unreferenced, due to the changes made by PR#102019.

* Replace the PRIVATE_NETWORKS check with stdlib's is_private() method.
  Besides a reduction of code, this results in a more comprehensive
  check, as stdlib includes additional address spaces that were not
  covered before, and is ever evolving (see, for example,
  python/cpython#113179).

* In contrast with CPython, loopbacks and link-locals are NOT included
  in our definition of "private", so adjust the code to keep the
  existing semantics

* However, this *does* change the semantics for some address spaces to
  follow Python's interpretation of IANA, such as marking reserved
  documentation spaces as "local". Invert the test cases for
  198.51.100.0/24 (TEST-NET-2) and 2001:db8::/32 (Documentation)
  accordingly.

* We now need a new globally reachable IP space to use as
  EXTERNAL_ADDRESSES in test_auth. Use AS112's address space, as it is
  reserved by IANA, but marked as Globally Reachable.

* Finally, inline the last remaining constant IPV6_IPV4_LOOPBACK, and
  leave a comment that work is underway in CPython by yours truly to
  reduce the need for it and have is_loopback() subsume it.

Further work is required to align the semantics of e.g. what "private"
means with stdlib, and replace these seldomly used util functions with
stdlib properties across the tree (as is already the case in several
integrations), but hopefully this provides a stepping stone towards this
direction.

Author: paravoid

homeassistant/util/network.py

@@ -7,42 +7,16 @@
 
 import yarl
 
-# RFC6890 - IP addresses of loopback interfaces
-IPV6_IPV4_LOOPBACK = ip_network("::ffff:127.0.0.0/104")
-
-LOOPBACK_NETWORKS = (
-    ip_network("127.0.0.0/8"),
-    ip_network("::1/128"),
-    IPV6_IPV4_LOOPBACK,
-)
-
-# RFC6890 - Address allocation for Private Internets
-PRIVATE_NETWORKS = (
-    ip_network("10.0.0.0/8"),
-    ip_network("172.16.0.0/12"),
-    ip_network("192.168.0.0/16"),
-    ip_network("fd00::/8"),
-    ip_network("::ffff:10.0.0.0/104"),
-    ip_network("::ffff:172.16.0.0/108"),
-    ip_network("::ffff:192.168.0.0/112"),
-)
-
-# RFC6890 - Link local ranges
-LINK_LOCAL_NETWORKS = (
-    ip_network("169.254.0.0/16"),
-    ip_network("fe80::/10"),
-    ip_network("::ffff:169.254.0.0/112"),
-)
-
 
 def is_loopback(address: IPv4Address | IPv6Address) -> bool:
     """Check if an address is a loopback address."""
-    return address.is_loopback or address in IPV6_IPV4_LOOPBACK
+    # the ::ffff: check is a workaround for python/cpython#117566
+    return address.is_loopback or address in ip_network("::ffff:127.0.0.0/104")
 
 
 def is_private(address: IPv4Address | IPv6Address) -> bool:
     """Check if an address is a unique local non-loopback address."""
-    return any(address in network for network in PRIVATE_NETWORKS)
+    return address.is_private and not is_loopback(address) and not address.is_link_local
 
 
 def is_link_local(address: IPv4Address | IPv6Address) -> bool:

tests/components/http/test_auth.py

@@ -53,7 +53,7 @@
     ip_network("FD01:DB8::1"),
 ]
 TRUSTED_ADDRESSES = ["100.64.0.1", "192.0.2.100", "FD01:DB8::1", "2001:DB8:ABCD::1"]
-EXTERNAL_ADDRESSES = ["198.51.100.1", "2001:DB8:FA1::1"]
+EXTERNAL_ADDRESSES = ["192.175.48.1", "2620:4f:8000::1"]
 UNTRUSTED_ADDRESSES = [*EXTERNAL_ADDRESSES, "127.0.0.1", "::1"]
 
 

tests/util/test_network.py

@@ -43,14 +43,26 @@ def test_is_invalid() -> None:
 
 def test_is_local() -> None:
     """Test local addresses."""
+    # RFC 1918 space
     assert network_util.is_local(ip_address("192.168.0.1"))
+    # loopback
     assert network_util.is_local(ip_address("127.0.0.1"))
+    assert network_util.is_local(ip_address("::ffff:127.0.0.1"))
+    assert network_util.is_local(ip_address("::1"))
+    # IPv6 ULA
     assert network_util.is_local(ip_address("fd12:3456:789a:1::1"))
+    # IPv6 link-local
     assert network_util.is_local(ip_address("fe80::1234:5678:abcd"))
+    # mapped ipv4-to-ipv6
     assert network_util.is_local(ip_address("::ffff:192.168.0.1"))
+    # Documentation/TEST-NET2 IP space, marked as Globally Reachable: False by IANA
+    assert network_util.is_local(ip_address("198.51.100.1"))
+    assert network_util.is_local(ip_address("2001:DB8:FA1::1"))
+    # AS112 space, marked as Globally Reachable: True by IANA
+    assert not network_util.is_local(ip_address("192.175.48.1"))
+    assert not network_util.is_local(ip_address("2620:4f:8000::1"))
+    # random globally routable IP space
     assert not network_util.is_local(ip_address("208.5.4.2"))
-    assert not network_util.is_local(ip_address("198.51.100.1"))
-    assert not network_util.is_local(ip_address("2001:DB8:FA1::1"))
     assert not network_util.is_local(ip_address("::ffff:208.5.4.2"))