List more private and link-local IP networks (#74064)

List more private and link-local IP networks

The IPv6 link-local network is especially important as without it
local accounts don't work on IPv6-capable networks with no IPv6 DHCP
server.

homeassistant/util/network.py

@@ -14,14 +14,21 @@ LOOPBACK_NETWORKS = (
 
 # RFC6890 - Address allocation for Private Internets
 PRIVATE_NETWORKS = (
-    ip_network("fd00::/8"),
     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_NETWORK = ip_network("169.254.0.0/16")
+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:
@@ -30,18 +37,18 @@ def is_loopback(address: IPv4Address | IPv6Address) -> bool:
 
 
 def is_private(address: IPv4Address | IPv6Address) -> bool:
-    """Check if an address is a private address."""
+    """Check if an address is a unique local non-loopback address."""
     return any(address in network for network in PRIVATE_NETWORKS)
 
 
 def is_link_local(address: IPv4Address | IPv6Address) -> bool:
-    """Check if an address is link local."""
-    return address in LINK_LOCAL_NETWORK
+    """Check if an address is link-local (local but not necessarily unique)."""
+    return any(address in network for network in LINK_LOCAL_NETWORKS)
 
 
 def is_local(address: IPv4Address | IPv6Address) -> bool:
-    """Check if an address is loopback or private."""
-    return is_loopback(address) or is_private(address)
+    """Check if an address is on a local network."""
+    return is_loopback(address) or is_private(address) or is_link_local(address)
 
 
 def is_invalid(address: IPv4Address | IPv6Address) -> bool:

tests/util/test_network.py

@@ -30,7 +30,9 @@ def test_is_private():
 def test_is_link_local():
     """Test link local addresses."""
     assert network_util.is_link_local(ip_address("169.254.12.3"))
+    assert network_util.is_link_local(ip_address("fe80::1234:5678:abcd"))
     assert not network_util.is_link_local(ip_address("127.0.0.1"))
+    assert not network_util.is_link_local(ip_address("::1"))
 
 
 def test_is_invalid():
@@ -43,7 +45,13 @@ def test_is_local():
     """Test local addresses."""
     assert network_util.is_local(ip_address("192.168.0.1"))
     assert network_util.is_local(ip_address("127.0.0.1"))
+    assert network_util.is_local(ip_address("fd12:3456:789a:1::1"))
+    assert network_util.is_local(ip_address("fe80::1234:5678:abcd"))
+    assert network_util.is_local(ip_address("::ffff:192.168.0.1"))
     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"))
 
 
 def test_is_ip_address():