[PR #9032/c693a816 backport][3.11] Fix Link-Local IPv6 Flags in the R…

…esolver (#9047)

Co-authored-by: GitNMLee <89409038+GitNMLee@users.noreply.github.com>
Fixes #9028 
Fixes #123'). -->

CHANGES/9032.bugfix.rst

@@ -0,0 +1,3 @@
+Fixed the incorrect use of flags for ``getnameinfo()`` in the Resolver --by :user:`GitNMLee`
+
+Link-Local IPv6 addresses can now be handled by the Resolver correctly.

aiohttp/resolver.py

@@ -17,6 +17,7 @@
 
 
 _NUMERIC_SOCKET_FLAGS = socket.AI_NUMERICHOST | socket.AI_NUMERICSERV
+_NAME_SOCKET_FLAGS = socket.NI_NUMERICHOST | socket.NI_NUMERICSERV
 
 
 class ThreadedResolver(AbstractResolver):
@@ -52,7 +53,7 @@ async def resolve(
                     # LL IPv6 is a VERY rare case. Strictly speaking, we should use
                     # getnameinfo() unconditionally, but performance makes sense.
                     resolved_host, _port = await self._loop.getnameinfo(
-                        address, _NUMERIC_SOCKET_FLAGS
+                        address, _NAME_SOCKET_FLAGS
                     )
                     port = int(_port)
                 else:
@@ -120,7 +121,7 @@ async def resolve(
                     # getnameinfo() unconditionally, but performance makes sense.
                     result = await self._resolver.getnameinfo(
                         (address[0].decode("ascii"), *address[1:]),
-                        _NUMERIC_SOCKET_FLAGS,
+                        _NAME_SOCKET_FLAGS,
                     )
                     resolved_host = result.node
                 else:

tests/test_resolver.py

@@ -3,12 +3,12 @@
 import socket
 from ipaddress import ip_address
 from typing import Any, Awaitable, Callable, Collection, List, NamedTuple, Tuple, Union
-from unittest.mock import Mock, patch
+from unittest.mock import Mock, create_autospec, patch
 
 import pytest
 
 from aiohttp.resolver import (
-    _NUMERIC_SOCKET_FLAGS,
+    _NAME_SOCKET_FLAGS,
     AsyncResolver,
     DefaultResolver,
     ThreadedResolver,
@@ -153,9 +153,7 @@ async def test_async_resolver_positive_link_local_ipv6_lookup(loop: Any) -> None
             port=0,
             type=socket.SOCK_STREAM,
         )
-        mock().getnameinfo.assert_called_with(
-            ("fe80::1", 0, 0, 3), _NUMERIC_SOCKET_FLAGS
-        )
+        mock().getnameinfo.assert_called_with(("fe80::1", 0, 0, 3), _NAME_SOCKET_FLAGS)
 
 
 @pytest.mark.skipif(not getaddrinfo, reason="aiodns >=3.2.0 required")
@@ -211,12 +209,31 @@ async def test_threaded_resolver_positive_ipv6_link_local_lookup() -> None:
     loop = Mock()
     loop.getaddrinfo = fake_ipv6_addrinfo(["fe80::1"])
     loop.getnameinfo = fake_ipv6_nameinfo("fe80::1%eth0")
+
+    # Mock the fake function that was returned by helper functions
+    loop.getaddrinfo = create_autospec(loop.getaddrinfo)
+    loop.getnameinfo = create_autospec(loop.getnameinfo)
+
+    # Set the correct return values for mock functions
+    loop.getaddrinfo.return_value = await fake_ipv6_addrinfo(["fe80::1"])()
+    loop.getnameinfo.return_value = await fake_ipv6_nameinfo("fe80::1%eth0")()
+
     resolver = ThreadedResolver()
     resolver._loop = loop
     real = await resolver.resolve("www.python.org")
     assert real[0]["hostname"] == "www.python.org"
     ipaddress.ip_address(real[0]["host"])
 
+    loop.getaddrinfo.assert_called_with(
+        "www.python.org",
+        0,
+        type=socket.SOCK_STREAM,
+        family=socket.AF_INET,
+        flags=socket.AI_ADDRCONFIG,
+    )
+
+    loop.getnameinfo.assert_called_with(("fe80::1", 0, 0, 3), _NAME_SOCKET_FLAGS)
+
 
 async def test_threaded_resolver_multiple_replies() -> None:
     loop = Mock()