From 48b15583305e692ce997ec6f5a6a2f88f23ace71 Mon Sep 17 00:00:00 2001
From: Sam Bull <git@sambull.org>
Date: Sun, 26 Nov 2023 14:33:50 +0000
Subject: [PATCH] Fix regression with connection upgrade (#7879)

Fixes #7867.
---
 CHANGES/7879.bugfix             |  1 +
 aiohttp/client_reqrep.py        | 19 ++++++++-----------
 aiohttp/connector.py            |  4 ++++
 tests/test_client_functional.py | 19 +++++++++++++++++++
 4 files changed, 32 insertions(+), 11 deletions(-)
 create mode 100644 CHANGES/7879.bugfix

diff --git a/CHANGES/7879.bugfix b/CHANGES/7879.bugfix
new file mode 100644
index 00000000000..08baf85be42
--- /dev/null
+++ b/CHANGES/7879.bugfix
@@ -0,0 +1 @@
+Fixed a regression where connection may get closed during upgrade. -- by :user:`Dreamsorcerer`
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 21858fc345a..2185aa85738 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -940,19 +940,14 @@ def _response_eof(self) -> None:
         if self._closed:
             return
 
-        if self._connection is not None:
-            # websocket, protocol could be None because
-            # connection could be detached
-            if (
-                self._connection.protocol is not None
-                and self._connection.protocol.upgraded
-            ):
-                return
-
-            self._release_connection()
+        # protocol could be None because connection could be detached
+        protocol = self._connection and self._connection.protocol
+        if protocol is not None and protocol.upgraded:
+            return
 
         self._closed = True
         self._cleanup_writer()
+        self._release_connection()
 
     @property
     def closed(self) -> bool:
@@ -1048,7 +1043,9 @@ async def read(self) -> bytes:
         elif self._released:  # Response explicitly released
             raise ClientConnectionError("Connection closed")
 
-        await self._wait_released()  # Underlying connection released
+        protocol = self._connection and self._connection.protocol
+        if protocol is None or not protocol.upgraded:
+            await self._wait_released()  # Underlying connection released
         return self._body
 
     def get_encoding(self) -> str:
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index 2460ca46705..295882f65ca 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -107,6 +107,10 @@ def __del__(self, _warnings: Any = warnings) -> None:
                 context["source_traceback"] = self._source_traceback
             self._loop.call_exception_handler(context)
 
+    def __bool__(self) -> Literal[True]:
+        """Force subclasses to not be falsy, to make checks simpler."""
+        return True
+
     @property
     def transport(self) -> Optional[asyncio.Transport]:
         if self._protocol is None:
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index 4f0d594cb1f..66af22b4494 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -174,6 +174,25 @@ async def handler(request):
     assert 1 == len(client._session.connector._conns)
 
 
+async def test_upgrade_connection_not_released_after_read(aiohttp_client: Any) -> None:
+    async def handler(request: web.Request) -> web.Response:
+        body = await request.read()
+        assert b"" == body
+        return web.Response(
+            status=101, headers={"Connection": "Upgrade", "Upgrade": "tcp"}
+        )
+
+    app = web.Application()
+    app.router.add_route("GET", "/", handler)
+
+    client = await aiohttp_client(app)
+
+    resp = await client.get("/")
+    await resp.read()
+    assert resp.connection is not None
+    assert not resp.closed
+
+
 async def test_keepalive_server_force_close_connection(aiohttp_client: Any) -> None:
     async def handler(request):
         body = await request.read()