Don't rearm WebSocket heartbeat after close

CHANGES/14125.bugfix.rst

@@ -0,0 +1,5 @@
+Stopped the server WebSocket heartbeat from being rearmed after close:
+peer-close data arriving after the close handshake scheduled a deferred
+heartbeat reset that re-created the heartbeat timer on the closed connection.
+The deferred reset is now dropped when the connection is closing or closed --
+by :user:`rinopatrick`.

CHANGES/14236.bugfix.rst

@@ -0,0 +1 @@
+14125.bugfix.rst

aiohttp/web_ws.py

@@ -70,7 +70,6 @@ def __bool__(self) -> bool:
 
 
 class WebSocketResponse(StreamResponse, Generic[_DecodeText]):
-
     _length_check: bool = False
     _ws_protocol: str | None = None
     _writer: WebSocketWriter | None = None
@@ -153,12 +152,20 @@ def _flush_heartbeat_reset(self) -> None:
         self._heartbeat_reset_handle = None
         if not self._need_heartbeat_reset:
             return
+        if self._closed or self._closing:
+            # The connection closed while the reset was deferred (e.g. the
+            # peer close frame arrived after the close handshake). Do not
+            # re-arm the heartbeat on a dead connection (see #14125).
+            self._need_heartbeat_reset = False
+            return
         self._reset_heartbeat()
         self._need_heartbeat_reset = False
 
     def _reset_heartbeat(self) -> None:
         if self._heartbeat is None:
             return
+        if self._closed or self._closing:
+            return
         self._cancel_pong_response_cb()
         req = self._req
         timeout_ceil_threshold = (

tests/test_web_websocket.py

@@ -143,6 +143,22 @@ async def test_flush_heartbeat_reset_returns_early_when_not_needed() -> None:
         reset.assert_not_called()
 
 
+async def test_flush_heartbeat_reset_does_not_rearm_after_close() -> None:
+    # Peer-close data arriving after the close handshake must not re-arm
+    # the heartbeat on the closed connection (see #14125).
+    ws = web.WebSocketResponse(heartbeat=10)
+    ws._loop = asyncio.get_running_loop()
+    ws._set_closed()
+
+    # data (e.g. the peer close frame) arrives after close
+    ws._on_data_received()
+    await asyncio.sleep(0)
+    await asyncio.sleep(0)
+
+    assert ws._heartbeat_cb is None
+    assert ws._need_heartbeat_reset is False
+
+
 async def test_send_heartbeat_returns_early_when_reset_is_pending() -> None:
     ws = web.WebSocketResponse(heartbeat=0.05)
     ws._need_heartbeat_reset = True