Patched code sample

from typing import Any, List, Optional, Tuple

from aiohttp.http_exceptions import HttpBadRequest, HttpUpgrade


# A mock message object to represent an HTTP request.
class _MockMessage:
    content_length: Optional[int] = 128


# Simplified representation of aiohttp's HttpRequestParser
class HttpRequestParser:
    def __init__(self) -> None:
        # A request message is built during parsing.
        # We simulate a message with a body for a WebSocket upgrade request.
        self._message: Optional[_MockMessage] = _MockMessage()

    def feed_data(self, data: bytes) -> Tuple[List[Any], bool, bytes]:
        try:
            # This simulates a low-level parser raising HttpUpgrade
            # when a WebSocket handshake is detected.
            raise HttpUpgrade(payload=data)
        except HttpUpgrade as exc:
            # FIX: Reject WebSocket upgrade requests that contain a body.
            if (
                self._message is not None
                and self._message.content_length is not None
                and self._message.content_length > 0
            ):
                raise HttpBadRequest("WebSocket upgrade request with body") from exc

            return [self._message], True, exc.payload

        return [], False, b""