Support Websocket Denial Response

[CaselIT]

This is an extension that allows sending a custom http response over websocket, to deny the upgrade from http to websocket. It's defined here: https://asgi.readthedocs.io/en/latest/extensions.html#websocket-denial-response

It can be sent only before accepting a websocket connection.

The api could be something like

class WebSocket:
  ...

  async def deny(self,
    status, *, headers=None, body: bytes|str=None
  ) -> None: ...

Not sure if it makes sense allowing media here, since websocket has no concept of mime type etc, so it's likely fine to just require that the body is already serialized

as for supporting asgi framework, uvicorn does support it https://www.uvicorn.org/release-notes/#added_8

[vytas7]

Maybe an MVP could be to add support for this thing in the error handling, so that HTTP errors would be serialized using the correct code and headers. We would probably still need a synthetic resp object though 🤔

[CaselIT]

We would probably still need a synthetic resp object though

I don't follow why we would need that? deny() would be similar to close() as it's a use once method

[vytas7]

I meant that ideally we would like to automatically handle this for HTTPError and HTTPStatus, then we might need a resp (but it is easy to create one). A simple deny() does not need it indeed.