def _translate_webserver_error(self, ex):
s = str(ex)
# NOTE(kgriffs): uvicorn or any other server using the "websockets"
# package that allows exceptions to bubble up
if 'code = 1000 (OK)' in s:
return errors.WebSocketDisconnected(WSCloseCode.NORMAL)
# NOTE(kgriffs): Autobahn (used by Daphne) raises a generic exception
# with this message
if 'protocol accepted must be from the list' in s:
return ValueError('WebSocket subprotocol must be from the list sent by the client')
return None
def _require_accepted(self):
if self._state == _WebSocketState.ACCEPTED:
return
if self._state in {_WebSocketState.CONNECT, _WebSocketState.HANDSHAKE}:
raise falcon_errors.OperationNotAllowed(
'WebSocket connection has not yet been accepted'
)
elif self._state == _WebSocketState.CLOSED:
raise falcon_errors.WebSocketDisconnected(self._close_code)
assert self._state == _WebSocketState.DENIED
if self._close_code == WSCloseCode.PATH_NOT_FOUND:
raise falcon_errors.WebSocketPathNotFound(WSCloseCode.PATH_NOT_FOUND)
if self._close_code == WSCloseCode.SERVER_ERROR:
raise falcon_errors.WebSocketServerError(WSCloseCode.SERVER_ERROR)
if self._close_code == WSCloseCode.HANDLER_NOT_FOUND:
raise falcon_errors.WebSocketHandlerNotFound(WSCloseCode.HANDLER_NOT_FOUND)
raise falcon_errors.WebSocketDisconnected(self._close_code)
async def _receive(self) -> dict:
event = await self._asgi_receive()
event_type = event['type']
if event_type != EventType.WS_RECEIVE:
# NOTE(kgriffs): Based on the ASGI spec, there are no other
# event types that should be emitted by the protocol server,
# but we sanity-check it here just in case.
assert event_type == EventType.WS_DISCONNECT
self._state = _WebSocketState.CLOSED
self._close_code = event.get('code', WSCloseCode.NORMAL)
raise errors.WebSocketDisconnected(self._close_code)
return event
async def _send(self, msg: dict):
if self._buffered_receiver.client_disconnected:
self._state = _WebSocketState.CLOSED
self._close_code = self._buffered_receiver.client_disconnected_code
raise errors.WebSocketDisconnected(self._close_code)
try:
await self._asgi_send(msg)
except Exception as ex:
# NOTE(kgriffs): If uvicorn (or any other server that uses the
# the "websockets" library) allows exceptions to bubble up,
# we will have an error raised on client disconnect.
#
# Daphne, on the other hand, does not raise an error but just
# eats the message. This approach is actually more in keeping
# with the ASGI spec, but poses its own challenges.
translated_ex = self._translate_webserver_error(ex)
if translated_ex:
raise translated_ex
# NOTE(kgriffs): Re-raise other errors directly so that we don't
# obscure the traceback.
raise
def _require_accepted(self):
if self._state == _WebSocketState.HANDSHAKE:
raise errors.OperationNotAllowed(
'WebSocket connection has not yet been accepted')
elif self._state == _WebSocketState.CLOSED:
raise errors.WebSocketDisconnected(self._close_code)