close websocket properly even on error

[crotwell]

If a websocket datalink client sends a command that results in an error, a ERROR datalink packet is sent back with a reason, which is helpful. But the ringserver also closes the connection without going through the websocket close handshake, ie sending a CLOSE frame and waiting for the corresponding CLOSE response.

In clients.c about line 404 there is code to close the regular socket:

  /* Close client socket */
  if (cinfo->socket)
  {
    shutdown (cinfo->socket, SHUT_RDWR);
    close (cinfo->socket);
    cinfo->socket = 0;
  }

but as far as I can see no corresponding code to close a websocket nicely. It would be nice if the websocket could be closed gracefully even in the case of errors.

Docs on CLOSE are here:
https://www.rfc-editor.org/rfc/rfc6455#section-5.5.1

[crotwell]

This also occurs on when ringserver does an idle close.

ringserver logs:

Wed Aug 14 12:49:11 2024 - Closing idle client connection: localhost
Wed Aug 14 12:49:11 2024 - Client disconnected: localhost

but my python websocket client shows exception:

  File "/Users/crotwell/Code/seis/simpledali/src/simpledali/websocketdali.py", line 67, in parseResponse
    response = await self.ws.recv()
  File "/opt/homebrew/Caskroom/miniforge/base/envs/simpledali_dev/lib/python3.10/site-packages/websockets/legacy/protocol.py", line 568, in recv
    await self.ensure_open()
  File "/opt/homebrew/Caskroom/miniforge/base/envs/simpledali_dev/lib/python3.10/site-packages/websockets/legacy/protocol.py", line 939, in ensure_open
    raise self.connection_closed_exc()
websockets.exceptions.ConnectionClosedError: no close frame received or sent