the websocket tunnel helper accepts control commands (encoded as
single-line JSON) on stdin, and prints responses on stdout.
the following commands are available:
- "connect" a 'control' tunnel via a websocket
- "forward" a local unix socket to a remote socket via a websocket
-- if requested, this will ask for a ticket via the control tunnel after
accepting a new connection on the unix socket
- "close" the control tunnel and any forwarded socket
any other json input (without the 'control' flag set) is forwarded as-is
to the remote end of the control tunnel.
internally, the tunnel helper will spawn tokio tasks for
- handling the control tunnel connection (new commands are passed in via
an mpsc channel together with a oneshot channel for the response)
- handling accepting new connections on each forwarded unix socket
- handling forwarding data over accepted forwarded connections