Constant PORT_FORWARD_MAX_MESSAGE_SIZE 

const PORT_FORWARD_MAX_MESSAGE_SIZE: usize = _; // 1_048_576usize

The largest WebSocket message and frame a client of port forwarding may send. A single message must not carry more than a connection takes while it gets established, the CONNECT_BUFFER of port_forward, nor all that the ports of a WebSocket hold together, its CHANNEL_BUFFER. A client which sends more gets the WebSocket closed with a code which tells why.