RefreshPorts code path doesn't really make sense

[williammartin]

Description

Someone shared this error log for gh cs ssh (used to connect to GitHub codespaces over ssh):

kex_exchange_identification: read: Connection reset by peer
Connection reset by 127.0.0.1 port 65225
tunnel closed: error forwarding port: refresh ports failed: failed to refresh ports: %!w(<nil>)

Looking at the code where this error is returned, there doesn't appear to be any case in which the error will be non-nil:

dev-tunnels/go/tunnels/client.go

Lines 210 to 219 in 845d75c

	res, _, err := c.ssh.SendSessionRequest("RefreshPorts", true, make([]byte, 0))
	if err != nil {
	return fmt.Errorf("failed to send port refresh message: %w", err)
	}
	if !res {
	return fmt.Errorf("failed to refresh ports: %w", err)
	}
	return err
	}

I have no opinion on what the message should say. Happy to open a PR with your recommendation.

---

Separately, as a minor nit reading this code, it seems like it would be better for the final return on this method to be return nil, since again, no other value is possible.

[williammartin]

In looking at the SSH spec, a false boolean return seems to be an occurrence of the server sending SSH_MSG_REQUEST_FAILURE, which happens when "If the recipient does not recognize or support the request"

https://datatracker.ietf.org/doc/html/rfc4254#section-9

So I suspect this should really say something like:

 	if !res { 
 		return errors.New("failed to refresh ports: server did not recognise or support the request") 
 	}