type sender interface {
	msgp.MarshalSizer
	Op() Op
}

type connectReq struct {
	ID    [16]byte
	Host  string
	Time  time.Time
	Token string
}

// addToken will add the token to the connect request.
func (c *connectReq) addToken(fn AuthFn) {
	c.Token = fn()
}

func (connectReq) Op() Op {
	return OpConnect
}

type connectResp struct {
	ID             [16]byte
	Accepted       bool

			retry(err)
			continue
		}
		// Send connect message.
		m := message{
			Op: OpConnect,
		}
		req := connectReq{
			Host: c.Local,
			ID:   c.id,
			Time: time.Now(),
		}
		req.addToken(c.authFn)
		err = c.sendMsg(conn, m, &req)
		if err != nil {
			retry(err)
			continue
		}
		// Wait for response
		var r connectResp
		err = c.receive(conn, &r)
		if err != nil {