How to end session in middleware when using MiddlewareWithProgramHandler()

[eltsu7]

I'm making a game where multiple people can log in. I'm ssh.User() as username ingame, and I want to prevent multiple people logging in with the same name. The program would have to deny the second login attempt. This is my code now, can I do it in that block with // END SESSION HERE ?

func gameProgramHandler(s ssh.Session) *tea.Program {
	if _, _, active := s.Pty(); !active {
		wish.Fatalln(s, "terminal is not active")
	}

	for _, p := range loggedInPlayers {
		if p.name == s.User() {
			// END SESSION HERE
		}
	}

	model := LoginModel{
		name:      s.User(),
		publicKey: s.PublicKey(),
	}

	p := tea.NewProgram(model, tea.WithOutput(s), tea.WithInput(s), tea.WithAltScreen())

	loggedInPlayers = append(loggedInPlayers, struct {
		name    string
		program *tea.Program
	}{
		name: s.User(), program: p,
	})

	return p
}

func gameMiddleware() wish.Middleware {
	return bm.MiddlewareWithProgramHandler(gameProgramHandler, termenv.ANSI256)
}

...

func main() {
	if len(os.Args) > 1 {
		host = "0.0.0.0"
	}
	log.SetLevel(log.DebugLevel)

	s, err := wish.NewServer(
		wish.WithAddress(fmt.Sprintf("%s:%d", host, port)),
		wish.WithHostKeyPath(".ssh/term_info_ed25519"),
		wish.WithPublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
			return true
		}),
		wish.WithMiddleware(
			gameMiddleware(),
			disconnectPlayerMiddleware(),
			logging.Middleware(),
		),
	)

	if err != nil {
		log.Error("could not start server", "error", err)
	}

	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	log.Infof("Starting SSH server on %s:%d", host, port)
	go func() {
		if err = s.ListenAndServe(); err != nil {
			log.Error(err)
		}
	}()

	<-done
	log.Info("Stopping SSH server")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer func() { cancel() }()
	if err := s.Shutdown(ctx); err != nil {
		log.Error(err)
	}
}

[caarlos0]

if you want the session to exit 0, probably the easiest way would be to create a userAlreadyPlayingModel and return a program that runs that instead.

that model would in turn defer tea.Quit and/or print a message to the user while doing so.

on the other hand, if it's ok for the user to see an error exit code on their side, you can quit with wish.Fatal.*