Refusing connection

[ecoshub]

Hi @thinkgos Thank you for this project it is working great so far.

I am wondering if there is a way to refuse a connection from server.

I have a server and multiple clients, can I limit the connect to server?.

I have try to close "UnderlyingConn()" but clients keep trying connect with attempt.

Do you have any other idea, maybe sending an ASDU like StopDT from server?

[thinkgos]

If add a return error on OnConnectHandler api?? if return error, indicate refuse the connection from server?? It seem like a idea.

[ecoshub]

OnConnectionHandler does not implement a return error statement. Do you mean should I implement the return error statement to the source code ?

// SetOnConnectionHandler set on connect handler
func (sf *Server) SetOnConnectionHandler(f func(asdu.Connect)) {
	sf.onConnection = f
}

if I refuse connections by closing them client is attempting in a infinite loop.

mainServer = cs104.NewServer(&myServer{})
mainServer.SetOnConnectionHandler(func(asd asdu.Connect){
	asd.UnderlyingConn().Close()
})

[thinkgos]

@ecoshub YES,OnConnectionHandler should implement a return error statement to the source code.

// SetOnConnectionHandler set on connect handler
func (sf *Server) SetOnConnectionHandler(f func(asdu.Connect) error ) {
	sf.onConnection = f
}

in the file server_session.go line 206 - 218

	defer func() {
		sf.setConnectStatus(disconnected)
		checkTicker.Stop()
		_ = sf.conn.Close() // 连锁引发cancel
		sf.wg.Wait()
		if sf.connectionLost != nil {
			sf.connectionLost(sf)
		}
		sf.Debug("run stopped!")
	}()

       if err := sf.onConnection(sf);err!= nil{
           return
      }

we can not forbid the client attempting in a infinite loop. only we can do, just refuse it.

what about this idea?

[ecoshub]

Yes I am currently doing that without implementing any other code to the source code. I am just closing the connection with asdu.UnderlyingConn().Close(). That is not the case.

Let me rephrase the question. Does iec 60870-5 104 protocol has any ASDU command for closing the connection from server like client do with StopDT and does this package has any thing like that?

[thinkgos]

sorry ,I can not find. you can refer to lib60870 c library lib60870 doc, maybe you can get an idea.

[ecoshub]

Thank you so much for your help I will read doc again for an answer. If there is no answer for my question in the doc I will try to find out a solution and post it from here.