spring tcp socket , authorizing clients and handle pending response

Question

The Spring framework support tcp connection as well , i wrote code below to setup a simple socket server , i am confused about adding below futures to my socket server :

• authorizing clients based on a unique identifier ( for example a client secret received from client, maybe using TCP Connection Events )
• send a message directly to specific client (based on identifier)
• broadcast a message

UPDATE :

• Config.sendMessage added to send message to single client

• Config.broadCast added to broadcast message

• authorizeIncomingConnection to authorize clients , accept or reject connections

• tcpConnections static filed added to keep tcpEvent sources

Questions !

• is using tcpConnections HashMap good idea ?!

• is the authorization method i implemented a good one ?!

Main.java

@SpringBootApplication
public class Main {

    public static void main(final String[] args) {
        SpringApplication.run(Main.class, args);
    }

}

Config.java

@EnableIntegration
@IntegrationComponentScan
@Configuration
public class Config implements ApplicationListener<TcpConnectionEvent> {

    private static final Logger LOGGER = Logger.getLogger(Config.class.getName());

    @Bean
    public AbstractServerConnectionFactory AbstractServerConnectionFactory() {
        return new TcpNetServerConnectionFactory(8181);
    }

    @Bean
    public TcpInboundGateway TcpInboundGateway(AbstractServerConnectionFactory connectionFactory) {
        TcpInboundGateway inGate = new TcpInboundGateway();
        inGate.setConnectionFactory(connectionFactory);
        inGate.setRequestChannel(getMessageChannel());
        return inGate;
    }

    @Bean
    public MessageChannel getMessageChannel() {
        return new DirectChannel();
    }

    @MessageEndpoint
    public class Echo {

        @Transformer(inputChannel = "getMessageChannel")
        public String convert(byte[] bytes) throws Exception {
            return new String(bytes);
        }

    }

    private static ConcurrentHashMap<String, TcpConnection> tcpConnections = new ConcurrentHashMap<>();

    @Override
    public void onApplicationEvent(TcpConnectionEvent tcpEvent) {
        TcpConnection source = (TcpConnection) tcpEvent.getSource();
        if (tcpEvent instanceof TcpConnectionOpenEvent) {

            LOGGER.info("Socket Opened " + source.getConnectionId());
            tcpConnections.put(tcpEvent.getConnectionId(), source);

            if (!authorizeIncomingConnection(source.getSocketInfo())) {
                LOGGER.warn("Socket Rejected " + source.getConnectionId());
                source.close();
            }

        } else if (tcpEvent instanceof TcpConnectionCloseEvent) {
            LOGGER.info("Socket Closed " + source.getConnectionId());
            tcpConnections.remove(source.getConnectionId());
        }
    }

    private boolean authorizeIncomingConnection(SocketInfo socketInfo) {
        //Authorization Logic , Like Ip,Mac Address WhiteList or anyThing else !
        return (System.currentTimeMillis() / 1000) % 2 == 0;
    }

    public static String broadCast(String message) {
        Set<String> connectionIds = tcpConnections.keySet();
        int successCounter = 0;
        int FailureCounter = 0;
        for (String connectionId : connectionIds) {
            try {
                sendMessage(connectionId, message);
                successCounter++;
            } catch (Exception e) {
                FailureCounter++;
            }
        }
        return "BroadCast Result , Success : " + successCounter + " Failure : " + FailureCounter;
    }

    public static void sendMessage(String connectionId, final String message) throws Exception {
        tcpConnections.get(connectionId).send(new Message<String>() {
            @Override
            public String getPayload() {
                return message;
            }

            @Override
            public MessageHeaders getHeaders() {
                return null;
            }
        });
    }
}

MainController.java

@Controller
public class MainController {

    @RequestMapping("/notify/{connectionId}/{message}")
    @ResponseBody
    public String home(@PathVariable String connectionId, @PathVariable String message) {
        try {
            Config.sendMessage(connectionId, message);
            return "Client Notified !";
        } catch (Exception e) {
            return "Failed To Notify Client , cause : \n " + e.toString();
        }
    }


    @RequestMapping("/broadCast/{message}")
    @ResponseBody
    public String home(@PathVariable String message) {
        return Config.broadCast(message);
    }

}

Usage :

1. Socket Request/Response Mode

2. notify single client

   http://localhost:8080/notify/{connectionId}/{message}

3. broadCast

   http://localhost:8080/broadCast/{message}

Answer 1

The TcpConnectionOpenEvent contains a connectionId property. Each message coming from that client will have the same property in the IpHeaders.CONNECTION_ID message header.

1. Add a custom router that keeps track of the logged-on state of each connection.
2. Lookup the connection id and if not authenticated, route to a challenge/response subflow.
3. When authenticated, route to the normal flow.

To use arbitrary messaging (rather than request/response) use a TcpReceivingChannelAdapter and TcpSendingMessageHandler instead of an inbound gateway. Both configured to use the same connection factory. For each message sent to the message handler, add the IpHeaders.CONNECTION_ID header to target the specific client.

To broadcast, send a message for each connection id.