Spring Integration - TCP SSL Support via DSL

[garyrussell]

Discussed in #4012

^{Originally posted by ppussar February 8, 2023}
Hi,

I am trying to implement a TCP Server, which does client certificate authentication on its connections. I added a TcpSocketSupport Bean as described in the documentation.

However I get a ClassCastException during the serverSocket cast, as it is still a ServerSocket and not a SSLServerSocket.

So I tryed (without success) to overwrite the TcpSocketFactorySupport Bean:

@Bean
    public TcpSocketSupport tcpSocketSupport(serverProperties serverProperties) {
        if (serverProperties.getSsl().isEnabled()) {
            return new DefaultTcpSocketSupport() {
                @Override
                public void postProcessServerSocket(ServerSocket serverSocket) {
                    ((SSLServerSocket) serverSocket).setNeedClientAuth(true);
                }
            };
        } else {
            return new DefaultTcpSocketSupport();
        }
    }

    @Bean
    public TcpSocketFactorySupport tcpSocketFactorySupport(
            ServerProperties serverProperties,
            TcpSSLContextSupport tcpSSLContextSupport) {

        if (serverProperties.getSsl().isEnabled()) {
            return new DefaultTcpNetSSLSocketFactorySupport(tcpSSLContextSupport);
        } else {
            return new DefaultTcpNetSocketFactorySupport();
        }
    }

But it has no effect. I guess it is not working as I am using the DSL syntax, which does not support SSL?:

IntegrationFlow.from(Tcp.inboundGateway(
                                Tcp.netServer(serverPort)
                                        .tcpSocketSupport(tcpSocketSupport)
                                        .deserializer(mySerde)
                                        .serializer(mySerde)
                                        .soTimeout(Integer.MAX_VALUE)
                                        .singleUseConnections(false)
                                        .mapper(tcpMessageMapper))
                        .id(TCP_GATEWAY_ID)
                        .errorChannel(ERROR_CHANNEL_NAME)
                        .replyChannel(REPLY_CHANNEL_NAME))

Is there a way to set the tcpSocketFactorySupport to DefaultTcpNetSSLSocketFactorySupport via DSL?