Thank you Norman,
That was the first thing I did, however HexDumpProxy doesn't use
ChannelDuplexHandler , HexDumpProxyFrontendHandler extends
ChannelInboundHandlerAdapter
and so does the HexDumpProxyBackendHandler. In addition, the socksProxy
classes doesn't utilize channelDuplexHandler. I do see the functionality I
was aiming for, however I could not find any examples of how to utilize the
ChannelDuplexHandler.
But, Again, I appreciate your response
On Tuesday, September 6, 2016 at 12:59:22 PM UTC-4, L_DisplayName wrote:
>
> Greetings All,
> I wanted to know how I can use ChannelDuplexHandler from a server to
> connect to another server? Also I would like to know if my understanding of
> channelDuplex handler is correct and what's the difference between
> bootstrapping a client and having it connect to a server verses having the
> ChannelDuplexHandler connect to the server?
>
> For example: If I have a *client A*, a *Server B *and a *Server C*.
> and I want *client A* to connect to *Server B* and *Server B *connect to
> *Server
> C. *where pictorially* I have:*
> * A-->B-->C *
>
> *Below I show Server's B Handler code, as soon as client A connects to
> Server B (The code for this is below B's Server Handler code), I want
> Server B to connect to Server C, can you tell me if the code below is
> correct or if any thing needs to be changed and if so what and how? Thank
> you!*
>
> *Attempting to connect Server B to Server C using ChannelDuplexHandler
> (Note I am showing Server B's handler class)*
> public class Server_B_Handler extends ChannelDuplexHandler {
>
> private String ipAddressToConnectTo, localIpAddress;
> private int portToConnectTo, localPort;
> private Logger logger;
> private ChannelHandlerContext ctx;
> private Channel channelFrom_A_to_B;
> private Channel channelFrom_B_to_C;
>
> public Server_B_Handler(String ipAddress, int port, localIpAddress,
> localPort) {
> ipAddressToConnectTo = ipAddress;
> portToConnectTo = port
> this.localIpAddress = localIpAddress;
> this.localPort = localPort;
> logger = Logger.getLogger(this.getClass().getName());
> this.ctx = null;
> channelFrom_A_to_B = null; //Inbound channel
> channelFrom_B_to_C = null; //Outbound Channel
>
> }
>
> @Override
> public void channelActive(ChannelHandlerContext ctx) throws Exception{
> //THIS CTX (Channel context) is for the channel connecting Client A to
> this Server (Server B)
> //Please see below for code connecting client A to Server B
> this.ctx = ctx;
> channelFrom_A_to_B = this.ctx().channel();
>
> //QUESTION HOW CAN I CONNECT TO SERVER C using this server's CONNECT
> METHOD?
>
> final Promise<Channel> myPromise = this.ctx.executor().newPromise();
> ctx.connect(new InetSocketAddress(InetAddress.getByName(
> ipAddressToConnectTo), portToConnectTo),new InetSocketAddress(this.
> localIpAddress,this.localPort),myPromise);
> myPromise.addListener(new FutureListener<Channel>(){
> @override
> public void operationComplete(final Future<Channel> future) throws
> Exception {
> if (future.isSuccess()){
> //Connection attempt successful
> channelFrom_B_to_C = future.get();
> logger.info("Server B successfully connected to Server C")
> }
> else {
> //Connection attempt was not successful
> channelFrom_B_to_C = future.get().close();
> logger.info("Server B did not successfully connect to Server C.
> closing...")
> }
> });
>
> }
>
>
> @Override
> public void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws
> Exception {
> //What ever the inbound channel (channelFrom_A_to_B) reads write it to
> the outbound channel
> if ( channelFrom_B_to_C.isActive()){
> channelFrom_B_to_C.write(msg);
> }
> }
>
> @Override
> public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
> cause.printStackTrace();
>
> if (ctx.channel().isActive()) {
> ctx.writeAndFlush("ERR: " +
> cause.getClass().getSimpleName() + ": " +
> cause.getMessage() + '\n').addListener(ChannelFutureListener.CLOSE);
> }
> }
> }
>
>
>
> *I know I can connect Client A to Client B by the following code*
>
> public final class Client_A {
>
> static final boolean SSL = System.getProperty("ssl") != null;
> static final int SIZE = Integer.parseInt(System.getProperty("size", "256"));
> static final String HOST = System.getProperty("host", "129.456.7.9");
> static final int PORT = Integer.parseInt(System.getProperty("port","4959"));
>
> public static void main(String[] args) throws Exception {
> final SslContext sslCtx;
> if (SSL) {
> sslCtx = SslContextBuilder.forClient()
> .trustManager(InsecureTrustManagerFactory.INSTANCE).build();
> } else {
> sslCtx = null;
> }
>
> // Configure the client.
> EventLoopGroup group = new NioEventLoopGroup();
> try {
> Bootstrap b = new Bootstrap();
> b.group(group)
> .channel(NioSocketChannel.class)
> .option(ChannelOption.TCP_NODELAY, true)
> .handler(new ChannelInitializer<SocketChannel>() {
> @Override
> public void initChannel(SocketChannel ch) throws Exception {
> ChannelPipeline p = ch.pipeline();
> if (sslCtx != null) {
> p.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));
> }
> //p.addLast(new LoggingHandler(LogLevel.INFO));
> p.addLast(
> new LengthFieldBasedFrameDecoder(1024*1024*128, 0, 8, 0, 8),
> new Client_A_Handler());
> }
> });
>
> // Start the client.
> ChannelFuture f = b.connect(HOST, PORT).sync();
>
> // Wait until the connection is closed.
> f.channel().closeFuture().sync();
> } finally {
> // Shut down the event loop to terminate all threads.
> group.shutdownGracefully();
> }
> }
> }
>
>
>
>
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