Obtaining Source IP address of Datagram packet UDP Netty 4.1

Question

I have set up a basic UDP server using netty 4.1 which works fine in reading data from the packets. I would like to add a feature to server to reply to the client upon receiving the UDP packet. What is the best way to go about doing this. I know UDP is a connection-less communication method, but you should be able to obtain the IP address and reply to the client?

My code is as follows;

public final class Server {

private static final int PORT = Integer.parseInt(System.getProperty("port", "6565"));

public static void runCommand () throws Exception {
    System.out.print("Server is started on port = "+PORT+"\n");
    EventLoopGroup group = new NioEventLoopGroup();
    try {
        Bootstrap b = new Bootstrap();
        b.group(group)
                .channel(NioDatagramChannel.class)
                .handler(new ServerHandler());

        b.bind(PORT).sync().channel().closeFuture().await();
    } finally {
        group.shutdownGracefully();
    }
}

}

public class ServerHandler extends SimpleChannelInboundHandler<DatagramPacket> {

@Override
public void channelRead0 (ChannelHandlerContext ctx, DatagramPacket packet) throws Exception {
    System.err.println ("Messaged received on " + new Date() + ":\r");
    System.err.println(packet.content().toString(CharsetUtil.UTF_8) + "\r\n");
}

@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
    ctx.flush();
}


@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
    cause.printStackTrace();
    ctx.close();
}

}

Could someone please point me in the right direction in how to obtain the source ip address? Many thanks in advance for your help

Answer 1

The source IP address is in the DatagramPacket.

Answer 2

Use:

packet.sender().getAddress()