IP address of clients in socket using NIO

Question

Using NIO, we have bound two ports to ServerSocket class.

        serverChannelPrimary = ServerSocketChannel.open();
        serverChannelSecondary = ServerSocketChannel.open();

        // Retrieves a server socket associated with this channel
        serverSocketPrimary = serverChannelPrimary.socket();
        serverSocketSecondary = serverChannelSecondary.socket();

        // Opens a connection selector
        connectionSelector = Selector.open();

        // Bind the specified port num
        serverSocketPrimary.bind(new InetSocketAddress(portOne));
        serverSocketSecondary.bind(new InetSocketAddress(portTwo));

        // Set nonblocking mode for the listening socket
        serverChannelPrimary.configureBlocking(false);
        serverChannelSecondary.configureBlocking(false);

        // Register the ServerSocketChannel with the Selector
        serverChannelPrimary.register(connectionSelector, SelectionKey.OP_ACCEPT);
        serverChannelSecondary.register(connectionSelector, SelectionKey.OP_ACCEPT);

Now, we are also able to fetch the IP address of the clients that are connected when the the new client makes the first request, which we are adding to a vector clientIps.

    while (isActive) {
        try {
            numberOfKeys = 0;
            numberOfKeys = connectionSelector.select(timeOut);
            if (numberOfKeys == 0) {
                continue; // None of request available
            }
            // Get iterator through the selected keys list
            Iterator<SelectionKey> iterKeys = connectionSelector
                    .selectedKeys().iterator();
            while (iterKeys.hasNext()) {
                try {
                    SelectionKey selectedKey = (SelectionKey) iterKeys
                            .next();
                    // Verify the key validity
                    if (!selectedKey.isValid()) {
                        logger.error("Received key is invalid");
                        continue;
                    } else if (selectedKey.isAcceptable()) {
                        // Accept the client request
                        ServerSocketChannel server = (ServerSocketChannel) selectedKey
                                .channel();
                        SocketChannel channel = server.accept();
                        // Get the socket associated with this channel
                        Socket clientInfo = channel.socket();
                        logger.debug("Application got client request from (Host name:"
                                + clientInfo.getInetAddress().getHostName()
                                + ",Ip address:"
                                + clientInfo.getInetAddress()
                                        .getHostAddress()
                                + ",port:"
                                + clientInfo.getPort());

                        String clientAddress=clientInfo.getInetAddress().getHostAddress();
                        if(!clientIps.contains(clientAddress)){
                            clientIps.add(clientAddress);
                        }

                        logger.debug("List of client : "+clientIps);

                        clientMgr.includeClient(channel);
                    }
                } catch (Exception e) {
                    logger.error(e.getMessage());
                } finally {
                    logger.debug("Since this key has been handled, remove the SelectedKey from the selector list.");
                    iterKeys.remove();
                }

            }

        } catch (Exception e) {
            logger.error(e.getMessage());
        }
    }

However, after the connection has been made, once we start getting data from multiple clients on both the ports, is it possible to determine, the .的。 I hope the code that I have provided is sufficient and clear to explain the situation we are having.

Answer 1

ServerSocketChannel is TCP, so the IP addresses at the two ends can't change.

In your line

SocketChannel channel = server.accept(); 

channel is specific to a particular client. These are the objects you will be using to communicate with each client and each one represents a single TCP session with a single remote ip/port tuple.

Answer 2

您可以调用SocketChannel.socket().getSocketAddress()来获取任何特定 SocketChannel 的远程地址。

Answer 3

Once you get the socketChannel to be able to send back to client, you get use the functions below.

//Not complete example
SocketChannel ssc;
/* after accepting and other such required operations */

ssc.socket().getInetAddress().toString();
/**
Returns:
the remote IP address to which this socket is connected, or null if the socket is not connected. 

will return 10.50.10.20 as a string
*/

//To get remote port as an int
ssc.socket().getPort();

Answer 4

I do not see "reading" part of code, but I am sure you have one. You can try to get remote socket address (ip + port) like this:

if (selectionKey.isReadable()) {
    SocketChannel client = (SocketChannel) selectionKey.channel();
    // you can here read data from given socket; client.read(buffer);
    // and also get remote (and local too) address
    client.getRemoteAddress();
}