Hi,


Im having a problem with some socket programming and im hoping someone here can help me.

basically im trying to bind a listener to a port. I have used some source code i obtained from the net, however the code was a few years old and contained the obsolete "Dns.Resolve(string.Empty);" method to get the IPHostEntry information.

Ive tried to replace this with "Dns.GetHostEntry(string.Empty);" however my code does not seem to be excuting past this point so im wondering if i have a logical error.


this is the original method

private void AcceptConnections()
		{
			IPHostEntry localMachineInfo;
			IPEndPoint localEndPoint;
			Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
			try
			{
				localMachineInfo = Dns.Resolve(string.Empty);
				localEndPoint = new IPEndPoint(localMachineInfo.AddressList[0], _port);
				// Bind the listener socket to a local port
				listener.Bind(localEndPoint);
				// Set the socket in a 'listener' mode
				listener.Listen(10);
				// Continue accepting and processing new connections indefinitely
				while (true)
				{
					threadEvent.Reset();
					// Begin listening for a new connection.  When a new connection arrives,
					//  a new thread will invoke the BeginSocketConversation method to handle the socket conversation
					listener.BeginAccept(new AsyncCallback( BeginSocketConversation), listener);
					// Wait for a connection to arrive.  When the connection arrives and is succesfully transferred
					// to a new thread, the new thread will signal this thread to begin listening again
					threadEvent.WaitOne();
				}
			}
			catch (Exception)
			{
			}
		}

this is my new altered method that does not seem to be executing

/// Listen for inbound TCP socket connections and spawn new threads to manage them
        /// </summary>
        private void AcceptConnections()
        {
            IPHostEntry localMachineInfo;
            IPEndPoint localEndPoint;
           
            Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            // print message to screen to verify code has reached this stage in execution
            string temp3 = "Accept connections executing";
            DialogTest(temp3);
            
            try
            {


                localMachineInfo = Dns.GetHostEntry(string.Empty);
                localEndPoint = new IPEndPoint(localMachineInfo.AddressList[0], _port);
                // Bind the listener socket to a local port
                listener.Bind(localEndPoint);
                // Set the socket in a 'listener' mode
                listener.Listen(10);
                string temp4 = "socket listener bound";
                DialogTest(temp4);
                // Continue accepting and processing new connections indefinitely
                while (true)
                {
                    threadEvent.Reset();
                    // Begin listening for a new connection.  When a new connection arrives,
                    //  a new thread will invoke the BeginSocketConversation method to handle the socket conversation
                    listener.BeginAccept(new AsyncCallback(BeginSocketConversation), listener);
                    string temp5 = "Begin socket conversation executing";
                    DialogTest(temp5);
                    // Wait for a connection to arrive.  When the connection arrives and is succesfully transferred
                    // to a new thread, the new thread will signal this thread to begin listening again
                    threadEvent.WaitOne();
                }
            }
            catch (Exception)
            {
            }
        }

basically the only difference is at line 8 in the original code, and line 17 in my new code, where i have tried to replace the Dns.Resolve with a Dns.GetHostEntry.plus i am using a method called DialogTest() to print messages to the screen so i can tell how far the code is executing.

i know the AcceptConnections() method is being called and starting to run because i recieve the
"Accept connections executing" message printed to screen, however the try statment does not seem to be executing properly.

does anyone know how i can properly replace this line of code

"localMachineInfo = Dns.Resolve(string.Empty);

with something that is logically correct and will work?

or can anyone see anything else they think might be preventing proper execution?

Many thanks

Attachments code.jpg 222.27 KB

What are you trying to do? Looking at this code I would say this is a bad idea:

localMachineInfo = Dns.Resolve(string.Empty);
localEndPoint = new IPEndPoint(localMachineInfo.AddressList[0], _port);

You have multiple local addresses on any given machine. Typically you have a LAN ip address of 192.168.x or 10.x.x.x and you also have a loopback address of 127.0.0.1 and with Vista and later you also have IPv6 addresses like 3ffe:401d:2042::. So blindly picking a local address to listen on is almost always a bad idea. There was a thread recently on a TCP client-server application for sending files:
http://www.daniweb.com/forums/thread228973.html

I would suggest binding to all interfaces on the machine with your desired port:

private TcpListener listener;
...
listener = new TcpListener(IPAddress.Any, DEFAULT_SERVER_PORT);

Take a look at the thread I mentioned and see if that helps you any. A functional application was also attached to the thread.

What are you trying to do? Looking at this code I would say this is a bad idea:

localMachineInfo = Dns.Resolve(string.Empty);
localEndPoint = new IPEndPoint(localMachineInfo.AddressList[0], _port);

You have multiple local addresses on any given machine. Typically you have a LAN ip address of 192.168.x or 10.x.x.x and you also have a loopback address of 127.0.0.1 and with Vista and later you also have IPv6 addresses like 3ffe:401d:2042::. So blindly picking a local address to listen on is almost always a bad idea. There was a thread recently on a TCP client-server application for sending files:
http://www.daniweb.com/forums/thread228973.html

I would suggest binding to all interfaces on the machine with your desired port:

private TcpListener listener;
...
listener = new TcpListener(IPAddress.Any, DEFAULT_SERVER_PORT);

Take a look at the thread I mentioned and see if that helps you any. A functional application was also attached to the thread.

Hi,

basically im writing an AddIn for windows media center. I want to be able to control media center remotely from my mobile phone. The socket listener is opened by the media center Addin and then waits for connections over a wifi connection from my mobile.

I'll check out that thread, cheers for the advice :)

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