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POSetting up a TCP/IP Client and Server to communicate over a network
 

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  1. POSetting up a TCP/IP Client and Server to communicate over a network
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    <p>I am trying to learn a little about socket programming and I have stumbled across TcpListener and TcpClient to use as I read they are slightly easier for beginners. The basic jist of what I want to accomplish is to have a small form that can be run on my laptop and another laptop on the same network and for them to be able to communicate i.e. send a string of text to each other. Once I have this I will hopefully develop it further :)</p> <p>So far I have created both a Client and a Server program using msdn and various guides found on the internet. I can get them to communicate when both running on one laptop however when I move the client to another laptop I get nowhere. I think my main issue is I do not understand quite how the client finds the Servers IP as I think I could hard code it but when I come back at another time I'm sure the IP will have changed. Is there any way to get the two to connect in a more dynamic way to encompass the changing IP? My current Client code:</p> <pre><code> public void msg(string mesg) { lstProgress.Items.Add("&gt;&gt; " + mesg); } private void btnConnect_Click(object sender, EventArgs e) { string message = "Test"; try { // Create a TcpClient. // Note, for this client to work you need to have a TcpServer // connected to the same address as specified by the server, port // combination. Int32 port = 1333; TcpClient client = new TcpClient(&lt;not sure&gt;, port); //Unsure of IP to use. // Translate the passed message into ASCII and store it as a Byte array. Byte[] data = System.Text.Encoding.ASCII.GetBytes(message); // Get a client stream for reading and writing. // Stream stream = client.GetStream(); NetworkStream stream = client.GetStream(); // Send the message to the connected TcpServer. stream.Write(data, 0, data.Length); lstProgress.Items.Add(String.Format("Sent: {0}", message)); // Receive the TcpServer.response. // Buffer to store the response bytes. data = new Byte[256]; // String to store the response ASCII representation. String responseData = String.Empty; // Read the first batch of the TcpServer response bytes. Int32 bytes = stream.Read(data, 0, data.Length); responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes); lstProgress.Items.Add(String.Format("Received: {0}", responseData)); // Close everything. stream.Close(); client.Close(); } catch (ArgumentNullException an) { lstProgress.Items.Add(String.Format("ArgumentNullException: {0}", an)); } catch (SocketException se) { lstProgress.Items.Add(String.Format("SocketException: {0}", se)); } } </code></pre> <p>My current Server code:</p> <pre><code> private void Prog_Load(object sender, EventArgs e) { bw.WorkerSupportsCancellation = true; bw.WorkerReportsProgress = true; bw.DoWork += new DoWorkEventHandler(bw_DoWork); bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged); if (bw.IsBusy != true) { bw.RunWorkerAsync(); } } private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e) { lstProgress.Items.Add(e.UserState); } private void bw_DoWork(object sender, DoWorkEventArgs e) { BackgroundWorker worker = sender as BackgroundWorker; if ((worker.CancellationPending == true)) { e.Cancel = true; } else { try { // Set the TcpListener on port 1333. Int32 port = 1333; //IPAddress localAddr = IPAddress.Parse("127.0.0.1"); TcpListener server = new TcpListener(IPAddress.Any, port); // Start listening for client requests. server.Start(); // Buffer for reading data Byte[] bytes = new Byte[256]; String data = null; // Enter the listening loop. while (true) { bw.ReportProgress(0, "Waiting for a connection... "); // Perform a blocking call to accept requests. // You could also user server.AcceptSocket() here. TcpClient client = server.AcceptTcpClient(); bw.ReportProgress(0, "Connected!"); data = null; // Get a stream object for reading and writing NetworkStream stream = client.GetStream(); int i; // Loop to receive all the data sent by the client. while ((i = stream.Read(bytes, 0, bytes.Length)) != 0) { // Translate data bytes to a ASCII string. data = System.Text.Encoding.ASCII.GetString(bytes, 0, i); bw.ReportProgress(0, String.Format("Received: {0}", data)); // Process the data sent by the client. data = String.Format("I Have Received Your Message: {0}", data); byte[] mssg = System.Text.Encoding.ASCII.GetBytes(data); // Send back a response. stream.Write(mssg, 0, mssg.Length); bw.ReportProgress(0, String.Format("Sent: {0}", data)); } // Shutdown and end connection client.Close(); } } catch (SocketException se) { bw.ReportProgress(0, String.Format("SocketException: {0}", se)); } } } </code></pre> <p>As you can probably tell I am brand new to this so if there is a better way to implement this I am more than happy to learn! Thanks for any help in advance :)</p> <p>My solution thanks to the answers below:</p> <pre><code>private String IPAddressCheck() { var IPAddr = Dns.GetHostEntry("HostName"); IPAddress ipString = null; foreach (var IP in IPAddr.AddressList) { if(IPAddress.TryParse(IP.ToString(), out ipString) &amp;&amp; IP.AddressFamily == AddressFamily.InterNetwork) { break; } } return ipString.ToString(); } private void btnConnect_Click(object sender, EventArgs e) { string message = "Test"; try { Int32 port = 1337; string IPAddr = IPAddressCheck(); TcpClient client = new TcpClient(IPAddr, port); </code></pre> <p>I'm not sure if it is the neatest solution but it is working well so thank you for the answers :)</p>
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    1. COIf you're looking for a general code review, I'd suggest posting to [CodeReview.SE](http://codereview.stackexchange.com/) instead. If you're looking for the answer to a specific question ("Is there any way to get the two to connect in a more dynamic way to encompass the changing IP?"), you should reduce the code to just the area you're having problems with.
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    2. COApologies Bobson I will keep my code snippets shorter and more relevant in the future! Thanks for the advice :)
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