// http://msdn.microsoft.com/en-us/library/fx6588te(v=vs.80).aspx using System; using System.Net; using System.Net.Sockets; using System.Text; using System.Threading; namespace echo { // State object for reading client data asynchronously public class StateObject { // Client socket. public Socket workSocket = null; // Size of receive buffer. public const int BufferSize = 64 * 1024; // Receive buffer. public byte[] buffer = new byte[BufferSize]; // Received data string. public StringBuilder sb = new StringBuilder(); } public class AsynchronousSocketListener { // Thread signal. public static ManualResetEvent allDone = new ManualResetEvent(false); public AsynchronousSocketListener() { } public static void StartListening() { UInt16 port = 11000; UInt16 maxConnections = 100; // Establish the local endpoint for the socket. // The DNS name of the computer // running the listener is "host.contoso.com". IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName()); IPAddress ipAddress = ipHostInfo.AddressList[0]; IPEndPoint localEndPoint = new IPEndPoint(ipAddress, port); // Create a TCP/IP socket. Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp ); // Bind the socket to the local endpoint and listen for incoming connections. try { listener.Bind(localEndPoint); listener.Listen(maxConnections); Console.WriteLine("Listening on {0}:{1}", ipAddress, port); while (true) { // Set the event to nonsignaled state. allDone.Reset(); // Start an asynchronous socket to listen for connections. Console.WriteLine("Waiting for a connection..."); listener.BeginAccept( new AsyncCallback(AcceptCallback), listener ); // Wait until a connection is made before continuing. allDone.WaitOne(); } } catch (Exception e) { Console.WriteLine(e.ToString()); } Console.WriteLine("\nPress ENTER to continue..."); Console.Read(); } public static void AcceptCallback(IAsyncResult ar) { // Signal the main thread to continue. allDone.Set(); // Get the socket that handles the client request. Socket listener = (Socket) ar.AsyncState; Socket handler = listener.EndAccept(ar); // Create the state object. StateObject state = new StateObject(); state.workSocket = handler; try { handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state); } catch(Exception e) { Console.WriteLine ("oh dear"); Console.WriteLine(e.ToString()); } } public static void ReadCallback(IAsyncResult ar) { String content = String.Empty; // Retrieve the state object and the handler socket // from the asynchronous state object. StateObject state = (StateObject) ar.AsyncState; Socket handler = state.workSocket; // Read data from the client socket. int bytesRead; try { bytesRead = handler.EndReceive(ar); } catch (Exception e) { Console.WriteLine ("Client already disconnected " + e.ToString()); return; } if (bytesRead > 0) { Console.WriteLine ("some bytes read"); // There might be more data, so store the data received so far. state.sb.Append(Encoding.ASCII.GetString( state.buffer,0,bytesRead)); // Check for end-of-file tag. If it is not there, read // more data. content = state.sb.ToString(); if (content.IndexOf("") > -1) { // All the data has been read from the // client. Display it on the console. Console.WriteLine("Read {0} bytes from socket. \n Data : {1}", content.Length, content ); // Echo the data back to the client. Send(handler, content); } else { // Not all data received. Get more. handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state); } } else { Console.WriteLine ("0 bytes read"); } } private static void Send(Socket handler, String data) { // Convert the string data to byte data using ASCII encoding. byte[] byteData = Encoding.ASCII.GetBytes(data); // Begin sending the data to the remote device. handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), handler); } private static void SendCallback(IAsyncResult ar) { try { // Retrieve the socket from the state object. Socket handler = (Socket) ar.AsyncState; // Complete sending the data to the remote device. int bytesSent = handler.EndSend(ar); Console.WriteLine("Sent {0} bytes to client.", bytesSent); handler.Shutdown(SocketShutdown.Both); handler.Close(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } public static int Main(String[] args) { StartListening(); return 0; } } }