Renamed the client and server forms to have their role in the name.

TestServer/ServerForm.cs

@@ -0,0 +1,221 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Data;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+using TestProtocol;
+
+namespace TestServer
+{
+    using NSspi;
+    using NSspi.Contexts;
+    using NSspi.Credentials;
+    using Message = TestProtocol.Message;
+
+    public partial class ServerForm : Form
+    {
+        private ServerCredential serverCred;
+
+        private ServerContext serverContext;
+
+        private CustomServer server;
+
+        private bool running;
+
+        private bool initializing;
+
+        private bool connected;
+
+        public ServerForm()
+        {
+            InitializeComponent();
+
+            this.serverCred = new ServerCredential( SecurityPackage.Negotiate );
+
+            this.serverContext = new ServerContext( 
+                serverCred,
+                ContextAttrib.AcceptIntegrity | 
+                ContextAttrib.ReplayDetect | 
+                ContextAttrib.SequenceDetect | 
+                ContextAttrib.MutualAuth | 
+                ContextAttrib.Delegate | 
+                ContextAttrib.Confidentiality
+            );
+
+            this.server = new CustomServer();
+            this.server.Received += server_Received;
+            this.server.Disconnected += server_Disconnected;
+
+            this.FormClosing += Form1_FormClosing;
+
+            this.startButton.Click += startButton_Click;
+            this.stopButton.Click += stopButton_Click;
+
+            this.encryptButton.Click += encryptButton_Click;
+            this.signButton.Click += signButton_Click;
+
+            this.running = false;
+            this.initializing = false;
+            this.connected = false;
+
+            UpdateButtons();
+        }
+
+        private void Form1_FormClosing( object sender, FormClosingEventArgs e )
+        {
+            this.server.Stop();
+        }
+
+        private void startButton_Click( object sender, EventArgs e )
+        {
+            this.server.StartServer( (int)this.portNumeric.Value );
+
+            this.running = true;
+            this.initializing = true;
+            this.connected = false;
+
+            UpdateButtons();
+        }
+
+        private void stopButton_Click( object sender, EventArgs e )
+        {
+            this.server.Stop();
+
+            this.running = false;
+            this.initializing = false;
+            this.connected = false;
+
+            UpdateButtons();
+        }
+
+        private void encryptButton_Click( object sender, EventArgs e )
+        {
+            Message message;
+
+            byte[] plainText = Encoding.UTF8.GetBytes( this.sendTextbox.Text );
+            byte[] cipherText = this.serverContext.Encrypt( plainText );
+
+            message = new Message( ProtocolOp.EncryptedMessage, cipherText );
+
+            this.server.Send( message );
+        }
+
+        private void signButton_Click( object sender, EventArgs e )
+        {
+            // Not implemented.
+        }
+        
+        private void UpdateButtons()
+        {
+            this.startButton.Enabled = this.running == false;
+            this.stopButton.Enabled = this.running;
+
+            this.encryptButton.Enabled = this.connected;
+            this.signButton.Enabled = this.connected;
+        }
+
+
+        private void server_Received( Message message )
+        {
+            if( message.Operation == ProtocolOp.ClientToken )
+            {
+                HandleInit( message );
+            }
+            else if( message.Operation == ProtocolOp.EncryptedMessage )
+            {
+                HandleEncrypted( message );
+            }
+            else if( message.Operation == ProtocolOp.SignedMessage )
+            {
+                HandleSigned( message );
+            }
+            else
+            {
+                HandleUnknown( message );
+            }
+        }
+
+        private void server_Disconnected()
+        {
+            this.running = false;
+            this.initializing = false;
+            this.connected = false;
+
+            UpdateButtons();
+        }
+
+
+        private void HandleInit( Message message )
+        {
+            byte[] nextToken;
+            SecurityStatus status;
+
+            if( initializing )
+            {
+                status = this.serverContext.AcceptToken( message.Data, out nextToken );
+
+                if( status == SecurityStatus.OK || status == SecurityStatus.ContinueNeeded )
+                {
+                    if( nextToken != null )
+                    {
+                        this.server.Send( new Message( ProtocolOp.ServerToken, nextToken ) );
+                    }
+
+                    if( status == SecurityStatus.OK )
+                    {
+                        this.initializing = false;
+                        this.connected = true;
+
+                        this.Invoke( (Action)delegate() { UpdateButtons(); } );
+                    }
+                }
+                else
+                {
+                    this.Invoke( (Action)delegate() 
+                    {
+                        MessageBox.Show( "Failed to accept token from client. Sspi error code: " + status );
+                    } );
+                }
+
+            }
+        }
+
+        private void HandleEncrypted( Message message )
+        {
+            this.Invoke( (Action)delegate()
+            {
+                byte[] plainText = this.serverContext.Decrypt( message.Data );
+                string text = Encoding.UTF8.GetString( plainText );
+                
+                this.receivedTextbox.Text += "Received encrypted message from client:\r\n" + text + "\r\n";
+            } );
+        }
+
+        private void HandleSigned( Message message )
+        {
+            // Not implemented yet.
+            /*
+            this.Invoke( (Action)delegate()
+            {
+                byte[] plainText = this.serverContext.Decrypt( message.Data );
+                string text = Encoding.UTF8.GetString( plainText );
+
+                this.receivedTextbox.Text += "Received encrypted message from client:\r\n" + text + "\r\n";
+            } );
+             */
+        }
+
+        private void HandleUnknown( Message message )
+        {
+            this.Invoke( (Action)delegate()
+            {
+                MessageBox.Show( "Received unexpected message from server. Message type: " + message.Operation );
+            } );
+        }
+
+    }
+}