Added support to retrieve the remote identity.

NSspi/Contexts/Context.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Security.Principal;
 using NSspi.Buffers;
 using NSspi.Credentials;
 
@@ -117,6 +118,68 @@ namespace NSspi.Contexts
             this.Disposed = true;
         }
 
+        public IIdentity GetRemoteIdentity()
+        {
+            using( var tokenHandle = GetContextToken() )
+            {
+                return new WindowsIdentity(
+                    tokenHandle.DangerousGetHandle(),
+                    this.Credential.SecurityPackage
+                );
+            }
+        }
+
+        private SafeTokenHandle GetContextToken()
+        {
+            bool gotRef = false;
+            SecurityStatus status = SecurityStatus.InternalError;
+            SafeTokenHandle token;
+
+            RuntimeHelpers.PrepareConstrainedRegions();
+            try
+            {
+                this.ContextHandle.DangerousAddRef( ref gotRef );
+            }
+            catch( Exception )
+            {
+                if( gotRef )
+                {
+                    this.ContextHandle.DangerousRelease();
+                    gotRef = false;
+                }
+
+                throw;
+            }
+            finally
+            {
+                if( gotRef )
+                {
+                    try
+                    {
+                        status = ContextNativeMethods.QuerySecurityContextToken(
+                            ref this.ContextHandle.rawHandle,
+                            out token
+                        );
+                    }
+                    finally
+                    {
+                        this.ContextHandle.DangerousRelease();
+                    }
+                }
+                else
+                {
+                    token = null;
+                }
+            }
+
+            if( status != SecurityStatus.OK )
+            {
+                throw new SSPIException( "Failed to query context token.", status );
+            }
+
+            return token;
+        }
+
         /// <summary>
         /// Encrypts the byte array using the context's session key.
         /// </summary>

NSspi/Contexts/ContextNativeMethods.cs

@@ -174,6 +174,10 @@ namespace NSspi.Contexts
         [DllImport( "Secur32.dll", EntryPoint = "RevertSecurityContext", CharSet = CharSet.Unicode )]
         internal static extern SecurityStatus RevertSecurityContext( ref RawSspiHandle contextHandle );
 
+        [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
+        [DllImport( "Secur32.dll", EntryPoint = "QuerySecurityContextToken", SetLastError = true )]
+        internal static extern SecurityStatus QuerySecurityContextToken( ref RawSspiHandle contextHandle, [Out] out SafeTokenHandle handle );
+
         [StructLayout( LayoutKind.Sequential )]
         private class KeyStruct
         {

NSspi/Contexts/ServerContext.cs

@@ -246,7 +246,7 @@ namespace NSspi.Contexts
 
             if( this.impersonating && this.impersonationSetsThreadPrinciple )
             {
-                SetThreadPrinciple();
+                Thread.CurrentPrincipal = new WindowsPrincipal( (WindowsIdentity)GetRemoteIdentity() );
             }
 
             return handle;
@@ -315,15 +315,5 @@ namespace NSspi.Contexts
 
             base.Dispose( disposing );
         }
-
-        /// <summary>
-        /// Set the current thread security context to the impersonated identity.
-        /// </summary>
-        private void SetThreadPrinciple()
-        {
-            Thread.CurrentPrincipal = new WindowsPrincipal(
-                WindowsIdentity.GetCurrent( TokenAccessLevels.AllAccess ) 
-            );
-        }
     }
 }

NSspi/NativeMethods.cs

@@ -17,5 +17,9 @@ namespace NSspi
         [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
         [DllImport( "Secur32.dll", EntryPoint = "EnumerateSecurityPackages", CharSet = CharSet.Unicode )]
         internal static extern SecurityStatus EnumerateSecurityPackages( ref int numPackages, ref IntPtr pkgInfoArry );
+
+        [DllImport( "Kernel32.dll", EntryPoint = "CloseHandle", SetLastError = true )]
+        [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
+        internal static extern bool CloseHandle( IntPtr handle );
     }
 }

TestServer/ServerForm.Designer.cs

@@ -170,7 +170,8 @@
             // 
             // impersonateButton
             // 
-            this.impersonateButton.Location = new System.Drawing.Point(262, 350);
+            this.impersonateButton.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)));
+            this.impersonateButton.Location = new System.Drawing.Point(262, 356);
             this.impersonateButton.Name = "impersonateButton";
             this.impersonateButton.Size = new System.Drawing.Size(116, 23);
             this.impersonateButton.TabIndex = 4;

TestServer/ServerForm.cs

@@ -1,14 +1,16 @@
 using System;
+using System.IO;
+using System.Security.Principal;
 using System.Text;
 using System.Windows.Forms;
+using NSspi;
+using NSspi.Contexts;
+using NSspi.Credentials;
 using TestProtocol;
 
 namespace TestServer
 {
-    using System.IO;
+
-    using NSspi;
-    using NSspi.Contexts;
-    using NSspi.Credentials;
     using Message = TestProtocol.Message;
 
     public partial class ServerForm : Form
@@ -38,7 +40,8 @@ namespace TestServer
                 ContextAttrib.SequenceDetect |
                 ContextAttrib.MutualAuth |
                 ContextAttrib.Delegate |
-                ContextAttrib.Confidentiality
+                ContextAttrib.Confidentiality,
+                true
             );
 
             this.server = new CustomServer();
@@ -123,7 +126,11 @@ namespace TestServer
             {
                 MessageBox.Show( "Starting impersonation: " + Environment.UserName );
 
-                FileStream stream = File.Create( Environment.GetFolderPath( Environment.SpecialFolder.DesktopDirectory ) + @"\test.txt" );
+                var directory = Environment.GetFolderPath( Environment.SpecialFolder.DesktopDirectory );
+
+                Directory.CreateDirectory( directory );
+
+                FileStream stream = File.Create( directory + @"\test.txt" );
                 StreamWriter writer = new StreamWriter( stream, Encoding.UTF8 );
 
                 writer.WriteLine( "Hello world." );
@@ -164,6 +171,32 @@ namespace TestServer
             }
         }
 
+        private void InitComplete()
+        {
+            UpdateButtons();
+            this.clientUsernameTextBox.Text = serverContext.ContextUserName;
+
+            var builder = new StringBuilder();
+            var remoteId = this.serverContext.GetRemoteIdentity();
+
+            builder.AppendLine( "Client identity information:" );
+            builder.AppendLine( " - Name: " + remoteId.Name );
+
+            var windowsId = remoteId as WindowsIdentity;
+
+            if( windowsId != null )
+            {
+                builder.AppendLine( " - User SID: " + windowsId.User.Value );
+
+                foreach( var claim in windowsId.Claims )
+                {
+                    builder.AppendLine( " - " + claim.ToString() );
+                }
+            }
+
+            this.receivedTextbox.AppendText( builder.ToString() );
+        }
+
         private void server_Disconnected()
         {
             this.running = true;
@@ -209,11 +242,7 @@ namespace TestServer
                         this.initializing = false;
                         this.connected = true;
 
-                        this.Invoke( (Action)delegate ()
+                        this.Invoke( (Action)InitComplete );
-                        {
-                            UpdateButtons();
-                            this.clientUsernameTextBox.Text = serverContext.ContextUserName;
-                        } );
                     }
                 }
                 else