Added a helpful flag to ServerContext to indicate to consumers whether it can support impersonation. Added checks to throw exceptions if impersonation is attempted on a ServerContext that does not support impersonation. Also modified the disposal behavior so that if the ServerContext is disposed while impersonation is occurring, impersonation is explicitly reverted. Consumers wishing to perform long-term impersonation must hold valid references to both the context and impersonation handle.

NSspi/Credentials/Credential.cs

@@ -28,6 +28,8 @@ namespace NSspi.Credentials
             this.securityPackage = package;
 
             this.expiry = DateTime.MinValue;
+
+            this.PackageInfo = PackageSupport.GetPackageCapabilities( this.SecurityPackage );
         }
       
         ~Credential()
@@ -35,6 +37,8 @@ namespace NSspi.Credentials
             Dispose( false );
         }
 
+        public SecPkgInfo PackageInfo { get; private set; }
+
         public string SecurityPackage
         {
             get