Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/DataAccess/ADConnectionHelper.cs

@@ -0,0 +1,95 @@
+//------------------------------------------------------------------------------
+// <copyright file="ADConnectionHelper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web.DataAccess 
+{
+    using  System.Net;
+    using  System.Diagnostics;
+    using  System.Web.Hosting;
+    using  System.Web.Security;
+    using  System.DirectoryServices;
+    using  System.DirectoryServices.Protocols;
+   
+    internal static class ActiveDirectoryConnectionHelper
+    {
+
+        internal static DirectoryEntryHolder GetDirectoryEntry(DirectoryInformation directoryInfo, string objectDN, bool revertImpersonation)
+        {
+            Debug.Assert ((objectDN != null) && (objectDN.Length != 0));
+
+            //
+            // Get the adspath and create a directory entry holder
+            //
+            DirectoryEntryHolder holder = new DirectoryEntryHolder(new DirectoryEntry (
+                                                                                                        directoryInfo.GetADsPath(objectDN), 
+                                                                                                        directoryInfo.GetUsername(), 
+                                                                                                        directoryInfo.GetPassword(), 
+                                                                                                        directoryInfo.AuthenticationTypes));
+            //
+            // If  revertImpersonation is true, we need to revert
+            //
+            holder.Open(null,  revertImpersonation);
+            return holder;
+        }
+    }
+
+    internal sealed class DirectoryEntryHolder 
+    {
+        private ImpersonationContext ctx = null;
+        private bool opened;
+        private DirectoryEntry entry;
+
+        internal DirectoryEntryHolder (DirectoryEntry entry)
+        {
+            Debug.Assert (entry != null);
+            this.entry = entry;
+        }
+
+        internal void Open (HttpContext context, bool revertImpersonate)
+        {
+            if (opened)
+                return; // Already opened
+
+            //
+            // Revert client impersonation if required
+            //
+            if (revertImpersonate)
+            {
+                ctx = new ApplicationImpersonationContext();
+            }
+            else
+            {
+                ctx = null;
+            }
+
+            opened = true; // Open worked!
+        }
+
+        internal void Close ()
+        {
+            if (!opened) // Not open!
+                return;
+
+            entry.Dispose();
+            RestoreImpersonation();
+            opened = false;
+        }
+
+        internal void RestoreImpersonation() {
+            // Restore impersonation
+            if (ctx != null)
+            {
+                ctx.Undo();
+                ctx = null;
+            }
+        }
+
+        internal DirectoryEntry DirectoryEntry
+        {
+            get { return entry; }
+        }
+    }
+}