Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/Util/ActivityIdHelper.cs

@@ -0,0 +1,95 @@
+//------------------------------------------------------------------------------
+// <copyright file="ActivityIdHelper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Diagnostics.Tracing;
+    using System.Runtime.CompilerServices;
+    using System.Threading;
+
+    internal sealed class ActivityIdHelper {
+
+        private delegate Guid GetCurrentDelegate();
+        private delegate void SetAndDestroyDelegate(Guid activityId);
+        private delegate void SetAndPreserveDelegate(Guid activityId, out Guid oldActivityThatWillContinue);
+
+        // Note to callers: this field can be null.
+        internal static readonly ActivityIdHelper Instance = GetSingleton();
+
+        private static readonly Guid _baseGuid = Guid.NewGuid();
+        private static long _counter;
+
+        private readonly GetCurrentDelegate _getCurrentDel;
+        private readonly SetAndDestroyDelegate _setAndDestroyDel;
+        private readonly SetAndPreserveDelegate _setAndPreserveDel;
+
+        // use the factory to create an instance of this type
+        private ActivityIdHelper(GetCurrentDelegate getCurrentDel, SetAndDestroyDelegate setAndDestroyDel, SetAndPreserveDelegate setAndPreserveDel) {
+            _getCurrentDel = getCurrentDel;
+            _setAndDestroyDel = setAndDestroyDel;
+            _setAndPreserveDel = setAndPreserveDel;
+        }
+
+        // Gets the current thread's activity ID.
+        public Guid CurrentThreadActivityId {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get { return _getCurrentDel(); }
+        }
+
+        private static ActivityIdHelper GetSingleton() {
+            try {
+                // The mscorlib APIs we depend on weren't added until Blue, so we can't
+                // take a direct dependency. Need to light up instead.
+
+                var getCurrentDel = (GetCurrentDelegate)Delegate.CreateDelegate(
+                    typeof(GetCurrentDelegate), typeof(EventSource), "get_CurrentThreadActivityId", ignoreCase: false, throwOnBindFailure: false);
+
+                var setAndDestroyDel = (SetAndDestroyDelegate)Delegate.CreateDelegate(
+                    typeof(SetAndDestroyDelegate), typeof(EventSource), "SetCurrentThreadActivityId", ignoreCase: false, throwOnBindFailure: false);
+
+                var setAndPreserveDel = (SetAndPreserveDelegate)Delegate.CreateDelegate(
+                    typeof(SetAndPreserveDelegate), typeof(EventSource), "SetCurrentThreadActivityId", ignoreCase: false, throwOnBindFailure: false);
+
+                if (getCurrentDel != null && setAndDestroyDel != null && setAndPreserveDel != null) {
+                    return new ActivityIdHelper(getCurrentDel, setAndDestroyDel, setAndPreserveDel);
+                }
+            }
+            catch {
+                // exceptions are not fatal; we just won't be able to call the new APIs
+            }
+
+            return null;
+        }
+
+        // Disposes of the thread's existing activity ID, then sets the new activity ID on this thread.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void SetCurrentThreadActivityId(Guid activityId) {
+            _setAndDestroyDel(activityId);
+        }
+
+        // Suspends (but does not dispose of) the thread's existing activity ID, then sets a new activity ID on this thread.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void SetCurrentThreadActivityId(Guid activityId, out Guid oldActivityThatWillContinue) {
+            _setAndPreserveDel(activityId, out oldActivityThatWillContinue);
+        }
+
+        // !! SECURITY WARNING !!
+        // The GUIDs created by this method are predictable and should be used ONLY for tracing.
+        // Any other use (such as leaking them to the user) constitutes information disclosure.
+        //
+        // This is a perf-sensitive method since it could potentially be called many times per
+        // request. Guid.NewGuid() is slow since it eventually calls CAPI, and we did actually
+        // see it show up as a bottleneck when developing MVC 2. The below implementation has
+        // measurably better performance characteristics than calling the other Guid ctors.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static unsafe Guid UnsafeCreateNewActivityId() {
+            Guid guidCopy = _baseGuid;
+            *(long*)(&guidCopy) ^= Interlocked.Increment(ref _counter); // operate on the copy, not the original
+            return guidCopy;
+        }
+
+    }
+}

external/referencesource/System.Web/Util/AppSettings.cs

@@ -0,0 +1,469 @@
+//------------------------------------------------------------------------------
+// <copyright file="AppSettings.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+// AppSettings.cs
+//
+
+using System;
+using System.Collections.Specialized;
+using System.Configuration;
+using System.Diagnostics.CodeAnalysis;
+using System.Security.Permissions;
+using System.Web.Configuration;
+using System.Web.Hosting;
+
+namespace System.Web.Util {
+
+    internal static class AppSettings
+    {
+        private static volatile bool _settingsInitialized = false;
+        private static object _appSettingsLock = new object();
+        private static void EnsureSettingsLoaded() {
+
+            if (!_settingsInitialized) {
+                lock (_appSettingsLock) {
+                    if (!_settingsInitialized) {
+
+                        NameValueCollection settings = null;
+
+                        try {
+                            settings = GetAppSettingsSection();
+                        } finally {
+            
+                            // GetApplicationPathData may throw.  That's fine.  Let the user see the exception
+                            // once, but just fall back on default settings for the future.
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseHostHeaderForRequestUrl"], out _useHostHeaderForRequestUrl))
+                                _useHostHeaderForRequestUrl = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowAnonymousImpersonation"], out _allowAnonymousImpersonation))
+                                _allowAnonymousImpersonation = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:ScriptResourceAllowNonJsFiles"], out _scriptResourceAllowNonJsFiles))
+                                _scriptResourceAllowNonJsFiles = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseLegacyEncryption"], out _useLegacyEncryption))
+                                _useLegacyEncryption = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseLegacyMachineKeyEncryption"], out _useLegacyMachineKeyEncryption))
+                                _useLegacyMachineKeyEncryption = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseLegacyFormsAuthenticationTicketCompatibility"], out _useLegacyFormsAuthenticationTicketCompatibility))
+                                _useLegacyFormsAuthenticationTicketCompatibility = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseLegacyEventValidationCompatibility"], out _useLegacyEventValidationCompatibility))
+                                _useLegacyEventValidationCompatibility = false;
+
+                            _allowInsecureDeserialization = GetNullableBooleanValue(settings, "aspnet:AllowInsecureDeserialization");
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AlwaysIgnoreViewStateValidationErrors"], out _alwaysIgnoreViewStateValidationErrors))
+                                _alwaysIgnoreViewStateValidationErrors = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowRelaxedHttpUserName"], out _allowRelaxedHttpUserName))
+                                _allowRelaxedHttpUserName = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:JavaScriptDoNotEncodeAmpersand"], out _javaScriptDoNotEncodeAmpersand))
+                                _javaScriptDoNotEncodeAmpersand = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseTaskFriendlySynchronizationContext"], out _useTaskFriendlySynchronizationContext))
+                                _useTaskFriendlySynchronizationContext = (BinaryCompatibility.Current.TargetsAtLeastFramework45) ? true : false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowAsyncDuringSyncStages"], out _allowAsyncDuringSyncStages))
+                                _allowAsyncDuringSyncStages = false;
+
+                            if (settings == null || !int.TryParse(settings["aspnet:MaxHttpCollectionKeys"], out _maxHttpCollectionKeys) || _maxHttpCollectionKeys < 0)
+                                _maxHttpCollectionKeys = DefaultMaxHttpCollectionKeys;
+
+                            if (settings == null || !int.TryParse(settings["aspnet:MaxJsonDeserializerMembers"], out _maxJsonDeserializerMembers) || _maxJsonDeserializerMembers < 0)
+                                _maxJsonDeserializerMembers = DefaultMaxJsonDeserializerMembers;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:DoNotDisposeSpecialHttpApplicationInstances"], out _doNotDisposeSpecialHttpApplicationInstances))
+                                _doNotDisposeSpecialHttpApplicationInstances = false;
+
+                            if (settings != null)
+                                _formsAuthReturnUrlVar = settings["aspnet:FormsAuthReturnUrlVar"];
+            
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:RestrictXmlControls"], out _restrictXmlControls))
+                                _restrictXmlControls = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowRelaxedRelativeUrl"], out _allowRelaxedRelativeUrl))
+                                _allowRelaxedRelativeUrl = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:UseLegacyRequestUrlGeneration"], out _useLegacyRequestUrlGeneration))
+                                _useLegacyRequestUrlGeneration = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowUtf7RequestContentEncoding"], out _allowUtf7RequestContentEncoding))
+                                _allowUtf7RequestContentEncoding = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:AllowRelaxedUnicodeDecoding"], out _allowRelaxedUnicodeDecoding))
+                                _allowRelaxedUnicodeDecoding = false;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:DontUsePercentUUrlEncoding"], out _dontUsePercentUUrlEncoding))
+                                _dontUsePercentUUrlEncoding = BinaryCompatibility.Current.TargetsAtLeastFramework452; // default value is keyed off of <httpRuntime targetFramework="4.5.2" />
+
+                            if (settings == null || !int.TryParse(settings["aspnet:UpdatePanelMaxScriptLength"], out _updatePanelMaxScriptLength) || _updatePanelMaxScriptLength < 0)
+                                _updatePanelMaxScriptLength = 0;
+                            
+                            // AppSettings override allows users to build against 4.5 but run against 4.0 or 4.5
+                            _maxConcurrentCompilations = GetNullableIntegerValue(settings, "aspnet:MaxConcurrentCompilations");
+
+                            if (settings == null || !int.TryParse(settings["aspnet:MaxAcceptLanguageFallbackCount"], out _maxAcceptLanguageFallbackCount) || _maxAcceptLanguageFallbackCount <= 0)
+                                _maxAcceptLanguageFallbackCount = DefaultMaxAcceptLanguageFallbackCount;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:PortableCompilationOutput"], out _portableCompilationOutput))
+                                _portableCompilationOutput = false;
+
+                            if (settings == null || string.IsNullOrWhiteSpace(_portableCompilationOutputSnapshotType = settings["aspnet:PortableCompilationOutputSnapshotType"]))
+                                _portableCompilationOutputSnapshotType = null;
+
+                            if (settings == null || string.IsNullOrWhiteSpace(_portableCompilationOutputSnapshotTypeOptions = settings["aspnet:PortableCompilationOutputSnapshotTypeOptions"]))
+                                _portableCompilationOutputSnapshotTypeOptions = null;
+
+                            if (settings == null || !Boolean.TryParse(settings["aspnet:EnsureSessionStateLockedOnFlush"], out _ensureSessionStateLockedOnFlush))
+                                _ensureSessionStateLockedOnFlush = false;
+
+                            _settingsInitialized = true;
+                        }
+                    }
+                }
+            }
+        }
+
+        [ConfigurationPermission(SecurityAction.Assert, Unrestricted = true)]
+        [SuppressMessage("Microsoft.Security", "CA2106:SecureAsserts", Justification = "This assert is safe since we control the callers; they're not leaking information.")]
+        private static NameValueCollection GetAppSettingsSection() {
+            // DevDiv #353926 - Fall back to reading App.config if System.Web types are being consumed outside an ASP.NET application
+            if (!HostingEnvironment.IsHosted) {
+                return ConfigurationManager.AppSettings;
+            }
+
+            // Check the app-level config. Ignore configuration errors
+            CachedPathData appPathData = CachedPathData.GetApplicationPathData();
+
+            if (appPathData != null && appPathData.ConfigRecord != null)
+                return appPathData.ConfigRecord.GetSection("appSettings") as NameValueCollection;
+
+            // nothing found
+            return null;
+        }
+
+        // helper function to read a tri-state boolean from config
+        private static bool? GetNullableBooleanValue(NameValueCollection settings, string key) {
+            bool value;
+            return (settings != null && Boolean.TryParse(settings[key], out value)) ? value : (bool?)null;
+        }
+
+        // helper function to read a nullable int from config
+        private static int? GetNullableIntegerValue(NameValueCollection settings, string key) {
+            int value;
+            return (settings != null && int.TryParse(settings[key], out value)) ? value : (int?)null;
+        }
+
+        private static  bool _useHostHeaderForRequestUrl;
+        internal static bool UseHostHeaderForRequestUrl {
+            get {
+                EnsureSettingsLoaded();
+                return _useHostHeaderForRequestUrl;
+            }
+        }
+
+        private static  bool _allowAnonymousImpersonation;
+        internal static bool AllowAnonymousImpersonation {
+            get {
+                EnsureSettingsLoaded();
+                return _allowAnonymousImpersonation;
+            }
+        }
+
+        // false [default] to allow ScriptResource.axd to serve static files only if they are *.js; 
+        // true to allow ScriptResource.axd to serve any static file (bad practice)
+        private static  bool _scriptResourceAllowNonJsFiles;
+        internal static bool ScriptResourceAllowNonJsFiles {
+            get {
+                EnsureSettingsLoaded();
+                return _scriptResourceAllowNonJsFiles;
+            }
+        }
+
+        // false [default] to use encrypt+sign for all except Membership and MachineKey public API
+        // true to use encrypt only (dangerous!)
+        private static  bool _useLegacyEncryption;
+        internal static bool UseLegacyEncryption {
+            get {
+                EnsureSettingsLoaded();
+                return _useLegacyEncryption;
+            }
+        }
+
+        // false [default] to use encrypt+sign for MachineKey public API
+        // true to use encrypt only for MachineKey public API (dangerous!)
+        private static  bool _useLegacyMachineKeyEncryption;
+        internal static bool UseLegacyMachineKeyEncryption {
+            get {
+                EnsureSettingsLoaded();
+                return _useLegacyMachineKeyEncryption;
+            }
+        }
+
+        // false [default] to use secure semantics when generating FormsAuthentication tickets
+        // true to allow ticketCompatibilityMode="Framework20" (dangerous!)
+        private static bool _useLegacyFormsAuthenticationTicketCompatibility;
+        internal static bool UseLegacyFormsAuthenticationTicketCompatibility {
+            get {
+                EnsureSettingsLoaded();
+                return _useLegacyFormsAuthenticationTicketCompatibility;
+            }
+        }
+
+        // false [default] to use a cryptographic hash algorithm when generating the __EVENTVALIDATION field
+        // true to use String.GetHashCode() instead (dangerous!)
+        // more info: DevDiv #233564 (http://vstfdevdiv:8080/DevDiv2/web/wi.aspx?id=233564)
+        private static bool _useLegacyEventValidationCompatibility;
+        internal static bool UseLegacyEventValidationCompatibility {
+            get {
+                EnsureSettingsLoaded();
+                return _useLegacyEventValidationCompatibility;
+            }
+        }
+
+        // false to always enforce EnableViewStateMac=false
+        // true to allow the developer to specify EnableViewStateMac=false (dangerous, leads to RCE!)
+        // null [default] to make the decision based on a registry key
+        // more info: DevDiv #461378 (http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/461378)
+        private static bool? _allowInsecureDeserialization;
+        internal static bool? AllowInsecureDeserialization {
+            get {
+                EnsureSettingsLoaded();
+                return _allowInsecureDeserialization;
+            }
+        }
+
+        // false [default] to use the default heuristic for determining when to suppress __VIEWSTATE MAC validation errors and when to display a YSOD
+        // true to always ---- errors and never show a YSOD
+        private static bool _alwaysIgnoreViewStateValidationErrors;
+        internal static bool AlwaysIgnoreViewStateValidationErrors {
+            get {
+                EnsureSettingsLoaded();
+                return _alwaysIgnoreViewStateValidationErrors;
+            }
+        }
+
+        // false [default] to restrict dangerous characters in any user name passed to native code
+        // true to allow dangerous characters
+        private static bool _allowRelaxedHttpUserName;
+        internal static bool AllowRelaxedHttpUserName {
+            get {
+                EnsureSettingsLoaded();
+                return _allowRelaxedHttpUserName;
+            }
+        }
+
+        // false [default] to encode '&' characters in HttpUtility.JavaScriptStringEncode()
+        // true to not encode '&' characters (bad practice)
+        private static bool _javaScriptDoNotEncodeAmpersand;
+        internal static bool JavaScriptDoNotEncodeAmpersand {
+            get {
+                EnsureSettingsLoaded();
+                return _javaScriptDoNotEncodeAmpersand;
+            }
+        }
+
+        // false [default] to use the updated AspNetSynchronizationContext type (needed for TAP methods)
+        // true to use LegacyAspNetSynchronizationContext (needed for some back-compat scenarios)
+        private static bool _useTaskFriendlySynchronizationContext ;
+        internal static bool UseTaskFriendlySynchronizationContext {
+            get {
+                EnsureSettingsLoaded();
+                return _useTaskFriendlySynchronizationContext ;
+            }
+        }
+
+        // false [default] if the updated AspNetSynchronizationContext type should throw when it encounters invalid operations
+        // true to allow some invalid operations through the system (needed for some back-compat scenarios)
+        // more info: see doc on HttpContext.AllowAsyncDuringSyncStages
+        private static bool _allowAsyncDuringSyncStages;
+        internal static bool AllowAsyncDuringSyncStages {
+            get {
+                EnsureSettingsLoaded();
+                return _allowAsyncDuringSyncStages;
+            }
+        }
+
+         // maximum number of keys a HttpValueCollection, HttpFileCollection or HttpCookieCollection is allowed to have
+         private const int DefaultMaxHttpCollectionKeys = Int32.MaxValue;
+         private static int _maxHttpCollectionKeys = DefaultMaxHttpCollectionKeys;
+         internal static int MaxHttpCollectionKeys {
+             get {
+                 EnsureSettingsLoaded();
+                 return _maxHttpCollectionKeys;
+             }
+         }
+
+         // maximum number of entries a Json deserialized dictionary is allowed to have
+         private const int DefaultMaxJsonDeserializerMembers = Int32.MaxValue;
+         private static int _maxJsonDeserializerMembers = DefaultMaxJsonDeserializerMembers;
+         internal static int MaxJsonDeserializerMembers {
+             get {
+                 EnsureSettingsLoaded();
+                 return _maxJsonDeserializerMembers;
+             }
+         }
+
+        // false [default] to call HttpApplication.Dispose() on all HttpApplication instances instantiated by ASP.NET
+        // true to suppress calling HttpApplication.Dispose() on "special" (i.e., associated with App_Start, App_End, etc.) HttpApplication instances
+        // see DevDiv #109006 (http://vstfdevdiv:8080/DevDiv2/web/wi.aspx?id=109006): HttpModules attached to the "Special" HttpApplication instance are not disposed
+        private static bool _doNotDisposeSpecialHttpApplicationInstances;
+        internal static bool DoNotDisposeSpecialHttpApplicationInstances {
+            get {
+                EnsureSettingsLoaded();
+                return _doNotDisposeSpecialHttpApplicationInstances;
+            }
+        }
+
+        // none [default] to use the existing /loging.aspx?ReturnUrl=
+        // <FormsAuthReturnUrlVar> to use /loging.aspx?<FormsAuthReturnUrlVar>=
+        private static string _formsAuthReturnUrlVar;
+        internal static string FormsAuthReturnUrlVar {
+            get {
+                EnsureSettingsLoaded();
+                return _formsAuthReturnUrlVar;
+            }
+        }
+
+        // false [default] to use potentially unsafe System.Xml API's that were in use for 1.0 through 4.0
+        // true to avoid using vulnerable System.Xml API's.
+        private static bool _restrictXmlControls;
+        internal static bool RestrictXmlControls {
+            get {
+                EnsureSettingsLoaded();
+                return _restrictXmlControls;
+            }
+        }
+
+        // false [default] - requires relative url to be more strict
+        // true - use less strict policy
+        private static bool _allowRelaxedRelativeUrl;
+        internal static bool AllowRelaxedRelativeUrl {
+            get {
+                EnsureSettingsLoaded();
+                return _allowRelaxedRelativeUrl;
+            }
+        }
+
+        // false [default] - attempts to re-encode HttpRequest.Url so that it is equivalent to the actual incoming URL 
+        // true - does not attempt to re-encode the Url, which could allow the Uri class to perform double-decoding (dangerous!)
+        // See also DevDiv #703232 (http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/703232)
+        private static bool _useLegacyRequestUrlGeneration;
+        internal static bool UseLegacyRequestUrlGeneration {
+            get {
+                EnsureSettingsLoaded();
+                return _useLegacyRequestUrlGeneration;
+            }
+        }
+
+        // false [default] - disallow UTF-7 as an incoming ContentEncoding
+        // true - allow UTF-7 as an incoming ContentEncoding (dangerous!)
+        private static bool _allowUtf7RequestContentEncoding;
+        internal static bool AllowUtf7RequestContentEncoding {
+            get {
+                EnsureSettingsLoaded();
+                return _allowUtf7RequestContentEncoding;
+            }
+        }
+
+        // false [default] - disallow invalid UTF-16 (like unpaired surrogates) when deserializing JSON strings and inside UrlDecode
+        // true - allow malformed strings like "\ud800" and "%ud800" to be deserialized (dangerous!)
+        private static bool _allowRelaxedUnicodeDecoding;
+        internal static bool AllowRelaxedUnicodeDecoding {
+            get {
+                EnsureSettingsLoaded();
+                return _allowRelaxedUnicodeDecoding;
+            }
+        }
+
+        // false - use UrlEncodeUnicode for some URL generation within ASP.NET, which can produce non-compliant results
+        // true - use UTF8 encoding for things like <form action>, which works with modern browsers
+        // defaults to true when targeting >= 4.5.2, otherwise false
+        // See DevDiv #762975 for more information.
+        private static bool _dontUsePercentUUrlEncoding;
+        internal static bool DontUsePercentUUrlEncoding {
+            get {
+                EnsureSettingsLoaded();
+                return _dontUsePercentUUrlEncoding;
+            }
+        }
+
+        // maximum length for UpdatePanel script block
+        private static int _updatePanelMaxScriptLength;
+        internal static int UpdatePanelMaxScriptLength {
+            get {
+                EnsureSettingsLoaded();
+                return _updatePanelMaxScriptLength;
+            }
+        }
+
+       // maximum number of concurrent compilations
+       private static int? _maxConcurrentCompilations;
+       internal static int? MaxConcurrentCompilations {
+           get {
+               EnsureSettingsLoaded();
+               return _maxConcurrentCompilations;
+           }
+       }
+
+        // Controls how deep we look when trying to get a CultureInfo from an Accept-Language header.
+        // For example, a value of 3 with Accept-Language: en-us, en, fr-FR, zh-CN will cause us to
+        // look for "en-us", "en", and "fr-FR" in order, taking the first hit, but we won't look
+        // for "zh-CN" if the first three fail. Setting this value too high could result in DoS.
+        private const int DefaultMaxAcceptLanguageFallbackCount = 3;
+        private static int _maxAcceptLanguageFallbackCount;
+        internal static int MaxAcceptLanguageFallbackCount {
+            get {
+                EnsureSettingsLoaded();
+                return _maxAcceptLanguageFallbackCount;
+            }
+        }
+
+       // false [default] 
+       // true to allow 
+       private static bool _portableCompilationOutput;
+       internal static bool PortableCompilationOutput {
+           get {
+               EnsureSettingsLoaded();
+               return _portableCompilationOutput;
+           }
+       }
+
+       // null [default] 
+       // complete type name as string
+       private static string _portableCompilationOutputSnapshotType;
+       internal static string PortableCompilationOutputSnapshotType {
+           get {
+               EnsureSettingsLoaded();
+               return _portableCompilationOutputSnapshotType;
+           }
+       }
+
+       // null [default] 
+       // options
+       private static string _portableCompilationOutputSnapshotTypeOptions;
+       internal static string PortableCompilationOutputSnapshotTypeOptions {
+           get {
+               EnsureSettingsLoaded();
+               return _portableCompilationOutputSnapshotTypeOptions;
+           }
+       }
+
+       // false [default] - allow delayed store of session state item (possibly concurrent access on new session)
+       // true - ensure the session state item is stored before another request is allowed to proceed with the same session
+       private static bool _ensureSessionStateLockedOnFlush;
+       internal static bool EnsureSessionStateLockedOnFlush {
+           get {
+               EnsureSettingsLoaded();
+               return _ensureSessionStateLockedOnFlush;
+           }
+       }
+    }
+}

external/referencesource/System.Web/Util/AppVerifierErrorCode.cs

@@ -0,0 +1,33 @@
+namespace System.Web.Util {
+    using System;
+
+    // IMPORTANT: Each error code must be used in *exactly one place* in order to make
+    // diagnosing the failure easier.
+
+    internal enum AppVerifierErrorCode {
+
+        Ok,
+
+        /* ASYNC OPERATIONS */
+        HttpApplicationInstanceWasNull,
+        BeginHandlerDelegateWasNull,
+        AsyncCallbackInvokedMultipleTimes,
+        AsyncCallbackInvokedWithNullParameter,
+        AsyncCallbackGivenAsyncResultWhichWasNotCompleted,
+        AsyncCallbackInvokedSynchronouslyButAsyncResultWasNotMarkedCompletedSynchronously,
+        AsyncCallbackInvokedAsynchronouslyButAsyncResultWasMarkedCompletedSynchronously,
+        AsyncCallbackInvokedWithUnexpectedAsyncResultInstance,
+        AsyncCallbackInvokedAsynchronouslyThenBeginHandlerThrew,
+        BeginHandlerThrewThenAsyncCallbackInvokedAsynchronously,
+        AsyncCallbackInvokedSynchronouslyThenBeginHandlerThrew,
+        AsyncCallbackInvokedWithUnexpectedAsyncResultAsyncState,
+        AsyncCallbackCalledAfterHttpApplicationReassigned,
+        BeginHandlerReturnedNull,
+        BeginHandlerReturnedAsyncResultMarkedCompletedSynchronouslyButWhichWasNotCompleted,
+        BeginHandlerReturnedAsyncResultMarkedCompletedSynchronouslyButAsyncCallbackNeverCalled,
+        BeginHandlerReturnedUnexpectedAsyncResultInstance,
+        BeginHandlerReturnedUnexpectedAsyncResultAsyncState,
+        SyncContextSendOrPostCalledAfterRequestCompleted
+
+    }
+}

external/referencesource/System.Web/Util/AppVerifierException.cs

@@ -0,0 +1,32 @@
+namespace System.Web.Util {
+    using System;
+    using System.Diagnostics.CodeAnalysis;
+    using System.Runtime.Serialization;
+
+    // Thrown when the AppVerifier fails an assert.
+
+    // This type is used solely as a support / diagnostics tool and will never appear over the normal course of an application.
+    // Specifically, it will never cross an AppDomain boundary, and we don't want to mark it as [Serializable] since that is
+    // essentially a public contract, and the AppVerifier feature has no public API surface. We want to retain the ability to
+    // change this feature on a whim without risk of breaking anybody.
+    [SuppressMessage("Microsoft.Usage", "CA2237:MarkISerializableTypesWithSerializable", Justification = "Doesn't need to be serializable.")]
+    internal sealed class AppVerifierException : Exception {
+
+        private readonly AppVerifierErrorCode _errorCode;
+
+        public AppVerifierException(AppVerifierErrorCode errorCode, string message)
+            : base(message) {
+
+            _errorCode = errorCode;
+        }
+
+        private AppVerifierException(SerializationInfo info, StreamingContext context) : base(info, context) { }
+
+        public AppVerifierErrorCode ErrorCode {
+            get {
+                return _errorCode;
+            }
+        }
+
+    }
+}

external/referencesource/System.Web/Util/ArglessEventHandlerProxy.cs

@@ -0,0 +1,164 @@
+//------------------------------------------------------------------------------
+// <copyright file="ArglessEventHandlerProxy.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Reflection;
+    using System.Reflection.Emit;
+    using System.Security.Permissions;
+    using System.Security;
+
+/*
+ * Proxy that provides EventHandler and redirects it to arg-less method on the given object
+ */
+    internal class ArglessEventHandlerProxy {
+        private Object _target;
+        private MethodInfo _arglessMethod;
+
+        internal ArglessEventHandlerProxy(Object target, MethodInfo arglessMethod) {
+            Debug.Assert(arglessMethod.GetParameters().Length == 0);
+
+            _target = target;
+            _arglessMethod = arglessMethod;
+        }
+
+        [ReflectionPermission(SecurityAction.Assert, Flags=ReflectionPermissionFlag.RestrictedMemberAccess)]
+        internal void Callback(Object sender, EventArgs e) {
+            _arglessMethod.Invoke(_target, new Object[0]);
+        }
+
+        internal EventHandler Handler {
+            get {
+                return new EventHandler(Callback);
+            }
+        }
+    }
+
+    internal delegate void VoidMethod();
+
+    internal class CalliEventHandlerDelegateProxy {
+        private delegate void ParameterlessDelegate();
+        private delegate void ParameterfulDelegate(object sender, EventArgs e);
+
+        private IntPtr _functionPointer;
+        private Object _target;
+        private bool _argless;
+
+        internal CalliEventHandlerDelegateProxy(Object target, IntPtr functionPointer, bool argless) {
+            _argless = argless;
+            _target = target;
+            _functionPointer = functionPointer;
+        }
+
+        internal void Callback(Object sender, EventArgs e) {
+            if (_argless) {
+                ParameterlessDelegate del = FastDelegateCreator<ParameterlessDelegate>.BindTo(_target, _functionPointer);
+                del();
+            }
+            else {
+                ParameterfulDelegate del = FastDelegateCreator<ParameterfulDelegate>.BindTo(_target, _functionPointer);
+                del(sender, e);
+            }
+        }
+
+        internal EventHandler Handler {
+            get {
+                return new EventHandler(Callback);
+            }
+        }
+    }
+
+#if LCG_Implementation
+    internal delegate void ArglessMethod(IntPtr methodPtr, Object target);
+    internal delegate void EventArgMethod(IntPtr methodPtr, Object target, Object source, EventArgs e);
+
+    internal class CalliHelper {
+        internal static ArglessMethod ArglessFunctionCaller;
+        internal static EventArgMethod EventArgFunctionCaller;
+
+        // Make sure we have reflection permission to use ReflectionEmit and access method
+        [ReflectionPermission(SecurityAction.Assert, Flags = ReflectionPermissionFlag.ReflectionEmit | ReflectionPermissionFlag.MemberAccess)]
+        static CalliHelper() {
+            // generate void(void) calli
+            DynamicMethod dm = new DynamicMethod("void_calli",
+                                                    typeof(void),
+                                                    new Type[] { typeof(IntPtr) /* function ptr */, typeof(Object) /* target */},
+                                                    typeof(CalliHelper).Module);
+            ILGenerator ilg = dm.GetILGenerator();
+
+            ilg.Emit(OpCodes.Ldarg_1);
+            ilg.Emit(OpCodes.Ldarg_0);
+            ilg.EmitCalli(OpCodes.Calli, CallingConventions.HasThis, typeof(void), new Type[0], null);
+            ilg.Emit(OpCodes.Ret);
+            ArglessFunctionCaller = (ArglessMethod)dm.CreateDelegate(typeof(ArglessMethod));
+
+            // generate void(Object, EventArgs) calli
+            dm = new DynamicMethod("eventarg_calli",
+                                    typeof(void),
+                                    new Type[] { typeof(IntPtr) /* function ptr */, typeof(Object) /* target */, typeof(Object) /* sender */, typeof(EventArgs) },
+                                    typeof(CalliHelper).Module);
+            ilg = dm.GetILGenerator();
+
+            ilg.Emit(OpCodes.Ldarg_1);
+            ilg.Emit(OpCodes.Ldarg_2);
+            ilg.Emit(OpCodes.Ldarg_3);
+            ilg.Emit(OpCodes.Ldarg_0);
+            ilg.EmitCalli(OpCodes.Calli, CallingConventions.HasThis, typeof(void), new Type[] { typeof(object) /* sender */, typeof(EventArgs) }, null);
+            ilg.Emit(OpCodes.Ret);
+            EventArgFunctionCaller = (EventArgMethod)dm.CreateDelegate(typeof(EventArgMethod));
+        }
+    }
+#endif //LCG_Implementation
+
+#if  Reflection_Emit_Implementation
+    internal delegate void ArglessMethod(IntPtr methodPtr, Object target);
+    internal delegate void EventArgMethod(IntPtr methodPtr, Object target, Object source, EventArgs e);
+
+    internal class CalliHelper {
+
+        internal static ArglessMethod ArglessFunctionCaller;
+        internal static EventArgMethod EventArgFunctionCaller;
+
+        // Make sure we have reflection permission to use ReflectionEmit and access method
+        [ReflectionPermission(SecurityAction.Assert, Flags = ReflectionPermissionFlag.ReflectionEmit | ReflectionPermissionFlag.MemberAccess)]
+        static CalliHelper() {
+
+            AssemblyName an = new AssemblyName("CalliHelper");
+            AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(an, AssemblyBuilderAccess.Run);
+            ModuleBuilder mb = ab.DefineDynamicModule("CalliHelper.dll");
+
+            ConstructorInfo ci = typeof(CLSCompliantAttribute).GetConstructor(new Type[] { typeof(bool) });
+            CustomAttributeBuilder cb = new CustomAttributeBuilder(ci, new object[] { true });
+            mb.SetCustomAttribute(cb);
+
+            TypeBuilder tb = mb.DefineType("System.Web.Util.CalliHelper", TypeAttributes.NotPublic | TypeAttributes.Sealed);
+            MethodBuilder methb = tb.DefineMethod("EventArgMethod", MethodAttributes.Assembly | MethodAttributes.Static, typeof(void), new Type[] { typeof(IntPtr), typeof(object), typeof(object), typeof(EventArgs) });
+            ILGenerator ilg = methb.GetILGenerator();
+
+            ilg.Emit(OpCodes.Ldarg_1);
+            ilg.Emit(OpCodes.Ldarg_2);
+            ilg.Emit(OpCodes.Ldarg_3);
+            ilg.Emit(OpCodes.Ldarg_0);
+            ilg.EmitCalli(OpCodes.Calli, CallingConventions.HasThis, typeof(void), new Type[] { typeof(object), typeof(EventArgs) }, null);
+            ilg.Emit(OpCodes.Ret);
+
+            methb = tb.DefineMethod("ArglessMethod", MethodAttributes.Assembly | MethodAttributes.Static, typeof(void), new Type[] { typeof (IntPtr), typeof(object) });
+            ilg = methb.GetILGenerator();
+
+            ilg.Emit(OpCodes.Ldarg_1);
+            ilg.Emit(OpCodes.Ldarg_0);
+            ilg.EmitCalli(OpCodes.Calli, CallingConventions.HasThis, typeof(void), new Type[0], null);
+            ilg.Emit(OpCodes.Ret);
+
+            Type t = tb.CreateType();
+            ArglessFunctionCaller = (ArglessMethod)Delegate.CreateDelegate(typeof(ArglessMethod), t, "ArglessMethod", true);
+            EventArgFunctionCaller = (EventArgMethod)Delegate.CreateDelegate(typeof(EventArgMethod), t, "EventArgMethod", true);
+
+            //ab.Save("CalliHelper.dll");
+        }
+    }
+#endif // Reflection_Emit_Implementation
+}

external/referencesource/System.Web/Util/AssemblyUtil.cs

@@ -0,0 +1,31 @@
+//------------------------------------------------------------------------------
+// <copyright file="AssemblyUtil.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+using System;
+using System.Reflection;
+
+namespace System.Web.Util {
+    internal static class AssemblyUtil {
+        private const string _emptyFileVersion = "0.0.0.0";
+
+        public static string GetAssemblyFileVersion(Assembly assembly) {
+            AssemblyFileVersionAttribute[] attributes =
+                (AssemblyFileVersionAttribute[])assembly.GetCustomAttributes(typeof(AssemblyFileVersionAttribute), false);
+
+            string version;
+            if (attributes.Length > 0) {
+                version = attributes[0].Version;
+                if (String.IsNullOrEmpty(version)) {
+                    version = _emptyFileVersion;
+                }
+            }
+            else {
+                version = _emptyFileVersion;
+            }
+            return version;
+        }
+    }
+}

external/referencesource/System.Web/Util/BinaryCompatibility.cs

@@ -0,0 +1,42 @@
+//------------------------------------------------------------------------------
+// <copyright file="BinaryCompatibility.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Runtime.Versioning;
+
+    // This class contains utility methods that mimic the mscorlib internal System.Runtime.Versioning.BinaryCompatibility type.
+
+    internal sealed class BinaryCompatibility {
+
+        // We need to use this AppDomain key instead of AppDomainSetup.TargetFrameworkName since we don't want applications
+        // which happened to set TargetFrameworkName and are calling into ASP.NET APIs to suddenly start getting new behaviors.
+        internal const string TargetFrameworkKey = "ASPNET_TARGETFRAMEWORK";
+
+        // quick accessor for the current AppDomain's instance
+        public static readonly BinaryCompatibility Current = new BinaryCompatibility(AppDomain.CurrentDomain.GetData(TargetFrameworkKey) as FrameworkName);
+
+        public BinaryCompatibility(FrameworkName frameworkName) {
+            // parse version from FrameworkName, otherwise use a default value
+            Version version = VersionUtil.FrameworkDefault;
+            if (frameworkName != null && frameworkName.Identifier == ".NETFramework") {
+                version = frameworkName.Version;
+            }
+
+            TargetFramework = version;
+            TargetsAtLeastFramework45 = (version >= VersionUtil.Framework45);
+            TargetsAtLeastFramework451 = (version >= VersionUtil.Framework451);
+            TargetsAtLeastFramework452 = (version >= VersionUtil.Framework452);
+        }
+
+        public bool TargetsAtLeastFramework45 { get; private set; }
+        public bool TargetsAtLeastFramework451 { get; private set; }
+        public bool TargetsAtLeastFramework452 { get; private set; }
+
+        public Version TargetFramework { get; private set; }
+
+    }
+}

external/referencesource/System.Web/Util/CancellationTokenHelper.cs

@@ -0,0 +1,102 @@
+//------------------------------------------------------------------------------
+// <copyright file="CancellationTokenHelper.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Threading;
+
+    // Helper class for dealing with CancellationToken instances. Our Cancel and Dispose methods
+    // are fully thread-safe and will never block or throw, while a normal CancellationTokenSource
+    // doesn't make these guarantees.
+
+    internal sealed class CancellationTokenHelper : IDisposable {
+
+        private const int STATE_CREATED = 0;
+        private const int STATE_CANCELING = 1;
+        private const int STATE_CANCELED = 2;
+        private const int STATE_DISPOSING = 3;
+        private const int STATE_DISPOSED = 4; // terminal state
+
+        // A CancellationTokenHelper which is already marked as disposed; useful for avoiding
+        // allocations of CancellationTokenHelper instances which are never observed.
+        internal static readonly CancellationTokenHelper StaticDisposed = GetStaticDisposedHelper();
+
+        private readonly CancellationTokenSource _cts = new CancellationTokenSource();
+        private int _state;
+
+        public CancellationTokenHelper(bool canceled) {
+            if (canceled) {
+                _cts.Cancel();
+            }
+            _state = (canceled) ? STATE_CANCELED : STATE_CREATED;
+        }
+
+        internal bool IsCancellationRequested {
+            get { return _cts.IsCancellationRequested; }
+        }
+
+        internal CancellationToken Token {
+            get { return _cts.Token; }
+        }
+
+        // Cancels the token.
+        public void Cancel() {
+            if (Interlocked.CompareExchange(ref _state, STATE_CANCELING, STATE_CREATED) == STATE_CREATED) {
+                // Only allow cancellation if the token hasn't yet been canceled or disposed.
+                // Cancel on a ThreadPool thread so that we can release the original thread back to IIS.
+                // We can use UnsafeQUWI to avoid an extra ExecutionContext capture since CancellationToken already captures it.
+                ThreadPool.UnsafeQueueUserWorkItem(_ => {
+                    try {
+                        _cts.Cancel();
+                    }
+                    catch {
+                        // ---- all exceptions to avoid killing the worker process.
+                    }
+                    finally {
+                        if (Interlocked.CompareExchange(ref _state, STATE_CANCELED, STATE_CANCELING) == STATE_DISPOSING) {
+                            // A call to Dispose() came in on another thread while we were in the middle of a cancel
+                            // operation. That thread will no-op, so we'll dispose of it here.
+                            _cts.Dispose();
+                            Interlocked.Exchange(ref _state, STATE_DISPOSED);
+                        }
+                    }
+                }, null);
+            }
+        }
+
+        // Disposes of the token.
+        public void Dispose() {
+            // Only allow a single call to Dispose.
+            int originalState = Interlocked.Exchange(ref _state, STATE_DISPOSING);
+            switch (originalState) {
+                case STATE_CREATED:
+                case STATE_CANCELED:
+                    // If Cancel() hasn't yet been called or has already run to completion,
+                    // the underlying CTS guarantees that the Dispose method won't block
+                    // or throw, so we can just call it directly.
+                    _cts.Dispose();
+                    Interlocked.Exchange(ref _state, STATE_DISPOSED);
+                    break;
+
+                case STATE_DISPOSED:
+                    // If the object was already disposed, we need to reset the flag here
+                    // since we accidentally blew it away with the original Exchange.
+                    Interlocked.Exchange(ref _state, STATE_DISPOSED);
+                    break;
+
+                // Otherwise, the object is already canceling or disposing, so the
+                // other thread will handle the call to Dispose().
+            }
+        }
+
+        private static CancellationTokenHelper GetStaticDisposedHelper() {
+            CancellationTokenHelper helper = new CancellationTokenHelper(false);
+            helper.Dispose();
+            return helper;
+        }
+
+    }
+}

external/referencesource/System.Web/Util/CodePageUtils.cs

@@ -0,0 +1,97 @@
+//------------------------------------------------------------------------------
+// <copyright file="CodePageUtils.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System.Collections;
+    
+    //
+    // Utility class to help with determining if a given code page
+    // is ASCII compatible (preserves 0-127 Unicode characters as is)
+    //
+
+    internal static class CodePageUtils {
+
+        /*      The following array of ASCII compatible code pages
+                is generated by running this code on a machine that
+                has _many_ codepages installed:
+
+                using System;
+                using System.Collections;
+                using System.Text;
+                public class qq {
+                    public static void Main(string[] args) {
+                        ArrayList list = new ArrayList();
+                        byte[] bb = new byte[128]; for (int i = 0; i < 128; i++) bb[i] = (byte)i;
+                        String asciiString = Encoding.ASCII.GetString(bb);
+                        for (int i = 1; i < 100000; i++) {
+                            try {
+                                Encoding e = Encoding.GetEncoding(i);
+                                byte[] xx = e.GetBytes(asciiString);
+                                if (xx.Length == 128) {
+                                    bool good = true;
+                                    for (int j = 0; j < 128; j++) { if (bb[j] != xx[j]) { good = false; break; } }
+                                    if (good) list.Add(i);
+                                }
+                            }
+                            catch {}
+                        }
+                        int n = list.Count;
+                        Console.Write("private const int[] _asciiCompatCodePages = new int[" + n + "] {\r\n    ");
+                        for (int i = 0; i < n; i++) {
+                            Console.Write("{0,5}", list[i]);
+                            if (i < n-1) Console.Write(", ");
+                            if (((i+1) % 10) == 0) Console.Write("\r\n    ");
+                        }
+                        Console.Write("\r\n};\r\n");
+                    }
+                }
+
+        */
+
+        private static int[] _asciiCompatCodePages = new int[79] {
+              437,   708,   720,   737,   775,   850,   852,   855,   857,   858,
+              860,   861,   862,   863,   864,   865,   866,   869,   874,   932,
+              936,   949,   950,  1250,  1251,  1252,  1253,  1254,  1255,  1256,
+             1257,  1258,  1361, 10000, 10001, 10002, 10003, 10004, 10005, 10006,
+            10007, 10008, 10010, 10017, 10029, 10079, 10081, 10082, 20000, 20001,
+            20002, 20003, 20004, 20005, 20127, 20866, 20932, 20936, 20949, 21866,
+            28591, 28592, 28593, 28594, 28595, 28596, 28597, 28598, 28599, 28605,
+            38598, 50220, 50221, 50222, 50225, 50227, 51932, 51949, 65001
+        };
+
+        internal /*public*/ static bool IsAsciiCompatibleCodePage(int codepage) {
+            //alternatives to binary search considered
+            //Hashtable: static initialization increases startup up, perf relative
+            //Byte array would consume ~8K, but lookups constant
+            //with 80 entries, binary search limited to 7 indexes into array
+            int lo = 0;
+            int hi = 78;
+            while(lo <= hi) {
+                int i = (lo + hi) >> 1;
+                int c;
+                c = _asciiCompatCodePages[i] - codepage;
+                if (c == 0) return true; //i is the index of the item
+                if (c < 0) {
+                    lo = i + 1;
+                }
+                else {
+                    hi = i - 1;
+                }
+            }
+            return false; 
+            //lo is the index of the item immediately after 
+            //~lo returned in some implementations for false indicator with additional info
+        }
+
+        internal const int CodePageUT8 = 65001;
+    }
+
+
+
+}
+
+
+

external/referencesource/System.Web/Util/CountdownTask.cs

@@ -0,0 +1,54 @@
+//------------------------------------------------------------------------------
+// <copyright file="CountdownTask.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Threading;
+    using System.Threading.Tasks;
+
+    // This class is similar to CountdownEvent, but it uses Task under the covers
+    // instead of ManualResetEvent. When the internal counter hits zero, the Task
+    // is marked as complete.
+    //
+    // This type is thread-safe. Error checking is not performed in RET builds.
+
+    internal sealed class CountdownTask {
+
+        private int _pendingCount;
+        private readonly TaskCompletionSource<object> _tcs = new TaskCompletionSource<object>();
+
+        public CountdownTask(int initialCount) {
+            AddCount(initialCount);
+        }
+
+        public int CurrentCount {
+            get { return _pendingCount; }
+        }
+
+        public Task Task {
+            get { return _tcs.Task; }
+        }
+
+        private void AddCount(int delta) {
+            int newCount = Interlocked.Add(ref _pendingCount, delta);
+            Debug.Assert(newCount >= 0, "The counter should never hit a negative value.");
+
+            if (newCount == 0) {
+                bool success = _tcs.TrySetResult(null);
+                Debug.Assert(success, "TrySetResult shouldn't have been already called.");
+            }
+        }
+
+        public void MarkOperationCompleted() {
+            AddCount(-1);
+        }
+
+        public void MarkOperationPending() {
+            AddCount(+1);
+        }
+
+    }
+}

external/referencesource/System.Web/Util/CultureUtil.cs

@@ -0,0 +1,67 @@
+//------------------------------------------------------------------------------
+// <copyright file="CultureUtil.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Globalization;
+
+    // This class contains helper methods for obtaining a CultureInfo instance from a list of candidates.
+
+    internal static class CultureUtil {
+
+        // Given a single culture name, attempts to turn it into a CultureInfo.
+        // If 'requireSpecific' is set, this method attempts to return an object where IsNeutral = false.
+        public static CultureInfo CreateReadOnlyCulture(string cultureName, bool requireSpecific) {
+            if (requireSpecific) {
+                return HttpServerUtility.CreateReadOnlySpecificCultureInfo(cultureName);
+            }
+            else {
+                return HttpServerUtility.CreateReadOnlyCultureInfo(cultureName);
+            }
+        }
+
+        // Given a list of culture names, loop through them until we find one we understand.
+        // We expect 'cultureNames' to be the raw Accept-Languages header value, as we'll strip q-values.
+        // Otherwise equivalent to the single-element overload.
+        public static CultureInfo CreateReadOnlyCulture(string[] cultureNames, bool requireSpecific) {
+            return ExtractCultureImpl(cultureNames, requireSpecific, AppSettings.MaxAcceptLanguageFallbackCount);
+        }
+
+        // for unit testing, uses 'maxCount' instead of the <appSettings> switch
+        internal static CultureInfo ExtractCultureImpl(string[] cultureNames, bool requireSpecific, int maxCount) {
+            int lastIndex = Math.Min(cultureNames.Length, maxCount) - 1;
+
+            for (int i = 0; i < cultureNames.Length; i++) {
+                string candidate = StripQValue(cultureNames[i]);
+
+                try {
+                    return CreateReadOnlyCulture(candidate, requireSpecific);
+                }
+                catch (CultureNotFoundException) {
+                    // If this is the last iteration before giving up, let the exception propagate upward.
+                    // Otherwise just ---- and move on to the next candidate.
+                    if (i == lastIndex) {
+                        throw;
+                    }
+                }
+            }
+
+            return null;
+        }
+
+        // Given an input "foo;q=xx", returns "foo".
+        private static string StripQValue(string input) {
+            if (input != null) {
+                int indexOfSemicolon = input.IndexOf(';');
+                if (indexOfSemicolon >= 0) {
+                    return input.Substring(0, indexOfSemicolon);
+                }
+            }
+            return input;
+        }
+
+    }
+}

external/referencesource/System.Web/Util/DateTimeUtil.cs

@@ -0,0 +1,52 @@
+//------------------------------------------------------------------------------
+// <copyright file="FileChangesMonitor.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+
+    using System;
+
+    internal sealed class DateTimeUtil {
+        private DateTimeUtil() {}
+
+        const long FileTimeOffset = 504911232000000000;
+        static readonly DateTime    MinValuePlusOneDay = DateTime.MinValue.AddDays(1);
+        static readonly DateTime    MaxValueMinusOneDay = DateTime.MaxValue.AddDays(-1);
+
+        static internal DateTime FromFileTimeToUtc(long filetime) {
+            long universalTicks = filetime + FileTimeOffset;
+            // Dev10 733288: Caching: behavior change for CacheDependency when using UseMemoryCache=1
+            // ObjectCacheHost converts DateTime to a DateTimeOffset, and the conversion requires
+            // that DateTimeKind be set correctly
+            return new DateTime(universalTicks, DateTimeKind.Utc);
+        }
+
+        static internal DateTime ConvertToUniversalTime(DateTime localTime) {
+            if (localTime < MinValuePlusOneDay) {
+                return DateTime.MinValue;
+            }
+
+            if (localTime > MaxValueMinusOneDay) {
+                return DateTime.MaxValue;
+            }
+
+            return localTime.ToUniversalTime();
+        }
+
+        static internal DateTime ConvertToLocalTime(DateTime utcTime) {
+            if (utcTime < MinValuePlusOneDay) {
+                return DateTime.MinValue;
+            }
+
+            if (utcTime > MaxValueMinusOneDay) {
+                return DateTime.MaxValue;
+            }
+
+            return utcTime.ToLocalTime();
+        }
+    }
+}
+
+

external/referencesource/System.Web/Util/DisposableAction.cs

@@ -0,0 +1,33 @@
+//------------------------------------------------------------------------------
+// <copyright file="DisposableAction.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+    using System.Threading;
+
+    // Helper class for wrapping a continuation inside an IDisposable.
+    // This class is thread-safe.
+
+    internal sealed class DisposableAction : IDisposable {
+
+        public static readonly DisposableAction Empty = new DisposableAction(null);
+
+        private Action _disposeAction;
+
+        public DisposableAction(Action disposeAction) {
+            _disposeAction = disposeAction;
+        }
+
+        public void Dispose() {
+            // Interlocked allows the continuation to be executed only once
+            Action continuation = Interlocked.Exchange(ref _disposeAction, null);
+            if (continuation != null) {
+                continuation();
+            }
+        }
+
+    }
+}

external/referencesource/System.Web/Util/DoNotResetAttribute.cs

@@ -0,0 +1,16 @@
+//------------------------------------------------------------------------------
+// <copyright file="DoNotResetAttribute.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.Web.Util {
+    using System;
+
+    // If this attribute is applied to a field, it will not be reset by a call to ReflectionUtil.Reset().
+    
+    [AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
+    internal sealed class DoNotResetAttribute : Attribute {
+    }
+
+}

external/referencesource/System.Web/Util/DoubleLink.cs

@@ -0,0 +1,65 @@
+//------------------------------------------------------------------------------
+// <copyright file="DoubleLink.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * DoubleLink
+ * 
+ * Copyright (c) 1998-1999, Microsoft Corporation
+ * 
+ */
+
+namespace System.Web.Util {
+    using System.Runtime.Serialization.Formatters;
+
+    internal class DoubleLink {
+        internal DoubleLink    _next, _prev;
+        internal Object           Item;
+
+        internal DoubleLink() {
+            _next = _prev = this;
+        }
+        internal DoubleLink(Object item)  : this() {
+            this.Item = item;
+        }
+        internal DoubleLink Next {get {return _next;}}
+
+        internal void InsertAfter(DoubleLink after) {
+            this._prev = after;
+            this._next = after._next;
+            after._next = this;
+            this._next._prev = this;
+        }
+
+        internal void InsertBefore(DoubleLink before) {
+            this._prev = before._prev;
+            this._next = before;
+            before._prev = this;
+            this._prev._next = this;
+        }
+
+        internal void Remove() {
+            this._prev._next = this._next;
+            this._next._prev = this._prev;
+            _next = _prev = this;
+        }
+
+#if DBG
+        internal virtual void DebugValidate() {
+            Debug.CheckValid(this._next != this || this._prev == this, "Invalid link");
+        }
+
+        internal virtual string DebugDescription(string indent) {
+            string desc;
+
+            desc = indent + "_next=" + _next + ", _prev=" + _prev + "\nItem=";
+            desc += Debug.GetDescription(Item, indent + "    ");
+
+            return desc;
+        }
+#endif
+    }
+
+}

external/referencesource/System.Web/Util/DoubleLinkList.cs

@@ -0,0 +1,114 @@
+//------------------------------------------------------------------------------
+// <copyright file="DoubleLinkList.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * DoubleLinkList
+ * 
+ * Copyright (c) 1998-1999, Microsoft Corporation
+ * 
+ */
+
+namespace System.Web.Util {
+    using System.Text;
+    using System.Runtime.Serialization.Formatters;
+
+    internal class DoubleLinkList : DoubleLink {
+        internal DoubleLinkList() {
+        }
+
+        internal bool IsEmpty() {
+            return _next == this;
+        }
+
+        internal virtual void InsertHead(DoubleLink entry) {
+            entry.InsertAfter(this);
+        }
+        internal virtual void InsertTail(DoubleLink entry) {
+            entry.InsertBefore(this);
+        }
+
+        internal DoubleLinkListEnumerator GetEnumerator() {
+            return new DoubleLinkListEnumerator(this);
+        }
+
+#if DBG
+        internal override void DebugValidate() {
+            DoubleLink  l1, l2;
+
+            base.DebugValidate();
+
+            /*
+             * Detect loops by moving one pointer forward 2 for every 1
+             * of the other.
+             */
+
+            l1 = l2 = this;
+            for (;;) {
+                /* move l2 forward */
+                l2 = l2._next;
+                if (l2 == this)
+                    break;
+
+                Debug.CheckValid(l2 != l1, "Invalid loop in list, first move.");
+                l2.DebugValidate();
+
+                /* move l2 forward again */
+                l2 = l2._next;
+                if (l2 == this)
+                    break;
+
+                Debug.CheckValid(l2 != l1, "Invalid loop in list, second move.");
+                l2.DebugValidate();
+
+                /* move l1 forward */
+                l1 = l1._next;
+            }
+        }
+
+        internal override string DebugDescription(String indent) {
+            string                      desc;
+            DoubleLinkListEnumerator    lenum;
+            int                         c;
+            StringBuilder               sb;
+            string                      i2 = indent + "    ";
+
+            if (IsEmpty()) {
+                desc = indent + "DoubleLinkList is empty\n";
+            }
+            else {
+                c = Length;
+
+                sb = new StringBuilder(indent + "DoubleLinkList has " + c + " entries.\n");
+                lenum = GetEnumerator();
+                while (lenum.MoveNext()) {
+                    sb.Append(Debug.GetDescription(lenum.GetDoubleLink(), i2));
+                }
+
+                desc = sb.ToString();
+            }
+
+            return desc;
+        }
+#endif    
+
+        internal int Length {
+            get {
+                DoubleLinkListEnumerator    lenum;
+                int                         c;
+
+                Debug.Validate(this);
+
+                c = 0;
+                lenum = GetEnumerator();
+                while (lenum.MoveNext()) {
+                    c++;
+                }
+
+                return c;
+            }
+        }
+    }
+}

external/referencesource/System.Web/Util/DoubleLinkListEnumerator.cs

@@ -0,0 +1,53 @@
+//------------------------------------------------------------------------------
+// <copyright file="DoubleLinkListEnumerator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * DoubleLinkList
+ * 
+ * Copyright (c) 1998-1999, Microsoft Corporation
+ * 
+ */
+
+namespace System.Web.Util {
+    using System.Runtime.Serialization.Formatters;
+    using System.Collections;
+
+    internal class DoubleLinkListEnumerator : IEnumerator {
+        private DoubleLinkList  _list;
+        private DoubleLink      _current;
+
+        internal DoubleLinkListEnumerator(DoubleLinkList list) {
+            _list = list;
+            _current = list;
+        }
+
+        public void Reset() {
+            _current = _list;
+        }
+
+        public bool MoveNext() {
+            if (_current.Next == _list) {
+                _current = null;
+                return false;
+            }
+
+            _current = _current.Next;
+            return true;
+        }
+
+        public Object Current {
+            get { 
+                if (_current == null || _current == _list)
+                    throw new InvalidOperationException();
+                return _current.Item;
+            }
+        }
+
+        internal DoubleLink GetDoubleLink() {
+            return _current;
+        }
+    }
+}