[mono.git] / mcs / class / System.Web / System.Web / HttpApplication.cs

//
// System.Web.HttpApplication.cs 
//
// Author:
//      Miguel de Icaza (miguel@novell.com)
//      Gonzalo Paniagua (gonzalo@ximian.com)
//    
//
// Copyright (C) 2005 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// The Application Processing Pipeline.
// 
//     The Http application pipeline implemented in this file is a
//     beautiful thing.  The application pipeline invokes a number of
//     hooks at various stages of the processing of a request.  These
//     hooks can be either synchronous or can be asynchronous.
//     
//     The pipeline must ensure that every step is completed before
//     moving to the next step.  A trivial thing for synchronous
//     hooks, but asynchronous hooks introduce an extra layer of
//     complexity: when the hook is invoked, the thread must
//     relinquish its control so that the thread can be reused in
//     another operation while waiting.
//
//     To implement this functionality we used C# iterators manually;
//     we drive the pipeline by executing the various hooks from the
//     `RunHooks' routine which is an enumerator that will yield the
//     value `false' if execution must proceed or `true' if execution
//     must be stopped.
//
//     By yielding values we can suspend execution of RunHooks.
//
//     Special attention must be given to `in_begin' and `must_yield'
//     variables.  These are used in the case that an async hook
//     completes synchronously as its important to not yield in that
//     case or we would hang.
//    
//     Many of Mono modules used to be declared async, but they would
//     actually be completely synchronous, this might resurface in the
//     future with other modules.
//
// TODO:
//    Events Disposed
//

using System.IO;
using System.Collections;
using System.ComponentModel;
using System.Configuration;
using System.Globalization;
using System.Reflection;
using System.Security.Permissions;
using System.Security.Principal;
using System.Threading;
using System.Web.Caching;
using System.Web.Configuration;
using System.Web.SessionState;
using System.Web.UI;

#if TARGET_J2EE
using Mainsoft.Web;
#endif
        
namespace System.Web {

        // CAS
        [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
        [AspNetHostingPermission (SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
        // attributes
        [ToolboxItem(false)]
        public class HttpApplication : IHttpAsyncHandler, IHttpHandler, IComponent, IDisposable {
                object this_lock = new object();

                internal static readonly string [] BinDirs = {"Bin", "bin"};
                
                HttpContext context;
                HttpSessionState session;
                ISite isite;

                // The source, and the exposed API (cache).
                HttpModuleCollection modcoll;

                string assemblyLocation;

                //
                // The factory for the handler currently running.
                //
                IHttpHandlerFactory factory;

                //
                // Whether the thread culture is to be auto-set.
                // Used only in the 2.0 profile, always false for 1.x
                //
                bool autoCulture;
                bool autoUICulture;
                
                //
                // Whether the pipeline should be stopped
                //
                bool stop_processing;

                //
                // The Pipeline
                //
                IEnumerator pipeline;

                // To flag when we are done processing a request from BeginProcessRequest.
                ManualResetEvent done;

                // The current IAsyncResult for the running async request handler in the pipeline
                AsyncRequestState begin_iar;

                // Tracks the current AsyncInvocation being dispatched
                AsyncInvoker current_ai;

                // We don't use the EventHandlerList here, but derived classes might do
                EventHandlerList events;

                // Culture and IPrincipal
                CultureInfo app_culture;
                CultureInfo appui_culture;
                CultureInfo prev_app_culture;
                CultureInfo prev_appui_culture;
                IPrincipal prev_user;

                static bool _runningOnWindows;
                
#if NET_2_0
#if TARGET_J2EE
                const string initialization_exception_key = "System.Web.HttpApplication.initialization_exception";
                static Exception initialization_exception {
                        get { return (Exception) AppDomain.CurrentDomain.GetData (initialization_exception_key); }
                        set { AppDomain.CurrentDomain.SetData (initialization_exception_key, value); }
                }
#else
                static Exception initialization_exception;
#endif
                bool removeConfigurationFromCache;
#endif

                //
                // These are used to detect the case where the EndXXX method is invoked
                // from within the BeginXXXX delegate, so we detect whether we kick the
                // pipeline from here, or from the the RunHook routine
                //
                bool must_yield;
                bool in_begin;

                static HttpApplication ()
                {
                        PlatformID pid = Environment.OSVersion.Platform;
                        _runningOnWindows = ((int) pid != 128 && (int) pid != 4);
                }
                
                public HttpApplication ()
                {
                        done = new ManualResetEvent (false);
                }
                
                internal void InitOnce (bool full_init)
                {
                        lock (this_lock) {
                                if (modcoll != null)
                                        return;

#if NET_2_0
                                HttpModulesSection modules;
                                modules = (HttpModulesSection) WebConfigurationManager.GetSection ("system.web/httpModules", HttpRuntime.AppDomainAppVirtualPath);
#else
                                ModulesConfiguration modules;

                                modules = (ModulesConfiguration) HttpContext.GetAppConfig ("system.web/httpModules");
#endif

                                modcoll = modules.LoadModules (this);

                                if (full_init) {
                                        HttpApplicationFactory.AttachEvents (this);
                                        Init ();
                                }
                        }
                }

                internal string AssemblyLocation {
                        get {
                                if (assemblyLocation == null)
                                        assemblyLocation = GetType ().Assembly.Location;
                                return assemblyLocation;
                        }
                }

#if NET_2_0
                internal static Exception InitializationException {
                        get { return initialization_exception; }
                }
#endif

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpApplicationState Application {
                        get {
                                return HttpApplicationFactory.ApplicationState;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpContext Context {
                        get {
                                return context;
                        }
                }
                                         
                protected EventHandlerList Events {
                        get {
                                if (events == null)
                                        events = new EventHandlerList ();

                                return events;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpModuleCollection Modules {
                        [AspNetHostingPermission (SecurityAction.Demand, Level = AspNetHostingPermissionLevel.High)]
                        get {
                                if (modcoll == null)
                                        modcoll = new HttpModuleCollection ();
                                
                                return modcoll;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpRequest Request {
                        get {
                                if (context == null)
                                        throw new HttpException (Locale.GetText ("No context is available."));

                                if (false == HttpApplicationFactory.ContextAvailable)
                                        throw new HttpException (Locale.GetText ("Request is not available in this context."));

                                return context.Request;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpResponse Response {
                        get {
                                if (context == null)
                                        throw new HttpException (Locale.GetText ("No context is available."));

                                if (false == HttpApplicationFactory.ContextAvailable)
                                        throw new HttpException (Locale.GetText ("Response is not available in this context."));

                                return context.Response;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpServerUtility Server {
                        get {
                                if (context != null)
                                        return context.Server;

                                //
                                // This is so we can get the Server and call a few methods
                                // which are not context sensitive, see HttpServerUtilityTest
                                //
                                return new HttpServerUtility ((HttpContext) null);
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public HttpSessionState Session {
                        get {
                                // Only used for Session_End
                                if (session != null)
                                        return session;

                                if (context == null)
                                        throw new HttpException (Locale.GetText ("No context is available."));
                                return context.Session;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
#if NET_2_0
                public ISite Site {
#else
                public virtual ISite Site {
#endif
                        get {
                                return isite;
                        }

                        set {
                                isite = value;
                        }
                }

                [Browsable (false)]
                [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
                public IPrincipal User {
                        get {
                                if (context == null)
                                        throw new HttpException (Locale.GetText ("No context is available."));
                                if (context.User == null)
                                        throw new HttpException (Locale.GetText ("No currently authenticated user."));
                                
                                return context.User;
                        }
                }
                
                public virtual event EventHandler Disposed;
                public virtual event EventHandler Error;

                public event EventHandler PreSendRequestHeaders;
                internal void TriggerPreSendRequestHeaders ()
                {
                        if (PreSendRequestHeaders != null)
                                PreSendRequestHeaders (this, EventArgs.Empty);
                }

                public event EventHandler PreSendRequestContent;
                internal void TriggerPreSendRequestContent ()
                {
                        if (PreSendRequestContent != null)
                                PreSendRequestContent (this, EventArgs.Empty);
                }
                
                public event EventHandler AcquireRequestState;
                public void AddOnAcquireRequestStateAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        AcquireRequestState += new EventHandler (invoker.Invoke);
                }

                public event EventHandler AuthenticateRequest;
                public void AddOnAuthenticateRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        AuthenticateRequest += new EventHandler (invoker.Invoke);
                }

                public event EventHandler AuthorizeRequest;
                public void AddOnAuthorizeRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        AuthorizeRequest += new EventHandler (invoker.Invoke);
                }

                public event EventHandler BeginRequest;
                public void AddOnBeginRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        BeginRequest += new EventHandler (invoker.Invoke);
                }

                public event EventHandler EndRequest;
                public void AddOnEndRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        EndRequest += new EventHandler (invoker.Invoke);
                }
                
                public event EventHandler PostRequestHandlerExecute;
                public void AddOnPostRequestHandlerExecuteAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        PostRequestHandlerExecute += new EventHandler (invoker.Invoke);
                }

                public event EventHandler PreRequestHandlerExecute;
                public void AddOnPreRequestHandlerExecuteAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        PreRequestHandlerExecute += new EventHandler (invoker.Invoke);
                }

                public event EventHandler ReleaseRequestState;
                public void AddOnReleaseRequestStateAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        ReleaseRequestState += new EventHandler (invoker.Invoke);
                }

                public event EventHandler ResolveRequestCache;
                public void AddOnResolveRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        ResolveRequestCache += new EventHandler (invoker.Invoke);
                }

                public event EventHandler UpdateRequestCache;
                public void AddOnUpdateRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh);
                        UpdateRequestCache += new EventHandler (invoker.Invoke);
                }

#if NET_2_0
                public event EventHandler PostAuthenticateRequest;
                public void AddOnPostAuthenticateRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostAuthenticateRequestAsync (bh, eh, null);
                }
                        
                public void AddOnPostAuthenticateRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostAuthenticateRequest += new EventHandler (invoker.Invoke);
                }
                
                public event EventHandler PostAuthorizeRequest;
                public void AddOnPostAuthorizeRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostAuthorizeRequestAsync (bh, eh, null);
                }
                
                public void AddOnPostAuthorizeRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostAuthorizeRequest += new EventHandler (invoker.Invoke);
                }

                public event EventHandler PostResolveRequestCache;
                public void AddOnPostResolveRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostResolveRequestCacheAsync (bh, eh, null);
                }
                
                public void AddOnPostResolveRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostResolveRequestCache += new EventHandler (invoker.Invoke);
                }

                public event EventHandler PostMapRequestHandler;
                public void AddOnPostMapRequestHandlerAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostMapRequestHandlerAsync (bh, eh, null);
                }
                
                public void AddOnPostMapRequestHandlerAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostMapRequestHandler += new EventHandler (invoker.Invoke);
                }
                
                public event EventHandler PostAcquireRequestState;
                public void AddOnPostAcquireRequestStateAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostAcquireRequestStateAsync (bh, eh, null);
                }
                
                public void AddOnPostAcquireRequestStateAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostAcquireRequestState += new EventHandler (invoker.Invoke);
                }
                
                public event EventHandler PostReleaseRequestState;
                public void AddOnPostReleaseRequestStateAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostReleaseRequestStateAsync (bh, eh, null);
                }
                
                public void AddOnPostReleaseRequestStateAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostReleaseRequestState += new EventHandler (invoker.Invoke);
                }

                public event EventHandler PostUpdateRequestCache;
                public void AddOnPostUpdateRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostUpdateRequestCacheAsync (bh, eh, null);
                }
                
                public void AddOnPostUpdateRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostUpdateRequestCache += new EventHandler (invoker.Invoke);
                }

                //
                // The new overloads that take a data parameter
                //
                public void AddOnAcquireRequestStateAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        AcquireRequestState += new EventHandler (invoker.Invoke);
                }

                public void AddOnAuthenticateRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        AuthenticateRequest += new EventHandler (invoker.Invoke);
                }

                public void AddOnAuthorizeRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        AuthorizeRequest += new EventHandler (invoker.Invoke);
                }

                public void AddOnBeginRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        BeginRequest += new EventHandler (invoker.Invoke);
                }

                public void AddOnEndRequestAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        EndRequest += new EventHandler (invoker.Invoke);
                }
                
                public void AddOnPostRequestHandlerExecuteAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PostRequestHandlerExecute += new EventHandler (invoker.Invoke);
                }

                public void AddOnPreRequestHandlerExecuteAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        PreRequestHandlerExecute += new EventHandler (invoker.Invoke);
                }

                public void AddOnReleaseRequestStateAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        ReleaseRequestState += new EventHandler (invoker.Invoke);
                }

                public void AddOnResolveRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        ResolveRequestCache += new EventHandler (invoker.Invoke);
                }

                public void AddOnUpdateRequestCacheAsync (BeginEventHandler bh, EndEventHandler eh, object data)
                {
                        AsyncInvoker invoker = new AsyncInvoker (bh, eh, data);
                        UpdateRequestCache += new EventHandler (invoker.Invoke);
                }

                // Added in 2.0 SP1
                // They are for use with the IIS7 integrated mode, but have been added for compatibility
                public event EventHandler LogRequest;
                public void AddOnLogRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnLogRequestAsync (bh, eh, null);
                }
                
                public void AddOnLogRequestAsync (BeginEventHandler beginHandler, EndEventHandler endHandler, object state)
                {
                        AsyncInvoker invoker = new AsyncInvoker (beginHandler, endHandler, state);
                        LogRequest += new EventHandler (invoker.Invoke);
                }

                public event EventHandler MapRequestHandler;
                public void AddOnMapRequestHandlerAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnMapRequestHandlerAsync (bh, eh, null);
                }

                public void AddOnMapRequestHandlerAsync (BeginEventHandler beginHandler, EndEventHandler endHandler, object state)
                {
                        AsyncInvoker invoker = new AsyncInvoker (beginHandler, endHandler, state);
                        MapRequestHandler += new EventHandler (invoker.Invoke);
                }

                public event EventHandler PostLogRequest;
                public void AddOnPostLogRequestAsync (BeginEventHandler bh, EndEventHandler eh)
                {
                        AddOnPostLogRequestAsync (bh, eh, null);
                }

                public void AddOnPostLogRequestAsync (BeginEventHandler beginHandler, EndEventHandler endHandler, object state)
                {
                        AsyncInvoker invoker = new AsyncInvoker (beginHandler, endHandler, state);
                        PostLogRequest += new EventHandler (invoker.Invoke);
                }

#endif
                
                internal event EventHandler DefaultAuthentication;
                
                //
                // Bypass all the event on the Http pipeline and go directly to EndRequest
                //
                public void CompleteRequest ()
                {
                        stop_processing = true;
                }

                internal bool RequestCompleted {
                        set { stop_processing = value; }
                }

                public virtual void Dispose ()
                {
                        if (modcoll != null) {
                                for (int i = modcoll.Count - 1; i >= 0; i--) {
                                        modcoll.Get (i).Dispose ();
                                }
                                modcoll = null;
                        }

                        if (Disposed != null)
                                Disposed (this, EventArgs.Empty);
                        
                        done.Close ();
                        done = null;
                }

                public virtual string GetVaryByCustomString (HttpContext context, string custom)
                {
                        if (custom == null) // Sigh
                                throw new NullReferenceException ();

                        if (0 == String.Compare (custom, "browser", true, CultureInfo.InvariantCulture))
                                return context.Request.Browser.Type;

                        return null;
                }

                //
                // If we catch an error, queue this error
                //
                void ProcessError (Exception e)
                {
                        bool first = context.Error == null;
                        context.AddError (e);
                        if (first){
                                if (Error != null){
                                        try {
                                                Error (this, EventArgs.Empty);
                                        } catch (ThreadAbortException taex){
                                                context.ClearError ();
                                                if (FlagEnd.Value == taex.ExceptionState)
                                                        // This happens on Redirect() or End()
                                                        Thread.ResetAbort ();
                                                else
                                                        // This happens on Thread.Abort()
                                                        context.AddError (taex);
                                        } catch (Exception ee){
                                                context.AddError (ee);
                                        }
                                }
                        }
                        stop_processing = true;
#if NET_2_0
                        // we want to remove configuration from the cache in case of 
                        // invalid resource not exists to prevent DOS attack.
                        HttpException httpEx = e as HttpException;
                        if (httpEx != null && httpEx.GetHttpCode () == 404) {
                                removeConfigurationFromCache = true;
                        }
#endif
                }
                
                //
                // Ticks the clock: next step on the pipeline.
                //
                internal void Tick ()
                {
                        try {
                                if (pipeline.MoveNext ()){
                                        if ((bool)pipeline.Current)
                                                PipelineDone ();
                                }
                        } catch (ThreadAbortException taex) {
                                object obj = taex.ExceptionState;
                                Thread.ResetAbort ();
                                stop_processing = true;
                                if (obj is StepTimeout)
                                        ProcessError (new HttpException ("The request timed out."));
                                else {
                                        context.ClearError ();
                                        if (FlagEnd.Value != obj)
                                                context.AddError (taex);
                                }

                                PipelineDone ();
                        } catch (Exception e) {
                                stop_processing = true;
                                ProcessError (e);
                                PipelineDone ();
                        }
                }

                void Resume ()
                {
                        if (in_begin)
                                must_yield = false;
                        else
                                Tick ();
                }
                
                //
                // Invoked when our async callback called from RunHooks completes,
                // we restart the pipeline here.
                //
                void async_callback_completed_cb (IAsyncResult ar)
                {
                        if (current_ai.end != null){
                                try {
                                        current_ai.end (ar);
                                } catch (Exception e) {
                                        ProcessError (e);
                                }
                        }

                        Resume ();
                }

                void async_handler_complete_cb (IAsyncResult ar)
                {
                        IHttpAsyncHandler async_handler = ((IHttpAsyncHandler) ar.AsyncState);

                        try {
                                async_handler.EndProcessRequest (ar);
                        } catch (Exception e){
                                ProcessError (e);
                        }
                        
                        Resume ();
                }
                
                //
                // This enumerator yields whether processing must be stopped:
                //    true:  processing of the pipeline must be stopped
                //    false: processing of the pipeline must not be stopped
                //
                IEnumerable RunHooks (Delegate list)
                {
                        Delegate [] delegates = list.GetInvocationList ();

                        foreach (EventHandler d in delegates){
                                if (d.Target != null && (d.Target is AsyncInvoker)){
                                        current_ai = (AsyncInvoker) d.Target;

                                        try {
                                                must_yield = true;
                                                in_begin = true;
                                                context.BeginTimeoutPossible ();
                                                current_ai.begin (this, EventArgs.Empty, async_callback_completed_cb, current_ai.data);
                                        } finally {
                                                in_begin = false;
                                                context.EndTimeoutPossible ();
                                        }

                                        //
                                        // If things are still moving forward, yield this
                                        // thread now
                                        //
                                        if (must_yield)
                                                yield return stop_processing;
                                        else if (stop_processing)
                                                yield return true;
                                } else {
                                        try {
                                                context.BeginTimeoutPossible ();
                                                d (this, EventArgs.Empty);
                                        } finally {
                                                context.EndTimeoutPossible ();
                                        }
                                        if (stop_processing)
                                                yield return true;
                                }
                        }
                }

                static void FinalErrorWrite (HttpResponse response, string error)
                {
                        try {
                                response.Write (error);
                                response.Flush (true);
                        } catch {
                                response.Close ();
                        }
                }

                void OutputPage ()
                {
                        if (context.Error == null){
                                try {
                                        context.Response.Flush (true);
                                } catch (Exception e){
                                        context.AddError (e);
                                }
                        }

                        Exception error = context.Error;
                        if (error != null){
#if TARGET_J2EE
                                Console.WriteLine (error.ToString ());
#endif
                                HttpResponse response = context.Response;

                                if (!response.HeadersSent){
                                        response.ClearHeaders ();
                                        response.ClearContent ();

                                        if (error is HttpException){
                                                response.StatusCode = ((HttpException)error).GetHttpCode ();
                                        } else {
                                                error = new HttpException ("", error);
                                                response.StatusCode = 500;
                                        }
                                        HttpException httpEx = (HttpException) error;
                                        if (!RedirectCustomError (ref httpEx))
                                                FinalErrorWrite (response, httpEx.GetHtmlErrorMessage ());
                                        else
                                                response.Flush (true);
                                } else {
                                        if (!(error is HttpException))
                                                error = new HttpException ("", error);
                                        FinalErrorWrite (response, ((HttpException) error).GetHtmlErrorMessage ());
                                }
                        }
                        
                }
                
                //
                // Invoked at the end of the pipeline execution
                //
                void PipelineDone ()
                {
                        try {
                                if (EndRequest != null)
                                        EndRequest (this, EventArgs.Empty);
                        } catch (Exception e){
                                ProcessError (e);
                        }

                        try {
                                OutputPage ();
                        } catch (Exception e) {
                                Console.WriteLine ("Internal error: OutputPage threw an exception " + e);
                        } finally {
                                context.WorkerRequest.EndOfRequest();
                                if (factory != null && context.Handler != null){
                                        factory.ReleaseHandler (context.Handler);
                                        context.Handler = null;
                                        factory = null;
                                }
#if NET_2_0
                                context.PopHandler ();
#endif
                                // context = null; -> moved to PostDone
                                pipeline = null;
                                current_ai = null;
                        }
                        PostDone ();

                        if (begin_iar != null)
                                begin_iar.Complete ();
                        else
                                done.Set ();
                }
                
                //
                // Events fired as described in `Http Runtime Support, HttpModules,
                // Handling Public Events'
                //
                IEnumerator Pipeline ()
                {
                        if (stop_processing)
                                yield return true;

                        if (BeginRequest != null)
                                foreach (bool stop in RunHooks (BeginRequest))
                                        yield return stop;

                        if (AuthenticateRequest != null)
                                foreach (bool stop in RunHooks (AuthenticateRequest))
                                        yield return stop;

                        if (DefaultAuthentication != null)
                                foreach (bool stop in RunHooks (DefaultAuthentication))
                                        yield return stop;

#if NET_2_0
                        if (PostAuthenticateRequest != null)
                                foreach (bool stop in RunHooks (PostAuthenticateRequest))
                                        yield return stop;
#endif
                        if (AuthorizeRequest != null)
                                foreach (bool stop in RunHooks (AuthorizeRequest))
                                        yield return stop;
#if NET_2_0
                        if (PostAuthorizeRequest != null)
                                foreach (bool stop in RunHooks (PostAuthorizeRequest))
                                        yield return stop;
#endif

                        if (ResolveRequestCache != null)
                                foreach (bool stop in RunHooks (ResolveRequestCache))
                                        yield return stop;

#if NET_2_0
                        if (PostResolveRequestCache != null)
                                foreach (bool stop in RunHooks (PostResolveRequestCache))
                                        yield return stop;

                        // As per http://msdn2.microsoft.com/en-us/library/bb470252(VS.90).aspx
                        if (MapRequestHandler != null)
                                foreach (bool stop in RunHooks (MapRequestHandler))
                                        yield return stop;
#endif
                        
                        // Obtain the handler for the request.
                        IHttpHandler handler = null;
                        try {
                                handler = GetHandler (context, context.Request.FilePath);
                                context.Handler = handler;
#if NET_2_0
                                context.PushHandler (handler);
#endif
                        } catch (FileNotFoundException fnf){
                                if (context.Request.IsLocal)
                                        ProcessError (new HttpException (404, String.Format ("File not found {0}", fnf.FileName), fnf));
                                else
                                        ProcessError (new HttpException (404, "File not found: " + Path.GetFileName (fnf.FileName)));
                        } catch (DirectoryNotFoundException dnf){
                                if (!context.Request.IsLocal)
                                        dnf = null; // Do not "leak" real path information
                                ProcessError (new HttpException (404, "Directory not found", dnf));
                        } catch (Exception e) {
                                ProcessError (e);
                        }

                        if (stop_processing)
                                yield return true;

#if NET_2_0
                        if (PostMapRequestHandler != null)
                                foreach (bool stop in RunHooks (PostMapRequestHandler))
                                        yield return stop;
                        
#endif
                        if (AcquireRequestState != null){
                                foreach (bool stop in RunHooks (AcquireRequestState))
                                        yield return stop;
                        }

#if NET_2_0
                        if (PostAcquireRequestState != null){
                                foreach (bool stop in RunHooks (PostAcquireRequestState))
                                        yield return stop;
                        }
#endif
                        
                        //
                        // From this point on, we need to ensure that we call
                        // ReleaseRequestState, so the code below jumps to
                        // `release:' to guarantee it rather than yielding.
                        //
                        if (PreRequestHandlerExecute != null)
                                foreach (bool stop in RunHooks (PreRequestHandlerExecute))
                                        if (stop)
                                                goto release;
                                
#if TARGET_J2EE
                processHandler:
                        bool doProcessHandler = false;
#endif
                        try {
                                context.BeginTimeoutPossible ();
                                if (handler != null){
                                        IHttpAsyncHandler async_handler = handler as IHttpAsyncHandler;
                                        
                                        if (async_handler != null){
                                                must_yield = true;
                                                in_begin = true;
                                                async_handler.BeginProcessRequest (context, async_handler_complete_cb, handler);
                                        } else {
                                                must_yield = false;
                                                handler.ProcessRequest (context);
#if TARGET_J2EE
                                                IHttpExtendedHandler extHandler=handler as IHttpExtendedHandler;
                                                doProcessHandler = extHandler != null && !extHandler.IsCompleted;
#endif
                                        }
                                }
                                if (context.Error != null)
                                        throw new TargetInvocationException(context.Error);
                        } finally {
                                in_begin = false;
                                context.EndTimeoutPossible ();
                        }
#if TARGET_J2EE
                        if (doProcessHandler) {
                                yield return false;
                                goto processHandler;
                        }
#endif
                        if (must_yield)
                                yield return stop_processing;
                        else if (stop_processing)
                                goto release;
                        
                        // These are executed after the application has returned
                        
                        if (PostRequestHandlerExecute != null)
                                foreach (bool stop in RunHooks (PostRequestHandlerExecute))
                                        if (stop)
                                                goto release;
                        
                release:
                        if (ReleaseRequestState != null){
#pragma warning disable 168
                                foreach (bool stop in RunHooks (ReleaseRequestState)){
                                        //
                                        // Ignore the stop signal while release the state
                                        //
                                        
                                }
#pragma warning restore 168
                        }
                        
                        if (stop_processing)
                                yield return true;

#if NET_2_0
                        if (PostReleaseRequestState != null)
                                foreach (bool stop in RunHooks (PostReleaseRequestState))
                                        yield return stop;
#endif

                        if (context.Error == null)
                                context.Response.DoFilter (true);

                        if (UpdateRequestCache != null)
                                foreach (bool stop in RunHooks (UpdateRequestCache))
                                        yield return stop;

#if NET_2_0
                        if (PostUpdateRequestCache != null)
                                foreach (bool stop in RunHooks (PostUpdateRequestCache))
                                        yield return stop;

                        if (LogRequest != null)
                                foreach (bool stop in RunHooks (LogRequest))
                                        yield return stop;

                        if (PostLogRequest != null)
                                foreach (bool stop in RunHooks (PostLogRequest))
                                        yield return stop;
#endif
                        PipelineDone ();
                }


                internal CultureInfo GetThreadCulture (HttpRequest request, CultureInfo culture, bool isAuto)
                {
#if NET_2_0
                        if (!isAuto)
                                return culture;
                        CultureInfo ret = null;
                        string[] languages = request.UserLanguages;
                        try {
                                if (languages != null && languages.Length > 0)
                                        ret = CultureInfo.CreateSpecificCulture (languages[0]);
                        } catch {
                        }
                        
                        if (ret == null)
                                ret = culture;
                        
                        return ret;
#else
                        return culture;
#endif
                }


                void PreStart ()
                {
#if NET_2_0
                        GlobalizationSection cfg;
                        cfg = (GlobalizationSection) WebConfigurationManager.GetSection ("system.web/globalization");
                        app_culture = cfg.GetCulture ();
                        autoCulture = cfg.IsAutoCulture;
                        appui_culture = cfg.GetUICulture ();
                        autoUICulture = cfg.IsAutoUICulture;
#else
                        GlobalizationConfiguration cfg;
                        cfg = GlobalizationConfiguration.GetInstance (null);
                        if (cfg != null) {
                                app_culture = cfg.Culture;
                                appui_culture = cfg.UICulture;
                        }
#endif

#if !TARGET_J2EE
                        context.StartTimeoutTimer ();
#endif
                        Thread th = Thread.CurrentThread;
                        if (app_culture != null) {
                                prev_app_culture = th.CurrentCulture;
                                CultureInfo new_app_culture = GetThreadCulture (Request, app_culture, autoCulture);
                                if (!new_app_culture.Equals (CultureInfo.InvariantCulture))
                                        th.CurrentCulture = new_app_culture;
                        }

                        if (appui_culture != null) {
                                prev_appui_culture = th.CurrentUICulture;
                                CultureInfo new_app_culture = GetThreadCulture (Request, appui_culture, autoUICulture);
                                if (!new_app_culture.Equals (CultureInfo.InvariantCulture))
                                        th.CurrentUICulture = new_app_culture;
                        }

#if !TARGET_JVM
                        prev_user = Thread.CurrentPrincipal;
#endif
                }

                void PostDone ()
                {
#if NET_2_0
                        if (removeConfigurationFromCache) {
                                WebConfigurationManager.RemoveConfigurationFromCache (context);
                                removeConfigurationFromCache = false;
                        }
#endif
                        Thread th = Thread.CurrentThread;
#if !TARGET_JVM
                        if (Thread.CurrentPrincipal != prev_user)
                                Thread.CurrentPrincipal = prev_user;
#endif
                        if (prev_appui_culture != null && prev_appui_culture != th.CurrentUICulture)
                                th.CurrentUICulture = prev_appui_culture;
                        if (prev_app_culture != null && prev_app_culture != th.CurrentCulture)
                                th.CurrentCulture = prev_app_culture;

#if !TARGET_J2EE
                        if (context == null)
                                context = HttpContext.Current;
                        context.StopTimeoutTimer ();
#endif
                        context = null;
                        session = null;
                        HttpContext.Current = null;
                }

                void Start (object x)
                {
                        try {
                                InitOnce (true);
                        } catch (Exception e) {
#if NET_2_0
                                initialization_exception = e;
#endif
                                FinalErrorWrite (context.Response, new HttpException ("", e).GetHtmlErrorMessage ());
                                PipelineDone ();
                                return;
                        }

                        HttpContext.Current = Context;
                        PreStart ();
                        pipeline = Pipeline ();
                        Tick ();
                }

                const string HANDLER_CACHE = "@@HttpHandlerCache@@";

                internal static Hashtable GetHandlerCache ()
                {
                        Cache cache = HttpRuntime.InternalCache;
                        Hashtable ret = cache [HANDLER_CACHE] as Hashtable;

                        if (ret == null) {
                                ret = new Hashtable ();
                                cache.Insert (HANDLER_CACHE, ret);
                        }

                        return ret;
                }
                
                internal static void ClearHandlerCache ()
                {
                        Hashtable cache = GetHandlerCache ();
                        cache.Clear ();
                }
                
                internal object LocateHandler (string verb, string url)
                {
                        Hashtable cache = GetHandlerCache ();
                        string id = String.Concat (verb, url);
                        object ret = cache [id];

                        if (ret != null)
                                return ret;
                        
#if NET_2_0
                        HttpHandlersSection     httpHandlersSection = (HttpHandlersSection) WebConfigurationManager.GetSection ("system.web/httpHandlers");
                        ret = httpHandlersSection.LocateHandler (verb, url);
#else
                        HandlerFactoryConfiguration factory_config = (HandlerFactoryConfiguration) HttpContext.GetAppConfig ("system.web/httpHandlers");
                        ret = factory_config.LocateHandler (verb, url);
#endif

                        cache [id] = ret;
                        return ret;
                }
                
                // Used by HttpServerUtility.Execute
                internal IHttpHandler GetHandler (HttpContext context,string url)
                {
                        HttpRequest request = context.Request;
                        string verb = request.RequestType;
                        
                        IHttpHandler handler = null;
                        object o = LocateHandler (verb, url);
                        
                        factory = o as IHttpHandlerFactory;
                        
                        if (factory == null) {
                                handler = (IHttpHandler) o;
                        } else {
                                handler = factory.GetHandler (context, verb, url, request.MapPath (url));
                        }

                        return handler;
                }
                
                void IHttpHandler.ProcessRequest (HttpContext context)
                {
                        begin_iar = null;
                        this.context = context;
                        done.Reset ();

                        Start (null);
                        done.WaitOne ();
                }

                //
                // This is used by FireOnAppStart, when we init the application
                // as the context is required to be set at that point (the user
                // might call methods that require it on that hook).
                //
                internal void SetContext (HttpContext context)
                {
                        this.context = context;
                }

                internal void SetSession (HttpSessionState session)
                {
                        this.session = session;
                }

                IAsyncResult IHttpAsyncHandler.BeginProcessRequest (HttpContext context, AsyncCallback cb, object extraData)
                {
                        this.context = context;
                        done.Reset ();
                        
                        begin_iar = new AsyncRequestState (done, cb, extraData);

#if TARGET_JVM
                        if (true)
#else
                        if (Thread.CurrentThread.IsThreadPoolThread)
#endif
                                Start (null);
                        else
                                ThreadPool.QueueUserWorkItem (new WaitCallback (Start), null);
                        
                        return begin_iar;
                }

                void IHttpAsyncHandler.EndProcessRequest (IAsyncResult result)
                {
#if TARGET_J2EE
                        if (result == null)
                                result = begin_iar;
#endif
                        if (!result.IsCompleted)
                                result.AsyncWaitHandle.WaitOne ();
                        begin_iar = null;
                }

                public virtual void Init ()
                {
                }

                bool IHttpHandler.IsReusable {
                        get {
                                return true;
                        }
                }
                
#region internals
                internal void ClearError ()
                {
                        context.ClearError ();
                }

                bool RedirectErrorPage (string error_page)
                {
                        if (context.Request.QueryString ["aspxerrorpath"] != null)
                                return false;

                        Response.Redirect (error_page + "?aspxerrorpath=" + Request.Path, false);
                        return true;
                }
                                                        
                bool RedirectCustomError (ref HttpException httpEx)
                {
                        try {
                        if (!context.IsCustomErrorEnabledUnsafe)
                                return false;
                        
#if NET_2_0
                        CustomErrorsSection config = (CustomErrorsSection)WebConfigurationManager.GetSection ("system.web/customErrors");
#else
                        CustomErrorsConfig config = null;
                        try {
                                config = (CustomErrorsConfig) context.GetConfig ("system.web/customErrors");
                        } catch { }
#endif
                        
                        if (config == null) {
                                if (context.ErrorPage != null)
                                        return RedirectErrorPage (context.ErrorPage);
                                
                                return false;
                        }
                        
#if NET_2_0
                        CustomError err = config.Errors [context.Response.StatusCode.ToString()];
                        string redirect = err == null ? null : err.Redirect;
#else
                        string redirect =  config [context.Response.StatusCode];
#endif
                        if (redirect == null) {
                                redirect = context.ErrorPage;
                                if (redirect == null)
                                        redirect = config.DefaultRedirect;
                        }
                        
                        if (redirect == null)
                                return false;
                        
                        return RedirectErrorPage (redirect);
                        }
                        catch (Exception ex) {
                                httpEx = new HttpException (500, "", ex);
                                return false;
                        }
                }
#endregion
                internal static bool IsRunningOnWindows {
                        get { return _runningOnWindows; }
                }
                
                internal static IEnumerable BinDirectories
                {
                        get {
                                AppDomainSetup setup = AppDomain.CurrentDomain.SetupInformation;
                                string baseDir = setup.ApplicationBase;
                                string bindir;

                                if (Environment.GetEnvironmentVariable ("MONO_IOMAP") != null || IsRunningOnWindows) {
                                        bindir = Path.Combine (baseDir, "bin");
                                        if (Directory.Exists (bindir))
                                                yield return bindir;
                                } else {
                                        foreach (string dir in BinDirs) {
                                                bindir = Path.Combine (baseDir, dir);
                                                if (!Directory.Exists (bindir))
                                                        continue;
                                                yield return bindir;
                                        }
                                }
                        }
                }

                internal static string[] BinDirectoryAssemblies
                {
                        get {
                                ArrayList binDlls = null;
                                string[] dlls;
                                
                                foreach (string bindir in BinDirectories) {
                                        if (binDlls == null)
                                                binDlls = new ArrayList ();
                                        dlls = Directory.GetFiles (bindir, "*.dll");
                                        binDlls.AddRange (dlls);
                                }

                                if (binDlls == null)
                                        return new string[] {};
                                return (string[])binDlls.ToArray (typeof (string));
                        }
                }
                                        
                internal static Type LoadType (string typeName)
                {
                        return LoadType (typeName, false);
                }
                
                internal static Type LoadType (string typeName, bool throwOnMissing)
                {
                        Type type = Type.GetType (typeName);
                        if (type != null)
                                return type;

#if !TARGET_JVM
                        Assembly [] assemblies = AppDomain.CurrentDomain.GetAssemblies ();
                        foreach (Assembly ass in assemblies) {
                                type = ass.GetType (typeName, false);
                                if (type != null)
                                        return type;
                        }

#if NET_2_0
                        IList tla = System.Web.Compilation.BuildManager.TopLevelAssemblies;
                        if (tla != null && tla.Count > 0) {
                                foreach (Assembly asm in tla) {
                                        if (asm == null)
                                                continue;
                                        type = asm.GetType (typeName, false);
                                        if (type != null)
                                                return type;
                                }
                        }
#endif

                        type = LoadTypeFromBin (typeName);
                        if (type != null)
                                return type;
#endif
                        if (throwOnMissing)
                                throw new TypeLoadException (String.Format ("Type '{0}' cannot be found", typeName));
                        
                        return null;
                }

                internal static Type LoadTypeFromBin (string typeName)
                {
                        Type type = null;
                        
                        foreach (string s in BinDirectoryAssemblies) {
                                Assembly binA = Assembly.LoadFrom (s);
                                type = binA.GetType (typeName, false);
                                if (type == null)
                                        continue;
                                
                                return type;
                        }

                        return null;
                }
        }

        //
        // Based on Fritz' Onion's AsyncRequestState class for asynchronous IHttpAsyncHandlers
        // 
        class AsyncRequestState : IAsyncResult {
                AsyncCallback cb;
                object cb_data;
                bool completed;
                ManualResetEvent complete_event = null;
                
                internal AsyncRequestState (ManualResetEvent complete_event, AsyncCallback cb, object cb_data)
                {
                        this.cb = cb;
                        this.cb_data = cb_data;
                        this.complete_event = complete_event;
                }

                internal void Complete ()
                {
                        completed = true;
                        try {
                                //
                                // TODO: if this throws an error, we have no way of reporting it
                                // Not really too bad, since the only failure might be
                                // `HttpRuntime.request_processed'.   
                                //
                                if (cb != null)
                                        cb (this);
                        } catch {
                        }
                        
                        complete_event.Set ();
                }

                public object AsyncState {
                        get {
                                return cb_data;
                        }
                }

                public bool CompletedSynchronously {
                        get {
                                return false;
                        }
                }

                public bool IsCompleted {
                        get {
                                return completed;
                        }
                }

                public WaitHandle AsyncWaitHandle {
                        get {
                                return complete_event;
                        }
                }
        }

#region Helper classes
        
        //
        // A wrapper to keep track of begin/end pairs
        //
        class AsyncInvoker {
                public BeginEventHandler begin;
                public EndEventHandler end;
                public object data;
                
                public AsyncInvoker (BeginEventHandler bh, EndEventHandler eh, object d)
                {
                        begin = bh;
                        end = eh;
                        data = d;
                }

                public AsyncInvoker (BeginEventHandler bh, EndEventHandler eh)
                {
                        begin = bh;
                        end = eh;
                }
                
                public void Invoke (object sender, EventArgs e)
                {
                        throw new Exception ("This is just a dummy");
                }
        }
#endregion
}