Redirecting unauthorized controller in ASP.NET MVC

小开

You should build your own Authorize-filter attribute.

Here's mine to study ;)

Public Class RequiresRoleAttribute : Inherits ActionFilterAttribute
Private _role As String


Public Property Role() As String
Get
Return Me._role
End Get
Set(ByVal value As String)
Me._role = value
End Set
End Property


Public Overrides Sub OnActionExecuting(ByVal filterContext As System.Web.Mvc.ActionExecutingContext)
If Not String.IsNullOrEmpty(Me.Role) Then
If Not filterContext.HttpContext.User.Identity.IsAuthenticated Then
Dim redirectOnSuccess As String = filterContext.HttpContext.Request.Url.AbsolutePath
Dim redirectUrl As String = String.Format("?ReturnUrl={0}", redirectOnSuccess)
Dim loginUrl As String = FormsAuthentication.LoginUrl + redirectUrl


filterContext.HttpContext.Response.Redirect(loginUrl, True)
Else
Dim hasAccess As Boolean = filterContext.HttpContext.User.IsInRole(Me.Role)
If Not hasAccess Then
Throw New UnauthorizedAccessException("You don't have access to this page. Only " & Me.Role & " can view this page.")
End If
End If
Else
Throw New InvalidOperationException("No Role Specified")
End If


End Sub
End Class

小开

最佳答案

Create a custom authorization attribute based on AuthorizeAttribute and override OnAuthorization to perform the check how you want it done. Normally, AuthorizeAttribute will set the filter result to HttpUnauthorizedResult if the authorization check fails. You could have it set it to a ViewResult (of your Error view) instead.

EDIT: I have a couple of blog posts that go into more detail:

Example:

    [AttributeUsage( AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false )]
public class MasterEventAuthorizationAttribute : AuthorizeAttribute
{
/// <summary>
/// The name of the master page or view to use when rendering the view on authorization failure.  Default
/// is null, indicating to use the master page of the specified view.
/// </summary>
public virtual string MasterName { get; set; }


/// <summary>
/// The name of the view to render on authorization failure.  Default is "Error".
/// </summary>
public virtual string ViewName { get; set; }


public MasterEventAuthorizationAttribute()
: base()
{
this.ViewName = "Error";
}


protected void CacheValidateHandler( HttpContext context, object data, ref HttpValidationStatus validationStatus )
{
validationStatus = OnCacheAuthorization( new HttpContextWrapper( context ) );
}


public override void OnAuthorization( AuthorizationContext filterContext )
{
if (filterContext == null)
{
throw new ArgumentNullException( "filterContext" );
}


if (AuthorizeCore( filterContext.HttpContext ))
{
SetCachePolicy( filterContext );
}
else if (!filterContext.HttpContext.User.Identity.IsAuthenticated)
{
// auth failed, redirect to login page
filterContext.Result = new HttpUnauthorizedResult();
}
else if (filterContext.HttpContext.User.IsInRole( "SuperUser" ))
{
// is authenticated and is in the SuperUser role
SetCachePolicy( filterContext );
}
else
{
ViewDataDictionary viewData = new ViewDataDictionary();
viewData.Add( "Message", "You do not have sufficient privileges for this operation." );
filterContext.Result = new ViewResult { MasterName = this.MasterName, ViewName = this.ViewName, ViewData = viewData };
}


}


protected void SetCachePolicy( AuthorizationContext filterContext )
{
// ** IMPORTANT **
// Since we're performing authorization at the action level, the authorization code runs
// after the output caching module. In the worst case this could allow an authorized user
// to cause the page to be cached, then an unauthorized user would later be served the
// cached page. We work around this by telling proxies not to cache the sensitive page,
// then we hook our custom authorization code into the caching mechanism so that we have
// the final say on whether a page should be served from the cache.
HttpCachePolicyBase cachePolicy = filterContext.HttpContext.Response.Cache;
cachePolicy.SetProxyMaxAge( new TimeSpan( 0 ) );
cachePolicy.AddValidationCallback( CacheValidateHandler, null /* data */);
}




}

小开

I had the same issue. Rather than figure out the MVC code, I opted for a cheap hack that seems to work. In my Global.asax class:

member x.Application_EndRequest() =
if x.Response.StatusCode = 401 then
let redir = "?redirectUrl=" + Uri.EscapeDataString x.Request.Url.PathAndQuery
if x.Request.Url.LocalPath.ToLowerInvariant().Contains("admin") then
x.Response.Redirect("/Login/Admin/" + redir)
else
x.Response.Redirect("/Login/Login/" + redir)

小开

The code by "tvanfosson" was giving me "Error executing Child Request".. I have changed the OnAuthorization like this:

public override void OnAuthorization(AuthorizationContext filterContext)
{
base.OnAuthorization(filterContext);


if (!_isAuthorized)
{
filterContext.Result = new HttpUnauthorizedResult();
}
else if (filterContext.HttpContext.User.IsInRole("Administrator") || filterContext.HttpContext.User.IsInRole("User") ||  filterContext.HttpContext.User.IsInRole("Manager"))
{
// is authenticated and is in one of the roles
SetCachePolicy(filterContext);
}
else
{
filterContext.Controller.TempData.Add("RedirectReason", "You are not authorized to access this page.");
filterContext.Result = new RedirectResult("~/Error");
}
}

This works well and I show the TempData on error page. Thanks to "tvanfosson" for the code snippet. I am using windows authentication and _isAuthorized is nothing but HttpContext.User.Identity.IsAuthenticated...

小开

You can work with the overridable HandleUnauthorizedRequest inside your custom AuthorizeAttribute

Like this:

protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
{
// Returns HTTP 401 by default - see HttpUnauthorizedResult.cs.
filterContext.Result = new RedirectToRouteResult(
new RouteValueDictionary
{
{ "action", "YourActionName" },
{ "controller", "YourControllerName" },
{ "parameterName", "YourParameterValue" }
});
}

You can also do something like this:

private class RedirectController : Controller
{
public ActionResult RedirectToSomewhere()
{
return RedirectToAction("Action", "Controller");
}
}

Now you can use it in your HandleUnauthorizedRequest method this way:

filterContext.Result = (new RedirectController()).RedirectToSomewhere();

小开

This problem has hounded me for some days now, so on finding the answer that affirmatively works with tvanfosson's answer above, I thought it would be worthwhile to emphasize the core part of the answer, and address some related catch ya's.

The core answer is this, sweet and simple:

filterContext.Result = new HttpUnauthorizedResult();

In my case I inherit from a base controller, so in each controller that inherits from it I override OnAuthorize:

protected override void OnAuthorization(AuthorizationContext filterContext)
{
base.OnAuthorization(filterContext);
YourAuth(filterContext); // do your own authorization logic here
}

The problem was that in 'YourAuth', I tried two things that I thought would not only work, but would also immediately terminate the request. Well, that is not how it works. So first, the two things that DO NOT work, unexpectedly:

filterContext.RequestContext.HttpContext.Response.Redirect("/Login"); // doesn't work!
FormsAuthentication.RedirectToLoginPage(); // doesn't work!

Not only do those not work, they don't end the request either. Which means the following:

if (!success) {
filterContext.Result = new HttpUnauthorizedResult();
}
DoMoreStuffNowThatYouThinkYourAuthorized();

Well, even with the correct answer above, the flow of logic still continues! You will still hit DoMoreStuff... within OnAuthorize. So keep that in mind (DoMore... should be in an else therefore).

But with the correct answer, while OnAuthorize flow of logic continues till the end still, after that you really do get what you expect: a redirect to your login page (if you have one set in Forms auth in your webconfig).

But unexpectedly, 1) Response.Redirect("/Login") does not work: the Action method still gets called, and 2) FormsAuthentication.RedirectToLoginPage(); does the same thing: the Action method still gets called!

Which seems totally wrong to me, particularly with the latter: who would have thought that FormsAuthentication.RedirectToLoginPage does not end the request, or do the equivalant above of what filterContext.Result = new HttpUnauthorizedResult() does?

小开

Would have left this as a comment but I need more rep, anyways I just wanted to mention to Nicholas Peterson that perhaps passing the second argument to the Redirect call to tell it to end the response would have worked. Not the most graceful way to handle this but it does in fact work.

So

filterContext.RequestContext.HttpContext.Response.Redirect("/Login", true);

instead of

filterContext.RequestContext.HttpContext.Response.Redirect("/Login);

So you'd have this in your controller:

 protected override void OnAuthorization(AuthorizationContext filterContext)
{
if(!User.IsInRole("Admin")
{
base.OnAuthorization(filterContext);
filterContext.RequestContext.HttpContext.Response.Redirect("/Login", true);
}
}

小开

Perhaps you get a blank page when you run from Visual Studio under development server using Windows authentication (previous topic).

If you deploy to IIS you can configure custom error pages for specific status codes, in this case 401. Add httpErrors under system.webServer:

<httpErrors>
<remove statusCode="401" />
<error statusCode="401" path="/yourapp/error/unauthorized" responseMode="Redirect" />
</httpErrors>

Then create ErrorController.Unauthorized method and corresponding custom view.