Restricting access through absolute path (css and js) - use Http Handlers

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C#

ASP.NET

I want to restrict users to access files using URL absolute path (authenticated and not).

Users wont be able to access a CSS or Js file (for example entering http://codeproject.com/css_folder/something.js).

Obviously I cant deny access on web.config because if I do that the JS are not executed (for authenticated users).

So I'm thinking on an approach through some code. Something like this:

string path = Request.Url.AbsoluteUri;
        string strExt = System.IO.Path.GetExtension(path); // to get extension
        Response.Write("here: " + path);
        Response.Write(" test: " + strExt);
        if (!System.IO.Path.IsPathRooted(path)) //should get if entered absolute path
        {
            if ((strExt == ".css") || (strExt == ".js"))
            {
                Response.Redirect("notas.aspx");

But that's not working. And is natural, because when we enter absolute path there's no more server side code processed on that page.

From what I searched the solution is using a HttpHandler to build CSS and JS, and then change authorization on those handlers.

I did on web.config

<httpHandlers>
         <add verb="*" path="css/*.css" type="handler.MyHttpHandler, handler" />
      <add verb="*" path="Script/*.js" type="handler.MyHttpHandler, handler" />
</httpHandlers>

and created a class Myhhtphandler

<pre lang="cs">

public class MyHttpHandler : IHttpHandler, IReadOnlySessionState
{
    public void ProcessRequest(HttpContext context)
    {
       
            context.Response.Redirect("/login.aspx?retUrl=" + context.Request.RawUrl);
           
      
    }
    public bool IsReusable
    {
        get { return false; }
    }
}

I have two problems: I dont know if this correct, and I get an error "could not load file or assembly 'handler' or one of its dependencies. The system cannot find the file specified."

Sorry if the solution is too obvious, but I honestly dont know.

EDIT: I created a web.config dedicated on css folder a placed html handlers, this way I dont get errors but I still can access the css file through URL absolute path.

EDIT2:

Now using as simple as that: MyHttpHandler.cs:

using System.Web;
using System.Web.Security;
using System.Web.UI;
namespace test
{
   public class MyHttpHandler : IHttpHandler
   {
      public void ProcessRequest(HttpContext context)
      {
         context.Response.Redirect(
            "~/Downloads/Files/AccessDenied.aspx");
      }
      public bool IsReusable
      {
         get
         {
            return true;
         }
      }
   }
}

css/web.config:

<?xml version="1.0"?>
<configuration>
  <system.web>

        <httpHandlers>
          <add verb="*" path="*.css"
          type="test.MyHttpHandler"/>
        </httpHandlers>

  </system.web>
</configuration>

Still dont work.