How to prevent downloading when user's allocated size or period exceeds

It is handled using httphandler in ASP.NET. The handler code is bellow ..

public class DownloadHandler : IHttpHandler

{

       public DownloadHandler()

       {

              //

              // TODO: Add constructor logic here

              //

       }

    public bool IsReusable

    {

        get { return true; }

    }

    /// <summary>

    /// Enables processing of HTTP Web requests by a custom HttpHandler that implements the <see cref="T:System.Web.IHttpHandler"/> interface.

    /// </summary>

    /// <param name="context">An <see cref="T:System.Web.HttpContext"/> object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param>

    public void ProcessRequest(HttpContext context)

    {

 

        long currentDownloadedAmount = 0;

        try

        {

            // File name

            string fileName = context.Request.Url.Segments[context.Request.Url.Segments.Length - 1]; ;

            fileName = context.Server.UrlDecode(fileName);

            string filePath = @"d:\ATVMovies\" + fileName;

            FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);

            // Total bytes to read

            long dataToRead = fileStream.Length;

            context.Server.ScriptTimeout = 600;

            context.Response.Buffer = true;

            context.Response.Clear();

            context.Response.ContentType = "application/octet-stream";

            context.Response.AddHeader("Content-Disposition",

                                       "attachment; filename=\"" + filePath + "\";");

            context.Response.AddHeader("Content-Length", dataToRead.ToString());

            int ChunkSize = 1024; //256 MB =256*1024

            // Buffer to read 10K bytes in chunk

            byte[] buffer = new Byte[ChunkSize];

            int offset = 0;

            int length;

            long UserRestAmount = MovieHelper.getMovieBalance((Guid)Membership.GetUser().ProviderUserKey);

            // Read the bytes.

            while (dataToRead > 0)

            {

                // Verify that the client is connected.

                if (context.Response.IsClientConnected)

                {

                    // UserRestAmount = MovieHelper.getMovieBalance((Guid)Membership.GetUser().ProviderUserKey);

                    if (UserRestAmount <= 0)

                    {

                        fileStream.Close();

                        dataToRead = -1; //disconnected

                        break;

                    }

                    // Read the data in buffer

                    length = fileStream.Read(buffer, offset, ChunkSize);

                    //offset += ChunkSize;

                    // Write the data to the current output stream.

                    context.Response.OutputStream.Write(buffer, 0, (int)length);

                    // Flush the data to the HTML output.

                    context.Response.Flush();

                    buffer = new Byte[ChunkSize];

                    dataToRead = dataToRead - length;

                    currentDownloadedAmount += length;

                    UserRestAmount -= length;

                }

                else

                {

                    //prevent infinite loop if user disconnects

                    dataToRead = -1;

                }

            }

            if (dataToRead == 0 || dataToRead == -1)  // complete or disconnected

            {

                MovieHelper.UpdateDownloadSize((Guid)Membership.GetUser().ProviderUserKey, currentDownloadedAmount);

                currentDownloadedAmount = 0;

            }

            fileStream.Close();

        }

        catch (Exception ex)

        {

            MovieHelper.UpdateDownloadSize((Guid)Membership.GetUser().ProviderUserKey, currentDownloadedAmount);

            currentDownloadedAmount = 0;

            context.Response.Write(ex.Message);

        }

     

     

    }

   

  

}