Download file in asp.net

public static void download(string fileName, string filepath)
    {
        string userAgent = HttpContext.Current.Request.Headers.Get("User-Agent");
        string f = HttpContext.Current.Server.UrlDecode(fileName);
        if (userAgent.Contains("MSIE 7.0"))
        {
            //for IE
            f = fileName.Replace(" ", "%20");
        }
        else
        {
            //do nothing
        }
        fileName = HttpContext.Current.Server.UrlDecode(fileName);
        System.IO.FileStream liveStream = new System.IO.FileStream(HttpContext.Current.Server.MapPath(filepath), System.IO.FileMode.Open, System.IO.FileAccess.Read);
        byte[] buffer = new byte[Convert.ToInt32(liveStream.Length)];
        liveStream.Read(buffer, 0, Convert.ToInt32(liveStream.Length));
        liveStream.Close();

        HttpContext.Current.Response.Clear();

        if (fileName.EndsWith(".csv"))
        {
            HttpContext.Current.Response.ContentType = "application/csv";
        }
        else
        {
            HttpContext.Current.Response.ContentType = "application/octet-stream";
        }
        
        HttpContext.Current.Response.AddHeader("Content-Length", buffer.Length.ToString());
        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=\"" + f + "\"");
        HttpContext.Current.Response.BinaryWrite(buffer);
        HttpContext.Current.Response.End();
    }