Mobile browser detection

using System.Text.RegularExpressions;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;

namespace MobileTest
{
    /*
     * Add the global filer RedirectMobileDevicesToMobileAreaAttribute to the global filter collection in
     * the Application_Start() of Global.asax.cs file
     *
     * GlobalFilters.Filters.Add(new RedirectMobileDevicesToMobileAreaAttribute(), 1);
     *
     * Add a reference to "51Degrees.mobi" library using NuGet
     *
     * See: http://weblogs.asp.net/shijuvarghese/archive/2011/02/25/mobile-enabled-web-apps-with-asp-net-mvc-3-and-jquery-mobile.aspx
     *      http://aspnetmobilesamples.codeplex.com/
     *
     * How to configure areas in MVC3:
     *      http://2010wave.blogspot.com/2009/12/how-to-create-areas-in-aspnet-mvc.html
     *      http://stackoverflow.com/questions/5243158/how-to-configure-areas-in-asp-net-mvc3
     */

    public class RedirectMobileDevicesToMobileAreaAttribute : AuthorizeAttribute
    {
        /// <summary>
        /// When overridden, provides an entry point for custom authorization checks.
        /// </summary>
        /// <param name="httpContext">The HTTP context, which encapsulates all HTTP-specific information about an individual HTTP request.</param>
        /// <returns>
        /// true if the user is authorized; otherwise, false.
        /// </returns>
        /// <exception cref="T:System.ArgumentNullException">The <paramref name="httpContext"/> parameter is null.</exception>
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            // Only redirect on the first request in a session
            if (!httpContext.Session.IsNewSession)
                return true;

            // Don't redirect non-mobile browsers
            if (!httpContext.Request.Browser.IsMobileDevice)
                return true;

            // Don't redirect requests for the Mobile area
            if (Regex.IsMatch(httpContext.Request.Url.PathAndQuery, "/Mobile($|/)"))
                return true;

            return false;
        }

        /// <summary>
        /// Gets the redirection route values.
        /// </summary>
        /// <param name="requestContext">The request context.</param>
        /// <returns></returns>
        protected virtual RouteValueDictionary GetRedirectionRouteValues(RequestContext requestContext)
        {
            return new RouteValueDictionary(new { area = "Mobile", controller = "Home", action = "Index" });
        }

        /// <summary>
        /// Processes HTTP requests that fail authorization.
        /// </summary>
        /// <param name="filterContext">Encapsulates the information for using <see cref="T:System.Web.Mvc.AuthorizeAttribute"/>. The <paramref name="filterContext"/> object contains the controller, HTTP context, request context, action result, and route data.</param>
        protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
        {
            var redirectionRouteValues = GetRedirectionRouteValues(filterContext.RequestContext);
            filterContext.Result = new RedirectToRouteResult(redirectionRouteValues);
        }
    }
}