How can I avoid duplicate content in ASP.NET MVC due to case-insensitive URLs and defaults?

Question

Edit: Now I need to solve this problem for real, I did a little more investigation and came up with a number of things to reduce duplicat

Answer 1

As well as posting here, I emailed ScottGu to see if he had a good response. He gave a sample for adding constraints to routes, so you could only respond to lowercase urls:

public class LowercaseConstraint : IRouteConstraint
{
    public bool Match(HttpContextBase httpContext, Route route,
            string parameterName, RouteValueDictionary values,
            RouteDirection routeDirection)
    {
        string value = (string)values[parameterName];

        return Equals(value, value.ToLower());
    }

And in the register routes method:

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    routes.MapRoute(
        "Default",                                              // Route name
        "{controller}/{action}/{id}",                           // URL with parameters
        new { controller = "home", action = "index", id = "" },
        new { controller = new LowercaseConstraint(), action = new LowercaseConstraint() }
    );
}

It's a start, but 'd want to be able to change the generation of links from methods like Html.ActionLink and RedirectToAction to match.