RequireHttpsPermanentAttribute - a subclass of the RequireHttpsAttribute that also allows HEAD requests and does a permanent redirect

RequireHttpsPermanentAttribute.cs

/// <summary>
/// Same as the standard RequireHttps attribute, except the redirect is permanent, 
/// and it doesn't throw exceptions for a HEAD request
/// </summary>
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, Inherited = true, AllowMultiple = false)]
public class RequireHttpsPermanentAttribute : RequireHttpsAttribute
{
    private static String[] _allowedMethods = new[] { "GET", "HEAD" };
    protected override void HandleNonHttpsRequest(AuthorizationContext filterContext)
    {
        if (!_allowedMethods.Contains(filterContext.HttpContext.Request.HttpMethod, StringComparer.OrdinalIgnoreCase))
        {
            throw new InvalidOperationException("The requested resource can only be accessed via SSL.");
        }
        string url = "https://" + filterContext.HttpContext.Request.Url.Host + filterContext.HttpContext.Request.RawUrl;
        filterContext.Result = new RedirectResult(url, true);
    }

}