Redirecting default.aspx to root virtual directory

I have a simple ASP.NET 3.5 application running under IIS7 under a virtual directory. So the URL of my app is like http://example.com/app. I want to 301-redirect the request to example.com/app/default.aspx to example.com/app for better SEO. I have to do this redirect through code only, not by any IIS settings. I am unable to do so via code mentioned in this article:

https://web.archive.org/web/20211020203216/https://www.4guysfromrolla.com/articles/072810-1.aspx

The code:

if (request.RawUrl.Equals("/default.aspx"))
{
newUrl = string.Format("{0}://{1}{2}",
                 request.Url.Scheme,
                 request.Url.Authority,
                 request.RawUrl.Remove(request.RawUrl.LastIndexOf("/default.aspx", StringComparison.OrdinalIgnoreCase)));

               context.Response.Status = "301 moved permanently";
               context.Response.AddHeader("Location", newUrl);
}

seems to go into an infinite loop when the application is under a virtual directory. the request.RawUrl property always returns "/default.aspx" even after a 301 redirect causing the infinite loop. How can I fix this issue?

thanks,

Asif