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://site.com/app. I want to 301-redirect the request to site.com/app/default.aspx to site.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:

[URL]

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.