Sample OWIN middleware that modifies requests based on standard nginx headers (used on AppHarbor)

AppHarborMiddleware.cs

public class AppHarborMiddleware : OwinMiddleware
{
	public AppHarborMiddleware(OwinMiddleware next)
		: base(next)
	{
	}

	public override Task Invoke(IOwinContext context)
	{
		if (string.Equals(context.Request.Headers["X-Forwarded-Proto"], "https", StringComparison.InvariantCultureIgnoreCase))
		{
			context.Request.Scheme = "https";
		}

		var forwardedForHeader = context.Request.Headers["X-Forwarded-For"];
		if (!string.IsNullOrEmpty(forwardedForHeader))
		{
			context.Request.RemoteIpAddress = forwardedForHeader;
		}
		return Next.Invoke(context);
	}
}

Works very well if you're doing SSL Termination in AWS, and want to use CookieSecure = CookieSecureOption.SameAsRequest,