static void FindFileType(RequestContext context, bool download, out string path, out string type)
{
path = Path.Combine(fileRoot, context.match.Groups[1].Value);
string ext = Path.GetExtension(path).ToLower().TrimStart(new char[] {'.'});
if (download || !fileTypes.TryGetValue(ext, out type))
type = "application/octet-stream";
}