How to check session before access to static page?

[Suliman via Digitalmars-d-learn]

void main()
{
    auto router = new URLRouter;
    router.get("/", 
serveStaticFiles("D:\\code\\onlineTest\\index.html"));
    router.get("/admin", 
serveStaticFiles("D:\\code\\onlineTest\\admin.html"));
    router.any("/foo", &foo);
    auto settings = new HTTPServerSettings;
    settings.port = 8080;
    settings.bindAddresses = ["::", "127.0.0.1"];
    settings.sessionStore = new MemorySessionStore; // SESSION
}


void foo(HTTPServerRequest req, HTTPServerResponse res)
{
    if (req.session)
    {
       res.writeBody("Hello, World!", "text/plain");
    }
}

Before showing foo I can check session status. But How to check 
session status for static /admin page?