code: function performAuth(opts) {
    var localAuth = opts.localAuth;
    return function(req, res, next) {
      if (fh && fh.auth && fh.auth.performAuth) {
        req.pause();
        fh.auth.performAuth(req, localAuth, function(err, fhres) {
          req.resume();
  
          if (err || !fhres) {
            next(err || new Error("No response sent by authentication endpoint"));
          } else {
            sendResponse(fhres.status, fhres.body, res, next);
          }
        });
      } else {
        return res.status(404).end();
      }
    };
  }
docs: performs authentication request ($fh.auth)