module.exports = (req, res, next) => {
  let key = req.headers.authorization;
  if(!key) return res.status(403).end();
  if(!key.toLowerCase().startsWith('basic ')) return res.status(403).end();
  key = key.substr(6);
  let site = req.app.locals.sites[key];
  if(!site) return res.status(403).end();
  res.locals.site = site;
  next();
};