unpkg/modules/middleware/checkBlacklist.js

const BlacklistAPI = require("../BlacklistAPI");

function checkBlacklist(req, res, next) {
  BlacklistAPI.includesPackage(req.packageName).then(
    blacklisted => {
      // Disallow packages that have been blacklisted.
      if (blacklisted) {
        res
          .status(403)
          .type("text")
          .send(`Package "${req.packageName}" is blacklisted`);
      } else {
        next();
      }
    },
    error => {
      console.error("Unable to fetch the blacklist: %s", error);

      // Continue anyway.
      next();
    }
  );
}

module.exports = checkBlacklist;