Token introspection as Express middleware

middleware.js

const tokenIntrospection = require('token-introspection');
const createError = require('http-errors');

const wrap = (fn) => (...args) => fn(...args).catch(args[2]);

const introspectMiddleware = (opts = {}) => {
  const introspect = tokenIntrospection(opts);

  return wrap(async (req, res, next) => {
    try {
      req.token = await introspect(req.token, 'access_token');
      next();
    } catch (err) {
      if (err instanceof tokenIntrospection.errors.TokenNotActiveError) {
        throw new createError.Unauthorized(err.message);
      }
      throw new createError.InternalServerError('An unknown error occurred when introspecting token');
    }
  });
};


// Then use the middleware
app.use(introspectMiddleware({ jwks_uri: 'https://example.com/jwks' }));