Simplified Native OAuth2.0 Application Login CLI implementation

index.js

/* eslint-disable no-console, camelcase */

const server = require('http').createServer().listen(0);

const { Issuer, generators } = require('openid-client');
const open = require('open');

server.removeAllListeners('request');
const { ISSUER = 'https://op.panva.cz' } = process.env;

server.once('listening', () => {
  (async () => {
    const issuer = await Issuer.discover(ISSUER);
    const { address, port } = server.address();
    const hostname = address === '::' ? '[::1]' : address;

    const client = await issuer.Client.register({
      redirect_uris: [`http://${hostname}`],
      application_type: 'native',
      token_endpoint_auth_method: 'none',
    });
    const code_verifier = generators.codeVerifier();
    const code_challenge = generators.codeChallenge(code_verifier);
    const redirect_uri = `http://${address === '::' ? '[::1]' : address}:${port}`;

    server.on('request', async (req, res) => {
      res.setHeader('connection', 'close');
      const params = client.callbackParams(req);
      if (Object.keys(params).length) {
        const tokenSet = await client.callback(
          redirect_uri, params, { code_verifier, response_type: 'code' },
        );

        console.log('got', tokenSet);
        console.log('id token claims', tokenSet.claims());

        const userinfo = await client.userinfo(tokenSet);
        console.log('userinfo', userinfo);

        res.end('you can close this now');
        server.close();
      }
    });

    await open(client.authorizationUrl({
      redirect_uri,
      code_challenge,
      code_challenge_method: 'S256',
      scope: 'openid email',
    }), { wait: false });
  })().catch((err) => {
    console.error(err);
    process.exitCode = 1;
    server.close();
  });
});

package.json

{
  "name": "pg",
  "version": "1.0.0",
  "description": "",
  "main": "codeflow.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "open": "^7.0.0",
    "openid-client": "^3.8.3"
  }
}