Dwolla OAuth flow with node.js

dwollaOAuth

var express = require('express');
var router = express.Router();
var request = require('request');
var c = require('../config');

//step 1
var redirect_uri = c.host + '/oauth_return';
router.get('/auth/dwolla', function(req, res) {
    var scope = 'Transactions';
    var client_id = c.client_id;
    var url = util.format("https://www.dwolla.com/oauth/v2/authenticate?client_id=%s&response_type=code&redirect_uri=%s&scope=%s",
        encodeURIComponent(client_id),
        encodeURIComponent(redirect_uri),
        encodeURIComponent(scope));
    res.redirect(url);
});
//step 2 & 3
router.get('/oauth_return', function(req, res) {
    var client_id = c.client_id;
    var client_secret = c.client_secret;
    var code = req.query.code;
    var url = util.format("https://www.dwolla.com/oauth/v2/token?client_id=%s&client_secret=%s&grant_type=authorization_code&redirect_uri=%s&code=%s",
        encodeURIComponent(client_id),
        encodeURIComponent(client_secret),
        encodeURIComponent(redirect_uri),
        encodeURIComponent(code));
    request(url, function(error, response, body) {
        if (!error && response.statusCode == 200) {
            var data = JSON.parse(body);
            req.session.access_token = data.access_token;
            console.log(req.session.access_token);
            res.redirect('/transactions');
        }
    });
});