chatbot-constructor/lib/middleware/slack_authentication.js

A chatbot constructor/builder that can help you develop chatbots in no time either using javascript and nodejs or without programming using excel sheet or JSON format. And it can also easily integrate with AI services like LUIS, Watson, Lex, Octane.AI, Wi

/**
 * Authentication module composed of an Express middleware used to validate
 * incoming requests from the Slack API for Slash commands and outgoing
 * webhooks.
 */

// Comparison constant
var TOKEN_NOT_FOUND = -1;

function init(tokens) {
    var authenticationTokens = flatten(tokens);

    if (authenticationTokens.length === 0) {
        console.warn('No auth tokens provided, webhook endpoints will always reply HTTP 401.');
    }

    /**
     * Express middleware that verifies a Slack token is passed;
     * if the expected token value is not passed, end with request test
     * with a 401 HTTP status code.
     *
     * Note: Slack is totally wacky in that the auth token is sent in the body
     * of the request instead of a header value.
     *
     * @param {object} req - Express request object
     * @param {object} res - Express response object
     * @param {function} next - Express callback
     */
    function authenticate(req, res, next) {
        var token = getToken(req.body);
        if (!token || authenticationTokens.indexOf(token) === TOKEN_NOT_FOUND) {
            res.status(401).send({
                'code': 401,
                'message': 'Unauthorized'
            });

            return;
        }

        next();
    }

    return authenticate;
}
/**
 * Function that flattens a series of arguments into an array.
 *
 * @param {Array} args - No token (null), single token (string), or token array (array)
 * @returns {Array} - Every element of the array is an authentication token
 */
function flatten(args) {
        var result = [];

        // convert a variable argument list to an array
        args.forEach(function(arg) {
            result = result.concat(arg);
        });
        return result;
    }
module.exports = init;

function getToken(body) {
    if (!body) return null;
    if (body.token) return body.token;
    if (!body.payload) return null;

    var payload = body.payload;
    if (typeof payload === 'string') {
        payload = JSON.parse(payload);
    }

    return payload.token;
}