strata/lib/basic-auth.js

A modular, streaming HTTP server

var strata = require('./index');
var utils = require('./utils');

/**
 * A middleware that performs basic auth on the incoming request before passing
 * it downstream. The validate argument must be a function that accepts three
 * arguments: the username and password used in the request, and a callback to
 * to call when auth is complete. This callback should be called with two
 * arguments: any error that occured and a string that contains the name of the
 * authorized user, if any.
 *
 *     strata.basicAuth(app, function (user, pass, callback) {
 *       if (user === 'admin' && pass === 'secret') {
 *         callback(null, user);
 *       } else {
 *         callback(null, false);
 *       }
 *     });
 *
 * When authorization fails, the client will automatically receive a 401
 * Unauthorized response with the appropriate challenge in the WWW-Authenticate
 * header.
 */
module.exports = function (app, validate, realm) {
  if (typeof validate !== 'function') {
    throw new Error('Missing validation function for basic auth');
  }

  function basicAuth(env, callback) {
    if (env.remoteUser) {
      app(env, callback);
      return;
    }

    var authorization = env.headers['authorization'];

    if (!authorization) {
      utils.unauthorized(env, callback, realm);
      return;
    }

    var parts = authorization.split(' ');
    var scheme = parts[0];

    if (scheme.toLowerCase() !== 'basic') {
      utils.badRequest(env, callback);
      return;
    }

    var params = new Buffer(parts[1], 'base64').toString().split(':');

    validate(params[0], params[1], function (err, user) {
      if (err && strata.handleError(err, env, callback)) {
        return;
      }

      if (user) {
        env.remoteUser = user;
        app(env, callback);
      } else {
        utils.unauthorized(env, callback, realm);
      }
    });
  }

  return basicAuth;
};