express-ws/lib/index.js

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }(); /* This module does a lot of monkeypatching, but unfortunately that appears to be the only way to
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          * accomplish this kind of stuff in Express.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          *
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          * Here be dragons. */

exports.expressWs = expressWs;

var _http = require('http');

var _http2 = _interopRequireDefault(_http);

var _express = require('express');

var _express2 = _interopRequireDefault(_express);

var _ws = require('ws');

var _ws2 = _interopRequireDefault(_ws);

var _trailingSlash = require('./trailing-slash');

var _trailingSlash2 = _interopRequireDefault(_trailingSlash);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/* The following fixes HenningM/express-ws#17, correctly. */
function websocketUrl(url) {
  if (url.indexOf('?') !== -1) {
    var _url$split = url.split('?');

    var _url$split2 = _slicedToArray(_url$split, 2);

    var baseUrl = _url$split2[0];
    var query = _url$split2[1];


    return (0, _trailingSlash2.default)(baseUrl) + '.websocket?' + query;
  }
  return (0, _trailingSlash2.default)(url) + '.websocket';
}

function expressWs(app, httpServer) {
  var options = arguments.length <= 2 || arguments[2] === undefined ? {} : arguments[2];

  var server = httpServer;

  if (!server) {
    /* No HTTP server was explicitly provided, create one for our Express application. */
    server = _http2.default.createServer(app);

    app.listen = function serverListen() {
      server.listen.apply(server, arguments);
    };
  }

  function wrapMiddleware(middleware) {
    return function (req, res, next) {
      if (req.ws !== null) {
        req.wsHandled = true;
        /* Unpack the `.ws` property and call the actual handler. */
        middleware(req.ws, req, next);
      } else {
        /* This wasn't a WebSocket request, so skip this middleware. */
        next();
      }
    };
  }

  function addWsMethod(target) {
    if (!target.ws) {
      /* This prevents conflict with other things setting `.ws`. */
      target.ws = function addWsRoute(route) {
        var middlewares = Array.prototype.slice.call(arguments, 1); // deopt!
        var wrappedMiddlewares = middlewares.map(wrapMiddleware);

        /* We append `/.websocket` to the route path here. Why? To prevent conflicts when
         * a non-WebSocket request is made to the same GET route - after all, we are only
         * interested in handling WebSocket requests.
         *
         * Whereas the original `express-ws` prefixed this path segment, we suffix it -
         * this makes it possible to let requests propagate through Routers like normal,
         * which allows us to specify WebSocket routes on Routers as well \o/! */
        var wsRoute = websocketUrl(route);

        /* Here we configure our new GET route. It will never get called by a client
         * directly, it's just to let our request propagate internally, so that we can
         * leave the regular middleware execution and error handling to Express. */
        target.get.apply(target, [wsRoute].concat(wrappedMiddlewares));
      };
    }
  }

  /* Make our custom `.ws` method available directly on the Express application. You should
   * really be using Routers, though. */
  addWsMethod(app);

  /* Monkeypatch our custom `.ws` method into Express' Router prototype. This makes it possible,
   * when using the standard Express Router, to use the `.ws` method without any further calls
   * to `makeRouter`. When using a custom router, the use of `makeRouter` may still be necessary.
   *
   * This approach works, because Express does a strange mixin hack - the Router factory
   * function is simultaneously the prototype that gets assigned to the resulting Router
   * object. */
  if (!options.leaveRouterUntouched) {
    addWsMethod(_express2.default.Router);
  }

  var wsServer = new _ws2.default.Server({ server: server });

  wsServer.on('connection', function (socket) {
    var request = socket.upgradeReq;

    request.ws = socket;
    request.wsHandled = false;

    /* By setting this fake `.url` on the request, we ensure that it will end up in the fake
     * `.get` handler that we defined above - where the wrapper will then unpack the `.ws`
     * property, indicate that the WebSocket has been handled, and call the actual handler. */
    request.url = websocketUrl(request.url);

    var dummyResponse = new _http2.default.ServerResponse(request);

    dummyResponse.writeHead = function (statusCode) {
      if (statusCode > 200) {
        /* Something in the middleware chain signalled an error. */
        socket.close();
      }
    };

    app.handle(request, dummyResponse, function () {
      if (!request.wsHandled) {
        /* There was no matching WebSocket-specific route for this request. We'll close
         * the connection, as no endpoint was able to handle the request anyway... */
        socket.close();
      }
    });
  });

  return {
    app: app,
    getWss: function getWss() {
      return wsServer;
    },
    applyTo: function applyTo(router) {
      return addWsMethod(router);
    }
  };
};