signal-desktop/js/websocket-resources.js

/* vim: ts=4:sw=4:expandtab
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
;(function(){
    'use strict';

    /*
     * WebSocket-Resources
     *
     * Create a request-response interface over websockets using the
     * WebSocket-Resources sub-protocol[1].
     *
     * var client = new WebSocketResource(socket, function(request) {
     *    request.respond(200, 'OK');
     * });
     *
     * client.sendRequest({
     *    verb: 'PUT',
     *    path: '/v1/messages',
     *    body: '{ some: "json" }',
     *    success: function(message, status, request) {...},
     *    error: function(message, status, request) {...}
     * });
     *
     * 1. https://github.com/WhisperSystems/WebSocket-Resources
     *
     */

    var Request = function(options) {
        this.verb    = options.verb || options.type;
        this.path    = options.path || options.url;
        this.body    = options.body || options.data;
        this.success = options.success
        this.error   = options.error
        this.id      = options.id;

        if (this.id === undefined) {
            var bits = new Uint32Array(2);
            window.crypto.getRandomValues(bits);
            this.id = dcodeIO.Long.fromBits(bits[0], bits[1], true);
        }
    };

    var IncomingWebSocketRequest = function(options) {
        var request = new Request(options);
        var socket = options.socket;

        this.verb = request.verb;
        this.path = request.path;
        this.body = request.body;

        this.respond = function(status, message) {
            socket.send(
                new textsecure.protobuf.WebSocketMessage({
                    type: textsecure.protobuf.WebSocketMessage.Type.RESPONSE,
                    response: { id: request.id, message: message, status: status }
                }).encode().toArrayBuffer()
            );
        };
    };

    var outgoing = {};
    var OutgoingWebSocketRequest = function(options, socket) {
        var request = new Request(options);
        outgoing[request.id] = request;
        socket.send(
            new textsecure.protobuf.WebSocketMessage({
                type: textsecure.protobuf.WebSocketMessage.Type.REQUEST,
                request: {
                    verb : request.verb,
                    path : request.path,
                    body : request.body,
                    id   : request.id
                }
            }).encode().toArrayBuffer()
        );
    };

    window.WebSocketResource = function(socket, handleRequest) {
        this.sendRequest = function(options) {
            return new OutgoingWebSocketRequest(options, socket);
        };

        socket.onmessage = function(socketMessage) {
            var blob = socketMessage.data;
            var reader = new FileReader();
            reader.onload = function() {
                var message = textsecure.protobuf.WebSocketMessage.decode(reader.result);
                if (message.type === textsecure.protobuf.WebSocketMessage.Type.REQUEST ) {
                    handleRequest(
                        new IncomingWebSocketRequest({
                            verb   : message.request.verb,
                            path   : message.request.path,
                            body   : message.request.body,
                            id     : message.request.id,
                            socket : socket
                        })
                    );
                }
                else if (message.type === textsecure.protobuf.WebSocketMessage.Type.RESPONSE ) {
                    var response = message.response;
                    var request = outgoing[response.id];
                    if (request) {
                        request.response = response;
                        var callback = request.error;
                        if (response.status >= 200 && response.status < 300) {
                            callback = request.success;
                        }

                        if (typeof callback === 'function') {
                            callback(response.message, response.status, request);
                        }
                    } else {
                        throw 'Received response for unknown request ' + message.response.id;
                    }
                }
            };
            reader.readAsArrayBuffer(blob);
        };
    };

}());