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// Copyright 2010 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview A message channel between Gears workers. This is meant to work
* even when the Gears worker has other message listeners. GearsWorkerChannel
* adds a specific prefix to its messages, and handles messages with that
* prefix.
*
*/
goog.provide('goog.gears.WorkerChannel');
goog.require('goog.Disposable');
goog.require('goog.debug');
goog.require('goog.debug.Logger');
goog.require('goog.events');
goog.require('goog.gears.Worker');
goog.require('goog.gears.Worker.EventType');
goog.require('goog.gears.WorkerEvent');
goog.require('goog.json');
goog.require('goog.messaging.AbstractChannel');
/**
* Creates a message channel for the given Gears worker.
*
* @param {goog.gears.Worker} worker The Gears worker to communicate with. This
* should already be initialized.
* @constructor
* @extends {goog.messaging.AbstractChannel}
*/
goog.gears.WorkerChannel = function(worker) {
goog.base(this);
/**
* The Gears worker to communicate with.
* @type {goog.gears.Worker}
* @private
*/
this.worker_ = worker;
goog.events.listen(this.worker_, goog.gears.Worker.EventType.MESSAGE,
this.deliver_, false, this);
};
goog.inherits(goog.gears.WorkerChannel, goog.messaging.AbstractChannel);
/**
* The flag added to messages that are sent by a GearsWorkerChannel, and are
* meant to be handled by one on the other side.
* @type {string}
*/
goog.gears.WorkerChannel.FLAG = '--goog.gears.WorkerChannel';
/**
* The expected origin of the other end of the worker channel, represented as a
* string of the form SCHEME://DOMAIN[:PORT]. The port may be omitted for
* standard ports (http port 80, https port 443).
*
* If this is set, all GearsWorkerChannel messages are validated to come from
* this origin, and ignored (with a warning) if they don't. Messages that aren't
* in the GearsWorkerChannel format are not validated.
*
* If more complex origin validation is required, the checkMessageOrigin method
* can be overridden.
*
* @type {?string}
*/
goog.gears.WorkerChannel.prototype.peerOrigin;
/**
* Logger for this class.
* @type {goog.debug.Logger}
* @protected
* @override
*/
goog.gears.WorkerChannel.prototype.logger =
goog.debug.Logger.getLogger('goog.gears.WorkerChannel');
/**
* @override
*/
goog.gears.WorkerChannel.prototype.send =
function(serviceName, payload) {
var message = {'serviceName': serviceName, 'payload': payload};
message[goog.gears.WorkerChannel.FLAG] = true;
this.worker_.sendMessage(message);
};
/** @override */
goog.gears.WorkerChannel.prototype.disposeInternal = function() {
goog.base(this, 'disposeInternal');
this.worker_.dispose();
};
/**
* Delivers a message to the appropriate service handler. If this message isn't
* a GearsWorkerChannel message, it's ignored and passed on to other handlers.
*
* @param {goog.gears.WorkerEvent} e The event.
* @private
*/
goog.gears.WorkerChannel.prototype.deliver_ = function(e) {
var messageObject = e.messageObject || {};
var body = messageObject.body;
if (!goog.isObject(body) || !body[goog.gears.WorkerChannel.FLAG]) {
return;
}
if (!this.checkMessageOrigin(messageObject.origin)) {
return;
}
if (this.validateMessage_(body)) {
this.deliver(body['serviceName'], body['payload']);
}
e.preventDefault();
e.stopPropagation();
};
/**
* Checks whether the message is invalid in some way.
*
* @param {Object} body The contents of the message.
* @return {boolean} True if the message is valid, false otherwise.
* @private
*/
goog.gears.WorkerChannel.prototype.validateMessage_ = function(body) {
if (!('serviceName' in body)) {
this.logger.warning('GearsWorkerChannel::deliver_(): ' +
'Message object doesn\'t contain service name: ' +
goog.debug.deepExpose(body));
return false;
}
if (!('payload' in body)) {
this.logger.warning('GearsWorkerChannel::deliver_(): ' +
'Message object doesn\'t contain payload: ' +
goog.debug.deepExpose(body));
return false;
}
return true;
};
/**
* Checks whether the origin for a given message is the expected origin. If it's
* not, a warning is logged and the message is ignored.
*
* This checks that the origin matches the peerOrigin property. It can be
* overridden if more complex origin detection is necessary.
*
* @param {string} messageOrigin The origin of the message, of the form
* SCHEME://HOST[:PORT]. The port is omitted for standard ports (http port
* 80, https port 443).
* @return {boolean} True if the origin is acceptable, false otherwise.
* @protected
*/
goog.gears.WorkerChannel.prototype.checkMessageOrigin = function(
messageOrigin) {
if (!this.peerOrigin) {
return true;
}
// Gears doesn't include standard port numbers, but we want to let the user
// include them, so we'll just edit them out.
var peerOrigin = this.peerOrigin;
if (/^http:/.test(peerOrigin)) {
peerOrigin = peerOrigin.replace(/\:80$/, '');
} else if (/^https:/.test(peerOrigin)) {
peerOrigin = peerOrigin.replace(/\:443$/, '');
}
if (messageOrigin === peerOrigin) {
return true;
}
this.logger.warning('Message from unexpected origin "' + messageOrigin +
'"; expected only messages from origin "' + peerOrigin +
'"');
return false;
};
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