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// Copyright 2007 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 Contains the frame element method transport for cross-domain
* communication. It exploits the fact that FF lets a page in an
* iframe call a method on the iframe-element it is contained in, even if the
* containing page is from a different domain.
*
*/
goog.provide('goog.net.xpc.FrameElementMethodTransport');
goog.require('goog.net.xpc');
goog.require('goog.net.xpc.CrossPageChannelRole');
goog.require('goog.net.xpc.Transport');
/**
* Frame-element method transport.
*
* Firefox allows a document within an iframe to call methods on the
* iframe-element added by the containing document.
* NOTE(user): Tested in all FF versions starting from 1.0
*
* @param {goog.net.xpc.CrossPageChannel} channel The channel this transport
* belongs to.
* @param {goog.dom.DomHelper=} opt_domHelper The dom helper to use for finding
* the correct window.
* @constructor
* @extends {goog.net.xpc.Transport}
*/
goog.net.xpc.FrameElementMethodTransport = function(channel, opt_domHelper) {
goog.base(this, opt_domHelper);
/**
* The channel this transport belongs to.
* @type {goog.net.xpc.CrossPageChannel}
* @private
*/
this.channel_ = channel;
// To transfer messages, this transport basically uses normal function calls,
// which are synchronous. To avoid endless recursion, the delivery has to
// be artificially made asynchronous.
/**
* Array for queued messages.
* @type {Array}
* @private
*/
this.queue_ = [];
/**
* Callback function which wraps deliverQueued_.
* @type {Function}
* @private
*/
this.deliverQueuedCb_ = goog.bind(this.deliverQueued_, this);
};
goog.inherits(goog.net.xpc.FrameElementMethodTransport, goog.net.xpc.Transport);
/**
* The transport type.
* @type {number}
* @protected
* @override
*/
goog.net.xpc.FrameElementMethodTransport.prototype.transportType =
goog.net.xpc.TransportTypes.FRAME_ELEMENT_METHOD;
/**
* Flag used to enforce asynchronous messaging semantics.
* @type {boolean}
* @private
*/
goog.net.xpc.FrameElementMethodTransport.prototype.recursive_ = false;
/**
* Timer used to enforce asynchronous message delivery.
* @type {number}
* @private
*/
goog.net.xpc.FrameElementMethodTransport.prototype.timer_ = 0;
/**
* Holds the function to send messages to the peer
* (once it becomes available).
* @type {Function}
* @private
*/
goog.net.xpc.FrameElementMethodTransport.outgoing_ = null;
/**
* Connect this transport.
* @override
*/
goog.net.xpc.FrameElementMethodTransport.prototype.connect = function() {
if (this.channel_.getRole() == goog.net.xpc.CrossPageChannelRole.OUTER) {
// get shortcut to iframe-element
this.iframeElm_ = this.channel_.getIframeElement();
// add the gateway function to the iframe-element
// (to be called by the peer)
this.iframeElm_['XPC_toOuter'] = goog.bind(this.incoming_, this);
// at this point we just have to wait for a notification from the peer...
} else {
this.attemptSetup_();
}
};
/**
* Only used from within an iframe. Attempts to attach the method
* to be used for sending messages by the containing document. Has to
* wait until the containing document has finished. Therefore calls
* itself in a timeout if not successful.
* @private
*/
goog.net.xpc.FrameElementMethodTransport.prototype.attemptSetup_ = function() {
var retry = true;
/** @preserveTry */
try {
if (!this.iframeElm_) {
// throws security exception when called too early
this.iframeElm_ = this.getWindow().frameElement;
}
// check if iframe-element and the gateway-function to the
// outer-frame are present
// TODO(user) Make sure the following code doesn't throw any exceptions
if (this.iframeElm_ && this.iframeElm_['XPC_toOuter']) {
// get a reference to the gateway function
this.outgoing_ = this.iframeElm_['XPC_toOuter'];
// attach the gateway function the other document will use
this.iframeElm_['XPC_toOuter']['XPC_toInner'] =
goog.bind(this.incoming_, this);
// stop retrying
retry = false;
// notify outer frame
this.send(goog.net.xpc.TRANSPORT_SERVICE_, goog.net.xpc.SETUP_ACK_);
// notify channel that the transport is ready
this.channel_.notifyConnected();
}
}
catch (e) {
goog.net.xpc.logger.severe(
'exception caught while attempting setup: ' + e);
}
// retry necessary?
if (retry) {
if (!this.attemptSetupCb_) {
this.attemptSetupCb_ = goog.bind(this.attemptSetup_, this);
}
this.getWindow().setTimeout(this.attemptSetupCb_, 100);
}
};
/**
* Handles transport service messages.
* @param {string} payload The message content.
* @override
*/
goog.net.xpc.FrameElementMethodTransport.prototype.transportServiceHandler =
function(payload) {
if (this.channel_.getRole() == goog.net.xpc.CrossPageChannelRole.OUTER &&
!this.channel_.isConnected() && payload == goog.net.xpc.SETUP_ACK_) {
// get a reference to the gateway function
this.outgoing_ = this.iframeElm_['XPC_toOuter']['XPC_toInner'];
// notify the channel we're ready
this.channel_.notifyConnected();
} else {
throw Error('Got unexpected transport message.');
}
};
/**
* Process incoming message.
* @param {string} serviceName The name of the service the message is to be
* delivered to.
* @param {string} payload The message to process.
* @private
*/
goog.net.xpc.FrameElementMethodTransport.prototype.incoming_ =
function(serviceName, payload) {
if (!this.recursive_ && this.queue_.length == 0) {
this.channel_.xpcDeliver(serviceName, payload);
}
else {
this.queue_.push({serviceName: serviceName, payload: payload});
if (this.queue_.length == 1) {
this.timer_ = this.getWindow().setTimeout(this.deliverQueuedCb_, 1);
}
}
};
/**
* Delivers queued messages.
* @private
*/
goog.net.xpc.FrameElementMethodTransport.prototype.deliverQueued_ =
function() {
while (this.queue_.length) {
var msg = this.queue_.shift();
this.channel_.xpcDeliver(msg.serviceName, msg.payload);
}
};
/**
* Send a message
* @param {string} service The name off the service the message is to be
* delivered to.
* @param {string} payload The message content.
* @override
*/
goog.net.xpc.FrameElementMethodTransport.prototype.send =
function(service, payload) {
this.recursive_ = true;
this.outgoing_(service, payload);
this.recursive_ = false;
};
/** @override */
goog.net.xpc.FrameElementMethodTransport.prototype.disposeInternal =
function() {
goog.net.xpc.FrameElementMethodTransport.superClass_.disposeInternal.call(
this);
this.outgoing_ = null;
this.iframeElm_ = null;
};
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