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4 years ago
'use strict';
// Few cool transports do work only for same-origin. In order to make
// them work cross-domain we shall use iframe, served from the
// remote domain. New browsers have capabilities to communicate with
// cross domain iframe using postMessage(). In IE it was implemented
// from IE 8+, but of course, IE got some details wrong:
// http://msdn.microsoft.com/en-us/library/cc197015(v=VS.85).aspx
// http://stevesouders.com/misc/test-postmessage.php
var inherits = require('inherits')
, JSON3 = require('json3')
, EventEmitter = require('events').EventEmitter
, version = require('../version')
, urlUtils = require('../utils/url')
, iframeUtils = require('../utils/iframe')
, eventUtils = require('../utils/event')
, random = require('../utils/random')
;
var debug = function() {};
if (process.env.NODE_ENV !== 'production') {
debug = require('debug')('sockjs-client:transport:iframe');
}
function IframeTransport(transport, transUrl, baseUrl) {
if (!IframeTransport.enabled()) {
throw new Error('Transport created when disabled');
}
EventEmitter.call(this);
var self = this;
this.origin = urlUtils.getOrigin(baseUrl);
this.baseUrl = baseUrl;
this.transUrl = transUrl;
this.transport = transport;
this.windowId = random.string(8);
var iframeUrl = urlUtils.addPath(baseUrl, '/iframe.html') + '#' + this.windowId;
debug(transport, transUrl, iframeUrl);
this.iframeObj = iframeUtils.createIframe(iframeUrl, function(r) {
debug('err callback');
self.emit('close', 1006, 'Unable to load an iframe (' + r + ')');
self.close();
});
this.onmessageCallback = this._message.bind(this);
eventUtils.attachEvent('message', this.onmessageCallback);
}
inherits(IframeTransport, EventEmitter);
IframeTransport.prototype.close = function() {
debug('close');
this.removeAllListeners();
if (this.iframeObj) {
eventUtils.detachEvent('message', this.onmessageCallback);
try {
// When the iframe is not loaded, IE raises an exception
// on 'contentWindow'.
this.postMessage('c');
} catch (x) {
// intentionally empty
}
this.iframeObj.cleanup();
this.iframeObj = null;
this.onmessageCallback = this.iframeObj = null;
}
};
IframeTransport.prototype._message = function(e) {
debug('message', e.data);
if (!urlUtils.isOriginEqual(e.origin, this.origin)) {
debug('not same origin', e.origin, this.origin);
return;
}
var iframeMessage;
try {
iframeMessage = JSON3.parse(e.data);
} catch (ignored) {
debug('bad json', e.data);
return;
}
if (iframeMessage.windowId !== this.windowId) {
debug('mismatched window id', iframeMessage.windowId, this.windowId);
return;
}
switch (iframeMessage.type) {
case 's':
this.iframeObj.loaded();
// window global dependency
this.postMessage('s', JSON3.stringify([
version
, this.transport
, this.transUrl
, this.baseUrl
]));
break;
case 't':
this.emit('message', iframeMessage.data);
break;
case 'c':
var cdata;
try {
cdata = JSON3.parse(iframeMessage.data);
} catch (ignored) {
debug('bad json', iframeMessage.data);
return;
}
this.emit('close', cdata[0], cdata[1]);
this.close();
break;
}
};
IframeTransport.prototype.postMessage = function(type, data) {
debug('postMessage', type, data);
this.iframeObj.post(JSON3.stringify({
windowId: this.windowId
, type: type
, data: data || ''
}), this.origin);
};
IframeTransport.prototype.send = function(message) {
debug('send', message);
this.postMessage('m', message);
};
IframeTransport.enabled = function() {
return iframeUtils.iframeEnabled;
};
IframeTransport.transportName = 'iframe';
IframeTransport.roundTrips = 2;
module.exports = IframeTransport;