gecko-dev/toolkit/components/url-classifier/content/xml-fetcher.js

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3.9 KiB
JavaScript

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
// A simple class that encapsulates a request. You'll notice the
// style here is different from the rest of the extension; that's
// because this was re-used from really old code we had. At some
// point it might be nice to replace this with something better
// (e.g., something that has explicit onerror handler, ability
// to set headers, and so on).
/**
* Because we might be in a component, we can't just assume that
* XMLHttpRequest exists. So we use this tiny factory function to wrap the
* XPCOM version.
*
* @return XMLHttpRequest object
*/
function PROT_NewXMLHttpRequest() {
var Cc = Components.classes;
var Ci = Components.interfaces;
var request = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"]
.createInstance(Ci.nsIXMLHttpRequest);
// Need the following so we get onerror/load/progresschange
request.QueryInterface(Ci.nsIJSXMLHttpRequest);
return request;
}
/**
* A helper class that does HTTP GETs and calls back a function with
* the content it receives. Asynchronous, so uses a closure for the
* callback.
*
* Note, that XMLFetcher is only used for SafeBrowsing, therefore
* we inherit from nsILoadContext, so we can use the callbacks on the
* channel to separate the safebrowsing cookie based on a reserved
* appId.
* @constructor
*/
function PROT_XMLFetcher() {
this.debugZone = "xmlfetcher";
this._request = PROT_NewXMLHttpRequest();
// implements nsILoadContext
this.appId = Ci.nsIScriptSecurityManager.SAFEBROWSING_APP_ID;
this.isInBrowserElement = false;
this.usePrivateBrowsing = false;
this.isContent = false;
}
PROT_XMLFetcher.prototype = {
/**
* Function that will be called back upon fetch completion.
*/
_callback: null,
/**
* Fetches some content.
*
* @param page URL to fetch
* @param callback Function to call back when complete.
*/
get: function(page, callback) {
this._request.abort(); // abort() is asynchronous, so
this._request = PROT_NewXMLHttpRequest();
this._callback = callback;
var asynchronous = true;
this._request.open("GET", page, asynchronous);
this._request.channel.notificationCallbacks = this;
// Create a closure
var self = this;
this._request.addEventListener("readystatechange", function() {
self.readyStateChange(self);
}, false);
this._request.send(null);
},
cancel: function() {
this._request.abort();
this._request = null;
},
/**
* Called periodically by the request to indicate some state change. 4
* means content has been received.
*/
readyStateChange: function(fetcher) {
if (fetcher._request.readyState != 4)
return;
// If the request fails, on trunk we get status set to
// NS_ERROR_NOT_AVAILABLE. On 1.8.1 branch we get an exception
// forwarded from nsIHttpChannel::GetResponseStatus. To be consistent
// between branch and trunk, we send back NS_ERROR_NOT_AVAILABLE for
// http failures.
var responseText = null;
var status = Components.results.NS_ERROR_NOT_AVAILABLE;
try {
G_Debug(this, "xml fetch status code: \"" +
fetcher._request.status + "\"");
status = fetcher._request.status;
responseText = fetcher._request.responseText;
} catch(e) {
G_Debug(this, "Caught exception trying to read xmlhttprequest " +
"status/response.");
G_Debug(this, e);
}
if (fetcher._callback)
fetcher._callback(responseText, status);
},
// nsIInterfaceRequestor
getInterface: function(iid) {
return this.QueryInterface(iid);
},
QueryInterface: XPCOMUtils.generateQI([Ci.nsIInterfaceRequestor,
Ci.nsISupports,
Ci.nsILoadContext])
};