从Firefox扩展中取消HTTP GET请求

Question

I have a firefox extension that listens to "http-on-modify-request" and inspects all GET requests coming from firefox. I'd like to be able to cancel the request (say return a fail code to the page) or modify the URI of the request but can't seem to do it. the nsiHttpChannel object just doesn't allow it - for instance

delete httpChannel;

or reseting to an empty request

httpChannel = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Components.interfaces.nsIXMLHttpRequest);

don't work (and you can't modify the URI).

So how do you both intercept and modify http GET requests in a firefox extension.

Answer 1

delete httpChannel; just deletes the variable, sort of like saying httpChannel = undefined; . The request itself is unchanged. Similarly, your second idea just sets the variable to point at a new nsIHttpChannel instance, but the old request is still unchanged.

To modify the request, use its properties and methods. See nsIHttpChannel or nsIChannel or nsIRequest . As you say, you can't modify the URI so you might want to cancel it (see below) and replace it with a new one. I'm not sure exactly how to do that but I imagine one of those three pages has the answer.

To cancel it, use nsIRequest.cancel()