How to cancel http requests?

I'm tring to cancel HTTP request using aSubject.cancel(Components.results.NS_BINDING_SUCCEEDED); but it dont work. The code is given below. Can anyone please correct it?

function(aSubject, aTopic, aData)
{
    if ("http-on-modify-request" == aTopic)
    {
        //get the http request url
            var url = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel).originalURI.spec;

        //get the referer of http request (this error gives an error; dont know why :( 
        var a = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel).getRequestHeader("referer");

        //Cancel http request from other domains 
        if (url.split('//')[1].split('/')[0] != a.split('//')[1].split('/')[0])
        {
            //the code below don't work! Someone please correct it.
            //code to cancel http r开发者_开发知识库equest
            aSubject.cancel(Components.results.NS_BINDING_SUCCEEDED);
            }
    }
}

That's probably because NS_BINDING_SUCCEEDED isn't an error code (yes, the documentation seems to be wrong). What you actually want to use is Components.results.NS_BINDING_ABORTED.

By the way, you seem to be comparing the host name in the URL. Given that you already have an nsIURI object this can be done easier:

var requestHost = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel).originalURI.host;
var referrerHost = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel).referrer.host;
if (requestHost != referrerHost)
{
    aSubject.cancel(Components.results.NS_BINDING_ABORTED);
}