Access parent URL from iframe

Question

Okay, I have a page on and on this page I have an iframe. What I need to do is on the iframe page, find out what the URL of the main page is.

I have searched around and I know that this is not possible if my iframe page is on a different domain, as that is cross-site scripting. But everywhere I've read says that if the iframe page is on the same domain as the parent page, it should work if I do for instance:

parent.document.location

parent.window.document.location

parent.window.location

parent.document.location.href

... or other similar combos, as there seems to be multiple ways to get the same info.

Anyways, so here's the problem. My iframe is on the same domain as the main page, but it is not on the same SUB domain. So for instance I have

http:// www.mysite.com/pageA.html

and then my iframe URL is

http:// qa-www.mysite.com/pageB.html

When I try to grab the URL from pageB.html (the iframe page), I keep getting the same access denied error. So it appears that even sub-domains count as cross-site scripting, is that correct, or am I doing something wrong?

Answer 1

Yes, accessing parent page's URL is not allowed if the iframe and the main page are not in the same (sub)domain. However, if you just need the URL of the main page (i.e. the browser URL), you can try this:

var url = (window.location != window.parent.location)
            ? document.referrer
            : document.location.href;

Note:

window.parent.location is allowed; it avoids the security error in the OP, which is caused by accessing the href property: window.parent.location.href causes "Blocked a frame with origin..."

document.referrer refers to "the URI of the page that linked to this page." This may not return the containing document if some other source is what determined the iframe location, for example:

• Container iframe @ Domain 1
• Sends child iframe to Domain 2
• But in the child iframe... Domain 2 redirects to Domain 3 (i.e. for authentication, maybe SAML), and then Domain 3 directs back to Domain 2 (i.e. via form submission(), a standard SAML technique)
• For the child iframe the document.referrer will be Domain 3, not the containing Domain 1

document.location refers to "a Location object, which contains information about the URL of the document"; presumably the current document, that is, the iframe currently open. When window.location === window.parent.location, then the iframe's href is the same as the containing parent's href.