SECURITY_ERR: DOM Exception 18 when applying document.domain on both sites. How do I resolve this?

Question

I have a page at an internal server, server1.mydomain.com/page.jsp and another page at a different internal server, 10.x.x.x:8081/page.aspx.

On server1.mydomain.com, I set document.domain in page.jsp like this:

//page.jsp on server1.mydomain.com
document.domain = document.domain;

When I issue an alert on document.domain, it comes up as server1.mydomain.com.

On the 10.x.x.x server, I set document.domain in page.aspx, as a result, like this:

//page.aspx on 10.x.x.x
document.domain = "server1.mydomain.com";
// test if same-origin policy violation occurs
document.getElementById("div_el").innerHTML = window.top.location.href;

In Safari 5.1.5, an error pops up on the console:

SECURITY_ERR: DOM Exception 18: An attempt was made to break through the security policy of the user agent."

From what I understand, when you set document.domain, the port number is set to null; so, you have to set it on both ends, which I did. Then, this error occurs and I'm scratching my head why. Does this have anything to do with the fact I'm using 10.x.x.x and not an actual domain name?

Thank you.

Solution

You can only set document.domain to its current value or to a super-domain of the current setting. Thus, a page at "foo.something.com" can set it to "something.com", but not "something.else.com".

Comments

[user717236]

Thank you for your help. Yes, I think I understand it a bit better, now. These two hosts cannot communicate with each other with document.domain, as it is set up. I'll have to think of something else. Thanks again.