Cross site scripting on the same domain, different sub domains

I have an iframe I'm using to pull in some content hosted by a 3rd party vendor to our website. We are trying to determine the height of that content to adjust the iframe height but I'm getting cross site scripting errors. I wasn't aware that sub-domains count as a cross-site. Is there some way around this witho开发者_高级运维ut having to keep them on matching sub-domains?

For reference, our weekly marketing is hosted by the 3rd party vendor in flash but with the sub-domain we can redirect to them while keeping the user on our domains for cookie purposes.

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From one of your subdomains, you can (with some exceptions) set the domain to allow broader access to other subdomains in the same main domain.

Take a look at this page: http://www.tomhoppe.com/index.php/2008/03/cross-sub-domain-javascript-ajax-iframe-etc/

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Also take a look at cross window messaging

This first page is the sender - it's calling postMessage (sending the textual message) and also holds the iframe within which the receiving window is held.

<iframe src="http://dev.jquery.com/~john/message/" id="iframe"></iframe>
<form id="form">
  <input type="text" id="msg" value="Message to send"/>
  <input type="submit"/>
</form>
<script>
window.onload = function(){
        var win = document.getElementById("iframe").contentWindow;
        document.getElementById("form").onsubmit = function(e){
                win.postMessage( document.getElementById("msg").value );
                e.preventDefault();
        };
};
</script>

The follow page is the receiver - it has an event listener bound which watches for messages being passed to it and injects them in to the DOM.

<b>This iframe is located on dev.jquery.com</b>
<div id="test">Send me a message!</div>
<script>
document.addEventListener("message", function(e){
        document.getElementById("test").textContent =
                e.domain + " said: " + e.data;
}, false);
</script>