I tried calling:
Application.ExternalEval("UnityObject2.instances[0].getUnity().SendMessage('GameObjectName', 'SomeFunctionHere', document.URL);");
Which works great, but it could only retrieve the frame's url (it is a very long random html link) instead of the outer top most like https://apps.facebook.com/appnamehere. I also tried window.top.location.href but it gives me a security error since it wasn't allowed.
I need to process the url before I even init, so I cannot use fb's deeplink or anything like that. Any ideas on how to get the url? I'm using 5.0.4 of the SDK on Facebook Canvas.
Because of cross-domain security, it isn't possible to get the top url.