How can I read xml from POST to IPN system?

I'm trying to make a IPN system work.

They post to my url an XML. I've tried to read it using simplexml_load_file but I can't. How can i read it?

Also, is there any way of logging the referrer of t开发者_JAVA百科he IP that is making the POST?

You want simplexml_load_string

You should be able to get the client's IP through $_SERVER["REMOTE_ADDR"]