IP address from REST calling station

I have a project in which I have automated my ChickenCoop doors with a Yun, so I can control the status, but also manage the doors.
Now I am wondering how do i get the calling IP address for a REST command?

You want to get the IP of your Yun or the IP of the device that sends the REST command?

If you want to do the second, the device that sends the command can send its IP together with the command. So the Yun will receive the command and who sent it.