Get User-Agent and IP Address of object anonymously uploaded to S3?

Is there a way to retrieve the User-Agent and/or IP Address of the client that uploaded an object anonymously to an S3 bucket?

I'm using an anonymous upload method similar to this: http://ift.tt/15Ei0qa

which shows a method of testing against the client's User-Agent (via. aws:UserAgent in a StringNotEquals block in the Condition block), and there is documentation that shows that aws:SourceIp exists as well, but I see no way of grabbing either after the file has been uploaded.

Am I missing something?