I need to build a config that serves only image files. Any other request is a 404 (or other error, or maybe a 1 pixel png).

Presumably actually checking the files themselves is not possible (certainly not fast), so it would have to be based on file extension? Assuming this to be true, then I will have a whitelist of suffixes. I'd like to make enforce the headers on these.

My google-fu is not helping me today, any pointers?