A summary of what I want to do is to redirect requests for image URL's that don't come from Amazon's CloudFront service to CloudFront. This is because I'm using origin pull, but what the redirect to be done at the nginx level.

Obviously this won't work:

rewrite ^/(.*).(png|gif|jpg) http://abc.cloudfront.net/$1.$2

because CloudFront's original requests will be redirected to itself, and also because I've got some further rewriting going on for WordPress image uploads (such that /files/myimage.png will be redirected to a PHP script for some sites, so I need that redirect to still happen and the one above to be bypassed in those instances when CloudFront is trying to do it's original lookup).

What I want to do is basically say:

if ($remote_addr !~ "abc.cloudfront.net") {
rewrite ^/(.*).(png|gif|jpg) http://abc.cloudfront.net/$1.$2
}

but this isn't possible (as remote_addr is an IP that may change) and is probably inefficient. Is there a correct way to redirect everything to a hostname that doesn't come from the hostname itself efficiently?