Finding out content type before logging process:

Hey guys!

I need to know if there’s a way to find out the content type of content
going through the proxy before the logging process.

I can use $upstream_http_content_type for logging the information, but I
need to access the value before outputting the page to the browser. The
http_content_type and send_http_content_type variables mentioned on the
Proxy page are empty.

Thanks in advance,