Ignored Cache-Control request header

[bcx]

I noticed that the nginx http proxy module by default does nothing with the
Cache-Control request header that is sent by browsers.

Most browsers (I tested Crome and Firefox, but from my online research it
showed that even Internet Explorer has the same behaviour) send a
Cache-Control: no-cache header when the page requested is with Ctrl-F5 (as
opposed to a normal F5 or page hit). I would like to configure my nginx
caching proxy to take this request as an instruction to invalidate the
cache, send a request to an upstream server, and send and cache that
response.

Note that I'm NOT talking about the Cache-Control header sent from upstream
webservers to the proxy. It's the Cache-Control request headers, not the
response header.

Is there a configuration option that I've missed? I spent quite some time
reading the documentation. Sadly the search terms that I can come up with
(cache-control, proxy, etc) are too generic for what I want to express.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,248326,248326#msg-248326