Preserving all original request headers through a proxy_pass ?

[Rasmus Lerdorf]

I'm probably being a bit lazy here, I have only skimmed the code, but is
there a way to bounce all original request headers through a proxy_pass
prefixed with X-Orig-* or something like that?

One reason for wanting to do this is for proxy detection.  Common
headers that are important to preserve are HTTP_X_FORWARDED, HTTP_VIA
and HTTP_PROXY_CONNECTION.

-R