Re: "If-None-Match:" header

[Michiel Boland]

For CGI programs that want to use "ETag" values (e.g. MD5 hashes) to
avoid re-sending dynamically-generated content that hasn't changed since
the last time the client requested it, it's useful to have access to the
HTTP header "If-None-Match".

This HTTP header isn't passed in the environment from Mathopd at
present.  I don't know the Mathopd source, but I'm guessing it should be
easy to patch Mathopd to provide it?

Perhaps a more general solution would be useful, so that mathopd.conf
can say which HTTP headers we want to have passed to CGI programs:
possibly, all of them, at least for debugging...

Last time I looked Mathopd passes all HTTP headers to CGI programs. Well, 
at least 1.5 does this.

The If-None-Match header should be visible in the environment as 
HTTP_IF_NONE_MATCH

Cheers
Michiel