need to write a fitler based on request header

["J. Peng" <suppressed>]

Hello members,

I need to write an input filter based on the request headers.
If request includes a "Accept-Encoding:	gzip, deflate" header, I
should redirect the request to /pathA.
If request doesn't include that header, I should redirect the request to /pathB.
(pathA and pathB are web document dirs on web server.)

How to do it? thanks.