How to do DTD in squid?

Hi, folks,

        I am trying to implement DTD in squid. The idea of
DTD is to send a HEAD request before GET to ask for
the Content-MD5 of a URL in the case of a URL miss. If
the returned Content-MD5 matches anything in the disk
cache (my disk cache is indexed by Content-MD5 values
instead of URLs), then it results in a cache hit.
Otherwise, it will have to run the GET request to
download the URL.

        Obviously, DTD disrupts squid's HTTP flow. So I am
stuck and don't know what to do... Here are my
questions:

1) Where should I make the Content-MD5 lookup after I
get a reply from my HEAD request?

2) The way I do DTD is to modify every METHOD_GET
request to METHOD_HEAD in clientProcessMiss. But then
when I am done downloading the HEAD reply, I am in
httpReadReply of http.c. storeClientCopy can't
run with clientCacheHit in http.c, so I can't handle
the case when there is a hit after I did a lookup in
my Content-MD5 table. How should I get around this
problem?

        I am hacking 2.4S7. You can find more information
about DTD by going to
http://devel.squid-cache.org/dtd/.

        Thanks in advance. Any help is appreciated.

Regards,
Yee Man

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Received on Wed Aug 21 2002 - 03:50:55 MDT