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RE: more on digest (was: Unidentified subject!)

From: Paul Leach <paulle@microsoft.com>
Date: Wed, 17 Dec 1997 13:49:22 -0800
Message-Id: <5CEA8663F24DD111A96100805FFE6587203898@red-msg-51.dns.microsoft.com>
To: John Franks <john@math.nwu.edu>, "'Roy T. Fielding'" <fielding@kiwi.ics.uci.edu>
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Does it (Apache proxy) canonicalize any other headers? If the incoming Date,
L-M, and Expires are already canonical, does the exact string value change
(spaces inserted, e.g.)?

> ----------
> From: 	Roy T. Fielding[SMTP:fielding@kiwi.ics.uci.edu]
> Sent: 	Wednesday, December 17, 1997 11:11 AM
> To: 	John Franks
> Cc: 	http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> Subject: 	Re: more on digest (was: Unidentified subject!)
> 
> >The only reason this came up at this point was that because a hash
> >of the Date, L-M and Expires headers can be part of the response
> >there could be a problem for servers with no clock if a proxy added
> >a Date header.  There is a simple answer to this which is that
> >proxies should not be allowed to add or change Date, L-M or Expires
> >headers.  There are no known implementations which do so and no one
> >has suggested any reason it is necessary to do so.
> 
> An HTTP/1.1 cache is required to change Date and Expires upon receipt
> of a 304 response containing updated values for those fields.  This
> does impact non-shared caches, so you will need to add something to the
> effect of the digest should be removed if those fields are updated.
> 
> The Apache proxy canonicalizes the response field-values of Date,
> Last-Modified, and Expires to the required HTTP-date format.  I have
> no idea what effect this would have on entity-digest.  If it caches
> the response, the cache will add Date and Content-Length if they are
> missing, but it won't normally cache the response if the request
> included Authorization (this would not be the case if we ever
> developed a personal, non-shared proxy).
> 
> ....Roy
> 
Received on Wednesday, 17 December 1997 14:11:10 EST

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