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Proxies and broken HTTP

From: Miles Sabin <msabin@cromwellmedia.co.uk>
Date: Fri, 10 Sep 1999 13:25:13 +0100
Message-ID: <c=US%a=_%p=Cromwell_Media%l=ODIN-990910122513Z-205@odin.cromwellmedia.co.uk>
To: "'http-wg@hplb.hpl.hp.com'" <http-wg@hplb.hpl.hp.com>
I'd be grateful for some advice on how the slogan
'applications should be liberal in what they receive and 
conservative in what they send' should be applied to
proxy servers.

The particular case I have in mind is an origin server
(which shall remain nameless) returning an entity body
with a 304. The client-side of our proxy is liberal 
enough to cope with this on receipt, but the server-
side conservatively refuses to forward it.

In this scenario it seems pretty reasonable to discard 
the entity: there's no way of reporting an error back
to the origin server, and it seems a bit extreme to send
the client a 502. But trying to generalize to other
kinds of upstream and downstream bad behaviour opens up 
a can of worms. The options seem to be,

1. Forward broken HTTP.

2. Enforce strict conformance by responding to all bad
   requests with 400s and all bad replies with 502s.

3. Fixup up bad requests/replies on their way through 
   wherever possible.

(1) is pretty much out of the question; (2) is over the
top; and (3) is completely unspecified, so liable to be
done differently be different proxy implementors.

What to do?

Cheers,


Miles

-- 
Miles Sabin                          Cromwell Media
Internet Systems Architect           5/6 Glenthorne Mews
+44 (0)181 410 2230                  London, W6 0LJ
msabin@cromwellmedia.co.uk           England
Received on Friday, 10 September 1999 13:26:57 EDT

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