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Re: NEW ISSUE: repeating non-list-type-headers

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Tue, 20 Nov 2007 11:59:14 +0100
To: Julian Reschke <julian.reschke@gmx.de>
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <npc5k39cbhsnv5k4n7kp525t7k0b6ce22k@hive.bjoern.hoehrmann.de>

* Julian Reschke wrote:
>>>    Multiple message-header fields with the same field-name MUST NOT be
>>>    present in a message unless the entire field-value for that
>>>    header field is defined as a comma-separated list [i.e., #(values)].
>> 
>> No, unlike the old text, that does not say when you may use them.
>
>Ahem? "...unless the entire field-value..."?

You are turning "Messages may X iff Y" into "Messages must not X unless
Y"; if Y is true, with the old version you know "Messages may X", with
your version you just know you are not violating "Messages must not X".
It might well be that Messages SHOULD NOT include duplicates even then.

>Of course both forms should be treated the same. The question I was 
>asking: what is a recipient -- in particular a client -- supposed to do 
>with a message where header values are known to be invalid?

Where the specification does not say that, the client is supposed to do
something that's appropriate for the particular client and the circum-
stances it is acting in. Some clients may close the connection on sight
of the bad header, others might ignore it, others might process only
some part of it, and yet others might not notice the error at all. It's
unlikely there is a one size fits all recommendation we could make.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Tuesday, 20 November 2007 10:59:22 GMT

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