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

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 20 Nov 2007 11:09:08 +0100
Message-ID: <4742B244.8020506@gmx.de>
To: Bjoern Hoehrmann <derhoermi@gmx.net>
CC: HTTP Working Group <ietf-http-wg@w3.org>

Bjoern Hoehrmann wrote:
> E* Julian Reschke wrote:
>> We currently say in Section 4.2:
>>
>>    Multiple message-header fields with the same field-name MAY be
>>    present in a message if and only if the entire field-value for that
>>    header field is defined as a comma-separated list [i.e., #(values)].
>>
>> -- <http://tools.ietf.org/html/rfc2616#section-4.2>
>>
>> Now this seems to be kind of backwards, wouldn't it be *much* clearer if 
>> it said:
>>
>>    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..."?

>> That being said, do we have a recommendation for recipients when that 
>> requirement is violated? I would assume that servers SHOULD return a 400 
>> (Bad Request), but what about clients?
> 
> You fold them into a single value as the specification suggests unless
> there is some reason not to do that. Servers should not be required to

Well, for Content-Type the specification says you can't do that.

> respond with Bad Request, they might not know the header, and they
> should not treat
> 
>   X: a
>   X: b
> 
> differently from X:a,b, so if they don't give you a Bad Request for the
> latter, they should not do it for the former. I think the current text
> is fine.

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?

Best regards, Julian
Received on Tuesday, 20 November 2007 10:36:08 GMT

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