Re: [TLS] Last Call: <draft-ietf-tls-dtls-connection-id-10.txt> (Connection Identifiers for DTLS 1.2) to Proposed Standard

[tom petch <[e-mail]>]

On 13/03/2021 18:03, Thomas Fossati wrote:
> hi Tom,
>
> On 13/03/2021, 11:54, "tom petch" <[e-mail]> wrote:
>>> Is your suggestion to remove the parenthetical?  I.e.:
>>>
>>> OLD
>>>      A zero-length value indicates that the server will send with the
>>>      client's CID but does not wish the client to include a CID (or
>>>      again, alternately, to use a zero-length CID).
>>>
>>> NEW
>>>      A zero-length value indicates that the server will send with the
>>>      client's CID but does not wish the client to include a CID.
>>
>> Thomas
>>
>> Yes, that would fix this particular problem I have within this
>> section.
>>
>> I word it that way since I did raise two other doubts about the
>> wording in this section in my original post, one about successful
>> negotiation, which seems to me an undefined term, and one about
>> sending and receiving, which seems over-restrictive in the context.
>
> At the top of the thread, you suggested to change:
>
>>   If DTLS peers have negotiated the use of a CIDs using the ClientHello
>>   and the ServerHello messages
>
> into:
>
>>   If DTLS peers have negotiated the use of a non-zero CID in at least
>>   one direction, using the ClientHello and the ServerHello messages
>
> which is fine with me.
>
> However, I think it doesn't completely remove the ambiguity you are
> pointing at.  So I'd suggest we also change the paragraph just above
> from:
>
>     If DTLS peers have not negotiated the use of CIDs then the RFC
>     6347-defined record format and content type MUST be used.
>
> to:
>
>     If DTLS peers have not negotiated the use of CIDs, which includes the
>     case where both sent a zero-length cid in their connection_id
>     extensions, then the RFC 6347-defined record format and content
>     type MUST be used.

Thomas

Yes, I agree, that is needed as well.

Tom Petch

>
> Regarding your suggestion:
>
>> "The DTLS peers determine whether incoming and outgoing messages
>> need.." seems not to cater for unidirectional CIDs; perhaps
>> "The DTLS peers determine whether incoming or outgoing, or both,
>> messages need.."
>
> It surely works for me.
>
> cheers, thanks!
>
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