Re: [TLS] WGLC for draft-ietf-tls-ticketrequests

Rob Sayre <sayrer@gmail.com> Thu, 21 November 2019 06:18 UTC

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From: Rob Sayre <sayrer@gmail.com>
Date: Wed, 20 Nov 2019 22:18:26 -0800
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To: David Schinazi <dschinazi.ietf@gmail.com>
Cc: Martin Thomson <mt@lowentropy.net>, "TLS@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] WGLC for draft-ietf-tls-ticketrequests
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So, the current PR says:

"Clients can use TicketRequestContents.count to indicate the number of
tickets they would prefer to receive. Servers SHOULD NOT send more tickets
than TicketRequestContents.count, as clients will most likely discard any
additional tickets. Servers SHOULD additionally place a limit on the number
of tickets they are willing to send to save resources. Therefore, the
number of NewSessionTicket messages sent will be the minimum of the
server's self-imposed limit and TicketRequestContents.count."

I would suggest two edits to this text:

1: The second sentence can read: "If servers send more tickets than
TicketRequestContents.count, clients will likely discard excess tickets.".
This avoids a "SHOULD NOT" that should be a "MAY" or unmentioned.

2: The third sentence is implementation advice, not an interoperability
requirement: "Servers SHOULD additionally place a limit on the number of
tickets they are willing to send to save resources." I think this sentence
should be struck, or rewritten in non-2119 English. If the editors wish to
keep the text, I think there should be a comma after "send".

These proposed edits make sense to me, because servers can't know if their
tickets will be used successfully (network problems, unreliable clients,
etc).

thanks,
Rob


On Wed, Nov 20, 2019 at 9:45 PM David Schinazi <dschinazi.ietf@gmail.com>;
wrote:

> Thanks. I've updated the PR to take MT's suggestion s/SHOULD/will/.
>
> David
>
> On Thu, Nov 21, 2019 at 1:38 PM Martin Thomson <mt@lowentropy.net>; wrote:
>
>> On Thu, Nov 21, 2019, at 11:19, David Schinazi wrote:
>> >  resources. Therefore, the number of NewSessionTicket messages sent
>> >  SHOULD be the minimum of the server's self-imposed limit and
>> >  TicketRequestContents.count.
>>
>> Thanks for doing this David.
>>
>> Friendly amendment: remove the SHOULD from this sentence (it's a
>> consequence of the two other "SHOULD"s):
>>
>> Therefore, the number of NewSessionTicket messages sent will be the
>> minimum [...]
>>
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