[Openid-specs-ab] Form Post Response Mode example has 'Pragma: no-cache'

Brian Campbell bcampbell at pingidentity.com
Mon Feb 23 23:55:38 UTC 2015


But that text is about directives on the cache-control _request_ header.

The directives in question here are on the _response_.

https://tools.ietf.org/html/rfc7234#section-5.2.2 is about the response
directives. With https://tools.ietf.org/html/rfc7234#section-5.2.2.3 saying
this about "no-store",

   The "no-store" response directive indicates that a cache MUST NOT
   store any part of either the immediate request or response.  This
   directive applies to both private and shared caches.  "MUST NOT
   store" in this context means that the cache MUST NOT intentionally
   store the information in non-volatile storage, and MUST make a
   best-effort attempt to remove the information from volatile storage
   as promptly as possible after forwarding it.

While "no-cache" at https://tools.ietf.org/html/rfc7234#section-5.2.2.2
isn't as strong:

   The "no-cache" response directive indicates that the response MUST
   NOT be used to satisfy a subsequent request without successful
   validation on the origin server.  This allows an origin server to
   prevent a cache from using it to satisfy a request without contacting
   it, even by caches that have been configured to send stale responses.





On Mon, Feb 23, 2015 at 4:39 PM, Mike Jones <Michael.Jones at microsoft.com>
wrote:

>  Brian, “Cache-control: no-store” does not seem to imply “Cache-control:
> no-cache”.  I say that because of this sentence in 5.2.1.5 of
> https://tools.ietf.org/html/rfc7234#section-5.2.1:
>
>
>
>    Note that if a request containing this directive is satisfied from a
>
>    cache, the no-store request directive does not apply to the already
>
>    stored response.
>
>
>
> Therefore, to be safe, I believe that we have to replace the “Pragma:
> no-cache” in our example with “Cache-control: no-cache”.
>
>
>
> Do people agree with that conclusion?
>
>
>
>                                                             -- Mike
>
>
>
> *From:* John Bradley [mailto:ve7jtb at ve7jtb.com]
> *Sent:* Thursday, February 19, 2015 7:19 PM
> *To:* Mike Jones
> *Cc:* Brian Campbell; <openid-specs-ab at lists.openid.net>
> *Subject:* Re: [Openid-specs-ab] Form Post Response Mode example has
> 'Pragma: no-cache'
>
>
>
> Yes and yes.
>
>
>
>  On Feb 19, 2015, at 5:08 PM, Mike Jones <Michael.Jones at microsoft.com>
> wrote:
>
>
>
> First question to the working group:  Do we agree that "Pragma: no-cache" should
> be changed to "Cache-Control: no-cache" in the Form Post Response Mode
> spec before approval?
>
>
>
> Second question to the working group:  If we agree to make this change (to
> text that only occurs in a non-normative example), are people comfortable
> doing this without restarting the 60 day review period (but still notifying
> people of the change)?
>
>
>
> My personal answers would be “yes” and “yes” but we shouldn’t do this at
> this point unless there’s working group consensus to do so.
>
>
>
> Brian, could you also send a note to the OAuth working group pointing this
> problem with RFC 6749 and RFC 6750 and asking whether errata should be
> filed?  This would help get more expert eyes on the issue.
>
>
>
> Thanks for bringing this to our attention, Brian!
>
>
>
>                                                                 -- Mike
>
>
>
> *From:* Openid-specs-ab [mailto:openid-specs-ab-bounces at lists.openid.net
> <openid-specs-ab-bounces at lists.openid.net>] *On Behalf Of *Brian Campbell
> *Sent:* Thursday, February 19, 2015 2:17 PM
> *To:* <openid-specs-ab at lists.openid.net>
> *Subject:* [Openid-specs-ab] Form Post Response Mode example has 'Pragma:
> no-cache'
>
>
>
> The example response in
> http://openid.net/specs/oauth-v2-form-post-response-mode-1_0-03.html#FormPostResponseExample
>  has a "Pragma: no-cache" response header.
>
> However both RFC 2616 <http://tools.ietf.org/html/rfc2616#section-14.32> and
> the shiny new RFC 7234 <https://tools.ietf.org/html/rfc7234#section-5.4> make
> special note along the lines of the following to say that it doesn't work
> as response header:
>
>
>
>       'Note: Because the meaning of "Pragma: no-cache" in responses is
>
>       not specified, it does not provide a reliable replacement for
>
>       "Cache-Control: no-cache" in them.'
>
>
> It doesn't really hurt anything having it in the Form Post Response Mode
> document but I'm thinking it'd be better to not further perpetuate the
> "Pragma: no-cache" response header myth in this specification* and that
> that line should probably be removed from the example.
>
> Or am I wrong on this? And if so, what am I missing?
>
>
>
> * And, yeah, it's in Connect Core and OAuth 2.0 as well but I figured
> starting with a draft that wasn't yet final was good.
>
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>
>
>
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