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Re: Weak validators in conditional requests

Eduard Bagdasaryan <eduard.bagdasaryan@measurement-factory.com> Thu, 06 September 2018 23:45 UTC

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From: Eduard Bagdasaryan <eduard.bagdasaryan@measurement-factory.com>
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Date: Fri, 07 Sep 2018 02:41:58 +0300
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Subject: Re: Weak validators in conditional requests
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Thanks, but 2616 changes mention only entity tags:
"Weak entity-tags are now allowed in all requests except range
requests.",
not considering If-Modified-Since, If-Unmodified-Since and
If-Range, I am concerned in.

Let's see an example: a proxy cached a response,
having two headers below:

[...]
Date: Tue, 15 Aug 2018 12:36:57 GMT
Last-Modified: Tue, 15 Aug 2018 12:36:27 GMT
[...]

According to https://tools.ietf.org/html/rfc7232#section-2.2.2,
we would need to use weak validator for Last-Modified
time, since the difference between these two fields
is less than 60 seconds.

Some time later, a client requests this cached resource
with a range GET request:

[...]
If-Unmodified-Since: Tue, 15 Aug 2016 12:36:27 GMT
Range: bytes=0-5
[...]

Can the proxy respond with 206 answer?
If no, are there any MUSTs in HTTPbis, prohibiting this?


On 04.09.2018 15:40, Julian Reschke wrote:
> On 9/4/2018 1:09 PM, Eduard Bagdasaryan wrote:
>> Yes, it is stated there, but only about If-Match and If-None-Match
>> headers. What about If-Modified-Since, If-Unmodified-Since
>> and If-Range?
>> ...
>
> See 
> <https://greenbytes.de/tech/webdav/rfc7232.html#changes.from.rfc.2616> 
> - so this was an intentional change.
>
> Best regards, Julian

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