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RE: Question about RFC7540 (HTTP/2) section 10.5.1

From: Lucas Pardue <Lucas.Pardue@bbc.co.uk>
Date: Fri, 6 Apr 2018 15:29:05 +0000
To: 安福一樹 <kazuki_yasufuku@dwango.co.jp>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-ID: <7CF7F94CB496BF4FAB1676F375F9666A3BB1BC84@bgb01xud1012>

IMO from reading the specs, both RFC 7540 and 7230 apply. 7230 talks about individual header fields (and sets), while 7540 talks about the header block (the serialized combination of all header fields for a particular message).

FWIW it sounds like an implementation/config issue to me. What is the size of SETTINGS_MAX_HEADER_LIST_SIZE for these connections? It seems like that size is smaller than the check in your HTTP/1.1 case.

I’m inclined to think that it is valid for a server to first send a 4XX response, followed by a GOAWAY with ENHANCE_YOUR_CALM. I’d be interested to hear what others think.


From: 安福一樹 [mailto:kazuki_yasufuku@dwango.co.jp]
Sent: 06 April 2018 07:58
To: ietf-http-wg@w3.org
Subject: Question about RFC7540 (HTTP/2) section 10.5.1


I am a developer of this HTML5 game upload site https://game.nicovideo.jp/atsumaru/

I have some question about RFC7540 section 10.5.1.
Why server "CAN" send an HTTP 431 status code when receives a larger header block (not MUST)?

In http/1.1 connection, server MUST respond 4xx status code when receives a larger header.(RFC7230)
So, if user access a site that can upload any javascript code, and get large cookies, then we can send customized HTTP 4xx response which contains erasing cookie code.
But, in http/2, server does not need to send HTTP 431 response, we will not have a chance to erase cookies.

In actual implementaion, nginx will terminate http/2 session with ENHANCE_YOUR_CALM error without any HTTP responses, so chrome will display "cannot connect to server",
So, we cannot send response which contains erasing cookie code to user who plays a game contains "Cookie Bomb".

So, we have two questions.
first question: why changed the text from "CAN" to "MUST" when recieves a large cookies(headers).
second question: is this problem an implementation issue or a specification problem?


Kazuki Yasufuku

Kazuki Yasufuku

Software Engeneer, UGC game platform section

DWANGO Co., Ltd.



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Received on Friday, 6 April 2018 15:29:37 UTC

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