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Re: H2 vs HPACK header table size... again

From: Martin Thomson <mt@lowentropy.net>
Date: Fri, 24 Dec 2021 11:50:25 +1100
Message-Id: <7a8d5f72-9649-4e85-9fb9-0a18f32f49fc@www.fastmail.com>
To: "Kazuho Oku" <kazuhooku@gmail.com>
Cc: "HTTP Working Group" <ietf-http-wg@w3.org>
On Fri, Dec 24, 2021, at 10:54, Kazuho Oku wrote:
> In case of H2O / fastly.com, this is a FIXME that never has been fixed. 
> H2O ignores SETTINGS_MAX_TABLE_SIZE.

Ahh, that's not great.  It makes <4096 pretty perilous for clients.  I wonder if that is the same reason for other implementations.

I didn't realize that Cory merged #1003; I'm not that far through my email yet...  My intent was to keep this open a little.  I'll revert that and reopen it so that we can keep discussing it.

Given where things stand, the change you suggest in #1004 is probably positive from a compatibility perspective.  It allows implementations to ignore increases in the maximum.  For your implementation, all you have to do is deal with a reduction in the maximum table size more elegantly (I'd start with a connection error of type INTERNAL_ERROR).

See: https://github.com/httpwg/http2-spec/pull/1005

I thought for a while we needed to update RFC 7541 as a result, but a careful read reveals that we're OK.  The most interesting part is the caution about reducing the maximum size.  It was a little fiddly to write.
Received on Friday, 24 December 2021 00:51:00 UTC

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