Re: H2 vs responses which should not carry any payload

[Bence Béky <[e-mail]>]

Hi Willy,

On Fri, Oct 23, 2020 at 12:57 AM Willy Tarreau <[e-mail]> wrote:
>
>
> And even then, do all implementations accept, say, a HEADERS frame with
> no ES flag in response to a HEAD request, followed by an empty DATA frame
> carrying the ES flag ? At the semantic level it's OK since there's no
> payload, but I can understand how some could find it annoying to wait
> for DATA frames when no payload is expected (it's our case as well as
> part of the possible fixes for this).
>
>

At some point during the GREASE experiments Chrome removed the
END_STREAM flag from every HEADERS frame, then sent a frame of
reserved type, then an empty DATA frame with END_STREAM, and I found
that not every server accepts this.  To my best knowledge WinHTTP
still fails to process such a request (ever without the reserved
frame) if the request method is GET.  My interpretation of RFC7540 is
that such a request is spec compliant, but in practice Chrome cannot
send them at this point.  (The GREASE experiment continues only on
requests with a request body.)

Bence