W3C home > Mailing lists > Public > ietf-http-wg@w3.org > April to June 2014

Re: PING frame behavior

From: David Krauss <potswa@gmail.com>
Date: Sun, 20 Apr 2014 10:50:11 +0800
Cc: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-Id: <B259F847-7805-4762-9806-76FE4109D361@gmail.com>
To: Alek Storm <alek.storm@gmail.com>

On 2014–04–20, at 5:55 AM, Alek Storm <alek.storm@gmail.com> wrote:

> 1. Are PING frame receivers obligated to respond with PING+ACK?
> 2. Must the PING+ACK payload be identical to that of the original PING?

From the spec: “Receivers of a PING frame that does not include an ACK flag MUST send a PING frame with the ACK flag set in response, with an identical payload.”

If you don’t want a reply but only side-band communication, you may send a PING with ACK pre-set. The spec defines behavior for this case and does not mention a protocol violation.

> 3. May the sender generate additional PING frames before the first is ACK’d?

Why not? There’s no state. Also, the other end can’t reliably tell the difference.

> 4. May intermediaries forward PING frames?

Where would they get forwarded? End-to-end would be nice, but without a stream ID you can usually only go one hop. The spec leaves a little ambiguity, which seems OK to me.

Come to think of it, was end-to-end, stream-wise PING considered and rejected for a particular reason? I guess it would tend to flood origin servers that are usually cached, so that’s a major vulnerability.
Received on Sunday, 20 April 2014 02:50:48 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:14:30 UTC