Design Issue: Must Ignore Rule for Unknown Frame Types
James M Snell <jasnell@gmail.com> Thu, 25 April 2013 23:00 UTC
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From: James M Snell <jasnell@gmail.com>
Date: Thu, 25 Apr 2013 15:58:39 -0700
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Subject: Design Issue: Must Ignore Rule for Unknown Frame Types
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https://github.com/http2/http2-spec/issues/80 In the current draft (-02) we say, "Implementations MUST ignore unsupported and unrecognized frame types." but we give no guidance that I can find about handling unknown frames that potentially modify session state. For example, suppose some extension comes up with a new frame type that includes a compressed header block. The receiving endpoint will have no way of interpreting the content, but if it ignores the frame entirely, it's stored session state can unknowingly fall out of sync with the sender. Recommendation: rather than a "MUST IGNORE" rule here, unknown and unrecognized frame types ought to be a Session Error because the receiver cannot determine whether and how those frames may have changed the session state on the sending side. It would not be safe for the receiver to continue attempting to communicate with the sender on that session. This obviously has an impact on the extensibility of the framing layer. In short, a sender would not be able to use a new frame type unless it knows the receiver can interpret it. The only solution for that would be to have some kind of negotiation occur where the sender effectively ask the recipient if particular extensions are supported (as part of the session header perhaps?)
- Design Issue: Must Ignore Rule for Unknown Frame … James M Snell
- Re: Design Issue: Must Ignore Rule for Unknown Fr… Martin Thomson
- Re: Design Issue: Must Ignore Rule for Unknown Fr… James M Snell
- Re: Design Issue: Must Ignore Rule for Unknown Fr… William Chan (陈智昌)