Re: [quicwg/base-drafts] ACK of non-existent packet is illegal (#2302)

Marten Seemann <> Tue, 08 January 2019 01:10 UTC

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Subject: Re: [quicwg/base-drafts] ACK of non-existent packet is illegal (#2302)
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marten-seemann commented on this pull request.

>  acknowledgment of its ACK frames, with the knowledge this could cause the sender
 to unnecessarily retransmit some data.  Standard QUIC {{QUIC-RECOVERY}}
 algorithms declare packets lost after sufficiently newer packets are
 acknowledged.  Therefore, the receiver SHOULD repeatedly acknowledge newly
 received packets in preference to packets received in the past.
+An endpoint SHOULD treat receipt of an acknowledgment for a packet it did not
+send as a connection error of type PROTOCOL_VIOLATION, if it is able to detect

We had PROTOCOL_VIOLATIONs come up in interop testing a couple of times. The problem is, it tells you **exactly nothing** about what's going wrong.

gQUIC was (relatively) easy to debug, partly because it has a very long list of error codes. At some point (and I don't remember when and why), we decided to shrink that list to just around 10 error codes. Now we don't even have a single error code left for loss-recovery related errors - it's all just a PROTOCOL_VIOLATION.

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