Re: [quicwg/base-drafts] Remembering transport parameters (#3434)

martinduke <notifications@github.com> Tue, 25 February 2020 15:53 UTC

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Date: Tue, 25 Feb 2020 07:53:14 -0800
From: martinduke <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] Remembering transport parameters (#3434)
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@martinthomson I have trouble seeing why this isn't safe.

Let's say that we change the rule to say that servers MUST reject 0RTT if max_udp_payload_size has decreased. Then the client will send its Initial, plus a bunch of 0RTT, and then get a server extension that indicates that the server isn't accepting early data. A sensible congestion controller will then disregard the inevitable 0RTT packet losses.

If we allow 0RTT in this case, the client will send the same thing. The server doesn't get, or chooses to drop, any datagram that exceeds the new max size. A sensible congestion controller will see the updated TP and disregard 0RTT packet losses that exceeded the new max size.

The second scenario doesn't strike me as any more problematic than the other.

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