Re: [quicwg/base-drafts] Padding requirement seems to be incorrect. (#3053)

ekr <> Tue, 01 October 2019 20:44 UTC

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Date: Tue, 01 Oct 2019 13:44:32 -0700
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Subject: Re: [quicwg/base-drafts] Padding requirement seems to be incorrect. (#3053)
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> I think the specification should mandate padding of server initial packets as well.
> When I was traveling a couple weeks ago, I was on a network where, when using IPv6, it allowed 1200-byte UDP packets through from client to server but blackholed them from server to client. Since our implementation pads initials in both directions, we were able to detect this failure during the handshake and fall back to TCP/TLS. If the server didn't pad its initials, we would have succeeded at the handshake but never gotten an HTTP response.

This *definitely* seems like a design issue. The purpose of the padding rule is solely to limit amplification, not to establish a minimum MTU. If you want some sort of MTU rule, that should be discussed separately.

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