Re: [quicwg/base-drafts] If you want a Stateless Reset you need to send a much larger packet than before (#2770)

Mike Bishop <notifications@github.com> Thu, 06 June 2019 22:57 UTC

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From: Mike Bishop <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] If you want a Stateless Reset you need to send a much larger packet than before (#2770)
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The problem is that while you as a server can do that, the question here is what size packet the client needs to send to provoke that behavior from a _generic_ server.  And the server can't just base it on the CID size that it uses locally, because what really matters is size relative to other packets flowing in that direction, i.e. the client's CID.  Which will often be zero, but can be immense and we need to account for that.

We currently say:
> An endpoint can increase the odds that a packet will trigger a Stateless Reset if it cannot be processed by padding it to at least 40 bytes.

There's a crazy way out by embedding your own minimum CID size (either unencrypted or non-privately) in every packet so that a server can use that to determine whether it could safely send you a smaller SR.  But adding an extra byte to all packets to save ~30 bytes per keepalive doesn't seem likely to work out well.

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