Re: Payload length 0

[Ian Swett <[e-mail]>]

I would also prefer to not do either of these, because I think it adds
complexity and the byte savings are tiny.

On Fri, May 18, 2018 at 1:34 AM Martin Thomson <[e-mail]>
wrote:

> Having just implemented this (and gotten it wrong once), I don't want more
> special cases.  Both of these options need extra code.  As Kazuho points
> out, filling in a two octet length is trivial.
>
> It's true that a length of 0 is invalid, but so is 1 through 16.
>
> Yes, this saves an octet, on about 4 packets per connection in the common
> case, more like 2 if you actually take advantage of compound packets.
> On Fri, May 18, 2018 at 3:08 PM Marten Seemann <[e-mail]>
> wrote:
>
> > Jana asked me to raise this issue on the list, after we already had a bit
> of discussion in https://github.com/quicwg/base-drafts/pull/1301.
>
> > The proposal is to make a payload length of 0 a special value, indicating
> that the packet is not a coalesced packet, i.e. that the whole payload of
> the UDP packet is the QUIC packet. This would eliminate an invalid value of
> the payload length (there are no empty packets), save one byte for packet
> lengths where varint encoding would result in a two byte number, and
> apparently also simplify (some) implementations.
>
> > Kazuho argued creating two versions of each Long Header type (one with
> and one without a payload length) is the better solution, since all values
> below the AEAD tag length + 1 are invalid values anyway, and it would save
> one more byte.
>
> > We should make a decision if and what we want to do about this.
>
>