Date: Sun, 18 Apr 2021 16:50:28 +0200 From: Michael Tuexen <tuexen@freebsd.org> To: Jeremy Harris <jgh@wizmail.org> Cc: "transport@freebsd.org" <transport@freebsd.org> Subject: Re: TCP Fast Open Message-ID: <AE836EB0-0A4F-4E0A-9D84-C0807A1D00EF@freebsd.org> In-Reply-To: <7c17539a-b50f-bf52-b55b-5d9b1cc3caad@wizmail.org> References: <7c17539a-b50f-bf52-b55b-5d9b1cc3caad@wizmail.org>
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> On 18. Apr 2021, at 14:49, Jeremy Harris <jgh@wizmail.org> wrote: >=20 > Could I put in a request for better observability? That is, for > an application to be able to tell (for both client and server cases) > if TFO was not tried / requested successfully / used with no data / > used with data ? Sure. It is on my plate and tracked in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D242492 >=20 > There is partial observability currently, via sockopts TCP_FASTOPEN > and TCP_INFO... and they are unreliable. >=20 > [ I'll note here that Linux is no better ] >=20 >=20 > Also, a means for getting data on the SYN,ACK packet. Currently > AFAIK we cannot; we can send data from the server (under TFO) before > the ACK of the SYN,ACK but only as a separate packet. >=20 > The use case in mind is SMTP, which is a server-first protocol. > Whether or not the facility would have to restrict to preloaded data, > or could manage an application interaction, is up for argument. So what you have in mind is a client using TCP fastopen, which does not send user data with the SYN segment, but the server sending its banner with the SYN-ACK. Is that the use case you are referring to? If that is the case, can you add that description to PR 242492? Best regards Michael > --=20 > Cheers, > Jeremy > _______________________________________________ > freebsd-transport@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-transport > To unsubscribe, send any mail to = "freebsd-transport-unsubscribe@freebsd.org"
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