Re: [TLS] Lost last DTLS Flight

[Eric Rescorla <ekr at networkresonance.com>]

At Mon, 27 Oct 2008 18:00:34 +0100,
Michael Tüxen wrote:
> 
> On Oct 27, 2008, at 4:24 PM, Eric Rescorla wrote:
> 
> > At Mon, 27 Oct 2008 12:07:59 +0100,
> > Robin Seggelmann wrote:
> >>
> >> We're still working on DTLS for SCTP and stumbled over a problem with
> >> the last flights specified in RFC 4347. The server receives flight 5
> >> (Certificate, ..., ChangeCipherSpec, Finished) from the client,
> >> changes its state to FINISHED and sends its ChangeCipherSpec and
> >> Finished (Flight 6). What happens if this flight gets lost? The
> >> server already is in the FINISHED state and as there also is no
> >> acknowledgement, so it won't be retransmitted. Hence, the client
> >> keeps waiting for the flight to arrive and the connection is most
> >> likely to fail.
> >
> > You're right, this is a bug in the state machine. Nice catch.
> >
> > ISTM that the way this actually needs to work is that the server needs
> > to stay in WAITING until 2MSL has expired, in case it receives a
> > retransmitted Flight 5, in which case it retransmits Flight 6.
> This means that the server will be in WAITING for approximately 30  
> seconds.
> What happens when the receives application data during that time?
> What happens if he want to transmit application during that time?
> for example after the renegotiation?

There's no reason why it can't transmit or receive during this period,
though I agree we need to be sure the text says this.

-Ekr

_______________________________________________
TLS mailing list
TLS at ietf.org
https://www.ietf.org/mailman/listinfo/tls