[erlang-questions] State of use_srtp ext in DTLS and TLS 1.3 support.

[Ingela Andin]

Hi Albin!

Den tors 14 mars 2019 kl 15:38 skrev Albin Stigö <albin.stigo@REDACTED>:

> Hi Ingela,
>
> Thanks for the quick reply!
>
> While cb_info certainly is one way of doing it, it feels a bit
> complicated... specifically if switching between active and passive
> mode. Not sure if ssl ever use passive mode internally? Demuxing is a
> different use case, I think..
>
>
The cb_info is intended so that you may replace the transport layer, with
most likely, an SCTP transport (can be done for  both TLS and DTLS
although there are some extensions needed for the DLTS version to work
properly). I think some people also use it to implement WebSockets.

ssl internally uses active n for TLS (since latest release) and active once
for DTLS (we might change it) but an OTP supervised process will not use
passive recv as we do not want it to block.



> Something that IMHO would be fantastic and simple (?) would be a
> dtls_filter_fun option. If true packet is passed up the ssl stack,
> otherwise passed on like a normal udp packet!
>
>
Sounds reasonable. Otherwise sent to some other Erlang process than the
"DTLS-connection" process that is.



> There's an RFC regarding the demultiplexing of SRTP/DTLS, it basically
> boils down to looking at the first byte of the packet, if it's
> [20..63] it should be treated as DTLS otherwise something else. So
> this would be absolutely trivial to implement if there was a
> dtls_filter_fun...
>
> https://tools.ietf.org/html/rfc7983
>
> Then of course there also has to be a way to bypass DTLS when sending
> data... maybe send/3 (Socket, Data, Options)...
>
>
Maybe transport_send as compared to the existing  transport_accept. Would
only work for DTLS.

Regards Ingela Erlang/OTP team  - Ericsson AB


> What do you think?
>
>
> --Albin
>
> On Thu, Mar 14, 2019 at 1:52 PM Ingela Andin <ingela.andin@REDACTED>
> wrote:
> >
> > Hi!
> >
> > Den tors 14 mars 2019 kl 12:29 skrev Albin Stigö <albin.stigo@REDACTED
> >:
> >>
> >> Hi,
> >>
> >> I'm working on an Erlang WebRTC peer client (to send audio/video to
> >> the browser).
> >>
> >> WebRTC requires dtls-srtp and that in turn requires:
> >>
> >> 1. The use_srtp extension for key exchange.
> >
> >
> > We will be implementing this as part of TLS-1.3 that we are currently
> working on, and we will have something runnable for OTP-22.0, although we
> are not promising that it will complete or that use_srtp will be part of
> OTP-22.0
> >
> >
> >>
> >> 2. Multiplexing of stun/turn/srtp packets on the socket.
> >>
> >> I know there's been work towards use_srtp and it's even in the source,
> >> but commented out. Ingela has been working on it for OTP 2, I believe,
> >> is there an ETA on this feature?
> >
> >
> >>
> >>
> >>
> >> Is multiplexing on the DTLS socket already possible using the cb_info?
> >> Has anyone tried that?
> >>
> >> http://erlang.org/pipermail/erlang-questions/2018-October/096457.html
> >>
> >
> > The code has been written to make such extensions possible. There might
> be a need for more callbacks. I have not really had time to work on that as
> > TLS-1.3, optimizations and erlang distribution over TLS has been
> prioritized higher.  Suggestions are welcome.
> >
> > Regards Ingela Erlang/OTP team - Ericsson AB
> >
> >
> >
> >
> >>
> >>
> >> --Albin
> >> _______________________________________________
> >> erlang-questions mailing list
> >> erlang-questions@REDACTED
> >> http://erlang.org/mailman/listinfo/erlang-questions
>
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