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Re: [MMUSIC] draft-dtls-sdp: Allow offerer to establish DTLS association before it has received the SDP answer?

Martin Thomson <martin.thomson@gmail.com> Tue, 23 May 2017 10:05 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Tue, 23 May 2017 20:04:52 +1000
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To: Christer Holmberg <christer.holmberg@ericsson.com>
Cc: Eric Rescorla <ekr@rtfm.com>, Roman Shpount <roman@telurix.com>, "mmusic@ietf.org" <mmusic@ietf.org>
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Subject: Re: [MMUSIC] draft-dtls-sdp: Allow offerer to establish DTLS association before it has received the SDP answer?
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On 23 May 2017 at 19:59, Christer Holmberg
<christer.holmberg@ericsson.com> wrote:
> If I understand correctly, you seem to suggest that we allow the handshake
> to ³proceed² (see 1st paragraph of your reply), but not to ³complete². If
> so, which endpoint is responsible to make sure that it doesn¹t ³complete²?

Whichever endpoint is unable to acquire the information it needs in
order to determine that the handshake is good.

>>Second in preference to that is to allow received data to be saved,
>>but not used.  In no circumstance should we allow data to be *sent*.
>
> I assume that also includes e.g., SCTP messages, i.e., in case of a WebRTC
> Data Channel it wouldn¹t be allowed to establish the SCTP association.

Yes, if you don't know to whom you are sending things, the only safe
action is not to send.  You can carve out exceptions for things like
handshaking SCTP on the proviso that they are found to contain no
actionable content, but that's tricky.

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