Re: [rtcweb] How to determine TLS roles?

[Tim Panton <[e-mail]>]

On 10 Feb 2014, at 13:51, Christer Holmberg <[e-mail]> wrote:

> Hi,
> 
>>> If I understand correctly, in RTCWEB we are going to use a single DTLS association for two things:
>>> 
>>> 1)      Key exchange for SRTP
>>> 2)      The data channel
>>> 
>>> Now, this means that there needs to be a generic way to determine the TLS roles.
>>> 
>>> In WEBRTC, how are the TLS roles determined?
>> 
>> That was the subject of a rant of mine.
>> 
>> I think the correct answer is that the party that ends up being IceControlling then becomes the DTLS client. Typically the initiator of a session is IceControlling. 
>> 
>> However the recent addition of
>> a=setup:passive
>> to chrome's SDP clouds the story somewhat, allowing an IceController to say that it is DTLS passive and allow the non-initiator to be the DTLS client.
>> 
>> Ostensibly this is to support early media - where the receiver of a call wishes to send media before the initiator does.
>> 
>> As I said (rather intemperately) this added complexity is not worth the benefit.
> 
> I think that it should be possible for a JS App to explicitly set the roles.
> 
> Because, when SDP O/A is used on the wire, there are specified rules on how the roles are determined. But, some other on-the-wire protocol may have different rules.
> 
> Regards,
> 
> Christer
> 

There are many things that the JS app will need to do if we aren't bound by SDP O/A - but I agreed not to talk about that -
until after 1.0 gets out :-)

T.