Re: [rtcweb] URI schemes for TURN and STUN

[Eric Rescorla <[e-mail]>]

On Sat, Nov 5, 2011 at 10:20 AM, Ned Freed <[e-mail]> wrote:
>> On 11/04/2011 04:56 PM, Eric Rescorla wrote:
>> > On Fri, Nov 4, 2011 at 8:31 AM, Ned Freed<[e-mail]>  wrote:
>> >>> Top-posting a general principle, detailed comment at the bottom....
>> >>> For all URI schemes, I think the URI needs to contain all the
>> >>> information you need in order to make contact with the service; you
>> >>> can't negotiate until you've made contact.
>> >>> (the process may involve things like "resolve through a resolution
>> >>> mechanism like DNS" or "get authorization tokens from somewhere
>> >>> else").
>> >>> In the case of TURN, you need to distinguish between TCP, UDP and TLS,
>> >>> and you need to make that determination before you send the first
>> >>> packet. That means the distinguishing information between those three
>> >>> things belongs in the URL; I don't think the scheme is a good place to
>> >>> encode it.
>> >> I'm in complete agreement with Harald on all of these points. And while
>> >> it
>> >> would have been nice if URL syntax was less messy and more general,
>> >> making
>> >> it easier to do these sorts of things in a consistent way, it quite
>> >> simply
>> >> isn't and we have to make do with what we have.
>> > I don't have any commitment to the scheme. What's the best place?
>
>> I like parameters, like this:
>
>> turn://user@host?proto=tcp
>
>> Quite hard to misunderstand, and quite easy to extend.
>
>> (Note: // is only allowed if what follows is [user[:pass]@]host - I
>> don't recommend using the password, for the obvious reasons, but the
>> syntax will allow it.)
>
> Given your earlier characterization of the TCP/UDP/TLS distinction being
> a single axis, I assume you mean that you'd say:
>
>  turn://user@host?proto=tls
>
> and not
>
>  turns://user@host?proto=tcp
>
> I have to say I prefer the parameter approach, but I wonder if these really
> are along a single axis - is DTLS a possibility here?

TCP/TLS
UDP/DTLS
TCP/DTLS

Are all options. Also, it seems like you might want to run DCCP or SCTP
and those work with DTLS and {DTLS,TLS} respectively. So, probably
better to make the parameters separate.

-Ekr