Re: [MMUSIC] Changes for draft-ietf-mmusic-trickle-ice-sip-14 - ABNF

[Thomas Stach <[e-mail]>]

Christer,

thanks for the comments.

replies inline


On 2018-05-07 13:31, Christer Holmberg wrote:
> Hi,
>
> I am ok with the change.
>
> However, I think there are some issue with the ABNF (not related to Adam¹s
> issue).
>
> For example, the syntax says:
>
>     ice-pwd-attribute      = %s"a" "=" ice-pwd-att
>
>
>
> Then the draft says:
>
>     with ice-pwd-attribute from [I-D.ietf-mmusic-ice-sip-sdp],
>
which says

ice-pwd-att           = "ice-pwd:" password
i.e. doesn't introduce a second a=

>
> In my reading, this would result in:
>
>     a=a=ice-pwd:asd88fgpdd777uzjYhagZg
>
> Is this what you want?
No, and with the above syntax we do not get the a=a=

>
>
> If you want to use the syntax of draft-ietf-mmusic-ice-sip-sdp, why not do
> it directly? Something like:
>
>   session-level-field = ice-pwd-att /
>                         Š
>                         Š
>
>   ;ice-pwd-att as defined in [I-D.ietf-mmusic-ice-sip-sdp]
>
>
>
> Or, have I missed something?
The trickle-ice-sdpfrag syntax uses just a subset of SDP attributes and 
isn't  build as open as  the SDP syntax , the above doesn't work.

Kind Regards
Thomas
>
>
>
>
> Regards,
>
> Christer
>
>
>
>
>
>
>
>
>
>
>
> On 06/05/18 21:31, "Thomas Stach" <[e-mail]> wrote:
>
>> All,
>>
>> during IESG review we got the below proposal by Adam for changing the
>> ABNF to allow for more encoding flexibility.
>>
>> Unless somebody objects, I'd provide the proposed change by end of the
>> week.
>>
>> It would affect the "session-level-fields" as proposed below and in a
>> similar way the  "pseudo-media-descriptions" and
>> "trickle-ice-attribute-fields"
>>
>> Excerpt from Adam'S IESG review:
>>
>> §9.2:
>>
>> The syntax for "session-level-fields", "pseudo-media-descriptions", and
>> "trickle-ice-attribute-fields" include extremely strict rules around
>> ordering of
>> fields (e.g., including ice-ufrag before ice-pwd would be syntactically
>> invalid). That level of strictness seems unlikely to lead to interoperable
>> implementations.
>>
>> If the intention is to be rigid in this fashion, please add prominent
>> prose
>> that warns implementors that fields MUST appear in the order specified,
>> and
>> that all other orders are invalid and MUST be rejected.
>>
>> If that's *not* your intention (and I suspect it isn't), then please fix
>> the
>> syntax definition to allow for arbitrary ordering of attributes in the
>> same way
>> as SDP does. For example:
>>
>>       session-level-fields = *(session-level-field CRLF)
>>
>>       session-level-field = bundle-group-attribute /
>>                             ice-lite-attribute /
>>                             ice-pwd-attribute /
>>                             ice-ufrag-attribute /
>>                             ice-options-attribute /
>>                             ice-pacing-attribute /
>>                             end-of-candidates-attribute /
>>                             extension-attribute-fields
>>                                    ; for future extensions
>>
>>
>> Regards
>>
>> Thomas
>>