Re: [Ecrit] I-D Action: draft-ietf-ecrit-car-crash-10.txt

[Randall Gellens <[e-mail]>]

At 3:08 PM -0400 9/22/16, Paul Kyzivat wrote:

>  Randall,
>
>  (Including ecrit)
>
>  On 9/22/16 12:26 PM, Randall Gellens wrote:
>>  Hi Paul,
>>
>>  Thanks very much for the quick review and comments.  I'm making other
>>  changes requested by Christer, and I want to fix the ones you found as
>>  well.
>>
>>  Section 12 is the Security Considerations.
>
>  In the -10 version I am looking at section 12 is Examples.

Sorry, I missed that you were replying to -10; I'd incorrectly 
assumed you were replying to -12.

>
>>  Did you mean Section 11, the
>>  Examples?  Or maybe Figure 10 (one of the examples)?   More to the point
>>  on correct C-D, there's text in Section 6 that says:
>>
>>     If the body part
>>     containing the MSD or metadata/control block is the only body part,
>>     it has a Content-Disposition header field value of "Info-Package;
>>     handling=optional".  If it is contained within a multipart body part,
>>     it has a Content-Disposition header field value of "By-Reference;
>>     handling=optional".
>>
>>  So this is wrong?  What should it say?
>
>  That text seems ok, at least for this case.
>
>  IIUC it isn't discussing the C-D *on* the multipart/mixed 
> container. It is discussing parts *within* the multipart. Those 
> seem to be correctly tagged.
>
>  The "Info-Package" C-D is only applicable for an INFO message. 
> Since this isn't an INFO message it makes no sense to use it.

That was fixed in -12.

I'm about to upload -13, which fixes the C-D issues.  I also added 
text to clarify that "handling=optional" is only used in the initial 
INVITE, to protect the INVITE from being rejected if it is processed 
by a legacy element (such as a gateway between SIP and CS) that does 
not understand an MSD.  I fixed the examples to comply.

>
>  The authoritative document on this stuff is RFC5621.  However it is 
> silent on what C-D used be used for multipart containers. So it is 
> necessary to read between the lines to figure that out.
>
>  1) Consider an ordinary INFO message. It will have a body with C-D 
> of "Info-Package", indicating that it is to be processed as the 
> package for this INFO.
>
>  2) Next, add a header that needs to reference a body part, such as 
> geolocation. Now we have two body parts, and need a multipart 
> wrapper to contain them. One body part has C-D of "Info-Package" 
> for the INFO, and the other has C-D of "by-reference" because it is 
> referenced by the geolocation header. The multipart that wraps them 
> needs *some* C-D. IMO it shouldn't be Info-Package because that 
> would imply that the whole thing is to be used by the INFO message. 
> It shouldn't be "by-reference" because it isn't referenced by 
> anything. It is really processed in a special way, and we have no 
> special C-D value to signify this. If omitted it will default to 
> C-D:render,handling=required. Having it be required is appropriate 
> in this case, since the handling of the info package is also 
> required. The "render" value seems as good as any, since the 
> contained parts have their own dispositions and "rendering" a 
> multipart independent of its contents also seems to have no meaning.
>
>  3) A similar situation to (2) holds for INVITE. In this case of an 
> SDP, the default C-D is "session".
>
>  4) For some message that doesn't require a body part for its own 
> processing (e.g., UPDATE) and a single header with a CID reference. 
> Then there will be no multipart - just the referenced part. It will 
> still have a C-D of by-reference.
>
>  5) A message with no body part of its own, but multiple CID 
> references from headers to body parts, will need a multipart body 
> containing the referenced body parts. It will be much like (2) but 
> without the Info-Package part.
>
>>  Section 10 (the INFO package registration) says:
>>
>>     If the body part is the only body
>>     part, it has a Content-Disposition header field value of "INFO-
>>     Package; handling=optional".  If the body part is contained within a
>>     multipart body part, it has a Content-Disposition header field value
>>     of "By-Reference; handling=optional" (the top-level multipart body
>>     part has "INFO-Package" in its Content-Disposition value).
>>
>>  So this is also wrong, especially the parenthetical statement that the
>>  top-level has a C-D of INFO-Package?  What should it say?
>
>  Hopefully the above is sufficient.
>
>>  Also, when you say "let it default to render" you mean just omit the C-D
>>  header field?
>
>  Yes. But that must be done with care, since it implies 
> handling=required. If processing of the headers with references 
> isn't required then that ought to be changed to handling=optional.
>
>  	Thanks,
>  	Paul


-- 
Randall Gellens
Opinions are personal;    facts are suspect;    I speak for myself only
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