Christer Holmberg (JO/LMF) wrote:
Hi,
* if they're out of sync, which one takes precedence (that
is, do I process a Content-Type that isn't listed in the
Content-Type-List?)
I'm with Dan on this. Also, this is well trodden ground in email, and
they haven't found a need for this.
The Content-Type contains "multipart/*", while the Content-Type-List
contains the types (app/sdp, app/isup, app/whatever etc) within that
multipart.
Please note that I am talking about SIP headers, not in the MIME bodies
(of course, if a MIME body contains another multipart/*, the header
could perhaps also be used there).
There really isn't any difference between sip headers and mime headers.
From a mime perspective the entire sip message is just a bunch of mime
headers including some that are extension headers.
* if a UA knew an intermediate box used Content-Type-List,
the UA could use Content-Type-List to make the intermediate
box think some sort of Content-Type is not present. That
additional content-type might contain the secret of the
universe, which the intermediate box really needed to know.
Well, this depends on the functionality of the middle-box.
If the middle-box is going to do some kind of policing, or otherwise
verify that the multipart actually contains what is claimed in the
Content-Type-List, it will have to parse the multipart anyway.
* looking for "^Content-Type *:" isn't too hard; you don't
really need to bother parsing MIME and looking for nested
parts unless there is, in fact, a content-type you care
about. Per Paul's message, if you only want ones with
Content-Disposition: session, you could look for that string
within 4-5 lines of Content-Type; if you found it, then you
could parse the MIME in the body.
I don't think it's that easy. Assume one MIME body contains a SIP
message (or part of a SIP message), or any other protocol which uses the
Content-Type header, which is not the Content-Type header of the MIME
body itself. The same goes for Content-Disposition.
IMO the servers that care about what is in the bodies should just bite
the bullet and do the necessary parsing. Frankly, middle boxes shouldn't
be looking at bodies anyway.
Paul
Regards,
Christer
-----Original Message-----
From: Christer Holmberg (JO/LMF)
[mailto:[EMAIL PROTECTED]
Sent: Thursday, May 10, 2007 6:44 PM
To: Paul Kyzivat; Dan Wing
Cc: [EMAIL PROTECTED]; [email protected]
Subject: RE: [Sip] Support for Multipart/MIME
Hi,
The following is not a proposal, but more "brain storming".
Would it be helpful to have a SIP header, e.g.
Content-Type-List, which
would list the different Content-Types in a multipart/* body.
A node could then first check that header in order to see
whether the
multipart/* contains something a specific node is interested in -
without having to parse the full multipart/* body first. It could
speed up the processing in nodes which may have interest only in a
small set of Content-Types.
Comments?
Regards,
Christer
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