Subject: RE: [Sip] Comments on history-info

From: "Mary Barnes" <[email-masked]>
Date: Sun, 15 Feb 2004 14:18:12 -0600

Eric,

Although Rohan responded to your "Big question:" part of this email:
http://www1.ietf.org/mail-archive/working-groups/sip/current/msg08998.html
it doesn't appear that I ever responded to the remaining points on the list.
Thank you for reviewing the draft and providing detailed comments.   In
updating the draft, I considered your comments as indicated below [MB].

Regards,
Mary. 

-----Original Message-----
From: Eric Burger [mailto:[email-masked]]
Sent: Thursday, November 06, 2003 3:44 AM
To: SIP List (E-mail)
Subject: [Sip] Comments on history-info

Big question:
Why don't we use multiple History-Info headers, instead of a (potentially
VERY long) single header?

I would argue for multiple headers on two grounds.

First, the idea of a proxy modifying history information doesn't sound
smart.  If it screws up, it is hard to figure out who screwed up.

Second, the index parameter frees us from worrying about header order, which
is a VERY good thing.

Overview:
While the motivation for History-Info is for the initiator of a request to
know what happened to a request, it is also of great use to the recipient
(End of Section 2 overview paragraph).

[MB]: I've clarified this. 

Section 1.2:
How is History-Info any different than Via w.r.t. security?

[MB]: It's quite similar actually, so I've added a statement to that effect
in this section.  I think the only difference being the dependency on the
Index written by the previous hop to generate the index for the current hop.
I do think the general M2M and M2E security solution would also be
applicable to Via if TLS were not deemed to be sufficient (i.e if there were
some reason why you would not want some intermediaries to be able to see the
Via added by an "untrusted" intermediary).  

Nits:
Section 2.5, first paragraph, last sentence:
this would like be a local
this would likely be a local
               ^^
[MB]: Fixed. 

Appendix B, message F8, extra space before last angle-bracket in the
History-Info line.

[MB]: Fixed.

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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: "Eric Burger" <[email-masked]>
Date: Sun, 15 Feb 2004 17:59:59 -0500

Excellent.

Thinking about it a bit more, is there any reason to ALLOW stuffing multiple history info info's on a single line?  The idea going back to SMTP was that you are only allowed to add history, not change it.  Putting multiple history info's in a single history-info header, by definition, changes history.

> From: Mary Barnes [mailto:[email-masked]]
> Sent: Sunday, February 15, 2004 3:18 PM
> To: Eric Burger; SIP List (E-mail)
> Subject: RE: [Sip] Comments on history-info
> 
> 
> Eric,
>

---

From: "Mary Barnes" <[email-masked]>
Date: Mon, 16 Feb 2004 08:57:50 -0600

Eric,

History-Info is a  bit different than the SMTP (at least as best as I
understand SMTP not being an expert in that area), since the retargeting in
SIP is more complicated that SMTP due to forking, etc.  In order to be able
to accurately reflecting the forking, we've added the index.  The index is
used to generate subsequent History-Info entries.  In addition, there's the
Reason that gets added to the targeted-to URIs to reflect the reason for the
retargeting. So, yes History-Info does change History in the sense that we
embellish the Request-URIs that are "visited" with additional information
that seems to be useful to a variety of end applications.  So, I think what
you're proposing would only provide a subset of the functionality that we're
after.

Mary. 

-----Original Message-----
From: Eric Burger [mailto:[email-masked]]
Sent: Sunday, February 15, 2004 5:00 PM
To: Barnes, Mary [NGC:B622:EXCH]; SIP List (E-mail)
Subject: RE: [Sip] Comments on history-info

Excellent.

Thinking about it a bit more, is there any reason to ALLOW stuffing multiple
history info info's on a single line?  The idea going back to SMTP was that
you are only allowed to add history, not change it.  Putting multiple
history info's in a single history-info header, by definition, changes
history.

---

From: "Eric Burger" <[email-masked]>
Date: Mon, 16 Feb 2004 18:49:59 -0500

I'm not changing any of the functionality.  As Rohan says, it is already in the spec.  I'm suggesting we do not allow a proxy to *modify* an existing history-info header.  A proxy can (and should) *insert* new history-info headers.  It is because we have the index tag that the modification restriction should not be a problem.

> Sent: Monday, February 16, 2004 9:58 AM