> -----Original Message-----
> From: Shail Bhatnagar [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, February 27, 2001 9:04 AM
> To: Jonathan Rosenberg
> Cc: '[EMAIL PROTECTED]'; [EMAIL PROTECTED]
> Subject: Re: [Sip-implementors] the meaning of "copy"
>
>
> > >
> > > It seems to me that byte-by-byte is more robust and easier to
> > > compare in
> > > terms of "From" and "To" headers. What are the potential
> reasons that
> > > somebody wants to modify these two headers in addition to the
> > > "Tag" param?
> >
> > The problem has to do with storing whitespace on other
> formatting > >characters
> > when parsing. I'd like to be able to parse a header,
> discard any LWS, and
> > reconstruct the header. This should be "equivalent" based
> on concrete
>
> I thought URLs cannot have whitespace, so I am not convinced
> about a proxy/ua messing around with From/To except appending
> a tag.
There is LWS in the To/From header in several places:
From: me <sip:u@h>;tag=2
From: me < sip:u@h>; tag=2
From: me < sip:u@h > ; tag=2
are all equivalent. They would not match under bytewise comparison of
To/From.
> While we are here, I posted some questions several times on
> the sip-implementors about transaction identification, but
> nobody responded.
> If To header tag is included in the hash computation, then
> ACK for a INVITE will identify a transaction different from
> the original INVITE. This is acceptable for an ACK for a 200,
> but not for non-200 ACK ( proxy has to stop response retx timer).
> If To header tag is not included then 2 different PRACKs will
> hash to the same transaction.
There are several ways to handle this in an implementation. Its a question
of being creative with hash table structures.
-Jonathan R.
---
Jonathan D. Rosenberg 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.cs.columbia.edu/~jdrosen PHONE: (973) 952-5000
http://www.dynamicsoft.com
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