Hi Florian,
I think the intent of RFC3261 should have been to allow optional
whitespace at the end of a quoted-string:
Currently in RFC 3261:
quoted-string = SWS DQUOTE *(qdtext / quoted-pair ) DQUOTE
Probably should have been in RFC 3261:
quoted-string = LDQUOT *(qdtext / quoted-pair ) RDQUOT
However, that is water under the bridge, so I have no objection
changing the c-p-instance production to look like this:
c-p-instance = "+sip.instance" EQUAL DQUOTE "<" instance-val ">" DQUOTE
If you are responsible for an implementation however, I urge you to be
generous in what you receive in this regard. Please ignore extraneous
whitespace unless the spec gives it some special semantic meaning (ex:
inside a quoted string).
thanks,
-rohan
On Apr 13, 2009, at 1:50 PM, Florian Zumbiehl wrote:
Hi,
in case you've read my bug report concerning draft-ietf-sip-gruu-15
from this morning, the short version: draft-ietf-sip-outbound-16 is
affected by the same problem.
The complete version:
draft-ietf-sip-outbound-16 contains (amongst others) these ABNF rules:
| contact-params =/ c-p-reg / c-p-instance
| c-p-instance = "+sip.instance" EQUAL
| LDQUOT "<" instance-val ">" RDQUOT
which, when adding them to the grammar from RFC 3261, would produce
from <Contact> a language that's a superset of the language that would
be produced by <Contact> from RFC 3261-only.
In particular, the language produced by <foo> is a subset of the
"outbound extended" language, but not of the RFC 3261-only one:
| foo = "m: <sip:[email protected]>;+sip.instance=" DQUOTE "x" DQUOTE SP CRLF
To put it in more practical terms: the <RDQUOT> in <c-p-instance>
allows for trailing <LWS>, which <contact-extension> does not,
so an implementation conforming to draft-ietf-sip-outbound-16 could
produce a Contact header that potentially could not be parsable
(except as an <extension-header>) by an implementation conforming
to RFC 3261.
Thus, I would suggest to replace the rules quoted above by:
| contact-params =/ c-p-reg / c-p-instance
| c-p-instance = "+sip.instance" EQUAL
| LDQUOT "<" instance-val ">" DQUOTE
This produces the same language, maybe it's a more consistent
replacement:
| contact-params =/ c-p-reg / c-p-instance
| c-p-instance = "+sip.instance" EQUAL
| DQUOTE "<" instance-val ">" DQUOTE
Florian
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