Discussion about the compliance of some particular vendor to this is
probably pointless. The draft was never a standard. It existed as a
personal draft for a long time, and finally was moved directly from that
to Historic status, without ever having been a standards track RFC. The
move to Historic was simply to provide some reference for the
proprietary implementations of it.
Given this status, your only practical recourse is to implement whatever
you must to interop with whatever you want to interop with, or else take
the argument to the implementer you have trouble with.
Thanks,
Paul
On 4/4/12 3:36 AM, Brandon W. Yuille wrote:
> Hi Peter,
>
> One followup that may change everything I said about Broadsoft being
> wrong: rfc 6044.
>
> Looks like this informational rfc addressed the odd syntax you found in
> rfc 5806:
>
> 3.2. Diversion Header Syntax
>
> The following text is restating the exact syntax that the production
> rules in [RFC5806<http://tools.ietf.org/html/rfc5806>] define, but using
> [RFC5234<http://tools.ietf.org/html/rfc5234>] ABNF:
>
> Diversion = "Diversion" HCOLON diversion-params
> *(COMMA diversion-params)
>
> diversion-params = name-addr *(SEMI (diversion-reason /
> diversion-counter / diversion-limit /
> diversion-privacy / diversion-screen /
> diversion-extension))
> diversion-reason = "reason" EQUAL ("unknown" / "user-busy" /
> "no-answer" / "unavailable" / "unconditional"
> / "time-of-day" / "do-not-disturb" /
> "deflection" / "follow-me" / "out-of-service"
> / "away" / token / quoted-string)
> diversion-counter = "counter" EQUAL 1*2DIGIT
> diversion-limit = "limit" EQUAL 1*2DIGIT
> diversion-privacy = "privacy" EQUAL ("full" / "name" / "uri" /
> "off" / token / quoted-string)
> diversion-screen = "screen" EQUAL ("yes" / "no" / token /
> quoted-string)
> diversion-extension = token [EQUAL (token / quoted-string)]
>
> Note: The Diversion header could be used in the comma-separated
> format, as described below, and in a header-separated format. Both
> formats could be combined a received INVITE as recommended in
> [RFC3261<http://tools.ietf.org/html/rfc3261>].
>
> Example:
>
> Diversion:
>
> diverting_user2_addr; reason="user-busy"; counter=1; privacy=full,
> diverting_user1_addr; reason="unconditional"; counter=1; privacy=off
>
>
> So is Broadsoft correctly following the syntax in rfc 5806? No. Are they
> correctly following the current syntax in informational rfc 6044? Yes.
>
> However in my view: in order to be interoperable with devices supporting
> the earlier rfc 5806 draft using the comma separated headers should be
> discouraged. It's also odd to me that this section 3.2 claims "the
> following text is restating the EXACT syntax that the production rules
> in [RFC5806] define, but using [RFC5234] ABNF." I don't see how changing
> the syntax to allow comma separated headers could be called exact.
> Perhaps someone else who's more familiar with this rfc could shed light
> on this apparent discrepancy.
>
> Again, I hope I could help,
> Brandon
>
> On 04/04/2012 03:16 AM, Brandon W. Yuille wrote:
>> Hi Peter,
>>
>> You're correct that their implementation does not follow the syntax for
>> rfc 5806. Though I'm not really sure how much scrutiny that draft received.
>>
>> Is it a real problem? Probably not as I'd be willing to bet most
>> implementations used the same parsing routines for the Diversion header
>> as they would for any other header that contains a name-addr, which all
>> that I can think of that allow multiple header lines also allow
>> combining into one single header line separated by commas. I would think
>> a programmer was rather odd if they chose to write a new parsing routing
>> for name-addr headers that only allowed exactly 1 name-addr per header line.
>>
>> If you're just concerned with pointing out the problem to Broadsoft,
>> then yes you have a valid point as there may be an odd device out there
>> that followed the header syntax exactly. This would lead to interop
>> problems. If Broadsoft were smart about interop they'd just put each
>> Diversion name-addr on a separate line to avoid any such problem. I'd
>> imagine they were looking to save space though.
>>
>> I hope I could help,
>> Brandon
>>
>> On 04/03/2012 10:43 PM, Peter Childs wrote:
>>
>>> I notice that our BroadSoft AS platform on a multiple diverted call sends
>>> the following to a Network element, where it appears two Diversion are
>>> concatenated into a single Diversion: header as follows.
>>>
>>> Diversion:"NodePhone"<sip:[email protected];user=phone>;privacy=full;reason=unconditional;counter=1,"NodePhone"<sip:[email protected];user=phone>;privacy=full;reason=unconditional;counter=1
>>>
>>> Most examples in for example draft-levy-sip-diversion/RFC5806 where
>>> multiple diversions exist show multiple Headers, one for each diversion.
>>>
>>> I did notice that in RFC3261 7.3 Headers Fields the following
>>>
>>> <quote>
>>> That applies to SIP as well, but the specific rule is different because of
>>> the different grammars. Specifically, any SIP
>>> header whose grammar is of the form
>>>
>>> header = "header-name" HCOLON header-value *(COMMA header-value)
>>>
>>> allows for combining header fields of the same name into a comma-separated
>>> list.
>>> </quote>
>>>
>>> I note whilst RFC4244 for History-Info has (4.1)
>>>
>>> History-Info = "History-Info" HCOLON
>>> hi-entry *(COMMA hi-entry)
>>>
>>> That RFC5806 for Diversion has (4)
>>>
>>> Diversion = "Diversion" ":" 1# (name-addr *( ";" diversion_params ))
>>>
>>> My question is does BroadSoft's use of combining multiple Diversions in a
>>> single Diversion Header appear to follow RFC5806?
>>>
>>> Thanks for your consideration.
>>>
>>> Cheers,
>>> Peter
>>>
>>> --
>>> Peter Childs - Voice Engineer
>>> Internode/Agile
>>>
>>>
>>>
>>> _______________________________________________
>>> Sip-implementors mailing list
>>> [email protected]
>>> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>>>
>>>
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