[sr-dev] about contact params

[Juha Heinanen]

Iñaki Baz Castillo writes:

> RURI is a addr-spec, so any param in the RURI is, of course, a URI param.
> But in case a From/Contact/To header contains a addr-spec then a param
> is ALWAYS a header param.

where is that stated in rfc3261?  it is not enough to me that you assure
so.  my counter argument could be that if there are no <>s, then every
param is uri param and that viewpoint is fully supported by the syntax.

> One more argument:
> 
>   contact-param  = (name-addr / addr-spec) *(SEMI contact-params)
> 
> Imagine you use addr-spec, you want a URI param ";uri-param=1234" and
> a header param ";header-param=9999". How would it look?:
> 
>   Contact: sip:alice at dom.org;uri-param=1234;header-param=9999

i can claim that you cannot use addr-spec if you want to use header
params, i.e., you must use <>s and haeder params will follow.

> If you were right, how to determine that ;uri-param is a URI param and
> ;header-param is a header param? There is no way!

see above.  if you want header param, you must use <> syntax.

> So the only solution is using name-addr:
> 
>   Contact: <sip:alice at dom.org;uri-param=1234>;header-param=9999

exactly, but if there are no <>s, then what?  i can justify the claim
that then all params are uri params.

> This is a complex grammar in the RFC 3261, and there have been long
> discussions about it in sip-implementors maillist, you can search for
> them if you want.

i don't want, but it is really strange that there is such a bug in the
grammar that has not been fixed by some other rfc.

> Yes, of course, but then it CANNOT contain URI params, just header
> params.

that is just your opinion that so far you have not based on any fact in
rfc3261. 

-- juha