SER CVS head, new select identifiers info - was - Re: [Serusers] Textops with AVPs?

[sip]

Greger,

Sounds incredibly handy. Is this available only in SER head or is it something
that's been around for a little while (i.e. do I have any hope of using it in
ser 0.9.6) ? 


N. 


On Tue, 11 Jul 2006 21:18:38 +0200, Greger V. Teigre wrote
> I repost Jan's original description of the "select identifier"
functionality. Since then, more select identifiers have been added, both from
core and modules.
g-)

SER core can parse select identifiers using the configuration parser.
 A select identifiers begins with @ characters and contains several
 components/tokens delimited by . (unless it is integer component).
 Integer components are enclosed in [], for example:

@contact[1].uri

This identifier is converted into binary structure which contains the
 array of components. After that the parser tries to lookup function
 that matches the identifier.

Available functions are arranged in a tree-like structure. When
 looking up a function the tree is traversed (starting at the root)
 until the parser finds corresponding function. The part of the tree
 containing TLS functions looks like:

"tls"-+-"peer"-+-"subj"-+-"name" (select_peer_name())
 | \
 | "state" (select_peer_state())
 |
 +-"issuer"-+-"name" (select_peer_issuer_name())
 \
 "state" (select_peer_issuer_state())

Thus when you write @tls.peer.subj.state in the configuration file
 then the parser will traverse the tree until it reaches
 select_peer_state() function and then it would remember that this
 function should be called.

The tree of identifiers and functions is built dynamically at runtime.
 This is a nice feature becase this way modules can register their own
 functions or whole subtrees and make their functions available in the
 configuration file.

Thus if you load TLS module then all @tls.* selects become avaiable,
 if you do not load the module they are not available. Only a couple of
 core functions and the framework is built in the core, the rest can be
 in modules.

This framework is currently used in tls and xmlrpc modules. XMLRPC
 module exports the name of the XML-RPC method to the script. TLS
 module exports information from TLS layer.

The SER core itself contains a couple of functions that can retrieve
 various parts of a SIP message:

@from, @from.uri, @to, @to.uri, @from.tag, @from.name, @to.tag.
 @to.name, @from.params, @to.params, @contact, @contact.uri,
 @contact.params, @contact.expires, @contact.q, @via, and so on.

TLS related functions are described in a separate email.
> 
> sip wrote: Sounds like something I might look more into. Thanks, Greger. Is
there
anything written more about @var constructs? I checked the admin guide (I
know... that was kind of silly considering how out of date it is ;) ), and
tried to do a search in Google (it seems to ignore the @, so @var just gives
me every message with the word 'var' in it) and didn't see anything. Is there
anything over at OnSIP discussing it? 

N.

On Tue, 11 Jul 2006 08:35:11 +0200, Greger V. Teigre wrote
   If this functionality was added in later openser versions than 0.9,
 it will most likely not be in SER. What you are describing is hard 
to do with the avpops version in 0.9. The avpops module was generic 
enough to do more than it was designed for; making some code 
operations quite dirty in 0.9 (using the ruri as a temporary storage 
while manipulating a variable). SER head uses @var to more directly 
access data instead of going through a module. You may want to have 
a look at it! g-)

sip wrote:
   Is there a version of textops that can do substs with AVPs that will work on
SER 0.9.6 or is that an openSER-only modification of the code? 

I'm curious because we're ALSO running into the issues of charging the
call-forwarding user for forwarding a call to the PSTN instead of charging the
calling party. Ideally, I'd like to rewrite the from address solely for the
purpose of authenticating the user who's doing the forwarding and charging him
for the call, but that would likely break things as there'd be no way to get
back to the original user if I just rewrote the from username. 

SO, I thought, why not let the b2bua handle the details and just forward a uri
with a prefix string that includes the user who's forwarding the call (the
original RURI instead of just the rewritten one). 

And there's the trick. How do I craft a RURI out of bits and pieces of things
into one long RURI? 

If it were all the same number, I could use prefix, but it's dynamic (as is
the nature of most things), so prefix won't work.

How do I take

RURI=1105

And add to it:

The rewritten RURI from the call forwarding info: 18005551212

AND the prefix for the b2bua auth: 9999

To make:

new ruri: 9999110518005551212

N.
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