[Users] The usrloc table, Oracle, and Asterisk

[Bogdan-Andrei Iancu]

Hi Jerome,

you are right - a server may change the expire advertised by the client. 
If it is the case or not, it's a matter of configuration in OpenSER - 
see the min_expires and max_expires in the registrar module.
    http://www.openser.org/docs/modules/1.2.x/registrar.html

if this params are not set, there is no risk of using the value 
advertised by the client.

regards,
bogdan

Jerome Martin wrote:

>On Thu, 2006-12-14 at 17:32 -0200, Juan Carlos Castro y Castro wrote:
>  
>
>>Forget I said that! There's $Ts + $hdr("Expires")! That'll teach me to 
>>always RTFA before answering!
>>    
>>
>
>Well, you need to be carefull about $hdr("Expires"). This is NOT the
>only way a UA can specify an expiration delay for a REGISTER request.
>
>If you take a look at the relevant parts of rfc3261
>( http://www.ietf.org/rfc/rfc3261.txt ), you'll see that using an
>Expires header is only one way of specifying a desired expired duration
>for the REGISTER. The other way is by using a Contact header parameter
>(page 60 of the rfc) :
>
>  
>
>>10.2.1.1 Setting the Expiration Interval of Contact Addresses
>>
>>   When a client sends a REGISTER request, it MAY suggest an expiration
>>   interval that indicates how long the client would like the
>>   registration to be valid.  (As described in Section 10.3, the
>>   registrar selects the actual time interval based on its local
>>   policy.)
>>
>>   There are two ways in which a client can suggest an expiration
>>   interval for a binding: through an Expires header field or an
>>   "expires" Contact header parameter.  The latter allows expiration
>>   intervals to be suggested on a per-binding basis when more than one
>>   binding is given in a single REGISTER request, whereas the former
>>   suggests an expiration interval for all Contact header field values
>>   that do not contain the "expires" parameter.
>>    
>>
>
>Also note that the expire parameter to a Contact header is totally 
>case-unsensitive ( page 32 of the RFC) :
>
>
>  
>
>>   When comparing header fields, field names are always case-
>>   insensitive.  Unless otherwise stated in the definition of a
>>   particular header field, field values, parameter names, and parameter
>>   values are case-insensitive.  Tokens are always case-insensitive.
>>   Unless specified otherwise, values expressed as quoted strings are
>>   case-sensitive.  For example,
>>
>>      Contact: <sip:alice at atlanta.com>;expires=3600
>>
>>   is equivalent to
>>
>>      CONTACT: <sip:alice at atlanta.com>;ExPiReS=3600
>>    
>>
>
>A good example of a very popular SIP UA always using the Contact header 
>parameter method is the Linksys PAP2 ATA. On the other hand, there are also
>many popular ATAs that use the Expires header method, i.e. Audiocodes 
>MP1XX ATAs. So unless you're in a very controlled environment and you don't
>care at all to be generic and RFC3261-compliant, you must support both. But
>be carefull, in my experience this almost always bites you back one day or 
>the other.
>
>Hope this helps,
>Best Regards,
>
>Jérôme Martin
>
>
>
>
>
>  
>