[asterisk-bugs] [JIRA] (ASTERISK-27759) res_pjsip_pubsub: Subscription persistence does not preserve XML <dialog-info> version number

[Bryan Nelson (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-27759?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=245014#comment-245014 ] 

Bryan Nelson commented on ASTERISK-27759:
-----------------------------------------

@ADTopkek

I definitely wouldn't go so far as to say this makes asterisk incompatible with modern SIP phones.  This problem only occurs when asterisk is restarted and the subscriptions are restored from the astdb, not when a phone restarts.  If you are having issues with BLF when a phone restarts, I suspect you are having a different problem.  I can't think of any reason to need an asterisk restart when updating firmware for phones...?

We have been running for a while with the sorcery config for persistence set to memory, rather than astdb storage to "disable" the persistence, which basically brings functionality back to the pre-pjsip days.
{quote}
[res_pjsip_pubsub]
subscription_persistence=memory
{quote}

(If anyone knows a more correct way to simply disable the persistence completely, I'd appreciate the help)

When asterisk restarts, all subscriptions are lost, and phones need to re-subscribe.  Setting a relatively low subscription interval helps restore things pretty quickly.  Since asterisk restarts "should" be a rare occurrence, and generally during off-hours, the BLF subscriptions are restored long before anyone is back in the office to use them.



> res_pjsip_pubsub: Subscription persistence does not preserve XML <dialog-info> version number
> ---------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-27759
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27759
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_pjsip_pubsub
>    Affects Versions: 15.3.0
>         Environment: CentOS Linux release 7.4.1708 (Core)
>            Reporter: Bryan Nelson
>            Severity: Minor
>              Labels: pjsip
>
> When utilizing the subscription persistence via astDB to restore dialog-info+xml subscriptions on restart of asterisk, the re-built subscriptions do not have the correct 'version' number in the xml content, and the message is discarded by phones per the RFC.  I am unable to find anywhere that the current xml version number is stored in the persistence table, so it makes sense that it cannot be restored on restart. 
> Desired behavior would be similar to how the SIP Cseq is stored, and used when restoring the subscription.
> Example:
> Prior to restart, version number has reached 6
> {quote}
> <?xml version="1.0" encoding="UTF-8"?>
> <dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" *version="6"* state="full" entity="sip:701 at 1.1.1.1:5060">
>  <dialog id="701">
>   <state>terminated</state>
>  </dialog>
> </dialog-info>
> {quote}
> After restart, subscription is restored, but version number starts at 1:
> {quote}
> <?xml version="1.0" encoding="UTF-8"?>
> <dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" *version="1"* state="full" entity="sip:701 at 1.1.1.1:5060">
>  <dialog id="701">
>   <state>confirmed</state>
>  </dialog>
> </dialog-info>
> {quote}
> In this particular case, the version number would 'catch up' to the phones with 5 more state changes, and the BLF would resume functioning on the phone.  In cases where there is a very long running subscription with many state changes, this version number can be in the hundreds, so the delay before if begins functioning again is quite long.



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