[asterisk-bugs] [JIRA] (ASTERISK-29704) res_pjsip_pubsub: Treats SUBSCRIBE with Expires 0 as invalid when it is valid

[Niksa Baldun (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-29704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=256704#comment-256704 ] 

Niksa Baldun commented on ASTERISK-29704:
-----------------------------------------

Yes, partial SIP implementation. Anyway, I was running the service on the same machine as Asterisk, and Asterisk wouldn't send a NOTIFY in that case. Why, I couldn't begin to guess. That's what caused "Unhandled by dialog usages" - Asterisk thought it sent a NOTIFY and didn't receive a response. When I tried subscribing from another host, everything was fine.

So, the only problem is Expires=0 in a new dialog. Obviously, a very minor issue.

> res_pjsip_pubsub: Treats SUBSCRIBE with Expires 0 as invalid when it is valid
> -----------------------------------------------------------------------------
>
>                 Key: ASTERISK-29704
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-29704
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_pjsip_pubsub
>    Affects Versions: 18.7.1
>         Environment: Debian Linux 10
>            Reporter: Niksa Baldun
>
> When res_pjsip receives SUBSCRIBE request with Expires=0, it responds with with 400 Bad request. Excerpt from res_pjsip_pubsub.c:
> {code}
>         if (expires_header->ivalue == 0) { 
>             ast_debug(1, "Subscription request from endpoint %s rejected. Expiration of 0 is invalid\n",
>                 ast_sorcery_object_get_id(endpoint));
>             pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 400, NULL, NULL, NULL);
>                 return PJ_TRUE;
>         }
> {code}
> However, Expires of 0 is perfectly valid. Relevant text from RFC 3265, section 3.1.1:
> {quote}
>    A natural consequence of this scheme is that a SUBSCRIBE with an
>    "Expires" of 0 constitutes a request to unsubscribe from an event.
>       In addition to being a request to unsubscribe, a SUBSCRIBE message
>       with "Expires" of 0 also causes a fetch of state; see section
>       3.3.6.
> {quote}
> Therefore, a SUBSCRIBE with Expires=0 should cause one NOTIFY to be sent, and remove the subscription if it exists.



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