[asterisk-bugs] [JIRA] (ASTERISK-28452) pjsip: <sess-version> of SDP is not incremented though SDP may be changed on reinvite without SDP offer

[Holger Hans Peter Freyther (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=252856#comment-252856 ] 

Holger Hans Peter Freyther commented on ASTERISK-28452:
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I dived a bit into pjmedia and some of the glue to asterisk. The first find is this https://github.com/pjsip/pjproject/blob/fe963266b13d708a56c654ac5690de5f9253daeb/pjmedia/src/pjmedia/sdp_neg.c#L411 place to increase the version when the local media changes.

pjmedia_sdp_neg_modify_local_offer does not appear to be called in asterisk at all and probably does not need to be. But it means we need to increase the version when we modify the pjmedia (e.g. add or remove content). I have seen a couple of places that this can happen. E.g. when we overwrite IPs for multi-homing, topology changes in the bridge.

> pjsip: <sess-version> of SDP is not incremented though SDP may be changed on reinvite without SDP offer
> -------------------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-28452
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-28452
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: pjproject/pjsip, Resources/res_pjsip_sdp_rtp
>    Affects Versions: 16.3.0
>         Environment: CentOS 7
>            Reporter: Michael Maier
>            Severity: Minor
>              Labels: patch, pjsip
>         Attachments: sdp-version.patch, sdp-version-v2.patch, wrong-SDP-sess-version.txt
>
>
> During late / delayed offer as part of a reInivte during an outbound call, the SDP sent to the provider in the 200 OK is changed compared to the initial INVITE - but the <sess-version> isn't incremented. This is against RFC6337, 5.2.5. Subsequent Offers and Answers.
> See the attached Trace!



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