[asterisk-bugs] [JIRA] (ASTERISK-20638) SIP dialog matching is incorrect when multiple provisional responses are received with pedantic SIP checking

[Eelco Brolman (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-20638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=200016#comment-200016 ] 

Eelco Brolman commented on ASTERISK-20638:
------------------------------------------

Ah, ok :), I get it ;). It is ofcourse better when asterisk collects all the 180 Responses in an array, it looks up the match. If that's the case in Asterisk 10 and up, then no patch is required. I have unfortunately no asterisk 10 in my lab. Maybe in the next couple of weeks...

Will this patch be applied against the 1.8 series?
                
> SIP dialog matching is incorrect when multiple provisional responses are received with pedantic SIP checking
> ------------------------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-20638
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-20638
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/Interoperability
>    Affects Versions: 1.8.17.0
>            Reporter: Eelco Brolman
>            Assignee: Eelco Brolman
>         Attachments: pedantic-call-pickup-from-tag.patch
>
>
> When an external call pickup (INVITE with Replaces: header) is sent to asterisk, asterisk tries to find the call ({{get_sip_pvt_byid_locked}}) based on the {{callid}}, {{fromtag}} and {{totag}} in pedantic mode.
> The match will fail in certain situations since the fromtag is not definite (final) as long as only Provisional responses have been received.
> When asterisk dials a SIP proxy which does ring group dialing for instance, multiple {{180 Ringing}} responses will be received, and the dialog within asterisk cannot be matched against a single fromtag.
> So as long as only provisional responses are received (i.e. when flag {{SIP_PAGE2_DIALOG_ESTABLISHED}} is not set), asterisk should not reject the match based on the fromtag.
> The patch for this specific situation is easy of course, you need to test if the dialog is established when checking the fromtag:
> {code}
> if ((frommismatch && ast_test_flag(&sip_pvt_ptr->flags[1], SIP_PAGE2_DIALOG_ESTABLISHED)) || tomismatch) {
> {code}
> but I don't know if this breaks other checks.

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