[asterisk-bugs] [JIRA] (ASTERISK-26432) chan_dahdi: hangup during long TDD sendtext not detected, blocking channel

[Richard Mudgett (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-26432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=232510#comment-232510 ] 

Richard Mudgett commented on ASTERISK-26432:
--------------------------------------------

The {{chan_dahdi.c:dahdi_sendtext()}} has a simplistic polling loop that doesn't process received frames.  Thus the queued AST_CONTROL_HANGUP frame from PRI does not get processed.

> chan_dahdi: hangup during long TDD sendtext not detected, blocking channel
> --------------------------------------------------------------------------
>
>                 Key: ASTERISK-26432
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26432
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_dahdi
>    Affects Versions: 13.11.1
>         Environment: CentOS 6.5
> libpri 1.5.0
> Dahdi 2.11.1
> Asterisk 13.11.2
> wanpipe 7.0.19
> 8 DMS100 PRIs on Sangoma A108DE cards
>            Reporter: Nicolas Chapleau
>
> (peusdo) 
> answer()
> setTDD ( on )
> sendText( "Put a long message to play back on the customers TTY device" )
> When a hangup occurs during the sendtext, I can see the PRI_EVENT_HANGUP_REQ on my PRI span but it is not processed until the sendtext command completes. I have debugged the sendtext command and I see it complete tdd_generate then loop (chan_dahdi.c line 13435) to write the tones while checking for hangup (line 13436), which is NOT detected. 
> Meanwhile, new calls coming into that span get rejected until the sendtext completes, after which I get PRI MDL (f) errors. On busy systems, it will also cause Exceptionally long frame queuing error messages.
> I can easily recreate this by hanging up during the sendtext command and calling back right away. 
> This issue has blocked us from upgrading from 1.4.43 where it does not happen. For now I put a temporary fix in our script to send TDD text one letter at a time which helps but not having sendtext block the span on hangup.



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