[asterisk-dev] [Code Review] Prevent 'Bad Magic Number' caused when a channel is optimized out by masquerade

[Alec Davis]

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This is an automatically generated e-mail. To reply, visit:
https://reviewboard.asterisk.org/r/928/
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(Updated 2010-09-18 05:45:40.035028)


Review request for Asterisk Developers.


Changes
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After comments from Stefan Schmidt on devlist.

In ast_do_masquerade:

  undid my initial defferal of unlocking the channels container, it's now in it's original place.

  Now, don't unlock the original and clonechan channel before they are linked back into the channels container, as they may disappear.
  There was a comment already there, suggesting that it could!

  When they do dissappear, we have a 'Bad Magic Number' senario setup. 


Summary
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there are 2 main fixes here.

1). Prevent a further masquerade being planned if either original/clonechan(masq/masqr) are set.
2). While the actual masquerade happens keep the channels container locked for the full duration. 

There is a comment 'that the channels container can be freed' after both channels are locked and unlink, but that not the case.


This addresses bugs 16057, 17037, 17363, and 17801.
    https://issues.asterisk.org/view.php?id=16057
    https://issues.asterisk.org/view.php?id=17037
    https://issues.asterisk.org/view.php?id=17363
    https://issues.asterisk.org/view.php?id=17801


Diffs (updated)
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  trunk/main/channel.c 287464 

Diff: https://reviewboard.asterisk.org/r/928/diff


Testing
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Using the following test plan, calling 10020 creates 20 looped Local channel calls, that then get optimized out.

[test]
exten => 10000,1,Answer()
exten => 10000,n,Playback(test-tones-follow)
exten => 10000,n,Milliwatt()

exten => _1XXXX,1,Set(i=${MATH(${EXTEN}-1,int)})
exten => _1XXXX,n,Dial(Local/${i}@test)

After patch: normal expected channels.
    asterix*CLI> core show channels
    Channel              Location             State   Application(Data)
    DAHDI/35-1           10010 at phones:2       Up      Dial(Local/10009 at phones)
    Local/10000 at phones-2 s at echo-test:4        Up      Echo()
    Local/10000 at phones-2 (None)               Up      AppDial((Outgoing Line))
    3 active channels
    2 active calls
    97 calls processed
    asterix*CLI>


prior to the patch:
   'Bad Magic Number' would reqularly been seen.

   dead channels left in container
   asterix*CLI> core show channels
   Channel              Location             State   Application(Data)
   Local/10000 at phones-2 s at echo-test:3        Up      Playback(echo-test)
   Local/10000 at phones-2 (None)               Up      AppDial((Outgoing Line))
   2 active channels
   1 active call
   21 calls processed
   asterix*CLI>


Thanks,

Alec