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Summary:ASTERISK-19461: ChanSpy - Improper refcounts avoid channel release
Reporter:Irontec (irontec)Labels:
Date Opened:2012-03-02 03:46:43.000-0600Date Closed:2012-03-02 09:52:19.000-0600
Priority:MajorRegression?
Status:Closed/CompleteComponents:Applications/app_chanspy
Versions:SVN Frequency of
Occurrence
Related
Issues:
Environment:Attachments:( 0) app_chanspy_iteartor_next_unref.patch
Description:After testing a bit ChanSpy with SPYGROUPS (g flag) we have discovered that spy channels are not properly released.
Afaik, channels are removed from groups when their refcount reaches 0.

After enabling REF_DEBUG we found that this was not happening:
{noformat}
[...]
0x3038238 -1   cli.c:1504:handle_showchan () [@66]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@65]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@66]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@67]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@68]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@69]
0x3038238 +1   channel.c:1627:ast_channel_iterator_next () [@70]
0x3038238 -1   cli.c:896:handle_chanlist () [@71]
[...]
{noformat}

It seems ast_channel_iterator_next returns the next channel in the iterator with a ref, avoiding the channel to be destroyed before we have finished with it, so we have to unref it before the next interation. After digging a bit, we found that next_channel function may be bugged, and is some cases it doesn't unref the channel before the next iteration.

===========================================================================

{code}
redo:
       if (!(next = ast_channel_iterator_next(iter))) {
               return NULL;
       }

       if (!strncmp(ast_channel_name(next), "DAHDI/pseudo", pseudo_len)) {
               goto redo;
       } else if (next == chan) {
               goto redo;

       }

       autochan_store = ast_autochan_setup(next);
       ast_channel_unref(next);
{code}

===========================================================================


I'm not an expert but I've attached a patch, if you find a better solution feel free to implement it :)
Comments:By: Irontec (irontec) 2012-03-02 03:47:57.809-0600

Unrefs the channel before next iteration.
By: Irontec (irontec) 2012-03-02 03:51:37.043-0600

This may fix some other issues like @ASTERISK-17515