[asterisk-dev] [Code Review] 4158: rtp_engine: Fix crash when endpoints send more RTCP report info blocks then we can handle

[Matt Jordan]

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(Updated Nov. 12, 2014, 5:59 p.m.)


Status
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This change has been marked as submitted.


Review request for Asterisk Developers.


Changes
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Committed in revision 427762


Bugs: ASTERISK-24489 and ASTERISK-24498
    https://issues.asterisk.org/jira/browse/ASTERISK-24489
    https://issues.asterisk.org/jira/browse/ASTERISK-24498


Repository: Asterisk


Description
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Asterisk - in res_rtp_asterisk - only understands a single RTCP report info block. When the RTCP information was refactored in the RTP Engine to be pushed over the Stasis message bus, I put in the hooks into the engine to handle multiple RTCP report info blocks, in the hope that a future RTP implementation would be able to provide that data. Unfortunately, res_rtp_asterisk has a tendency to "lie":
(1) It will send RTCP reports with a reception_report_count greater than 1 (which is pulled directly from the RTCP packet itself, so that part is correct)
(2) It will only provide a single report block

When the rtp_engine goes to convert this to a JSON blob, hilarity ensues as it looks for a report block that doesn't exist.

This patch updates the rtp_engine to be a bit more skeptical about what it is presented with. While this could also be fixed in res_rtp_asterisk, I prefer to fix it in the engine for two reasons:
(1) The engine is designed to work with multiple RTP implementation, and hence having it be more robust is a good thing (tm)
(2) res_rtp_asterisk's handling of RTCP information is "fun". It should report the correct reception_report_count; ideally it should also be giving us all of the blocks - but it is *definitely* not designed to do that. Going down that road is a non-trivial effort.


Diffs
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  /branches/12/main/rtp_engine.c 427539 

Diff: https://reviewboard.asterisk.org/r/4158/diff/


Testing
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Issue reporter tested and verified that they no longer crash.


Thanks,

Matt Jordan

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