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Bug #2658

osmo-mgw accepts CRCX without LocalConnectionOptions or with LCO without "a:" but fails to return media information

Added by laforge 8 months ago. Updated 28 days ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
11/18/2017
Due date:
% Done:

100%

Estimated time:

Description

If a call agent sends a CRCX without LocalConnectionOptions (which is legal), or with LCO that contain no "a:" audio codec information, osmo-mgw will accept the CRCX, but the response will lack any audio information: There's no "m=" line in the SDP specifying the port.

If the call agent doesn't specify the codec, I think the MGW gets to pick and we should pick some sane default like PCM/8000/1 in that case and respond accordingly.

History

#1 Updated by dexter about 2 months ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 10

The lack for port information is linked to the fact that the parser could not assign any codec. Since I am currently restructuring the codec handling in osmo-mgw I am on this as well. When no sdp and no LCO are included in a CRCX the MGW should pick a sane default, this makes sense.

#2 Updated by dexter about 2 months ago

  • % Done changed from 10 to 50

I have now fixed the problem, and also created a TTCN3 test to pinpoint it. I have choosen PCMU/8000/1 as default. This is payload type 0. Now it looks good. The MGW selects the default payload type and also returns the code.

#3 Updated by dexter about 2 months ago

Note: I did not push yet, but i will do this as soon as I have cleaned up some other things.

#4 Updated by dexter about 2 months ago

I have now added the test case that sends a Non-LCO CRCX. With the current master we expect the test to fail.

https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/9479 MGCP_Test: Test non LCO crcx

#5 Updated by dexter about 1 month ago

  • % Done changed from 50 to 80

#6 Updated by dexter about 1 month ago

  • % Done changed from 80 to 90

osmo-mgw now can handle missing LCO. When there is an CRCX without a: option in LCO, PCMU is picked as default. However. I have to revisit the TTCN3 test for non lco. The problem here is that osmo-mgw now supresses IANA assigned codecs in rtpmap (unnecessary because already fully defined) this makes the test fail while the osmo-mgw response is completely legal.

See also:
https://gerrit.osmocom.org/#/c/osmo-mgw/+/9648/

#7 Updated by dexter about 1 month ago

The testcase for non-lco CRCX turned out to be to restrictive. The MGW now supresses unnecessary listing of media attributes, so our default "PCMU/8000/1" will not appear in the media attributes. We must change the check and see if the payload type number (0) appears in the media description.

https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/9691 MGCP_Test: ts_CRCX_no_lco: check media description instead of media attribute

#8 Updated by dexter about 1 month ago

  • % Done changed from 90 to 100

#9 Updated by dexter 28 days ago

  • Status changed from In Progress to Resolved

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