MGCP: When Call actor receives CANCEL on inbound call before MS has send respond to CRCX, Connect tries to remove all endpoints

[gvagenas]

... using DLCX mobicents/bridge/$ and DLCX mobicents/ivr/$
It should wait for response from MS to get the endpoint and then use the specific endpoint for DLCX

[hrosa]

Here's relevant portion from a pcap

• INVITE comes in and RestComm sends CRCX to the Media Server, to create bridge and IVR endpoints.
• User Agent CANCELs the call. At this point, RestComm has not yet received the MGCP response to the CRCX request. So resources were created at MS side but RestComm is still not aware of their IDs.
• RestComm sends DLCX to the media server with wildcard. This is not allowed!

My suggestion is that RestComm Call actor should enter a CANCELING state where it waits for the pending response from Media Server, before proceeding with resource cleanup.

This issue is serious and can cripple the system, because ghost resources will be left unchecked on Media Server side, consuming memory and CPU.

[gvagenas]

It's very hard to reproduce the issue with live test calls, since the CANCEL must arrive 10-15ms after INVITE.
Its impossible to reproduce on the testsuite.