[asterisk-dev] [Code Review] sip: ignore CANCEL request after having already received final response to INVITE

[David Vossel]

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https://reviewboard.asterisk.org/r/697/
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Review request for Asterisk Developers.


Summary
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RFC 3261 section 9 states that a CANCEL has no effect on a request to a UAS that has already given a final response.  This patch checks to make sure there is a pending invite before allowing a CANCEL request to be processed, otherwise it responds to the CANCEL with a "481 Call/Transaction Does Not Exist".


Diffs
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  /trunk/channels/chan_sip.c 269006 

Diff: https://reviewboard.asterisk.org/r/697/diff


Testing
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I wrote two SIPP scenarios to test this.

1. A CANCEL is sent after the final response for an INVITE is provided.  I verified the new 481 response is given in response to the late CANCEL.

2. A CANCEL is sent before the final response for an INVITE is provided.  I verified the invite is canceled as expected.


Thanks,

David