On SCTP_NOTIFY_ASSOC_DOWN, the receive callback (recv_callback) gets called with zero information

[dirkz]

How to reproduce:

• Server creates the socket with a receive callback, and event types SCTP_REMOTE_ERROR, SCTP_SHUTDOWN_EVENT, SCTP_PARTIAL_DELIVERY_EVENT, SCTP_SENDER_DRY_EVENT.
• Server binds, waits for data.
• Client sends a message, disconnects.
• Server's receive callback is called.

Observed:

In the call to the receive callback, the data is NULL (and therefore any info about the notification), and the address is memset to all 0s.

Expected:

The receive callback gets usable data that it can act upon, like notification data and peer address.

Notes:

• The calling line is here: sctputil.c.

[tuexen]

Does the server get the message sent by the client before the receive callback with NULL fires? I'm expecting to see a NULL as the last thing happening (like a recv() would return 0).

[dirkz]

Yes, the message is fully received, no problems there. If this is expected behavior, I can certainly handle it, but I wasn't sure if the code I was looking at does what it does intentionally.

[tuexen]

You need an indication that you will not receive anything further. In the socket API, the recv() call returns 0. We model this by also providing 0 in the length and the NULL pointer for the data. That is expected and allows you to do cleanup if needed.

[dirkz]

Thanks for the info. Will close because works as designed.