OpenSSL: ASYNC operations and application callback function.

Narasimha Nayak narasimha.nayak at
Fri Sep 13 16:47:52 UTC 2019

Hello All,

I am investigating the usage of OpenSSL v1.1.1.c with QAT offload.

As part of the investigation to enable ASYNC mode for SSL ops I came across
the possibility of providing callbacks via “SSL_CTX_set_async_callback”,
and not use poll/select as required earlier.

The callback functionality has been added via commit (
in Nov, 2018.

These changes are not yet part of OpenSSL v1.1.1c/d.

Hence I would like to understand the following:

   1. Is this feature complete and use-able with QAT engine provided by
   Intel for OpenSSL ? Are there any drawbacks to be aware of ?
   2. Do we have any examples to depict the usage for these APIs ? Will
   help to know if there are any corner cases to handle.

Any feedback is much appreciated.


Thanks and Regards,

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