ktls: improve messaging around freed handshakes #4346
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goatgoose
reviewed
Jan 9, 2024
camshaft
approved these changes
Jan 9, 2024
goatgoose
approved these changes
Jan 9, 2024
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Description of changes:
A customer integrating with ktls ran into a "NULL pointer encountered" error because they tried to enable ktls after freeing the handshake, which is required to calculate the TLS1.2 keys. I've updated the documentation and added a specific check for "prf_space" so that the caller gets the slightly more helpful "Invalid state, this is the result of invalid use of an API. Check the API documentation for the function that raised this error for more info" error.
Call-outs:
We could theoretically re-allocate and then re-free the memory needed to calculate the TLS1.2 keys, but I don't think that's the right behavior. We should just provide the information the application needs to call the API in a way that doesn't waste memory.
Testing:
I manually verified that prf_space is the only field from the handshake that ktls needs for either TLS1.2 or TLS1.3 by adding the call to s2n_connection_free_handshake, but without s2n_prf_free.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.