* taken from the flow specified in the 'execute->key_len' bytes of
* 'execute->key'. ('execute->key' is mostly redundant with
* 'execute->packet', but it contains some metadata that cannot be
* taken from the flow specified in the 'execute->key_len' bytes of
* 'execute->key'. ('execute->key' is mostly redundant with
* 'execute->packet', but it contains some metadata that cannot be