This uses ssl3_read_bytes for now. We still need to dismantle that
function and then invert the handshake state machine, but this gets
things closer to the right shape as an intermediate step and is a large
chunk in itself. It simplifies a lot of the CCS/handshake
synchronization as a lot of the invariants much more clearly follow from
the handshake itself.
Tests need to be adjusted since this changes some error codes. Now all
the CCS/Handshake checks fall through to the usual
SSL_R_UNEXPECTED_RECORD codepath. Most of what used to be a special-case
falls out naturally. (If half of Finished was in the same record as the
pre-CCS message, that part of the handshake record would have been left
unconsumed, so read_change_cipher_spec would have noticed, just like
read_app_data would have noticed.)
Change-Id: I15c7501afe523d5062f0e24a3b65f053008d87be
Reviewed-on: https://boringssl-review.googlesource.com/6642
Reviewed-by: Adam Langley <agl@google.com>
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