SSL_get_current_cipher is documented by upstream to return the cipher actually
being used. However, because it reads s->session, it returns information
pertaining to the session to be offered if queried before ServerHello or early
in an abbreviated handshake.
Logic around s->session needs more comprehensive cleanup but for just this
function, defining it to be the current outgoing cipher is close to the current
semantics but for fixing the initial state (s->session->cipher is populated
when sending CCS). Store it in the SSL_AEAD_CTX which seems a natural place to
associate state pertaining to a connection half.
BUG=484744
Change-Id: Ife8db27a16615d0dbb2aec65359537243e08af7c
Reviewed-on: https://boringssl-review.googlesource.com/4733
Reviewed-by: Adam Langley <agl@google.com>
a07c0fc8f2