As of our 82b7da271f, an SSL_SESSION created
externally always has a cipher set. Unknown ciphers are rejected early. Prior
to that, an SSL_SESSION would only have a valid cipher or valid cipher_id
depending on whether it came from an internal or external session cache.
See upstream's 6a8afe2201cd888e472e44225d3c9ca5fae1ca62 and
c566205319beeaa196e247400c7eb0c16388372b for more context.
Since we don't get ourselves into this strange situation and s->cipher is now
always valid for established SSL_SESSION objects (the existence of
unestablished SSL_SESSION objects during a handshake is awkward, but something
to deal with later), do away with s->cipher_id altogether. An application
should be able to handle failing to parse an SSL_SESSION instead of parsing it
successfuly but rejecting all resumptions.
Change-Id: I2f064a815e0db657b109c7c9269ac6c726d1ffed
Reviewed-on: https://boringssl-review.googlesource.com/2703
Reviewed-by: Adam Langley <agl@google.com>