Fix (and cleanup) crypto flags in combination with NCP

Fix (and cleanup) crypto flags in combination with NCP

tls_session_update_crypto_params() did not properly set crypto_flags_or,
but instead set crypto_flags_and twice if a OFB/CFB mode was selected.

Also, the crypto flags in ks->crypto_options.flags were set before
tls_session_update_crypto_params() was called, causing those to not be
adjusted.  To fix this, set the crypto flags in
tls_session_generate_data_channel_keys() instead of key_state_init().

While touching that code, remove the to _or and _and variables, which are
not needed at all.

Finally, refuse to accept --no-iv if NCP is enabled  (we might otherwise
negotiate invalid combinations and ASSERT out later, and using --no-iv is
a bad idea anyway).

Trac: #784

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1481133684-5325-1-git-send-email-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13428.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>