Mysql_protocol.Mp_authenticationval client_authentication_packet : 
  handshake:Mp_handshake.handshake ->
  capabilities:Mp_capabilities.capabilities list ->
  max_packet_size:int64 ->
  charset_number:int ->
  user:string ->
  password:string ->
  databasename:string ->
  auth_plugin_name:string ->
  Bitstring.bitstring