@startuml
#PaleVioletRed:Decoded to_server message;
fork
    :Direct user message;
    :Store message to provided lookup key;
fork again
    :Matriochka user message;
    :Forward to next server;
fork again
    :Known servers message;
    :Send back known servers list;
fork again
    :Broadcast message;
    :Store message to 255 lookup key;
fork again
    :Admin message;
    :Store message to 0 lookup key;
end fork
(*)
@enduml