3.2.5.2 Processing a Request in the AuthReceived State

When the server receives a request in the AuthReceived state, the server MUST attempt to parse it according to the auth_login_username_response ABNF rule specified in section 2.2.2. The server MUST save the username in the Username associated with the connection, set the Substate to UsernameReceived, and send a response that conforms to the auth_login_password_challenge ABNF rule..