Admin Network

   Preface
1. Joining the network
2. Asking for updates
3. Polling manually
4. Sending rcon commands
5. Sending chat
6. Receiving chat
7. Disconnecting
8. Certain packet information


   Preface
----------

  The admin network provides a dedicated network protocol designed for other
  applications to communicate with OpenTTD. Connected applications can execute
  console commands remotely (rcon commands) with no further authentication.
  Furthermore information about clients and companies can be provided.

  Admin applications remain connected when starting a new game or loading a saved
  game in contrast to normal OpenTTD clients that get disconnected.

  This document describes the admin network and its protocol.

  Please refer to the mentioned enums in src/network/core/tcp_admin.h

  Please also note that further improvements to the admin protocol can mean that
  more packet types will be sent by the server. For forward compatibility it is
  therefore wise to ignore unknown packets. Future improvements might also add
  additional data to packets. This data should be ignored. Data will never be
  removed from packets in later versions, except the possibility that complete
  packets are dropped in favour of a new packet.
  This though will be reflected in the protocol version as announced in the
  ADMIN_PACKET_SERVER_PROTOCOL in section 1.


1. Joining the network
----------------------

  Create a TCP connection to the server on port 3977. The application is
  expected to authenticate within 10 seconds.

  To authenticate send a ADMIN_PACKET_ADMIN_JOIN packet.

  The server will reply with ADMIN_PACKET_SERVER_PROTOCOL followed directly by
  ADMIN_PACKET_SERVER_WELCOME.

  ADMIN_PACKET_SERVER_PROTOCOL contains details about the protocol version.
  It is the job of your application to check this number and decide whether
  it will remain connected or not.
  Furthermore, this packet holds details on every AdminUpdateType and the
  supported AdminFrequencyTypes (bitwise representation).

  ADMIN_PACKET_SERVER_WELCOME contains details on the server and the map,
  e.g. if the server is dedicated, its NetworkLanguage, size of the Map, etc.

  Once you have received ADMIN_PACKET_SERVER_WELCOME you are connected and
  authorized to do your thing.
  The server will not provide any game related updates unless you ask for them.
  There are four packets the server will none the less send, if applicable:
    - ADMIN_PACKET_SERVER_ERROR
    - ADMIN_PACKET_SERVER_WELCOME
    - ADMIN_PACKET_SERVER_NEWGAME
    - ADMIN_PACKET_SERVER_SHUTDOWN

  However, ADMIN_PACKET_SERVER_WELCOME only after a ADMIN_PACKET_SERVER_NEWGAME


2. Asking for updates
---------------------

  Asking for updates is done with ADMIN_PACKET_ADMIN_UPDATE_FREQUENCY.
  With this packet you define which update you wish to receive at which
  frequency.

  Note: not every update type supports every frequency. If in doubt, you can
  verify against the data received in ADMIN_PACKET_SERVER_PROTOCOL.

  The server will not confirm your registered update. However, asking for an
  invalid AdminUpdateType or a not supported AdminUpdateFrequency you will be
  disconnected from the server with NETWORK_ERROR_ILLEGAL_PACKET.

  Additional debug information can be found with a debug level of net=3.

  ADMIN_UPDATE_DATE results in the server sending:
    - ADMIN_PACKET_SERVER_DATE

  ADMIN_UPDATE_CLIENT_INFO results in the server sending:
    - ADMIN_PACKET_SERVER_CLIENT_JOIN
    - ADMIN_PACKET_SERVER_CLIENT_INFO
    - ADMIN_PACKET_SERVER_CLIENT_UPDATE
    - ADMIN_PACKET_SERVER_CLIENT_QUIT
    - ADMIN_PACKET_SERVER_CLIENT_ERROR

  ADMIN_UPDATE_COMPANY_INFO results in the server sending:
    - ADMIN_PACKET_SERVER_COMPANY_NEW
    - ADMIN_PACKET_SERVER_COMPANY_INFO
    - ADMIN_PACKET_SERVER_COMPANY_UPDATE
    - ADMIN_PACKET_SERVER_COMPANY_REMOVE

  ADMIN_UPDATE_COMPANY_ECONOMY results in the server sending:
    - ADMIN_PACKET_SERVER_COMPANY_ECONOMY

  ADMIN_UPDATE_COMPANY_STATS results in the server sending:
    - ADMIN_PACKET_SERVER_COMPANY_STATS

  ADMIN_UPDATE_CHAT results in the server sending:
    - ADMIN_PACKET_SERVER_CHAT

  ADMIN_UPDATE_CONSOLE results in the server sending:
    - ADMIN_PACKET_SERVER_CONSOLE


  ADMIN_UPDATE_CMD_LOGGING results in the server sending:
    - ADMIN_PACKET_SERVER_CMD_LOGGING

3. Polling manually
-------------------

  Certain AdminUpdateTypes can also be polled:
    - ADMIN_UPDATE_DATE
    - ADMIN_UPDATE_CLIENT_INFO
    - ADMIN_UPDATE_COMPANY_INFO
    - ADMIN_UPDATE_COMPANY_ECONOMY
    - ADMIN_UPDATE_COMPANY_STATS
    - ADMIN_UPDATE_CMD_NAMES

  ADMIN_UPDATE_CLIENT_INFO and ADMIN_UPDATE_COMPANY_INFO accept an additional
  parameter. This parameter is used to specify a certain client or company.
  Setting this parameter to UINT32_MAX (0xFFFFFFFF) will tell the server you
  want to receive updates for all clients or companies.

  Not supported AdminUpdateType in the poll will result in the server
  disconnecting the application with NETWORK_ERROR_ILLEGAL_PACKET.

  Additional debug information can be found with a debug level of net=3.


4. Sending rcon commands
------------------------

  Rcon runs separate from the ADMIN_UPDATE_CONSOLE AdminUpdateType. Requesting
  the execution of a remote console command is done with the packet
  ADMIN_PACKET_ADMIN_RCON.

  Note: No additional authentication is required for rcon commands.

  The server will reply with a ADMIN_PACKET_SERVER_RCON packet. Applications
  will not receive the answer twice if they have asked for the AdminUpdateType
  ADMIN_UPDATE_CONSOLE, as the result is not printed on the servers console
  (just like clients rcon commands).

  Furthermore, sending a 'say' command (or any similar command) will not
  be sent back into the admin network.
  Chat from the server itself will only be sent to the admin network when it
  was not sent from the admin network.


5. Sending Chat
---------------

  Sending a ADMIN_PACKET_ADMIN_CHAT results in chat originating from the server.

  Currently four types of chat are supported:
    - NETWORK_ACTION_CHAT
    - NETWORK_ACTION_CHAT_CLIENT
    - NETWORK_ACTION_CHAT_COMPANY
    - NETWORK_ACTION_SERVER_MESSAGE

  NETWORK_ACTION_SERVER_MESSAGE can be sent to a single client or company
  using the respective DestType and ID.
  This is a message prefixed with the 3 stars, e.g. *** foo has joined the game


6. Receiving chat
-----------------

  Register ADMIN_UPDATE_CHAT at ADMIN_FREQUENCY_AUTOMATIC to receive chat.
  The application will be able to receive all chat the server can see.

  The configuration option network.server_admin_chat specifies whether
  private chat for to the server is distributed into the admin network.


7. Disconnecting
----------------

  It is a kind thing to say good bye before leaving. Do this by sending the
  ADMIN_PACKET_ADMIN_QUIT packet.


8. Certain packet information
-----------------------------

  All ADMIN_PACKET_SERVER_* packets have an enum value greater 100.

  ADMIN_PACKET_SERVER_WELCOME
    Either directly follows ADMIN_PACKET_SERVER_PROTOCOL or is sent
    after a new game has been started or a map loaded, i.e. also
    after ADMIN_PACKET_SERVER_NEWGAME.

  ADMIN_PACKET_SERVER_CLIENT_JOIN and ADMIN_PACKET_SERVER_COMPANY_NEW
    These packets directly follow their respective INFO packets. If you receive
    a CLIENT_JOIN / COMPANY_NEW packet without having received the INFO packet
    it may be a good idea to POLL for the specific ID.

  ADMIN_PACKET_SERVER_CMD_NAMES and ADMIN_PACKET_SERVER_CMD_LOGGING
    Data provided with these packets is not stable and will not be
    treated as such. Do not rely on IDs or names to be constant
    across different versions / revisions of OpenTTD.
    Data provided in this packet is for logging purposes only.