This XML document describes the KGS protocol. It is also used to automatically generate the perl parser for all the messages and structures in the protocol. Adapting it to other languages should be almost trivial (and partly has been done).
If you feel you need to update the visual appearance of this document, feel free to look at doc/doc2html.xsl and improve it.
The current version of this document can always be found at here, while the HTML version of it can be found here.
"ORIGIN: CLIENT" means messages send from the client to the server, while "ORIGIN: SERVER" means messages send by the server to the client.
Everything on the wire is in little-endian format (what a shame).
Primitive types are mostly integers (signed
"I<bits>", unsigned "U<bits>"),
ascii strings ("username"), zero- or non-terminated
UCS2-Strings ("ZSTRING" or "STRING"). Yes,
I know java is supposed to do UTF-16, but no implementation seems to
care...
To get a feel for the protocol, get the KGS perl module from CPAN, install it an run kgstrace, then conenct to 127.0.0.1 with your client. kgstrace will dump all messages from and to the server.
For the rest, go figure or bug me, Marc Lehmann <pcg@goof.com>
After connecting to the server, a handshake byte is sent. It's the major version number of the protocol the client expects to receive. Version 3 and 4 are mostly the same, except that Version 4 clients expect server messages to be compressed, version 3 clients do not. (version 3 probably is no longer supported).
The server sends back his protocol number, which is always 3 in the current protocol. Most of the protocol variation is determined by the server using the client version that is used in the initial login message, not the initial handshake byte.
After the initial handshake, the client sends uncompressed messages, while the server sends back a zlib-compressed stream (rfc1950 and rfc1951).
All messages have the same header:
The length is the length of the full message including the header.
Beginning with version 2.5.x, a number is xored into the low
byte of the length in sent packages only, as given by the
following recurrence: rand[0] = 0; rand[i+1] = msg[i].length
+ (rand[i] * 0x04c2af9b + 0xfffffffb); xorbyte = rand >>
24, all in 32 bit unsigned iso-c arithmetic.
If the type is >= 0x4000 this is a message for a specific channel. The channel number is always the next U16. All of these channel values are valid, including zero.
Beginning with version 2.5.x, a number is added on received messages only. The algorithm is as follows:
msglen < 44: type = typefield
msglen > 44: type = (typefield + rand[i]) % 0x10000
rand[0] = 0
rand[i+1] = username[type % length username] + rand[i] * (type - 0x6cdd)
where username is the user name of the logged-in user. coooool.
Apart from the basic types, I need to define some extra types to
deal with fixed-point values (based on integer types) or fixed-length
strings (either 7-bit-ascii or more limited (A), or UCS-2
based (S)).
The basic user or login name, used throughout the protocol as a handle to the user.
Many strings in the protocol are fixed-width for no good reason (maybe this is one reason for using compression in newer versions, as the packets itself are wasting lots of space.
Used in user_record.
A kind of locale specifier. It seems the general format seems to be lowercase language, underscore, uppercase location, e.g. en_US. More fancy specifications don't fit.
Just a simple boolean value. 0 means false, and 1 generally true, but I suggest accepting != 0 as true.
Komi values are multiplied by 2 or 4 to make them integer in the protocol.
The game result is also multiplied by 2 to give it higher resolution. There are also special values for wins by time etc., either in result or in the score* types, or both :)
A score value (used for displaying the score at the end of a game) are multiplied by 2 or 4 for a change (the 0.25 resolution is not used). In game structures it is encoded by dividing by two, though, so watch out! And in some others, it's encoded by multiplying by 1000... yuck!
Time values are multiplied by 1000, giving them millisecond accuracy.
64 bit timeval, milliseconds since posix epoch, e.g. my
($year, $month, $day) = (gmtime $date * 0.001)[5,4,3];
Password is a number calculated as follows (VERY insecure, basically
plaintext!): password = 0; for char in characters do password ←
password * 1055 + ascii_code (char)
An id chosen by the client, usually starting at one, to identify some handshakes initiated by the client, such as new games or memos.
PRIVATE is or'ed onto DEMONSTRATION or TEACHING
Admins only(?)
Seems to be set on the english room. Or maybe not.
This room is private.
Special score values, in addition to numerical scores. Some are also used with their negative value. Unfortunately, these are the raw vaues, before scaling. WMS loves code duplication.
Convinience constants used in several places.
Sometimes used to mark absence of marks, or no player or etc...
Almost everywhere a user + flags is required, even used in some places where only a username is required. I see no general rule on when a complete user and when a partial user is required.
This structure is used for challenges as well as in the special TREE "subprotocol". It tightly encodes the game parameters.
Sent to login, usually the first message sent. The password needs to be set when the guest flag is true. Possible replies: . Followed by:
Request info about a certain user. Possible reply:
Update user info. Message structure is very similar to .
This message is sent to initiate or continue a private chat with a user. You'll always receive a copy of what you have sent back from the server (as usual).
No idea. Not used anymore?
Request user graph data, replied with .
Request a user picture from the server. Results in a or a timeout.
A boolean, probably. Always true for me.
Unconditionally deletes all memos.
Send a global message. Maybe. Never tried, for obvious reasons :/. Results in a sent to all users.
Probably setting a notifier on a username, to get informed about changes using messages. sending your own username gives you a disconnect, so don't do that at home, kids!
Probably remove the notifier again.
List the rooms in a specific group/category. Results in a message.
Request a rooms update message for the given room.
Requests part of the users game record to be sent. Results in a or maybe a timeout.
If zero, start at the newest games, else this should be the timestamp of the first gamerecord sent in the response.
Joins the given room. messages for yourself and all users in that room, as well as the initial gamelist, are send if the room exists. If not, timeout...
Create a new game.
The room where to start the new game
GAMETYPE_UPLOAD probably not allowed. GAMETYPE_PRIVATE only allowd together with GAMETYPE_TEACHING, GAMETYPE_DEMONSTRATION.
0x2 == global open game list
When cloning a game, the rules are set up like this: count => 65535, ruleset => 0, time => 4294967295, timesys => 0, interval => 4294967295. Cloning itself seems to be implemented solely in the client (somewhat sane, for a change).
Used to send challenges to existing games.
Possibly an id. No idea. Better echo this from the challenge request.
Upload a partial game tree to the server. This is used to send moves and even in-game comments to the server. For the comments, the server prepends the username and rank.
Marks stones ad dead (or alive?) by the client. Details unclear
Possibly true means mark dead and false unmark, but that's just a wild guess.
Request the game tree starting at a given node. This is used when the server only sends a partial tree (with end code "more").
Sent by the client to mark the game as done.
An id field (start at one please) to make sure that the client responds to the correct done click.
Used by the client to claim a win.
Adds the given amount of time to your opponent's clock.
Change the teacher to somebody else (or possibly yourself == take it). If the name is empty, the game will continue normally.
Unclear. Maybe allow users to talk? No idea, really.
Only during playing, moves.
Possibly an id. No idea. Better echo this from the challenge request.
Quite brokenly, the want this to send you more comments. Reply to .
Is send when a game is closed and should be saved on the gamerecord.
Sets (or clears) the quiet flag on a game.
Sent by the client just before it logs out.
The ruleset member is a pure guess, please verify. it could also be after size for example.
The room channel.
A single game record entry, as seen in .
A revision number in case there are multiple similar games.
0:11 == komi * 2; 12:15 == no idea, always 1-0-0-0?
0:5 == size; 6 no idea; 7 == inprogress
No idea. I see many values here.
Sent when no userinfo for the requested user could be found(?)
idle warning, autologout soon (10 minutes...). Responding with usually helps.
Account unknown.
Just a guess.
User is currently online, please use chat.
Just a guess.
The memo was sent successfully
Game result record?
Is sent after the initial messages, probably to signify the end of the login process.
The cid of the new_game etc. request.
Wether more games are available (must be requested manually by another message with the timestamp set to the timestamp of the first game of this packet.
Game records, from oldest to newest.
Adds or updates a global challenge (open game list).
The game. The "moves" member contains a small number. Probably garbage.
Not all room messages are for rooms only, and rooms need to parse not only these messages. Orthogonality, what for?
Possibly an id. No idea. Better echo this from the challenge request.
This field is optional
Send by the server when one of the players sends a done.
An id field to make sure that the client responds to the correct done click.
The high bit has the "please press done again" warning function, i.e. if set, opponent has changed board.
Sent when the opponent is out of time and moves, or when the other requests .
Colour who won the game.
See . In addition, flags the tree as being uploaded completely.
Possibly an id. No idea. Better echo this from the challenge request.
Sent at end of games to set the comments not seen previously.
Sent at end of games to add all game commentary.
Quite brokenly, the server sends you this to make you ask for more comments. Reply with .
Notifies the client that a new game has been created. This message is sent long *after* upd_games and upd_observers etc. have been received. *sigh*
The newly created game.
The ID sent to the server in new_game.
Sets (or clears) the quiet flag on a game.
Sent when joining a running game. Gives the remaining time + periods/moves for the players, to correctly initialize the clocks.
Remove a game from the global challenge list (open game list).
The game id to remove.
Probably the same. I suggest to use this id for no good reason.