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<h1>$Revision: 1.78 $</h1>

<h1>KGS Protocol Description</h1>

   <p>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).</p>

   <p>If you feel you need to update the visual appearance of this
   document, feel free to look at <tt>doc/doc2html.xsl</tt> and improve
   it.</p>

   <p>The current version of this document can always be found at 
   <a href="http://cvs.schmorp.de/browse/*checkout*/kgsueme/doc/protocol.xml">here</a>, while
   the HTML version of it can be found
   <a href="http://cvs.schmorp.de/browse/*checkout*/kgsueme/doc/protocol.html">here</a>.</p>

<h2>Structure and conventions of this document and the protocol</h2>

   <p>"ORIGIN: CLIENT" means messages send from the client to the server,
   while "ORIGIN: SERVER" means messages send by the server to the
   client.</p>

   <p>Everything on the wire is in little-endian format (what a shame).</p>

   <p>Primitive types are mostly integers (signed
   "<code>I</code>&lt;bits&gt;", unsigned "<code>U</code>&lt;bits&gt;"),
   ascii strings ("<code>username</code>"), zero- or non-terminated
   UCS2-Strings ("<code>ZSTRING</code>" or "<code>STRING</code>"). Yes,
   I know java is supposed to do UTF-16, but no implementation seems to
   care...</p>

   <p>To get a feel for the protocol, get the <tt>KGS</tt> perl module
   from CPAN, install it an run <tt>kgstrace</tt>, then conenct to
   <tt>127.0.0.1</tt> with your client. <tt>kgstrace</tt> will dump all
   messages from and to the server.</p>

   <p>For the rest, go figure or bug me, <a
   href="mailto:pcg@goof.com">Marc Lehmann &lt;pcg@goof.com&gt;</a></p>

<h2>Stream and message structure.</h2>

   <p>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).</p>

   <p>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.</p>

   <p>After the initial handshake, the client sends uncompressed
   messages, while the server sends back a zlib-compressed
   stream (<a href="http://rfc1950.x42.com/">rfc1950</a> and <a
   href="http://rfc1950.x42.com/">rfc1951</a>).</p>

   <p>All messages have the same header:</p>

   <struct name="message_header">
      <member name="length" type="U16"/>

      <p>The length is the length of the full message including the header.</p>

      <p>Beginning with version 2.5.x, a number is xored into the low
      byte of the length in <em>sent</em> packages only, as given by the
      following recurrence: <code>rand[0] = 0; rand[i+1] = msg[i].length
      + (rand[i] * 0x04c2af9b + 0xfffffffb); xorbyte = rand &gt;&gt;
      24</code>, all in 32 bit unsigned iso-c arithmetic.</p>

      <member name="type" type="U16"/>
      <p>If the type is &gt;= 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.</p>

      <p>Beginning with version 2.5.x, a number is <em>added</em> on <em>received</em>
      messages only. The algorithm is as follows:
      
      <pre>
         msglen &lt; 44: type = typefield
         msglen &gt; 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.
      </pre>
      </p>

   </struct>

<h2>Primitive types used in the protocol.</h2>

   <p>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 (<code>A</code>), or UCS-2
   based (<code>S</code>)).</p>

   <type name="username" type="A" length="10"/>

   <p>The basic user or login name, used throughout the protocol
   as a handle to the user.</p>

   <type name="roomname" type="S" length="25"/><!-- argh, how horribly broken -->

   <p>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.</p>

   <type name="realname" type="S" length="50"/>
   <type name="email" type="S" length="70"/>
   <type name="userinfo" type="S" length="1000"/>
   <type name="url" type="A" length="100"/>

   <p>Used in user_record.</p>

   <type name="locale" type="A" length="5"/>

   <p>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.</p>

   <type name="flag" type="U8" multiplier="1"/>

   <p>Just a simple boolean value. 0 means false, and 1 generally true,
   but I suggest accepting != 0 as true.</p>

   <type name="komi16_2" type="I16" multiplier="2"/>
   <type name="komi16_4" type="I16" multiplier="4"/>
   <type name="komi32_2" type="I32" multiplier="2"/>
   <type name="komi32_4" type="I32" multiplier="4"/>

   <p>Komi values are multiplied by 2 or 4 to make them integer in the
   protocol.</p>

   <type name="result" type="I32" multiplier="2"/>

   <p>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 :)</p>

   <type name="score16_2" type="I16" multiplier="2"/>
   <type name="score16_4" type="I16" multiplier="4"/>
   <type name="score32_4" type="I32" multiplier="4"/>
   <type name="score32_1000" type="I32" multiplier="1000"/>

   <p>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!</p>

   <type name="time" type="U32" multiplier="1000"/>

   <p>Time values are multiplied by 1000, giving them millisecond
   accuracy.</p>

   <type name="timestamp" type="U64" multiplier="1000"/>

   <p>64 bit timeval, milliseconds since posix epoch, e.g. <code>my
   ($year, $month, $day) = (gmtime $date * 0.001)[5,4,3];</code></p>

   <type name="password" type="U64"/>

   <p>Password is a number calculated as follows (VERY insecure, basically
   plaintext!): <code>password = 0; for char in characters do password ←
   password * 1055 + ascii_code (char)</code></p>

   <type name="CLIENTID16" type="U16" multiplier="1"/>
   <type name="CLIENTID8" type="U8" multiplier="1"/>

   <p>An id chosen by the client, usually starting at one, to identify
   some handshakes initiated by the client, such as new games or memos.</p>

<h2>Enumeration and set types used in the protocol.</h2>

   <enum name="GAMETYPE">
      <member name="DEMONSTRATION" value="0"/>
      <member name="EDITING"       value="1"/>
      <member name="TEACHING"      value="2"/>
      <member name="SIMUL"         value="3"/>
      <member name="FREE"          value="4"/>
      <member name="RATED"         value="5"/>
      <member name="PRIVATE"       value="128"/>
      <p>PRIVATE is or'ed onto DEMONSTRATION or TEACHING</p>
   </enum>

   <set name="GAMEFLAG">
      <member name="SCORED"    value="1"/>
      <member name="ADJOURNED" value="2"/>
      <member name="UPLOADED"  value="4"/>
   </set>

   <set name="ROOMFLAG">
      <member name="ADMIN"    value="0x01"/>
      <p>Admins only(?)</p>
      <member name="DEFAULT"  value="0x04"/>
      <p>Seems to be set on the english room. Or maybe not.</p>
      <member name="PRIVATE"  value="0x10"/>
      <p>This room is private.</p>
   </set>

   <set name="GAMESTATUS">
      <member name="INPLAY"    value="0x80"/>
   </set>

   <enum name="SCORE">
      <p>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.</p>

      <member name="TIMEOUT"   value="16384"/>
      Also used negatively to score for white instead of black.

      <member name="RESIGN"    value="16385"/>
      Also used negatively to score for white instead of black.

      <member name="FORFEIT"   value="    0"/>
      Also used negatively to score for white instead of black.

      <member name="JIGO"      value="16386"/>

      <member name="NO_RESULT" value="16386"/>
      <member name="ADJOURNED" value="16387"/>
      <member name="UNKNOWN"   value="16389"/>
   </enum>

   <enum name="RULESET">
      <member name="JAPANESE"    value="0"/>
      <member name="CHINESE "    value="1"/>
      <member name="AGA"         value="2"/>
      <member name="NEW_ZEALAND" value="3"/>
   </enum>

   <enum name="TIMESYS">
      <member name="NONE"     value="0"/>
      <member name="ABSOLUTE" value="1"/>
      <member name="BYO_YOMI" value="2"/>
      <member name="CANADIAN" value="3"/>
   </enum>

   <enum name="COLOUR">
      <p>Convinience constants used in several places.</p>
      <member name="BLACK" value="0"/>
      <member name="WHITE" value="1"/>
      <member name="NONE" value="2"/>
      <p>Sometimes used to mark absence of marks, or no player or etc...</p>
   </enum>

<h2>Structs used in send &amp; receive messages</h2>

   <struct name="user" class="KGS::User">

      <p>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.</p>

      <member name="name" type="username"/>
      <member name="flags" type="U32" value="1"/>
   </struct>

   <struct name="rules" class="KGS::Rules">

      <p>This structure is used for challenges as well as in the special
      TREE "subprotocol". It tightly encodes the game parameters.</p>

      <member name="ruleset" type="U8"/>
      <member name="size" type="U8"/>
      <member name="handicap" type="U8"/>
      <member name="komi" type="komi16_2"/>
      <member name="timesys" type="U8"/>
      <member name="time" type="U32"/>
      <member name="interval" type="U32"/>
      byo-yomi time / canadian time
      <member name="count" type="U16"/>
      periods / moves
   </struct>

<h2>Structs used in messages from the client</h2>

<h2>Client-generated messages</h2>

   <message type="0000" name="login" src="client">

      <p>Sent to login, usually the first message sent. The password needs to be set when the
      guest flag is true.
      Possible replies: <ref reply="login"/>. Followed by: <ref reply="timewarning_default"/> <ref reply="chal_defaults"/>
      </p>

      <member name="ver_major" type="U32" value="2"/>
      <member name="ver_minor" type="U32" value="6"/>
      <member name="ver_micro" type="U32" value="1"/>
      <member name="name" type="username"/>
      <member name="password" type="password" value="0"/>
      <member name="guest" type="flag" value="1"/>
      <member name="_unknown3" type="U16" value="0"/>
      <member name="locale" type="locale" value='"en_US"'/>
      <member name="clientver" type="DATA" value='"1.4.2_03:Swing app:Sun Microsystems Inc."'/>
      The "default" is the java vm version, not exactly he client version. However,
      you should always send a text like "Jonathan's C client version 0.6" or somesuch,
      so the server can, if necessary, block broken clients or client versions.
   </message>

   <message type="0007" name="req_userinfo" src="client">
      <p>Request info about a certain user. Possible reply: <ref reply="userinfo"/></p>
      <member name="name" type="username"/>
   </message>

   <message type="0007" name="update_userinfo" src="client">
      <p>Update user info. Message structure is very similar
      to <ref ref="userinfo"/>.</p>
      <member name="setpass" type="flag"/>
      Should the password be updated?
      <member name="password" type="password" value="0"/>
      <member name="realname" type="realname"/>
      <member name="email" type="email"/>
      <member name="info" type="userinfo"/>
      <member name="homepage" type="url"/>
      <member name="_unused" type="U64" value="0"/>
      <member name="_unused" type="U64" value="0"/>
   </message>

   <message type="0013" name="msg_chat" src="client">
      <p>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).</p>

      <member name="name" type="username"/>
      Name of sender ("yourself").
      <member name="name2" type="username"/>
      Name of recipient.
      <member name="message" type="STRING"/>
      The message.
   </message>

   <message type="0014" name="req_stats" src="client">
      <p>Request server statistics. Replied with <ref reply="stats"/></p>
   </message>

   <message type="0016" name="idle_reset" src="client">
      <p>Send in response to <ref reply="idle_warn"/> to keep the server from disconnecting.</p>
   </message>

   <message type="001d" name="ping" src="client">
      <p>No idea. Not used anymore?</p>
   </message>

   <message type="001e" name="req_usergraph" src="client">
      <p>Request user graph data, replied with <ref reply="usergraph"/>.</p>
      <member name="name" type="username"/>
   </message>

   <message type="0021" name="req_pic" src="client">
      <p>Request a user picture from the server. Results in a <ref reply="userpic"/>
      or a timeout.</p>
      <member name="name" type="username"/>
   </message>

   <message type="0021" name="upload_pic" src="client">
      Same code as pic_req, but with an additional data section that
      must contain a JPEG image that is &lt;=7KB. It must have 141×200 pixels.
      <member name="name" type="username"/>
      <member name="data" type="DATA"/>
   </message>

   <message type="0023" name="send_memo" src="client">
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
      <p>A boolean, probably. Always true for me.</p>
      <member name="msg" type="STRING"/>
   </message>

   <message type="0024" name="delete_memos" src="client">
      <p>Unconditionally deletes all memos.</p>
   </message>

   <message type="0100" name="gnotice" src="client">
      <p>Send a global message. Maybe. Never tried, for obvious reasons :/. Results
      in a <ref reply="gnotice"/> sent to all users.</p>
      <member name="notice" type="STRING"/>
   </message>

   <message type="0200" name="notify_add" src="client">

      <p>Probably setting a notifier on a username, to get informed about
      changes using <ref reply="notify_upd"/> messages. sending your own
      username gives you a disconnect, so don't do that at home, kids!</p>

      <member name="name" type="username"/>
   </message>

   <message type="0201" name="notify_del" src="client">

      <p>Probably remove the notifier again.</p>

      <member name="name" type="username"/>
   </message>

   <message type="0318" name="list_rooms" src="client">
      <p>List the rooms in a specific group/category. Results in a <ref reply="upd_rooms"/> message.</p>
      <member name="group" type="U8"/>
   </message>

   <message type="031a" name="new_room" src="client">
      Create a new room. Not verified.
      <member name="name" type="username"/>
      <member name="i1" type="U32" value="0"/>
      <member name="b1" type="U8" value="0"/>
      <member name="b2" type="U8" value="255"/>
      <member name="b3" type="U8" value="255"/>
      <member name="group" type="U8" value="1"/>
      <member name="name" type="ZSTRING"/>
      <member name="description" type="ZSTRING"/>
      <member name="flags" type="U8"/>
      See ROOMFLAGs
   </message>

   <message type="031b" name="req_upd_rooms" src="client">
      <p>Request a rooms update message for the given room.</p>
      <member name="channel" type="U16"/>
   </message>

   <message type="0413" name="req_game_record" src="client">
      <p>Requests part of the users game record to be sent. Results in a <ref reply="game_record"/> or maybe a timeout.</p>
      <member name="name" type="username"/>
      <member name="timestamp" type="timestamp"/>
      <p>If zero, start at the newest games, else this should be the timestamp
      of the first gamerecord sent in the <ref reply="game_record"/> response.</p>
   </message>

   <message type="4300" name="join_room" src="client">
      <p>Joins the given room. <ref reply="join_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...</p>
      <member name="channel" type="U16"/>
      <member name="user" type="user"/>
   </message>

   <message type="4301" name="msg_room" src="client">
      Send a message to the room.
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
      Must be the login-name of the user.
      <member name="message" type="STRING"/>
   </message>

   <message type="4302" name="part_room" src="client">
      Remove yourself (or maybe others as admin) from a room.
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
   </message>

   <message type="4305" name="new_game" src="client">
      <p>Create a new game.</p>

      <member name="channel" type="U16"/>
      <p>The room where to start the new game</p>
      <member name="cid" type="CLIENTID16"/>
      <member name="gametype" type="U8"/>
      <p>
         GAMETYPE_UPLOAD probably not allowed. GAMETYPE_PRIVATE
         only allowd together with GAMETYPE_TEACHING, GAMETYPE_DEMONSTRATION.
      </p>
      <member name="flags" type="U8"/>
      <p>
         0x2 == global open game list
      </p>
      <member name="rules" type="rules"/>
      <p>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).
      </p>
      <member name="notes" type="STRING"/>
   </message>

   <message type="430a" name="load_game" src="client">
      Load an existing game into a room(?)
      There is no indication that a new game is there except
      for a upd_observers message with your name in it. Which means
      you have to watch upd_observers messages that are not for any
      currently open game and open one. Ugh.
      <member name="channel" type="U16"/>
      The room to load the game into.
      <member name="timestamp" type="timestamp"/>
      From the game record.
      <member name="user" type="username"/>
      <member name="flags" type="U8"/>
      0 == public, 2 == private
   </message>

   <message type="430b" name="req_games" src="client">
      Request to update room game list (send this once per minute to get
      updated). Results in upd_games messages.
      <member name="channel" type="U16"/>
   </message>

   <message type="4319" name="req_desc" src="client">
      Request room description.
      <member name="channel" type="U16"/>
   </message>

   <message type="4400" name="challenge" src="client">
      <p>Used to send challenges to existing games.</p>
      <member name="channel" type="U16"/>
      <member name="black" type="user"/>
      <member name="white" type="user"/>
      <member name="gametype" type="U8"/>
      <member name="cid" type="CLIENTID8"/>
      <p>Possibly an id. No idea. Better echo this from the challenge request.</p>
      <member name="rules" type="rules"/>
   </message>

   <message type="4403" name="join_game" src="client">
      Join a game. See join_room.
      <member name="channel" type="U16"/>
      <member name="user" type="user"/>
   </message>

   <message type="4404" name="part_game" src="client">
      Leave (or kick as admin?) a certain user from a game.
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
   </message>

   <message type="4405" name="set_tree" src="client">
      Possibly upload an initial game to an empty room. Not tested.

      <member name="channel" type="U16"/>
      <member name="tree" type="TREE"/>
   </message>

   <message type="4406" name="upd_tree" src="client">
      <p>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.</p>
      <member name="channel" type="U16"/>
      <member name="tree" type="TREE"/>
   </message>

   <message type="4407" name="mark_dead" src="client">
      <p>Marks stones ad dead (or alive?) by the client. Details unclear</p>
      <member name="channel" type="U16"/>
      <member name="x" type="U8"/>
      <member name="y" type="U8"/>
      <member name="dead" type="flag"/>
      <p>Possibly true means mark dead and false unmark, but that's just a wild guess.</p>
   </message>

   <message type="4408" name="get_tree" src="client">
      <p>Request the game tree starting at a given node. This is used when
      the server only sends a partial tree (with end code "more").</p>
      <member name="channel" type="U16"/>
      <member name="node" type="U32"/>
   </message>

   <message type="440a" name="game_done" src="client">
      <p>Sent by the client to mark the game as done.</p>
      <member name="channel" type="U16"/>
      <member name="id" type="U32"/>
      <p>An id field (start at one please) to make sure that the client responds to the correct done click.</p>
   </message>

   <message type="440c" name="claim_win" src="client">
      <p>Used by the client to claim a win.</p>
      <member name="channel" type="U16"/>
      <member name="player" type="U8 "/>
   </message>

   <message type="440d" name="add_time" src="client">
      <p>Adds the given amount of time to your opponent's clock.</p>
      <member name="channel" type="U16"/>
      <member name="time" type="U32"/>
      <member name="player" type="U8"/>
   </message>

   <message type="440e" name="req_undo" src="client">
      <member name="channel" type="U16"/>
   </message>

   <message type="440f" name="grant_undo" src="client">
      Can be send after a req_undo message was received to grant the undo.
      <member name="channel" type="U16"/>
   </message>

   <message type="4410" name="resign_game" src="client">
      Resign the game.
      <member name="channel" type="U16"/>
      <member name="player" type="U8"/>
   </message>

   <message type="441a" name="set_teacher" src="client">
      <p>Change the teacher to somebody else (or possibly yourself == take it). If the
      name is empty, the game will continue normally.</p>
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
   </message>

   <message type="4422" name="allow_user" src="client">
      <p>Unclear. Maybe allow users to talk? No idea, really.</p>

      <member name="channel" type="U16"/>
      <member name="othername" type="username"/>
      <member name="name" type="username"/>; # gives user access to the game (to what? ;)
   </message>

   <message type="4423" name="set_privacy" src="client">
      Probably sets the "quiet" flag. Not checked.
      <member name="channel" type="U16"/>
      <member name="private" type="flag"/>
   </message>

   <message type="4427" name="game_move" src="client">
      <p>Only during playing, moves.</p>
      <member name="channel" type="U16"/>
      <member name="x" type="U8"/>
      <member name="y" type="U8"/>
   </message>

   <message type="4429" name="reject_challenge" src="client">
      Reject a challenge from a given user. Not checked.

      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
      <member name="gametype" type="U8"/>
      <member name="cid" type="CLIENTID8"/>
      <p>Possibly an id. No idea. Better echo this from the challenge request.</p>
      <member name="rules" type="rules"/>
   </message>

   <message type="442d" name="more_comments" src="client">
      <p>Quite brokenly, the want this to send you more comments.
      Reply to <ref ref="more_comments"/>.</p>
      <member name="channel" type="U16"/>
      <member name="node" type="U32"/>
   </message>

   <message type="442e" name="save_game" src="client">
      <p>Is send when a game is closed and should be saved on the gamerecord.</p>

      <member name="channel" type="U16"/>
   </message>

   <message type="4433" name="req_result" src="client">
      I forgot.

      <member name="channel" type="U16"/>
   </message>

   <message type="4434" name="set_quiet" src="client">
      <p>Sets (or clears) the quiet flag on a game.</p>
      <member name="channel" type="U16"/>
      <member name="quiet" type="flag"/>
   </message>

   <message type="4436" name="msg_game" src="client">
      <member name="channel" type="U16"/>
      <member name="message" type="STRING"/>
   </message>

   <message type="ffff" name="quit" src="client">
      <p>Sent by the client just before it logs out.</p>
   </message>

<h2>Structs mainly used in messages send by the server</h2>

   <struct name="challenge_defaults">
      Send soon after log-in to set the defaults for game challenges.
      <member name="gametype" type="U8"/>
      <member name="ruleset" type="U8"/>
      <p>The ruleset member is a pure guess, please verify. it could also be after size for example.</p>
      <member name="size" type="U32"/>
      <member name="timesys" type="U32"/>
      <member name="time" type="U32"/>
      <member name="byo_time" type="U32"/>
      <member name="byo_periods" type="U32"/>
      <member name="can_time" type="U32"/>
      <member name="can_stones" type="U32"/>
      <member name="notes" type="STRING"/>
   </struct>

   <struct name="game" class="KGS::Game">
      Basic information about a game. Used in rooms for the gamelist and
      in games to detect when a game is saved, changed type (e.g. R => D)
      etc.

      <member name="channel" type="U16"/>
      <member name="type" type="U8"/>
      <member name="black" type="user"/>
      White
      <member name="white" type="user"/>
      Black
      <member name="owner" type="user"/>
      Owner
      <member name="size" type="U8"/>
      <member name="handicap" type="I8"/>
      &lt; 0 not fully setup
      <member name="komi" type="komi16_2"/>
      <member name="moves" type="I16"/>
      This field reflects either the movenum or the score, sorry, not even guards help, as
      the flags to determine that are _after_ the field. Arg. Divide by two to get the actual
      score (arg²).
      <member name="flags" type="U16"/>
      <member name="observers" type="U32"/>
      <member name="saved" type="flag"/>
      <member name="notes" type="ZSTRING" guard-member="handicap" guard-cond="&lt; 0"/>
   </struct>

   <struct name="room_game">
      A game with the room id prepended.

      <member name="channel" type="U16"/>
      <p>The room channel.</p>
      <member name="game" type="game"/>
   </struct>

   <struct name="room_obs">
      Obsolete.
      
      <member name="name" type="roomname"/>
      <member name="channel" type="U16"/>
      <member name="flags" type="U32"/>
      <member name="users" type="U32"/>
   </struct>

   <struct name="room" class="KGS::Room">
      <member name="channel" type="U16"/>
      <member name="flags" type="U8"/>
      <member name="group" type="U8"/>
      <member name="users" type="U16"/>
      <member name="games" type="U16"/>
      <member name="name" type="STRING"/>
   </struct>

   <struct name="scorevalues" class="KGS::Score">
      <member name="score" type="score32_4"/>
      <member name="territory" type="U32"/>
      <member name="captures" type="U32"/>
      <member name="i3" type="U32"/>
      <member name="f2" type="U32"/>
      <member name="komi" type="komi32_4"/>
      <member name="i4" type="U32"/>
      Apparently the i3, f2, i4 are zero.
   </struct>

   <struct name="game_record" class="KGS::GameRecord">
      <p>A single game record entry, as seen in <ref ref="userinfo"/>.</p>

      <member name="timestamp" type="timestamp"/>
      Time this game was played.
      <member name="type" type="U8"/>
      <member name="handicap" type="U8"/>

      <member name="revision" type="U16"/>
      <p>A revision number in case there are multiple similar games.</p>

      <member name="black" type="user"/>
      <member name="white" type="user"/>
      <member name="owner" type="user"/>

      <member name="komi" type="U16"/>
      <p>0:11 == komi * 2; 12:15 == no idea, always 1-0-0-0?</p>
      <member name="score" type="score16_2"/>
      <member name="size" type="U8"/>
      <p>0:5 == size; 6 no idea; 7 == inprogress</p>
      <member name="flags" type="U8"/>
      <p>No idea. I see many values here.</p>

   </struct>

<h2>Server-generated messages</h2>

   <message type="0001" name="login" src="server">
      <member name="message" type="CONSTANT" value='login successful'/>
      <member name="success" type="CONSTANT" value="1"/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0002" name="login" src="server">
      <member name="message" type="CONSTANT" value='login successful: client version is outdated.'/>
      <member name="success" type="CONSTANT" value="1"/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0003" name="login" src="server">
      <member name="message" type="CONSTANT" value='login failed: client version out of date'/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0004" name="login" src="server">
      <member name="message" type="CONSTANT" value='login failed: wrong password'/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0005" name="login" src="server">
      <member name="message" type="CONSTANT" value='login failed: specified user does not exist'/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0006" name="login" src="server">
      <member name="message" type="CONSTANT" value='login failed: other user of same name already exists'/>

      <member name="user" type="user"/>
      <member name="unknown1" type="U16"/>
      <member name="unknown2" type="U16"/>
   </message>

   <message type="0008" name="userinfo" src="server">
      User info.
      <member name="_unused0" type="flag"/>
      <member name="user" type="user"/>
      <member name="_unused1" type="U64"/>
      <member name="realname" type="realname"/>
      <member name="email" type="email"/>
      <member name="info" type="userinfo"/>
      <member name="homepage" type="url"/>
      <member name="regdate" type="timestamp"/>
      When the user registered (0 == never registered).
      <member name="lastlogin" type="timestamp"/>
      When the user logged in for the last time.
      <!-- maybe more? -->
   </message>

   <message type="0009" name="upd_userinfo_result" src="server">
      <member name="name" type="username"/>
      <member name="message" type="CONSTANT" value='Thanks for registering.'/>
   </message>

   <message type="000a" name="upd_userinfo_result" src="server">
      <member name="name" type="username"/>
      <member name="message" type="CONSTANT" value='The user &quot;%s&quot; has been successfully updated.'/>
   </message>

   <message type="000b" name="upd_userinfo_result" src="server">
      <member name="name" type="username"/>
      <member name="message" type="CONSTANT" value='There is no user &quot;%s&quot;. Update failed.'/>
   </message>

   <message type="0012" name="userinfo_failed" src="server">
      <p>Sent when no userinfo for the requested user could be found(?)</p>
      <member name="name" type="username"/>
   </message>

   <message type="0013" name="msg_chat" src="server">
      <member name="name" type="username"/>
      Name of sender (either yourself (echo) or other)
      <member name="name2" type="username"/>
      Name of recipient.
      <member name="message" type="STRING"/>
   </message>

   <message type="0015" name="stats" src="server">
      <member name="ver_major" type="U16"/>
      <member name="ver_minor" type="U16"/>
      <member name="ver_micro" type="U16"/>
      <member name="boot_time" type="timestamp"/>
      <member name="users_cur" type="U32"/>
      <member name="users_max" type="U32"/>
      <member name="users_lim" type="U32"/>
      <member name="accts_cur" type="U32"/>
      <member name="accts_max" type="U32"/>
      <member name="unknown1" type="U32"/>
      <member name="work_max" type="U32"/>
      <member name="rooms_cur" type="U32"/>
      <member name="rooms_max" type="U32"/>
      <member name="rooms_lim" type="U32"/>
      <member name="games_cur" type="U32"/>
      <member name="games_max" type="U32"/>
      <member name="games_lim" type="U32"/>
      <member name="results_cur" type="U32"/>
      <member name="results_max" type="U32"/>
      <member name="unknown2" type="U32"/>
      <member name="params_cur" type="U32"/>
      <member name="params_max" type="U32"/>
      <member name="bytes_in" type="U64"/>
      <member name="packets_in" type="U64"/>
      <member name="bytes_out" type="U64"/>
      <member name="packets_out" type="U64"/>
   </message>

   <message type="0016" name="idle_warn" src="server">
      <p>idle warning, autologout soon (10 minutes...). Responding with <ref ref="ping"/> usually helps.</p>
   </message>

   <message type="0018" name="login" src="server">
      <member name="message" type="CONSTANT" value='logged out: another client logged in with your username'/>
   </message>

   <message type="001c" name="login" src="server">
      <member name="message" type="CONSTANT" value='logged out: idle for too long'/>
   </message>

   <message type="0020" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, you have too many unfinished games. You cannot turn on your rank. Please finish some of your games, then try again.'/>
   </message>

   <message type="0022" name="login" src="server">
      I was blocked sooo many times for developing this client that it was
      easy to figure out. The KGS admins sure need no extra nazi training
      :(
      <member name="reason" type="STRING"/>
      <member name="result" type="CONSTANT" value='user or ip blocked'/>
   </message>

   <message type="001b" name="timewarning_default" src="server">
      WILD guess
      <member name="channel" type="U16"/>
      <member name="time" type="U16"/>
   </message>

   <message type="001c" name="idle_err" src="server">
      autologout
   </message>

   <message type="001d" name="ping" src="server">
      Sent by the server regularly, but not answering them
      isn't valid. Strange form of keepalive?
   </message>

   <message type="001e" name="usergraph" src="server">
      User graph data.
      <member name="name" type="username"/>
      <member name="data" type="I16" array="yes"/>
      If empty, no graph is available. The unit seems to
      be centi-kyu, with 1 dan == 0, 2 dan == 100, 1 kyu == -100.
      There is probably one entry per day, the newest one last.
   </message>

   <message type="0021" name="userpic" src="server">
      <member name="name" type="username"/>
      Reply to pic_req, contains an image in jpeg format.
      <member name="data" type="DATA"/>
   </message>

   <message type="0025" name="memo_error" src="server">
      <p>Account unknown.</p>
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
      <member name="message" type="CONSTANT" value='memo send failed: account already exists'/>
      <member name="subtype" type="CONSTANT" value='25'/>
   </message>

   <message type="0026" name="memo_error" src="server">
      <p>Just a guess.</p>
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
      <member name="message" type="CONSTANT" value='memo send failed: error 26'/>
      <member name="subtype" type="CONSTANT" value='26'/>
   </message>

   <message type="0027" name="memo_error" src="server">
      <p>User is currently online, please use chat.</p>
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
      <member name="message" type="CONSTANT" value='memo send failed: user is online, use chat'/>
      <member name="subtype" type="CONSTANT" value='27'/>
   </message>

   <message type="0028" name="memo_error" src="server">
      <p>Just a guess.</p>
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
      <member name="message" type="CONSTANT" value='memo send failed: error 28'/>
      <member name="subtype" type="CONSTANT" value='28'/>
   </message>

   <message type="0029" name="memo" src="server">
      <member name="name" type="username"/>
      <member name="time" type="timestamp"/>
      <member name="message" type="ZSTRING"/>
   </message>

   <message type="002a" name="memo_sent" src="server">
      <p>The memo was sent successfully</p>
      <member name="name" type="username"/>
      <member name="cid" type="CLIENTID16"/>
   </message>

   <message type="0100" name="gnotice" src="server">
      global notice, sent to everybody
      <member name="notice" type="STRING"/>
   </message>

   <message type="0202" name="notify_event" src="server">
      # maybe soe notify? Totally unclear.
      # loc 0" type="userinfo, flags etc. loc 1 => gameinfo?, loc 2 => game result (more data)
      <member name="event" type="U32"/>
      <member name="user" type="user"/>
      <member name="gamerecord" type="game_record" guard-member="event" guard-cond="== 2"/>
      <p>Game result record?</p>
      
   </message>

   <message type="030c" name="login_done" src="server">
      <p>Is sent after the initial messages, probably
      to signify the end of the login process.</p>
   </message>

   <message type="0310" name="priv_room" src="server">
      "permission denied" when joining a room
      <member name="name" type="STRING"/>
   </message>

   <message type="0318" name="upd_rooms" src="server">
      <member name="rooms" type="room" array="yes"/>
   </message>

   <message type="0411" name="chal_defaults" src="server">
      <member name="channel" type="U16"/>
      <member name="defaults" type="challenge_defaults"/>
   </message>

   <message type="0412" name="already_playing" src="server">
      Unable to create new game.
      <member name="message" type="CONSTANT" value='Sorry, you are already playing in one game, so you can&apos;t start playing in another.'/>
      <member name="cid" type="CLIENTID16"/>
      <p>The cid of the new_game etc. request.</p>
   </message>

   <message type="0414" name="game_record" src="server">
      The users game record.
      <member name="name" type="username"/>
      <member name="more" type="flag"/>
      <p>Wether more games are available (must be requested manually by
      another <ref reply="req_game_record"/> message with the timestamp set
      to the timestamp of the <em>first</em> game of this packet.</p>
      <member name="games" type="game_record" array="yes"/>
      <p>Game records, from oldest to newest.</p>
   </message>

   <message type="0417" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, your opponent is currently not logged in, so you can&apos;t resume this game.'/>
   </message>

   <message type="0418" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, your opponent is already playing in a game, so you cannot continue this one.'/>
   </message>

   <message type="0419" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, the server is out of boards! Please wait a few minutes and try to start a game again.'/>
   </message>

   <message type="041c" name="upd_game2" src="server">
      Unclear.
      <member name="channel_junk" type="U16"/>
      <member name="game" type="game"/>
   </message>

   <message type="041f" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, the game you tried to load was not correctly saved...probably caused by the server crashing. It cannot be recovered.'/>
   </message>

   <message type="0420" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, user &quot;%s&quot; has left the game you are starting before you could challenge them. You will have to play against somebody else.'/>
   </message>

   <message type="0421" name="error" src="server">
      <member name="message" type="CONSTANT" value='Sorry, this game is a private lesson. You will not be allowed to observe it.'/>
   </message>

   <!-- added recently -->
   <message type="043a" name="add_global_challenges" src="server">
      <p>
         Adds or updates a global challenge (open game list).
      </p>
      <member name="games" type="room_game" array="yes"/>
      <p>The game. The "moves" member contains a small number. Probably garbage.</p>
   </message>

<h3>Room messages</h3>

   <p>Not all room messages are for rooms only, and rooms need to parse
   not only these messages. Orthogonality, what for?</p>

   <message type="4300" name="join_room" src="server">
      <member name="channel" type="U16"/>
      <member name="users" type="user" array="yes"/>
   </message>

   <message type="4301" name="msg_room" src="server">
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
      <member name="message" type="STRING"/>
   </message>

   <message type="4302" name="part_room" src="server">
      <member name="channel" type="U16"/>
      <member name="user" type="user"/>
   </message>

   <message type="4303" name="del_room" src="server">
      <member name="channel" type="U16"/>
   </message>

   <message type="4304" name="upd_games" src="server">
      <member name="channel" type="U16"/>
      <member name="games" type="game" array="yes"/>
   </message>

   <message type="4319" name="desc_room" src="server">
      <member name="channel" type="U16"/>
      <member name="owner" type="username"/>
      <member name="description" type="STRING"/>
   </message>

<h3>Game messages</h3>

   <message type="4400" name="challenge" src="server">
      Unclear.
      <member name="channel" type="U16"/>
      <member name="black" type="user"/>
      <member name="white" type="user"/>
      <member name="gametype" type="U8"/>
      <member name="cid" type="CLIENTID8"/>
      <p>Possibly an id. No idea. Better echo this from the challenge request.</p>
      <member name="rules" type="rules"/>
      <member name="notes" type="STRING"/>
      <p>This field is optional</p>
   </message>

   <message type="4401" name="upd_game" src="server">
      <member name="channel" type="U16"/>
      <member name="game" type="game"/>
   </message>

   <message type="4402" name="del_game" src="server">
      <member name="channel" type="U16"/>
   </message>

   <message type="4403" name="upd_observers" src="server">
      <member name="channel" type="U16"/>
      <member name="users" type="user" array="yes"/>
   </message>

   <message type="4404" name="del_observer" src="server">
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
   </message>

   <message type="4405" name="set_tree" src="server">
      <member name="channel" type="U16"/>
      <member name="tree" type="TREE"/>
   </message>

   <message type="4406" name="upd_tree" src="server">
      <member name="channel" type="U16"/>
      <member name="tree" type="TREE"/>
   </message>

   <message type="4409" name="superko" src="server">
      Superko-warning.
      <member name="channel" type="U16"/>
   </message>

   <message type="440a" name="game_done" src="server">
      <p>Send by the server when one of the players sends a done.</p>
      <member name="channel" type="U16"/>
      <member name="id" type="U32"/>
      <p>An id field to make sure that the client responds to the correct done click.</p>
      <p>The high bit has the "please press done again" warning function, i.e. if set, opponent has changed board.</p>
      <member name="black" type="flag"/>
      <member name="white" type="flag"/>
   </message>

   <message type="440b" name="final_result" src="server">
      <member name="channel" type="U16"/>
      <member name="blackscore" type="scorevalues"/>
      <member name="whitescore" type="scorevalues"/>
   </message>

   <message type="440c" name="out_of_time" src="server">
      <p>Sent when the opponent is out of time and moves, or when the other
      requests <ref reply="userinfo"/>.</p>
      <member name="channel" type="U16"/>
      <member name="player" type="U8"/>
      <p>Colour who ran out of time (lost).</p>
   </message>

   <message type="440e" name="req_undo" src="server">
      <member name="channel" type="U16"/>
   </message>

   <message type="4410" name="resign_game" src="server">
      <member name="channel" type="U16"/>
      <member name="player" type="U8"/>
   </message>

   <message type="4415" name="game_error" src="server">
      <member name="channel" type="U16"/>
      <member name="message" type="CONSTANT" value='Sorry, this is a lecture game. Only authorized players are allowed to make comments.'/>
   </message>

   <message type="441a" name="set_teacher" src="server">
      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
   </message>

   <message type="441d" name="owner_left" src="server">
      <member name="channel" type="U16"/>
      <member name="message" type="CONSTANT" value='Sorry, the owner of this game has left. Nobody will be allowed to edit it until the owner returns.'/>
   </message>

   <message type="441e" name="teacher_left" src="server">
      Unclear.
      <member name="channel" type="U16"/>
   </message>

   <message type="4422" name="allow_user_result" src="server">
      <member name="message" type="CONSTANT" value='User &quot;%s&quot; will now be allowed full access to your game.'/>
      <member name="channel" type="U16"/>
   </message>

   <message type="4424" name="allow_user_result" src="server">
      <member name="message" type="CONSTANT" value='Sorry, user &quot;%s&quot; is a guest and cannot be allowed full access to your game.'/>
      <member name="channel" type="U16"/>
   </message>

   <message type="4425" name="allow_user_result" src="server">
      <member name="message" type="CONSTANT" value='Sorry, user &quot;%s&quot; does not seem to exist and cannot be allowed into your game.'/>
      <member name="channel" type="U16"/>
   </message>

   <message type="4428" name="add_tree" src="server">
      <p>See <ref ref="set_tree"/>. In addition, flags the tree as being
      uploaded completely.</p>
      <member name="channel" type="U16"/>
      <member name="tree" type="TREE"/>
   </message>

   <message type="4429" name="reject_challenge" src="server">
      Reject a challenge by a given user. Not checked.
      <!-- should become a record type somehow... -->

      <member name="channel" type="U16"/>
      <member name="name" type="username"/>
      <member name="gametype" type="U8"/>
      <member name="cid" type="CLIENTID8"/>
      <p>Possibly an id. No idea. Better echo this from the challenge request.</p>
      <member name="rules" type="rules"/>
   </message>

   <message type="442b" name="set_comments" src="server">
      <p>Sent at end of games to set the comments not seen previously.</p>
      <member name="channel" type="U16"/>
      <member name="node" type="U32"/>
      <member name="comments" type="STRING"/>
   </message>

   <message type="442c" name="add_comments" src="server">
      <p>Sent at end of games to add all game commentary.</p>
      <member name="channel" type="U16"/>
      <member name="node" type="U32"/>
      <member name="comments" type="STRING"/>
   </message>

   <message type="442d" name="more_comments" src="server">
      <p>Quite brokenly, the server sends you this to make you ask for more comments.
      Reply with <ref reply="more_comments"/>.</p>
      <member name="channel" type="U16"/>
      <member name="node" type="U32"/>
   </message>

   <message type="442f" name="new_game" src="server">
      <p>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*</p>

      <member name="channel" type="U16"/>
      <p>The newly created game.</p>
      <member name="cid" type="CLIENTID16"/>
      <p>The ID sent to the server in new_game.</p>
   </message>

   <message type="4433" name="req_result" src="server">
       Unclear.
       <member name="channel" type="U16"/>
       # # recv_result(?)
   </message>

   <message type="4434" name="set_quiet" src="server">
      <p>Sets (or clears) the quiet flag on a game.</p>
      <member name="channel" type="U16"/>
      <member name="quiet" type="flag"/>
   </message>

   <message type="4437" name="set_gametime" src="server">
      <p>Sent when joining a running game. Gives the remaining time +
      periods/moves for the players, to correctly initialize the clocks.</p>
      <member name="channel" type="U16"/>
      <member name="black_time" type="time"/>
      <member name="black_moves" type="U16"/>
      <member name="white_time" type="time"/>
      <member name="white_moves" type="U16"/>
   </message>

   <message type="443b" name="del_global_challenge" src="server">
      <p>
         Remove a game from the global challenge list (open game list).
      </p>
      <member name="channel" type="U16"/>
      <p>The game id to remove.</p>
      <member name="game" type="U16"/>
      <p>Probably the same. I suggest to use this id for no good reason.</p>
   </message>
</body>
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