1 APPLICATION LAYER PROTOCOL FOR THE CITADEL SYSTEM
2 (c) 1995-2005 by Art Cancro et. al. All Rights Reserved
8 This is an attempt to document the application layer protocol used by the
9 Citadel system, beginning with version 4.00, which is the first version
10 to implement a client/server paradigm. It is intended as a resource for
11 programmers who intend to develop their own Citadel clients, but it may have
15 IMPORTANT NOTE TO DEVELOPERS!
16 -----------------------------
18 Anyone who wants to add commands or other functionality to this protocol,
19 *please* get in touch so that these efforts can be coordinated. New
20 commands added by other developers can be added to this document, so we
21 don't end up with new server commands from multiple developers which have
22 the same name but perform different functions. If you don't coordinate new
23 developments ahead of time, please at least send in an e-mail documenting
24 what you did, so that your new commands can be added to this document.
26 The coordinator of the Citadel project is Art Cancro
27 <ajc@uncensored.citadel.org>.
30 CONNECTING TO A SERVER
31 ----------------------
33 The protocols used below the application layer are beyond the scope of this
34 document, but we will briefly cover the methodology employed by Citadel.
36 Citadel offers its client protocol using TCP/IP. It does so via a
37 multithreaded server listening on a TCP port. Local connections may also
38 be made using the same protocol using Unix domain sockets.
40 The port number officially assigned to Citadel by the IANA is 504/tcp. Since
41 our application layer assumes a clean, reliable, sequenced connection, the use
42 of UDP would render the server unstable and unusable, so we stick with TCP.
45 GENERAL INFORMATION ABOUT THE SERVER
46 ------------------------------------
48 The server is connection-oriented and stateful: each client requires its own
49 connection to a server process, and when a command is sent, the client must
50 read the response, and then transfer data or change modes if necessary.
52 The application layer is very much like other Internet protocols such as SMTP
53 or NNTP. A client program sends one-line commands to the server, and the
54 server responds with a three-digit numeric result code followed by a message
55 describing what happened. This cycle continues until the end of the
58 Unlike protocols such as FTP, all data transfers occur in-band. This means
59 that the same connection that is used for exchange of client/server
60 messages, will also be used to transfer data back and forth. (FTP opens a
61 separate connection for data transfers.) This keeps protocol administration
62 straightforward, as it can traverse firewalls without any special protocol
63 support on the firewall except for opening the port number.
69 The server will respond to all commands with a 3-digit result code, which
70 will be the first three characters on the line. The rest of the line may
71 contain a human-readable string explaining what happened. (Some client
72 software will display some of these strings to the user.)
74 The first digit is the most important. The following codes are defined for
75 this position: ERROR, OK, MORE_DATA, LISTING_FOLLOWS, and SEND_LISTING.
77 The second and third digits may provide a reason as to why a command
78 succeeded or failed. See ipcdef.h for the available codes.
80 ERROR means the command did not complete.
81 OK means the command executed successfully.
82 MORE_DATA means the command executed partially. Usually this means that
83 another command needs to be executed to complete the operation. For example,
84 sending the USER command to log in a user usually results in a MORE_DATA
85 result code, because the client needs to execute a PASS command to send the
86 password and complete the login.
87 LISTING_FOLLOWS means that after the server response, the server will
88 output a listing of some sort. The client *must* read the listing, whether
89 it wants to or not. The end of the listing is signified by the string
90 "000" on a line by itself.
91 SEND_LISTING is the opposite of LISTING_FOLLOWS. It means that the client
92 should begin sending a listing of some sort. The client *must* send something,
93 even if it is an empty listing. Again, the listing ends with "000" on a line
95 BINARY_FOLLOWS and SEND_BINARY mean that the client must immediately send
96 or receive a block of binary data. The first parameter will always be the
98 ASYNC_MESSAGE_FOLLOWS means that an asynchronous, or unsolicited, message
99 follows. The next line will be one of the above codes, and if a data transfer
100 is involved it must be handled immediately. Note that the client will not
101 receive this type of response unless it indicates to the server that it is
102 capable of handling them; see the writeup of the ASYN command later in this
108 Zero or more parameters may be passed to a command. When more than one
109 parameter is passed to a command, they should be separated by the "|"
112 In this example, we're using the "SETU" command and passing three
113 parameters: 80, 24, and 260.
115 When the server spits out data that has parameters, if more than one
116 parameter is returned, they will be separated by the "|" symbol like
119 In this example, we just executed the "GETU" command, and it returned us
120 an OK result code (the '2' in the 200) and three parameters: 80, 24, and
127 This is a listing of all the commands that a Citadel server can execute.
132 This command does nothing. It takes no arguments and always returns
133 OK. It is intended primarily for testing and development, but it might also
134 be used as a "keep alive" command to prevent the server from timing out, if
135 it's running over a transport that needs this type of thing.
138 ECHO (ECHO something)
140 This command also does nothing. It simply returns OK followed by whatever
146 Terminate the server connection. This command takes no arguments. It
147 returns OK and closes the connection immediately.
152 Log out the user without closing the server connection. It always returns
153 OK even if no user is logged in.
156 USER (send USER name)
158 The first step in logging in a user. This command takes one argument: the
159 name of the user to be logged in. If the user exists, a MORE_DATA return
160 code will be sent, which means the client should execute PASS as the next
161 command. If the user does not exist, ERROR + NO_SUCH_USER is returned.
166 The second step in logging in a user. This command takes one argument: the
167 password for the user we are attempting to log in. If the password doesn't
168 match the correct password for the user we specified for the USER command,
169 ERROR + PASSWORD_REQUIRED is returned. If a USER command has not been
170 executed yet, ERROR + USERNAME_REQUIRED is returned. If a user is already
171 logged in, ERROR + ALREADY_LOGGED_IN is returned. If the password is
172 correct, OK is returned and the user is now logged in... and most of the
173 other server commands can now be executed. Along with OK, the following
174 parameters are returned:
176 0 - The user's name (in case the client wants the right upper/lower casing)
177 1 - The user's current access level
180 4 - Various flags (see citadel.h)
182 6 - Time of last call (UNIX timestamp)
185 NEWU (create NEW User account)
187 This command creates a new user account AND LOGS IT IN. The argument to
188 this command will be the name of the account. No case conversion is done
189 on the name. Note that the new account is installed with a default
190 configuration, and no password, so the client should immediately prompt the
191 user for a password and install it with the SETP command as soon as this
192 command completes. This command returns OK if the account was created and
193 logged in, ERROR + ALREADY_EXISTS if another user already exists with this
194 name, ERROR + NOT_HERE if self-service account creation is disabled,
195 ERROR + MAX_SESSIONS_EXCEEDED if too many users are logged in, ERROR +
196 USERNAME_REQUIRED if a username was not provided, or ERROR + ILELGAL_VALUE
197 if the username provided is invalid. If OK, it will also return the same
198 parameters that PASS returns.
200 Please note that the NEWU command should only be used for self-service
201 user account creation. For administratively creating user accounts, please
202 use the CREU command.
205 SETP (SET new Password)
207 This command sets a new password for the currently logged in user. The
208 argument to this command will be the new password. The command always
209 returns OK, unless the client is not logged in, in which case it will return
210 ERROR + NOT_LOGGED_IN, or if the user is an auto-login user, in which case
211 it will return ERROR + NOT_HERE.
214 CREU (CREate new User account)
216 This command creates a new user account AND DOES NOT LOG IT IN. The first
217 argument to this command will be the name of the account. No case conversion
218 is done on the name. Note that the new account is installed with a default
219 configuration, and no password. The second argument is optional, and will be
220 an initial password for the user. This command returns OK if the account was
221 created, ERROR + HIGHER_ACCESS_REQUIRED if the user is not an Aide, ERROR +
222 USERNAME_REQUIRED if no username was specified, or ERROR + ALREADY_EXISTS if
223 another user already exists with this name.
225 Please note that CREU is intended to be used for activities in which a
226 system administrator is creating user accounts. For self-service user
227 account creation, use the NEWU command.
230 LKRN (List Known Rooms with New messages)
232 List known rooms with new messages. If the client is not logged in, ERROR +
233 NOT_LOGGED_IN is returned. Otherwise, LISTING_FOLLOWS is returned, followed
234 by the room listing. Each line in the listing contains the full name of a
235 room, followed by the '|' symbol, and then a number that may contain the
238 #define QR_PERMANENT 1 /* Room does not purge */
239 #define QR_PRIVATE 4 /* Set for any type of private room */
240 #define QR_PASSWORDED 8 /* Set if there's a password too */
241 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
242 #define QR_DIRECTORY 32 /* Directory room */
243 #define QR_UPLOAD 64 /* Allowed to upload */
244 #define QR_DOWNLOAD 128 /* Allowed to download */
245 #define QR_VISDIR 256 /* Visible directory */
246 #define QR_ANONONLY 512 /* Anonymous-Only room */
247 #define QR_ANON2 1024 /* Anonymous-Option room */
248 #define QR_NETWORK 2048 /* Shared network room */
249 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
250 #define QR_READONLY 8192 /* Aide status required to post */
252 Then it returns another '|' symbol, followed by a second set of bits comprised
255 #define QR2_SYSTEM 1 /* System room; hide by default */
256 #define QR2_SELFLIST 2 /* Self-service mailing list mgmt */
258 Other bits may be defined in the future. The listing terminates, as with
259 all listings, with "000" on a line by itself.
261 Starting with version 4.01 and above, floors are supported. The first
262 argument to LKRN should be the number of the floor to list rooms from. Only
263 rooms from this floor will be listed. If no arguments are passed to LKRN, or
264 if the floor number requested is (-1), rooms on all floors will be listed.
266 The third field displayed on each line is the number of the floor the room
267 is on. The LFLR command should be used to associate floor numbers with
270 The fourth field displayed on each line is a "room listing order." Unless
271 there is a compelling reason not to, clients should sort any received room
272 listings by this value.
274 The fifth field is a special bit bucket containing fields which pertain to
275 room access controls:
277 #define UA_KNOWN 2 /* Known room */
278 #define UA_GOTOALLOWED 4 /* Access will be granted to this room
279 * if the user calls it up by name */
280 #define UA_HASNEWMSGS 8 /* Unread messages exist in room */
281 #define UA_ZAPPED 16 /* Zapped from known rooms list */
283 The sixth field is the user's current view for the room. (See VIEW command)
286 LKRO (List Known Rooms with Old [no new] messages)
288 This follows the same usage and format as LKRN.
291 LZRM (List Zapped RooMs)
293 This follows the same usage and format as LKRN and LKRO.
296 LKRA (List All Known Rooms)
298 Same format. Lists all known rooms, with or without new messages.
301 LRMS (List all accessible RooMS)
303 Again, same format. This command lists all accessible rooms, known and
304 forgotten, with and without new messages. It does not, however, list
305 inaccessible private rooms.
308 LPRM (List all Public RooMs)
310 Again, same format. This command lists all public rooms, and nothing else.
311 Unlike the other list rooms commands, this one can be executed without logging
315 GETU (GET User configuration)
317 This command retrieves the screen dimensions and user options for the
318 currently logged in account. ERROR + NOT_LOGGED_IN will be returned if no
319 user is logged in, of course. Otherwise, OK will be returned, followed by
320 four parameters. The first parameter is the user's screen width, the second
321 parameter is the user's screen height, and the third parameter is a bag of
322 bits with the following meanings:
324 #define US_LASTOLD 16 /* Print last old message with new */
325 #define US_EXPERT 32 /* Experienced user */
326 #define US_UNLISTED 64 /* Unlisted userlog entry */
327 #define US_NOPROMPT 128 /* Don't prompt after each message */
328 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
329 #define US_PAGINATOR 2048 /* Pause after each screen of text */
331 There are other bits, too, but they can't be changed by the user (see below).
334 SETU (SET User configuration)
336 This command does the opposite of SETU: it takes the screen dimensions and
337 user options (which were probably obtained with a GETU command, and perhaps
338 modified by the user) and writes them to the user account. This command
339 should be passed three parameters: the screen width, the screen height, and
340 the option bits (see above). It returns ERROR + NOT_LOGGED_IN if no user is
341 logged in, and ERROR + ILLEGAL_VALUE if the parameters are incorrect.
343 Note that there exist bits here which are not listed in this document. Some
344 are flags that can only be set by Aides or the system administrator. SETU
345 will ignore attempts to toggle these bits. There also may be more user
346 settable bits added at a later date. To maintain later downward compatibility,
347 the following procedure is suggested:
349 1. Execute GETU to read the current flags
350 2. Toggle the bits that we know we can toggle
351 3. Execute SETU to write the flags
353 If we are passed a bit whose meaning we don't know, it's best to leave it
354 alone, and pass it right back to the server. That way we can use an old
355 client on a server that uses an unknown bit without accidentally clearing
356 it every time we set the user's configuration.
361 This command is used to goto a new room. When the user first logs in (login
362 is completed after execution of the PASS command) this command is
363 automatically and silently executed to take the user to the first room in the
364 system (usually called the Lobby).
366 This command can be passed one or two parameters. The first parameter is,
367 of course, the name of the room. Although it is not case sensitive, the
368 full name of the room must be used. Wildcard matching or unique string
369 matching of room names should be the responsibility of the client.
371 Note that the reserved room name "_BASEROOM_" can be passed to the server
372 to cause the goto command to take the user to the first room in the system,
373 traditionally known as the Lobby>. As long as a user is logged in, a
374 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
375 allow client software to return to the base room when it doesn't know
378 There are also two additional reserved room names:
379 "_MAIL_" translates to the system's designated room for e-mail messages.
380 "_BITBUCKET_" goes to whatever room has been chosen for messages
383 The second (and optional) parameter is a password, if one is required for
384 access to the room. This allows for all types of rooms to be accessed via
385 this command: for public rooms, invitation-only rooms to which the user
386 has access, and preferred users only rooms to which the user has access, the
387 room will appear in a room listing. For guess-name rooms, this command
388 will work transparently, adding the room to the user's known room list when
389 it completes. For passworded rooms, access will be denied if the password
390 is not supplied or is incorrect, or the command will complete successfully
391 if the password is correct.
393 The third (and also) optional parameter is a "transient" flag. Normally,
394 when a user enters a private and/or zapped room, the room is added to the
395 user's known rooms list. If the transient flag is set to non-zero, this is
396 called a "transient goto" which causes the user to enter the room without
397 adding the room to the known rooms list.
399 The possible result codes are:
401 OK - The command completed successfully. User is now in the room.
402 (See the list of returned parameters below)
404 ERROR - The command did not complete successfully. Check the second and
405 third positions of the result code to find out what happened:
407 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
408 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
409 password was incorrect.
410 ROOM_NOT_FOUND - The requested room does not exist.
412 The typical procedure for entering a passworded room would be:
414 1. Execute a GOTO command without supplying any password.
415 2. ERROR + PASSWORD_REQUIRED will be returned. The client now knows that
416 the room is passworded, and prompts the user for a password.
417 3. Execute a GOTO command, supplying both the room name and the password.
418 4. If OK is returned, the command is complete. If, however,
419 ERROR + PASSWORD_REQUIRED is still returned, tell the user that the supplied
420 password was incorrect. The user remains in the room he/she was previously
423 When the command succeeds, these parameters are returned:
424 0. The name of the room
425 1. Number of unread messages in this room
426 2. Total number of messages in this room
427 3. Info flag: set to nonzero if the user needs to read this room's info
428 file (see RINF command below)
429 4. Various flags associated with this room. (See LKRN cmd above)
430 5. The highest message number present in this room
431 6. The highest message number the user has read in this room
432 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
433 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
434 a regular Aide (this makes access checks easy).
435 9. The number of new Mail messages the user has (useful for alerting the
436 user to the arrival of new mail during a session)
437 10. The floor number this room resides on
438 11. The *current* "view" for this room (see views.txt for more info)
439 12. The *default* "view" for this room
441 The default view gives the client a hint as to what views the user should
442 be allowed to select. For example, it would be confusing to allow messages
443 in a room intended for calendar items. The server does not enforce these
444 restrictions, though.
447 MSGS (get pointers to MeSsaGeS in this room)
449 This command obtains a listing of all the messages in the current room
450 which the client may request. This command may be passed a single parameter:
451 either "all", "old", or "new" to request all messages, only old messages, or
452 new messages. Or it may be passed two parameters: "last" plus a number, in
453 which case that many message pointers will be returned, or "first" plus a
454 number, for the corresponding effect. If no parameters are specified, "all"
457 In Citadel 5.00 and above, the client may also specify "gt" plus a number,
458 to list all messages in the current room with a message number greater than
461 The third argument, valid only in Citadel 5.60 and above, may be either
462 0 or 1. If it is 1, this command behaves differently: before a listing is
463 returned, the client must transmit a list of fields to search for. The field
464 headers are listed below in the writeup for the "MSG0" command.
466 This command can return three possible results. ERROR + NOT_LOGGED_IN will
467 be returned if no user is currently logged in. Otherwise, LISTING_FOLLOWS
468 will be returned, and the listing will consist of zero or more message
469 numbers, one per line. The listing ends, as always, with the string "000"
470 alone on a line by itself. The listed message numbers can be used to request
471 messages from the system. If "search mode" is being used, the server will
472 return START_CHAT_MODE, and the client is expected to transmit the search
473 criteria, and then read the message list.
475 Since this is somewhat complex, here are some examples:
477 Example 1: Read all new messages
480 Server: 100 Message list...
486 Example 2: Read the last five messages
489 Server: 100 Message list...
497 Example 3: Read all messages written by "IGnatius T Foobar"
500 Server: 800 Send template then receive message list
501 Client: from|IGnatius T Foobar
515 Note that in "search mode" the client may specify any number of search
516 criteria. These criteria are applied with an AND logic.
519 MSG0 (read MeSsaGe, mode 0)
521 This is a command used to read the text of a message. "Mode 0" implies that
522 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
523 messages in more robust formats. This command should be passed two arguments.
524 The first is the message number of the message being requested. The second
525 argument specifies whether the client wants headers and/or message body:
529 3 = Headers only, with MIME information suppressed (this runs faster)
531 If the request is denied, ERROR + NOT_LOGGED_IN or ERROR + MESSAGE_NOT_FOUND
532 will be returned. Otherwise, LISTING_FOLLOWS will be returned, followed by
533 the contents of the message. The following fields may be sent:
535 type= Formatting type. The currently defined types are:
536 0 = "traditional" Citadel formatting. This means that newlines should be
537 treated as spaces UNLESS the first character on the next line is a space. In
538 other words, only indented lines should generate a newline on the user's screen
539 when the message is being displayed. This allows a message to be formatted to
540 the reader's screen width. It also allows the use of proportional fonts.
541 1 = a simple fixed-format message. The message should be displayed to
542 the user's screen as is, preferably in a fixed-width font that will fit 80
544 4 = MIME format message. The message text is expected to contain a header
545 with the "Content-type:" directive (and possibly others).
547 msgn= The message ID of this message on the system it originated on.
548 path= An e-mailable path back to the user who wrote the message.
550 time= The date and time of the message, in Unix format (the number of
551 seconds since midnight on January 1, 1970, GMT).
553 from= The name of the author of the message.
554 rcpt= If the message is a private e-mail, this is the recipient.
555 room= The name of the room the message originated in.
556 node= The short node name of the system this message originated on.
557 hnod= The long node name of the system this message originated on.
558 zaps= The id/node of a message which this one zaps (supersedes).
560 part= Information about a MIME part embedded in this message.
561 pref= Information about a multipart MIME prefix such as "multipart/mixed"
562 or "multipart/alternative". This will be output immediately prior
563 to the various "part=" lines which make up the multipart section.
564 suff= Information about a multipart MIME suffix. This will be output
565 immediately following the various "part=" lines which make up the
568 text Note that there is no "=" after the word "text". This string
569 signifies that the message text begins on the next line.
572 WHOK (WHO Knows room)
574 This command is available only to Aides. ERROR + HIGHER_ACCESS_REQUIRED
575 will be returned if the user is not an Aide. Otherwise, it returns
576 LISTING_FOLLOWS and then lists, one user per line, every user who has
577 access to the current room.
580 INFO (get server INFO)
582 This command will *always* return LISTING_FOLLOWS and then print out a
583 listing of zero or more strings. Client software should be written to expect
584 anywhere from a null listing to an infinite number of lines, to allow later
585 backward compatibility. The current implementation defines the following
586 parts of the listing:
588 Line 1 - Your unique session ID on the server
589 Line 2 - The node name of the Citadel server
590 Line 3 - Human-readable node name of the Citadel server
591 Line 4 - The fully-qualified domain name (FQDN) of the server
592 Line 5 - The name of the server software, i.e. "Citadel 4.00"
593 Line 6 - (The revision level of the server code) * 100
594 Line 7 - The geographical location of the site (city and state if in the US)
595 Line 8 - The name of the system administrator
596 Line 9 - A number identifying the server type (see below)
597 Line 10 - The text of the system's paginator prompt
598 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
599 Line 12 - Paging level. 0 if the system only supports inline paging,
600 1 if the system supports "extended" paging (check-only and
601 multiline modes). See the SEXP command for further information.
602 Line 13 - The "nonce" for this session, for support of APOP-style
603 authentication. If this field is present, clients may authenticate
605 Line 14 - Set to nonzero if this server supports the QNOP command.
606 Line 15 - Set to nonzero if this server is capable of connecting to a
607 directory service using LDAP.
609 *** NOTE! *** The "server type" code is intended to promote global
610 compatibility in a scenario in which developers have added proprietary
611 features to their servers or clients. We are attempting to avoid a future
612 situation in which users need to keep different client software around for
613 each Citadel they use. *Please*, if you are a developer and plan to add
614 proprietary features:
616 -> Your client programs should still be able to utilize servers other than
618 -> Clients other than your own should still be able to utilize your server,
619 even if your proprietary extensions aren't supported.
620 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
621 server type code, which can be assigned to your server program.
622 -> If you document what you did in detail, perhaps it can be added to a
623 future release of the Citadel program, so everyone can enjoy it. Better
624 yet, just work with the Citadel development team on the main source tree.
626 If everyone follows this scheme, we can avoid a chaotic situation with lots
627 of confusion about which client program works with which server, etc. Client
628 software can simply check the server type (and perhaps the revision level)
629 to determine ahead of time what commands may be utilized.
631 Please refer to "developers.txt" for information on what codes belong to whom.
635 RDIR (Read room DIRectory)
637 Use this command to read the directory of a directory room. ERROR + NOT_HERE
638 will be returned if the room has no directory, ERROR + HIGHER_ACCESS_REQUIRED
639 will be returned if the room's directory is not visible and the user does not
640 have Aide or Room Aide privileges, ERROR + NOT_LOGGED_IN will be returned if
641 the user is not logged in; otherwise LISTING_FOLLOWS will be returned,
642 followed by the room's directory. Each line of the directory listing will
643 contain three fields: a filename, the length of the file, and a description.
645 The server message contained on the same line with LISTING_FOLLOWS will
646 contain the name of the system and the name of the directory, such as:
648 uncensored.citadel.org|/usr/local/citadel/files/my_room_directory
651 SLRP (Set Last-message-Read Pointer)
653 This command marks all messages in the current room as read (seen) up to and
654 including the specified number. Its sole parameter is the number of the last
655 message that has been read. This allows the pointer to be set at any
656 arbitrary point in the room. Optionally, the parameter "highest" may be used
657 instead of a message number, to set the pointer to the number of the highest
658 message in the room, effectively marking all messages in the room as having
659 been read (ala the Citadel <G>oto command).
661 The command will return OK if the pointer was set, or ERROR + NOT_LOGGED_IN
662 if the user is not logged in. If OK is returned, it will be followed by a
663 single argument containing the message number the last-read-pointer was set to.
666 INVT (INViTe a user to a room)
668 This command may only be executed by Aides, or by the room aide for the
669 current room. It is used primarily to add users to invitation-only rooms,
670 but it may also be used in other types of private rooms as well. Its sole
671 parameter is the name of the user to invite.
673 The command will return OK if the operation succeeded. ERROR + NO_SUCH_USER
674 will be returned if the user does not exist, ERROR + HIGHER_ACCESS_REQUIRED
675 will be returned if the operation would have been possible if the user had
676 higher access, and ERROR + NOT_HERE may be returned if the room is not a
680 KICK (KICK a user out of a room)
682 This is the opposite of INVT: it is used to kick a user out of a private
683 room. It can also be used to kick a user out of a public room, but the
684 effect will only be the same as if the user <Z>apped the room - a non-stupid
685 user can simply un-zap the room to get back in.
688 GETR (GET Room attributes)
690 This command is used for editing the various attributes associated with a
691 room. A typical "edit room" command would work like this:
692 1. Use the GETR command to get the current attributes
693 2. Change some of them around
694 3. Use SETR (see below) to save the changes
695 4. Possibly also change the room aide using the GETA and SETA commands
697 GETR takes no arguments. It will only return OK if the SETR command will
698 also return OK. This allows client software to tell the user that he/she
699 can't edit the room *before* going through the trouble of actually doing the
700 editing. Possible return codes are:
702 ERROR+NOT_LOGGED_IN - No user is logged in.
703 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
704 and the room aide associated with the current room, can access this command.
705 OK - Command succeeded. Parameters are returned.
707 If OK is returned, the following parameters will be returned as well:
709 0. The name of the room
710 1. The room's password (if it's a passworded room)
711 2. The name of the room's directory (if it's a directory room)
712 3. Various flags (bits) associated with the room (see LKRN cmd above)
713 4. The floor number on which the room resides
714 5. The room listing order
715 6. The default view for the room (see views.txt)
716 7. A second set of flags (bits) associated with the room
719 SETR (SET Room attributes)
721 This command sets various attributes associated with the current room. It
722 should be passed the following arguments:
724 0. The name of the room
725 1. The room's password (if it's a passworded room)
726 2. The name of the room's directory (if it's a directory room)
727 3. Various flags (bits) associated with the room (see LKRN cmd above)
728 4. "Bump" flag (see below)
729 5. The floor number on which the room should reside
730 6. The room listing order
731 7. The default view for the room (see views.txt)
732 8. A second set of flags (bits) associated with the room
734 *Important: You should always use GETR to retrieve the current attributes of
735 the room, then change what you want to change, and then use SETR to write it
736 all back. This is particularly important with respect to the flags: if a
737 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
738 only toggle the bits you want to toggle. This will allow for upward
741 The _BASEROOM_, user's Mail> and Aide> rooms can only be partially edited.
742 Any changes which cannot be made will be silently ignored.
744 If the room is a private room, you have the option of causing all users who
745 currently have access, to forget the room. If you want to do this, set the
746 "bump" flag to 1, otherwise set it to 0.
751 This command is used to get the name of the Room Aide for the current room.
752 It will return ERROR + NOT_LOGGED_IN if no user is logged in, or OK if the
753 command succeeded. Along with OK there will be returned one parameter: the
754 name of the Room Aide. A conforming server must guarantee that the user is
760 The opposite of GETA, used to set the Room Aide for the current room. One
761 parameter should be passed, which is the name of the user who is to be the
762 new Room Aide. Under Citadel, this command may only be executed by Aides
763 and by the *current* Room Aide for the room. Return codes possible are:
764 ERROR + NOT_LOGGED_IN (Not logged in.)
765 ERROR + HIGHER_ACCESS_REQUIRED (Higher access required.)
766 ERROR + NOT_HERE (Room cannot be edited.)
767 OK (Command succeeded.)
770 ENT0 (ENTer message, mode 0)
772 This command is used to enter messages into the system. It accepts four
775 0 - Post flag. This should be set to 1 to post a message. If it is
776 set to 0, the server only returns OK or ERROR (plus any flags describing
777 the error) without reading in a message. Client software should, in fact,
778 perform this operation at the beginning of an "enter message" command
779 *before* starting up its editor, so the user does not end up typing a message
780 in vain that will not be permitted to be saved. If it is set to 2, the
781 server will accept an "apparent" post name if the user is privileged enough.
782 This post name is arg 5.
783 1 - Recipient. This argument is utilized only for private mail messages.
784 It is ignored for public messages. It contains, of course, the name of the
785 recipient of the message.
786 2 - Anonymous flag. This argument is ignored unless the room allows
787 anonymous messages. In such rooms, this flag may be set to 1 to flag a
788 message as anonymous, otherwise 0 for a normal message.
789 3 - Format type. Any valid Citadel format type may be used (this will
790 typically be 0; see the MSG0 command above).
791 4 - Subject. If present, this argument will be used as the subject of
793 5 - Post name. When postflag is 2, this is the name you are posting as.
794 This is an Aide only command.
795 6 - Do Confirmation. NOTE: this changes the protocol semantics! When
796 you set this to nonzero, ENT0 will reply with a confirmation message after
797 you submit the message text. The reply code for the ENT0 command will be
798 START_CHAT_MODE instead of SEND_LISTING.
800 Possible result codes:
801 OK - The request is valid. (Client did not set the "post" flag, so the
802 server will not read in message text.) If the message is an e-mail with
803 a recipient, the text that follows the OK code will contain the exact name
804 to which mail is being sent. The client can display this to the user. The
805 implication here is that the name that the server returns will contain the
806 correct upper and lower case characters. In addition, if the recipient is
807 having his/her mail forwarded, the forwarding address will be returned.
808 SEND_LISTING - The request is valid. The client should now transmit
809 the text of the message (ending with a 000 on a line by itself, as usual).
810 START_CHAT_MODE - The request is valid. The client should now transmit
811 the text of the message, ending with a 000 on a line by itself. After
812 transmitting the 000 terminator, the client MUST read in the confirmation
813 from the server, which will also end with 000 on a line by itself. The format
814 of the confirmation appears below.
815 ERROR + NOT_LOGGED_IN - Not logged in.
816 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
817 explanation follows, worded in a form that can be displayed to the user.
818 ERROR + NO_SUCH_USER - The specified recipient does not exist.
820 The format of the confirmation message, if requested, is as follows:
821 Line 1: The new message number on the server for the message. It will be
822 positive for a real message number, or negative to denote
823 that an error occurred. If an error occurred, the message was
825 Line 2: A human-readable confirmation or error message.
826 Line 3: The resulting Exclusive UID of the message, if present.
827 (More may be added to this in the future, so do not assume that there will
828 only be these lines output. Keep reading until 000 is received.)
831 RINF (read Room INFormation file)
833 Each room has associated with it a text file containing a description of
834 the room, perhaps containing its intended purpose or other important
835 information. The info file for the Lobby> (the system's base room) is
836 often used as a repository for system bulletins and the like.
838 This command, which accepts no arguments, is simply used to read the info
839 file for the current room. It will return LISTING_FOLLOWS followed by
840 the text of the message (always in format type 0) if the request can be
841 honored, or ERROR if no info file exists for the current room (which is
842 often the case). Other error description codes may accompany this result.
844 When should this command be used? This is, of course, up to the discretion
845 of client software authors, but in Citadel it is executed in two situations:
846 the first time the user ever enters a room; and whenever the contents of the
847 file change. The latter can be determined from the result of a GOTO command,
848 which will tell the client whether the file needs to be read (see GOTO above).
851 DELE (DELEte a message)
853 Delete a message from the current room. The one argument that should be
854 passed to this command is the message number of the message to be deleted.
855 The return value will be OK if the message was deleted, or an ERROR code.
856 If the delete is successful, the message's reference count is decremented, and
857 if the reference count reaches zero, the message is removed from the message
861 MOVE (MOVE or copy a message to a different room)
863 Move or copy a message to a different room. This command expects to be
864 passed three arguments:
865 0: the message number of the message to be moved or copied.
866 1: the name of the target room.
867 2: flag: 0 to move the message, 1 to copy it without deleting from the
870 This command never creates or deletes copies of a message; it merely moves
871 around links. When a message is moved, its reference count remains the same.
872 When a message is copied, its reference count is incremented.
875 KILL (KILL current room)
877 This command deletes the current room. It accepts a single argument, which
878 should be nonzero to actually delete the room, or zero to merely check
879 whether the room can be deleted.
881 Once the room is deleted, the current room is undefined. It is suggested
882 that client software immediately GOTO another room (usually _BASEROOM_)
883 after this command completes.
885 Possible return codes:
887 OK - room has been deleted (or, if checking only, request is valid).
888 ERROR+NOT_LOGGED_IN - no user is logged in.
889 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
890 ERROR+NOT_HERE - this room can not be deleted.
893 CRE8 (CRE[ate] a new room)
895 This command is used to create a new room. Like some of the other
896 commands, it provides a mechanism to first check to see if a room can be
897 created before actually executing the command. CRE8 accepts the following
900 0 - Create flag. Set this to 1 to actually create the room. If it is
901 set to 0, the server merely checks that there is a free slot in which to
902 create a new room, and that the user has enough access to create a room. It
903 returns OK if the client should go ahead and prompt the user for more info,
904 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
905 1 - Name for new room.
906 2 - Access type for new room:
908 1 - Private; can be entered by guessing the room's name
909 2 - Private; can be entered by knowing the name *and* password
910 3 - Private; invitation only (sometimes called "exclusive")
911 4 - Personal (mailbox for this user only)
912 3 - Password for new room (if it is a type 2 room)
913 4 - Floor number on which the room should reside (optional)
914 5 - Set to 1 to avoid automatically gaining access to the created room.
915 6 - The default "view" for the room.
917 If the create flag is set to 1, the room is created (unless something
918 went wrong and an ERROR return is sent), and the server returns OK, but
919 the session is **not** automatically sent to that room. The client still
920 must perform a GOTO command to go to the new room.
923 FORG (FORGet the current room)
925 This command is used to forget (zap) the current room. For those not
926 familiar with Citadel, this terminology refers to removing the room from
927 a user's own known rooms list, *not* removing the room itself. After a
928 room is forgotten, it no longer shows up in the user's known room list,
929 but it will exist in the user's forgotten room list, and will return to the
930 known room list if the user goes to the room (in Citadel, this is
931 accomplished by explicitly typing the room's name in a <.G>oto command).
933 The command takes no arguments. If the command cannot execute for any
934 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
935 be returned as they apply.
937 If the command succeeds, OK will be returned. At this point, the current
938 room is **undefined**, and the client software is responsible for taking
939 the user to another room before executing any other room commands (usually
940 this will be _BASEROOM_ since it is always there).
943 MESG (read system MESsaGe)
945 This command is used to display system messages and/or help files. The
946 single argument it accepts is the name of the file to display. IT IS CASE
947 SENSITIVE. Citadel looks for these files first in the "messages"
948 subdirectory and then in the "help" subdirectory.
950 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
951 to the file being displayed. Then the message is printed, in format type 0
952 (see MSG0 command for more information on this). If the file is not found,
955 There are some "well known" names of system messages which client software
956 may expect most servers to carry:
958 hello - Welcome message, to be displayed before the user logs in.
959 changepw - To be displayed whenever the user is prompted for a new
960 password. Warns about picking guessable passwords and such.
961 register - Should be displayed prior to the user entering registration.
962 Warnings about not getting access if not registered, etc.
963 help - Main system help file.
964 goodbye - System logoff banner; display when user logs off.
965 roomaccess - Information about how public rooms and different types of
966 private rooms function with regards to access.
967 unlisted - Tells users not to choose to be unlisted unless they're
968 really paranoid, and warns that aides can still see
969 unlisted userlog entries.
971 Citadel provides these for the Citadel Unix text client. They are
972 probably not very useful for other clients:
974 mainmenu - Main menu (when in idiot mode).
979 saveopt - Options to save a message, abort, etc.
980 entermsg - Displayed just before a message is entered, when in
984 GNUR (Get Next Unvalidated User)
986 This command shows the name of a user that needs to be validated. If there
987 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
988 along with the name of the first unvalidated user the server finds. All of
989 the usual ERROR codes may be returned as well (for example, if the user is
990 not an Aide and cannot validate users).
992 A typical "Validate New Users" command would keep executing this command,
993 and then validating each user it returns, until it returns OK when all new
994 users have been validated.
997 GREG (Get REGistration for user)
999 This command retrieves the registration info for a user, whose name is the
1000 command's sole argument. All the usual error messages can be returned. If
1001 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
1002 (retrieved from the userlog, with the right upper and lower case etc.) The
1003 contents of the listing contains one field per line, followed by the usual
1004 000 on the last line.
1006 The following lines are defined. Others WILL be added in the futre, so all
1007 software should be written to read the lines it knows about and then ignore
1008 all remaining lines:
1013 Line 4: Street address or PO Box
1014 Line 5: City/town/village/etc.
1015 Line 6: State/province/etc.
1017 Line 8: Telephone number
1018 Line 9: Access level
1019 Line 10: Internet e-mail address
1022 Users without Aide privileges may retrieve their own registration using
1023 this command. This can be accomplished either by passing the user's own
1024 name as the argument, or the string "_SELF_". The command will always
1025 succeed when used in this manner, unless no user is logged in.
1028 VALI (VALIdate user)
1030 This command is used to validate users. Obviously, it can only be executed
1031 by users with Aide level access. It should be passed two parameters: the
1032 name of the user to validate, and the desired access level
1034 If the command succeeds, OK is returned. The user's access level is changed
1035 and the "need validation" bit is cleared. If the command fails for any
1036 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
1040 EINF (Enter INFo file for room)
1042 Transmit the info file for the current room with this command. EINF uses
1043 a boolean flag (1 or 0 as the first and only argument to the command) to
1044 determine whether the client actually wishes to transmit a new info file, or
1045 is merely checking to see if it has permission to do so.
1047 If the command cannot succeed, it returns ERROR.
1048 If the client is only checking for permission, and permission will be
1049 granted, OK is returned.
1050 If the client wishes to transmit the new info file, SEND_LISTING is
1051 returned, and the client should transmit the text of the info file, ended
1052 by the usual 000 on a line by itself.
1057 This is a simple user listing. It always succeeds, returning
1058 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
1059 fields on each line are as follows:
1064 4. Date/time of last login (Unix format)
1067 7. Password (listed only if the user requesting the list is an Aide)
1069 Unlisted entries will also be listed to Aides logged into the server, but
1070 not to ordinary users.
1072 The LIST command accepts an optional single argument, which is a simple,
1073 case-insensitive search string. If this argument is present, only usernames
1074 in which the search string is present will be returned. It is a simple
1075 substring search, not a regular expression search. If this string is empty
1076 or not present, all users will be returned.
1079 REGI (send REGIstration)
1081 Clients will use this command to transmit a user's registration info. If
1082 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
1083 SEND_LISTING is returned, and the server will expect the following information
1084 (terminated by 000 on a line by itself):
1087 Line 2: Street address or PO Box
1088 Line 3: City/town/village/etc.
1089 Line 4: State/province/etc.
1091 Line 6: Telephone number
1092 Line 7: e-mail address
1096 CHEK (CHEcK various things)
1098 When logging in, there are various things that need to be checked. This
1099 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
1100 it returns OK and the following parameters:
1102 0: Number of new private messages in Mail>
1103 1: Nonzero if the user needs to register
1104 2: (Relevant to Aides only) Nonzero if new users require validation
1105 3: The user's preferred Internet e-mail address
1108 DELF (DELete a File)
1110 This command deletes a file from the room's directory, if there is one. The
1111 name of the file to delete is the only parameter to be supplied. Wildcards
1112 are not acceptable, and any slashes in the filename will be converted to
1113 underscores, to prevent unauthorized access to neighboring directories. The
1114 possible return codes are:
1116 OK - Command succeeded. The file was deleted.
1117 ERROR+NOT_LOGGED_IN - Not logged in.
1118 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1119 ERROR+NOT_HERE - There is no directory in this room.
1120 ERROR+FILE_NOT_FOUND - Requested file was not found.
1125 This command is similar to DELF, except that it moves a file (and its
1126 associated file description) to another room. It should be passed two
1127 parameters: the name of the file to move, and the name of the room to move
1128 the file to. All of the same return codes as DELF may be returned, and also
1129 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1130 does not exist. ERROR+NOT_HERE could also mean that the target room does
1131 not have a directory.
1134 NETF (NETwork send a File)
1136 This command is similar to MOVF, except that it attempts to send a file over
1137 the network to another system. It should be passed two parameters: the name
1138 of the file to send, and the node name of the system to send it to. All of
1139 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1140 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1143 The name of the originating room will be sent along with the file. Most
1144 implementations will look for a room with the same name at the receiving end
1145 and attempt to place the file there, otherwise it goes into a bit bucket room
1146 for miscellaneous files. This is, however, beyond the scope of this document;
1147 see elsewhere for more details.
1150 RWHO (Read WHO's online)
1152 Displays a list of all users connected to the server. No error codes are
1153 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1154 lines containing the following three fields:
1156 0 - Session ID. Citadel fills this with the pid of a server program.
1158 2 - The name of the room the user is currently in. This field might not
1159 be displayed (for example, if the user is in a private room) or it might
1160 contain other information (such as the name of a file the user is
1162 3 - (server v4.03 and above) The name of the host the client is connecting
1163 from, or "localhost" if the client is local.
1164 4 - (server v4.04 and above) Description of the client software being used
1165 5 - The last time, locally to the server, that a command was received from
1166 this client (Note: NOOP's don't count)
1167 6 - The last command received from a client. (NOOP's don't count)
1168 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1169 (posting) and . (idle).
1170 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1171 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1172 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1173 11 - Nonzero if the session is a logged-in user, zero otherwise.
1175 The listing is terminated, as always, with the string "000" on a line by
1179 OPEN (OPEN a file for download)
1181 This command is used to open a file for downloading. Only one download
1182 file may be open at a time. The only argument to this command is the name
1183 of the file to be opened. The user should already be in the room where the
1184 file resides. Possible return codes are:
1187 ERROR+NOT_HERE (no directory in this room)
1188 ERROR+FILE_NOT_FOUND (could not open the file)
1192 If the file is successfully opened, OK will be returned, along with the
1193 size (in bytes) of the file, the time of last modification (if applicable),
1194 the filename (if known), and the MIME type of the file (if known).
1197 CLOS (CLOSe the download file)
1199 This command is used to close the download file. It returns OK if the
1200 file was successfully closed, or ERROR if there wasn't any file open in the
1204 READ (READ from the download file)
1206 Two arguments are passed to this command. The first is the starting position
1207 in the download file, and the second is the total number of bytes to be
1208 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1209 along with the number of bytes to follow. Then, immediately following the
1210 newline, will be that many bytes of binary data. The client *must* read
1211 exactly that number of bytes, otherwise the client and server will get out
1214 If the operation cannot be performed, any of the usual error codes will be
1218 UOPN (OPeN a file for Uploading)
1220 This command is similar to OPEN, except that this one is used when the
1221 client wishes to upload a file to the server. The first argument is the name
1222 of the file to create, and the second argument is a one-line comment
1223 describing the contents of the file. Only one upload file may be open at a
1224 time. Possible return codes are:
1227 ERROR+NOT_HERE (no directory in this room)
1228 ERROR+FILE_NOT_FOUND (a name must be specified)
1229 ERROR (miscellaneous errors)
1230 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1233 If OK is returned, the command has succeeded and writes may be performed.
1236 UCLS (CLoSe the Upload file)
1238 Close the file opened with UOPN. An argument of "1" should be passed to
1239 this command to close and save the file; otherwise, the transfer will be
1240 considered aborted and the file will be deleted. This command returns OK
1241 if the operation succeeded or ERROR if it did not.
1244 WRIT (WRITe to the upload file)
1246 If an upload file is open, this command may be used to write to it. The
1247 argument passed to this command is the number of bytes the client wishes to
1248 transmit. An ERROR code will be returned if the operation cannot be
1251 If the operation can be performed, SEND_BINARY will be returned, followed
1252 by the number of bytes the server is expecting. The client must then transmit
1253 exactly that number of bytes. Note that in the current implementation, the
1254 number of bytes the server is expecting will always be the number of bytes
1255 the client requested to transmit, but the client software should never assume
1256 that this will always happen, in case changes are made later.
1259 QUSR (Query for a USeR)
1261 This command is used to check to see if a particular user exists. The only
1262 argument to this command is the name of the user being searched for. If
1263 the user exists, OK is returned, along with the name of the user in the userlog
1264 (so the client software can learn the correct upper/lower casing of the name
1265 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1266 No login or current room is required to utilize this command.
1269 OIMG (Open an IMaGe file)
1271 Open an image (graphics) file for downloading. Once opened, the file can be
1272 read as if it were a download file. This implies that an image and a download
1273 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1275 All images will be in GIF (Graphics Interchange Format). In the case of
1276 Citadel, the server will convert the supplied filename to all lower case,
1277 append the characters ".gif" to the filename, and look for it in the "images"
1278 subdirectory. As with the MESG command, there are several "well known"
1279 images which are likely to exist on most servers:
1281 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1282 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1283 background - Background image (usually tiled) for graphical clients
1285 The following "special" image names are defined in Citadel server version
1288 _userpic_ - Picture of a user (send the username as the second argument)
1289 _floorpic_ - A graphical floor label (send the floor number as the second
1290 argument). Clients which request a floor picture will display
1291 the picture *instead* of the floor name.
1292 _roompic_ - A graphic associated with the *current* room. Clients which
1293 request a room picture will display the picture in *addition*
1294 to the room name (i.e. it's used for a room banner, as
1295 opposed to the floor picture's use in a floor listing).
1298 NETP (authenticate as network session with connection NET Password)
1300 This command is used by client software to identify itself as a transport
1301 session for Citadel site-to-site networking. It should be called with
1302 two arguments: the node name of the calling system, and the "shared secret"
1303 password for that connection. If the authentication succeeds, NETP will
1304 return OK, otherwise, it returns ERROR.
1307 NSYN (Network SYNchronize room)
1309 This command can be used to synchronize the contents of a room on the
1310 network. It is only usable by Aides. It accepts one argument: the name of
1311 a network node (which must be a valid one).
1313 When NSYN is run, the *entire* contents of the current room will be spooled
1314 to the specified node, without regard to whether any of the messages have
1315 already undergone network processing. It is up to the receiving node to
1316 check for duplicates (the Citadel networker does handle this) and avoid
1319 The command returns OK upon success or ERROR if the user is not an Aide.
1322 NUOP (Network Upload OPen file)
1324 Open a network spool file for uploading. The client must have already
1325 identified itself as a network session using the NETP command. If the command
1326 returns OK, the client may begin transmitting IGnet/Open spool data using
1327 a series of WRIT commands. When a UCLS command is issued, the spooled data
1328 is entered into the server if the argument to UCLS is 1 or discarded if the
1329 argument to UCLS is 0. If the client has not authenticated itself with a
1330 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1333 NDOP (Network Download OPen file)
1335 Open a network spool file for downloading. The client must have already
1336 identified itself as a network session using the NETP command. If the command
1337 returns OK, the client may begin receiving IGnet/Open spool data using
1338 a series of READ commands. When a CLOS command is issued, the spooled data
1339 is deleted from the server and may not be read again. If the client has not
1340 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1344 LFLR (List all known FLooRs)
1346 On systems supporting floors, this command lists all known floors. The
1347 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1348 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1349 the available floors, each line consisting of three fields:
1351 1. The floor number associated with the floor
1352 2. The name of the floor
1353 3. Reference count (number of rooms on this floor)
1356 CFLR (Create a new FLooR)
1358 This command is used to create a new floor. It should be passed two
1359 arguments: the name of the new floor to be created, and a 1 or 0 depending
1360 on whether the client is actually creating a floor or merely checking to
1361 see if it has permission to create the floor. The user must be logged in
1362 and have Aide privileges to create a floor.
1364 If the command succeeds, it will return OK followed by the floor number
1365 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1366 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1367 followed by a description of why the command failed.
1372 This command is used to delete a floor. It should be passed two
1373 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1374 on whether the client is actually deleting the floor or merely checking to
1375 see if it has permission to delete the floor. The user must be logged in
1376 and have Aide privileges to delete a floor.
1378 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1379 they must be either deleted or moved to different floors first. This implies
1380 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1381 Aide> all reside on the Main Floor and cannot be deleted.
1383 If the command succeeds, it will return OK. Otherwise it will return
1384 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1385 followed by a description of why the command failed.
1390 Edit the parameters of a floor. The client may pass one or more parameters
1393 1. The number of the floor to be edited
1394 2. The desired new name
1396 More parameters may be added in the future. Any parameters not passed to
1397 the server will remain unchanged. A minimal command would be EFLR and a
1398 floor number -- which would do nothing. EFLR plus the floor number plus a
1399 floor name would change the floor's name.
1401 If the command succeeds, it will return OK. Otherwise it will return
1402 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1405 IDEN (IDENtify the client software)
1407 The client software has the option to identify itself to the server.
1408 Currently, the server does nothing with this information except to write
1409 it to the syslog to satisfy the system administrator's curiosity. Other
1410 uses might become apparent in the future.
1412 The IDEN command should contain five fields: a developer ID number (same as
1413 the server developer ID numbers in the INFO command -- please obtain one if
1414 you are a new developer), a client ID number (which does not have to be
1415 globally unique - only unique within the domain of the developer number),
1416 a version number, a free-form text string describing the client, and the name
1417 of the host the user is located at.
1419 It is up to the server to determine whether to accept the host name or to
1420 use the host name it has detected itself. Generally, if the client is
1421 running on a trusted host (either localhost or a well-known publically
1422 accessible client) it should use the host name transmitted by IDEN,
1423 otherwise it should use the host name it has detected itself.
1425 IDEN always returns OK, but since that's the only way it ever returns
1426 there's no point in checking the result code.
1429 IPGM (identify as an Internal ProGraM)
1431 IPGM is a low-level command that should not be used by normal user clients.
1432 It is used for various utilities to communicate with the server on the same
1433 host. For example, the "sendcommand" utility logs onto the server as an
1434 internal program in order to run arbitrary server commands. Since user clients
1435 do not utilize this command (or any of its companion commands), developers
1436 writing Citadel-compatible servers need not implement it.
1438 The sole argument to IPGM is the system's internal program password. This
1439 password is generated by the setup program and stored in the config file.
1440 Since internal programs have access to the config file, they know the correct
1443 IPGM returns OK for a correct authentication or ERROR otherwise.
1446 CHAT (enter CHAT mode)
1448 This command functions differently from every other command in the system. It
1449 is used to implement multi-user chat. For this to function, a new transfer
1450 mode, called START_CHAT_MODE, is implemented. If a client does not support
1451 chat mode, it should never send a CHAT command!
1453 In chat mode, messages may arrive asynchronously from the server at any
1454 time. The client may send messages at any time. This allows the arrival of
1455 messages without the client having to poll for them. Arriving messages will
1456 be of the form "user|message", where the "user" portion is, of course, the
1457 name of the user sending the message, and "message" is the message text.
1459 Chat mode ends when the server says it ends. The server will signal the end
1460 of chat mode by transmitting "000" on a line by itself. When the client reads
1461 this line, it must immediately exit from chat mode without sending any
1462 further traffic to the server. The next transmission sent to the server
1463 will be a regular server command.
1465 The Citadel server understands the following commands:
1466 /quit - Exit from chat mode (causes the server to do an 000 end)
1467 /who - List users currently in chat
1468 /whobbs - List users currently in chat and elsewhere
1469 /me - Do an irc-style action.
1470 /join - Join a new "room" in which all messages are only heard by
1471 people in that room.
1472 /msg - /msg <user> <msg> will send the msg to <user> only.
1473 /help - Print help information
1474 NOOP - Do nothing (silently)
1476 Any other non-empty string is treated as message text and will be broadcast
1477 to other users currently in chat.
1480 SEXP (Send instant message)
1482 This is one of two commands which implement instant messages (also known
1483 as "paging"). Commands ending in "...EXP" are so-named because we called
1484 them "express messages" before the industry standardized on the term
1485 "instant messages." When an instant message is sent, it will be
1486 logged in user to another. When an instant message is sent, it will be
1487 displayed the next time the target user executes a PEXP or GEXP command.
1489 The SEXP command accepts two arguments: the name of the user to send the
1490 message to, and the text of the message. If the message is successfully
1491 transmitted, OK is returned. If the target user is not logged in or if
1492 anything else goes wrong, ERROR is returned.
1494 If the server supports extended paging, sending a zero-length message
1495 merely checks for the presence of the requested user without actually sending
1496 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1497 the server to return SEND_LISTING if the requested user is logged in, and the
1498 client can then transmit a multi-line page.
1500 The reserved name "broadcast" may be used instead of a user name, to
1501 broadcast an instant message to all users currently connected to the server.
1503 Do be aware that if an instant message is transmitted to a user who is logged
1504 in using a client that does not check for instant messages, the message will
1505 never be received. Also, instant messages are NOT sent via the following
1506 transports: SMTP, POP3.
1509 PEXP (Print instant messages) ***DEPRECATED***
1511 This command is deprecated; it will eventually disappear from the protocol and
1512 its use is not recommended. Please use the GEXP command instead.
1514 Called without any arguments, PEXP simply dumps out the contents
1515 of any waiting instant messages. It returns ERROR if there is a problem,
1516 otherwise it returns LISTING_FOLLOWS followed by all messages.
1518 So how does the client know there are instant messages waiting? It could
1519 execute a random PEXP every now and then. Or, it can check the byte in
1520 server return code messages, between the return code and the parameters. In
1521 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1522 an "*" in this position to signify the presence of waiting instant messages.
1525 EBIO (Enter BIOgraphy)
1527 Transmit to the server a free-form text file containing a little bit of
1528 information about the user for other users to browse. This is typically
1529 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1530 after which the client is expected to transmit the file, or any of the usual
1531 ERROR codes if it fails.
1534 RBIO (Read BIOgraphy)
1536 Receive from the server a named user's bio. This command should be passed
1537 a single argument - the name of the user whose bio is requested. RBIO returns
1538 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1539 The return has the following parameters: the user name, user number, access
1540 level, date of last call, times called, and messages posted. This command
1541 returns ERROR+NO_SUCH_USER if the named user does not exist.
1543 RBIO no longer considers a user with no bio on file to be an error condition.
1544 It now returns a message saying the user has no bio on file as the text of the
1545 bio. This allows newer servers to operate with older clients.
1548 STEL (enter STEaLth mode)
1550 When in "stealth mode," a user will not show up in the "Who is online"
1551 listing (the RWHO server command). Only Aides may use stealth mode. The
1552 STEL command accepts one argument: a 1 indicating that the user wishes to
1553 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1554 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1555 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide;
1556 followed by a 1 or 0 indicating the new state.
1558 If any value other than 1 or 0 is sent by the client, the server simply
1559 replies with 1 or 0 to indicate the current state without changing it.
1561 The STEL command also makes it so a user does not show up in the chat room
1565 LBIO (List users who have BIOs on file)
1567 This command is self-explanatory. Any user who has used EBIO to place a bio
1568 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1569 this listing, unless it experiences an internal error in which case ERROR
1573 MSG2 (read MeSsaGe, mode 2)
1575 MSG2 follows the same calling convention as MSG0. The difference between
1576 the two commands is that MSG2 outputs messages in standard RFC822 format
1577 rather than in Citadel proprietary format.
1579 This command was implemented in order to make various gateway programs
1580 easier to implement, and to provide some sort of multimedia support in the
1581 future. Keep in mind that when this command is used, all messages will be
1582 output in fixed 80-column format.
1585 MSG3 (read MeSsaGe, mode 3 -- internal command)
1587 MSG3 is for use by internal programs only and should not be utilized by
1588 user-mode clients. It does require IPGM authentication. MSG3 follows the
1589 same calling convention as the other MSG commands, but upon success returns
1590 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1594 TERM (TERMinate another session)
1596 In a multithreaded environment, it sometimes becomes necessary to terminate
1597 a session that is unusable for whatever reason. The TERM command performs
1598 this task. Naturally, only Aides can execute TERM. The command should be
1599 called with a single argument: the session ID (obtained from an RWHO command)
1600 of the session to be terminated.
1602 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1603 a client program is prohibited from terminating the session it is currently
1609 DOWN (shut DOWN the server)
1611 This command, which may only be executed by an Aide, immediately shuts down
1612 the server. It is only implemented on servers on which such an operation is
1613 possible, such as a multithreaded Citadel engine. The server does not restart.
1614 DOWN returns OK if the user is allowed to shut down the server, in which case
1615 the client program should expect the connection to be immediately broken.
1618 SCDN (Schedule or Cancel a shutDowN)
1620 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1621 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1622 set, the server will be shut down when there are no longer any users logged in.
1623 Any value other than 0 or 1 will not change the flag, only report its state.
1624 No users will be kicked off the system, and in fact the server is still
1625 available for new connections. The command returns ERROR if it fails;
1626 otherwise, it returns OK followed by a number representing the current state
1630 EMSG (Enter a system MeSsaGe)
1632 This is the opposite of the MESG command - it allows the creation and editing
1633 of system messages. The only argument passed to EMSG is the name of the
1634 file being transmitted. If the file exists in any system message directory
1635 on the server it will be overwritten, otherwise a new file is created. EMSG
1636 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1639 Typical client software would use MESG to retrieve any existing message into
1640 an edit buffer, then present an editor to the user and run EMSG if the changes
1644 UIMG (Upload an IMaGe file)
1646 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1647 The first parameter supplied to UIMG should be 0 if the client is only checking
1648 for permission to upload, or 1 if the client is actually attempting to begin
1649 the upload operation. The second argument is the name of the file to be
1650 transmitted. In Citadel, the filename is converted to all lower case,
1651 appended with the characters ".gif", and stored in the "images" directory.
1653 UIMG returns OK if the client has permission to perform the requested upload,
1654 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1655 the operation (first parameter set to 1), an upload file is opened, and the
1656 client should begin writing to it with WRIT commands, then close it with a
1659 The supplied filename should be one of:
1661 -> _userpic_ (Server will attempt to write to the user's online photo)
1662 -> Any of the "well known" filenames described in the writeup for the
1666 HCHG (Hostname CHanGe)
1668 HCHG is a command, usable by any user, that allows a user to change their RWHO
1669 host value. This will mask a client's originating hostname from normal
1670 users; access level 6 and higher can see, in an extended wholist, the actual
1671 hostname the user originates from.
1673 The format of an HCHG command is:
1677 If a HCHG command is successful, the value OK (200) is returned.
1680 RCHG (Roomname CHanGe)
1682 RCHG is a command, usable by any user, that allows a user to change their RWHO
1683 room value. This will mask a client's roomname from normal users; access
1684 level 6 and higher can see, in an extended wholist, the actual room the user
1687 The format of an RCHG command is:
1691 If a RCHG command is successful, the value OK (200) is returned.
1694 UCHG (Username CHanGe)
1696 UCHG is an aide-level command which allows an aide to effectively change their
1697 username. If this value is blank, the user goes into stealth mode (see
1699 will show up as being from the real username in this mode, however. In
1700 addition, the RWHO listing will include both the spoofed and real usernames.
1702 The format of an UCHG command is:
1706 If a UCHG command is successful, the value OK (200) is returned.
1709 TIME (get server local TIME)
1711 TIME returns OK followed by the current time measured in seconds since
1712 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1714 This is used in allowing a client to calculate idle times.
1717 AGUP (Administrative Get User Parameters)
1718 ASUP (Administrative Set User Parameters)
1720 These commands are only executable by Aides and by server extensions running
1721 at system-level. They are used to get/set any and all parameters relating to
1722 a user account. AGUP requires only one argument: the name of the user in
1723 question. SGUP requires all of the parameters to be set. The parameters are
1724 as follows, and are common to both commands:
1728 2 - Flags (see citadel.h)
1733 7 - Timestamp of last call
1734 8 - Purge time (in days) for this user (or 0 to use system default)
1736 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1737 simply returns OK. If the client has insufficient access to perform the
1738 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1739 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1743 GPEX (Get Policy for message EXpiration)
1745 Returns the policy of the current room, floor, or site regarding the automatic
1746 purging (expiration) of messages. The following policies are available:
1747 0 - Fall back to the policy of the next higher level. If this is a room,
1748 use the floor's default policy. If this is a floor, use the system
1749 default policy. This is an invalid value for the system policy.
1750 1 - Do not purge messages automatically.
1751 2 - Purge by message count. (Requires a value: number of messages)
1752 3 - Purge by message age. (Requires a value: number of days)
1754 The format of this command is: GPEX <which>
1755 The value of <which> must be one of: "room" "floor" "site" "mailboxes"
1757 If successful, GPEX returns OK followed by <policy>|<value>.
1761 SPEX (Set Policy for message EXpiration)
1763 Sets the policy of the current room, floor, or site regarding the automatic
1764 purging (expiration) of messages. See the writeup for the GPEX command for
1765 the list of available policies.
1767 The format of this command is: SPEX <which>|<policy>|<value>
1768 The value of <which> must be one of: "room" "floor" "site" "mailboxes"
1770 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1774 CONF (get or set global CONFiguration options)
1776 Retrieves or sets various system-wide configuration and policy options. This
1777 command is only available to Aides. The sole parameter accepted is a command,
1778 which should be either GET or SET. If the GET command succeeds, CONF will
1779 return LISTING_FOLLOWS followed by the fields described below, one line at a
1780 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1781 the fields described below, one line at a time (don't worry about other fields
1782 being added in the future; if a 'short' configuration list is sent, the missing
1783 values at the end will be left unchanged on the system). If either command
1784 fails for any reason, ERROR is returned.
1786 The configuration lines are as follows:
1789 2. Fully qualified domain name
1790 3. Human-readable node name
1791 4. Landline telephone number of this system
1792 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1793 6. Server connection idle timeout (in seconds)
1794 7. Initial access level for new users
1795 8. Flag (0 or 1) - require registration for new users
1796 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1797 10. Name of twit room
1798 11. Text of <more> prompt
1799 12. Flag (0 or 1) - restrict access to Internet mail
1800 13. Geographic location of this system
1801 14. Name of the system administrator
1802 15. Number of maximum concurrent sessions allowed on the server
1803 16. (placeholder -- this field is no longer in use)
1804 17. Default purge time (in days) for users
1805 18. Default purge time (in days) for rooms
1806 19. Name of room to log instant messages to (or a zero-length name for none)
1807 20. Access level required to create rooms
1808 21. Maximum message length which may be entered into the system
1809 22. Minimum number of worker threads
1810 23. Maximum number of worker threads
1811 24. Port number for POP3 service
1812 25. Port number for SMTP service
1813 26. Flag (0 or 1) - strict RFC822 adherence - don't correct From: forgeries
1814 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1815 28. Port number for IMAP service
1816 29. How often (in seconds) to run the networker
1817 30. Flag (0 or 1) - disable self-service new user registration
1818 31. (placeholder -- this field is no longer in use)
1819 32. Hour (0 through 23) during which database auto-purge jobs are run
1820 33. Name of host where an LDAP service may be found
1821 34. Port number of LDAP service on above host
1824 37. Password for LDAP Bind DN
1825 38. Server IP address to listen on (or "0.0.0.0" for all addresses)
1826 39. Port number for SMTP MSA service
1827 40. Port number for IMAPS (SSL-encrypted IMAP)
1828 41. Port number for POP3S (SSL-encrypted POP3)
1829 42. Port number for SMTPS (SSL-encrypted SMTP)
1830 43. Flag (0 or 1) - enable full text search index
1832 CONF also accepts two additional commands: GETSYS and PUTSYS followed by an
1833 arbitrary MIME type (such as application/x-citadel-internet-config) which
1834 provides a means of storing generic configuration data in the Global System
1835 Configuration room without the need to add extra get/set commands to the
1838 Please note that the LDAP-specific configs have no effect on Citadel servers
1839 in which LDAP support is not enabled.
1843 MSG4 (read MeSsaGe, mode 4 -- output in preferred MIME format)
1845 This is the equivalent of MSG0, except it's a bit smarter about messages in
1846 rich text formats. Immediately following the "text" directive, the server
1847 will output RFC822-like MIME part headers such as "Content-type:" and
1848 "Content-length:". MIME formats are chosen and/or converted based on the
1849 client's preferred format settings, which are set using the MSGP command,
1854 MSGP (set MeSsaGe Preferred MIME format)
1856 Client tells the server what MIME content types it knows how to handle, and
1857 the order in which it prefers them. This is similar to an HTTP "Accept:"
1860 The parameters to a MSGP command are the client's acceptable MIME content
1861 types, in the order it prefers them (from most preferred to least preferred).
1862 For example: MSGP text/html|text/plain
1864 The MSGP command always returns OK.
1868 OPNA (OPeN Attachment)
1870 Opens, as a download file, a component of a MIME-encoded message. The two
1871 parameters which must be passed to this command are the message number and the
1872 name of the desired section. If the message or section does not exist, an
1873 appropriate ERROR code will be returned; otherwise, if the open is successful,
1874 this command will succeed returning the same information as an OPEN command.
1877 GEXP (Get instant messages)
1879 This is a more sophisticated way of retrieving instant messages than the old
1880 PEXP method. If there are no instant messages waiting, PEXP returns ERROR;
1881 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1883 0 - a boolean value telling the client whether there are any additional
1884 instant messages waiting following this one
1885 1 - a Unix-style timestamp
1886 2 - flags (see server.h for more info)
1887 3 - the name of the sender
1888 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1890 The text sent to the client will be the body of the instant message.
1892 So how does the client know there are instant messages waiting? It could
1893 execute a random GEXP every now and then. Or, it can check the byte in
1894 server return code messages, between the return code and the parameters. In
1895 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1896 an "*" in this position to signify the presence of waiting instant messages.
1899 FSCK (check message base reference counts)
1901 Verify, via the long way, that all message referenmce counts are correct. If
1902 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1903 by a transcript of the run. Otherwise ERROR is returned.
1906 DEXP (Disable receiving instant messages)
1908 DEXP sets or clears the "disable instant messages" flag. Pass this command a
1909 1 or 0 to respectively set or clear the flag. When the "disable instant
1910 messages" flag is set, no one except Aides may send the user instant messages.
1911 Any value other than 0 or 1 will not change the flag, only report its state.
1912 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1913 number representing the current state of the flag.
1916 REQT (REQuest client Termination)
1918 Request that the specified client (or all clients) log off. Aide level
1919 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1922 The REQT command accepts one parameter: the session ID of the client which
1923 should be terminated, or 0 for all clients. When successful, the REQT command
1926 It should be noted that REQT simply transmits an instant message to the
1927 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1928 this flag, and it is certainly possible for users to re-program their client
1929 software to ignore it. Therefore the effects of the REQT command should be
1930 considered advisory only. The recommended implementation practice is to first
1931 issue a REQT command, then wait a little while (from 30 seconds up to a few
1932 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1933 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1934 you are logging off users for the purpose of shutting down the server).
1937 SEEN (set or clear the SEEN flag for a message)
1939 Beginning with version 5.80, Citadel supports the concept of setting or
1940 clearing the "seen" flag for each individual message, instead of only allowing
1941 a "last seen" pointer. In fact, the old semantics are implemented in terms
1942 of the new semantics. This command requires two arguments: the number of the
1943 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1945 This command returns OK, unless the user is not logged in or a usage error
1946 occurred, in which case it returns ERROR. Please note that no checking is
1947 done on the supplied data; if the requested message does not exist, the SEEN
1948 command simply returns OK without doing anything.
1951 GTSN (GeT the list of SeeN messages)
1953 This command retrieves the list of "seen" (as opposed to unread) messages for
1954 the current room. It returns OK followed by an IMAP-format message list.
1957 SMTP (utility commands for the SMTP gateway)
1959 This command, accessible only by Aides, supports several utility operations
1960 which examine or manipulate Citadel's SMTP support. The first command argument
1961 is a subcommand telling the server what to do. The following subcommands are
1964 SMTP mx|hostname (display all MX hosts for 'hostname')
1965 SMTP runqueue (attempt immediate delivery of all messages
1966 in the outbound SMTP queue, ignoring any
1967 retry times stored there)
1970 STLS (Start Transport Layer Security)
1972 This command starts TLS on the current connection. The current
1973 implementation uses OpenSSL on both the client and server end. For future
1974 compatibility all clients must support at least TLSv1, and servers are
1975 guaranteed to support TLSv1. During TLS negotiation (see below) the server
1976 and client may agree to use a different protocol.
1978 The server returns ERROR if it does not support SSL or SSL initialization
1979 failed on the server; otherwise it returns OK. Once the server returns OK and
1980 the client has read the response, the server and client immediately negotiate
1981 TLS (in OpenSSL, using SSL_connect() on the client and SSL_accept() on the
1982 server). If negotiation fails, the server and client should attempt to resume
1983 the session unencrypted. If either end is unable to resume the session, the
1984 connection should be closed.
1986 This command may be run at any time.
1989 GTLS (Get Transport Layer Security Status)
1991 This command returns information about the current connection. The server
1992 returns OK plus several parameters if the connection is encrypted, and ERROR
1993 if the connection is not encrypted. It is primarily used for debugging. The
1994 command may be run at any time.
1996 0 - Protocol name, e.g. "SSLv3"
1997 1 - Cipher suite name, e.g. "ADH-RC4-MD5"
1998 2 - Cipher strength bits, e.g. 128
1999 3 - Cipher strength bits actually in use, e.g. 128
2002 IGAB (Initialize Global Address Book)
2004 This command creates, or re-creates, a database of Internet e-mail addresses
2005 using the vCard information in the Global Address Book room. This procedure
2006 is normally run internally when the server determines it necessary, but is
2007 also provided as a server command to be used as a troubleshooting/maintenenance
2008 tool. Only a system Aide can run the command. It returns OK on success or
2012 QDIR (Query global DIRectory)
2014 Look up an internet address in the global directory. Any logged-in user may
2015 call QDIR with one parameter, the Internet e-mail address to look up. QDIR
2016 returns OK followed by a Citadel address if there is a match, otherwise it
2017 returns ERROR+NOT_LOGGED_IN.
2020 ISME (find out if an e-mail address IS ME)
2022 This is a quickie shortcut command to find out if a given e-mail address
2023 belongs to the user currently logged in. Its sole argument is an address to
2024 parse. The supplied address may be in any format (local, IGnet, or Internet).
2025 The command returns OK if the address belongs to the user, ERROR otherwise.
2028 VIEW (set the VIEW for a room)
2030 Set the preferred view for the current user in the current room. Please see
2031 views.txt for more information on views. The sole parameter for this command
2032 is the type of view requested. VIEW returns OK on success or ERROR on failure.
2035 QNOP (Quiet No OPeration)
2037 This command does nothing, similar to the NOOP command. However, unlike the
2038 NOOP command, it returns *absolutely no response* at all. The client has no
2039 way of knowing that the command executed. It is intended for sending
2040 "keepalives" in situations where a full NOOP would cause the client protocol
2043 Naturally, sending this command to a server that doesn't support it is an
2044 easy way to mess things up. Therefore, client software should first check
2045 the output of an INFO command to ensure that the server supports quiet noops.
2049 ICAL (Internet CALendaring commands)
2051 This command supports a number of subcommands which are used to process the
2052 calendaring/scheduling support in Citadel. Here are the subcommands which
2056 Test server for calendaring support. Always returns OK unless the server
2057 does not have the calendar module enabled.
2059 ICAL respond|msgnum|partnum|action
2060 Respond to a meeting request. 'msgnum' and 'partnum' refer to a MIME-encoded
2061 meeting invitation in the current room. 'action' must be set to either
2062 "accept" or "decline" to determine the action to take. This subcommand will
2063 return either OK or ERROR.
2065 ICAL conflicts|msgnum|partnum
2066 Determine whether an incoming VEVENT will fit in the user's calendar by
2067 checking it against the existing VEVENTs. 'msgnum' and 'partnum' refer to
2068 a MIME-encoded meeting invitation in the current room (usually the inbox).
2069 This command may return ERROR if something went wrong, but usually it will
2070 return LISTING_FOLLOWS followed by a list of zero or more conflicting
2071 events. A zero-length list means that there were no conflicts.
2073 ICAL handle_rsvp|msgnum|partnum
2074 Handle an incoming "reply" (or RSVP) to a meeting request you sent out.
2075 'msgnum' and 'partnum' refer to a MIME-encoded reply in the current room.
2076 'action' must be set to either "update" or "ignore" to determine the action
2077 to take. If the action is "update" then the server will hunt for the meeting
2078 in the user's Calendar> room, and update the status for this attendee. Either
2079 way, the reply message is deleted from the current room. This subcommand will
2080 return either OK or ERROR.
2082 ICAL freebusy|username
2083 Output the free/busy times for the requested user. If the user specified
2084 has a calendar available, this command will return LISTING_FOLLOWS and a
2085 compound VCALENDAR object. That object, in turn, will contain VEVENT
2086 objects that have been stripped of all properties except for the bare
2087 minimum needed to learn free/busy times (such as DTSTART, DTEND, and
2088 TRANSP). If there is no such user, or no calendar available, the usual
2089 ERROR codes will be returned.
2093 Readers who are paying attention will notice that there is no subcommand to
2094 send out meeting invitations. This is because that task can be handled
2095 automatically by the Citadel server. Issue this command with <bool> set to 1
2096 to enable Server Generated Invitations. In this mode, when an event is saved
2097 to the user's Calendar> room and it contains attendees, Citadel will
2098 automatically turn the event into vCalendar REQUEST messages and mail them
2099 out to all listed attendees. If for some reason the client needs to disable
2100 Server Generated Invitations, the command may be sent again with <bool> = 0.
2104 MRTG (Multi Router Traffic Grapher)
2106 Multi Router Traffic Grapher (please see http://www.mrtg.org for more info) is
2107 a tool which creates pretty graphs of network activity, usually collected from
2108 routers using SNMP. However, its ability to call external scripts has spawned
2109 a small community of people using it to graph anything which can be graphed.
2110 The MRTG command can output Citadel server activity in the format MRTG expects.
2112 This format is as follows:
2117 Line 3: uptime of system
2118 Line 4: name of system
2121 MRTG accepts two different keywords. "MRTG users" will return two variables,
2122 the number of connected users and the number of active users. "MRTG messages"
2123 will return one variable (and a zero in the second field), showing the current
2124 highest message number on the system. Any other keyword, or a missing keyword,
2125 will cause the MRTG command to return an ERROR code.
2127 Please get in touch with the Citadel developers if you wish to experiment with
2132 GNET (Get NETwork configuration for this room)
2133 SNET (Set NETwork configuration for this room)
2135 These commands get/set the network configuration for the current room. Aide
2136 or Room Aide privileges are required, otherwise an ERROR code is returned.
2137 If the command succeeds, LISTING_FOLLOWS or SEND_LISTING is returned. The
2138 network configuration for a specific room includes neighbor nodes with whom
2139 the room is shared, and mailing list recipients. The format of the network
2140 configuration is described in the file "netconfigs.txt".
2144 ASYN (ASYNchronous message support)
2146 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
2147 only parameter specified should be 1 or 0 to indicate that the client can or
2148 cannot handle this type of messages. The server will reply OK followed by a
2149 1 or 0 to tell the client which mode it is now operating in.
2151 If the command is not available on the server (i.e. it returns ERROR), or
2152 if the command has not been executed by the client, it should be assumed that
2153 this mode of operation is NOT in effect.
2155 The client may also send any value other than 0 or 1 to simply cause the
2156 server to output its current state without changing it.
2158 When asynchronous protocol mode is in effect, the client MUST handle any
2159 asynchronous messages as they arrive, before doing anything else.
2163 SRCH (SeaRCH the message base)
2165 This command's implementation is incomplete and will be documented when it
2171 ASYNCHRONOUS MESSAGES
2172 ---------------------
2174 When the client protocol is operating in asynchronous mode (please refer to
2175 the writeup of the ASYN command above), the following messages may arrive at
2179 902 (instant message arriving)
2181 One or more instant messages have arrived for this client.