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.
48 The native character set for the Citadel system is UTF-8. Unless otherwise
49 specified, all data elements are expected to be in the UTF-8 character set.
50 Specifically, all non-MIME messages should be assumed to be in UTF-8. MIME
51 messages may be in whatever character set is specified by the MIME header, of
52 course; however, some clients (such as WebCit) will automatically convert
53 messages from other character sets before displaying them.
56 GENERAL INFORMATION ABOUT THE SERVER
57 ------------------------------------
59 The server is connection-oriented and stateful: each client requires its own
60 connection to a server process, and when a command is sent, the client must
61 read the response, and then transfer data or change modes if necessary.
63 The application layer is very much like other Internet protocols such as SMTP
64 or NNTP. A client program sends one-line commands to the server, and the
65 server responds with a three-digit numeric result code followed by a message
66 describing what happened. This cycle continues until the end of the
69 Unlike protocols such as FTP, all data transfers occur in-band. This means
70 that the same connection that is used for exchange of client/server
71 messages, will also be used to transfer data back and forth. (FTP opens a
72 separate connection for data transfers.) This keeps protocol administration
73 straightforward, as it can traverse firewalls without any special protocol
74 support on the firewall except for opening the port number.
80 The server will respond to all commands with a 3-digit result code, which
81 will be the first three characters on the line. The rest of the line may
82 contain a human-readable string explaining what happened. (Some client
83 software will display some of these strings to the user.)
85 The first digit is the most important. The following codes are defined for
86 this position: ERROR, OK, MORE_DATA, LISTING_FOLLOWS, and SEND_LISTING.
88 The second and third digits may provide a reason as to why a command
89 succeeded or failed. See ipcdef.h for the available codes.
91 ERROR means the command did not complete.
92 OK means the command executed successfully.
93 MORE_DATA means the command executed partially. Usually this means that
94 another command needs to be executed to complete the operation. For example,
95 sending the USER command to log in a user usually results in a MORE_DATA
96 result code, because the client needs to execute a PASS command to send the
97 password and complete the login.
98 LISTING_FOLLOWS means that after the server response, the server will
99 output a listing of some sort. The client *must* read the listing, whether
100 it wants to or not. The end of the listing is signified by the string
101 "000" on a line by itself.
102 SEND_LISTING is the opposite of LISTING_FOLLOWS. It means that the client
103 should begin sending a listing of some sort. The client *must* send something,
104 even if it is an empty listing. Again, the listing ends with "000" on a line
106 BINARY_FOLLOWS and SEND_BINARY mean that the client must immediately send
107 or receive a block of binary data. The first parameter will always be the
109 ASYNC_MESSAGE_FOLLOWS means that an asynchronous, or unsolicited, message
110 follows. The next line will be one of the above codes, and if a data transfer
111 is involved it must be handled immediately. Note that the client will not
112 receive this type of response unless it indicates to the server that it is
113 capable of handling them; see the writeup of the ASYN command later in this
119 Zero or more parameters may be passed to a command. When more than one
120 parameter is passed to a command, they should be separated by the "|"
123 In this example, we're using the "SETU" command and passing three
124 parameters: 80, 24, and 260.
126 When the server spits out data that has parameters, if more than one
127 parameter is returned, they will be separated by the "|" symbol like
130 In this example, we just executed the "GETU" command, and it returned us
131 an OK result code (the '2' in the 200) and three parameters: 80, 24, and
138 This is a listing of all the commands that a Citadel server can execute.
143 This command does nothing. It takes no arguments and always returns
144 OK. It is intended primarily for testing and development, but it might also
145 be used as a "keep alive" command to prevent the server from timing out, if
146 it's running over a transport that needs this type of thing.
149 ECHO (ECHO something)
151 This command also does nothing. It simply returns OK followed by whatever
157 Terminate the server connection. This command takes no arguments. It
158 returns OK and closes the connection immediately.
163 Log out the user without closing the server connection. It always returns
164 OK even if no user is logged in.
167 USER (send USER name)
169 The first step in logging in a user. This command takes one argument: the
170 name of the user to be logged in. If the user exists, a MORE_DATA return
171 code will be sent, which means the client should execute PASS as the next
172 command. If the user does not exist, ERROR + NO_SUCH_USER is returned.
177 The second step in logging in a user. This command takes one argument: the
178 password for the user we are attempting to log in. If the password doesn't
179 match the correct password for the user we specified for the USER command,
180 ERROR + PASSWORD_REQUIRED is returned. If a USER command has not been
181 executed yet, ERROR + USERNAME_REQUIRED is returned. If a user is already
182 logged in, ERROR + ALREADY_LOGGED_IN is returned. If the password is
183 correct, OK is returned and the user is now logged in... and most of the
184 other server commands can now be executed. Along with OK, the following
185 parameters are returned:
187 0 - The user's name (in case the client wants the right upper/lower casing)
188 1 - The user's current access level
191 4 - Various flags (see citadel.h)
193 6 - Time of last call (UNIX timestamp)
196 NEWU (create NEW User account)
198 This command creates a new user account AND LOGS IT IN. The argument to
199 this command will be the name of the account. No case conversion is done
200 on the name. Note that the new account is installed with a default
201 configuration, and no password, so the client should immediately prompt the
202 user for a password and install it with the SETP command as soon as this
203 command completes. This command returns OK if the account was created and
204 logged in, ERROR + ALREADY_EXISTS if another user already exists with this
205 name, ERROR + NOT_HERE if self-service account creation is disabled,
206 ERROR + MAX_SESSIONS_EXCEEDED if too many users are logged in, ERROR +
207 USERNAME_REQUIRED if a username was not provided, or ERROR + ILELGAL_VALUE
208 if the username provided is invalid. If OK, it will also return the same
209 parameters that PASS returns.
211 Please note that the NEWU command should only be used for self-service
212 user account creation. For administratively creating user accounts, please
213 use the CREU command.
216 SETP (SET new Password)
218 This command sets a new password for the currently logged in user. The
219 argument to this command will be the new password. The command always
220 returns OK, unless the client is not logged in, in which case it will return
221 ERROR + NOT_LOGGED_IN, or if the user is an auto-login user, in which case
222 it will return ERROR + NOT_HERE.
225 CREU (CREate new User account)
227 This command creates a new user account AND DOES NOT LOG IT IN. The first
228 argument to this command will be the name of the account. No case conversion
229 is done on the name. Note that the new account is installed with a default
230 configuration, and no password. The second argument is optional, and will be
231 an initial password for the user. This command returns OK if the account was
232 created, ERROR + HIGHER_ACCESS_REQUIRED if the user is not an Aide, ERROR +
233 USERNAME_REQUIRED if no username was specified, or ERROR + ALREADY_EXISTS if
234 another user already exists with this name.
236 Please note that CREU is intended to be used for activities in which a
237 system administrator is creating user accounts. For self-service user
238 account creation, use the NEWU command.
241 LKRN (List Known Rooms with New messages)
243 List known rooms with new messages. If the client is not logged in, ERROR +
244 NOT_LOGGED_IN is returned. Otherwise, LISTING_FOLLOWS is returned, followed
245 by the room listing. Each line in the listing contains the full name of a
246 room, followed by the '|' symbol, and then a number that may contain the
249 #define QR_PERMANENT 1 /* Room does not purge */
250 #define QR_PRIVATE 4 /* Set for any type of private room */
251 #define QR_PASSWORDED 8 /* Set if there's a password too */
252 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
253 #define QR_DIRECTORY 32 /* Directory room */
254 #define QR_UPLOAD 64 /* Allowed to upload */
255 #define QR_DOWNLOAD 128 /* Allowed to download */
256 #define QR_VISDIR 256 /* Visible directory */
257 #define QR_ANONONLY 512 /* Anonymous-Only room */
258 #define QR_ANON2 1024 /* Anonymous-Option room */
259 #define QR_NETWORK 2048 /* Shared network room */
260 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
261 #define QR_READONLY 8192 /* Aide status required to post */
263 Then it returns another '|' symbol, followed by a second set of bits comprised
266 #define QR2_SYSTEM 1 /* System room; hide by default */
267 #define QR2_SELFLIST 2 /* Self-service mailing list mgmt */
269 Other bits may be defined in the future. The listing terminates, as with
270 all listings, with "000" on a line by itself.
272 Starting with version 4.01 and above, floors are supported. The first
273 argument to LKRN should be the number of the floor to list rooms from. Only
274 rooms from this floor will be listed. If no arguments are passed to LKRN, or
275 if the floor number requested is (-1), rooms on all floors will be listed.
277 The third field displayed on each line is the number of the floor the room
278 is on. The LFLR command should be used to associate floor numbers with
281 The fourth field displayed on each line is a "room listing order." Unless
282 there is a compelling reason not to, clients should sort any received room
283 listings by this value.
285 The fifth field is a special bit bucket containing fields which pertain to
286 room access controls:
288 #define UA_KNOWN 2 /* Known room */
289 #define UA_GOTOALLOWED 4 /* Access will be granted to this room
290 * if the user calls it up by name */
291 #define UA_HASNEWMSGS 8 /* Unread messages exist in room */
292 #define UA_ZAPPED 16 /* Zapped from known rooms list */
294 The sixth field is the user's current view for the room. (See VIEW command)
297 LKRO (List Known Rooms with Old [no new] messages)
299 This follows the same usage and format as LKRN.
302 LZRM (List Zapped RooMs)
304 This follows the same usage and format as LKRN and LKRO.
307 LKRA (List All Known Rooms)
309 Same format. Lists all known rooms, with or without new messages.
312 LRMS (List all accessible RooMS)
314 Again, same format. This command lists all accessible rooms, known and
315 forgotten, with and without new messages. It does not, however, list
316 inaccessible private rooms.
319 LPRM (List all Public RooMs)
321 Again, same format. This command lists all public rooms, and nothing else.
322 Unlike the other list rooms commands, this one can be executed without logging
326 GETU (GET User configuration)
328 This command retrieves the screen dimensions and user options for the
329 currently logged in account. ERROR + NOT_LOGGED_IN will be returned if no
330 user is logged in, of course. Otherwise, OK will be returned, followed by
331 four parameters. The first parameter is the user's screen width, the second
332 parameter is the user's screen height, and the third parameter is a bag of
333 bits with the following meanings:
335 #define US_LASTOLD 16 /* Print last old message with new */
336 #define US_EXPERT 32 /* Experienced user */
337 #define US_UNLISTED 64 /* Unlisted userlog entry */
338 #define US_NOPROMPT 128 /* Don't prompt after each message */
339 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
340 #define US_PAGINATOR 2048 /* Pause after each screen of text */
342 There are other bits, too, but they can't be changed by the user (see below).
345 SETU (SET User configuration)
347 This command does the opposite of SETU: it takes the screen dimensions and
348 user options (which were probably obtained with a GETU command, and perhaps
349 modified by the user) and writes them to the user account. This command
350 should be passed three parameters: the screen width, the screen height, and
351 the option bits (see above). It returns ERROR + NOT_LOGGED_IN if no user is
352 logged in, and ERROR + ILLEGAL_VALUE if the parameters are incorrect.
354 Note that there exist bits here which are not listed in this document. Some
355 are flags that can only be set by Aides or the system administrator. SETU
356 will ignore attempts to toggle these bits. There also may be more user
357 settable bits added at a later date. To maintain later downward compatibility,
358 the following procedure is suggested:
360 1. Execute GETU to read the current flags
361 2. Toggle the bits that we know we can toggle
362 3. Execute SETU to write the flags
364 If we are passed a bit whose meaning we don't know, it's best to leave it
365 alone, and pass it right back to the server. That way we can use an old
366 client on a server that uses an unknown bit without accidentally clearing
367 it every time we set the user's configuration.
372 This command is used to goto a new room. When the user first logs in (login
373 is completed after execution of the PASS command) this command is
374 automatically and silently executed to take the user to the first room in the
375 system (usually called the Lobby).
377 This command can be passed one or two parameters. The first parameter is,
378 of course, the name of the room. Although it is not case sensitive, the
379 full name of the room must be used. Wildcard matching or unique string
380 matching of room names should be the responsibility of the client.
382 Note that the reserved room name "_BASEROOM_" can be passed to the server
383 to cause the goto command to take the user to the first room in the system,
384 traditionally known as the Lobby>. As long as a user is logged in, a
385 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
386 allow client software to return to the base room when it doesn't know
389 There are also several additional reserved room names:
390 "_MAIL_" goes to the user's inbox (i.e. the Mail> room).
391 "_TRASH_" goes to the user's personal trashcan room (trash folder).
392 "_BITBUCKET_" goes to a room that has been chosen for messages without a home.
393 "_CALENDAR_" goes to the user's primary personal calendar.
394 "_CONTACTS_" goes to the user's primary personal address book.
395 "_NOTES_" goes to the user's primary personal notes room.
396 "_TASKS_" goes to the user's primary personal task list.
399 The second (and optional) parameter is a password, if one is required for
400 access to the room. This allows for all types of rooms to be accessed via
401 this command: for public rooms, invitation-only rooms to which the user
402 has access, and preferred users only rooms to which the user has access, the
403 room will appear in a room listing. For guess-name rooms, this command
404 will work transparently, adding the room to the user's known room list when
405 it completes. For passworded rooms, access will be denied if the password
406 is not supplied or is incorrect, or the command will complete successfully
407 if the password is correct.
409 The third (and also) optional parameter is a "transient" flag. Normally,
410 when a user enters a private and/or zapped room, the room is added to the
411 user's known rooms list. If the transient flag is set to non-zero, this is
412 called a "transient goto" which causes the user to enter the room without
413 adding the room to the known rooms list.
415 The possible result codes are:
417 OK - The command completed successfully. User is now in the room.
418 (See the list of returned parameters below)
420 ERROR - The command did not complete successfully. Check the second and
421 third positions of the result code to find out what happened:
423 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
424 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
425 password was incorrect.
426 ROOM_NOT_FOUND - The requested room does not exist.
428 The typical procedure for entering a passworded room would be:
430 1. Execute a GOTO command without supplying any password.
431 2. ERROR + PASSWORD_REQUIRED will be returned. The client now knows that
432 the room is passworded, and prompts the user for a password.
433 3. Execute a GOTO command, supplying both the room name and the password.
434 4. If OK is returned, the command is complete. If, however,
435 ERROR + PASSWORD_REQUIRED is still returned, tell the user that the supplied
436 password was incorrect. The user remains in the room he/she was previously
439 When the command succeeds, these parameters are returned:
440 0. The name of the room
441 1. Number of unread messages in this room
442 2. Total number of messages in this room
443 3. Info flag: set to nonzero if the user needs to read this room's info
444 file (see RINF command below)
445 4. Various flags associated with this room. (See LKRN cmd above)
446 5. The highest message number present in this room
447 6. The highest message number the user has read in this room
448 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
449 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
450 a regular Aide (this makes access checks easy).
451 9. The number of new Mail messages the user has (useful for alerting the
452 user to the arrival of new mail during a session)
453 10. The floor number this room resides on
454 11. The *current* "view" for this room (see views.txt for more info)
455 12. The *default* "view" for this room
457 The default view gives the client a hint as to what views the user should
458 be allowed to select. For example, it would be confusing to allow messages
459 in a room intended for calendar items. The server does not enforce these
460 restrictions, though.
463 MSGS (get pointers to MeSsaGeS in this room)
465 This command obtains a listing of all the messages in the current room
466 which the client may request. This command may be passed a single parameter:
467 either "all", "old", or "new" to request all messages, only old messages, or
468 new messages. Or it may be passed two parameters: "last" plus a number, in
469 which case that many message pointers will be returned; "first" plus a
470 number, for the corresponding effect; or "gt" plus a number, to list all
471 messages in the current room with a message number greater than the one
472 specified. If no parameters are specified, "all" is assumed.
474 The third argument, may be either 0 or 1. If it is 1, this command behaves
475 differently: before a listing is returned, the client must transmit a list
476 of fields to search for. The field headers are listed below in the writeup
477 for the "MSG0" command.
479 The optional fourth argument may also be either 0 or 1. If it is 1, the
480 output of this command will include not only a list of message numbers, but
481 a simple header summary of each message as well. This is somewhat resource
482 intensive so you shouldn't do this unless you absolutely need all the headers
483 immediately. The fields which are output (in the usual delimited fashion, of
484 course) are: message number, timestamp, display name, node name, Internet
485 email address (if present), subject (if present).
487 This command can return three possible results. ERROR + NOT_LOGGED_IN will
488 be returned if no user is currently logged in. Otherwise, LISTING_FOLLOWS
489 will be returned, and the listing will consist of zero or more message
490 numbers, one per line. The listing ends, as always, with the string "000"
491 alone on a line by itself. The listed message numbers can be used to request
492 messages from the system. If "search mode" is being used, the server will
493 return START_CHAT_MODE, and the client is expected to transmit the search
494 criteria, and then read the message list.
496 Since this is somewhat complex, here are some examples:
498 Example 1: Read all new messages
501 Server: 100 Message list...
507 Example 2: Read the last five messages
510 Server: 100 Message list...
518 Example 3: Read all messages written by "IGnatius T Foobar"
521 Server: 800 Send template then receive message list
522 Client: from|IGnatius T Foobar
536 Note that in "search mode" the client may specify any number of search
537 criteria. These criteria are applied with an AND logic.
540 MSG0 (read MeSsaGe, mode 0)
542 This is a command used to read the text of a message. "Mode 0" implies that
543 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
544 messages in more robust formats. This command should be passed two arguments.
545 The first is the message number of the message being requested. The second
546 argument specifies whether the client wants headers and/or message body:
550 3 = Headers only, with MIME information suppressed (this runs faster)
552 If the request is denied, ERROR + NOT_LOGGED_IN or ERROR + MESSAGE_NOT_FOUND
553 will be returned. Otherwise, LISTING_FOLLOWS will be returned, followed by
554 the contents of the message. The following fields may be sent:
556 type= Formatting type. The currently defined types are:
557 0 = "traditional" Citadel formatting. This means that newlines should be
558 treated as spaces UNLESS the first character on the next line is a space. In
559 other words, only indented lines should generate a newline on the user's screen
560 when the message is being displayed. This allows a message to be formatted to
561 the reader's screen width. It also allows the use of proportional fonts.
562 1 = a simple fixed-format message. The message should be displayed to
563 the user's screen as is, preferably in a fixed-width font that will fit 80
565 4 = MIME format message. The message text is expected to contain a header
566 with the "Content-type:" directive (and possibly others).
568 msgn= The message ID of this message on the system it originated on.
569 path= An e-mailable path back to the user who wrote the message.
571 time= The date and time of the message, in Unix format (the number of
572 seconds since midnight on January 1, 1970, GMT).
574 from= The name of the author of the message.
575 rcpt= If the message is a private e-mail, this is the recipient.
576 room= The name of the room the message originated in.
577 node= The short node name of the system this message originated on.
578 hnod= The long node name of the system this message originated on.
579 zaps= The id/node of a message which this one zaps (supersedes).
581 part= Information about a MIME part embedded in this message.
582 pref= Information about a multipart MIME prefix such as "multipart/mixed"
583 or "multipart/alternative". This will be output immediately prior
584 to the various "part=" lines which make up the multipart section.
585 suff= Information about a multipart MIME suffix. This will be output
586 immediately following the various "part=" lines which make up the
589 text Note that there is no "=" after the word "text". This string
590 signifies that the message text begins on the next line.
593 WHOK (WHO Knows room)
595 This command is available only to Aides. ERROR + HIGHER_ACCESS_REQUIRED
596 will be returned if the user is not an Aide. Otherwise, it returns
597 LISTING_FOLLOWS and then lists, one user per line, every user who has
598 access to the current room.
601 INFO (get server INFO)
603 This command will *always* return LISTING_FOLLOWS and then print out a
604 listing of zero or more strings. Client software should be written to expect
605 anywhere from a null listing to an infinite number of lines, to allow later
606 backward compatibility. The current implementation defines the following
607 parts of the listing:
609 Line 1 - Your unique session ID on the server
610 Line 2 - The node name of the Citadel server
611 Line 3 - Human-readable node name of the Citadel server
612 Line 4 - The fully-qualified domain name (FQDN) of the server
613 Line 5 - The name of the server software, i.e. "Citadel 4.00"
614 Line 6 - (The revision level of the server code) * 100
615 Line 7 - The geographical location of the site (city and state if in the US)
616 Line 8 - The name of the system administrator
617 Line 9 - A number identifying the server type (see below)
618 Line 10 - The text of the system's paginator prompt
619 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
620 Line 12 - Paging level. 0 if the system only supports inline paging,
621 1 if the system supports "extended" paging (check-only and
622 multiline modes). See the SEXP command for further information.
623 Line 13 - The "nonce" for this session, for support of APOP-style
624 authentication. If this field is present, clients may authenticate
626 Line 14 - Set to nonzero if this server supports the QNOP command.
627 Line 15 - Set to nonzero if this server is capable of connecting to a
628 directory service using LDAP.
630 *** NOTE! *** The "server type" code is intended to promote global
631 compatibility in a scenario in which developers have added proprietary
632 features to their servers or clients. We are attempting to avoid a future
633 situation in which users need to keep different client software around for
634 each Citadel they use. *Please*, if you are a developer and plan to add
635 proprietary features:
637 -> Your client programs should still be able to utilize servers other than
639 -> Clients other than your own should still be able to utilize your server,
640 even if your proprietary extensions aren't supported.
641 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
642 server type code, which can be assigned to your server program.
643 -> If you document what you did in detail, perhaps it can be added to a
644 future release of the Citadel program, so everyone can enjoy it. Better
645 yet, just work with the Citadel development team on the main source tree.
647 If everyone follows this scheme, we can avoid a chaotic situation with lots
648 of confusion about which client program works with which server, etc. Client
649 software can simply check the server type (and perhaps the revision level)
650 to determine ahead of time what commands may be utilized.
652 Please refer to "developers.txt" for information on what codes belong to whom.
656 RDIR (Read room DIRectory)
658 Use this command to read the directory of a directory room. ERROR + NOT_HERE
659 will be returned if the room has no directory, ERROR + HIGHER_ACCESS_REQUIRED
660 will be returned if the room's directory is not visible and the user does not
661 have Aide or Room Aide privileges, ERROR + NOT_LOGGED_IN will be returned if
662 the user is not logged in; otherwise LISTING_FOLLOWS will be returned,
663 followed by the room's directory. Each line of the directory listing will
664 contain three fields: a filename, the length of the file, and a description.
666 The server message contained on the same line with LISTING_FOLLOWS will
667 contain the name of the system and the name of the directory, such as:
669 uncensored.citadel.org|/usr/local/citadel/files/my_room_directory
672 SLRP (Set Last-message-Read Pointer)
674 This command marks all messages in the current room as read (seen) up to and
675 including the specified number. Its sole parameter is the number of the last
676 message that has been read. This allows the pointer to be set at any
677 arbitrary point in the room. Optionally, the parameter "highest" may be used
678 instead of a message number, to set the pointer to the number of the highest
679 message in the room, effectively marking all messages in the room as having
680 been read (ala the Citadel <G>oto command).
682 The command will return OK if the pointer was set, or ERROR + NOT_LOGGED_IN
683 if the user is not logged in. If OK is returned, it will be followed by a
684 single argument containing the message number the last-read-pointer was set to.
687 INVT (INViTe a user to a room)
689 This command may only be executed by Aides, or by the room aide for the
690 current room. It is used primarily to add users to invitation-only rooms,
691 but it may also be used in other types of private rooms as well. Its sole
692 parameter is the name of the user to invite.
694 The command will return OK if the operation succeeded. ERROR + NO_SUCH_USER
695 will be returned if the user does not exist, ERROR + HIGHER_ACCESS_REQUIRED
696 will be returned if the operation would have been possible if the user had
697 higher access, and ERROR + NOT_HERE may be returned if the room is not a
701 KICK (KICK a user out of a room)
703 This is the opposite of INVT: it is used to kick a user out of a private
704 room. It can also be used to kick a user out of a public room, but the
705 effect will only be the same as if the user <Z>apped the room - a non-stupid
706 user can simply un-zap the room to get back in.
709 GETR (GET Room attributes)
711 This command is used for editing the various attributes associated with a
712 room. A typical "edit room" command would work like this:
713 1. Use the GETR command to get the current attributes
714 2. Change some of them around
715 3. Use SETR (see below) to save the changes
716 4. Possibly also change the room aide using the GETA and SETA commands
718 GETR takes no arguments. It will only return OK if the SETR command will
719 also return OK. This allows client software to tell the user that he/she
720 can't edit the room *before* going through the trouble of actually doing the
721 editing. Possible return codes are:
723 ERROR+NOT_LOGGED_IN - No user is logged in.
724 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
725 and the room aide associated with the current room, can access this command.
726 OK - Command succeeded. Parameters are returned.
728 If OK is returned, the following parameters will be returned as well:
730 0. The name of the room
731 1. The room's password (if it's a passworded room)
732 2. The name of the room's directory (if it's a directory room)
733 3. Various flags (bits) associated with the room (see LKRN cmd above)
734 4. The floor number on which the room resides
735 5. The room listing order
736 6. The default view for the room (see views.txt)
737 7. A second set of flags (bits) associated with the room
740 SETR (SET Room attributes)
742 This command sets various attributes associated with the current room. It
743 should be passed the following arguments:
745 0. The name of the room
746 1. The room's password (if it's a passworded room)
747 2. The name of the room's directory (if it's a directory room)
748 3. Various flags (bits) associated with the room (see LKRN cmd above)
749 4. "Bump" flag (see below)
750 5. The floor number on which the room should reside
751 6. The room listing order
752 7. The default view for the room (see views.txt)
753 8. A second set of flags (bits) associated with the room
755 *Important: You should always use GETR to retrieve the current attributes of
756 the room, then change what you want to change, and then use SETR to write it
757 all back. This is particularly important with respect to the flags: if a
758 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
759 only toggle the bits you want to toggle. This will allow for upward
762 The _BASEROOM_, user's Mail> and Aide> rooms can only be partially edited.
763 Any changes which cannot be made will be silently ignored.
765 If the room is a private room, you have the option of causing all users who
766 currently have access, to forget the room. If you want to do this, set the
767 "bump" flag to 1, otherwise set it to 0.
772 This command is used to get the name of the Room Aide for the current room.
773 It will return ERROR + NOT_LOGGED_IN if no user is logged in, or OK if the
774 command succeeded. Along with OK there will be returned one parameter: the
775 name of the Room Aide. A conforming server must guarantee that the user is
781 The opposite of GETA, used to set the Room Aide for the current room. One
782 parameter should be passed, which is the name of the user who is to be the
783 new Room Aide. Under Citadel, this command may only be executed by Aides
784 and by the *current* Room Aide for the room. Return codes possible are:
785 ERROR + NOT_LOGGED_IN (Not logged in.)
786 ERROR + HIGHER_ACCESS_REQUIRED (Higher access required.)
787 ERROR + NOT_HERE (Room cannot be edited.)
788 OK (Command succeeded.)
791 ENT0 (ENTer message, mode 0)
793 This command is used to enter messages into the system. It accepts four
796 0 - Post flag. This should be set to 1 to post a message. If it is
797 set to 0, the server only returns OK or ERROR (plus any flags describing
798 the error) without reading in a message. Client software should, in fact,
799 perform this operation at the beginning of an "enter message" command
800 *before* starting up its editor, so the user does not end up typing a message
801 in vain that will not be permitted to be saved. If it is set to 2, the
802 server will accept an "apparent" post name if the user is privileged enough.
803 This post name is arg 5.
804 1 - Recipient (To: field). This argument is utilized only for private
805 mail. It is ignored for public messages. It contains, of course, the name
806 of the recipient(s) of the message.
807 2 - Anonymous flag. This argument is ignored unless the room allows
808 anonymous messages. In such rooms, this flag may be set to 1 to flag a
809 message as anonymous, otherwise 0 for a normal message.
810 3 - Format type. Any valid Citadel format type may be used (this will
811 typically be 0; see the MSG0 command above).
812 4 - Subject. If present, this argument will be used as the subject of
814 5 - Post name. When postflag is 2, this is the name you are posting as.
815 This is an Aide only command.
816 6 - Do Confirmation. NOTE: this changes the protocol semantics! When
817 you set this to nonzero, ENT0 will reply with a confirmation message after
818 you submit the message text. The reply code for the ENT0 command will be
819 START_CHAT_MODE instead of SEND_LISTING.
820 7 - Recipient (Cc: field). This argument is utilized only for private
821 mail. It is ignored for public messages. It contains, of course, the name
822 of the recipient(s) of the message.
823 8 - Recipient (Bcc: field). This argument is utilized only for private
824 mail. It is ignored for public messages. It contains, of course, the name
825 of the recipient(s) of the message.
827 Possible result codes:
828 OK - The request is valid. (Client did not set the "post" flag, so the
829 server will not read in message text.) If the message is an e-mail with
830 a recipient, the text that follows the OK code will contain the exact name
831 to which mail is being sent. The client can display this to the user. The
832 implication here is that the name that the server returns will contain the
833 correct upper and lower case characters. In addition, if the recipient is
834 having his/her mail forwarded, the forwarding address will be returned.
835 SEND_LISTING - The request is valid. The client should now transmit
836 the text of the message (ending with a 000 on a line by itself, as usual).
837 START_CHAT_MODE - The request is valid. The client should now transmit
838 the text of the message, ending with a 000 on a line by itself. After
839 transmitting the 000 terminator, the client MUST read in the confirmation
840 from the server, which will also end with 000 on a line by itself. The format
841 of the confirmation appears below.
842 ERROR + NOT_LOGGED_IN - Not logged in.
843 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
844 explanation follows, worded in a form that can be displayed to the user.
845 ERROR + NO_SUCH_USER - The specified recipient does not exist.
847 The format of the confirmation message, if requested, is as follows:
848 Line 1: The new message number on the server for the message. It will be
849 positive for a real message number, or negative to denote
850 that an error occurred. If an error occurred, the message was
852 Line 2: A human-readable confirmation or error message.
853 Line 3: The resulting Exclusive UID of the message, if present.
854 (More may be added to this in the future, so do not assume that there will
855 only be these lines output. Keep reading until 000 is received.)
858 RINF (read Room INFormation file)
860 Each room has associated with it a text file containing a description of
861 the room, perhaps containing its intended purpose or other important
862 information. The info file for the Lobby> (the system's base room) is
863 often used as a repository for system bulletins and the like.
865 This command, which accepts no arguments, is simply used to read the info
866 file for the current room. It will return LISTING_FOLLOWS followed by
867 the text of the message (always in format type 0) if the request can be
868 honored, or ERROR if no info file exists for the current room (which is
869 often the case). Other error description codes may accompany this result.
871 When should this command be used? This is, of course, up to the discretion
872 of client software authors, but in Citadel it is executed in two situations:
873 the first time the user ever enters a room; and whenever the contents of the
874 file change. The latter can be determined from the result of a GOTO command,
875 which will tell the client whether the file needs to be read (see GOTO above).
878 DELE (DELEte a message)
880 Delete a message from the current room. The one argument that should be
881 passed to this command is the message number of the message to be deleted.
882 The return value will be OK if the message was deleted, or an ERROR code.
883 If the delete is successful, the message's reference count is decremented, and
884 if the reference count reaches zero, the message is removed from the message
888 MOVE (MOVE or copy a message to a different room)
890 Move or copy a message to a different room. This command expects to be
891 passed three arguments:
892 0: the message number of the message to be moved or copied.
893 1: the name of the target room.
894 2: flag: 0 to move the message, 1 to copy it without deleting from the
897 This command never creates or deletes copies of a message; it merely moves
898 around links. When a message is moved, its reference count remains the same.
899 When a message is copied, its reference count is incremented.
902 KILL (KILL current room)
904 This command deletes the current room. It accepts a single argument, which
905 should be nonzero to actually delete the room, or zero to merely check
906 whether the room can be deleted.
908 Once the room is deleted, the current room is undefined. It is suggested
909 that client software immediately GOTO another room (usually _BASEROOM_)
910 after this command completes.
912 Possible return codes:
914 OK - room has been deleted (or, if checking only, request is valid).
915 ERROR+NOT_LOGGED_IN - no user is logged in.
916 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
917 ERROR+NOT_HERE - this room can not be deleted.
920 CRE8 (CRE[ate] a new room)
922 This command is used to create a new room. Like some of the other
923 commands, it provides a mechanism to first check to see if a room can be
924 created before actually executing the command. CRE8 accepts the following
927 0 - Create flag. Set this to 1 to actually create the room. If it is
928 set to 0, the server merely checks that there is a free slot in which to
929 create a new room, and that the user has enough access to create a room. It
930 returns OK if the client should go ahead and prompt the user for more info,
931 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
932 1 - Name for new room.
933 2 - Access type for new room:
935 1 - Private; can be entered by guessing the room's name
936 2 - Private; can be entered by knowing the name *and* password
937 3 - Private; invitation only (sometimes called "exclusive")
938 4 - Personal (mailbox for this user only)
939 3 - Password for new room (if it is a type 2 room)
940 4 - Floor number on which the room should reside (optional)
941 5 - Set to 1 to avoid automatically gaining access to the created room.
942 6 - The default "view" for the room.
944 If the create flag is set to 1, the room is created (unless something
945 went wrong and an ERROR return is sent), and the server returns OK, but
946 the session is **not** automatically sent to that room. The client still
947 must perform a GOTO command to go to the new room.
950 FORG (FORGet the current room)
952 This command is used to forget (zap) the current room. For those not
953 familiar with Citadel, this terminology refers to removing the room from
954 a user's own known rooms list, *not* removing the room itself. After a
955 room is forgotten, it no longer shows up in the user's known room list,
956 but it will exist in the user's forgotten room list, and will return to the
957 known room list if the user goes to the room (in Citadel, this is
958 accomplished by explicitly typing the room's name in a <.G>oto command).
960 The command takes no arguments. If the command cannot execute for any
961 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
962 be returned as they apply.
964 If the command succeeds, OK will be returned. At this point, the current
965 room is **undefined**, and the client software is responsible for taking
966 the user to another room before executing any other room commands (usually
967 this will be _BASEROOM_ since it is always there).
970 MESG (read system MESsaGe)
972 This command is used to display system messages and/or help files. The
973 single argument it accepts is the name of the file to display. IT IS CASE
974 SENSITIVE. Citadel looks for these files first in the "messages"
975 subdirectory and then in the "help" subdirectory.
977 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
978 to the file being displayed. Then the message is printed, in format type 0
979 (see MSG0 command for more information on this). If the file is not found,
982 There are some "well known" names of system messages which client software
983 may expect most servers to carry:
985 hello - Welcome message, to be displayed before the user logs in.
986 changepw - To be displayed whenever the user is prompted for a new
987 password. Warns about picking guessable passwords and such.
988 register - Should be displayed prior to the user entering registration.
989 Warnings about not getting access if not registered, etc.
990 help - Main system help file.
991 goodbye - System logoff banner; display when user logs off.
992 roomaccess - Information about how public rooms and different types of
993 private rooms function with regards to access.
994 unlisted - Tells users not to choose to be unlisted unless they're
995 really paranoid, and warns that aides can still see
996 unlisted userlog entries.
998 Citadel provides these for the Citadel Unix text client. They are
999 probably not very useful for other clients:
1001 mainmenu - Main menu (when in idiot mode).
1006 saveopt - Options to save a message, abort, etc.
1007 entermsg - Displayed just before a message is entered, when in
1011 GNUR (Get Next Unvalidated User)
1013 This command shows the name of a user that needs to be validated. If there
1014 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
1015 along with the name of the first unvalidated user the server finds. All of
1016 the usual ERROR codes may be returned as well (for example, if the user is
1017 not an Aide and cannot validate users).
1019 A typical "Validate New Users" command would keep executing this command,
1020 and then validating each user it returns, until it returns OK when all new
1021 users have been validated.
1024 GREG (Get REGistration for user)
1026 This command retrieves the registration info for a user, whose name is the
1027 command's sole argument. All the usual error messages can be returned. If
1028 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
1029 (retrieved from the userlog, with the right upper and lower case etc.) The
1030 contents of the listing contains one field per line, followed by the usual
1031 000 on the last line.
1033 The following lines are defined. Others WILL be added in the futre, so all
1034 software should be written to read the lines it knows about and then ignore
1035 all remaining lines:
1040 Line 4: Street address or PO Box
1041 Line 5: City/town/village/etc.
1042 Line 6: State/province/etc.
1044 Line 8: Telephone number
1045 Line 9: Access level
1046 Line 10: Internet e-mail address
1049 Users without Aide privileges may retrieve their own registration using
1050 this command. This can be accomplished either by passing the user's own
1051 name as the argument, or the string "_SELF_". The command will always
1052 succeed when used in this manner, unless no user is logged in.
1055 VALI (VALIdate user)
1057 This command is used to validate users. Obviously, it can only be executed
1058 by users with Aide level access. It should be passed two parameters: the
1059 name of the user to validate, and the desired access level
1061 If the command succeeds, OK is returned. The user's access level is changed
1062 and the "need validation" bit is cleared. If the command fails for any
1063 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
1067 EINF (Enter INFo file for room)
1069 Transmit the info file for the current room with this command. EINF uses
1070 a boolean flag (1 or 0 as the first and only argument to the command) to
1071 determine whether the client actually wishes to transmit a new info file, or
1072 is merely checking to see if it has permission to do so.
1074 If the command cannot succeed, it returns ERROR.
1075 If the client is only checking for permission, and permission will be
1076 granted, OK is returned.
1077 If the client wishes to transmit the new info file, SEND_LISTING is
1078 returned, and the client should transmit the text of the info file, ended
1079 by the usual 000 on a line by itself.
1084 This is a simple user listing. It always succeeds, returning
1085 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
1086 fields on each line are as follows:
1091 4. Date/time of last login (Unix format)
1094 7. Password (listed only if the user requesting the list is an Aide)
1096 Unlisted entries will also be listed to Aides logged into the server, but
1097 not to ordinary users.
1099 The LIST command accepts an optional single argument, which is a simple,
1100 case-insensitive search string. If this argument is present, only usernames
1101 in which the search string is present will be returned. It is a simple
1102 substring search, not a regular expression search. If this string is empty
1103 or not present, all users will be returned.
1106 REGI (send REGIstration)
1108 Clients will use this command to transmit a user's registration info. If
1109 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
1110 SEND_LISTING is returned, and the server will expect the following information
1111 (terminated by 000 on a line by itself):
1114 Line 2: Street address or PO Box
1115 Line 3: City/town/village/etc.
1116 Line 4: State/province/etc.
1118 Line 6: Telephone number
1119 Line 7: e-mail address
1123 CHEK (CHEcK various things)
1125 When logging in, there are various things that need to be checked. This
1126 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
1127 it returns OK and the following parameters:
1129 0: Number of new private messages in Mail>
1130 1: Nonzero if the user needs to register
1131 2: (Relevant to Aides only) Nonzero if new users require validation
1132 3: The user's preferred Internet e-mail address
1135 DELF (DELete a File)
1137 This command deletes a file from the room's directory, if there is one. The
1138 name of the file to delete is the only parameter to be supplied. Wildcards
1139 are not acceptable, and any slashes in the filename will be converted to
1140 underscores, to prevent unauthorized access to neighboring directories. The
1141 possible return codes are:
1143 OK - Command succeeded. The file was deleted.
1144 ERROR+NOT_LOGGED_IN - Not logged in.
1145 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1146 ERROR+NOT_HERE - There is no directory in this room.
1147 ERROR+FILE_NOT_FOUND - Requested file was not found.
1152 This command is similar to DELF, except that it moves a file (and its
1153 associated file description) to another room. It should be passed two
1154 parameters: the name of the file to move, and the name of the room to move
1155 the file to. All of the same return codes as DELF may be returned, and also
1156 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1157 does not exist. ERROR+NOT_HERE could also mean that the target room does
1158 not have a directory.
1161 NETF (NETwork send a File)
1163 This command is similar to MOVF, except that it attempts to send a file over
1164 the network to another system. It should be passed two parameters: the name
1165 of the file to send, and the node name of the system to send it to. All of
1166 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1167 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1170 The name of the originating room will be sent along with the file. Most
1171 implementations will look for a room with the same name at the receiving end
1172 and attempt to place the file there, otherwise it goes into a bit bucket room
1173 for miscellaneous files. This is, however, beyond the scope of this document;
1174 see elsewhere for more details.
1177 RWHO (Read WHO's online)
1179 Displays a list of all users connected to the server. No error codes are
1180 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1181 lines containing the following three fields:
1183 0 - Session ID. Citadel fills this with the pid of a server program.
1185 2 - The name of the room the user is currently in. This field might not
1186 be displayed (for example, if the user is in a private room) or it might
1187 contain other information (such as the name of a file the user is
1189 3 - (server v4.03 and above) The name of the host the client is connecting
1190 from, or "localhost" if the client is local.
1191 4 - (server v4.04 and above) Description of the client software being used
1192 5 - The last time, locally to the server, that a command was received from
1193 this client (Note: NOOP's don't count)
1194 6 - The last command received from a client. (NOOP's don't count)
1195 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1196 (posting) and . (idle).
1197 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1198 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1199 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1200 11 - Nonzero if the session is a logged-in user, zero otherwise.
1202 The listing is terminated, as always, with the string "000" on a line by
1206 OPEN (OPEN a file for download)
1208 This command is used to open a file for downloading. Only one download
1209 file may be open at a time. The only argument to this command is the name
1210 of the file to be opened. The user should already be in the room where the
1211 file resides. Possible return codes are:
1214 ERROR+NOT_HERE (no directory in this room)
1215 ERROR+FILE_NOT_FOUND (could not open the file)
1219 If the file is successfully opened, OK will be returned, along with the
1220 size (in bytes) of the file, the time of last modification (if applicable),
1221 the filename (if known), and the MIME type of the file (if known).
1224 CLOS (CLOSe the download file)
1226 This command is used to close the download file. It returns OK if the
1227 file was successfully closed, or ERROR if there wasn't any file open in the
1231 READ (READ from the download file)
1233 Two arguments are passed to this command. The first is the starting position
1234 in the download file, and the second is the total number of bytes to be
1235 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1236 along with the number of bytes to follow. Then, immediately following the
1237 newline, will be that many bytes of binary data. The client *must* read
1238 exactly that number of bytes, otherwise the client and server will get out
1241 If the operation cannot be performed, any of the usual error codes will be
1245 UOPN (OPeN a file for Uploading)
1247 This command is similar to OPEN, except that this one is used when the
1248 client wishes to upload a file to the server. The first argument is the name
1249 of the file to create, and the second argument is a one-line comment
1250 describing the contents of the file. Only one upload file may be open at a
1251 time. Possible return codes are:
1254 ERROR+NOT_HERE (no directory in this room)
1255 ERROR+FILE_NOT_FOUND (a name must be specified)
1256 ERROR (miscellaneous errors)
1257 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1260 If OK is returned, the command has succeeded and writes may be performed.
1263 UCLS (CLoSe the Upload file)
1265 Close the file opened with UOPN. An argument of "1" should be passed to
1266 this command to close and save the file; otherwise, the transfer will be
1267 considered aborted and the file will be deleted. This command returns OK
1268 if the operation succeeded or ERROR if it did not.
1271 WRIT (WRITe to the upload file)
1273 If an upload file is open, this command may be used to write to it. The
1274 argument passed to this command is the number of bytes the client wishes to
1275 transmit. An ERROR code will be returned if the operation cannot be
1278 If the operation can be performed, SEND_BINARY will be returned, followed
1279 by the number of bytes the server is expecting. The client must then transmit
1280 exactly that number of bytes. Note that in the current implementation, the
1281 number of bytes the server is expecting will always be the number of bytes
1282 the client requested to transmit, but the client software should never assume
1283 that this will always happen, in case changes are made later.
1286 QUSR (Query for a USeR)
1288 This command is used to check to see if a particular user exists. The only
1289 argument to this command is the name of the user being searched for. If
1290 the user exists, OK is returned, along with the name of the user in the userlog
1291 (so the client software can learn the correct upper/lower casing of the name
1292 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1293 No login or current room is required to utilize this command.
1296 OIMG (Open an IMaGe file)
1298 Open an image (graphics) file for downloading. Once opened, the file can be
1299 read as if it were a download file. This implies that an image and a download
1300 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1302 All images will be in GIF (Graphics Interchange Format). In the case of
1303 Citadel, the server will convert the supplied filename to all lower case,
1304 append the characters ".gif" to the filename, and look for it in the "images"
1305 subdirectory. As with the MESG command, there are several "well known"
1306 images which are likely to exist on most servers:
1308 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1309 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1310 background - Background image (usually tiled) for graphical clients
1312 The following "special" image names are defined in Citadel server version
1315 _userpic_ - Picture of a user (send the username as the second argument)
1316 _floorpic_ - A graphical floor label (send the floor number as the second
1317 argument). Clients which request a floor picture will display
1318 the picture *instead* of the floor name.
1319 _roompic_ - A graphic associated with the *current* room. Clients which
1320 request a room picture will display the picture in *addition*
1321 to the room name (i.e. it's used for a room banner, as
1322 opposed to the floor picture's use in a floor listing).
1325 NETP (authenticate as network session with connection NET Password)
1327 This command is used by client software to identify itself as a transport
1328 session for Citadel site-to-site networking. It should be called with
1329 two arguments: the node name of the calling system, and the "shared secret"
1330 password for that connection. If the authentication succeeds, NETP will
1331 return OK, otherwise, it returns ERROR.
1334 NSYN (Network SYNchronize room)
1336 This command can be used to synchronize the contents of a room on the
1337 network. It is only usable by Aides. It accepts one argument: the name of
1338 a network node (which must be a valid one).
1340 When NSYN is run, the *entire* contents of the current room will be spooled
1341 to the specified node, without regard to whether any of the messages have
1342 already undergone network processing. It is up to the receiving node to
1343 check for duplicates (the Citadel networker does handle this) and avoid
1346 The command returns OK upon success or ERROR if the user is not an Aide.
1349 NUOP (Network Upload OPen file)
1351 Open a network spool file for uploading. The client must have already
1352 identified itself as a network session using the NETP command. If the command
1353 returns OK, the client may begin transmitting IGnet/Open spool data using
1354 a series of WRIT commands. When a UCLS command is issued, the spooled data
1355 is entered into the server if the argument to UCLS is 1 or discarded if the
1356 argument to UCLS is 0. If the client has not authenticated itself with a
1357 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1360 NDOP (Network Download OPen file)
1362 Open a network spool file for downloading. The client must have already
1363 identified itself as a network session using the NETP command. If the command
1364 returns OK, the client may begin receiving IGnet/Open spool data using
1365 a series of READ commands. When a CLOS command is issued, the spooled data
1366 is deleted from the server and may not be read again. If the client has not
1367 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1371 LFLR (List all known FLooRs)
1373 On systems supporting floors, this command lists all known floors. The
1374 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1375 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1376 the available floors, each line consisting of three fields:
1378 1. The floor number associated with the floor
1379 2. The name of the floor
1380 3. Reference count (number of rooms on this floor)
1383 CFLR (Create a new FLooR)
1385 This command is used to create a new floor. It should be passed two
1386 arguments: the name of the new floor to be created, and a 1 or 0 depending
1387 on whether the client is actually creating a floor or merely checking to
1388 see if it has permission to create the floor. The user must be logged in
1389 and have Aide privileges to create a floor.
1391 If the command succeeds, it will return OK followed by the floor number
1392 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1393 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1394 followed by a description of why the command failed.
1399 This command is used to delete a floor. It should be passed two
1400 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1401 on whether the client is actually deleting the floor or merely checking to
1402 see if it has permission to delete the floor. The user must be logged in
1403 and have Aide privileges to delete a floor.
1405 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1406 they must be either deleted or moved to different floors first. This implies
1407 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1408 Aide> all reside on the Main Floor and cannot be deleted.
1410 If the command succeeds, it will return OK. Otherwise it will return
1411 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1412 followed by a description of why the command failed.
1417 Edit the parameters of a floor. The client may pass one or more parameters
1420 1. The number of the floor to be edited
1421 2. The desired new name
1423 More parameters may be added in the future. Any parameters not passed to
1424 the server will remain unchanged. A minimal command would be EFLR and a
1425 floor number -- which would do nothing. EFLR plus the floor number plus a
1426 floor name would change the floor's name.
1428 If the command succeeds, it will return OK. Otherwise it will return
1429 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1432 IDEN (IDENtify the client software)
1434 The client software has the option to identify itself to the server.
1435 Currently, the server does nothing with this information except to write
1436 it to the syslog to satisfy the system administrator's curiosity. Other
1437 uses might become apparent in the future.
1439 The IDEN command should contain five fields: a developer ID number (same as
1440 the server developer ID numbers in the INFO command -- please obtain one if
1441 you are a new developer), a client ID number (which does not have to be
1442 globally unique - only unique within the domain of the developer number),
1443 a version number, a free-form text string describing the client, and the name
1444 of the host the user is located at.
1446 It is up to the server to determine whether to accept the host name or to
1447 use the host name it has detected itself. Generally, if the client is
1448 running on a trusted host (either localhost or a well-known publically
1449 accessible client) it should use the host name transmitted by IDEN,
1450 otherwise it should use the host name it has detected itself.
1452 IDEN always returns OK, but since that's the only way it ever returns
1453 there's no point in checking the result code.
1456 IPGM (identify as an Internal ProGraM)
1458 IPGM is a low-level command that should not be used by normal user clients.
1459 It is used for various utilities to communicate with the server on the same
1460 host. For example, the "sendcommand" utility logs onto the server as an
1461 internal program in order to run arbitrary server commands. Since user clients
1462 do not utilize this command (or any of its companion commands), developers
1463 writing Citadel-compatible servers need not implement it.
1465 The sole argument to IPGM is the system's internal program password. This
1466 password is generated by the setup program and stored in the config file.
1467 Since internal programs have access to the config file, they know the correct
1470 IPGM returns OK for a correct authentication or ERROR otherwise.
1473 CHAT (enter CHAT mode)
1475 This command functions differently from every other command in the system. It
1476 is used to implement multi-user chat. For this to function, a new transfer
1477 mode, called START_CHAT_MODE, is implemented. If a client does not support
1478 chat mode, it should never send a CHAT command!
1480 In chat mode, messages may arrive asynchronously from the server at any
1481 time. The client may send messages at any time. This allows the arrival of
1482 messages without the client having to poll for them. Arriving messages will
1483 be of the form "user|message", where the "user" portion is, of course, the
1484 name of the user sending the message, and "message" is the message text.
1486 Chat mode ends when the server says it ends. The server will signal the end
1487 of chat mode by transmitting "000" on a line by itself. When the client reads
1488 this line, it must immediately exit from chat mode without sending any
1489 further traffic to the server. The next transmission sent to the server
1490 will be a regular server command.
1492 The Citadel server understands the following commands:
1493 /quit - Exit from chat mode (causes the server to do an 000 end)
1494 /who - List users currently in chat
1495 /whobbs - List users currently in chat and elsewhere
1496 /me - Do an irc-style action.
1497 /join - Join a new "room" in which all messages are only heard by
1498 people in that room.
1499 /msg - /msg <user> <msg> will send the msg to <user> only.
1500 /help - Print help information
1501 NOOP - Do nothing (silently)
1503 Any other non-empty string is treated as message text and will be broadcast
1504 to other users currently in chat.
1507 SEXP (Send instant message)
1509 This is one of two commands which implement instant messages (also known
1510 as "paging"). Commands ending in "...EXP" are so-named because we called
1511 them "express messages" before the industry standardized on the term
1512 "instant messages." When an instant message is sent, it will be
1513 logged in user to another. When an instant message is sent, it will be
1514 displayed the next time the target user executes a PEXP or GEXP command.
1516 The SEXP command accepts two arguments: the name of the user to send the
1517 message to, and the text of the message. If the message is successfully
1518 transmitted, OK is returned. If the target user is not logged in or if
1519 anything else goes wrong, ERROR is returned.
1521 If the server supports extended paging, sending a zero-length message
1522 merely checks for the presence of the requested user without actually sending
1523 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1524 the server to return SEND_LISTING if the requested user is logged in, and the
1525 client can then transmit a multi-line page.
1527 The reserved name "broadcast" may be used instead of a user name, to
1528 broadcast an instant message to all users currently connected to the server.
1530 Do be aware that if an instant message is transmitted to a user who is logged
1531 in using a client that does not check for instant messages, the message will
1532 never be received. Also, instant messages are NOT sent via the following
1533 transports: SMTP, POP3.
1536 PEXP (Print instant messages) ***DEPRECATED***
1538 This command is deprecated; it will eventually disappear from the protocol and
1539 its use is not recommended. Please use the GEXP command instead.
1541 Called without any arguments, PEXP simply dumps out the contents
1542 of any waiting instant messages. It returns ERROR if there is a problem,
1543 otherwise it returns LISTING_FOLLOWS followed by all messages.
1545 So how does the client know there are instant messages waiting? It could
1546 execute a random PEXP every now and then. Or, it can check the byte in
1547 server return code messages, between the return code and the parameters. In
1548 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1549 an "*" in this position to signify the presence of waiting instant messages.
1552 EBIO (Enter BIOgraphy)
1554 Transmit to the server a free-form text file containing a little bit of
1555 information about the user for other users to browse. This is typically
1556 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1557 after which the client is expected to transmit the file, or any of the usual
1558 ERROR codes if it fails.
1561 RBIO (Read BIOgraphy)
1563 Receive from the server a named user's bio. This command should be passed
1564 a single argument - the name of the user whose bio is requested. RBIO returns
1565 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1566 The return has the following parameters: the user name, user number, access
1567 level, date of last call, times called, and messages posted. This command
1568 returns ERROR+NO_SUCH_USER if the named user does not exist.
1570 RBIO no longer considers a user with no bio on file to be an error condition.
1571 It now returns a message saying the user has no bio on file as the text of the
1572 bio. This allows newer servers to operate with older clients.
1575 STEL (enter STEaLth mode)
1577 When in "stealth mode," a user will not show up in the "Who is online"
1578 listing (the RWHO server command). Only Aides may use stealth mode. The
1579 STEL command accepts one argument: a 1 indicating that the user wishes to
1580 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1581 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1582 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide;
1583 followed by a 1 or 0 indicating the new state.
1585 If any value other than 1 or 0 is sent by the client, the server simply
1586 replies with 1 or 0 to indicate the current state without changing it.
1588 The STEL command also makes it so a user does not show up in the chat room
1592 LBIO (List users who have BIOs on file)
1594 This command is self-explanatory. Any user who has used EBIO to place a bio
1595 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1596 this listing, unless it experiences an internal error in which case ERROR
1600 MSG2 (read MeSsaGe, mode 2)
1602 MSG2 follows the same calling convention as MSG0. The difference between
1603 the two commands is that MSG2 outputs messages in standard RFC822 format
1604 rather than in Citadel proprietary format.
1606 This command was implemented in order to make various gateway programs
1607 easier to implement, and to provide some sort of multimedia support in the
1608 future. Keep in mind that when this command is used, all messages will be
1609 output in fixed 80-column format.
1612 MSG3 (read MeSsaGe, mode 3 -- internal command)
1614 MSG3 is for use by internal programs only and should not be utilized by
1615 user-mode clients. It does require IPGM authentication. MSG3 follows the
1616 same calling convention as the other MSG commands, but upon success returns
1617 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1621 TERM (TERMinate another session)
1623 In a multithreaded environment, it sometimes becomes necessary to terminate
1624 a session that is unusable for whatever reason. The TERM command performs
1625 this task. Naturally, only Aides can execute TERM. The command should be
1626 called with a single argument: the session ID (obtained from an RWHO command)
1627 of the session to be terminated.
1629 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1630 a client program is prohibited from terminating the session it is currently
1636 DOWN (shut DOWN the server)
1638 This command, which may only be executed by an Aide, immediately shuts down
1639 the server. It is only implemented on servers on which such an operation is
1640 possible, such as a multithreaded Citadel engine. The server does not restart.
1641 DOWN returns OK if the user is allowed to shut down the server, in which case
1642 the client program should expect the connection to be immediately broken.
1645 SCDN (Schedule or Cancel a shutDowN)
1647 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1648 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1649 set, the server will be shut down when there are no longer any users logged in.
1650 Any value other than 0 or 1 will not change the flag, only report its state.
1651 No users will be kicked off the system, and in fact the server is still
1652 available for new connections. The command returns ERROR if it fails;
1653 otherwise, it returns OK followed by a number representing the current state
1657 EMSG (Enter a system MeSsaGe)
1659 This is the opposite of the MESG command - it allows the creation and editing
1660 of system messages. The only argument passed to EMSG is the name of the
1661 file being transmitted. If the file exists in any system message directory
1662 on the server it will be overwritten, otherwise a new file is created. EMSG
1663 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1666 Typical client software would use MESG to retrieve any existing message into
1667 an edit buffer, then present an editor to the user and run EMSG if the changes
1671 UIMG (Upload an IMaGe file)
1673 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1674 The first parameter supplied to UIMG should be 0 if the client is only checking
1675 for permission to upload, or 1 if the client is actually attempting to begin
1676 the upload operation. The second argument is the name of the file to be
1677 transmitted. In Citadel, the filename is converted to all lower case,
1678 appended with the characters ".gif", and stored in the "images" directory.
1680 UIMG returns OK if the client has permission to perform the requested upload,
1681 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1682 the operation (first parameter set to 1), an upload file is opened, and the
1683 client should begin writing to it with WRIT commands, then close it with a
1686 The supplied filename should be one of:
1688 -> _userpic_ (Server will attempt to write to the user's online photo)
1689 -> Any of the "well known" filenames described in the writeup for the
1693 HCHG (Hostname CHanGe)
1695 HCHG is a command, usable by any user, that allows a user to change their RWHO
1696 host value. This will mask a client's originating hostname from normal
1697 users; access level 6 and higher can see, in an extended wholist, the actual
1698 hostname the user originates from.
1700 The format of an HCHG command is:
1704 If a HCHG command is successful, the value OK (200) is returned.
1707 RCHG (Roomname CHanGe)
1709 RCHG is a command, usable by any user, that allows a user to change their RWHO
1710 room value. This will mask a client's roomname from normal users; access
1711 level 6 and higher can see, in an extended wholist, the actual room the user
1714 The format of an RCHG command is:
1718 If a RCHG command is successful, the value OK (200) is returned.
1721 UCHG (Username CHanGe)
1723 UCHG is an aide-level command which allows an aide to effectively change their
1724 username. If this value is blank, the user goes into stealth mode (see
1726 will show up as being from the real username in this mode, however. In
1727 addition, the RWHO listing will include both the spoofed and real usernames.
1729 The format of an UCHG command is:
1733 If a UCHG command is successful, the value OK (200) is returned.
1736 TIME (get server local TIME)
1738 TIME returns OK followed by the current time measured in seconds since
1739 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1741 This is used in allowing a client to calculate idle times.
1744 AGUP (Administrative Get User Parameters)
1745 ASUP (Administrative Set User Parameters)
1747 These commands are only executable by Aides and by server extensions running
1748 at system-level. They are used to get/set any and all parameters relating to
1749 a user account. AGUP requires only one argument: the name of the user in
1750 question. SGUP requires all of the parameters to be set. The parameters are
1751 as follows, and are common to both commands:
1755 2 - Flags (see citadel.h)
1760 7 - Timestamp of last call
1761 8 - Purge time (in days) for this user (or 0 to use system default)
1763 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1764 simply returns OK. If the client has insufficient access to perform the
1765 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1766 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1770 GPEX (Get Policy for message EXpiration)
1772 Returns the policy of the current room, floor, or site regarding the automatic
1773 purging (expiration) of messages. The following policies are available:
1774 0 - Fall back to the policy of the next higher level. If this is a room,
1775 use the floor's default policy. If this is a floor, use the system
1776 default policy. This is an invalid value for the system policy.
1777 1 - Do not purge messages automatically.
1778 2 - Purge by message count. (Requires a value: number of messages)
1779 3 - Purge by message age. (Requires a value: number of days)
1781 The format of this command is: GPEX <which>
1782 The value of <which> must be one of: "room" "floor" "site" "mailboxes"
1784 If successful, GPEX returns OK followed by <policy>|<value>.
1788 SPEX (Set Policy for message EXpiration)
1790 Sets the policy of the current room, floor, or site regarding the automatic
1791 purging (expiration) of messages. See the writeup for the GPEX command for
1792 the list of available policies.
1794 The format of this command is: SPEX <which>|<policy>|<value>
1795 The value of <which> must be one of: "room" "floor" "site" "mailboxes"
1797 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1801 CONF (get or set global CONFiguration options)
1803 Retrieves or sets various system-wide configuration and policy options. This
1804 command is only available to Aides. The sole parameter accepted is a command,
1805 which should be either GET or SET. If the GET command succeeds, CONF will
1806 return LISTING_FOLLOWS followed by the fields described below, one line at a
1807 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1808 the fields described below, one line at a time (don't worry about other fields
1809 being added in the future; if a 'short' configuration list is sent, the missing
1810 values at the end will be left unchanged on the system). If either command
1811 fails for any reason, ERROR is returned.
1813 The configuration lines are as follows:
1816 2. Fully qualified domain name
1817 3. Human-readable node name
1818 4. Landline telephone number of this system
1819 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1820 6. Server connection idle timeout (in seconds)
1821 7. Initial access level for new users
1822 8. Flag (0 or 1) - require registration for new users
1823 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1824 10. Name of twit room
1825 11. Text of <more> prompt
1826 12. Flag (0 or 1) - restrict access to Internet mail
1827 13. Geographic location of this system
1828 14. Name of the system administrator
1829 15. Number of maximum concurrent sessions allowed on the server
1830 16. (placeholder -- this field is no longer in use)
1831 17. Default purge time (in days) for users
1832 18. Default purge time (in days) for rooms
1833 19. Name of room to log instant messages to (or a zero-length name for none)
1834 20. Access level required to create rooms
1835 21. Maximum message length which may be entered into the system
1836 22. Minimum number of worker threads
1837 23. Maximum number of worker threads
1838 24. Port number for POP3 service
1839 25. Port number for SMTP service
1840 26. Flag (0 or 1) - strict RFC822 adherence - don't correct From: forgeries
1841 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1842 28. Port number for IMAP service
1843 29. How often (in seconds) to run the networker
1844 30. Flag (0 or 1) - disable self-service new user registration
1845 31. (placeholder -- this field is no longer in use)
1846 32. Hour (0 through 23) during which database auto-purge jobs are run
1847 33. Name of host where an LDAP service may be found
1848 34. Port number of LDAP service on above host
1851 37. Password for LDAP Bind DN
1852 38. Server IP address to listen on (or "0.0.0.0" for all addresses)
1853 39. Port number for SMTP MSA service
1854 40. Port number for IMAPS (SSL-encrypted IMAP)
1855 41. Port number for POP3S (SSL-encrypted POP3)
1856 42. Port number for SMTPS (SSL-encrypted SMTP)
1857 43. Flag (0 or 1) - enable full text search index
1858 44. Flag (0 or 1) - automatically cull database log files
1859 45. Flag (0 or 1) - enable IMAP "instant expunge" of deleted messages
1860 46. Flag (0 or 1) - allow unauthenticated SMTP clients to spoof my domains
1862 CONF also accepts two additional commands: GETSYS and PUTSYS followed by an
1863 arbitrary MIME type (such as application/x-citadel-internet-config) which
1864 provides a means of storing generic configuration data in the Global System
1865 Configuration room without the need to add extra get/set commands to the
1868 Please note that the LDAP-specific configs have no effect on Citadel servers
1869 in which LDAP support is not enabled.
1873 MSG4 (read MeSsaGe, mode 4 -- output in preferred MIME format)
1875 This is the equivalent of MSG0, except it's a bit smarter about messages in
1876 rich text formats. Immediately following the "text" directive, the server
1877 will output RFC822-like MIME part headers such as "Content-type:" and
1878 "Content-length:". MIME formats are chosen and/or converted based on the
1879 client's preferred format settings, which are set using the MSGP command,
1882 The MSG4 command also accepts an optional second argument, which may be the
1883 MIME part specifier of an encapsulated message/rfc822 message. This is useful
1884 for fetching the encapsulated message instead of the top-level message, for
1885 example, when someone has forwarded a message as an attachment. Note that the
1886 only way for the client to know the part specifier is to fetch the top-level
1887 message and then look for attachments of type message/rfc822, and then call
1888 MSG4 again with that part specifier.
1893 MSGP (set MeSsaGe Preferred MIME format)
1895 Client tells the server what MIME content types it knows how to handle, and
1896 the order in which it prefers them. This is similar to an HTTP "Accept:"
1899 The parameters to a MSGP command are the client's acceptable MIME content
1900 types, in the order it prefers them (from most preferred to least preferred).
1901 For example: MSGP text/html|text/plain
1903 The MSGP command always returns OK.
1907 OPNA (OPeN Attachment)
1909 Opens, as a download file, a component of a MIME-encoded message. The two
1910 parameters which must be passed to this command are the message number and the
1911 name of the desired section. If the message or section does not exist, an
1912 appropriate ERROR code will be returned; otherwise, if the open is successful,
1913 this command will succeed returning the same information as an OPEN command.
1916 GEXP (Get instant messages)
1918 This is a more sophisticated way of retrieving instant messages than the old
1919 PEXP method. If there are no instant messages waiting, PEXP returns ERROR;
1920 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1922 0 - a boolean value telling the client whether there are any additional
1923 instant messages waiting following this one
1924 1 - a Unix-style timestamp
1925 2 - flags (see server.h for more info)
1926 3 - the name of the sender
1927 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1929 The text sent to the client will be the body of the instant message.
1931 So how does the client know there are instant messages waiting? It could
1932 execute a random GEXP every now and then. Or, it can check the byte in
1933 server return code messages, between the return code and the parameters. In
1934 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1935 an "*" in this position to signify the presence of waiting instant messages.
1938 FSCK (check message base reference counts)
1940 Verify, via the long way, that all message referenmce counts are correct. If
1941 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1942 by a transcript of the run. Otherwise ERROR is returned.
1945 DEXP (Disable receiving instant messages)
1947 DEXP sets or clears the "disable instant messages" flag. Pass this command a
1948 1 or 0 to respectively set or clear the flag. When the "disable instant
1949 messages" flag is set, no one except Aides may send the user instant messages.
1950 Any value other than 0 or 1 will not change the flag, only report its state.
1951 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1952 number representing the current state of the flag.
1955 REQT (REQuest client Termination)
1957 Request that the specified client (or all clients) log off. Aide level
1958 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1961 The REQT command accepts one parameter: the session ID of the client which
1962 should be terminated, or 0 for all clients. When successful, the REQT command
1965 It should be noted that REQT simply transmits an instant message to the
1966 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1967 this flag, and it is certainly possible for users to re-program their client
1968 software to ignore it. Therefore the effects of the REQT command should be
1969 considered advisory only. The recommended implementation practice is to first
1970 issue a REQT command, then wait a little while (from 30 seconds up to a few
1971 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1972 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1973 you are logging off users for the purpose of shutting down the server).
1976 SEEN (set or clear the SEEN flag for a message)
1978 Beginning with version 5.80, Citadel supports the concept of setting or
1979 clearing the "seen" flag for each individual message, instead of only allowing
1980 a "last seen" pointer. In fact, the old semantics are implemented in terms
1981 of the new semantics. This command requires two arguments: the number of the
1982 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1984 This command returns OK, unless the user is not logged in or a usage error
1985 occurred, in which case it returns ERROR. Please note that no checking is
1986 done on the supplied data; if the requested message does not exist, the SEEN
1987 command simply returns OK without doing anything.
1990 GTSN (GeT the list of SeeN messages)
1992 This command retrieves the list of "seen" (as opposed to unread) messages for
1993 the current room. It returns OK followed by an IMAP-format message list.
1996 SMTP (utility commands for the SMTP gateway)
1998 This command, accessible only by Aides, supports several utility operations
1999 which examine or manipulate Citadel's SMTP support. The first command argument
2000 is a subcommand telling the server what to do. The following subcommands are
2003 SMTP mx|hostname (display all MX hosts for 'hostname')
2004 SMTP runqueue (attempt immediate delivery of all messages
2005 in the outbound SMTP queue, ignoring any
2006 retry times stored there)
2009 STLS (Start Transport Layer Security)
2011 This command starts TLS on the current connection. The current
2012 implementation uses OpenSSL on both the client and server end. For future
2013 compatibility all clients must support at least TLSv1, and servers are
2014 guaranteed to support TLSv1. During TLS negotiation (see below) the server
2015 and client may agree to use a different protocol.
2017 The server returns ERROR if it does not support SSL or SSL initialization
2018 failed on the server; otherwise it returns OK. Once the server returns OK and
2019 the client has read the response, the server and client immediately negotiate
2020 TLS (in OpenSSL, using SSL_connect() on the client and SSL_accept() on the
2021 server). If negotiation fails, the server and client should attempt to resume
2022 the session unencrypted. If either end is unable to resume the session, the
2023 connection should be closed.
2025 This command may be run at any time.
2028 GTLS (Get Transport Layer Security Status)
2030 This command returns information about the current connection. The server
2031 returns OK plus several parameters if the connection is encrypted, and ERROR
2032 if the connection is not encrypted. It is primarily used for debugging. The
2033 command may be run at any time.
2035 0 - Protocol name, e.g. "SSLv3"
2036 1 - Cipher suite name, e.g. "ADH-RC4-MD5"
2037 2 - Cipher strength bits, e.g. 128
2038 3 - Cipher strength bits actually in use, e.g. 128
2041 IGAB (Initialize Global Address Book)
2043 This command creates, or re-creates, a database of Internet e-mail addresses
2044 using the vCard information in the Global Address Book room. This procedure
2045 is normally run internally when the server determines it necessary, but is
2046 also provided as a server command to be used as a troubleshooting/maintenenance
2047 tool. Only a system Aide can run the command. It returns OK on success or
2051 QDIR (Query global DIRectory)
2053 Look up an internet address in the global directory. Any logged-in user may
2054 call QDIR with one parameter, the Internet e-mail address to look up. QDIR
2055 returns OK followed by a Citadel address if there is a match, otherwise it
2056 returns ERROR+NOT_LOGGED_IN.
2059 ISME (find out if an e-mail address IS ME)
2061 This is a quickie shortcut command to find out if a given e-mail address
2062 belongs to the user currently logged in. Its sole argument is an address to
2063 parse. The supplied address may be in any format (local, IGnet, or Internet).
2064 The command returns OK if the address belongs to the user, ERROR otherwise.
2067 VIEW (set the VIEW for a room)
2069 Set the preferred view for the current user in the current room. Please see
2070 views.txt for more information on views. The sole parameter for this command
2071 is the type of view requested. VIEW returns OK on success or ERROR on failure.
2074 QNOP (Quiet No OPeration)
2076 This command does nothing, similar to the NOOP command. However, unlike the
2077 NOOP command, it returns *absolutely no response* at all. The client has no
2078 way of knowing that the command executed. It is intended for sending
2079 "keepalives" in situations where a full NOOP would cause the client protocol
2082 Naturally, sending this command to a server that doesn't support it is an
2083 easy way to mess things up. Therefore, client software should first check
2084 the output of an INFO command to ensure that the server supports quiet noops.
2088 ICAL (Internet CALendaring commands)
2090 This command supports a number of subcommands which are used to process the
2091 calendaring/scheduling support in Citadel. Here are the subcommands which
2095 Test server for calendaring support. Always returns OK unless the server
2096 does not have the calendar module enabled.
2098 ICAL respond|msgnum|partnum|action
2099 Respond to a meeting request. 'msgnum' and 'partnum' refer to a MIME-encoded
2100 meeting invitation in the current room. 'action' must be set to either
2101 "accept" or "decline" to determine the action to take. This subcommand will
2102 return either OK or ERROR.
2104 ICAL conflicts|msgnum|partnum
2105 Determine whether an incoming VEVENT will fit in the user's calendar by
2106 checking it against the existing VEVENTs. 'msgnum' and 'partnum' refer to
2107 a MIME-encoded meeting invitation in the current room (usually the inbox).
2108 This command may return ERROR if something went wrong, but usually it will
2109 return LISTING_FOLLOWS followed by a list of zero or more conflicting
2110 events. A zero-length list means that there were no conflicts.
2112 ICAL handle_rsvp|msgnum|partnum
2113 Handle an incoming "reply" (or RSVP) to a meeting request you sent out.
2114 'msgnum' and 'partnum' refer to a MIME-encoded reply in the current room.
2115 'action' must be set to either "update" or "ignore" to determine the action
2116 to take. If the action is "update" then the server will hunt for the meeting
2117 in the user's Calendar> room, and update the status for this attendee. Either
2118 way, the reply message is deleted from the current room. This subcommand will
2119 return either OK or ERROR.
2121 ICAL freebusy|username
2122 Output the free/busy times for the requested user. If the user specified
2123 has a calendar available, this command will return LISTING_FOLLOWS and a
2124 compound VCALENDAR object. That object, in turn, will contain VEVENT
2125 objects that have been stripped of all properties except for the bare
2126 minimum needed to learn free/busy times (such as DTSTART, DTEND, and
2127 TRANSP). If there is no such user, or no calendar available, the usual
2128 ERROR codes will be returned.
2132 Readers who are paying attention will notice that there is no subcommand to
2133 send out meeting invitations. This is because that task can be handled
2134 automatically by the Citadel server. Issue this command with <bool> set to 1
2135 to enable Server Generated Invitations. In this mode, when an event is saved
2136 to the user's Calendar> room and it contains attendees, Citadel will
2137 automatically turn the event into vCalendar REQUEST messages and mail them
2138 out to all listed attendees. If for some reason the client needs to disable
2139 Server Generated Invitations, the command may be sent again with <bool> = 0.
2143 MRTG (Multi Router Traffic Grapher)
2145 Multi Router Traffic Grapher (please see http://www.mrtg.org for more info) is
2146 a tool which creates pretty graphs of network activity, usually collected from
2147 routers using SNMP. However, its ability to call external scripts has spawned
2148 a small community of people using it to graph anything which can be graphed.
2149 The MRTG command can output Citadel server activity in the format MRTG expects.
2151 This format is as follows:
2156 Line 3: uptime of system
2157 Line 4: name of system
2160 MRTG accepts two different keywords. "MRTG users" will return two variables,
2161 the number of connected users and the number of active users. "MRTG messages"
2162 will return one variable (and a zero in the second field), showing the current
2163 highest message number on the system. Any other keyword, or a missing keyword,
2164 will cause the MRTG command to return an ERROR code.
2166 Please get in touch with the Citadel developers if you wish to experiment with
2171 GNET (Get NETwork configuration for this room)
2172 SNET (Set NETwork configuration for this room)
2174 These commands get/set the network configuration for the current room. Aide
2175 or Room Aide privileges are required, otherwise an ERROR code is returned.
2176 If the command succeeds, LISTING_FOLLOWS or SEND_LISTING is returned. The
2177 network configuration for a specific room includes neighbor nodes with whom
2178 the room is shared, and mailing list recipients. The format of the network
2179 configuration is described in the file "netconfigs.txt".
2183 ASYN (ASYNchronous message support)
2185 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
2186 only parameter specified should be 1 or 0 to indicate that the client can or
2187 cannot handle this type of messages. The server will reply OK followed by a
2188 1 or 0 to tell the client which mode it is now operating in.
2190 If the command is not available on the server (i.e. it returns ERROR), or
2191 if the command has not been executed by the client, it should be assumed that
2192 this mode of operation is NOT in effect.
2194 The client may also send any value other than 0 or 1 to simply cause the
2195 server to output its current state without changing it.
2197 When asynchronous protocol mode is in effect, the client MUST handle any
2198 asynchronous messages as they arrive, before doing anything else.
2202 AUTO (AUTOcompletion of email addresses)
2204 The AUTO command is used by clients which want to request a list of email
2205 recipients whose names or email addresses match a partial string supplied by
2206 the client. This string is the only parameter passed to this command. The
2207 command will return ERROR if no user is logged in or if no address book could
2208 be found; otherwise, it returns LISTING_FOLLOWS followed by zero or more
2209 candidate recipients.
2213 SRCH (SeaRCH the message base)
2215 This command's implementation is incomplete and will be documented when it
2216 is finished. The current implementation accepts a search string as its sole
2217 argument, and will respond with LISTING_FOLLOWS followed by a list of
2218 messages (globally, not just in the current room) which contain ALL of the
2219 words in the search string. If the client desires an "exact phrase" match,
2220 it must then slow-search the text of each returned message for the exact
2221 string. The client should also compare the returned message numbers against
2222 those which actually exist in the room or rooms being searched. In
2223 particular, clients should avoid telling the user about messages which exist
2224 only in rooms to which the user does not have access.
2226 Again, keep in mind that this is a temporary implementation and is not
2227 guaranteed to continue to exist in this form.
2230 EUID (get message number using an EUID)}
2232 Returns the message number, if present, of the message in the current room
2233 which is indexed using the supplied EUID (exclusive message ID). There can be
2234 only one message in a room with any given EUID; if another message arrives
2235 with the same EUID, the existing one is replaced. This makes it possible to
2236 reference things like calendar items using an immutable URL that does not
2237 change even when the message number changes due to an update.
2239 The format of this command is: EUID <euid>
2241 If successful, EUID returns OK followed by a message number.
2242 If no message exists in the current room with the supplied EUID, the command
2243 returns ERROR+MESSAGE_NOT_FOUND.
2249 ASYNCHRONOUS MESSAGES
2250 ---------------------
2252 When the client protocol is operating in asynchronous mode (please refer to
2253 the writeup of the ASYN command above), the following messages may arrive at
2257 902 (instant message arriving)
2259 One or more instant messages have arrived for this client.