1 SESSION LAYER PROTOCOL FOR CITADEL/UX
2 (c) 1995-2001 by Art Cancro et. al. All Rights Reserved
8 This is an attempt to document the session layer protocol used by the
9 Citadel/UX 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/UX project is Art Cancro
27 <ajc@uncensored.citadel.org>.
30 CONNECTING TO A SERVER
31 ----------------------
33 The protocols used below the session layer are beyond the scope of this
34 document, but we will briefly cover the methodology employed by Citadel/UX.
36 Citadel/UX offers Citadel BBS service using TCP/IP. It does so via a
37 multithreaded server listening on a TCP port. Older (4.xx) versions employed
38 an inetd-based server.
40 The port number officially assigned to Citadel by the IANA is 504/tcp. Since
41 our session layer assumes a clean, reliable, sequenced connection, the use
42 of UDP would render the server unstable and unusable, so we stick with TCP.
45 GENERAL INFORMATION ABOUT THE SERVER
46 ------------------------------------
48 The server is connection-oriented and stateful: each client requires its own
49 connection to a server process, and when a command is sent, the client must
50 read the response, and then transfer data or change modes if necessary.
52 The session layer is very much like other Internet protocols such as SMTP
53 or NNTP. A client program sends one-line commands to the server, and the
54 server responds with a three-digit numeric result code followed by a message
55 describing what happened. This cycle continues until the end of the
58 Unlike protocols such as FTP, all data transfers occur in-band. This means
59 that the same connection that is used for exchange of client/server
60 messages, will also be used to transfer data back and forth. (FTP opens a
61 separate connection for data transfers.) This keeps protocol administration
62 straightforward, as it can traverse firewalls without any special protocol
63 support on the firewall except for opening the port number.
69 The server will respond to all commands with a 3-digit result code, which
70 will be the first three characters on the line. The rest of the line may
71 contain a human-readable string explaining what happened. (Some client
72 software will display some of these strings to the user.)
74 The first digit is the most important. The following codes are defined for
75 this position: ERROR, OK, MORE_DATA, LISTING_FOLLOWS, and SEND_LISTING.
77 The second and third digits may provide a reason as to why a command
78 succeeded or failed. See ipcdef.h for the available codes.
80 ERROR means the command did not complete.
81 OK means the command executed successfully.
82 MORE_DATA means the command executed partially. Usually this means that
83 another command needs to be executed to complete the operation. For example,
84 sending the USER command to log in a user usually results in a MORE_DATA
85 result code, because the client needs to execute a PASS command to send the
86 password and complete the login.
87 LISTING_FOLLOWS means that after the server response, the server will
88 output a listing of some sort. The client *must* read the listing, whether
89 it wants to or not. The end of the listing is signified by the string
90 "000" on a line by itself.
91 SEND_LISTING is the opposite of LISTING_FOLLOWS. It means that the client
92 should begin sending a listing of some sort. The client *must* send something,
93 even if it is an empty listing. Again, the listing ends with "000" on a line
95 BINARY_FOLLOWS and SEND_BINARY mean that the client must immediately send
96 or receive a block of binary data. The first parameter will always be the
98 ASYNC_MESSAGE_FOLLOWS means that an asynchronous, or unsolicited, message
99 follows. The next line will be one of the above codes, and if a data transfer
100 is involved it must be handled immediately. Note that the client will not
101 receive this type of response unless it indicates to the server that it is
102 capable of handling them; see the writeup of the ASYN command later in this
108 Zero or more parameters may be passed to a command. When more than one
109 parameter is passed to a command, they should be separated by the "|"
112 In this example, we're using the "SETU" command and passing three
113 parameters: 80, 24, and 260.
115 When the server spits out data that has parameters, if more than one
116 parameter is returned, they will be separated by the "|" symbol like
119 In this example, we just executed the "GETU" command, and it returned us
120 an OK result code (the '2' in the 200) and three parameters: 80, 24, and
127 This is a listing of all the commands that a Citadel/UX server can execute.
132 This command does nothing. It takes no arguments and always returns
133 OK. It is intended primarily for testing and development, but it might also
134 be used as a "keep alive" command to prevent the server from timing out, if
135 it's running over a transport that needs this type of thing.
138 ECHO (ECHO something)
140 This command also does nothing. It simply returns OK followed by whatever
146 Terminate the server connection. This command takes no arguments. It
147 returns OK and closes the connection immediately.
152 Log out the user without closing the server connection. It always returns
153 OK even if no user is logged in.
156 USER (send USER name)
158 The first step in logging in a user. This command takes one argument: the
159 name of the user to be logged in. If the user exists, a MORE_DATA return
160 code will be sent, which means the client should execute PASS as the next
161 command. If the user does not exist, ERROR is returned.
166 The second step in logging in a user. This command takes one argument: the
167 password for the user we are attempting to log in. If the password doesn't
168 match the correct password for the user we specified for the USER command,
169 or if a USER command has not been executed yet, ERROR is returned. If the
170 password is correct, OK is returned and the user is now logged in... and
171 most of the other server commands can now be executed. Along with OK, the
172 following parameters are returned:
174 0 - The user's name (in case the client wants the right upper/lower casing)
175 1 - The user's current access level
178 4 - Various flags (see citadel.h)
180 6 - Time of last call (UNIX timestamp)
183 NEWU (create NEW User account)
185 This command creates a new user account and logs it in. The argument to
186 this command will be the name of the account. No case conversion is done
187 on the name. Note that the new account is installed with a default
188 configuration, and no password, so the client should immediately prompt the
189 user for a password and install it with the SETP command as soon as this
190 command completes. This command returns OK if the account was created and
191 logged in, or ERROR if another user already exists with this name. If OK,
192 it will also return the same parameters that PASS returns.
195 SETP (SET new Password)
197 This command sets a new password for the currently logged in user. The
198 argument to this command will be the new password. The command always
199 returns OK, unless the client is not logged in, in which case it will return
203 LKRN (List Known Rooms with New messages)
205 List known rooms with new messages. If the client is not logged in, ERROR
206 is returned. Otherwise, LISTING_FOLLOWS is returned, followed by the room
207 listing. Each line in the listing contains the full name of a room, followed
208 by the '|' symbol, and then a number that may contain the following bits:
211 #define QR_PERMANENT 1 /* Room does not purge */
212 #define QR_PRIVATE 4 /* Set for any type of private room */
213 #define QR_PASSWORDED 8 /* Set if there's a password too */
214 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
215 #define QR_DIRECTORY 32 /* Directory room */
216 #define QR_UPLOAD 64 /* Allowed to upload */
217 #define QR_DOWNLOAD 128 /* Allowed to download */
218 #define QR_VISDIR 256 /* Visible directory */
219 #define QR_ANONONLY 512 /* Anonymous-Only room */
220 #define QR_ANON2 1024 /* Anonymous-Option room */
221 #define QR_NETWORK 2048 /* Shared network room */
222 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
223 #define QR_READONLY 8192 /* Aide status required to post */
226 Other bits may be defined in the future. The listing terminates, as with
227 all listings, with "000" on a line by itself.
229 Starting with version 4.01 and above, floors are supported. The first
230 argument to LKRN should be the number of the floor to list rooms from. Only
231 rooms from this floor will be listed. If no arguments are passed to LKRN, or
232 if the floor number requested is (-1), rooms on all floors will be listed.
234 The third field displayed on each line is the number of the floor the room
235 is on. The LFLR command should be used to associate floor numbers with
238 The fourth field displayed on each line is a "room listing order." Unless
239 there is a compelling reason not to, clients should sort any received room
240 listings by this value.
244 LKRO (List Known Rooms with Old [no new] messages)
246 This follows the same usage and format as LKRN.
249 LZRM (List Zapped RooMs)
251 This follows the same usage and format as LKRN and LKRO.
254 LKRA (List All Known Rooms)
256 Same format. Lists all known rooms, with or without new messages.
259 LRMS (List all accessible RooMS)
261 Again, same format. This command lists all accessible rooms, known and
262 forgotten, with and without new messages. It does not, however, list
263 inaccessible private rooms.
266 GETU (GET User configuration)
268 This command retrieves the screen dimensions and user options for the
269 currently logged in account. ERROR will be returned if no user is logged
270 in, of course. Otherwise, OK will be returned, followed by four parameters.
271 The first parameter is the user's screen width, the second parameter is the
272 user's screen height, and the third parameter is a bag of bits with the
275 #define US_LASTOLD 16 /* Print last old message with new */
276 #define US_EXPERT 32 /* Experienced user */
277 #define US_UNLISTED 64 /* Unlisted userlog entry */
278 #define US_NOPROMPT 128 /* Don't prompt after each message */
279 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
280 #define US_PAGINATOR 2048 /* Pause after each screen of text */
282 There are other bits, too, but they can't be changed by the user (see below).
284 The fourth parameter, if present, is the moderation level this user is
288 SETU (SET User configuration)
290 This command does the opposite of SETU: it takes the screen dimensions and
291 user options (which were probably obtained with a GETU command, and perhaps
292 modified by the user) and writes them to the user account. This command
293 should be passed four parameters: the screen width, the screen height,
294 the option bits (see above), and the desired moderation level to filter at.
296 Note that there exist bits here which are not listed in this document. Some
297 are flags that can only be set by Aides or the system administrator. SETU
298 will ignore attempts to toggle these bits. There also may be more user
299 settable bits added at a later date. To maintain later downward compatibility,
300 the following procedure is suggested:
302 1. Execute GETU to read the current flags
303 2. Toggle the bits that we know we can toggle
304 3. Execute SETU to write the flags
306 If we are passed a bit whose meaning we don't know, it's best to leave it
307 alone, and pass it right back to the server. That way we can use an old
308 client on a server that uses an unknown bit without accidentally clearing
309 it every time we set the user's configuration.
314 This command is used to goto a new room. When the user first logs in (login
315 is completed after execution of the PASS command) this command is
316 automatically and silently executed to take the user to the first room in the
317 system (usually called the Lobby).
319 This command can be passed one or two parameters. The first parameter is,
320 of course, the name of the room. Although it is not case sensitive, the
321 full name of the room must be used. Wildcard matching or unique string
322 matching of room names should be the responsibility of the client.
324 Note that the reserved room name "_BASEROOM_" can be passed to the server
325 to cause the goto command to take the user to the first room in the system,
326 traditionally known as the Lobby>. As long as a user is logged in, a
327 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
328 allow client software to return to the base room when it doesn't know
331 There are also two additional reserved room names:
332 "_MAIL_" translates to the system's designated room for e-mail messages.
333 "_BITBUCKET_" goes to whatever room has been chosen for messages
336 The second (and optional) parameter is a password, if one is required for
337 access to the room. This allows for all types of rooms to be accessed via
338 this command: for public rooms, invitation-only rooms to which the user
339 has access, and preferred users only rooms to which the user has access, the
340 room will appear in a room listing. For guess-name rooms, this command
341 will work transparently, adding the room to the user's known room list when
342 it completes. For passworded rooms, access will be denied if the password
343 is not supplied or is incorrect, or the command will complete successfully
344 if the password is correct.
346 The possible result codes are:
348 OK - The command completed successfully. User is now in the room.
349 (See the list of returned parameters below)
351 ERROR - The command did not complete successfully. Check the second and
352 third positions of the result code to find out what happened:
354 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
355 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
356 password was incorrect.
357 NO_SUCH_ROOM - The requested room does not exist.
359 The typical procedure for entering a passworded room would be:
361 1. Execute a GOTO command without supplying any password.
362 2. ERROR+PASSWORD_REQUIRED will be returned. The client now knows that
363 the room is passworded, and prompts the user for a password.
364 3. Execute a GOTO command, supplying both the room name and the password.
365 4. If OK is returned, the command is complete. If, however,
366 ERROR+PASSWORD_REQUIRED is still returned, tell the user that the supplied
367 password was incorrect. The user remains in the room he/she was previously
370 When the command succeeds, these parameters are returned:
371 0. The name of the room
372 1. Number of unread messages in this room
373 2. Total number of messages in this room
374 3. Info flag: set to nonzero if the user needs to read this room's info
375 file (see RINF command below)
376 4. Various flags associated with this room. (See LKRN cmd above)
377 5. The highest message number present in this room
378 6. The highest message number the user has read in this room
379 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
380 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
381 a regular Aide (this makes access checks easy).
382 9. The number of new Mail messages the user has (useful for alerting the
383 user to the arrival of new mail during a session)
384 10. The floor number this room resides on
387 MSGS (get pointers to MeSsaGeS in this room)
389 This command obtains a listing of all the messages in the current room
390 which the client may request. This command may be passed a single parameter:
391 either "all", "old", or "new" to request all messages, only old messages, or
392 new messages. Or it may be passed two parameters: "last" plus a number, in
393 which case that many message pointers will be returned, or "first" plus a
394 number, for the corresponding effect. If no parameters are specified, "all"
397 In Citadel/UX 5.00 and above, the client may also specify "gt" plus a number,
398 to list all messages in the current room with a message number greater than
401 The third argument, valid only in Citadel/UX 5.60 and above, may be either
402 0 or 1. If it is 1, this command behaves differently: before a listing is
403 returned, the client must transmit a list of fields to search for. The field
404 headers are listed below in the writeup for the "MSG0" command.
406 This command can return three possible results. An ERROR code may be returned
407 if no user is currently logged in or if something else went wrong. Otherwise,
408 LISTING_FOLLOWS will be returned, and the listing will consist of zero or
409 more message numbers, one per line. The listing ends, as always, with the
410 string "000" alone on a line by itself. The listed message numbers can be used
411 to request messages from the system. If "search mode" is being used, the
412 server will return START_CHAT_MODE, and the client is expected to transmit
413 the search criteria, and then read the message list.
415 Since this is somewhat complex, here are some examples:
417 Example 1: Read all new messages
420 Server: 100 Message list...
426 Example 2: Read the last five messages
429 Server: 100 Message list...
437 Example 3: Read all messages written by "IGnatius T Foobar"
440 Server: 800 Send template then receive message list
441 Client: from|IGnatius T Foobar
455 Note that in "search mode" the client may specify any number of search
456 criteria. These criteria are applied with an AND logic.
460 MSG0 (read MeSsaGe, mode 0)
462 This is a command used to read the text of a message. "Mode 0" implies that
463 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
464 messages in more robust formats. This command should be passed two arguments.
465 The first is the message number of the message being requested. In server
466 version 4.04 and above, the second argument may be set to either 0 to read the
467 entire message, or 1 to read the headers only.
469 The server should, of course, make sure that the client actually has access
470 to the message being requested before honoring this request. Citadel/UX does
471 so by checking the message number against the contents of the current room. If
472 it's not there, the request is denied.
474 If the request is denied, an ERROR code will be returned. Otherwise, the
475 LISTING_FOLLOWS code will be returned, followed by the contents of the message.
476 The following fields may be sent:
478 type= Formatting type. The currently defined types are:
479 0 = "traditional" Citadel formatting. This means that newlines should be
480 treated as spaces UNLESS the first character on the next line is a space. In
481 other words, only indented lines should generate a newline on the user's screen
482 when the message is being displayed. This allows a message to be formatted to
483 the reader's screen width. It also allows the use of proportional fonts.
484 1 = a simple fixed-format message. The message should be displayed to
485 the user's screen as is, preferably in a fixed-width font that will fit 80
487 4 = MIME format message. The message text is expected to contain a header
488 with the "Content-type:" directive (and possibly others).
490 msgn= The message ID of this message on the system it originated on.
491 path= An e-mailable path back to the user who wrote the message.
493 time= The date and time of the message, in Unix format (the number of
494 seconds since midnight on January 1, 1970, GMT).
496 from= The name of the author of the message.
497 rcpt= If the message is a private e-mail, this is the recipient.
498 room= The name of the room the message originated in.
499 node= The short node name of the system this message originated on.
500 hnod= The long node name of the system this message originated on.
501 zaps= The id/node of a message which this one zaps (supersedes).
503 text Note that there is no "=" after the word "text". This string
504 signifies that the message text begins on the next line.
507 WHOK (WHO Knows room)
509 This command is available only to Aides. ERROR+HIGHER_ACCESS_REQUIRED will
510 be returned if the user is not an Aide. Otherwise, it returns
511 LISTING_FOLLOWS and then lists, one user per line, every user who has
512 access to the current room.
515 INFO (get server INFO)
517 This command will *always* return LISTING_FOLLOWS and then print out a
518 listing of zero or more strings. Client software should be written to expect
519 anywhere from a null listing to an infinite number of lines, to allow later
520 backward compatibility. The current implementation defines the following
521 parts of the listing:
523 Line 1 - Your unique session ID on the server
524 Line 2 - The node name of the server BBS
525 Line 3 - Human-readable node name of the server BBS
526 Line 4 - The fully-qualified domain name (FQDN) of the server
527 Line 5 - The name of the server software, i.e. "Citadel/UX 4.00"
528 Line 6 - (The revision level of the server code) * 100
529 Line 7 - The geographical location of the BBS (city and state if in the US)
530 Line 8 - The name of the system administrator
531 Line 9 - A number identifying the server type (see below)
532 Line 10 - The text of the system's paginator prompt
533 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
534 Line 12 - Paging level. 0 if the system only supports inline paging,
535 1 if the system supports "extended" paging (check-only and
536 multiline modes). See the SEXP command for further information.
537 Line 13 - The "nonce" for this session, for support of APOP-style
538 authentication. If this field is present, clients may authenticate
541 *** NOTE! *** The "server type" code is intended to promote global
542 compatibility in a scenario in which developers have added proprietary
543 features to their servers or clients. We are attempting to avoid a future
544 situation in which users need to keep different client software around for
545 each BBS they use. *Please*, if you are a developer and plan to add
546 proprietary features:
548 -> Your client programs should still be able to utilize servers other than
550 -> Clients other than your own should still be able to utilize your server,
551 even if your proprietary extensions aren't supported.
552 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
553 server type code, which can be assigned to your server program.
554 -> If you document what you did in detail, perhaps it can be added to a
555 future release of the Citadel/UX program, so everyone can enjoy it. Better
556 yet, just work with the Citadel development team on the main source tree.
558 If everyone follows this scheme, we can avoid a chaotic situation with lots
559 of confusion about which client program works with which server, etc. Client
560 software can simply check the server type (and perhaps the revision level)
561 to determine ahead of time what commands may be utilized.
563 Please refer to "developers.txt" for information on what codes belong to whom.
567 RDIR (Read room DIRectory)
569 Use this command to read the directory of a directory room. ERROR+NOT_HERE
570 will be returned if the room has no directory, or some other error; ERROR +
571 HIGHER_ACCESS_REQUIRED will be returned if the room's directory is not
572 visible and the user does not have Aide or Room Aide privileges; otherwise
573 LISTING_FOLLOWS will be returned, followed by the room's directory. Each
574 line of the directory listing will contain three fields: a filename, the
575 length of the file, and a description.
577 The server message contained on the same line with LISTING_FOLLOWS will
578 contain the name of the system and the name of the directory, such as:
579 uncensored.citadel.org|/usr/bbs/files/my_room_directory
582 SLRP (Set Last-message-Read Pointer)
584 This command marks all messages in the current room as read (seen) up to and
585 including the specified number. Its sole parameter
586 is the number of the last message that has been read. This allows the pointer
587 to be set at any arbitrary point in the room. Optionally, the parameter
588 "highest" may be used instead of a message number, to set the pointer to the
589 number of the highest message in the room, effectively marking all messages
590 in the room as having been read (ala the Citadel <G>oto command).
592 The command will return OK if the pointer was set, or ERROR if something
593 went wrong. If OK is returned, it will be followed by a single argument
594 containing the message number the last-read-pointer was set to.
597 INVT (INViTe a user to a room)
599 This command may only be executed by Aides, or by the room aide for the
600 current room. It is used primarily to add users to invitation-only rooms,
601 but it may also be used in other types of private rooms as well. Its sole
602 parameter is the name of the user to invite.
604 The command will return OK if the operation succeeded, or ERROR if it did
605 not. ERROR+HIGHER_ACCESS_REQUIRED may also be returned if the operation
606 would have been possible if the user had higher access, and ERROR+NOT_HERE
607 may be returned if the room is not a private room.
610 KICK (KICK a user out of a room)
612 This is the opposite of INVT: it is used to kick a user out of a private
613 room. It can also be used to kick a user out of a public room, but the
614 effect will only be the same as if the user <Z>apped the room - a non-stupid
615 user can simply un-zap the room to get back in.
618 GETR (GET Room attributes)
620 This command is used for editing the various attributes associated with a
621 room. A typical "edit room" command would work like this:
622 1. Use the GETR command to get the current attributes
623 2. Change some of them around
624 3. Use SETR (see below) to save the changes
625 4. Possibly also change the room aide using the GETA and SETA commands
627 GETR takes no arguments. It will only return OK if the SETR command will
628 also return OK. This allows client software to tell the user that he/she
629 can't edit the room *before* going through the trouble of actually doing the
630 editing. Possible return codes are:
632 ERROR+NOT_LOGGED_IN - No user is logged in.
633 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
634 and the room aide associated with the current room, can access this command.
635 ERROR+NOT_HERE - Lobby>, Mail>, and Aide> cannot be edited.
636 OK - Command succeeded. Parameters are returned.
638 If OK is returned, the following parameters will be returned as well:
640 0. The name of the room
641 1. The room's password (if it's a passworded room)
642 2. The name of the room's directory (if it's a directory room)
643 3. Various flags (bits) associated with the room (see LKRN cmd above)
644 4. The floor number on which the room resides
645 5. The room listing order
648 SETR (SET Room attributes)
650 This command sets various attributes associated with the current room. It
651 should be passed the following arguments:
653 0. The name of the room
654 1. The room's password (if it's a passworded room)
655 2. The name of the room's directory (if it's a directory room)
656 3. Various flags (bits) associated with the room (see LKRN cmd above)
657 4. "Bump" flag (see below)
658 5. The floor number on which the room should reside
659 6. The room listing order
661 *Important: You should always use GETR to retrieve the current attributes of
662 the room, then change what you want to change, and then use SETR to write it
663 all back. This is particularly important with respect to the flags: if a
664 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
665 only toggle the bits you want to toggle. This will allow for upward
668 If the room is a private room, you have the option of causing all users who
669 currently have access, to forget the room. If you want to do this, set the
670 "bump" flag to 1, otherwise set it to 0.
675 This command is used to get the name of the Room Aide for the current room.
676 It will return ERROR+NOT_LOGGED_IN if no user is logged in, ERROR if there
677 is no current room, or OK if the command succeeded. Along with OK there will
678 be returned one parameter: the name of the Room Aide.
683 The opposite of GETA, used to set the Room Aide for the current room. One
684 parameter should be passed, which is the name of the user who is to be the
685 new Room Aide. Under Citadel/UX, this command may only be executed by Aides
686 and by the *current* Room Aide for the room. Return codes possible are:
687 ERROR+NOT_LOGGED_IN (Not logged in.)
688 ERROR+HIGHER_ACCESS_REQUIRED (Higher access required.)
689 ERROR+NOT_HERE (No current room, or room cannot be edited.
690 Under Citadel/UX, the Lobby> Mail> and Aide> rooms are non-editable.)
691 OK (Command succeeded.)
694 ENT0 (ENTer message, mode 0)
696 This command is used to enter messages into the system. It accepts four
699 0 - Post flag. This should be set to 1 to post a message. If it is
700 set to 0, the server only returns OK or ERROR (plus any flags describing
701 the error) without reading in a message. Client software should, in fact,
702 perform this operation at the beginning of an "enter message" command
703 *before* starting up its editor, so the user does not end up typing a message
704 in vain that will not be permitted to be saved. If it is set to 2, the
705 server will accept an "apparent" post name if the user is privileged enough.
706 This post name is arg 4.
707 1 - Recipient. This argument is utilized only for private mail messages.
708 It is ignored for public messages. It contains, of course, the name of the
709 recipient of the message.
710 2 - Anonymous flag. This argument is ignored unless the room allows
711 anonymous messages. In such rooms, this flag may be set to 1 to flag a
712 message as anonymous, otherwise 0 for a normal message.
713 3 - Format type. Any valid Citadel/UX format type may be used (this will
714 typically be 0; see the MSG0 command above).
715 4 - Post name. When postflag is 2, this is the name you are posting as.
716 This is an Aide only command.
718 Possible result codes:
719 OK - The request is valid. (Client did not set the "post" flag, so the
720 server will not read in message text.) If the message is an e-mail with
721 a recipient, the text that follows the OK code will contain the exact name
722 to which mail is being sent. The client can display this to the user. The
723 implication here is that the name that the server returns will contain the
724 correct upper and lower case characters. In addition, if the recipient is
725 having his/her mail forwarded, the forwarding address will be returned.
726 SEND_LISTING - The request is valid. The client should now transmit
727 the text of the message (ending with a 000 on a line by itself, as usual).
728 ERROR - Miscellaneous error. (Explanation probably follows.)
729 ERROR + NOT_LOGGED_IN - Not logged in.
730 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
731 explanation follows, worded in a form that can be displayed to the user.
732 ERROR + NO_SUCH_USER - The specified recipient does not exist.
735 RINF (read Room INFormation file)
737 Each room has associated with it a text file containing a description of
738 the room, perhaps containing its intended purpose or other important
739 information. The info file for the Lobby> (the system's base room) is
740 often used as a repository for system bulletins and the like.
742 This command, which accepts no arguments, is simply used to read the info
743 file for the current room. It will return LISTING_FOLLOWS followed by
744 the text of the message (always in format type 0) if the request can be
745 honored, or ERROR if no info file exists for the current room (which is
746 often the case). Other error description codes may accompany this result.
748 When should this command be used? This is, of course, up to the discretion
749 of client software authors, but in Citadel it is executed in two situations:
750 the first time the user ever enters a room; and whenever the contents of the
751 file change. The latter can be determined from the result of a GOTO command,
752 which will tell the client whether the file needs to be read (see GOTO above).
755 DELE (DELEte a message)
757 Delete a message from the current room. The one argument that should be
758 passed to this command is the message number of the message to be deleted.
759 The return value will be OK if the message was deleted, or an ERROR code.
760 If the delete is successful, the message's reference count is decremented, and
761 if the reference count reaches zero, the message is removed from the message
765 MOVE (MOVE or copy a message to a different room)
767 Move a message to a different room. The two arguments that should be passed
768 to this command are the message number of the message to be deleted, and the
769 name of the target room. If the operation succeeds, the message will be
770 deleted from the current room and moved to the target room. An ERROR code
771 usually means that either the user does not have permission to perform this
772 operation, or that the target room does not exist.
774 In Citadel/UX 5.55 and above, a third argument may be specified: 0 or 1 to
775 designate whether the message should be moved (0) or copied (1) to the target
776 room. In the case of a "copy" operation, the message's reference count is
777 incremented, and a pointer to the message will exist in both the source *and*
778 target rooms. In the case of a "move" operation, the message pointer is
779 deleted from the source room and the reference count remains the same.
782 KILL (KILL current room)
784 This command deletes the current room. It accepts a single argument, which
785 should be nonzero to actually delete the room, or zero to merely check
786 whether the room can be deleted.
788 Once the room is deleted, the current room is undefined. It is suggested
789 that client software immediately GOTO another room (usually _BASEROOM_)
790 after this command completes.
792 Possible return codes:
794 OK - room has been deleted (or, if checking only, request is valid).
795 ERROR+NOT_LOGGED_IN - no user is logged in.
796 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
797 ERROR+NOT_HERE - this room can not be deleted.
800 CRE8 (CRE[ate] a new room)
802 This command is used to create a new room. Like some of the other
803 commands, it provides a mechanism to first check to see if a room can be
804 created before actually executing the command. CRE8 accepts the following
807 0 - Create flag. Set this to 1 to actually create the room. If it is
808 set to 0, the server merely checks that there is a free slot in which to
809 create a new room, and that the user has enough access to create a room. It
810 returns OK if the client should go ahead and prompt the user for more info,
811 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
812 1 - Name for new room.
813 2 - Access type for new room:
815 1 - Private; can be entered by guessing the room's name
816 2 - Private; can be entered by knowing the name *and* password
817 3 - Private; invitation only (sometimes called "exclusive")
818 3 - Password for new room (if it is a type 2 room)
819 4 - Floor number on which the room should reside (optional)
821 If the create flag is set to 1, the room is created (unless something
822 went wrong and an ERROR return is sent), and the server returns OK, but
823 the session is **not** automatically sent to that room. The client still
824 must perform a GOTO command to go to the new room.
827 FORG (FORGet the current room)
829 This command is used to forget (zap) the current room. For those not
830 familiar with Citadel, this terminology refers to removing the room from
831 a user's own known rooms list, *not* removing the room itself. After a
832 room is forgotten, it no longer shows up in the user's known room list,
833 but it will exist in the user's forgotten room list, and will return to the
834 known room list if the user goes to the room (in Citadel, this is
835 accomplished by explicitly typing the room's name in a <.G>oto command).
837 The command takes no arguments. If the command cannot execute for any
838 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
839 be returned as they apply.
841 If the command succeeds, OK will be returned. At this point, the current
842 room is **undefined**, and the client software is responsible for taking
843 the user to another room before executing any other room commands (usually
844 this will be _BASEROOM_ since it is always there).
847 MESG (read system MESsaGe)
849 This command is used to display system messages and/or help files. The
850 single argument it accepts is the name of the file to display. IT IS CASE
851 SENSITIVE. Citadel/UX looks for these files first in the "messages"
852 subdirectory and then in the "help" subdirectory.
854 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
855 to the file being displayed. Then the message is printed, in format type 0
856 (see MSG0 command for more information on this). If the file is not found,
859 There are some "well known" names of system messages which client software
860 may expect most servers to carry:
862 hello - Welcome message, to be displayed before the user logs in.
863 changepw - To be displayed whenever the user is prompted for a new
864 password. Warns about picking guessable passwords and such.
865 register - Should be displayed prior to the user entering registration.
866 Warnings about not getting access if not registered, etc.
867 help - Main system help file.
868 goodbye - System logoff banner; display when user logs off.
869 roomaccess - Information about how public rooms and different types of
870 private rooms function with regards to access.
871 unlisted - Tells users not to choose to be unlisted unless they're
872 really paranoid, and warns that aides can still see
873 unlisted userlog entries.
875 Citadel/UX provides these for the Citadel/UX Unix text client. They are
876 probably not very useful for other clients:
878 mainmenu - Main menu (when in idiot mode).
883 saveopt - Options to save a message, abort, etc.
884 entermsg - Displayed just before a message is entered, when in
888 GNUR (Get Next Unvalidated User)
890 This command shows the name of a user that needs to be validated. If there
891 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
892 along with the name of the first unvalidated user the server finds. All of
893 the usual ERROR codes may be returned as well (for example, if the user is
894 not an Aide and cannot validate users).
896 A typical "Validate New Users" command would keep executing this command,
897 and then validating each user it returns, until it returns OK when all new
898 users have been validated.
901 GREG (Get REGistration for user)
903 This command retrieves the registration info for a user, whose name is the
904 command's sole argument. All the usual error messages can be returned. If
905 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
906 (retrieved from the userlog, with the right upper and lower case etc.) The
907 contents of the listing contains one field per line, followed by the usual
908 000 on the last line.
910 The following lines are defined. Others WILL be added in the futre, so all
911 software should be written to read the lines it knows about and then ignore
917 Line 4: Street address or PO Box
918 Line 5: City/town/village/etc.
919 Line 6: State/province/etc.
921 Line 8: Telephone number
923 Line 10: Internet e-mail address
926 Users without Aide privileges may retrieve their own registration using
927 this command. This can be accomplished either by passing the user's own
928 name as the argument, or the string "_SELF_". The command will always
929 succeed when used in this manner, unless no user is logged in.
934 This command is used to validate users. Obviously, it can only be executed
935 by users with Aide level access. It should be passed two parameters: the
936 name of the user to validate, and the desired access level
938 If the command succeeds, OK is returned. The user's access level is changed
939 and the "need validation" bit is cleared. If the command fails for any
940 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
944 EINF (Enter INFo file for room)
946 Transmit the info file for the current room with this command. EINF uses
947 a boolean flag (1 or 0 as the first and only argument to the command) to
948 determine whether the client actually wishes to transmit a new info file, or
949 is merely checking to see if it has permission to do so.
951 If the command cannot succeed, it returns ERROR.
952 If the client is only checking for permission, and permission will be
953 granted, OK is returned.
954 If the client wishes to transmit the new info file, SEND_LISTING is
955 returned, and the client should transmit the text of the info file, ended
956 by the usual 000 on a line by itself.
961 This is a simple user listing. It always succeeds, returning
962 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
963 fields on each line are as follows:
968 4. Date/time of last login (Unix format)
971 7. Password (listed only if the user requesting the list is an Aide)
973 Unlisted entries will also be listed to Aides logged into the server, but
974 not to ordinary users.
977 REGI (send REGIstration)
979 Clients will use this command to transmit a user's registration info. If
980 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
981 SEND_LISTING is returned, and the server will expect the following information
982 (terminated by 000 on a line by itself):
985 Line 2: Street address or PO Box
986 Line 3: City/town/village/etc.
987 Line 4: State/province/etc.
989 Line 6: Telephone number
990 Line 7: e-mail address
994 CHEK (CHEcK various things)
996 When logging in, there are various things that need to be checked. This
997 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
998 it returns OK and the following parameters:
1000 0: Number of new private messages in Mail>
1001 1: Nonzero if the user needs to register
1002 2: (Relevant to Aides only) Nonzero if new users require validation
1005 DELF (DELete a File)
1007 This command deletes a file from the room's directory, if there is one. The
1008 name of the file to delete is the only parameter to be supplied. Wildcards
1009 are not acceptable, and any slashes in the filename will be converted to
1010 underscores, to prevent unauthorized access to neighboring directories. The
1011 possible return codes are:
1013 OK - Command succeeded. The file was deleted.
1014 ERROR+NOT_LOGGED_IN - Not logged in.
1015 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1016 ERROR+NOT_HERE - There is no directory in this room.
1017 ERROR+FILE_NOT_FOUND - Requested file was not found.
1022 This command is similar to DELF, except that it moves a file (and its
1023 associated file description) to another room. It should be passed two
1024 parameters: the name of the file to move, and the name of the room to move
1025 the file to. All of the same return codes as DELF may be returned, and also
1026 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1027 does not exist. ERROR+NOT_HERE could also mean that the target room does
1028 not have a directory.
1031 NETF (NETwork send a File)
1033 This command is similar to MOVF, except that it attempts to send a file over
1034 the network to another system. It should be passed two parameters: the name
1035 of the file to send, and the node name of the system to send it to. All of
1036 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1037 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1040 The name of the originating room will be sent along with the file. Most
1041 implementations will look for a room with the same name at the receiving end
1042 and attempt to place the file there, otherwise it goes into a bit bucket room
1043 for miscellaneous files. This is, however, beyond the scope of this document;
1044 see elsewhere for more details.
1047 RWHO (Read WHO's online)
1049 Displays a list of all users connected to the server. No error codes are
1050 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1051 lines containing the following three fields:
1053 0 - Session ID. Citadel/UX fills this with the pid of a server program.
1055 2 - The name of the room the user is currently in. This field might not
1056 be displayed (for example, if the user is in a private room) or it might
1057 contain other information (such as the name of a file the user is
1059 3 - (server v4.03 and above) The name of the host the client is connecting
1060 from, or "localhost" if the client is local.
1061 4 - (server v4.04 and above) Description of the client software being used
1062 5 - The last time, locally to the server, that a command was received from
1063 this client (Note: NOOP's don't count)
1064 6 - The last command received from a client. (NOOP's don't count)
1065 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1066 (posting) and . (idle).
1067 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1068 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1069 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1071 The listing is terminated, as always, with the string "000" on a line by
1075 OPEN (OPEN a file for download)
1077 This command is used to open a file for downloading. Only one download
1078 file may be open at a time. The only argument to this command is the name
1079 of the file to be opened. The user should already be in the room where the
1080 file resides. Possible return codes are:
1083 ERROR+NOT_HERE (no directory in this room)
1084 ERROR+FILE_NOT_FOUND (could not open the file)
1088 If the file is successfully opened, OK will be returned, along with the
1089 size (in bytes) of the file, the time of last modification (if applicable),
1090 the filename (if known), and the MIME type of the file (if known).
1093 CLOS (CLOSe the download file)
1095 This command is used to close the download file. It returns OK if the
1096 file was successfully closed, or ERROR if there wasn't any file open in the
1100 READ (READ from the download file)
1102 Two arguments are passed to this command. The first is the starting position
1103 in the download file, and the second is the total number of bytes to be
1104 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1105 along with the number of bytes to follow. Then, immediately following the
1106 newline, will be that many bytes of binary data. The client *must* read
1107 exactly that number of bytes, otherwise the client and server will get out
1110 If the operation cannot be performed, any of the usual error codes will be
1114 UOPN (OPeN a file for Uploading)
1116 This command is similar to OPEN, except that this one is used when the
1117 client wishes to upload a file to the server. The first argument is the name
1118 of the file to create, and the second argument is a one-line comment
1119 describing the contents of the file. Only one upload file may be open at a
1120 time. Possible return codes are:
1123 ERROR+NOT_HERE (no directory in this room)
1124 ERROR+FILE_NOT_FOUND (a name must be specified)
1125 ERROR (miscellaneous errors)
1126 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1129 If OK is returned, the command has succeeded and writes may be performed.
1132 UCLS (CLoSe the Upload file)
1134 Close the file opened with UOPN. An argument of "1" should be passed to
1135 this command to close and save the file; otherwise, the transfer will be
1136 considered aborted and the file will be deleted. This command returns OK
1137 if the operation succeeded or ERROR if it did not.
1140 WRIT (WRITe to the upload file)
1142 If an upload file is open, this command may be used to write to it. The
1143 argument passed to this command is the number of bytes the client wishes to
1144 transmit. An ERROR code will be returned if the operation cannot be
1147 If the operation can be performed, SEND_BINARY will be returned, followed
1148 by the number of bytes the server is expecting. The client must then transmit
1149 exactly that number of bytes. Note that in the current implementation, the
1150 number of bytes the server is expecting will always be the number of bytes
1151 the client requested to transmit, but the client software should never assume
1152 that this will always happen, in case changes are made later.
1155 QUSR (Query for a USeR)
1157 This command is used to check to see if a particular user exists. The only
1158 argument to this command is the name of the user being searched for. If
1159 the user exists, OK is returned, along with the name of the user in the userlog
1160 (so the client software can learn the correct upper/lower casing of the name
1161 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1162 No login or current room is required to utilize this command.
1165 OIMG (Open an IMaGe file)
1167 Open an image (graphics) file for downloading. Once opened, the file can be
1168 read as if it were a download file. This implies that an image and a download
1169 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1171 All images will be in GIF (Graphics Interchange Format). In the case of
1172 Citadel/UX, the server will convert the supplied filename to all lower case,
1173 append the characters ".gif" to the filename, and look for it in the "images"
1174 subdirectory. As with the MESG command, there are several "well known"
1175 images which are likely to exist on most servers:
1177 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1178 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1179 background - Background image (usually tiled) for graphical clients
1181 The following "special" image names are defined in Citadel/UX server version
1184 _userpic_ - Picture of a user (send the username as the second argument)
1185 _floorpic_ - A graphical floor label (send the floor number as the second
1186 argument). Clients which request a floor picture will display
1187 the picture *instead* of the floor name.
1188 _roompic_ - A graphic associated with the *current* room. Clients which
1189 request a room picture will display the picture in *addition*
1190 to the room name (i.e. it's used for a room banner, as
1191 opposed to the floor picture's use in a floor listing).
1194 NETP (authenticate as network session with system NET Password)
1196 This command is used by client software to identify itself as a transport
1197 session for IGnet/Open BBS to BBS networking. It should be called with
1198 two arguments: the node name of the calling system, and the system net
1199 password for the server. If the authentication succeeds, NETP will return
1200 OK, otherwise, it returns ERROR.
1203 NUOP (Network Upload OPen file)
1205 Open a network spool file for uploading. The client must have already
1206 identified itself as a network session using the NETP command. If the command
1207 returns OK, the client may begin transmitting IGnet/Open spool data using
1208 a series of WRIT commands. When a UCLS command is issued, the spooled data
1209 is entered into the BBS if the argument to UCLS is 1 or discarded if the
1210 argument to UCLS is 0. If the client has not authenticated itself with a
1211 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1214 NDOP (Network Download OPen file)
1216 Open a network spool file for downloading. The client must have already
1217 identified itself as a network session using the NETP command. If the command
1218 returns OK, the client may begin receiving IGnet/Open spool data using
1219 a series of READ commands. When a CLOS command is issued, the spooled data
1220 is deleted from the server and may not be read again. If the client has not
1221 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1225 LFLR (List all known FLooRs)
1227 On systems supporting floors, this command lists all known floors. The
1228 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1229 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1230 the available floors, each line consisting of three fields:
1232 1. The floor number associated with the floor
1233 2. The name of the floor
1234 3. Reference count (number of rooms on this floor)
1237 CFLR (Create a new FLooR)
1239 This command is used to create a new floor. It should be passed two
1240 arguments: the name of the new floor to be created, and a 1 or 0 depending
1241 on whether the client is actually creating a floor or merely checking to
1242 see if it has permission to create the floor. The user must be logged in
1243 and have Aide privileges to create a floor.
1245 If the command succeeds, it will return OK followed by the floor number
1246 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1247 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1248 followed by a description of why the command failed.
1253 This command is used to delete a floor. It should be passed two
1254 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1255 on whether the client is actually deleting the floor or merely checking to
1256 see if it has permission to delete the floor. The user must be logged in
1257 and have Aide privileges to delete a floor.
1259 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1260 they must be either deleted or moved to different floors first. This implies
1261 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1262 Aide> all reside on the Main Floor and cannot be deleted.
1264 If the command succeeds, it will return OK. Otherwise it will return
1265 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1266 followed by a description of why the command failed.
1271 Edit the parameters of a floor. The client may pass one or more parameters
1274 1. The number of the floor to be edited
1275 2. The desired new name
1277 More parameters may be added in the future. Any parameters not passed to
1278 the server will remain unchanged. A minimal command would be EFLR and a
1279 floor number -- which would do nothing. EFLR plus the floor number plus a
1280 floor name would change the floor's name.
1282 If the command succeeds, it will return OK. Otherwise it will return
1283 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1286 IDEN (IDENtify the client software)
1288 The client software has the option to identify itself to the server.
1289 Currently, the server does nothing with this information except to write
1290 it to the syslog to satisfy the system administrator's curiosity. Other
1291 uses might become apparent in the future.
1293 The IDEN command should contain five fields: a developer ID number (same as
1294 the server developer ID numbers in the INFO command -- please obtain one if
1295 you are a new developer), a client ID number (which does not have to be
1296 globally unique - only unique within the domain of the developer number),
1297 a version number, a free-form text string describing the client, and the name
1298 of the host the user is located at.
1300 It is up to the server to determine whether to accept the host name or to
1301 use the host name it has detected itself. Generally, if the client is
1302 running on a trusted host (either localhost or a well-known publically
1303 accessible client) it should use the host name transmitted by IDEN,
1304 otherwise it should use the host name it has detected itself.
1306 IDEN always returns OK, but since that's the only way it ever returns
1307 there's no point in checking the result code.
1310 IPGM (identify as an Internal ProGraM)
1312 IPGM is a low-level command that should not be used by normal user clients.
1313 It is used for various utilities to communicate with the server on the same
1314 host. For example, the "sendcommand" utility logs onto the server as an
1315 internal program in order to run arbitrary server commands. Since user clients
1316 do not utilize this command (or any of its companion commands), developers
1317 writing Citadel-compatible servers need not implement it.
1319 The sole argument to IPGM is the system's internal program password. This
1320 password is generated by the setup program and stored in the config file.
1321 Since internal programs have access to the config file, they know the correct
1324 IPGM returns OK for a correct authentication or ERROR otherwise.
1327 CHAT (enter CHAT mode)
1329 This command functions differently from every other command in the system. It
1330 is used to implement multi-user chat. For this to function, a new transfer
1331 mode, called START_CHAT_MODE, is implemented. If a client does not support
1332 chat mode, it should never send a CHAT command!
1334 In chat mode, messages may arrive asynchronously from the server at any
1335 time. The client may send messages at any time. This allows the arrival of
1336 messages without the client having to poll for them. Arriving messages will
1337 be of the form "user|message", where the "user" portion is, of course, the
1338 name of the user sending the message, and "message" is the message text.
1340 Chat mode ends when the server says it ends. The server will signal the end
1341 of chat mode by transmitting "000" on a line by itself. When the client reads
1342 this line, it must immediately exit from chat mode without sending any
1343 further traffic to the server. The next transmission sent to the server
1344 will be a regular server command.
1346 The Citadel/UX server understands the following commands:
1347 /quit - Exit from chat mode (causes the server to do an 000 end)
1348 /who - List users currently in chat
1349 /whobbs - List users currently in chat and on the bbs
1350 /me - Do an irc-style action.
1351 /join - Join a new "room" in which all messages are only heard by
1352 people in that room.
1353 /msg - /msg <user> <msg> will send the msg to <user> only.
1354 /help - Print help information
1355 NOOP - Do nothing (silently)
1357 Any other non-empty string is treated as message text and will be broadcast
1358 to other users currently in chat.
1361 SEXP (Send EXPress messages)
1363 This is one of two commands which implement "express messages" (also known
1364 as "paging"). An express message is a near-real-time message sent from one
1365 logged in user to another. When an express message is sent, it will be
1366 displayed the next time the target user executes a PEXP or GEXP command.
1368 The SEXP command accepts two arguments: the name of the user to send the
1369 message to, and the text of the message. If the message is successfully
1370 transmitted, OK is returned. If the target user is not logged in or if
1371 anything else goes wrong, ERROR is returned.
1373 If the server supports extended paging, sending a zero-length message
1374 merely checks for the presence of the requested user without actually sending
1375 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1376 the server to return SEND_LISTING if the requested user is logged in, and the
1377 client can then transmit a multi-line page.
1379 The reserved name "broadcast" may be used instead of a user name, to
1380 broadcast an express message to all users currently connected to the server.
1382 Do be aware that if an express message is transmitted to a user who is logged
1383 in using a client that does not check for express messages, the message will
1387 PEXP (Print EXPress messages) ***DEPRECATED***
1389 This command is deprecated; it will eventually disappear from the protocol and
1390 its use is not recommended. Please use the GEXP command instead.
1392 Called without any arguments, PEXP simply dumps out the contents
1393 of any waiting express messages. It returns ERROR if there is a problem,
1394 otherwise it returns LISTING_FOLLOWS followed by all messages.
1396 So how does the client know there are express messages waiting? It could
1397 execute a random PEXP every now and then. Or, it can check the byte in
1398 server return code messages, between the return code and the parameters. In
1399 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1400 an "*" in this position to signify the presence of waiting express messages.
1403 EBIO (Enter BIOgraphy)
1405 Transmit to the server a free-form text file containing a little bit of
1406 information about the user for other users to browse. This is typically
1407 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1408 after which the client is expected to transmit the file, or any of the usual
1409 ERROR codes if it fails.
1412 RBIO (Read BIOgraphy)
1414 Receive from the server a named user's bio. This command should be passed
1415 a single argument - the name of the user whose bio is requested. RBIO returns
1416 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1417 The return has the following parameters: the user name, user number, access
1418 level, date of last call, times called, and messages posted. This command
1419 returns ERROR+NO_SUCH_USER if the named user does not exist.
1421 RBIO no longer considers a user with no bio on file to be an error condition.
1422 It now returns a message saying the user has no bio on file as the text of the
1423 bio. This allows newer servers to operate with older clients.
1426 STEL (enter STEaLth mode)
1428 When in "stealth mode," a user will not show up in the "Who is online"
1429 listing (the RWHO server command). Only Aides may use stealth mode. The
1430 STEL command accepts one argument: a 1 indicating that the user wishes to
1431 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1432 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1433 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide.
1435 The STEL command also makes it so a user does not show up in the chat room
1439 LBIO (List users who have BIOs on file)
1441 This command is self-explanatory. Any user who has used EBIO to place a bio
1442 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1443 this listing, unless it experiences an internal error in which case ERROR
1447 MSG2 (read MeSsaGe, mode 2)
1449 MSG2 follows the same calling convention as MSG0. The difference between
1450 the two commands is that MSG2 outputs messages in standard RFC822 format
1451 rather than in Citadel/UX proprietary format.
1453 This command was implemented in order to make various gateway programs
1454 easier to implement, and to provide some sort of multimedia support in the
1455 future. Keep in mind that when this command is used, all messages will be
1456 output in fixed 80-column format.
1459 MSG3 (read MeSsaGe, mode 3 -- internal command)
1461 MSG3 is for use by internal programs only and should not be utilized by
1462 user-mode clients. It does require IPGM authentication. MSG3 follows the
1463 same calling convention as the other MSG commands, but upon success returns
1464 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1468 ENT3 (ENTer message, mode 3 -- internal command)
1470 ENT3 is for use by internal programs only and should not be utilized by
1471 user-mode clients. It does require IPGM authentication. This command posts
1472 a raw message straight into the message base without modification or performing
1473 any checks. It accepts the following arguments:
1475 0 - Post flag. This should be set to 1 to post a message. If it is
1476 set to 0, the server only returns OK or ERROR (plus any flags describing
1477 the error) without reading in a message. This is used to verify the operation
1478 before actually transmitting a message.
1479 1 - Recipient. This argument is utilized only for private mail messages.
1480 It is ignored for public messages. It contains, of course, the name of the
1481 recipient of the message.
1482 2 - The size (in bytes) of the message to be transmitted.
1484 ENT3 returns OK to tell the client that a message can be posted, ERROR if
1485 there would be a problem with the operation, or SEND_BINARY followed by a byte
1486 count if it is expecting the message to be transmitted.
1489 TERM (TERMinate another session)
1491 In a multithreaded environment, it sometimes becomes necessary to terminate
1492 a session that is unusable for whatever reason. The TERM command performs
1493 this task. Naturally, only Aides can execute TERM. The command should be
1494 called with a single argument: the session ID (obtained from an RWHO command)
1495 of the session to be terminated.
1497 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1498 a client program is prohibited from terminating the session it is currently
1504 NSET (Network SETup commands)
1506 Aides may use this command to configure the networker. This command's
1507 parameters are passed directly to the 'netsetup' command line utility. If
1508 netsetup returns a non-zero exit code, ERROR is returned, along with the
1509 error message (if any). If netsetup returns a zero (success) exit code,
1510 LISTING_FOLLOWS is returned, followed by zero or more lines of output (since
1511 netsetup may have information to display, such as a room or node list) and
1512 the usual '000' listing terminator.
1515 DOWN (shut DOWN the server)
1517 This command, which may only be executed by an Aide, immediately shuts down
1518 the server. It is only implemented on servers on which such an operation is
1519 possible, such as a multithreaded Citadel engine. The server does not restart.
1520 DOWN returns OK if the user is allowed to shut down the server, in which case
1521 the client program should expect the connection to be immediately broken.
1524 SCDN (Schedule or Cancel a shutDowN)
1526 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1527 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1528 set, the server will be shut down when there are no longer any users logged in.
1529 Any value other than 0 or 1 will not change the flag, only report its state.
1530 No users will be kicked off the system, and in fact the server is still
1531 available for new connections. The command returns ERROR if it fails;
1532 otherwise, it returns OK followed by a number representing the current state
1536 EMSG (Enter a system MeSsaGe)
1538 This is the opposite of the MESG command - it allows the creation and editing
1539 of system messages. The only argument passed to EMSG is the name of the
1540 file being transmitted. If the file exists in any system message directory
1541 on the server it will be overwritten, otherwise a new file is created. EMSG
1542 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1545 Typical client software would use MESG to retrieve any existing message into
1546 an edit buffer, then present an editor to the user and run EMSG if the changes
1550 UIMG (Upload an IMaGe file)
1552 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1553 The first parameter supplied to UIMG should be 0 if the client is only checking
1554 for permission to upload, or 1 if the client is actually attempting to begin
1555 the upload operation. The second argument is the name of the file to be
1556 transmitted. In Citadel/UX, the filename is converted to all lower case,
1557 appended with the characters ".gif", and stored in the "images" directory.
1559 UIMG returns OK if the client has permission to perform the requested upload,
1560 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1561 the operation (first parameter set to 1), an upload file is opened, and the
1562 client should begin writing to it with WRIT commands, then close it with a
1565 The supplied filename should be one of:
1567 -> _userpic_ (Server will attempt to write to the user's online photo)
1568 -> Any of the "well known" filenames described in the writeup for the
1572 HCHG (Hostname CHanGe)
1574 HCHG is a command, usable by any user, that allows a user to change their RWHO
1575 host value. This will mask a client's originating hostname from normal
1576 users; access level 6 and higher can see, in an extended wholist, the actual
1577 hostname the user originates from.
1579 The format of an HCHG command is:
1583 If a HCHG command is successful, the value OK (200) is returned.
1586 RCHG (Roomname CHanGe)
1588 RCHG is a command, usable by any user, that allows a user to change their RWHO
1589 room value. This will mask a client's roomname from normal users; access
1590 level 6 and higher can see, in an extended wholist, the actual room the user
1593 The format of an RCHG command is:
1597 If a RCHG command is successful, the value OK (200) is returned.
1600 UCHG (Username CHanGe)
1602 UCHG is an aide-level command which allows an aide to effectively change their
1603 username. If this value is blank, the user goes into stealth mode (see
1605 will show up as being from the real username in this mode, however. In
1606 addition, the RWHO listing will include both the spoofed and real usernames.
1608 The format of an UCHG command is:
1612 If a UCHG command is successful, the value OK (200) is returned.
1615 TIME (get server local TIME)
1617 TIME returns OK followed by the current time measured in seconds since
1618 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1620 This is used in allowing a client to calculate idle times.
1623 AGUP (Administrative Get User Parameters)
1624 ASUP (Administrative Set User Parameters)
1626 These commands are only executable by Aides and by server extensions running
1627 at system-level. They are used to get/set any and all parameters relating to
1628 a user account. AGUP requires only one argument: the name of the user in
1629 question. SGUP requires all of the parameters to be set. The parameters are
1630 as follows, and are common to both commands:
1634 2 - Flags (see citadel.h)
1639 7 - Timestamp of last call
1640 8 - Purge time (in days) for this user (or 0 to use system default)
1642 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1643 simply returns OK. If the client has insufficient access to perform the
1644 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1645 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1649 GPEX (Get Policy for message EXpiration)
1651 Returns the policy of the current room, floor, or site regarding the automatic
1652 purging (expiration) of messages. The following policies are available:
1653 0 - Fall back to the policy of the next higher level. If this is a room,
1654 use the floor's default policy. If this is a floor, use the system
1655 default policy. This is an invalid value for the system policy.
1656 1 - Do not purge messages automatically.
1657 2 - Purge by message count. (Requires a value: number of messages)
1658 3 - Purge by message age. (Requires a value: number of days)
1660 The format of this command is: GPEX <which>
1661 The value of <which> must be one of: "room" "floor" "site"
1663 If successful, GPEX returns OK followed by <policy>|<value>.
1667 SPEX (Set Policy for message EXpiration)
1669 Sets the policy of the current room, floor, or site regarding the automatic
1670 purging (expiration) of messages. See the writeup for the GPEX command for
1671 the list of available policies.
1673 The format of this command is: SPEX <which>|<policy>|<value>
1674 The value of <which> must be one of: "room" "floor" "site"
1676 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1680 CONF (get or set global CONFiguration options)
1682 Retrieves or sets various system-wide configuration and policy options. This
1683 command is only available to Aides. The sole parameter accepted is a command,
1684 which should be either GET or SET. If the GET command succeeds, CONF will
1685 return LISTING_FOLLOWS followed by the fields described below, one line at a
1686 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1687 the fields described below, one line at a time (don't worry about other fields
1688 being added in the future; if a 'short' configuration list is sent, the missing
1689 values at the end will be left unchanged on the system). If either command
1690 fails for any reason, ERROR is returned.
1692 The configuration lines are as follows:
1695 2. Fully qualified domain name
1696 3. Human-readable node name
1697 4. Landline telephone number of this system
1698 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1699 6. Server connection idle timeout (in seconds)
1700 7. Initial access level for new users
1701 8. Flag (0 or 1) - require registration for new users
1702 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1703 10. Name of twit room
1704 11. Text of <more> prompt
1705 12. Flag (0 or 1) - restrict access to Internet mail
1706 13. Geographic location of this system
1707 14. Name of the system administrator
1708 15. Number of maximum concurrent sessions allowed on the server
1709 16. Password for server-to-server networking
1710 17. Default purge time (in days) for users
1711 18. Default purge time (in days) for rooms
1712 19. Name of room to log express messages to (or a zero-length name for none)
1713 20. Access level required to create rooms
1714 21. Maximum message length which may be entered into the system
1715 22. Minimum number of worker threads
1716 23. Maximum number of worker threads
1717 24. Port number for POP3 service
1718 25. Port number for SMTP service
1719 26. Default moderation filter level for new users (-63 to +63)
1720 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1721 28. Port number for IMAP service
1722 29. How often (in seconds) to run the networker
1724 CONF also accepts two additional commands: GETSYS and PUTSYS followed by an
1725 arbitrary MIME type (such as application/x-citadel-internet-config) which
1726 provides a means of storing generic configuration data in the Global System
1727 Configuration room without the need to add extra get/set commands to the
1731 EXPI (EXPIre system objects)
1733 Begins purge operations for objects which, according to site policy, are
1734 "old" and should be removed. EXPI should be called with one argument, one of:
1736 "messages" (purge old messages out of each room)
1737 "users" (purge old users from the userlog)
1738 "rooms" (remove rooms which have not been posted in for some time)
1739 "visits" (purge dereferenced user/room relationship records)
1741 EXPI returns OK (probably after a long delay while it does its work) if it
1742 succeeds; otherwise it returns an ERROR code.
1744 This command is probably temporary, until we can work some sort of scheduler
1745 into the system. It is implemented in the serv_expire module.
1749 MSG4 (read MeSsaGe, mode 4 -- enumerate MIME parts)
1751 FIX ... do the writeup for this once it's done.
1755 OPNA (OPeN Attachment)
1757 Opens, as a download file, a component of a MIME-encoded message. The two
1758 parameters which must be passed to this command are the message number and the
1759 name of the desired section. If the message or section does not exist, an
1760 appropriate ERROR code will be returned; otherwise, if the open is successful,
1761 this command will succeed returning the same information as an OPEN command.
1764 GEXP (Get EXPress messages)
1766 This is a more sophisticated way of retrieving express messages than the old
1767 PEXP method. If there are no express messages waiting, PEXP returns ERROR;
1768 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1770 0 - a boolean value telling the client whether there are any additional
1771 express messages waiting following this one
1772 1 - a Unix-style timestamp
1773 2 - flags (see server.h for more info)
1774 3 - the name of the sender
1775 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1777 The text sent to the client will be the body of the express message.
1779 So how does the client know there are express messages waiting? It could
1780 execute a random GEXP every now and then. Or, it can check the byte in
1781 server return code messages, between the return code and the parameters. In
1782 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1783 an "*" in this position to signify the presence of waiting express messages.
1786 FSCK (check message base reference counts)
1788 Verify, via the long way, that all message referenmce counts are correct. If
1789 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1790 by a transcript of the run. Otherwise ERROR is returned.
1793 DEXP (Disable EXPress messages)
1795 DEXP sets or clears the "disable express messages" flag. Pass this command a
1796 1 or 0 to respectively set or clear the flag. When the "disable express
1797 messages" flag is set, no one except Aides may send the user express messages.
1798 Any value other than 0 or 1 will not change the flag, only report its state.
1799 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1800 number representing the current state of the flag.
1803 MMOD (MODerate a Message)
1805 Set or change the moderation level of a message. The two parameters passed
1806 to this command should be the message number and the desired moderation level.
1807 Please refer to the "moderation.txt" document for a description of some
1808 commonly used moderation levels.
1810 If the command succeeds, OK is returned. If the specified message does not
1811 exist in the current room, or if the specified moderation level is not within
1812 acceptable limits, ERROR+ILLEGAL_VALUE is returned. This command requires at
1813 least Room Aide access; if the calling user is not an Aide, or a Room Aide for
1814 the current room, ERROR+HIGHER_ACCESS_REQUIRED is returned.
1817 REQT (REQuest client Termination)
1819 Request that the specified client (or all clients) log off. Aide level
1820 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1823 The REQT command accepts one parameter: the session ID of the client which
1824 should be terminated, or 0 for all clients. When successful, the REQT command
1827 It should be noted that REQT simply transmits an express message to the
1828 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1829 this flag, and it is certainly possible for users to re-program their client
1830 software to ignore it. Therefore the effects of the REQT command should be
1831 considered advisory only. The recommended implementation practice is to first
1832 issue a REQT command, then wait a little while (from 30 seconds up to a few
1833 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1834 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1835 you are logging off users for the purpose of shutting down the server).
1838 SEEN (set or clear the SEEN flag for a message)
1840 Beginning with version 5.80, Citadel supports the concept of setting or
1841 clearing the "seen" flag for each individual message, instead of only allowing
1842 a "last seen" pointer. In fact, the old semantics are implemented in terms
1843 of the new semantics. This command requires two arguments: the number of the
1844 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1846 This command returns OK, unless the user is not logged in or a usage error
1847 occurred, in which case it returns ERROR. Please note that no checking is
1848 done on the supplied data; if the requested message does not exist, the SEEN
1849 command simply returns OK without doing anything.
1852 SMTP (utility commands for the SMTP gateway)
1854 This command, accessible only by Aides, supports several utility operations
1855 which examine or manipulate Citadel's SMTP support. The first command argument
1856 is a subcommand telling the server what to do. The following subcommands are
1859 SMTP mx|hostname (display all MX hosts for 'hostname')
1860 SMTP runqueue (attempt immediate delivery of all messages
1861 in the outbound SMTP queue, ignoring any
1862 retry times stored there)
1865 ASYN (ASYNchronous message support)
1867 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
1868 only parameter specified should be 1 or 0 to indicate that the client can or
1869 cannot handle this type of messages. The server will reply OK followed by a
1870 1 or 0 to tell the client which mode it is now operating in.
1872 If the command is not available on the server (i.e. it returns ERROR), or
1873 if the command has not been executed by the client, it should be assumed that
1874 this mode of operation is NOT in effect.
1876 The client may also send any value other than 0 or 1 to simply cause the
1877 server to output its current state without changing it.
1879 When asynchronous protocol mode is in effect, the client MUST handle any
1880 asynchronous messages as they arrive, before doing anything else.
1885 ASYNCHRONOUS MESSAGES
1886 ---------------------
1888 When the client protocol is operating in asynchronous mode (please refer to
1889 the writeup of the ASYN command above), the following messages may arrive at
1893 901 (express message arriving)
1895 There is an express message intended for this client. When the client
1896 receives this message, it MUST act as if it just sent a GEXP command (the data
1897 following the 901 message WILL be a LISTING_FOLLOWS data transfer; in fact,
1898 the current implementation simply executes a GEXP command internally).