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 TCP/504. 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.) We do this to allow the server to
62 function over transports which can only handle one session at a time (such
63 as a dialup connection).
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)
182 NEWU (create NEW User account)
184 This command creates a new user account and logs it in. The argument to
185 this command will be the name of the account. No case conversion is done
186 on the name. Note that the new account is installed with a default
187 configuration, and no password, so the client should immediately prompt the
188 user for a password and install it with the SETP command as soon as this
189 command completes. This command returns OK if the account was created and
190 logged in, or ERROR if another user already exists with this name. If OK,
191 it will also return the same parameters that PASS returns.
194 SETP (SET new Password)
196 This command sets a new password for the currently logged in user. The
197 argument to this command will be the new password. The command always
198 returns OK, unless the client is not logged in, in which case it will return
202 LKRN (List Known Rooms with New messages)
204 List known rooms with new messages. If the client is not logged in, ERROR
205 is returned. Otherwise, LISTING_FOLLOWS is returned, followed by the room
206 listing. Each line in the listing contains the full name of a room, followed
207 by the '|' symbol, and then a number that may contain the following bits:
210 #define QR_PERMANENT 1 /* Room does not purge */
211 #define QR_PRIVATE 4 /* Set for any type of private room */
212 #define QR_PASSWORDED 8 /* Set if there's a password too */
213 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
214 #define QR_DIRECTORY 32 /* Directory room */
215 #define QR_UPLOAD 64 /* Allowed to upload */
216 #define QR_DOWNLOAD 128 /* Allowed to download */
217 #define QR_VISDIR 256 /* Visible directory */
218 #define QR_ANONONLY 512 /* Anonymous-Only room */
219 #define QR_ANON2 1024 /* Anonymous-Option room */
220 #define QR_NETWORK 2048 /* Shared network room */
221 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
222 #define QR_READONLY 8192 /* Aide status required to post */
225 Other bits may be defined in the future. The listing terminates, as with
226 all listings, with "000" on a line by itself.
228 Starting with version 4.01 and above, floors are supported. The first
229 argument to LKRN should be the number of the floor to list rooms from. Only
230 rooms from this floor will be listed. If no arguments are passed to LKRN, or
231 if the floor number requested is (-1), rooms on all floors will be listed.
233 The third field displayed on each line is the number of the floor the room
234 is on. The LFLR command should be used to associate floor numbers with
237 The fourth field displayed on each line is a "room listing order." Unless
238 there is a compelling reason not to, clients should sort any received room
239 listings by this value.
243 LKRO (List Known Rooms with Old [no new] messages)
245 This follows the same usage and format as LKRN.
248 LZRM (List Zapped RooMs)
250 This follows the same usage and format as LKRN and LKRO.
253 LKRA (List All Known Rooms)
255 Same format. Lists all known rooms, with or without new messages.
258 LRMS (List all accessible RooMS)
260 Again, same format. This command lists all accessible rooms, known and
261 forgotten, with and without new messages. It does not, however, list
262 inaccessible private rooms.
265 GETU (GET User configuration)
267 This command retrieves the screen dimensions and user options for the
268 currently logged in account. ERROR will be returned if no user is logged
269 in, of course. Otherwise, OK will be returned, followed by four parameters.
270 The first parameter is the user's screen width, the second parameter is the
271 user's screen height, and the third parameter is a bag of bits with the
274 #define US_LASTOLD 16 /* Print last old message with new */
275 #define US_EXPERT 32 /* Experienced user */
276 #define US_UNLISTED 64 /* Unlisted userlog entry */
277 #define US_NOPROMPT 128 /* Don't prompt after each message */
278 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
279 #define US_PAGINATOR 2048 /* Pause after each screen of text */
281 There are other bits, too, but they can't be changed by the user (see below).
283 The fourth parameter, if present, is the moderation level this user is
287 SETU (SET User configuration)
289 This command does the opposite of SETU: it takes the screen dimensions and
290 user options (which were probably obtained with a GETU command, and perhaps
291 modified by the user) and writes them to the user account. This command
292 should be passed four parameters: the screen width, the screen height,
293 the option bits (see above), and the desired moderation level to filter at.
295 Note that there exist bits here which are not listed in this document. Some
296 are flags that can only be set by Aides or the system administrator. SETU
297 will ignore attempts to toggle these bits. There also may be more user
298 settable bits added at a later date. To maintain later downward compatibility,
299 the following procedure is suggested:
301 1. Execute GETU to read the current flags
302 2. Toggle the bits that we know we can toggle
303 3. Execute SETU to write the flags
305 If we are passed a bit whose meaning we don't know, it's best to leave it
306 alone, and pass it right back to the server. That way we can use an old
307 client on a server that uses an unknown bit without accidentally clearing
308 it every time we set the user's configuration.
313 This command is used to goto a new room. When the user first logs in (login
314 is completed after execution of the PASS command) this command is
315 automatically and silently executed to take the user to the first room in the
316 system (usually called the Lobby).
318 This command can be passed one or two parameters. The first parameter is,
319 of course, the name of the room. Although it is not case sensitive, the
320 full name of the room must be used. Wildcard matching or unique string
321 matching of room names should be the responsibility of the client.
323 Note that the reserved room name "_BASEROOM_" can be passed to the server
324 to cause the goto command to take the user to the first room in the system,
325 traditionally known as the Lobby>. As long as a user is logged in, a
326 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
327 allow client software to return to the base room when it doesn't know
330 There are also two additional reserved room names:
331 "_MAIL_" translates to the system's designated room for e-mail messages.
332 "_BITBUCKET_" goes to whatever room has been chosen for messages
335 The second (and optional) parameter is a password, if one is required for
336 access to the room. This allows for all types of rooms to be accessed via
337 this command: for public rooms, invitation-only rooms to which the user
338 has access, and preferred users only rooms to which the user has access, the
339 room will appear in a room listing. For guess-name rooms, this command
340 will work transparently, adding the room to the user's known room list when
341 it completes. For passworded rooms, access will be denied if the password
342 is not supplied or is incorrect, or the command will complete successfully
343 if the password is correct.
345 The possible result codes are:
347 OK - The command completed successfully. User is now in the room.
348 (See the list of returned parameters below)
350 ERROR - The command did not complete successfully. Check the second and
351 third positions of the result code to find out what happened:
353 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
354 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
355 password was incorrect.
356 NO_SUCH_ROOM - The requested room does not exist.
358 The typical procedure for entering a passworded room would be:
360 1. Execute a GOTO command without supplying any password.
361 2. ERROR+PASSWORD_REQUIRED will be returned. The client now knows that
362 the room is passworded, and prompts the user for a password.
363 3. Execute a GOTO command, supplying both the room name and the password.
364 4. If OK is returned, the command is complete. If, however,
365 ERROR+PASSWORD_REQUIRED is still returned, tell the user that the supplied
366 password was incorrect. The user remains in the room he/she was previously
369 When the command succeeds, these parameters are returned:
370 0. The name of the room
371 1. Number of unread messages in this room
372 2. Total number of messages in this room
373 3. Info flag: set to nonzero if the user needs to read this room's info
374 file (see RINF command below)
375 4. Various flags associated with this room. (See LKRN cmd above)
376 5. The highest message number present in this room
377 6. The highest message number the user has read in this room
378 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
379 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
380 a regular Aide (this makes access checks easy).
381 9. The number of new Mail messages the user has (useful for alerting the
382 user to the arrival of new mail during a session)
383 10. The floor number this room resides on
386 MSGS (get pointers to MeSsaGeS in this room)
388 This command obtains a listing of all the messages in the current room
389 which the client may request. This command may be passed a single parameter:
390 either "all", "old", or "new" to request all messages, only old messages, or
391 new messages. Or it may be passed two parameters: "last" plus a number, in
392 which case that many message pointers will be returned, or "first" plus a
393 number, for the corresponding effect. If no parameters are specified, "all"
396 In Citadel/UX 5.00 and above, the client may also specify "gt" plus a number,
397 to list all messages in the current room with a message number greater than
400 The third argument, valid only in Citadel/UX 5.60 and above, may be either
401 0 or 1. If it is 1, this command behaves differently: before a listing is
402 returned, the client must transmit a list of fields to search for. The field
403 headers are listed below in the writeup for the "MSG0" command.
405 This command can return three possible results. An ERROR code may be returned
406 if no user is currently logged in or if something else went wrong. Otherwise,
407 LISTING_FOLLOWS will be returned, and the listing will consist of zero or
408 more message numbers, one per line. The listing ends, as always, with the
409 string "000" alone on a line by itself. The listed message numbers can be used
410 to request messages from the system. If "search mode" is being used, the
411 server will return START_CHAT_MODE, and the client is expected to transmit
412 the search criteria, and then read the message list.
414 Since this is somewhat complex, here are some examples:
416 Example 1: Read all new messages
419 Server: 100 Message list...
425 Example 2: Read the last five messages
428 Server: 100 Message list...
436 Example 3: Read all messages written by "IGnatius T Foobar"
439 Server: 800 Send template then receive message list
440 Client: from|IGnatius T Foobar
454 Note that in "search mode" the client may specify any number of search
455 criteria. These criteria are applied with an AND logic.
459 MSG0 (read MeSsaGe, mode 0)
461 This is a command used to read the text of a message. "Mode 0" implies that
462 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
463 messages in more robust formats. This command should be passed two arguments.
464 The first is the message number of the message being requested. In server
465 version 4.04 and above, the second argument may be set to either 0 to read the
466 entire message, or 1 to read the headers only.
468 The server should, of course, make sure that the client actually has access
469 to the message being requested before honoring this request. Citadel/UX does
470 so by checking the message number against the contents of the current room. If
471 it's not there, the request is denied.
473 If the request is denied, an ERROR code will be returned. Otherwise, the
474 LISTING_FOLLOWS code will be returned, followed by the contents of the message.
475 The following fields may be sent:
477 type= Formatting type. The currently defined types are:
478 0 = "traditional" Citadel formatting. This means that newlines should be
479 treated as spaces UNLESS the first character on the next line is a space. In
480 other words, only indented lines should generate a newline on the user's screen
481 when the message is being displayed. This allows a message to be formatted to
482 the reader's screen width. It also allows the use of proportional fonts.
483 1 = a simple fixed-format message. The message should be displayed to
484 the user's screen as is, preferably in a fixed-width font that will fit 80
486 4 = MIME format message. The message text is expected to contain a header
487 with the "Content-type:" directive (and possibly others).
489 msgn= The message ID of this message on the system it originated on.
490 path= An e-mailable path back to the user who wrote the message.
492 time= The date and time of the message, in Unix format (the number of
493 seconds since midnight on January 1, 1970, GMT).
495 from= The name of the author of the message.
496 rcpt= If the message is a private e-mail, this is the recipient.
497 room= The name of the room the message originated in.
498 node= The short node name of the system this message originated on.
499 hnod= The long node name of the system this message originated on.
500 zaps= The id/node of a message which this one zaps (supersedes).
502 text Note that there is no "=" after the word "text". This string
503 signifies that the message text begins on the next line.
506 WHOK (WHO Knows room)
508 This command is available only to Aides. ERROR+HIGHER_ACCESS_REQUIRED will
509 be returned if the user is not an Aide. Otherwise, it returns
510 LISTING_FOLLOWS and then lists, one user per line, every user who has
511 access to the current room.
514 INFO (get server INFO)
516 This command will *always* return LISTING_FOLLOWS and then print out a
517 listing of zero or more strings. Client software should be written to expect
518 anywhere from a null listing to an infinite number of lines, to allow later
519 backward compatibility. The current implementation defines the following
520 parts of the listing:
522 Line 1 - Your unique session ID on the server
523 Line 2 - The node name of the server BBS
524 Line 3 - Human-readable node name of the server BBS
525 Line 4 - The fully-qualified domain name (FQDN) of the server
526 Line 5 - The name of the server software, i.e. "Citadel/UX 4.00"
527 Line 6 - (The revision level of the server code) * 100
528 Line 7 - The geographical location of the BBS (city and state if in the US)
529 Line 8 - The name of the system administrator
530 Line 9 - A number identifying the server type (see below)
531 Line 10 - The text of the system's paginator prompt
532 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
533 Line 12 - Paging level. 0 if the system only supports inline paging,
534 1 if the system supports "extended" paging (check-only and
535 multiline modes). See the SEXP command for further information.
536 Line 13 - The "nonce" for this session, for support of APOP-style
537 authentication. If this field is present, clients may authenticate
540 *** NOTE! *** The "server type" code is intended to promote global
541 compatibility in a scenario in which developers have added proprietary
542 features to their servers or clients. We are attempting to avoid a future
543 situation in which users need to keep different client software around for
544 each BBS they use. *Please*, if you are a developer and plan to add
545 proprietary features:
547 -> Your client programs should still be able to utilize servers other than
549 -> Clients other than your own should still be able to utilize your server,
550 even if your proprietary extensions aren't supported.
551 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
552 server type code, which can be assigned to your server program.
553 -> If you document what you did in detail, perhaps it can be added to a
554 future release of the Citadel/UX program, so everyone can enjoy it. Better
555 yet, just work with the Citadel development team on the main source tree.
557 If everyone follows this scheme, we can avoid a chaotic situation with lots
558 of confusion about which client program works with which server, etc. Client
559 software can simply check the server type (and perhaps the revision level)
560 to determine ahead of time what commands may be utilized.
562 Please refer to "developers.txt" for information on what codes belong to whom.
566 RDIR (Read room DIRectory)
568 Use this command to read the directory of a directory room. ERROR+NOT_HERE
569 will be returned if the room has no directory, or some other error; ERROR +
570 HIGHER_ACCESS_REQUIRED will be returned if the room's directory is not
571 visible and the user does not have Aide or Room Aide privileges; otherwise
572 LISTING_FOLLOWS will be returned, followed by the room's directory. Each
573 line of the directory listing will contain three fields: a filename, the
574 length of the file, and a description.
576 The server message contained on the same line with LISTING_FOLLOWS will
577 contain the name of the system and the name of the directory, such as:
578 uncensored.citadel.org|/usr/bbs/files/my_room_directory
581 SLRP (Set Last-message-Read Pointer)
583 This command marks all messages in the current room as read (seen) up to and
584 including the specified number. Its sole parameter
585 is the number of the last message that has been read. This allows the pointer
586 to be set at any arbitrary point in the room. Optionally, the parameter
587 "highest" may be used instead of a message number, to set the pointer to the
588 number of the highest message in the room, effectively marking all messages
589 in the room as having been read (ala the Citadel <G>oto command).
591 The command will return OK if the pointer was set, or ERROR if something
592 went wrong. If OK is returned, it will be followed by a single argument
593 containing the message number the last-read-pointer was set to.
596 INVT (INViTe a user to a room)
598 This command may only be executed by Aides, or by the room aide for the
599 current room. It is used primarily to add users to invitation-only rooms,
600 but it may also be used in other types of private rooms as well. Its sole
601 parameter is the name of the user to invite.
603 The command will return OK if the operation succeeded, or ERROR if it did
604 not. ERROR+HIGHER_ACCESS_REQUIRED may also be returned if the operation
605 would have been possible if the user had higher access, and ERROR+NOT_HERE
606 may be returned if the room is not a private room.
609 KICK (KICK a user out of a room)
611 This is the opposite of INVT: it is used to kick a user out of a private
612 room. It can also be used to kick a user out of a public room, but the
613 effect will only be the same as if the user <Z>apped the room - a non-stupid
614 user can simply un-zap the room to get back in.
617 GETR (GET Room attributes)
619 This command is used for editing the various attributes associated with a
620 room. A typical "edit room" command would work like this:
621 1. Use the GETR command to get the current attributes
622 2. Change some of them around
623 3. Use SETR (see below) to save the changes
624 4. Possibly also change the room aide using the GETA and SETA commands
626 GETR takes no arguments. It will only return OK if the SETR command will
627 also return OK. This allows client software to tell the user that he/she
628 can't edit the room *before* going through the trouble of actually doing the
629 editing. Possible return codes are:
631 ERROR+NOT_LOGGED_IN - No user is logged in.
632 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
633 and the room aide associated with the current room, can access this command.
634 ERROR+NOT_HERE - Lobby>, Mail>, and Aide> cannot be edited.
635 OK - Command succeeded. Parameters are returned.
637 If OK is returned, the following parameters will be returned as well:
639 0. The name of the room
640 1. The room's password (if it's a passworded room)
641 2. The name of the room's directory (if it's a directory room)
642 3. Various flags (bits) associated with the room (see LKRN cmd above)
643 4. The floor number on which the room resides
644 5. The room listing order
647 SETR (SET Room attributes)
649 This command sets various attributes associated with the current room. It
650 should be passed the following arguments:
652 0. The name of the room
653 1. The room's password (if it's a passworded room)
654 2. The name of the room's directory (if it's a directory room)
655 3. Various flags (bits) associated with the room (see LKRN cmd above)
656 4. "Bump" flag (see below)
657 5. The floor number on which the room should reside
658 6. The room listing order
660 *Important: You should always use GETR to retrieve the current attributes of
661 the room, then change what you want to change, and then use SETR to write it
662 all back. This is particularly important with respect to the flags: if a
663 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
664 only toggle the bits you want to toggle. This will allow for upward
667 If the room is a private room, you have the option of causing all users who
668 currently have access, to forget the room. If you want to do this, set the
669 "bump" flag to 1, otherwise set it to 0.
674 This command is used to get the name of the Room Aide for the current room.
675 It will return ERROR+NOT_LOGGED_IN if no user is logged in, ERROR if there
676 is no current room, or OK if the command succeeded. Along with OK there will
677 be returned one parameter: the name of the Room Aide.
682 The opposite of GETA, used to set the Room Aide for the current room. One
683 parameter should be passed, which is the name of the user who is to be the
684 new Room Aide. Under Citadel/UX, this command may only be executed by Aides
685 and by the *current* Room Aide for the room. Return codes possible are:
686 ERROR+NOT_LOGGED_IN (Not logged in.)
687 ERROR+HIGHER_ACCESS_REQUIRED (Higher access required.)
688 ERROR+NOT_HERE (No current room, or room cannot be edited.
689 Under Citadel/UX, the Lobby> Mail> and Aide> rooms are non-editable.)
690 OK (Command succeeded.)
693 ENT0 (ENTer message, mode 0)
695 This command is used to enter messages into the system. It accepts four
698 0 - Post flag. This should be set to 1 to post a message. If it is
699 set to 0, the server only returns OK or ERROR (plus any flags describing
700 the error) without reading in a message. Client software should, in fact,
701 perform this operation at the beginning of an "enter message" command
702 *before* starting up its editor, so the user does not end up typing a message
703 in vain that will not be permitted to be saved. If it is set to 2, the
704 server will accept an "apparent" post name if the user is privileged enough.
705 This post name is arg 4.
706 1 - Recipient. This argument is utilized only for private mail messages.
707 It is ignored for public messages. It contains, of course, the name of the
708 recipient of the message.
709 2 - Anonymous flag. This argument is ignored unless the room allows
710 anonymous messages. In such rooms, this flag may be set to 1 to flag a
711 message as anonymous, otherwise 0 for a normal message.
712 3 - Format type. Any valid Citadel/UX format type may be used (this will
713 typically be 0; see the MSG0 command above).
714 4 - Post name. When postflag is 2, this is the name you are posting as.
715 This is an Aide only command.
717 Possible result codes:
718 OK - The request is valid. (Client did not set the "post" flag, so the
719 server will not read in message text.) If the message is an e-mail with
720 a recipient, the text that follows the OK code will contain the exact name
721 to which mail is being sent. The client can display this to the user. The
722 implication here is that the name that the server returns will contain the
723 correct upper and lower case characters. In addition, if the recipient is
724 having his/her mail forwarded, the forwarding address will be returned.
725 SEND_LISTING - The request is valid. The client should now transmit
726 the text of the message (ending with a 000 on a line by itself, as usual).
727 ERROR - Miscellaneous error. (Explanation probably follows.)
728 ERROR + NOT_LOGGED_IN - Not logged in.
729 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
730 explanation follows, worded in a form that can be displayed to the user.
731 ERROR + NO_SUCH_USER - The specified recipient does not exist.
734 RINF (read Room INFormation file)
736 Each room has associated with it a text file containing a description of
737 the room, perhaps containing its intended purpose or other important
738 information. The info file for the Lobby> (the system's base room) is
739 often used as a repository for system bulletins and the like.
741 This command, which accepts no arguments, is simply used to read the info
742 file for the current room. It will return LISTING_FOLLOWS followed by
743 the text of the message (always in format type 0) if the request can be
744 honored, or ERROR if no info file exists for the current room (which is
745 often the case). Other error description codes may accompany this result.
747 When should this command be used? This is, of course, up to the discretion
748 of client software authors, but in Citadel it is executed in two situations:
749 the first time the user ever enters a room; and whenever the contents of the
750 file change. The latter can be determined from the result of a GOTO command,
751 which will tell the client whether the file needs to be read (see GOTO above).
754 DELE (DELEte a message)
756 Delete a message from the current room. The one argument that should be
757 passed to this command is the message number of the message to be deleted.
758 The return value will be OK if the message was deleted, or an ERROR code.
759 If the delete is successful, the message's reference count is decremented, and
760 if the reference count reaches zero, the message is removed from the message
764 MOVE (MOVE or copy a message to a different room)
766 Move a message to a different room. The two arguments that should be passed
767 to this command are the message number of the message to be deleted, and the
768 name of the target room. If the operation succeeds, the message will be
769 deleted from the current room and moved to the target room. An ERROR code
770 usually means that either the user does not have permission to perform this
771 operation, or that the target room does not exist.
773 In Citadel/UX 5.55 and above, a third argument may be specified: 0 or 1 to
774 designate whether the message should be moved (0) or copied (1) to the target
775 room. In the case of a "copy" operation, the message's reference count is
776 incremented, and a pointer to the message will exist in both the source *and*
777 target rooms. In the case of a "move" operation, the message pointer is
778 deleted from the source room and the reference count remains the same.
781 KILL (KILL current room)
783 This command deletes the current room. It accepts a single argument, which
784 should be nonzero to actually delete the room, or zero to merely check
785 whether the room can be deleted.
787 Once the room is deleted, the current room is undefined. It is suggested
788 that client software immediately GOTO another room (usually _BASEROOM_)
789 after this command completes.
791 Possible return codes:
793 OK - room has been deleted (or, if checking only, request is valid).
794 ERROR+NOT_LOGGED_IN - no user is logged in.
795 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
796 ERROR+NOT_HERE - this room can not be deleted.
799 CRE8 (CRE[ate] a new room)
801 This command is used to create a new room. Like some of the other
802 commands, it provides a mechanism to first check to see if a room can be
803 created before actually executing the command. CRE8 accepts the following
806 0 - Create flag. Set this to 1 to actually create the room. If it is
807 set to 0, the server merely checks that there is a free slot in which to
808 create a new room, and that the user has enough access to create a room. It
809 returns OK if the client should go ahead and prompt the user for more info,
810 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
811 1 - Name for new room.
812 2 - Access type for new room:
814 1 - Private; can be entered by guessing the room's name
815 2 - Private; can be entered by knowing the name *and* password
816 3 - Private; invitation only (sometimes called "exclusive")
817 3 - Password for new room (if it is a type 2 room)
818 4 - Floor number on which the room should reside (optional)
820 If the create flag is set to 1, the room is created (unless something
821 went wrong and an ERROR return is sent), and the server returns OK, but
822 the session is **not** automatically sent to that room. The client still
823 must perform a GOTO command to go to the new room.
826 FORG (FORGet the current room)
828 This command is used to forget (zap) the current room. For those not
829 familiar with Citadel, this terminology refers to removing the room from
830 a user's own known rooms list, *not* removing the room itself. After a
831 room is forgotten, it no longer shows up in the user's known room list,
832 but it will exist in the user's forgotten room list, and will return to the
833 known room list if the user goes to the room (in Citadel, this is
834 accomplished by explicitly typing the room's name in a <.G>oto command).
836 The command takes no arguments. If the command cannot execute for any
837 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
838 be returned as they apply.
840 If the command succeeds, OK will be returned. At this point, the current
841 room is **undefined**, and the client software is responsible for taking
842 the user to another room before executing any other room commands (usually
843 this will be _BASEROOM_ since it is always there).
846 MESG (read system MESsaGe)
848 This command is used to display system messages and/or help files. The
849 single argument it accepts is the name of the file to display. IT IS CASE
850 SENSITIVE. Citadel/UX looks for these files first in the "messages"
851 subdirectory and then in the "help" subdirectory.
853 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
854 to the file being displayed. Then the message is printed, in format type 0
855 (see MSG0 command for more information on this). If the file is not found,
858 There are some "well known" names of system messages which client software
859 may expect most servers to carry:
861 hello - Welcome message, to be displayed before the user logs in.
862 changepw - To be displayed whenever the user is prompted for a new
863 password. Warns about picking guessable passwords and such.
864 register - Should be displayed prior to the user entering registration.
865 Warnings about not getting access if not registered, etc.
866 help - Main system help file.
867 goodbye - System logoff banner; display when user logs off.
868 roomaccess - Information about how public rooms and different types of
869 private rooms function with regards to access.
870 unlisted - Tells users not to choose to be unlisted unless they're
871 really paranoid, and warns that aides can still see
872 unlisted userlog entries.
874 Citadel/UX provides these for the Citadel/UX Unix text client. They are
875 probably not very useful for other clients:
877 mainmenu - Main menu (when in idiot mode).
882 saveopt - Options to save a message, abort, etc.
883 entermsg - Displayed just before a message is entered, when in
887 GNUR (Get Next Unvalidated User)
889 This command shows the name of a user that needs to be validated. If there
890 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
891 along with the name of the first unvalidated user the server finds. All of
892 the usual ERROR codes may be returned as well (for example, if the user is
893 not an Aide and cannot validate users).
895 A typical "Validate New Users" command would keep executing this command,
896 and then validating each user it returns, until it returns OK when all new
897 users have been validated.
900 GREG (Get REGistration for user)
902 This command retrieves the registration info for a user, whose name is the
903 command's sole argument. All the usual error messages can be returned. If
904 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
905 (retrieved from the userlog, with the right upper and lower case etc.) The
906 contents of the listing contains one field per line, followed by the usual
907 000 on the last line.
909 The following lines are defined. Others WILL be added in the futre, so all
910 software should be written to read the lines it knows about and then ignore
916 Line 4: Street address or PO Box
917 Line 5: City/town/village/etc.
918 Line 6: State/province/etc.
920 Line 8: Telephone number
922 Line 10: Internet e-mail address
925 Users without Aide privileges may retrieve their own registration using
926 this command. This can be accomplished either by passing the user's own
927 name as the argument, or the string "_SELF_". The command will always
928 succeed when used in this manner, unless no user is logged in.
933 This command is used to validate users. Obviously, it can only be executed
934 by users with Aide level access. It should be passed two parameters: the
935 name of the user to validate, and the desired access level
937 If the command succeeds, OK is returned. The user's access level is changed
938 and the "need validation" bit is cleared. If the command fails for any
939 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
943 EINF (Enter INFo file for room)
945 Transmit the info file for the current room with this command. EINF uses
946 a boolean flag (1 or 0 as the first and only argument to the command) to
947 determine whether the client actually wishes to transmit a new info file, or
948 is merely checking to see if it has permission to do so.
950 If the command cannot succeed, it returns ERROR.
951 If the client is only checking for permission, and permission will be
952 granted, OK is returned.
953 If the client wishes to transmit the new info file, SEND_LISTING is
954 returned, and the client should transmit the text of the info file, ended
955 by the usual 000 on a line by itself.
960 This is a simple user listing. It always succeeds, returning
961 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
962 fields on each line are as follows:
967 4. Date/time of last login (Unix format)
970 7. Password (listed only if the user requesting the list is an Aide)
972 Unlisted entries will also be listed to Aides logged into the server, but
973 not to ordinary users.
976 REGI (send REGIstration)
978 Clients will use this command to transmit a user's registration info. If
979 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
980 SEND_LISTING is returned, and the server will expect the following information
981 (terminated by 000 on a line by itself):
984 Line 2: Street address or PO Box
985 Line 3: City/town/village/etc.
986 Line 4: State/province/etc.
988 Line 6: Telephone number
989 Line 7: e-mail address
993 CHEK (CHEcK various things)
995 When logging in, there are various things that need to be checked. This
996 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
997 it returns OK and the following parameters:
999 0: Number of new private messages in Mail>
1000 1: Nonzero if the user needs to register
1001 2: (Relevant to Aides only) Nonzero if new users require validation
1004 DELF (DELete a File)
1006 This command deletes a file from the room's directory, if there is one. The
1007 name of the file to delete is the only parameter to be supplied. Wildcards
1008 are not acceptable, and any slashes in the filename will be converted to
1009 underscores, to prevent unauthorized access to neighboring directories. The
1010 possible return codes are:
1012 OK - Command succeeded. The file was deleted.
1013 ERROR+NOT_LOGGED_IN - Not logged in.
1014 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1015 ERROR+NOT_HERE - There is no directory in this room.
1016 ERROR+FILE_NOT_FOUND - Requested file was not found.
1021 This command is similar to DELF, except that it moves a file (and its
1022 associated file description) to another room. It should be passed two
1023 parameters: the name of the file to move, and the name of the room to move
1024 the file to. All of the same return codes as DELF may be returned, and also
1025 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1026 does not exist. ERROR+NOT_HERE could also mean that the target room does
1027 not have a directory.
1030 NETF (NETwork send a File)
1032 This command is similar to MOVF, except that it attempts to send a file over
1033 the network to another system. It should be passed two parameters: the name
1034 of the file to send, and the node name of the system to send it to. All of
1035 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1036 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1039 The name of the originating room will be sent along with the file. Most
1040 implementations will look for a room with the same name at the receiving end
1041 and attempt to place the file there, otherwise it goes into a bit bucket room
1042 for miscellaneous files. This is, however, beyond the scope of this document;
1043 see elsewhere for more details.
1046 RWHO (Read WHO's online)
1048 Displays a list of all users connected to the server. No error codes are
1049 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1050 lines containing the following three fields:
1052 0 - Session ID. Citadel/UX fills this with the pid of a server program.
1054 2 - The name of the room the user is currently in. This field might not
1055 be displayed (for example, if the user is in a private room) or it might
1056 contain other information (such as the name of a file the user is
1058 3 - (server v4.03 and above) The name of the host the client is connecting
1059 from, or "localhost" if the client is local.
1060 4 - (server v4.04 and above) Description of the client software being used
1061 5 - The last time, locally to the server, that a command was received from
1062 this client (Note: NOOP's don't count)
1063 6 - The last command received from a client. (NOOP's don't count)
1064 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1065 (posting) and . (idle).
1066 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1067 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1068 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1070 The listing is terminated, as always, with the string "000" on a line by
1074 OPEN (OPEN a file for download)
1076 This command is used to open a file for downloading. Only one download
1077 file may be open at a time. The only argument to this command is the name
1078 of the file to be opened. The user should already be in the room where the
1079 file resides. Possible return codes are:
1082 ERROR+NOT_HERE (no directory in this room)
1083 ERROR+FILE_NOT_FOUND (could not open the file)
1087 If the file is successfully opened, OK will be returned, along with the
1088 size (in bytes) of the file, the time of last modification (if applicable),
1089 the filename (if known), and the MIME type of the file (if known).
1092 CLOS (CLOSe the download file)
1094 This command is used to close the download file. It returns OK if the
1095 file was successfully closed, or ERROR if there wasn't any file open in the
1099 READ (READ from the download file)
1101 Two arguments are passed to this command. The first is the starting position
1102 in the download file, and the second is the total number of bytes to be
1103 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1104 along with the number of bytes to follow. Then, immediately following the
1105 newline, will be that many bytes of binary data. The client *must* read
1106 exactly that number of bytes, otherwise the client and server will get out
1109 If the operation cannot be performed, any of the usual error codes will be
1113 UOPN (OPeN a file for Uploading)
1115 This command is similar to OPEN, except that this one is used when the
1116 client wishes to upload a file to the server. The first argument is the name
1117 of the file to create, and the second argument is a one-line comment
1118 describing the contents of the file. Only one upload file may be open at a
1119 time. Possible return codes are:
1122 ERROR+NOT_HERE (no directory in this room)
1123 ERROR+FILE_NOT_FOUND (a name must be specified)
1124 ERROR (miscellaneous errors)
1125 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1128 If OK is returned, the command has succeeded and writes may be performed.
1131 UCLS (CLoSe the Upload file)
1133 Close the file opened with UOPN. An argument of "1" should be passed to
1134 this command to close and save the file; otherwise, the transfer will be
1135 considered aborted and the file will be deleted. This command returns OK
1136 if the operation succeeded or ERROR if it did not.
1139 WRIT (WRITe to the upload file)
1141 If an upload file is open, this command may be used to write to it. The
1142 argument passed to this command is the number of bytes the client wishes to
1143 transmit. An ERROR code will be returned if the operation cannot be
1146 If the operation can be performed, SEND_BINARY will be returned, followed
1147 by the number of bytes the server is expecting. The client must then transmit
1148 exactly that number of bytes. Note that in the current implementation, the
1149 number of bytes the server is expecting will always be the number of bytes
1150 the client requested to transmit, but the client software should never assume
1151 that this will always happen, in case changes are made later.
1154 QUSR (Query for a USeR)
1156 This command is used to check to see if a particular user exists. The only
1157 argument to this command is the name of the user being searched for. If
1158 the user exists, OK is returned, along with the name of the user in the userlog
1159 (so the client software can learn the correct upper/lower casing of the name
1160 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1161 No login or current room is required to utilize this command.
1164 OIMG (Open an IMaGe file)
1166 Open an image (graphics) file for downloading. Once opened, the file can be
1167 read as if it were a download file. This implies that an image and a download
1168 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1170 All images will be in GIF (Graphics Interchange Format). In the case of
1171 Citadel/UX, the server will convert the supplied filename to all lower case,
1172 append the characters ".gif" to the filename, and look for it in the "images"
1173 subdirectory. As with the MESG command, there are several "well known"
1174 images which are likely to exist on most servers:
1176 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1177 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1178 background - Background image (usually tiled) for graphical clients
1180 The following "special" image names are defined in Citadel/UX server version
1183 _userpic_ - Picture of a user (send the username as the second argument)
1184 _floorpic_ - A graphical floor label (send the floor number as the second
1185 argument). Clients which request a floor picture will display
1186 the picture *instead* of the floor name.
1187 _roompic_ - A graphic associated with the *current* room. Clients which
1188 request a room picture will display the picture in *addition*
1189 to the room name (i.e. it's used for a room banner, as
1190 opposed to the floor picture's use in a floor listing).
1193 NETP (authenticate as network session with system NET Password)
1195 This command is used by client software to identify itself as a transport
1196 session for IGnet/Open BBS to BBS networking. It should be called with
1197 two arguments: the node name of the calling system, and the system net
1198 password for the server. If the authentication succeeds, NETP will return
1199 OK, otherwise, it returns ERROR.
1202 NUOP (Network Upload OPen file)
1204 Open a network spool file for uploading. The client must have already
1205 identified itself as a network session using the NETP command. If the command
1206 returns OK, the client may begin transmitting IGnet/Open spool data using
1207 a series of WRIT commands. When a UCLS command is issued, the spooled data
1208 is entered into the BBS if the argument to UCLS is 1 or discarded if the
1209 argument to UCLS is 0. If the client has not authenticated itself with a
1210 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1213 NDOP (Network Download OPen file)
1215 Open a network spool file for downloading. The client must have already
1216 identified itself as a network session using the NETP command. If the command
1217 returns OK, the client may begin receiving IGnet/Open spool data using
1218 a series of READ commands. When a CLOS command is issued, the spooled data
1219 is deleted from the server and may not be read again. If the client has not
1220 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1224 LFLR (List all known FLooRs)
1226 On systems supporting floors, this command lists all known floors. The
1227 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1228 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1229 the available floors, each line consisting of three fields:
1231 1. The floor number associated with the floor
1232 2. The name of the floor
1233 3. Reference count (number of rooms on this floor)
1236 CFLR (Create a new FLooR)
1238 This command is used to create a new floor. It should be passed two
1239 arguments: the name of the new floor to be created, and a 1 or 0 depending
1240 on whether the client is actually creating a floor or merely checking to
1241 see if it has permission to create the floor. The user must be logged in
1242 and have Aide privileges to create a floor.
1244 If the command succeeds, it will return OK followed by the floor number
1245 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1246 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1247 followed by a description of why the command failed.
1252 This command is used to delete a floor. It should be passed two
1253 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1254 on whether the client is actually deleting the floor or merely checking to
1255 see if it has permission to delete the floor. The user must be logged in
1256 and have Aide privileges to delete a floor.
1258 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1259 they must be either deleted or moved to different floors first. This implies
1260 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1261 Aide> all reside on the Main Floor and cannot be deleted.
1263 If the command succeeds, it will return OK. Otherwise it will return
1264 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1265 followed by a description of why the command failed.
1270 Edit the parameters of a floor. The client may pass one or more parameters
1273 1. The number of the floor to be edited
1274 2. The desired new name
1276 More parameters may be added in the future. Any parameters not passed to
1277 the server will remain unchanged. A minimal command would be EFLR and a
1278 floor number -- which would do nothing. EFLR plus the floor number plus a
1279 floor name would change the floor's name.
1281 If the command succeeds, it will return OK. Otherwise it will return
1282 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1285 IDEN (IDENtify the client software)
1287 The client software has the option to identify itself to the server.
1288 Currently, the server does nothing with this information except to write
1289 it to the syslog to satisfy the system administrator's curiosity. Other
1290 uses might become apparent in the future.
1292 The IDEN command should contain five fields: a developer ID number (same as
1293 the server developer ID numbers in the INFO command -- please obtain one if
1294 you are a new developer), a client ID number (which does not have to be
1295 globally unique - only unique within the domain of the developer number),
1296 a version number, a free-form text string describing the client, and the name
1297 of the host the user is located at.
1299 It is up to the server to determine whether to accept the host name or to
1300 use the host name it has detected itself. Generally, if the client is
1301 running on a trusted host (either localhost or a well-known publically
1302 accessible client) it should use the host name transmitted by IDEN,
1303 otherwise it should use the host name it has detected itself.
1305 IDEN always returns OK, but since that's the only way it ever returns
1306 there's no point in checking the result code.
1309 IPGM (identify as an Internal ProGraM)
1311 IPGM is a low-level command that should not be used by normal user clients.
1312 It is used for various utilities to communicate with the server on the same
1313 host. For example, the networker (netproc.c) logs onto the server as an
1314 internal program in order to fetch and store messages. Since user clients
1315 do not utilize this command (or any of its companion commands), developers
1316 writing Citadel-compatible servers need not implement it.
1318 The sole argument to IPGM is the system's internal program password. This
1319 password is generated by the setup program and stored in the config file.
1320 Since internal programs have access to the config file, they know the correct
1323 IPGM returns OK for a correct authentication or ERROR otherwise.
1326 CHAT (enter CHAT mode)
1328 This command functions differently from every other command in the system. It
1329 is used to implement multi-user chat. For this to function, a new transfer
1330 mode, called START_CHAT_MODE, is implemented. If a client does not support
1331 chat mode, it should never send a CHAT command!
1333 In chat mode, messages may arrive asynchronously from the server at any
1334 time. The client may send messages at any time. This allows the arrival of
1335 messages without the client having to poll for them. Arriving messages will
1336 be of the form "user|message", where the "user" portion is, of course, the
1337 name of the user sending the message, and "message" is the message text.
1339 Chat mode ends when the server says it ends. The server will signal the end
1340 of chat mode by transmitting "000" on a line by itself. When the client reads
1341 this line, it must immediately exit from chat mode without sending any
1342 further traffic to the server. The next transmission sent to the server
1343 will be a regular server command.
1345 The Citadel/UX server understands the following commands:
1346 /quit - Exit from chat mode (causes the server to do an 000 end)
1347 /who - List users currently in chat
1348 /whobbs - List users currently in chat and on the bbs
1349 /me - Do an irc-style action.
1350 /join - Join a new "room" in which all messages are only heard by
1351 people in that room.
1352 /msg - /msg <user> <msg> will send the msg to <user> only.
1353 /help - Print help information
1354 NOOP - Do nothing (silently)
1356 Any other non-empty string is treated as message text and will be broadcast
1357 to other users currently in chat.
1360 SEXP (Send EXPress messages)
1362 This is one of two commands which implement "express messages" (also known
1363 as "paging"). An express message is a near-real-time message sent from one
1364 logged in user to another. When an express message is sent, it will be
1365 displayed the next time the target user executes a PEXP or GEXP command.
1367 The SEXP command accepts two arguments: the name of the user to send the
1368 message to, and the text of the message. If the message is successfully
1369 transmitted, OK is returned. If the target user is not logged in or if
1370 anything else goes wrong, ERROR is returned.
1372 If the server supports extended paging, sending a zero-length message
1373 merely checks for the presence of the requested user without actually sending
1374 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1375 the server to return SEND_LISTING if the requested user is logged in, and the
1376 client can then transmit a multi-line page.
1378 The reserved name "broadcast" may be used instead of a user name, to
1379 broadcast an express message to all users currently connected to the server.
1381 Do be aware that if an express message is transmitted to a user who is logged
1382 in using a client that does not check for express messages, the message will
1386 PEXP (Print EXPress messages) ***DEPRECATED***
1388 This command is deprecated; it will eventually disappear from the protocol and
1389 its use is not recommended. Please use the GEXP command instead.
1391 Called without any arguments, PEXP simply dumps out the contents
1392 of any waiting express messages. It returns ERROR if there is a problem,
1393 otherwise it returns LISTING_FOLLOWS followed by all messages.
1395 So how does the client know there are express messages waiting? It could
1396 execute a random PEXP every now and then. Or, it can check the byte in
1397 server return code messages, between the return code and the parameters. In
1398 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1399 an "*" in this position to signify the presence of waiting express messages.
1402 EBIO (Enter BIOgraphy)
1404 Transmit to the server a free-form text file containing a little bit of
1405 information about the user for other users to browse. This is typically
1406 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1407 after which the client is expected to transmit the file, or any of the usual
1408 ERROR codes if it fails.
1411 RBIO (Read BIOgraphy)
1413 Receive from the server a named user's bio. This command should be passed
1414 a single argument - the name of the user whose bio is requested. RBIO returns
1415 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1416 The return has the following parameters: the user name, user number, access
1417 level, date of last call, times called, and messages posted. This command
1418 returns ERROR+NO_SUCH_USER if the named user does not exist.
1420 RBIO no longer considers a user with no bio on file to be an error condition.
1421 It now returns a message saying the user has no bio on file as the text of the
1422 bio. This allows newer servers to operate with older clients.
1425 STEL (enter STEaLth mode)
1427 When in "stealth mode," a user will not show up in the "Who is online"
1428 listing (the RWHO server command). Only Aides may use stealth mode. The
1429 STEL command accepts one argument: a 1 indicating that the user wishes to
1430 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1431 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1432 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide.
1434 The STEL command also makes it so a user does not show up in the chat room
1438 LBIO (List users who have BIOs on file)
1440 This command is self-explanatory. Any user who has used EBIO to place a bio
1441 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1442 this listing, unless it experiences an internal error in which case ERROR
1446 MSG2 (read MeSsaGe, mode 2)
1448 MSG2 follows the same calling convention as MSG0. The difference between
1449 the two commands is that MSG2 outputs messages in standard RFC822 format
1450 rather than in Citadel/UX proprietary format.
1452 This command was implemented in order to make various gateway programs
1453 easier to implement, and to provide some sort of multimedia support in the
1454 future. Keep in mind that when this command is used, all messages will be
1455 output in fixed 80-column format.
1458 MSG3 (read MeSsaGe, mode 3 -- internal command)
1460 MSG3 is for use by internal programs only and should not be utilized by
1461 user-mode clients. It does require IPGM authentication. MSG3 follows the
1462 same calling convention as the other MSG commands, but upon success returns
1463 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1467 ENT3 (ENTer message, mode 3 -- internal command)
1469 ENT3 is for use by internal programs only and should not be utilized by
1470 user-mode clients. It does require IPGM authentication. This command posts
1471 a raw message straight into the message base without modification or performing
1472 any checks. It accepts the following arguments:
1474 0 - Post flag. This should be set to 1 to post a message. If it is
1475 set to 0, the server only returns OK or ERROR (plus any flags describing
1476 the error) without reading in a message. This is used to verify the operation
1477 before actually transmitting a message.
1478 1 - Recipient. This argument is utilized only for private mail messages.
1479 It is ignored for public messages. It contains, of course, the name of the
1480 recipient of the message.
1481 2 - The size (in bytes) of the message to be transmitted.
1483 ENT3 returns OK to tell the client that a message can be posted, ERROR if
1484 there would be a problem with the operation, or SEND_BINARY followed by a byte
1485 count if it is expecting the message to be transmitted.
1488 TERM (TERMinate another session)
1490 In a multithreaded environment, it sometimes becomes necessary to terminate
1491 a session that is unusable for whatever reason. The TERM command performs
1492 this task. Naturally, only Aides can execute TERM. The command should be
1493 called with a single argument: the session ID (obtained from an RWHO command)
1494 of the session to be terminated.
1496 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1497 a client program is prohibited from terminating the session it is currently
1503 NSET (Network SETup commands)
1505 Aides may use this command to configure the networker. This command's
1506 parameters are passed directly to the 'netsetup' command line utility. If
1507 netsetup returns a non-zero exit code, ERROR is returned, along with the
1508 error message (if any). If netsetup returns a zero (success) exit code,
1509 LISTING_FOLLOWS is returned, followed by zero or more lines of output (since
1510 netsetup may have information to display, such as a room or node list) and
1511 the usual '000' listing terminator.
1514 DOWN (shut DOWN the server)
1516 This command, which may only be executed by an Aide, immediately shuts down
1517 the server. It is only implemented on servers on which such an operation is
1518 possible, such as a multithreaded Citadel engine. The server does not restart.
1519 DOWN returns OK if the user is allowed to shut down the server, in which case
1520 the client program should expect the connection to be immediately broken.
1523 SCDN (Schedule or Cancel a shutDowN)
1525 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1526 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1527 set, the server will be shut down when there are no longer any users logged in.
1528 Any value other than 0 or 1 will not change the flag, only report its state.
1529 No users will be kicked off the system, and in fact the server is still
1530 available for new connections. The command returns ERROR if it fails;
1531 otherwise, it returns OK followed by a number representing the current state
1535 EMSG (Enter a system MeSsaGe)
1537 This is the opposite of the MESG command - it allows the creation and editing
1538 of system messages. The only argument passed to EMSG is the name of the
1539 file being transmitted. If the file exists in any system message directory
1540 on the server it will be overwritten, otherwise a new file is created. EMSG
1541 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1544 Typical client software would use MESG to retrieve any existing message into
1545 an edit buffer, then present an editor to the user and run EMSG if the changes
1549 UIMG (Upload an IMaGe file)
1551 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1552 The first parameter supplied to UIMG should be 0 if the client is only checking
1553 for permission to upload, or 1 if the client is actually attempting to begin
1554 the upload operation. The second argument is the name of the file to be
1555 transmitted. In Citadel/UX, the filename is converted to all lower case,
1556 appended with the characters ".gif", and stored in the "images" directory.
1558 UIMG returns OK if the client has permission to perform the requested upload,
1559 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1560 the operation (first parameter set to 1), an upload file is opened, and the
1561 client should begin writing to it with WRIT commands, then close it with a
1564 The supplied filename should be one of:
1566 -> _userpic_ (Server will attempt to write to the user's online photo)
1567 -> Any of the "well known" filenames described in the writeup for the
1571 HCHG (Hostname CHanGe)
1573 HCHG is a command, usable by any user, that allows a user to change their RWHO
1574 host value. This will mask a client's originating hostname from normal
1575 users; access level 6 and higher see an entry right underneath the spoofed
1576 entry listing the actual hostname the user originates from.
1578 The format of an HCHG command is:
1582 If a HCHG command is successful, the value OK (200) is returned.
1585 RCHG (Roomname CHanGe)
1587 RCHG is a command, usable by any user, that allows a user to change their RWHO
1588 room value. This will mask a client's roomname from normal users; access
1589 level 6 and higher see an entry right underneath the spoofed entry listing
1590 the actual room the user is in.
1592 The format of an RCHG command is:
1596 If a RCHG command is successful, the value OK (200) is returned.
1599 UCHG (Username CHanGe)
1601 UCHG is an aide-level command which allows an aide to effectively change their
1602 username. If this value is blank, the user goes into stealth mode (see
1604 will show up as being from the real username in this mode, however. In
1605 addition, the RWHO listing will include both the spoofed and real usernames.
1607 The format of an UCHG command is:
1611 If a UCHG command is successful, the value OK (200) is returned.
1614 TIME (get server local TIME)
1616 TIME returns OK followed by the current time measured in seconds since
1617 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1619 This is used in allowing a client to calculate idle times.
1622 AGUP (Administrative Get User Parameters)
1623 ASUP (Administrative Set User Parameters)
1625 These commands are only executable by Aides and by server extensions running
1626 at system-level. They are used to get/set any and all parameters relating to
1627 a user account. AGUP requires only one argument: the name of the user in
1628 question. SGUP requires all of the parameters to be set. The parameters are
1629 as follows, and are common to both commands:
1633 2 - Flags (see citadel.h)
1638 7 - Timestamp of last call
1639 8 - Purge time (in days) for this user (or 0 to use system default)
1641 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1642 simply returns OK. If the client has insufficient access to perform the
1643 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1644 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1648 GPEX (Get Policy for message EXpiration)
1650 Returns the policy of the current room, floor, or site regarding the automatic
1651 purging (expiration) of messages. The following policies are available:
1652 0 - Fall back to the policy of the next higher level. If this is a room,
1653 use the floor's default policy. If this is a floor, use the system
1654 default policy. This is an invalid value for the system policy.
1655 1 - Do not purge messages automatically.
1656 2 - Purge by message count. (Requires a value: number of messages)
1657 3 - Purge by message age. (Requires a value: number of days)
1659 The format of this command is: GPEX <which>
1660 The value of <which> must be one of: "room" "floor" "site"
1662 If successful, GPEX returns OK followed by <policy>|<value>.
1666 SPEX (Set Polict for message EXpiration)
1668 Sets the policy of the current room, floor, or site regarding the automatic
1669 purging (expiration) of messages. See the writeup for the GPEX command for
1670 the list of available policies.
1672 The format of this command is: SPEX <which>|<policy>|<value>
1673 The value of <which> must be one of: "room" "floor" "site"
1675 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1679 CONF (get or set global CONFiguration options)
1681 Retrieves or sets various system-wide configuration and policy options. This
1682 command is only available to Aides. The sole parameter accepted is a command,
1683 which should be either GET or SET. If the GET command succeeds, CONF will
1684 return LISTING_FOLLOWS followed by the fields described below, one line at a
1685 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1686 the fields described below, one line at a time (don't worry about other fields
1687 being added in the future; if a 'short' configuration list is sent, the missing
1688 values at the end will be left unchanged on the system). If either command
1689 fails for any reason, ERROR is returned.
1691 The configuration lines are as follows:
1694 2. Fully qualified domain name
1695 3. Human-readable node name
1696 4. Landline telephone number of this system
1697 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1698 6. Server connection idle timeout (in seconds)
1699 7. Initial access level for new users
1700 8. Flag (0 or 1) - require registration for new users
1701 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1702 10. Name of twit room
1703 11. Text of <more> prompt
1704 12. Flag (0 or 1) - restrict access to Internet mail
1705 13. Geographic location of this system
1706 14. Name of the system administrator
1707 15. Number of maximum concurrent sessions allowed on the server
1708 16. Password for server-to-server networking
1709 17. Default purge time (in days) for users
1710 18. Default purge time (in days) for rooms
1711 19. Name of room to log express messages to (or a zero-length name for none)
1712 20. Access level required to create rooms
1713 21. Maximum message length which may be entered into the system
1714 22. Minimum number of worker threads
1715 23. Maximum number of worker threads
1716 24. Port number for POP3 service
1717 25. Port number for SMTP service
1718 26. Default moderation filter level for new users (-63 to +63)
1719 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1720 28. Port number for IMAP service
1723 EXPI (EXPIre system objects)
1725 Begins purge operations for objects which, according to site policy, are
1726 "old" and should be removed. EXPI should be called with one argument, one of:
1728 "messages" (purge old messages out of each room)
1729 "users" (purge old users from the userlog)
1730 "rooms" (remove rooms which have not been posted in for some time)
1731 "visits" (purge dereferenced user/room relationship records)
1733 EXPI returns OK (probably after a long delay while it does its work) if it
1734 succeeds; otherwise it returns an ERROR code.
1736 This command is probably temporary, until we can work some sort of scheduler
1737 into the system. It is implemented in the serv_expire module.
1741 MSG4 (read MeSsaGe, mode 4 -- enumerate MIME parts)
1743 FIX ... do the writeup for this once it's done.
1747 OPNA (OPeN Attachment)
1749 Opens, as a download file, a component of a MIME-encoded message. The two
1750 parameters which must be passed to this command are the message number and the
1751 name of the desired section. If the message or section does not exist, an
1752 appropriate ERROR code will be returned; otherwise, if the open is successful,
1753 this command will succeed returning the same information as an OPEN command.
1756 GEXP (Get EXPress messages)
1758 This is a more sophisticated way of retrieving express messages than the old
1759 PEXP method. If there are no express messages waiting, PEXP returns ERROR;
1760 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1762 0 - a boolean value telling the client whether there are any additional
1763 express messages waiting following this one
1764 1 - a Unix-style timestamp
1765 2 - flags (see server.h for more info)
1766 3 - the name of the sender
1767 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1769 The text sent to the client will be the body of the express message.
1771 So how does the client know there are express messages waiting? It could
1772 execute a random GEXP every now and then. Or, it can check the byte in
1773 server return code messages, between the return code and the parameters. In
1774 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1775 an "*" in this position to signify the presence of waiting express messages.
1778 FSCK (check message base reference counts)
1780 Verify, via the long way, that all message referenmce counts are correct. If
1781 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1782 by a transcript of the run. Otherwise ERROR is returned.
1785 DEXP (Disable EXPress messages)
1787 DEXP sets or clears the "disable express messages" flag. Pass this command a
1788 1 or 0 to respectively set or clear the flag. When the "disable express
1789 messages" flag is set, no one except Aides may send the user express messages.
1790 Any value other than 0 or 1 will not change the flag, only report its state.
1791 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1792 number representing the current state of the flag.
1795 MMOD (MODerate a Message)
1797 Set or change the moderation level of a message. The two parameters passed
1798 to this command should be the message number and the desired moderation level.
1799 Please refer to the "moderation.txt" document for a description of some
1800 commonly used moderation levels.
1802 If the command succeeds, OK is returned. If the specified message does not
1803 exist in the current room, or if the specified moderation level is not within
1804 acceptable limits, ERROR+ILLEGAL_VALUE is returned. This command requires at
1805 least Room Aide access; if the calling user is not an Aide, or a Room Aide for
1806 the current room, ERROR+HIGHER_ACCESS_REQUIRED is returned.
1809 REQT (REQuest client Termination)
1811 Request that the specified client (or all clients) log off. Aide level
1812 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1815 The REQT command accepts one parameter: the session ID of the client which
1816 should be terminated, or 0 for all clients. When successful, the REQT command
1819 It should be noted that REQT simply transmits an express message to the
1820 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1821 this flag, and it is certainly possible for users to re-program their client
1822 software to ignore it. Therefore the effects of the REQT command should be
1823 considered advisory only. The recommended implementation practice is to first
1824 issue a REQT command, then wait a little while (from 30 seconds up to a few
1825 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1826 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1827 you are logging off users for the purpose of shutting down the server).
1830 SEEN (set or clear the SEEN flag for a message)
1832 Beginning with version 5.80, Citadel supports the concept of setting or
1833 clearing the "seen" flag for each individual message, instead of only allowing
1834 a "last seen" pointer. In fact, the old semantics are implemented in terms
1835 of the new semantics. This command requires two arguments: the number of the
1836 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1838 This command returns OK, unless the user is not logged in or a usage error
1839 occurred, in which case it returns ERROR. Please note that no checking is
1840 done on the supplied data; if the requested message does not exist, the SEEN
1841 command simply returns OK without doing anything.
1845 ASYN (ASYNchronous message support)
1847 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
1848 only parameter specified should be 1 or 0 to indicate that the client can or
1849 cannot handle this type of messages. The server will reply OK followed by a
1850 1 or 0 to tell the client which mode it is now operating in.
1852 If the command is not available on the server (i.e. it returns ERROR), or
1853 if the command has not been executed by the client, it should be assumed that
1854 this mode of operation is NOT in effect.
1856 The client may also send any value other than 0 or 1 to simply cause the
1857 server to output its current state without changing it.
1859 When asynchronous protocol mode is in effect, the client MUST handle any
1860 asynchronous messages as they arrive, before doing anything else.
1865 ASYNCHRONOUS MESSAGES
1866 ---------------------
1868 When the client protocol is operating in asynchronous mode (please refer to
1869 the writeup of the ASYN command above), the following messages may arrive at
1873 901 (express message arriving)
1875 There is an express message intended for this client. When the client
1876 receives this message, it MUST act as if it just sent a GEXP command (the data
1877 following the 901 message WILL be a LISTING_FOLLOWS data transfer; in fact,
1878 the current implementation simply executes a GEXP command internally).