1 SESSION LAYER PROTOCOL FOR CITADEL/UX
2 (c) 1995-2002 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.
194 Please note that the NEWU command should only be used for self-service user account
195 creation. For administratively creating user accounts, please use the CREU command.
198 SETP (SET new Password)
200 This command sets a new password for the currently logged in user. The
201 argument to this command will be the new password. The command always
202 returns OK, unless the client is not logged in, in which case it will return
206 CREU (CREate new User account)
208 This command creates a new user account AND DOES NOT LOG IT IN. The argument to
209 this command will be the name of the account. No case conversion is done
210 on the name. Note that the new account is installed with a default
211 configuration, and no password. This command returns OK if the account was created,
212 or ERROR if another user already exists with this name.
214 Please note that CREU is intended to be used for activities in which a system
215 administrator is creating user accounts. For self-service user account creation,
216 use the NEWU command.
220 LKRN (List Known Rooms with New messages)
222 List known rooms with new messages. If the client is not logged in, ERROR
223 is returned. Otherwise, LISTING_FOLLOWS is returned, followed by the room
224 listing. Each line in the listing contains the full name of a room, followed
225 by the '|' symbol, and then a number that may contain the following bits:
228 #define QR_PERMANENT 1 /* Room does not purge */
229 #define QR_PRIVATE 4 /* Set for any type of private room */
230 #define QR_PASSWORDED 8 /* Set if there's a password too */
231 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
232 #define QR_DIRECTORY 32 /* Directory room */
233 #define QR_UPLOAD 64 /* Allowed to upload */
234 #define QR_DOWNLOAD 128 /* Allowed to download */
235 #define QR_VISDIR 256 /* Visible directory */
236 #define QR_ANONONLY 512 /* Anonymous-Only room */
237 #define QR_ANON2 1024 /* Anonymous-Option room */
238 #define QR_NETWORK 2048 /* Shared network room */
239 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
240 #define QR_READONLY 8192 /* Aide status required to post */
243 Other bits may be defined in the future. The listing terminates, as with
244 all listings, with "000" on a line by itself.
246 Starting with version 4.01 and above, floors are supported. The first
247 argument to LKRN should be the number of the floor to list rooms from. Only
248 rooms from this floor will be listed. If no arguments are passed to LKRN, or
249 if the floor number requested is (-1), rooms on all floors will be listed.
251 The third field displayed on each line is the number of the floor the room
252 is on. The LFLR command should be used to associate floor numbers with
255 The fourth field displayed on each line is a "room listing order." Unless
256 there is a compelling reason not to, clients should sort any received room
257 listings by this value.
261 LKRO (List Known Rooms with Old [no new] messages)
263 This follows the same usage and format as LKRN.
266 LZRM (List Zapped RooMs)
268 This follows the same usage and format as LKRN and LKRO.
271 LKRA (List All Known Rooms)
273 Same format. Lists all known rooms, with or without new messages.
276 LRMS (List all accessible RooMS)
278 Again, same format. This command lists all accessible rooms, known and
279 forgotten, with and without new messages. It does not, however, list
280 inaccessible private rooms.
283 GETU (GET User configuration)
285 This command retrieves the screen dimensions and user options for the
286 currently logged in account. ERROR will be returned if no user is logged
287 in, of course. Otherwise, OK will be returned, followed by four parameters.
288 The first parameter is the user's screen width, the second parameter is the
289 user's screen height, and the third parameter is a bag of bits with the
292 #define US_LASTOLD 16 /* Print last old message with new */
293 #define US_EXPERT 32 /* Experienced user */
294 #define US_UNLISTED 64 /* Unlisted userlog entry */
295 #define US_NOPROMPT 128 /* Don't prompt after each message */
296 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
297 #define US_PAGINATOR 2048 /* Pause after each screen of text */
299 There are other bits, too, but they can't be changed by the user (see below).
302 SETU (SET User configuration)
304 This command does the opposite of SETU: it takes the screen dimensions and
305 user options (which were probably obtained with a GETU command, and perhaps
306 modified by the user) and writes them to the user account. This command
307 should be passed three parameters: the screen width, the screen height, and
308 the option bits (see above).
310 Note that there exist bits here which are not listed in this document. Some
311 are flags that can only be set by Aides or the system administrator. SETU
312 will ignore attempts to toggle these bits. There also may be more user
313 settable bits added at a later date. To maintain later downward compatibility,
314 the following procedure is suggested:
316 1. Execute GETU to read the current flags
317 2. Toggle the bits that we know we can toggle
318 3. Execute SETU to write the flags
320 If we are passed a bit whose meaning we don't know, it's best to leave it
321 alone, and pass it right back to the server. That way we can use an old
322 client on a server that uses an unknown bit without accidentally clearing
323 it every time we set the user's configuration.
328 This command is used to goto a new room. When the user first logs in (login
329 is completed after execution of the PASS command) this command is
330 automatically and silently executed to take the user to the first room in the
331 system (usually called the Lobby).
333 This command can be passed one or two parameters. The first parameter is,
334 of course, the name of the room. Although it is not case sensitive, the
335 full name of the room must be used. Wildcard matching or unique string
336 matching of room names should be the responsibility of the client.
338 Note that the reserved room name "_BASEROOM_" can be passed to the server
339 to cause the goto command to take the user to the first room in the system,
340 traditionally known as the Lobby>. As long as a user is logged in, a
341 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
342 allow client software to return to the base room when it doesn't know
345 There are also two additional reserved room names:
346 "_MAIL_" translates to the system's designated room for e-mail messages.
347 "_BITBUCKET_" goes to whatever room has been chosen for messages
350 The second (and optional) parameter is a password, if one is required for
351 access to the room. This allows for all types of rooms to be accessed via
352 this command: for public rooms, invitation-only rooms to which the user
353 has access, and preferred users only rooms to which the user has access, the
354 room will appear in a room listing. For guess-name rooms, this command
355 will work transparently, adding the room to the user's known room list when
356 it completes. For passworded rooms, access will be denied if the password
357 is not supplied or is incorrect, or the command will complete successfully
358 if the password is correct.
360 The possible result codes are:
362 OK - The command completed successfully. User is now in the room.
363 (See the list of returned parameters below)
365 ERROR - The command did not complete successfully. Check the second and
366 third positions of the result code to find out what happened:
368 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
369 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
370 password was incorrect.
371 NO_SUCH_ROOM - The requested room does not exist.
373 The typical procedure for entering a passworded room would be:
375 1. Execute a GOTO command without supplying any password.
376 2. ERROR+PASSWORD_REQUIRED will be returned. The client now knows that
377 the room is passworded, and prompts the user for a password.
378 3. Execute a GOTO command, supplying both the room name and the password.
379 4. If OK is returned, the command is complete. If, however,
380 ERROR+PASSWORD_REQUIRED is still returned, tell the user that the supplied
381 password was incorrect. The user remains in the room he/she was previously
384 When the command succeeds, these parameters are returned:
385 0. The name of the room
386 1. Number of unread messages in this room
387 2. Total number of messages in this room
388 3. Info flag: set to nonzero if the user needs to read this room's info
389 file (see RINF command below)
390 4. Various flags associated with this room. (See LKRN cmd above)
391 5. The highest message number present in this room
392 6. The highest message number the user has read in this room
393 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
394 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
395 a regular Aide (this makes access checks easy).
396 9. The number of new Mail messages the user has (useful for alerting the
397 user to the arrival of new mail during a session)
398 10. The floor number this room resides on
399 11. The current "view" for this room (see views.txt for more info)
402 MSGS (get pointers to MeSsaGeS in this room)
404 This command obtains a listing of all the messages in the current room
405 which the client may request. This command may be passed a single parameter:
406 either "all", "old", or "new" to request all messages, only old messages, or
407 new messages. Or it may be passed two parameters: "last" plus a number, in
408 which case that many message pointers will be returned, or "first" plus a
409 number, for the corresponding effect. If no parameters are specified, "all"
412 In Citadel/UX 5.00 and above, the client may also specify "gt" plus a number,
413 to list all messages in the current room with a message number greater than
416 The third argument, valid only in Citadel/UX 5.60 and above, may be either
417 0 or 1. If it is 1, this command behaves differently: before a listing is
418 returned, the client must transmit a list of fields to search for. The field
419 headers are listed below in the writeup for the "MSG0" command.
421 This command can return three possible results. An ERROR code may be returned
422 if no user is currently logged in or if something else went wrong. Otherwise,
423 LISTING_FOLLOWS will be returned, and the listing will consist of zero or
424 more message numbers, one per line. The listing ends, as always, with the
425 string "000" alone on a line by itself. The listed message numbers can be used
426 to request messages from the system. If "search mode" is being used, the
427 server will return START_CHAT_MODE, and the client is expected to transmit
428 the search criteria, and then read the message list.
430 Since this is somewhat complex, here are some examples:
432 Example 1: Read all new messages
435 Server: 100 Message list...
441 Example 2: Read the last five messages
444 Server: 100 Message list...
452 Example 3: Read all messages written by "IGnatius T Foobar"
455 Server: 800 Send template then receive message list
456 Client: from|IGnatius T Foobar
470 Note that in "search mode" the client may specify any number of search
471 criteria. These criteria are applied with an AND logic.
475 MSG0 (read MeSsaGe, mode 0)
477 This is a command used to read the text of a message. "Mode 0" implies that
478 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
479 messages in more robust formats. This command should be passed two arguments.
480 The first is the message number of the message being requested. In server
481 version 4.04 and above, the second argument may be set to either 0 to read the
482 entire message, or 1 to read the headers only.
484 The server should, of course, make sure that the client actually has access
485 to the message being requested before honoring this request. Citadel/UX does
486 so by checking the message number against the contents of the current room. If
487 it's not there, the request is denied.
489 If the request is denied, an ERROR code will be returned. Otherwise, the
490 LISTING_FOLLOWS code will be returned, followed by the contents of the message.
491 The following fields may be sent:
493 type= Formatting type. The currently defined types are:
494 0 = "traditional" Citadel formatting. This means that newlines should be
495 treated as spaces UNLESS the first character on the next line is a space. In
496 other words, only indented lines should generate a newline on the user's screen
497 when the message is being displayed. This allows a message to be formatted to
498 the reader's screen width. It also allows the use of proportional fonts.
499 1 = a simple fixed-format message. The message should be displayed to
500 the user's screen as is, preferably in a fixed-width font that will fit 80
502 4 = MIME format message. The message text is expected to contain a header
503 with the "Content-type:" directive (and possibly others).
505 msgn= The message ID of this message on the system it originated on.
506 path= An e-mailable path back to the user who wrote the message.
508 time= The date and time of the message, in Unix format (the number of
509 seconds since midnight on January 1, 1970, GMT).
511 from= The name of the author of the message.
512 rcpt= If the message is a private e-mail, this is the recipient.
513 room= The name of the room the message originated in.
514 node= The short node name of the system this message originated on.
515 hnod= The long node name of the system this message originated on.
516 zaps= The id/node of a message which this one zaps (supersedes).
518 text Note that there is no "=" after the word "text". This string
519 signifies that the message text begins on the next line.
522 WHOK (WHO Knows room)
524 This command is available only to Aides. ERROR+HIGHER_ACCESS_REQUIRED will
525 be returned if the user is not an Aide. Otherwise, it returns
526 LISTING_FOLLOWS and then lists, one user per line, every user who has
527 access to the current room.
530 INFO (get server INFO)
532 This command will *always* return LISTING_FOLLOWS and then print out a
533 listing of zero or more strings. Client software should be written to expect
534 anywhere from a null listing to an infinite number of lines, to allow later
535 backward compatibility. The current implementation defines the following
536 parts of the listing:
538 Line 1 - Your unique session ID on the server
539 Line 2 - The node name of the server BBS
540 Line 3 - Human-readable node name of the server BBS
541 Line 4 - The fully-qualified domain name (FQDN) of the server
542 Line 5 - The name of the server software, i.e. "Citadel/UX 4.00"
543 Line 6 - (The revision level of the server code) * 100
544 Line 7 - The geographical location of the BBS (city and state if in the US)
545 Line 8 - The name of the system administrator
546 Line 9 - A number identifying the server type (see below)
547 Line 10 - The text of the system's paginator prompt
548 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
549 Line 12 - Paging level. 0 if the system only supports inline paging,
550 1 if the system supports "extended" paging (check-only and
551 multiline modes). See the SEXP command for further information.
552 Line 13 - The "nonce" for this session, for support of APOP-style
553 authentication. If this field is present, clients may authenticate
555 Line 14 - Set to nonzero if this server supports the QNOP command.
557 *** NOTE! *** The "server type" code is intended to promote global
558 compatibility in a scenario in which developers have added proprietary
559 features to their servers or clients. We are attempting to avoid a future
560 situation in which users need to keep different client software around for
561 each BBS they use. *Please*, if you are a developer and plan to add
562 proprietary features:
564 -> Your client programs should still be able to utilize servers other than
566 -> Clients other than your own should still be able to utilize your server,
567 even if your proprietary extensions aren't supported.
568 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
569 server type code, which can be assigned to your server program.
570 -> If you document what you did in detail, perhaps it can be added to a
571 future release of the Citadel/UX program, so everyone can enjoy it. Better
572 yet, just work with the Citadel development team on the main source tree.
574 If everyone follows this scheme, we can avoid a chaotic situation with lots
575 of confusion about which client program works with which server, etc. Client
576 software can simply check the server type (and perhaps the revision level)
577 to determine ahead of time what commands may be utilized.
579 Please refer to "developers.txt" for information on what codes belong to whom.
583 RDIR (Read room DIRectory)
585 Use this command to read the directory of a directory room. ERROR+NOT_HERE
586 will be returned if the room has no directory, or some other error; ERROR +
587 HIGHER_ACCESS_REQUIRED will be returned if the room's directory is not
588 visible and the user does not have Aide or Room Aide privileges; otherwise
589 LISTING_FOLLOWS will be returned, followed by the room's directory. Each
590 line of the directory listing will contain three fields: a filename, the
591 length of the file, and a description.
593 The server message contained on the same line with LISTING_FOLLOWS will
594 contain the name of the system and the name of the directory, such as:
595 uncensored.citadel.org|/usr/bbs/files/my_room_directory
598 SLRP (Set Last-message-Read Pointer)
600 This command marks all messages in the current room as read (seen) up to and
601 including the specified number. Its sole parameter
602 is the number of the last message that has been read. This allows the pointer
603 to be set at any arbitrary point in the room. Optionally, the parameter
604 "highest" may be used instead of a message number, to set the pointer to the
605 number of the highest message in the room, effectively marking all messages
606 in the room as having been read (ala the Citadel <G>oto command).
608 The command will return OK if the pointer was set, or ERROR if something
609 went wrong. If OK is returned, it will be followed by a single argument
610 containing the message number the last-read-pointer was set to.
613 INVT (INViTe a user to a room)
615 This command may only be executed by Aides, or by the room aide for the
616 current room. It is used primarily to add users to invitation-only rooms,
617 but it may also be used in other types of private rooms as well. Its sole
618 parameter is the name of the user to invite.
620 The command will return OK if the operation succeeded, or ERROR if it did
621 not. ERROR+HIGHER_ACCESS_REQUIRED may also be returned if the operation
622 would have been possible if the user had higher access, and ERROR+NOT_HERE
623 may be returned if the room is not a private room.
626 KICK (KICK a user out of a room)
628 This is the opposite of INVT: it is used to kick a user out of a private
629 room. It can also be used to kick a user out of a public room, but the
630 effect will only be the same as if the user <Z>apped the room - a non-stupid
631 user can simply un-zap the room to get back in.
634 GETR (GET Room attributes)
636 This command is used for editing the various attributes associated with a
637 room. A typical "edit room" command would work like this:
638 1. Use the GETR command to get the current attributes
639 2. Change some of them around
640 3. Use SETR (see below) to save the changes
641 4. Possibly also change the room aide using the GETA and SETA commands
643 GETR takes no arguments. It will only return OK if the SETR command will
644 also return OK. This allows client software to tell the user that he/she
645 can't edit the room *before* going through the trouble of actually doing the
646 editing. Possible return codes are:
648 ERROR+NOT_LOGGED_IN - No user is logged in.
649 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
650 and the room aide associated with the current room, can access this command.
651 ERROR+NOT_HERE - Lobby>, Mail>, and Aide> cannot be edited.
652 OK - Command succeeded. Parameters are returned.
654 If OK is returned, the following parameters will be returned as well:
656 0. The name of the room
657 1. The room's password (if it's a passworded room)
658 2. The name of the room's directory (if it's a directory room)
659 3. Various flags (bits) associated with the room (see LKRN cmd above)
660 4. The floor number on which the room resides
661 5. The room listing order
662 6. The default view for the room (see views.txt)
665 SETR (SET Room attributes)
667 This command sets various attributes associated with the current room. It
668 should be passed the following arguments:
670 0. The name of the room
671 1. The room's password (if it's a passworded room)
672 2. The name of the room's directory (if it's a directory room)
673 3. Various flags (bits) associated with the room (see LKRN cmd above)
674 4. "Bump" flag (see below)
675 5. The floor number on which the room should reside
676 6. The room listing order
677 7. The default view for the room (see views.txt)
679 *Important: You should always use GETR to retrieve the current attributes of
680 the room, then change what you want to change, and then use SETR to write it
681 all back. This is particularly important with respect to the flags: if a
682 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
683 only toggle the bits you want to toggle. This will allow for upward
686 If the room is a private room, you have the option of causing all users who
687 currently have access, to forget the room. If you want to do this, set the
688 "bump" flag to 1, otherwise set it to 0.
693 This command is used to get the name of the Room Aide for the current room.
694 It will return ERROR+NOT_LOGGED_IN if no user is logged in, ERROR if there
695 is no current room, or OK if the command succeeded. Along with OK there will
696 be returned one parameter: the name of the Room Aide.
701 The opposite of GETA, used to set the Room Aide for the current room. One
702 parameter should be passed, which is the name of the user who is to be the
703 new Room Aide. Under Citadel/UX, this command may only be executed by Aides
704 and by the *current* Room Aide for the room. Return codes possible are:
705 ERROR+NOT_LOGGED_IN (Not logged in.)
706 ERROR+HIGHER_ACCESS_REQUIRED (Higher access required.)
707 ERROR+NOT_HERE (No current room, or room cannot be edited.
708 Under Citadel/UX, the Lobby> Mail> and Aide> rooms are non-editable.)
709 OK (Command succeeded.)
712 ENT0 (ENTer message, mode 0)
714 This command is used to enter messages into the system. It accepts four
717 0 - Post flag. This should be set to 1 to post a message. If it is
718 set to 0, the server only returns OK or ERROR (plus any flags describing
719 the error) without reading in a message. Client software should, in fact,
720 perform this operation at the beginning of an "enter message" command
721 *before* starting up its editor, so the user does not end up typing a message
722 in vain that will not be permitted to be saved. If it is set to 2, the
723 server will accept an "apparent" post name if the user is privileged enough.
724 This post name is arg 4.
725 1 - Recipient. This argument is utilized only for private mail messages.
726 It is ignored for public messages. It contains, of course, the name of the
727 recipient of the message.
728 2 - Anonymous flag. This argument is ignored unless the room allows
729 anonymous messages. In such rooms, this flag may be set to 1 to flag a
730 message as anonymous, otherwise 0 for a normal message.
731 3 - Format type. Any valid Citadel/UX format type may be used (this will
732 typically be 0; see the MSG0 command above).
733 4 - Post name. When postflag is 2, this is the name you are posting as.
734 This is an Aide only command.
736 Possible result codes:
737 OK - The request is valid. (Client did not set the "post" flag, so the
738 server will not read in message text.) If the message is an e-mail with
739 a recipient, the text that follows the OK code will contain the exact name
740 to which mail is being sent. The client can display this to the user. The
741 implication here is that the name that the server returns will contain the
742 correct upper and lower case characters. In addition, if the recipient is
743 having his/her mail forwarded, the forwarding address will be returned.
744 SEND_LISTING - The request is valid. The client should now transmit
745 the text of the message (ending with a 000 on a line by itself, as usual).
746 ERROR - Miscellaneous error. (Explanation probably follows.)
747 ERROR + NOT_LOGGED_IN - Not logged in.
748 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
749 explanation follows, worded in a form that can be displayed to the user.
750 ERROR + NO_SUCH_USER - The specified recipient does not exist.
753 RINF (read Room INFormation file)
755 Each room has associated with it a text file containing a description of
756 the room, perhaps containing its intended purpose or other important
757 information. The info file for the Lobby> (the system's base room) is
758 often used as a repository for system bulletins and the like.
760 This command, which accepts no arguments, is simply used to read the info
761 file for the current room. It will return LISTING_FOLLOWS followed by
762 the text of the message (always in format type 0) if the request can be
763 honored, or ERROR if no info file exists for the current room (which is
764 often the case). Other error description codes may accompany this result.
766 When should this command be used? This is, of course, up to the discretion
767 of client software authors, but in Citadel it is executed in two situations:
768 the first time the user ever enters a room; and whenever the contents of the
769 file change. The latter can be determined from the result of a GOTO command,
770 which will tell the client whether the file needs to be read (see GOTO above).
773 DELE (DELEte a message)
775 Delete a message from the current room. The one argument that should be
776 passed to this command is the message number of the message to be deleted.
777 The return value will be OK if the message was deleted, or an ERROR code.
778 If the delete is successful, the message's reference count is decremented, and
779 if the reference count reaches zero, the message is removed from the message
783 MOVE (MOVE or copy a message to a different room)
785 Move a message to a different room. The two arguments that should be passed
786 to this command are the message number of the message to be deleted, and the
787 name of the target room. If the operation succeeds, the message will be
788 deleted from the current room and moved to the target room. An ERROR code
789 usually means that either the user does not have permission to perform this
790 operation, or that the target room does not exist.
792 In Citadel/UX 5.55 and above, a third argument may be specified: 0 or 1 to
793 designate whether the message should be moved (0) or copied (1) to the target
794 room. In the case of a "copy" operation, the message's reference count is
795 incremented, and a pointer to the message will exist in both the source *and*
796 target rooms. In the case of a "move" operation, the message pointer is
797 deleted from the source room and the reference count remains the same.
800 KILL (KILL current room)
802 This command deletes the current room. It accepts a single argument, which
803 should be nonzero to actually delete the room, or zero to merely check
804 whether the room can be deleted.
806 Once the room is deleted, the current room is undefined. It is suggested
807 that client software immediately GOTO another room (usually _BASEROOM_)
808 after this command completes.
810 Possible return codes:
812 OK - room has been deleted (or, if checking only, request is valid).
813 ERROR+NOT_LOGGED_IN - no user is logged in.
814 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
815 ERROR+NOT_HERE - this room can not be deleted.
818 CRE8 (CRE[ate] a new room)
820 This command is used to create a new room. Like some of the other
821 commands, it provides a mechanism to first check to see if a room can be
822 created before actually executing the command. CRE8 accepts the following
825 0 - Create flag. Set this to 1 to actually create the room. If it is
826 set to 0, the server merely checks that there is a free slot in which to
827 create a new room, and that the user has enough access to create a room. It
828 returns OK if the client should go ahead and prompt the user for more info,
829 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
830 1 - Name for new room.
831 2 - Access type for new room:
833 1 - Private; can be entered by guessing the room's name
834 2 - Private; can be entered by knowing the name *and* password
835 3 - Private; invitation only (sometimes called "exclusive")
836 3 - Password for new room (if it is a type 2 room)
837 4 - Floor number on which the room should reside (optional)
839 If the create flag is set to 1, the room is created (unless something
840 went wrong and an ERROR return is sent), and the server returns OK, but
841 the session is **not** automatically sent to that room. The client still
842 must perform a GOTO command to go to the new room.
845 FORG (FORGet the current room)
847 This command is used to forget (zap) the current room. For those not
848 familiar with Citadel, this terminology refers to removing the room from
849 a user's own known rooms list, *not* removing the room itself. After a
850 room is forgotten, it no longer shows up in the user's known room list,
851 but it will exist in the user's forgotten room list, and will return to the
852 known room list if the user goes to the room (in Citadel, this is
853 accomplished by explicitly typing the room's name in a <.G>oto command).
855 The command takes no arguments. If the command cannot execute for any
856 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
857 be returned as they apply.
859 If the command succeeds, OK will be returned. At this point, the current
860 room is **undefined**, and the client software is responsible for taking
861 the user to another room before executing any other room commands (usually
862 this will be _BASEROOM_ since it is always there).
865 MESG (read system MESsaGe)
867 This command is used to display system messages and/or help files. The
868 single argument it accepts is the name of the file to display. IT IS CASE
869 SENSITIVE. Citadel/UX looks for these files first in the "messages"
870 subdirectory and then in the "help" subdirectory.
872 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
873 to the file being displayed. Then the message is printed, in format type 0
874 (see MSG0 command for more information on this). If the file is not found,
877 There are some "well known" names of system messages which client software
878 may expect most servers to carry:
880 hello - Welcome message, to be displayed before the user logs in.
881 changepw - To be displayed whenever the user is prompted for a new
882 password. Warns about picking guessable passwords and such.
883 register - Should be displayed prior to the user entering registration.
884 Warnings about not getting access if not registered, etc.
885 help - Main system help file.
886 goodbye - System logoff banner; display when user logs off.
887 roomaccess - Information about how public rooms and different types of
888 private rooms function with regards to access.
889 unlisted - Tells users not to choose to be unlisted unless they're
890 really paranoid, and warns that aides can still see
891 unlisted userlog entries.
893 Citadel/UX provides these for the Citadel/UX Unix text client. They are
894 probably not very useful for other clients:
896 mainmenu - Main menu (when in idiot mode).
901 saveopt - Options to save a message, abort, etc.
902 entermsg - Displayed just before a message is entered, when in
906 GNUR (Get Next Unvalidated User)
908 This command shows the name of a user that needs to be validated. If there
909 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
910 along with the name of the first unvalidated user the server finds. All of
911 the usual ERROR codes may be returned as well (for example, if the user is
912 not an Aide and cannot validate users).
914 A typical "Validate New Users" command would keep executing this command,
915 and then validating each user it returns, until it returns OK when all new
916 users have been validated.
919 GREG (Get REGistration for user)
921 This command retrieves the registration info for a user, whose name is the
922 command's sole argument. All the usual error messages can be returned. If
923 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
924 (retrieved from the userlog, with the right upper and lower case etc.) The
925 contents of the listing contains one field per line, followed by the usual
926 000 on the last line.
928 The following lines are defined. Others WILL be added in the futre, so all
929 software should be written to read the lines it knows about and then ignore
935 Line 4: Street address or PO Box
936 Line 5: City/town/village/etc.
937 Line 6: State/province/etc.
939 Line 8: Telephone number
941 Line 10: Internet e-mail address
944 Users without Aide privileges may retrieve their own registration using
945 this command. This can be accomplished either by passing the user's own
946 name as the argument, or the string "_SELF_". The command will always
947 succeed when used in this manner, unless no user is logged in.
952 This command is used to validate users. Obviously, it can only be executed
953 by users with Aide level access. It should be passed two parameters: the
954 name of the user to validate, and the desired access level
956 If the command succeeds, OK is returned. The user's access level is changed
957 and the "need validation" bit is cleared. If the command fails for any
958 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
962 EINF (Enter INFo file for room)
964 Transmit the info file for the current room with this command. EINF uses
965 a boolean flag (1 or 0 as the first and only argument to the command) to
966 determine whether the client actually wishes to transmit a new info file, or
967 is merely checking to see if it has permission to do so.
969 If the command cannot succeed, it returns ERROR.
970 If the client is only checking for permission, and permission will be
971 granted, OK is returned.
972 If the client wishes to transmit the new info file, SEND_LISTING is
973 returned, and the client should transmit the text of the info file, ended
974 by the usual 000 on a line by itself.
979 This is a simple user listing. It always succeeds, returning
980 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
981 fields on each line are as follows:
986 4. Date/time of last login (Unix format)
989 7. Password (listed only if the user requesting the list is an Aide)
991 Unlisted entries will also be listed to Aides logged into the server, but
992 not to ordinary users.
995 REGI (send REGIstration)
997 Clients will use this command to transmit a user's registration info. If
998 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
999 SEND_LISTING is returned, and the server will expect the following information
1000 (terminated by 000 on a line by itself):
1003 Line 2: Street address or PO Box
1004 Line 3: City/town/village/etc.
1005 Line 4: State/province/etc.
1007 Line 6: Telephone number
1008 Line 7: e-mail address
1012 CHEK (CHEcK various things)
1014 When logging in, there are various things that need to be checked. This
1015 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
1016 it returns OK and the following parameters:
1018 0: Number of new private messages in Mail>
1019 1: Nonzero if the user needs to register
1020 2: (Relevant to Aides only) Nonzero if new users require validation
1023 DELF (DELete a File)
1025 This command deletes a file from the room's directory, if there is one. The
1026 name of the file to delete is the only parameter to be supplied. Wildcards
1027 are not acceptable, and any slashes in the filename will be converted to
1028 underscores, to prevent unauthorized access to neighboring directories. The
1029 possible return codes are:
1031 OK - Command succeeded. The file was deleted.
1032 ERROR+NOT_LOGGED_IN - Not logged in.
1033 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1034 ERROR+NOT_HERE - There is no directory in this room.
1035 ERROR+FILE_NOT_FOUND - Requested file was not found.
1040 This command is similar to DELF, except that it moves a file (and its
1041 associated file description) to another room. It should be passed two
1042 parameters: the name of the file to move, and the name of the room to move
1043 the file to. All of the same return codes as DELF may be returned, and also
1044 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1045 does not exist. ERROR+NOT_HERE could also mean that the target room does
1046 not have a directory.
1049 NETF (NETwork send a File)
1051 This command is similar to MOVF, except that it attempts to send a file over
1052 the network to another system. It should be passed two parameters: the name
1053 of the file to send, and the node name of the system to send it to. All of
1054 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1055 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1058 The name of the originating room will be sent along with the file. Most
1059 implementations will look for a room with the same name at the receiving end
1060 and attempt to place the file there, otherwise it goes into a bit bucket room
1061 for miscellaneous files. This is, however, beyond the scope of this document;
1062 see elsewhere for more details.
1065 RWHO (Read WHO's online)
1067 Displays a list of all users connected to the server. No error codes are
1068 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1069 lines containing the following three fields:
1071 0 - Session ID. Citadel/UX fills this with the pid of a server program.
1073 2 - The name of the room the user is currently in. This field might not
1074 be displayed (for example, if the user is in a private room) or it might
1075 contain other information (such as the name of a file the user is
1077 3 - (server v4.03 and above) The name of the host the client is connecting
1078 from, or "localhost" if the client is local.
1079 4 - (server v4.04 and above) Description of the client software being used
1080 5 - The last time, locally to the server, that a command was received from
1081 this client (Note: NOOP's don't count)
1082 6 - The last command received from a client. (NOOP's don't count)
1083 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1084 (posting) and . (idle).
1085 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1086 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1087 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1089 The listing is terminated, as always, with the string "000" on a line by
1093 OPEN (OPEN a file for download)
1095 This command is used to open a file for downloading. Only one download
1096 file may be open at a time. The only argument to this command is the name
1097 of the file to be opened. The user should already be in the room where the
1098 file resides. Possible return codes are:
1101 ERROR+NOT_HERE (no directory in this room)
1102 ERROR+FILE_NOT_FOUND (could not open the file)
1106 If the file is successfully opened, OK will be returned, along with the
1107 size (in bytes) of the file, the time of last modification (if applicable),
1108 the filename (if known), and the MIME type of the file (if known).
1111 CLOS (CLOSe the download file)
1113 This command is used to close the download file. It returns OK if the
1114 file was successfully closed, or ERROR if there wasn't any file open in the
1118 READ (READ from the download file)
1120 Two arguments are passed to this command. The first is the starting position
1121 in the download file, and the second is the total number of bytes to be
1122 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1123 along with the number of bytes to follow. Then, immediately following the
1124 newline, will be that many bytes of binary data. The client *must* read
1125 exactly that number of bytes, otherwise the client and server will get out
1128 If the operation cannot be performed, any of the usual error codes will be
1132 UOPN (OPeN a file for Uploading)
1134 This command is similar to OPEN, except that this one is used when the
1135 client wishes to upload a file to the server. The first argument is the name
1136 of the file to create, and the second argument is a one-line comment
1137 describing the contents of the file. Only one upload file may be open at a
1138 time. Possible return codes are:
1141 ERROR+NOT_HERE (no directory in this room)
1142 ERROR+FILE_NOT_FOUND (a name must be specified)
1143 ERROR (miscellaneous errors)
1144 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1147 If OK is returned, the command has succeeded and writes may be performed.
1150 UCLS (CLoSe the Upload file)
1152 Close the file opened with UOPN. An argument of "1" should be passed to
1153 this command to close and save the file; otherwise, the transfer will be
1154 considered aborted and the file will be deleted. This command returns OK
1155 if the operation succeeded or ERROR if it did not.
1158 WRIT (WRITe to the upload file)
1160 If an upload file is open, this command may be used to write to it. The
1161 argument passed to this command is the number of bytes the client wishes to
1162 transmit. An ERROR code will be returned if the operation cannot be
1165 If the operation can be performed, SEND_BINARY will be returned, followed
1166 by the number of bytes the server is expecting. The client must then transmit
1167 exactly that number of bytes. Note that in the current implementation, the
1168 number of bytes the server is expecting will always be the number of bytes
1169 the client requested to transmit, but the client software should never assume
1170 that this will always happen, in case changes are made later.
1173 QUSR (Query for a USeR)
1175 This command is used to check to see if a particular user exists. The only
1176 argument to this command is the name of the user being searched for. If
1177 the user exists, OK is returned, along with the name of the user in the userlog
1178 (so the client software can learn the correct upper/lower casing of the name
1179 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1180 No login or current room is required to utilize this command.
1183 OIMG (Open an IMaGe file)
1185 Open an image (graphics) file for downloading. Once opened, the file can be
1186 read as if it were a download file. This implies that an image and a download
1187 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1189 All images will be in GIF (Graphics Interchange Format). In the case of
1190 Citadel/UX, the server will convert the supplied filename to all lower case,
1191 append the characters ".gif" to the filename, and look for it in the "images"
1192 subdirectory. As with the MESG command, there are several "well known"
1193 images which are likely to exist on most servers:
1195 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1196 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1197 background - Background image (usually tiled) for graphical clients
1199 The following "special" image names are defined in Citadel/UX server version
1202 _userpic_ - Picture of a user (send the username as the second argument)
1203 _floorpic_ - A graphical floor label (send the floor number as the second
1204 argument). Clients which request a floor picture will display
1205 the picture *instead* of the floor name.
1206 _roompic_ - A graphic associated with the *current* room. Clients which
1207 request a room picture will display the picture in *addition*
1208 to the room name (i.e. it's used for a room banner, as
1209 opposed to the floor picture's use in a floor listing).
1212 NETP (authenticate as network session with system NET Password)
1214 This command is used by client software to identify itself as a transport
1215 session for IGnet/Open BBS to BBS networking. It should be called with
1216 two arguments: the node name of the calling system, and the system net
1217 password for the server. If the authentication succeeds, NETP will return
1218 OK, otherwise, it returns ERROR.
1221 NUOP (Network Upload OPen file)
1223 Open a network spool file for uploading. The client must have already
1224 identified itself as a network session using the NETP command. If the command
1225 returns OK, the client may begin transmitting IGnet/Open spool data using
1226 a series of WRIT commands. When a UCLS command is issued, the spooled data
1227 is entered into the BBS if the argument to UCLS is 1 or discarded if the
1228 argument to UCLS is 0. If the client has not authenticated itself with a
1229 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1232 NDOP (Network Download OPen file)
1234 Open a network spool file for downloading. The client must have already
1235 identified itself as a network session using the NETP command. If the command
1236 returns OK, the client may begin receiving IGnet/Open spool data using
1237 a series of READ commands. When a CLOS command is issued, the spooled data
1238 is deleted from the server and may not be read again. If the client has not
1239 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1243 LFLR (List all known FLooRs)
1245 On systems supporting floors, this command lists all known floors. The
1246 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1247 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1248 the available floors, each line consisting of three fields:
1250 1. The floor number associated with the floor
1251 2. The name of the floor
1252 3. Reference count (number of rooms on this floor)
1255 CFLR (Create a new FLooR)
1257 This command is used to create a new floor. It should be passed two
1258 arguments: the name of the new floor to be created, and a 1 or 0 depending
1259 on whether the client is actually creating a floor or merely checking to
1260 see if it has permission to create the floor. The user must be logged in
1261 and have Aide privileges to create a floor.
1263 If the command succeeds, it will return OK followed by the floor number
1264 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1265 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1266 followed by a description of why the command failed.
1271 This command is used to delete a floor. It should be passed two
1272 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1273 on whether the client is actually deleting the floor or merely checking to
1274 see if it has permission to delete the floor. The user must be logged in
1275 and have Aide privileges to delete a floor.
1277 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1278 they must be either deleted or moved to different floors first. This implies
1279 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1280 Aide> all reside on the Main Floor and cannot be deleted.
1282 If the command succeeds, it will return OK. Otherwise it will return
1283 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1284 followed by a description of why the command failed.
1289 Edit the parameters of a floor. The client may pass one or more parameters
1292 1. The number of the floor to be edited
1293 2. The desired new name
1295 More parameters may be added in the future. Any parameters not passed to
1296 the server will remain unchanged. A minimal command would be EFLR and a
1297 floor number -- which would do nothing. EFLR plus the floor number plus a
1298 floor name would change the floor's name.
1300 If the command succeeds, it will return OK. Otherwise it will return
1301 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1304 IDEN (IDENtify the client software)
1306 The client software has the option to identify itself to the server.
1307 Currently, the server does nothing with this information except to write
1308 it to the syslog to satisfy the system administrator's curiosity. Other
1309 uses might become apparent in the future.
1311 The IDEN command should contain five fields: a developer ID number (same as
1312 the server developer ID numbers in the INFO command -- please obtain one if
1313 you are a new developer), a client ID number (which does not have to be
1314 globally unique - only unique within the domain of the developer number),
1315 a version number, a free-form text string describing the client, and the name
1316 of the host the user is located at.
1318 It is up to the server to determine whether to accept the host name or to
1319 use the host name it has detected itself. Generally, if the client is
1320 running on a trusted host (either localhost or a well-known publically
1321 accessible client) it should use the host name transmitted by IDEN,
1322 otherwise it should use the host name it has detected itself.
1324 IDEN always returns OK, but since that's the only way it ever returns
1325 there's no point in checking the result code.
1328 IPGM (identify as an Internal ProGraM)
1330 IPGM is a low-level command that should not be used by normal user clients.
1331 It is used for various utilities to communicate with the server on the same
1332 host. For example, the "sendcommand" utility logs onto the server as an
1333 internal program in order to run arbitrary server commands. Since user clients
1334 do not utilize this command (or any of its companion commands), developers
1335 writing Citadel-compatible servers need not implement it.
1337 The sole argument to IPGM is the system's internal program password. This
1338 password is generated by the setup program and stored in the config file.
1339 Since internal programs have access to the config file, they know the correct
1342 IPGM returns OK for a correct authentication or ERROR otherwise.
1345 CHAT (enter CHAT mode)
1347 This command functions differently from every other command in the system. It
1348 is used to implement multi-user chat. For this to function, a new transfer
1349 mode, called START_CHAT_MODE, is implemented. If a client does not support
1350 chat mode, it should never send a CHAT command!
1352 In chat mode, messages may arrive asynchronously from the server at any
1353 time. The client may send messages at any time. This allows the arrival of
1354 messages without the client having to poll for them. Arriving messages will
1355 be of the form "user|message", where the "user" portion is, of course, the
1356 name of the user sending the message, and "message" is the message text.
1358 Chat mode ends when the server says it ends. The server will signal the end
1359 of chat mode by transmitting "000" on a line by itself. When the client reads
1360 this line, it must immediately exit from chat mode without sending any
1361 further traffic to the server. The next transmission sent to the server
1362 will be a regular server command.
1364 The Citadel/UX server understands the following commands:
1365 /quit - Exit from chat mode (causes the server to do an 000 end)
1366 /who - List users currently in chat
1367 /whobbs - List users currently in chat and on the bbs
1368 /me - Do an irc-style action.
1369 /join - Join a new "room" in which all messages are only heard by
1370 people in that room.
1371 /msg - /msg <user> <msg> will send the msg to <user> only.
1372 /help - Print help information
1373 NOOP - Do nothing (silently)
1375 Any other non-empty string is treated as message text and will be broadcast
1376 to other users currently in chat.
1379 SEXP (Send EXPress messages)
1381 This is one of two commands which implement "express messages" (also known
1382 as "paging"). An express message is a near-real-time message sent from one
1383 logged in user to another. When an express message is sent, it will be
1384 displayed the next time the target user executes a PEXP or GEXP command.
1386 The SEXP command accepts two arguments: the name of the user to send the
1387 message to, and the text of the message. If the message is successfully
1388 transmitted, OK is returned. If the target user is not logged in or if
1389 anything else goes wrong, ERROR is returned.
1391 If the server supports extended paging, sending a zero-length message
1392 merely checks for the presence of the requested user without actually sending
1393 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1394 the server to return SEND_LISTING if the requested user is logged in, and the
1395 client can then transmit a multi-line page.
1397 The reserved name "broadcast" may be used instead of a user name, to
1398 broadcast an express message to all users currently connected to the server.
1400 Do be aware that if an express message is transmitted to a user who is logged
1401 in using a client that does not check for express messages, the message will
1405 PEXP (Print EXPress messages) ***DEPRECATED***
1407 This command is deprecated; it will eventually disappear from the protocol and
1408 its use is not recommended. Please use the GEXP command instead.
1410 Called without any arguments, PEXP simply dumps out the contents
1411 of any waiting express messages. It returns ERROR if there is a problem,
1412 otherwise it returns LISTING_FOLLOWS followed by all messages.
1414 So how does the client know there are express messages waiting? It could
1415 execute a random PEXP every now and then. Or, it can check the byte in
1416 server return code messages, between the return code and the parameters. In
1417 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1418 an "*" in this position to signify the presence of waiting express messages.
1421 EBIO (Enter BIOgraphy)
1423 Transmit to the server a free-form text file containing a little bit of
1424 information about the user for other users to browse. This is typically
1425 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1426 after which the client is expected to transmit the file, or any of the usual
1427 ERROR codes if it fails.
1430 RBIO (Read BIOgraphy)
1432 Receive from the server a named user's bio. This command should be passed
1433 a single argument - the name of the user whose bio is requested. RBIO returns
1434 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1435 The return has the following parameters: the user name, user number, access
1436 level, date of last call, times called, and messages posted. This command
1437 returns ERROR+NO_SUCH_USER if the named user does not exist.
1439 RBIO no longer considers a user with no bio on file to be an error condition.
1440 It now returns a message saying the user has no bio on file as the text of the
1441 bio. This allows newer servers to operate with older clients.
1444 STEL (enter STEaLth mode)
1446 When in "stealth mode," a user will not show up in the "Who is online"
1447 listing (the RWHO server command). Only Aides may use stealth mode. The
1448 STEL command accepts one argument: a 1 indicating that the user wishes to
1449 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1450 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1451 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide;
1452 followed by a 1 or 0 indicating the new state.
1454 If any value other than 1 or 0 is sent by the client, the server simply
1455 replies with 1 or 0 to indicate the current state without changing it.
1457 The STEL command also makes it so a user does not show up in the chat room
1461 LBIO (List users who have BIOs on file)
1463 This command is self-explanatory. Any user who has used EBIO to place a bio
1464 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1465 this listing, unless it experiences an internal error in which case ERROR
1469 MSG2 (read MeSsaGe, mode 2)
1471 MSG2 follows the same calling convention as MSG0. The difference between
1472 the two commands is that MSG2 outputs messages in standard RFC822 format
1473 rather than in Citadel/UX proprietary format.
1475 This command was implemented in order to make various gateway programs
1476 easier to implement, and to provide some sort of multimedia support in the
1477 future. Keep in mind that when this command is used, all messages will be
1478 output in fixed 80-column format.
1481 MSG3 (read MeSsaGe, mode 3 -- internal command)
1483 MSG3 is for use by internal programs only and should not be utilized by
1484 user-mode clients. It does require IPGM authentication. MSG3 follows the
1485 same calling convention as the other MSG commands, but upon success returns
1486 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1490 TERM (TERMinate another session)
1492 In a multithreaded environment, it sometimes becomes necessary to terminate
1493 a session that is unusable for whatever reason. The TERM command performs
1494 this task. Naturally, only Aides can execute TERM. The command should be
1495 called with a single argument: the session ID (obtained from an RWHO command)
1496 of the session to be terminated.
1498 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1499 a client program is prohibited from terminating the session it is currently
1505 DOWN (shut DOWN the server)
1507 This command, which may only be executed by an Aide, immediately shuts down
1508 the server. It is only implemented on servers on which such an operation is
1509 possible, such as a multithreaded Citadel engine. The server does not restart.
1510 DOWN returns OK if the user is allowed to shut down the server, in which case
1511 the client program should expect the connection to be immediately broken.
1514 SCDN (Schedule or Cancel a shutDowN)
1516 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1517 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1518 set, the server will be shut down when there are no longer any users logged in.
1519 Any value other than 0 or 1 will not change the flag, only report its state.
1520 No users will be kicked off the system, and in fact the server is still
1521 available for new connections. The command returns ERROR if it fails;
1522 otherwise, it returns OK followed by a number representing the current state
1526 EMSG (Enter a system MeSsaGe)
1528 This is the opposite of the MESG command - it allows the creation and editing
1529 of system messages. The only argument passed to EMSG is the name of the
1530 file being transmitted. If the file exists in any system message directory
1531 on the server it will be overwritten, otherwise a new file is created. EMSG
1532 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1535 Typical client software would use MESG to retrieve any existing message into
1536 an edit buffer, then present an editor to the user and run EMSG if the changes
1540 UIMG (Upload an IMaGe file)
1542 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1543 The first parameter supplied to UIMG should be 0 if the client is only checking
1544 for permission to upload, or 1 if the client is actually attempting to begin
1545 the upload operation. The second argument is the name of the file to be
1546 transmitted. In Citadel/UX, the filename is converted to all lower case,
1547 appended with the characters ".gif", and stored in the "images" directory.
1549 UIMG returns OK if the client has permission to perform the requested upload,
1550 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1551 the operation (first parameter set to 1), an upload file is opened, and the
1552 client should begin writing to it with WRIT commands, then close it with a
1555 The supplied filename should be one of:
1557 -> _userpic_ (Server will attempt to write to the user's online photo)
1558 -> Any of the "well known" filenames described in the writeup for the
1562 HCHG (Hostname CHanGe)
1564 HCHG is a command, usable by any user, that allows a user to change their RWHO
1565 host value. This will mask a client's originating hostname from normal
1566 users; access level 6 and higher can see, in an extended wholist, the actual
1567 hostname the user originates from.
1569 The format of an HCHG command is:
1573 If a HCHG command is successful, the value OK (200) is returned.
1576 RCHG (Roomname CHanGe)
1578 RCHG is a command, usable by any user, that allows a user to change their RWHO
1579 room value. This will mask a client's roomname from normal users; access
1580 level 6 and higher can see, in an extended wholist, the actual room the user
1583 The format of an RCHG command is:
1587 If a RCHG command is successful, the value OK (200) is returned.
1590 UCHG (Username CHanGe)
1592 UCHG is an aide-level command which allows an aide to effectively change their
1593 username. If this value is blank, the user goes into stealth mode (see
1595 will show up as being from the real username in this mode, however. In
1596 addition, the RWHO listing will include both the spoofed and real usernames.
1598 The format of an UCHG command is:
1602 If a UCHG command is successful, the value OK (200) is returned.
1605 TIME (get server local TIME)
1607 TIME returns OK followed by the current time measured in seconds since
1608 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1610 This is used in allowing a client to calculate idle times.
1613 AGUP (Administrative Get User Parameters)
1614 ASUP (Administrative Set User Parameters)
1616 These commands are only executable by Aides and by server extensions running
1617 at system-level. They are used to get/set any and all parameters relating to
1618 a user account. AGUP requires only one argument: the name of the user in
1619 question. SGUP requires all of the parameters to be set. The parameters are
1620 as follows, and are common to both commands:
1624 2 - Flags (see citadel.h)
1629 7 - Timestamp of last call
1630 8 - Purge time (in days) for this user (or 0 to use system default)
1632 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1633 simply returns OK. If the client has insufficient access to perform the
1634 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1635 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1639 GPEX (Get Policy for message EXpiration)
1641 Returns the policy of the current room, floor, or site regarding the automatic
1642 purging (expiration) of messages. The following policies are available:
1643 0 - Fall back to the policy of the next higher level. If this is a room,
1644 use the floor's default policy. If this is a floor, use the system
1645 default policy. This is an invalid value for the system policy.
1646 1 - Do not purge messages automatically.
1647 2 - Purge by message count. (Requires a value: number of messages)
1648 3 - Purge by message age. (Requires a value: number of days)
1650 The format of this command is: GPEX <which>
1651 The value of <which> must be one of: "room" "floor" "site"
1653 If successful, GPEX returns OK followed by <policy>|<value>.
1657 SPEX (Set Policy for message EXpiration)
1659 Sets the policy of the current room, floor, or site regarding the automatic
1660 purging (expiration) of messages. See the writeup for the GPEX command for
1661 the list of available policies.
1663 The format of this command is: SPEX <which>|<policy>|<value>
1664 The value of <which> must be one of: "room" "floor" "site"
1666 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1670 CONF (get or set global CONFiguration options)
1672 Retrieves or sets various system-wide configuration and policy options. This
1673 command is only available to Aides. The sole parameter accepted is a command,
1674 which should be either GET or SET. If the GET command succeeds, CONF will
1675 return LISTING_FOLLOWS followed by the fields described below, one line at a
1676 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1677 the fields described below, one line at a time (don't worry about other fields
1678 being added in the future; if a 'short' configuration list is sent, the missing
1679 values at the end will be left unchanged on the system). If either command
1680 fails for any reason, ERROR is returned.
1682 The configuration lines are as follows:
1685 2. Fully qualified domain name
1686 3. Human-readable node name
1687 4. Landline telephone number of this system
1688 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1689 6. Server connection idle timeout (in seconds)
1690 7. Initial access level for new users
1691 8. Flag (0 or 1) - require registration for new users
1692 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1693 10. Name of twit room
1694 11. Text of <more> prompt
1695 12. Flag (0 or 1) - restrict access to Internet mail
1696 13. Geographic location of this system
1697 14. Name of the system administrator
1698 15. Number of maximum concurrent sessions allowed on the server
1699 16. Password for server-to-server networking
1700 17. Default purge time (in days) for users
1701 18. Default purge time (in days) for rooms
1702 19. Name of room to log express messages to (or a zero-length name for none)
1703 20. Access level required to create rooms
1704 21. Maximum message length which may be entered into the system
1705 22. Minimum number of worker threads
1706 23. Maximum number of worker threads
1707 24. Port number for POP3 service
1708 25. Port number for SMTP service
1710 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1711 28. Port number for IMAP service
1712 29. How often (in seconds) to run the networker
1714 CONF also accepts two additional commands: GETSYS and PUTSYS followed by an
1715 arbitrary MIME type (such as application/x-citadel-internet-config) which
1716 provides a means of storing generic configuration data in the Global System
1717 Configuration room without the need to add extra get/set commands to the
1721 EXPI (EXPIre system objects)
1723 Begins purge operations for objects which, according to site policy, are
1724 "old" and should be removed. EXPI should be called with one argument, one of:
1726 "messages" (purge old messages out of each room)
1727 "users" (purge old users from the userlog)
1728 "rooms" (remove rooms which have not been posted in for some time)
1729 "visits" (purge dereferenced user/room relationship records)
1731 EXPI returns OK (probably after a long delay while it does its work) if it
1732 succeeds; otherwise it returns an ERROR code.
1734 This command is probably temporary, until we can work some sort of scheduler
1735 into the system. It is implemented in the serv_expire module.
1739 MSG4 (read MeSsaGe, mode 4 -- enumerate MIME parts)
1741 FIXME ... do the writeup for this once it's done.
1745 OPNA (OPeN Attachment)
1747 Opens, as a download file, a component of a MIME-encoded message. The two
1748 parameters which must be passed to this command are the message number and the
1749 name of the desired section. If the message or section does not exist, an
1750 appropriate ERROR code will be returned; otherwise, if the open is successful,
1751 this command will succeed returning the same information as an OPEN command.
1754 GEXP (Get EXPress messages)
1756 This is a more sophisticated way of retrieving express messages than the old
1757 PEXP method. If there are no express messages waiting, PEXP returns ERROR;
1758 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1760 0 - a boolean value telling the client whether there are any additional
1761 express messages waiting following this one
1762 1 - a Unix-style timestamp
1763 2 - flags (see server.h for more info)
1764 3 - the name of the sender
1765 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1767 The text sent to the client will be the body of the express message.
1769 So how does the client know there are express messages waiting? It could
1770 execute a random GEXP every now and then. Or, it can check the byte in
1771 server return code messages, between the return code and the parameters. In
1772 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1773 an "*" in this position to signify the presence of waiting express messages.
1776 FSCK (check message base reference counts)
1778 Verify, via the long way, that all message referenmce counts are correct. If
1779 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1780 by a transcript of the run. Otherwise ERROR is returned.
1783 DEXP (Disable EXPress messages)
1785 DEXP sets or clears the "disable express messages" flag. Pass this command a
1786 1 or 0 to respectively set or clear the flag. When the "disable express
1787 messages" flag is set, no one except Aides may send the user express messages.
1788 Any value other than 0 or 1 will not change the flag, only report its state.
1789 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1790 number representing the current state of the flag.
1793 REQT (REQuest client Termination)
1795 Request that the specified client (or all clients) log off. Aide level
1796 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1799 The REQT command accepts one parameter: the session ID of the client which
1800 should be terminated, or 0 for all clients. When successful, the REQT command
1803 It should be noted that REQT simply transmits an express message to the
1804 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1805 this flag, and it is certainly possible for users to re-program their client
1806 software to ignore it. Therefore the effects of the REQT command should be
1807 considered advisory only. The recommended implementation practice is to first
1808 issue a REQT command, then wait a little while (from 30 seconds up to a few
1809 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1810 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1811 you are logging off users for the purpose of shutting down the server).
1814 SEEN (set or clear the SEEN flag for a message)
1816 Beginning with version 5.80, Citadel supports the concept of setting or
1817 clearing the "seen" flag for each individual message, instead of only allowing
1818 a "last seen" pointer. In fact, the old semantics are implemented in terms
1819 of the new semantics. This command requires two arguments: the number of the
1820 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1822 This command returns OK, unless the user is not logged in or a usage error
1823 occurred, in which case it returns ERROR. Please note that no checking is
1824 done on the supplied data; if the requested message does not exist, the SEEN
1825 command simply returns OK without doing anything.
1828 GTSN (GeT the list of SeeN messages)
1830 This command retrieves the list of "seen" (as opposed to unread) messages for
1831 the current room. It returns OK followed by an IMAP-format message list.
1834 SMTP (utility commands for the SMTP gateway)
1836 This command, accessible only by Aides, supports several utility operations
1837 which examine or manipulate Citadel's SMTP support. The first command argument
1838 is a subcommand telling the server what to do. The following subcommands are
1841 SMTP mx|hostname (display all MX hosts for 'hostname')
1842 SMTP runqueue (attempt immediate delivery of all messages
1843 in the outbound SMTP queue, ignoring any
1844 retry times stored there)
1847 STLS (Start Transport Layer Security)
1849 This command starts TLS on the current connection. The current
1850 implementation uses OpenSSL on both the client and server end. For future
1851 compatibility all clients must support at least TLSv1, and servers are
1852 guaranteed to support TLSv1. During TLS negotiation (see below) the server
1853 and client may agree to use a different protocol.
1855 The server returns ERROR if it does not support SSL or SSL initialization
1856 failed on the server; otherwise it returns OK. Once the server returns OK and
1857 the client has read the response, the server and client immediately negotiate
1858 TLS (in OpenSSL, using SSL_connect() on the client and SSL_accept() on the
1859 server). If negotiation fails, the server and client should attempt to resume
1860 the session unencrypted. If either end is unable to resume the session, the
1861 connection should be closed.
1863 This command may be run at any time.
1866 GTLS (Get Transport Layer Security Status)
1868 This command returns information about the current connection. The server
1869 returns OK plus several parameters if the connection is encrypted, and ERROR
1870 if the connection is not encrypted. It is primarily used for debugging. The
1871 command may be run at any time.
1873 0 - Protocol name, e.g. "SSLv3"
1874 1 - Cipher suite name, e.g. "ADH-RC4-MD5"
1875 2 - Cipher strength bits, e.g. 128
1876 3 - Cipher strength bits actually in use, e.g. 128
1879 IGAB (Initialize Global Address Book)
1881 This command creates, or re-creates, a database of Internet e-mail addresses
1882 using the vCard information in the Global Address Book room. This procedure
1883 is normally run internally when the server determines it necessary, but is
1884 also provided as a server command to be used as a troubleshooting/maintenenance
1885 tool. Only a system Aide can run the command. It returns OK on success or
1889 QDIR (Query global DIRectory)
1891 Look up an internet address in the global directory. Any logged-in user may
1892 call QDIR with one parameter, the Internet e-mail address to look up. QDIR
1893 returns OK followed by a Citadel address if there is a match, otherwise it
1894 returns ERROR+NOT_LOGGED_IN.
1897 VIEW (set the VIEW for a room)
1899 Set the preferred view for the current user in the current room. Please see
1900 views.txt for more information on views. The sole parameter for this command
1901 is the type of view requested. VIEW returns OK on success or ERROR on failure.
1904 QNOP (Quiet No OPeration)
1906 This command does nothing, similar to the NOOP command. However, unlike the
1907 NOOP command, it returns *absolutely no response* at all. The client has no
1908 way of knowing that the command executed. It is intended for sending
1909 "keepalives" in situations where a full NOOP would cause the client protocol
1912 Naturally, sending this command to a server that doesn't support it is an
1913 easy way to mess things up. Therefore, client software should first check
1914 the output of an INFO command to ensure that the server supports quiet noops.
1918 MRTG (Multi Router Traffic Grapher)
1920 Multi Router Traffic Grapher (please see http://www.mrtg.org for more info) is
1921 a tool which creates pretty graphs of network activity, usually collected from
1922 routers using SNMP. However, its ability to call external scripts has spawned
1923 a small community of people using it to graph anything which can be graphed.
1924 The MRTG command can output Citadel server activity in the format MRTG expects.
1926 This format is as follows:
1931 Line 3: uptime of system
1932 Line 4: name of system
1935 MRTG accepts two different keywords. "MRTG users" will return two variables,
1936 the number of connected users and the number of active users. "MRTG messages"
1937 will return one variable (and a zero in the second field), showing the current
1938 highest message number on the system. Any other keyword, or a missing keyword,
1939 will cause the MRTG command to return an ERROR code.
1941 Please get in touch with the Citadel developers if you wish to experiment with
1946 ASYN (ASYNchronous message support)
1948 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
1949 only parameter specified should be 1 or 0 to indicate that the client can or
1950 cannot handle this type of messages. The server will reply OK followed by a
1951 1 or 0 to tell the client which mode it is now operating in.
1953 If the command is not available on the server (i.e. it returns ERROR), or
1954 if the command has not been executed by the client, it should be assumed that
1955 this mode of operation is NOT in effect.
1957 The client may also send any value other than 0 or 1 to simply cause the
1958 server to output its current state without changing it.
1960 When asynchronous protocol mode is in effect, the client MUST handle any
1961 asynchronous messages as they arrive, before doing anything else.
1966 ASYNCHRONOUS MESSAGES
1967 ---------------------
1969 When the client protocol is operating in asynchronous mode (please refer to
1970 the writeup of the ASYN command above), the following messages may arrive at
1974 901 (express message arriving)
1976 There is an express message intended for this client. When the client
1977 receives this message, it MUST act as if it just sent a GEXP command (the data
1978 following the 901 message WILL be a LISTING_FOLLOWS data transfer; in fact,
1979 the current implementation simply executes a GEXP command internally).