1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * Copyright (C) 2008 by Spencer Oliver *
9 * spen@spen-soft.co.uk *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
16 * This program is distributed in the hope that it will be useful, *
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
19 * GNU General Public License for more details. *
21 * You should have received a copy of the GNU General Public License *
22 * along with this program; if not, write to the *
23 * Free Software Foundation, Inc., *
24 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
25 ***************************************************************************/
30 #include "telnet_server.h"
31 #include <target/target_request.h>
33 static unsigned short telnet_port
= 4444;
35 static char *negotiate
=
36 "\xFF\xFB\x03" /* IAC WILL Suppress Go Ahead */
37 "\xFF\xFB\x01" /* IAC WILL Echo */
38 "\xFF\xFD\x03" /* IAC DO Suppress Go Ahead */
39 "\xFF\xFE\x01"; /* IAC DON'T Echo */
41 #define CTRL(c) (c - '@')
43 /* The only way we can detect that the socket is closed is the first time
44 * we write to it, we will fail. Subsequent write operations will
47 int telnet_write(struct connection
*connection
, const void *data
, int len
)
49 struct telnet_connection
*t_con
= connection
->priv
;
51 return ERROR_SERVER_REMOTE_CLOSED
;
53 if (write_socket(connection
->fd
, data
, len
) == len
)
58 return ERROR_SERVER_REMOTE_CLOSED
;
61 int telnet_prompt(struct connection
*connection
)
63 struct telnet_connection
*t_con
= connection
->priv
;
65 telnet_write(connection
, "\r", 1); /* the prompt is always placed at the line beginning */
66 return telnet_write(connection
, t_con
->prompt
, strlen(t_con
->prompt
));
69 int telnet_outputline(struct connection
*connection
, const char *line
)
73 /* process lines in buffer */
75 char *line_end
= strchr(line
, '\n');
82 telnet_write(connection
, line
, len
);
85 telnet_write(connection
, "\r\n", 2);
97 int telnet_output(struct command_context
*cmd_ctx
, const char* line
)
99 struct connection
*connection
= cmd_ctx
->output_handler_priv
;
101 return telnet_outputline(connection
, line
);
104 void telnet_log_callback(void *priv
, const char *file
, unsigned line
,
105 const char *function
, const char *string
)
107 struct connection
*connection
= priv
;
108 struct telnet_connection
*t_con
= connection
->priv
;
111 /* if there is no prompt, simply output the message */
112 if (t_con
->line_cursor
< 0)
114 telnet_outputline(connection
, string
);
118 /* clear the command line */
119 telnet_write(connection
, "\r", 1);
120 for (i
= strlen(t_con
->prompt
) + t_con
->line_size
; i
> 0; i
-= 16)
121 telnet_write(connection
, " ", i
> 16 ? 16 : i
);
122 telnet_write(connection
, "\r", 1);
124 /* output the message */
125 telnet_outputline(connection
, string
);
127 /* put the command line to its previous state */
128 telnet_prompt(connection
);
129 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
130 for (i
= t_con
->line_size
; i
> t_con
->line_cursor
; i
--)
131 telnet_write(connection
, "\b", 1);
134 int telnet_new_connection(struct connection
*connection
)
136 struct telnet_connection
*telnet_connection
= malloc(sizeof(struct telnet_connection
));
137 struct telnet_service
*telnet_service
= connection
->service
->priv
;
140 connection
->priv
= telnet_connection
;
142 /* initialize telnet connection information */
143 telnet_connection
->closed
= 0;
144 telnet_connection
->line_size
= 0;
145 telnet_connection
->line_cursor
= 0;
146 telnet_connection
->option_size
= 0;
147 telnet_connection
->prompt
= strdup("> ");
148 telnet_connection
->state
= TELNET_STATE_DATA
;
150 /* output goes through telnet connection */
151 command_set_output_handler(connection
->cmd_ctx
, telnet_output
, connection
);
153 /* negotiate telnet options */
154 telnet_write(connection
, negotiate
, strlen(negotiate
));
156 /* print connection banner */
157 if (telnet_service
->banner
)
159 telnet_write(connection
, telnet_service
->banner
, strlen(telnet_service
->banner
));
160 telnet_write(connection
, "\r\n", 2);
163 telnet_prompt(connection
);
165 /* initialize history */
166 for (i
= 0; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
168 telnet_connection
->history
[i
] = NULL
;
170 telnet_connection
->next_history
= 0;
171 telnet_connection
->current_history
= 0;
173 log_add_callback(telnet_log_callback
, connection
);
178 void telnet_clear_line(struct connection
*connection
, struct telnet_connection
*t_con
)
180 /* move to end of line */
181 if (t_con
->line_cursor
< t_con
->line_size
)
183 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
186 /* backspace, overwrite with space, backspace */
187 while (t_con
->line_size
> 0)
189 telnet_write(connection
, "\b \b", 3);
192 t_con
->line_cursor
= 0;
195 int telnet_input(struct connection
*connection
)
198 char buffer
[TELNET_BUFFER_SIZE
];
200 struct telnet_connection
*t_con
= connection
->priv
;
201 struct command_context
*command_context
= connection
->cmd_ctx
;
203 bytes_read
= read_socket(connection
->fd
, buffer
, TELNET_BUFFER_SIZE
);
206 return ERROR_SERVER_REMOTE_CLOSED
;
207 else if (bytes_read
== -1)
209 LOG_ERROR("error during read: %s", strerror(errno
));
210 return ERROR_SERVER_REMOTE_CLOSED
;
216 switch (t_con
->state
)
218 case TELNET_STATE_DATA
:
219 if (*buf_p
== '\xff')
221 t_con
->state
= TELNET_STATE_IAC
;
225 if (isprint(*buf_p
)) /* printable character */
227 /* watch buffer size leaving one spare character for string null termination */
228 if (t_con
->line_size
== TELNET_LINE_MAX_SIZE
-1)
230 /* output audible bell if buffer is full */
231 telnet_write(connection
, "\x07", 1); /* "\a" does not work, at least on windows */
233 else if (t_con
->line_cursor
== t_con
->line_size
)
235 telnet_write(connection
, buf_p
, 1);
236 t_con
->line
[t_con
->line_size
++] = *buf_p
;
237 t_con
->line_cursor
++;
242 memmove(t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
243 t_con
->line
[t_con
->line_cursor
] = *buf_p
;
245 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
246 t_con
->line_cursor
++;
247 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
249 telnet_write(connection
, "\b", 1);
253 else /* non-printable */
255 if (*buf_p
== 0x1b) /* escape */
257 t_con
->state
= TELNET_STATE_ESCAPE
;
258 t_con
->last_escape
= '\x00';
260 else if ((*buf_p
== 0xd) || (*buf_p
== 0xa)) /* CR/LF */
264 /* skip over combinations with CR/LF and NUL characters */
265 if ((bytes_read
> 1) && ((*(buf_p
+ 1) == 0xa) || (*(buf_p
+ 1) == 0xd)))
270 if ((bytes_read
> 1) && (*(buf_p
+ 1) == 0))
275 t_con
->line
[t_con
->line_size
] = 0;
277 telnet_write(connection
, "\r\n\x00", 3);
279 if (strcmp(t_con
->line
, "history") == 0)
282 for (i
= 1; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
284 /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
285 char *history_line
= t_con
->history
[(t_con
->next_history
+ i
) % TELNET_LINE_HISTORY_SIZE
];
288 telnet_write(connection
, history_line
, strlen(history_line
));
289 telnet_write(connection
, "\r\n\x00", 3);
292 t_con
->line_size
= 0;
293 t_con
->line_cursor
= 0;
297 /* save only non-blank not repeating lines in the history */
298 char *prev_line
= t_con
->history
[(t_con
->current_history
> 0) ? t_con
->current_history
- 1 : TELNET_LINE_HISTORY_SIZE
-1];
299 if (*t_con
->line
&& (prev_line
== NULL
|| strcmp(t_con
->line
, prev_line
)))
301 /* if the history slot is already taken, free it */
302 if (t_con
->history
[t_con
->next_history
])
304 free(t_con
->history
[t_con
->next_history
]);
307 /* add line to history */
308 t_con
->history
[t_con
->next_history
] = strdup(t_con
->line
);
310 /* wrap history at TELNET_LINE_HISTORY_SIZE */
311 t_con
->next_history
= (t_con
->next_history
+ 1) % TELNET_LINE_HISTORY_SIZE
;
313 /* current history line starts at the new entry */
314 t_con
->current_history
= t_con
->next_history
;
316 if (t_con
->history
[t_con
->current_history
])
318 free(t_con
->history
[t_con
->current_history
]);
320 t_con
->history
[t_con
->current_history
] = strdup("");
323 t_con
->line_size
= 0;
325 t_con
->line_cursor
= -1; /* to supress prompt in log callback during command execution */
327 retval
= command_run_line(command_context
, t_con
->line
);
329 t_con
->line_cursor
= 0;
331 if (retval
== ERROR_COMMAND_CLOSE_CONNECTION
)
332 return ERROR_SERVER_REMOTE_CLOSED
;
334 retval
= telnet_prompt(connection
);
335 if (retval
== ERROR_SERVER_REMOTE_CLOSED
)
336 return ERROR_SERVER_REMOTE_CLOSED
;
339 else if ((*buf_p
== 0x7f) || (*buf_p
== 0x8)) /* delete character */
341 if (t_con
->line_cursor
> 0)
343 if (t_con
->line_cursor
!= t_con
->line_size
)
346 telnet_write(connection
, "\b", 1);
347 t_con
->line_cursor
--;
349 memmove(t_con
->line
+ t_con
->line_cursor
, t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line_size
- t_con
->line_cursor
);
351 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
352 telnet_write(connection
, " \b", 2);
353 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
355 telnet_write(connection
, "\b", 1);
361 t_con
->line_cursor
--;
362 /* back space: move the 'printer' head one char back, overwrite with space, move back again */
363 telnet_write(connection
, "\b \b", 3);
367 else if (*buf_p
== 0x15) /* clear line */
369 telnet_clear_line(connection
, t_con
);
371 else if (*buf_p
== CTRL('B')) /* cursor left */
373 if (t_con
->line_cursor
> 0)
375 telnet_write(connection
, "\b", 1);
376 t_con
->line_cursor
--;
378 t_con
->state
= TELNET_STATE_DATA
;
380 else if (*buf_p
== CTRL('F')) /* cursor right */
382 if (t_con
->line_cursor
< t_con
->line_size
)
384 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
++, 1);
386 t_con
->state
= TELNET_STATE_DATA
;
390 LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p
);
395 case TELNET_STATE_IAC
:
399 t_con
->state
= TELNET_STATE_DONT
;
402 t_con
->state
= TELNET_STATE_DO
;
405 t_con
->state
= TELNET_STATE_WONT
;
408 t_con
->state
= TELNET_STATE_WILL
;
412 case TELNET_STATE_SB
:
414 case TELNET_STATE_SE
:
416 case TELNET_STATE_WILL
:
417 case TELNET_STATE_WONT
:
418 case TELNET_STATE_DO
:
419 case TELNET_STATE_DONT
:
420 t_con
->state
= TELNET_STATE_DATA
;
422 case TELNET_STATE_ESCAPE
:
423 if (t_con
->last_escape
== '[')
425 if (*buf_p
== 'D') /* cursor left */
427 if (t_con
->line_cursor
> 0)
429 telnet_write(connection
, "\b", 1);
430 t_con
->line_cursor
--;
432 t_con
->state
= TELNET_STATE_DATA
;
434 else if (*buf_p
== 'C') /* cursor right */
436 if (t_con
->line_cursor
< t_con
->line_size
)
438 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
++, 1);
440 t_con
->state
= TELNET_STATE_DATA
;
442 else if (*buf_p
== 'A') /* cursor up */
444 int last_history
= (t_con
->current_history
> 0) ? t_con
->current_history
- 1 : TELNET_LINE_HISTORY_SIZE
-1;
445 if (t_con
->history
[last_history
])
447 telnet_clear_line(connection
, t_con
);
448 t_con
->line_size
= strlen(t_con
->history
[last_history
]);
449 t_con
->line_cursor
= t_con
->line_size
;
450 memcpy(t_con
->line
, t_con
->history
[last_history
], t_con
->line_size
);
451 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
452 t_con
->current_history
= last_history
;
454 t_con
->state
= TELNET_STATE_DATA
;
456 else if (*buf_p
== 'B') /* cursor down */
458 int next_history
= (t_con
->current_history
+ 1) % TELNET_LINE_HISTORY_SIZE
;
459 if (t_con
->history
[next_history
])
461 telnet_clear_line(connection
, t_con
);
462 t_con
->line_size
= strlen(t_con
->history
[next_history
]);
463 t_con
->line_cursor
= t_con
->line_size
;
464 memcpy(t_con
->line
, t_con
->history
[next_history
], t_con
->line_size
);
465 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
466 t_con
->current_history
= next_history
;
468 t_con
->state
= TELNET_STATE_DATA
;
470 else if (*buf_p
== '3')
472 t_con
->last_escape
= *buf_p
;
476 t_con
->state
= TELNET_STATE_DATA
;
479 else if (t_con
->last_escape
== '3')
481 /* Remove character */
484 if (t_con
->line_cursor
< t_con
->line_size
)
488 /* remove char from line buffer */
489 memmove(t_con
->line
+ t_con
->line_cursor
, t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line_size
- t_con
->line_cursor
);
491 /* print remainder of buffer */
492 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
493 /* overwrite last char with whitespace */
494 telnet_write(connection
, " \b", 2);
496 /* move back to cursor position*/
497 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
499 telnet_write(connection
, "\b", 1);
503 t_con
->state
= TELNET_STATE_DATA
;
507 t_con
->state
= TELNET_STATE_DATA
;
510 else if (t_con
->last_escape
== '\x00')
514 t_con
->last_escape
= *buf_p
;
518 t_con
->state
= TELNET_STATE_DATA
;
523 LOG_ERROR("BUG: unexpected value in t_con->last_escape");
524 t_con
->state
= TELNET_STATE_DATA
;
529 LOG_ERROR("unknown telnet state");
540 int telnet_connection_closed(struct connection
*connection
)
542 struct telnet_connection
*t_con
= connection
->priv
;
545 log_remove_callback(telnet_log_callback
, connection
);
550 t_con
->prompt
= NULL
;
553 for (i
= 0; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
555 if (t_con
->history
[i
])
557 free(t_con
->history
[i
]);
558 t_con
->history
[i
] = NULL
;
562 /* if this connection registered a debug-message receiver delete it */
563 delete_debug_msg_receiver(connection
->cmd_ctx
, NULL
);
565 if (connection
->priv
)
567 free(connection
->priv
);
568 connection
->priv
= NULL
;
572 LOG_ERROR("BUG: connection->priv == NULL");
578 int telnet_set_prompt(struct connection
*connection
, char *prompt
)
580 struct telnet_connection
*t_con
= connection
->priv
;
582 if (t_con
->prompt
!= NULL
)
585 t_con
->prompt
= strdup(prompt
);
590 int telnet_init(char *banner
)
592 struct telnet_service
*telnet_service
= malloc(sizeof(struct telnet_service
));
594 if (telnet_port
== 0)
596 LOG_INFO("telnet port disabled");
597 free(telnet_service
);
601 telnet_service
->banner
= banner
;
603 add_service("telnet", CONNECTION_TCP
, telnet_port
, 1, telnet_new_connection
, telnet_input
, telnet_connection_closed
, telnet_service
);
608 /* daemon configuration command telnet_port */
609 COMMAND_HANDLER(handle_telnet_port_command
)
611 return CALL_COMMAND_HANDLER(server_port_command
, &telnet_port
);
614 COMMAND_HANDLER(handle_exit_command
)
616 return ERROR_COMMAND_CLOSE_CONNECTION
;
619 static const struct command_registration telnet_command_handlers
[] = {
622 .handler
= &handle_exit_command
,
623 .mode
= COMMAND_EXEC
,
624 .help
= "exit telnet session",
627 .name
= "telnet_port",
628 .handler
= &handle_telnet_port_command
,
630 .help
= "port on which to listen "
631 "for incoming telnet connections",
634 COMMAND_REGISTRATION_DONE
637 int telnet_register_commands(struct command_context
*cmd_ctx
)
639 return register_commands(cmd_ctx
, NULL
, telnet_command_handlers
);