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 return telnet_write(connection
, t_con
->prompt
, strlen(t_con
->prompt
));
68 int telnet_outputline(struct connection
*connection
, const char *line
)
72 /* process lines in buffer */
74 char *line_end
= strchr(line
, '\n');
81 telnet_write(connection
, line
, len
);
84 telnet_write(connection
, "\r\n", 2);
96 int telnet_output(struct command_context
*cmd_ctx
, const char* line
)
98 struct connection
*connection
= cmd_ctx
->output_handler_priv
;
100 return telnet_outputline(connection
, line
);
103 void telnet_log_callback(void *priv
, const char *file
, unsigned line
,
104 const char *function
, const char *string
)
106 struct connection
*connection
= priv
;
107 struct telnet_connection
*t_con
= connection
->priv
;
110 /* if there is no prompt, simply output the message */
111 if (t_con
->line_cursor
< 0)
113 telnet_outputline(connection
, string
);
117 /* clear the command line */
118 for (i
= strlen(t_con
->prompt
) + t_con
->line_size
; i
> 0; i
-= 16)
119 telnet_write(connection
, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i
> 16 ? 16 : i
);
120 for (i
= strlen(t_con
->prompt
) + t_con
->line_size
; i
> 0; i
-= 16)
121 telnet_write(connection
, " ", i
> 16 ? 16 : i
);
122 for (i
= strlen(t_con
->prompt
) + t_con
->line_size
; i
> 0; i
-= 16)
123 telnet_write(connection
, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i
> 16 ? 16 : i
);
125 /* output the message */
126 telnet_outputline(connection
, string
);
128 /* put the command line to its previous state */
129 telnet_prompt(connection
);
130 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
131 for (i
= t_con
->line_size
; i
> t_con
->line_cursor
; i
--)
132 telnet_write(connection
, "\b", 1);
135 int telnet_new_connection(struct connection
*connection
)
137 struct telnet_connection
*telnet_connection
= malloc(sizeof(struct telnet_connection
));
138 struct telnet_service
*telnet_service
= connection
->service
->priv
;
141 connection
->priv
= telnet_connection
;
143 /* initialize telnet connection information */
144 telnet_connection
->closed
= 0;
145 telnet_connection
->line_size
= 0;
146 telnet_connection
->line_cursor
= 0;
147 telnet_connection
->option_size
= 0;
148 telnet_connection
->prompt
= strdup("> ");
149 telnet_connection
->state
= TELNET_STATE_DATA
;
151 /* output goes through telnet connection */
152 command_set_output_handler(connection
->cmd_ctx
, telnet_output
, connection
);
154 /* negotiate telnet options */
155 telnet_write(connection
, negotiate
, strlen(negotiate
));
157 /* print connection banner */
158 if (telnet_service
->banner
)
160 telnet_write(connection
, telnet_service
->banner
, strlen(telnet_service
->banner
));
161 telnet_write(connection
, "\r\n", 2);
164 telnet_write(connection
, "\r", 1); /* the prompt is always placed at the line beginning */
165 telnet_prompt(connection
);
167 /* initialize history */
168 for (i
= 0; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
170 telnet_connection
->history
[i
] = NULL
;
172 telnet_connection
->next_history
= 0;
173 telnet_connection
->current_history
= 0;
175 log_add_callback(telnet_log_callback
, connection
);
180 void telnet_clear_line(struct connection
*connection
, struct telnet_connection
*t_con
)
182 /* move to end of line */
183 if (t_con
->line_cursor
< t_con
->line_size
)
185 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
188 /* backspace, overwrite with space, backspace */
189 while (t_con
->line_size
> 0)
191 telnet_write(connection
, "\b \b", 3);
194 t_con
->line_cursor
= 0;
197 int telnet_input(struct connection
*connection
)
200 unsigned char buffer
[TELNET_BUFFER_SIZE
];
201 unsigned char *buf_p
;
202 struct telnet_connection
*t_con
= connection
->priv
;
203 struct command_context
*command_context
= connection
->cmd_ctx
;
205 bytes_read
= read_socket(connection
->fd
, buffer
, TELNET_BUFFER_SIZE
);
208 return ERROR_SERVER_REMOTE_CLOSED
;
209 else if (bytes_read
== -1)
211 LOG_ERROR("error during read: %s", strerror(errno
));
212 return ERROR_SERVER_REMOTE_CLOSED
;
218 switch (t_con
->state
)
220 case TELNET_STATE_DATA
:
223 t_con
->state
= TELNET_STATE_IAC
;
227 if (isprint(*buf_p
)) /* printable character */
229 /* watch buffer size leaving one spare character for string null termination */
230 if (t_con
->line_size
== TELNET_LINE_MAX_SIZE
-1)
232 /* output audible bell if buffer is full */
233 telnet_write(connection
, "\x07", 1); /* "\a" does not work, at least on windows */
235 else if (t_con
->line_cursor
== t_con
->line_size
)
237 telnet_write(connection
, buf_p
, 1);
238 t_con
->line
[t_con
->line_size
++] = *buf_p
;
239 t_con
->line_cursor
++;
244 memmove(t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
245 t_con
->line
[t_con
->line_cursor
] = *buf_p
;
247 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
248 t_con
->line_cursor
++;
249 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
251 telnet_write(connection
, "\b", 1);
255 else /* non-printable */
257 if (*buf_p
== 0x1b) /* escape */
259 t_con
->state
= TELNET_STATE_ESCAPE
;
260 t_con
->last_escape
= '\x00';
262 else if ((*buf_p
== 0xd) || (*buf_p
== 0xa)) /* CR/LF */
266 /* skip over combinations with CR/LF and NUL characters */
267 if ((bytes_read
> 1) && ((*(buf_p
+ 1) == 0xa) || (*(buf_p
+ 1) == 0xd)))
272 if ((bytes_read
> 1) && (*(buf_p
+ 1) == 0))
277 t_con
->line
[t_con
->line_size
] = 0;
279 telnet_write(connection
, "\r\n\x00", 3);
281 if (strcmp(t_con
->line
, "history") == 0)
284 for (i
= 1; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
286 /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
287 char *history_line
= t_con
->history
[(t_con
->next_history
+ i
) % TELNET_LINE_HISTORY_SIZE
];
290 telnet_write(connection
, history_line
, strlen(history_line
));
291 telnet_write(connection
, "\r\n\x00", 3);
294 t_con
->line_size
= 0;
295 t_con
->line_cursor
= 0;
299 /* save only non-blank not repeating lines in the history */
300 char *prev_line
= t_con
->history
[(t_con
->current_history
> 0) ? t_con
->current_history
- 1 : TELNET_LINE_HISTORY_SIZE
-1];
301 if (*t_con
->line
&& (prev_line
== NULL
|| strcmp(t_con
->line
, prev_line
)))
303 /* if the history slot is already taken, free it */
304 if (t_con
->history
[t_con
->next_history
])
306 free(t_con
->history
[t_con
->next_history
]);
309 /* add line to history */
310 t_con
->history
[t_con
->next_history
] = strdup(t_con
->line
);
312 /* wrap history at TELNET_LINE_HISTORY_SIZE */
313 t_con
->next_history
= (t_con
->next_history
+ 1) % TELNET_LINE_HISTORY_SIZE
;
315 /* current history line starts at the new entry */
316 t_con
->current_history
= t_con
->next_history
;
318 if (t_con
->history
[t_con
->current_history
])
320 free(t_con
->history
[t_con
->current_history
]);
322 t_con
->history
[t_con
->current_history
] = strdup("");
325 t_con
->line_size
= 0;
327 t_con
->line_cursor
= -1; /* to supress prompt in log callback during command execution */
329 retval
= command_run_line(command_context
, t_con
->line
);
331 t_con
->line_cursor
= 0;
333 if (retval
== ERROR_COMMAND_CLOSE_CONNECTION
)
334 return ERROR_SERVER_REMOTE_CLOSED
;
336 telnet_write(connection
, "\r", 1); /* the prompt is always placed at the line beginning */
337 retval
= telnet_prompt(connection
);
338 if (retval
== ERROR_SERVER_REMOTE_CLOSED
)
339 return ERROR_SERVER_REMOTE_CLOSED
;
342 else if ((*buf_p
== 0x7f) || (*buf_p
== 0x8)) /* delete character */
344 if (t_con
->line_cursor
> 0)
346 if (t_con
->line_cursor
!= t_con
->line_size
)
349 telnet_write(connection
, "\b", 1);
350 t_con
->line_cursor
--;
352 memmove(t_con
->line
+ t_con
->line_cursor
, t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line_size
- t_con
->line_cursor
);
354 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
355 telnet_write(connection
, " \b", 2);
356 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
358 telnet_write(connection
, "\b", 1);
364 t_con
->line_cursor
--;
365 /* back space: move the 'printer' head one char back, overwrite with space, move back again */
366 telnet_write(connection
, "\b \b", 3);
370 else if (*buf_p
== 0x15) /* clear line */
372 telnet_clear_line(connection
, t_con
);
374 else if (*buf_p
== CTRL('B')) /* cursor left */
376 if (t_con
->line_cursor
> 0)
378 telnet_write(connection
, "\b", 1);
379 t_con
->line_cursor
--;
381 t_con
->state
= TELNET_STATE_DATA
;
383 else if (*buf_p
== CTRL('F')) /* cursor right */
385 if (t_con
->line_cursor
< t_con
->line_size
)
387 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
++, 1);
389 t_con
->state
= TELNET_STATE_DATA
;
393 LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p
);
398 case TELNET_STATE_IAC
:
402 t_con
->state
= TELNET_STATE_DONT
;
405 t_con
->state
= TELNET_STATE_DO
;
408 t_con
->state
= TELNET_STATE_WONT
;
411 t_con
->state
= TELNET_STATE_WILL
;
415 case TELNET_STATE_SB
:
417 case TELNET_STATE_SE
:
419 case TELNET_STATE_WILL
:
420 case TELNET_STATE_WONT
:
421 case TELNET_STATE_DO
:
422 case TELNET_STATE_DONT
:
423 t_con
->state
= TELNET_STATE_DATA
;
425 case TELNET_STATE_ESCAPE
:
426 if (t_con
->last_escape
== '[')
428 if (*buf_p
== 'D') /* cursor left */
430 if (t_con
->line_cursor
> 0)
432 telnet_write(connection
, "\b", 1);
433 t_con
->line_cursor
--;
435 t_con
->state
= TELNET_STATE_DATA
;
437 else if (*buf_p
== 'C') /* cursor right */
439 if (t_con
->line_cursor
< t_con
->line_size
)
441 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
++, 1);
443 t_con
->state
= TELNET_STATE_DATA
;
445 else if (*buf_p
== 'A') /* cursor up */
447 int last_history
= (t_con
->current_history
> 0) ? t_con
->current_history
- 1 : TELNET_LINE_HISTORY_SIZE
-1;
448 if (t_con
->history
[last_history
])
450 telnet_clear_line(connection
, t_con
);
451 t_con
->line_size
= strlen(t_con
->history
[last_history
]);
452 t_con
->line_cursor
= t_con
->line_size
;
453 memcpy(t_con
->line
, t_con
->history
[last_history
], t_con
->line_size
);
454 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
455 t_con
->current_history
= last_history
;
457 t_con
->state
= TELNET_STATE_DATA
;
459 else if (*buf_p
== 'B') /* cursor down */
461 int next_history
= (t_con
->current_history
+ 1) % TELNET_LINE_HISTORY_SIZE
;
462 if (t_con
->history
[next_history
])
464 telnet_clear_line(connection
, t_con
);
465 t_con
->line_size
= strlen(t_con
->history
[next_history
]);
466 t_con
->line_cursor
= t_con
->line_size
;
467 memcpy(t_con
->line
, t_con
->history
[next_history
], t_con
->line_size
);
468 telnet_write(connection
, t_con
->line
, t_con
->line_size
);
469 t_con
->current_history
= next_history
;
471 t_con
->state
= TELNET_STATE_DATA
;
473 else if (*buf_p
== '3')
475 t_con
->last_escape
= *buf_p
;
479 t_con
->state
= TELNET_STATE_DATA
;
482 else if (t_con
->last_escape
== '3')
484 /* Remove character */
487 if (t_con
->line_cursor
< t_con
->line_size
)
491 /* remove char from line buffer */
492 memmove(t_con
->line
+ t_con
->line_cursor
, t_con
->line
+ t_con
->line_cursor
+ 1, t_con
->line_size
- t_con
->line_cursor
);
494 /* print remainder of buffer */
495 telnet_write(connection
, t_con
->line
+ t_con
->line_cursor
, t_con
->line_size
- t_con
->line_cursor
);
496 /* overwrite last char with whitespace */
497 telnet_write(connection
, " \b", 2);
499 /* move back to cursor position*/
500 for (i
= t_con
->line_cursor
; i
< t_con
->line_size
; i
++)
502 telnet_write(connection
, "\b", 1);
506 t_con
->state
= TELNET_STATE_DATA
;
510 t_con
->state
= TELNET_STATE_DATA
;
513 else if (t_con
->last_escape
== '\x00')
517 t_con
->last_escape
= *buf_p
;
521 t_con
->state
= TELNET_STATE_DATA
;
526 LOG_ERROR("BUG: unexpected value in t_con->last_escape");
527 t_con
->state
= TELNET_STATE_DATA
;
532 LOG_ERROR("unknown telnet state");
543 int telnet_connection_closed(struct connection
*connection
)
545 struct telnet_connection
*t_con
= connection
->priv
;
548 log_remove_callback(telnet_log_callback
, connection
);
553 t_con
->prompt
= NULL
;
556 for (i
= 0; i
< TELNET_LINE_HISTORY_SIZE
; i
++)
558 if (t_con
->history
[i
])
560 free(t_con
->history
[i
]);
561 t_con
->history
[i
] = NULL
;
565 /* if this connection registered a debug-message receiver delete it */
566 delete_debug_msg_receiver(connection
->cmd_ctx
, NULL
);
568 if (connection
->priv
)
570 free(connection
->priv
);
571 connection
->priv
= NULL
;
575 LOG_ERROR("BUG: connection->priv == NULL");
581 int telnet_set_prompt(struct connection
*connection
, char *prompt
)
583 struct telnet_connection
*t_con
= connection
->priv
;
585 if (t_con
->prompt
!= NULL
)
588 t_con
->prompt
= strdup(prompt
);
593 int telnet_init(char *banner
)
595 struct telnet_service
*telnet_service
= malloc(sizeof(struct telnet_service
));
597 if (telnet_port
== 0)
599 LOG_INFO("telnet port disabled");
600 free(telnet_service
);
604 telnet_service
->banner
= banner
;
606 add_service("telnet", CONNECTION_TCP
, telnet_port
, 1, telnet_new_connection
, telnet_input
, telnet_connection_closed
, telnet_service
);
611 /* daemon configuration command telnet_port */
612 COMMAND_HANDLER(handle_telnet_port_command
)
614 return CALL_COMMAND_HANDLER(server_port_command
, &telnet_port
);
617 COMMAND_HANDLER(handle_exit_command
)
619 return ERROR_COMMAND_CLOSE_CONNECTION
;
622 static const struct command_registration telnet_command_handlers
[] = {
625 .handler
= handle_exit_command
,
626 .mode
= COMMAND_EXEC
,
627 .help
= "exit telnet session",
630 .name
= "telnet_port",
631 .handler
= handle_telnet_port_command
,
633 .help
= "Specify port on which to listen "
634 "for incoming telnet connections. "
635 "No arguments reports telnet port; zero disables.",
636 .usage
= "[port_num]",
638 COMMAND_REGISTRATION_DONE
641 int telnet_register_commands(struct command_context
*cmd_ctx
)
643 return register_commands(cmd_ctx
, NULL
, telnet_command_handlers
);