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 "replacements.h"
32 #include "telnet_server.h"
38 #include "target_request.h"
46 static unsigned short telnet_port = 0;
48 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
49 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
51 static char *negotiate =
52 "\xFF\xFB\x03" /* IAC WILL Suppress Go Ahead */
53 "\xFF\xFB\x01" /* IAC WILL Echo */
54 "\xFF\xFD\x03" /* IAC DO Suppress Go Ahead */
55 "\xFF\xFE\x01"; /* IAC DON'T Echo */
57 #define CTRL(c) (c - '@')
59 /* The only way we can detect that the socket is closed is the first time
60 * we write to it, we will fail. Subsequent write operations will
63 int telnet_write(connection_t *connection, const void *data, int len)
65 telnet_connection_t *t_con = connection->priv;
67 return ERROR_SERVER_REMOTE_CLOSED;
69 if (write_socket(connection->fd, data, len) == len)
74 return ERROR_SERVER_REMOTE_CLOSED;
77 int telnet_prompt(connection_t *connection)
79 telnet_connection_t *t_con = connection->priv;
81 telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
82 return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
85 int telnet_outputline(connection_t *connection, const char *line)
89 /* process lines in buffer */
91 char *line_end = strchr(line, '\n');
98 telnet_write(connection, line, len);
101 telnet_write(connection, "\r\n", 2);
113 int telnet_output(struct command_context_s *cmd_ctx, const char* line)
115 connection_t *connection = cmd_ctx->output_handler_priv;
117 return telnet_outputline(connection, line);
120 void telnet_log_callback(void *priv, const char *file, int line,
121 const char *function, const char *string)
123 connection_t *connection = priv;
124 telnet_connection_t *t_con = connection->priv;
127 /* if there is no prompt, simply output the message */
128 if (t_con->line_cursor < 0)
130 telnet_outputline(connection, string);
134 /* clear the command line */
135 telnet_write(connection, "\r", 1);
136 for (i = strlen(t_con->prompt) + t_con->line_size; i>0; i-=16)
137 telnet_write(connection, " ", i>16 ? 16 : i);
138 telnet_write(connection, "\r", 1);
140 /* output the message */
141 telnet_outputline(connection, string);
143 /* put the command line to its previous state */
144 telnet_prompt(connection);
145 telnet_write(connection, t_con->line, t_con->line_size);
146 for (i=t_con->line_size; i>t_con->line_cursor; i--)
147 telnet_write(connection, "\b", 1);
150 int telnet_new_connection(connection_t *connection)
152 telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
153 telnet_service_t *telnet_service = connection->service->priv;
156 connection->priv = telnet_connection;
158 /* initialize telnet connection information */
159 telnet_connection->closed = 0;
160 telnet_connection->line_size = 0;
161 telnet_connection->line_cursor = 0;
162 telnet_connection->option_size = 0;
163 telnet_connection->prompt = strdup("> ");
164 telnet_connection->state = TELNET_STATE_DATA;
166 /* output goes through telnet connection */
167 command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
169 /* negotiate telnet options */
170 telnet_write(connection, negotiate, strlen(negotiate));
172 /* print connection banner */
173 if (telnet_service->banner)
175 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
176 telnet_write(connection, "\r\n", 2);
179 telnet_prompt(connection);
181 /* initialize history */
182 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
184 telnet_connection->history[i] = NULL;
186 telnet_connection->next_history = 0;
187 telnet_connection->current_history = 0;
189 log_add_callback(telnet_log_callback, connection);
196 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
198 /* move to end of line */
199 if (t_con->line_cursor < t_con->line_size)
201 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
204 /* backspace, overwrite with space, backspace */
205 while (t_con->line_size > 0)
207 telnet_write(connection, "\b \b", 3);
210 t_con->line_cursor = 0;
213 int telnet_input(connection_t *connection)
216 char buffer[TELNET_BUFFER_SIZE];
218 telnet_connection_t *t_con = connection->priv;
219 command_context_t *command_context = connection->cmd_ctx;
221 bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
224 return ERROR_SERVER_REMOTE_CLOSED;
225 else if (bytes_read == -1)
227 LOG_ERROR("error during read: %s", strerror(errno));
228 return ERROR_SERVER_REMOTE_CLOSED;
234 switch (t_con->state)
236 case TELNET_STATE_DATA:
237 if (*buf_p == '\xff')
239 t_con->state = TELNET_STATE_IAC;
243 if (isprint(*buf_p)) /* printable character */
245 /* watch buffer size leaving one spare character for string null termination */
246 if (t_con->line_size == TELNET_LINE_MAX_SIZE-1)
248 /* output audible bell if buffer is full */
249 telnet_write(connection, "\x07", 1); /* "\a" does not work, at least on windows */
251 else if (t_con->line_cursor == t_con->line_size)
253 telnet_write(connection, buf_p, 1);
254 t_con->line[t_con->line_size++] = *buf_p;
255 t_con->line_cursor++;
260 memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
261 t_con->line[t_con->line_cursor] = *buf_p;
263 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
264 t_con->line_cursor++;
265 for (i = t_con->line_cursor; i < t_con->line_size; i++)
267 telnet_write(connection, "\b", 1);
271 else /* non-printable */
273 if (*buf_p == 0x1b) /* escape */
275 t_con->state = TELNET_STATE_ESCAPE;
276 t_con->last_escape = '\x00';
278 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
282 /* skip over combinations with CR/LF and NUL characters */
283 if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)))
288 if ((bytes_read > 1) && (*(buf_p + 1) == 0))
293 t_con->line[t_con->line_size] = 0;
295 telnet_write(connection, "\r\n\x00", 3);
297 if (strcmp(t_con->line, "history") == 0)
300 for (i = 1; i < TELNET_LINE_HISTORY_SIZE; i++)
302 /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
303 char *history_line = t_con->history[(t_con->next_history + i) % TELNET_LINE_HISTORY_SIZE];
306 telnet_write(connection, history_line, strlen(history_line));
307 telnet_write(connection, "\r\n\x00", 3);
310 t_con->line_size = 0;
311 t_con->line_cursor = 0;
315 /* save only non-blank not repeating lines in the history */
316 char *prev_line = t_con->history[(t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
317 if (*t_con->line && (prev_line == NULL || strcmp(t_con->line, prev_line)))
319 /* if the history slot is already taken, free it */
320 if (t_con->history[t_con->next_history])
322 free(t_con->history[t_con->next_history]);
325 /* add line to history */
326 t_con->history[t_con->next_history] = strdup(t_con->line);
328 /* wrap history at TELNET_LINE_HISTORY_SIZE */
329 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
331 /* current history line starts at the new entry */
332 t_con->current_history = t_con->next_history;
334 if (t_con->history[t_con->current_history])
336 free(t_con->history[t_con->current_history]);
338 t_con->history[t_con->current_history] = strdup("");
341 t_con->line_size = 0;
343 t_con->line_cursor = -1; /* to supress prompt in log callback during command execution */
344 retval = command_run_line(command_context, t_con->line);
345 t_con->line_cursor = 0;
347 if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
348 return ERROR_SERVER_REMOTE_CLOSED;
350 retval = telnet_prompt(connection);
351 if (retval == ERROR_SERVER_REMOTE_CLOSED)
352 return ERROR_SERVER_REMOTE_CLOSED;
355 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
357 if (t_con->line_cursor > 0)
359 if (t_con->line_cursor != t_con->line_size)
362 telnet_write(connection, "\b", 1);
363 t_con->line_cursor--;
365 memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
367 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
368 telnet_write(connection, " \b", 2);
369 for (i = t_con->line_cursor; i < t_con->line_size; i++)
371 telnet_write(connection, "\b", 1);
377 t_con->line_cursor--;
378 /* back space: move the 'printer' head one char back, overwrite with space, move back again */
379 telnet_write(connection, "\b \b", 3);
383 else if (*buf_p == 0x15) /* clear line */
385 telnet_clear_line(connection, t_con);
387 else if (*buf_p == CTRL('B')) /* cursor left */
389 if (t_con->line_cursor > 0)
391 telnet_write(connection, "\b", 1);
392 t_con->line_cursor--;
394 t_con->state = TELNET_STATE_DATA;
396 else if (*buf_p == CTRL('F')) /* cursor right */
398 if (t_con->line_cursor < t_con->line_size)
400 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
402 t_con->state = TELNET_STATE_DATA;
406 LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
411 case TELNET_STATE_IAC:
415 t_con->state = TELNET_STATE_DONT;
418 t_con->state = TELNET_STATE_DO;
421 t_con->state = TELNET_STATE_WONT;
424 t_con->state = TELNET_STATE_WILL;
428 case TELNET_STATE_SB:
430 case TELNET_STATE_SE:
432 case TELNET_STATE_WILL:
433 case TELNET_STATE_WONT:
434 case TELNET_STATE_DO:
435 case TELNET_STATE_DONT:
436 t_con->state = TELNET_STATE_DATA;
438 case TELNET_STATE_ESCAPE:
439 if (t_con->last_escape == '[')
441 if (*buf_p == 'D') /* cursor left */
443 if (t_con->line_cursor > 0)
445 telnet_write(connection, "\b", 1);
446 t_con->line_cursor--;
448 t_con->state = TELNET_STATE_DATA;
450 else if (*buf_p == 'C') /* cursor right */
452 if (t_con->line_cursor < t_con->line_size)
454 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
456 t_con->state = TELNET_STATE_DATA;
458 else if (*buf_p == 'A') /* cursor up */
460 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
461 if (t_con->history[last_history])
463 telnet_clear_line(connection, t_con);
464 t_con->line_size = strlen(t_con->history[last_history]);
465 t_con->line_cursor = t_con->line_size;
466 memcpy(t_con->line, t_con->history[last_history], t_con->line_size);
467 telnet_write(connection, t_con->line, t_con->line_size);
468 t_con->current_history = last_history;
470 t_con->state = TELNET_STATE_DATA;
472 else if (*buf_p == 'B') /* cursor down */
474 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
475 if (t_con->history[next_history])
477 telnet_clear_line(connection, t_con);
478 t_con->line_size = strlen(t_con->history[next_history]);
479 t_con->line_cursor = t_con->line_size;
480 memcpy(t_con->line, t_con->history[next_history], t_con->line_size);
481 telnet_write(connection, t_con->line, t_con->line_size);
482 t_con->current_history = next_history;
484 t_con->state = TELNET_STATE_DATA;
486 else if (*buf_p == '3')
488 t_con->last_escape = *buf_p;
492 t_con->state = TELNET_STATE_DATA;
495 else if (t_con->last_escape == '3')
497 /* Remove character */
500 if (t_con->line_cursor < t_con->line_size)
504 /* remove char from line buffer */
505 memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
507 /* print remainder of buffer */
508 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
509 /* overwrite last char with whitespace */
510 telnet_write(connection, " \b", 2);
512 /* move back to cursor position*/
513 for (i = t_con->line_cursor; i < t_con->line_size; i++)
515 telnet_write(connection, "\b", 1);
519 t_con->state = TELNET_STATE_DATA;
523 t_con->state = TELNET_STATE_DATA;
526 else if (t_con->last_escape == '\x00')
530 t_con->last_escape = *buf_p;
534 t_con->state = TELNET_STATE_DATA;
539 LOG_ERROR("BUG: unexpected value in t_con->last_escape");
540 t_con->state = TELNET_STATE_DATA;
545 LOG_ERROR("unknown telnet state");
556 int telnet_connection_closed(connection_t *connection)
558 telnet_connection_t *t_con = connection->priv;
561 log_remove_callback(telnet_log_callback, connection);
566 t_con->prompt = NULL;
569 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
571 if (t_con->history[i])
573 free(t_con->history[i]);
574 t_con->history[i] = NULL;
578 /* if this connection registered a debug-message receiver delete it */
579 delete_debug_msg_receiver(connection->cmd_ctx, NULL);
581 if (connection->priv)
583 free(connection->priv);
584 connection->priv = NULL;
588 LOG_ERROR("BUG: connection->priv == NULL");
594 int telnet_set_prompt(connection_t *connection, char *prompt)
596 telnet_connection_t *t_con = connection->priv;
598 if (t_con->prompt != NULL)
601 t_con->prompt = strdup(prompt);
606 int telnet_init(char *banner)
608 telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
610 if (telnet_port == 0)
612 LOG_WARNING("no telnet port specified, using default port 4444");
616 telnet_service->banner = banner;
618 add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
623 int telnet_register_commands(command_context_t *command_context)
625 register_command(command_context, NULL, "exit", handle_exit_command,
626 COMMAND_EXEC, "exit telnet session");
628 register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
634 /* daemon configuration command telnet_port */
635 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
640 telnet_port = strtoul(args[0], NULL, 0);
645 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
647 return ERROR_COMMAND_CLOSE_CONNECTION;