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   1 /***************************************************************************
   2  *   Copyright (C) 2005 by Dominic Rath                                    *
   3  *   Dominic.Rath@gmx.de                                                   *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include "replacements.h"
  25
  26 #include "telnet_server.h"
  27
  28 #include "server.h"
  29 #include "log.h"
  30 #include "command.h"
  31 #include "target.h"
  32 #include "target_request.h"
  33
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36 #include <errno.h>
  37 #include <string.h>
  38 #include <ctype.h>
  39
  40 static unsigned short telnet_port = 0;
  41
  42 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  43 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  44
  45 static char *negotiate =
  46                 "\xFF\xFB\x03"          /* IAC WILL Suppress Go Ahead */
  47                 "\xFF\xFB\x01"          /* IAC WILL Echo */
  48                 "\xFF\xFD\x03"          /* IAC DO Suppress Go Ahead */
  49                 "\xFF\xFE\x01";         /* IAC DON'T Echo */
  50
  51 #define CTRL(c) (c - '@')
  52
  53 /* The only way we can detect that the socket is closed is the first time
  54  * we write to it, we will fail. Subsequent write operations will
  55  * succeed. Shudder!
  56  */
  57 int telnet_write(connection_t *connection, const void *data, int len)
  58 {
  59         telnet_connection_t *t_con = connection->priv;
  60         if (t_con->closed)
  61                 return ERROR_SERVER_REMOTE_CLOSED;
  62
  63         if (write_socket(connection->fd, data, len) == len)
  64         {
  65                 return ERROR_OK;
  66         }
  67         t_con->closed = 1;
  68         return ERROR_SERVER_REMOTE_CLOSED;
  69 }
  70
  71 int telnet_prompt(connection_t *connection)
  72 {
  73         telnet_connection_t *t_con = connection->priv;
  74
  75         telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
  76         return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
  77 }
  78
  79 int telnet_outputline(connection_t *connection, const char *line)
  80 {
  81         int len;
  82
  83         /* process lines in buffer */
  84         while (*line) {
  85                 char *line_end = strchr(line, '\n');
  86
  87                 if (line_end)
  88                         len = line_end-line;
  89                 else
  90                         len = strlen(line);
  91
  92                 telnet_write(connection, line, len);
  93                 if (line_end)
  94                 {
  95                         telnet_write(connection, "\r\n", 2);
  96                         line += len+1;
  97                 }
  98                 else
  99                 {
 100                         line += len;
 101                 }
 102         }
 103
 104         return ERROR_OK;
 105 }
 106
 107 int telnet_output(struct command_context_s *cmd_ctx, const char* line)
 108 {
 109         connection_t *connection = cmd_ctx->output_handler_priv;
 110
 111         return telnet_outputline(connection, line);
 112 }
 113
 114 void telnet_log_callback(void *priv, const char *file, int line,
 115                 const char *function, const char *string)
 116 {
 117         connection_t *connection = priv;
 118         telnet_connection_t *t_con = connection->priv;
 119         int i;
 120
 121         /* if there is no prompt, simply output the message */
 122         if (t_con->line_cursor < 0)
 123         {
 124                 telnet_outputline(connection, string);
 125                 return;
 126         }
 127
 128         /* clear the command line */
 129         telnet_write(connection, "\r", 1);
 130         for (i = strlen(t_con->prompt) + t_con->line_size; i>0; i-=16)
 131                 telnet_write(connection, "                ", i>16 ? 16 : i);
 132         telnet_write(connection, "\r", 1);
 133
 134         /* output the message */
 135         telnet_outputline(connection, string);
 136
 137         /* put the command line to its previous state */
 138         telnet_prompt(connection);
 139         telnet_write(connection, t_con->line, t_con->line_size);
 140         for (i=t_con->line_size; i>t_con->line_cursor; i--)
 141                 telnet_write(connection, "\b", 1);
 142 }
 143
 144 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
 145 {
 146         switch (event)
 147         {
 148                 case TARGET_EVENT_HALTED:
 149                         target_arch_state(target);
 150                         break;
 151                 default:
 152                         break;
 153         }
 154
 155         return ERROR_OK;
 156 }
 157
 158 int telnet_new_connection(connection_t *connection)
 159 {
 160         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 161         telnet_service_t *telnet_service = connection->service->priv;
 162         int i;
 163
 164         connection->priv = telnet_connection;
 165
 166         /* initialize telnet connection information */
 167         telnet_connection->closed = 0;
 168         telnet_connection->line_size = 0;
 169         telnet_connection->line_cursor = 0;
 170         telnet_connection->option_size = 0;
 171         telnet_connection->prompt = strdup("> ");
 172         telnet_connection->state = TELNET_STATE_DATA;
 173
 174         /* output goes through telnet connection */
 175         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 176
 177         /* negotiate telnet options */
 178         telnet_write(connection, negotiate, strlen(negotiate));
 179
 180         /* print connection banner */
 181         if (telnet_service->banner)
 182         {
 183                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 184                 telnet_write(connection, "\r\n", 2);
 185         }
 186
 187         telnet_prompt(connection);
 188
 189         /* initialize history */
 190         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 191         {
 192                 telnet_connection->history[i] = NULL;
 193         }
 194         telnet_connection->next_history = 0;
 195         telnet_connection->current_history = 0;
 196
 197         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 198
 199         log_add_callback(telnet_log_callback, connection);
 200
 201
 202
 203         return ERROR_OK;
 204 }
 205
 206 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 207 {
 208         /* move to end of line */
 209         if (t_con->line_cursor < t_con->line_size)
 210         {
 211                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 212         }
 213
 214         /* backspace, overwrite with space, backspace */
 215         while (t_con->line_size > 0)
 216         {
 217                 telnet_write(connection, "\b \b", 3);
 218                 t_con->line_size--;
 219         }
 220         t_con->line_cursor = 0;
 221 }
 222
 223 int telnet_input(connection_t *connection)
 224 {
 225         int bytes_read;
 226         char buffer[TELNET_BUFFER_SIZE];
 227         char *buf_p;
 228         telnet_connection_t *t_con = connection->priv;
 229         command_context_t *command_context = connection->cmd_ctx;
 230
 231         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 232
 233         if (bytes_read == 0)
 234                 return ERROR_SERVER_REMOTE_CLOSED;
 235         else if (bytes_read == -1)
 236         {
 237                 LOG_ERROR("error during read: %s", strerror(errno));
 238                 return ERROR_SERVER_REMOTE_CLOSED;
 239         }
 240
 241         buf_p = buffer;
 242         while (bytes_read)
 243         {
 244                 switch (t_con->state)
 245                 {
 246                         case TELNET_STATE_DATA:
 247                                 if (*buf_p == '\xff')
 248                                 {
 249                                         t_con->state = TELNET_STATE_IAC;
 250                                 }
 251                                 else
 252                                 {
 253                                         if (isprint(*buf_p)) /* printable character */
 254                                         {
 255                                                 /* watch buffer size leaving one spare character for string null termination */
 256                                                 if (t_con->line_size == TELNET_LINE_MAX_SIZE-1)
 257                                                 {
 258                                                         /* output audible bell if buffer is full */
 259                                                         telnet_write(connection, "\x07", 1); /* "\a" does not work, at least on windows */
 260                                                 }
 261                                                 else if (t_con->line_cursor == t_con->line_size)
 262                                                 {
 263                                                         telnet_write(connection, buf_p, 1);
 264                                                         t_con->line[t_con->line_size++] = *buf_p;
 265                                                         t_con->line_cursor++;
 266                                                 }
 267                                                 else
 268                                                 {
 269                                                         int i;
 270                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 271                                                         t_con->line[t_con->line_cursor] = *buf_p;
 272                                                         t_con->line_size++;
 273                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 274                                                         t_con->line_cursor++;
 275                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 276                                                         {
 277                                                                 telnet_write(connection, "\b", 1);
 278                                                         }
 279                                                 }
 280                                         }
 281                                         else /* non-printable */
 282                                         {
 283                                                 if (*buf_p == 0x1b) /* escape */
 284                                                 {
 285                                                         t_con->state = TELNET_STATE_ESCAPE;
 286                                                         t_con->last_escape = '\x00';
 287                                                 }
 288                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 289                                                 {
 290                                                         int retval;
 291
 292                                                         /* skip over combinations with CR/LF and NUL characters */
 293                                                         if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)))
 294                                                         {
 295                                                                 buf_p++;
 296                                                                 bytes_read--;
 297                                                         }
 298                                                         if ((bytes_read > 1) && (*(buf_p + 1) == 0))
 299                                                         {
 300                                                                 buf_p++;
 301                                                                 bytes_read--;
 302                                                         }
 303                                                         t_con->line[t_con->line_size] = 0;
 304
 305                                                         telnet_write(connection, "\r\n\x00", 3);
 306
 307                                                         if (strcmp(t_con->line, "history") == 0)
 308                                                         {
 309                                                                 int i;
 310                                                                 for (i = 1; i < TELNET_LINE_HISTORY_SIZE; i++)
 311                                                                 {
 312                                                                         /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
 313                                                                         char *history_line = t_con->history[(t_con->next_history + i) % TELNET_LINE_HISTORY_SIZE];
 314                                                                         if (history_line)
 315                                                                         {
 316                                                                                 telnet_write(connection, history_line, strlen(history_line));
 317                                                                                 telnet_write(connection, "\r\n\x00", 3);
 318                                                                         }
 319                                                                 }
 320                                                                 t_con->line_size = 0;
 321                                                                 t_con->line_cursor = 0;
 322                                                                 continue;
 323                                                         }
 324
 325                                                         /* save only non-blank not repeating lines in the history */
 326                                                         char *prev_line = t_con->history[(t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
 327                                                         if (*t_con->line && (prev_line == NULL || strcmp(t_con->line, prev_line)))
 328                                                         {
 329                                                                 /* if the history slot is already taken, free it */
 330                                                                 if (t_con->history[t_con->next_history])
 331                                                                 {
 332                                                                         free(t_con->history[t_con->next_history]);
 333                                                                 }
 334
 335                                                                 /* add line to history */
 336                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 337
 338                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 339                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 340
 341                                                                 /* current history line starts at the new entry */
 342                                                                 t_con->current_history = t_con->next_history;
 343
 344                                                                 if (t_con->history[t_con->current_history])
 345                                                                 {
 346                                                                         free(t_con->history[t_con->current_history]);
 347                                                                 }
 348                                                                 t_con->history[t_con->current_history] = strdup("");
 349                                                         }
 350
 351                                                         t_con->line_size = 0;
 352
 353                                                         t_con->line_cursor = -1; /* to supress prompt in log callback during command execution */
 354                                                         retval = command_run_line(command_context, t_con->line);
 355                                                         t_con->line_cursor = 0;
 356
 357                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 358                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 359
 360                                                         retval = telnet_prompt(connection);
 361                                                         if (retval == ERROR_SERVER_REMOTE_CLOSED)
 362                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 363
 364                                                 }
 365                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 366                                                 {
 367                                                         if (t_con->line_cursor > 0)
 368                                                         {
 369                                                                 if (t_con->line_cursor != t_con->line_size)
 370                                                                 {
 371                                                                         int i;
 372                                                                         telnet_write(connection, "\b", 1);
 373                                                                         t_con->line_cursor--;
 374                                                                         t_con->line_size--;
 375                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 376
 377                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 378                                                                         telnet_write(connection, " \b", 2);
 379                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 380                                                                         {
 381                                                                                 telnet_write(connection, "\b", 1);
 382                                                                         }
 383                                                                 }
 384                                                                 else
 385                                                                 {
 386                                                                         t_con->line_size--;
 387                                                                         t_con->line_cursor--;
 388                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 389                                                                         telnet_write(connection, "\b \b", 3);
 390                                                                 }
 391                                                         }
 392                                                 }
 393                                                 else if (*buf_p == 0x15) /* clear line */
 394                                                 {
 395                                                         telnet_clear_line(connection, t_con);
 396                                                 }
 397                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 398                                                 {
 399                                                         if (t_con->line_cursor > 0)
 400                                                         {
 401                                                                 telnet_write(connection, "\b", 1);
 402                                                                 t_con->line_cursor--;
 403                                                         }
 404                                                         t_con->state = TELNET_STATE_DATA;
 405                                                 }
 406                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 407                                                 {
 408                                                         if (t_con->line_cursor < t_con->line_size)
 409                                                         {
 410                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 411                                                         }
 412                                                         t_con->state = TELNET_STATE_DATA;
 413                                                 }
 414                                                 else
 415                                                 {
 416                                                         LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 417                                                 }
 418                                         }
 419                                 }
 420                                 break;
 421                         case TELNET_STATE_IAC:
 422                                 switch (*buf_p)
 423                                 {
 424                                         case '\xfe':
 425                                                 t_con->state = TELNET_STATE_DONT;
 426                                                 break;
 427                                         case '\xfd':
 428                                                 t_con->state = TELNET_STATE_DO;
 429                                                 break;
 430                                         case '\xfc':
 431                                                 t_con->state = TELNET_STATE_WONT;
 432                                                 break;
 433                                         case '\xfb':
 434                                                 t_con->state = TELNET_STATE_WILL;
 435                                                 break;
 436                                 }
 437                                 break;
 438                         case TELNET_STATE_SB:
 439                                 break;
 440                         case TELNET_STATE_SE:
 441                                 break;
 442                         case TELNET_STATE_WILL:
 443                         case TELNET_STATE_WONT:
 444                         case TELNET_STATE_DO:
 445                         case TELNET_STATE_DONT:
 446                                 t_con->state = TELNET_STATE_DATA;
 447                                 break;
 448                         case TELNET_STATE_ESCAPE:
 449                                 if (t_con->last_escape == '[')
 450                                 {
 451                                         if (*buf_p == 'D') /* cursor left */
 452                                         {
 453                                                 if (t_con->line_cursor > 0)
 454                                                 {
 455                                                         telnet_write(connection, "\b", 1);
 456                                                         t_con->line_cursor--;
 457                                                 }
 458                                                 t_con->state = TELNET_STATE_DATA;
 459                                         }
 460                                         else if (*buf_p == 'C') /* cursor right */
 461                                         {
 462                                                 if (t_con->line_cursor < t_con->line_size)
 463                                                 {
 464                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 465                                                 }
 466                                                 t_con->state = TELNET_STATE_DATA;
 467                                         }
 468                                         else if (*buf_p == 'A') /* cursor up */
 469                                         {
 470                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 471                                                 if (t_con->history[last_history])
 472                                                 {
 473                                                         telnet_clear_line(connection, t_con);
 474                                                         t_con->line_size = strlen(t_con->history[last_history]);
 475                                                         t_con->line_cursor = t_con->line_size;
 476                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size);
 477                                                         telnet_write(connection, t_con->line, t_con->line_size);
 478                                                         t_con->current_history = last_history;
 479                                                 }
 480                                                 t_con->state = TELNET_STATE_DATA;
 481                                         }
 482                                         else if (*buf_p == 'B') /* cursor down */
 483                                         {
 484                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 485                                                 if (t_con->history[next_history])
 486                                                 {
 487                                                         telnet_clear_line(connection, t_con);
 488                                                         t_con->line_size = strlen(t_con->history[next_history]);
 489                                                         t_con->line_cursor = t_con->line_size;
 490                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size);
 491                                                         telnet_write(connection, t_con->line, t_con->line_size);
 492                                                         t_con->current_history = next_history;
 493                                                 }
 494                                                 t_con->state = TELNET_STATE_DATA;
 495                                         }
 496                                         else if (*buf_p == '3')
 497                                         {
 498                                                 t_con->last_escape = *buf_p;
 499                                         }
 500                                         else
 501                                         {
 502                                                 t_con->state = TELNET_STATE_DATA;
 503                                         }
 504                                 }
 505                                 else if (t_con->last_escape == '3')
 506                                 {
 507                                         /* Remove character */
 508                                         if (*buf_p == '~')
 509                                         {
 510                                                 if (t_con->line_cursor < t_con->line_size)
 511                                                 {
 512                                                         int i;
 513                                                         t_con->line_size--;
 514                                                         /* remove char from line buffer */
 515                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 516
 517                                                         /* print remainder of buffer */
 518                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 519                                                         /* overwrite last char with whitespace */
 520                                                         telnet_write(connection, " \b", 2);
 521
 522                                                         /* move back to cursor position*/
 523                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 524                                                         {
 525                                                                 telnet_write(connection, "\b", 1);
 526                                                         }
 527                                                 }
 528
 529                                                 t_con->state = TELNET_STATE_DATA;
 530                                         }
 531                                         else
 532                                         {
 533                                                 t_con->state = TELNET_STATE_DATA;
 534                                         }
 535                                 }
 536                                 else if (t_con->last_escape == '\x00')
 537                                 {
 538                                         if (*buf_p == '[')
 539                                         {
 540                                                 t_con->last_escape = *buf_p;
 541                                         }
 542                                         else
 543                                         {
 544                                                 t_con->state = TELNET_STATE_DATA;
 545                                         }
 546                                 }
 547                                 else
 548                                 {
 549                                         LOG_ERROR("BUG: unexpected value in t_con->last_escape");
 550                                         t_con->state = TELNET_STATE_DATA;
 551                                 }
 552
 553                                 break;
 554                         default:
 555                                 LOG_ERROR("unknown telnet state");
 556                                 exit(-1);
 557                 }
 558
 559                 bytes_read--;
 560                 buf_p++;
 561         }
 562
 563         return ERROR_OK;
 564 }
 565
 566 int telnet_connection_closed(connection_t *connection)
 567 {
 568         telnet_connection_t *t_con = connection->priv;
 569         int i;
 570
 571         log_remove_callback(telnet_log_callback, connection);
 572
 573         if (t_con->prompt)
 574         {
 575                 free(t_con->prompt);
 576                 t_con->prompt = NULL;
 577         }
 578
 579         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 580         {
 581                 if (t_con->history[i])
 582                 {
 583                         free(t_con->history[i]);
 584                         t_con->history[i] = NULL;
 585                 }
 586         }
 587
 588         /* if this connection registered a debug-message receiver delete it */
 589         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 590
 591         if (connection->priv)
 592         {
 593                 free(connection->priv);
 594                 connection->priv = NULL;
 595         }
 596         else
 597         {
 598                 LOG_ERROR("BUG: connection->priv == NULL");
 599         }
 600
 601         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 602
 603         return ERROR_OK;
 604 }
 605
 606 int telnet_set_prompt(connection_t *connection, char *prompt)
 607 {
 608         telnet_connection_t *t_con = connection->priv;
 609
 610         if (t_con->prompt != NULL)
 611                 free(t_con->prompt);
 612
 613         t_con->prompt = strdup(prompt);
 614
 615         return ERROR_OK;
 616 }
 617
 618 int telnet_init(char *banner)
 619 {
 620         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 621
 622         if (telnet_port == 0)
 623         {
 624                 LOG_WARNING("no telnet port specified, using default port 4444");
 625                 telnet_port = 4444;
 626         }
 627
 628         telnet_service->banner = banner;
 629
 630         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 631
 632         return ERROR_OK;
 633 }
 634
 635 int telnet_register_commands(command_context_t *command_context)
 636 {
 637         register_command(command_context, NULL, "exit", handle_exit_command,
 638                                          COMMAND_EXEC, "exit telnet session");
 639
 640         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 641                                          COMMAND_CONFIG, "");
 642
 643         return ERROR_OK;
 644 }
 645
 646 /* daemon configuration command telnet_port */
 647 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 648 {
 649         if (argc == 0)
 650                 return ERROR_OK;
 651
 652         telnet_port = strtoul(args[0], NULL, 0);
 653
 654         return ERROR_OK;
 655 }
 656
 657 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 658 {
 659         return ERROR_COMMAND_CLOSE_CONNECTION;
 660 }