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   1 /***************************************************************************
   2  *   Copyright (C) 2005 by Dominic Rath                                    *
   3  *   Dominic.Rath@gmx.de                                                   *
   4  *                                                                         *
   5  *   Copyright (C) 2007-2010 Øyvind Harboe                                 *
   6  *   oyvind.harboe@zylin.com                                               *
   7  *                                                                         *
   8  *   Copyright (C) 2008 by Spencer Oliver                                  *
   9  *   spen@spen-soft.co.uk                                                  *
  10  *                                                                         *
  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.                                   *
  15  *                                                                         *
  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.                          *
  20  *                                                                         *
  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  ***************************************************************************/
  26 #ifdef HAVE_CONFIG_H
  27 #include "config.h"
  28 #endif
  29
  30 #include "telnet_server.h"
  31 #include <target/target_request.h>
  32
  33 static unsigned short telnet_port = 4444;
  34
  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 */
  40
  41 #define CTRL(c) (c - '@')
  42
  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
  45  * succeed. Shudder!
  46  */
  47 static int telnet_write(struct connection *connection, const void *data,
  48                 int len)
  49 {
  50         struct telnet_connection *t_con = connection->priv;
  51         if (t_con->closed)
  52                 return ERROR_SERVER_REMOTE_CLOSED;
  53
  54         if (write_socket(connection->fd_out, data, len) == len)
  55         {
  56                 return ERROR_OK;
  57         }
  58         t_con->closed = 1;
  59         return ERROR_SERVER_REMOTE_CLOSED;
  60 }
  61
  62 static int telnet_prompt(struct connection *connection)
  63 {
  64         struct telnet_connection *t_con = connection->priv;
  65
  66         return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
  67 }
  68
  69 static int telnet_outputline(struct connection *connection, const char *line)
  70 {
  71         int len;
  72
  73         /* process lines in buffer */
  74         while (*line) {
  75                 char *line_end = strchr(line, '\n');
  76
  77                 if (line_end)
  78                         len = line_end-line;
  79                 else
  80                         len = strlen(line);
  81
  82                 telnet_write(connection, line, len);
  83                 if (line_end)
  84                 {
  85                         telnet_write(connection, "\r\n", 2);
  86                         line += len + 1;
  87                 }
  88                 else
  89                 {
  90                         line += len;
  91                 }
  92         }
  93
  94         return ERROR_OK;
  95 }
  96
  97 static int telnet_output(struct command_context *cmd_ctx, const char* line)
  98 {
  99         struct connection *connection = cmd_ctx->output_handler_priv;
 100
 101         return telnet_outputline(connection, line);
 102 }
 103
 104 static void telnet_log_callback(void *priv, const char *file, unsigned line,
 105                 const char *function, const char *string)
 106 {
 107         struct connection *connection = priv;
 108         struct telnet_connection *t_con = connection->priv;
 109         int i;
 110
 111         /* if there is no prompt, simply output the message */
 112         if (t_con->line_cursor < 0)
 113         {
 114                 telnet_outputline(connection, string);
 115                 return;
 116         }
 117
 118         /* clear the command line */
 119         for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
 120                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i > 16 ? 16 : i);
 121         for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
 122                 telnet_write(connection, "                ", i > 16 ? 16 : i);
 123         for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
 124                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i > 16 ? 16 : i);
 125
 126         /* output the message */
 127         telnet_outputline(connection, string);
 128
 129         /* put the command line to its previous state */
 130         telnet_prompt(connection);
 131         telnet_write(connection, t_con->line, t_con->line_size);
 132         for (i = t_con->line_size; i > t_con->line_cursor; i--)
 133                 telnet_write(connection, "\b", 1);
 134 }
 135
 136 static int telnet_new_connection(struct connection *connection)
 137 {
 138         struct telnet_connection *telnet_connection = malloc(sizeof(struct telnet_connection));
 139         struct telnet_service *telnet_service = connection->service->priv;
 140         int i;
 141
 142         connection->priv = telnet_connection;
 143
 144         /* initialize telnet connection information */
 145         telnet_connection->closed = 0;
 146         telnet_connection->line_size = 0;
 147         telnet_connection->line_cursor = 0;
 148         telnet_connection->option_size = 0;
 149         telnet_connection->prompt = strdup("> ");
 150         telnet_connection->state = TELNET_STATE_DATA;
 151
 152         /* output goes through telnet connection */
 153         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 154
 155         /* negotiate telnet options */
 156         telnet_write(connection, negotiate, strlen(negotiate));
 157
 158         /* print connection banner */
 159         if (telnet_service->banner)
 160         {
 161                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 162                 telnet_write(connection, "\r\n", 2);
 163         }
 164
 165         telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
 166         telnet_prompt(connection);
 167
 168         /* initialize history */
 169         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 170         {
 171                 telnet_connection->history[i] = NULL;
 172         }
 173         telnet_connection->next_history = 0;
 174         telnet_connection->current_history = 0;
 175
 176         log_add_callback(telnet_log_callback, connection);
 177
 178         return ERROR_OK;
 179 }
 180
 181 static void telnet_clear_line(struct connection *connection,
 182                 struct telnet_connection *t_con)
 183 {
 184         /* move to end of line */
 185         if (t_con->line_cursor < t_con->line_size)
 186         {
 187                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 188         }
 189
 190         /* backspace, overwrite with space, backspace */
 191         while (t_con->line_size > 0)
 192         {
 193                 telnet_write(connection, "\b \b", 3);
 194                 t_con->line_size--;
 195         }
 196         t_con->line_cursor = 0;
 197 }
 198
 199 static int telnet_input(struct connection *connection)
 200 {
 201         int bytes_read;
 202         unsigned char buffer[TELNET_BUFFER_SIZE];
 203         unsigned char *buf_p;
 204         struct telnet_connection *t_con = connection->priv;
 205         struct command_context *command_context = connection->cmd_ctx;
 206
 207         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 208
 209         if (bytes_read == 0)
 210                 return ERROR_SERVER_REMOTE_CLOSED;
 211         else if (bytes_read == -1)
 212         {
 213                 LOG_ERROR("error during read: %s", strerror(errno));
 214                 return ERROR_SERVER_REMOTE_CLOSED;
 215         }
 216
 217         buf_p = buffer;
 218         while (bytes_read)
 219         {
 220                 switch (t_con->state)
 221                 {
 222                         case TELNET_STATE_DATA:
 223                                 if (*buf_p == 0xff)
 224                                 {
 225                                         t_con->state = TELNET_STATE_IAC;
 226                                 }
 227                                 else
 228                                 {
 229                                         if (isprint(*buf_p)) /* printable character */
 230                                         {
 231                                                 /* watch buffer size leaving one spare character for string null termination */
 232                                                 if (t_con->line_size == TELNET_LINE_MAX_SIZE-1)
 233                                                 {
 234                                                         /* output audible bell if buffer is full */
 235                                                         telnet_write(connection, "\x07", 1); /* "\a" does not work, at least on windows */
 236                                                 }
 237                                                 else if (t_con->line_cursor == t_con->line_size)
 238                                                 {
 239                                                         telnet_write(connection, buf_p, 1);
 240                                                         t_con->line[t_con->line_size++] = *buf_p;
 241                                                         t_con->line_cursor++;
 242                                                 }
 243                                                 else
 244                                                 {
 245                                                         int i;
 246                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 247                                                         t_con->line[t_con->line_cursor] = *buf_p;
 248                                                         t_con->line_size++;
 249                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 250                                                         t_con->line_cursor++;
 251                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 252                                                         {
 253                                                                 telnet_write(connection, "\b", 1);
 254                                                         }
 255                                                 }
 256                                         }
 257                                         else /* non-printable */
 258                                         {
 259                                                 if (*buf_p == 0x1b) /* escape */
 260                                                 {
 261                                                         t_con->state = TELNET_STATE_ESCAPE;
 262                                                         t_con->last_escape = '\x00';
 263                                                 }
 264                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 265                                                 {
 266                                                         int retval;
 267
 268                                                         /* skip over combinations with CR/LF and NUL characters */
 269                                                         if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)))
 270                                                         {
 271                                                                 buf_p++;
 272                                                                 bytes_read--;
 273                                                         }
 274                                                         if ((bytes_read > 1) && (*(buf_p + 1) == 0))
 275                                                         {
 276                                                                 buf_p++;
 277                                                                 bytes_read--;
 278                                                         }
 279                                                         t_con->line[t_con->line_size] = 0;
 280
 281                                                         telnet_write(connection, "\r\n\x00", 3);
 282
 283                                                         if (strcmp(t_con->line, "history") == 0)
 284                                                         {
 285                                                                 int i;
 286                                                                 for (i = 1; i < TELNET_LINE_HISTORY_SIZE; i++)
 287                                                                 {
 288                                                                         /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
 289                                                                         char *history_line = t_con->history[(t_con->next_history + i) % TELNET_LINE_HISTORY_SIZE];
 290                                                                         if (history_line)
 291                                                                         {
 292                                                                                 telnet_write(connection, history_line, strlen(history_line));
 293                                                                                 telnet_write(connection, "\r\n\x00", 3);
 294                                                                         }
 295                                                                 }
 296                                                                 t_con->line_size = 0;
 297                                                                 t_con->line_cursor = 0;
 298                                                                 continue;
 299                                                         }
 300
 301                                                         /* save only non-blank not repeating lines in the history */
 302                                                         char *prev_line = t_con->history[(t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
 303                                                         if (*t_con->line && (prev_line == NULL || strcmp(t_con->line, prev_line)))
 304                                                         {
 305                                                                 /* if the history slot is already taken, free it */
 306                                                                 if (t_con->history[t_con->next_history])
 307                                                                 {
 308                                                                         free(t_con->history[t_con->next_history]);
 309                                                                 }
 310
 311                                                                 /* add line to history */
 312                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 313
 314                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 315                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 316
 317                                                                 /* current history line starts at the new entry */
 318                                                                 t_con->current_history = t_con->next_history;
 319
 320                                                                 if (t_con->history[t_con->current_history])
 321                                                                 {
 322                                                                         free(t_con->history[t_con->current_history]);
 323                                                                 }
 324                                                                 t_con->history[t_con->current_history] = strdup("");
 325                                                         }
 326
 327                                                         t_con->line_size = 0;
 328
 329                                                         t_con->line_cursor = -1; /* to supress prompt in log callback during command execution */
 330
 331                                                         retval = command_run_line(command_context, t_con->line);
 332
 333                                                         t_con->line_cursor = 0;
 334
 335                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 336                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 337
 338                                                         telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
 339                                                         retval = telnet_prompt(connection);
 340                                                         if (retval == ERROR_SERVER_REMOTE_CLOSED)
 341                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 342
 343                                                 }
 344                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 345                                                 {
 346                                                         if (t_con->line_cursor > 0)
 347                                                         {
 348                                                                 if (t_con->line_cursor != t_con->line_size)
 349                                                                 {
 350                                                                         int i;
 351                                                                         telnet_write(connection, "\b", 1);
 352                                                                         t_con->line_cursor--;
 353                                                                         t_con->line_size--;
 354                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 355
 356                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 357                                                                         telnet_write(connection, " \b", 2);
 358                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 359                                                                         {
 360                                                                                 telnet_write(connection, "\b", 1);
 361                                                                         }
 362                                                                 }
 363                                                                 else
 364                                                                 {
 365                                                                         t_con->line_size--;
 366                                                                         t_con->line_cursor--;
 367                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 368                                                                         telnet_write(connection, "\b \b", 3);
 369                                                                 }
 370                                                         }
 371                                                 }
 372                                                 else if (*buf_p == 0x15) /* clear line */
 373                                                 {
 374                                                         telnet_clear_line(connection, t_con);
 375                                                 }
 376                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 377                                                 {
 378                                                         if (t_con->line_cursor > 0)
 379                                                         {
 380                                                                 telnet_write(connection, "\b", 1);
 381                                                                 t_con->line_cursor--;
 382                                                         }
 383                                                         t_con->state = TELNET_STATE_DATA;
 384                                                 }
 385                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 386                                                 {
 387                                                         if (t_con->line_cursor < t_con->line_size)
 388                                                         {
 389                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 390                                                         }
 391                                                         t_con->state = TELNET_STATE_DATA;
 392                                                 }
 393                                                 else
 394                                                 {
 395                                                         LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 396                                                 }
 397                                         }
 398                                 }
 399                                 break;
 400                         case TELNET_STATE_IAC:
 401                                 switch (*buf_p)
 402                                 {
 403                                         case 0xfe:
 404                                                 t_con->state = TELNET_STATE_DONT;
 405                                                 break;
 406                                         case 0xfd:
 407                                                 t_con->state = TELNET_STATE_DO;
 408                                                 break;
 409                                         case 0xfc:
 410                                                 t_con->state = TELNET_STATE_WONT;
 411                                                 break;
 412                                         case 0xfb:
 413                                                 t_con->state = TELNET_STATE_WILL;
 414                                                 break;
 415                                 }
 416                                 break;
 417                         case TELNET_STATE_SB:
 418                                 break;
 419                         case TELNET_STATE_SE:
 420                                 break;
 421                         case TELNET_STATE_WILL:
 422                         case TELNET_STATE_WONT:
 423                         case TELNET_STATE_DO:
 424                         case TELNET_STATE_DONT:
 425                                 t_con->state = TELNET_STATE_DATA;
 426                                 break;
 427                         case TELNET_STATE_ESCAPE:
 428                                 if (t_con->last_escape == '[')
 429                                 {
 430                                         if (*buf_p == 'D') /* cursor left */
 431                                         {
 432                                                 if (t_con->line_cursor > 0)
 433                                                 {
 434                                                         telnet_write(connection, "\b", 1);
 435                                                         t_con->line_cursor--;
 436                                                 }
 437                                                 t_con->state = TELNET_STATE_DATA;
 438                                         }
 439                                         else if (*buf_p == 'C') /* cursor right */
 440                                         {
 441                                                 if (t_con->line_cursor < t_con->line_size)
 442                                                 {
 443                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 444                                                 }
 445                                                 t_con->state = TELNET_STATE_DATA;
 446                                         }
 447                                         else if (*buf_p == 'A') /* cursor up */
 448                                         {
 449                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 450                                                 if (t_con->history[last_history])
 451                                                 {
 452                                                         telnet_clear_line(connection, t_con);
 453                                                         t_con->line_size = strlen(t_con->history[last_history]);
 454                                                         t_con->line_cursor = t_con->line_size;
 455                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size);
 456                                                         telnet_write(connection, t_con->line, t_con->line_size);
 457                                                         t_con->current_history = last_history;
 458                                                 }
 459                                                 t_con->state = TELNET_STATE_DATA;
 460                                         }
 461                                         else if (*buf_p == 'B') /* cursor down */
 462                                         {
 463                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 464                                                 if (t_con->history[next_history])
 465                                                 {
 466                                                         telnet_clear_line(connection, t_con);
 467                                                         t_con->line_size = strlen(t_con->history[next_history]);
 468                                                         t_con->line_cursor = t_con->line_size;
 469                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size);
 470                                                         telnet_write(connection, t_con->line, t_con->line_size);
 471                                                         t_con->current_history = next_history;
 472                                                 }
 473                                                 t_con->state = TELNET_STATE_DATA;
 474                                         }
 475                                         else if (*buf_p == '3')
 476                                         {
 477                                                 t_con->last_escape = *buf_p;
 478                                         }
 479                                         else
 480                                         {
 481                                                 t_con->state = TELNET_STATE_DATA;
 482                                         }
 483                                 }
 484                                 else if (t_con->last_escape == '3')
 485                                 {
 486                                         /* Remove character */
 487                                         if (*buf_p == '~')
 488                                         {
 489                                                 if (t_con->line_cursor < t_con->line_size)
 490                                                 {
 491                                                         int i;
 492                                                         t_con->line_size--;
 493                                                         /* remove char from line buffer */
 494                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 495
 496                                                         /* print remainder of buffer */
 497                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 498                                                         /* overwrite last char with whitespace */
 499                                                         telnet_write(connection, " \b", 2);
 500
 501                                                         /* move back to cursor position*/
 502                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 503                                                         {
 504                                                                 telnet_write(connection, "\b", 1);
 505                                                         }
 506                                                 }
 507
 508                                                 t_con->state = TELNET_STATE_DATA;
 509                                         }
 510                                         else
 511                                         {
 512                                                 t_con->state = TELNET_STATE_DATA;
 513                                         }
 514                                 }
 515                                 else if (t_con->last_escape == '\x00')
 516                                 {
 517                                         if (*buf_p == '[')
 518                                         {
 519                                                 t_con->last_escape = *buf_p;
 520                                         }
 521                                         else
 522                                         {
 523                                                 t_con->state = TELNET_STATE_DATA;
 524                                         }
 525                                 }
 526                                 else
 527                                 {
 528                                         LOG_ERROR("BUG: unexpected value in t_con->last_escape");
 529                                         t_con->state = TELNET_STATE_DATA;
 530                                 }
 531
 532                                 break;
 533                         default:
 534                                 LOG_ERROR("unknown telnet state");
 535                                 exit(-1);
 536                 }
 537
 538                 bytes_read--;
 539                 buf_p++;
 540         }
 541
 542         return ERROR_OK;
 543 }
 544
 545 static int telnet_connection_closed(struct connection *connection)
 546 {
 547         struct telnet_connection *t_con = connection->priv;
 548         int i;
 549
 550         log_remove_callback(telnet_log_callback, connection);
 551
 552         if (t_con->prompt)
 553         {
 554                 free(t_con->prompt);
 555                 t_con->prompt = NULL;
 556         }
 557
 558         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 559         {
 560                 if (t_con->history[i])
 561                 {
 562                         free(t_con->history[i]);
 563                         t_con->history[i] = NULL;
 564                 }
 565         }
 566
 567         /* if this connection registered a debug-message receiver delete it */
 568         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 569
 570         if (connection->priv)
 571         {
 572                 free(connection->priv);
 573                 connection->priv = NULL;
 574         }
 575         else
 576         {
 577                 LOG_ERROR("BUG: connection->priv == NULL");
 578         }
 579
 580         return ERROR_OK;
 581 }
 582
 583 int telnet_init(char *banner)
 584 {
 585         struct telnet_service *telnet_service = malloc(sizeof(struct telnet_service));
 586
 587         if (telnet_port == 0)
 588         {
 589                 LOG_INFO("telnet port disabled");
 590                 free(telnet_service);
 591                 return ERROR_OK;
 592         }
 593
 594         telnet_service->banner = banner;
 595
 596         add_service("telnet", CONNECTION_TCP, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 597
 598         return ERROR_OK;
 599 }
 600
 601 /* daemon configuration command telnet_port */
 602 COMMAND_HANDLER(handle_telnet_port_command)
 603 {
 604         return CALL_COMMAND_HANDLER(server_port_command, &telnet_port);
 605 }
 606
 607 COMMAND_HANDLER(handle_exit_command)
 608 {
 609         return ERROR_COMMAND_CLOSE_CONNECTION;
 610 }
 611
 612 static const struct command_registration telnet_command_handlers[] = {
 613         {
 614                 .name = "exit",
 615                 .handler = handle_exit_command,
 616                 .mode = COMMAND_EXEC,
 617                 .help = "exit telnet session",
 618         },
 619         {
 620                 .name = "telnet_port",
 621                 .handler = handle_telnet_port_command,
 622                 .mode = COMMAND_ANY,
 623                 .help = "Specify port on which to listen "
 624                         "for incoming telnet connections.  "
 625                         "No arguments reports telnet port; zero disables.",
 626                 .usage = "[port_num]",
 627         },
 628         COMMAND_REGISTRATION_DONE
 629 };
 630
 631 int telnet_register_commands(struct command_context *cmd_ctx)
 632 {
 633         return register_commands(cmd_ctx, NULL, telnet_command_handlers);
 634 }