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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, see <http://www.gnu.org/licenses/>. *
  23  ***************************************************************************/
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 #include "telnet_server.h"
  30 #include <target/target_request.h>
  31 #include <helper/configuration.h>
  32
  33 static char *telnet_port;
  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 #define TELNET_HISTORY  ".openocd_history"
  43
  44 /* The only way we can detect that the socket is closed is the first time
  45  * we write to it, we will fail. Subsequent write operations will
  46  * succeed. Shudder!
  47  */
  48 static int telnet_write(struct connection *connection, const void *data,
  49         int len)
  50 {
  51         struct telnet_connection *t_con = connection->priv;
  52         if (t_con->closed)
  53                 return ERROR_SERVER_REMOTE_CLOSED;
  54
  55         if (connection_write(connection, data, len) == len)
  56                 return ERROR_OK;
  57         t_con->closed = true;
  58         return ERROR_SERVER_REMOTE_CLOSED;
  59 }
  60
  61 static int telnet_prompt(struct connection *connection)
  62 {
  63         struct telnet_connection *t_con = connection->priv;
  64
  65         return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
  66 }
  67
  68 static int telnet_outputline(struct connection *connection, const char *line)
  69 {
  70         int len;
  71
  72         /* process lines in buffer */
  73         while (*line) {
  74                 char *line_end = strchr(line, '\n');
  75
  76                 if (line_end)
  77                         len = line_end-line;
  78                 else
  79                         len = strlen(line);
  80
  81                 telnet_write(connection, line, len);
  82                 if (line_end) {
  83                         telnet_write(connection, "\r\n", 2);
  84                         line += len + 1;
  85                 } else
  86                         line += len;
  87         }
  88
  89         return ERROR_OK;
  90 }
  91
  92 static int telnet_output(struct command_context *cmd_ctx, const char *line)
  93 {
  94         struct connection *connection = cmd_ctx->output_handler_priv;
  95
  96         return telnet_outputline(connection, line);
  97 }
  98
  99 static void telnet_log_callback(void *priv, const char *file, unsigned line,
 100         const char *function, const char *string)
 101 {
 102         struct connection *connection = priv;
 103         struct telnet_connection *t_con = connection->priv;
 104         size_t i;
 105         size_t tmp;
 106
 107         /* If the prompt is not visible, simply output the message. */
 108         if (!t_con->prompt_visible) {
 109                 telnet_outputline(connection, string);
 110                 return;
 111         }
 112
 113         /* Clear the command line. */
 114         tmp = strlen(t_con->prompt) + t_con->line_size;
 115
 116         for (i = 0; i < tmp; i += 16)
 117                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 118                         MIN(tmp - i, 16));
 119
 120         for (i = 0; i < tmp; i += 16)
 121                 telnet_write(connection, "                ", MIN(tmp - i, 16));
 122
 123         for (i = 0; i < tmp; i += 16)
 124                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 125                         MIN(tmp - i, 16));
 126
 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
 133         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 134                 telnet_write(connection, "\b", 1);
 135 }
 136
 137 static void telnet_load_history(struct telnet_connection *t_con)
 138 {
 139         FILE *histfp;
 140         char buffer[TELNET_BUFFER_SIZE];
 141         int i = 0;
 142
 143         char *history = get_home_dir(TELNET_HISTORY);
 144
 145         if (history == NULL) {
 146                 LOG_INFO("unable to get user home directory, telnet history will be disabled");
 147                 return;
 148         }
 149
 150         histfp = fopen(history, "rb");
 151
 152         if (histfp) {
 153
 154                 while (fgets(buffer, sizeof(buffer), histfp) != NULL) {
 155
 156                         char *p = strchr(buffer, '\n');
 157                         if (p)
 158                                 *p = '\0';
 159                         if (buffer[0] && i < TELNET_LINE_HISTORY_SIZE)
 160                                 t_con->history[i++] = strdup(buffer);
 161                 }
 162
 163                 t_con->next_history = i;
 164                 t_con->next_history %= TELNET_LINE_HISTORY_SIZE;
 165                 /* try to set to last entry - 1, that way we skip over any exit/shutdown cmds */
 166                 t_con->current_history = t_con->next_history > 0 ? i - 1 : 0;
 167                 fclose(histfp);
 168         }
 169
 170         free(history);
 171 }
 172
 173 static void telnet_save_history(struct telnet_connection *t_con)
 174 {
 175         FILE *histfp;
 176         int i;
 177         int num;
 178
 179         char *history = get_home_dir(TELNET_HISTORY);
 180
 181         if (history == NULL) {
 182                 LOG_INFO("unable to get user home directory, telnet history will be disabled");
 183                 return;
 184         }
 185
 186         histfp = fopen(history, "wb");
 187
 188         if (histfp) {
 189
 190                 num = TELNET_LINE_HISTORY_SIZE;
 191                 i = t_con->current_history + 1;
 192                 i %= TELNET_LINE_HISTORY_SIZE;
 193
 194                 while (t_con->history[i] == NULL && num > 0) {
 195                         i++;
 196                         i %= TELNET_LINE_HISTORY_SIZE;
 197                         num--;
 198                 }
 199
 200                 if (num > 0) {
 201                         for (; num > 0; num--) {
 202                                 fprintf(histfp, "%s\n", t_con->history[i]);
 203                                 i++;
 204                                 i %= TELNET_LINE_HISTORY_SIZE;
 205                         }
 206                 }
 207                 fclose(histfp);
 208         }
 209
 210         free(history);
 211 }
 212
 213 static int telnet_new_connection(struct connection *connection)
 214 {
 215         struct telnet_connection *telnet_connection;
 216         struct telnet_service *telnet_service = connection->service->priv;
 217         int i;
 218
 219         telnet_connection = malloc(sizeof(struct telnet_connection));
 220
 221         if (!telnet_connection) {
 222                 LOG_ERROR("Failed to allocate telnet connection.");
 223                 return ERROR_FAIL;
 224         }
 225
 226         connection->priv = telnet_connection;
 227
 228         /* initialize telnet connection information */
 229         telnet_connection->closed = false;
 230         telnet_connection->line_size = 0;
 231         telnet_connection->line_cursor = 0;
 232         telnet_connection->prompt = strdup("> ");
 233         telnet_connection->prompt_visible = true;
 234         telnet_connection->state = TELNET_STATE_DATA;
 235
 236         /* output goes through telnet connection */
 237         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 238
 239         /* negotiate telnet options */
 240         telnet_write(connection, negotiate, strlen(negotiate));
 241
 242         /* print connection banner */
 243         if (telnet_service->banner) {
 244                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 245                 telnet_write(connection, "\r\n", 2);
 246         }
 247
 248         /* the prompt is always placed at the line beginning */
 249         telnet_write(connection, "\r", 1);
 250         telnet_prompt(connection);
 251
 252         /* initialize history */
 253         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 254                 telnet_connection->history[i] = NULL;
 255         telnet_connection->next_history = 0;
 256         telnet_connection->current_history = 0;
 257         telnet_load_history(telnet_connection);
 258
 259         log_add_callback(telnet_log_callback, connection);
 260
 261         return ERROR_OK;
 262 }
 263
 264 static void telnet_clear_line(struct connection *connection,
 265         struct telnet_connection *t_con)
 266 {
 267         /* move to end of line */
 268         if (t_con->line_cursor < t_con->line_size)
 269                 telnet_write(connection,
 270                         t_con->line + t_con->line_cursor,
 271                         t_con->line_size - t_con->line_cursor);
 272
 273         /* backspace, overwrite with space, backspace */
 274         while (t_con->line_size > 0) {
 275                 telnet_write(connection, "\b \b", 3);
 276                 t_con->line_size--;
 277         }
 278         t_con->line_cursor = 0;
 279 }
 280
 281 static void telnet_history_go(struct connection *connection, int idx)
 282 {
 283         struct telnet_connection *t_con = connection->priv;
 284
 285         if (t_con->history[idx]) {
 286                 telnet_clear_line(connection, t_con);
 287                 t_con->line_size = strlen(t_con->history[idx]);
 288                 t_con->line_cursor = t_con->line_size;
 289                 memcpy(t_con->line, t_con->history[idx], t_con->line_size);
 290                 telnet_write(connection, t_con->line, t_con->line_size);
 291                 t_con->current_history = idx;
 292         }
 293         t_con->state = TELNET_STATE_DATA;
 294 }
 295
 296 static void telnet_history_up(struct connection *connection)
 297 {
 298         struct telnet_connection *t_con = connection->priv;
 299
 300         size_t last_history = (t_con->current_history > 0) ?
 301                                 t_con->current_history - 1 :
 302                                 TELNET_LINE_HISTORY_SIZE-1;
 303         telnet_history_go(connection, last_history);
 304 }
 305
 306 static void telnet_history_down(struct connection *connection)
 307 {
 308         struct telnet_connection *t_con = connection->priv;
 309         size_t next_history;
 310
 311         next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 312         telnet_history_go(connection, next_history);
 313 }
 314
 315 static int telnet_history_print(struct connection *connection)
 316 {
 317         struct telnet_connection *tc;
 318
 319         tc = connection->priv;
 320
 321         for (size_t i = 1; i < TELNET_LINE_HISTORY_SIZE; i++) {
 322                 char *line;
 323
 324                 /*
 325                  * The tc->next_history line contains empty string (unless NULL), thus
 326                  * it is not printed.
 327                  */
 328                 line = tc->history[(tc->next_history + i) % TELNET_LINE_HISTORY_SIZE];
 329
 330                 if (line) {
 331                         telnet_write(connection, line, strlen(line));
 332                         telnet_write(connection, "\r\n\x00", 3);
 333                 }
 334         }
 335
 336         tc->line_size = 0;
 337         tc->line_cursor = 0;
 338
 339         /* The prompt is always placed at the line beginning. */
 340         telnet_write(connection, "\r", 1);
 341
 342         return telnet_prompt(connection);
 343 }
 344
 345 static void telnet_move_cursor(struct connection *connection, size_t pos)
 346 {
 347         struct telnet_connection *tc;
 348         size_t tmp;
 349
 350         tc = connection->priv;
 351
 352         if (pos < tc->line_cursor) {
 353                 tmp = tc->line_cursor - pos;
 354
 355                 for (size_t i = 0; i < tmp; i += 16)
 356                         telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 357                                 MIN(tmp - i, 16));
 358         } else {
 359                 tmp = pos - tc->line_cursor;
 360
 361                 for (size_t i = 0; i < tmp; i += 16)
 362                         telnet_write(connection, tc->line + tc->line_cursor + i,
 363                                 MIN(tmp - i, 16));
 364         }
 365
 366         tc->line_cursor = pos;
 367 }
 368
 369 static int telnet_input(struct connection *connection)
 370 {
 371         int bytes_read;
 372         unsigned char buffer[TELNET_BUFFER_SIZE];
 373         unsigned char *buf_p;
 374         struct telnet_connection *t_con = connection->priv;
 375         struct command_context *command_context = connection->cmd_ctx;
 376
 377         bytes_read = connection_read(connection, buffer, TELNET_BUFFER_SIZE);
 378
 379         if (bytes_read == 0)
 380                 return ERROR_SERVER_REMOTE_CLOSED;
 381         else if (bytes_read == -1) {
 382                 LOG_ERROR("error during read: %s", strerror(errno));
 383                 return ERROR_SERVER_REMOTE_CLOSED;
 384         }
 385
 386         buf_p = buffer;
 387         while (bytes_read) {
 388                 switch (t_con->state) {
 389                         case TELNET_STATE_DATA:
 390                                 if (*buf_p == 0xff)
 391                                         t_con->state = TELNET_STATE_IAC;
 392                                 else {
 393                                         if (isprint(*buf_p)) {  /* printable character */
 394                                                 /* watch buffer size leaving one spare character for
 395                                                  * string null termination */
 396                                                 if (t_con->line_size == TELNET_LINE_MAX_SIZE-1) {
 397                                                         /* output audible bell if buffer is full
 398                                                          * "\a" does not work, at least on windows */
 399                                                         telnet_write(connection, "\x07", 1);
 400                                                 } else if (t_con->line_cursor == t_con->line_size) {
 401                                                         telnet_write(connection, buf_p, 1);
 402                                                         t_con->line[t_con->line_size++] = *buf_p;
 403                                                         t_con->line_cursor++;
 404                                                 } else {
 405                                                         size_t i;
 406                                                         memmove(t_con->line + t_con->line_cursor + 1,
 407                                                                         t_con->line + t_con->line_cursor,
 408                                                                         t_con->line_size - t_con->line_cursor);
 409                                                         t_con->line[t_con->line_cursor] = *buf_p;
 410                                                         t_con->line_size++;
 411                                                         telnet_write(connection,
 412                                                                         t_con->line + t_con->line_cursor,
 413                                                                         t_con->line_size - t_con->line_cursor);
 414                                                         t_con->line_cursor++;
 415                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 416                                                                 telnet_write(connection, "\b", 1);
 417                                                 }
 418                                         } else {        /* non-printable */
 419                                                 if (*buf_p == 0x1b) {   /* escape */
 420                                                         t_con->state = TELNET_STATE_ESCAPE;
 421                                                         t_con->last_escape = '\x00';
 422                                                 } else if ((*buf_p == 0xd) || (*buf_p == 0xa)) {        /* CR/LF */
 423                                                         int retval;
 424
 425                                                         /* skip over combinations with CR/LF and NUL characters */
 426                                                         if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) ||
 427                                                                         (*(buf_p + 1) == 0xd))) {
 428                                                                 buf_p++;
 429                                                                 bytes_read--;
 430                                                         }
 431                                                         if ((bytes_read > 1) && (*(buf_p + 1) == 0)) {
 432                                                                 buf_p++;
 433                                                                 bytes_read--;
 434                                                         }
 435                                                         t_con->line[t_con->line_size] = 0;
 436
 437                                                         telnet_write(connection, "\r\n\x00", 3);
 438
 439                                                         if (strcmp(t_con->line, "history") == 0) {
 440                                                                 retval = telnet_history_print(connection);
 441
 442                                                                 if (retval != ERROR_OK)
 443                                                                         return retval;
 444
 445                                                                 continue;
 446                                                         }
 447
 448                                                         /* save only non-blank not repeating lines in the history */
 449                                                         char *prev_line = t_con->history[(t_con->current_history > 0) ?
 450                                                                         t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
 451                                                         if (*t_con->line && (prev_line == NULL ||
 452                                                                         strcmp(t_con->line, prev_line))) {
 453                                                                 /* if the history slot is already taken, free it */
 454                                                                 if (t_con->history[t_con->next_history])
 455                                                                         free(t_con->history[t_con->next_history]);
 456
 457                                                                 /* add line to history */
 458                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 459
 460                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 461                                                                 t_con->next_history = (t_con->next_history + 1) %
 462                                                                                 TELNET_LINE_HISTORY_SIZE;
 463
 464                                                                 /* current history line starts at the new entry */
 465                                                                 t_con->current_history =
 466                                                                                 t_con->next_history;
 467
 468                                                                 if (t_con->history[t_con->current_history])
 469                                                                         free(t_con->history[t_con->current_history]);
 470                                                                 t_con->history[t_con->current_history] = strdup("");
 471                                                         }
 472
 473                                                         t_con->line_size = 0;
 474
 475                                                         /* to suppress prompt in log callback during command execution */
 476                                                         t_con->prompt_visible = false;
 477
 478                                                         if (strcmp(t_con->line, "shutdown") == 0)
 479                                                                 telnet_save_history(t_con);
 480
 481                                                         retval = command_run_line(command_context, t_con->line);
 482
 483                                                         t_con->line_cursor = 0;
 484                                                         t_con->prompt_visible = true;
 485
 486                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 487                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 488
 489                                                         /* the prompt is always * placed at the line beginning */
 490                                                         telnet_write(connection, "\r", 1);
 491
 492                                                         retval = telnet_prompt(connection);
 493                                                         if (retval == ERROR_SERVER_REMOTE_CLOSED)
 494                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 495
 496                                                 } else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) {       /* delete character */
 497                                                         if (t_con->line_cursor > 0) {
 498                                                                 if (t_con->line_cursor != t_con->line_size) {
 499                                                                         size_t i;
 500                                                                         telnet_write(connection, "\b", 1);
 501                                                                         t_con->line_cursor--;
 502                                                                         t_con->line_size--;
 503                                                                         memmove(t_con->line + t_con->line_cursor,
 504                                                                                         t_con->line + t_con->line_cursor + 1,
 505                                                                                         t_con->line_size -
 506                                                                                         t_con->line_cursor);
 507
 508                                                                         telnet_write(connection,
 509                                                                                         t_con->line + t_con->line_cursor,
 510                                                                                         t_con->line_size -
 511                                                                                         t_con->line_cursor);
 512                                                                         telnet_write(connection, " \b", 2);
 513                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 514                                                                                 telnet_write(connection, "\b", 1);
 515                                                                 } else {
 516                                                                         t_con->line_size--;
 517                                                                         t_con->line_cursor--;
 518                                                                         /* back space: move the 'printer' head one char
 519                                                                          * back, overwrite with space, move back again */
 520                                                                         telnet_write(connection, "\b \b", 3);
 521                                                                 }
 522                                                         }
 523                                                 } else if (*buf_p == 0x15) /* clear line */
 524                                                         telnet_clear_line(connection, t_con);
 525                                                 else if (*buf_p == CTRL('B')) { /* cursor left */
 526                                                         if (t_con->line_cursor > 0) {
 527                                                                 telnet_write(connection, "\b", 1);
 528                                                                 t_con->line_cursor--;
 529                                                         }
 530                                                         t_con->state = TELNET_STATE_DATA;
 531                                                 } else if (*buf_p == CTRL('F')) {       /* cursor right */
 532                                                         if (t_con->line_cursor < t_con->line_size)
 533                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 534                                                         t_con->state = TELNET_STATE_DATA;
 535                                                 } else if (*buf_p == CTRL('P'))         /* cursor up */
 536                                                         telnet_history_up(connection);
 537                                                 else if (*buf_p == CTRL('N'))           /* cursor down */
 538                                                         telnet_history_down(connection);
 539                                                 else if (*buf_p == CTRL('A'))
 540                                                         telnet_move_cursor(connection, 0);
 541                                                 else if (*buf_p == CTRL('E'))
 542                                                         telnet_move_cursor(connection, t_con->line_size);
 543                                                 else
 544                                                         LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 545                                         }
 546                                 }
 547                                 break;
 548                         case TELNET_STATE_IAC:
 549                                 switch (*buf_p) {
 550                                 case 0xfe:
 551                                         t_con->state = TELNET_STATE_DONT;
 552                                         break;
 553                                 case 0xfd:
 554                                         t_con->state = TELNET_STATE_DO;
 555                                         break;
 556                                 case 0xfc:
 557                                         t_con->state = TELNET_STATE_WONT;
 558                                         break;
 559                                 case 0xfb:
 560                                         t_con->state = TELNET_STATE_WILL;
 561                                         break;
 562                                 }
 563                                 break;
 564                         case TELNET_STATE_SB:
 565                                 break;
 566                         case TELNET_STATE_SE:
 567                                 break;
 568                         case TELNET_STATE_WILL:
 569                         case TELNET_STATE_WONT:
 570                         case TELNET_STATE_DO:
 571                         case TELNET_STATE_DONT:
 572                                 t_con->state = TELNET_STATE_DATA;
 573                                 break;
 574                         case TELNET_STATE_ESCAPE:
 575                                 if (t_con->last_escape == '[') {
 576                                         if (*buf_p == 'D') {    /* cursor left */
 577                                                 if (t_con->line_cursor > 0) {
 578                                                         telnet_write(connection, "\b", 1);
 579                                                         t_con->line_cursor--;
 580                                                 }
 581                                                 t_con->state = TELNET_STATE_DATA;
 582                                         } else if (*buf_p == 'C') {     /* cursor right */
 583                                                 if (t_con->line_cursor < t_con->line_size)
 584                                                         telnet_write(connection,
 585                                                                         t_con->line + t_con->line_cursor++, 1);
 586                                                 t_con->state = TELNET_STATE_DATA;
 587                                         } else if (*buf_p == 'A') {     /* cursor up */
 588                                                 telnet_history_up(connection);
 589                                         } else if (*buf_p == 'B') {     /* cursor down */
 590                                                 telnet_history_down(connection);
 591                                         } else if (*buf_p == '3')
 592                                                 t_con->last_escape = *buf_p;
 593                                         else
 594                                                 t_con->state = TELNET_STATE_DATA;
 595                                 } else if (t_con->last_escape == '3') {
 596                                         /* Remove character */
 597                                         if (*buf_p == '~') {
 598                                                 if (t_con->line_cursor < t_con->line_size) {
 599                                                         size_t i;
 600                                                         t_con->line_size--;
 601                                                         /* remove char from line buffer */
 602                                                         memmove(t_con->line + t_con->line_cursor,
 603                                                                         t_con->line + t_con->line_cursor + 1,
 604                                                                         t_con->line_size - t_con->line_cursor);
 605
 606                                                         /* print remainder of buffer */
 607                                                         telnet_write(connection, t_con->line + t_con->line_cursor,
 608                                                                         t_con->line_size - t_con->line_cursor);
 609                                                         /* overwrite last char with whitespace */
 610                                                         telnet_write(connection, " \b", 2);
 611
 612                                                         /* move back to cursor position*/
 613                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 614                                                                 telnet_write(connection, "\b", 1);
 615                                                 }
 616
 617                                                 t_con->state = TELNET_STATE_DATA;
 618                                         } else
 619                                                 t_con->state = TELNET_STATE_DATA;
 620                                 } else if (t_con->last_escape == '\x00') {
 621                                         if (*buf_p == '[')
 622                                                 t_con->last_escape = *buf_p;
 623                                         else
 624                                                 t_con->state = TELNET_STATE_DATA;
 625                                 } else {
 626                                         LOG_ERROR("BUG: unexpected value in t_con->last_escape");
 627                                         t_con->state = TELNET_STATE_DATA;
 628                                 }
 629
 630                                 break;
 631                         default:
 632                                 LOG_ERROR("unknown telnet state");
 633                                 return ERROR_FAIL;
 634                 }
 635
 636                 bytes_read--;
 637                 buf_p++;
 638         }
 639
 640         return ERROR_OK;
 641 }
 642
 643 static int telnet_connection_closed(struct connection *connection)
 644 {
 645         struct telnet_connection *t_con = connection->priv;
 646         int i;
 647
 648         log_remove_callback(telnet_log_callback, connection);
 649
 650         if (t_con->prompt) {
 651                 free(t_con->prompt);
 652                 t_con->prompt = NULL;
 653         }
 654
 655         /* save telnet history */
 656         telnet_save_history(t_con);
 657
 658         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++) {
 659                 if (t_con->history[i]) {
 660                         free(t_con->history[i]);
 661                         t_con->history[i] = NULL;
 662                 }
 663         }
 664
 665         /* if this connection registered a debug-message receiver delete it */
 666         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 667
 668         if (connection->priv) {
 669                 free(connection->priv);
 670                 connection->priv = NULL;
 671         } else
 672                 LOG_ERROR("BUG: connection->priv == NULL");
 673
 674         return ERROR_OK;
 675 }
 676
 677 int telnet_init(char *banner)
 678 {
 679         if (strcmp(telnet_port, "disabled") == 0) {
 680                 LOG_INFO("telnet server disabled");
 681                 return ERROR_OK;
 682         }
 683
 684         struct telnet_service *telnet_service =
 685                 malloc(sizeof(struct telnet_service));
 686
 687         if (!telnet_service) {
 688                 LOG_ERROR("Failed to allocate telnet service.");
 689                 return ERROR_FAIL;
 690         }
 691
 692         telnet_service->banner = banner;
 693
 694         int ret = add_service("telnet", telnet_port, CONNECTION_LIMIT_UNLIMITED,
 695                 telnet_new_connection, telnet_input, telnet_connection_closed,
 696                 telnet_service);
 697
 698         if (ret != ERROR_OK) {
 699                 free(telnet_service);
 700                 return ret;
 701         }
 702
 703         return ERROR_OK;
 704 }
 705
 706 /* daemon configuration command telnet_port */
 707 COMMAND_HANDLER(handle_telnet_port_command)
 708 {
 709         return CALL_COMMAND_HANDLER(server_pipe_command, &telnet_port);
 710 }
 711
 712 COMMAND_HANDLER(handle_exit_command)
 713 {
 714         return ERROR_COMMAND_CLOSE_CONNECTION;
 715 }
 716
 717 static const struct command_registration telnet_command_handlers[] = {
 718         {
 719                 .name = "exit",
 720                 .handler = handle_exit_command,
 721                 .mode = COMMAND_EXEC,
 722                 .usage = "",
 723                 .help = "exit telnet session",
 724         },
 725         {
 726                 .name = "telnet_port",
 727                 .handler = handle_telnet_port_command,
 728                 .mode = COMMAND_CONFIG,
 729                 .help = "Specify port on which to listen "
 730                         "for incoming telnet connections.  "
 731                         "Read help on 'gdb_port'.",
 732                 .usage = "[port_num]",
 733         },
 734         COMMAND_REGISTRATION_DONE
 735 };
 736
 737 int telnet_register_commands(struct command_context *cmd_ctx)
 738 {
 739         telnet_port = strdup("4444");
 740         return register_commands(cmd_ctx, NULL, telnet_command_handlers);
 741 }
 742
 743 void telnet_service_free(void)
 744 {
 745         free(telnet_port);
 746 }