git.sur5r.net Git - openocd/blob - src/server/telnet_server.c

   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 void telnet_move_cursor(struct connection *connection, size_t pos)
 316 {
 317         struct telnet_connection *tc;
 318         size_t tmp;
 319
 320         tc = connection->priv;
 321
 322         if (pos < tc->line_cursor) {
 323                 tmp = tc->line_cursor - pos;
 324
 325                 for (size_t i = 0; i < tmp; i += 16)
 326                         telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 327                                 MIN(tmp - i, 16));
 328         } else {
 329                 tmp = pos - tc->line_cursor;
 330
 331                 for (size_t i = 0; i < tmp; i += 16)
 332                         telnet_write(connection, tc->line + tc->line_cursor + i,
 333                                 MIN(tmp - i, 16));
 334         }
 335
 336         tc->line_cursor = pos;
 337 }
 338
 339 static int telnet_input(struct connection *connection)
 340 {
 341         int bytes_read;
 342         unsigned char buffer[TELNET_BUFFER_SIZE];
 343         unsigned char *buf_p;
 344         struct telnet_connection *t_con = connection->priv;
 345         struct command_context *command_context = connection->cmd_ctx;
 346
 347         bytes_read = connection_read(connection, buffer, TELNET_BUFFER_SIZE);
 348
 349         if (bytes_read == 0)
 350                 return ERROR_SERVER_REMOTE_CLOSED;
 351         else if (bytes_read == -1) {
 352                 LOG_ERROR("error during read: %s", strerror(errno));
 353                 return ERROR_SERVER_REMOTE_CLOSED;
 354         }
 355
 356         buf_p = buffer;
 357         while (bytes_read) {
 358                 switch (t_con->state) {
 359                         case TELNET_STATE_DATA:
 360                                 if (*buf_p == 0xff)
 361                                         t_con->state = TELNET_STATE_IAC;
 362                                 else {
 363                                         if (isprint(*buf_p)) {  /* printable character */
 364                                                 /* watch buffer size leaving one spare character for
 365                                                  * string null termination */
 366                                                 if (t_con->line_size == TELNET_LINE_MAX_SIZE-1) {
 367                                                         /* output audible bell if buffer is full
 368                                                          * "\a" does not work, at least on windows */
 369                                                         telnet_write(connection, "\x07", 1);
 370                                                 } else if (t_con->line_cursor == t_con->line_size) {
 371                                                         telnet_write(connection, buf_p, 1);
 372                                                         t_con->line[t_con->line_size++] = *buf_p;
 373                                                         t_con->line_cursor++;
 374                                                 } else {
 375                                                         size_t i;
 376                                                         memmove(t_con->line + t_con->line_cursor + 1,
 377                                                                         t_con->line + t_con->line_cursor,
 378                                                                         t_con->line_size - t_con->line_cursor);
 379                                                         t_con->line[t_con->line_cursor] = *buf_p;
 380                                                         t_con->line_size++;
 381                                                         telnet_write(connection,
 382                                                                         t_con->line + t_con->line_cursor,
 383                                                                         t_con->line_size - t_con->line_cursor);
 384                                                         t_con->line_cursor++;
 385                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 386                                                                 telnet_write(connection, "\b", 1);
 387                                                 }
 388                                         } else {        /* non-printable */
 389                                                 if (*buf_p == 0x1b) {   /* escape */
 390                                                         t_con->state = TELNET_STATE_ESCAPE;
 391                                                         t_con->last_escape = '\x00';
 392                                                 } else if ((*buf_p == 0xd) || (*buf_p == 0xa)) {        /* CR/LF */
 393                                                         int retval;
 394
 395                                                         /* skip over combinations with CR/LF and NUL characters */
 396                                                         if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) ||
 397                                                                         (*(buf_p + 1) == 0xd))) {
 398                                                                 buf_p++;
 399                                                                 bytes_read--;
 400                                                         }
 401                                                         if ((bytes_read > 1) && (*(buf_p + 1) == 0)) {
 402                                                                 buf_p++;
 403                                                                 bytes_read--;
 404                                                         }
 405                                                         t_con->line[t_con->line_size] = 0;
 406
 407                                                         telnet_write(connection, "\r\n\x00", 3);
 408
 409                                                         if (strcmp(t_con->line, "history") == 0) {
 410                                                                 size_t i;
 411                                                                 for (i = 1; i < TELNET_LINE_HISTORY_SIZE; i++) {
 412                                                                         /* the t_con->next_history line contains empty string
 413                                                                          * (unless NULL), thus it is not printed */
 414                                                                         char *history_line = t_con->history[(t_con->
 415                                                                                         next_history + i) %
 416                                                                                         TELNET_LINE_HISTORY_SIZE];
 417                                                                         if (history_line) {
 418                                                                                 telnet_write(connection, history_line,
 419                                                                                                 strlen(history_line));
 420                                                                                 telnet_write(connection, "\r\n\x00", 3);
 421                                                                         }
 422                                                                 }
 423                                                                 t_con->line_size = 0;
 424                                                                 t_con->line_cursor = 0;
 425                                                                 continue;
 426                                                         }
 427
 428                                                         /* save only non-blank not repeating lines in the history */
 429                                                         char *prev_line = t_con->history[(t_con->current_history > 0) ?
 430                                                                         t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
 431                                                         if (*t_con->line && (prev_line == NULL ||
 432                                                                         strcmp(t_con->line, prev_line))) {
 433                                                                 /* if the history slot is already taken, free it */
 434                                                                 if (t_con->history[t_con->next_history])
 435                                                                         free(t_con->history[t_con->next_history]);
 436
 437                                                                 /* add line to history */
 438                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 439
 440                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 441                                                                 t_con->next_history = (t_con->next_history + 1) %
 442                                                                                 TELNET_LINE_HISTORY_SIZE;
 443
 444                                                                 /* current history line starts at the new entry */
 445                                                                 t_con->current_history =
 446                                                                                 t_con->next_history;
 447
 448                                                                 if (t_con->history[t_con->current_history])
 449                                                                         free(t_con->history[t_con->current_history]);
 450                                                                 t_con->history[t_con->current_history] = strdup("");
 451                                                         }
 452
 453                                                         t_con->line_size = 0;
 454
 455                                                         /* to suppress prompt in log callback during command execution */
 456                                                         t_con->prompt_visible = false;
 457
 458                                                         if (strcmp(t_con->line, "shutdown") == 0)
 459                                                                 telnet_save_history(t_con);
 460
 461                                                         retval = command_run_line(command_context, t_con->line);
 462
 463                                                         t_con->line_cursor = 0;
 464                                                         t_con->prompt_visible = true;
 465
 466                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 467                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 468
 469                                                         /* the prompt is always * placed at the line beginning */
 470                                                         telnet_write(connection, "\r", 1);
 471
 472                                                         retval = telnet_prompt(connection);
 473                                                         if (retval == ERROR_SERVER_REMOTE_CLOSED)
 474                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 475
 476                                                 } else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) {       /* delete character */
 477                                                         if (t_con->line_cursor > 0) {
 478                                                                 if (t_con->line_cursor != t_con->line_size) {
 479                                                                         size_t i;
 480                                                                         telnet_write(connection, "\b", 1);
 481                                                                         t_con->line_cursor--;
 482                                                                         t_con->line_size--;
 483                                                                         memmove(t_con->line + t_con->line_cursor,
 484                                                                                         t_con->line + t_con->line_cursor + 1,
 485                                                                                         t_con->line_size -
 486                                                                                         t_con->line_cursor);
 487
 488                                                                         telnet_write(connection,
 489                                                                                         t_con->line + t_con->line_cursor,
 490                                                                                         t_con->line_size -
 491                                                                                         t_con->line_cursor);
 492                                                                         telnet_write(connection, " \b", 2);
 493                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 494                                                                                 telnet_write(connection, "\b", 1);
 495                                                                 } else {
 496                                                                         t_con->line_size--;
 497                                                                         t_con->line_cursor--;
 498                                                                         /* back space: move the 'printer' head one char
 499                                                                          * back, overwrite with space, move back again */
 500                                                                         telnet_write(connection, "\b \b", 3);
 501                                                                 }
 502                                                         }
 503                                                 } else if (*buf_p == 0x15) /* clear line */
 504                                                         telnet_clear_line(connection, t_con);
 505                                                 else if (*buf_p == CTRL('B')) { /* cursor left */
 506                                                         if (t_con->line_cursor > 0) {
 507                                                                 telnet_write(connection, "\b", 1);
 508                                                                 t_con->line_cursor--;
 509                                                         }
 510                                                         t_con->state = TELNET_STATE_DATA;
 511                                                 } else if (*buf_p == CTRL('F')) {       /* cursor right */
 512                                                         if (t_con->line_cursor < t_con->line_size)
 513                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 514                                                         t_con->state = TELNET_STATE_DATA;
 515                                                 } else if (*buf_p == CTRL('P'))         /* cursor up */
 516                                                         telnet_history_up(connection);
 517                                                 else if (*buf_p == CTRL('N'))           /* cursor down */
 518                                                         telnet_history_down(connection);
 519                                                 else if (*buf_p == CTRL('A'))
 520                                                         telnet_move_cursor(connection, 0);
 521                                                 else if (*buf_p == CTRL('E'))
 522                                                         telnet_move_cursor(connection, t_con->line_size);
 523                                                 else
 524                                                         LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 525                                         }
 526                                 }
 527                                 break;
 528                         case TELNET_STATE_IAC:
 529                                 switch (*buf_p) {
 530                                 case 0xfe:
 531                                         t_con->state = TELNET_STATE_DONT;
 532                                         break;
 533                                 case 0xfd:
 534                                         t_con->state = TELNET_STATE_DO;
 535                                         break;
 536                                 case 0xfc:
 537                                         t_con->state = TELNET_STATE_WONT;
 538                                         break;
 539                                 case 0xfb:
 540                                         t_con->state = TELNET_STATE_WILL;
 541                                         break;
 542                                 }
 543                                 break;
 544                         case TELNET_STATE_SB:
 545                                 break;
 546                         case TELNET_STATE_SE:
 547                                 break;
 548                         case TELNET_STATE_WILL:
 549                         case TELNET_STATE_WONT:
 550                         case TELNET_STATE_DO:
 551                         case TELNET_STATE_DONT:
 552                                 t_con->state = TELNET_STATE_DATA;
 553                                 break;
 554                         case TELNET_STATE_ESCAPE:
 555                                 if (t_con->last_escape == '[') {
 556                                         if (*buf_p == 'D') {    /* cursor left */
 557                                                 if (t_con->line_cursor > 0) {
 558                                                         telnet_write(connection, "\b", 1);
 559                                                         t_con->line_cursor--;
 560                                                 }
 561                                                 t_con->state = TELNET_STATE_DATA;
 562                                         } else if (*buf_p == 'C') {     /* cursor right */
 563                                                 if (t_con->line_cursor < t_con->line_size)
 564                                                         telnet_write(connection,
 565                                                                         t_con->line + t_con->line_cursor++, 1);
 566                                                 t_con->state = TELNET_STATE_DATA;
 567                                         } else if (*buf_p == 'A') {     /* cursor up */
 568                                                 telnet_history_up(connection);
 569                                         } else if (*buf_p == 'B') {     /* cursor down */
 570                                                 telnet_history_down(connection);
 571                                         } else if (*buf_p == '3')
 572                                                 t_con->last_escape = *buf_p;
 573                                         else
 574                                                 t_con->state = TELNET_STATE_DATA;
 575                                 } else if (t_con->last_escape == '3') {
 576                                         /* Remove character */
 577                                         if (*buf_p == '~') {
 578                                                 if (t_con->line_cursor < t_con->line_size) {
 579                                                         size_t i;
 580                                                         t_con->line_size--;
 581                                                         /* remove char from line buffer */
 582                                                         memmove(t_con->line + t_con->line_cursor,
 583                                                                         t_con->line + t_con->line_cursor + 1,
 584                                                                         t_con->line_size - t_con->line_cursor);
 585
 586                                                         /* print remainder of buffer */
 587                                                         telnet_write(connection, t_con->line + t_con->line_cursor,
 588                                                                         t_con->line_size - t_con->line_cursor);
 589                                                         /* overwrite last char with whitespace */
 590                                                         telnet_write(connection, " \b", 2);
 591
 592                                                         /* move back to cursor position*/
 593                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 594                                                                 telnet_write(connection, "\b", 1);
 595                                                 }
 596
 597                                                 t_con->state = TELNET_STATE_DATA;
 598                                         } else
 599                                                 t_con->state = TELNET_STATE_DATA;
 600                                 } else if (t_con->last_escape == '\x00') {
 601                                         if (*buf_p == '[')
 602                                                 t_con->last_escape = *buf_p;
 603                                         else
 604                                                 t_con->state = TELNET_STATE_DATA;
 605                                 } else {
 606                                         LOG_ERROR("BUG: unexpected value in t_con->last_escape");
 607                                         t_con->state = TELNET_STATE_DATA;
 608                                 }
 609
 610                                 break;
 611                         default:
 612                                 LOG_ERROR("unknown telnet state");
 613                                 return ERROR_FAIL;
 614                 }
 615
 616                 bytes_read--;
 617                 buf_p++;
 618         }
 619
 620         return ERROR_OK;
 621 }
 622
 623 static int telnet_connection_closed(struct connection *connection)
 624 {
 625         struct telnet_connection *t_con = connection->priv;
 626         int i;
 627
 628         log_remove_callback(telnet_log_callback, connection);
 629
 630         if (t_con->prompt) {
 631                 free(t_con->prompt);
 632                 t_con->prompt = NULL;
 633         }
 634
 635         /* save telnet history */
 636         telnet_save_history(t_con);
 637
 638         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++) {
 639                 if (t_con->history[i]) {
 640                         free(t_con->history[i]);
 641                         t_con->history[i] = NULL;
 642                 }
 643         }
 644
 645         /* if this connection registered a debug-message receiver delete it */
 646         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 647
 648         if (connection->priv) {
 649                 free(connection->priv);
 650                 connection->priv = NULL;
 651         } else
 652                 LOG_ERROR("BUG: connection->priv == NULL");
 653
 654         return ERROR_OK;
 655 }
 656
 657 int telnet_init(char *banner)
 658 {
 659         if (strcmp(telnet_port, "disabled") == 0) {
 660                 LOG_INFO("telnet server disabled");
 661                 return ERROR_OK;
 662         }
 663
 664         struct telnet_service *telnet_service =
 665                 malloc(sizeof(struct telnet_service));
 666
 667         if (!telnet_service) {
 668                 LOG_ERROR("Failed to allocate telnet service.");
 669                 return ERROR_FAIL;
 670         }
 671
 672         telnet_service->banner = banner;
 673
 674         int ret = add_service("telnet", telnet_port, CONNECTION_LIMIT_UNLIMITED,
 675                 telnet_new_connection, telnet_input, telnet_connection_closed,
 676                 telnet_service);
 677
 678         if (ret != ERROR_OK) {
 679                 free(telnet_service);
 680                 return ret;
 681         }
 682
 683         return ERROR_OK;
 684 }
 685
 686 /* daemon configuration command telnet_port */
 687 COMMAND_HANDLER(handle_telnet_port_command)
 688 {
 689         return CALL_COMMAND_HANDLER(server_pipe_command, &telnet_port);
 690 }
 691
 692 COMMAND_HANDLER(handle_exit_command)
 693 {
 694         return ERROR_COMMAND_CLOSE_CONNECTION;
 695 }
 696
 697 static const struct command_registration telnet_command_handlers[] = {
 698         {
 699                 .name = "exit",
 700                 .handler = handle_exit_command,
 701                 .mode = COMMAND_EXEC,
 702                 .usage = "",
 703                 .help = "exit telnet session",
 704         },
 705         {
 706                 .name = "telnet_port",
 707                 .handler = handle_telnet_port_command,
 708                 .mode = COMMAND_ANY,
 709                 .help = "Specify port on which to listen "
 710                         "for incoming telnet connections.  "
 711                         "Read help on 'gdb_port'.",
 712                 .usage = "[port_num]",
 713         },
 714         COMMAND_REGISTRATION_DONE
 715 };
 716
 717 int telnet_register_commands(struct command_context *cmd_ctx)
 718 {
 719         telnet_port = strdup("4444");
 720         return register_commands(cmd_ctx, NULL, telnet_command_handlers);
 721 }
 722
 723 void telnet_service_free(void)
 724 {
 725         free(telnet_port);
 726 }