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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 #include <helper/list.h>
  33
  34 static char *telnet_port;
  35
  36 static char *negotiate =
  37         "\xFF\xFB\x03"                  /* IAC WILL Suppress Go Ahead */
  38         "\xFF\xFB\x01"                  /* IAC WILL Echo */
  39         "\xFF\xFD\x03"                  /* IAC DO Suppress Go Ahead */
  40         "\xFF\xFE\x01";                 /* IAC DON'T Echo */
  41
  42 #define CTRL(c) (c - '@')
  43 #define TELNET_HISTORY  ".openocd_history"
  44
  45 /* The only way we can detect that the socket is closed is the first time
  46  * we write to it, we will fail. Subsequent write operations will
  47  * succeed. Shudder!
  48  */
  49 static int telnet_write(struct connection *connection, const void *data,
  50         int len)
  51 {
  52         struct telnet_connection *t_con = connection->priv;
  53         if (t_con->closed)
  54                 return ERROR_SERVER_REMOTE_CLOSED;
  55
  56         if (connection_write(connection, data, len) == len)
  57                 return ERROR_OK;
  58         t_con->closed = true;
  59         return ERROR_SERVER_REMOTE_CLOSED;
  60 }
  61
  62 /* output an audible bell */
  63 static int telnet_bell(struct connection *connection)
  64 {
  65         /* ("\a" does not work, at least on windows) */
  66         return telnet_write(connection, "\x07", 1);
  67 }
  68
  69 static int telnet_prompt(struct connection *connection)
  70 {
  71         struct telnet_connection *t_con = connection->priv;
  72
  73         return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
  74 }
  75
  76 static int telnet_outputline(struct connection *connection, const char *line)
  77 {
  78         int len;
  79
  80         /* process lines in buffer */
  81         while (*line) {
  82                 char *line_end = strchr(line, '\n');
  83
  84                 if (line_end)
  85                         len = line_end-line;
  86                 else
  87                         len = strlen(line);
  88
  89                 telnet_write(connection, line, len);
  90                 if (line_end) {
  91                         telnet_write(connection, "\r\n", 2);
  92                         line += len + 1;
  93                 } else
  94                         line += len;
  95         }
  96
  97         return ERROR_OK;
  98 }
  99
 100 static int telnet_output(struct command_context *cmd_ctx, const char *line)
 101 {
 102         struct connection *connection = cmd_ctx->output_handler_priv;
 103
 104         return telnet_outputline(connection, line);
 105 }
 106
 107 static void telnet_log_callback(void *priv, const char *file, unsigned line,
 108         const char *function, const char *string)
 109 {
 110         struct connection *connection = priv;
 111         struct telnet_connection *t_con = connection->priv;
 112         size_t i;
 113         size_t tmp;
 114
 115         /* If the prompt is not visible, simply output the message. */
 116         if (!t_con->prompt_visible) {
 117                 telnet_outputline(connection, string);
 118                 return;
 119         }
 120
 121         /* Clear the command line. */
 122         tmp = strlen(t_con->prompt) + t_con->line_size;
 123
 124         for (i = 0; i < tmp; i += 16)
 125                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 126                         MIN(tmp - i, 16));
 127
 128         for (i = 0; i < tmp; i += 16)
 129                 telnet_write(connection, "                ", MIN(tmp - i, 16));
 130
 131         for (i = 0; i < tmp; i += 16)
 132                 telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 133                         MIN(tmp - i, 16));
 134
 135         telnet_outputline(connection, string);
 136
 137         /* Put the command line to its previous state. */
 138         telnet_prompt(connection);
 139         telnet_write(connection, t_con->line, t_con->line_size);
 140
 141         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 142                 telnet_write(connection, "\b", 1);
 143 }
 144
 145 static void telnet_load_history(struct telnet_connection *t_con)
 146 {
 147         FILE *histfp;
 148         char buffer[TELNET_BUFFER_SIZE];
 149         int i = 0;
 150
 151         char *history = get_home_dir(TELNET_HISTORY);
 152
 153         if (!history) {
 154                 LOG_INFO("unable to get user home directory, telnet history will be disabled");
 155                 return;
 156         }
 157
 158         histfp = fopen(history, "rb");
 159
 160         if (histfp) {
 161
 162                 while (fgets(buffer, sizeof(buffer), histfp)) {
 163
 164                         char *p = strchr(buffer, '\n');
 165                         if (p)
 166                                 *p = '\0';
 167                         if (buffer[0] && i < TELNET_LINE_HISTORY_SIZE)
 168                                 t_con->history[i++] = strdup(buffer);
 169                 }
 170
 171                 t_con->next_history = i;
 172                 t_con->next_history %= TELNET_LINE_HISTORY_SIZE;
 173                 /* try to set to last entry - 1, that way we skip over any exit/shutdown cmds */
 174                 t_con->current_history = t_con->next_history > 0 ? i - 1 : 0;
 175                 fclose(histfp);
 176         }
 177
 178         free(history);
 179 }
 180
 181 static void telnet_save_history(struct telnet_connection *t_con)
 182 {
 183         FILE *histfp;
 184         int i;
 185         int num;
 186
 187         char *history = get_home_dir(TELNET_HISTORY);
 188
 189         if (!history) {
 190                 LOG_INFO("unable to get user home directory, telnet history will be disabled");
 191                 return;
 192         }
 193
 194         histfp = fopen(history, "wb");
 195
 196         if (histfp) {
 197
 198                 num = TELNET_LINE_HISTORY_SIZE;
 199                 i = t_con->current_history + 1;
 200                 i %= TELNET_LINE_HISTORY_SIZE;
 201
 202                 while (!t_con->history[i] && num > 0) {
 203                         i++;
 204                         i %= TELNET_LINE_HISTORY_SIZE;
 205                         num--;
 206                 }
 207
 208                 if (num > 0) {
 209                         for (; num > 0; num--) {
 210                                 fprintf(histfp, "%s\n", t_con->history[i]);
 211                                 i++;
 212                                 i %= TELNET_LINE_HISTORY_SIZE;
 213                         }
 214                 }
 215                 fclose(histfp);
 216         }
 217
 218         free(history);
 219 }
 220
 221 static int telnet_new_connection(struct connection *connection)
 222 {
 223         struct telnet_connection *telnet_connection;
 224         struct telnet_service *telnet_service = connection->service->priv;
 225         int i;
 226
 227         telnet_connection = malloc(sizeof(struct telnet_connection));
 228
 229         if (!telnet_connection) {
 230                 LOG_ERROR("Failed to allocate telnet connection.");
 231                 return ERROR_FAIL;
 232         }
 233
 234         connection->priv = telnet_connection;
 235
 236         /* initialize telnet connection information */
 237         telnet_connection->closed = false;
 238         telnet_connection->line_size = 0;
 239         telnet_connection->line_cursor = 0;
 240         telnet_connection->prompt = strdup("> ");
 241         telnet_connection->prompt_visible = true;
 242         telnet_connection->state = TELNET_STATE_DATA;
 243
 244         /* output goes through telnet connection */
 245         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 246
 247         /* negotiate telnet options */
 248         telnet_write(connection, negotiate, strlen(negotiate));
 249
 250         /* print connection banner */
 251         if (telnet_service->banner) {
 252                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 253                 telnet_write(connection, "\r\n", 2);
 254         }
 255
 256         /* the prompt is always placed at the line beginning */
 257         telnet_write(connection, "\r", 1);
 258         telnet_prompt(connection);
 259
 260         /* initialize history */
 261         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 262                 telnet_connection->history[i] = NULL;
 263         telnet_connection->next_history = 0;
 264         telnet_connection->current_history = 0;
 265         telnet_load_history(telnet_connection);
 266
 267         log_add_callback(telnet_log_callback, connection);
 268
 269         return ERROR_OK;
 270 }
 271
 272 static void telnet_clear_line(struct connection *connection,
 273         struct telnet_connection *t_con)
 274 {
 275         /* move to end of line */
 276         if (t_con->line_cursor < t_con->line_size)
 277                 telnet_write(connection,
 278                         t_con->line + t_con->line_cursor,
 279                         t_con->line_size - t_con->line_cursor);
 280
 281         /* backspace, overwrite with space, backspace */
 282         while (t_con->line_size > 0) {
 283                 telnet_write(connection, "\b \b", 3);
 284                 t_con->line_size--;
 285         }
 286         t_con->line_cursor = 0;
 287 }
 288
 289 static void telnet_history_go(struct connection *connection, int idx)
 290 {
 291         struct telnet_connection *t_con = connection->priv;
 292
 293         if (t_con->history[idx]) {
 294                 telnet_clear_line(connection, t_con);
 295                 t_con->line_size = strlen(t_con->history[idx]);
 296                 t_con->line_cursor = t_con->line_size;
 297                 memcpy(t_con->line, t_con->history[idx], t_con->line_size);
 298                 telnet_write(connection, t_con->line, t_con->line_size);
 299                 t_con->current_history = idx;
 300         }
 301         t_con->state = TELNET_STATE_DATA;
 302 }
 303
 304 static void telnet_history_up(struct connection *connection)
 305 {
 306         struct telnet_connection *t_con = connection->priv;
 307
 308         size_t last_history = (t_con->current_history > 0) ?
 309                                 t_con->current_history - 1 :
 310                                 TELNET_LINE_HISTORY_SIZE-1;
 311         telnet_history_go(connection, last_history);
 312 }
 313
 314 static void telnet_history_down(struct connection *connection)
 315 {
 316         struct telnet_connection *t_con = connection->priv;
 317         size_t next_history;
 318
 319         next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 320         telnet_history_go(connection, next_history);
 321 }
 322
 323 static int telnet_history_print(struct connection *connection)
 324 {
 325         struct telnet_connection *tc;
 326
 327         tc = connection->priv;
 328
 329         for (size_t i = 1; i < TELNET_LINE_HISTORY_SIZE; i++) {
 330                 char *line;
 331
 332                 /*
 333                  * The tc->next_history line contains empty string (unless NULL), thus
 334                  * it is not printed.
 335                  */
 336                 line = tc->history[(tc->next_history + i) % TELNET_LINE_HISTORY_SIZE];
 337
 338                 if (line) {
 339                         telnet_write(connection, line, strlen(line));
 340                         telnet_write(connection, "\r\n\x00", 3);
 341                 }
 342         }
 343
 344         tc->line_size = 0;
 345         tc->line_cursor = 0;
 346
 347         /* The prompt is always placed at the line beginning. */
 348         telnet_write(connection, "\r", 1);
 349
 350         return telnet_prompt(connection);
 351 }
 352
 353 static void telnet_move_cursor(struct connection *connection, size_t pos)
 354 {
 355         struct telnet_connection *tc = connection->priv;
 356         size_t tmp;
 357
 358         if (pos == tc->line_cursor) /* nothing to do */
 359                 return;
 360
 361         if (pos > tc->line_size) /* out of bounds */
 362                 return;
 363
 364         if (pos < tc->line_cursor) {
 365                 tmp = tc->line_cursor - pos;
 366
 367                 for (size_t i = 0; i < tmp; i += 16)
 368                         telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
 369                                 MIN(tmp - i, 16));
 370         } else {
 371                 tmp = pos - tc->line_cursor;
 372
 373                 for (size_t i = 0; i < tmp; i += 16)
 374                         telnet_write(connection, tc->line + tc->line_cursor + i,
 375                                 MIN(tmp - i, 16));
 376         }
 377
 378         tc->line_cursor = pos;
 379 }
 380
 381 /* check buffer size leaving one spare character for string null termination */
 382 static inline bool telnet_can_insert(struct connection *connection, size_t len)
 383 {
 384         struct telnet_connection *t_con = connection->priv;
 385
 386         return t_con->line_size + len < TELNET_LINE_MAX_SIZE;
 387 }
 388
 389 /* write to telnet console, and update the telnet_connection members
 390  * this function is capable of inserting in the middle of a line
 391  * please ensure that data does not contain special characters (\n, \r, \t, \b ...)
 392  *
 393  * returns false when it fails to insert the requested data
 394  */
 395 static bool telnet_insert(struct connection *connection, const void *data, size_t len)
 396 {
 397         struct telnet_connection *t_con = connection->priv;
 398
 399         if (!telnet_can_insert(connection, len)) {
 400                 telnet_bell(connection);
 401                 return false;
 402         }
 403
 404         if (t_con->line_cursor < t_con->line_size) {
 405                 /* we have some content after the cursor */
 406                 memmove(t_con->line + t_con->line_cursor + len,
 407                                 t_con->line + t_con->line_cursor,
 408                                 t_con->line_size - t_con->line_cursor);
 409         }
 410
 411         strncpy(t_con->line + t_con->line_cursor, data, len);
 412
 413         telnet_write(connection,
 414                         t_con->line + t_con->line_cursor,
 415                         t_con->line_size + len - t_con->line_cursor);
 416
 417         t_con->line_size += len;
 418         t_con->line_cursor += len;
 419
 420         for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
 421                 telnet_write(connection, "\b", 1);
 422
 423         return true;
 424 }
 425
 426 static void telnet_auto_complete(struct connection *connection)
 427 {
 428         struct telnet_connection *t_con = connection->priv;
 429         struct command_context *command_context = connection->cmd_ctx;
 430
 431         struct cmd_match {
 432                 char *cmd;
 433                 struct list_head lh;
 434         };
 435
 436         LIST_HEAD(matches);
 437
 438         /* user command sequence, either at line beginning
 439          * or we start over after these characters ';', '[', '{' */
 440         size_t seq_start = (t_con->line_cursor == 0) ? 0 : (t_con->line_cursor - 1);
 441         while (seq_start > 0) {
 442                 char c = t_con->line[seq_start];
 443                 if (c == ';' || c == '[' || c == '{') {
 444                         seq_start++;
 445                         break;
 446                 }
 447
 448                 seq_start--;
 449         }
 450
 451         /* user command position in the line, ignore leading spaces */
 452         size_t usr_cmd_pos = seq_start;
 453         while ((usr_cmd_pos < t_con->line_cursor) && isspace(t_con->line[usr_cmd_pos]))
 454                 usr_cmd_pos++;
 455
 456         /* user command length */
 457         size_t usr_cmd_len = t_con->line_cursor - usr_cmd_pos;
 458
 459         /* optimize multiple spaces in the user command,
 460          * because info commands does not tolerate multiple spaces */
 461         size_t optimized_spaces = 0;
 462         char query[usr_cmd_len + 1];
 463         for (size_t i = 0; i < usr_cmd_len; i++) {
 464                 if ((i < usr_cmd_len - 1) && isspace(t_con->line[usr_cmd_pos + i])
 465                                 && isspace(t_con->line[usr_cmd_pos + i + 1])) {
 466                         optimized_spaces++;
 467                         continue;
 468                 }
 469
 470                 query[i - optimized_spaces] = t_con->line[usr_cmd_pos + i];
 471         }
 472
 473         usr_cmd_len -= optimized_spaces;
 474         query[usr_cmd_len] = '\0';
 475
 476         /* filter commands */
 477         char *query_cmd = alloc_printf("_telnet_autocomplete_helper {%s*}", query);
 478
 479         if (!query_cmd) {
 480                 LOG_ERROR("Out of memory");
 481                 return;
 482         }
 483
 484         int retval = Jim_EvalSource(command_context->interp, __FILE__, __LINE__, query_cmd);
 485         free(query_cmd);
 486         if (retval != JIM_OK)
 487                 return;
 488
 489         Jim_Obj *list = Jim_GetResult(command_context->interp);
 490         Jim_IncrRefCount(list);
 491
 492         /* common prefix length of the matched commands */
 493         size_t common_len = 0;
 494         char *first_match = NULL; /* used to compute the common prefix length */
 495
 496         int len = Jim_ListLength(command_context->interp, list);
 497         for (int i = 0; i < len; i++) {
 498                 Jim_Obj *elem = Jim_ListGetIndex(command_context->interp, list, i);
 499                 Jim_IncrRefCount(elem);
 500
 501                 char *name = (char *)Jim_GetString(elem, NULL);
 502
 503                 /* validate the command */
 504                 bool ignore_cmd = false;
 505                 Jim_Cmd *jim_cmd = Jim_GetCommand(command_context->interp, elem, JIM_NONE);
 506
 507                 if (!jim_cmd) {
 508                         /* Why we are here? Let's ignore it! */
 509                         ignore_cmd = true;
 510                 } else if (jimcmd_is_oocd_command(jim_cmd)) {
 511                         struct command *cmd = jimcmd_privdata(jim_cmd);
 512
 513                         if (cmd && !cmd->handler && !cmd->jim_handler) {
 514                                 /* Initial part of a multi-word command. Ignore it! */
 515                                 ignore_cmd = true;
 516                         } else if (cmd && cmd->mode == COMMAND_CONFIG) {
 517                                 /* Not executable after config phase. Ignore it! */
 518                                 ignore_cmd = true;
 519                         }
 520                 }
 521
 522                 /* save the command in the prediction list */
 523                 if (!ignore_cmd) {
 524                         struct cmd_match *match = calloc(1, sizeof(struct cmd_match));
 525                         if (!match) {
 526                                 LOG_ERROR("Out of memory");
 527                                 Jim_DecrRefCount(command_context->interp, elem);
 528                                 break; /* break the for loop */
 529                         }
 530
 531                         if (list_empty(&matches)) {
 532                                 common_len = strlen(name);
 533                                 first_match = name;
 534                         } else {
 535                                 size_t new_common_len = usr_cmd_len; /* save some loops */
 536
 537                                 while (new_common_len < common_len && first_match[new_common_len] == name[new_common_len])
 538                                         new_common_len++;
 539
 540                                 common_len = new_common_len;
 541                         }
 542
 543                         match->cmd = name;
 544                         list_add_tail(&match->lh, &matches);
 545                 }
 546
 547                 Jim_DecrRefCount(command_context->interp, elem);
 548         }
 549         /* end of command filtering */
 550
 551         /* proceed with auto-completion */
 552         if (list_empty(&matches))
 553                 telnet_bell(connection);
 554         else if (common_len == usr_cmd_len && list_is_singular(&matches) && t_con->line_cursor == t_con->line_size)
 555                 telnet_insert(connection, " ", 1);
 556         else if (common_len > usr_cmd_len) {
 557                 int completion_size = common_len - usr_cmd_len;
 558                 if (telnet_insert(connection, first_match + usr_cmd_len, completion_size)) {
 559                         /* in bash this extra space is only added when the cursor in at the end of line */
 560                         if (list_is_singular(&matches) && t_con->line_cursor == t_con->line_size)
 561                                 telnet_insert(connection, " ", 1);
 562                 }
 563         } else if (!list_is_singular(&matches)) {
 564                 telnet_write(connection, "\n\r", 2);
 565
 566                 struct cmd_match *match;
 567                 list_for_each_entry(match, &matches, lh) {
 568                         telnet_write(connection, match->cmd, strlen(match->cmd));
 569                         telnet_write(connection, "\n\r", 2);
 570                 }
 571
 572                 telnet_prompt(connection);
 573                 telnet_write(connection, t_con->line, t_con->line_size);
 574
 575                 /* restore the terminal visible cursor location */
 576                 for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
 577                         telnet_write(connection, "\b", 1);
 578         }
 579
 580         /* destroy the command_list */
 581         struct cmd_match *tmp, *match;
 582         list_for_each_entry_safe(match, tmp, &matches, lh)
 583                 free(match);
 584
 585         Jim_DecrRefCount(command_context->interp, list);
 586 }
 587
 588 static int telnet_input(struct connection *connection)
 589 {
 590         int bytes_read;
 591         unsigned char buffer[TELNET_BUFFER_SIZE];
 592         unsigned char *buf_p;
 593         struct telnet_connection *t_con = connection->priv;
 594         struct command_context *command_context = connection->cmd_ctx;
 595
 596         bytes_read = connection_read(connection, buffer, TELNET_BUFFER_SIZE);
 597
 598         if (bytes_read == 0)
 599                 return ERROR_SERVER_REMOTE_CLOSED;
 600         else if (bytes_read == -1) {
 601                 LOG_ERROR("error during read: %s", strerror(errno));
 602                 return ERROR_SERVER_REMOTE_CLOSED;
 603         }
 604
 605         buf_p = buffer;
 606         while (bytes_read) {
 607                 switch (t_con->state) {
 608                         case TELNET_STATE_DATA:
 609                                 if (*buf_p == 0xff) {
 610                                         t_con->state = TELNET_STATE_IAC;
 611                                 } else {
 612                                         if (isprint(*buf_p)) {  /* printable character */
 613                                                 telnet_insert(connection, buf_p, 1);
 614                                         } else { /* non-printable */
 615                                                 if (*buf_p == 0x1b) {   /* escape */
 616                                                         t_con->state = TELNET_STATE_ESCAPE;
 617                                                         t_con->last_escape = '\x00';
 618                                                 } else if ((*buf_p == 0xd) || (*buf_p == 0xa)) { /* CR/LF */
 619                                                         int retval;
 620
 621                                                         /* skip over combinations with CR/LF and NUL characters */
 622                                                         if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) ||
 623                                                                         (*(buf_p + 1) == 0xd))) {
 624                                                                 buf_p++;
 625                                                                 bytes_read--;
 626                                                         }
 627                                                         if ((bytes_read > 1) && (*(buf_p + 1) == 0)) {
 628                                                                 buf_p++;
 629                                                                 bytes_read--;
 630                                                         }
 631                                                         t_con->line[t_con->line_size] = 0;
 632
 633                                                         telnet_write(connection, "\r\n\x00", 3);
 634
 635                                                         if (strcmp(t_con->line, "history") == 0) {
 636                                                                 retval = telnet_history_print(connection);
 637
 638                                                                 if (retval != ERROR_OK)
 639                                                                         return retval;
 640
 641                                                                 continue;
 642                                                         }
 643
 644                                                         /* save only non-blank not repeating lines in the history */
 645                                                         char *prev_line = t_con->history[(t_con->current_history > 0) ?
 646                                                                         t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
 647                                                         if (*t_con->line && (!prev_line ||
 648                                                                         strcmp(t_con->line, prev_line))) {
 649                                                                 /* if the history slot is already taken, free it */
 650                                                                 free(t_con->history[t_con->next_history]);
 651
 652                                                                 /* add line to history */
 653                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 654
 655                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 656                                                                 t_con->next_history = (t_con->next_history + 1) %
 657                                                                                 TELNET_LINE_HISTORY_SIZE;
 658
 659                                                                 /* current history line starts at the new entry */
 660                                                                 t_con->current_history =
 661                                                                                 t_con->next_history;
 662
 663                                                                 free(t_con->history[t_con->current_history]);
 664                                                                 t_con->history[t_con->current_history] = strdup("");
 665                                                         }
 666
 667                                                         t_con->line_size = 0;
 668
 669                                                         /* to suppress prompt in log callback during command execution */
 670                                                         t_con->prompt_visible = false;
 671
 672                                                         if (strcmp(t_con->line, "shutdown") == 0)
 673                                                                 telnet_save_history(t_con);
 674
 675                                                         retval = command_run_line(command_context, t_con->line);
 676
 677                                                         t_con->line_cursor = 0;
 678                                                         t_con->prompt_visible = true;
 679
 680                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 681                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 682
 683                                                         /* the prompt is always * placed at the line beginning */
 684                                                         telnet_write(connection, "\r", 1);
 685
 686                                                         retval = telnet_prompt(connection);
 687                                                         if (retval == ERROR_SERVER_REMOTE_CLOSED)
 688                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 689
 690                                                 } else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) {       /* delete character */
 691                                                         if (t_con->line_cursor > 0) {
 692                                                                 if (t_con->line_cursor != t_con->line_size) {
 693                                                                         size_t i;
 694                                                                         telnet_write(connection, "\b", 1);
 695                                                                         t_con->line_cursor--;
 696                                                                         t_con->line_size--;
 697                                                                         memmove(t_con->line + t_con->line_cursor,
 698                                                                                         t_con->line + t_con->line_cursor + 1,
 699                                                                                         t_con->line_size -
 700                                                                                         t_con->line_cursor);
 701
 702                                                                         telnet_write(connection,
 703                                                                                         t_con->line + t_con->line_cursor,
 704                                                                                         t_con->line_size -
 705                                                                                         t_con->line_cursor);
 706                                                                         telnet_write(connection, " \b", 2);
 707                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 708                                                                                 telnet_write(connection, "\b", 1);
 709                                                                 } else {
 710                                                                         t_con->line_size--;
 711                                                                         t_con->line_cursor--;
 712                                                                         /* back space: move the 'printer' head one char
 713                                                                          * back, overwrite with space, move back again */
 714                                                                         telnet_write(connection, "\b \b", 3);
 715                                                                 }
 716                                                         }
 717                                                 } else if (*buf_p == 0x15) {    /* clear line */
 718                                                         telnet_clear_line(connection, t_con);
 719                                                 } else if (*buf_p == CTRL('B')) {       /* cursor left */
 720                                                         if (t_con->line_cursor > 0) {
 721                                                                 telnet_write(connection, "\b", 1);
 722                                                                 t_con->line_cursor--;
 723                                                         }
 724                                                         t_con->state = TELNET_STATE_DATA;
 725                                                 } else if (*buf_p == CTRL('C')) {       /* interrupt */
 726                                                         /* print '^C' at line end, and display a new command prompt */
 727                                                         telnet_move_cursor(connection, t_con->line_size);
 728                                                         telnet_write(connection, "^C\n\r", 4);
 729                                                         t_con->line_cursor = 0;
 730                                                         t_con->line_size = 0;
 731                                                         telnet_prompt(connection);
 732                                                 } else if (*buf_p == CTRL('F')) {       /* cursor right */
 733                                                         if (t_con->line_cursor < t_con->line_size)
 734                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 735                                                         t_con->state = TELNET_STATE_DATA;
 736                                                 } else if (*buf_p == CTRL('P')) {       /* cursor up */
 737                                                         telnet_history_up(connection);
 738                                                 } else if (*buf_p == CTRL('N')) {       /* cursor down */
 739                                                         telnet_history_down(connection);
 740                                                 } else if (*buf_p == CTRL('A')) {       /* move the cursor to the beginning of the line */
 741                                                         telnet_move_cursor(connection, 0);
 742                                                 } else if (*buf_p == CTRL('E')) {       /* move the cursor to the end of the line */
 743                                                         telnet_move_cursor(connection, t_con->line_size);
 744                                                 } else if (*buf_p == CTRL('K')) {       /* kill line to end */
 745                                                         if (t_con->line_cursor < t_con->line_size) {
 746                                                                 /* overwrite with space, until end of line, move back */
 747                                                                 for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
 748                                                                         telnet_write(connection, " ", 1);
 749                                                                 for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
 750                                                                         telnet_write(connection, "\b", 1);
 751                                                                 t_con->line[t_con->line_cursor] = '\0';
 752                                                                 t_con->line_size = t_con->line_cursor;
 753                                                         }
 754                                                 } else if (*buf_p == '\t') {
 755                                                         telnet_auto_complete(connection);
 756                                                 } else {
 757                                                         LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 758                                                 }
 759                                         }
 760                                 }
 761                                 break;
 762                         case TELNET_STATE_IAC:
 763                                 switch (*buf_p) {
 764                                 case 0xfe:
 765                                         t_con->state = TELNET_STATE_DONT;
 766                                         break;
 767                                 case 0xfd:
 768                                         t_con->state = TELNET_STATE_DO;
 769                                         break;
 770                                 case 0xfc:
 771                                         t_con->state = TELNET_STATE_WONT;
 772                                         break;
 773                                 case 0xfb:
 774                                         t_con->state = TELNET_STATE_WILL;
 775                                         break;
 776                                 }
 777                                 break;
 778                         case TELNET_STATE_SB:
 779                                 break;
 780                         case TELNET_STATE_SE:
 781                                 break;
 782                         case TELNET_STATE_WILL:
 783                         case TELNET_STATE_WONT:
 784                         case TELNET_STATE_DO:
 785                         case TELNET_STATE_DONT:
 786                                 t_con->state = TELNET_STATE_DATA;
 787                                 break;
 788                         case TELNET_STATE_ESCAPE:
 789                                 if (t_con->last_escape == '[') {
 790                                         if (*buf_p == 'D') {    /* cursor left */
 791                                                 if (t_con->line_cursor > 0) {
 792                                                         telnet_write(connection, "\b", 1);
 793                                                         t_con->line_cursor--;
 794                                                 }
 795                                                 t_con->state = TELNET_STATE_DATA;
 796                                         } else if (*buf_p == 'C') {     /* cursor right */
 797                                                 if (t_con->line_cursor < t_con->line_size)
 798                                                         telnet_write(connection,
 799                                                                         t_con->line + t_con->line_cursor++, 1);
 800                                                 t_con->state = TELNET_STATE_DATA;
 801                                         } else if (*buf_p == 'A') {     /* cursor up */
 802                                                 telnet_history_up(connection);
 803                                         } else if (*buf_p == 'B') {     /* cursor down */
 804                                                 telnet_history_down(connection);
 805                                         } else if (*buf_p == 'F') { /* end key */
 806                                                 telnet_move_cursor(connection, t_con->line_size);
 807                                                 t_con->state = TELNET_STATE_DATA;
 808                                         } else if (*buf_p == 'H') { /* home key */
 809                                                 telnet_move_cursor(connection, 0);
 810                                                 t_con->state = TELNET_STATE_DATA;
 811                                         } else if (*buf_p == '3') {
 812                                                 t_con->last_escape = *buf_p;
 813                                         } else {
 814                                                 t_con->state = TELNET_STATE_DATA;
 815                                         }
 816                                 } else if (t_con->last_escape == '3') {
 817                                         /* Remove character */
 818                                         if (*buf_p == '~') {
 819                                                 if (t_con->line_cursor < t_con->line_size) {
 820                                                         size_t i;
 821                                                         t_con->line_size--;
 822                                                         /* remove char from line buffer */
 823                                                         memmove(t_con->line + t_con->line_cursor,
 824                                                                         t_con->line + t_con->line_cursor + 1,
 825                                                                         t_con->line_size - t_con->line_cursor);
 826
 827                                                         /* print remainder of buffer */
 828                                                         telnet_write(connection, t_con->line + t_con->line_cursor,
 829                                                                         t_con->line_size - t_con->line_cursor);
 830                                                         /* overwrite last char with whitespace */
 831                                                         telnet_write(connection, " \b", 2);
 832
 833                                                         /* move back to cursor position*/
 834                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 835                                                                 telnet_write(connection, "\b", 1);
 836                                                 }
 837
 838                                                 t_con->state = TELNET_STATE_DATA;
 839                                         } else
 840                                                 t_con->state = TELNET_STATE_DATA;
 841                                 } else if (t_con->last_escape == '\x00') {
 842                                         if (*buf_p == '[')
 843                                                 t_con->last_escape = *buf_p;
 844                                         else
 845                                                 t_con->state = TELNET_STATE_DATA;
 846                                 } else {
 847                                         LOG_ERROR("BUG: unexpected value in t_con->last_escape");
 848                                         t_con->state = TELNET_STATE_DATA;
 849                                 }
 850
 851                                 break;
 852                         default:
 853                                 LOG_ERROR("unknown telnet state");
 854                                 return ERROR_FAIL;
 855                 }
 856
 857                 bytes_read--;
 858                 buf_p++;
 859         }
 860
 861         return ERROR_OK;
 862 }
 863
 864 static int telnet_connection_closed(struct connection *connection)
 865 {
 866         struct telnet_connection *t_con = connection->priv;
 867         int i;
 868
 869         log_remove_callback(telnet_log_callback, connection);
 870
 871         free(t_con->prompt);
 872         t_con->prompt = NULL;
 873
 874         /* save telnet history */
 875         telnet_save_history(t_con);
 876
 877         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++) {
 878                 free(t_con->history[i]);
 879                 t_con->history[i] = NULL;
 880         }
 881
 882         /* if this connection registered a debug-message receiver delete it */
 883         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 884
 885         free(connection->priv);
 886         connection->priv = NULL;
 887
 888         return ERROR_OK;
 889 }
 890
 891 int telnet_init(char *banner)
 892 {
 893         if (strcmp(telnet_port, "disabled") == 0) {
 894                 LOG_INFO("telnet server disabled");
 895                 return ERROR_OK;
 896         }
 897
 898         struct telnet_service *telnet_service =
 899                 malloc(sizeof(struct telnet_service));
 900
 901         if (!telnet_service) {
 902                 LOG_ERROR("Failed to allocate telnet service.");
 903                 return ERROR_FAIL;
 904         }
 905
 906         telnet_service->banner = banner;
 907
 908         int ret = add_service("telnet", telnet_port, CONNECTION_LIMIT_UNLIMITED,
 909                 telnet_new_connection, telnet_input, telnet_connection_closed,
 910                 telnet_service);
 911
 912         if (ret != ERROR_OK) {
 913                 free(telnet_service);
 914                 return ret;
 915         }
 916
 917         return ERROR_OK;
 918 }
 919
 920 /* daemon configuration command telnet_port */
 921 COMMAND_HANDLER(handle_telnet_port_command)
 922 {
 923         return CALL_COMMAND_HANDLER(server_pipe_command, &telnet_port);
 924 }
 925
 926 COMMAND_HANDLER(handle_exit_command)
 927 {
 928         return ERROR_COMMAND_CLOSE_CONNECTION;
 929 }
 930
 931 static const struct command_registration telnet_command_handlers[] = {
 932         {
 933                 .name = "exit",
 934                 .handler = handle_exit_command,
 935                 .mode = COMMAND_EXEC,
 936                 .usage = "",
 937                 .help = "exit telnet session",
 938         },
 939         {
 940                 .name = "telnet_port",
 941                 .handler = handle_telnet_port_command,
 942                 .mode = COMMAND_CONFIG,
 943                 .help = "Specify port on which to listen "
 944                         "for incoming telnet connections.  "
 945                         "Read help on 'gdb_port'.",
 946                 .usage = "[port_num]",
 947         },
 948         COMMAND_REGISTRATION_DONE
 949 };
 950
 951 int telnet_register_commands(struct command_context *cmd_ctx)
 952 {
 953         telnet_port = strdup("4444");
 954         return register_commands(cmd_ctx, NULL, telnet_command_handlers);
 955 }
 956
 957 void telnet_service_free(void)
 958 {
 959         free(telnet_port);
 960 }