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