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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         switch (event)
 123         {
 124                 case TARGET_EVENT_HALTED:
 125                         target_arch_state(target);
 126                         break;
 127                 default:
 128                         break;
 129         }
 130
 131         return ERROR_OK;
 132 }
 133
 134 int telnet_new_connection(connection_t *connection)
 135 {
 136         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 137         telnet_service_t *telnet_service = connection->service->priv;
 138         int i;
 139
 140         connection->priv = telnet_connection;
 141
 142         /* initialize telnet connection information */
 143         telnet_connection->closed = 0;
 144         telnet_connection->line_size = 0;
 145         telnet_connection->line_cursor = 0;
 146         telnet_connection->option_size = 0;
 147         telnet_connection->prompt = strdup("> ");
 148         telnet_connection->state = TELNET_STATE_DATA;
 149
 150         /* output goes through telnet connection */
 151         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 152
 153         /* negotiate telnet options */
 154         telnet_write(connection, negotiate, strlen(negotiate));
 155
 156         /* print connection banner */
 157         if (telnet_service->banner)
 158         {
 159                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 160                 telnet_write(connection, "\r\n\0", 3);
 161         }
 162
 163         telnet_prompt(connection);
 164
 165         /* initialize history */
 166         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 167         {
 168                 telnet_connection->history[i] = NULL;
 169         }
 170         telnet_connection->next_history = 0;
 171         telnet_connection->current_history = 0;
 172
 173         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 174
 175         return ERROR_OK;
 176 }
 177
 178 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 179 {
 180         /* move to end of line */
 181         if (t_con->line_cursor < t_con->line_size)
 182         {
 183                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 184         }
 185
 186         /* backspace, overwrite with space, backspace */
 187         while (t_con->line_size > 0)
 188         {
 189                 telnet_write(connection, "\b \b", 3);
 190                 t_con->line_size--;
 191         }
 192         t_con->line_cursor = 0;
 193 }
 194
 195 int telnet_input(connection_t *connection)
 196 {
 197         int bytes_read;
 198         char buffer[TELNET_BUFFER_SIZE];
 199         char *buf_p;
 200         telnet_connection_t *t_con = connection->priv;
 201         command_context_t *command_context = connection->cmd_ctx;
 202
 203         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 204
 205         if (bytes_read == 0)
 206                 return ERROR_SERVER_REMOTE_CLOSED;
 207         else if (bytes_read == -1)
 208         {
 209                 ERROR("error during read: %s", strerror(errno));
 210                 return ERROR_SERVER_REMOTE_CLOSED;
 211         }
 212
 213         buf_p = buffer;
 214         while (bytes_read)
 215         {
 216                 switch (t_con->state)
 217                 {
 218                         case TELNET_STATE_DATA:
 219                                 if (*buf_p == '\xff')
 220                                 {
 221                                         t_con->state = TELNET_STATE_IAC;
 222                                 }
 223                                 else
 224                                 {
 225                                         if (isprint(*buf_p)) /* printable character */
 226                                         {
 227                                                 telnet_write(connection, buf_p, 1);
 228                                                 if (t_con->line_cursor == t_con->line_size)
 229                                                 {
 230                                                         t_con->line[t_con->line_size++] = *buf_p;
 231                                                         t_con->line_cursor++;
 232                                                 }
 233                                                 else
 234                                                 {
 235                                                         int i;
 236                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 237                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 238                                                         t_con->line_size++;
 239                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 240                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 241                                                         {
 242                                                                 telnet_write(connection, "\b", 1);
 243                                                         }
 244                                                 }
 245                                         }
 246                                         else /* non-printable */
 247                                         {
 248                                                 if (*buf_p == 0x1b) /* escape */
 249                                                 {
 250                                                         t_con->state = TELNET_STATE_ESCAPE;
 251                                                         t_con->last_escape = '\x00';
 252                                                 }
 253                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 254                                                 {
 255                                                         int retval;
 256
 257                                                         /* skip over combinations with CR/LF + NUL */
 258                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 259                                                         {
 260                                                                 buf_p++;
 261                                                                 bytes_read--;
 262                                                         }
 263                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 264                                                         {
 265                                                                 buf_p++;
 266                                                                 bytes_read--;
 267                                                         }
 268                                                         t_con->line[t_con->line_size] = 0;
 269
 270                                                         telnet_write(connection, "\r\n\x00", 3);
 271
 272                                                         if (strcmp(t_con->line, "history") == 0)
 273                                                         {
 274                                                                 int i;
 275                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 276                                                                 {
 277                                                                         if (t_con->history[i])
 278                                                                         {
 279                                                                                 telnet_write(connection, t_con->history[i], strlen(t_con->history[i]));
 280                                                                                 telnet_write(connection, "\r\n\x00", 3);
 281                                                                         }
 282                                                                 }
 283                                                                 telnet_prompt(connection);
 284                                                                 t_con->line_size = 0;
 285                                                                 t_con->line_cursor = 0;
 286                                                                 continue;
 287                                                         }
 288
 289                                                         log_add_callback(telnet_log_callback, connection);
 290
 291                                                         retval = command_run_line(command_context, t_con->line);
 292
 293                                                         log_remove_callback(telnet_log_callback, connection);
 294
 295                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 296                                                         {
 297                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 298                                                         }
 299
 300                                                         /* Save only non-blank lines in the history */
 301                                                         if (t_con->line_size > 0)
 302                                                         {
 303                                                                 /* if the history slot is already taken, free it */
 304                                                                 if (t_con->history[t_con->next_history])
 305                                                                 {
 306                                                                         free(t_con->history[t_con->next_history]);
 307                                                                 }
 308
 309                                                                 /* add line to history */
 310                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 311
 312                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 313                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 314
 315                                                                 /* current history line starts at the new entry */
 316                                                                 t_con->current_history = t_con->next_history;
 317
 318                                                                 if (t_con->history[t_con->current_history])
 319                                                                 {
 320                                                                         free(t_con->history[t_con->current_history]);
 321                                                                 }
 322                                                                 t_con->history[t_con->current_history] = strdup("");
 323                                                         }
 324
 325                                                         int t = telnet_prompt(connection);
 326                                                         if (t == ERROR_SERVER_REMOTE_CLOSED)
 327                                                                 return t;
 328
 329                                                         t_con->line_size = 0;
 330                                                         t_con->line_cursor = 0;
 331                                                 }
 332                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 333                                                 {
 334                                                         if (t_con->line_cursor > 0)
 335                                                         {
 336                                                                 if (t_con->line_cursor != t_con->line_size)
 337                                                                 {
 338                                                                         int i;
 339                                                                         telnet_write(connection, "\b", 1);
 340                                                                         t_con->line_cursor--;
 341                                                                         t_con->line_size--;
 342                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 343
 344                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 345                                                                         telnet_write(connection, " \b", 2);
 346                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 347                                                                         {
 348                                                                                 telnet_write(connection, "\b", 1);
 349                                                                         }
 350                                                                 }
 351                                                                 else
 352                                                                 {
 353                                                                         t_con->line_size--;
 354                                                                         t_con->line_cursor--;
 355                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 356                                                                         telnet_write(connection, "\b \b", 3);
 357                                                                 }
 358                                                         }
 359                                                 }
 360                                                 else if (*buf_p == 0x15) /* clear line */
 361                                                 {
 362                                                         telnet_clear_line(connection, t_con);
 363                                                 }
 364                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 365                                                 {
 366                                                         if (t_con->line_cursor > 0)
 367                                                         {
 368                                                                 telnet_write(connection, "\b", 1);
 369                                                                 t_con->line_cursor--;
 370                                                         }
 371                                                         t_con->state = TELNET_STATE_DATA;
 372                                                 }
 373                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 374                                                 {
 375                                                         if (t_con->line_cursor < t_con->line_size)
 376                                                         {
 377                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 378                                                         }
 379                                                         t_con->state = TELNET_STATE_DATA;
 380                                                 }
 381                                                 else
 382                                                 {
 383                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 384                                                 }
 385                                         }
 386                                 }
 387                                 break;
 388                         case TELNET_STATE_IAC:
 389                                 switch (*buf_p)
 390                                 {
 391                                         case '\xfe':
 392                                                 t_con->state = TELNET_STATE_DONT;
 393                                                 break;
 394                                         case '\xfd':
 395                                                 t_con->state = TELNET_STATE_DO;
 396                                                 break;
 397                                         case '\xfc':
 398                                                 t_con->state = TELNET_STATE_WONT;
 399                                                 break;
 400                                         case '\xfb':
 401                                                 t_con->state = TELNET_STATE_WILL;
 402                                                 break;
 403                                 }
 404                                 break;
 405                         case TELNET_STATE_SB:
 406                                 break;
 407                         case TELNET_STATE_SE:
 408                                 break;
 409                         case TELNET_STATE_WILL:
 410                         case TELNET_STATE_WONT:
 411                         case TELNET_STATE_DO:
 412                         case TELNET_STATE_DONT:
 413                                 t_con->state = TELNET_STATE_DATA;
 414                                 break;
 415                         case TELNET_STATE_ESCAPE:
 416                                 if (t_con->last_escape == '[')
 417                                 {
 418                                         if (*buf_p == 'D') /* cursor left */
 419                                         {
 420                                                 if (t_con->line_cursor > 0)
 421                                                 {
 422                                                         telnet_write(connection, "\b", 1);
 423                                                         t_con->line_cursor--;
 424                                                 }
 425                                                 t_con->state = TELNET_STATE_DATA;
 426                                         }
 427                                         else if (*buf_p == 'C') /* cursor right */
 428                                         {
 429                                                 if (t_con->line_cursor < t_con->line_size)
 430                                                 {
 431                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 432                                                 }
 433                                                 t_con->state = TELNET_STATE_DATA;
 434                                         }
 435                                         else if (*buf_p == 'A') /* cursor up */
 436                                         {
 437                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 438                                                 if (t_con->history[last_history])
 439                                                 {
 440                                                         telnet_clear_line(connection, t_con);
 441                                                         t_con->line_size = strlen(t_con->history[last_history]);
 442                                                         t_con->line_cursor = t_con->line_size;
 443                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 444                                                         telnet_write(connection, t_con->line, t_con->line_size);
 445                                                         t_con->current_history = last_history;
 446                                                 }
 447                                                 t_con->state = TELNET_STATE_DATA;
 448                                         }
 449                                         else if (*buf_p == 'B') /* cursor down */
 450                                         {
 451                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 452                                                 if (t_con->history[next_history])
 453                                                 {
 454                                                         telnet_clear_line(connection, t_con);
 455                                                         t_con->line_size = strlen(t_con->history[next_history]);
 456                                                         t_con->line_cursor = t_con->line_size;
 457                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 458                                                         telnet_write(connection, t_con->line, t_con->line_size);
 459                                                         t_con->current_history = next_history;
 460                                                 }
 461                                                 t_con->state = TELNET_STATE_DATA;
 462                                         }
 463                                         else if (*buf_p == '3')
 464                                         {
 465                                                 t_con->last_escape = *buf_p;
 466                                         }
 467                                         else
 468                                         {
 469                                                 t_con->state = TELNET_STATE_DATA;
 470                                         }
 471                                 }
 472                                 else if (t_con->last_escape == '3')
 473                                 {
 474                                         /* Remove character */
 475                                         if (*buf_p == '~')
 476                                         {
 477                                                 if (t_con->line_cursor < t_con->line_size)
 478                                                 {
 479                                                         int i;
 480                                                         t_con->line_size--;
 481                                                         /* remove char from line buffer */
 482                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 483
 484                                                         /* print remainder of buffer */
 485                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 486                                                         /* overwrite last char with whitespace */
 487                                                         telnet_write(connection, " \b", 2);
 488
 489                                                         /* move back to cursor position*/
 490                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 491                                                         {
 492                                                                 telnet_write(connection, "\b", 1);
 493                                                         }
 494                                                 }
 495
 496                                                 t_con->state = TELNET_STATE_DATA;
 497                                         }
 498                                         else
 499                                         {
 500                                                 t_con->state = TELNET_STATE_DATA;
 501                                         }
 502                                 }
 503                                 else if (t_con->last_escape == '\x00')
 504                                 {
 505                                         if (*buf_p == '[')
 506                                         {
 507                                                 t_con->last_escape = *buf_p;
 508                                         }
 509                                         else
 510                                         {
 511                                                 t_con->state = TELNET_STATE_DATA;
 512                                         }
 513                                 }
 514                                 else
 515                                 {
 516                                         ERROR("BUG: unexpected value in t_con->last_escape");
 517                                         t_con->state = TELNET_STATE_DATA;
 518                                 }
 519
 520                                 break;
 521                         default:
 522                                 ERROR("unknown telnet state");
 523                                 exit(-1);
 524                 }
 525
 526                 bytes_read--;
 527                 buf_p++;
 528         }
 529
 530         return ERROR_OK;
 531 }
 532
 533 int telnet_connection_closed(connection_t *connection)
 534 {
 535         telnet_connection_t *t_con = connection->priv;
 536         int i;
 537
 538         if (t_con->prompt)
 539         {
 540                 free(t_con->prompt);
 541                 t_con->prompt = NULL;
 542         }
 543
 544         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 545         {
 546                 if (t_con->history[i])
 547                 {
 548                         free(t_con->history[i]);
 549                         t_con->history[i] = NULL;
 550                 }
 551         }
 552
 553         /* if this connection registered a debug-message receiver delete it */
 554         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 555
 556         if (connection->priv)
 557         {
 558                 free(connection->priv);
 559                 connection->priv = NULL;
 560         }
 561         else
 562         {
 563                 ERROR("BUG: connection->priv == NULL");
 564         }
 565
 566         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 567
 568         return ERROR_OK;
 569 }
 570
 571 int telnet_set_prompt(connection_t *connection, char *prompt)
 572 {
 573         telnet_connection_t *t_con = connection->priv;
 574
 575         t_con->prompt = strdup(prompt);
 576
 577         return ERROR_OK;
 578 }
 579
 580 int telnet_init(char *banner)
 581 {
 582         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 583
 584         if (telnet_port == 0)
 585         {
 586                 WARNING("no telnet port specified, using default port 4444");
 587                 telnet_port = 4444;
 588         }
 589
 590         telnet_service->banner = banner;
 591
 592         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 593
 594         return ERROR_OK;
 595 }
 596
 597 int telnet_register_commands(command_context_t *command_context)
 598 {
 599         register_command(command_context, NULL, "exit", handle_exit_command,
 600                                          COMMAND_EXEC, "exit telnet session");
 601
 602         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 603                                          COMMAND_CONFIG, "");
 604
 605         return ERROR_OK;
 606 }
 607
 608 /* daemon configuration command telnet_port */
 609 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 610 {
 611         if (argc == 0)
 612                 return ERROR_OK;
 613
 614         telnet_port = strtoul(args[0], NULL, 0);
 615
 616         return ERROR_OK;
 617 }
 618
 619 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 620 {
 621         return ERROR_COMMAND_CLOSE_CONNECTION;
 622 }