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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, 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, char* line)
  79 {
  80
  81         /* process lines in buffer */
  82         char *p=line;
  83         do {
  84                 char *next = strchr(p, '\n');
  85
  86                 if (next)
  87                         *next++ = 0;
  88
  89
  90                 telnet_write(connection, p, strlen(p));
  91                 if (next)
  92                 {
  93                         telnet_write(connection, "\r\n\0", 3);
  94                 }
  95
  96                 p = next;
  97         } while (p);
  98
  99         return ERROR_OK;
 100 }
 101
 102 int telnet_output(struct command_context_s *cmd_ctx, char* line)
 103 {
 104         connection_t *connection = cmd_ctx->output_handler_priv;
 105
 106         return telnet_outputline(connection, line);
 107 }
 108
 109 void telnet_log_callback(void *priv, const char *file, int line,
 110                 const char *function, const char *format, va_list args)
 111 {
 112         connection_t *connection = priv;
 113         char *t = alloc_printf(format, args);
 114         if (t == NULL)
 115                 return;
 116         telnet_outputline(connection, t);
 117
 118         free(t);
 119 }
 120
 121 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
 122 {
 123         struct command_context_s *cmd_ctx = priv;
 124         connection_t *connection = cmd_ctx->output_handler_priv;
 125         telnet_connection_t *t_con = connection->priv;
 126
 127         switch (event)
 128         {
 129                 case TARGET_EVENT_HALTED:
 130                         target_arch_state(target);
 131                         if (!t_con->suppress_prompt)
 132                                 telnet_prompt(connection);
 133                         break;
 134                 case TARGET_EVENT_RESUMED:
 135                         if (!t_con->suppress_prompt)
 136                                 telnet_prompt(connection);
 137                         break;
 138                 default:
 139                         break;
 140         }
 141
 142         return ERROR_OK;
 143 }
 144
 145 int telnet_new_connection(connection_t *connection)
 146 {
 147         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 148         telnet_service_t *telnet_service = connection->service->priv;
 149         int i;
 150
 151         connection->priv = telnet_connection;
 152
 153         /* initialize telnet connection information */
 154         telnet_connection->closed = 0;
 155         telnet_connection->line_size = 0;
 156         telnet_connection->line_cursor = 0;
 157         telnet_connection->option_size = 0;
 158         telnet_connection->prompt = strdup("> ");
 159         telnet_connection->suppress_prompt = 0;
 160         telnet_connection->state = TELNET_STATE_DATA;
 161
 162         /* output goes through telnet connection */
 163         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 164
 165         /* negotiate telnet options */
 166         telnet_write(connection, negotiate, strlen(negotiate));
 167
 168         /* print connection banner */
 169         if (telnet_service->banner)
 170         {
 171                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 172                 telnet_write(connection, "\r\n\0", 3);
 173         }
 174
 175         telnet_prompt(connection);
 176
 177         /* initialize history */
 178         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 179         {
 180                 telnet_connection->history[i] = NULL;
 181         }
 182         telnet_connection->next_history = 0;
 183         telnet_connection->current_history = 0;
 184
 185         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 186
 187         return ERROR_OK;
 188 }
 189
 190 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 191 {
 192         /* move to end of line */
 193         if (t_con->line_cursor < t_con->line_size)
 194         {
 195                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 196         }
 197
 198         /* backspace, overwrite with space, backspace */
 199         while (t_con->line_size > 0)
 200         {
 201                 telnet_write(connection, "\b \b", 3);
 202                 t_con->line_size--;
 203         }
 204         t_con->line_cursor = 0;
 205 }
 206
 207 int telnet_input(connection_t *connection)
 208 {
 209         int bytes_read;
 210         char buffer[TELNET_BUFFER_SIZE];
 211         char *buf_p;
 212         telnet_connection_t *t_con = connection->priv;
 213         command_context_t *command_context = connection->cmd_ctx;
 214
 215         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 216
 217         if (bytes_read == 0)
 218                 return ERROR_SERVER_REMOTE_CLOSED;
 219         else if (bytes_read == -1)
 220         {
 221                 ERROR("error during read: %s", strerror(errno));
 222                 return ERROR_SERVER_REMOTE_CLOSED;
 223         }
 224
 225         buf_p = buffer;
 226         while (bytes_read)
 227         {
 228                 switch (t_con->state)
 229                 {
 230                         case TELNET_STATE_DATA:
 231                                 if (*buf_p == '\xff')
 232                                 {
 233                                         t_con->state = TELNET_STATE_IAC;
 234                                 }
 235                                 else
 236                                 {
 237                                         if (isprint(*buf_p)) /* printable character */
 238                                         {
 239                                                 telnet_write(connection, buf_p, 1);
 240                                                 if (t_con->line_cursor == t_con->line_size)
 241                                                 {
 242                                                         t_con->line[t_con->line_size++] = *buf_p;
 243                                                         t_con->line_cursor++;
 244                                                 }
 245                                                 else
 246                                                 {
 247                                                         int i;
 248                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 249                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 250                                                         t_con->line_size++;
 251                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 252                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 253                                                         {
 254                                                                 telnet_write(connection, "\b", 1);
 255                                                         }
 256                                                 }
 257                                         }
 258                                         else /* non-printable */
 259                                         {
 260                                                 if (*buf_p == 0x1b) /* escape */
 261                                                 {
 262                                                         t_con->state = TELNET_STATE_ESCAPE;
 263                                                         t_con->last_escape = '\x00';
 264                                                 }
 265                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 266                                                 {
 267                                                         int retval;
 268
 269                                                         /* skip over combinations with CR/LF + NUL */
 270                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 271                                                         {
 272                                                                 buf_p++;
 273                                                                 bytes_read--;
 274                                                         }
 275                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 276                                                         {
 277                                                                 buf_p++;
 278                                                                 bytes_read--;
 279                                                         }
 280                                                         t_con->line[t_con->line_size] = 0;
 281
 282                                                         telnet_write(connection, "\r\n\x00", 3);
 283
 284                                                         if (strcmp(t_con->line, "history") == 0)
 285                                                         {
 286                                                                 int i;
 287                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 288                                                                 {
 289                                                                         if (t_con->history[i])
 290                                                                         {
 291                                                                                 telnet_write(connection, t_con->history[i], strlen(t_con->history[i]));
 292                                                                                 telnet_write(connection, "\r\n\x00", 3);
 293                                                                         }
 294                                                                 }
 295                                                                 telnet_prompt(connection);
 296                                                                 t_con->line_size = 0;
 297                                                                 t_con->line_cursor = 0;
 298                                                                 continue;
 299                                                         }
 300
 301                                                         log_add_callback(telnet_log_callback, connection);
 302                                                         t_con->suppress_prompt = 1;
 303
 304                                                         retval = command_run_line(command_context, t_con->line);
 305
 306                                                         log_remove_callback(telnet_log_callback, connection);
 307                                                         t_con->suppress_prompt = 0;
 308
 309                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 310                                                         {
 311                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 312                                                         }
 313
 314                                                         /* Save only non-blank lines in the history */
 315                                                         if (t_con->line_size > 0)
 316                                                         {
 317                                                                 /* if the history slot is already taken, free it */
 318                                                                 if (t_con->history[t_con->next_history])
 319                                                                 {
 320                                                                         free(t_con->history[t_con->next_history]);
 321                                                                 }
 322
 323                                                                 /* add line to history */
 324                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 325
 326                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 327                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 328
 329                                                                 /* current history line starts at the new entry */
 330                                                                 t_con->current_history = t_con->next_history;
 331
 332                                                                 if (t_con->history[t_con->current_history])
 333                                                                 {
 334                                                                         free(t_con->history[t_con->current_history]);
 335                                                                 }
 336                                                                 t_con->history[t_con->current_history] = strdup("");
 337                                                         }
 338
 339                                                         int t = telnet_prompt(connection);
 340                                                         if (t == ERROR_SERVER_REMOTE_CLOSED)
 341                                                                 return t;
 342
 343                                                         t_con->line_size = 0;
 344                                                         t_con->line_cursor = 0;
 345                                                 }
 346                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 347                                                 {
 348                                                         if (t_con->line_cursor > 0)
 349                                                         {
 350                                                                 if (t_con->line_cursor != t_con->line_size)
 351                                                                 {
 352                                                                         int i;
 353                                                                         telnet_write(connection, "\b", 1);
 354                                                                         t_con->line_cursor--;
 355                                                                         t_con->line_size--;
 356                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 357
 358                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 359                                                                         telnet_write(connection, " \b", 2);
 360                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 361                                                                         {
 362                                                                                 telnet_write(connection, "\b", 1);
 363                                                                         }
 364                                                                 }
 365                                                                 else
 366                                                                 {
 367                                                                         t_con->line_size--;
 368                                                                         t_con->line_cursor--;
 369                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 370                                                                         telnet_write(connection, "\b \b", 3);
 371                                                                 }
 372                                                         }
 373                                                 }
 374                                                 else if (*buf_p == 0x15) /* clear line */
 375                                                 {
 376                                                         telnet_clear_line(connection, t_con);
 377                                                 }
 378                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 379                                                 {
 380                                                         if (t_con->line_cursor > 0)
 381                                                         {
 382                                                                 telnet_write(connection, "\b", 1);
 383                                                                 t_con->line_cursor--;
 384                                                         }
 385                                                         t_con->state = TELNET_STATE_DATA;
 386                                                 }
 387                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 388                                                 {
 389                                                         if (t_con->line_cursor < t_con->line_size)
 390                                                         {
 391                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 392                                                         }
 393                                                         t_con->state = TELNET_STATE_DATA;
 394                                                 }
 395                                                 else
 396                                                 {
 397                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 398                                                 }
 399                                         }
 400                                 }
 401                                 break;
 402                         case TELNET_STATE_IAC:
 403                                 switch (*buf_p)
 404                                 {
 405                                         case '\xfe':
 406                                                 t_con->state = TELNET_STATE_DONT;
 407                                                 break;
 408                                         case '\xfd':
 409                                                 t_con->state = TELNET_STATE_DO;
 410                                                 break;
 411                                         case '\xfc':
 412                                                 t_con->state = TELNET_STATE_WONT;
 413                                                 break;
 414                                         case '\xfb':
 415                                                 t_con->state = TELNET_STATE_WILL;
 416                                                 break;
 417                                 }
 418                                 break;
 419                         case TELNET_STATE_SB:
 420                                 break;
 421                         case TELNET_STATE_SE:
 422                                 break;
 423                         case TELNET_STATE_WILL:
 424                         case TELNET_STATE_WONT:
 425                         case TELNET_STATE_DO:
 426                         case TELNET_STATE_DONT:
 427                                 t_con->state = TELNET_STATE_DATA;
 428                                 break;
 429                         case TELNET_STATE_ESCAPE:
 430                                 if (t_con->last_escape == '[')
 431                                 {
 432                                         if (*buf_p == 'D') /* cursor left */
 433                                         {
 434                                                 if (t_con->line_cursor > 0)
 435                                                 {
 436                                                         telnet_write(connection, "\b", 1);
 437                                                         t_con->line_cursor--;
 438                                                 }
 439                                                 t_con->state = TELNET_STATE_DATA;
 440                                         }
 441                                         else if (*buf_p == 'C') /* cursor right */
 442                                         {
 443                                                 if (t_con->line_cursor < t_con->line_size)
 444                                                 {
 445                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 446                                                 }
 447                                                 t_con->state = TELNET_STATE_DATA;
 448                                         }
 449                                         else if (*buf_p == 'A') /* cursor up */
 450                                         {
 451                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 452                                                 if (t_con->history[last_history])
 453                                                 {
 454                                                         telnet_clear_line(connection, t_con);
 455                                                         t_con->line_size = strlen(t_con->history[last_history]);
 456                                                         t_con->line_cursor = t_con->line_size;
 457                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 458                                                         telnet_write(connection, t_con->line, t_con->line_size);
 459                                                         t_con->current_history = last_history;
 460                                                 }
 461                                                 t_con->state = TELNET_STATE_DATA;
 462                                         }
 463                                         else if (*buf_p == 'B') /* cursor down */
 464                                         {
 465                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 466                                                 if (t_con->history[next_history])
 467                                                 {
 468                                                         telnet_clear_line(connection, t_con);
 469                                                         t_con->line_size = strlen(t_con->history[next_history]);
 470                                                         t_con->line_cursor = t_con->line_size;
 471                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 472                                                         telnet_write(connection, t_con->line, t_con->line_size);
 473                                                         t_con->current_history = next_history;
 474                                                 }
 475                                                 t_con->state = TELNET_STATE_DATA;
 476                                         }
 477                                         else if (*buf_p == '3')
 478                                         {
 479                                                 t_con->last_escape = *buf_p;
 480                                         }
 481                                         else
 482                                         {
 483                                                 t_con->state = TELNET_STATE_DATA;
 484                                         }
 485                                 }
 486                                 else if (t_con->last_escape == '3')
 487                                 {
 488                                         /* Remove character */
 489                                         if (*buf_p == '~')
 490                                         {
 491                                                 if (t_con->line_cursor < t_con->line_size)
 492                                                 {
 493                                                         int i;
 494                                                         t_con->line_size--;
 495                                                         /* remove char from line buffer */
 496                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 497
 498                                                         /* print remainder of buffer */
 499                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 500                                                         /* overwrite last char with whitespace */
 501                                                         telnet_write(connection, " \b", 2);
 502
 503                                                         /* move back to cursor position*/
 504                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 505                                                         {
 506                                                                 telnet_write(connection, "\b", 1);
 507                                                         }
 508                                                 }
 509
 510                                                 t_con->state = TELNET_STATE_DATA;
 511                                         }
 512                                         else
 513                                         {
 514                                                 t_con->state = TELNET_STATE_DATA;
 515                                         }
 516                                 }
 517                                 else if (t_con->last_escape == '\x00')
 518                                 {
 519                                         if (*buf_p == '[')
 520                                         {
 521                                                 t_con->last_escape = *buf_p;
 522                                         }
 523                                         else
 524                                         {
 525                                                 t_con->state = TELNET_STATE_DATA;
 526                                         }
 527                                 }
 528                                 else
 529                                 {
 530                                         ERROR("BUG: unexpected value in t_con->last_escape");
 531                                         t_con->state = TELNET_STATE_DATA;
 532                                 }
 533
 534                                 break;
 535                         default:
 536                                 ERROR("unknown telnet state");
 537                                 exit(-1);
 538                 }
 539
 540                 bytes_read--;
 541                 buf_p++;
 542         }
 543
 544         return ERROR_OK;
 545 }
 546
 547 int telnet_connection_closed(connection_t *connection)
 548 {
 549         telnet_connection_t *t_con = connection->priv;
 550         int i;
 551
 552         if (t_con->prompt)
 553         {
 554                 free(t_con->prompt);
 555                 t_con->prompt = NULL;
 556         }
 557
 558         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 559         {
 560                 if (t_con->history[i])
 561                 {
 562                         free(t_con->history[i]);
 563                         t_con->history[i] = NULL;
 564                 }
 565         }
 566
 567         /* if this connection registered a debug-message receiver delete it */
 568         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 569
 570         if (connection->priv)
 571         {
 572                 free(connection->priv);
 573                 connection->priv = NULL;
 574         }
 575         else
 576         {
 577                 ERROR("BUG: connection->priv == NULL");
 578         }
 579
 580         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 581
 582         return ERROR_OK;
 583 }
 584
 585 int telnet_set_prompt(connection_t *connection, char *prompt)
 586 {
 587         telnet_connection_t *t_con = connection->priv;
 588
 589         t_con->prompt = strdup(prompt);
 590
 591         return ERROR_OK;
 592 }
 593
 594 int telnet_init(char *banner)
 595 {
 596         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 597
 598         if (telnet_port == 0)
 599         {
 600                 WARNING("no telnet port specified, using default port 4444");
 601                 telnet_port = 4444;
 602         }
 603
 604         telnet_service->banner = banner;
 605
 606         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 607
 608         return ERROR_OK;
 609 }
 610
 611 int telnet_register_commands(command_context_t *command_context)
 612 {
 613         register_command(command_context, NULL, "exit", handle_exit_command,
 614                                          COMMAND_EXEC, "exit telnet session");
 615
 616         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 617                                          COMMAND_CONFIG, "");
 618
 619         return ERROR_OK;
 620 }
 621
 622 /* daemon configuration command telnet_port */
 623 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 624 {
 625         if (argc == 0)
 626                 return ERROR_OK;
 627
 628         /* only if the port wasn't overwritten by cmdline */
 629         if (telnet_port == 0)
 630                 telnet_port = strtoul(args[0], NULL, 0);
 631
 632         return ERROR_OK;
 633 }
 634
 635 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 636 {
 637         return ERROR_COMMAND_CLOSE_CONNECTION;
 638 }