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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 void telnet_prompt(connection_t *connection)
  54 {
  55         telnet_connection_t *t_con = connection->priv;
  56
  57         write_socket(connection->fd, t_con->prompt, strlen(t_con->prompt));
  58 }
  59
  60 int telnet_output(struct command_context_s *cmd_ctx, char* line)
  61 {
  62         connection_t *connection = cmd_ctx->output_handler_priv;
  63
  64         write_socket(connection->fd, line, strlen(line));
  65         write_socket(connection->fd, "\r\n\0", 3);
  66
  67         return ERROR_OK;
  68 }
  69
  70 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
  71 {
  72         struct command_context_s *cmd_ctx = priv;
  73         char buffer[512];
  74
  75         switch (event)
  76         {
  77                 case TARGET_EVENT_HALTED:
  78                         command_print(cmd_ctx, "Target %i halted", get_num_by_target(target));
  79                         target->type->arch_state(target, buffer, 512);
  80                         buffer[511] = 0;
  81                         command_print(cmd_ctx, "%s", buffer);
  82                         break;
  83                 case TARGET_EVENT_RESUMED:
  84                         command_print(cmd_ctx, "Target %i resumed", get_num_by_target(target));
  85                         break;
  86                 default:
  87                         break;
  88         }
  89
  90         return ERROR_OK;
  91 }
  92
  93 int telnet_new_connection(connection_t *connection)
  94 {
  95         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
  96         telnet_service_t *telnet_service = connection->service->priv;
  97         int i;
  98
  99         connection->priv = telnet_connection;
 100
 101         /* initialize telnet connection information */
 102         telnet_connection->line_size = 0;
 103         telnet_connection->line_cursor = 0;
 104         telnet_connection->option_size = 0;
 105         telnet_connection->prompt = strdup("> ");
 106         telnet_connection->state = TELNET_STATE_DATA;
 107
 108         /* output goes through telnet connection */
 109         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 110
 111         /* negotiate telnet options */
 112         write_socket(connection->fd, negotiate, strlen(negotiate));
 113
 114         /* print connection banner */
 115         if (telnet_service->banner)
 116         {
 117                 write_socket(connection->fd, telnet_service->banner, strlen(telnet_service->banner));
 118                 write_socket(connection->fd, "\r\n\0", 3);
 119         }
 120
 121         telnet_prompt(connection);
 122
 123         /* initialize history */
 124         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 125         {
 126                 telnet_connection->history[i] = NULL;
 127         }
 128         telnet_connection->next_history = 0;
 129         telnet_connection->current_history = 0;
 130
 131         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 132
 133         return ERROR_OK;
 134 }
 135
 136 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 137 {
 138         /* move to end of line */
 139         if (t_con->line_cursor < t_con->line_size)
 140         {
 141                 write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 142         }
 143
 144         /* backspace, overwrite with space, backspace */
 145         while (t_con->line_size > 0)
 146         {
 147                 write_socket(connection->fd, "\b \b", 3);
 148                 t_con->line_size--;
 149         }
 150         t_con->line_cursor = 0;
 151 }
 152
 153 int telnet_input(connection_t *connection)
 154 {
 155         int bytes_read;
 156         char buffer[TELNET_BUFFER_SIZE];
 157         char *buf_p;
 158         telnet_connection_t *t_con = connection->priv;
 159         command_context_t *command_context = connection->cmd_ctx;
 160
 161         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 162
 163         if (bytes_read == 0)
 164                 return ERROR_SERVER_REMOTE_CLOSED;
 165         else if (bytes_read == -1)
 166         {
 167                 ERROR("error during read: %s", strerror(errno));
 168                 return ERROR_SERVER_REMOTE_CLOSED;
 169         }
 170
 171         buf_p = buffer;
 172         while (bytes_read)
 173         {
 174                 switch (t_con->state)
 175                 {
 176                         case TELNET_STATE_DATA:
 177                                 if (*buf_p == '\xff')
 178                                 {
 179                                         t_con->state = TELNET_STATE_IAC;
 180                                 }
 181                                 else
 182                                 {
 183                                         if (isprint(*buf_p)) /* printable character */
 184                                         {
 185                                                 write_socket(connection->fd, buf_p, 1);
 186                                                 if (t_con->line_cursor == t_con->line_size)
 187                                                 {
 188                                                         t_con->line[t_con->line_size++] = *buf_p;
 189                                                         t_con->line_cursor++;
 190                                                 }
 191                                                 else
 192                                                 {
 193                                                         int i;
 194                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 195                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 196                                                         t_con->line_size++;
 197                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 198                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 199                                                         {
 200                                                                 write_socket(connection->fd, "\b", 1);
 201                                                         }
 202                                                 }
 203                                         }
 204                                         else /* non-printable */
 205                                         {
 206                                                 if (*buf_p == 0x1b) /* escape */
 207                                                 {
 208                                                         t_con->state = TELNET_STATE_ESCAPE;
 209                                                         t_con->last_escape = '\x00';
 210                                                 }
 211                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 212                                                 {
 213                                                         int retval;
 214
 215                                                         /* skip over combinations with CR/LF + NUL */
 216                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 217                                                         {
 218                                                                 buf_p++;
 219                                                                 bytes_read--;
 220                                                         }
 221                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 222                                                         {
 223                                                                 buf_p++;
 224                                                                 bytes_read--;
 225                                                         }
 226                                                         t_con->line[t_con->line_size] = 0;
 227
 228                                                         write_socket(connection->fd, "\r\n\x00", 3);
 229
 230                                                         if (strcmp(t_con->line, "history") == 0)
 231                                                         {
 232                                                                 int i;
 233                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 234                                                                 {
 235                                                                         if (t_con->history[i])
 236                                                                         {
 237                                                                                 write_socket(connection->fd, t_con->history[i], strlen(t_con->history[i]));
 238                                                                                 write_socket(connection->fd, "\r\n\x00", 3);
 239                                                                         }
 240                                                                 }
 241                                                                 telnet_prompt(connection);
 242                                                                 t_con->line_size = 0;
 243                                                                 t_con->line_cursor = 0;
 244                                                                 continue;
 245                                                         }
 246
 247                                                         if ((retval = command_run_line(command_context, t_con->line)) != ERROR_OK)
 248                                                         {
 249                                                                 if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 250                                                                 {
 251                                                                         return ERROR_SERVER_REMOTE_CLOSED;
 252                                                                 }
 253                                                         }
 254
 255                                                         /* Save only non-blank lines in the history */
 256                                                         if (t_con->line_size > 0)
 257                                                         {
 258                                                                 /* if the history slot is already taken, free it */
 259                                                                 if (t_con->history[t_con->next_history])
 260                                                                 {
 261                                                                         free(t_con->history[t_con->next_history]);
 262                                                                 }
 263
 264                                                                 /* add line to history */
 265                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 266
 267                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 268                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 269
 270                                                                 /* current history line starts at the new entry */
 271                                                                 t_con->current_history = t_con->next_history;
 272
 273                                                                 if (t_con->history[t_con->current_history])
 274                                                                 {
 275                                                                         free(t_con->history[t_con->current_history]);
 276                                                                 }
 277                                                                 t_con->history[t_con->current_history] = strdup("");
 278                                                         }
 279
 280                                                         /* output prompt after command */
 281                                                         telnet_prompt(connection);
 282
 283                                                         t_con->line_size = 0;
 284                                                         t_con->line_cursor = 0;
 285                                                 }
 286                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 287                                                 {
 288                                                         if (t_con->line_cursor > 0)
 289                                                         {
 290                                                                 if (t_con->line_cursor != t_con->line_size)
 291                                                                 {
 292                                                                         int i;
 293                                                                         write_socket(connection->fd, "\b", 1);
 294                                                                         t_con->line_cursor--;
 295                                                                         t_con->line_size--;
 296                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 297
 298                                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 299                                                                         write_socket(connection->fd, " \b", 2);
 300                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 301                                                                         {
 302                                                                                 write_socket(connection->fd, "\b", 1);
 303                                                                         }
 304                                                                 }
 305                                                                 else
 306                                                                 {
 307                                                                         t_con->line_size--;
 308                                                                         t_con->line_cursor--;
 309                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 310                                                                         write_socket(connection->fd, "\b \b", 3);
 311                                                                 }
 312                                                         }
 313                                                 }
 314                                                 else if (*buf_p == 0x15) /* clear line */
 315                                                 {
 316                                                         telnet_clear_line(connection, t_con);
 317                                                 }
 318                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 319                                                 {
 320                                                         if (t_con->line_cursor > 0)
 321                                                         {
 322                                                                 write_socket(connection->fd, "\b", 1);
 323                                                                 t_con->line_cursor--;
 324                                                         }
 325                                                         t_con->state = TELNET_STATE_DATA;
 326                                                 }
 327                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 328                                                 {
 329                                                         if (t_con->line_cursor < t_con->line_size)
 330                                                         {
 331                                                                 write_socket(connection->fd, t_con->line + t_con->line_cursor++, 1);
 332                                                         }
 333                                                         t_con->state = TELNET_STATE_DATA;
 334                                                 }
 335                                                 else
 336                                                 {
 337                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 338                                                 }
 339                                         }
 340                                 }
 341                                 break;
 342                         case TELNET_STATE_IAC:
 343                                 switch (*buf_p)
 344                                 {
 345                                         case '\xfe':
 346                                                 t_con->state = TELNET_STATE_DONT;
 347                                                 break;
 348                                         case '\xfd':
 349                                                 t_con->state = TELNET_STATE_DO;
 350                                                 break;
 351                                         case '\xfc':
 352                                                 t_con->state = TELNET_STATE_WONT;
 353                                                 break;
 354                                         case '\xfb':
 355                                                 t_con->state = TELNET_STATE_WILL;
 356                                                 break;
 357                                 }
 358                                 break;
 359                         case TELNET_STATE_SB:
 360                                 break;
 361                         case TELNET_STATE_SE:
 362                                 break;
 363                         case TELNET_STATE_WILL:
 364                         case TELNET_STATE_WONT:
 365                         case TELNET_STATE_DO:
 366                         case TELNET_STATE_DONT:
 367                                 t_con->state = TELNET_STATE_DATA;
 368                                 break;
 369                         case TELNET_STATE_ESCAPE:
 370                                 if (t_con->last_escape == '[')
 371                                 {
 372                                         if (*buf_p == 'D') /* cursor left */
 373                                         {
 374                                                 if (t_con->line_cursor > 0)
 375                                                 {
 376                                                         write_socket(connection->fd, "\b", 1);
 377                                                         t_con->line_cursor--;
 378                                                 }
 379                                                 t_con->state = TELNET_STATE_DATA;
 380                                         }
 381                                         else if (*buf_p == 'C') /* cursor right */
 382                                         {
 383                                                 if (t_con->line_cursor < t_con->line_size)
 384                                                 {
 385                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor++, 1);
 386                                                 }
 387                                                 t_con->state = TELNET_STATE_DATA;
 388                                         }
 389                                         else if (*buf_p == 'A') /* cursor up */
 390                                         {
 391                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 392                                                 if (t_con->history[last_history])
 393                                                 {
 394                                                         telnet_clear_line(connection, t_con);
 395                                                         t_con->line_size = strlen(t_con->history[last_history]);
 396                                                         t_con->line_cursor = t_con->line_size;
 397                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 398                                                         write_socket(connection->fd, t_con->line, t_con->line_size);
 399                                                         t_con->current_history = last_history;
 400                                                 }
 401                                                 t_con->state = TELNET_STATE_DATA;
 402                                         }
 403                                         else if (*buf_p == 'B') /* cursor down */
 404                                         {
 405                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 406                                                 if (t_con->history[next_history])
 407                                                 {
 408                                                         telnet_clear_line(connection, t_con);
 409                                                         t_con->line_size = strlen(t_con->history[next_history]);
 410                                                         t_con->line_cursor = t_con->line_size;
 411                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 412                                                         write_socket(connection->fd, t_con->line, t_con->line_size);
 413                                                         t_con->current_history = next_history;
 414                                                 }
 415                                                 t_con->state = TELNET_STATE_DATA;
 416                                         }
 417                                         else if (*buf_p == '3')
 418                                         {
 419                                                 t_con->last_escape = *buf_p;
 420                                         }
 421                                         else
 422                                         {
 423                                                 t_con->state = TELNET_STATE_DATA;
 424                                         }
 425                                 }
 426                                 else if (t_con->last_escape == '3')
 427                                 {
 428                                         /* Remove character */
 429                                         if (*buf_p == '~')
 430                                         {
 431                                                 if (t_con->line_cursor < t_con->line_size)
 432                                                 {
 433                                                         int i;
 434                                                         t_con->line_size--;
 435                                                         /* remove char from line buffer */
 436                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 437
 438                                                         /* print remainder of buffer */
 439                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 440                                                         /* overwrite last char with whitespace */
 441                                                         write_socket(connection->fd, " \b", 2);
 442
 443                                                         /* move back to cursor position*/
 444                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 445                                                         {
 446                                                                 write_socket(connection->fd, "\b", 1);
 447                                                         }
 448                                                 }
 449
 450                                                 t_con->state = TELNET_STATE_DATA;
 451                                         }
 452                                         else
 453                                         {
 454                                                 t_con->state = TELNET_STATE_DATA;
 455                                         }
 456                                 }
 457                                 else if (t_con->last_escape == '\x00')
 458                                 {
 459                                         if (*buf_p == '[')
 460                                         {
 461                                                 t_con->last_escape = *buf_p;
 462                                         }
 463                                         else
 464                                         {
 465                                                 t_con->state = TELNET_STATE_DATA;
 466                                         }
 467                                 }
 468                                 else
 469                                 {
 470                                         ERROR("BUG: unexpected value in t_con->last_escape");
 471                                         t_con->state = TELNET_STATE_DATA;
 472                                 }
 473
 474                                 break;
 475                         default:
 476                                 ERROR("unknown telnet state");
 477                                 exit(-1);
 478                 }
 479
 480                 bytes_read--;
 481                 buf_p++;
 482         }
 483
 484         return ERROR_OK;
 485 }
 486
 487 int telnet_connection_closed(connection_t *connection)
 488 {
 489         telnet_connection_t *t_con = connection->priv;
 490         int i;
 491
 492         if (t_con->prompt)
 493         {
 494                 free(t_con->prompt);
 495                 t_con->prompt = NULL;
 496         }
 497
 498         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 499         {
 500                 if (t_con->history[i])
 501                 {
 502                         free(t_con->history[i]);
 503                         t_con->history[i] = NULL;
 504                 }
 505         }
 506
 507         /* if this connection registered a debug-message receiver delete it */
 508         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 509
 510         if (connection->priv)
 511         {
 512                 free(connection->priv);
 513                 connection->priv = NULL;
 514         }
 515         else
 516         {
 517                 ERROR("BUG: connection->priv == NULL");
 518         }
 519
 520         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 521
 522         return ERROR_OK;
 523 }
 524
 525 int telnet_set_prompt(connection_t *connection, char *prompt)
 526 {
 527         telnet_connection_t *t_con = connection->priv;
 528
 529         t_con->prompt = strdup(prompt);
 530
 531         return ERROR_OK;
 532 }
 533
 534 int telnet_init(char *banner)
 535 {
 536         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 537
 538         if (telnet_port == 0)
 539         {
 540                 WARNING("no telnet port specified, using default port 4444");
 541                 telnet_port = 4444;
 542         }
 543
 544         telnet_service->banner = banner;
 545
 546         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 547
 548         return ERROR_OK;
 549 }
 550
 551 int telnet_register_commands(command_context_t *command_context)
 552 {
 553         register_command(command_context, NULL, "exit", handle_exit_command,
 554                                          COMMAND_EXEC, "exit telnet session");
 555
 556         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 557                                          COMMAND_CONFIG, "");
 558
 559         return ERROR_OK;
 560 }
 561
 562 /* daemon configuration command telnet_port */
 563 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 564 {
 565         if (argc == 0)
 566                 return ERROR_OK;
 567
 568         /* only if the port wasn't overwritten by cmdline */
 569         if (telnet_port == 0)
 570                 telnet_port = strtoul(args[0], NULL, 0);
 571
 572         return ERROR_OK;
 573 }
 574
 575 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 576 {
 577         return ERROR_COMMAND_CLOSE_CONNECTION;
 578 }