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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 #include "telnet_server.h"
  21
  22 #include "server.h"
  23 #include "log.h"
  24 #include "command.h"
  25 #include "target.h"
  26
  27 #include <stdlib.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30 #include <string.h>
  31 #include <ctype.h>
  32
  33 static unsigned short telnet_port = 0;
  34
  35 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  36 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  37
  38 static char *negotiate =
  39                 "\xFF\xFB\x03"          /* IAC WILL Suppress Go Ahead */
  40                 "\xFF\xFB\x01"          /* IAC WILL Echo */
  41                 "\xFF\xFD\x03"          /* IAC DO Suppress Go Ahead */
  42                 "\xFF\xFE\x01";         /* IAC DON'T Echo */
  43
  44 #define CTRL(c) (c - '@')
  45
  46 void telnet_prompt(connection_t *connection)
  47 {
  48         telnet_connection_t *t_con = connection->priv;
  49
  50         write(connection->fd, t_con->prompt, strlen(t_con->prompt));
  51 }
  52
  53 int telnet_output(struct command_context_s *cmd_ctx, char* line)
  54 {
  55         connection_t *connection = cmd_ctx->output_handler_priv;
  56
  57         write(connection->fd, line, strlen(line));
  58         write(connection->fd, "\r\n\0", 3);
  59
  60         return ERROR_OK;
  61 }
  62
  63 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
  64 {
  65         struct command_context_s *cmd_ctx = priv;
  66         connection_t *connection = cmd_ctx->output_handler_priv;
  67         telnet_connection_t *t_con = connection->priv;
  68         char buffer[512];
  69
  70         switch (event)
  71         {
  72                 case TARGET_EVENT_HALTED:
  73                         command_print(cmd_ctx, "Target %i halted", get_num_by_target(target));
  74                         target->type->arch_state(target, buffer, 512);
  75                         buffer[511] = 0;
  76                         command_print(cmd_ctx, "%s", buffer);
  77                         telnet_prompt(connection);
  78                         t_con->suppress_prompt = 1;
  79                         break;
  80                 case TARGET_EVENT_RESUMED:
  81                         command_print(cmd_ctx, "Target %i resumed", get_num_by_target(target));
  82                         telnet_prompt(connection);
  83                         t_con->suppress_prompt = 1;
  84                         break;
  85                 default:
  86                         break;
  87         }
  88
  89         return ERROR_OK;
  90 }
  91
  92 int telnet_new_connection(connection_t *connection)
  93 {
  94         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
  95         telnet_service_t *telnet_service = connection->service->priv;
  96         int i;
  97
  98         connection->priv = telnet_connection;
  99
 100         /* initialize telnet connection information */
 101         telnet_connection->line_size = 0;
 102         telnet_connection->line_cursor = 0;
 103         telnet_connection->option_size = 0;
 104         telnet_connection->prompt = strdup("> ");
 105         telnet_connection->suppress_prompt = 0;
 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(connection->fd, negotiate, strlen(negotiate));
 113
 114         /* print connection banner */
 115         if (telnet_service->banner)
 116         {
 117                 write(connection->fd, telnet_service->banner, strlen(telnet_service->banner));
 118                 write(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(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(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(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(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(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(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(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(connection->fd, t_con->history[i], strlen(t_con->history[i]));
 238                                                                                 write(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                                                         /* we're running a command, so we need a prompt
 248                                                          * if the output handler is called, this gets set again */
 249                                                         t_con->suppress_prompt = 0;
 250                                                         if ((retval = command_run_line(command_context, t_con->line)) != ERROR_OK)
 251                                                         {
 252                                                                 if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 253                                                                 {
 254                                                                         return ERROR_SERVER_REMOTE_CLOSED;
 255                                                                 }
 256                                                         }
 257
 258                                                         /* Save only non-blank lines in the history */
 259                                                         if (t_con->line_size > 0)
 260                                                         {
 261                                                                 /* if the history slot is already taken, free it */
 262                                                                 if (t_con->history[t_con->next_history])
 263                                                                 {
 264                                                                         free(t_con->history[t_con->next_history]);
 265                                                                 }
 266
 267                                                                 /* add line to history */
 268                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 269
 270                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 271                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 272
 273                                                                 /* current history line starts at the new entry */
 274                                                                 t_con->current_history = t_con->next_history;
 275
 276                                                                 if (t_con->history[t_con->current_history])
 277                                                                 {
 278                                                                         free(t_con->history[t_con->current_history]);
 279                                                                 }
 280                                                                 t_con->history[t_con->current_history] = strdup("");
 281                                                         }
 282
 283                                                         if (!t_con->suppress_prompt)
 284                                                         {
 285                                                                 telnet_prompt(connection);
 286                                                         }
 287                                                         else
 288                                                         {
 289                                                                 t_con->suppress_prompt = 0;
 290                                                         }
 291
 292                                                         t_con->line_size = 0;
 293                                                         t_con->line_cursor = 0;
 294                                                 }
 295                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 296                                                 {
 297                                                         if (t_con->line_cursor > 0)
 298                                                         {
 299                                                                 if (t_con->line_cursor != t_con->line_size)
 300                                                                 {
 301                                                                         int i;
 302                                                                         write(connection->fd, "\b", 1);
 303                                                                         t_con->line_cursor--;
 304                                                                         t_con->line_size--;
 305                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 306
 307                                                                         write(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 308                                                                         write(connection->fd, " \b", 2);
 309                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 310                                                                         {
 311                                                                                 write(connection->fd, "\b", 1);
 312                                                                         }
 313                                                                 }
 314                                                                 else
 315                                                                 {
 316                                                                         t_con->line_size--;
 317                                                                         t_con->line_cursor--;
 318                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 319                                                                         write(connection->fd, "\b \b", 3);
 320                                                                 }
 321                                                         }
 322                                                 }
 323                                                 else if (*buf_p == 0x15) /* clear line */
 324                                                 {
 325                                                         telnet_clear_line(connection, t_con);
 326                                                 }
 327                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 328                                                 {
 329                                                         if (t_con->line_cursor > 0)
 330                                                         {
 331                                                                 write(connection->fd, "\b", 1);
 332                                                                 t_con->line_cursor--;
 333                                                         }
 334                                                         t_con->state = TELNET_STATE_DATA;
 335                                                 }
 336                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 337                                                 {
 338                                                         if (t_con->line_cursor < t_con->line_size)
 339                                                         {
 340                                                                 write(connection->fd, t_con->line + t_con->line_cursor++, 1);
 341                                                         }
 342                                                         t_con->state = TELNET_STATE_DATA;
 343                                                 }
 344                                                 else
 345                                                 {
 346                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 347                                                 }
 348                                         }
 349                                 }
 350                                 break;
 351                         case TELNET_STATE_IAC:
 352                                 switch (*buf_p)
 353                                 {
 354                                         case '\xfe':
 355                                                 t_con->state = TELNET_STATE_DONT;
 356                                                 break;
 357                                         case '\xfd':
 358                                                 t_con->state = TELNET_STATE_DO;
 359                                                 break;
 360                                         case '\xfc':
 361                                                 t_con->state = TELNET_STATE_WONT;
 362                                                 break;
 363                                         case '\xfb':
 364                                                 t_con->state = TELNET_STATE_WILL;
 365                                                 break;
 366                                 }
 367                                 break;
 368                         case TELNET_STATE_SB:
 369                                 break;
 370                         case TELNET_STATE_SE:
 371                                 break;
 372                         case TELNET_STATE_WILL:
 373                         case TELNET_STATE_WONT:
 374                         case TELNET_STATE_DO:
 375                         case TELNET_STATE_DONT:
 376                                 t_con->state = TELNET_STATE_DATA;
 377                                 break;
 378                         case TELNET_STATE_ESCAPE:
 379                                 if (t_con->last_escape == '[')
 380                                 {
 381                                         if (*buf_p == 'D') /* cursor left */
 382                                         {
 383                                                 if (t_con->line_cursor > 0)
 384                                                 {
 385                                                         write(connection->fd, "\b", 1);
 386                                                         t_con->line_cursor--;
 387                                                 }
 388                                                 t_con->state = TELNET_STATE_DATA;
 389                                         }
 390                                         else if (*buf_p == 'C') /* cursor right */
 391                                         {
 392                                                 if (t_con->line_cursor < t_con->line_size)
 393                                                 {
 394                                                         write(connection->fd, t_con->line + t_con->line_cursor++, 1);
 395                                                 }
 396                                                 t_con->state = TELNET_STATE_DATA;
 397                                         }
 398                                         else if (*buf_p == 'A') /* cursor up */
 399                                         {
 400                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 401                                                 if (t_con->history[last_history])
 402                                                 {
 403                                                         telnet_clear_line(connection, t_con);
 404                                                         t_con->line_size = strlen(t_con->history[last_history]);
 405                                                         t_con->line_cursor = t_con->line_size;
 406                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 407                                                         write(connection->fd, t_con->line, t_con->line_size);
 408                                                         t_con->current_history = last_history;
 409                                                 }
 410                                                 t_con->state = TELNET_STATE_DATA;
 411                                         }
 412                                         else if (*buf_p == 'B') /* cursor down */
 413                                         {
 414                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 415                                                 if (t_con->history[next_history])
 416                                                 {
 417                                                         telnet_clear_line(connection, t_con);
 418                                                         t_con->line_size = strlen(t_con->history[next_history]);
 419                                                         t_con->line_cursor = t_con->line_size;
 420                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 421                                                         write(connection->fd, t_con->line, t_con->line_size);
 422                                                         t_con->current_history = next_history;
 423                                                 }
 424                                                 t_con->state = TELNET_STATE_DATA;
 425                                         }
 426                                         else if (*buf_p == '3')
 427                                         {
 428                                                 t_con->last_escape = *buf_p;
 429                                         }
 430                                         else
 431                                         {
 432                                                 t_con->state = TELNET_STATE_DATA;
 433                                         }
 434                                 }
 435                                 else if (t_con->last_escape == '3')
 436                                 {
 437                                         /* Remove character */
 438                                         if (*buf_p == '~')
 439                                         {
 440                                                 if (t_con->line_cursor < t_con->line_size)
 441                                                 {
 442                                                         int i;
 443                                                         t_con->line_size--;
 444                                                         /* remove char from line buffer */
 445                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 446
 447                                                         /* print remainder of buffer */
 448                                                         write(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 449                                                         /* overwrite last char with whitespace */
 450                                                         write(connection->fd, " \b", 2);
 451
 452                                                         /* move back to cursor position*/
 453                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 454                                                         {
 455                                                                 write(connection->fd, "\b", 1);
 456                                                         }
 457                                                 }
 458
 459                                                 t_con->state = TELNET_STATE_DATA;
 460                                         }
 461                                         else
 462                                         {
 463                                                 t_con->state = TELNET_STATE_DATA;
 464                                         }
 465                                 }
 466                                 else if (t_con->last_escape == '\x00')
 467                                 {
 468                                         if (*buf_p == '[')
 469                                         {
 470                                                 t_con->last_escape = *buf_p;
 471                                         }
 472                                         else
 473                                         {
 474                                                 t_con->state = TELNET_STATE_DATA;
 475                                         }
 476                                 }
 477                                 else
 478                                 {
 479                                         ERROR("BUG: unexpected value in t_con->last_escape");
 480                                         t_con->state = TELNET_STATE_DATA;
 481                                 }
 482
 483                                 break;
 484                         default:
 485                                 ERROR("unknown telnet state");
 486                                 exit(-1);
 487                 }
 488
 489                 bytes_read--;
 490                 buf_p++;
 491         }
 492
 493         return ERROR_OK;
 494 }
 495
 496 int telnet_connection_closed(connection_t *connection)
 497 {
 498         telnet_connection_t *t_con = connection->priv;
 499         int i;
 500
 501         if (t_con->prompt)
 502                 free(t_con->prompt);
 503
 504         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 505         {
 506                 if (t_con->history[i])
 507                         free(t_con->history[i]);
 508         }
 509
 510         if (connection->priv)
 511                 free(connection->priv);
 512         else
 513                 ERROR("BUG: connection->priv == NULL");
 514
 515         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 516
 517         return ERROR_OK;
 518 }
 519
 520 int telnet_set_prompt(connection_t *connection, char *prompt)
 521 {
 522         telnet_connection_t *t_con = connection->priv;
 523
 524         t_con->prompt = strdup(prompt);
 525
 526         return ERROR_OK;
 527 }
 528
 529 int telnet_init(char *banner)
 530 {
 531         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 532
 533         if (telnet_port == 0)
 534         {
 535                 WARNING("no telnet port specified, using default port 4444");
 536                 telnet_port = 4444;
 537         }
 538
 539         telnet_service->banner = banner;
 540
 541         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 542
 543         return ERROR_OK;
 544 }
 545
 546 int telnet_register_commands(command_context_t *command_context)
 547 {
 548         register_command(command_context, NULL, "exit", handle_exit_command,
 549                                          COMMAND_EXEC, "exit telnet session");
 550
 551         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 552                                          COMMAND_CONFIG, "");
 553
 554         return ERROR_OK;
 555 }
 556
 557 /* daemon configuration command telnet_port */
 558 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 559 {
 560         if (argc == 0)
 561                 return ERROR_OK;
 562
 563         /* only if the port wasn't overwritten by cmdline */
 564         if (telnet_port == 0)
 565                 telnet_port = strtoul(args[0], NULL, 0);
 566
 567         return ERROR_OK;
 568 }
 569
 570 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 571 {
 572         return ERROR_COMMAND_CLOSE_CONNECTION;
 573 }