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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         telnet_write(connection, line, strlen(line));
  81         return telnet_write(connection, "\r\n\0", 3);
  82 }
  83
  84 int telnet_output(struct command_context_s *cmd_ctx, char* line)
  85 {
  86         connection_t *connection = cmd_ctx->output_handler_priv;
  87
  88         return telnet_outputline(connection, line);
  89 }
  90
  91 void telnet_log_callback(void *priv, const char *file, int line,
  92                 const char *function, const char *format, va_list args)
  93 {
  94         connection_t *connection = priv;
  95         char *t = alloc_printf(format, args);
  96         char *t2;
  97         if (t == NULL)
  98                 return;
  99         t2=t;
 100         char *endline;
 101         do
 102         {
 103                 if ((endline=strchr(t2, '\n'))!=NULL)
 104                 {
 105                         *endline=0;
 106                 }
 107                 telnet_outputline(connection, t2);
 108                 t2=endline+1;
 109         } while (endline);
 110
 111         free(t);
 112 }
 113
 114 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
 115 {
 116         struct command_context_s *cmd_ctx = priv;
 117         connection_t *connection = cmd_ctx->output_handler_priv;
 118         telnet_connection_t *t_con = connection->priv;
 119
 120         switch (event)
 121         {
 122                 case TARGET_EVENT_HALTED:
 123                         target_arch_state(target);
 124                         if (!t_con->suppress_prompt)
 125                                 telnet_prompt(connection);
 126                         break;
 127                 case TARGET_EVENT_RESUMED:
 128                         if (!t_con->suppress_prompt)
 129                                 telnet_prompt(connection);
 130                         break;
 131                 default:
 132                         break;
 133         }
 134
 135         return ERROR_OK;
 136 }
 137
 138 int telnet_new_connection(connection_t *connection)
 139 {
 140         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 141         telnet_service_t *telnet_service = connection->service->priv;
 142         int i;
 143
 144         connection->priv = telnet_connection;
 145
 146         /* initialize telnet connection information */
 147         telnet_connection->closed = 0;
 148         telnet_connection->line_size = 0;
 149         telnet_connection->line_cursor = 0;
 150         telnet_connection->option_size = 0;
 151         telnet_connection->prompt = strdup("> ");
 152         telnet_connection->suppress_prompt = 0;
 153         telnet_connection->state = TELNET_STATE_DATA;
 154
 155         /* output goes through telnet connection */
 156         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 157
 158         /* negotiate telnet options */
 159         telnet_write(connection, negotiate, strlen(negotiate));
 160
 161         /* print connection banner */
 162         if (telnet_service->banner)
 163         {
 164                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 165                 telnet_write(connection, "\r\n\0", 3);
 166         }
 167
 168         telnet_prompt(connection);
 169
 170         /* initialize history */
 171         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 172         {
 173                 telnet_connection->history[i] = NULL;
 174         }
 175         telnet_connection->next_history = 0;
 176         telnet_connection->current_history = 0;
 177
 178         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 179
 180         return ERROR_OK;
 181 }
 182
 183 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 184 {
 185         /* move to end of line */
 186         if (t_con->line_cursor < t_con->line_size)
 187         {
 188                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 189         }
 190
 191         /* backspace, overwrite with space, backspace */
 192         while (t_con->line_size > 0)
 193         {
 194                 telnet_write(connection, "\b \b", 3);
 195                 t_con->line_size--;
 196         }
 197         t_con->line_cursor = 0;
 198 }
 199
 200 int telnet_input(connection_t *connection)
 201 {
 202         int bytes_read;
 203         char buffer[TELNET_BUFFER_SIZE];
 204         char *buf_p;
 205         telnet_connection_t *t_con = connection->priv;
 206         command_context_t *command_context = connection->cmd_ctx;
 207
 208         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 209
 210         if (bytes_read == 0)
 211                 return ERROR_SERVER_REMOTE_CLOSED;
 212         else if (bytes_read == -1)
 213         {
 214                 ERROR("error during read: %s", strerror(errno));
 215                 return ERROR_SERVER_REMOTE_CLOSED;
 216         }
 217
 218         buf_p = buffer;
 219         while (bytes_read)
 220         {
 221                 switch (t_con->state)
 222                 {
 223                         case TELNET_STATE_DATA:
 224                                 if (*buf_p == '\xff')
 225                                 {
 226                                         t_con->state = TELNET_STATE_IAC;
 227                                 }
 228                                 else
 229                                 {
 230                                         if (isprint(*buf_p)) /* printable character */
 231                                         {
 232                                                 telnet_write(connection, buf_p, 1);
 233                                                 if (t_con->line_cursor == t_con->line_size)
 234                                                 {
 235                                                         t_con->line[t_con->line_size++] = *buf_p;
 236                                                         t_con->line_cursor++;
 237                                                 }
 238                                                 else
 239                                                 {
 240                                                         int i;
 241                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 242                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 243                                                         t_con->line_size++;
 244                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 245                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 246                                                         {
 247                                                                 telnet_write(connection, "\b", 1);
 248                                                         }
 249                                                 }
 250                                         }
 251                                         else /* non-printable */
 252                                         {
 253                                                 if (*buf_p == 0x1b) /* escape */
 254                                                 {
 255                                                         t_con->state = TELNET_STATE_ESCAPE;
 256                                                         t_con->last_escape = '\x00';
 257                                                 }
 258                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 259                                                 {
 260                                                         int retval;
 261
 262                                                         /* skip over combinations with CR/LF + NUL */
 263                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 264                                                         {
 265                                                                 buf_p++;
 266                                                                 bytes_read--;
 267                                                         }
 268                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 269                                                         {
 270                                                                 buf_p++;
 271                                                                 bytes_read--;
 272                                                         }
 273                                                         t_con->line[t_con->line_size] = 0;
 274
 275                                                         telnet_write(connection, "\r\n\x00", 3);
 276
 277                                                         if (strcmp(t_con->line, "history") == 0)
 278                                                         {
 279                                                                 int i;
 280                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 281                                                                 {
 282                                                                         if (t_con->history[i])
 283                                                                         {
 284                                                                                 telnet_write(connection, t_con->history[i], strlen(t_con->history[i]));
 285                                                                                 telnet_write(connection, "\r\n\x00", 3);
 286                                                                         }
 287                                                                 }
 288                                                                 telnet_prompt(connection);
 289                                                                 t_con->line_size = 0;
 290                                                                 t_con->line_cursor = 0;
 291                                                                 continue;
 292                                                         }
 293
 294                                                         log_add_callback(telnet_log_callback, connection);
 295                                                         t_con->suppress_prompt = 1;
 296
 297                                                         retval = command_run_line(command_context, t_con->line);
 298
 299                                                         log_remove_callback(telnet_log_callback, connection);
 300                                                         t_con->suppress_prompt = 0;
 301
 302                                                         if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 303                                                         {
 304                                                                 return ERROR_SERVER_REMOTE_CLOSED;
 305                                                         }
 306
 307                                                         /* Save only non-blank lines in the history */
 308                                                         if (t_con->line_size > 0)
 309                                                         {
 310                                                                 /* if the history slot is already taken, free it */
 311                                                                 if (t_con->history[t_con->next_history])
 312                                                                 {
 313                                                                         free(t_con->history[t_con->next_history]);
 314                                                                 }
 315
 316                                                                 /* add line to history */
 317                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 318
 319                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 320                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 321
 322                                                                 /* current history line starts at the new entry */
 323                                                                 t_con->current_history = t_con->next_history;
 324
 325                                                                 if (t_con->history[t_con->current_history])
 326                                                                 {
 327                                                                         free(t_con->history[t_con->current_history]);
 328                                                                 }
 329                                                                 t_con->history[t_con->current_history] = strdup("");
 330                                                         }
 331
 332                                                         int t = telnet_prompt(connection);
 333                                                         if (t == ERROR_SERVER_REMOTE_CLOSED)
 334                                                                 return t;
 335
 336                                                         t_con->line_size = 0;
 337                                                         t_con->line_cursor = 0;
 338                                                 }
 339                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 340                                                 {
 341                                                         if (t_con->line_cursor > 0)
 342                                                         {
 343                                                                 if (t_con->line_cursor != t_con->line_size)
 344                                                                 {
 345                                                                         int i;
 346                                                                         telnet_write(connection, "\b", 1);
 347                                                                         t_con->line_cursor--;
 348                                                                         t_con->line_size--;
 349                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 350
 351                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 352                                                                         telnet_write(connection, " \b", 2);
 353                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 354                                                                         {
 355                                                                                 telnet_write(connection, "\b", 1);
 356                                                                         }
 357                                                                 }
 358                                                                 else
 359                                                                 {
 360                                                                         t_con->line_size--;
 361                                                                         t_con->line_cursor--;
 362                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 363                                                                         telnet_write(connection, "\b \b", 3);
 364                                                                 }
 365                                                         }
 366                                                 }
 367                                                 else if (*buf_p == 0x15) /* clear line */
 368                                                 {
 369                                                         telnet_clear_line(connection, t_con);
 370                                                 }
 371                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 372                                                 {
 373                                                         if (t_con->line_cursor > 0)
 374                                                         {
 375                                                                 telnet_write(connection, "\b", 1);
 376                                                                 t_con->line_cursor--;
 377                                                         }
 378                                                         t_con->state = TELNET_STATE_DATA;
 379                                                 }
 380                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 381                                                 {
 382                                                         if (t_con->line_cursor < t_con->line_size)
 383                                                         {
 384                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 385                                                         }
 386                                                         t_con->state = TELNET_STATE_DATA;
 387                                                 }
 388                                                 else
 389                                                 {
 390                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 391                                                 }
 392                                         }
 393                                 }
 394                                 break;
 395                         case TELNET_STATE_IAC:
 396                                 switch (*buf_p)
 397                                 {
 398                                         case '\xfe':
 399                                                 t_con->state = TELNET_STATE_DONT;
 400                                                 break;
 401                                         case '\xfd':
 402                                                 t_con->state = TELNET_STATE_DO;
 403                                                 break;
 404                                         case '\xfc':
 405                                                 t_con->state = TELNET_STATE_WONT;
 406                                                 break;
 407                                         case '\xfb':
 408                                                 t_con->state = TELNET_STATE_WILL;
 409                                                 break;
 410                                 }
 411                                 break;
 412                         case TELNET_STATE_SB:
 413                                 break;
 414                         case TELNET_STATE_SE:
 415                                 break;
 416                         case TELNET_STATE_WILL:
 417                         case TELNET_STATE_WONT:
 418                         case TELNET_STATE_DO:
 419                         case TELNET_STATE_DONT:
 420                                 t_con->state = TELNET_STATE_DATA;
 421                                 break;
 422                         case TELNET_STATE_ESCAPE:
 423                                 if (t_con->last_escape == '[')
 424                                 {
 425                                         if (*buf_p == 'D') /* cursor left */
 426                                         {
 427                                                 if (t_con->line_cursor > 0)
 428                                                 {
 429                                                         telnet_write(connection, "\b", 1);
 430                                                         t_con->line_cursor--;
 431                                                 }
 432                                                 t_con->state = TELNET_STATE_DATA;
 433                                         }
 434                                         else if (*buf_p == 'C') /* cursor right */
 435                                         {
 436                                                 if (t_con->line_cursor < t_con->line_size)
 437                                                 {
 438                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 439                                                 }
 440                                                 t_con->state = TELNET_STATE_DATA;
 441                                         }
 442                                         else if (*buf_p == 'A') /* cursor up */
 443                                         {
 444                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 445                                                 if (t_con->history[last_history])
 446                                                 {
 447                                                         telnet_clear_line(connection, t_con);
 448                                                         t_con->line_size = strlen(t_con->history[last_history]);
 449                                                         t_con->line_cursor = t_con->line_size;
 450                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 451                                                         telnet_write(connection, t_con->line, t_con->line_size);
 452                                                         t_con->current_history = last_history;
 453                                                 }
 454                                                 t_con->state = TELNET_STATE_DATA;
 455                                         }
 456                                         else if (*buf_p == 'B') /* cursor down */
 457                                         {
 458                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 459                                                 if (t_con->history[next_history])
 460                                                 {
 461                                                         telnet_clear_line(connection, t_con);
 462                                                         t_con->line_size = strlen(t_con->history[next_history]);
 463                                                         t_con->line_cursor = t_con->line_size;
 464                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 465                                                         telnet_write(connection, t_con->line, t_con->line_size);
 466                                                         t_con->current_history = next_history;
 467                                                 }
 468                                                 t_con->state = TELNET_STATE_DATA;
 469                                         }
 470                                         else if (*buf_p == '3')
 471                                         {
 472                                                 t_con->last_escape = *buf_p;
 473                                         }
 474                                         else
 475                                         {
 476                                                 t_con->state = TELNET_STATE_DATA;
 477                                         }
 478                                 }
 479                                 else if (t_con->last_escape == '3')
 480                                 {
 481                                         /* Remove character */
 482                                         if (*buf_p == '~')
 483                                         {
 484                                                 if (t_con->line_cursor < t_con->line_size)
 485                                                 {
 486                                                         int i;
 487                                                         t_con->line_size--;
 488                                                         /* remove char from line buffer */
 489                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 490
 491                                                         /* print remainder of buffer */
 492                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 493                                                         /* overwrite last char with whitespace */
 494                                                         telnet_write(connection, " \b", 2);
 495
 496                                                         /* move back to cursor position*/
 497                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 498                                                         {
 499                                                                 telnet_write(connection, "\b", 1);
 500                                                         }
 501                                                 }
 502
 503                                                 t_con->state = TELNET_STATE_DATA;
 504                                         }
 505                                         else
 506                                         {
 507                                                 t_con->state = TELNET_STATE_DATA;
 508                                         }
 509                                 }
 510                                 else if (t_con->last_escape == '\x00')
 511                                 {
 512                                         if (*buf_p == '[')
 513                                         {
 514                                                 t_con->last_escape = *buf_p;
 515                                         }
 516                                         else
 517                                         {
 518                                                 t_con->state = TELNET_STATE_DATA;
 519                                         }
 520                                 }
 521                                 else
 522                                 {
 523                                         ERROR("BUG: unexpected value in t_con->last_escape");
 524                                         t_con->state = TELNET_STATE_DATA;
 525                                 }
 526
 527                                 break;
 528                         default:
 529                                 ERROR("unknown telnet state");
 530                                 exit(-1);
 531                 }
 532
 533                 bytes_read--;
 534                 buf_p++;
 535         }
 536
 537         return ERROR_OK;
 538 }
 539
 540 int telnet_connection_closed(connection_t *connection)
 541 {
 542         telnet_connection_t *t_con = connection->priv;
 543         int i;
 544
 545         if (t_con->prompt)
 546         {
 547                 free(t_con->prompt);
 548                 t_con->prompt = NULL;
 549         }
 550
 551         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 552         {
 553                 if (t_con->history[i])
 554                 {
 555                         free(t_con->history[i]);
 556                         t_con->history[i] = NULL;
 557                 }
 558         }
 559
 560         /* if this connection registered a debug-message receiver delete it */
 561         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 562
 563         if (connection->priv)
 564         {
 565                 free(connection->priv);
 566                 connection->priv = NULL;
 567         }
 568         else
 569         {
 570                 ERROR("BUG: connection->priv == NULL");
 571         }
 572
 573         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 574
 575         return ERROR_OK;
 576 }
 577
 578 int telnet_set_prompt(connection_t *connection, char *prompt)
 579 {
 580         telnet_connection_t *t_con = connection->priv;
 581
 582         t_con->prompt = strdup(prompt);
 583
 584         return ERROR_OK;
 585 }
 586
 587 int telnet_init(char *banner)
 588 {
 589         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 590
 591         if (telnet_port == 0)
 592         {
 593                 WARNING("no telnet port specified, using default port 4444");
 594                 telnet_port = 4444;
 595         }
 596
 597         telnet_service->banner = banner;
 598
 599         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 600
 601         return ERROR_OK;
 602 }
 603
 604 int telnet_register_commands(command_context_t *command_context)
 605 {
 606         register_command(command_context, NULL, "exit", handle_exit_command,
 607                                          COMMAND_EXEC, "exit telnet session");
 608
 609         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 610                                          COMMAND_CONFIG, "");
 611
 612         return ERROR_OK;
 613 }
 614
 615 /* daemon configuration command telnet_port */
 616 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 617 {
 618         if (argc == 0)
 619                 return ERROR_OK;
 620
 621         /* only if the port wasn't overwritten by cmdline */
 622         if (telnet_port == 0)
 623                 telnet_port = strtoul(args[0], NULL, 0);
 624
 625         return ERROR_OK;
 626 }
 627
 628 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 629 {
 630         return ERROR_COMMAND_CLOSE_CONNECTION;
 631 }