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