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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
  33 #include <stdlib.h>
  34 #include <unistd.h>
  35 #include <errno.h>
  36 #include <string.h>
  37 #include <ctype.h>
  38
  39 static unsigned short telnet_port = 0;
  40
  41 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  42 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
  43
  44 static char *negotiate =
  45                 "\xFF\xFB\x03"          /* IAC WILL Suppress Go Ahead */
  46                 "\xFF\xFB\x01"          /* IAC WILL Echo */
  47                 "\xFF\xFD\x03"          /* IAC DO Suppress Go Ahead */
  48                 "\xFF\xFE\x01";         /* IAC DON'T Echo */
  49
  50 #define CTRL(c) (c - '@')
  51
  52 void telnet_prompt(connection_t *connection)
  53 {
  54         telnet_connection_t *t_con = connection->priv;
  55
  56         write_socket(connection->fd, t_con->prompt, strlen(t_con->prompt));
  57 }
  58
  59 int telnet_output(struct command_context_s *cmd_ctx, char* line)
  60 {
  61         connection_t *connection = cmd_ctx->output_handler_priv;
  62
  63         write_socket(connection->fd, line, strlen(line));
  64         write_socket(connection->fd, "\r\n\0", 3);
  65
  66         return ERROR_OK;
  67 }
  68
  69 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
  70 {
  71         struct command_context_s *cmd_ctx = priv;
  72         connection_t *connection = cmd_ctx->output_handler_priv;
  73         telnet_connection_t *t_con = connection->priv;
  74         char buffer[512];
  75
  76         switch (event)
  77         {
  78                 case TARGET_EVENT_HALTED:
  79                         command_print(cmd_ctx, "Target %i halted", get_num_by_target(target));
  80                         target->type->arch_state(target, buffer, 512);
  81                         buffer[511] = 0;
  82                         command_print(cmd_ctx, "%s", buffer);
  83                         telnet_prompt(connection);
  84                         t_con->suppress_prompt = 1;
  85                         break;
  86                 case TARGET_EVENT_RESUMED:
  87                         command_print(cmd_ctx, "Target %i resumed", get_num_by_target(target));
  88                         telnet_prompt(connection);
  89                         t_con->suppress_prompt = 1;
  90                         break;
  91                 default:
  92                         break;
  93         }
  94
  95         return ERROR_OK;
  96 }
  97
  98 int telnet_new_connection(connection_t *connection)
  99 {
 100         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 101         telnet_service_t *telnet_service = connection->service->priv;
 102         int i;
 103
 104         connection->priv = telnet_connection;
 105
 106         /* initialize telnet connection information */
 107         telnet_connection->line_size = 0;
 108         telnet_connection->line_cursor = 0;
 109         telnet_connection->option_size = 0;
 110         telnet_connection->prompt = strdup("> ");
 111         telnet_connection->suppress_prompt = 0;
 112         telnet_connection->state = TELNET_STATE_DATA;
 113
 114         /* output goes through telnet connection */
 115         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 116
 117         /* negotiate telnet options */
 118         write_socket(connection->fd, negotiate, strlen(negotiate));
 119
 120         /* print connection banner */
 121         if (telnet_service->banner)
 122         {
 123                 write_socket(connection->fd, telnet_service->banner, strlen(telnet_service->banner));
 124                 write_socket(connection->fd, "\r\n\0", 3);
 125         }
 126
 127         telnet_prompt(connection);
 128
 129         /* initialize history */
 130         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 131         {
 132                 telnet_connection->history[i] = NULL;
 133         }
 134         telnet_connection->next_history = 0;
 135         telnet_connection->current_history = 0;
 136
 137         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 138
 139         return ERROR_OK;
 140 }
 141
 142 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 143 {
 144         /* move to end of line */
 145         if (t_con->line_cursor < t_con->line_size)
 146         {
 147                 write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 148         }
 149
 150         /* backspace, overwrite with space, backspace */
 151         while (t_con->line_size > 0)
 152         {
 153                 write_socket(connection->fd, "\b \b", 3);
 154                 t_con->line_size--;
 155         }
 156         t_con->line_cursor = 0;
 157 }
 158
 159 int telnet_input(connection_t *connection)
 160 {
 161         int bytes_read;
 162         char buffer[TELNET_BUFFER_SIZE];
 163         char *buf_p;
 164         telnet_connection_t *t_con = connection->priv;
 165         command_context_t *command_context = connection->cmd_ctx;
 166
 167         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 168
 169         if (bytes_read == 0)
 170                 return ERROR_SERVER_REMOTE_CLOSED;
 171         else if (bytes_read == -1)
 172         {
 173                 ERROR("error during read: %s", strerror(errno));
 174                 return ERROR_SERVER_REMOTE_CLOSED;
 175         }
 176
 177         buf_p = buffer;
 178         while (bytes_read)
 179         {
 180                 switch (t_con->state)
 181                 {
 182                         case TELNET_STATE_DATA:
 183                                 if (*buf_p == '\xff')
 184                                 {
 185                                         t_con->state = TELNET_STATE_IAC;
 186                                 }
 187                                 else
 188                                 {
 189                                         if (isprint(*buf_p)) /* printable character */
 190                                         {
 191                                                 write_socket(connection->fd, buf_p, 1);
 192                                                 if (t_con->line_cursor == t_con->line_size)
 193                                                 {
 194                                                         t_con->line[t_con->line_size++] = *buf_p;
 195                                                         t_con->line_cursor++;
 196                                                 }
 197                                                 else
 198                                                 {
 199                                                         int i;
 200                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 201                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 202                                                         t_con->line_size++;
 203                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 204                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 205                                                         {
 206                                                                 write_socket(connection->fd, "\b", 1);
 207                                                         }
 208                                                 }
 209                                         }
 210                                         else /* non-printable */
 211                                         {
 212                                                 if (*buf_p == 0x1b) /* escape */
 213                                                 {
 214                                                         t_con->state = TELNET_STATE_ESCAPE;
 215                                                         t_con->last_escape = '\x00';
 216                                                 }
 217                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 218                                                 {
 219                                                         int retval;
 220
 221                                                         /* skip over combinations with CR/LF + NUL */
 222                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 223                                                         {
 224                                                                 buf_p++;
 225                                                                 bytes_read--;
 226                                                         }
 227                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 228                                                         {
 229                                                                 buf_p++;
 230                                                                 bytes_read--;
 231                                                         }
 232                                                         t_con->line[t_con->line_size] = 0;
 233
 234                                                         write_socket(connection->fd, "\r\n\x00", 3);
 235
 236                                                         if (strcmp(t_con->line, "history") == 0)
 237                                                         {
 238                                                                 int i;
 239                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 240                                                                 {
 241                                                                         if (t_con->history[i])
 242                                                                         {
 243                                                                                 write_socket(connection->fd, t_con->history[i], strlen(t_con->history[i]));
 244                                                                                 write_socket(connection->fd, "\r\n\x00", 3);
 245                                                                         }
 246                                                                 }
 247                                                                 telnet_prompt(connection);
 248                                                                 t_con->line_size = 0;
 249                                                                 t_con->line_cursor = 0;
 250                                                                 continue;
 251                                                         }
 252
 253                                                         /* we're running a command, so we need a prompt
 254                                                          * if the output handler is called, this gets set again */
 255                                                         t_con->suppress_prompt = 0;
 256                                                         if ((retval = command_run_line(command_context, t_con->line)) != ERROR_OK)
 257                                                         {
 258                                                                 if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 259                                                                 {
 260                                                                         return ERROR_SERVER_REMOTE_CLOSED;
 261                                                                 }
 262                                                         }
 263
 264                                                         /* Save only non-blank lines in the history */
 265                                                         if (t_con->line_size > 0)
 266                                                         {
 267                                                                 /* if the history slot is already taken, free it */
 268                                                                 if (t_con->history[t_con->next_history])
 269                                                                 {
 270                                                                         free(t_con->history[t_con->next_history]);
 271                                                                 }
 272
 273                                                                 /* add line to history */
 274                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 275
 276                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 277                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 278
 279                                                                 /* current history line starts at the new entry */
 280                                                                 t_con->current_history = t_con->next_history;
 281
 282                                                                 if (t_con->history[t_con->current_history])
 283                                                                 {
 284                                                                         free(t_con->history[t_con->current_history]);
 285                                                                 }
 286                                                                 t_con->history[t_con->current_history] = strdup("");
 287                                                         }
 288
 289                                                         if (!t_con->suppress_prompt)
 290                                                         {
 291                                                                 telnet_prompt(connection);
 292                                                         }
 293                                                         else
 294                                                         {
 295                                                                 t_con->suppress_prompt = 0;
 296                                                         }
 297
 298                                                         t_con->line_size = 0;
 299                                                         t_con->line_cursor = 0;
 300                                                 }
 301                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 302                                                 {
 303                                                         if (t_con->line_cursor > 0)
 304                                                         {
 305                                                                 if (t_con->line_cursor != t_con->line_size)
 306                                                                 {
 307                                                                         int i;
 308                                                                         write_socket(connection->fd, "\b", 1);
 309                                                                         t_con->line_cursor--;
 310                                                                         t_con->line_size--;
 311                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 312
 313                                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 314                                                                         write_socket(connection->fd, " \b", 2);
 315                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 316                                                                         {
 317                                                                                 write_socket(connection->fd, "\b", 1);
 318                                                                         }
 319                                                                 }
 320                                                                 else
 321                                                                 {
 322                                                                         t_con->line_size--;
 323                                                                         t_con->line_cursor--;
 324                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 325                                                                         write_socket(connection->fd, "\b \b", 3);
 326                                                                 }
 327                                                         }
 328                                                 }
 329                                                 else if (*buf_p == 0x15) /* clear line */
 330                                                 {
 331                                                         telnet_clear_line(connection, t_con);
 332                                                 }
 333                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 334                                                 {
 335                                                         if (t_con->line_cursor > 0)
 336                                                         {
 337                                                                 write_socket(connection->fd, "\b", 1);
 338                                                                 t_con->line_cursor--;
 339                                                         }
 340                                                         t_con->state = TELNET_STATE_DATA;
 341                                                 }
 342                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 343                                                 {
 344                                                         if (t_con->line_cursor < t_con->line_size)
 345                                                         {
 346                                                                 write_socket(connection->fd, t_con->line + t_con->line_cursor++, 1);
 347                                                         }
 348                                                         t_con->state = TELNET_STATE_DATA;
 349                                                 }
 350                                                 else
 351                                                 {
 352                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 353                                                 }
 354                                         }
 355                                 }
 356                                 break;
 357                         case TELNET_STATE_IAC:
 358                                 switch (*buf_p)
 359                                 {
 360                                         case '\xfe':
 361                                                 t_con->state = TELNET_STATE_DONT;
 362                                                 break;
 363                                         case '\xfd':
 364                                                 t_con->state = TELNET_STATE_DO;
 365                                                 break;
 366                                         case '\xfc':
 367                                                 t_con->state = TELNET_STATE_WONT;
 368                                                 break;
 369                                         case '\xfb':
 370                                                 t_con->state = TELNET_STATE_WILL;
 371                                                 break;
 372                                 }
 373                                 break;
 374                         case TELNET_STATE_SB:
 375                                 break;
 376                         case TELNET_STATE_SE:
 377                                 break;
 378                         case TELNET_STATE_WILL:
 379                         case TELNET_STATE_WONT:
 380                         case TELNET_STATE_DO:
 381                         case TELNET_STATE_DONT:
 382                                 t_con->state = TELNET_STATE_DATA;
 383                                 break;
 384                         case TELNET_STATE_ESCAPE:
 385                                 if (t_con->last_escape == '[')
 386                                 {
 387                                         if (*buf_p == 'D') /* cursor left */
 388                                         {
 389                                                 if (t_con->line_cursor > 0)
 390                                                 {
 391                                                         write_socket(connection->fd, "\b", 1);
 392                                                         t_con->line_cursor--;
 393                                                 }
 394                                                 t_con->state = TELNET_STATE_DATA;
 395                                         }
 396                                         else if (*buf_p == 'C') /* cursor right */
 397                                         {
 398                                                 if (t_con->line_cursor < t_con->line_size)
 399                                                 {
 400                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor++, 1);
 401                                                 }
 402                                                 t_con->state = TELNET_STATE_DATA;
 403                                         }
 404                                         else if (*buf_p == 'A') /* cursor up */
 405                                         {
 406                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 407                                                 if (t_con->history[last_history])
 408                                                 {
 409                                                         telnet_clear_line(connection, t_con);
 410                                                         t_con->line_size = strlen(t_con->history[last_history]);
 411                                                         t_con->line_cursor = t_con->line_size;
 412                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 413                                                         write_socket(connection->fd, t_con->line, t_con->line_size);
 414                                                         t_con->current_history = last_history;
 415                                                 }
 416                                                 t_con->state = TELNET_STATE_DATA;
 417                                         }
 418                                         else if (*buf_p == 'B') /* cursor down */
 419                                         {
 420                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 421                                                 if (t_con->history[next_history])
 422                                                 {
 423                                                         telnet_clear_line(connection, t_con);
 424                                                         t_con->line_size = strlen(t_con->history[next_history]);
 425                                                         t_con->line_cursor = t_con->line_size;
 426                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 427                                                         write_socket(connection->fd, t_con->line, t_con->line_size);
 428                                                         t_con->current_history = next_history;
 429                                                 }
 430                                                 t_con->state = TELNET_STATE_DATA;
 431                                         }
 432                                         else if (*buf_p == '3')
 433                                         {
 434                                                 t_con->last_escape = *buf_p;
 435                                         }
 436                                         else
 437                                         {
 438                                                 t_con->state = TELNET_STATE_DATA;
 439                                         }
 440                                 }
 441                                 else if (t_con->last_escape == '3')
 442                                 {
 443                                         /* Remove character */
 444                                         if (*buf_p == '~')
 445                                         {
 446                                                 if (t_con->line_cursor < t_con->line_size)
 447                                                 {
 448                                                         int i;
 449                                                         t_con->line_size--;
 450                                                         /* remove char from line buffer */
 451                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 452
 453                                                         /* print remainder of buffer */
 454                                                         write_socket(connection->fd, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 455                                                         /* overwrite last char with whitespace */
 456                                                         write_socket(connection->fd, " \b", 2);
 457
 458                                                         /* move back to cursor position*/
 459                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 460                                                         {
 461                                                                 write_socket(connection->fd, "\b", 1);
 462                                                         }
 463                                                 }
 464
 465                                                 t_con->state = TELNET_STATE_DATA;
 466                                         }
 467                                         else
 468                                         {
 469                                                 t_con->state = TELNET_STATE_DATA;
 470                                         }
 471                                 }
 472                                 else if (t_con->last_escape == '\x00')
 473                                 {
 474                                         if (*buf_p == '[')
 475                                         {
 476                                                 t_con->last_escape = *buf_p;
 477                                         }
 478                                         else
 479                                         {
 480                                                 t_con->state = TELNET_STATE_DATA;
 481                                         }
 482                                 }
 483                                 else
 484                                 {
 485                                         ERROR("BUG: unexpected value in t_con->last_escape");
 486                                         t_con->state = TELNET_STATE_DATA;
 487                                 }
 488
 489                                 break;
 490                         default:
 491                                 ERROR("unknown telnet state");
 492                                 exit(-1);
 493                 }
 494
 495                 bytes_read--;
 496                 buf_p++;
 497         }
 498
 499         return ERROR_OK;
 500 }
 501
 502 int telnet_connection_closed(connection_t *connection)
 503 {
 504         telnet_connection_t *t_con = connection->priv;
 505         int i;
 506
 507         if (t_con->prompt)
 508                 free(t_con->prompt);
 509
 510         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 511         {
 512                 if (t_con->history[i])
 513                         free(t_con->history[i]);
 514         }
 515
 516         if (connection->priv)
 517                 free(connection->priv);
 518         else
 519                 ERROR("BUG: connection->priv == NULL");
 520
 521         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 522
 523         return ERROR_OK;
 524 }
 525
 526 int telnet_set_prompt(connection_t *connection, char *prompt)
 527 {
 528         telnet_connection_t *t_con = connection->priv;
 529
 530         t_con->prompt = strdup(prompt);
 531
 532         return ERROR_OK;
 533 }
 534
 535 int telnet_init(char *banner)
 536 {
 537         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 538
 539         if (telnet_port == 0)
 540         {
 541                 WARNING("no telnet port specified, using default port 4444");
 542                 telnet_port = 4444;
 543         }
 544
 545         telnet_service->banner = banner;
 546
 547         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 548
 549         return ERROR_OK;
 550 }
 551
 552 int telnet_register_commands(command_context_t *command_context)
 553 {
 554         register_command(command_context, NULL, "exit", handle_exit_command,
 555                                          COMMAND_EXEC, "exit telnet session");
 556
 557         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 558                                          COMMAND_CONFIG, "");
 559
 560         return ERROR_OK;
 561 }
 562
 563 /* daemon configuration command telnet_port */
 564 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 565 {
 566         if (argc == 0)
 567                 return ERROR_OK;
 568
 569         /* only if the port wasn't overwritten by cmdline */
 570         if (telnet_port == 0)
 571                 telnet_port = strtoul(args[0], NULL, 0);
 572
 573         return ERROR_OK;
 574 }
 575
 576 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 577 {
 578         return ERROR_COMMAND_CLOSE_CONNECTION;
 579 }