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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
  54 /* The only way we can detect that the socket is closed is the first time
  55  * we write to it, we will fail. Subsequent write operations will
  56  * succeed. Shudder!
  57  */
  58 int telnet_write(connection_t *connection, void *data, int len)
  59 {
  60         telnet_connection_t *t_con = connection->priv;
  61         if (t_con->closed)
  62                 return ERROR_SERVER_REMOTE_CLOSED;
  63
  64         if (write_socket(connection->fd, data, len)==len)
  65         {
  66                 return ERROR_OK;
  67         }
  68         t_con->closed=1;
  69         return ERROR_SERVER_REMOTE_CLOSED;
  70 }
  71
  72
  73 int telnet_prompt(connection_t *connection)
  74 {
  75         telnet_connection_t *t_con = connection->priv;
  76
  77         return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
  78 }
  79
  80 int telnet_outputline(connection_t *connection, char* line)
  81 {
  82         telnet_write(connection, line, strlen(line));
  83         return telnet_write(connection, "\r\n\0", 3);
  84 }
  85
  86
  87 int telnet_output(struct command_context_s *cmd_ctx, char* line)
  88 {
  89         connection_t *connection = cmd_ctx->output_handler_priv;
  90
  91         return telnet_outputline(connection, line);
  92 }
  93
  94 void telnet_log_callback(void *priv, const char *file, int line,
  95                 const char *function, const char *format, va_list args)
  96 {
  97         connection_t *connection = priv;
  98         char *t=allocPrintf(format, args);
  99         if (t==NULL)
 100                 return;
 101
 102         telnet_outputline(connection, t);
 103
 104         free(t);
 105 }
 106
 107
 108 int telnet_target_callback_event_handler(struct target_s *target, enum target_event event, void *priv)
 109 {
 110         struct command_context_s *cmd_ctx = priv;
 111         char buffer[512];
 112
 113         switch (event)
 114         {
 115                 case TARGET_EVENT_HALTED:
 116                         command_print(cmd_ctx, "Target %i halted", get_num_by_target(target));
 117                         target->type->arch_state(target, buffer, 512);
 118                         buffer[511] = 0;
 119                         command_print(cmd_ctx, "%s", buffer);
 120                         break;
 121                 case TARGET_EVENT_RESUMED:
 122                         command_print(cmd_ctx, "Target %i resumed", get_num_by_target(target));
 123                         break;
 124                 default:
 125                         break;
 126         }
 127
 128         return ERROR_OK;
 129 }
 130
 131 int telnet_new_connection(connection_t *connection)
 132 {
 133         telnet_connection_t *telnet_connection = malloc(sizeof(telnet_connection_t));
 134         telnet_service_t *telnet_service = connection->service->priv;
 135         int i;
 136
 137         connection->priv = telnet_connection;
 138
 139         /* initialize telnet connection information */
 140         telnet_connection->closed = 0;
 141         telnet_connection->line_size = 0;
 142         telnet_connection->line_cursor = 0;
 143         telnet_connection->option_size = 0;
 144         telnet_connection->prompt = strdup("> ");
 145         telnet_connection->state = TELNET_STATE_DATA;
 146
 147         /* output goes through telnet connection */
 148         command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
 149
 150         /* negotiate telnet options */
 151         telnet_write(connection, negotiate, strlen(negotiate));
 152
 153         /* print connection banner */
 154         if (telnet_service->banner)
 155         {
 156                 telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
 157                 telnet_write(connection, "\r\n\0", 3);
 158         }
 159
 160         telnet_prompt(connection);
 161
 162         /* initialize history */
 163         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 164         {
 165                 telnet_connection->history[i] = NULL;
 166         }
 167         telnet_connection->next_history = 0;
 168         telnet_connection->current_history = 0;
 169
 170         target_register_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 171
 172         return ERROR_OK;
 173 }
 174
 175 void telnet_clear_line(connection_t *connection, telnet_connection_t *t_con)
 176 {
 177         /* move to end of line */
 178         if (t_con->line_cursor < t_con->line_size)
 179         {
 180                 telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 181         }
 182
 183         /* backspace, overwrite with space, backspace */
 184         while (t_con->line_size > 0)
 185         {
 186                 telnet_write(connection, "\b \b", 3);
 187                 t_con->line_size--;
 188         }
 189         t_con->line_cursor = 0;
 190 }
 191
 192 int telnet_input(connection_t *connection)
 193 {
 194         int bytes_read;
 195         char buffer[TELNET_BUFFER_SIZE];
 196         char *buf_p;
 197         telnet_connection_t *t_con = connection->priv;
 198         command_context_t *command_context = connection->cmd_ctx;
 199
 200         bytes_read = read_socket(connection->fd, buffer, TELNET_BUFFER_SIZE);
 201
 202         if (bytes_read == 0)
 203                 return ERROR_SERVER_REMOTE_CLOSED;
 204         else if (bytes_read == -1)
 205         {
 206                 ERROR("error during read: %s", strerror(errno));
 207                 return ERROR_SERVER_REMOTE_CLOSED;
 208         }
 209
 210         buf_p = buffer;
 211         while (bytes_read)
 212         {
 213                 switch (t_con->state)
 214                 {
 215                         case TELNET_STATE_DATA:
 216                                 if (*buf_p == '\xff')
 217                                 {
 218                                         t_con->state = TELNET_STATE_IAC;
 219                                 }
 220                                 else
 221                                 {
 222                                         if (isprint(*buf_p)) /* printable character */
 223                                         {
 224                                                 telnet_write(connection, buf_p, 1);
 225                                                 if (t_con->line_cursor == t_con->line_size)
 226                                                 {
 227                                                         t_con->line[t_con->line_size++] = *buf_p;
 228                                                         t_con->line_cursor++;
 229                                                 }
 230                                                 else
 231                                                 {
 232                                                         int i;
 233                                                         memmove(t_con->line + t_con->line_cursor + 1, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 234                                                         t_con->line[t_con->line_cursor++] = *buf_p;
 235                                                         t_con->line_size++;
 236                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 237                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 238                                                         {
 239                                                                 telnet_write(connection, "\b", 1);
 240                                                         }
 241                                                 }
 242                                         }
 243                                         else /* non-printable */
 244                                         {
 245                                                 if (*buf_p == 0x1b) /* escape */
 246                                                 {
 247                                                         t_con->state = TELNET_STATE_ESCAPE;
 248                                                         t_con->last_escape = '\x00';
 249                                                 }
 250                                                 else if ((*buf_p == 0xd) || (*buf_p == 0xa)) /* CR/LF */
 251                                                 {
 252                                                         int retval;
 253
 254                                                         /* skip over combinations with CR/LF + NUL */
 255                                                         if (((*(buf_p + 1) == 0xa) || (*(buf_p + 1) == 0xd)) && (bytes_read > 1))
 256                                                         {
 257                                                                 buf_p++;
 258                                                                 bytes_read--;
 259                                                         }
 260                                                         if ((*(buf_p + 1) == 0) && (bytes_read > 1))
 261                                                         {
 262                                                                 buf_p++;
 263                                                                 bytes_read--;
 264                                                         }
 265                                                         t_con->line[t_con->line_size] = 0;
 266
 267                                                         telnet_write(connection, "\r\n\x00", 3);
 268
 269                                                         if (strcmp(t_con->line, "history") == 0)
 270                                                         {
 271                                                                 int i;
 272                                                                 for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 273                                                                 {
 274                                                                         if (t_con->history[i])
 275                                                                         {
 276                                                                                 telnet_write(connection, t_con->history[i], strlen(t_con->history[i]));
 277                                                                                 telnet_write(connection, "\r\n\x00", 3);
 278                                                                         }
 279                                                                 }
 280                                                                 telnet_prompt(connection);
 281                                                                 t_con->line_size = 0;
 282                                                                 t_con->line_cursor = 0;
 283                                                                 continue;
 284                                                         }
 285
 286                                                         log_setCallback(telnet_log_callback, connection);
 287
 288                                                         if ((retval = command_run_line(command_context, t_con->line)) != ERROR_OK)
 289                                                         {
 290                                                                 if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
 291                                                                 {
 292                                                                         return ERROR_SERVER_REMOTE_CLOSED;
 293                                                                 }
 294                                                         }
 295
 296                                                         /* Save only non-blank lines in the history */
 297                                                         if (t_con->line_size > 0)
 298                                                         {
 299                                                                 /* if the history slot is already taken, free it */
 300                                                                 if (t_con->history[t_con->next_history])
 301                                                                 {
 302                                                                         free(t_con->history[t_con->next_history]);
 303                                                                 }
 304
 305                                                                 /* add line to history */
 306                                                                 t_con->history[t_con->next_history] = strdup(t_con->line);
 307
 308                                                                 /* wrap history at TELNET_LINE_HISTORY_SIZE */
 309                                                                 t_con->next_history = (t_con->next_history + 1) % TELNET_LINE_HISTORY_SIZE;
 310
 311                                                                 /* current history line starts at the new entry */
 312                                                                 t_con->current_history = t_con->next_history;
 313
 314                                                                 if (t_con->history[t_con->current_history])
 315                                                                 {
 316                                                                         free(t_con->history[t_con->current_history]);
 317                                                                 }
 318                                                                 t_con->history[t_con->current_history] = strdup("");
 319                                                         }
 320
 321                                                         int t=telnet_prompt(connection);
 322                                                         if (t==ERROR_SERVER_REMOTE_CLOSED)
 323                                                                 return t;
 324
 325                                                         t_con->line_size = 0;
 326                                                         t_con->line_cursor = 0;
 327                                                 }
 328                                                 else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) /* delete character */
 329                                                 {
 330                                                         if (t_con->line_cursor > 0)
 331                                                         {
 332                                                                 if (t_con->line_cursor != t_con->line_size)
 333                                                                 {
 334                                                                         int i;
 335                                                                         telnet_write(connection, "\b", 1);
 336                                                                         t_con->line_cursor--;
 337                                                                         t_con->line_size--;
 338                                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 339
 340                                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 341                                                                         telnet_write(connection, " \b", 2);
 342                                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 343                                                                         {
 344                                                                                 telnet_write(connection, "\b", 1);
 345                                                                         }
 346                                                                 }
 347                                                                 else
 348                                                                 {
 349                                                                         t_con->line_size--;
 350                                                                         t_con->line_cursor--;
 351                                                                         /* back space: move the 'printer' head one char back, overwrite with space, move back again */
 352                                                                         telnet_write(connection, "\b \b", 3);
 353                                                                 }
 354                                                         }
 355                                                 }
 356                                                 else if (*buf_p == 0x15) /* clear line */
 357                                                 {
 358                                                         telnet_clear_line(connection, t_con);
 359                                                 }
 360                                                 else if (*buf_p == CTRL('B')) /* cursor left */
 361                                                 {
 362                                                         if (t_con->line_cursor > 0)
 363                                                         {
 364                                                                 telnet_write(connection, "\b", 1);
 365                                                                 t_con->line_cursor--;
 366                                                         }
 367                                                         t_con->state = TELNET_STATE_DATA;
 368                                                 }
 369                                                 else if (*buf_p == CTRL('F')) /* cursor right */
 370                                                 {
 371                                                         if (t_con->line_cursor < t_con->line_size)
 372                                                         {
 373                                                                 telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 374                                                         }
 375                                                         t_con->state = TELNET_STATE_DATA;
 376                                                 }
 377                                                 else
 378                                                 {
 379                                                         DEBUG("unhandled nonprintable: %2.2x", *buf_p);
 380                                                 }
 381                                         }
 382                                 }
 383                                 break;
 384                         case TELNET_STATE_IAC:
 385                                 switch (*buf_p)
 386                                 {
 387                                         case '\xfe':
 388                                                 t_con->state = TELNET_STATE_DONT;
 389                                                 break;
 390                                         case '\xfd':
 391                                                 t_con->state = TELNET_STATE_DO;
 392                                                 break;
 393                                         case '\xfc':
 394                                                 t_con->state = TELNET_STATE_WONT;
 395                                                 break;
 396                                         case '\xfb':
 397                                                 t_con->state = TELNET_STATE_WILL;
 398                                                 break;
 399                                 }
 400                                 break;
 401                         case TELNET_STATE_SB:
 402                                 break;
 403                         case TELNET_STATE_SE:
 404                                 break;
 405                         case TELNET_STATE_WILL:
 406                         case TELNET_STATE_WONT:
 407                         case TELNET_STATE_DO:
 408                         case TELNET_STATE_DONT:
 409                                 t_con->state = TELNET_STATE_DATA;
 410                                 break;
 411                         case TELNET_STATE_ESCAPE:
 412                                 if (t_con->last_escape == '[')
 413                                 {
 414                                         if (*buf_p == 'D') /* cursor left */
 415                                         {
 416                                                 if (t_con->line_cursor > 0)
 417                                                 {
 418                                                         telnet_write(connection, "\b", 1);
 419                                                         t_con->line_cursor--;
 420                                                 }
 421                                                 t_con->state = TELNET_STATE_DATA;
 422                                         }
 423                                         else if (*buf_p == 'C') /* cursor right */
 424                                         {
 425                                                 if (t_con->line_cursor < t_con->line_size)
 426                                                 {
 427                                                         telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
 428                                                 }
 429                                                 t_con->state = TELNET_STATE_DATA;
 430                                         }
 431                                         else if (*buf_p == 'A') /* cursor up */
 432                                         {
 433                                                 int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
 434                                                 if (t_con->history[last_history])
 435                                                 {
 436                                                         telnet_clear_line(connection, t_con);
 437                                                         t_con->line_size = strlen(t_con->history[last_history]);
 438                                                         t_con->line_cursor = t_con->line_size;
 439                                                         memcpy(t_con->line, t_con->history[last_history], t_con->line_size + 1);
 440                                                         telnet_write(connection, t_con->line, t_con->line_size);
 441                                                         t_con->current_history = last_history;
 442                                                 }
 443                                                 t_con->state = TELNET_STATE_DATA;
 444                                         }
 445                                         else if (*buf_p == 'B') /* cursor down */
 446                                         {
 447                                                 int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
 448                                                 if (t_con->history[next_history])
 449                                                 {
 450                                                         telnet_clear_line(connection, t_con);
 451                                                         t_con->line_size = strlen(t_con->history[next_history]);
 452                                                         t_con->line_cursor = t_con->line_size;
 453                                                         memcpy(t_con->line, t_con->history[next_history], t_con->line_size + 1);
 454                                                         telnet_write(connection, t_con->line, t_con->line_size);
 455                                                         t_con->current_history = next_history;
 456                                                 }
 457                                                 t_con->state = TELNET_STATE_DATA;
 458                                         }
 459                                         else if (*buf_p == '3')
 460                                         {
 461                                                 t_con->last_escape = *buf_p;
 462                                         }
 463                                         else
 464                                         {
 465                                                 t_con->state = TELNET_STATE_DATA;
 466                                         }
 467                                 }
 468                                 else if (t_con->last_escape == '3')
 469                                 {
 470                                         /* Remove character */
 471                                         if (*buf_p == '~')
 472                                         {
 473                                                 if (t_con->line_cursor < t_con->line_size)
 474                                                 {
 475                                                         int i;
 476                                                         t_con->line_size--;
 477                                                         /* remove char from line buffer */
 478                                                         memmove(t_con->line + t_con->line_cursor, t_con->line + t_con->line_cursor + 1, t_con->line_size - t_con->line_cursor);
 479
 480                                                         /* print remainder of buffer */
 481                                                         telnet_write(connection, t_con->line + t_con->line_cursor, t_con->line_size - t_con->line_cursor);
 482                                                         /* overwrite last char with whitespace */
 483                                                         telnet_write(connection, " \b", 2);
 484
 485                                                         /* move back to cursor position*/
 486                                                         for (i = t_con->line_cursor; i < t_con->line_size; i++)
 487                                                         {
 488                                                                 telnet_write(connection, "\b", 1);
 489                                                         }
 490                                                 }
 491
 492                                                 t_con->state = TELNET_STATE_DATA;
 493                                         }
 494                                         else
 495                                         {
 496                                                 t_con->state = TELNET_STATE_DATA;
 497                                         }
 498                                 }
 499                                 else if (t_con->last_escape == '\x00')
 500                                 {
 501                                         if (*buf_p == '[')
 502                                         {
 503                                                 t_con->last_escape = *buf_p;
 504                                         }
 505                                         else
 506                                         {
 507                                                 t_con->state = TELNET_STATE_DATA;
 508                                         }
 509                                 }
 510                                 else
 511                                 {
 512                                         ERROR("BUG: unexpected value in t_con->last_escape");
 513                                         t_con->state = TELNET_STATE_DATA;
 514                                 }
 515
 516                                 break;
 517                         default:
 518                                 ERROR("unknown telnet state");
 519                                 exit(-1);
 520                 }
 521
 522                 bytes_read--;
 523                 buf_p++;
 524         }
 525
 526         return ERROR_OK;
 527 }
 528
 529 int telnet_connection_closed(connection_t *connection)
 530 {
 531         telnet_connection_t *t_con = connection->priv;
 532         int i;
 533
 534         if (t_con->prompt)
 535         {
 536                 free(t_con->prompt);
 537                 t_con->prompt = NULL;
 538         }
 539
 540         for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
 541         {
 542                 if (t_con->history[i])
 543                 {
 544                         free(t_con->history[i]);
 545                         t_con->history[i] = NULL;
 546                 }
 547         }
 548
 549         /* if this connection registered a debug-message receiver delete it */
 550         delete_debug_msg_receiver(connection->cmd_ctx, NULL);
 551
 552         if (connection->priv)
 553         {
 554                 free(connection->priv);
 555                 connection->priv = NULL;
 556         }
 557         else
 558         {
 559                 ERROR("BUG: connection->priv == NULL");
 560         }
 561
 562         target_unregister_event_callback(telnet_target_callback_event_handler, connection->cmd_ctx);
 563
 564         return ERROR_OK;
 565 }
 566
 567 int telnet_set_prompt(connection_t *connection, char *prompt)
 568 {
 569         telnet_connection_t *t_con = connection->priv;
 570
 571         t_con->prompt = strdup(prompt);
 572
 573         return ERROR_OK;
 574 }
 575
 576 int telnet_init(char *banner)
 577 {
 578         telnet_service_t *telnet_service = malloc(sizeof(telnet_service_t));
 579
 580         if (telnet_port == 0)
 581         {
 582                 WARNING("no telnet port specified, using default port 4444");
 583                 telnet_port = 4444;
 584         }
 585
 586         telnet_service->banner = banner;
 587
 588         add_service("telnet", CONNECTION_TELNET, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
 589
 590         return ERROR_OK;
 591 }
 592
 593 int telnet_register_commands(command_context_t *command_context)
 594 {
 595         register_command(command_context, NULL, "exit", handle_exit_command,
 596                                          COMMAND_EXEC, "exit telnet session");
 597
 598         register_command(command_context, NULL, "telnet_port", handle_telnet_port_command,
 599                                          COMMAND_CONFIG, "");
 600
 601         return ERROR_OK;
 602 }
 603
 604 /* daemon configuration command telnet_port */
 605 int handle_telnet_port_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 606 {
 607         if (argc == 0)
 608                 return ERROR_OK;
 609
 610         /* only if the port wasn't overwritten by cmdline */
 611         if (telnet_port == 0)
 612                 telnet_port = strtoul(args[0], NULL, 0);
 613
 614         return ERROR_OK;
 615 }
 616
 617 int handle_exit_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 618 {
 619         return ERROR_COMMAND_CLOSE_CONNECTION;
 620 }