appl/telnet/telnetd/state.c

   1 /*
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "telnetd.h"
  35
  36 RCSID("$Id$");
  37
  38 unsigned char   doopt[] = { IAC, DO, '%', 'c', 0 };
  39 unsigned char   dont[] = { IAC, DONT, '%', 'c', 0 };
  40 unsigned char   will[] = { IAC, WILL, '%', 'c', 0 };
  41 unsigned char   wont[] = { IAC, WONT, '%', 'c', 0 };
  42 int     not42 = 1;
  43
  44 /*
  45  * Buffer for sub-options, and macros
  46  * for suboptions buffer manipulations
  47  */
  48 unsigned char subbuffer[1024*64], *subpointer= subbuffer, *subend= subbuffer;
  49
  50 #define SB_CLEAR()      subpointer = subbuffer
  51 #define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
  52 #define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
  53     *subpointer++ = (c); \
  54                              }
  55 #define SB_GET()        ((*subpointer++)&0xff)
  56 #define SB_EOF()        (subpointer >= subend)
  57 #define SB_LEN()        (subend - subpointer)
  58
  59 #ifdef  ENV_HACK
  60 unsigned char *subsave;
  61 #define SB_SAVE()       subsave = subpointer;
  62 #define SB_RESTORE()    subpointer = subsave;
  63 #endif
  64
  65
  66 /*
  67  * State for recv fsm
  68  */
  69 #define TS_DATA         0       /* base state */
  70 #define TS_IAC          1       /* look for double IAC's */
  71 #define TS_CR           2       /* CR-LF ->'s CR */
  72 #define TS_SB           3       /* throw away begin's... */
  73 #define TS_SE           4       /* ...end's (suboption negotiation) */
  74 #define TS_WILL         5       /* will option negotiation */
  75 #define TS_WONT         6       /* wont -''- */
  76 #define TS_DO           7       /* do -''- */
  77 #define TS_DONT         8       /* dont -''- */
  78
  79 void
  80 telrcv(void)
  81 {
  82     int c;
  83     static int state = TS_DATA;
  84
  85     while (ncc > 0) {
  86         if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
  87             break;
  88         c = *netip++ & 0377, ncc--;
  89 #ifdef ENCRYPTION
  90         if (decrypt_input)
  91             c = (*decrypt_input)(c);
  92 #endif
  93         switch (state) {
  94
  95         case TS_CR:
  96             state = TS_DATA;
  97             /* Strip off \n or \0 after a \r */
  98             if ((c == 0) || (c == '\n')) {
  99                 break;
 100             }
 101             /* FALL THROUGH */
 102
 103         case TS_DATA:
 104             if (c == IAC) {
 105                 state = TS_IAC;
 106                 break;
 107             }
 108             /*
 109              * We now map \r\n ==> \r for pragmatic reasons.
 110              * Many client implementations send \r\n when
 111              * the user hits the CarriageReturn key.
 112              *
 113              * We USED to map \r\n ==> \n, since \r\n says
 114              * that we want to be in column 1 of the next
 115              * printable line, and \n is the standard
 116              * unix way of saying that (\r is only good
 117              * if CRMOD is set, which it normally is).
 118              */
 119             if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 120                 int nc = *netip;
 121 #ifdef ENCRYPTION
 122                 if (decrypt_input)
 123                     nc = (*decrypt_input)(nc & 0xff);
 124 #endif
 125                 {
 126 #ifdef ENCRYPTION
 127                     if (decrypt_input)
 128                         (void)(*decrypt_input)(-1);
 129 #endif
 130                     state = TS_CR;
 131                 }
 132             }
 133             *pfrontp++ = c;
 134             break;
 135
 136         case TS_IAC:
 137         gotiac:                 switch (c) {
 138
 139             /*
 140              * Send the process on the pty side an
 141              * interrupt.  Do this with a NULL or
 142              * interrupt char; depending on the tty mode.
 143              */
 144         case IP:
 145             DIAG(TD_OPTIONS,
 146                  printoption("td: recv IAC", c));
 147             interrupt();
 148             break;
 149
 150         case BREAK:
 151             DIAG(TD_OPTIONS,
 152                  printoption("td: recv IAC", c));
 153             sendbrk();
 154             break;
 155
 156             /*
 157              * Are You There?
 158              */
 159         case AYT:
 160             DIAG(TD_OPTIONS,
 161                  printoption("td: recv IAC", c));
 162             recv_ayt();
 163             break;
 164
 165             /*
 166              * Abort Output
 167              */
 168         case AO:
 169             {
 170                 DIAG(TD_OPTIONS,
 171                      printoption("td: recv IAC", c));
 172                 ptyflush();     /* half-hearted */
 173                 init_termbuf();
 174
 175                 if (slctab[SLC_AO].sptr &&
 176                     *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
 177                     *pfrontp++ =
 178                         (unsigned char)*slctab[SLC_AO].sptr;
 179                 }
 180
 181                 netclear();     /* clear buffer back */
 182                 output_data ("%c%c", IAC, DM);
 183                 neturg = nfrontp-1; /* off by one XXX */
 184                 DIAG(TD_OPTIONS,
 185                      printoption("td: send IAC", DM));
 186                 break;
 187             }
 188
 189         /*
 190          * Erase Character and
 191          * Erase Line
 192          */
 193         case EC:
 194         case EL:
 195             {
 196                 cc_t ch;
 197
 198                 DIAG(TD_OPTIONS,
 199                      printoption("td: recv IAC", c));
 200                 ptyflush();     /* half-hearted */
 201                 init_termbuf();
 202                 if (c == EC)
 203                     ch = *slctab[SLC_EC].sptr;
 204                 else
 205                     ch = *slctab[SLC_EL].sptr;
 206                 if (ch != (cc_t)(_POSIX_VDISABLE))
 207                     *pfrontp++ = (unsigned char)ch;
 208                 break;
 209             }
 210
 211         /*
 212          * Check for urgent data...
 213          */
 214         case DM:
 215             DIAG(TD_OPTIONS,
 216                  printoption("td: recv IAC", c));
 217             SYNCHing = stilloob(net);
 218             settimer(gotDM);
 219             break;
 220
 221
 222             /*
 223              * Begin option subnegotiation...
 224              */
 225         case SB:
 226             state = TS_SB;
 227             SB_CLEAR();
 228             continue;
 229
 230         case WILL:
 231             state = TS_WILL;
 232             continue;
 233
 234         case WONT:
 235             state = TS_WONT;
 236             continue;
 237
 238         case DO:
 239             state = TS_DO;
 240             continue;
 241
 242         case DONT:
 243             state = TS_DONT;
 244             continue;
 245         case EOR:
 246             if (his_state_is_will(TELOPT_EOR))
 247                 doeof();
 248             break;
 249
 250             /*
 251              * Handle RFC 10xx Telnet linemode option additions
 252              * to command stream (EOF, SUSP, ABORT).
 253              */
 254         case xEOF:
 255             doeof();
 256             break;
 257
 258         case SUSP:
 259             sendsusp();
 260             break;
 261
 262         case ABORT:
 263             sendbrk();
 264             break;
 265
 266         case IAC:
 267             *pfrontp++ = c;
 268             break;
 269         }
 270         state = TS_DATA;
 271         break;
 272
 273         case TS_SB:
 274             if (c == IAC) {
 275                 state = TS_SE;
 276             } else {
 277                 SB_ACCUM(c);
 278             }
 279             break;
 280
 281         case TS_SE:
 282             if (c != SE) {
 283                 if (c != IAC) {
 284                     /*
 285                      * bad form of suboption negotiation.
 286                      * handle it in such a way as to avoid
 287                      * damage to local state.  Parse
 288                      * suboption buffer found so far,
 289                      * then treat remaining stream as
 290                      * another command sequence.
 291                      */
 292
 293                     /* for DIAGNOSTICS */
 294                     SB_ACCUM(IAC);
 295                     SB_ACCUM(c);
 296                     subpointer -= 2;
 297
 298                     SB_TERM();
 299                     suboption();
 300                     state = TS_IAC;
 301                     goto gotiac;
 302                 }
 303                 SB_ACCUM(c);
 304                 state = TS_SB;
 305             } else {
 306                 /* for DIAGNOSTICS */
 307                 SB_ACCUM(IAC);
 308                 SB_ACCUM(SE);
 309                 subpointer -= 2;
 310
 311                 SB_TERM();
 312                 suboption();    /* handle sub-option */
 313                 state = TS_DATA;
 314             }
 315             break;
 316
 317         case TS_WILL:
 318             willoption(c);
 319             state = TS_DATA;
 320             continue;
 321
 322         case TS_WONT:
 323             wontoption(c);
 324             if (c==TELOPT_ENCRYPT && his_do_dont_is_changing(TELOPT_ENCRYPT) )
 325                 dontoption(c);
 326             state = TS_DATA;
 327             continue;
 328
 329         case TS_DO:
 330             dooption(c);
 331             state = TS_DATA;
 332             continue;
 333
 334         case TS_DONT:
 335             dontoption(c);
 336             state = TS_DATA;
 337             continue;
 338
 339         default:
 340             syslog(LOG_ERR, "telnetd: panic state=%d\n", state);
 341             printf("telnetd: panic state=%d\n", state);
 342             exit(1);
 343         }
 344     }
 345 }  /* end of telrcv */
 346
 347 /*
 348  * The will/wont/do/dont state machines are based on Dave Borman's
 349  * Telnet option processing state machine.
 350  *
 351  * These correspond to the following states:
 352  *      my_state = the last negotiated state
 353  *      want_state = what I want the state to go to
 354  *      want_resp = how many requests I have sent
 355  * All state defaults are negative, and resp defaults to 0.
 356  *
 357  * When initiating a request to change state to new_state:
 358  *
 359  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 360  *      do nothing;
 361  * } else {
 362  *      want_state = new_state;
 363  *      send new_state;
 364  *      want_resp++;
 365  * }
 366  *
 367  * When receiving new_state:
 368  *
 369  * if (want_resp) {
 370  *      want_resp--;
 371  *      if (want_resp && (new_state == my_state))
 372  *              want_resp--;
 373  * }
 374  * if ((want_resp == 0) && (new_state != want_state)) {
 375  *      if (ok_to_switch_to new_state)
 376  *              want_state = new_state;
 377  *      else
 378  *              want_resp++;
 379  *      send want_state;
 380  * }
 381  * my_state = new_state;
 382  *
 383  * Note that new_state is implied in these functions by the function itself.
 384  * will and do imply positive new_state, wont and dont imply negative.
 385  *
 386  * Finally, there is one catch.  If we send a negative response to a
 387  * positive request, my_state will be the positive while want_state will
 388  * remain negative.  my_state will revert to negative when the negative
 389  * acknowlegment arrives from the peer.  Thus, my_state generally tells
 390  * us not only the last negotiated state, but also tells us what the peer
 391  * wants to be doing as well.  It is important to understand this difference
 392  * as we may wish to be processing data streams based on our desired state
 393  * (want_state) or based on what the peer thinks the state is (my_state).
 394  *
 395  * This all works fine because if the peer sends a positive request, the data
 396  * that we receive prior to negative acknowlegment will probably be affected
 397  * by the positive state, and we can process it as such (if we can; if we
 398  * can't then it really doesn't matter).  If it is that important, then the
 399  * peer probably should be buffering until this option state negotiation
 400  * is complete.
 401  *
 402  */
 403 void
 404 send_do(int option, int init)
 405 {
 406     if (init) {
 407         if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
 408             his_want_state_is_will(option))
 409             return;
 410         /*
 411          * Special case for TELOPT_TM:  We send a DO, but pretend
 412          * that we sent a DONT, so that we can send more DOs if
 413          * we want to.
 414          */
 415         if (option == TELOPT_TM)
 416             set_his_want_state_wont(option);
 417         else
 418             set_his_want_state_will(option);
 419         do_dont_resp[option]++;
 420     }
 421     output_data((const char *)doopt, option);
 422
 423     DIAG(TD_OPTIONS, printoption("td: send do", option));
 424 }
 425
 426 #ifdef  AUTHENTICATION
 427 extern void auth_request(void);
 428 #endif
 429 #ifdef  ENCRYPTION
 430 extern void encrypt_send_support(void);
 431 #endif
 432
 433 void
 434 willoption(int option)
 435 {
 436     int changeok = 0;
 437     void (*func)(void) = NULL;
 438
 439     /*
 440      * process input from peer.
 441      */
 442
 443     DIAG(TD_OPTIONS, printoption("td: recv will", option));
 444
 445     if (do_dont_resp[option]) {
 446         do_dont_resp[option]--;
 447         if (do_dont_resp[option] && his_state_is_will(option))
 448             do_dont_resp[option]--;
 449     }
 450     if (do_dont_resp[option] == 0) {
 451         if (his_want_state_is_wont(option)) {
 452             switch (option) {
 453
 454             case TELOPT_BINARY:
 455                 init_termbuf();
 456                 tty_binaryin(1);
 457                 set_termbuf();
 458                 changeok++;
 459                 break;
 460
 461             case TELOPT_ECHO:
 462                 /*
 463                  * See comments below for more info.
 464                  */
 465                 not42 = 0;      /* looks like a 4.2 system */
 466                 break;
 467
 468             case TELOPT_TM:
 469                 /*
 470                  * We never respond to a WILL TM, and
 471                  * we leave the state WONT.
 472                  */
 473                 return;
 474
 475             case TELOPT_LFLOW:
 476                 /*
 477                  * If we are going to support flow control
 478                  * option, then don't worry peer that we can't
 479                  * change the flow control characters.
 480                  */
 481                 slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 482                 slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 483                 slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 484                 slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 485             case TELOPT_TTYPE:
 486             case TELOPT_SGA:
 487             case TELOPT_NAWS:
 488             case TELOPT_TSPEED:
 489             case TELOPT_XDISPLOC:
 490             case TELOPT_NEW_ENVIRON:
 491             case TELOPT_OLD_ENVIRON:
 492                 changeok++;
 493                 break;
 494
 495
 496 #ifdef  AUTHENTICATION
 497             case TELOPT_AUTHENTICATION:
 498                 func = auth_request;
 499                 changeok++;
 500                 break;
 501 #endif
 502
 503 #ifdef  ENCRYPTION
 504             case TELOPT_ENCRYPT:
 505                 func = encrypt_send_support;
 506                 changeok++;
 507                 break;
 508 #endif
 509
 510             default:
 511                 break;
 512             }
 513             if (changeok) {
 514                 set_his_want_state_will(option);
 515                 send_do(option, 0);
 516             } else {
 517                 do_dont_resp[option]++;
 518                 send_dont(option, 0);
 519             }
 520         } else {
 521             /*
 522              * Option processing that should happen when
 523              * we receive conformation of a change in
 524              * state that we had requested.
 525              */
 526             switch (option) {
 527             case TELOPT_ECHO:
 528                 not42 = 0;      /* looks like a 4.2 system */
 529                 /*
 530                  * Egads, he responded "WILL ECHO".  Turn
 531                  * it off right now!
 532                  */
 533                 send_dont(option, 1);
 534                 /*
 535                  * "WILL ECHO".  Kludge upon kludge!
 536                  * A 4.2 client is now echoing user input at
 537                  * the tty.  This is probably undesireable and
 538                  * it should be stopped.  The client will
 539                  * respond WONT TM to the DO TM that we send to
 540                  * check for kludge linemode.  When the WONT TM
 541                  * arrives, linemode will be turned off and a
 542                  * change propogated to the pty.  This change
 543                  * will cause us to process the new pty state
 544                  * in localstat(), which will notice that
 545                  * linemode is off and send a WILL ECHO
 546                  * so that we are properly in character mode and
 547                  * all is well.
 548                  */
 549                 break;
 550
 551 #ifdef  AUTHENTICATION
 552             case TELOPT_AUTHENTICATION:
 553                 func = auth_request;
 554                 break;
 555 #endif
 556
 557 #ifdef  ENCRYPTION
 558             case TELOPT_ENCRYPT:
 559                 func = encrypt_send_support;
 560                 break;
 561 #endif
 562
 563             case TELOPT_LFLOW:
 564                 func = flowstat;
 565                 break;
 566             }
 567         }
 568     }
 569     set_his_state_will(option);
 570     if (func)
 571         (*func)();
 572 }  /* end of willoption */
 573
 574 void
 575 send_dont(int option, int init)
 576 {
 577     if (init) {
 578         if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 579             his_want_state_is_wont(option))
 580             return;
 581         set_his_want_state_wont(option);
 582         do_dont_resp[option]++;
 583     }
 584     output_data((const char *)dont, option);
 585
 586     DIAG(TD_OPTIONS, printoption("td: send dont", option));
 587 }
 588
 589 void
 590 wontoption(int option)
 591 {
 592     /*
 593      * Process client input.
 594          */
 595
 596     DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 597
 598     if (do_dont_resp[option]) {
 599         do_dont_resp[option]--;
 600         if (do_dont_resp[option] && his_state_is_wont(option))
 601             do_dont_resp[option]--;
 602     }
 603     if (do_dont_resp[option] == 0) {
 604         if (his_want_state_is_will(option)) {
 605             /* it is always ok to change to negative state */
 606             switch (option) {
 607             case TELOPT_ECHO:
 608                 not42 = 1; /* doesn't seem to be a 4.2 system */
 609                 break;
 610
 611             case TELOPT_BINARY:
 612                 init_termbuf();
 613                 tty_binaryin(0);
 614                 set_termbuf();
 615                 break;
 616
 617             case TELOPT_TM:
 618                 /*
 619                  * If we get a WONT TM, and had sent a DO TM,
 620                  * don't respond with a DONT TM, just leave it
 621                  * as is.  Short circut the state machine to
 622                  * achive this.
 623                  */
 624                 set_his_want_state_wont(TELOPT_TM);
 625                 return;
 626
 627             case TELOPT_LFLOW:
 628                 /*
 629                  * If we are not going to support flow control
 630                  * option, then let peer know that we can't
 631                  * change the flow control characters.
 632                  */
 633                 slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 634                 slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 635                 slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 636                 slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 637                 break;
 638
 639 #ifdef AUTHENTICATION
 640             case TELOPT_AUTHENTICATION:
 641                 auth_finished(0, AUTH_REJECT);
 642                 break;
 643 #endif
 644
 645                 /*
 646                  * For options that we might spin waiting for
 647                  * sub-negotiation, if the client turns off the
 648                  * option rather than responding to the request,
 649                  * we have to treat it here as if we got a response
 650                  * to the sub-negotiation, (by updating the timers)
 651                  * so that we'll break out of the loop.
 652                  */
 653             case TELOPT_TTYPE:
 654                 settimer(ttypesubopt);
 655                 break;
 656
 657             case TELOPT_TSPEED:
 658                 settimer(tspeedsubopt);
 659                 break;
 660
 661             case TELOPT_XDISPLOC:
 662                 settimer(xdisplocsubopt);
 663                 break;
 664
 665             case TELOPT_OLD_ENVIRON:
 666                 settimer(oenvironsubopt);
 667                 break;
 668
 669             case TELOPT_NEW_ENVIRON:
 670                 settimer(environsubopt);
 671                 break;
 672
 673             default:
 674                 break;
 675             }
 676             set_his_want_state_wont(option);
 677             if (his_state_is_will(option))
 678                 send_dont(option, 0);
 679         } else {
 680             switch (option) {
 681             case TELOPT_TM:
 682                 break;
 683
 684 #ifdef AUTHENTICATION
 685             case TELOPT_AUTHENTICATION:
 686                 auth_finished(0, AUTH_REJECT);
 687                 break;
 688 #endif
 689             default:
 690                 break;
 691             }
 692         }
 693     }
 694     set_his_state_wont(option);
 695
 696 }  /* end of wontoption */
 697
 698 void
 699 send_will(int option, int init)
 700 {
 701     if (init) {
 702         if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 703             my_want_state_is_will(option))
 704             return;
 705         set_my_want_state_will(option);
 706         will_wont_resp[option]++;
 707     }
 708     output_data ((const char *)will, option);
 709
 710     DIAG(TD_OPTIONS, printoption("td: send will", option));
 711 }
 712
 713 /*
 714  * When we get a DONT SGA, we will try once to turn it
 715  * back on.  If the other side responds DONT SGA, we
 716  * leave it at that.  This is so that when we talk to
 717  * clients that understand KLUDGELINEMODE but not LINEMODE,
 718  * we'll keep them in char-at-a-time mode.
 719  */
 720 int turn_on_sga = 0;
 721
 722 void
 723 dooption(int option)
 724 {
 725     int changeok = 0;
 726
 727     /*
 728      * Process client input.
 729      */
 730
 731     DIAG(TD_OPTIONS, printoption("td: recv do", option));
 732
 733     if (will_wont_resp[option]) {
 734         will_wont_resp[option]--;
 735         if (will_wont_resp[option] && my_state_is_will(option))
 736             will_wont_resp[option]--;
 737     }
 738     if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 739         switch (option) {
 740         case TELOPT_ECHO:
 741             {
 742                 init_termbuf();
 743                 tty_setecho(1);
 744                 set_termbuf();
 745             }
 746         changeok++;
 747         break;
 748
 749         case TELOPT_BINARY:
 750             init_termbuf();
 751             tty_binaryout(1);
 752             set_termbuf();
 753             changeok++;
 754             break;
 755
 756         case TELOPT_SGA:
 757             turn_on_sga = 0;
 758             changeok++;
 759             break;
 760
 761         case TELOPT_STATUS:
 762             changeok++;
 763             break;
 764
 765         case TELOPT_TM:
 766             /*
 767              * Special case for TM.  We send a WILL, but
 768              * pretend we sent a WONT.
 769              */
 770             send_will(option, 0);
 771             set_my_want_state_wont(option);
 772             set_my_state_wont(option);
 773             return;
 774
 775         case TELOPT_LOGOUT:
 776             /*
 777              * When we get a LOGOUT option, respond
 778              * with a WILL LOGOUT, make sure that
 779              * it gets written out to the network,
 780              * and then just go away...
 781              */
 782             set_my_want_state_will(TELOPT_LOGOUT);
 783             send_will(TELOPT_LOGOUT, 0);
 784             set_my_state_will(TELOPT_LOGOUT);
 785             netflush();
 786             cleanup(0);
 787             /* NOT REACHED */
 788             break;
 789
 790 #ifdef ENCRYPTION
 791         case TELOPT_ENCRYPT:
 792             changeok++;
 793             break;
 794 #endif
 795         case TELOPT_LINEMODE:
 796         case TELOPT_TTYPE:
 797         case TELOPT_NAWS:
 798         case TELOPT_TSPEED:
 799         case TELOPT_LFLOW:
 800         case TELOPT_XDISPLOC:
 801 #ifdef  TELOPT_ENVIRON
 802         case TELOPT_NEW_ENVIRON:
 803 #endif
 804         case TELOPT_OLD_ENVIRON:
 805         default:
 806             break;
 807         }
 808         if (changeok) {
 809             set_my_want_state_will(option);
 810             send_will(option, 0);
 811         } else {
 812             will_wont_resp[option]++;
 813             send_wont(option, 0);
 814         }
 815     }
 816     set_my_state_will(option);
 817
 818 }  /* end of dooption */
 819
 820 void
 821 send_wont(int option, int init)
 822 {
 823     if (init) {
 824         if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 825             my_want_state_is_wont(option))
 826             return;
 827         set_my_want_state_wont(option);
 828         will_wont_resp[option]++;
 829     }
 830     output_data ((const char *)wont, option);
 831
 832     DIAG(TD_OPTIONS, printoption("td: send wont", option));
 833 }
 834
 835 void
 836 dontoption(int option)
 837 {
 838     /*
 839      * Process client input.
 840          */
 841
 842
 843     DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 844
 845     if (will_wont_resp[option]) {
 846         will_wont_resp[option]--;
 847         if (will_wont_resp[option] && my_state_is_wont(option))
 848             will_wont_resp[option]--;
 849     }
 850     if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 851         switch (option) {
 852         case TELOPT_BINARY:
 853             init_termbuf();
 854             tty_binaryout(0);
 855             set_termbuf();
 856             break;
 857
 858         case TELOPT_ECHO:       /* we should stop echoing */
 859             {
 860                 init_termbuf();
 861                 tty_setecho(0);
 862                 set_termbuf();
 863             }
 864         break;
 865
 866         case TELOPT_SGA:
 867             set_my_want_state_wont(option);
 868             if (my_state_is_will(option))
 869                 send_wont(option, 0);
 870             set_my_state_wont(option);
 871             if (turn_on_sga ^= 1)
 872                 send_will(option, 1);
 873             return;
 874
 875         default:
 876             break;
 877         }
 878
 879         set_my_want_state_wont(option);
 880         if (my_state_is_will(option))
 881             send_wont(option, 0);
 882     }
 883     set_my_state_wont(option);
 884
 885 }  /* end of dontoption */
 886
 887 #ifdef  ENV_HACK
 888 int env_ovar = -1;
 889 int env_ovalue = -1;
 890 #else   /* ENV_HACK */
 891 # define env_ovar OLD_ENV_VAR
 892 # define env_ovalue OLD_ENV_VALUE
 893 #endif  /* ENV_HACK */
 894
 895 /*
 896  * suboption()
 897  *
 898  *      Look at the sub-option buffer, and try to be helpful to the other
 899  * side.
 900  *
 901  *      Currently we recognize:
 902  *
 903  *      Terminal type is
 904  *      Linemode
 905  *      Window size
 906  *      Terminal speed
 907  */
 908 void
 909 suboption(void)
 910 {
 911     int subchar;
 912
 913     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
 914
 915     subchar = SB_GET();
 916     switch (subchar) {
 917     case TELOPT_TSPEED: {
 918         int xspeed, rspeed;
 919
 920         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
 921             break;
 922
 923         settimer(tspeedsubopt);
 924
 925         if (SB_EOF() || SB_GET() != TELQUAL_IS)
 926             return;
 927
 928         xspeed = atoi((char *)subpointer);
 929
 930         while (SB_GET() != ',' && !SB_EOF());
 931         if (SB_EOF())
 932             return;
 933
 934         rspeed = atoi((char *)subpointer);
 935         clientstat(TELOPT_TSPEED, xspeed, rspeed);
 936
 937         break;
 938
 939     }  /* end of case TELOPT_TSPEED */
 940
 941     case TELOPT_TTYPE: {                /* Yaaaay! */
 942         char *p;
 943
 944         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
 945             break;
 946         settimer(ttypesubopt);
 947
 948         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
 949             return;             /* ??? XXX but, this is the most robust */
 950         }
 951
 952         p = terminaltype;
 953
 954         while ((p < (terminaltype + sizeof terminaltype-1)) &&
 955                !SB_EOF()) {
 956             int c;
 957
 958             c = SB_GET();
 959             if (isupper(c)) {
 960                 c = tolower(c);
 961             }
 962             *p++ = c;    /* accumulate name */
 963         }
 964         *p = 0;
 965         break;
 966     }  /* end of case TELOPT_TTYPE */
 967
 968     case TELOPT_NAWS: {
 969         int xwinsize, ywinsize;
 970
 971         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
 972             break;
 973
 974         if (SB_EOF())
 975             return;
 976         xwinsize = SB_GET() << 8;
 977         if (SB_EOF())
 978             return;
 979         xwinsize |= SB_GET();
 980         if (SB_EOF())
 981             return;
 982         ywinsize = SB_GET() << 8;
 983         if (SB_EOF())
 984             return;
 985         ywinsize |= SB_GET();
 986         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
 987
 988         break;
 989
 990     }  /* end of case TELOPT_NAWS */
 991
 992     case TELOPT_STATUS: {
 993         int mode;
 994
 995         if (SB_EOF())
 996             break;
 997         mode = SB_GET();
 998         switch (mode) {
 999         case TELQUAL_SEND:
1000             if (my_state_is_will(TELOPT_STATUS))
1001                 send_status();
1002             break;
1003
1004         case TELQUAL_IS:
1005             break;
1006
1007         default:
1008             break;
1009         }
1010         break;
1011     }  /* end of case TELOPT_STATUS */
1012
1013     case TELOPT_XDISPLOC: {
1014         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1015             return;
1016         settimer(xdisplocsubopt);
1017         subpointer[SB_LEN()] = '\0';
1018         esetenv("DISPLAY", (char *)subpointer, 1);
1019         break;
1020     }  /* end of case TELOPT_XDISPLOC */
1021
1022 #ifdef  TELOPT_NEW_ENVIRON
1023     case TELOPT_NEW_ENVIRON:
1024 #endif
1025     case TELOPT_OLD_ENVIRON: {
1026         int c;
1027         char *cp, *varp, *valp;
1028
1029         if (SB_EOF())
1030             return;
1031         c = SB_GET();
1032         if (c == TELQUAL_IS) {
1033             if (subchar == TELOPT_OLD_ENVIRON)
1034                 settimer(oenvironsubopt);
1035             else
1036                 settimer(environsubopt);
1037         } else if (c != TELQUAL_INFO) {
1038             return;
1039         }
1040
1041 #ifdef  TELOPT_NEW_ENVIRON
1042         if (subchar == TELOPT_NEW_ENVIRON) {
1043             while (!SB_EOF()) {
1044                 c = SB_GET();
1045                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1046                     break;
1047             }
1048         } else
1049 #endif
1050             {
1051 #ifdef  ENV_HACK
1052                 /*
1053                  * We only want to do this if we haven't already decided
1054                  * whether or not the other side has its VALUE and VAR
1055                  * reversed.
1056                  */
1057                 if (env_ovar < 0) {
1058                     int last = -1;              /* invalid value */
1059                     int empty = 0;
1060                     int got_var = 0, got_value = 0, got_uservar = 0;
1061
1062                     /*
1063                      * The other side might have its VALUE and VAR values
1064                      * reversed.  To be interoperable, we need to determine
1065                      * which way it is.  If the first recognized character
1066                      * is a VAR or VALUE, then that will tell us what
1067                      * type of client it is.  If the fist recognized
1068                      * character is a USERVAR, then we continue scanning
1069                      * the suboption looking for two consecutive
1070                      * VAR or VALUE fields.  We should not get two
1071                      * consecutive VALUE fields, so finding two
1072                      * consecutive VALUE or VAR fields will tell us
1073                      * what the client is.
1074                      */
1075                     SB_SAVE();
1076                     while (!SB_EOF()) {
1077                         c = SB_GET();
1078                         switch(c) {
1079                         case OLD_ENV_VAR:
1080                             if (last < 0 || last == OLD_ENV_VAR
1081                                 || (empty && (last == OLD_ENV_VALUE)))
1082                                 goto env_ovar_ok;
1083                             got_var++;
1084                             last = OLD_ENV_VAR;
1085                             break;
1086                         case OLD_ENV_VALUE:
1087                             if (last < 0 || last == OLD_ENV_VALUE
1088                                 || (empty && (last == OLD_ENV_VAR)))
1089                                 goto env_ovar_wrong;
1090                             got_value++;
1091                             last = OLD_ENV_VALUE;
1092                             break;
1093                         case ENV_USERVAR:
1094                             /* count strings of USERVAR as one */
1095                             if (last != ENV_USERVAR)
1096                                 got_uservar++;
1097                             if (empty) {
1098                                 if (last == OLD_ENV_VALUE)
1099                                     goto env_ovar_ok;
1100                                 if (last == OLD_ENV_VAR)
1101                                     goto env_ovar_wrong;
1102                             }
1103                             last = ENV_USERVAR;
1104                             break;
1105                         case ENV_ESC:
1106                             if (!SB_EOF())
1107                                 c = SB_GET();
1108                             /* FALL THROUGH */
1109                         default:
1110                             empty = 0;
1111                             continue;
1112                         }
1113                         empty = 1;
1114                     }
1115                     if (empty) {
1116                         if (last == OLD_ENV_VALUE)
1117                             goto env_ovar_ok;
1118                         if (last == OLD_ENV_VAR)
1119                             goto env_ovar_wrong;
1120                     }
1121                     /*
1122                      * Ok, the first thing was a USERVAR, and there
1123                      * are not two consecutive VAR or VALUE commands,
1124                      * and none of the VAR or VALUE commands are empty.
1125                      * If the client has sent us a well-formed option,
1126                      * then the number of VALUEs received should always
1127                      * be less than or equal to the number of VARs and
1128                      * USERVARs received.
1129                      *
1130                      * If we got exactly as many VALUEs as VARs and
1131                      * USERVARs, the client has the same definitions.
1132                      *
1133                      * If we got exactly as many VARs as VALUEs and
1134                      * USERVARS, the client has reversed definitions.
1135                      */
1136                     if (got_uservar + got_var == got_value) {
1137                     env_ovar_ok:
1138                         env_ovar = OLD_ENV_VAR;
1139                         env_ovalue = OLD_ENV_VALUE;
1140                     } else if (got_uservar + got_value == got_var) {
1141                     env_ovar_wrong:
1142                         env_ovar = OLD_ENV_VALUE;
1143                         env_ovalue = OLD_ENV_VAR;
1144                         DIAG(TD_OPTIONS, {
1145                             output_data("ENVIRON VALUE and VAR are reversed!\r\n");
1146                         });
1147
1148                     }
1149                 }
1150                 SB_RESTORE();
1151 #endif
1152
1153                 while (!SB_EOF()) {
1154                     c = SB_GET();
1155                     if ((c == env_ovar) || (c == ENV_USERVAR))
1156                         break;
1157                 }
1158             }
1159
1160         if (SB_EOF())
1161             return;
1162
1163         cp = varp = (char *)subpointer;
1164         valp = 0;
1165
1166         while (!SB_EOF()) {
1167             c = SB_GET();
1168             if (subchar == TELOPT_OLD_ENVIRON) {
1169                 if (c == env_ovar)
1170                     c = NEW_ENV_VAR;
1171                 else if (c == env_ovalue)
1172                     c = NEW_ENV_VALUE;
1173             }
1174             switch (c) {
1175
1176             case NEW_ENV_VALUE:
1177                 *cp = '\0';
1178                 cp = valp = (char *)subpointer;
1179                 break;
1180
1181             case NEW_ENV_VAR:
1182             case ENV_USERVAR:
1183                 *cp = '\0';
1184                 if (valp)
1185                     esetenv(varp, valp, 1);
1186                 else
1187                     unsetenv(varp);
1188                 cp = varp = (char *)subpointer;
1189                 valp = 0;
1190                 break;
1191
1192             case ENV_ESC:
1193                 if (SB_EOF())
1194                     break;
1195                 c = SB_GET();
1196                 /* FALL THROUGH */
1197             default:
1198                 *cp++ = c;
1199                 break;
1200             }
1201         }
1202         *cp = '\0';
1203         if (valp)
1204             esetenv(varp, valp, 1);
1205         else
1206             unsetenv(varp);
1207         break;
1208     }  /* end of case TELOPT_NEW_ENVIRON */
1209 #ifdef AUTHENTICATION
1210     case TELOPT_AUTHENTICATION:
1211         if (SB_EOF())
1212             break;
1213         switch(SB_GET()) {
1214         case TELQUAL_SEND:
1215         case TELQUAL_REPLY:
1216             /*
1217              * These are sent by us and cannot be sent by
1218              * the client.
1219              */
1220             break;
1221         case TELQUAL_IS:
1222             auth_is(subpointer, SB_LEN());
1223             break;
1224         case TELQUAL_NAME:
1225             auth_name(subpointer, SB_LEN());
1226             break;
1227         }
1228         break;
1229 #endif
1230 #ifdef ENCRYPTION
1231     case TELOPT_ENCRYPT:
1232         if (SB_EOF())
1233             break;
1234         switch(SB_GET()) {
1235         case ENCRYPT_SUPPORT:
1236             encrypt_support(subpointer, SB_LEN());
1237             break;
1238         case ENCRYPT_IS:
1239             encrypt_is(subpointer, SB_LEN());
1240             break;
1241         case ENCRYPT_REPLY:
1242             encrypt_reply(subpointer, SB_LEN());
1243             break;
1244         case ENCRYPT_START:
1245             encrypt_start(subpointer, SB_LEN());
1246             break;
1247         case ENCRYPT_END:
1248             if (require_encryption)
1249                 fatal(net, "Output encryption is not possible to turn off");
1250             encrypt_end();
1251             break;
1252         case ENCRYPT_REQSTART:
1253             encrypt_request_start(subpointer, SB_LEN());
1254             break;
1255         case ENCRYPT_REQEND:
1256             /*
1257              * We can always send an REQEND so that we cannot
1258              * get stuck encrypting.  We should only get this
1259              * if we have been able to get in the correct mode
1260              * anyhow.
1261              */
1262             if (require_encryption)
1263                 fatal(net, "Input encryption is not possible to turn off");
1264             encrypt_request_end();
1265             break;
1266         case ENCRYPT_ENC_KEYID:
1267             encrypt_enc_keyid(subpointer, SB_LEN());
1268             break;
1269         case ENCRYPT_DEC_KEYID:
1270             encrypt_dec_keyid(subpointer, SB_LEN());
1271             break;
1272         default:
1273             break;
1274         }
1275         break;
1276 #endif
1277
1278     default:
1279         break;
1280     }  /* end of switch */
1281
1282 }  /* end of suboption */
1283
1284 void
1285 doclientstat(void)
1286 {
1287     clientstat(TELOPT_LINEMODE, WILL, 0);
1288 }
1289
1290 #undef ADD
1291 #define ADD(c)   *ncp++ = c
1292 #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1293
1294 void
1295 send_status(void)
1296 {
1297     unsigned char statusbuf[256];
1298     unsigned char *ncp;
1299     unsigned char i;
1300
1301     ncp = statusbuf;
1302
1303     netflush(); /* get rid of anything waiting to go out */
1304
1305     ADD(IAC);
1306     ADD(SB);
1307     ADD(TELOPT_STATUS);
1308     ADD(TELQUAL_IS);
1309
1310     /*
1311      * We check the want_state rather than the current state,
1312      * because if we received a DO/WILL for an option that we
1313      * don't support, and the other side didn't send a DONT/WONT
1314      * in response to our WONT/DONT, then the "state" will be
1315      * WILL/DO, and the "want_state" will be WONT/DONT.  We
1316      * need to go by the latter.
1317      */
1318     for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1319         if (my_want_state_is_will(i)) {
1320             ADD(WILL);
1321             ADD_DATA(i);
1322         }
1323         if (his_want_state_is_will(i)) {
1324             ADD(DO);
1325             ADD_DATA(i);
1326         }
1327     }
1328
1329     if (his_want_state_is_will(TELOPT_LFLOW)) {
1330         ADD(SB);
1331         ADD(TELOPT_LFLOW);
1332         if (flowmode) {
1333             ADD(LFLOW_ON);
1334         } else {
1335             ADD(LFLOW_OFF);
1336         }
1337         ADD(SE);
1338
1339         if (restartany >= 0) {
1340             ADD(SB);
1341             ADD(TELOPT_LFLOW);
1342             if (restartany) {
1343                 ADD(LFLOW_RESTART_ANY);
1344             } else {
1345                 ADD(LFLOW_RESTART_XON);
1346             }
1347             ADD(SE);
1348         }
1349     }
1350
1351
1352     ADD(IAC);
1353     ADD(SE);
1354
1355     writenet(statusbuf, ncp - statusbuf);
1356     netflush(); /* Send it on its way */
1357
1358     DIAG(TD_OPTIONS,
1359          {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1360 }