crypto/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  * @(#)state.c  8.5 (Berkeley) 5/30/95
  34  * $FreeBSD: src/crypto/telnet/telnetd/state.c,v 1.4.2.3 2002/04/13 10:59:08 markm Exp $
  35  * $DragonFly: src/crypto/telnet/telnetd/state.c,v 1.2 2003/06/17 04:24:37 dillon Exp $
  36  */
  37
  38 #include <stdarg.h>
  39 #include "telnetd.h"
  40 #ifdef  AUTHENTICATION
  41 #include <libtelnet/auth.h>
  42 #endif
  43 #ifdef  ENCRYPTION
  44 #include <libtelnet/encrypt.h>
  45 #endif
  46
  47 unsigned char   doopt[] = { IAC, DO, '%', 'c', 0 };
  48 unsigned char   dont[] = { IAC, DONT, '%', 'c', 0 };
  49 unsigned char   will[] = { IAC, WILL, '%', 'c', 0 };
  50 unsigned char   wont[] = { IAC, WONT, '%', 'c', 0 };
  51 int     not42 = 1;
  52
  53 /*
  54  * Buffer for sub-options, and macros
  55  * for suboptions buffer manipulations
  56  */
  57 unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;
  58
  59 #define SB_CLEAR()      subpointer = subbuffer
  60 #define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
  61 #define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
  62                                 *subpointer++ = (c); \
  63                         }
  64 #define SB_GET()        ((*subpointer++)&0xff)
  65 #define SB_EOF()        (subpointer >= subend)
  66 #define SB_LEN()        (subend - subpointer)
  67
  68 #ifdef  ENV_HACK
  69 unsigned char *subsave;
  70 #define SB_SAVE()       subsave = subpointer;
  71 #define SB_RESTORE()    subpointer = subsave;
  72 #endif
  73
  74
  75 /*
  76  * State for recv fsm
  77  */
  78 #define TS_DATA         0       /* base state */
  79 #define TS_IAC          1       /* look for double IAC's */
  80 #define TS_CR           2       /* CR-LF ->'s CR */
  81 #define TS_SB           3       /* throw away begin's... */
  82 #define TS_SE           4       /* ...end's (suboption negotiation) */
  83 #define TS_WILL         5       /* will option negotiation */
  84 #define TS_WONT         6       /* wont " */
  85 #define TS_DO           7       /* do " */
  86 #define TS_DONT         8       /* dont " */
  87
  88 static void doclientstat(void);
  89
  90 void
  91 telrcv(void)
  92 {
  93         int c;
  94         static int state = TS_DATA;
  95
  96         while (ncc > 0) {
  97                 if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
  98                         break;
  99                 c = *netip++ & 0377, ncc--;
 100 #ifdef  ENCRYPTION
 101                 if (decrypt_input)
 102                         c = (*decrypt_input)(c);
 103 #endif  /* ENCRYPTION */
 104                 switch (state) {
 105
 106                 case TS_CR:
 107                         state = TS_DATA;
 108                         /* Strip off \n or \0 after a \r */
 109                         if ((c == 0) || (c == '\n')) {
 110                                 break;
 111                         }
 112                         /* FALL THROUGH */
 113
 114                 case TS_DATA:
 115                         if (c == IAC) {
 116                                 state = TS_IAC;
 117                                 break;
 118                         }
 119                         /*
 120                          * We now map \r\n ==> \r for pragmatic reasons.
 121                          * Many client implementations send \r\n when
 122                          * the user hits the CarriageReturn key.
 123                          *
 124                          * We USED to map \r\n ==> \n, since \r\n says
 125                          * that we want to be in column 1 of the next
 126                          * printable line, and \n is the standard
 127                          * unix way of saying that (\r is only good
 128                          * if CRMOD is set, which it normally is).
 129                          */
 130                         if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 131                                 int nc = *netip;
 132 #ifdef  ENCRYPTION
 133                                 if (decrypt_input)
 134                                         nc = (*decrypt_input)(nc & 0xff);
 135 #endif  /* ENCRYPTION */
 136 #ifdef  LINEMODE
 137                                 /*
 138                                  * If we are operating in linemode,
 139                                  * convert to local end-of-line.
 140                                  */
 141                                 if (linemode && (ncc > 0) && (('\n' == nc) ||
 142                                          ((0 == nc) && tty_iscrnl())) ) {
 143                                         netip++; ncc--;
 144                                         c = '\n';
 145                                 } else
 146 #endif
 147                                 {
 148 #ifdef  ENCRYPTION
 149                                         if (decrypt_input)
 150                                                 (void)(*decrypt_input)(-1);
 151 #endif  /* ENCRYPTION */
 152                                         state = TS_CR;
 153                                 }
 154                         }
 155                         *pfrontp++ = c;
 156                         break;
 157
 158                 case TS_IAC:
 159 gotiac:                 switch (c) {
 160
 161                         /*
 162                          * Send the process on the pty side an
 163                          * interrupt.  Do this with a NULL or
 164                          * interrupt char; depending on the tty mode.
 165                          */
 166                         case IP:
 167                                 DIAG(TD_OPTIONS,
 168                                         printoption("td: recv IAC", c));
 169                                 interrupt();
 170                                 break;
 171
 172                         case BREAK:
 173                                 DIAG(TD_OPTIONS,
 174                                         printoption("td: recv IAC", c));
 175                                 sendbrk();
 176                                 break;
 177
 178                         /*
 179                          * Are You There?
 180                          */
 181                         case AYT:
 182                                 DIAG(TD_OPTIONS,
 183                                         printoption("td: recv IAC", c));
 184                                 recv_ayt();
 185                                 break;
 186
 187                         /*
 188                          * Abort Output
 189                          */
 190                         case AO:
 191                             {
 192                                 DIAG(TD_OPTIONS,
 193                                         printoption("td: recv IAC", c));
 194                                 ptyflush();     /* half-hearted */
 195                                 init_termbuf();
 196
 197                                 if (slctab[SLC_AO].sptr &&
 198                                     *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
 199                                     *pfrontp++ =
 200                                         (unsigned char)*slctab[SLC_AO].sptr;
 201                                 }
 202
 203                                 netclear();     /* clear buffer back */
 204                                 output_data("%c%c", IAC, DM);
 205                                 neturg = nfrontp-1; /* off by one XXX */
 206                                 DIAG(TD_OPTIONS,
 207                                         printoption("td: send IAC", DM));
 208                                 break;
 209                             }
 210
 211                         /*
 212                          * Erase Character and
 213                          * Erase Line
 214                          */
 215                         case EC:
 216                         case EL:
 217                             {
 218                                 cc_t ch;
 219
 220                                 DIAG(TD_OPTIONS,
 221                                         printoption("td: recv IAC", c));
 222                                 ptyflush();     /* half-hearted */
 223                                 init_termbuf();
 224                                 if (c == EC)
 225                                         ch = *slctab[SLC_EC].sptr;
 226                                 else
 227                                         ch = *slctab[SLC_EL].sptr;
 228                                 if (ch != (cc_t)(_POSIX_VDISABLE))
 229                                         *pfrontp++ = (unsigned char)ch;
 230                                 break;
 231                             }
 232
 233                         /*
 234                          * Check for urgent data...
 235                          */
 236                         case DM:
 237                                 DIAG(TD_OPTIONS,
 238                                         printoption("td: recv IAC", c));
 239                                 SYNCHing = stilloob(net);
 240                                 settimer(gotDM);
 241                                 break;
 242
 243
 244                         /*
 245                          * Begin option subnegotiation...
 246                          */
 247                         case SB:
 248                                 state = TS_SB;
 249                                 SB_CLEAR();
 250                                 continue;
 251
 252                         case WILL:
 253                                 state = TS_WILL;
 254                                 continue;
 255
 256                         case WONT:
 257                                 state = TS_WONT;
 258                                 continue;
 259
 260                         case DO:
 261                                 state = TS_DO;
 262                                 continue;
 263
 264                         case DONT:
 265                                 state = TS_DONT;
 266                                 continue;
 267                         case EOR:
 268                                 if (his_state_is_will(TELOPT_EOR))
 269                                         doeof();
 270                                 break;
 271
 272                         /*
 273                          * Handle RFC 10xx Telnet linemode option additions
 274                          * to command stream (EOF, SUSP, ABORT).
 275                          */
 276                         case xEOF:
 277                                 doeof();
 278                                 break;
 279
 280                         case SUSP:
 281                                 sendsusp();
 282                                 break;
 283
 284                         case ABORT:
 285                                 sendbrk();
 286                                 break;
 287
 288                         case IAC:
 289                                 *pfrontp++ = c;
 290                                 break;
 291                         }
 292                         state = TS_DATA;
 293                         break;
 294
 295                 case TS_SB:
 296                         if (c == IAC) {
 297                                 state = TS_SE;
 298                         } else {
 299                                 SB_ACCUM(c);
 300                         }
 301                         break;
 302
 303                 case TS_SE:
 304                         if (c != SE) {
 305                                 if (c != IAC) {
 306                                         /*
 307                                          * bad form of suboption negotiation.
 308                                          * handle it in such a way as to avoid
 309                                          * damage to local state.  Parse
 310                                          * suboption buffer found so far,
 311                                          * then treat remaining stream as
 312                                          * another command sequence.
 313                                          */
 314
 315                                         /* for DIAGNOSTICS */
 316                                         SB_ACCUM(IAC);
 317                                         SB_ACCUM(c);
 318                                         subpointer -= 2;
 319
 320                                         SB_TERM();
 321                                         suboption();
 322                                         state = TS_IAC;
 323                                         goto gotiac;
 324                                 }
 325                                 SB_ACCUM(c);
 326                                 state = TS_SB;
 327                         } else {
 328                                 /* for DIAGNOSTICS */
 329                                 SB_ACCUM(IAC);
 330                                 SB_ACCUM(SE);
 331                                 subpointer -= 2;
 332
 333                                 SB_TERM();
 334                                 suboption();    /* handle sub-option */
 335                                 state = TS_DATA;
 336                         }
 337                         break;
 338
 339                 case TS_WILL:
 340                         willoption(c);
 341                         state = TS_DATA;
 342                         continue;
 343
 344                 case TS_WONT:
 345                         wontoption(c);
 346                         state = TS_DATA;
 347                         continue;
 348
 349                 case TS_DO:
 350                         dooption(c);
 351                         state = TS_DATA;
 352                         continue;
 353
 354                 case TS_DONT:
 355                         dontoption(c);
 356                         state = TS_DATA;
 357                         continue;
 358
 359                 default:
 360                         syslog(LOG_ERR, "panic state=%d", state);
 361                         printf("telnetd: panic state=%d\n", state);
 362                         exit(1);
 363                 }
 364         }
 365 }  /* end of telrcv */
 366
 367 /*
 368  * The will/wont/do/dont state machines are based on Dave Borman's
 369  * Telnet option processing state machine.
 370  *
 371  * These correspond to the following states:
 372  *      my_state = the last negotiated state
 373  *      want_state = what I want the state to go to
 374  *      want_resp = how many requests I have sent
 375  * All state defaults are negative, and resp defaults to 0.
 376  *
 377  * When initiating a request to change state to new_state:
 378  *
 379  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 380  *      do nothing;
 381  * } else {
 382  *      want_state = new_state;
 383  *      send new_state;
 384  *      want_resp++;
 385  * }
 386  *
 387  * When receiving new_state:
 388  *
 389  * if (want_resp) {
 390  *      want_resp--;
 391  *      if (want_resp && (new_state == my_state))
 392  *              want_resp--;
 393  * }
 394  * if ((want_resp == 0) && (new_state != want_state)) {
 395  *      if (ok_to_switch_to new_state)
 396  *              want_state = new_state;
 397  *      else
 398  *              want_resp++;
 399  *      send want_state;
 400  * }
 401  * my_state = new_state;
 402  *
 403  * Note that new_state is implied in these functions by the function itself.
 404  * will and do imply positive new_state, wont and dont imply negative.
 405  *
 406  * Finally, there is one catch.  If we send a negative response to a
 407  * positive request, my_state will be the positive while want_state will
 408  * remain negative.  my_state will revert to negative when the negative
 409  * acknowlegment arrives from the peer.  Thus, my_state generally tells
 410  * us not only the last negotiated state, but also tells us what the peer
 411  * wants to be doing as well.  It is important to understand this difference
 412  * as we may wish to be processing data streams based on our desired state
 413  * (want_state) or based on what the peer thinks the state is (my_state).
 414  *
 415  * This all works fine because if the peer sends a positive request, the data
 416  * that we receive prior to negative acknowlegment will probably be affected
 417  * by the positive state, and we can process it as such (if we can; if we
 418  * can't then it really doesn't matter).  If it is that important, then the
 419  * peer probably should be buffering until this option state negotiation
 420  * is complete.
 421  *
 422  */
 423 void
 424 send_do(int option, int init)
 425 {
 426         if (init) {
 427                 if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
 428                     his_want_state_is_will(option))
 429                         return;
 430                 /*
 431                  * Special case for TELOPT_TM:  We send a DO, but pretend
 432                  * that we sent a DONT, so that we can send more DOs if
 433                  * we want to.
 434                  */
 435                 if (option == TELOPT_TM)
 436                         set_his_want_state_wont(option);
 437                 else
 438                         set_his_want_state_will(option);
 439                 do_dont_resp[option]++;
 440         }
 441         output_data((const char *)doopt, option);
 442
 443         DIAG(TD_OPTIONS, printoption("td: send do", option));
 444 }
 445
 446 void
 447 willoption(int option)
 448 {
 449         int changeok = 0;
 450         void (*func)(void) = 0;
 451
 452         /*
 453          * process input from peer.
 454          */
 455
 456         DIAG(TD_OPTIONS, printoption("td: recv will", option));
 457
 458         if (do_dont_resp[option]) {
 459                 do_dont_resp[option]--;
 460                 if (do_dont_resp[option] && his_state_is_will(option))
 461                         do_dont_resp[option]--;
 462         }
 463         if (do_dont_resp[option] == 0) {
 464             if (his_want_state_is_wont(option)) {
 465                 switch (option) {
 466
 467                 case TELOPT_BINARY:
 468                         init_termbuf();
 469                         tty_binaryin(1);
 470                         set_termbuf();
 471                         changeok++;
 472                         break;
 473
 474                 case TELOPT_ECHO:
 475                         /*
 476                          * See comments below for more info.
 477                          */
 478                         not42 = 0;      /* looks like a 4.2 system */
 479                         break;
 480
 481                 case TELOPT_TM:
 482 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 483                         /*
 484                          * This telnetd implementation does not really
 485                          * support timing marks, it just uses them to
 486                          * support the kludge linemode stuff.  If we
 487                          * receive a will or wont TM in response to our
 488                          * do TM request that may have been sent to
 489                          * determine kludge linemode support, process
 490                          * it, otherwise TM should get a negative
 491                          * response back.
 492                          */
 493                         /*
 494                          * Handle the linemode kludge stuff.
 495                          * If we are not currently supporting any
 496                          * linemode at all, then we assume that this
 497                          * is the client telling us to use kludge
 498                          * linemode in response to our query.  Set the
 499                          * linemode type that is to be supported, note
 500                          * that the client wishes to use linemode, and
 501                          * eat the will TM as though it never arrived.
 502                          */
 503                         if (lmodetype < KLUDGE_LINEMODE) {
 504                                 lmodetype = KLUDGE_LINEMODE;
 505                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 506                                 send_wont(TELOPT_SGA, 1);
 507                         } else if (lmodetype == NO_AUTOKLUDGE) {
 508                                 lmodetype = KLUDGE_OK;
 509                         }
 510 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 511                         /*
 512                          * We never respond to a WILL TM, and
 513                          * we leave the state WONT.
 514                          */
 515                         return;
 516
 517                 case TELOPT_LFLOW:
 518                         /*
 519                          * If we are going to support flow control
 520                          * option, then don't worry peer that we can't
 521                          * change the flow control characters.
 522                          */
 523                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 524                         slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 525                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 526                         slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 527                 case TELOPT_TTYPE:
 528                 case TELOPT_SGA:
 529                 case TELOPT_NAWS:
 530                 case TELOPT_TSPEED:
 531                 case TELOPT_XDISPLOC:
 532                 case TELOPT_NEW_ENVIRON:
 533                 case TELOPT_OLD_ENVIRON:
 534                         changeok++;
 535                         break;
 536
 537 #ifdef  LINEMODE
 538                 case TELOPT_LINEMODE:
 539 # ifdef KLUDGELINEMODE
 540                         /*
 541                          * Note client's desire to use linemode.
 542                          */
 543                         lmodetype = REAL_LINEMODE;
 544 # endif /* KLUDGELINEMODE */
 545                         func = doclientstat;
 546                         changeok++;
 547                         break;
 548 #endif  /* LINEMODE */
 549
 550 #ifdef  AUTHENTICATION
 551                 case TELOPT_AUTHENTICATION:
 552                         func = auth_request;
 553                         changeok++;
 554                         break;
 555 #endif
 556
 557 #ifdef  ENCRYPTION
 558                 case TELOPT_ENCRYPT:
 559                         func = encrypt_send_support;
 560                         changeok++;
 561                         break;
 562 #endif  /* ENCRYPTION */
 563
 564                 default:
 565                         break;
 566                 }
 567                 if (changeok) {
 568                         set_his_want_state_will(option);
 569                         send_do(option, 0);
 570                 } else {
 571                         do_dont_resp[option]++;
 572                         send_dont(option, 0);
 573                 }
 574             } else {
 575                 /*
 576                  * Option processing that should happen when
 577                  * we receive conformation of a change in
 578                  * state that we had requested.
 579                  */
 580                 switch (option) {
 581                 case TELOPT_ECHO:
 582                         not42 = 0;      /* looks like a 4.2 system */
 583                         /*
 584                          * Egads, he responded "WILL ECHO".  Turn
 585                          * it off right now!
 586                          */
 587                         send_dont(option, 1);
 588                         /*
 589                          * "WILL ECHO".  Kludge upon kludge!
 590                          * A 4.2 client is now echoing user input at
 591                          * the tty.  This is probably undesireable and
 592                          * it should be stopped.  The client will
 593                          * respond WONT TM to the DO TM that we send to
 594                          * check for kludge linemode.  When the WONT TM
 595                          * arrives, linemode will be turned off and a
 596                          * change propogated to the pty.  This change
 597                          * will cause us to process the new pty state
 598                          * in localstat(), which will notice that
 599                          * linemode is off and send a WILL ECHO
 600                          * so that we are properly in character mode and
 601                          * all is well.
 602                          */
 603                         break;
 604 #ifdef  LINEMODE
 605                 case TELOPT_LINEMODE:
 606 # ifdef KLUDGELINEMODE
 607                         /*
 608                          * Note client's desire to use linemode.
 609                          */
 610                         lmodetype = REAL_LINEMODE;
 611 # endif /* KLUDGELINEMODE */
 612                         func = doclientstat;
 613                         break;
 614 #endif  /* LINEMODE */
 615
 616 #ifdef  AUTHENTICATION
 617                 case TELOPT_AUTHENTICATION:
 618                         func = auth_request;
 619                         break;
 620 #endif
 621
 622 #ifdef  ENCRYPTION
 623                 case TELOPT_ENCRYPT:
 624                         func = encrypt_send_support;
 625                         break;
 626 #endif  /* ENCRYPTION */
 627                 case TELOPT_LFLOW:
 628                         func = flowstat;
 629                         break;
 630                 }
 631             }
 632         }
 633         set_his_state_will(option);
 634         if (func)
 635                 (*func)();
 636 }  /* end of willoption */
 637
 638 void
 639 send_dont(int option, int init)
 640 {
 641         if (init) {
 642                 if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 643                     his_want_state_is_wont(option))
 644                         return;
 645                 set_his_want_state_wont(option);
 646                 do_dont_resp[option]++;
 647         }
 648         output_data((const char *)dont, option);
 649
 650         DIAG(TD_OPTIONS, printoption("td: send dont", option));
 651 }
 652
 653 void
 654 wontoption(int option)
 655 {
 656         /*
 657          * Process client input.
 658          */
 659
 660         DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 661
 662         if (do_dont_resp[option]) {
 663                 do_dont_resp[option]--;
 664                 if (do_dont_resp[option] && his_state_is_wont(option))
 665                         do_dont_resp[option]--;
 666         }
 667         if (do_dont_resp[option] == 0) {
 668             if (his_want_state_is_will(option)) {
 669                 /* it is always ok to change to negative state */
 670                 switch (option) {
 671                 case TELOPT_ECHO:
 672                         not42 = 1; /* doesn't seem to be a 4.2 system */
 673                         break;
 674
 675                 case TELOPT_BINARY:
 676                         init_termbuf();
 677                         tty_binaryin(0);
 678                         set_termbuf();
 679                         break;
 680
 681 #ifdef  LINEMODE
 682                 case TELOPT_LINEMODE:
 683 # ifdef KLUDGELINEMODE
 684                         /*
 685                          * If real linemode is supported, then client is
 686                          * asking to turn linemode off.
 687                          */
 688                         if (lmodetype != REAL_LINEMODE)
 689                                 break;
 690                         lmodetype = KLUDGE_LINEMODE;
 691 # endif /* KLUDGELINEMODE */
 692                         clientstat(TELOPT_LINEMODE, WONT, 0);
 693                         break;
 694 #endif  /* LINEMODE */
 695
 696                 case TELOPT_TM:
 697                         /*
 698                          * If we get a WONT TM, and had sent a DO TM,
 699                          * don't respond with a DONT TM, just leave it
 700                          * as is.  Short circut the state machine to
 701                          * achive this.
 702                          */
 703                         set_his_want_state_wont(TELOPT_TM);
 704                         return;
 705
 706                 case TELOPT_LFLOW:
 707                         /*
 708                          * If we are not going to support flow control
 709                          * option, then let peer know that we can't
 710                          * change the flow control characters.
 711                          */
 712                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 713                         slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 714                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 715                         slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 716                         break;
 717
 718 #ifdef  AUTHENTICATION
 719                 case TELOPT_AUTHENTICATION:
 720                         auth_finished(0, AUTH_REJECT);
 721                         break;
 722 #endif
 723
 724                 /*
 725                  * For options that we might spin waiting for
 726                  * sub-negotiation, if the client turns off the
 727                  * option rather than responding to the request,
 728                  * we have to treat it here as if we got a response
 729                  * to the sub-negotiation, (by updating the timers)
 730                  * so that we'll break out of the loop.
 731                  */
 732                 case TELOPT_TTYPE:
 733                         settimer(ttypesubopt);
 734                         break;
 735
 736                 case TELOPT_TSPEED:
 737                         settimer(tspeedsubopt);
 738                         break;
 739
 740                 case TELOPT_XDISPLOC:
 741                         settimer(xdisplocsubopt);
 742                         break;
 743
 744                 case TELOPT_OLD_ENVIRON:
 745                         settimer(oenvironsubopt);
 746                         break;
 747
 748                 case TELOPT_NEW_ENVIRON:
 749                         settimer(environsubopt);
 750                         break;
 751
 752                 default:
 753                         break;
 754                 }
 755                 set_his_want_state_wont(option);
 756                 if (his_state_is_will(option))
 757                         send_dont(option, 0);
 758             } else {
 759                 switch (option) {
 760                 case TELOPT_TM:
 761 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 762                         if (lmodetype < NO_AUTOKLUDGE) {
 763                                 lmodetype = NO_LINEMODE;
 764                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 765                                 send_will(TELOPT_SGA, 1);
 766                                 send_will(TELOPT_ECHO, 1);
 767                         }
 768 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 769                         break;
 770
 771 #ifdef AUTHENTICATION
 772                 case TELOPT_AUTHENTICATION:
 773                         auth_finished(0, AUTH_REJECT);
 774                         break;
 775 #endif
 776                 default:
 777                         break;
 778                 }
 779             }
 780         }
 781         set_his_state_wont(option);
 782
 783 }  /* end of wontoption */
 784
 785 void
 786 send_will(int option, int init)
 787 {
 788         if (init) {
 789                 if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 790                     my_want_state_is_will(option))
 791                         return;
 792                 set_my_want_state_will(option);
 793                 will_wont_resp[option]++;
 794         }
 795         output_data((const char *)will, option);
 796
 797         DIAG(TD_OPTIONS, printoption("td: send will", option));
 798 }
 799
 800 #if     !defined(LINEMODE) || !defined(KLUDGELINEMODE)
 801 /*
 802  * When we get a DONT SGA, we will try once to turn it
 803  * back on.  If the other side responds DONT SGA, we
 804  * leave it at that.  This is so that when we talk to
 805  * clients that understand KLUDGELINEMODE but not LINEMODE,
 806  * we'll keep them in char-at-a-time mode.
 807  */
 808 int turn_on_sga = 0;
 809 #endif
 810
 811 void
 812 dooption(int option)
 813 {
 814         int changeok = 0;
 815
 816         /*
 817          * Process client input.
 818          */
 819
 820         DIAG(TD_OPTIONS, printoption("td: recv do", option));
 821
 822         if (will_wont_resp[option]) {
 823                 will_wont_resp[option]--;
 824                 if (will_wont_resp[option] && my_state_is_will(option))
 825                         will_wont_resp[option]--;
 826         }
 827         if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 828                 switch (option) {
 829                 case TELOPT_ECHO:
 830 #ifdef  LINEMODE
 831 # ifdef KLUDGELINEMODE
 832                         if (lmodetype == NO_LINEMODE)
 833 # else
 834                         if (his_state_is_wont(TELOPT_LINEMODE))
 835 # endif
 836 #endif
 837                         {
 838                                 init_termbuf();
 839                                 tty_setecho(1);
 840                                 set_termbuf();
 841                         }
 842                         changeok++;
 843                         break;
 844
 845                 case TELOPT_BINARY:
 846                         init_termbuf();
 847                         tty_binaryout(1);
 848                         set_termbuf();
 849                         changeok++;
 850                         break;
 851
 852                 case TELOPT_SGA:
 853 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 854                         /*
 855                          * If kludge linemode is in use, then we must
 856                          * process an incoming do SGA for linemode
 857                          * purposes.
 858                          */
 859                         if (lmodetype == KLUDGE_LINEMODE) {
 860                                 /*
 861                                  * Receipt of "do SGA" in kludge
 862                                  * linemode is the peer asking us to
 863                                  * turn off linemode.  Make note of
 864                                  * the request.
 865                                  */
 866                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 867                                 /*
 868                                  * If linemode did not get turned off
 869                                  * then don't tell peer that we did.
 870                                  * Breaking here forces a wont SGA to
 871                                  * be returned.
 872                                  */
 873                                 if (linemode)
 874                                         break;
 875                         }
 876 #else
 877                         turn_on_sga = 0;
 878 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 879                         changeok++;
 880                         break;
 881
 882                 case TELOPT_STATUS:
 883                         changeok++;
 884                         break;
 885
 886                 case TELOPT_TM:
 887                         /*
 888                          * Special case for TM.  We send a WILL, but
 889                          * pretend we sent a WONT.
 890                          */
 891                         send_will(option, 0);
 892                         set_my_want_state_wont(option);
 893                         set_my_state_wont(option);
 894                         return;
 895
 896                 case TELOPT_LOGOUT:
 897                         /*
 898                          * When we get a LOGOUT option, respond
 899                          * with a WILL LOGOUT, make sure that
 900                          * it gets written out to the network,
 901                          * and then just go away...
 902                          */
 903                         set_my_want_state_will(TELOPT_LOGOUT);
 904                         send_will(TELOPT_LOGOUT, 0);
 905                         set_my_state_will(TELOPT_LOGOUT);
 906                         (void)netflush();
 907                         cleanup(0);
 908                         /* NOT REACHED */
 909                         break;
 910
 911 #ifdef  ENCRYPTION
 912                 case TELOPT_ENCRYPT:
 913                         changeok++;
 914                         break;
 915 #endif  /* ENCRYPTION */
 916                 case TELOPT_LINEMODE:
 917                 case TELOPT_TTYPE:
 918                 case TELOPT_NAWS:
 919                 case TELOPT_TSPEED:
 920                 case TELOPT_LFLOW:
 921                 case TELOPT_XDISPLOC:
 922 #ifdef  TELOPT_ENVIRON
 923                 case TELOPT_NEW_ENVIRON:
 924 #endif
 925                 case TELOPT_OLD_ENVIRON:
 926                 default:
 927                         break;
 928                 }
 929                 if (changeok) {
 930                         set_my_want_state_will(option);
 931                         send_will(option, 0);
 932                 } else {
 933                         will_wont_resp[option]++;
 934                         send_wont(option, 0);
 935                 }
 936         }
 937         set_my_state_will(option);
 938
 939 }  /* end of dooption */
 940
 941 void
 942 send_wont(int option, int init)
 943 {
 944         if (init) {
 945                 if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 946                     my_want_state_is_wont(option))
 947                         return;
 948                 set_my_want_state_wont(option);
 949                 will_wont_resp[option]++;
 950         }
 951         output_data((const char *)wont, option);
 952
 953         DIAG(TD_OPTIONS, printoption("td: send wont", option));
 954 }
 955
 956 void
 957 dontoption(int option)
 958 {
 959         /*
 960          * Process client input.
 961          */
 962
 963
 964         DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 965
 966         if (will_wont_resp[option]) {
 967                 will_wont_resp[option]--;
 968                 if (will_wont_resp[option] && my_state_is_wont(option))
 969                         will_wont_resp[option]--;
 970         }
 971         if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 972                 switch (option) {
 973                 case TELOPT_BINARY:
 974                         init_termbuf();
 975                         tty_binaryout(0);
 976                         set_termbuf();
 977                         break;
 978
 979                 case TELOPT_ECHO:       /* we should stop echoing */
 980 #ifdef  LINEMODE
 981 # ifdef KLUDGELINEMODE
 982                         if ((lmodetype != REAL_LINEMODE) &&
 983                             (lmodetype != KLUDGE_LINEMODE))
 984 # else
 985                         if (his_state_is_wont(TELOPT_LINEMODE))
 986 # endif
 987 #endif
 988                         {
 989                                 init_termbuf();
 990                                 tty_setecho(0);
 991                                 set_termbuf();
 992                         }
 993                         break;
 994
 995                 case TELOPT_SGA:
 996 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 997                         /*
 998                          * If kludge linemode is in use, then we
 999                          * must process an incoming do SGA for
1000                          * linemode purposes.
1001                          */
1002                         if ((lmodetype == KLUDGE_LINEMODE) ||
1003                             (lmodetype == KLUDGE_OK)) {
1004                                 /*
1005                                  * The client is asking us to turn
1006                                  * linemode on.
1007                                  */
1008                                 lmodetype = KLUDGE_LINEMODE;
1009                                 clientstat(TELOPT_LINEMODE, WILL, 0);
1010                                 /*
1011                                  * If we did not turn line mode on,
1012                                  * then what do we say?  Will SGA?
1013                                  * This violates design of telnet.
1014                                  * Gross.  Very Gross.
1015                                  */
1016                         }
1017                         break;
1018 #else
1019                         set_my_want_state_wont(option);
1020                         if (my_state_is_will(option))
1021                                 send_wont(option, 0);
1022                         set_my_state_wont(option);
1023                         if (turn_on_sga ^= 1)
1024                                 send_will(option, 1);
1025                         return;
1026 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
1027
1028                 default:
1029                         break;
1030                 }
1031
1032                 set_my_want_state_wont(option);
1033                 if (my_state_is_will(option))
1034                         send_wont(option, 0);
1035         }
1036         set_my_state_wont(option);
1037
1038 }  /* end of dontoption */
1039
1040 #ifdef  ENV_HACK
1041 int env_ovar = -1;
1042 int env_ovalue = -1;
1043 #else   /* ENV_HACK */
1044 # define env_ovar OLD_ENV_VAR
1045 # define env_ovalue OLD_ENV_VALUE
1046 #endif  /* ENV_HACK */
1047
1048 /*
1049  * suboption()
1050  *
1051  *      Look at the sub-option buffer, and try to be helpful to the other
1052  * side.
1053  *
1054  *      Currently we recognize:
1055  *
1056  *      Terminal type is
1057  *      Linemode
1058  *      Window size
1059  *      Terminal speed
1060  */
1061 void
1062 suboption(void)
1063 {
1064     int subchar;
1065
1066     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1067
1068     subchar = SB_GET();
1069     switch (subchar) {
1070     case TELOPT_TSPEED: {
1071         int xspeed, rspeed;
1072
1073         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
1074                 break;
1075
1076         settimer(tspeedsubopt);
1077
1078         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1079                 return;
1080
1081         xspeed = atoi((char *)subpointer);
1082
1083         while (SB_GET() != ',' && !SB_EOF());
1084         if (SB_EOF())
1085                 return;
1086
1087         rspeed = atoi((char *)subpointer);
1088         clientstat(TELOPT_TSPEED, xspeed, rspeed);
1089
1090         break;
1091
1092     }  /* end of case TELOPT_TSPEED */
1093
1094     case TELOPT_TTYPE: {                /* Yaaaay! */
1095         static char terminalname[41];
1096
1097         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
1098                 break;
1099         settimer(ttypesubopt);
1100
1101         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1102             return;             /* ??? XXX but, this is the most robust */
1103         }
1104
1105         terminaltype = terminalname;
1106
1107         while ((terminaltype < (terminalname + sizeof terminalname-1)) &&
1108                                                                     !SB_EOF()) {
1109             int c;
1110
1111             c = SB_GET();
1112             if (isupper(c)) {
1113                 c = tolower(c);
1114             }
1115             *terminaltype++ = c;    /* accumulate name */
1116         }
1117         *terminaltype = 0;
1118         terminaltype = terminalname;
1119         break;
1120     }  /* end of case TELOPT_TTYPE */
1121
1122     case TELOPT_NAWS: {
1123         int xwinsize, ywinsize;
1124
1125         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
1126                 break;
1127
1128         if (SB_EOF())
1129                 return;
1130         xwinsize = SB_GET() << 8;
1131         if (SB_EOF())
1132                 return;
1133         xwinsize |= SB_GET();
1134         if (SB_EOF())
1135                 return;
1136         ywinsize = SB_GET() << 8;
1137         if (SB_EOF())
1138                 return;
1139         ywinsize |= SB_GET();
1140         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1141
1142         break;
1143
1144     }  /* end of case TELOPT_NAWS */
1145
1146 #ifdef  LINEMODE
1147     case TELOPT_LINEMODE: {
1148         int request;
1149
1150         if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
1151                 break;
1152         /*
1153          * Process linemode suboptions.
1154          */
1155         if (SB_EOF())
1156             break;              /* garbage was sent */
1157         request = SB_GET();     /* get will/wont */
1158
1159         if (SB_EOF())
1160             break;              /* another garbage check */
1161
1162         if (request == LM_SLC) {  /* SLC is not preceeded by WILL or WONT */
1163                 /*
1164                  * Process suboption buffer of slc's
1165                  */
1166                 start_slc(1);
1167                 do_opt_slc(subpointer, subend - subpointer);
1168                 (void) end_slc(0);
1169                 break;
1170         } else if (request == LM_MODE) {
1171                 if (SB_EOF())
1172                     return;
1173                 useeditmode = SB_GET();  /* get mode flag */
1174                 clientstat(LM_MODE, 0, 0);
1175                 break;
1176         }
1177
1178         if (SB_EOF())
1179             break;
1180         switch (SB_GET()) {  /* what suboption? */
1181         case LM_FORWARDMASK:
1182                 /*
1183                  * According to spec, only server can send request for
1184                  * forwardmask, and client can only return a positive response.
1185                  * So don't worry about it.
1186                  */
1187
1188         default:
1189                 break;
1190         }
1191         break;
1192     }  /* end of case TELOPT_LINEMODE */
1193 #endif
1194     case TELOPT_STATUS: {
1195         int mode;
1196
1197         if (SB_EOF())
1198             break;
1199         mode = SB_GET();
1200         switch (mode) {
1201         case TELQUAL_SEND:
1202             if (my_state_is_will(TELOPT_STATUS))
1203                 send_status();
1204             break;
1205
1206         case TELQUAL_IS:
1207             break;
1208
1209         default:
1210             break;
1211         }
1212         break;
1213     }  /* end of case TELOPT_STATUS */
1214
1215     case TELOPT_XDISPLOC: {
1216         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1217                 return;
1218         settimer(xdisplocsubopt);
1219         subpointer[SB_LEN()] = '\0';
1220         (void)setenv("DISPLAY", (char *)subpointer, 1);
1221         break;
1222     }  /* end of case TELOPT_XDISPLOC */
1223
1224 #ifdef  TELOPT_NEW_ENVIRON
1225     case TELOPT_NEW_ENVIRON:
1226 #endif
1227     case TELOPT_OLD_ENVIRON: {
1228         int c;
1229         char *cp, *varp, *valp;
1230
1231         if (SB_EOF())
1232                 return;
1233         c = SB_GET();
1234         if (c == TELQUAL_IS) {
1235                 if (subchar == TELOPT_OLD_ENVIRON)
1236                         settimer(oenvironsubopt);
1237                 else
1238                         settimer(environsubopt);
1239         } else if (c != TELQUAL_INFO) {
1240                 return;
1241         }
1242
1243 #ifdef  TELOPT_NEW_ENVIRON
1244         if (subchar == TELOPT_NEW_ENVIRON) {
1245             while (!SB_EOF()) {
1246                 c = SB_GET();
1247                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1248                         break;
1249             }
1250         } else
1251 #endif
1252         {
1253 #ifdef  ENV_HACK
1254             /*
1255              * We only want to do this if we haven't already decided
1256              * whether or not the other side has its VALUE and VAR
1257              * reversed.
1258              */
1259             if (env_ovar < 0) {
1260                 int last = -1;          /* invalid value */
1261                 int empty = 0;
1262                 int got_var = 0, got_value = 0, got_uservar = 0;
1263
1264                 /*
1265                  * The other side might have its VALUE and VAR values
1266                  * reversed.  To be interoperable, we need to determine
1267                  * which way it is.  If the first recognized character
1268                  * is a VAR or VALUE, then that will tell us what
1269                  * type of client it is.  If the fist recognized
1270                  * character is a USERVAR, then we continue scanning
1271                  * the suboption looking for two consecutive
1272                  * VAR or VALUE fields.  We should not get two
1273                  * consecutive VALUE fields, so finding two
1274                  * consecutive VALUE or VAR fields will tell us
1275                  * what the client is.
1276                  */
1277                 SB_SAVE();
1278                 while (!SB_EOF()) {
1279                         c = SB_GET();
1280                         switch(c) {
1281                         case OLD_ENV_VAR:
1282                                 if (last < 0 || last == OLD_ENV_VAR
1283                                     || (empty && (last == OLD_ENV_VALUE)))
1284                                         goto env_ovar_ok;
1285                                 got_var++;
1286                                 last = OLD_ENV_VAR;
1287                                 break;
1288                         case OLD_ENV_VALUE:
1289                                 if (last < 0 || last == OLD_ENV_VALUE
1290                                     || (empty && (last == OLD_ENV_VAR)))
1291                                         goto env_ovar_wrong;
1292                                 got_value++;
1293                                 last = OLD_ENV_VALUE;
1294                                 break;
1295                         case ENV_USERVAR:
1296                                 /* count strings of USERVAR as one */
1297                                 if (last != ENV_USERVAR)
1298                                         got_uservar++;
1299                                 if (empty) {
1300                                         if (last == OLD_ENV_VALUE)
1301                                                 goto env_ovar_ok;
1302                                         if (last == OLD_ENV_VAR)
1303                                                 goto env_ovar_wrong;
1304                                 }
1305                                 last = ENV_USERVAR;
1306                                 break;
1307                         case ENV_ESC:
1308                                 if (!SB_EOF())
1309                                         c = SB_GET();
1310                                 /* FALL THROUGH */
1311                         default:
1312                                 empty = 0;
1313                                 continue;
1314                         }
1315                         empty = 1;
1316                 }
1317                 if (empty) {
1318                         if (last == OLD_ENV_VALUE)
1319                                 goto env_ovar_ok;
1320                         if (last == OLD_ENV_VAR)
1321                                 goto env_ovar_wrong;
1322                 }
1323                 /*
1324                  * Ok, the first thing was a USERVAR, and there
1325                  * are not two consecutive VAR or VALUE commands,
1326                  * and none of the VAR or VALUE commands are empty.
1327                  * If the client has sent us a well-formed option,
1328                  * then the number of VALUEs received should always
1329                  * be less than or equal to the number of VARs and
1330                  * USERVARs received.
1331                  *
1332                  * If we got exactly as many VALUEs as VARs and
1333                  * USERVARs, the client has the same definitions.
1334                  *
1335                  * If we got exactly as many VARs as VALUEs and
1336                  * USERVARS, the client has reversed definitions.
1337                  */
1338                 if (got_uservar + got_var == got_value) {
1339             env_ovar_ok:
1340                         env_ovar = OLD_ENV_VAR;
1341                         env_ovalue = OLD_ENV_VALUE;
1342                 } else if (got_uservar + got_value == got_var) {
1343             env_ovar_wrong:
1344                         env_ovar = OLD_ENV_VALUE;
1345                         env_ovalue = OLD_ENV_VAR;
1346                         DIAG(TD_OPTIONS,
1347                             output_data("ENVIRON VALUE and VAR are reversed!\r\n"));
1348
1349                 }
1350             }
1351             SB_RESTORE();
1352 #endif
1353
1354             while (!SB_EOF()) {
1355                 c = SB_GET();
1356                 if ((c == env_ovar) || (c == ENV_USERVAR))
1357                         break;
1358             }
1359         }
1360
1361         if (SB_EOF())
1362                 return;
1363
1364         cp = varp = (char *)subpointer;
1365         valp = 0;
1366
1367         while (!SB_EOF()) {
1368                 c = SB_GET();
1369                 if (subchar == TELOPT_OLD_ENVIRON) {
1370                         if (c == env_ovar)
1371                                 c = NEW_ENV_VAR;
1372                         else if (c == env_ovalue)
1373                                 c = NEW_ENV_VALUE;
1374                 }
1375                 switch (c) {
1376
1377                 case NEW_ENV_VALUE:
1378                         *cp = '\0';
1379                         cp = valp = (char *)subpointer;
1380                         break;
1381
1382                 case NEW_ENV_VAR:
1383                 case ENV_USERVAR:
1384                         *cp = '\0';
1385                         if (valp)
1386                                 (void)setenv(varp, valp, 1);
1387                         else
1388                                 unsetenv(varp);
1389                         cp = varp = (char *)subpointer;
1390                         valp = 0;
1391                         break;
1392
1393                 case ENV_ESC:
1394                         if (SB_EOF())
1395                                 break;
1396                         c = SB_GET();
1397                         /* FALL THROUGH */
1398                 default:
1399                         *cp++ = c;
1400                         break;
1401                 }
1402         }
1403         *cp = '\0';
1404         if (valp)
1405                 (void)setenv(varp, valp, 1);
1406         else
1407                 unsetenv(varp);
1408         break;
1409     }  /* end of case TELOPT_NEW_ENVIRON */
1410 #ifdef  AUTHENTICATION
1411     case TELOPT_AUTHENTICATION:
1412         if (SB_EOF())
1413                 break;
1414         switch(SB_GET()) {
1415         case TELQUAL_SEND:
1416         case TELQUAL_REPLY:
1417                 /*
1418                  * These are sent by us and cannot be sent by
1419                  * the client.
1420                  */
1421                 break;
1422         case TELQUAL_IS:
1423                 auth_is(subpointer, SB_LEN());
1424                 break;
1425         case TELQUAL_NAME:
1426                 auth_name(subpointer, SB_LEN());
1427                 break;
1428         }
1429         break;
1430 #endif
1431 #ifdef  ENCRYPTION
1432     case TELOPT_ENCRYPT:
1433         if (SB_EOF())
1434                 break;
1435         switch(SB_GET()) {
1436         case ENCRYPT_SUPPORT:
1437                 encrypt_support(subpointer, SB_LEN());
1438                 break;
1439         case ENCRYPT_IS:
1440                 encrypt_is(subpointer, SB_LEN());
1441                 break;
1442         case ENCRYPT_REPLY:
1443                 encrypt_reply(subpointer, SB_LEN());
1444                 break;
1445         case ENCRYPT_START:
1446                 encrypt_start(subpointer, SB_LEN());
1447                 break;
1448         case ENCRYPT_END:
1449                 encrypt_end();
1450                 break;
1451         case ENCRYPT_REQSTART:
1452                 encrypt_request_start(subpointer, SB_LEN());
1453                 break;
1454         case ENCRYPT_REQEND:
1455                 /*
1456                  * We can always send an REQEND so that we cannot
1457                  * get stuck encrypting.  We should only get this
1458                  * if we have been able to get in the correct mode
1459                  * anyhow.
1460                  */
1461                 encrypt_request_end();
1462                 break;
1463         case ENCRYPT_ENC_KEYID:
1464                 encrypt_enc_keyid(subpointer, SB_LEN());
1465                 break;
1466         case ENCRYPT_DEC_KEYID:
1467                 encrypt_dec_keyid(subpointer, SB_LEN());
1468                 break;
1469         default:
1470                 break;
1471         }
1472         break;
1473 #endif  /* ENCRYPTION */
1474
1475     default:
1476         break;
1477     }  /* end of switch */
1478
1479 }  /* end of suboption */
1480
1481 static void
1482 doclientstat(void)
1483 {
1484         clientstat(TELOPT_LINEMODE, WILL, 0);
1485 }
1486
1487 #define ADD(c)   *ncp++ = c
1488 #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1489 void
1490 send_status(void)
1491 {
1492         unsigned char statusbuf[256];
1493         unsigned char *ncp;
1494         unsigned char i;
1495
1496         ncp = statusbuf;
1497
1498         netflush();     /* get rid of anything waiting to go out */
1499
1500         ADD(IAC);
1501         ADD(SB);
1502         ADD(TELOPT_STATUS);
1503         ADD(TELQUAL_IS);
1504
1505         /*
1506          * We check the want_state rather than the current state,
1507          * because if we received a DO/WILL for an option that we
1508          * don't support, and the other side didn't send a DONT/WONT
1509          * in response to our WONT/DONT, then the "state" will be
1510          * WILL/DO, and the "want_state" will be WONT/DONT.  We
1511          * need to go by the latter.
1512          */
1513         for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1514                 if (my_want_state_is_will(i)) {
1515                         ADD(WILL);
1516                         ADD_DATA(i);
1517                         if (i == IAC)
1518                                 ADD(IAC);
1519                 }
1520                 if (his_want_state_is_will(i)) {
1521                         ADD(DO);
1522                         ADD_DATA(i);
1523                         if (i == IAC)
1524                                 ADD(IAC);
1525                 }
1526         }
1527
1528         if (his_want_state_is_will(TELOPT_LFLOW)) {
1529                 ADD(SB);
1530                 ADD(TELOPT_LFLOW);
1531                 if (flowmode) {
1532                         ADD(LFLOW_ON);
1533                 } else {
1534                         ADD(LFLOW_OFF);
1535                 }
1536                 ADD(SE);
1537
1538                 if (restartany >= 0) {
1539                         ADD(SB);
1540                         ADD(TELOPT_LFLOW);
1541                         if (restartany) {
1542                                 ADD(LFLOW_RESTART_ANY);
1543                         } else {
1544                                 ADD(LFLOW_RESTART_XON);
1545                         }
1546                         ADD(SE);
1547                 }
1548         }
1549
1550 #ifdef  LINEMODE
1551         if (his_want_state_is_will(TELOPT_LINEMODE)) {
1552                 unsigned char *cp, *cpe;
1553                 int len;
1554
1555                 ADD(SB);
1556                 ADD(TELOPT_LINEMODE);
1557                 ADD(LM_MODE);
1558                 ADD_DATA(editmode);
1559                 ADD(SE);
1560
1561                 ADD(SB);
1562                 ADD(TELOPT_LINEMODE);
1563                 ADD(LM_SLC);
1564                 start_slc(0);
1565                 send_slc();
1566                 len = end_slc(&cp);
1567                 for (cpe = cp + len; cp < cpe; cp++)
1568                         ADD_DATA(*cp);
1569                 ADD(SE);
1570         }
1571 #endif  /* LINEMODE */
1572
1573         ADD(IAC);
1574         ADD(SE);
1575
1576         output_datalen(statusbuf, ncp - statusbuf);
1577         netflush();     /* Send it on its way */
1578
1579         DIAG(TD_OPTIONS,
1580                 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1581 }
1582
1583 /*
1584  * This function appends data to nfrontp and advances nfrontp.
1585  * Returns the number of characters written altogether (the
1586  * buffer may have been flushed in the process).
1587  */
1588
1589 int
1590 output_data(const char *format, ...)
1591 {
1592         va_list args;
1593         int len;
1594         char *buf;
1595
1596         va_start(args, format);
1597         if ((len = vasprintf(&buf, format, args)) == -1)
1598                 return -1;
1599         output_datalen(buf, len);
1600         va_end(args);
1601         free(buf);
1602         return (len);
1603 }
1604
1605 void
1606 output_datalen(const char *buf, int len)
1607 {
1608         int remaining, copied;
1609
1610         remaining = BUFSIZ - (nfrontp - netobuf);
1611         while (len > 0) {
1612                 /* Free up enough space if the room is too low*/
1613                 if ((len > BUFSIZ ? BUFSIZ : len) > remaining) {
1614                         netflush();
1615                         remaining = BUFSIZ - (nfrontp - netobuf);
1616                 }
1617
1618                 /* Copy out as much as will fit */
1619                 copied = remaining > len ? len : remaining;
1620                 memmove(nfrontp, buf, copied);
1621                 nfrontp += copied;
1622                 len -= copied;
1623                 remaining -= copied;
1624                 buf += copied;
1625         }
1626         return;
1627 }