libexec/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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)state.c  8.5 (Berkeley) 5/30/95
  30  * $FreeBSD: src/crypto/telnet/telnetd/state.c,v 1.4.2.3 2002/04/13 10:59:08 markm Exp $
  31  */
  32
  33 #include <stdarg.h>
  34 #include "telnetd.h"
  35 #ifdef  AUTHENTICATION
  36 #include <libtelnet/auth.h>
  37 #endif
  38 #ifdef  ENCRYPTION
  39 #include <libtelnet/encrypt.h>
  40 #endif
  41
  42 static int envvarok(char *);
  43
  44 unsigned char   doopt[] = { IAC, DO, '%', 'c', 0 };
  45 unsigned char   dont[] = { IAC, DONT, '%', 'c', 0 };
  46 unsigned char   will[] = { IAC, WILL, '%', 'c', 0 };
  47 unsigned char   wont[] = { IAC, WONT, '%', 'c', 0 };
  48 int     not42 = 1;
  49
  50 /*
  51  * Buffer for sub-options, and macros
  52  * for suboptions buffer manipulations
  53  */
  54 unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;
  55
  56 #define SB_CLEAR()      subpointer = subbuffer
  57 #define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
  58 #define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
  59                                 *subpointer++ = (c); \
  60                         }
  61 #define SB_GET()        ((*subpointer++)&0xff)
  62 #define SB_EOF()        (subpointer >= subend)
  63 #define SB_LEN()        (subend - subpointer)
  64
  65 #ifdef  ENV_HACK
  66 unsigned char *subsave;
  67 #define SB_SAVE()       subsave = subpointer;
  68 #define SB_RESTORE()    subpointer = subsave;
  69 #endif
  70
  71
  72 /*
  73  * State for recv fsm
  74  */
  75 #define TS_DATA         0       /* base state */
  76 #define TS_IAC          1       /* look for double IAC's */
  77 #define TS_CR           2       /* CR-LF ->'s CR */
  78 #define TS_SB           3       /* throw away begin's... */
  79 #define TS_SE           4       /* ...end's (suboption negotiation) */
  80 #define TS_WILL         5       /* will option negotiation */
  81 #define TS_WONT         6       /* wont " */
  82 #define TS_DO           7       /* do " */
  83 #define TS_DONT         8       /* dont " */
  84
  85 static void doclientstat(void);
  86
  87 void
  88 telrcv(void)
  89 {
  90         int c;
  91         static int state = TS_DATA;
  92
  93         while (ncc > 0) {
  94                 if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
  95                         break;
  96                 c = *netip++ & 0377, ncc--;
  97 #ifdef  ENCRYPTION
  98                 if (decrypt_input)
  99                         c = (*decrypt_input)(c);
 100 #endif  /* ENCRYPTION */
 101                 switch (state) {
 102
 103                 case TS_CR:
 104                         state = TS_DATA;
 105                         /* Strip off \n or \0 after a \r */
 106                         if ((c == 0) || (c == '\n')) {
 107                                 break;
 108                         }
 109                         /* FALL THROUGH */
 110
 111                 case TS_DATA:
 112                         if (c == IAC) {
 113                                 state = TS_IAC;
 114                                 break;
 115                         }
 116                         /*
 117                          * We now map \r\n ==> \r for pragmatic reasons.
 118                          * Many client implementations send \r\n when
 119                          * the user hits the CarriageReturn key.
 120                          *
 121                          * We USED to map \r\n ==> \n, since \r\n says
 122                          * that we want to be in column 1 of the next
 123                          * printable line, and \n is the standard
 124                          * unix way of saying that (\r is only good
 125                          * if CRMOD is set, which it normally is).
 126                          */
 127                         if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 128                                 int nc = *netip;
 129 #ifdef  ENCRYPTION
 130                                 if (decrypt_input)
 131                                         nc = (*decrypt_input)(nc & 0xff);
 132 #endif  /* ENCRYPTION */
 133 #ifdef  LINEMODE
 134                                 /*
 135                                  * If we are operating in linemode,
 136                                  * convert to local end-of-line.
 137                                  */
 138                                 if (linemode && (ncc > 0) && (('\n' == nc) ||
 139                                          ((0 == nc) && tty_iscrnl())) ) {
 140                                         netip++; ncc--;
 141                                         c = '\n';
 142                                 } else
 143 #endif
 144                                 {
 145 #ifdef  ENCRYPTION
 146                                         if (decrypt_input)
 147                                                 (void)(*decrypt_input)(-1);
 148 #endif  /* ENCRYPTION */
 149                                         state = TS_CR;
 150                                 }
 151                         }
 152                         *pfrontp++ = c;
 153                         break;
 154
 155                 case TS_IAC:
 156 gotiac:                 switch (c) {
 157
 158                         /*
 159                          * Send the process on the pty side an
 160                          * interrupt.  Do this with a NULL or
 161                          * interrupt char; depending on the tty mode.
 162                          */
 163                         case IP:
 164                                 DIAG(TD_OPTIONS,
 165                                         printoption("td: recv IAC", c));
 166                                 interrupt();
 167                                 break;
 168
 169                         case BREAK:
 170                                 DIAG(TD_OPTIONS,
 171                                         printoption("td: recv IAC", c));
 172                                 sendbrk();
 173                                 break;
 174
 175                         /*
 176                          * Are You There?
 177                          */
 178                         case AYT:
 179                                 DIAG(TD_OPTIONS,
 180                                         printoption("td: recv IAC", c));
 181                                 recv_ayt();
 182                                 break;
 183
 184                         /*
 185                          * Abort Output
 186                          */
 187                         case AO:
 188                             {
 189                                 DIAG(TD_OPTIONS,
 190                                         printoption("td: recv IAC", c));
 191                                 ptyflush();     /* half-hearted */
 192                                 init_termbuf();
 193
 194                                 if (slctab[SLC_AO].sptr &&
 195                                     *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
 196                                     *pfrontp++ =
 197                                         (unsigned char)*slctab[SLC_AO].sptr;
 198                                 }
 199
 200                                 netclear();     /* clear buffer back */
 201                                 output_data("%c%c", IAC, DM);
 202                                 neturg = nfrontp-1; /* off by one XXX */
 203                                 DIAG(TD_OPTIONS,
 204                                         printoption("td: send IAC", DM));
 205                                 break;
 206                             }
 207
 208                         /*
 209                          * Erase Character and
 210                          * Erase Line
 211                          */
 212                         case EC:
 213                         case EL:
 214                             {
 215                                 cc_t ch;
 216
 217                                 DIAG(TD_OPTIONS,
 218                                         printoption("td: recv IAC", c));
 219                                 ptyflush();     /* half-hearted */
 220                                 init_termbuf();
 221                                 if (c == EC)
 222                                         ch = *slctab[SLC_EC].sptr;
 223                                 else
 224                                         ch = *slctab[SLC_EL].sptr;
 225                                 if (ch != (cc_t)(_POSIX_VDISABLE))
 226                                         *pfrontp++ = (unsigned char)ch;
 227                                 break;
 228                             }
 229
 230                         /*
 231                          * Check for urgent data...
 232                          */
 233                         case DM:
 234                                 DIAG(TD_OPTIONS,
 235                                         printoption("td: recv IAC", c));
 236                                 SYNCHing = stilloob(net);
 237                                 settimer(gotDM);
 238                                 break;
 239
 240
 241                         /*
 242                          * Begin option subnegotiation...
 243                          */
 244                         case SB:
 245                                 state = TS_SB;
 246                                 SB_CLEAR();
 247                                 continue;
 248
 249                         case WILL:
 250                                 state = TS_WILL;
 251                                 continue;
 252
 253                         case WONT:
 254                                 state = TS_WONT;
 255                                 continue;
 256
 257                         case DO:
 258                                 state = TS_DO;
 259                                 continue;
 260
 261                         case DONT:
 262                                 state = TS_DONT;
 263                                 continue;
 264                         case EOR:
 265                                 if (his_state_is_will(TELOPT_EOR))
 266                                         doeof();
 267                                 break;
 268
 269                         /*
 270                          * Handle RFC 10xx Telnet linemode option additions
 271                          * to command stream (EOF, SUSP, ABORT).
 272                          */
 273                         case xEOF:
 274                                 doeof();
 275                                 break;
 276
 277                         case SUSP:
 278                                 sendsusp();
 279                                 break;
 280
 281                         case ABORT:
 282                                 sendbrk();
 283                                 break;
 284
 285                         case IAC:
 286                                 *pfrontp++ = c;
 287                                 break;
 288                         }
 289                         state = TS_DATA;
 290                         break;
 291
 292                 case TS_SB:
 293                         if (c == IAC) {
 294                                 state = TS_SE;
 295                         } else {
 296                                 SB_ACCUM(c);
 297                         }
 298                         break;
 299
 300                 case TS_SE:
 301                         if (c != SE) {
 302                                 if (c != IAC) {
 303                                         /*
 304                                          * bad form of suboption negotiation.
 305                                          * handle it in such a way as to avoid
 306                                          * damage to local state.  Parse
 307                                          * suboption buffer found so far,
 308                                          * then treat remaining stream as
 309                                          * another command sequence.
 310                                          */
 311
 312                                         /* for DIAGNOSTICS */
 313                                         SB_ACCUM(IAC);
 314                                         SB_ACCUM(c);
 315                                         subpointer -= 2;
 316
 317                                         SB_TERM();
 318                                         suboption();
 319                                         state = TS_IAC;
 320                                         goto gotiac;
 321                                 }
 322                                 SB_ACCUM(c);
 323                                 state = TS_SB;
 324                         } else {
 325                                 /* for DIAGNOSTICS */
 326                                 SB_ACCUM(IAC);
 327                                 SB_ACCUM(SE);
 328                                 subpointer -= 2;
 329
 330                                 SB_TERM();
 331                                 suboption();    /* handle sub-option */
 332                                 state = TS_DATA;
 333                         }
 334                         break;
 335
 336                 case TS_WILL:
 337                         willoption(c);
 338                         state = TS_DATA;
 339                         continue;
 340
 341                 case TS_WONT:
 342                         wontoption(c);
 343                         state = TS_DATA;
 344                         continue;
 345
 346                 case TS_DO:
 347                         dooption(c);
 348                         state = TS_DATA;
 349                         continue;
 350
 351                 case TS_DONT:
 352                         dontoption(c);
 353                         state = TS_DATA;
 354                         continue;
 355
 356                 default:
 357                         syslog(LOG_ERR, "panic state=%d", state);
 358                         printf("telnetd: panic state=%d\n", state);
 359                         exit(1);
 360                 }
 361         }
 362 }  /* end of telrcv */
 363
 364 /*
 365  * The will/wont/do/dont state machines are based on Dave Borman's
 366  * Telnet option processing state machine.
 367  *
 368  * These correspond to the following states:
 369  *      my_state = the last negotiated state
 370  *      want_state = what I want the state to go to
 371  *      want_resp = how many requests I have sent
 372  * All state defaults are negative, and resp defaults to 0.
 373  *
 374  * When initiating a request to change state to new_state:
 375  *
 376  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 377  *      do nothing;
 378  * } else {
 379  *      want_state = new_state;
 380  *      send new_state;
 381  *      want_resp++;
 382  * }
 383  *
 384  * When receiving new_state:
 385  *
 386  * if (want_resp) {
 387  *      want_resp--;
 388  *      if (want_resp && (new_state == my_state))
 389  *              want_resp--;
 390  * }
 391  * if ((want_resp == 0) && (new_state != want_state)) {
 392  *      if (ok_to_switch_to new_state)
 393  *              want_state = new_state;
 394  *      else
 395  *              want_resp++;
 396  *      send want_state;
 397  * }
 398  * my_state = new_state;
 399  *
 400  * Note that new_state is implied in these functions by the function itself.
 401  * will and do imply positive new_state, wont and dont imply negative.
 402  *
 403  * Finally, there is one catch.  If we send a negative response to a
 404  * positive request, my_state will be the positive while want_state will
 405  * remain negative.  my_state will revert to negative when the negative
 406  * acknowlegment arrives from the peer.  Thus, my_state generally tells
 407  * us not only the last negotiated state, but also tells us what the peer
 408  * wants to be doing as well.  It is important to understand this difference
 409  * as we may wish to be processing data streams based on our desired state
 410  * (want_state) or based on what the peer thinks the state is (my_state).
 411  *
 412  * This all works fine because if the peer sends a positive request, the data
 413  * that we receive prior to negative acknowlegment will probably be affected
 414  * by the positive state, and we can process it as such (if we can; if we
 415  * can't then it really doesn't matter).  If it is that important, then the
 416  * peer probably should be buffering until this option state negotiation
 417  * is complete.
 418  *
 419  */
 420 void
 421 send_do(int option, int init)
 422 {
 423         if (init) {
 424                 if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
 425                     his_want_state_is_will(option))
 426                         return;
 427                 /*
 428                  * Special case for TELOPT_TM:  We send a DO, but pretend
 429                  * that we sent a DONT, so that we can send more DOs if
 430                  * we want to.
 431                  */
 432                 if (option == TELOPT_TM)
 433                         set_his_want_state_wont(option);
 434                 else
 435                         set_his_want_state_will(option);
 436                 do_dont_resp[option]++;
 437         }
 438         output_data((const char *)doopt, option);
 439
 440         DIAG(TD_OPTIONS, printoption("td: send do", option));
 441 }
 442
 443 void
 444 willoption(int option)
 445 {
 446         int changeok = 0;
 447         void (*func)(void) = NULL;
 448
 449         /*
 450          * process input from peer.
 451          */
 452
 453         DIAG(TD_OPTIONS, printoption("td: recv will", option));
 454
 455         if (do_dont_resp[option]) {
 456                 do_dont_resp[option]--;
 457                 if (do_dont_resp[option] && his_state_is_will(option))
 458                         do_dont_resp[option]--;
 459         }
 460         if (do_dont_resp[option] == 0) {
 461             if (his_want_state_is_wont(option)) {
 462                 switch (option) {
 463
 464                 case TELOPT_BINARY:
 465                         init_termbuf();
 466                         tty_binaryin(1);
 467                         set_termbuf();
 468                         changeok++;
 469                         break;
 470
 471                 case TELOPT_ECHO:
 472                         /*
 473                          * See comments below for more info.
 474                          */
 475                         not42 = 0;      /* looks like a 4.2 system */
 476                         break;
 477
 478                 case TELOPT_TM:
 479 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 480                         /*
 481                          * This telnetd implementation does not really
 482                          * support timing marks, it just uses them to
 483                          * support the kludge linemode stuff.  If we
 484                          * receive a will or wont TM in response to our
 485                          * do TM request that may have been sent to
 486                          * determine kludge linemode support, process
 487                          * it, otherwise TM should get a negative
 488                          * response back.
 489                          */
 490                         /*
 491                          * Handle the linemode kludge stuff.
 492                          * If we are not currently supporting any
 493                          * linemode at all, then we assume that this
 494                          * is the client telling us to use kludge
 495                          * linemode in response to our query.  Set the
 496                          * linemode type that is to be supported, note
 497                          * that the client wishes to use linemode, and
 498                          * eat the will TM as though it never arrived.
 499                          */
 500                         if (lmodetype < KLUDGE_LINEMODE) {
 501                                 lmodetype = KLUDGE_LINEMODE;
 502                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 503                                 send_wont(TELOPT_SGA, 1);
 504                         } else if (lmodetype == NO_AUTOKLUDGE) {
 505                                 lmodetype = KLUDGE_OK;
 506                         }
 507 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 508                         /*
 509                          * We never respond to a WILL TM, and
 510                          * we leave the state WONT.
 511                          */
 512                         return;
 513
 514                 case TELOPT_LFLOW:
 515                         /*
 516                          * If we are going to support flow control
 517                          * option, then don't worry peer that we can't
 518                          * change the flow control characters.
 519                          */
 520                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 521                         slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 522                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 523                         slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 524                         /* FALLTHROUGH */
 525                 case TELOPT_TTYPE:
 526                 case TELOPT_SGA:
 527                 case TELOPT_NAWS:
 528                 case TELOPT_TSPEED:
 529                 case TELOPT_XDISPLOC:
 530                 case TELOPT_NEW_ENVIRON:
 531                 case TELOPT_OLD_ENVIRON:
 532                         changeok++;
 533                         break;
 534
 535 #ifdef  LINEMODE
 536                 case TELOPT_LINEMODE:
 537 # ifdef KLUDGELINEMODE
 538                         /*
 539                          * Note client's desire to use linemode.
 540                          */
 541                         lmodetype = REAL_LINEMODE;
 542 # endif /* KLUDGELINEMODE */
 543                         func = doclientstat;
 544                         changeok++;
 545                         break;
 546 #endif  /* LINEMODE */
 547
 548 #ifdef  AUTHENTICATION
 549                 case TELOPT_AUTHENTICATION:
 550                         func = auth_request;
 551                         changeok++;
 552                         break;
 553 #endif
 554
 555 #ifdef  ENCRYPTION
 556                 case TELOPT_ENCRYPT:
 557                         func = encrypt_send_support;
 558                         changeok++;
 559                         break;
 560 #endif  /* ENCRYPTION */
 561
 562                 default:
 563                         break;
 564                 }
 565                 if (changeok) {
 566                         set_his_want_state_will(option);
 567                         send_do(option, 0);
 568                 } else {
 569                         do_dont_resp[option]++;
 570                         send_dont(option, 0);
 571                 }
 572             } else {
 573                 /*
 574                  * Option processing that should happen when
 575                  * we receive conformation of a change in
 576                  * state that we had requested.
 577                  */
 578                 switch (option) {
 579                 case TELOPT_ECHO:
 580                         not42 = 0;      /* looks like a 4.2 system */
 581                         /*
 582                          * Egads, he responded "WILL ECHO".  Turn
 583                          * it off right now!
 584                          */
 585                         send_dont(option, 1);
 586                         /*
 587                          * "WILL ECHO".  Kludge upon kludge!
 588                          * A 4.2 client is now echoing user input at
 589                          * the tty.  This is probably undesireable and
 590                          * it should be stopped.  The client will
 591                          * respond WONT TM to the DO TM that we send to
 592                          * check for kludge linemode.  When the WONT TM
 593                          * arrives, linemode will be turned off and a
 594                          * change propogated to the pty.  This change
 595                          * will cause us to process the new pty state
 596                          * in localstat(), which will notice that
 597                          * linemode is off and send a WILL ECHO
 598                          * so that we are properly in character mode and
 599                          * all is well.
 600                          */
 601                         break;
 602 #ifdef  LINEMODE
 603                 case TELOPT_LINEMODE:
 604 # ifdef KLUDGELINEMODE
 605                         /*
 606                          * Note client's desire to use linemode.
 607                          */
 608                         lmodetype = REAL_LINEMODE;
 609 # endif /* KLUDGELINEMODE */
 610                         func = doclientstat;
 611                         break;
 612 #endif  /* LINEMODE */
 613
 614 #ifdef  AUTHENTICATION
 615                 case TELOPT_AUTHENTICATION:
 616                         func = auth_request;
 617                         break;
 618 #endif
 619
 620 #ifdef  ENCRYPTION
 621                 case TELOPT_ENCRYPT:
 622                         func = encrypt_send_support;
 623                         break;
 624 #endif  /* ENCRYPTION */
 625                 case TELOPT_LFLOW:
 626                         func = flowstat;
 627                         break;
 628                 }
 629             }
 630         }
 631         set_his_state_will(option);
 632         if (func)
 633                 (*func)();
 634 }  /* end of willoption */
 635
 636 void
 637 send_dont(int option, int init)
 638 {
 639         if (init) {
 640                 if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 641                     his_want_state_is_wont(option))
 642                         return;
 643                 set_his_want_state_wont(option);
 644                 do_dont_resp[option]++;
 645         }
 646         output_data((const char *)dont, option);
 647
 648         DIAG(TD_OPTIONS, printoption("td: send dont", option));
 649 }
 650
 651 void
 652 wontoption(int option)
 653 {
 654         /*
 655          * Process client input.
 656          */
 657
 658         DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 659
 660         if (do_dont_resp[option]) {
 661                 do_dont_resp[option]--;
 662                 if (do_dont_resp[option] && his_state_is_wont(option))
 663                         do_dont_resp[option]--;
 664         }
 665         if (do_dont_resp[option] == 0) {
 666             if (his_want_state_is_will(option)) {
 667                 /* it is always ok to change to negative state */
 668                 switch (option) {
 669                 case TELOPT_ECHO:
 670                         not42 = 1; /* doesn't seem to be a 4.2 system */
 671                         break;
 672
 673                 case TELOPT_BINARY:
 674                         init_termbuf();
 675                         tty_binaryin(0);
 676                         set_termbuf();
 677                         break;
 678
 679 #ifdef  LINEMODE
 680                 case TELOPT_LINEMODE:
 681 # ifdef KLUDGELINEMODE
 682                         /*
 683                          * If real linemode is supported, then client is
 684                          * asking to turn linemode off.
 685                          */
 686                         if (lmodetype != REAL_LINEMODE)
 687                                 break;
 688                         lmodetype = KLUDGE_LINEMODE;
 689 # endif /* KLUDGELINEMODE */
 690                         clientstat(TELOPT_LINEMODE, WONT, 0);
 691                         break;
 692 #endif  /* LINEMODE */
 693
 694                 case TELOPT_TM:
 695                         /*
 696                          * If we get a WONT TM, and had sent a DO TM,
 697                          * don't respond with a DONT TM, just leave it
 698                          * as is.  Short circut the state machine to
 699                          * achive this.
 700                          */
 701                         set_his_want_state_wont(TELOPT_TM);
 702                         return;
 703
 704                 case TELOPT_LFLOW:
 705                         /*
 706                          * If we are not going to support flow control
 707                          * option, then let peer know that we can't
 708                          * change the flow control characters.
 709                          */
 710                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 711                         slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 712                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 713                         slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 714                         break;
 715
 716 #ifdef  AUTHENTICATION
 717                 case TELOPT_AUTHENTICATION:
 718                         auth_finished(0, AUTH_REJECT);
 719                         break;
 720 #endif
 721
 722                 /*
 723                  * For options that we might spin waiting for
 724                  * sub-negotiation, if the client turns off the
 725                  * option rather than responding to the request,
 726                  * we have to treat it here as if we got a response
 727                  * to the sub-negotiation, (by updating the timers)
 728                  * so that we'll break out of the loop.
 729                  */
 730                 case TELOPT_TTYPE:
 731                         settimer(ttypesubopt);
 732                         break;
 733
 734                 case TELOPT_TSPEED:
 735                         settimer(tspeedsubopt);
 736                         break;
 737
 738                 case TELOPT_XDISPLOC:
 739                         settimer(xdisplocsubopt);
 740                         break;
 741
 742                 case TELOPT_OLD_ENVIRON:
 743                         settimer(oenvironsubopt);
 744                         break;
 745
 746                 case TELOPT_NEW_ENVIRON:
 747                         settimer(environsubopt);
 748                         break;
 749
 750                 default:
 751                         break;
 752                 }
 753                 set_his_want_state_wont(option);
 754                 if (his_state_is_will(option))
 755                         send_dont(option, 0);
 756             } else {
 757                 switch (option) {
 758                 case TELOPT_TM:
 759 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 760                         if (lmodetype < NO_AUTOKLUDGE) {
 761                                 lmodetype = NO_LINEMODE;
 762                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 763                                 send_will(TELOPT_SGA, 1);
 764                                 send_will(TELOPT_ECHO, 1);
 765                         }
 766 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 767                         break;
 768
 769 #ifdef AUTHENTICATION
 770                 case TELOPT_AUTHENTICATION:
 771                         auth_finished(0, AUTH_REJECT);
 772                         break;
 773 #endif
 774                 default:
 775                         break;
 776                 }
 777             }
 778         }
 779         set_his_state_wont(option);
 780
 781 }  /* end of wontoption */
 782
 783 void
 784 send_will(int option, int init)
 785 {
 786         if (init) {
 787                 if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 788                     my_want_state_is_will(option))
 789                         return;
 790                 set_my_want_state_will(option);
 791                 will_wont_resp[option]++;
 792         }
 793         output_data((const char *)will, option);
 794
 795         DIAG(TD_OPTIONS, printoption("td: send will", option));
 796 }
 797
 798 #if     !defined(LINEMODE) || !defined(KLUDGELINEMODE)
 799 /*
 800  * When we get a DONT SGA, we will try once to turn it
 801  * back on.  If the other side responds DONT SGA, we
 802  * leave it at that.  This is so that when we talk to
 803  * clients that understand KLUDGELINEMODE but not LINEMODE,
 804  * we'll keep them in char-at-a-time mode.
 805  */
 806 int turn_on_sga = 0;
 807 #endif
 808
 809 void
 810 dooption(int option)
 811 {
 812         int changeok = 0;
 813
 814         /*
 815          * Process client input.
 816          */
 817
 818         DIAG(TD_OPTIONS, printoption("td: recv do", option));
 819
 820         if (will_wont_resp[option]) {
 821                 will_wont_resp[option]--;
 822                 if (will_wont_resp[option] && my_state_is_will(option))
 823                         will_wont_resp[option]--;
 824         }
 825         if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 826                 switch (option) {
 827                 case TELOPT_ECHO:
 828 #ifdef  LINEMODE
 829 # ifdef KLUDGELINEMODE
 830                         if (lmodetype == NO_LINEMODE)
 831 # else
 832                         if (his_state_is_wont(TELOPT_LINEMODE))
 833 # endif
 834 #endif
 835                         {
 836                                 init_termbuf();
 837                                 tty_setecho(1);
 838                                 set_termbuf();
 839                         }
 840                         changeok++;
 841                         break;
 842
 843                 case TELOPT_BINARY:
 844                         init_termbuf();
 845                         tty_binaryout(1);
 846                         set_termbuf();
 847                         changeok++;
 848                         break;
 849
 850                 case TELOPT_SGA:
 851 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 852                         /*
 853                          * If kludge linemode is in use, then we must
 854                          * process an incoming do SGA for linemode
 855                          * purposes.
 856                          */
 857                         if (lmodetype == KLUDGE_LINEMODE) {
 858                                 /*
 859                                  * Receipt of "do SGA" in kludge
 860                                  * linemode is the peer asking us to
 861                                  * turn off linemode.  Make note of
 862                                  * the request.
 863                                  */
 864                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 865                                 /*
 866                                  * If linemode did not get turned off
 867                                  * then don't tell peer that we did.
 868                                  * Breaking here forces a wont SGA to
 869                                  * be returned.
 870                                  */
 871                                 if (linemode)
 872                                         break;
 873                         }
 874 #else
 875                         turn_on_sga = 0;
 876 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 877                         changeok++;
 878                         break;
 879
 880                 case TELOPT_STATUS:
 881                         changeok++;
 882                         break;
 883
 884                 case TELOPT_TM:
 885                         /*
 886                          * Special case for TM.  We send a WILL, but
 887                          * pretend we sent a WONT.
 888                          */
 889                         send_will(option, 0);
 890                         set_my_want_state_wont(option);
 891                         set_my_state_wont(option);
 892                         return;
 893
 894                 case TELOPT_LOGOUT:
 895                         /*
 896                          * When we get a LOGOUT option, respond
 897                          * with a WILL LOGOUT, make sure that
 898                          * it gets written out to the network,
 899                          * and then just go away...
 900                          */
 901                         set_my_want_state_will(TELOPT_LOGOUT);
 902                         send_will(TELOPT_LOGOUT, 0);
 903                         set_my_state_will(TELOPT_LOGOUT);
 904                         (void)netflush();
 905                         cleanup(0);
 906                         /* NOT REACHED */
 907                         break;
 908
 909 #ifdef  ENCRYPTION
 910                 case TELOPT_ENCRYPT:
 911                         changeok++;
 912                         break;
 913 #endif  /* ENCRYPTION */
 914                 case TELOPT_LINEMODE:
 915                 case TELOPT_TTYPE:
 916                 case TELOPT_NAWS:
 917                 case TELOPT_TSPEED:
 918                 case TELOPT_LFLOW:
 919                 case TELOPT_XDISPLOC:
 920 #ifdef  TELOPT_ENVIRON
 921                 case TELOPT_NEW_ENVIRON:
 922 #endif
 923                 case TELOPT_OLD_ENVIRON:
 924                 default:
 925                         break;
 926                 }
 927                 if (changeok) {
 928                         set_my_want_state_will(option);
 929                         send_will(option, 0);
 930                 } else {
 931                         will_wont_resp[option]++;
 932                         send_wont(option, 0);
 933                 }
 934         }
 935         set_my_state_will(option);
 936
 937 }  /* end of dooption */
 938
 939 void
 940 send_wont(int option, int init)
 941 {
 942         if (init) {
 943                 if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 944                     my_want_state_is_wont(option))
 945                         return;
 946                 set_my_want_state_wont(option);
 947                 will_wont_resp[option]++;
 948         }
 949         output_data((const char *)wont, option);
 950
 951         DIAG(TD_OPTIONS, printoption("td: send wont", option));
 952 }
 953
 954 void
 955 dontoption(int option)
 956 {
 957         /*
 958          * Process client input.
 959          */
 960
 961
 962         DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 963
 964         if (will_wont_resp[option]) {
 965                 will_wont_resp[option]--;
 966                 if (will_wont_resp[option] && my_state_is_wont(option))
 967                         will_wont_resp[option]--;
 968         }
 969         if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 970                 switch (option) {
 971                 case TELOPT_BINARY:
 972                         init_termbuf();
 973                         tty_binaryout(0);
 974                         set_termbuf();
 975                         break;
 976
 977                 case TELOPT_ECHO:       /* we should stop echoing */
 978 #ifdef  LINEMODE
 979 # ifdef KLUDGELINEMODE
 980                         if ((lmodetype != REAL_LINEMODE) &&
 981                             (lmodetype != KLUDGE_LINEMODE))
 982 # else
 983                         if (his_state_is_wont(TELOPT_LINEMODE))
 984 # endif
 985 #endif
 986                         {
 987                                 init_termbuf();
 988                                 tty_setecho(0);
 989                                 set_termbuf();
 990                         }
 991                         break;
 992
 993                 case TELOPT_SGA:
 994 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 995                         /*
 996                          * If kludge linemode is in use, then we
 997                          * must process an incoming do SGA for
 998                          * linemode purposes.
 999                          */
1000                         if ((lmodetype == KLUDGE_LINEMODE) ||
1001                             (lmodetype == KLUDGE_OK)) {
1002                                 /*
1003                                  * The client is asking us to turn
1004                                  * linemode on.
1005                                  */
1006                                 lmodetype = KLUDGE_LINEMODE;
1007                                 clientstat(TELOPT_LINEMODE, WILL, 0);
1008                                 /*
1009                                  * If we did not turn line mode on,
1010                                  * then what do we say?  Will SGA?
1011                                  * This violates design of telnet.
1012                                  * Gross.  Very Gross.
1013                                  */
1014                         }
1015                         break;
1016 #else
1017                         set_my_want_state_wont(option);
1018                         if (my_state_is_will(option))
1019                                 send_wont(option, 0);
1020                         set_my_state_wont(option);
1021                         if (turn_on_sga ^= 1)
1022                                 send_will(option, 1);
1023                         return;
1024 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
1025
1026                 default:
1027                         break;
1028                 }
1029
1030                 set_my_want_state_wont(option);
1031                 if (my_state_is_will(option))
1032                         send_wont(option, 0);
1033         }
1034         set_my_state_wont(option);
1035
1036 }  /* end of dontoption */
1037
1038 #ifdef  ENV_HACK
1039 int env_ovar = -1;
1040 int env_ovalue = -1;
1041 #else   /* ENV_HACK */
1042 # define env_ovar OLD_ENV_VAR
1043 # define env_ovalue OLD_ENV_VALUE
1044 #endif  /* ENV_HACK */
1045
1046 /* envvarok(char*) */
1047 /* check that variable is safe to pass to login or shell */
1048 static int
1049 envvarok(char *varp)
1050 {
1051
1052         if (strcmp(varp, "TERMCAP") &&  /* to prevent a security hole */
1053             strcmp(varp, "TERMINFO") && /* with tgetent */
1054             strcmp(varp, "TERMPATH") &&
1055             strcmp(varp, "HOME") &&     /* to prevent the tegetent bug  */
1056             strncmp(varp, "LD_", strlen("LD_")) &&      /* most systems */
1057             strncmp(varp, "_RLD_", strlen("_RLD_")) &&  /* IRIX */
1058             strcmp(varp, "LIBPATH") &&                  /* AIX */
1059             strcmp(varp, "ENV") &&
1060             strcmp(varp, "BASH_ENV") &&
1061             strcmp(varp, "IFS") &&
1062             strncmp(varp, "KRB5", strlen("KRB5")) &&    /* Krb5 */
1063             /*
1064              * The above case is a catch-all for now.  Here are some of
1065              * the specific ones we must avoid passing, at least until
1066              * we can prove it can be done safely.  Keep this list
1067              * around un case someone wants to remove the catch-all.
1068              */
1069             strcmp(varp, "KRB5_CONFIG") &&              /* Krb5 */
1070             strcmp(varp, "KRB5CCNAME") &&               /* Krb5 */
1071             strcmp(varp, "KRB5_KTNAME") &&              /* Krb5 */
1072             strcmp(varp, "KRBTKFILE") &&                /* Krb4 */
1073             strcmp(varp, "KRB_CONF") &&                 /* CNS 4 */
1074             strcmp(varp, "KRB_REALMS") &&               /* CNS 4 */
1075             strcmp(varp, "RESOLV_HOST_CONF"))           /* Linux */
1076                 return (1);
1077         else {
1078                 syslog(LOG_INFO, "Rejected the attempt to modify the "
1079                     "environment variable \"%s\"", varp);
1080                 return (0);
1081         }
1082 }
1083
1084 /*
1085  * suboption()
1086  *
1087  *      Look at the sub-option buffer, and try to be helpful to the other
1088  * side.
1089  *
1090  *      Currently we recognize:
1091  *
1092  *      Terminal type is
1093  *      Linemode
1094  *      Window size
1095  *      Terminal speed
1096  */
1097 void
1098 suboption(void)
1099 {
1100     int subchar;
1101
1102     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1103
1104     subchar = SB_GET();
1105     switch (subchar) {
1106     case TELOPT_TSPEED: {
1107         int xspeed, rspeed;
1108
1109         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
1110                 break;
1111
1112         settimer(tspeedsubopt);
1113
1114         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1115                 return;
1116
1117         xspeed = atoi((char *)subpointer);
1118
1119         while (SB_GET() != ',' && !SB_EOF());
1120         if (SB_EOF())
1121                 return;
1122
1123         rspeed = atoi((char *)subpointer);
1124         clientstat(TELOPT_TSPEED, xspeed, rspeed);
1125
1126         break;
1127
1128     }  /* end of case TELOPT_TSPEED */
1129
1130     case TELOPT_TTYPE: {                /* Yaaaay! */
1131         static char terminalname[TERMINAL_TYPE_SIZE];
1132
1133         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
1134                 break;
1135         settimer(ttypesubopt);
1136
1137         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1138             return;             /* ??? XXX but, this is the most robust */
1139         }
1140
1141         terminaltype = terminalname;
1142
1143         while ((terminaltype < (terminalname + sizeof terminalname-1)) &&
1144                                                                     !SB_EOF()) {
1145             int c;
1146
1147             c = SB_GET();
1148             if (isupper(c)) {
1149                 c = tolower(c);
1150             }
1151             *terminaltype++ = c;    /* accumulate name */
1152         }
1153         *terminaltype = 0;
1154         terminaltype = terminalname;
1155         break;
1156     }  /* end of case TELOPT_TTYPE */
1157
1158     case TELOPT_NAWS: {
1159         int xwinsize, ywinsize;
1160
1161         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
1162                 break;
1163
1164         if (SB_EOF())
1165                 return;
1166         xwinsize = SB_GET() << 8;
1167         if (SB_EOF())
1168                 return;
1169         xwinsize |= SB_GET();
1170         if (SB_EOF())
1171                 return;
1172         ywinsize = SB_GET() << 8;
1173         if (SB_EOF())
1174                 return;
1175         ywinsize |= SB_GET();
1176         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1177
1178         break;
1179
1180     }  /* end of case TELOPT_NAWS */
1181
1182 #ifdef  LINEMODE
1183     case TELOPT_LINEMODE: {
1184         int request;
1185
1186         if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
1187                 break;
1188         /*
1189          * Process linemode suboptions.
1190          */
1191         if (SB_EOF())
1192             break;              /* garbage was sent */
1193         request = SB_GET();     /* get will/wont */
1194
1195         if (SB_EOF())
1196             break;              /* another garbage check */
1197
1198         if (request == LM_SLC) {  /* SLC is not preceeded by WILL or WONT */
1199                 /*
1200                  * Process suboption buffer of slc's
1201                  */
1202                 start_slc(1);
1203                 do_opt_slc(subpointer, subend - subpointer);
1204                 (void) end_slc(0);
1205                 break;
1206         } else if (request == LM_MODE) {
1207                 if (SB_EOF())
1208                     return;
1209                 useeditmode = SB_GET();  /* get mode flag */
1210                 clientstat(LM_MODE, 0, 0);
1211                 break;
1212         }
1213
1214         if (SB_EOF())
1215             break;
1216         switch (SB_GET()) {  /* what suboption? */
1217         case LM_FORWARDMASK:
1218                 /*
1219                  * According to spec, only server can send request for
1220                  * forwardmask, and client can only return a positive response.
1221                  * So don't worry about it.
1222                  */
1223
1224         default:
1225                 break;
1226         }
1227         break;
1228     }  /* end of case TELOPT_LINEMODE */
1229 #endif
1230     case TELOPT_STATUS: {
1231         int mode;
1232
1233         if (SB_EOF())
1234             break;
1235         mode = SB_GET();
1236         switch (mode) {
1237         case TELQUAL_SEND:
1238             if (my_state_is_will(TELOPT_STATUS))
1239                 send_status();
1240             break;
1241
1242         case TELQUAL_IS:
1243             break;
1244
1245         default:
1246             break;
1247         }
1248         break;
1249     }  /* end of case TELOPT_STATUS */
1250
1251     case TELOPT_XDISPLOC: {
1252         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1253                 return;
1254         settimer(xdisplocsubopt);
1255         subpointer[SB_LEN()] = '\0';
1256         if (setenv("DISPLAY", (char *)subpointer, 1) == -1)
1257                 syslog(LOG_ERR, "setenv: cannot set DISPLAY=%s: %m", (char *)subpointer);
1258         break;
1259     }  /* end of case TELOPT_XDISPLOC */
1260
1261 #ifdef  TELOPT_NEW_ENVIRON
1262     case TELOPT_NEW_ENVIRON:
1263 #endif
1264     case TELOPT_OLD_ENVIRON: {
1265         int c;
1266         char *cp, *varp, *valp;
1267
1268         if (SB_EOF())
1269                 return;
1270         c = SB_GET();
1271         if (c == TELQUAL_IS) {
1272                 if (subchar == TELOPT_OLD_ENVIRON)
1273                         settimer(oenvironsubopt);
1274                 else
1275                         settimer(environsubopt);
1276         } else if (c != TELQUAL_INFO) {
1277                 return;
1278         }
1279
1280 #ifdef  TELOPT_NEW_ENVIRON
1281         if (subchar == TELOPT_NEW_ENVIRON) {
1282             while (!SB_EOF()) {
1283                 c = SB_GET();
1284                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1285                         break;
1286             }
1287         } else
1288 #endif
1289         {
1290 #ifdef  ENV_HACK
1291             /*
1292              * We only want to do this if we haven't already decided
1293              * whether or not the other side has its VALUE and VAR
1294              * reversed.
1295              */
1296             if (env_ovar < 0) {
1297                 int last = -1;          /* invalid value */
1298                 int empty = 0;
1299                 int got_var = 0, got_value = 0, got_uservar = 0;
1300
1301                 /*
1302                  * The other side might have its VALUE and VAR values
1303                  * reversed.  To be interoperable, we need to determine
1304                  * which way it is.  If the first recognized character
1305                  * is a VAR or VALUE, then that will tell us what
1306                  * type of client it is.  If the fist recognized
1307                  * character is a USERVAR, then we continue scanning
1308                  * the suboption looking for two consecutive
1309                  * VAR or VALUE fields.  We should not get two
1310                  * consecutive VALUE fields, so finding two
1311                  * consecutive VALUE or VAR fields will tell us
1312                  * what the client is.
1313                  */
1314                 SB_SAVE();
1315                 while (!SB_EOF()) {
1316                         c = SB_GET();
1317                         switch(c) {
1318                         case OLD_ENV_VAR:
1319                                 if (last < 0 || last == OLD_ENV_VAR
1320                                     || (empty && (last == OLD_ENV_VALUE)))
1321                                         goto env_ovar_ok;
1322                                 got_var++;
1323                                 last = OLD_ENV_VAR;
1324                                 break;
1325                         case OLD_ENV_VALUE:
1326                                 if (last < 0 || last == OLD_ENV_VALUE
1327                                     || (empty && (last == OLD_ENV_VAR)))
1328                                         goto env_ovar_wrong;
1329                                 got_value++;
1330                                 last = OLD_ENV_VALUE;
1331                                 break;
1332                         case ENV_USERVAR:
1333                                 /* count strings of USERVAR as one */
1334                                 if (last != ENV_USERVAR)
1335                                         got_uservar++;
1336                                 if (empty) {
1337                                         if (last == OLD_ENV_VALUE)
1338                                                 goto env_ovar_ok;
1339                                         if (last == OLD_ENV_VAR)
1340                                                 goto env_ovar_wrong;
1341                                 }
1342                                 last = ENV_USERVAR;
1343                                 break;
1344                         case ENV_ESC:
1345                                 if (!SB_EOF())
1346                                         c = SB_GET();
1347                                 /* FALL THROUGH */
1348                         default:
1349                                 empty = 0;
1350                                 continue;
1351                         }
1352                         empty = 1;
1353                 }
1354                 if (empty) {
1355                         if (last == OLD_ENV_VALUE)
1356                                 goto env_ovar_ok;
1357                         if (last == OLD_ENV_VAR)
1358                                 goto env_ovar_wrong;
1359                 }
1360                 /*
1361                  * Ok, the first thing was a USERVAR, and there
1362                  * are not two consecutive VAR or VALUE commands,
1363                  * and none of the VAR or VALUE commands are empty.
1364                  * If the client has sent us a well-formed option,
1365                  * then the number of VALUEs received should always
1366                  * be less than or equal to the number of VARs and
1367                  * USERVARs received.
1368                  *
1369                  * If we got exactly as many VALUEs as VARs and
1370                  * USERVARs, the client has the same definitions.
1371                  *
1372                  * If we got exactly as many VARs as VALUEs and
1373                  * USERVARS, the client has reversed definitions.
1374                  */
1375                 if (got_uservar + got_var == got_value) {
1376             env_ovar_ok:
1377                         env_ovar = OLD_ENV_VAR;
1378                         env_ovalue = OLD_ENV_VALUE;
1379                 } else if (got_uservar + got_value == got_var) {
1380             env_ovar_wrong:
1381                         env_ovar = OLD_ENV_VALUE;
1382                         env_ovalue = OLD_ENV_VAR;
1383                         DIAG(TD_OPTIONS,
1384                             output_data("ENVIRON VALUE and VAR are reversed!\r\n"));
1385
1386                 }
1387             }
1388             SB_RESTORE();
1389 #endif
1390
1391             while (!SB_EOF()) {
1392                 c = SB_GET();
1393                 if ((c == env_ovar) || (c == ENV_USERVAR))
1394                         break;
1395             }
1396         }
1397
1398         if (SB_EOF())
1399                 return;
1400
1401         cp = varp = (char *)subpointer;
1402         valp = NULL;
1403
1404         while (!SB_EOF()) {
1405                 c = SB_GET();
1406                 if (subchar == TELOPT_OLD_ENVIRON) {
1407                         if (c == env_ovar)
1408                                 c = NEW_ENV_VAR;
1409                         else if (c == env_ovalue)
1410                                 c = NEW_ENV_VALUE;
1411                 }
1412                 switch (c) {
1413
1414                 case NEW_ENV_VALUE:
1415                         *cp = '\0';
1416                         cp = valp = (char *)subpointer;
1417                         break;
1418
1419                 case NEW_ENV_VAR:
1420                 case ENV_USERVAR:
1421                         *cp = '\0';
1422                         if (envvarok(varp)) {
1423                                 if (valp) {
1424                                         if (setenv(varp, valp, 1) == -1)
1425                                                 syslog(LOG_ERR, "setenv: cannot set %s=%s: %m", varp, valp);
1426                                 }
1427                                 else
1428                                         unsetenv(varp);
1429                         }
1430                         cp = varp = (char *)subpointer;
1431                         valp = NULL;
1432                         break;
1433
1434                 case ENV_ESC:
1435                         if (SB_EOF())
1436                                 break;
1437                         c = SB_GET();
1438                         /* FALL THROUGH */
1439                 default:
1440                         *cp++ = c;
1441                         break;
1442                 }
1443         }
1444         *cp = '\0';
1445         if (envvarok(varp)) {
1446                 if (valp) {
1447                         if (setenv(varp, valp, 1) == -1)
1448                                 syslog(LOG_ERR, "setenv: cannot set %s=%s: %m", varp, valp);
1449                 }
1450                 else
1451                         unsetenv(varp);
1452         }
1453         break;
1454     }  /* end of case TELOPT_NEW_ENVIRON */
1455 #ifdef  AUTHENTICATION
1456     case TELOPT_AUTHENTICATION:
1457         if (SB_EOF())
1458                 break;
1459         switch(SB_GET()) {
1460         case TELQUAL_SEND:
1461         case TELQUAL_REPLY:
1462                 /*
1463                  * These are sent by us and cannot be sent by
1464                  * the client.
1465                  */
1466                 break;
1467         case TELQUAL_IS:
1468                 auth_is(subpointer, SB_LEN());
1469                 break;
1470         case TELQUAL_NAME:
1471                 auth_name(subpointer, SB_LEN());
1472                 break;
1473         }
1474         break;
1475 #endif
1476 #ifdef  ENCRYPTION
1477     case TELOPT_ENCRYPT:
1478         if (SB_EOF())
1479                 break;
1480         switch(SB_GET()) {
1481         case ENCRYPT_SUPPORT:
1482                 encrypt_support(subpointer, SB_LEN());
1483                 break;
1484         case ENCRYPT_IS:
1485                 encrypt_is(subpointer, SB_LEN());
1486                 break;
1487         case ENCRYPT_REPLY:
1488                 encrypt_reply(subpointer, SB_LEN());
1489                 break;
1490         case ENCRYPT_START:
1491                 encrypt_start(subpointer, SB_LEN());
1492                 break;
1493         case ENCRYPT_END:
1494                 encrypt_end();
1495                 break;
1496         case ENCRYPT_REQSTART:
1497                 encrypt_request_start(subpointer, SB_LEN());
1498                 break;
1499         case ENCRYPT_REQEND:
1500                 /*
1501                  * We can always send an REQEND so that we cannot
1502                  * get stuck encrypting.  We should only get this
1503                  * if we have been able to get in the correct mode
1504                  * anyhow.
1505                  */
1506                 encrypt_request_end();
1507                 break;
1508         case ENCRYPT_ENC_KEYID:
1509                 encrypt_enc_keyid(subpointer, SB_LEN());
1510                 break;
1511         case ENCRYPT_DEC_KEYID:
1512                 encrypt_dec_keyid(subpointer, SB_LEN());
1513                 break;
1514         default:
1515                 break;
1516         }
1517         break;
1518 #endif  /* ENCRYPTION */
1519
1520     default:
1521         break;
1522     }  /* end of switch */
1523
1524 }  /* end of suboption */
1525
1526 static void
1527 doclientstat(void)
1528 {
1529         clientstat(TELOPT_LINEMODE, WILL, 0);
1530 }
1531
1532 #define ADD(c)   *ncp++ = c
1533 #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1534 void
1535 send_status(void)
1536 {
1537         unsigned char statusbuf[256];
1538         unsigned char *ncp;
1539         unsigned char i;
1540
1541         ncp = statusbuf;
1542
1543         netflush();     /* get rid of anything waiting to go out */
1544
1545         ADD(IAC);
1546         ADD(SB);
1547         ADD(TELOPT_STATUS);
1548         ADD(TELQUAL_IS);
1549
1550         /*
1551          * We check the want_state rather than the current state,
1552          * because if we received a DO/WILL for an option that we
1553          * don't support, and the other side didn't send a DONT/WONT
1554          * in response to our WONT/DONT, then the "state" will be
1555          * WILL/DO, and the "want_state" will be WONT/DONT.  We
1556          * need to go by the latter.
1557          */
1558         for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1559                 if (my_want_state_is_will(i)) {
1560                         ADD(WILL);
1561                         ADD_DATA(i);
1562                         if (i == IAC)
1563                                 ADD(IAC);
1564                 }
1565                 if (his_want_state_is_will(i)) {
1566                         ADD(DO);
1567                         ADD_DATA(i);
1568                         if (i == IAC)
1569                                 ADD(IAC);
1570                 }
1571         }
1572
1573         if (his_want_state_is_will(TELOPT_LFLOW)) {
1574                 ADD(SB);
1575                 ADD(TELOPT_LFLOW);
1576                 if (flowmode) {
1577                         ADD(LFLOW_ON);
1578                 } else {
1579                         ADD(LFLOW_OFF);
1580                 }
1581                 ADD(SE);
1582
1583                 if (restartany >= 0) {
1584                         ADD(SB);
1585                         ADD(TELOPT_LFLOW);
1586                         if (restartany) {
1587                                 ADD(LFLOW_RESTART_ANY);
1588                         } else {
1589                                 ADD(LFLOW_RESTART_XON);
1590                         }
1591                         ADD(SE);
1592                 }
1593         }
1594
1595 #ifdef  LINEMODE
1596         if (his_want_state_is_will(TELOPT_LINEMODE)) {
1597                 unsigned char *cp, *cpe;
1598                 int len;
1599
1600                 ADD(SB);
1601                 ADD(TELOPT_LINEMODE);
1602                 ADD(LM_MODE);
1603                 ADD_DATA(editmode);
1604                 ADD(SE);
1605
1606                 ADD(SB);
1607                 ADD(TELOPT_LINEMODE);
1608                 ADD(LM_SLC);
1609                 start_slc(0);
1610                 send_slc();
1611                 len = end_slc(&cp);
1612                 for (cpe = cp + len; cp < cpe; cp++)
1613                         ADD_DATA(*cp);
1614                 ADD(SE);
1615         }
1616 #endif  /* LINEMODE */
1617
1618         ADD(IAC);
1619         ADD(SE);
1620
1621         output_datalen(statusbuf, ncp - statusbuf);
1622         netflush();     /* Send it on its way */
1623
1624         DIAG(TD_OPTIONS,
1625                 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1626 }
1627
1628 /*
1629  * This function appends data to nfrontp and advances nfrontp.
1630  * Returns the number of characters written altogether (the
1631  * buffer may have been flushed in the process).
1632  */
1633
1634 int
1635 output_data(const char *format, ...)
1636 {
1637         va_list args;
1638         int len;
1639         char *buf;
1640
1641         va_start(args, format);
1642         if ((len = vasprintf(&buf, format, args)) == -1) {
1643                 va_end(args);
1644                 return -1;
1645         }
1646         output_datalen(buf, len);
1647         va_end(args);
1648         free(buf);
1649         return (len);
1650 }
1651
1652 void
1653 output_datalen(const char *buf, int len)
1654 {
1655         int remaining, copied;
1656
1657         remaining = BUFSIZ - (nfrontp - netobuf);
1658         while (len > 0) {
1659                 /* Free up enough space if the room is too low*/
1660                 if ((len > BUFSIZ ? BUFSIZ : len) > remaining) {
1661                         netflush();
1662                         remaining = BUFSIZ - (nfrontp - netobuf);
1663                 }
1664
1665                 /* Copy out as much as will fit */
1666                 copied = remaining > len ? len : remaining;
1667                 memmove(nfrontp, buf, copied);
1668                 nfrontp += copied;
1669                 len -= copied;
1670                 remaining -= copied;
1671                 buf += copied;
1672         }
1673         return;
1674 }