libexec/telnetd/state.c

   1 /*      $NetBSD: state.c,v 1.29 2012/01/09 16:36:48 christos Exp $      */
   2
   3 /*
   4  * Copyright (c) 1989, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)state.c     8.5 (Berkeley) 5/30/95";
  36 #else
  37 __RCSID("$NetBSD: state.c,v 1.29 2012/01/09 16:36:48 christos Exp $");
  38 #endif
  39 #endif /* not lint */
  40
  41 #include <ctype.h>
  42 #include <stdarg.h>
  43
  44 #include "telnetd.h"
  45
  46 static int envvarok(char *);
  47
  48 int     not42 = 1;
  49
  50 /*
  51  * Buffer for sub-options, and macros
  52  * for suboptions buffer manipulations
  53  */
  54 unsigned char subbuffer[4096], *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 void
  86 telrcv(void)
  87 {
  88         int c;
  89         static int state = TS_DATA;
  90
  91         while (ncc > 0) {
  92                 if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
  93                         break;
  94                 c = *netip++ & 0377, ncc--;
  95 #ifdef  ENCRYPTION
  96                 if (decrypt_input)
  97                         c = (*decrypt_input)(c);
  98 #endif  /* ENCRYPTION */
  99                 switch (state) {
 100
 101                 case TS_CR:
 102                         state = TS_DATA;
 103                         /* Strip off \n or \0 after a \r */
 104                         if ((c == 0) || (c == '\n')) {
 105                                 break;
 106                         }
 107                         /* FALL THROUGH */
 108
 109                 case TS_DATA:
 110                         if (c == IAC) {
 111                                 state = TS_IAC;
 112                                 break;
 113                         }
 114                         /*
 115                          * We now map \r\n ==> \r for pragmatic reasons.
 116                          * Many client implementations send \r\n when
 117                          * the user hits the CarriageReturn key.
 118                          *
 119                          * We USED to map \r\n ==> \n, since \r\n says
 120                          * that we want to be in column 1 of the next
 121                          * printable line, and \n is the standard
 122                          * unix way of saying that (\r is only good
 123                          * if CRMOD is set, which it normally is).
 124                          */
 125                         if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 126 #ifndef __minix
 127                                 int nc = *netip;
 128 #endif /* !__minix */
 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         (void) output_data("%c%c%c", IAC, DO, option);
 439
 440         DIAG(TD_OPTIONS, printoption("td: send do", option));
 441 }
 442
 443 #ifdef  LINEMODE
 444 extern void doclientstat(void);
 445 #endif
 446 #if 0
 447 #ifdef  AUTHENTICATION
 448 extern void auth_request(void); /* libtelnet */
 449 #endif
 450 #ifdef  ENCRYPTION
 451 extern void encrypt_send_support(void);
 452 #endif  /* ENCRYPTION */
 453 #endif
 454
 455 void
 456 willoption(int option)
 457 {
 458         int changeok = 0;
 459         void (*func)(void) = 0;
 460
 461         /*
 462          * process input from peer.
 463          */
 464
 465         DIAG(TD_OPTIONS, printoption("td: recv will", option));
 466
 467         if (do_dont_resp[option]) {
 468                 do_dont_resp[option]--;
 469                 if (do_dont_resp[option] && his_state_is_will(option))
 470                         do_dont_resp[option]--;
 471         }
 472         if (do_dont_resp[option] == 0) {
 473             if (his_want_state_is_wont(option)) {
 474                 switch (option) {
 475
 476                 case TELOPT_BINARY:
 477                         init_termbuf();
 478                         tty_binaryin(1);
 479                         set_termbuf();
 480                         changeok++;
 481                         break;
 482
 483                 case TELOPT_ECHO:
 484                         /*
 485                          * See comments below for more info.
 486                          */
 487                         not42 = 0;      /* looks like a 4.2 system */
 488                         break;
 489
 490                 case TELOPT_TM:
 491 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 492                         /*
 493                          * This telnetd implementation does not really
 494                          * support timing marks, it just uses them to
 495                          * support the kludge linemode stuff.  If we
 496                          * receive a will or wont TM in response to our
 497                          * do TM request that may have been sent to
 498                          * determine kludge linemode support, process
 499                          * it, otherwise TM should get a negative
 500                          * response back.
 501                          */
 502                         /*
 503                          * Handle the linemode kludge stuff.
 504                          * If we are not currently supporting any
 505                          * linemode at all, then we assume that this
 506                          * is the client telling us to use kludge
 507                          * linemode in response to our query.  Set the
 508                          * linemode type that is to be supported, note
 509                          * that the client wishes to use linemode, and
 510                          * eat the will TM as though it never arrived.
 511                          */
 512                         if (lmodetype < KLUDGE_LINEMODE) {
 513                                 lmodetype = KLUDGE_LINEMODE;
 514                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 515                                 send_wont(TELOPT_SGA, 1);
 516                         } else if (lmodetype == NO_AUTOKLUDGE) {
 517                                 lmodetype = KLUDGE_OK;
 518                         }
 519 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 520                         /*
 521                          * We never respond to a WILL TM, and
 522                          * we leave the state WONT.
 523                          */
 524                         return;
 525
 526                 case TELOPT_LFLOW:
 527                         /*
 528                          * If we are going to support flow control
 529                          * option, then don't worry peer that we can't
 530                          * change the flow control characters.
 531                          */
 532                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 533                         slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 534                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 535                         slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 536                 case TELOPT_TTYPE:
 537                 case TELOPT_SGA:
 538                 case TELOPT_NAWS:
 539                 case TELOPT_TSPEED:
 540                 case TELOPT_XDISPLOC:
 541                 case TELOPT_NEW_ENVIRON:
 542                 case TELOPT_OLD_ENVIRON:
 543                         changeok++;
 544                         break;
 545
 546 #ifdef  LINEMODE
 547                 case TELOPT_LINEMODE:
 548 # ifdef KLUDGELINEMODE
 549                         /*
 550                          * Note client's desire to use linemode.
 551                          */
 552                         lmodetype = REAL_LINEMODE;
 553 # endif /* KLUDGELINEMODE */
 554                         func = doclientstat;
 555                         changeok++;
 556                         break;
 557 #endif  /* LINEMODE */
 558
 559 #ifdef  AUTHENTICATION
 560                 case TELOPT_AUTHENTICATION:
 561                         func = auth_request;
 562                         changeok++;
 563                         break;
 564 #endif
 565
 566 #ifdef  ENCRYPTION
 567                 case TELOPT_ENCRYPT:
 568                         func = encrypt_send_support;
 569                         changeok++;
 570                         break;
 571 #endif  /* ENCRYPTION */
 572
 573                 default:
 574                         break;
 575                 }
 576                 if (changeok) {
 577                         set_his_want_state_will(option);
 578                         send_do(option, 0);
 579                 } else {
 580                         do_dont_resp[option]++;
 581                         send_dont(option, 0);
 582                 }
 583             } else {
 584                 /*
 585                  * Option processing that should happen when
 586                  * we receive conformation of a change in
 587                  * state that we had requested.
 588                  */
 589                 switch (option) {
 590                 case TELOPT_ECHO:
 591                         not42 = 0;      /* looks like a 4.2 system */
 592                         /*
 593                          * Egads, he responded "WILL ECHO".  Turn
 594                          * it off right now!
 595                          */
 596                         send_dont(option, 1);
 597                         /*
 598                          * "WILL ECHO".  Kludge upon kludge!
 599                          * A 4.2 client is now echoing user input at
 600                          * the tty.  This is probably undesireable and
 601                          * it should be stopped.  The client will
 602                          * respond WONT TM to the DO TM that we send to
 603                          * check for kludge linemode.  When the WONT TM
 604                          * arrives, linemode will be turned off and a
 605                          * change propogated to the pty.  This change
 606                          * will cause us to process the new pty state
 607                          * in localstat(), which will notice that
 608                          * linemode is off and send a WILL ECHO
 609                          * so that we are properly in character mode and
 610                          * all is well.
 611                          */
 612                         break;
 613 #ifdef  LINEMODE
 614                 case TELOPT_LINEMODE:
 615 # ifdef KLUDGELINEMODE
 616                         /*
 617                          * Note client's desire to use linemode.
 618                          */
 619                         lmodetype = REAL_LINEMODE;
 620 # endif /* KLUDGELINEMODE */
 621                         func = doclientstat;
 622                         break;
 623 #endif  /* LINEMODE */
 624
 625 #ifdef  AUTHENTICATION
 626                 case TELOPT_AUTHENTICATION:
 627                         func = auth_request;
 628                         break;
 629 #endif
 630
 631 #ifdef  ENCRYPTION
 632                 case TELOPT_ENCRYPT:
 633                         func = encrypt_send_support;
 634                         break;
 635 #endif  /* ENCRYPTION */
 636
 637                 case TELOPT_LFLOW:
 638                         func = flowstat;
 639                         break;
 640                 }
 641             }
 642         }
 643         set_his_state_will(option);
 644         if (func)
 645                 (*func)();
 646 }  /* end of willoption */
 647
 648 void
 649 send_dont(int option, int init)
 650 {
 651         if (init) {
 652                 if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 653                     his_want_state_is_wont(option))
 654                         return;
 655                 set_his_want_state_wont(option);
 656                 do_dont_resp[option]++;
 657         }
 658         (void) output_data("%c%c%c", IAC, DONT, option);
 659
 660         DIAG(TD_OPTIONS, printoption("td: send dont", option));
 661 }
 662
 663 void
 664 wontoption(int option)
 665 {
 666         /*
 667          * Process client input.
 668          */
 669
 670         DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 671
 672         if (do_dont_resp[option]) {
 673                 do_dont_resp[option]--;
 674                 if (do_dont_resp[option] && his_state_is_wont(option))
 675                         do_dont_resp[option]--;
 676         }
 677         if (do_dont_resp[option] == 0) {
 678             if (his_want_state_is_will(option)) {
 679                 /* it is always ok to change to negative state */
 680                 switch (option) {
 681                 case TELOPT_ECHO:
 682                         not42 = 1; /* doesn't seem to be a 4.2 system */
 683                         break;
 684
 685                 case TELOPT_BINARY:
 686                         init_termbuf();
 687                         tty_binaryin(0);
 688                         set_termbuf();
 689                         break;
 690
 691 #ifdef  LINEMODE
 692                 case TELOPT_LINEMODE:
 693 # ifdef KLUDGELINEMODE
 694                         /*
 695                          * If real linemode is supported, then client is
 696                          * asking to turn linemode off.
 697                          */
 698                         if (lmodetype != REAL_LINEMODE)
 699                                 break;
 700                         /* XXX double-check this --thorpej */
 701                         lmodetype = KLUDGE_LINEMODE;
 702 # endif /* KLUDGELINEMODE */
 703                         clientstat(TELOPT_LINEMODE, WONT, 0);
 704                         break;
 705 #endif  /* LINEMODE */
 706
 707                 case TELOPT_TM:
 708                         /*
 709                          * If we get a WONT TM, and had sent a DO TM,
 710                          * don't respond with a DONT TM, just leave it
 711                          * as is.  Short circut the state machine to
 712                          * achieve this.
 713                          */
 714                         set_his_want_state_wont(TELOPT_TM);
 715                         return;
 716
 717                 case TELOPT_LFLOW:
 718                         /*
 719                          * If we are not going to support flow control
 720                          * option, then let peer know that we can't
 721                          * change the flow control characters.
 722                          */
 723                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 724                         slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 725                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 726                         slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 727                         break;
 728
 729 #ifdef AUTHENTICATION
 730                 case TELOPT_AUTHENTICATION:
 731                         auth_finished(0, AUTH_REJECT);
 732                         break;
 733 #endif
 734
 735                 /*
 736                  * For options that we might spin waiting for
 737                  * sub-negotiation, if the client turns off the
 738                  * option rather than responding to the request,
 739                  * we have to treat it here as if we got a response
 740                  * to the sub-negotiation, (by updating the timers)
 741                  * so that we'll break out of the loop.
 742                  */
 743                 case TELOPT_TTYPE:
 744                         settimer(ttypesubopt);
 745                         break;
 746
 747                 case TELOPT_TSPEED:
 748                         settimer(tspeedsubopt);
 749                         break;
 750
 751                 case TELOPT_XDISPLOC:
 752                         settimer(xdisplocsubopt);
 753                         break;
 754
 755                 case TELOPT_OLD_ENVIRON:
 756                         settimer(oenvironsubopt);
 757                         break;
 758
 759                 case TELOPT_NEW_ENVIRON:
 760                         settimer(environsubopt);
 761                         break;
 762
 763                 default:
 764                         break;
 765                 }
 766                 set_his_want_state_wont(option);
 767                 if (his_state_is_will(option))
 768                         send_dont(option, 0);
 769             } else {
 770                 switch (option) {
 771                 case TELOPT_TM:
 772 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 773                         if (lmodetype < NO_AUTOKLUDGE) {
 774                                 lmodetype = NO_LINEMODE;
 775                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 776                                 send_will(TELOPT_SGA, 1);
 777                                 send_will(TELOPT_ECHO, 1);
 778                         }
 779 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 780                         break;
 781
 782 #ifdef AUTHENTICATION
 783                 case TELOPT_AUTHENTICATION:
 784                         auth_finished(0, AUTH_REJECT);
 785                         break;
 786 #endif
 787                 default:
 788                         break;
 789                 }
 790             }
 791         }
 792         set_his_state_wont(option);
 793
 794 }  /* end of wontoption */
 795
 796 void
 797 send_will(int option, int init)
 798 {
 799         if (init) {
 800                 if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 801                     my_want_state_is_will(option))
 802                         return;
 803                 set_my_want_state_will(option);
 804                 will_wont_resp[option]++;
 805         }
 806         (void) output_data("%c%c%c", IAC, WILL, option);
 807
 808         DIAG(TD_OPTIONS, printoption("td: send will", option));
 809 }
 810
 811 #if     !defined(LINEMODE) || !defined(KLUDGELINEMODE)
 812 /*
 813  * When we get a DONT SGA, we will try once to turn it
 814  * back on.  If the other side responds DONT SGA, we
 815  * leave it at that.  This is so that when we talk to
 816  * clients that understand KLUDGELINEMODE but not LINEMODE,
 817  * we'll keep them in char-at-a-time mode.
 818  */
 819 int turn_on_sga = 0;
 820 #endif
 821
 822 void
 823 dooption(int option)
 824 {
 825         int changeok = 0;
 826
 827         /*
 828          * Process client input.
 829          */
 830
 831         DIAG(TD_OPTIONS, printoption("td: recv do", option));
 832
 833         if (will_wont_resp[option]) {
 834                 will_wont_resp[option]--;
 835                 if (will_wont_resp[option] && my_state_is_will(option))
 836                         will_wont_resp[option]--;
 837         }
 838         if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 839                 switch (option) {
 840                 case TELOPT_ECHO:
 841 #ifdef  LINEMODE
 842 # ifdef KLUDGELINEMODE
 843                         if (lmodetype == NO_LINEMODE)
 844 # else
 845                         if (his_state_is_wont(TELOPT_LINEMODE))
 846 # endif
 847 #endif
 848                         {
 849                                 init_termbuf();
 850                                 tty_setecho(1);
 851                                 set_termbuf();
 852                         }
 853                         changeok++;
 854                         break;
 855
 856                 case TELOPT_BINARY:
 857                         init_termbuf();
 858                         tty_binaryout(1);
 859                         set_termbuf();
 860                         changeok++;
 861                         break;
 862
 863                 case TELOPT_SGA:
 864 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 865                         /*
 866                          * If kludge linemode is in use, then we must
 867                          * process an incoming do SGA for linemode
 868                          * purposes.
 869                          */
 870                         if (lmodetype == KLUDGE_LINEMODE) {
 871                                 /*
 872                                  * Receipt of "do SGA" in kludge
 873                                  * linemode is the peer asking us to
 874                                  * turn off linemode.  Make note of
 875                                  * the request.
 876                                  */
 877                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 878                                 /*
 879                                  * If linemode did not get turned off
 880                                  * then don't tell peer that we did.
 881                                  * Breaking here forces a wont SGA to
 882                                  * be returned.
 883                                  */
 884                                 if (linemode)
 885                                         break;
 886                         }
 887 #else
 888                         turn_on_sga = 0;
 889 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 890                         changeok++;
 891                         break;
 892
 893                 case TELOPT_STATUS:
 894                         changeok++;
 895                         break;
 896
 897                 case TELOPT_TM:
 898                         /*
 899                          * Special case for TM.  We send a WILL, but
 900                          * pretend we sent a WONT.
 901                          */
 902                         send_will(option, 0);
 903                         set_my_want_state_wont(option);
 904                         set_my_state_wont(option);
 905                         return;
 906
 907                 case TELOPT_LOGOUT:
 908                         /*
 909                          * When we get a LOGOUT option, respond
 910                          * with a WILL LOGOUT, make sure that
 911                          * it gets written out to the network,
 912                          * and then just go away...
 913                          */
 914                         set_my_want_state_will(TELOPT_LOGOUT);
 915                         send_will(TELOPT_LOGOUT, 0);
 916                         set_my_state_will(TELOPT_LOGOUT);
 917                         (void)netflush();
 918                         cleanup(0);
 919                         /* NOT REACHED */
 920                         break;
 921
 922 #ifdef  ENCRYPTION
 923                 case TELOPT_ENCRYPT:
 924                         changeok++;
 925                         break;
 926 #endif  /* ENCRYPTION */
 927
 928                 case TELOPT_LINEMODE:
 929                 case TELOPT_TTYPE:
 930                 case TELOPT_NAWS:
 931                 case TELOPT_TSPEED:
 932                 case TELOPT_LFLOW:
 933                 case TELOPT_XDISPLOC:
 934                 case TELOPT_OLD_ENVIRON:
 935                 default:
 936                         break;
 937                 }
 938                 if (changeok) {
 939                         set_my_want_state_will(option);
 940                         send_will(option, 0);
 941                 } else {
 942                         will_wont_resp[option]++;
 943                         send_wont(option, 0);
 944                 }
 945         }
 946         set_my_state_will(option);
 947
 948 }  /* end of dooption */
 949
 950 void
 951 send_wont(int option, int init)
 952 {
 953         if (init) {
 954                 if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 955                     my_want_state_is_wont(option))
 956                         return;
 957                 set_my_want_state_wont(option);
 958                 will_wont_resp[option]++;
 959         }
 960         (void) output_data("%c%c%c", IAC, WONT, option);
 961
 962         DIAG(TD_OPTIONS, printoption("td: send wont", option));
 963 }
 964
 965 void
 966 dontoption(int option)
 967 {
 968         /*
 969          * Process client input.
 970          */
 971
 972
 973         DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 974
 975         if (will_wont_resp[option]) {
 976                 will_wont_resp[option]--;
 977                 if (will_wont_resp[option] && my_state_is_wont(option))
 978                         will_wont_resp[option]--;
 979         }
 980         if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 981                 switch (option) {
 982                 case TELOPT_BINARY:
 983                         init_termbuf();
 984                         tty_binaryout(0);
 985                         set_termbuf();
 986                         break;
 987
 988                 case TELOPT_ECHO:       /* we should stop echoing */
 989 #ifdef  LINEMODE
 990 # ifdef KLUDGELINEMODE
 991                         if ((lmodetype != REAL_LINEMODE) &&
 992                             (lmodetype != KLUDGE_LINEMODE))
 993 # else
 994                         if (his_state_is_wont(TELOPT_LINEMODE))
 995 # endif
 996 #endif
 997                         {
 998                                 init_termbuf();
 999                                 tty_setecho(0);
1000                                 set_termbuf();
1001                         }
1002                         break;
1003
1004                 case TELOPT_SGA:
1005 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
1006                         /*
1007                          * If kludge linemode is in use, then we
1008                          * must process an incoming do SGA for
1009                          * linemode purposes.
1010                          */
1011                         if ((lmodetype == KLUDGE_LINEMODE) ||
1012                             (lmodetype == KLUDGE_OK)) {
1013                                 /*
1014                                  * The client is asking us to turn
1015                                  * linemode on.
1016                                  */
1017                                 lmodetype = KLUDGE_LINEMODE;
1018                                 clientstat(TELOPT_LINEMODE, WILL, 0);
1019                                 /*
1020                                  * If we did not turn line mode on,
1021                                  * then what do we say?  Will SGA?
1022                                  * This violates design of telnet.
1023                                  * Gross.  Very Gross.
1024                                  */
1025                         }
1026                         break;
1027 #else
1028                         set_my_want_state_wont(option);
1029                         if (my_state_is_will(option))
1030                                 send_wont(option, 0);
1031                         set_my_state_wont(option);
1032                         if (turn_on_sga ^= 1)
1033                                 send_will(option, 1);
1034                         return;
1035 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
1036
1037                 default:
1038                         break;
1039                 }
1040
1041                 set_my_want_state_wont(option);
1042                 if (my_state_is_will(option))
1043                         send_wont(option, 0);
1044         }
1045         set_my_state_wont(option);
1046
1047 }  /* end of dontoption */
1048
1049 #ifdef  ENV_HACK
1050 int env_ovar = -1;
1051 int env_ovalue = -1;
1052 #else   /* ENV_HACK */
1053 # define env_ovar OLD_ENV_VAR
1054 # define env_ovalue OLD_ENV_VALUE
1055 #endif  /* ENV_HACK */
1056
1057 /* envvarok(char*) */
1058 /* check that variable is safe to pass to login or shell */
1059 static int
1060 envvarok(char *varp)
1061 {
1062
1063         if (strcmp(varp, "TERMCAP") &&  /* to prevent a security hole */
1064             strcmp(varp, "TERMINFO") && /* with tgetent */
1065             strcmp(varp, "TERMPATH") &&
1066             strcmp(varp, "HOME") &&     /* to prevent the tegetent bug  */
1067             strncmp(varp, "LD_", strlen("LD_")) &&      /* most systems */
1068             strncmp(varp, "_RLD_", strlen("_RLD_")) &&  /* IRIX */
1069             strcmp(varp, "LIBPATH") &&                  /* AIX */
1070             strcmp(varp, "ENV") &&
1071             strcmp(varp, "BASH_ENV") &&
1072             strcmp(varp, "IFS") &&
1073             strncmp(varp, "KRB5", strlen("KRB5")) &&    /* Krb5 */
1074             /*
1075              * The above case is a catch-all for now.  Here are some of
1076              * the specific ones we must avoid passing, at least until
1077              * we can prove it can be done safely.  Keep this list
1078              * around un case someone wants to remove the catch-all.
1079              */
1080             strcmp(varp, "KRB5_CONFIG") &&              /* Krb5 */
1081             strcmp(varp, "KRB5CCNAME") &&               /* Krb5 */
1082             strcmp(varp, "KRB5_KTNAME") &&              /* Krb5 */
1083             strcmp(varp, "KRBTKFILE") &&                /* Krb4 */
1084             strcmp(varp, "KRB_CONF") &&                 /* CNS 4 */
1085             strcmp(varp, "KRB_REALMS") &&               /* CNS 4 */
1086             strcmp(varp, "RESOLV_HOST_CONF"))           /* Linux */
1087                 return (1);
1088         else {
1089                 syslog(LOG_INFO, "Rejected the attempt to modify the "
1090                     "environment variable \"%s\"", varp);
1091                 return (0);
1092         }
1093 }
1094
1095 /*
1096  * suboption()
1097  *
1098  *      Look at the sub-option buffer, and try to be helpful to the other
1099  * side.
1100  *
1101  *      Currently we recognize:
1102  *
1103  *      Terminal type is
1104  *      Linemode
1105  *      Window size
1106  *      Terminal speed
1107  */
1108 void
1109 suboption(void)
1110 {
1111     int subchar;
1112
1113     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1114
1115     subchar = SB_GET();
1116     switch (subchar) {
1117     case TELOPT_TSPEED: {
1118         int xspeed, rspeed;
1119
1120         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
1121                 break;
1122
1123         settimer(tspeedsubopt);
1124
1125         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1126                 return;
1127
1128         xspeed = atoi((char *)subpointer);
1129
1130         while (SB_GET() != ',' && !SB_EOF());
1131         if (SB_EOF())
1132                 return;
1133
1134         rspeed = atoi((char *)subpointer);
1135         clientstat(TELOPT_TSPEED, xspeed, rspeed);
1136
1137         break;
1138
1139     }  /* end of case TELOPT_TSPEED */
1140
1141     case TELOPT_TTYPE: {                /* Yaaaay! */
1142         char *p;
1143
1144         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
1145                 break;
1146         settimer(ttypesubopt);
1147
1148         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1149             return;             /* ??? XXX but, this is the most robust */
1150         }
1151
1152         p = terminaltype;
1153
1154         while ((p < (terminaltype + sizeof terminaltype-1)) &&
1155                                                                     !SB_EOF()) {
1156             int c;
1157
1158             c = SB_GET();
1159             if (isupper(c)) {
1160                 c = tolower(c);
1161             }
1162             *p++ = c;    /* accumulate name */
1163         }
1164         *p = 0;
1165         break;
1166     }  /* end of case TELOPT_TTYPE */
1167
1168     case TELOPT_NAWS: {
1169         int xwinsize, ywinsize;
1170
1171         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
1172                 break;
1173
1174         if (SB_EOF())
1175                 return;
1176         xwinsize = SB_GET() << 8;
1177         if (SB_EOF())
1178                 return;
1179         xwinsize |= SB_GET();
1180         if (SB_EOF())
1181                 return;
1182         ywinsize = SB_GET() << 8;
1183         if (SB_EOF())
1184                 return;
1185         ywinsize |= SB_GET();
1186         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1187
1188         break;
1189
1190     }  /* end of case TELOPT_NAWS */
1191
1192 #ifdef  LINEMODE
1193     case TELOPT_LINEMODE: {
1194         int request;
1195
1196         if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
1197                 break;
1198         /*
1199          * Process linemode suboptions.
1200          */
1201         if (SB_EOF())
1202             break;              /* garbage was sent */
1203         request = SB_GET();     /* get will/wont */
1204
1205         if (SB_EOF())
1206             break;              /* another garbage check */
1207
1208         if (request == LM_SLC) {  /* SLC is not preceded by WILL or WONT */
1209                 /*
1210                  * Process suboption buffer of slc's
1211                  */
1212                 start_slc(1);
1213                 do_opt_slc(subpointer, SB_LEN());
1214                 (void) end_slc(0);
1215                 break;
1216         } else if (request == LM_MODE) {
1217                 if (SB_EOF())
1218                     return;
1219                 useeditmode = SB_GET();  /* get mode flag */
1220                 clientstat(LM_MODE, 0, 0);
1221                 break;
1222         }
1223
1224         if (SB_EOF())
1225             break;
1226         switch (SB_GET()) {  /* what suboption? */
1227         case LM_FORWARDMASK:
1228                 /*
1229                  * According to spec, only server can send request for
1230                  * forwardmask, and client can only return a positive response.
1231                  * So don't worry about it.
1232                  */
1233
1234         default:
1235                 break;
1236         }
1237         break;
1238     }  /* end of case TELOPT_LINEMODE */
1239 #endif
1240     case TELOPT_STATUS: {
1241         int mode;
1242
1243         if (SB_EOF())
1244             break;
1245         mode = SB_GET();
1246         switch (mode) {
1247         case TELQUAL_SEND:
1248             if (my_state_is_will(TELOPT_STATUS))
1249                 send_status();
1250             break;
1251
1252         case TELQUAL_IS:
1253             break;
1254
1255         default:
1256             break;
1257         }
1258         break;
1259     }  /* end of case TELOPT_STATUS */
1260
1261     case TELOPT_XDISPLOC: {
1262         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1263                 return;
1264         settimer(xdisplocsubopt);
1265         subpointer[SB_LEN()] = '\0';
1266         (void)setenv("DISPLAY", (char *)subpointer, 1);
1267         break;
1268     }  /* end of case TELOPT_XDISPLOC */
1269
1270     case TELOPT_NEW_ENVIRON:
1271     case TELOPT_OLD_ENVIRON: {
1272         int c;
1273         char *cp, *varp, *valp;
1274
1275         if (SB_EOF())
1276                 return;
1277         c = SB_GET();
1278         if (c == TELQUAL_IS) {
1279                 if (subchar == TELOPT_OLD_ENVIRON)
1280                         settimer(oenvironsubopt);
1281                 else
1282                         settimer(environsubopt);
1283         } else if (c != TELQUAL_INFO) {
1284                 return;
1285         }
1286
1287         if (subchar == TELOPT_NEW_ENVIRON) {
1288             while (!SB_EOF()) {
1289                 c = SB_GET();
1290                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1291                         break;
1292             }
1293         } else
1294         {
1295 #ifdef  ENV_HACK
1296             /*
1297              * We only want to do this if we haven't already decided
1298              * whether or not the other side has its VALUE and VAR
1299              * reversed.
1300              */
1301             if (env_ovar < 0) {
1302                 int last = -1;          /* invalid value */
1303                 int empty = 0;
1304                 int got_var = 0, got_value = 0, got_uservar = 0;
1305
1306                 /*
1307                  * The other side might have its VALUE and VAR values
1308                  * reversed.  To be interoperable, we need to determine
1309                  * which way it is.  If the first recognized character
1310                  * is a VAR or VALUE, then that will tell us what
1311                  * type of client it is.  If the fist recognized
1312                  * character is a USERVAR, then we continue scanning
1313                  * the suboption looking for two consecutive
1314                  * VAR or VALUE fields.  We should not get two
1315                  * consecutive VALUE fields, so finding two
1316                  * consecutive VALUE or VAR fields will tell us
1317                  * what the client is.
1318                  */
1319                 SB_SAVE();
1320                 while (!SB_EOF()) {
1321                         c = SB_GET();
1322                         switch(c) {
1323                         case OLD_ENV_VAR:
1324                                 if (last < 0 || last == OLD_ENV_VAR
1325                                     || (empty && (last == OLD_ENV_VALUE)))
1326                                         goto env_ovar_ok;
1327                                 got_var++;
1328                                 last = OLD_ENV_VAR;
1329                                 break;
1330                         case OLD_ENV_VALUE:
1331                                 if (last < 0 || last == OLD_ENV_VALUE
1332                                     || (empty && (last == OLD_ENV_VAR)))
1333                                         goto env_ovar_wrong;
1334                                 got_value++;
1335                                 last = OLD_ENV_VALUE;
1336                                 break;
1337                         case ENV_USERVAR:
1338                                 /* count strings of USERVAR as one */
1339                                 if (last != ENV_USERVAR)
1340                                         got_uservar++;
1341                                 if (empty) {
1342                                         if (last == OLD_ENV_VALUE)
1343                                                 goto env_ovar_ok;
1344                                         if (last == OLD_ENV_VAR)
1345                                                 goto env_ovar_wrong;
1346                                 }
1347                                 last = ENV_USERVAR;
1348                                 break;
1349                         case ENV_ESC:
1350                                 if (!SB_EOF())
1351                                         c = SB_GET();
1352                                 /* FALL THROUGH */
1353                         default:
1354                                 empty = 0;
1355                                 continue;
1356                         }
1357                         empty = 1;
1358                 }
1359                 if (empty) {
1360                         if (last == OLD_ENV_VALUE)
1361                                 goto env_ovar_ok;
1362                         if (last == OLD_ENV_VAR)
1363                                 goto env_ovar_wrong;
1364                 }
1365                 /*
1366                  * Ok, the first thing was a USERVAR, and there
1367                  * are not two consecutive VAR or VALUE commands,
1368                  * and none of the VAR or VALUE commands are empty.
1369                  * If the client has sent us a well-formed option,
1370                  * then the number of VALUEs received should always
1371                  * be less than or equal to the number of VARs and
1372                  * USERVARs received.
1373                  *
1374                  * If we got exactly as many VALUEs as VARs and
1375                  * USERVARs, the client has the same definitions.
1376                  *
1377                  * If we got exactly as many VARs as VALUEs and
1378                  * USERVARS, the client has reversed definitions.
1379                  */
1380                 if (got_uservar + got_var == got_value) {
1381             env_ovar_ok:
1382                         env_ovar = OLD_ENV_VAR;
1383                         env_ovalue = OLD_ENV_VALUE;
1384                 } else if (got_uservar + got_value == got_var) {
1385             env_ovar_wrong:
1386                         env_ovar = OLD_ENV_VALUE;
1387                         env_ovalue = OLD_ENV_VAR;
1388                         DIAG(TD_OPTIONS, {output_data(
1389                                 "ENVIRON VALUE and VAR are reversed!\r\n");});
1390
1391                 }
1392             }
1393             SB_RESTORE();
1394 #endif
1395
1396             while (!SB_EOF()) {
1397                 c = SB_GET();
1398                 if ((c == env_ovar) || (c == ENV_USERVAR))
1399                         break;
1400             }
1401         }
1402
1403         if (SB_EOF())
1404                 return;
1405
1406         cp = varp = (char *)subpointer;
1407         valp = 0;
1408
1409         while (!SB_EOF()) {
1410                 c = SB_GET();
1411                 if (subchar == TELOPT_OLD_ENVIRON) {
1412                         if (c == env_ovar)
1413                                 c = NEW_ENV_VAR;
1414                         else if (c == env_ovalue)
1415                                 c = NEW_ENV_VALUE;
1416                 }
1417                 switch (c) {
1418
1419                 case NEW_ENV_VALUE:
1420                         *cp = '\0';
1421                         cp = valp = (char *)subpointer;
1422                         break;
1423
1424                 case NEW_ENV_VAR:
1425                 case ENV_USERVAR:
1426                         *cp = '\0';
1427                         if (envvarok(varp)) {
1428                                 if (valp)
1429                                         (void)setenv(varp, valp, 1);
1430                                 else
1431                                         unsetenv(varp);
1432                         }
1433                         cp = varp = (char *)subpointer;
1434                         valp = 0;
1435                         break;
1436
1437                 case ENV_ESC:
1438                         if (SB_EOF())
1439                                 break;
1440                         c = SB_GET();
1441                         /* FALL THROUGH */
1442                 default:
1443                         *cp++ = c;
1444                         break;
1445                 }
1446         }
1447         *cp = '\0';
1448         if (envvarok(varp)) {
1449                 if (valp)
1450                         (void)setenv(varp, valp, 1);
1451                 else
1452                         unsetenv(varp);
1453         }
1454         break;
1455     }  /* end of case TELOPT_NEW_ENVIRON */
1456 #ifdef AUTHENTICATION
1457     case TELOPT_AUTHENTICATION:
1458         if (SB_EOF())
1459                 break;
1460         switch(SB_GET()) {
1461         case TELQUAL_SEND:
1462         case TELQUAL_REPLY:
1463                 /*
1464                  * These are sent by us and cannot be sent by
1465                  * the client.
1466                  */
1467                 break;
1468         case TELQUAL_IS:
1469                 auth_is(subpointer, SB_LEN());
1470                 break;
1471         case TELQUAL_NAME:
1472                 auth_name(subpointer, SB_LEN());
1473                 break;
1474         }
1475         break;
1476 #endif
1477 #ifdef  ENCRYPTION
1478     case TELOPT_ENCRYPT:
1479         if (SB_EOF())
1480                 break;
1481         switch(SB_GET()) {
1482         case ENCRYPT_SUPPORT:
1483                 encrypt_support(subpointer, SB_LEN());
1484                 break;
1485         case ENCRYPT_IS:
1486                 encrypt_is(subpointer, SB_LEN());
1487                 break;
1488         case ENCRYPT_REPLY:
1489                 encrypt_reply(subpointer, SB_LEN());
1490                 break;
1491         case ENCRYPT_START:
1492                 encrypt_start(subpointer, SB_LEN());
1493                 break;
1494         case ENCRYPT_END:
1495                 encrypt_end();
1496                 break;
1497         case ENCRYPT_REQSTART:
1498                 encrypt_request_start(subpointer, SB_LEN());
1499                 break;
1500         case ENCRYPT_REQEND:
1501                 /*
1502                  * We can always send an REQEND so that we cannot
1503                  * get stuck encrypting.  We should only get this
1504                  * if we have been able to get in the correct mode
1505                  * anyhow.
1506                  */
1507                 encrypt_request_end();
1508                 break;
1509         case ENCRYPT_ENC_KEYID:
1510                 encrypt_enc_keyid(subpointer, SB_LEN());
1511                 break;
1512         case ENCRYPT_DEC_KEYID:
1513                 encrypt_dec_keyid(subpointer, SB_LEN());
1514                 break;
1515         default:
1516                 break;
1517         }
1518         break;
1519 #endif  /* ENCRYPTION */
1520
1521     default:
1522         break;
1523     }  /* end of switch */
1524
1525 }  /* end of suboption */
1526
1527 #ifdef LINEMODE
1528 void
1529 doclientstat(void)
1530 {
1531         clientstat(TELOPT_LINEMODE, WILL, 0);
1532 }
1533 #endif /* LINEMODE */
1534
1535 void
1536 send_status(void)
1537 {
1538 #define ADD(c) \
1539         do { \
1540                 if (ep > ncp) \
1541                         *ncp++ = c; \
1542                 else \
1543                         goto trunc; \
1544         } while (0)
1545 #define ADD_DATA(c) \
1546         do { \
1547                 ADD(c); if (c == SE || c == IAC) ADD(c); \
1548         } while (0)
1549
1550         unsigned char statusbuf[256];
1551         unsigned char *ep;
1552         unsigned char *ncp;
1553         unsigned char i;
1554
1555         ncp = statusbuf;
1556         ep = statusbuf + sizeof(statusbuf);
1557
1558         netflush();     /* get rid of anything waiting to go out */
1559
1560         ADD(IAC);
1561         ADD(SB);
1562         ADD(TELOPT_STATUS);
1563         ADD(TELQUAL_IS);
1564
1565         /*
1566          * We check the want_state rather than the current state,
1567          * because if we received a DO/WILL for an option that we
1568          * don't support, and the other side didn't send a DONT/WONT
1569          * in response to our WONT/DONT, then the "state" will be
1570          * WILL/DO, and the "want_state" will be WONT/DONT.  We
1571          * need to go by the latter.
1572          */
1573         for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1574                 if (my_want_state_is_will(i)) {
1575                         ADD(WILL);
1576                         ADD_DATA(i);
1577                 }
1578                 if (his_want_state_is_will(i)) {
1579                         ADD(DO);
1580                         ADD_DATA(i);
1581                 }
1582         }
1583
1584         if (his_want_state_is_will(TELOPT_LFLOW)) {
1585                 ADD(SB);
1586                 ADD(TELOPT_LFLOW);
1587                 if (flowmode) {
1588                         ADD(LFLOW_ON);
1589                 } else {
1590                         ADD(LFLOW_OFF);
1591                 }
1592                 ADD(SE);
1593
1594                 if (restartany >= 0) {
1595                         ADD(SB);
1596                         ADD(TELOPT_LFLOW);
1597                         if (restartany) {
1598                                 ADD(LFLOW_RESTART_ANY);
1599                         } else {
1600                                 ADD(LFLOW_RESTART_XON);
1601                         }
1602                         ADD(SE);
1603                 }
1604         }
1605
1606 #ifdef  LINEMODE
1607         if (his_want_state_is_will(TELOPT_LINEMODE)) {
1608                 unsigned char *cp, *cpe;
1609                 int len;
1610
1611                 ADD(SB);
1612                 ADD(TELOPT_LINEMODE);
1613                 ADD(LM_MODE);
1614                 ADD_DATA(editmode);
1615                 ADD(SE);
1616
1617                 ADD(SB);
1618                 ADD(TELOPT_LINEMODE);
1619                 ADD(LM_SLC);
1620                 start_slc(0);
1621                 send_slc();
1622                 len = end_slc(&cp);
1623                 for (cpe = cp + len; cp < cpe; cp++)
1624                         ADD_DATA(*cp);
1625                 ADD(SE);
1626         }
1627 #endif  /* LINEMODE */
1628
1629         ADD(IAC);
1630         ADD(SE);
1631
1632         writenet(statusbuf, ncp - statusbuf);
1633         netflush();     /* Send it on its way */
1634
1635         DIAG(TD_OPTIONS,
1636                 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1637         return;
1638
1639 trunc:
1640         /* XXX bark? */
1641         return;
1642 #undef ADD
1643 #undef ADD_DATA
1644 }
1645
1646 int
1647 output_data(const char *format, ...)
1648 {
1649         va_list args;
1650         size_t remaining, ret;
1651
1652         va_start(args, format);
1653         remaining = BUFSIZ - (nfrontp - netobuf);
1654         /* try a netflush() if the room is too low */
1655         if (strlen(format) > remaining || BUFSIZ / 4 > remaining) {
1656                 netflush();
1657                 remaining = BUFSIZ - (nfrontp - netobuf);
1658         }
1659         ret = vsnprintf(nfrontp, remaining, format, args);
1660         nfrontp += ((ret < remaining - 1) ? ret : remaining - 1);
1661         va_end(args);
1662         return ret;
1663 }
1664
1665 int
1666 output_datalen(const char *buf, size_t l)
1667 {
1668         size_t remaining;
1669
1670         remaining = BUFSIZ - (nfrontp - netobuf);
1671         if (remaining < l) {
1672                 netflush();
1673                 remaining = BUFSIZ - (nfrontp - netobuf);
1674         }
1675         if (remaining < l)
1676                 return -1;
1677         memmove(nfrontp, buf, l);
1678         nfrontp += l;
1679         return (int)l;
1680 }