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