libexec/telnetd/state.c

   1 /*
   2  * Copyright (c) 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)state.c  8.5 (Berkeley) 5/30/95
  34  * $FreeBSD: src/crypto/telnet/telnetd/state.c,v 1.4.2.3 2002/04/13 10:59:08 markm Exp $
  35  * $DragonFly: src/crypto/telnet/telnetd/state.c,v 1.3 2006/01/17 23:50:35 dillon Exp $
  36  */
  37
  38 #include <stdarg.h>
  39 #include "telnetd.h"
  40 #ifdef  AUTHENTICATION
  41 #include <libtelnet/auth.h>
  42 #endif
  43 #ifdef  ENCRYPTION
  44 #include <libtelnet/encrypt.h>
  45 #endif
  46
  47 static int envvarok(char *);
  48
  49 unsigned char   doopt[] = { IAC, DO, '%', 'c', 0 };
  50 unsigned char   dont[] = { IAC, DONT, '%', 'c', 0 };
  51 unsigned char   will[] = { IAC, WILL, '%', 'c', 0 };
  52 unsigned char   wont[] = { IAC, WONT, '%', 'c', 0 };
  53 int     not42 = 1;
  54
  55 /*
  56  * Buffer for sub-options, and macros
  57  * for suboptions buffer manipulations
  58  */
  59 unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;
  60
  61 #define SB_CLEAR()      subpointer = subbuffer
  62 #define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
  63 #define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
  64                                 *subpointer++ = (c); \
  65                         }
  66 #define SB_GET()        ((*subpointer++)&0xff)
  67 #define SB_EOF()        (subpointer >= subend)
  68 #define SB_LEN()        (subend - subpointer)
  69
  70 #ifdef  ENV_HACK
  71 unsigned char *subsave;
  72 #define SB_SAVE()       subsave = subpointer;
  73 #define SB_RESTORE()    subpointer = subsave;
  74 #endif
  75
  76
  77 /*
  78  * State for recv fsm
  79  */
  80 #define TS_DATA         0       /* base state */
  81 #define TS_IAC          1       /* look for double IAC's */
  82 #define TS_CR           2       /* CR-LF ->'s CR */
  83 #define TS_SB           3       /* throw away begin's... */
  84 #define TS_SE           4       /* ...end's (suboption negotiation) */
  85 #define TS_WILL         5       /* will option negotiation */
  86 #define TS_WONT         6       /* wont " */
  87 #define TS_DO           7       /* do " */
  88 #define TS_DONT         8       /* dont " */
  89
  90 static void doclientstat(void);
  91
  92 void
  93 telrcv(void)
  94 {
  95         int c;
  96         static int state = TS_DATA;
  97
  98         while (ncc > 0) {
  99                 if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
 100                         break;
 101                 c = *netip++ & 0377, ncc--;
 102 #ifdef  ENCRYPTION
 103                 if (decrypt_input)
 104                         c = (*decrypt_input)(c);
 105 #endif  /* ENCRYPTION */
 106                 switch (state) {
 107
 108                 case TS_CR:
 109                         state = TS_DATA;
 110                         /* Strip off \n or \0 after a \r */
 111                         if ((c == 0) || (c == '\n')) {
 112                                 break;
 113                         }
 114                         /* FALL THROUGH */
 115
 116                 case TS_DATA:
 117                         if (c == IAC) {
 118                                 state = TS_IAC;
 119                                 break;
 120                         }
 121                         /*
 122                          * We now map \r\n ==> \r for pragmatic reasons.
 123                          * Many client implementations send \r\n when
 124                          * the user hits the CarriageReturn key.
 125                          *
 126                          * We USED to map \r\n ==> \n, since \r\n says
 127                          * that we want to be in column 1 of the next
 128                          * printable line, and \n is the standard
 129                          * unix way of saying that (\r is only good
 130                          * if CRMOD is set, which it normally is).
 131                          */
 132                         if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 133                                 int nc = *netip;
 134 #ifdef  ENCRYPTION
 135                                 if (decrypt_input)
 136                                         nc = (*decrypt_input)(nc & 0xff);
 137 #endif  /* ENCRYPTION */
 138 #ifdef  LINEMODE
 139                                 /*
 140                                  * If we are operating in linemode,
 141                                  * convert to local end-of-line.
 142                                  */
 143                                 if (linemode && (ncc > 0) && (('\n' == nc) ||
 144                                          ((0 == nc) && tty_iscrnl())) ) {
 145                                         netip++; ncc--;
 146                                         c = '\n';
 147                                 } else
 148 #endif
 149                                 {
 150 #ifdef  ENCRYPTION
 151                                         if (decrypt_input)
 152                                                 (void)(*decrypt_input)(-1);
 153 #endif  /* ENCRYPTION */
 154                                         state = TS_CR;
 155                                 }
 156                         }
 157                         *pfrontp++ = c;
 158                         break;
 159
 160                 case TS_IAC:
 161 gotiac:                 switch (c) {
 162
 163                         /*
 164                          * Send the process on the pty side an
 165                          * interrupt.  Do this with a NULL or
 166                          * interrupt char; depending on the tty mode.
 167                          */
 168                         case IP:
 169                                 DIAG(TD_OPTIONS,
 170                                         printoption("td: recv IAC", c));
 171                                 interrupt();
 172                                 break;
 173
 174                         case BREAK:
 175                                 DIAG(TD_OPTIONS,
 176                                         printoption("td: recv IAC", c));
 177                                 sendbrk();
 178                                 break;
 179
 180                         /*
 181                          * Are You There?
 182                          */
 183                         case AYT:
 184                                 DIAG(TD_OPTIONS,
 185                                         printoption("td: recv IAC", c));
 186                                 recv_ayt();
 187                                 break;
 188
 189                         /*
 190                          * Abort Output
 191                          */
 192                         case AO:
 193                             {
 194                                 DIAG(TD_OPTIONS,
 195                                         printoption("td: recv IAC", c));
 196                                 ptyflush();     /* half-hearted */
 197                                 init_termbuf();
 198
 199                                 if (slctab[SLC_AO].sptr &&
 200                                     *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
 201                                     *pfrontp++ =
 202                                         (unsigned char)*slctab[SLC_AO].sptr;
 203                                 }
 204
 205                                 netclear();     /* clear buffer back */
 206                                 output_data("%c%c", IAC, DM);
 207                                 neturg = nfrontp-1; /* off by one XXX */
 208                                 DIAG(TD_OPTIONS,
 209                                         printoption("td: send IAC", DM));
 210                                 break;
 211                             }
 212
 213                         /*
 214                          * Erase Character and
 215                          * Erase Line
 216                          */
 217                         case EC:
 218                         case EL:
 219                             {
 220                                 cc_t ch;
 221
 222                                 DIAG(TD_OPTIONS,
 223                                         printoption("td: recv IAC", c));
 224                                 ptyflush();     /* half-hearted */
 225                                 init_termbuf();
 226                                 if (c == EC)
 227                                         ch = *slctab[SLC_EC].sptr;
 228                                 else
 229                                         ch = *slctab[SLC_EL].sptr;
 230                                 if (ch != (cc_t)(_POSIX_VDISABLE))
 231                                         *pfrontp++ = (unsigned char)ch;
 232                                 break;
 233                             }
 234
 235                         /*
 236                          * Check for urgent data...
 237                          */
 238                         case DM:
 239                                 DIAG(TD_OPTIONS,
 240                                         printoption("td: recv IAC", c));
 241                                 SYNCHing = stilloob(net);
 242                                 settimer(gotDM);
 243                                 break;
 244
 245
 246                         /*
 247                          * Begin option subnegotiation...
 248                          */
 249                         case SB:
 250                                 state = TS_SB;
 251                                 SB_CLEAR();
 252                                 continue;
 253
 254                         case WILL:
 255                                 state = TS_WILL;
 256                                 continue;
 257
 258                         case WONT:
 259                                 state = TS_WONT;
 260                                 continue;
 261
 262                         case DO:
 263                                 state = TS_DO;
 264                                 continue;
 265
 266                         case DONT:
 267                                 state = TS_DONT;
 268                                 continue;
 269                         case EOR:
 270                                 if (his_state_is_will(TELOPT_EOR))
 271                                         doeof();
 272                                 break;
 273
 274                         /*
 275                          * Handle RFC 10xx Telnet linemode option additions
 276                          * to command stream (EOF, SUSP, ABORT).
 277                          */
 278                         case xEOF:
 279                                 doeof();
 280                                 break;
 281
 282                         case SUSP:
 283                                 sendsusp();
 284                                 break;
 285
 286                         case ABORT:
 287                                 sendbrk();
 288                                 break;
 289
 290                         case IAC:
 291                                 *pfrontp++ = c;
 292                                 break;
 293                         }
 294                         state = TS_DATA;
 295                         break;
 296
 297                 case TS_SB:
 298                         if (c == IAC) {
 299                                 state = TS_SE;
 300                         } else {
 301                                 SB_ACCUM(c);
 302                         }
 303                         break;
 304
 305                 case TS_SE:
 306                         if (c != SE) {
 307                                 if (c != IAC) {
 308                                         /*
 309                                          * bad form of suboption negotiation.
 310                                          * handle it in such a way as to avoid
 311                                          * damage to local state.  Parse
 312                                          * suboption buffer found so far,
 313                                          * then treat remaining stream as
 314                                          * another command sequence.
 315                                          */
 316
 317                                         /* for DIAGNOSTICS */
 318                                         SB_ACCUM(IAC);
 319                                         SB_ACCUM(c);
 320                                         subpointer -= 2;
 321
 322                                         SB_TERM();
 323                                         suboption();
 324                                         state = TS_IAC;
 325                                         goto gotiac;
 326                                 }
 327                                 SB_ACCUM(c);
 328                                 state = TS_SB;
 329                         } else {
 330                                 /* for DIAGNOSTICS */
 331                                 SB_ACCUM(IAC);
 332                                 SB_ACCUM(SE);
 333                                 subpointer -= 2;
 334
 335                                 SB_TERM();
 336                                 suboption();    /* handle sub-option */
 337                                 state = TS_DATA;
 338                         }
 339                         break;
 340
 341                 case TS_WILL:
 342                         willoption(c);
 343                         state = TS_DATA;
 344                         continue;
 345
 346                 case TS_WONT:
 347                         wontoption(c);
 348                         state = TS_DATA;
 349                         continue;
 350
 351                 case TS_DO:
 352                         dooption(c);
 353                         state = TS_DATA;
 354                         continue;
 355
 356                 case TS_DONT:
 357                         dontoption(c);
 358                         state = TS_DATA;
 359                         continue;
 360
 361                 default:
 362                         syslog(LOG_ERR, "panic state=%d", state);
 363                         printf("telnetd: panic state=%d\n", state);
 364                         exit(1);
 365                 }
 366         }
 367 }  /* end of telrcv */
 368
 369 /*
 370  * The will/wont/do/dont state machines are based on Dave Borman's
 371  * Telnet option processing state machine.
 372  *
 373  * These correspond to the following states:
 374  *      my_state = the last negotiated state
 375  *      want_state = what I want the state to go to
 376  *      want_resp = how many requests I have sent
 377  * All state defaults are negative, and resp defaults to 0.
 378  *
 379  * When initiating a request to change state to new_state:
 380  *
 381  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 382  *      do nothing;
 383  * } else {
 384  *      want_state = new_state;
 385  *      send new_state;
 386  *      want_resp++;
 387  * }
 388  *
 389  * When receiving new_state:
 390  *
 391  * if (want_resp) {
 392  *      want_resp--;
 393  *      if (want_resp && (new_state == my_state))
 394  *              want_resp--;
 395  * }
 396  * if ((want_resp == 0) && (new_state != want_state)) {
 397  *      if (ok_to_switch_to new_state)
 398  *              want_state = new_state;
 399  *      else
 400  *              want_resp++;
 401  *      send want_state;
 402  * }
 403  * my_state = new_state;
 404  *
 405  * Note that new_state is implied in these functions by the function itself.
 406  * will and do imply positive new_state, wont and dont imply negative.
 407  *
 408  * Finally, there is one catch.  If we send a negative response to a
 409  * positive request, my_state will be the positive while want_state will
 410  * remain negative.  my_state will revert to negative when the negative
 411  * acknowlegment arrives from the peer.  Thus, my_state generally tells
 412  * us not only the last negotiated state, but also tells us what the peer
 413  * wants to be doing as well.  It is important to understand this difference
 414  * as we may wish to be processing data streams based on our desired state
 415  * (want_state) or based on what the peer thinks the state is (my_state).
 416  *
 417  * This all works fine because if the peer sends a positive request, the data
 418  * that we receive prior to negative acknowlegment will probably be affected
 419  * by the positive state, and we can process it as such (if we can; if we
 420  * can't then it really doesn't matter).  If it is that important, then the
 421  * peer probably should be buffering until this option state negotiation
 422  * is complete.
 423  *
 424  */
 425 void
 426 send_do(int option, int init)
 427 {
 428         if (init) {
 429                 if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
 430                     his_want_state_is_will(option))
 431                         return;
 432                 /*
 433                  * Special case for TELOPT_TM:  We send a DO, but pretend
 434                  * that we sent a DONT, so that we can send more DOs if
 435                  * we want to.
 436                  */
 437                 if (option == TELOPT_TM)
 438                         set_his_want_state_wont(option);
 439                 else
 440                         set_his_want_state_will(option);
 441                 do_dont_resp[option]++;
 442         }
 443         output_data((const char *)doopt, option);
 444
 445         DIAG(TD_OPTIONS, printoption("td: send do", option));
 446 }
 447
 448 void
 449 willoption(int option)
 450 {
 451         int changeok = 0;
 452         void (*func)(void) = 0;
 453
 454         /*
 455          * process input from peer.
 456          */
 457
 458         DIAG(TD_OPTIONS, printoption("td: recv will", option));
 459
 460         if (do_dont_resp[option]) {
 461                 do_dont_resp[option]--;
 462                 if (do_dont_resp[option] && his_state_is_will(option))
 463                         do_dont_resp[option]--;
 464         }
 465         if (do_dont_resp[option] == 0) {
 466             if (his_want_state_is_wont(option)) {
 467                 switch (option) {
 468
 469                 case TELOPT_BINARY:
 470                         init_termbuf();
 471                         tty_binaryin(1);
 472                         set_termbuf();
 473                         changeok++;
 474                         break;
 475
 476                 case TELOPT_ECHO:
 477                         /*
 478                          * See comments below for more info.
 479                          */
 480                         not42 = 0;      /* looks like a 4.2 system */
 481                         break;
 482
 483                 case TELOPT_TM:
 484 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 485                         /*
 486                          * This telnetd implementation does not really
 487                          * support timing marks, it just uses them to
 488                          * support the kludge linemode stuff.  If we
 489                          * receive a will or wont TM in response to our
 490                          * do TM request that may have been sent to
 491                          * determine kludge linemode support, process
 492                          * it, otherwise TM should get a negative
 493                          * response back.
 494                          */
 495                         /*
 496                          * Handle the linemode kludge stuff.
 497                          * If we are not currently supporting any
 498                          * linemode at all, then we assume that this
 499                          * is the client telling us to use kludge
 500                          * linemode in response to our query.  Set the
 501                          * linemode type that is to be supported, note
 502                          * that the client wishes to use linemode, and
 503                          * eat the will TM as though it never arrived.
 504                          */
 505                         if (lmodetype < KLUDGE_LINEMODE) {
 506                                 lmodetype = KLUDGE_LINEMODE;
 507                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 508                                 send_wont(TELOPT_SGA, 1);
 509                         } else if (lmodetype == NO_AUTOKLUDGE) {
 510                                 lmodetype = KLUDGE_OK;
 511                         }
 512 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 513                         /*
 514                          * We never respond to a WILL TM, and
 515                          * we leave the state WONT.
 516                          */
 517                         return;
 518
 519                 case TELOPT_LFLOW:
 520                         /*
 521                          * If we are going to support flow control
 522                          * option, then don't worry peer that we can't
 523                          * change the flow control characters.
 524                          */
 525                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 526                         slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 527                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 528                         slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 529                 case TELOPT_TTYPE:
 530                 case TELOPT_SGA:
 531                 case TELOPT_NAWS:
 532                 case TELOPT_TSPEED:
 533                 case TELOPT_XDISPLOC:
 534                 case TELOPT_NEW_ENVIRON:
 535                 case TELOPT_OLD_ENVIRON:
 536                         changeok++;
 537                         break;
 538
 539 #ifdef  LINEMODE
 540                 case TELOPT_LINEMODE:
 541 # ifdef KLUDGELINEMODE
 542                         /*
 543                          * Note client's desire to use linemode.
 544                          */
 545                         lmodetype = REAL_LINEMODE;
 546 # endif /* KLUDGELINEMODE */
 547                         func = doclientstat;
 548                         changeok++;
 549                         break;
 550 #endif  /* LINEMODE */
 551
 552 #ifdef  AUTHENTICATION
 553                 case TELOPT_AUTHENTICATION:
 554                         func = auth_request;
 555                         changeok++;
 556                         break;
 557 #endif
 558
 559 #ifdef  ENCRYPTION
 560                 case TELOPT_ENCRYPT:
 561                         func = encrypt_send_support;
 562                         changeok++;
 563                         break;
 564 #endif  /* ENCRYPTION */
 565
 566                 default:
 567                         break;
 568                 }
 569                 if (changeok) {
 570                         set_his_want_state_will(option);
 571                         send_do(option, 0);
 572                 } else {
 573                         do_dont_resp[option]++;
 574                         send_dont(option, 0);
 575                 }
 576             } else {
 577                 /*
 578                  * Option processing that should happen when
 579                  * we receive conformation of a change in
 580                  * state that we had requested.
 581                  */
 582                 switch (option) {
 583                 case TELOPT_ECHO:
 584                         not42 = 0;      /* looks like a 4.2 system */
 585                         /*
 586                          * Egads, he responded "WILL ECHO".  Turn
 587                          * it off right now!
 588                          */
 589                         send_dont(option, 1);
 590                         /*
 591                          * "WILL ECHO".  Kludge upon kludge!
 592                          * A 4.2 client is now echoing user input at
 593                          * the tty.  This is probably undesireable and
 594                          * it should be stopped.  The client will
 595                          * respond WONT TM to the DO TM that we send to
 596                          * check for kludge linemode.  When the WONT TM
 597                          * arrives, linemode will be turned off and a
 598                          * change propogated to the pty.  This change
 599                          * will cause us to process the new pty state
 600                          * in localstat(), which will notice that
 601                          * linemode is off and send a WILL ECHO
 602                          * so that we are properly in character mode and
 603                          * all is well.
 604                          */
 605                         break;
 606 #ifdef  LINEMODE
 607                 case TELOPT_LINEMODE:
 608 # ifdef KLUDGELINEMODE
 609                         /*
 610                          * Note client's desire to use linemode.
 611                          */
 612                         lmodetype = REAL_LINEMODE;
 613 # endif /* KLUDGELINEMODE */
 614                         func = doclientstat;
 615                         break;
 616 #endif  /* LINEMODE */
 617
 618 #ifdef  AUTHENTICATION
 619                 case TELOPT_AUTHENTICATION:
 620                         func = auth_request;
 621                         break;
 622 #endif
 623
 624 #ifdef  ENCRYPTION
 625                 case TELOPT_ENCRYPT:
 626                         func = encrypt_send_support;
 627                         break;
 628 #endif  /* ENCRYPTION */
 629                 case TELOPT_LFLOW:
 630                         func = flowstat;
 631                         break;
 632                 }
 633             }
 634         }
 635         set_his_state_will(option);
 636         if (func)
 637                 (*func)();
 638 }  /* end of willoption */
 639
 640 void
 641 send_dont(int option, int init)
 642 {
 643         if (init) {
 644                 if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 645                     his_want_state_is_wont(option))
 646                         return;
 647                 set_his_want_state_wont(option);
 648                 do_dont_resp[option]++;
 649         }
 650         output_data((const char *)dont, option);
 651
 652         DIAG(TD_OPTIONS, printoption("td: send dont", option));
 653 }
 654
 655 void
 656 wontoption(int option)
 657 {
 658         /*
 659          * Process client input.
 660          */
 661
 662         DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 663
 664         if (do_dont_resp[option]) {
 665                 do_dont_resp[option]--;
 666                 if (do_dont_resp[option] && his_state_is_wont(option))
 667                         do_dont_resp[option]--;
 668         }
 669         if (do_dont_resp[option] == 0) {
 670             if (his_want_state_is_will(option)) {
 671                 /* it is always ok to change to negative state */
 672                 switch (option) {
 673                 case TELOPT_ECHO:
 674                         not42 = 1; /* doesn't seem to be a 4.2 system */
 675                         break;
 676
 677                 case TELOPT_BINARY:
 678                         init_termbuf();
 679                         tty_binaryin(0);
 680                         set_termbuf();
 681                         break;
 682
 683 #ifdef  LINEMODE
 684                 case TELOPT_LINEMODE:
 685 # ifdef KLUDGELINEMODE
 686                         /*
 687                          * If real linemode is supported, then client is
 688                          * asking to turn linemode off.
 689                          */
 690                         if (lmodetype != REAL_LINEMODE)
 691                                 break;
 692                         lmodetype = KLUDGE_LINEMODE;
 693 # endif /* KLUDGELINEMODE */
 694                         clientstat(TELOPT_LINEMODE, WONT, 0);
 695                         break;
 696 #endif  /* LINEMODE */
 697
 698                 case TELOPT_TM:
 699                         /*
 700                          * If we get a WONT TM, and had sent a DO TM,
 701                          * don't respond with a DONT TM, just leave it
 702                          * as is.  Short circut the state machine to
 703                          * achive this.
 704                          */
 705                         set_his_want_state_wont(TELOPT_TM);
 706                         return;
 707
 708                 case TELOPT_LFLOW:
 709                         /*
 710                          * If we are not going to support flow control
 711                          * option, then let peer know that we can't
 712                          * change the flow control characters.
 713                          */
 714                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 715                         slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 716                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 717                         slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 718                         break;
 719
 720 #ifdef  AUTHENTICATION
 721                 case TELOPT_AUTHENTICATION:
 722                         auth_finished(0, AUTH_REJECT);
 723                         break;
 724 #endif
 725
 726                 /*
 727                  * For options that we might spin waiting for
 728                  * sub-negotiation, if the client turns off the
 729                  * option rather than responding to the request,
 730                  * we have to treat it here as if we got a response
 731                  * to the sub-negotiation, (by updating the timers)
 732                  * so that we'll break out of the loop.
 733                  */
 734                 case TELOPT_TTYPE:
 735                         settimer(ttypesubopt);
 736                         break;
 737
 738                 case TELOPT_TSPEED:
 739                         settimer(tspeedsubopt);
 740                         break;
 741
 742                 case TELOPT_XDISPLOC:
 743                         settimer(xdisplocsubopt);
 744                         break;
 745
 746                 case TELOPT_OLD_ENVIRON:
 747                         settimer(oenvironsubopt);
 748                         break;
 749
 750                 case TELOPT_NEW_ENVIRON:
 751                         settimer(environsubopt);
 752                         break;
 753
 754                 default:
 755                         break;
 756                 }
 757                 set_his_want_state_wont(option);
 758                 if (his_state_is_will(option))
 759                         send_dont(option, 0);
 760             } else {
 761                 switch (option) {
 762                 case TELOPT_TM:
 763 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 764                         if (lmodetype < NO_AUTOKLUDGE) {
 765                                 lmodetype = NO_LINEMODE;
 766                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 767                                 send_will(TELOPT_SGA, 1);
 768                                 send_will(TELOPT_ECHO, 1);
 769                         }
 770 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 771                         break;
 772
 773 #ifdef AUTHENTICATION
 774                 case TELOPT_AUTHENTICATION:
 775                         auth_finished(0, AUTH_REJECT);
 776                         break;
 777 #endif
 778                 default:
 779                         break;
 780                 }
 781             }
 782         }
 783         set_his_state_wont(option);
 784
 785 }  /* end of wontoption */
 786
 787 void
 788 send_will(int option, int init)
 789 {
 790         if (init) {
 791                 if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 792                     my_want_state_is_will(option))
 793                         return;
 794                 set_my_want_state_will(option);
 795                 will_wont_resp[option]++;
 796         }
 797         output_data((const char *)will, option);
 798
 799         DIAG(TD_OPTIONS, printoption("td: send will", option));
 800 }
 801
 802 #if     !defined(LINEMODE) || !defined(KLUDGELINEMODE)
 803 /*
 804  * When we get a DONT SGA, we will try once to turn it
 805  * back on.  If the other side responds DONT SGA, we
 806  * leave it at that.  This is so that when we talk to
 807  * clients that understand KLUDGELINEMODE but not LINEMODE,
 808  * we'll keep them in char-at-a-time mode.
 809  */
 810 int turn_on_sga = 0;
 811 #endif
 812
 813 void
 814 dooption(int option)
 815 {
 816         int changeok = 0;
 817
 818         /*
 819          * Process client input.
 820          */
 821
 822         DIAG(TD_OPTIONS, printoption("td: recv do", option));
 823
 824         if (will_wont_resp[option]) {
 825                 will_wont_resp[option]--;
 826                 if (will_wont_resp[option] && my_state_is_will(option))
 827                         will_wont_resp[option]--;
 828         }
 829         if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 830                 switch (option) {
 831                 case TELOPT_ECHO:
 832 #ifdef  LINEMODE
 833 # ifdef KLUDGELINEMODE
 834                         if (lmodetype == NO_LINEMODE)
 835 # else
 836                         if (his_state_is_wont(TELOPT_LINEMODE))
 837 # endif
 838 #endif
 839                         {
 840                                 init_termbuf();
 841                                 tty_setecho(1);
 842                                 set_termbuf();
 843                         }
 844                         changeok++;
 845                         break;
 846
 847                 case TELOPT_BINARY:
 848                         init_termbuf();
 849                         tty_binaryout(1);
 850                         set_termbuf();
 851                         changeok++;
 852                         break;
 853
 854                 case TELOPT_SGA:
 855 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 856                         /*
 857                          * If kludge linemode is in use, then we must
 858                          * process an incoming do SGA for linemode
 859                          * purposes.
 860                          */
 861                         if (lmodetype == KLUDGE_LINEMODE) {
 862                                 /*
 863                                  * Receipt of "do SGA" in kludge
 864                                  * linemode is the peer asking us to
 865                                  * turn off linemode.  Make note of
 866                                  * the request.
 867                                  */
 868                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 869                                 /*
 870                                  * If linemode did not get turned off
 871                                  * then don't tell peer that we did.
 872                                  * Breaking here forces a wont SGA to
 873                                  * be returned.
 874                                  */
 875                                 if (linemode)
 876                                         break;
 877                         }
 878 #else
 879                         turn_on_sga = 0;
 880 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 881                         changeok++;
 882                         break;
 883
 884                 case TELOPT_STATUS:
 885                         changeok++;
 886                         break;
 887
 888                 case TELOPT_TM:
 889                         /*
 890                          * Special case for TM.  We send a WILL, but
 891                          * pretend we sent a WONT.
 892                          */
 893                         send_will(option, 0);
 894                         set_my_want_state_wont(option);
 895                         set_my_state_wont(option);
 896                         return;
 897
 898                 case TELOPT_LOGOUT:
 899                         /*
 900                          * When we get a LOGOUT option, respond
 901                          * with a WILL LOGOUT, make sure that
 902                          * it gets written out to the network,
 903                          * and then just go away...
 904                          */
 905                         set_my_want_state_will(TELOPT_LOGOUT);
 906                         send_will(TELOPT_LOGOUT, 0);
 907                         set_my_state_will(TELOPT_LOGOUT);
 908                         (void)netflush();
 909                         cleanup(0);
 910                         /* NOT REACHED */
 911                         break;
 912
 913 #ifdef  ENCRYPTION
 914                 case TELOPT_ENCRYPT:
 915                         changeok++;
 916                         break;
 917 #endif  /* ENCRYPTION */
 918                 case TELOPT_LINEMODE:
 919                 case TELOPT_TTYPE:
 920                 case TELOPT_NAWS:
 921                 case TELOPT_TSPEED:
 922                 case TELOPT_LFLOW:
 923                 case TELOPT_XDISPLOC:
 924 #ifdef  TELOPT_ENVIRON
 925                 case TELOPT_NEW_ENVIRON:
 926 #endif
 927                 case TELOPT_OLD_ENVIRON:
 928                 default:
 929                         break;
 930                 }
 931                 if (changeok) {
 932                         set_my_want_state_will(option);
 933                         send_will(option, 0);
 934                 } else {
 935                         will_wont_resp[option]++;
 936                         send_wont(option, 0);
 937                 }
 938         }
 939         set_my_state_will(option);
 940
 941 }  /* end of dooption */
 942
 943 void
 944 send_wont(int option, int init)
 945 {
 946         if (init) {
 947                 if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 948                     my_want_state_is_wont(option))
 949                         return;
 950                 set_my_want_state_wont(option);
 951                 will_wont_resp[option]++;
 952         }
 953         output_data((const char *)wont, option);
 954
 955         DIAG(TD_OPTIONS, printoption("td: send wont", option));
 956 }
 957
 958 void
 959 dontoption(int option)
 960 {
 961         /*
 962          * Process client input.
 963          */
 964
 965
 966         DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 967
 968         if (will_wont_resp[option]) {
 969                 will_wont_resp[option]--;
 970                 if (will_wont_resp[option] && my_state_is_wont(option))
 971                         will_wont_resp[option]--;
 972         }
 973         if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 974                 switch (option) {
 975                 case TELOPT_BINARY:
 976                         init_termbuf();
 977                         tty_binaryout(0);
 978                         set_termbuf();
 979                         break;
 980
 981                 case TELOPT_ECHO:       /* we should stop echoing */
 982 #ifdef  LINEMODE
 983 # ifdef KLUDGELINEMODE
 984                         if ((lmodetype != REAL_LINEMODE) &&
 985                             (lmodetype != KLUDGE_LINEMODE))
 986 # else
 987                         if (his_state_is_wont(TELOPT_LINEMODE))
 988 # endif
 989 #endif
 990                         {
 991                                 init_termbuf();
 992                                 tty_setecho(0);
 993                                 set_termbuf();
 994                         }
 995                         break;
 996
 997                 case TELOPT_SGA:
 998 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 999                         /*
1000                          * If kludge linemode is in use, then we
1001                          * must process an incoming do SGA for
1002                          * linemode purposes.
1003                          */
1004                         if ((lmodetype == KLUDGE_LINEMODE) ||
1005                             (lmodetype == KLUDGE_OK)) {
1006                                 /*
1007                                  * The client is asking us to turn
1008                                  * linemode on.
1009                                  */
1010                                 lmodetype = KLUDGE_LINEMODE;
1011                                 clientstat(TELOPT_LINEMODE, WILL, 0);
1012                                 /*
1013                                  * If we did not turn line mode on,
1014                                  * then what do we say?  Will SGA?
1015                                  * This violates design of telnet.
1016                                  * Gross.  Very Gross.
1017                                  */
1018                         }
1019                         break;
1020 #else
1021                         set_my_want_state_wont(option);
1022                         if (my_state_is_will(option))
1023                                 send_wont(option, 0);
1024                         set_my_state_wont(option);
1025                         if (turn_on_sga ^= 1)
1026                                 send_will(option, 1);
1027                         return;
1028 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
1029
1030                 default:
1031                         break;
1032                 }
1033
1034                 set_my_want_state_wont(option);
1035                 if (my_state_is_will(option))
1036                         send_wont(option, 0);
1037         }
1038         set_my_state_wont(option);
1039
1040 }  /* end of dontoption */
1041
1042 #ifdef  ENV_HACK
1043 int env_ovar = -1;
1044 int env_ovalue = -1;
1045 #else   /* ENV_HACK */
1046 # define env_ovar OLD_ENV_VAR
1047 # define env_ovalue OLD_ENV_VALUE
1048 #endif  /* ENV_HACK */
1049
1050 /* envvarok(char*) */
1051 /* check that variable is safe to pass to login or shell */
1052 static int
1053 envvarok(char *varp)
1054 {
1055
1056         if (strcmp(varp, "TERMCAP") &&  /* to prevent a security hole */
1057             strcmp(varp, "TERMINFO") && /* with tgetent */
1058             strcmp(varp, "TERMPATH") &&
1059             strcmp(varp, "HOME") &&     /* to prevent the tegetent bug  */
1060             strncmp(varp, "LD_", strlen("LD_")) &&      /* most systems */
1061             strncmp(varp, "_RLD_", strlen("_RLD_")) &&  /* IRIX */
1062             strcmp(varp, "LIBPATH") &&                  /* AIX */
1063             strcmp(varp, "ENV") &&
1064             strcmp(varp, "BASH_ENV") &&
1065             strcmp(varp, "IFS") &&
1066             strncmp(varp, "KRB5", strlen("KRB5")) &&    /* Krb5 */
1067             /*
1068              * The above case is a catch-all for now.  Here are some of
1069              * the specific ones we must avoid passing, at least until
1070              * we can prove it can be done safely.  Keep this list
1071              * around un case someone wants to remove the catch-all.
1072              */
1073             strcmp(varp, "KRB5_CONFIG") &&              /* Krb5 */
1074             strcmp(varp, "KRB5CCNAME") &&               /* Krb5 */
1075             strcmp(varp, "KRB5_KTNAME") &&              /* Krb5 */
1076             strcmp(varp, "KRBTKFILE") &&                /* Krb4 */
1077             strcmp(varp, "KRB_CONF") &&                 /* CNS 4 */
1078             strcmp(varp, "KRB_REALMS") &&               /* CNS 4 */
1079             strcmp(varp, "RESOLV_HOST_CONF"))           /* Linux */
1080                 return (1);
1081         else {
1082                 syslog(LOG_INFO, "Rejected the attempt to modify the "
1083                     "environment variable \"%s\"", varp);
1084                 return (0);
1085         }
1086 }
1087
1088 /*
1089  * suboption()
1090  *
1091  *      Look at the sub-option buffer, and try to be helpful to the other
1092  * side.
1093  *
1094  *      Currently we recognize:
1095  *
1096  *      Terminal type is
1097  *      Linemode
1098  *      Window size
1099  *      Terminal speed
1100  */
1101 void
1102 suboption(void)
1103 {
1104     int subchar;
1105
1106     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1107
1108     subchar = SB_GET();
1109     switch (subchar) {
1110     case TELOPT_TSPEED: {
1111         int xspeed, rspeed;
1112
1113         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
1114                 break;
1115
1116         settimer(tspeedsubopt);
1117
1118         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1119                 return;
1120
1121         xspeed = atoi((char *)subpointer);
1122
1123         while (SB_GET() != ',' && !SB_EOF());
1124         if (SB_EOF())
1125                 return;
1126
1127         rspeed = atoi((char *)subpointer);
1128         clientstat(TELOPT_TSPEED, xspeed, rspeed);
1129
1130         break;
1131
1132     }  /* end of case TELOPT_TSPEED */
1133
1134     case TELOPT_TTYPE: {                /* Yaaaay! */
1135         static char terminalname[TERMINAL_TYPE_SIZE];
1136
1137         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
1138                 break;
1139         settimer(ttypesubopt);
1140
1141         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1142             return;             /* ??? XXX but, this is the most robust */
1143         }
1144
1145         terminaltype = terminalname;
1146
1147         while ((terminaltype < (terminalname + sizeof terminalname-1)) &&
1148                                                                     !SB_EOF()) {
1149             int c;
1150
1151             c = SB_GET();
1152             if (isupper(c)) {
1153                 c = tolower(c);
1154             }
1155             *terminaltype++ = c;    /* accumulate name */
1156         }
1157         *terminaltype = 0;
1158         terminaltype = terminalname;
1159         break;
1160     }  /* end of case TELOPT_TTYPE */
1161
1162     case TELOPT_NAWS: {
1163         int xwinsize, ywinsize;
1164
1165         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
1166                 break;
1167
1168         if (SB_EOF())
1169                 return;
1170         xwinsize = SB_GET() << 8;
1171         if (SB_EOF())
1172                 return;
1173         xwinsize |= SB_GET();
1174         if (SB_EOF())
1175                 return;
1176         ywinsize = SB_GET() << 8;
1177         if (SB_EOF())
1178                 return;
1179         ywinsize |= SB_GET();
1180         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1181
1182         break;
1183
1184     }  /* end of case TELOPT_NAWS */
1185
1186 #ifdef  LINEMODE
1187     case TELOPT_LINEMODE: {
1188         int request;
1189
1190         if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
1191                 break;
1192         /*
1193          * Process linemode suboptions.
1194          */
1195         if (SB_EOF())
1196             break;              /* garbage was sent */
1197         request = SB_GET();     /* get will/wont */
1198
1199         if (SB_EOF())
1200             break;              /* another garbage check */
1201
1202         if (request == LM_SLC) {  /* SLC is not preceeded by WILL or WONT */
1203                 /*
1204                  * Process suboption buffer of slc's
1205                  */
1206                 start_slc(1);
1207                 do_opt_slc(subpointer, subend - subpointer);
1208                 (void) end_slc(0);
1209                 break;
1210         } else if (request == LM_MODE) {
1211                 if (SB_EOF())
1212                     return;
1213                 useeditmode = SB_GET();  /* get mode flag */
1214                 clientstat(LM_MODE, 0, 0);
1215                 break;
1216         }
1217
1218         if (SB_EOF())
1219             break;
1220         switch (SB_GET()) {  /* what suboption? */
1221         case LM_FORWARDMASK:
1222                 /*
1223                  * According to spec, only server can send request for
1224                  * forwardmask, and client can only return a positive response.
1225                  * So don't worry about it.
1226                  */
1227
1228         default:
1229                 break;
1230         }
1231         break;
1232     }  /* end of case TELOPT_LINEMODE */
1233 #endif
1234     case TELOPT_STATUS: {
1235         int mode;
1236
1237         if (SB_EOF())
1238             break;
1239         mode = SB_GET();
1240         switch (mode) {
1241         case TELQUAL_SEND:
1242             if (my_state_is_will(TELOPT_STATUS))
1243                 send_status();
1244             break;
1245
1246         case TELQUAL_IS:
1247             break;
1248
1249         default:
1250             break;
1251         }
1252         break;
1253     }  /* end of case TELOPT_STATUS */
1254
1255     case TELOPT_XDISPLOC: {
1256         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1257                 return;
1258         settimer(xdisplocsubopt);
1259         subpointer[SB_LEN()] = '\0';
1260         if (setenv("DISPLAY", (char *)subpointer, 1) == -1)
1261                 syslog(LOG_ERR, "setenv: cannot set DISPLAY=%s: %m", (char *)subpointer);
1262         break;
1263     }  /* end of case TELOPT_XDISPLOC */
1264
1265 #ifdef  TELOPT_NEW_ENVIRON
1266     case TELOPT_NEW_ENVIRON:
1267 #endif
1268     case TELOPT_OLD_ENVIRON: {
1269         int c;
1270         char *cp, *varp, *valp;
1271
1272         if (SB_EOF())
1273                 return;
1274         c = SB_GET();
1275         if (c == TELQUAL_IS) {
1276                 if (subchar == TELOPT_OLD_ENVIRON)
1277                         settimer(oenvironsubopt);
1278                 else
1279                         settimer(environsubopt);
1280         } else if (c != TELQUAL_INFO) {
1281                 return;
1282         }
1283
1284 #ifdef  TELOPT_NEW_ENVIRON
1285         if (subchar == TELOPT_NEW_ENVIRON) {
1286             while (!SB_EOF()) {
1287                 c = SB_GET();
1288                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1289                         break;
1290             }
1291         } else
1292 #endif
1293         {
1294 #ifdef  ENV_HACK
1295             /*
1296              * We only want to do this if we haven't already decided
1297              * whether or not the other side has its VALUE and VAR
1298              * reversed.
1299              */
1300             if (env_ovar < 0) {
1301                 int last = -1;          /* invalid value */
1302                 int empty = 0;
1303                 int got_var = 0, got_value = 0, got_uservar = 0;
1304
1305                 /*
1306                  * The other side might have its VALUE and VAR values
1307                  * reversed.  To be interoperable, we need to determine
1308                  * which way it is.  If the first recognized character
1309                  * is a VAR or VALUE, then that will tell us what
1310                  * type of client it is.  If the fist recognized
1311                  * character is a USERVAR, then we continue scanning
1312                  * the suboption looking for two consecutive
1313                  * VAR or VALUE fields.  We should not get two
1314                  * consecutive VALUE fields, so finding two
1315                  * consecutive VALUE or VAR fields will tell us
1316                  * what the client is.
1317                  */
1318                 SB_SAVE();
1319                 while (!SB_EOF()) {
1320                         c = SB_GET();
1321                         switch(c) {
1322                         case OLD_ENV_VAR:
1323                                 if (last < 0 || last == OLD_ENV_VAR
1324                                     || (empty && (last == OLD_ENV_VALUE)))
1325                                         goto env_ovar_ok;
1326                                 got_var++;
1327                                 last = OLD_ENV_VAR;
1328                                 break;
1329                         case OLD_ENV_VALUE:
1330                                 if (last < 0 || last == OLD_ENV_VALUE
1331                                     || (empty && (last == OLD_ENV_VAR)))
1332                                         goto env_ovar_wrong;
1333                                 got_value++;
1334                                 last = OLD_ENV_VALUE;
1335                                 break;
1336                         case ENV_USERVAR:
1337                                 /* count strings of USERVAR as one */
1338                                 if (last != ENV_USERVAR)
1339                                         got_uservar++;
1340                                 if (empty) {
1341                                         if (last == OLD_ENV_VALUE)
1342                                                 goto env_ovar_ok;
1343                                         if (last == OLD_ENV_VAR)
1344                                                 goto env_ovar_wrong;
1345                                 }
1346                                 last = ENV_USERVAR;
1347                                 break;
1348                         case ENV_ESC:
1349                                 if (!SB_EOF())
1350                                         c = SB_GET();
1351                                 /* FALL THROUGH */
1352                         default:
1353                                 empty = 0;
1354                                 continue;
1355                         }
1356                         empty = 1;
1357                 }
1358                 if (empty) {
1359                         if (last == OLD_ENV_VALUE)
1360                                 goto env_ovar_ok;
1361                         if (last == OLD_ENV_VAR)
1362                                 goto env_ovar_wrong;
1363                 }
1364                 /*
1365                  * Ok, the first thing was a USERVAR, and there
1366                  * are not two consecutive VAR or VALUE commands,
1367                  * and none of the VAR or VALUE commands are empty.
1368                  * If the client has sent us a well-formed option,
1369                  * then the number of VALUEs received should always
1370                  * be less than or equal to the number of VARs and
1371                  * USERVARs received.
1372                  *
1373                  * If we got exactly as many VALUEs as VARs and
1374                  * USERVARs, the client has the same definitions.
1375                  *
1376                  * If we got exactly as many VARs as VALUEs and
1377                  * USERVARS, the client has reversed definitions.
1378                  */
1379                 if (got_uservar + got_var == got_value) {
1380             env_ovar_ok:
1381                         env_ovar = OLD_ENV_VAR;
1382                         env_ovalue = OLD_ENV_VALUE;
1383                 } else if (got_uservar + got_value == got_var) {
1384             env_ovar_wrong:
1385                         env_ovar = OLD_ENV_VALUE;
1386                         env_ovalue = OLD_ENV_VAR;
1387                         DIAG(TD_OPTIONS,
1388                             output_data("ENVIRON VALUE and VAR are reversed!\r\n"));
1389
1390                 }
1391             }
1392             SB_RESTORE();
1393 #endif
1394
1395             while (!SB_EOF()) {
1396                 c = SB_GET();
1397                 if ((c == env_ovar) || (c == ENV_USERVAR))
1398                         break;
1399             }
1400         }
1401
1402         if (SB_EOF())
1403                 return;
1404
1405         cp = varp = (char *)subpointer;
1406         valp = 0;
1407
1408         while (!SB_EOF()) {
1409                 c = SB_GET();
1410                 if (subchar == TELOPT_OLD_ENVIRON) {
1411                         if (c == env_ovar)
1412                                 c = NEW_ENV_VAR;
1413                         else if (c == env_ovalue)
1414                                 c = NEW_ENV_VALUE;
1415                 }
1416                 switch (c) {
1417
1418                 case NEW_ENV_VALUE:
1419                         *cp = '\0';
1420                         cp = valp = (char *)subpointer;
1421                         break;
1422
1423                 case NEW_ENV_VAR:
1424                 case ENV_USERVAR:
1425                         *cp = '\0';
1426                         if (envvarok(varp)) {
1427                                 if (valp) {
1428                                         if (setenv(varp, valp, 1) == -1)
1429                                                 syslog(LOG_ERR, "setenv: cannot set %s=%s: %m", varp, valp);
1430                                 }
1431                                 else
1432                                         unsetenv(varp);
1433                         }
1434                         cp = varp = (char *)subpointer;
1435                         valp = 0;
1436                         break;
1437
1438                 case ENV_ESC:
1439                         if (SB_EOF())
1440                                 break;
1441                         c = SB_GET();
1442                         /* FALL THROUGH */
1443                 default:
1444                         *cp++ = c;
1445                         break;
1446                 }
1447         }
1448         *cp = '\0';
1449         if (envvarok(varp)) {
1450                 if (valp) {
1451                         if (setenv(varp, valp, 1) == -1)
1452                                 syslog(LOG_ERR, "setenv: cannot set %s=%s: %m", varp, valp);
1453                 }
1454                 else
1455                         unsetenv(varp);
1456         }
1457         break;
1458     }  /* end of case TELOPT_NEW_ENVIRON */
1459 #ifdef  AUTHENTICATION
1460     case TELOPT_AUTHENTICATION:
1461         if (SB_EOF())
1462                 break;
1463         switch(SB_GET()) {
1464         case TELQUAL_SEND:
1465         case TELQUAL_REPLY:
1466                 /*
1467                  * These are sent by us and cannot be sent by
1468                  * the client.
1469                  */
1470                 break;
1471         case TELQUAL_IS:
1472                 auth_is(subpointer, SB_LEN());
1473                 break;
1474         case TELQUAL_NAME:
1475                 auth_name(subpointer, SB_LEN());
1476                 break;
1477         }
1478         break;
1479 #endif
1480 #ifdef  ENCRYPTION
1481     case TELOPT_ENCRYPT:
1482         if (SB_EOF())
1483                 break;
1484         switch(SB_GET()) {
1485         case ENCRYPT_SUPPORT:
1486                 encrypt_support(subpointer, SB_LEN());
1487                 break;
1488         case ENCRYPT_IS:
1489                 encrypt_is(subpointer, SB_LEN());
1490                 break;
1491         case ENCRYPT_REPLY:
1492                 encrypt_reply(subpointer, SB_LEN());
1493                 break;
1494         case ENCRYPT_START:
1495                 encrypt_start(subpointer, SB_LEN());
1496                 break;
1497         case ENCRYPT_END:
1498                 encrypt_end();
1499                 break;
1500         case ENCRYPT_REQSTART:
1501                 encrypt_request_start(subpointer, SB_LEN());
1502                 break;
1503         case ENCRYPT_REQEND:
1504                 /*
1505                  * We can always send an REQEND so that we cannot
1506                  * get stuck encrypting.  We should only get this
1507                  * if we have been able to get in the correct mode
1508                  * anyhow.
1509                  */
1510                 encrypt_request_end();
1511                 break;
1512         case ENCRYPT_ENC_KEYID:
1513                 encrypt_enc_keyid(subpointer, SB_LEN());
1514                 break;
1515         case ENCRYPT_DEC_KEYID:
1516                 encrypt_dec_keyid(subpointer, SB_LEN());
1517                 break;
1518         default:
1519                 break;
1520         }
1521         break;
1522 #endif  /* ENCRYPTION */
1523
1524     default:
1525         break;
1526     }  /* end of switch */
1527
1528 }  /* end of suboption */
1529
1530 static void
1531 doclientstat(void)
1532 {
1533         clientstat(TELOPT_LINEMODE, WILL, 0);
1534 }
1535
1536 #define ADD(c)   *ncp++ = c
1537 #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1538 void
1539 send_status(void)
1540 {
1541         unsigned char statusbuf[256];
1542         unsigned char *ncp;
1543         unsigned char i;
1544
1545         ncp = statusbuf;
1546
1547         netflush();     /* get rid of anything waiting to go out */
1548
1549         ADD(IAC);
1550         ADD(SB);
1551         ADD(TELOPT_STATUS);
1552         ADD(TELQUAL_IS);
1553
1554         /*
1555          * We check the want_state rather than the current state,
1556          * because if we received a DO/WILL for an option that we
1557          * don't support, and the other side didn't send a DONT/WONT
1558          * in response to our WONT/DONT, then the "state" will be
1559          * WILL/DO, and the "want_state" will be WONT/DONT.  We
1560          * need to go by the latter.
1561          */
1562         for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1563                 if (my_want_state_is_will(i)) {
1564                         ADD(WILL);
1565                         ADD_DATA(i);
1566                         if (i == IAC)
1567                                 ADD(IAC);
1568                 }
1569                 if (his_want_state_is_will(i)) {
1570                         ADD(DO);
1571                         ADD_DATA(i);
1572                         if (i == IAC)
1573                                 ADD(IAC);
1574                 }
1575         }
1576
1577         if (his_want_state_is_will(TELOPT_LFLOW)) {
1578                 ADD(SB);
1579                 ADD(TELOPT_LFLOW);
1580                 if (flowmode) {
1581                         ADD(LFLOW_ON);
1582                 } else {
1583                         ADD(LFLOW_OFF);
1584                 }
1585                 ADD(SE);
1586
1587                 if (restartany >= 0) {
1588                         ADD(SB);
1589                         ADD(TELOPT_LFLOW);
1590                         if (restartany) {
1591                                 ADD(LFLOW_RESTART_ANY);
1592                         } else {
1593                                 ADD(LFLOW_RESTART_XON);
1594                         }
1595                         ADD(SE);
1596                 }
1597         }
1598
1599 #ifdef  LINEMODE
1600         if (his_want_state_is_will(TELOPT_LINEMODE)) {
1601                 unsigned char *cp, *cpe;
1602                 int len;
1603
1604                 ADD(SB);
1605                 ADD(TELOPT_LINEMODE);
1606                 ADD(LM_MODE);
1607                 ADD_DATA(editmode);
1608                 ADD(SE);
1609
1610                 ADD(SB);
1611                 ADD(TELOPT_LINEMODE);
1612                 ADD(LM_SLC);
1613                 start_slc(0);
1614                 send_slc();
1615                 len = end_slc(&cp);
1616                 for (cpe = cp + len; cp < cpe; cp++)
1617                         ADD_DATA(*cp);
1618                 ADD(SE);
1619         }
1620 #endif  /* LINEMODE */
1621
1622         ADD(IAC);
1623         ADD(SE);
1624
1625         output_datalen(statusbuf, ncp - statusbuf);
1626         netflush();     /* Send it on its way */
1627
1628         DIAG(TD_OPTIONS,
1629                 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1630 }
1631
1632 /*
1633  * This function appends data to nfrontp and advances nfrontp.
1634  * Returns the number of characters written altogether (the
1635  * buffer may have been flushed in the process).
1636  */
1637
1638 int
1639 output_data(const char *format, ...)
1640 {
1641         va_list args;
1642         int len;
1643         char *buf;
1644
1645         va_start(args, format);
1646         if ((len = vasprintf(&buf, format, args)) == -1)
1647                 return -1;
1648         output_datalen(buf, len);
1649         va_end(args);
1650         free(buf);
1651         return (len);
1652 }
1653
1654 void
1655 output_datalen(const char *buf, int len)
1656 {
1657         int remaining, copied;
1658
1659         remaining = BUFSIZ - (nfrontp - netobuf);
1660         while (len > 0) {
1661                 /* Free up enough space if the room is too low*/
1662                 if ((len > BUFSIZ ? BUFSIZ : len) > remaining) {
1663                         netflush();
1664                         remaining = BUFSIZ - (nfrontp - netobuf);
1665                 }
1666
1667                 /* Copy out as much as will fit */
1668                 copied = remaining > len ? len : remaining;
1669                 memmove(nfrontp, buf, copied);
1670                 nfrontp += copied;
1671                 len -= copied;
1672                 remaining -= copied;
1673                 buf += copied;
1674         }
1675         return;
1676 }