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
  34 #include <sys/cdefs.h>
  35
  36 __FBSDID("$FreeBSD: src/libexec/telnetd/state.c,v 1.9.2.4 2002/04/13 11:07:12 markm Exp $");
  37
  38 #ifndef lint
  39 static const char sccsid[] = "@(#)state.c       8.5 (Berkeley) 5/30/95";
  40 #endif
  41
  42 #include <stdarg.h>
  43 #include "telnetd.h"
  44
  45 unsigned char   doopt[] = { IAC, DO, '%', 'c', 0 };
  46 unsigned char   dont[] = { IAC, DONT, '%', 'c', 0 };
  47 unsigned char   will[] = { IAC, WILL, '%', 'c', 0 };
  48 unsigned char   wont[] = { IAC, WONT, '%', 'c', 0 };
  49 int     not42 = 1;
  50
  51 /*
  52  * Buffer for sub-options, and macros
  53  * for suboptions buffer manipulations
  54  */
  55 unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;
  56
  57 #define SB_CLEAR()      subpointer = subbuffer
  58 #define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
  59 #define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
  60                                 *subpointer++ = (c); \
  61                         }
  62 #define SB_GET()        ((*subpointer++)&0xff)
  63 #define SB_EOF()        (subpointer >= subend)
  64 #define SB_LEN()        (subend - subpointer)
  65
  66 #ifdef  ENV_HACK
  67 unsigned char *subsave;
  68 #define SB_SAVE()       subsave = subpointer;
  69 #define SB_RESTORE()    subpointer = subsave;
  70 #endif
  71
  72
  73 /*
  74  * State for recv fsm
  75  */
  76 #define TS_DATA         0       /* base state */
  77 #define TS_IAC          1       /* look for double IAC's */
  78 #define TS_CR           2       /* CR-LF ->'s CR */
  79 #define TS_SB           3       /* throw away begin's... */
  80 #define TS_SE           4       /* ...end's (suboption negotiation) */
  81 #define TS_WILL         5       /* will option negotiation */
  82 #define TS_WONT         6       /* wont " */
  83 #define TS_DO           7       /* do " */
  84 #define TS_DONT         8       /* dont " */
  85
  86 static void doclientstat(void);
  87
  88 void
  89 telrcv(void)
  90 {
  91         int c;
  92         static int state = TS_DATA;
  93
  94         while (ncc > 0) {
  95                 if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
  96                         break;
  97                 c = *netip++ & 0377, ncc--;
  98                 switch (state) {
  99
 100                 case TS_CR:
 101                         state = TS_DATA;
 102                         /* Strip off \n or \0 after a \r */
 103                         if ((c == 0) || (c == '\n')) {
 104                                 break;
 105                         }
 106                         /* FALL THROUGH */
 107
 108                 case TS_DATA:
 109                         if (c == IAC) {
 110                                 state = TS_IAC;
 111                                 break;
 112                         }
 113                         /*
 114                          * We now map \r\n ==> \r for pragmatic reasons.
 115                          * Many client implementations send \r\n when
 116                          * the user hits the CarriageReturn key.
 117                          *
 118                          * We USED to map \r\n ==> \n, since \r\n says
 119                          * that we want to be in column 1 of the next
 120                          * printable line, and \n is the standard
 121                          * unix way of saying that (\r is only good
 122                          * if CRMOD is set, which it normally is).
 123                          */
 124                         if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
 125                                 int nc = *netip;
 126 #ifdef  LINEMODE
 127                                 /*
 128                                  * If we are operating in linemode,
 129                                  * convert to local end-of-line.
 130                                  */
 131                                 if (linemode && (ncc > 0) && (('\n' == nc) ||
 132                                          ((0 == nc) && tty_iscrnl())) ) {
 133                                         netip++; ncc--;
 134                                         c = '\n';
 135                                 } else
 136 #endif
 137                                 {
 138                                         state = TS_CR;
 139                                 }
 140                         }
 141                         *pfrontp++ = c;
 142                         break;
 143
 144                 case TS_IAC:
 145 gotiac:                 switch (c) {
 146
 147                         /*
 148                          * Send the process on the pty side an
 149                          * interrupt.  Do this with a NULL or
 150                          * interrupt char; depending on the tty mode.
 151                          */
 152                         case IP:
 153                                 DIAG(TD_OPTIONS,
 154                                         printoption("td: recv IAC", c));
 155                                 interrupt();
 156                                 break;
 157
 158                         case BREAK:
 159                                 DIAG(TD_OPTIONS,
 160                                         printoption("td: recv IAC", c));
 161                                 sendbrk();
 162                                 break;
 163
 164                         /*
 165                          * Are You There?
 166                          */
 167                         case AYT:
 168                                 DIAG(TD_OPTIONS,
 169                                         printoption("td: recv IAC", c));
 170                                 recv_ayt();
 171                                 break;
 172
 173                         /*
 174                          * Abort Output
 175                          */
 176                         case AO:
 177                             {
 178                                 DIAG(TD_OPTIONS,
 179                                         printoption("td: recv IAC", c));
 180                                 ptyflush();     /* half-hearted */
 181                                 init_termbuf();
 182
 183                                 if (slctab[SLC_AO].sptr &&
 184                                     *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
 185                                     *pfrontp++ =
 186                                         (unsigned char)*slctab[SLC_AO].sptr;
 187                                 }
 188
 189                                 netclear();     /* clear buffer back */
 190                                 output_data("%c%c", IAC, DM);
 191                                 neturg = nfrontp-1; /* off by one XXX */
 192                                 DIAG(TD_OPTIONS,
 193                                         printoption("td: send IAC", DM));
 194                                 break;
 195                             }
 196
 197                         /*
 198                          * Erase Character and
 199                          * Erase Line
 200                          */
 201                         case EC:
 202                         case EL:
 203                             {
 204                                 cc_t ch;
 205
 206                                 DIAG(TD_OPTIONS,
 207                                         printoption("td: recv IAC", c));
 208                                 ptyflush();     /* half-hearted */
 209                                 init_termbuf();
 210                                 if (c == EC)
 211                                         ch = *slctab[SLC_EC].sptr;
 212                                 else
 213                                         ch = *slctab[SLC_EL].sptr;
 214                                 if (ch != (cc_t)(_POSIX_VDISABLE))
 215                                         *pfrontp++ = (unsigned char)ch;
 216                                 break;
 217                             }
 218
 219                         /*
 220                          * Check for urgent data...
 221                          */
 222                         case DM:
 223                                 DIAG(TD_OPTIONS,
 224                                         printoption("td: recv IAC", c));
 225                                 SYNCHing = stilloob(net);
 226                                 settimer(gotDM);
 227                                 break;
 228
 229
 230                         /*
 231                          * Begin option subnegotiation...
 232                          */
 233                         case SB:
 234                                 state = TS_SB;
 235                                 SB_CLEAR();
 236                                 continue;
 237
 238                         case WILL:
 239                                 state = TS_WILL;
 240                                 continue;
 241
 242                         case WONT:
 243                                 state = TS_WONT;
 244                                 continue;
 245
 246                         case DO:
 247                                 state = TS_DO;
 248                                 continue;
 249
 250                         case DONT:
 251                                 state = TS_DONT;
 252                                 continue;
 253                         case EOR:
 254                                 if (his_state_is_will(TELOPT_EOR))
 255                                         doeof();
 256                                 break;
 257
 258                         /*
 259                          * Handle RFC 10xx Telnet linemode option additions
 260                          * to command stream (EOF, SUSP, ABORT).
 261                          */
 262                         case xEOF:
 263                                 doeof();
 264                                 break;
 265
 266                         case SUSP:
 267                                 sendsusp();
 268                                 break;
 269
 270                         case ABORT:
 271                                 sendbrk();
 272                                 break;
 273
 274                         case IAC:
 275                                 *pfrontp++ = c;
 276                                 break;
 277                         }
 278                         state = TS_DATA;
 279                         break;
 280
 281                 case TS_SB:
 282                         if (c == IAC) {
 283                                 state = TS_SE;
 284                         } else {
 285                                 SB_ACCUM(c);
 286                         }
 287                         break;
 288
 289                 case TS_SE:
 290                         if (c != SE) {
 291                                 if (c != IAC) {
 292                                         /*
 293                                          * bad form of suboption negotiation.
 294                                          * handle it in such a way as to avoid
 295                                          * damage to local state.  Parse
 296                                          * suboption buffer found so far,
 297                                          * then treat remaining stream as
 298                                          * another command sequence.
 299                                          */
 300
 301                                         /* for DIAGNOSTICS */
 302                                         SB_ACCUM(IAC);
 303                                         SB_ACCUM(c);
 304                                         subpointer -= 2;
 305
 306                                         SB_TERM();
 307                                         suboption();
 308                                         state = TS_IAC;
 309                                         goto gotiac;
 310                                 }
 311                                 SB_ACCUM(c);
 312                                 state = TS_SB;
 313                         } else {
 314                                 /* for DIAGNOSTICS */
 315                                 SB_ACCUM(IAC);
 316                                 SB_ACCUM(SE);
 317                                 subpointer -= 2;
 318
 319                                 SB_TERM();
 320                                 suboption();    /* handle sub-option */
 321                                 state = TS_DATA;
 322                         }
 323                         break;
 324
 325                 case TS_WILL:
 326                         willoption(c);
 327                         state = TS_DATA;
 328                         continue;
 329
 330                 case TS_WONT:
 331                         wontoption(c);
 332                         state = TS_DATA;
 333                         continue;
 334
 335                 case TS_DO:
 336                         dooption(c);
 337                         state = TS_DATA;
 338                         continue;
 339
 340                 case TS_DONT:
 341                         dontoption(c);
 342                         state = TS_DATA;
 343                         continue;
 344
 345                 default:
 346                         syslog(LOG_ERR, "panic state=%d", state);
 347                         printf("telnetd: panic state=%d\n", state);
 348                         exit(1);
 349                 }
 350         }
 351 }  /* end of telrcv */
 352
 353 /*
 354  * The will/wont/do/dont state machines are based on Dave Borman's
 355  * Telnet option processing state machine.
 356  *
 357  * These correspond to the following states:
 358  *      my_state = the last negotiated state
 359  *      want_state = what I want the state to go to
 360  *      want_resp = how many requests I have sent
 361  * All state defaults are negative, and resp defaults to 0.
 362  *
 363  * When initiating a request to change state to new_state:
 364  *
 365  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 366  *      do nothing;
 367  * } else {
 368  *      want_state = new_state;
 369  *      send new_state;
 370  *      want_resp++;
 371  * }
 372  *
 373  * When receiving new_state:
 374  *
 375  * if (want_resp) {
 376  *      want_resp--;
 377  *      if (want_resp && (new_state == my_state))
 378  *              want_resp--;
 379  * }
 380  * if ((want_resp == 0) && (new_state != want_state)) {
 381  *      if (ok_to_switch_to new_state)
 382  *              want_state = new_state;
 383  *      else
 384  *              want_resp++;
 385  *      send want_state;
 386  * }
 387  * my_state = new_state;
 388  *
 389  * Note that new_state is implied in these functions by the function itself.
 390  * will and do imply positive new_state, wont and dont imply negative.
 391  *
 392  * Finally, there is one catch.  If we send a negative response to a
 393  * positive request, my_state will be the positive while want_state will
 394  * remain negative.  my_state will revert to negative when the negative
 395  * acknowlegment arrives from the peer.  Thus, my_state generally tells
 396  * us not only the last negotiated state, but also tells us what the peer
 397  * wants to be doing as well.  It is important to understand this difference
 398  * as we may wish to be processing data streams based on our desired state
 399  * (want_state) or based on what the peer thinks the state is (my_state).
 400  *
 401  * This all works fine because if the peer sends a positive request, the data
 402  * that we receive prior to negative acknowlegment will probably be affected
 403  * by the positive state, and we can process it as such (if we can; if we
 404  * can't then it really doesn't matter).  If it is that important, then the
 405  * peer probably should be buffering until this option state negotiation
 406  * is complete.
 407  *
 408  */
 409 void
 410 send_do(int option, int init)
 411 {
 412         if (init) {
 413                 if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
 414                     his_want_state_is_will(option))
 415                         return;
 416                 /*
 417                  * Special case for TELOPT_TM:  We send a DO, but pretend
 418                  * that we sent a DONT, so that we can send more DOs if
 419                  * we want to.
 420                  */
 421                 if (option == TELOPT_TM)
 422                         set_his_want_state_wont(option);
 423                 else
 424                         set_his_want_state_will(option);
 425                 do_dont_resp[option]++;
 426         }
 427         output_data((const char *)doopt, option);
 428
 429         DIAG(TD_OPTIONS, printoption("td: send do", option));
 430 }
 431
 432 void
 433 willoption(int option)
 434 {
 435         int changeok = 0;
 436         void (*func)(void) = 0;
 437
 438         /*
 439          * process input from peer.
 440          */
 441
 442         DIAG(TD_OPTIONS, printoption("td: recv will", option));
 443
 444         if (do_dont_resp[option]) {
 445                 do_dont_resp[option]--;
 446                 if (do_dont_resp[option] && his_state_is_will(option))
 447                         do_dont_resp[option]--;
 448         }
 449         if (do_dont_resp[option] == 0) {
 450             if (his_want_state_is_wont(option)) {
 451                 switch (option) {
 452
 453                 case TELOPT_BINARY:
 454                         init_termbuf();
 455                         tty_binaryin(1);
 456                         set_termbuf();
 457                         changeok++;
 458                         break;
 459
 460                 case TELOPT_ECHO:
 461                         /*
 462                          * See comments below for more info.
 463                          */
 464                         not42 = 0;      /* looks like a 4.2 system */
 465                         break;
 466
 467                 case TELOPT_TM:
 468 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 469                         /*
 470                          * This telnetd implementation does not really
 471                          * support timing marks, it just uses them to
 472                          * support the kludge linemode stuff.  If we
 473                          * receive a will or wont TM in response to our
 474                          * do TM request that may have been sent to
 475                          * determine kludge linemode support, process
 476                          * it, otherwise TM should get a negative
 477                          * response back.
 478                          */
 479                         /*
 480                          * Handle the linemode kludge stuff.
 481                          * If we are not currently supporting any
 482                          * linemode at all, then we assume that this
 483                          * is the client telling us to use kludge
 484                          * linemode in response to our query.  Set the
 485                          * linemode type that is to be supported, note
 486                          * that the client wishes to use linemode, and
 487                          * eat the will TM as though it never arrived.
 488                          */
 489                         if (lmodetype < KLUDGE_LINEMODE) {
 490                                 lmodetype = KLUDGE_LINEMODE;
 491                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 492                                 send_wont(TELOPT_SGA, 1);
 493                         } else if (lmodetype == NO_AUTOKLUDGE) {
 494                                 lmodetype = KLUDGE_OK;
 495                         }
 496 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 497                         /*
 498                          * We never respond to a WILL TM, and
 499                          * we leave the state WONT.
 500                          */
 501                         return;
 502
 503                 case TELOPT_LFLOW:
 504                         /*
 505                          * If we are going to support flow control
 506                          * option, then don't worry peer that we can't
 507                          * change the flow control characters.
 508                          */
 509                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 510                         slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
 511                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 512                         slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
 513                 case TELOPT_TTYPE:
 514                 case TELOPT_SGA:
 515                 case TELOPT_NAWS:
 516                 case TELOPT_TSPEED:
 517                 case TELOPT_XDISPLOC:
 518                 case TELOPT_NEW_ENVIRON:
 519                 case TELOPT_OLD_ENVIRON:
 520                         changeok++;
 521                         break;
 522
 523 #ifdef  LINEMODE
 524                 case TELOPT_LINEMODE:
 525 # ifdef KLUDGELINEMODE
 526                         /*
 527                          * Note client's desire to use linemode.
 528                          */
 529                         lmodetype = REAL_LINEMODE;
 530 # endif /* KLUDGELINEMODE */
 531                         func = doclientstat;
 532                         changeok++;
 533                         break;
 534 #endif  /* LINEMODE */
 535
 536
 537
 538                 default:
 539                         break;
 540                 }
 541                 if (changeok) {
 542                         set_his_want_state_will(option);
 543                         send_do(option, 0);
 544                 } else {
 545                         do_dont_resp[option]++;
 546                         send_dont(option, 0);
 547                 }
 548             } else {
 549                 /*
 550                  * Option processing that should happen when
 551                  * we receive conformation of a change in
 552                  * state that we had requested.
 553                  */
 554                 switch (option) {
 555                 case TELOPT_ECHO:
 556                         not42 = 0;      /* looks like a 4.2 system */
 557                         /*
 558                          * Egads, he responded "WILL ECHO".  Turn
 559                          * it off right now!
 560                          */
 561                         send_dont(option, 1);
 562                         /*
 563                          * "WILL ECHO".  Kludge upon kludge!
 564                          * A 4.2 client is now echoing user input at
 565                          * the tty.  This is probably undesireable and
 566                          * it should be stopped.  The client will
 567                          * respond WONT TM to the DO TM that we send to
 568                          * check for kludge linemode.  When the WONT TM
 569                          * arrives, linemode will be turned off and a
 570                          * change propogated to the pty.  This change
 571                          * will cause us to process the new pty state
 572                          * in localstat(), which will notice that
 573                          * linemode is off and send a WILL ECHO
 574                          * so that we are properly in character mode and
 575                          * all is well.
 576                          */
 577                         break;
 578 #ifdef  LINEMODE
 579                 case TELOPT_LINEMODE:
 580 # ifdef KLUDGELINEMODE
 581                         /*
 582                          * Note client's desire to use linemode.
 583                          */
 584                         lmodetype = REAL_LINEMODE;
 585 # endif /* KLUDGELINEMODE */
 586                         func = doclientstat;
 587                         break;
 588 #endif  /* LINEMODE */
 589
 590
 591                 case TELOPT_LFLOW:
 592                         func = flowstat;
 593                         break;
 594                 }
 595             }
 596         }
 597         set_his_state_will(option);
 598         if (func)
 599                 (*func)();
 600 }  /* end of willoption */
 601
 602 void
 603 send_dont(int option, int init)
 604 {
 605         if (init) {
 606                 if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
 607                     his_want_state_is_wont(option))
 608                         return;
 609                 set_his_want_state_wont(option);
 610                 do_dont_resp[option]++;
 611         }
 612         output_data((const char *)dont, option);
 613
 614         DIAG(TD_OPTIONS, printoption("td: send dont", option));
 615 }
 616
 617 void
 618 wontoption(int option)
 619 {
 620         /*
 621          * Process client input.
 622          */
 623
 624         DIAG(TD_OPTIONS, printoption("td: recv wont", option));
 625
 626         if (do_dont_resp[option]) {
 627                 do_dont_resp[option]--;
 628                 if (do_dont_resp[option] && his_state_is_wont(option))
 629                         do_dont_resp[option]--;
 630         }
 631         if (do_dont_resp[option] == 0) {
 632             if (his_want_state_is_will(option)) {
 633                 /* it is always ok to change to negative state */
 634                 switch (option) {
 635                 case TELOPT_ECHO:
 636                         not42 = 1; /* doesn't seem to be a 4.2 system */
 637                         break;
 638
 639                 case TELOPT_BINARY:
 640                         init_termbuf();
 641                         tty_binaryin(0);
 642                         set_termbuf();
 643                         break;
 644
 645 #ifdef  LINEMODE
 646                 case TELOPT_LINEMODE:
 647 # ifdef KLUDGELINEMODE
 648                         /*
 649                          * If real linemode is supported, then client is
 650                          * asking to turn linemode off.
 651                          */
 652                         if (lmodetype != REAL_LINEMODE)
 653                                 break;
 654                         lmodetype = KLUDGE_LINEMODE;
 655 # endif /* KLUDGELINEMODE */
 656                         clientstat(TELOPT_LINEMODE, WONT, 0);
 657                         break;
 658 #endif  /* LINEMODE */
 659
 660                 case TELOPT_TM:
 661                         /*
 662                          * If we get a WONT TM, and had sent a DO TM,
 663                          * don't respond with a DONT TM, just leave it
 664                          * as is.  Short circut the state machine to
 665                          * achive this.
 666                          */
 667                         set_his_want_state_wont(TELOPT_TM);
 668                         return;
 669
 670                 case TELOPT_LFLOW:
 671                         /*
 672                          * If we are not going to support flow control
 673                          * option, then let peer know that we can't
 674                          * change the flow control characters.
 675                          */
 676                         slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
 677                         slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
 678                         slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
 679                         slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
 680                         break;
 681
 682
 683                 /*
 684                  * For options that we might spin waiting for
 685                  * sub-negotiation, if the client turns off the
 686                  * option rather than responding to the request,
 687                  * we have to treat it here as if we got a response
 688                  * to the sub-negotiation, (by updating the timers)
 689                  * so that we'll break out of the loop.
 690                  */
 691                 case TELOPT_TTYPE:
 692                         settimer(ttypesubopt);
 693                         break;
 694
 695                 case TELOPT_TSPEED:
 696                         settimer(tspeedsubopt);
 697                         break;
 698
 699                 case TELOPT_XDISPLOC:
 700                         settimer(xdisplocsubopt);
 701                         break;
 702
 703                 case TELOPT_OLD_ENVIRON:
 704                         settimer(oenvironsubopt);
 705                         break;
 706
 707                 case TELOPT_NEW_ENVIRON:
 708                         settimer(environsubopt);
 709                         break;
 710
 711                 default:
 712                         break;
 713                 }
 714                 set_his_want_state_wont(option);
 715                 if (his_state_is_will(option))
 716                         send_dont(option, 0);
 717             } else {
 718                 switch (option) {
 719                 case TELOPT_TM:
 720 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 721                         if (lmodetype < NO_AUTOKLUDGE) {
 722                                 lmodetype = NO_LINEMODE;
 723                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 724                                 send_will(TELOPT_SGA, 1);
 725                                 send_will(TELOPT_ECHO, 1);
 726                         }
 727 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 728                         break;
 729
 730                 default:
 731                         break;
 732                 }
 733             }
 734         }
 735         set_his_state_wont(option);
 736
 737 }  /* end of wontoption */
 738
 739 void
 740 send_will(int option, int init)
 741 {
 742         if (init) {
 743                 if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
 744                     my_want_state_is_will(option))
 745                         return;
 746                 set_my_want_state_will(option);
 747                 will_wont_resp[option]++;
 748         }
 749         output_data((const char *)will, option);
 750
 751         DIAG(TD_OPTIONS, printoption("td: send will", option));
 752 }
 753
 754 #if     !defined(LINEMODE) || !defined(KLUDGELINEMODE)
 755 /*
 756  * When we get a DONT SGA, we will try once to turn it
 757  * back on.  If the other side responds DONT SGA, we
 758  * leave it at that.  This is so that when we talk to
 759  * clients that understand KLUDGELINEMODE but not LINEMODE,
 760  * we'll keep them in char-at-a-time mode.
 761  */
 762 int turn_on_sga = 0;
 763 #endif
 764
 765 void
 766 dooption(int option)
 767 {
 768         int changeok = 0;
 769
 770         /*
 771          * Process client input.
 772          */
 773
 774         DIAG(TD_OPTIONS, printoption("td: recv do", option));
 775
 776         if (will_wont_resp[option]) {
 777                 will_wont_resp[option]--;
 778                 if (will_wont_resp[option] && my_state_is_will(option))
 779                         will_wont_resp[option]--;
 780         }
 781         if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
 782                 switch (option) {
 783                 case TELOPT_ECHO:
 784 #ifdef  LINEMODE
 785 # ifdef KLUDGELINEMODE
 786                         if (lmodetype == NO_LINEMODE)
 787 # else
 788                         if (his_state_is_wont(TELOPT_LINEMODE))
 789 # endif
 790 #endif
 791                         {
 792                                 init_termbuf();
 793                                 tty_setecho(1);
 794                                 set_termbuf();
 795                         }
 796                         changeok++;
 797                         break;
 798
 799                 case TELOPT_BINARY:
 800                         init_termbuf();
 801                         tty_binaryout(1);
 802                         set_termbuf();
 803                         changeok++;
 804                         break;
 805
 806                 case TELOPT_SGA:
 807 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 808                         /*
 809                          * If kludge linemode is in use, then we must
 810                          * process an incoming do SGA for linemode
 811                          * purposes.
 812                          */
 813                         if (lmodetype == KLUDGE_LINEMODE) {
 814                                 /*
 815                                  * Receipt of "do SGA" in kludge
 816                                  * linemode is the peer asking us to
 817                                  * turn off linemode.  Make note of
 818                                  * the request.
 819                                  */
 820                                 clientstat(TELOPT_LINEMODE, WONT, 0);
 821                                 /*
 822                                  * If linemode did not get turned off
 823                                  * then don't tell peer that we did.
 824                                  * Breaking here forces a wont SGA to
 825                                  * be returned.
 826                                  */
 827                                 if (linemode)
 828                                         break;
 829                         }
 830 #else
 831                         turn_on_sga = 0;
 832 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 833                         changeok++;
 834                         break;
 835
 836                 case TELOPT_STATUS:
 837                         changeok++;
 838                         break;
 839
 840                 case TELOPT_TM:
 841                         /*
 842                          * Special case for TM.  We send a WILL, but
 843                          * pretend we sent a WONT.
 844                          */
 845                         send_will(option, 0);
 846                         set_my_want_state_wont(option);
 847                         set_my_state_wont(option);
 848                         return;
 849
 850                 case TELOPT_LOGOUT:
 851                         /*
 852                          * When we get a LOGOUT option, respond
 853                          * with a WILL LOGOUT, make sure that
 854                          * it gets written out to the network,
 855                          * and then just go away...
 856                          */
 857                         set_my_want_state_will(TELOPT_LOGOUT);
 858                         send_will(TELOPT_LOGOUT, 0);
 859                         set_my_state_will(TELOPT_LOGOUT);
 860                         (void)netflush();
 861                         cleanup(0);
 862                         /* NOT REACHED */
 863                         break;
 864
 865                 case TELOPT_LINEMODE:
 866                 case TELOPT_TTYPE:
 867                 case TELOPT_NAWS:
 868                 case TELOPT_TSPEED:
 869                 case TELOPT_LFLOW:
 870                 case TELOPT_XDISPLOC:
 871 #ifdef  TELOPT_ENVIRON
 872                 case TELOPT_NEW_ENVIRON:
 873 #endif
 874                 case TELOPT_OLD_ENVIRON:
 875                 default:
 876                         break;
 877                 }
 878                 if (changeok) {
 879                         set_my_want_state_will(option);
 880                         send_will(option, 0);
 881                 } else {
 882                         will_wont_resp[option]++;
 883                         send_wont(option, 0);
 884                 }
 885         }
 886         set_my_state_will(option);
 887
 888 }  /* end of dooption */
 889
 890 void
 891 send_wont(int option, int init)
 892 {
 893         if (init) {
 894                 if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
 895                     my_want_state_is_wont(option))
 896                         return;
 897                 set_my_want_state_wont(option);
 898                 will_wont_resp[option]++;
 899         }
 900         output_data((const char *)wont, option);
 901
 902         DIAG(TD_OPTIONS, printoption("td: send wont", option));
 903 }
 904
 905 void
 906 dontoption(int option)
 907 {
 908         /*
 909          * Process client input.
 910          */
 911
 912
 913         DIAG(TD_OPTIONS, printoption("td: recv dont", option));
 914
 915         if (will_wont_resp[option]) {
 916                 will_wont_resp[option]--;
 917                 if (will_wont_resp[option] && my_state_is_wont(option))
 918                         will_wont_resp[option]--;
 919         }
 920         if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
 921                 switch (option) {
 922                 case TELOPT_BINARY:
 923                         init_termbuf();
 924                         tty_binaryout(0);
 925                         set_termbuf();
 926                         break;
 927
 928                 case TELOPT_ECHO:       /* we should stop echoing */
 929 #ifdef  LINEMODE
 930 # ifdef KLUDGELINEMODE
 931                         if ((lmodetype != REAL_LINEMODE) &&
 932                             (lmodetype != KLUDGE_LINEMODE))
 933 # else
 934                         if (his_state_is_wont(TELOPT_LINEMODE))
 935 # endif
 936 #endif
 937                         {
 938                                 init_termbuf();
 939                                 tty_setecho(0);
 940                                 set_termbuf();
 941                         }
 942                         break;
 943
 944                 case TELOPT_SGA:
 945 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 946                         /*
 947                          * If kludge linemode is in use, then we
 948                          * must process an incoming do SGA for
 949                          * linemode purposes.
 950                          */
 951                         if ((lmodetype == KLUDGE_LINEMODE) ||
 952                             (lmodetype == KLUDGE_OK)) {
 953                                 /*
 954                                  * The client is asking us to turn
 955                                  * linemode on.
 956                                  */
 957                                 lmodetype = KLUDGE_LINEMODE;
 958                                 clientstat(TELOPT_LINEMODE, WILL, 0);
 959                                 /*
 960                                  * If we did not turn line mode on,
 961                                  * then what do we say?  Will SGA?
 962                                  * This violates design of telnet.
 963                                  * Gross.  Very Gross.
 964                                  */
 965                         }
 966                         break;
 967 #else
 968                         set_my_want_state_wont(option);
 969                         if (my_state_is_will(option))
 970                                 send_wont(option, 0);
 971                         set_my_state_wont(option);
 972                         if (turn_on_sga ^= 1)
 973                                 send_will(option, 1);
 974                         return;
 975 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 976
 977                 default:
 978                         break;
 979                 }
 980
 981                 set_my_want_state_wont(option);
 982                 if (my_state_is_will(option))
 983                         send_wont(option, 0);
 984         }
 985         set_my_state_wont(option);
 986
 987 }  /* end of dontoption */
 988
 989 #ifdef  ENV_HACK
 990 int env_ovar = -1;
 991 int env_ovalue = -1;
 992 #else   /* ENV_HACK */
 993 # define env_ovar OLD_ENV_VAR
 994 # define env_ovalue OLD_ENV_VALUE
 995 #endif  /* ENV_HACK */
 996
 997 /*
 998  * suboption()
 999  *
1000  *      Look at the sub-option buffer, and try to be helpful to the other
1001  * side.
1002  *
1003  *      Currently we recognize:
1004  *
1005  *      Terminal type is
1006  *      Linemode
1007  *      Window size
1008  *      Terminal speed
1009  */
1010 void
1011 suboption(void)
1012 {
1013     int subchar;
1014
1015     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1016
1017     subchar = SB_GET();
1018     switch (subchar) {
1019     case TELOPT_TSPEED: {
1020         int xspeed, rspeed;
1021
1022         if (his_state_is_wont(TELOPT_TSPEED))   /* Ignore if option disabled */
1023                 break;
1024
1025         settimer(tspeedsubopt);
1026
1027         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1028                 return;
1029
1030         xspeed = atoi((char *)subpointer);
1031
1032         while (SB_GET() != ',' && !SB_EOF());
1033         if (SB_EOF())
1034                 return;
1035
1036         rspeed = atoi((char *)subpointer);
1037         clientstat(TELOPT_TSPEED, xspeed, rspeed);
1038
1039         break;
1040
1041     }  /* end of case TELOPT_TSPEED */
1042
1043     case TELOPT_TTYPE: {                /* Yaaaay! */
1044         static char terminalname[41];
1045
1046         if (his_state_is_wont(TELOPT_TTYPE))    /* Ignore if option disabled */
1047                 break;
1048         settimer(ttypesubopt);
1049
1050         if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1051             return;             /* ??? XXX but, this is the most robust */
1052         }
1053
1054         terminaltype = terminalname;
1055
1056         while ((terminaltype < (terminalname + sizeof terminalname-1)) &&
1057                                                                     !SB_EOF()) {
1058             int c;
1059
1060             c = SB_GET();
1061             if (isupper(c)) {
1062                 c = tolower(c);
1063             }
1064             *terminaltype++ = c;    /* accumulate name */
1065         }
1066         *terminaltype = 0;
1067         terminaltype = terminalname;
1068         break;
1069     }  /* end of case TELOPT_TTYPE */
1070
1071     case TELOPT_NAWS: {
1072         int xwinsize, ywinsize;
1073
1074         if (his_state_is_wont(TELOPT_NAWS))     /* Ignore if option disabled */
1075                 break;
1076
1077         if (SB_EOF())
1078                 return;
1079         xwinsize = SB_GET() << 8;
1080         if (SB_EOF())
1081                 return;
1082         xwinsize |= SB_GET();
1083         if (SB_EOF())
1084                 return;
1085         ywinsize = SB_GET() << 8;
1086         if (SB_EOF())
1087                 return;
1088         ywinsize |= SB_GET();
1089         clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1090
1091         break;
1092
1093     }  /* end of case TELOPT_NAWS */
1094
1095 #ifdef  LINEMODE
1096     case TELOPT_LINEMODE: {
1097         int request;
1098
1099         if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
1100                 break;
1101         /*
1102          * Process linemode suboptions.
1103          */
1104         if (SB_EOF())
1105             break;              /* garbage was sent */
1106         request = SB_GET();     /* get will/wont */
1107
1108         if (SB_EOF())
1109             break;              /* another garbage check */
1110
1111         if (request == LM_SLC) {  /* SLC is not preceeded by WILL or WONT */
1112                 /*
1113                  * Process suboption buffer of slc's
1114                  */
1115                 start_slc(1);
1116                 do_opt_slc(subpointer, subend - subpointer);
1117                 (void) end_slc(0);
1118                 break;
1119         } else if (request == LM_MODE) {
1120                 if (SB_EOF())
1121                     return;
1122                 useeditmode = SB_GET();  /* get mode flag */
1123                 clientstat(LM_MODE, 0, 0);
1124                 break;
1125         }
1126
1127         if (SB_EOF())
1128             break;
1129         switch (SB_GET()) {  /* what suboption? */
1130         case LM_FORWARDMASK:
1131                 /*
1132                  * According to spec, only server can send request for
1133                  * forwardmask, and client can only return a positive response.
1134                  * So don't worry about it.
1135                  */
1136
1137         default:
1138                 break;
1139         }
1140         break;
1141     }  /* end of case TELOPT_LINEMODE */
1142 #endif
1143     case TELOPT_STATUS: {
1144         int mode;
1145
1146         if (SB_EOF())
1147             break;
1148         mode = SB_GET();
1149         switch (mode) {
1150         case TELQUAL_SEND:
1151             if (my_state_is_will(TELOPT_STATUS))
1152                 send_status();
1153             break;
1154
1155         case TELQUAL_IS:
1156             break;
1157
1158         default:
1159             break;
1160         }
1161         break;
1162     }  /* end of case TELOPT_STATUS */
1163
1164     case TELOPT_XDISPLOC: {
1165         if (SB_EOF() || SB_GET() != TELQUAL_IS)
1166                 return;
1167         settimer(xdisplocsubopt);
1168         subpointer[SB_LEN()] = '\0';
1169         (void)setenv("DISPLAY", (char *)subpointer, 1);
1170         break;
1171     }  /* end of case TELOPT_XDISPLOC */
1172
1173 #ifdef  TELOPT_NEW_ENVIRON
1174     case TELOPT_NEW_ENVIRON:
1175 #endif
1176     case TELOPT_OLD_ENVIRON: {
1177         int c;
1178         char *cp, *varp, *valp;
1179
1180         if (SB_EOF())
1181                 return;
1182         c = SB_GET();
1183         if (c == TELQUAL_IS) {
1184                 if (subchar == TELOPT_OLD_ENVIRON)
1185                         settimer(oenvironsubopt);
1186                 else
1187                         settimer(environsubopt);
1188         } else if (c != TELQUAL_INFO) {
1189                 return;
1190         }
1191
1192 #ifdef  TELOPT_NEW_ENVIRON
1193         if (subchar == TELOPT_NEW_ENVIRON) {
1194             while (!SB_EOF()) {
1195                 c = SB_GET();
1196                 if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1197                         break;
1198             }
1199         } else
1200 #endif
1201         {
1202 #ifdef  ENV_HACK
1203             /*
1204              * We only want to do this if we haven't already decided
1205              * whether or not the other side has its VALUE and VAR
1206              * reversed.
1207              */
1208             if (env_ovar < 0) {
1209                 int last = -1;          /* invalid value */
1210                 int empty = 0;
1211                 int got_var = 0, got_value = 0, got_uservar = 0;
1212
1213                 /*
1214                  * The other side might have its VALUE and VAR values
1215                  * reversed.  To be interoperable, we need to determine
1216                  * which way it is.  If the first recognized character
1217                  * is a VAR or VALUE, then that will tell us what
1218                  * type of client it is.  If the fist recognized
1219                  * character is a USERVAR, then we continue scanning
1220                  * the suboption looking for two consecutive
1221                  * VAR or VALUE fields.  We should not get two
1222                  * consecutive VALUE fields, so finding two
1223                  * consecutive VALUE or VAR fields will tell us
1224                  * what the client is.
1225                  */
1226                 SB_SAVE();
1227                 while (!SB_EOF()) {
1228                         c = SB_GET();
1229                         switch(c) {
1230                         case OLD_ENV_VAR:
1231                                 if (last < 0 || last == OLD_ENV_VAR
1232                                     || (empty && (last == OLD_ENV_VALUE)))
1233                                         goto env_ovar_ok;
1234                                 got_var++;
1235                                 last = OLD_ENV_VAR;
1236                                 break;
1237                         case OLD_ENV_VALUE:
1238                                 if (last < 0 || last == OLD_ENV_VALUE
1239                                     || (empty && (last == OLD_ENV_VAR)))
1240                                         goto env_ovar_wrong;
1241                                 got_value++;
1242                                 last = OLD_ENV_VALUE;
1243                                 break;
1244                         case ENV_USERVAR:
1245                                 /* count strings of USERVAR as one */
1246                                 if (last != ENV_USERVAR)
1247                                         got_uservar++;
1248                                 if (empty) {
1249                                         if (last == OLD_ENV_VALUE)
1250                                                 goto env_ovar_ok;
1251                                         if (last == OLD_ENV_VAR)
1252                                                 goto env_ovar_wrong;
1253                                 }
1254                                 last = ENV_USERVAR;
1255                                 break;
1256                         case ENV_ESC:
1257                                 if (!SB_EOF())
1258                                         c = SB_GET();
1259                                 /* FALL THROUGH */
1260                         default:
1261                                 empty = 0;
1262                                 continue;
1263                         }
1264                         empty = 1;
1265                 }
1266                 if (empty) {
1267                         if (last == OLD_ENV_VALUE)
1268                                 goto env_ovar_ok;
1269                         if (last == OLD_ENV_VAR)
1270                                 goto env_ovar_wrong;
1271                 }
1272                 /*
1273                  * Ok, the first thing was a USERVAR, and there
1274                  * are not two consecutive VAR or VALUE commands,
1275                  * and none of the VAR or VALUE commands are empty.
1276                  * If the client has sent us a well-formed option,
1277                  * then the number of VALUEs received should always
1278                  * be less than or equal to the number of VARs and
1279                  * USERVARs received.
1280                  *
1281                  * If we got exactly as many VALUEs as VARs and
1282                  * USERVARs, the client has the same definitions.
1283                  *
1284                  * If we got exactly as many VARs as VALUEs and
1285                  * USERVARS, the client has reversed definitions.
1286                  */
1287                 if (got_uservar + got_var == got_value) {
1288             env_ovar_ok:
1289                         env_ovar = OLD_ENV_VAR;
1290                         env_ovalue = OLD_ENV_VALUE;
1291                 } else if (got_uservar + got_value == got_var) {
1292             env_ovar_wrong:
1293                         env_ovar = OLD_ENV_VALUE;
1294                         env_ovalue = OLD_ENV_VAR;
1295                         DIAG(TD_OPTIONS,
1296                             output_data("ENVIRON VALUE and VAR are reversed!\r\n"));
1297
1298                 }
1299             }
1300             SB_RESTORE();
1301 #endif
1302
1303             while (!SB_EOF()) {
1304                 c = SB_GET();
1305                 if ((c == env_ovar) || (c == ENV_USERVAR))
1306                         break;
1307             }
1308         }
1309
1310         if (SB_EOF())
1311                 return;
1312
1313         cp = varp = (char *)subpointer;
1314         valp = 0;
1315
1316         while (!SB_EOF()) {
1317                 c = SB_GET();
1318                 if (subchar == TELOPT_OLD_ENVIRON) {
1319                         if (c == env_ovar)
1320                                 c = NEW_ENV_VAR;
1321                         else if (c == env_ovalue)
1322                                 c = NEW_ENV_VALUE;
1323                 }
1324                 switch (c) {
1325
1326                 case NEW_ENV_VALUE:
1327                         *cp = '\0';
1328                         cp = valp = (char *)subpointer;
1329                         break;
1330
1331                 case NEW_ENV_VAR:
1332                 case ENV_USERVAR:
1333                         *cp = '\0';
1334                         if (valp)
1335                                 (void)setenv(varp, valp, 1);
1336                         else
1337                                 unsetenv(varp);
1338                         cp = varp = (char *)subpointer;
1339                         valp = 0;
1340                         break;
1341
1342                 case ENV_ESC:
1343                         if (SB_EOF())
1344                                 break;
1345                         c = SB_GET();
1346                         /* FALL THROUGH */
1347                 default:
1348                         *cp++ = c;
1349                         break;
1350                 }
1351         }
1352         *cp = '\0';
1353         if (valp)
1354                 (void)setenv(varp, valp, 1);
1355         else
1356                 unsetenv(varp);
1357         break;
1358     }  /* end of case TELOPT_NEW_ENVIRON */
1359
1360     default:
1361         break;
1362     }  /* end of switch */
1363
1364 }  /* end of suboption */
1365
1366 static void
1367 doclientstat(void)
1368 {
1369         clientstat(TELOPT_LINEMODE, WILL, 0);
1370 }
1371
1372 #define ADD(c)   *ncp++ = c
1373 #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1374 void
1375 send_status(void)
1376 {
1377         unsigned char statusbuf[256];
1378         unsigned char *ncp;
1379         unsigned char i;
1380
1381         ncp = statusbuf;
1382
1383         netflush();     /* get rid of anything waiting to go out */
1384
1385         ADD(IAC);
1386         ADD(SB);
1387         ADD(TELOPT_STATUS);
1388         ADD(TELQUAL_IS);
1389
1390         /*
1391          * We check the want_state rather than the current state,
1392          * because if we received a DO/WILL for an option that we
1393          * don't support, and the other side didn't send a DONT/WONT
1394          * in response to our WONT/DONT, then the "state" will be
1395          * WILL/DO, and the "want_state" will be WONT/DONT.  We
1396          * need to go by the latter.
1397          */
1398         for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1399                 if (my_want_state_is_will(i)) {
1400                         ADD(WILL);
1401                         ADD_DATA(i);
1402                         if (i == IAC)
1403                                 ADD(IAC);
1404                 }
1405                 if (his_want_state_is_will(i)) {
1406                         ADD(DO);
1407                         ADD_DATA(i);
1408                         if (i == IAC)
1409                                 ADD(IAC);
1410                 }
1411         }
1412
1413         if (his_want_state_is_will(TELOPT_LFLOW)) {
1414                 ADD(SB);
1415                 ADD(TELOPT_LFLOW);
1416                 if (flowmode) {
1417                         ADD(LFLOW_ON);
1418                 } else {
1419                         ADD(LFLOW_OFF);
1420                 }
1421                 ADD(SE);
1422
1423                 if (restartany >= 0) {
1424                         ADD(SB);
1425                         ADD(TELOPT_LFLOW);
1426                         if (restartany) {
1427                                 ADD(LFLOW_RESTART_ANY);
1428                         } else {
1429                                 ADD(LFLOW_RESTART_XON);
1430                         }
1431                         ADD(SE);
1432                 }
1433         }
1434
1435 #ifdef  LINEMODE
1436         if (his_want_state_is_will(TELOPT_LINEMODE)) {
1437                 unsigned char *cp, *cpe;
1438                 int len;
1439
1440                 ADD(SB);
1441                 ADD(TELOPT_LINEMODE);
1442                 ADD(LM_MODE);
1443                 ADD_DATA(editmode);
1444                 ADD(SE);
1445
1446                 ADD(SB);
1447                 ADD(TELOPT_LINEMODE);
1448                 ADD(LM_SLC);
1449                 start_slc(0);
1450                 send_slc();
1451                 len = end_slc(&cp);
1452                 for (cpe = cp + len; cp < cpe; cp++)
1453                         ADD_DATA(*cp);
1454                 ADD(SE);
1455         }
1456 #endif  /* LINEMODE */
1457
1458         ADD(IAC);
1459         ADD(SE);
1460
1461         output_datalen(statusbuf, ncp - statusbuf);
1462         netflush();     /* Send it on its way */
1463
1464         DIAG(TD_OPTIONS,
1465                 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
1466 }
1467
1468 /*
1469  * This function appends data to nfrontp and advances nfrontp.
1470  * Returns the number of characters written altogether (the
1471  * buffer may have been flushed in the process).
1472  */
1473
1474 int
1475 output_data(const char *format, ...)
1476 {
1477         va_list args;
1478         int len;
1479         char *buf;
1480
1481         va_start(args, format);
1482         if ((len = vasprintf(&buf, format, args)) == -1)
1483                 return -1;
1484         output_datalen(buf, len);
1485         va_end(args);
1486         free(buf);
1487         return (len);
1488 }
1489
1490 void
1491 output_datalen(const char *buf, int len)
1492 {
1493         int remaining, copied;
1494
1495         remaining = BUFSIZ - (nfrontp - netobuf);
1496         while (len > 0) {
1497                 /* Free up enough space if the room is too low*/
1498                 if ((len > BUFSIZ ? BUFSIZ : len) > remaining) {
1499                         netflush();
1500                         remaining = BUFSIZ - (nfrontp - netobuf);
1501                 }
1502
1503                 /* Copy out as much as will fit */
1504                 copied = remaining > len ? len : remaining;
1505                 memmove(nfrontp, buf, copied);
1506                 nfrontp += copied;
1507                 len -= copied;
1508                 remaining -= copied;
1509                 buf += copied;
1510         }
1511         return;
1512 }