libexec/telnetd/slc.c

   1 /*      $NetBSD: slc.c,v 1.15 2006/11/24 19:46:58 christos Exp $        */
   2
   3 /*
   4  * Copyright (c) 1989, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)slc.c       8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: slc.c,v 1.15 2006/11/24 19:46:58 christos Exp $");
  38 #endif
  39 #endif /* not lint */
  40
  41 #include "telnetd.h"
  42
  43 #ifdef  LINEMODE
  44 /*
  45  * local varibles
  46  */
  47 static unsigned char    *def_slcbuf = (unsigned char *)0;
  48 static int              def_slclen = 0;
  49 static int              slcchange;      /* change to slc is requested */
  50 static unsigned char    *slcptr;        /* pointer into slc buffer */
  51 static unsigned char    slcbuf[NSLC*6]; /* buffer for slc negotiation */
  52
  53 void default_slc(void);
  54 void process_slc(u_int, u_int, cc_t);
  55
  56 /*
  57  * send_slc
  58  *
  59  * Write out the current special characters to the client.
  60  */
  61 void
  62 send_slc(void)
  63 {
  64         int i;
  65
  66         /*
  67          * Send out list of triplets of special characters
  68          * to client.  We only send info on the characters
  69          * that are currently supported.
  70          */
  71         for (i = 1; i <= NSLC; i++) {
  72                 if ((slctab[i].defset.flag & SLC_LEVELBITS) == SLC_NOSUPPORT)
  73                         continue;
  74                 add_slc((unsigned char)i, slctab[i].current.flag,
  75                                                         slctab[i].current.val);
  76         }
  77
  78 }  /* end of send_slc */
  79
  80 /*
  81  * default_slc
  82  *
  83  * Set pty special characters to all the defaults.
  84  */
  85 void
  86 default_slc(void)
  87 {
  88         int i;
  89
  90         for (i = 1; i <= NSLC; i++) {
  91                 slctab[i].current.val = slctab[i].defset.val;
  92                 if (slctab[i].current.val == (cc_t)(_POSIX_VDISABLE))
  93                         slctab[i].current.flag = SLC_NOSUPPORT;
  94                 else
  95                         slctab[i].current.flag = slctab[i].defset.flag;
  96                 if (slctab[i].sptr) {
  97                         *(slctab[i].sptr) = slctab[i].defset.val;
  98                 }
  99         }
 100         slcchange = 1;
 101
 102 }  /* end of default_slc */
 103 #endif  /* LINEMODE */
 104
 105 /*
 106  * get_slc_defaults
 107  *
 108  * Initialize the slc mapping table.
 109  */
 110 void
 111 get_slc_defaults(void)
 112 {
 113         int i;
 114
 115         init_termbuf();
 116
 117         for (i = 1; i <= NSLC; i++) {
 118                 slctab[i].defset.flag =
 119                         spcset(i, &slctab[i].defset.val, &slctab[i].sptr);
 120                 slctab[i].current.flag = SLC_NOSUPPORT;
 121                 slctab[i].current.val = 0;
 122         }
 123
 124 }  /* end of get_slc_defaults */
 125
 126 #ifdef  LINEMODE
 127 /*
 128  * add_slc
 129  *
 130  * Add an slc triplet to the slc buffer.
 131  */
 132 void
 133 add_slc(char func, char flag, cc_t val)
 134 {
 135
 136         if ((*slcptr++ = (unsigned char)func) == 0xff)
 137                 *slcptr++ = 0xff;
 138
 139         if ((*slcptr++ = (unsigned char)flag) == 0xff)
 140                 *slcptr++ = 0xff;
 141
 142         if ((*slcptr++ = (unsigned char)val) == 0xff)
 143                 *slcptr++ = 0xff;
 144
 145 }  /* end of add_slc */
 146
 147 /*
 148  * start_slc
 149  *
 150  * Get ready to process incoming slc's and respond to them.
 151  *
 152  * The parameter getit is non-zero if it is necessary to grab a copy
 153  * of the terminal control structures.
 154  */
 155 void
 156 start_slc(int getit)
 157 {
 158
 159         slcchange = 0;
 160         if (getit)
 161                 init_termbuf();
 162         (void)snprintf((char *)slcbuf, sizeof slcbuf, "%c%c%c%c",
 163                                         IAC, SB, TELOPT_LINEMODE, LM_SLC);
 164         slcptr = slcbuf + 4;
 165
 166 }  /* end of start_slc */
 167
 168 /*
 169  * end_slc
 170  *
 171  * Finish up the slc negotiation.  If something to send, then send it.
 172  */
 173 int
 174 end_slc(unsigned char **bufp)
 175 {
 176         int len;
 177
 178         /*
 179          * If a change has occurred, store the new terminal control
 180          * structures back to the terminal driver.
 181          */
 182         if (slcchange) {
 183                 set_termbuf();
 184         }
 185
 186         /*
 187          * If the pty state has not yet been fully processed and there is a
 188          * deferred slc request from the client, then do not send any
 189          * sort of slc negotiation now.  We will respond to the client's
 190          * request very soon.
 191          */
 192         if (def_slcbuf && (terminit() == 0)) {
 193                 return(0);
 194         }
 195
 196         if (slcptr > (slcbuf + 4)) {
 197                 if (bufp) {
 198                         *bufp = &slcbuf[4];
 199                         return(slcptr - slcbuf - 4);
 200                 } else {
 201                         (void) snprintf((char *)slcptr,
 202                             sizeof(slcbuf) - (slcptr - slcbuf), "%c%c",
 203                             IAC, SE);
 204                         slcptr += 2;
 205                         len = slcptr - slcbuf;
 206                         writenet(slcbuf, len);
 207                         netflush();  /* force it out immediately */
 208                         DIAG(TD_OPTIONS, printsub('>', slcbuf+2, len-2););
 209                 }
 210         }
 211         return (0);
 212
 213 }  /* end of end_slc */
 214
 215 /*
 216  * process_slc
 217  *
 218  * Figure out what to do about the client's slc
 219  */
 220 void
 221 process_slc(u_int func, u_int flag, cc_t val)
 222 {
 223         int hislevel, mylevel, ack;
 224
 225         /*
 226          * Ensure that we know something about this function
 227          */
 228         if (func > NSLC) {
 229                 add_slc(func, SLC_NOSUPPORT, 0);
 230                 return;
 231         }
 232
 233         /*
 234          * Process the special case requests of 0 SLC_DEFAULT 0
 235          * and 0 SLC_VARIABLE 0.  Be a little forgiving here, don't
 236          * worry about whether the value is actually 0 or not.
 237          */
 238         if (func == 0) {
 239                 if ((flag = flag & SLC_LEVELBITS) == SLC_DEFAULT) {
 240                         default_slc();
 241                         send_slc();
 242                 } else if (flag == SLC_VARIABLE) {
 243                         send_slc();
 244                 }
 245                 return;
 246         }
 247
 248         /*
 249          * Appears to be a function that we know something about.  So
 250          * get on with it and see what we know.
 251          */
 252
 253         hislevel = flag & SLC_LEVELBITS;
 254         mylevel = slctab[func].current.flag & SLC_LEVELBITS;
 255         ack = flag & SLC_ACK;
 256         /*
 257          * ignore the command if:
 258          * the function value and level are the same as what we already have;
 259          * or the level is the same and the ack bit is set
 260          */
 261         if (hislevel == mylevel && (val == slctab[func].current.val || ack)) {
 262                 return;
 263         } else if (ack) {
 264                 /*
 265                  * If we get here, we got an ack, but the levels don't match.
 266                  * This shouldn't happen.  If it does, it is probably because
 267                  * we have sent two requests to set a variable without getting
 268                  * a response between them, and this is the first response.
 269                  * So, ignore it, and wait for the next response.
 270                  */
 271                 return;
 272         } else {
 273                 change_slc(func, flag, val);
 274         }
 275
 276 }  /* end of process_slc */
 277
 278 /*
 279  * change_slc
 280  *
 281  * Process a request to change one of our special characters.
 282  * Compare client's request with what we are capable of supporting.
 283  */
 284 void
 285 change_slc(int func, int flag, cc_t val)
 286 {
 287         int hislevel, mylevel;
 288
 289         hislevel = flag & SLC_LEVELBITS;
 290         mylevel = slctab[func].defset.flag & SLC_LEVELBITS;
 291         /*
 292          * If client is setting a function to NOSUPPORT
 293          * or DEFAULT, then we can easily and directly
 294          * accommodate the request.
 295          */
 296         if (hislevel == SLC_NOSUPPORT) {
 297                 slctab[func].current.flag = flag;
 298                 slctab[func].current.val = (cc_t)_POSIX_VDISABLE;
 299                 flag |= SLC_ACK;
 300                 add_slc(func, flag, val);
 301                 return;
 302         }
 303         if (hislevel == SLC_DEFAULT) {
 304                 /*
 305                  * Special case here.  If client tells us to use
 306                  * the default on a function we don't support, then
 307                  * return NOSUPPORT instead of what we may have as a
 308                  * default level of DEFAULT.
 309                  */
 310                 if (mylevel == SLC_DEFAULT) {
 311                         slctab[func].current.flag = SLC_NOSUPPORT;
 312                 } else {
 313                         slctab[func].current.flag = slctab[func].defset.flag;
 314                 }
 315                 slctab[func].current.val = slctab[func].defset.val;
 316                 add_slc(func, slctab[func].current.flag,
 317                                                 slctab[func].current.val);
 318                 return;
 319         }
 320
 321         /*
 322          * Client wants us to change to a new value or he
 323          * is telling us that he can't change to our value.
 324          * Some of the slc's we support and can change,
 325          * some we do support but can't change,
 326          * and others we don't support at all.
 327          * If we can change it then we have a pointer to
 328          * the place to put the new value, so change it,
 329          * otherwise, continue the negotiation.
 330          */
 331         if (slctab[func].sptr) {
 332                 /*
 333                  * We can change this one.
 334                  */
 335                 slctab[func].current.val = val;
 336                 *(slctab[func].sptr) = val;
 337                 slctab[func].current.flag = flag;
 338                 flag |= SLC_ACK;
 339                 slcchange = 1;
 340                 add_slc(func, flag, val);
 341         } else {
 342                 /*
 343                 * It is not possible for us to support this
 344                 * request as he asks.
 345                 *
 346                 * If our level is DEFAULT, then just ack whatever was
 347                 * sent.
 348                 *
 349                 * If he can't change and we can't change,
 350                 * then degenerate to NOSUPPORT.
 351                 *
 352                 * Otherwise we send our level back to him, (CANTCHANGE
 353                 * or NOSUPPORT) and if CANTCHANGE, send
 354                 * our value as well.
 355                 */
 356                 if (mylevel == SLC_DEFAULT) {
 357                         slctab[func].current.flag = flag;
 358                         slctab[func].current.val = val;
 359                         flag |= SLC_ACK;
 360                 } else if (hislevel == SLC_CANTCHANGE &&
 361                                     mylevel == SLC_CANTCHANGE) {
 362                         flag &= ~SLC_LEVELBITS;
 363                         flag |= SLC_NOSUPPORT;
 364                         slctab[func].current.flag = flag;
 365                 } else {
 366                         flag &= ~SLC_LEVELBITS;
 367                         flag |= mylevel;
 368                         slctab[func].current.flag = flag;
 369                         if (mylevel == SLC_CANTCHANGE) {
 370                                 slctab[func].current.val =
 371                                         slctab[func].defset.val;
 372                                 val = slctab[func].current.val;
 373                         }
 374                 }
 375                 add_slc(func, flag, val);
 376         }
 377
 378 }  /* end of change_slc */
 379
 380 #if VEOF == VMIN
 381 cc_t oldeofc = '\004';
 382 #endif
 383
 384 /*
 385  * check_slc
 386  *
 387  * Check the special characters in use and notify the client if any have
 388  * changed.  Only those characters that are capable of being changed are
 389  * likely to have changed.  If a local change occurs, kick the support level
 390  * and flags up to the defaults.
 391  */
 392 void
 393 check_slc(void)
 394 {
 395         int i;
 396
 397         for (i = 1; i <= NSLC; i++) {
 398 #if VEOF == VMIN
 399                 /*
 400                  * In a perfect world this would be a neat little
 401                  * function.  But in this world, we should not notify
 402                  * client of changes to the VEOF char when
 403                  * ICANON is off, because it is not representing
 404                  * a special character.
 405                  */
 406                 if (i == SLC_EOF) {
 407                         if (!tty_isediting())
 408                                 continue;
 409                         else if (slctab[i].sptr)
 410                                 oldeofc = *(slctab[i].sptr);
 411                 }
 412 #endif  /* VEOF == VMIN */
 413                 if (slctab[i].sptr &&
 414                                 (*(slctab[i].sptr) != slctab[i].current.val)) {
 415                         slctab[i].current.val = *(slctab[i].sptr);
 416                         if (*(slctab[i].sptr) == (cc_t)_POSIX_VDISABLE)
 417                                 slctab[i].current.flag = SLC_NOSUPPORT;
 418                         else
 419                                 slctab[i].current.flag = slctab[i].defset.flag;
 420                         add_slc((unsigned char)i, slctab[i].current.flag,
 421                                                 slctab[i].current.val);
 422                 }
 423         }
 424 }  /* check_slc */
 425
 426 /*
 427  * do_opt_slc
 428  *
 429  * Process an slc option buffer.  Defer processing of incoming slc's
 430  * until after the terminal state has been processed.  Save the first slc
 431  * request that comes along, but discard all others.
 432  *
 433  * ptr points to the beginning of the buffer, len is the length.
 434  */
 435 void
 436 do_opt_slc(unsigned char *ptr, int len)
 437 {
 438         unsigned char func, flag;
 439         cc_t val;
 440         unsigned char *end = ptr + len;
 441
 442         if (terminit()) {  /* go ahead */
 443                 while (ptr < end) {
 444                         func = *ptr++;
 445                         if (ptr >= end) break;
 446                         flag = *ptr++;
 447                         if (ptr >= end) break;
 448                         val = (cc_t)*ptr++;
 449
 450                         process_slc((u_int)func, (u_int)flag, val);
 451
 452                 }
 453         } else {
 454                 /*
 455                  * save this slc buffer if it is the first, otherwise dump
 456                  * it.
 457                  */
 458                 if (def_slcbuf == (unsigned char *)0) {
 459                         def_slclen = len;
 460                         def_slcbuf = (unsigned char *)malloc((unsigned)len);
 461                         if (def_slcbuf == (unsigned char *)0)
 462                                 return;  /* too bad */
 463                         memcpy(def_slcbuf, ptr, len);
 464                 }
 465         }
 466
 467 }  /* end of do_opt_slc */
 468
 469 /*
 470  * deferslc
 471  *
 472  * Do slc stuff that was deferred.
 473  */
 474 void
 475 deferslc(void)
 476 {
 477         if (def_slcbuf) {
 478                 start_slc(1);
 479                 do_opt_slc(def_slcbuf, def_slclen);
 480                 (void) end_slc(0);
 481                 free(def_slcbuf);
 482                 def_slcbuf = (unsigned char *)0;
 483                 def_slclen = 0;
 484         }
 485
 486 }  /* end of deferslc */
 487
 488 #endif  /* LINEMODE */