libexec/telnetd/telnetd.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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)telnetd.c        8.4 (Berkeley) 5/30/95
  30  * $FreeBSD: src/crypto/telnet/telnetd/telnetd.c,v 1.11.2.5 2002/04/13 10:59:09 markm Exp $
  31  */
  32
  33 #include "telnetd.h"
  34 #include "pathnames.h"
  35
  36 #include <sys/mman.h>
  37 #include <err.h>
  38 #include <libutil.h>
  39 #include <paths.h>
  40 #include <termcap.h>
  41 #include <utmp.h>
  42
  43 #include <arpa/inet.h>
  44
  45 #ifdef  AUTHENTICATION
  46 #include <libtelnet/auth.h>
  47 int     auth_level = 0;
  48 #endif
  49 #ifdef  ENCRYPTION
  50 #include <libtelnet/encrypt.h>
  51 #endif
  52 #include <libtelnet/misc.h>
  53
  54 char    remote_hostname[MAXHOSTNAMELEN];
  55 size_t  utmp_len = sizeof(remote_hostname) - 1;
  56 int     registerd_host_only = 0;
  57
  58
  59 /*
  60  * I/O data buffers,
  61  * pointers, and counters.
  62  */
  63 char    ptyibuf[BUFSIZ], *ptyip = ptyibuf;
  64 char    ptyibuf2[BUFSIZ];
  65
  66 int readstream(int, char *, int);
  67 void doit(struct sockaddr *);
  68 int terminaltypeok(char *);
  69
  70 int     hostinfo = 1;                   /* do we print login banner? */
  71
  72 int debug = 0;
  73 int keepalive = 1;
  74 const char *altlogin;
  75
  76 void doit(struct sockaddr *);
  77 int terminaltypeok(char *);
  78 void startslave(char *, int, char *);
  79 extern void usage(void);
  80 static void _gettermname(void);
  81
  82 /*
  83  * The string to pass to getopt().  We do it this way so
  84  * that only the actual options that we support will be
  85  * passed off to getopt().
  86  */
  87 char valid_opts[] = {
  88         'd', ':', 'h', 'k', 'n', 'p', ':', 'S', ':', 'u', ':', 'U',
  89         '4', '6',
  90 #ifdef  AUTHENTICATION
  91         'a', ':', 'X', ':',
  92 #endif
  93 #ifdef BFTPDAEMON
  94         'B',
  95 #endif
  96 #ifdef DIAGNOSTICS
  97         'D', ':',
  98 #endif
  99 #ifdef  ENCRYPTION
 100         'e', ':',
 101 #endif
 102 #ifdef  LINEMODE
 103         'l',
 104 #endif
 105         '\0'
 106 };
 107
 108 int family = AF_INET;
 109
 110 #ifndef MAXHOSTNAMELEN
 111 #define MAXHOSTNAMELEN 256
 112 #endif  /* MAXHOSTNAMELEN */
 113
 114 char *hostname;
 115 char host_name[MAXHOSTNAMELEN];
 116
 117 extern void telnet(int, int, char *);
 118
 119 int level;
 120 char user_name[256];
 121
 122 int
 123 main(int argc, char *argv[])
 124 {
 125         struct sockaddr_storage from;
 126         int on = 1, fromlen;
 127         int ch;
 128 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 129         int tos = -1;
 130 #endif
 131
 132         pfrontp = pbackp = ptyobuf;
 133         netip = netibuf;
 134         nfrontp = nbackp = netobuf;
 135 #ifdef  ENCRYPTION
 136         nclearto = 0;
 137 #endif  /* ENCRYPTION */
 138
 139         /*
 140          * This initialization causes linemode to default to a configuration
 141          * that works on all telnet clients, including the FreeBSD client.
 142          * This is not quite the same as the telnet client issuing a "mode
 143          * character" command, but has most of the same benefits, and is
 144          * preferable since some clients (like usofts) don't have the
 145          * mode character command anyway and linemode breaks things.
 146          * The most notable symptom of fix is that csh "set filec" operations
 147          * like <ESC> (filename completion) and ^D (choices) keys now work
 148          * in telnet sessions and can be used more than once on the same line.
 149          * CR/LF handling is also corrected in some termio modes.  This
 150          * change resolves problem reports bin/771 and bin/1037.
 151          */
 152
 153         linemode=1;     /*Default to mode that works on bulk of clients*/
 154
 155         while ((ch = getopt(argc, argv, valid_opts)) != -1) {
 156                 switch(ch) {
 157
 158 #ifdef  AUTHENTICATION
 159                 case 'a':
 160                         /*
 161                          * Check for required authentication level
 162                          */
 163                         if (strcmp(optarg, "debug") == 0) {
 164                                 extern int auth_debug_mode;
 165                                 auth_debug_mode = 1;
 166                         } else if (strcasecmp(optarg, "none") == 0) {
 167                                 auth_level = 0;
 168                         } else if (strcasecmp(optarg, "other") == 0) {
 169                                 auth_level = AUTH_OTHER;
 170                         } else if (strcasecmp(optarg, "user") == 0) {
 171                                 auth_level = AUTH_USER;
 172                         } else if (strcasecmp(optarg, "valid") == 0) {
 173                                 auth_level = AUTH_VALID;
 174                         } else if (strcasecmp(optarg, "off") == 0) {
 175                                 /*
 176                                  * This hack turns off authentication
 177                                  */
 178                                 auth_level = -1;
 179                         } else {
 180                                 warnx("unknown authorization level for -a");
 181                         }
 182                         break;
 183 #endif  /* AUTHENTICATION */
 184
 185 #ifdef BFTPDAEMON
 186                 case 'B':
 187                         bftpd++;
 188                         break;
 189 #endif /* BFTPDAEMON */
 190
 191                 case 'd':
 192                         if (strcmp(optarg, "ebug") == 0) {
 193                                 debug++;
 194                                 break;
 195                         }
 196                         usage();
 197                         /* NOTREACHED */
 198                         break;
 199
 200 #ifdef DIAGNOSTICS
 201                 case 'D':
 202                         /*
 203                          * Check for desired diagnostics capabilities.
 204                          */
 205                         if (!strcmp(optarg, "report")) {
 206                                 diagnostic |= TD_REPORT|TD_OPTIONS;
 207                         } else if (!strcmp(optarg, "exercise")) {
 208                                 diagnostic |= TD_EXERCISE;
 209                         } else if (!strcmp(optarg, "netdata")) {
 210                                 diagnostic |= TD_NETDATA;
 211                         } else if (!strcmp(optarg, "ptydata")) {
 212                                 diagnostic |= TD_PTYDATA;
 213                         } else if (!strcmp(optarg, "options")) {
 214                                 diagnostic |= TD_OPTIONS;
 215                         } else {
 216                                 usage();
 217                                 /* NOT REACHED */
 218                         }
 219                         break;
 220 #endif /* DIAGNOSTICS */
 221
 222 #ifdef  ENCRYPTION
 223                 case 'e':
 224                         if (strcmp(optarg, "debug") == 0) {
 225                                 extern int encrypt_debug_mode;
 226                                 encrypt_debug_mode = 1;
 227                                 break;
 228                         }
 229                         usage();
 230                         /* NOTREACHED */
 231                         break;
 232 #endif  /* ENCRYPTION */
 233
 234                 case 'h':
 235                         hostinfo = 0;
 236                         break;
 237
 238 #ifdef  LINEMODE
 239                 case 'l':
 240                         alwayslinemode = 1;
 241                         break;
 242 #endif  /* LINEMODE */
 243
 244                 case 'k':
 245 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 246                         lmodetype = NO_AUTOKLUDGE;
 247 #else
 248                         /* ignore -k option if built without kludge linemode */
 249 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 250                         break;
 251
 252                 case 'n':
 253                         keepalive = 0;
 254                         break;
 255
 256                 case 'p':
 257                         altlogin = optarg;
 258                         break;
 259
 260                 case 'S':
 261 #ifdef  HAS_GETTOS
 262                         if ((tos = parsetos(optarg, "tcp")) < 0)
 263                                 warnx("%s%s%s",
 264                                         "bad TOS argument '", optarg,
 265                                         "'; will try to use default TOS");
 266 #else
 267                         warnx("TOS option unavailable; -S flag not supported");
 268 #endif
 269                         break;
 270
 271                 case 'u':
 272                         utmp_len = (size_t)atoi(optarg);
 273                         if (utmp_len >= sizeof(remote_hostname))
 274                                 utmp_len = sizeof(remote_hostname) - 1;
 275                         break;
 276
 277                 case 'U':
 278                         registerd_host_only = 1;
 279                         break;
 280
 281 #ifdef  AUTHENTICATION
 282                 case 'X':
 283                         /*
 284                          * Check for invalid authentication types
 285                          */
 286                         auth_disable_name(optarg);
 287                         break;
 288 #endif  /* AUTHENTICATION */
 289
 290                 case '4':
 291                         family = AF_INET;
 292                         break;
 293
 294 #ifdef INET6
 295                 case '6':
 296                         family = AF_INET6;
 297                         break;
 298 #endif
 299
 300                 default:
 301                         warnx("%c: unknown option", ch);
 302                         /* FALLTHROUGH */
 303                 case '?':
 304                         usage();
 305                         /* NOTREACHED */
 306                 }
 307         }
 308
 309         argc -= optind;
 310         argv += optind;
 311
 312         if (debug) {
 313             int s, ns, foo, error;
 314             const char *service = "telnet";
 315             struct addrinfo hints, *res;
 316
 317             if (argc > 1) {
 318                 usage();
 319                 /* NOT REACHED */
 320             } else if (argc == 1)
 321                 service = *argv;
 322
 323             memset(&hints, 0, sizeof(hints));
 324             hints.ai_flags = AI_PASSIVE;
 325             hints.ai_family = family;
 326             hints.ai_socktype = SOCK_STREAM;
 327             hints.ai_protocol = 0;
 328             error = getaddrinfo(NULL, service, &hints, &res);
 329
 330             if (error) {
 331                 errx(1, "tcp/%s: %s\n", service, gai_strerror(error));
 332                 if (error == EAI_SYSTEM)
 333                     errx(1, "tcp/%s: %s\n", service, strerror(errno));
 334                 usage();
 335             }
 336
 337             s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 338             if (s < 0)
 339                     err(1, "socket");
 340             (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
 341                                 (char *)&on, sizeof(on));
 342             if (bind(s, res->ai_addr, res->ai_addrlen) < 0)
 343                 err(1, "bind");
 344             if (listen(s, 1) < 0)
 345                 err(1, "listen");
 346             foo = res->ai_addrlen;
 347             ns = accept(s, res->ai_addr, &foo);
 348             if (ns < 0)
 349                 err(1, "accept");
 350             (void) dup2(ns, 0);
 351             (void) close(ns);
 352             (void) close(s);
 353 #ifdef convex
 354         } else if (argc == 1) {
 355                 ; /* VOID*/             /* Just ignore the host/port name */
 356 #endif
 357         } else if (argc > 0) {
 358                 usage();
 359                 /* NOT REACHED */
 360         }
 361
 362         openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
 363         fromlen = sizeof (from);
 364         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 365                 warn("getpeername");
 366                 _exit(1);
 367         }
 368         if (keepalive &&
 369             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE,
 370                         (char *)&on, sizeof (on)) < 0) {
 371                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 372         }
 373
 374 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 375         if (from.ss_family == AF_INET) {
 376 # if    defined(HAS_GETTOS)
 377                 struct tosent *tp;
 378                 if (tos < 0 && (tp = gettosbyname("telnet", "tcp")))
 379                         tos = tp->t_tos;
 380 # endif
 381                 if (tos < 0)
 382                         tos = 020;      /* Low Delay bit */
 383                 if (tos
 384                    && (setsockopt(0, IPPROTO_IP, IP_TOS,
 385                                   (char *)&tos, sizeof(tos)) < 0)
 386                    && (errno != ENOPROTOOPT) )
 387                         syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 388         }
 389 #endif  /* defined(IPPROTO_IP) && defined(IP_TOS) */
 390         net = 0;
 391         doit((struct sockaddr *)&from);
 392         /* NOTREACHED */
 393         return(0);
 394 }  /* end of main */
 395
 396 void
 397 usage(void)
 398 {
 399         fprintf(stderr, "usage: telnetd");
 400 #ifdef  AUTHENTICATION
 401         fprintf(stderr, " [-a (debug|other|user|valid|off|none)]\n\t");
 402 #endif
 403 #ifdef BFTPDAEMON
 404         fprintf(stderr, " [-B]");
 405 #endif
 406         fprintf(stderr, " [-debug]");
 407 #ifdef DIAGNOSTICS
 408         fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t");
 409 #endif
 410 #ifdef  AUTHENTICATION
 411         fprintf(stderr, " [-edebug]");
 412 #endif
 413         fprintf(stderr, " [-h]");
 414 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 415         fprintf(stderr, " [-k]");
 416 #endif
 417 #ifdef LINEMODE
 418         fprintf(stderr, " [-l]");
 419 #endif
 420         fprintf(stderr, " [-n]");
 421         fprintf(stderr, "\n\t");
 422 #ifdef  HAS_GETTOS
 423         fprintf(stderr, " [-S tos]");
 424 #endif
 425 #ifdef  AUTHENTICATION
 426         fprintf(stderr, " [-X auth-type]");
 427 #endif
 428         fprintf(stderr, " [-u utmp_hostname_length] [-U]");
 429         fprintf(stderr, " [port]\n");
 430         exit(1);
 431 }
 432
 433 /*
 434  * getterminaltype
 435  *
 436  *      Ask the other end to send along its terminal type and speed.
 437  * Output is the variable terminaltype filled in.
 438  */
 439 static unsigned char ttytype_sbbuf[] = {
 440         IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
 441 };
 442
 443
 444 #ifndef AUTHENTICATION
 445 #define undef2 __unused
 446 #else
 447 #define undef2
 448 #endif
 449
 450 static int
 451 getterminaltype(char *name undef2)
 452 {
 453     int retval = -1;
 454
 455     settimer(baseline);
 456 #ifdef  AUTHENTICATION
 457     /*
 458      * Handle the Authentication option before we do anything else.
 459      */
 460     send_do(TELOPT_AUTHENTICATION, 1);
 461     while (his_will_wont_is_changing(TELOPT_AUTHENTICATION))
 462         ttloop();
 463     if (his_state_is_will(TELOPT_AUTHENTICATION)) {
 464         retval = auth_wait(name);
 465     }
 466 #endif
 467
 468 #ifdef  ENCRYPTION
 469     send_will(TELOPT_ENCRYPT, 1);
 470 #endif  /* ENCRYPTION */
 471     send_do(TELOPT_TTYPE, 1);
 472     send_do(TELOPT_TSPEED, 1);
 473     send_do(TELOPT_XDISPLOC, 1);
 474     send_do(TELOPT_NEW_ENVIRON, 1);
 475     send_do(TELOPT_OLD_ENVIRON, 1);
 476     while (
 477 #ifdef  ENCRYPTION
 478            his_do_dont_is_changing(TELOPT_ENCRYPT) ||
 479 #endif  /* ENCRYPTION */
 480            his_will_wont_is_changing(TELOPT_TTYPE) ||
 481            his_will_wont_is_changing(TELOPT_TSPEED) ||
 482            his_will_wont_is_changing(TELOPT_XDISPLOC) ||
 483            his_will_wont_is_changing(TELOPT_NEW_ENVIRON) ||
 484            his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) {
 485         ttloop();
 486     }
 487 #ifdef  ENCRYPTION
 488     /*
 489      * Wait for the negotiation of what type of encryption we can
 490      * send with.  If autoencrypt is not set, this will just return.
 491      */
 492     if (his_state_is_will(TELOPT_ENCRYPT)) {
 493         encrypt_wait();
 494     }
 495 #endif  /* ENCRYPTION */
 496     if (his_state_is_will(TELOPT_TSPEED)) {
 497         static unsigned char sb[] =
 498                         { IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE };
 499
 500         output_datalen(sb, sizeof sb);
 501         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 502     }
 503     if (his_state_is_will(TELOPT_XDISPLOC)) {
 504         static unsigned char sb[] =
 505                         { IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE };
 506
 507         output_datalen(sb, sizeof sb);
 508         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 509     }
 510     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 511         static unsigned char sb[] =
 512                         { IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE };
 513
 514         output_datalen(sb, sizeof sb);
 515         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 516     }
 517     else if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 518         static unsigned char sb[] =
 519                         { IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE };
 520
 521         output_datalen(sb, sizeof sb);
 522         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 523     }
 524     if (his_state_is_will(TELOPT_TTYPE)) {
 525
 526         output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 527         DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 528                                         sizeof ttytype_sbbuf - 2););
 529     }
 530     if (his_state_is_will(TELOPT_TSPEED)) {
 531         while (sequenceIs(tspeedsubopt, baseline))
 532             ttloop();
 533     }
 534     if (his_state_is_will(TELOPT_XDISPLOC)) {
 535         while (sequenceIs(xdisplocsubopt, baseline))
 536             ttloop();
 537     }
 538     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 539         while (sequenceIs(environsubopt, baseline))
 540             ttloop();
 541     }
 542     if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 543         while (sequenceIs(oenvironsubopt, baseline))
 544             ttloop();
 545     }
 546     if (his_state_is_will(TELOPT_TTYPE)) {
 547         char first[256], last[256];
 548
 549         while (sequenceIs(ttypesubopt, baseline))
 550             ttloop();
 551
 552         /*
 553          * If the other side has already disabled the option, then
 554          * we have to just go with what we (might) have already gotten.
 555          */
 556         if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
 557             (void) strncpy(first, terminaltype, sizeof(first)-1);
 558             first[sizeof(first)-1] = '\0';
 559             for(;;) {
 560                 /*
 561                  * Save the unknown name, and request the next name.
 562                  */
 563                 (void) strncpy(last, terminaltype, sizeof(last)-1);
 564                 last[sizeof(last)-1] = '\0';
 565                 _gettermname();
 566                 if (terminaltypeok(terminaltype))
 567                     break;
 568                 if ((strncmp(last, terminaltype, sizeof(last)) == 0) ||
 569                     his_state_is_wont(TELOPT_TTYPE)) {
 570                     /*
 571                      * We've hit the end.  If this is the same as
 572                      * the first name, just go with it.
 573                      */
 574                     if (strncmp(first, terminaltype, sizeof(first)) == 0)
 575                         break;
 576                     /*
 577                      * Get the terminal name one more time, so that
 578                      * RFC1091 compliant telnets will cycle back to
 579                      * the start of the list.
 580                      */
 581                      _gettermname();
 582                     if (strncmp(first, terminaltype, sizeof(first)) != 0) {
 583                         (void) strncpy(terminaltype, first, TERMINAL_TYPE_SIZE-1);
 584                         terminaltype[TERMINAL_TYPE_SIZE-1] = '\0';
 585                     }
 586                     break;
 587                 }
 588             }
 589         }
 590     }
 591     return(retval);
 592 }  /* end of getterminaltype */
 593
 594 static void
 595 _gettermname(void)
 596 {
 597     /*
 598      * If the client turned off the option,
 599      * we can't send another request, so we
 600      * just return.
 601      */
 602     if (his_state_is_wont(TELOPT_TTYPE))
 603         return;
 604     settimer(baseline);
 605     output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 606     DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 607                                         sizeof ttytype_sbbuf - 2););
 608     while (sequenceIs(ttypesubopt, baseline))
 609         ttloop();
 610 }
 611
 612 int
 613 terminaltypeok(char *s)
 614 {
 615     char buf[1024];
 616
 617     if (terminaltype == NULL)
 618         return(1);
 619
 620     /*
 621      * tgetent() will return 1 if the type is known, and
 622      * 0 if it is not known.  If it returns -1, it couldn't
 623      * open the database.  But if we can't open the database,
 624      * it won't help to say we failed, because we won't be
 625      * able to verify anything else.  So, we treat -1 like 1.
 626      */
 627     if (tgetent(buf, s) == 0)
 628         return(0);
 629     return(1);
 630 }
 631
 632 /*
 633  * Get a pty, scan input lines.
 634  */
 635 void
 636 doit(struct sockaddr *who)
 637 {
 638         int err_; /* XXX */
 639         int ptynum;
 640
 641         /*
 642          * Find an available pty to use.
 643          */
 644 #ifndef convex
 645         pty = getpty(&ptynum);
 646         if (pty < 0)
 647                 fatal(net, "All network ports in use");
 648 #else
 649         for (;;) {
 650                 char *lp;
 651
 652                 if ((lp = getpty()) == NULL)
 653                         fatal(net, "Out of ptys");
 654
 655                 if ((pty = open(lp, 2)) >= 0) {
 656                         strlcpy(line,lp,sizeof(line));
 657                         line[5] = 't';
 658                         break;
 659                 }
 660         }
 661 #endif
 662
 663         /* get name of connected client */
 664         if (realhostname_sa(remote_hostname, sizeof(remote_hostname) - 1,
 665             who, who->sa_len) == HOSTNAME_INVALIDADDR && registerd_host_only)
 666                 fatal(net, "Couldn't resolve your address into a host name.\r\n\
 667         Please contact your net administrator");
 668         remote_hostname[sizeof(remote_hostname) - 1] = '\0';
 669
 670         trimdomain(remote_hostname, UT_HOSTSIZE);
 671         if (!isdigit(remote_hostname[0]) && strlen(remote_hostname) > utmp_len)
 672                 err_ = getnameinfo(who, who->sa_len, remote_hostname,
 673                                   sizeof(remote_hostname), NULL, 0,
 674                                   NI_NUMERICHOST|NI_WITHSCOPEID);
 675                 /* XXX: do 'err_' check */
 676
 677         (void) gethostname(host_name, sizeof(host_name) - 1);
 678         host_name[sizeof(host_name) - 1] = '\0';
 679         hostname = host_name;
 680
 681 #ifdef  AUTHENTICATION
 682 #ifdef  ENCRYPTION
 683 /* The above #ifdefs should actually be "or"'ed, not "and"'ed.
 684  * This is a byproduct of needing "#ifdef" and not "#if defined()"
 685  * for unifdef. XXX MarkM
 686  */
 687         auth_encrypt_init(hostname, remote_hostname, "TELNETD", 1);
 688 #endif
 689 #endif
 690
 691         init_env();
 692         /*
 693          * get terminal type.
 694          */
 695         *user_name = 0;
 696         level = getterminaltype(user_name);
 697         if (setenv("TERM", terminaltype ? terminaltype : "network", 1) == -1)
 698                 syslog(LOG_ERR, "setenv: cannot set TERM=%s: %m", terminaltype ? terminaltype : "network");
 699
 700         telnet(net, pty, remote_hostname);      /* begin server process */
 701
 702         /*NOTREACHED*/
 703 }  /* end of doit */
 704
 705 /*
 706  * Main loop.  Select from pty and network, and
 707  * hand data to telnet receiver finite state machine.
 708  */
 709 void
 710 telnet(int f, int p, char *host)
 711 {
 712         int on = 1;
 713 #define TABBUFSIZ       512
 714         char    defent[TABBUFSIZ];
 715         char    defstrs[TABBUFSIZ];
 716 #undef  TABBUFSIZ
 717         char *HE;
 718         char *HN;
 719         char *IM;
 720         int nfd;
 721
 722         /*
 723          * Initialize the slc mapping table.
 724          */
 725         get_slc_defaults();
 726
 727         /*
 728          * Do some tests where it is desireable to wait for a response.
 729          * Rather than doing them slowly, one at a time, do them all
 730          * at once.
 731          */
 732         if (my_state_is_wont(TELOPT_SGA))
 733                 send_will(TELOPT_SGA, 1);
 734         /*
 735          * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
 736          * because 4.2 clients are unable to deal with TCP urgent data.
 737          *
 738          * To find out, we send out a "DO ECHO".  If the remote system
 739          * answers "WILL ECHO" it is probably a 4.2 client, and we note
 740          * that fact ("WILL ECHO" ==> that the client will echo what
 741          * WE, the server, sends it; it does NOT mean that the client will
 742          * echo the terminal input).
 743          */
 744         send_do(TELOPT_ECHO, 1);
 745
 746 #ifdef  LINEMODE
 747         if (his_state_is_wont(TELOPT_LINEMODE)) {
 748                 /* Query the peer for linemode support by trying to negotiate
 749                  * the linemode option.
 750                  */
 751                 linemode = 0;
 752                 editmode = 0;
 753                 send_do(TELOPT_LINEMODE, 1);  /* send do linemode */
 754         }
 755 #endif  /* LINEMODE */
 756
 757         /*
 758          * Send along a couple of other options that we wish to negotiate.
 759          */
 760         send_do(TELOPT_NAWS, 1);
 761         send_will(TELOPT_STATUS, 1);
 762         flowmode = 1;           /* default flow control state */
 763         restartany = -1;        /* uninitialized... */
 764         send_do(TELOPT_LFLOW, 1);
 765
 766         /*
 767          * Spin, waiting for a response from the DO ECHO.  However,
 768          * some REALLY DUMB telnets out there might not respond
 769          * to the DO ECHO.  So, we spin looking for NAWS, (most dumb
 770          * telnets so far seem to respond with WONT for a DO that
 771          * they don't understand...) because by the time we get the
 772          * response, it will already have processed the DO ECHO.
 773          * Kludge upon kludge.
 774          */
 775         while (his_will_wont_is_changing(TELOPT_NAWS))
 776                 ttloop();
 777
 778         /*
 779          * But...
 780          * The client might have sent a WILL NAWS as part of its
 781          * startup code; if so, we'll be here before we get the
 782          * response to the DO ECHO.  We'll make the assumption
 783          * that any implementation that understands about NAWS
 784          * is a modern enough implementation that it will respond
 785          * to our DO ECHO request; hence we'll do another spin
 786          * waiting for the ECHO option to settle down, which is
 787          * what we wanted to do in the first place...
 788          */
 789         if (his_want_state_is_will(TELOPT_ECHO) &&
 790             his_state_is_will(TELOPT_NAWS)) {
 791                 while (his_will_wont_is_changing(TELOPT_ECHO))
 792                         ttloop();
 793         }
 794         /*
 795          * On the off chance that the telnet client is broken and does not
 796          * respond to the DO ECHO we sent, (after all, we did send the
 797          * DO NAWS negotiation after the DO ECHO, and we won't get here
 798          * until a response to the DO NAWS comes back) simulate the
 799          * receipt of a will echo.  This will also send a WONT ECHO
 800          * to the client, since we assume that the client failed to
 801          * respond because it believes that it is already in DO ECHO
 802          * mode, which we do not want.
 803          */
 804         if (his_want_state_is_will(TELOPT_ECHO)) {
 805                 DIAG(TD_OPTIONS, output_data("td: simulating recv\r\n"));
 806                 willoption(TELOPT_ECHO);
 807         }
 808
 809         /*
 810          * Finally, to clean things up, we turn on our echo.  This
 811          * will break stupid 4.2 telnets out of local terminal echo.
 812          */
 813
 814         if (my_state_is_wont(TELOPT_ECHO))
 815                 send_will(TELOPT_ECHO, 1);
 816
 817         /*
 818          * Turn on packet mode
 819          */
 820         (void) ioctl(p, TIOCPKT, (char *)&on);
 821
 822 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 823         /*
 824          * Continuing line mode support.  If client does not support
 825          * real linemode, attempt to negotiate kludge linemode by sending
 826          * the do timing mark sequence.
 827          */
 828         if (lmodetype < REAL_LINEMODE)
 829                 send_do(TELOPT_TM, 1);
 830 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 831
 832         /*
 833          * Call telrcv() once to pick up anything received during
 834          * terminal type negotiation, 4.2/4.3 determination, and
 835          * linemode negotiation.
 836          */
 837         telrcv();
 838
 839         (void) ioctl(f, FIONBIO, (char *)&on);
 840         (void) ioctl(p, FIONBIO, (char *)&on);
 841
 842 #if     defined(SO_OOBINLINE)
 843         (void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE,
 844                                 (char *)&on, sizeof on);
 845 #endif  /* defined(SO_OOBINLINE) */
 846
 847 #ifdef  SIGTSTP
 848         (void) signal(SIGTSTP, SIG_IGN);
 849 #endif
 850 #ifdef  SIGTTOU
 851         /*
 852          * Ignoring SIGTTOU keeps the kernel from blocking us
 853          * in ttioct() in /sys/tty.c.
 854          */
 855         (void) signal(SIGTTOU, SIG_IGN);
 856 #endif
 857
 858         (void) signal(SIGCHLD, cleanup);
 859
 860 #ifdef  TIOCNOTTY
 861         {
 862                 int t;
 863                 t = open(_PATH_TTY, O_RDWR);
 864                 if (t >= 0) {
 865                         (void) ioctl(t, TIOCNOTTY, NULL);
 866                         (void) close(t);
 867                 }
 868         }
 869 #endif
 870
 871         /*
 872          * Show banner that getty never gave.
 873          *
 874          * We put the banner in the pty input buffer.  This way, it
 875          * gets carriage return null processing, etc., just like all
 876          * other pty --> client data.
 877          */
 878
 879         if (getent(defent, "default") == 1) {
 880                 char *cp=defstrs;
 881
 882                 HE = Getstr("he", &cp);
 883                 HN = Getstr("hn", &cp);
 884                 IM = Getstr("im", &cp);
 885                 if (HN && *HN)
 886                         (void) strlcpy(host_name, HN, sizeof(host_name));
 887                 if (IM == NULL)
 888                         IM = strdup("");
 889         } else {
 890                 IM = strdup(DEFAULT_IM);
 891                 HE = NULL;
 892         }
 893         edithost(HE, host_name);
 894         if (hostinfo && *IM)
 895                 putf(IM, ptyibuf2);
 896
 897         if (pcc)
 898                 (void) strncat(ptyibuf2, ptyip, pcc+1);
 899         ptyip = ptyibuf2;
 900         pcc = strlen(ptyip);
 901 #ifdef  LINEMODE
 902         /*
 903          * Last check to make sure all our states are correct.
 904          */
 905         init_termbuf();
 906         localstat();
 907 #endif  /* LINEMODE */
 908
 909         DIAG(TD_REPORT, output_data("td: Entering processing loop\r\n"));
 910
 911         /*
 912          * Startup the login process on the slave side of the terminal
 913          * now.  We delay this until here to insure option negotiation
 914          * is complete.
 915          */
 916         startslave(host, level, user_name);
 917
 918         nfd = ((f > p) ? f : p) + 1;
 919         for (;;) {
 920                 fd_set ibits, obits, xbits;
 921                 int c;
 922
 923                 if (ncc < 0 && pcc < 0)
 924                         break;
 925
 926                 FD_ZERO(&ibits);
 927                 FD_ZERO(&obits);
 928                 FD_ZERO(&xbits);
 929                 /*
 930                  * Never look for input if there's still
 931                  * stuff in the corresponding output buffer
 932                  */
 933                 if (nfrontp - nbackp || pcc > 0) {
 934                         FD_SET(f, &obits);
 935                 } else {
 936                         FD_SET(p, &ibits);
 937                 }
 938                 if (pfrontp - pbackp || ncc > 0) {
 939                         FD_SET(p, &obits);
 940                 } else {
 941                         FD_SET(f, &ibits);
 942                 }
 943                 if (!SYNCHing) {
 944                         FD_SET(f, &xbits);
 945                 }
 946                 if ((c = select(nfd, &ibits, &obits, &xbits, NULL)) < 1) {
 947                         if (c == -1) {
 948                                 if (errno == EINTR) {
 949                                         continue;
 950                                 }
 951                         }
 952                         sleep(5);
 953                         continue;
 954                 }
 955
 956                 /*
 957                  * Any urgent data?
 958                  */
 959                 if (FD_ISSET(net, &xbits)) {
 960                     SYNCHing = 1;
 961                 }
 962
 963                 /*
 964                  * Something to read from the network...
 965                  */
 966                 if (FD_ISSET(net, &ibits)) {
 967 #if     !defined(SO_OOBINLINE)
 968                         /*
 969                          * In 4.2 (and 4.3 beta) systems, the
 970                          * OOB indication and data handling in the kernel
 971                          * is such that if two separate TCP Urgent requests
 972                          * come in, one byte of TCP data will be overlaid.
 973                          * This is fatal for Telnet, but we try to live
 974                          * with it.
 975                          *
 976                          * In addition, in 4.2 (and...), a special protocol
 977                          * is needed to pick up the TCP Urgent data in
 978                          * the correct sequence.
 979                          *
 980                          * What we do is:  if we think we are in urgent
 981                          * mode, we look to see if we are "at the mark".
 982                          * If we are, we do an OOB receive.  If we run
 983                          * this twice, we will do the OOB receive twice,
 984                          * but the second will fail, since the second
 985                          * time we were "at the mark", but there wasn't
 986                          * any data there (the kernel doesn't reset
 987                          * "at the mark" until we do a normal read).
 988                          * Once we've read the OOB data, we go ahead
 989                          * and do normal reads.
 990                          *
 991                          * There is also another problem, which is that
 992                          * since the OOB byte we read doesn't put us
 993                          * out of OOB state, and since that byte is most
 994                          * likely the TELNET DM (data mark), we would
 995                          * stay in the TELNET SYNCH (SYNCHing) state.
 996                          * So, clocks to the rescue.  If we've "just"
 997                          * received a DM, then we test for the
 998                          * presence of OOB data when the receive OOB
 999                          * fails (and AFTER we did the normal mode read
1000                          * to clear "at the mark").
1001                          */
1002                     if (SYNCHing) {
1003                         int atmark;
1004
1005                         (void) ioctl(net, SIOCATMARK, (char *)&atmark);
1006                         if (atmark) {
1007                             ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
1008                             if ((ncc == -1) && (errno == EINVAL)) {
1009                                 ncc = read(net, netibuf, sizeof (netibuf));
1010                                 if (sequenceIs(didnetreceive, gotDM)) {
1011                                     SYNCHing = stilloob(net);
1012                                 }
1013                             }
1014                         } else {
1015                             ncc = read(net, netibuf, sizeof (netibuf));
1016                         }
1017                     } else {
1018                         ncc = read(net, netibuf, sizeof (netibuf));
1019                     }
1020                     settimer(didnetreceive);
1021 #else   /* !defined(SO_OOBINLINE)) */
1022                     ncc = read(net, netibuf, sizeof (netibuf));
1023 #endif  /* !defined(SO_OOBINLINE)) */
1024                     if (ncc < 0 && errno == EWOULDBLOCK)
1025                         ncc = 0;
1026                     else {
1027                         if (ncc <= 0) {
1028                             break;
1029                         }
1030                         netip = netibuf;
1031                     }
1032                     DIAG((TD_REPORT | TD_NETDATA),
1033                         output_data("td: netread %d chars\r\n", ncc));
1034                     DIAG(TD_NETDATA, printdata("nd", netip, ncc));
1035                 }
1036
1037                 /*
1038                  * Something to read from the pty...
1039                  */
1040                 if (FD_ISSET(p, &ibits)) {
1041                         pcc = read(p, ptyibuf, BUFSIZ);
1042                         /*
1043                          * On some systems, if we try to read something
1044                          * off the master side before the slave side is
1045                          * opened, we get EIO.
1046                          */
1047                         if (pcc < 0 && (errno == EWOULDBLOCK ||
1048 #ifdef  EAGAIN
1049                                         errno == EAGAIN ||
1050 #endif
1051                                         errno == EIO)) {
1052                                 pcc = 0;
1053                         } else {
1054                                 if (pcc <= 0)
1055                                         break;
1056 #ifdef  LINEMODE
1057                                 /*
1058                                  * If ioctl from pty, pass it through net
1059                                  */
1060                                 if (ptyibuf[0] & TIOCPKT_IOCTL) {
1061                                         copy_termbuf(ptyibuf+1, pcc-1);
1062                                         localstat();
1063                                         pcc = 1;
1064                                 }
1065 #endif  /* LINEMODE */
1066                                 if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
1067                                         netclear();     /* clear buffer back */
1068 #ifndef NO_URGENT
1069                                         /*
1070                                          * There are client telnets on some
1071                                          * operating systems get screwed up
1072                                          * royally if we send them urgent
1073                                          * mode data.
1074                                          */
1075                                         output_data("%c%c", IAC, DM);
1076                                         neturg = nfrontp-1; /* off by one XXX */
1077                                         DIAG(TD_OPTIONS,
1078                                             printoption("td: send IAC", DM));
1079
1080 #endif
1081                                 }
1082                                 if (his_state_is_will(TELOPT_LFLOW) &&
1083                                     (ptyibuf[0] &
1084                                      (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
1085                                         int newflow =
1086                                             ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
1087                                         if (newflow != flowmode) {
1088                                                 flowmode = newflow;
1089                                                 output_data("%c%c%c%c%c%c",
1090                                                         IAC, SB, TELOPT_LFLOW,
1091                                                         flowmode ? LFLOW_ON
1092                                                                  : LFLOW_OFF,
1093                                                         IAC, SE);
1094                                                 DIAG(TD_OPTIONS, printsub('>',
1095                                                     (unsigned char *)nfrontp-4,
1096                                                     4););
1097                                         }
1098                                 }
1099                                 pcc--;
1100                                 ptyip = ptyibuf+1;
1101                         }
1102                 }
1103
1104                 while (pcc > 0) {
1105                         if ((&netobuf[BUFSIZ] - nfrontp) < 2)
1106                                 break;
1107                         c = *ptyip++ & 0377, pcc--;
1108                         if (c == IAC)
1109                                 output_data("%c", c);
1110                         output_data("%c", c);
1111                         if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
1112                                 if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
1113                                         output_data("%c", *ptyip++ & 0377);
1114                                         pcc--;
1115                                 } else
1116                                         output_data("%c", '\0');
1117                         }
1118                 }
1119
1120                 if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
1121                         netflush();
1122                 if (ncc > 0)
1123                         telrcv();
1124                 if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
1125                         ptyflush();
1126         }
1127         cleanup(0);
1128 }  /* end of telnet */
1129
1130 #ifndef TCSIG
1131 # ifdef TIOCSIG
1132 #  define TCSIG TIOCSIG
1133 # endif
1134 #endif
1135
1136 /*
1137  * Send interrupt to process on other side of pty.
1138  * If it is in raw mode, just write NULL;
1139  * otherwise, write intr char.
1140  */
1141 void
1142 interrupt(void)
1143 {
1144         ptyflush();     /* half-hearted */
1145
1146 #ifdef  TCSIG
1147         (void) ioctl(pty, TCSIG, (char *)SIGINT);
1148 #else   /* TCSIG */
1149         init_termbuf();
1150         *pfrontp++ = slctab[SLC_IP].sptr ?
1151                         (unsigned char)*slctab[SLC_IP].sptr : '\177';
1152 #endif  /* TCSIG */
1153 }
1154
1155 /*
1156  * Send quit to process on other side of pty.
1157  * If it is in raw mode, just write NULL;
1158  * otherwise, write quit char.
1159  */
1160 void
1161 sendbrk(void)
1162 {
1163         ptyflush();     /* half-hearted */
1164 #ifdef  TCSIG
1165         (void) ioctl(pty, TCSIG, (char *)SIGQUIT);
1166 #else   /* TCSIG */
1167         init_termbuf();
1168         *pfrontp++ = slctab[SLC_ABORT].sptr ?
1169                         (unsigned char)*slctab[SLC_ABORT].sptr : '\034';
1170 #endif  /* TCSIG */
1171 }
1172
1173 void
1174 sendsusp(void)
1175 {
1176 #ifdef  SIGTSTP
1177         ptyflush();     /* half-hearted */
1178 # ifdef TCSIG
1179         (void) ioctl(pty, TCSIG, (char *)SIGTSTP);
1180 # else  /* TCSIG */
1181         *pfrontp++ = slctab[SLC_SUSP].sptr ?
1182                         (unsigned char)*slctab[SLC_SUSP].sptr : '\032';
1183 # endif /* TCSIG */
1184 #endif  /* SIGTSTP */
1185 }
1186
1187 /*
1188  * When we get an AYT, if ^T is enabled, use that.  Otherwise,
1189  * just send back "[Yes]".
1190  */
1191 void
1192 recv_ayt(void)
1193 {
1194 #if     defined(SIGINFO) && defined(TCSIG)
1195         if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
1196                 (void) ioctl(pty, TCSIG, (char *)SIGINFO);
1197                 return;
1198         }
1199 #endif
1200         output_data("\r\n[Yes]\r\n");
1201 }
1202
1203 void
1204 doeof(void)
1205 {
1206         init_termbuf();
1207
1208 #if     defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN)
1209         if (!tty_isediting()) {
1210                 extern char oldeofc;
1211                 *pfrontp++ = oldeofc;
1212                 return;
1213         }
1214 #endif
1215         *pfrontp++ = slctab[SLC_EOF].sptr ?
1216                         (unsigned char)*slctab[SLC_EOF].sptr : '\004';
1217 }