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. 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  * @(#)telnetd.c        8.4 (Berkeley) 5/30/95
  34  * $FreeBSD: src/crypto/telnet/telnetd/telnetd.c,v 1.11.2.5 2002/04/13 10:59:09 markm Exp $
  35  * $DragonFly: src/crypto/telnet/telnetd/telnetd.c,v 1.3 2006/01/17 23:50:35 dillon Exp $
  36  */
  37
  38 #include "telnetd.h"
  39 #include "pathnames.h"
  40
  41 #include <sys/mman.h>
  42 #include <err.h>
  43 #include <libutil.h>
  44 #include <paths.h>
  45 #include <termcap.h>
  46 #include <utmp.h>
  47
  48 #include <arpa/inet.h>
  49
  50 #ifdef  AUTHENTICATION
  51 #include <libtelnet/auth.h>
  52 int     auth_level = 0;
  53 #endif
  54 #ifdef  ENCRYPTION
  55 #include <libtelnet/encrypt.h>
  56 #endif
  57 #include <libtelnet/misc.h>
  58
  59 char    remote_hostname[MAXHOSTNAMELEN];
  60 size_t  utmp_len = sizeof(remote_hostname) - 1;
  61 int     registerd_host_only = 0;
  62
  63
  64 /*
  65  * I/O data buffers,
  66  * pointers, and counters.
  67  */
  68 char    ptyibuf[BUFSIZ], *ptyip = ptyibuf;
  69 char    ptyibuf2[BUFSIZ];
  70
  71 int readstream(int, char *, int);
  72 void doit(struct sockaddr *);
  73 int terminaltypeok(char *);
  74
  75 int     hostinfo = 1;                   /* do we print login banner? */
  76
  77 int debug = 0;
  78 int keepalive = 1;
  79 const char *altlogin;
  80
  81 void doit(struct sockaddr *);
  82 int terminaltypeok(char *);
  83 void startslave(char *, int, char *);
  84 extern void usage(void);
  85 static void _gettermname(void);
  86
  87 /*
  88  * The string to pass to getopt().  We do it this way so
  89  * that only the actual options that we support will be
  90  * passed off to getopt().
  91  */
  92 char valid_opts[] = {
  93         'd', ':', 'h', 'k', 'n', 'p', ':', 'S', ':', 'u', ':', 'U',
  94         '4', '6',
  95 #ifdef  AUTHENTICATION
  96         'a', ':', 'X', ':',
  97 #endif
  98 #ifdef BFTPDAEMON
  99         'B',
 100 #endif
 101 #ifdef DIAGNOSTICS
 102         'D', ':',
 103 #endif
 104 #ifdef  ENCRYPTION
 105         'e', ':',
 106 #endif
 107 #ifdef  LINEMODE
 108         'l',
 109 #endif
 110         '\0'
 111 };
 112
 113 int family = AF_INET;
 114
 115 #ifndef MAXHOSTNAMELEN
 116 #define MAXHOSTNAMELEN 256
 117 #endif  /* MAXHOSTNAMELEN */
 118
 119 char *hostname;
 120 char host_name[MAXHOSTNAMELEN];
 121
 122 extern void telnet(int, int, char *);
 123
 124 int level;
 125 char user_name[256];
 126
 127 int
 128 main(int argc, char *argv[])
 129 {
 130         struct sockaddr_storage from;
 131         int on = 1, fromlen;
 132         int ch;
 133 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 134         int tos = -1;
 135 #endif
 136
 137         pfrontp = pbackp = ptyobuf;
 138         netip = netibuf;
 139         nfrontp = nbackp = netobuf;
 140 #ifdef  ENCRYPTION
 141         nclearto = 0;
 142 #endif  /* ENCRYPTION */
 143
 144         /*
 145          * This initialization causes linemode to default to a configuration
 146          * that works on all telnet clients, including the FreeBSD client.
 147          * This is not quite the same as the telnet client issuing a "mode
 148          * character" command, but has most of the same benefits, and is
 149          * preferable since some clients (like usofts) don't have the
 150          * mode character command anyway and linemode breaks things.
 151          * The most notable symptom of fix is that csh "set filec" operations
 152          * like <ESC> (filename completion) and ^D (choices) keys now work
 153          * in telnet sessions and can be used more than once on the same line.
 154          * CR/LF handling is also corrected in some termio modes.  This
 155          * change resolves problem reports bin/771 and bin/1037.
 156          */
 157
 158         linemode=1;     /*Default to mode that works on bulk of clients*/
 159
 160         while ((ch = getopt(argc, argv, valid_opts)) != -1) {
 161                 switch(ch) {
 162
 163 #ifdef  AUTHENTICATION
 164                 case 'a':
 165                         /*
 166                          * Check for required authentication level
 167                          */
 168                         if (strcmp(optarg, "debug") == 0) {
 169                                 extern int auth_debug_mode;
 170                                 auth_debug_mode = 1;
 171                         } else if (strcasecmp(optarg, "none") == 0) {
 172                                 auth_level = 0;
 173                         } else if (strcasecmp(optarg, "other") == 0) {
 174                                 auth_level = AUTH_OTHER;
 175                         } else if (strcasecmp(optarg, "user") == 0) {
 176                                 auth_level = AUTH_USER;
 177                         } else if (strcasecmp(optarg, "valid") == 0) {
 178                                 auth_level = AUTH_VALID;
 179                         } else if (strcasecmp(optarg, "off") == 0) {
 180                                 /*
 181                                  * This hack turns off authentication
 182                                  */
 183                                 auth_level = -1;
 184                         } else {
 185                                 warnx("unknown authorization level for -a");
 186                         }
 187                         break;
 188 #endif  /* AUTHENTICATION */
 189
 190 #ifdef BFTPDAEMON
 191                 case 'B':
 192                         bftpd++;
 193                         break;
 194 #endif /* BFTPDAEMON */
 195
 196                 case 'd':
 197                         if (strcmp(optarg, "ebug") == 0) {
 198                                 debug++;
 199                                 break;
 200                         }
 201                         usage();
 202                         /* NOTREACHED */
 203                         break;
 204
 205 #ifdef DIAGNOSTICS
 206                 case 'D':
 207                         /*
 208                          * Check for desired diagnostics capabilities.
 209                          */
 210                         if (!strcmp(optarg, "report")) {
 211                                 diagnostic |= TD_REPORT|TD_OPTIONS;
 212                         } else if (!strcmp(optarg, "exercise")) {
 213                                 diagnostic |= TD_EXERCISE;
 214                         } else if (!strcmp(optarg, "netdata")) {
 215                                 diagnostic |= TD_NETDATA;
 216                         } else if (!strcmp(optarg, "ptydata")) {
 217                                 diagnostic |= TD_PTYDATA;
 218                         } else if (!strcmp(optarg, "options")) {
 219                                 diagnostic |= TD_OPTIONS;
 220                         } else {
 221                                 usage();
 222                                 /* NOT REACHED */
 223                         }
 224                         break;
 225 #endif /* DIAGNOSTICS */
 226
 227 #ifdef  ENCRYPTION
 228                 case 'e':
 229                         if (strcmp(optarg, "debug") == 0) {
 230                                 extern int encrypt_debug_mode;
 231                                 encrypt_debug_mode = 1;
 232                                 break;
 233                         }
 234                         usage();
 235                         /* NOTREACHED */
 236                         break;
 237 #endif  /* ENCRYPTION */
 238
 239                 case 'h':
 240                         hostinfo = 0;
 241                         break;
 242
 243 #ifdef  LINEMODE
 244                 case 'l':
 245                         alwayslinemode = 1;
 246                         break;
 247 #endif  /* LINEMODE */
 248
 249                 case 'k':
 250 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 251                         lmodetype = NO_AUTOKLUDGE;
 252 #else
 253                         /* ignore -k option if built without kludge linemode */
 254 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 255                         break;
 256
 257                 case 'n':
 258                         keepalive = 0;
 259                         break;
 260
 261                 case 'p':
 262                         altlogin = optarg;
 263                         break;
 264
 265                 case 'S':
 266 #ifdef  HAS_GETTOS
 267                         if ((tos = parsetos(optarg, "tcp")) < 0)
 268                                 warnx("%s%s%s",
 269                                         "bad TOS argument '", optarg,
 270                                         "'; will try to use default TOS");
 271 #else
 272                         warnx("TOS option unavailable; -S flag not supported");
 273 #endif
 274                         break;
 275
 276                 case 'u':
 277                         utmp_len = (size_t)atoi(optarg);
 278                         if (utmp_len >= sizeof(remote_hostname))
 279                                 utmp_len = sizeof(remote_hostname) - 1;
 280                         break;
 281
 282                 case 'U':
 283                         registerd_host_only = 1;
 284                         break;
 285
 286 #ifdef  AUTHENTICATION
 287                 case 'X':
 288                         /*
 289                          * Check for invalid authentication types
 290                          */
 291                         auth_disable_name(optarg);
 292                         break;
 293 #endif  /* AUTHENTICATION */
 294
 295                 case '4':
 296                         family = AF_INET;
 297                         break;
 298
 299 #ifdef INET6
 300                 case '6':
 301                         family = AF_INET6;
 302                         break;
 303 #endif
 304
 305                 default:
 306                         warnx("%c: unknown option", ch);
 307                         /* FALLTHROUGH */
 308                 case '?':
 309                         usage();
 310                         /* NOTREACHED */
 311                 }
 312         }
 313
 314         argc -= optind;
 315         argv += optind;
 316
 317         if (debug) {
 318             int s, ns, foo, error;
 319             const char *service = "telnet";
 320             struct addrinfo hints, *res;
 321
 322             if (argc > 1) {
 323                 usage();
 324                 /* NOT REACHED */
 325             } else if (argc == 1)
 326                 service = *argv;
 327
 328             memset(&hints, 0, sizeof(hints));
 329             hints.ai_flags = AI_PASSIVE;
 330             hints.ai_family = family;
 331             hints.ai_socktype = SOCK_STREAM;
 332             hints.ai_protocol = 0;
 333             error = getaddrinfo(NULL, service, &hints, &res);
 334
 335             if (error) {
 336                 errx(1, "tcp/%s: %s\n", service, gai_strerror(error));
 337                 if (error == EAI_SYSTEM)
 338                     errx(1, "tcp/%s: %s\n", service, strerror(errno));
 339                 usage();
 340             }
 341
 342             s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 343             if (s < 0)
 344                     err(1, "socket");
 345             (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
 346                                 (char *)&on, sizeof(on));
 347             if (bind(s, res->ai_addr, res->ai_addrlen) < 0)
 348                 err(1, "bind");
 349             if (listen(s, 1) < 0)
 350                 err(1, "listen");
 351             foo = res->ai_addrlen;
 352             ns = accept(s, res->ai_addr, &foo);
 353             if (ns < 0)
 354                 err(1, "accept");
 355             (void) dup2(ns, 0);
 356             (void) close(ns);
 357             (void) close(s);
 358 #ifdef convex
 359         } else if (argc == 1) {
 360                 ; /* VOID*/             /* Just ignore the host/port name */
 361 #endif
 362         } else if (argc > 0) {
 363                 usage();
 364                 /* NOT REACHED */
 365         }
 366
 367         openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
 368         fromlen = sizeof (from);
 369         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 370                 warn("getpeername");
 371                 _exit(1);
 372         }
 373         if (keepalive &&
 374             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE,
 375                         (char *)&on, sizeof (on)) < 0) {
 376                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 377         }
 378
 379 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 380         if (from.ss_family == AF_INET) {
 381 # if    defined(HAS_GETTOS)
 382                 struct tosent *tp;
 383                 if (tos < 0 && (tp = gettosbyname("telnet", "tcp")))
 384                         tos = tp->t_tos;
 385 # endif
 386                 if (tos < 0)
 387                         tos = 020;      /* Low Delay bit */
 388                 if (tos
 389                    && (setsockopt(0, IPPROTO_IP, IP_TOS,
 390                                   (char *)&tos, sizeof(tos)) < 0)
 391                    && (errno != ENOPROTOOPT) )
 392                         syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 393         }
 394 #endif  /* defined(IPPROTO_IP) && defined(IP_TOS) */
 395         net = 0;
 396         doit((struct sockaddr *)&from);
 397         /* NOTREACHED */
 398         return(0);
 399 }  /* end of main */
 400
 401         void
 402 usage()
 403 {
 404         fprintf(stderr, "usage: telnetd");
 405 #ifdef  AUTHENTICATION
 406         fprintf(stderr, " [-a (debug|other|user|valid|off|none)]\n\t");
 407 #endif
 408 #ifdef BFTPDAEMON
 409         fprintf(stderr, " [-B]");
 410 #endif
 411         fprintf(stderr, " [-debug]");
 412 #ifdef DIAGNOSTICS
 413         fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t");
 414 #endif
 415 #ifdef  AUTHENTICATION
 416         fprintf(stderr, " [-edebug]");
 417 #endif
 418         fprintf(stderr, " [-h]");
 419 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 420         fprintf(stderr, " [-k]");
 421 #endif
 422 #ifdef LINEMODE
 423         fprintf(stderr, " [-l]");
 424 #endif
 425         fprintf(stderr, " [-n]");
 426         fprintf(stderr, "\n\t");
 427 #ifdef  HAS_GETTOS
 428         fprintf(stderr, " [-S tos]");
 429 #endif
 430 #ifdef  AUTHENTICATION
 431         fprintf(stderr, " [-X auth-type]");
 432 #endif
 433         fprintf(stderr, " [-u utmp_hostname_length] [-U]");
 434         fprintf(stderr, " [port]\n");
 435         exit(1);
 436 }
 437
 438 /*
 439  * getterminaltype
 440  *
 441  *      Ask the other end to send along its terminal type and speed.
 442  * Output is the variable terminaltype filled in.
 443  */
 444 static unsigned char ttytype_sbbuf[] = {
 445         IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
 446 };
 447
 448
 449 #ifndef AUTHENTICATION
 450 #define undef2 __unused
 451 #else
 452 #define undef2
 453 #endif
 454
 455 static int
 456 getterminaltype(char *name undef2)
 457 {
 458     int retval = -1;
 459
 460     settimer(baseline);
 461 #ifdef  AUTHENTICATION
 462     /*
 463      * Handle the Authentication option before we do anything else.
 464      */
 465     send_do(TELOPT_AUTHENTICATION, 1);
 466     while (his_will_wont_is_changing(TELOPT_AUTHENTICATION))
 467         ttloop();
 468     if (his_state_is_will(TELOPT_AUTHENTICATION)) {
 469         retval = auth_wait(name);
 470     }
 471 #endif
 472
 473 #ifdef  ENCRYPTION
 474     send_will(TELOPT_ENCRYPT, 1);
 475 #endif  /* ENCRYPTION */
 476     send_do(TELOPT_TTYPE, 1);
 477     send_do(TELOPT_TSPEED, 1);
 478     send_do(TELOPT_XDISPLOC, 1);
 479     send_do(TELOPT_NEW_ENVIRON, 1);
 480     send_do(TELOPT_OLD_ENVIRON, 1);
 481     while (
 482 #ifdef  ENCRYPTION
 483            his_do_dont_is_changing(TELOPT_ENCRYPT) ||
 484 #endif  /* ENCRYPTION */
 485            his_will_wont_is_changing(TELOPT_TTYPE) ||
 486            his_will_wont_is_changing(TELOPT_TSPEED) ||
 487            his_will_wont_is_changing(TELOPT_XDISPLOC) ||
 488            his_will_wont_is_changing(TELOPT_NEW_ENVIRON) ||
 489            his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) {
 490         ttloop();
 491     }
 492 #ifdef  ENCRYPTION
 493     /*
 494      * Wait for the negotiation of what type of encryption we can
 495      * send with.  If autoencrypt is not set, this will just return.
 496      */
 497     if (his_state_is_will(TELOPT_ENCRYPT)) {
 498         encrypt_wait();
 499     }
 500 #endif  /* ENCRYPTION */
 501     if (his_state_is_will(TELOPT_TSPEED)) {
 502         static unsigned char sb[] =
 503                         { IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE };
 504
 505         output_datalen(sb, sizeof sb);
 506         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 507     }
 508     if (his_state_is_will(TELOPT_XDISPLOC)) {
 509         static unsigned char sb[] =
 510                         { IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE };
 511
 512         output_datalen(sb, sizeof sb);
 513         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 514     }
 515     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 516         static unsigned char sb[] =
 517                         { IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE };
 518
 519         output_datalen(sb, sizeof sb);
 520         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 521     }
 522     else if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 523         static unsigned char sb[] =
 524                         { IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE };
 525
 526         output_datalen(sb, sizeof sb);
 527         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 528     }
 529     if (his_state_is_will(TELOPT_TTYPE)) {
 530
 531         output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 532         DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 533                                         sizeof ttytype_sbbuf - 2););
 534     }
 535     if (his_state_is_will(TELOPT_TSPEED)) {
 536         while (sequenceIs(tspeedsubopt, baseline))
 537             ttloop();
 538     }
 539     if (his_state_is_will(TELOPT_XDISPLOC)) {
 540         while (sequenceIs(xdisplocsubopt, baseline))
 541             ttloop();
 542     }
 543     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 544         while (sequenceIs(environsubopt, baseline))
 545             ttloop();
 546     }
 547     if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 548         while (sequenceIs(oenvironsubopt, baseline))
 549             ttloop();
 550     }
 551     if (his_state_is_will(TELOPT_TTYPE)) {
 552         char first[256], last[256];
 553
 554         while (sequenceIs(ttypesubopt, baseline))
 555             ttloop();
 556
 557         /*
 558          * If the other side has already disabled the option, then
 559          * we have to just go with what we (might) have already gotten.
 560          */
 561         if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
 562             (void) strncpy(first, terminaltype, sizeof(first)-1);
 563             first[sizeof(first)-1] = '\0';
 564             for(;;) {
 565                 /*
 566                  * Save the unknown name, and request the next name.
 567                  */
 568                 (void) strncpy(last, terminaltype, sizeof(last)-1);
 569                 last[sizeof(last)-1] = '\0';
 570                 _gettermname();
 571                 if (terminaltypeok(terminaltype))
 572                     break;
 573                 if ((strncmp(last, terminaltype, sizeof(last)) == 0) ||
 574                     his_state_is_wont(TELOPT_TTYPE)) {
 575                     /*
 576                      * We've hit the end.  If this is the same as
 577                      * the first name, just go with it.
 578                      */
 579                     if (strncmp(first, terminaltype, sizeof(first)) == 0)
 580                         break;
 581                     /*
 582                      * Get the terminal name one more time, so that
 583                      * RFC1091 compliant telnets will cycle back to
 584                      * the start of the list.
 585                      */
 586                      _gettermname();
 587                     if (strncmp(first, terminaltype, sizeof(first)) != 0) {
 588                         (void) strncpy(terminaltype, first, TERMINAL_TYPE_SIZE-1);
 589                         terminaltype[TERMINAL_TYPE_SIZE-1] = '\0';
 590                     }
 591                     break;
 592                 }
 593             }
 594         }
 595     }
 596     return(retval);
 597 }  /* end of getterminaltype */
 598
 599 static void
 600 _gettermname(void)
 601 {
 602     /*
 603      * If the client turned off the option,
 604      * we can't send another request, so we
 605      * just return.
 606      */
 607     if (his_state_is_wont(TELOPT_TTYPE))
 608         return;
 609     settimer(baseline);
 610     output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 611     DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 612                                         sizeof ttytype_sbbuf - 2););
 613     while (sequenceIs(ttypesubopt, baseline))
 614         ttloop();
 615 }
 616
 617 int
 618 terminaltypeok(char *s)
 619 {
 620     char buf[1024];
 621
 622     if (terminaltype == NULL)
 623         return(1);
 624
 625     /*
 626      * tgetent() will return 1 if the type is known, and
 627      * 0 if it is not known.  If it returns -1, it couldn't
 628      * open the database.  But if we can't open the database,
 629      * it won't help to say we failed, because we won't be
 630      * able to verify anything else.  So, we treat -1 like 1.
 631      */
 632     if (tgetent(buf, s) == 0)
 633         return(0);
 634     return(1);
 635 }
 636
 637 /*
 638  * Get a pty, scan input lines.
 639  */
 640 void
 641 doit(struct sockaddr *who)
 642 {
 643         int err_; /* XXX */
 644         int ptynum;
 645
 646         /*
 647          * Find an available pty to use.
 648          */
 649 #ifndef convex
 650         pty = getpty(&ptynum);
 651         if (pty < 0)
 652                 fatal(net, "All network ports in use");
 653 #else
 654         for (;;) {
 655                 char *lp;
 656
 657                 if ((lp = getpty()) == NULL)
 658                         fatal(net, "Out of ptys");
 659
 660                 if ((pty = open(lp, 2)) >= 0) {
 661                         strlcpy(line,lp,sizeof(line));
 662                         line[5] = 't';
 663                         break;
 664                 }
 665         }
 666 #endif
 667
 668         /* get name of connected client */
 669         if (realhostname_sa(remote_hostname, sizeof(remote_hostname) - 1,
 670             who, who->sa_len) == HOSTNAME_INVALIDADDR && registerd_host_only)
 671                 fatal(net, "Couldn't resolve your address into a host name.\r\n\
 672         Please contact your net administrator");
 673         remote_hostname[sizeof(remote_hostname) - 1] = '\0';
 674
 675         trimdomain(remote_hostname, UT_HOSTSIZE);
 676         if (!isdigit(remote_hostname[0]) && strlen(remote_hostname) > utmp_len)
 677                 err_ = getnameinfo(who, who->sa_len, remote_hostname,
 678                                   sizeof(remote_hostname), NULL, 0,
 679                                   NI_NUMERICHOST|NI_WITHSCOPEID);
 680                 /* XXX: do 'err_' check */
 681
 682         (void) gethostname(host_name, sizeof(host_name) - 1);
 683         host_name[sizeof(host_name) - 1] = '\0';
 684         hostname = host_name;
 685
 686 #ifdef  AUTHENTICATION
 687 #ifdef  ENCRYPTION
 688 /* The above #ifdefs should actually be "or"'ed, not "and"'ed.
 689  * This is a byproduct of needing "#ifdef" and not "#if defined()"
 690  * for unifdef. XXX MarkM
 691  */
 692         auth_encrypt_init(hostname, remote_hostname, "TELNETD", 1);
 693 #endif
 694 #endif
 695
 696         init_env();
 697         /*
 698          * get terminal type.
 699          */
 700         *user_name = 0;
 701         level = getterminaltype(user_name);
 702         if (setenv("TERM", terminaltype ? terminaltype : "network", 1) == -1)
 703                 syslog(LOG_ERR, "setenv: cannot set TERM=%s: %m", terminaltype ? terminaltype : "network");
 704
 705         telnet(net, pty, remote_hostname);      /* begin server process */
 706
 707         /*NOTREACHED*/
 708 }  /* end of doit */
 709
 710 /*
 711  * Main loop.  Select from pty and network, and
 712  * hand data to telnet receiver finite state machine.
 713  */
 714 void
 715 telnet(int f, int p, char *host)
 716 {
 717         int on = 1;
 718 #define TABBUFSIZ       512
 719         char    defent[TABBUFSIZ];
 720         char    defstrs[TABBUFSIZ];
 721 #undef  TABBUFSIZ
 722         char *HE;
 723         char *HN;
 724         char *IM;
 725         int nfd;
 726
 727         /*
 728          * Initialize the slc mapping table.
 729          */
 730         get_slc_defaults();
 731
 732         /*
 733          * Do some tests where it is desireable to wait for a response.
 734          * Rather than doing them slowly, one at a time, do them all
 735          * at once.
 736          */
 737         if (my_state_is_wont(TELOPT_SGA))
 738                 send_will(TELOPT_SGA, 1);
 739         /*
 740          * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
 741          * because 4.2 clients are unable to deal with TCP urgent data.
 742          *
 743          * To find out, we send out a "DO ECHO".  If the remote system
 744          * answers "WILL ECHO" it is probably a 4.2 client, and we note
 745          * that fact ("WILL ECHO" ==> that the client will echo what
 746          * WE, the server, sends it; it does NOT mean that the client will
 747          * echo the terminal input).
 748          */
 749         send_do(TELOPT_ECHO, 1);
 750
 751 #ifdef  LINEMODE
 752         if (his_state_is_wont(TELOPT_LINEMODE)) {
 753                 /* Query the peer for linemode support by trying to negotiate
 754                  * the linemode option.
 755                  */
 756                 linemode = 0;
 757                 editmode = 0;
 758                 send_do(TELOPT_LINEMODE, 1);  /* send do linemode */
 759         }
 760 #endif  /* LINEMODE */
 761
 762         /*
 763          * Send along a couple of other options that we wish to negotiate.
 764          */
 765         send_do(TELOPT_NAWS, 1);
 766         send_will(TELOPT_STATUS, 1);
 767         flowmode = 1;           /* default flow control state */
 768         restartany = -1;        /* uninitialized... */
 769         send_do(TELOPT_LFLOW, 1);
 770
 771         /*
 772          * Spin, waiting for a response from the DO ECHO.  However,
 773          * some REALLY DUMB telnets out there might not respond
 774          * to the DO ECHO.  So, we spin looking for NAWS, (most dumb
 775          * telnets so far seem to respond with WONT for a DO that
 776          * they don't understand...) because by the time we get the
 777          * response, it will already have processed the DO ECHO.
 778          * Kludge upon kludge.
 779          */
 780         while (his_will_wont_is_changing(TELOPT_NAWS))
 781                 ttloop();
 782
 783         /*
 784          * But...
 785          * The client might have sent a WILL NAWS as part of its
 786          * startup code; if so, we'll be here before we get the
 787          * response to the DO ECHO.  We'll make the assumption
 788          * that any implementation that understands about NAWS
 789          * is a modern enough implementation that it will respond
 790          * to our DO ECHO request; hence we'll do another spin
 791          * waiting for the ECHO option to settle down, which is
 792          * what we wanted to do in the first place...
 793          */
 794         if (his_want_state_is_will(TELOPT_ECHO) &&
 795             his_state_is_will(TELOPT_NAWS)) {
 796                 while (his_will_wont_is_changing(TELOPT_ECHO))
 797                         ttloop();
 798         }
 799         /*
 800          * On the off chance that the telnet client is broken and does not
 801          * respond to the DO ECHO we sent, (after all, we did send the
 802          * DO NAWS negotiation after the DO ECHO, and we won't get here
 803          * until a response to the DO NAWS comes back) simulate the
 804          * receipt of a will echo.  This will also send a WONT ECHO
 805          * to the client, since we assume that the client failed to
 806          * respond because it believes that it is already in DO ECHO
 807          * mode, which we do not want.
 808          */
 809         if (his_want_state_is_will(TELOPT_ECHO)) {
 810                 DIAG(TD_OPTIONS, output_data("td: simulating recv\r\n"));
 811                 willoption(TELOPT_ECHO);
 812         }
 813
 814         /*
 815          * Finally, to clean things up, we turn on our echo.  This
 816          * will break stupid 4.2 telnets out of local terminal echo.
 817          */
 818
 819         if (my_state_is_wont(TELOPT_ECHO))
 820                 send_will(TELOPT_ECHO, 1);
 821
 822         /*
 823          * Turn on packet mode
 824          */
 825         (void) ioctl(p, TIOCPKT, (char *)&on);
 826
 827 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 828         /*
 829          * Continuing line mode support.  If client does not support
 830          * real linemode, attempt to negotiate kludge linemode by sending
 831          * the do timing mark sequence.
 832          */
 833         if (lmodetype < REAL_LINEMODE)
 834                 send_do(TELOPT_TM, 1);
 835 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 836
 837         /*
 838          * Call telrcv() once to pick up anything received during
 839          * terminal type negotiation, 4.2/4.3 determination, and
 840          * linemode negotiation.
 841          */
 842         telrcv();
 843
 844         (void) ioctl(f, FIONBIO, (char *)&on);
 845         (void) ioctl(p, FIONBIO, (char *)&on);
 846
 847 #if     defined(SO_OOBINLINE)
 848         (void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE,
 849                                 (char *)&on, sizeof on);
 850 #endif  /* defined(SO_OOBINLINE) */
 851
 852 #ifdef  SIGTSTP
 853         (void) signal(SIGTSTP, SIG_IGN);
 854 #endif
 855 #ifdef  SIGTTOU
 856         /*
 857          * Ignoring SIGTTOU keeps the kernel from blocking us
 858          * in ttioct() in /sys/tty.c.
 859          */
 860         (void) signal(SIGTTOU, SIG_IGN);
 861 #endif
 862
 863         (void) signal(SIGCHLD, cleanup);
 864
 865 #ifdef  TIOCNOTTY
 866         {
 867                 int t;
 868                 t = open(_PATH_TTY, O_RDWR);
 869                 if (t >= 0) {
 870                         (void) ioctl(t, TIOCNOTTY, NULL);
 871                         (void) close(t);
 872                 }
 873         }
 874 #endif
 875
 876         /*
 877          * Show banner that getty never gave.
 878          *
 879          * We put the banner in the pty input buffer.  This way, it
 880          * gets carriage return null processing, etc., just like all
 881          * other pty --> client data.
 882          */
 883
 884         if (getent(defent, "default") == 1) {
 885                 char *cp=defstrs;
 886
 887                 HE = Getstr("he", &cp);
 888                 HN = Getstr("hn", &cp);
 889                 IM = Getstr("im", &cp);
 890                 if (HN && *HN)
 891                         (void) strlcpy(host_name, HN, sizeof(host_name));
 892                 if (IM == 0)
 893                         IM = strdup("");
 894         } else {
 895                 IM = strdup(DEFAULT_IM);
 896                 HE = 0;
 897         }
 898         edithost(HE, host_name);
 899         if (hostinfo && *IM)
 900                 putf(IM, ptyibuf2);
 901
 902         if (pcc)
 903                 (void) strncat(ptyibuf2, ptyip, pcc+1);
 904         ptyip = ptyibuf2;
 905         pcc = strlen(ptyip);
 906 #ifdef  LINEMODE
 907         /*
 908          * Last check to make sure all our states are correct.
 909          */
 910         init_termbuf();
 911         localstat();
 912 #endif  /* LINEMODE */
 913
 914         DIAG(TD_REPORT, output_data("td: Entering processing loop\r\n"));
 915
 916         /*
 917          * Startup the login process on the slave side of the terminal
 918          * now.  We delay this until here to insure option negotiation
 919          * is complete.
 920          */
 921         startslave(host, level, user_name);
 922
 923         nfd = ((f > p) ? f : p) + 1;
 924         for (;;) {
 925                 fd_set ibits, obits, xbits;
 926                 int c;
 927
 928                 if (ncc < 0 && pcc < 0)
 929                         break;
 930
 931                 FD_ZERO(&ibits);
 932                 FD_ZERO(&obits);
 933                 FD_ZERO(&xbits);
 934                 /*
 935                  * Never look for input if there's still
 936                  * stuff in the corresponding output buffer
 937                  */
 938                 if (nfrontp - nbackp || pcc > 0) {
 939                         FD_SET(f, &obits);
 940                 } else {
 941                         FD_SET(p, &ibits);
 942                 }
 943                 if (pfrontp - pbackp || ncc > 0) {
 944                         FD_SET(p, &obits);
 945                 } else {
 946                         FD_SET(f, &ibits);
 947                 }
 948                 if (!SYNCHing) {
 949                         FD_SET(f, &xbits);
 950                 }
 951                 if ((c = select(nfd, &ibits, &obits, &xbits, NULL)) < 1) {
 952                         if (c == -1) {
 953                                 if (errno == EINTR) {
 954                                         continue;
 955                                 }
 956                         }
 957                         sleep(5);
 958                         continue;
 959                 }
 960
 961                 /*
 962                  * Any urgent data?
 963                  */
 964                 if (FD_ISSET(net, &xbits)) {
 965                     SYNCHing = 1;
 966                 }
 967
 968                 /*
 969                  * Something to read from the network...
 970                  */
 971                 if (FD_ISSET(net, &ibits)) {
 972 #if     !defined(SO_OOBINLINE)
 973                         /*
 974                          * In 4.2 (and 4.3 beta) systems, the
 975                          * OOB indication and data handling in the kernel
 976                          * is such that if two separate TCP Urgent requests
 977                          * come in, one byte of TCP data will be overlaid.
 978                          * This is fatal for Telnet, but we try to live
 979                          * with it.
 980                          *
 981                          * In addition, in 4.2 (and...), a special protocol
 982                          * is needed to pick up the TCP Urgent data in
 983                          * the correct sequence.
 984                          *
 985                          * What we do is:  if we think we are in urgent
 986                          * mode, we look to see if we are "at the mark".
 987                          * If we are, we do an OOB receive.  If we run
 988                          * this twice, we will do the OOB receive twice,
 989                          * but the second will fail, since the second
 990                          * time we were "at the mark", but there wasn't
 991                          * any data there (the kernel doesn't reset
 992                          * "at the mark" until we do a normal read).
 993                          * Once we've read the OOB data, we go ahead
 994                          * and do normal reads.
 995                          *
 996                          * There is also another problem, which is that
 997                          * since the OOB byte we read doesn't put us
 998                          * out of OOB state, and since that byte is most
 999                          * likely the TELNET DM (data mark), we would
1000                          * stay in the TELNET SYNCH (SYNCHing) state.
1001                          * So, clocks to the rescue.  If we've "just"
1002                          * received a DM, then we test for the
1003                          * presence of OOB data when the receive OOB
1004                          * fails (and AFTER we did the normal mode read
1005                          * to clear "at the mark").
1006                          */
1007                     if (SYNCHing) {
1008                         int atmark;
1009
1010                         (void) ioctl(net, SIOCATMARK, (char *)&atmark);
1011                         if (atmark) {
1012                             ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
1013                             if ((ncc == -1) && (errno == EINVAL)) {
1014                                 ncc = read(net, netibuf, sizeof (netibuf));
1015                                 if (sequenceIs(didnetreceive, gotDM)) {
1016                                     SYNCHing = stilloob(net);
1017                                 }
1018                             }
1019                         } else {
1020                             ncc = read(net, netibuf, sizeof (netibuf));
1021                         }
1022                     } else {
1023                         ncc = read(net, netibuf, sizeof (netibuf));
1024                     }
1025                     settimer(didnetreceive);
1026 #else   /* !defined(SO_OOBINLINE)) */
1027                     ncc = read(net, netibuf, sizeof (netibuf));
1028 #endif  /* !defined(SO_OOBINLINE)) */
1029                     if (ncc < 0 && errno == EWOULDBLOCK)
1030                         ncc = 0;
1031                     else {
1032                         if (ncc <= 0) {
1033                             break;
1034                         }
1035                         netip = netibuf;
1036                     }
1037                     DIAG((TD_REPORT | TD_NETDATA),
1038                         output_data("td: netread %d chars\r\n", ncc));
1039                     DIAG(TD_NETDATA, printdata("nd", netip, ncc));
1040                 }
1041
1042                 /*
1043                  * Something to read from the pty...
1044                  */
1045                 if (FD_ISSET(p, &ibits)) {
1046                         pcc = read(p, ptyibuf, BUFSIZ);
1047                         /*
1048                          * On some systems, if we try to read something
1049                          * off the master side before the slave side is
1050                          * opened, we get EIO.
1051                          */
1052                         if (pcc < 0 && (errno == EWOULDBLOCK ||
1053 #ifdef  EAGAIN
1054                                         errno == EAGAIN ||
1055 #endif
1056                                         errno == EIO)) {
1057                                 pcc = 0;
1058                         } else {
1059                                 if (pcc <= 0)
1060                                         break;
1061 #ifdef  LINEMODE
1062                                 /*
1063                                  * If ioctl from pty, pass it through net
1064                                  */
1065                                 if (ptyibuf[0] & TIOCPKT_IOCTL) {
1066                                         copy_termbuf(ptyibuf+1, pcc-1);
1067                                         localstat();
1068                                         pcc = 1;
1069                                 }
1070 #endif  /* LINEMODE */
1071                                 if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
1072                                         netclear();     /* clear buffer back */
1073 #ifndef NO_URGENT
1074                                         /*
1075                                          * There are client telnets on some
1076                                          * operating systems get screwed up
1077                                          * royally if we send them urgent
1078                                          * mode data.
1079                                          */
1080                                         output_data("%c%c", IAC, DM);
1081                                         neturg = nfrontp-1; /* off by one XXX */
1082                                         DIAG(TD_OPTIONS,
1083                                             printoption("td: send IAC", DM));
1084
1085 #endif
1086                                 }
1087                                 if (his_state_is_will(TELOPT_LFLOW) &&
1088                                     (ptyibuf[0] &
1089                                      (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
1090                                         int newflow =
1091                                             ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
1092                                         if (newflow != flowmode) {
1093                                                 flowmode = newflow;
1094                                                 output_data("%c%c%c%c%c%c",
1095                                                         IAC, SB, TELOPT_LFLOW,
1096                                                         flowmode ? LFLOW_ON
1097                                                                  : LFLOW_OFF,
1098                                                         IAC, SE);
1099                                                 DIAG(TD_OPTIONS, printsub('>',
1100                                                     (unsigned char *)nfrontp-4,
1101                                                     4););
1102                                         }
1103                                 }
1104                                 pcc--;
1105                                 ptyip = ptyibuf+1;
1106                         }
1107                 }
1108
1109                 while (pcc > 0) {
1110                         if ((&netobuf[BUFSIZ] - nfrontp) < 2)
1111                                 break;
1112                         c = *ptyip++ & 0377, pcc--;
1113                         if (c == IAC)
1114                                 output_data("%c", c);
1115                         output_data("%c", c);
1116                         if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
1117                                 if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
1118                                         output_data("%c", *ptyip++ & 0377);
1119                                         pcc--;
1120                                 } else
1121                                         output_data("%c", '\0');
1122                         }
1123                 }
1124
1125                 if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
1126                         netflush();
1127                 if (ncc > 0)
1128                         telrcv();
1129                 if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
1130                         ptyflush();
1131         }
1132         cleanup(0);
1133 }  /* end of telnet */
1134
1135 #ifndef TCSIG
1136 # ifdef TIOCSIG
1137 #  define TCSIG TIOCSIG
1138 # endif
1139 #endif
1140
1141 /*
1142  * Send interrupt to process on other side of pty.
1143  * If it is in raw mode, just write NULL;
1144  * otherwise, write intr char.
1145  */
1146 void
1147 interrupt(void)
1148 {
1149         ptyflush();     /* half-hearted */
1150
1151 #ifdef  TCSIG
1152         (void) ioctl(pty, TCSIG, (char *)SIGINT);
1153 #else   /* TCSIG */
1154         init_termbuf();
1155         *pfrontp++ = slctab[SLC_IP].sptr ?
1156                         (unsigned char)*slctab[SLC_IP].sptr : '\177';
1157 #endif  /* TCSIG */
1158 }
1159
1160 /*
1161  * Send quit to process on other side of pty.
1162  * If it is in raw mode, just write NULL;
1163  * otherwise, write quit char.
1164  */
1165 void
1166 sendbrk(void)
1167 {
1168         ptyflush();     /* half-hearted */
1169 #ifdef  TCSIG
1170         (void) ioctl(pty, TCSIG, (char *)SIGQUIT);
1171 #else   /* TCSIG */
1172         init_termbuf();
1173         *pfrontp++ = slctab[SLC_ABORT].sptr ?
1174                         (unsigned char)*slctab[SLC_ABORT].sptr : '\034';
1175 #endif  /* TCSIG */
1176 }
1177
1178 void
1179 sendsusp(void)
1180 {
1181 #ifdef  SIGTSTP
1182         ptyflush();     /* half-hearted */
1183 # ifdef TCSIG
1184         (void) ioctl(pty, TCSIG, (char *)SIGTSTP);
1185 # else  /* TCSIG */
1186         *pfrontp++ = slctab[SLC_SUSP].sptr ?
1187                         (unsigned char)*slctab[SLC_SUSP].sptr : '\032';
1188 # endif /* TCSIG */
1189 #endif  /* SIGTSTP */
1190 }
1191
1192 /*
1193  * When we get an AYT, if ^T is enabled, use that.  Otherwise,
1194  * just send back "[Yes]".
1195  */
1196 void
1197 recv_ayt(void)
1198 {
1199 #if     defined(SIGINFO) && defined(TCSIG)
1200         if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
1201                 (void) ioctl(pty, TCSIG, (char *)SIGINFO);
1202                 return;
1203         }
1204 #endif
1205         output_data("\r\n[Yes]\r\n");
1206 }
1207
1208 void
1209 doeof(void)
1210 {
1211         init_termbuf();
1212
1213 #if     defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN)
1214         if (!tty_isediting()) {
1215                 extern char oldeofc;
1216                 *pfrontp++ = oldeofc;
1217                 return;
1218         }
1219 #endif
1220         *pfrontp++ = slctab[SLC_EOF].sptr ?
1221                         (unsigned char)*slctab[SLC_EOF].sptr : '\004';
1222 }