libexec/telnetd/telnetd.c

   1 /*      $NetBSD: telnetd.c,v 1.50 2006/05/09 20:18:07 mrg Exp $ */
   2
   3 /*
   4  * Copyright (C) 1997 and 1998 WIDE Project.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the project nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * Copyright (c) 1989, 1993
  34  *      The Regents of the University of California.  All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions
  38  * are met:
  39  * 1. Redistributions of source code must retain the above copyright
  40  *    notice, this list of conditions and the following disclaimer.
  41  * 2. Redistributions in binary form must reproduce the above copyright
  42  *    notice, this list of conditions and the following disclaimer in the
  43  *    documentation and/or other materials provided with the distribution.
  44  * 3. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61 #include <sys/cdefs.h>
  62 #ifndef lint
  63 __COPYRIGHT("@(#) Copyright (c) 1989, 1993\
  64  The Regents of the University of California.  All rights reserved.");
  65 #if 0
  66 static char sccsid[] = "@(#)telnetd.c   8.4 (Berkeley) 5/30/95";
  67 #else
  68 __RCSID("$NetBSD: telnetd.c,v 1.50 2006/05/09 20:18:07 mrg Exp $");
  69 #endif
  70 #endif /* not lint */
  71
  72 #include "telnetd.h"
  73 #include "pathnames.h"
  74
  75 #include <arpa/inet.h>
  76
  77 #include <err.h>
  78 #include <termcap.h>
  79
  80 #include <limits.h>
  81
  82 #ifdef KRB5
  83 #define Authenticator   k5_Authenticator
  84 #include <krb5.h>
  85 #undef  Authenticator
  86 #include <com_err.h>
  87 #endif
  88
  89 #ifdef AUTHENTICATION
  90 int     auth_level = 0;
  91 #endif
  92
  93 #if     defined(AUTHENTICATION) || defined(ENCRYPTION)
  94 #include <libtelnet/misc.h>
  95 #endif
  96
  97 #ifdef SECURELOGIN
  98 int     require_secure_login = 0;
  99 #endif
 100
 101 extern int require_hwpreauth;
 102 #ifdef KRB5
 103 extern krb5_context telnet_context;
 104 #endif
 105 int     registerd_host_only = 0;
 106
 107
 108 /*
 109  * I/O data buffers,
 110  * pointers, and counters.
 111  */
 112 char    ptyibuf[BUFSIZ], *ptyip = ptyibuf;
 113 char    ptyibuf2[BUFSIZ];
 114
 115
 116 int     hostinfo = 1;                   /* do we print login banner? */
 117
 118
 119 static int debug = 0;
 120 int keepalive = 1;
 121 char *gettyname = "default";
 122 char *progname;
 123
 124 int main(int, char *[]);
 125 void usage(void);
 126 int getterminaltype(char *, size_t);
 127 int getent(char *, char *);
 128 void doit(struct sockaddr *);
 129 void _gettermname(void);
 130 int terminaltypeok(char *);
 131 char *getstr(const char *, char **);
 132
 133 /*
 134  * The string to pass to getopt().  We do it this way so
 135  * that only the actual options that we support will be
 136  * passed off to getopt().
 137  */
 138 char valid_opts[] = {
 139         'd', ':', 'g', ':', 'h', 'k', 'n', 'S', ':', 'u', ':', 'U',
 140         '4', '6',
 141 #ifdef  AUTHENTICATION
 142         'a', ':', 'X', ':',
 143 #endif
 144 #ifdef  ENCRYPTION
 145         'e', ':',
 146 #endif
 147 #ifdef DIAGNOSTICS
 148         'D', ':',
 149 #endif
 150 #ifdef  LINEMODE
 151         'l',
 152 #endif
 153 #ifdef  SECURELOGIN
 154         's',
 155 #endif
 156 #ifdef  KRB5
 157         'R', ':', 'H',
 158 #endif
 159         '\0'
 160 };
 161
 162 int family = AF_INET;
 163 struct sockaddr_storage from;
 164
 165 int
 166 main(int argc, char *argv[])
 167 {
 168         socklen_t fromlen;
 169         int on = 1;
 170         int ch;
 171 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 172         int tos = -1;
 173 #endif
 174
 175         pfrontp = pbackp = ptyobuf;
 176         netip = netibuf;
 177         nfrontp = nbackp = netobuf;
 178 #ifdef  ENCRYPTION
 179         nclearto = 0;
 180 #endif  /* ENCRYPTION */
 181
 182         progname = *argv;
 183
 184
 185         while ((ch = getopt(argc, argv, valid_opts)) != -1) {
 186                 switch (ch) {
 187
 188 #ifdef  AUTHENTICATION
 189                 case 'a':
 190                         /*
 191                          * Check for required authentication level
 192                          */
 193                         if (strcmp(optarg, "debug") == 0) {
 194                                 auth_debug_mode = 1;
 195                         } else if (strcasecmp(optarg, "none") == 0) {
 196                                 auth_level = 0;
 197                         } else if (strcasecmp(optarg, "other") == 0) {
 198                                 auth_level = AUTH_OTHER;
 199                         } else if (strcasecmp(optarg, "user") == 0) {
 200                                 auth_level = AUTH_USER;
 201                         } else if (strcasecmp(optarg, "valid") == 0) {
 202                                 auth_level = AUTH_VALID;
 203                         } else if (strcasecmp(optarg, "off") == 0) {
 204                                 /*
 205                                  * This hack turns off authentication
 206                                  */
 207                                 auth_level = -1;
 208                         } else {
 209                                 fprintf(stderr,
 210                             "telnetd: unknown authorization level for -a\n");
 211                         }
 212                         break;
 213 #endif  /* AUTHENTICATION */
 214
 215
 216                 case 'd':
 217                         if (strcmp(optarg, "ebug") == 0) {
 218                                 debug++;
 219                                 break;
 220                         }
 221                         usage();
 222                         /* NOTREACHED */
 223                         break;
 224
 225 #ifdef DIAGNOSTICS
 226                 case 'D':
 227                         /*
 228                          * Check for desired diagnostics capabilities.
 229                          */
 230                         if (!strcmp(optarg, "report")) {
 231                                 diagnostic |= TD_REPORT|TD_OPTIONS;
 232                         } else if (!strcmp(optarg, "exercise")) {
 233                                 diagnostic |= TD_EXERCISE;
 234                         } else if (!strcmp(optarg, "netdata")) {
 235                                 diagnostic |= TD_NETDATA;
 236                         } else if (!strcmp(optarg, "ptydata")) {
 237                                 diagnostic |= TD_PTYDATA;
 238                         } else if (!strcmp(optarg, "options")) {
 239                                 diagnostic |= TD_OPTIONS;
 240                         } else {
 241                                 usage();
 242                                 /* NOT REACHED */
 243                         }
 244                         break;
 245 #endif /* DIAGNOSTICS */
 246
 247 #ifdef  ENCRYPTION
 248                 case 'e':
 249                         if (strcmp(optarg, "debug") == 0) {
 250                                 encrypt_debug_mode = 1;
 251                                 break;
 252                         }
 253                         usage();
 254                         /* NOTREACHED */
 255                         break;
 256 #endif  /* ENCRYPTION */
 257
 258                 case 'g':
 259                         gettyname = optarg;
 260                         break;
 261
 262                 case 'h':
 263                         hostinfo = 0;
 264                         break;
 265
 266 #ifdef  KRB5
 267                 case 'H':
 268                     {
 269                         require_hwpreauth = 1;
 270                         break;
 271                     }
 272 #endif  /* KRB5 */
 273
 274
 275 #ifdef  LINEMODE
 276                 case 'l':
 277                         alwayslinemode = 1;
 278                         break;
 279 #endif  /* LINEMODE */
 280
 281                 case 'k':
 282 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 283                         lmodetype = NO_AUTOKLUDGE;
 284 #else
 285                         /* ignore -k option if built without kludge linemode */
 286 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 287                         break;
 288
 289                 case 'n':
 290                         keepalive = 0;
 291                         break;
 292
 293
 294 #ifdef  KRB5
 295                 case 'R':
 296                     {
 297                         krb5_error_code retval;
 298
 299                         if (telnet_context == 0) {
 300                                 retval = krb5_init_context(&telnet_context);
 301                                 if (retval) {
 302                                         com_err("telnetd", retval,
 303                                             "while initializing krb5");
 304                                         exit(1);
 305                                 }
 306                         }
 307                         krb5_set_default_realm(telnet_context, optarg);
 308                         break;
 309                     }
 310 #endif  /* KRB5 */
 311
 312 #ifdef  SECURELOGIN
 313                 case 's':
 314                         /* Secure login required */
 315                         require_secure_login = 1;
 316                         break;
 317 #endif  /* SECURELOGIN */
 318                 case 'S':
 319                         fprintf(stderr, "%s%s\n", "TOS option unavailable; ",
 320                                                 "-S flag not supported\n");
 321                         break;
 322
 323                 case 'u':
 324                         fprintf(stderr, "telnetd: -u option unneeded\n");
 325                         break;
 326
 327                 case 'U':
 328                         registerd_host_only = 1;
 329                         break;
 330
 331 #ifdef  AUTHENTICATION
 332                 case 'X':
 333                         /*
 334                          * Check for invalid authentication types
 335                          */
 336                         auth_disable_name(optarg);
 337                         break;
 338 #endif  /* AUTHENTICATION */
 339
 340                 case '4':
 341                         family = AF_INET;
 342                         break;
 343
 344                 case '6':
 345                         family = AF_INET6;
 346                         break;
 347
 348                 default:
 349                         fprintf(stderr, "telnetd: %c: unknown option\n", ch);
 350                         /* FALLTHROUGH */
 351                 case '?':
 352                         usage();
 353                         /* NOTREACHED */
 354                 }
 355         }
 356
 357         argc -= optind;
 358         argv += optind;
 359
 360         if (debug) {
 361             int s, ns, error;
 362             socklen_t foo;
 363             char *service = "telnet";
 364             struct addrinfo hints, *res;
 365
 366             if (argc > 1) {
 367                 usage();
 368                 /* NOT REACHED */
 369             } else if (argc == 1)
 370                 service = *argv;
 371
 372             memset(&hints, 0, sizeof(hints));
 373             hints.ai_flags = AI_PASSIVE;
 374             hints.ai_family = family;
 375             hints.ai_socktype = SOCK_STREAM;
 376             hints.ai_protocol = 0;
 377             error = getaddrinfo(NULL, service, &hints, &res);
 378
 379             if (error) {
 380                 fprintf(stderr, "tcp/%s: %s\n", service, gai_strerror(error));
 381                 exit(1);
 382             }
 383
 384             s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 385             if (s < 0) {
 386                 perror("telnetd: socket");
 387                 exit(1);
 388             }
 389             (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
 390                                 (char *)&on, sizeof(on));
 391             if (bind(s, res->ai_addr, res->ai_addrlen) < 0) {
 392                 perror("bind");
 393                 exit(1);
 394             }
 395             if (listen(s, 1) < 0) {
 396                 perror("listen");
 397                 exit(1);
 398             }
 399             foo = res->ai_addrlen;
 400             ns = accept(s, res->ai_addr, &foo);
 401             if (ns < 0) {
 402                 perror("accept");
 403                 exit(1);
 404             }
 405             (void) dup2(ns, 0);
 406             (void) close(ns);
 407             (void) close(s);
 408         } else if (argc > 0) {
 409                 usage();
 410                 /* NOT REACHED */
 411         }
 412
 413         openlog("telnetd", LOG_PID, LOG_DAEMON);
 414         fromlen = sizeof (from);
 415         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 416                 fprintf(stderr, "%s: ", progname);
 417                 perror("getpeername");
 418                 _exit(1);
 419         }
 420         if (keepalive &&
 421             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE,
 422                         (char *)&on, sizeof (on)) < 0) {
 423                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 424         }
 425
 426 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 427         if (((struct sockaddr *)&from)->sa_family == AF_INET) {
 428                 if (tos < 0)
 429                         tos = 020;      /* Low Delay bit */
 430                 if (tos
 431                    && (setsockopt(0, IPPROTO_IP, IP_TOS,
 432                                   (char *)&tos, sizeof(tos)) < 0)
 433                    && (errno != ENOPROTOOPT) )
 434                         syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 435         }
 436 #endif  /* defined(IPPROTO_IP) && defined(IP_TOS) */
 437
 438         net = 0;
 439         doit((struct sockaddr *)&from);
 440         /* NOTREACHED */
 441 #ifdef __GNUC__
 442         exit(0);
 443 #endif
 444 }  /* end of main */
 445
 446 void
 447 usage(void)
 448 {
 449         fprintf(stderr, "Usage: telnetd");
 450 #ifdef  AUTHENTICATION
 451         fprintf(stderr, " [-a (debug|other|user|valid|off|none)]\n\t");
 452 #endif
 453         fprintf(stderr, " [-debug]");
 454 #ifdef DIAGNOSTICS
 455         fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t");
 456 #endif
 457 #ifdef  ENCRYPTION
 458         fprintf(stderr, " [-edebug]");
 459 #endif
 460         fprintf(stderr, " [-h]");
 461 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 462         fprintf(stderr, " [-k]");
 463 #endif
 464 #ifdef LINEMODE
 465         fprintf(stderr, " [-l]");
 466 #endif
 467         fprintf(stderr, " [-n]");
 468         fprintf(stderr, "\n\t");
 469 #ifdef  SECURELOGIN
 470         fprintf(stderr, " [-s]");
 471 #endif
 472 #ifdef  AUTHENTICATION
 473         fprintf(stderr, " [-X auth-type]");
 474 #endif
 475         fprintf(stderr, " [-u utmp_hostname_length] [-U]");
 476         fprintf(stderr, " [port]\n");
 477         exit(1);
 478 }
 479
 480 /*
 481  * getterminaltype
 482  *
 483  *      Ask the other end to send along its terminal type and speed.
 484  * Output is the variable terminaltype filled in.
 485  */
 486 static unsigned char ttytype_sbbuf[] = {
 487         IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
 488 };
 489
 490 int
 491 getterminaltype(char *name, size_t l)
 492 {
 493     int retval = -1;
 494
 495     settimer(baseline);
 496 #ifdef AUTHENTICATION
 497     /*
 498      * Handle the Authentication option before we do anything else.
 499      */
 500     send_do(TELOPT_AUTHENTICATION, 1);
 501     while (his_will_wont_is_changing(TELOPT_AUTHENTICATION))
 502         ttloop();
 503     if (his_state_is_will(TELOPT_AUTHENTICATION)) {
 504         retval = auth_wait(name, l);
 505     }
 506 #endif
 507
 508 #ifdef  ENCRYPTION
 509     send_will(TELOPT_ENCRYPT, 1);
 510 #endif  /* ENCRYPTION */
 511     send_do(TELOPT_TTYPE, 1);
 512     send_do(TELOPT_TSPEED, 1);
 513     send_do(TELOPT_XDISPLOC, 1);
 514     send_do(TELOPT_NEW_ENVIRON, 1);
 515     send_do(TELOPT_OLD_ENVIRON, 1);
 516     while (
 517 #ifdef  ENCRYPTION
 518            his_do_dont_is_changing(TELOPT_ENCRYPT) ||
 519 #endif  /* ENCRYPTION */
 520            his_will_wont_is_changing(TELOPT_TTYPE) ||
 521            his_will_wont_is_changing(TELOPT_TSPEED) ||
 522            his_will_wont_is_changing(TELOPT_XDISPLOC) ||
 523            his_will_wont_is_changing(TELOPT_NEW_ENVIRON) ||
 524            his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) {
 525         ttloop();
 526     }
 527     if (his_state_is_will(TELOPT_TSPEED)) {
 528         static unsigned char sb[] =
 529                         { IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE };
 530
 531         output_datalen((const char *)sb, sizeof sb);
 532         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 533     }
 534 #ifdef  ENCRYPTION
 535     /*
 536      * Wait for the negotiation of what type of encryption we can
 537      * send with.  If autoencrypt is not set, this will just return.
 538      */
 539     if (his_state_is_will(TELOPT_ENCRYPT)) {
 540         encrypt_wait();
 541     }
 542 #endif  /* ENCRYPTION */
 543     if (his_state_is_will(TELOPT_XDISPLOC)) {
 544         static unsigned char sb[] =
 545                         { IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE };
 546
 547         output_datalen((const char *)sb, sizeof sb);
 548         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 549     }
 550     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 551         static unsigned char sb[] =
 552                         { IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE };
 553
 554         output_datalen((const char *)sb, sizeof sb);
 555         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 556     }
 557     else if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 558         static unsigned char sb[] =
 559                         { IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE };
 560
 561         output_datalen((const char *)sb, sizeof sb);
 562         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 563     }
 564     if (his_state_is_will(TELOPT_TTYPE)) {
 565
 566         output_datalen((const char *)ttytype_sbbuf, sizeof ttytype_sbbuf);
 567         DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 568                                         sizeof ttytype_sbbuf - 2););
 569     }
 570     if (his_state_is_will(TELOPT_TSPEED)) {
 571         while (sequenceIs(tspeedsubopt, baseline))
 572             ttloop();
 573     }
 574     if (his_state_is_will(TELOPT_XDISPLOC)) {
 575         while (sequenceIs(xdisplocsubopt, baseline))
 576             ttloop();
 577     }
 578     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 579         while (sequenceIs(environsubopt, baseline))
 580             ttloop();
 581     }
 582     if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 583         while (sequenceIs(oenvironsubopt, baseline))
 584             ttloop();
 585     }
 586     if (his_state_is_will(TELOPT_TTYPE)) {
 587         char first[256], last[256];
 588
 589         while (sequenceIs(ttypesubopt, baseline))
 590             ttloop();
 591
 592         /*
 593          * If the other side has already disabled the option, then
 594          * we have to just go with what we (might) have already gotten.
 595          */
 596         if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
 597             (void) strlcpy(first, terminaltype, sizeof(first));
 598             for(;;) {
 599                 /*
 600                  * Save the unknown name, and request the next name.
 601                  */
 602                 (void) strlcpy(last, terminaltype, sizeof(last));
 603                 _gettermname();
 604                 if (terminaltypeok(terminaltype))
 605                     break;
 606                 if ((strncmp(last, terminaltype, sizeof(last)) == 0) ||
 607                     his_state_is_wont(TELOPT_TTYPE)) {
 608                     /*
 609                      * We've hit the end.  If this is the same as
 610                      * the first name, just go with it.
 611                      */
 612                     if (strncmp(first, terminaltype, sizeof(first)) == 0)
 613                         break;
 614                     /*
 615                      * Get the terminal name one more time, so that
 616                      * RFC1091 compliant telnets will cycle back to
 617                      * the start of the list.
 618                      */
 619                      _gettermname();
 620                     if (strncmp(first, terminaltype, sizeof(first)) != 0) {
 621                         (void) strlcpy(terminaltype, first, sizeof(terminaltype));
 622                     }
 623                     break;
 624                 }
 625             }
 626         }
 627     }
 628     return(retval);
 629 }  /* end of getterminaltype */
 630
 631 void
 632 _gettermname(void)
 633 {
 634     /*
 635      * If the client turned off the option,
 636      * we can't send another request, so we
 637      * just return.
 638      */
 639     if (his_state_is_wont(TELOPT_TTYPE))
 640         return;
 641     settimer(baseline);
 642     output_datalen((const char *)ttytype_sbbuf, sizeof ttytype_sbbuf);
 643     DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 644                                         sizeof ttytype_sbbuf - 2););
 645     while (sequenceIs(ttypesubopt, baseline))
 646         ttloop();
 647 }
 648
 649 int
 650 terminaltypeok(char *s)
 651 {
 652     char buf[1024];
 653
 654     if (terminaltype == NULL)
 655         return(1);
 656
 657     /*
 658      * tgetent() will return 1 if the type is known, and
 659      * 0 if it is not known.  If it returns -1, it couldn't
 660      * open the database.  But if we can't open the database,
 661      * it won't help to say we failed, because we won't be
 662      * able to verify anything else.  So, we treat -1 like 1.
 663      */
 664     if (tgetent(buf, s) == 0)
 665         return(0);
 666     return(1);
 667 }
 668
 669 char *hostname;
 670 char host_name[MAXHOSTNAMELEN + 1];
 671 char remote_host_name[MAXHOSTNAMELEN + 1];
 672
 673 extern void telnet(int, int);
 674
 675 /*
 676  * Get a pty, scan input lines.
 677  */
 678 void
 679 doit(struct sockaddr *who)
 680 {
 681         char *host;
 682         int error;
 683         int level;
 684         int ptynum;
 685         int flags;
 686         char user_name[256];
 687
 688         /*
 689          * Find an available pty to use.
 690          */
 691         pty = getpty(&ptynum);
 692         if (pty < 0)
 693                 fatal(net, "All network ports in use");
 694
 695         flags = registerd_host_only ? NI_NAMEREQD : 0;
 696
 697         /* get name of connected client */
 698         error = getnameinfo(who, who->sa_len, remote_host_name,
 699             sizeof(remote_host_name), NULL, 0, flags);
 700
 701         if (error) {
 702                 fatal(net, "Couldn't resolve your address into a host name.\r\n\
 703          Please contact your net administrator");
 704 #ifdef __GNUC__
 705                 host = NULL;    /* XXX gcc */
 706 #endif
 707         }
 708
 709         remote_host_name[sizeof(remote_host_name)-1] = 0;
 710         host = remote_host_name;
 711
 712         (void)gethostname(host_name, sizeof(host_name));
 713         host_name[sizeof(host_name) - 1] = '\0';
 714         hostname = host_name;
 715
 716 #if     defined(AUTHENTICATION) || defined(ENCRYPTION)
 717         auth_encrypt_init(hostname, host, "TELNETD", 1);
 718 #endif
 719
 720         init_env();
 721         /*
 722          * get terminal type.
 723          */
 724         *user_name = 0;
 725         level = getterminaltype(user_name, sizeof(user_name));
 726         setenv("TERM", terminaltype[0] ? terminaltype : "network", 1);
 727
 728         /*
 729          * Start up the login process on the slave side of the terminal
 730          */
 731         startslave(host, level, user_name);
 732
 733         telnet(net, pty);  /* begin server processing */
 734         /*NOTREACHED*/
 735 }  /* end of doit */
 736
 737
 738 /*
 739  * Main loop.  Select from pty and network, and
 740  * hand data to telnet receiver finite state machine.
 741  */
 742 void
 743 telnet(int f, int p)
 744 {
 745         int on = 1;
 746 #define TABBUFSIZ       512
 747         char    defent[TABBUFSIZ];
 748         char    defstrs[TABBUFSIZ];
 749 #undef  TABBUFSIZ
 750         char *HE, *HN, *IM, *IF, *ptyibuf2ptr;
 751         struct pollfd set[2];
 752
 753         /*
 754          * Initialize the slc mapping table.
 755          */
 756         get_slc_defaults();
 757
 758         /*
 759          * Do some tests where it is desireable to wait for a response.
 760          * Rather than doing them slowly, one at a time, do them all
 761          * at once.
 762          */
 763         if (my_state_is_wont(TELOPT_SGA))
 764                 send_will(TELOPT_SGA, 1);
 765         /*
 766          * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
 767          * because 4.2 clients are unable to deal with TCP urgent data.
 768          *
 769          * To find out, we send out a "DO ECHO".  If the remote system
 770          * answers "WILL ECHO" it is probably a 4.2 client, and we note
 771          * that fact ("WILL ECHO" ==> that the client will echo what
 772          * WE, the server, sends it; it does NOT mean that the client will
 773          * echo the terminal input).
 774          */
 775         send_do(TELOPT_ECHO, 1);
 776
 777 #ifdef  LINEMODE
 778         if (his_state_is_wont(TELOPT_LINEMODE)) {
 779                 /* Query the peer for linemode support by trying to negotiate
 780                  * the linemode option.
 781                  */
 782                 linemode = 0;
 783                 editmode = 0;
 784                 send_do(TELOPT_LINEMODE, 1);  /* send do linemode */
 785         }
 786 #endif  /* LINEMODE */
 787
 788         /*
 789          * Send along a couple of other options that we wish to negotiate.
 790          */
 791         send_do(TELOPT_NAWS, 1);
 792         send_will(TELOPT_STATUS, 1);
 793         flowmode = 1;           /* default flow control state */
 794         restartany = -1;        /* uninitialized... */
 795         send_do(TELOPT_LFLOW, 1);
 796
 797         /*
 798          * Spin, waiting for a response from the DO ECHO.  However,
 799          * some REALLY DUMB telnets out there might not respond
 800          * to the DO ECHO.  So, we spin looking for NAWS, (most dumb
 801          * telnets so far seem to respond with WONT for a DO that
 802          * they don't understand...) because by the time we get the
 803          * response, it will already have processed the DO ECHO.
 804          * Kludge upon kludge.
 805          */
 806         while (his_will_wont_is_changing(TELOPT_NAWS))
 807                 ttloop();
 808
 809         /*
 810          * But...
 811          * The client might have sent a WILL NAWS as part of its
 812          * startup code; if so, we'll be here before we get the
 813          * response to the DO ECHO.  We'll make the assumption
 814          * that any implementation that understands about NAWS
 815          * is a modern enough implementation that it will respond
 816          * to our DO ECHO request; hence we'll do another spin
 817          * waiting for the ECHO option to settle down, which is
 818          * what we wanted to do in the first place...
 819          */
 820         if (his_want_state_is_will(TELOPT_ECHO) &&
 821             his_state_is_will(TELOPT_NAWS)) {
 822                 while (his_will_wont_is_changing(TELOPT_ECHO))
 823                         ttloop();
 824         }
 825         /*
 826          * On the off chance that the telnet client is broken and does not
 827          * respond to the DO ECHO we sent, (after all, we did send the
 828          * DO NAWS negotiation after the DO ECHO, and we won't get here
 829          * until a response to the DO NAWS comes back) simulate the
 830          * receipt of a will echo.  This will also send a WONT ECHO
 831          * to the client, since we assume that the client failed to
 832          * respond because it believes that it is already in DO ECHO
 833          * mode, which we do not want.
 834          */
 835         if (his_want_state_is_will(TELOPT_ECHO)) {
 836                 DIAG(TD_OPTIONS,
 837                         {output_data("td: simulating recv\r\n");});
 838                 willoption(TELOPT_ECHO);
 839         }
 840
 841         /*
 842          * Finally, to clean things up, we turn on our echo.  This
 843          * will break stupid 4.2 telnets out of local terminal echo.
 844          */
 845
 846         if (my_state_is_wont(TELOPT_ECHO))
 847                 send_will(TELOPT_ECHO, 1);
 848
 849         /*
 850          * Turn on packet mode
 851          */
 852         (void) ioctl(p, TIOCPKT, (char *)&on);
 853
 854 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 855         /*
 856          * Continuing line mode support.  If client does not support
 857          * real linemode, attempt to negotiate kludge linemode by sending
 858          * the do timing mark sequence.
 859          */
 860         if (lmodetype < REAL_LINEMODE)
 861                 send_do(TELOPT_TM, 1);
 862 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 863
 864         /*
 865          * Call telrcv() once to pick up anything received during
 866          * terminal type negotiation, 4.2/4.3 determination, and
 867          * linemode negotiation.
 868          */
 869         telrcv();
 870
 871         (void) ioctl(f, FIONBIO, (char *)&on);
 872         (void) ioctl(p, FIONBIO, (char *)&on);
 873
 874         (void) setsockopt(f, SOL_SOCKET, SO_OOBINLINE, (char *)&on, sizeof on);
 875
 876         (void) signal(SIGTSTP, SIG_IGN);
 877         /*
 878          * Ignoring SIGTTOU keeps the kernel from blocking us
 879          * in ttioct() in /sys/tty.c.
 880          */
 881         (void) signal(SIGTTOU, SIG_IGN);
 882
 883         (void) signal(SIGCHLD, cleanup);
 884
 885
 886         {
 887                 int t;
 888                 t = open(_PATH_TTY, O_RDWR);
 889                 if (t >= 0) {
 890                         (void) ioctl(t, TIOCNOTTY, (char *)0);
 891                         (void) close(t);
 892                 }
 893         }
 894
 895
 896         /*
 897          * Show banner that getty never gave.
 898          *
 899          * We put the banner in the pty input buffer.  This way, it
 900          * gets carriage return null processing, etc., just like all
 901          * other pty --> client data.
 902          */
 903
 904         if (getent(defent, gettyname) == 1) {
 905                 char *cp=defstrs;
 906
 907                 HE = getstr("he", &cp);
 908                 HN = getstr("hn", &cp);
 909                 IM = getstr("im", &cp);
 910                 IF = getstr("if", &cp);
 911                 if (HN && *HN)
 912                         (void)strlcpy(host_name, HN, sizeof(host_name));
 913                 if (IM == 0)
 914                         IM = "";
 915         } else {
 916                 IM = DEFAULT_IM;
 917                 HE = 0;
 918                 IF = NULL;
 919         }
 920         edithost(HE, host_name);
 921         ptyibuf2ptr = ptyibuf2;
 922         if (hostinfo) {
 923                 if (IF) {
 924                         char buf[_POSIX2_LINE_MAX];
 925                         FILE *fd;
 926
 927                         if ((fd = fopen(IF, "r")) != NULL) {
 928                                 while (fgets(buf, sizeof(buf) - 1, fd) != NULL)
 929                                         ptyibuf2ptr = putf(buf, ptyibuf2ptr);
 930                                 fclose(fd);
 931                         }
 932                 }
 933                 if (*IM)
 934                         ptyibuf2ptr = putf(IM, ptyibuf2ptr);
 935         }
 936
 937         if (pcc)
 938                 strncpy(ptyibuf2ptr, ptyip, pcc+1);
 939         ptyip = ptyibuf2;
 940         pcc = strlen(ptyip);
 941 #ifdef  LINEMODE
 942         /*
 943          * Last check to make sure all our states are correct.
 944          */
 945         init_termbuf();
 946         localstat();
 947 #endif  /* LINEMODE */
 948
 949         DIAG(TD_REPORT,
 950                 {output_data("td: Entering processing loop\r\n");});
 951
 952
 953         set[0].fd = f;
 954         set[1].fd = p;
 955         for (;;) {
 956                 int c;
 957
 958                 if (ncc < 0 && pcc < 0)
 959                         break;
 960
 961                 /*
 962                  * Never look for input if there's still
 963                  * stuff in the corresponding output buffer
 964                  */
 965                 set[0].events = 0;
 966                 set[1].events = 0;
 967                 if (nfrontp - nbackp || pcc > 0)
 968                         set[0].events |= POLLOUT;
 969                 else
 970                         set[1].events |= POLLIN;
 971                 if (pfrontp - pbackp || ncc > 0)
 972                         set[1].events |= POLLOUT;
 973                 else
 974                         set[0].events |= POLLIN;
 975                 if (!SYNCHing)
 976                         set[0].events |= POLLPRI;
 977
 978                 if ((c = poll(set, 2, INFTIM)) < 1) {
 979                         if (c == -1) {
 980                                 if (errno == EINTR) {
 981                                         continue;
 982                                 }
 983                         }
 984                         sleep(5);
 985                         continue;
 986                 }
 987
 988                 /*
 989                  * Any urgent data?
 990                  */
 991                 if (set[0].revents & POLLPRI) {
 992                     SYNCHing = 1;
 993                 }
 994
 995                 /*
 996                  * Something to read from the network...
 997                  */
 998                 if (set[0].revents & POLLIN) {
 999                     ncc = read(f, netibuf, sizeof (netibuf));
1000                     if (ncc < 0 && errno == EWOULDBLOCK)
1001                         ncc = 0;
1002                     else {
1003                         if (ncc <= 0) {
1004                             break;
1005                         }
1006                         netip = netibuf;
1007                     }
1008                     DIAG((TD_REPORT | TD_NETDATA),
1009                             {output_data("td: netread %d chars\r\n", ncc);});
1010                     DIAG(TD_NETDATA, printdata("nd", netip, ncc));
1011                 }
1012
1013                 /*
1014                  * Something to read from the pty...
1015                  */
1016                 if (set[1].revents & POLLIN) {
1017                         pcc = read(p, ptyibuf, BUFSIZ);
1018                         /*
1019                          * On some systems, if we try to read something
1020                          * off the master side before the slave side is
1021                          * opened, we get EIO.
1022                          */
1023                         if (pcc < 0 && (errno == EWOULDBLOCK ||
1024                                         errno == EAGAIN ||
1025                                         errno == EIO)) {
1026                                 pcc = 0;
1027                         } else {
1028                                 if (pcc <= 0)
1029                                         break;
1030 #ifdef  LINEMODE
1031                                 /*
1032                                  * If ioctl from pty, pass it through net
1033                                  */
1034                                 if (ptyibuf[0] & TIOCPKT_IOCTL) {
1035                                         copy_termbuf(ptyibuf+1, pcc-1);
1036                                         localstat();
1037                                         pcc = 1;
1038                                 }
1039 #endif  /* LINEMODE */
1040                                 if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
1041                                         netclear();     /* clear buffer back */
1042                                         /*
1043                                          * There are client telnets on some
1044                                          * operating systems get screwed up
1045                                          * royally if we send them urgent
1046                                          * mode data.
1047                                          */
1048                                         output_data("%c%c", IAC, DM);
1049                                         neturg = nfrontp - 1; /* off by one XXX */
1050                                         DIAG(TD_OPTIONS,
1051                                             printoption("td: send IAC", DM));
1052                                 }
1053                                 if (his_state_is_will(TELOPT_LFLOW) &&
1054                                     (ptyibuf[0] &
1055                                      (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
1056                                         int newflow =
1057                                             ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
1058                                         if (newflow != flowmode) {
1059                                                 flowmode = newflow;
1060                                                 (void) output_data(
1061                                                         "%c%c%c%c%c%c",
1062                                                         IAC, SB, TELOPT_LFLOW,
1063                                                         flowmode ? LFLOW_ON
1064                                                                  : LFLOW_OFF,
1065                                                         IAC, SE);
1066                                                 DIAG(TD_OPTIONS, printsub('>',
1067                                                     (unsigned char *)nfrontp - 4,
1068                                                     4););
1069                                         }
1070                                 }
1071                                 pcc--;
1072                                 ptyip = ptyibuf+1;
1073                         }
1074                 }
1075
1076                 while (pcc > 0) {
1077                         if ((&netobuf[BUFSIZ] - nfrontp) < 2)
1078                                 break;
1079                         c = *ptyip++ & 0377, pcc--;
1080                         if (c == IAC)
1081                                 output_data("%c", c);
1082                         output_data("%c", c);
1083                         if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
1084                                 if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
1085                                         output_data("%c", *ptyip++ & 0377);
1086                                         pcc--;
1087                                 } else
1088                                         output_datalen("\0", 1);
1089                         }
1090                 }
1091
1092                 if ((set[0].revents & POLLOUT) && (nfrontp - nbackp) > 0)
1093                         netflush();
1094                 if (ncc > 0)
1095                         telrcv();
1096                 if ((set[1].revents & POLLOUT) && (pfrontp - pbackp) > 0)
1097                         ptyflush();
1098         }
1099         cleanup(0);
1100 }  /* end of telnet */
1101
1102 /*
1103  * Send interrupt to process on other side of pty.
1104  * If it is in raw mode, just write NULL;
1105  * otherwise, write intr char.
1106  */
1107 void
1108 interrupt(void)
1109 {
1110         ptyflush();     /* half-hearted */
1111
1112         (void) ioctl(pty, TIOCSIG, (char *)SIGINT);
1113 }
1114
1115 /*
1116  * Send quit to process on other side of pty.
1117  * If it is in raw mode, just write NULL;
1118  * otherwise, write quit char.
1119  */
1120 void
1121 sendbrk(void)
1122 {
1123         ptyflush();     /* half-hearted */
1124         (void) ioctl(pty, TIOCSIG, (char *)SIGQUIT);
1125 }
1126
1127 void
1128 sendsusp(void)
1129 {
1130         ptyflush();     /* half-hearted */
1131         (void) ioctl(pty, TIOCSIG, (char *)SIGTSTP);
1132 }
1133
1134 /*
1135  * When we get an AYT, if ^T is enabled, use that.  Otherwise,
1136  * just send back "[Yes]".
1137  */
1138 void
1139 recv_ayt(void)
1140 {
1141         if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
1142                 (void) ioctl(pty, TIOCSIG, (char *)SIGINFO);
1143                 return;
1144         }
1145         (void) output_data("\r\n[Yes]\r\n");
1146 }
1147
1148 void
1149 doeof(void)
1150 {
1151         init_termbuf();
1152
1153 #if     defined(LINEMODE) && (VEOF == VMIN)
1154         if (!tty_isediting()) {
1155                 extern char oldeofc;
1156                 *pfrontp++ = oldeofc;
1157                 return;
1158         }
1159 #endif
1160         *pfrontp++ = slctab[SLC_EOF].sptr ?
1161                         (unsigned char)*slctab[SLC_EOF].sptr : '\004';
1162 }