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/libexec/telnetd/telnetd.c,v 1.22.2.8 2002/04/13 11:07:12 markm Exp $
  35  * $DragonFly: src/libexec/telnetd/telnetd.c,v 1.3 2006/01/12 13:43:10 corecode 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 #include <libtelnet/misc.h>
  51
  52 char    remote_hostname[MAXHOSTNAMELEN];
  53 size_t  utmp_len = sizeof(remote_hostname) - 1;
  54 int     registerd_host_only = 0;
  55
  56
  57 /*
  58  * I/O data buffers,
  59  * pointers, and counters.
  60  */
  61 char    ptyibuf[BUFSIZ], *ptyip = ptyibuf;
  62 char    ptyibuf2[BUFSIZ];
  63
  64 int readstream(int, char *, int);
  65 void doit(struct sockaddr *);
  66 int terminaltypeok(char *);
  67
  68 int     hostinfo = 1;                   /* do we print login banner? */
  69
  70 int debug = 0;
  71 int keepalive = 1;
  72 const char *altlogin;
  73
  74 void doit(struct sockaddr *);
  75 int terminaltypeok(char *);
  76 void startslave(char *, int, char *);
  77 extern void usage(void);
  78 static void _gettermname(void);
  79
  80 /*
  81  * The string to pass to getopt().  We do it this way so
  82  * that only the actual options that we support will be
  83  * passed off to getopt().
  84  */
  85 char valid_opts[] = {
  86         'd', ':', 'h', 'k', 'n', 'p', ':', 'S', ':', 'u', ':', 'U',
  87         '4', '6',
  88 #ifdef BFTPDAEMON
  89         'B',
  90 #endif
  91 #ifdef DIAGNOSTICS
  92         'D', ':',
  93 #endif
  94 #ifdef  LINEMODE
  95         'l',
  96 #endif
  97         '\0'
  98 };
  99
 100 int family = AF_INET;
 101
 102 #ifndef MAXHOSTNAMELEN
 103 #define MAXHOSTNAMELEN 256
 104 #endif  /* MAXHOSTNAMELEN */
 105
 106 char *hostname;
 107 char host_name[MAXHOSTNAMELEN];
 108
 109 extern void telnet(int, int, char *);
 110
 111 int level;
 112 char user_name[256];
 113
 114 int
 115 main(int argc, char *argv[])
 116 {
 117         struct sockaddr_storage from;
 118         int on = 1, fromlen;
 119         int ch;
 120 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 121         int tos = -1;
 122 #endif
 123
 124         pfrontp = pbackp = ptyobuf;
 125         netip = netibuf;
 126         nfrontp = nbackp = netobuf;
 127
 128         /*
 129          * This initialization causes linemode to default to a configuration
 130          * that works on all telnet clients, including the FreeBSD client.
 131          * This is not quite the same as the telnet client issuing a "mode
 132          * character" command, but has most of the same benefits, and is
 133          * preferable since some clients (like usofts) don't have the
 134          * mode character command anyway and linemode breaks things.
 135          * The most notable symptom of fix is that csh "set filec" operations
 136          * like <ESC> (filename completion) and ^D (choices) keys now work
 137          * in telnet sessions and can be used more than once on the same line.
 138          * CR/LF handling is also corrected in some termio modes.  This
 139          * change resolves problem reports bin/771 and bin/1037.
 140          */
 141
 142         linemode=1;     /*Default to mode that works on bulk of clients*/
 143
 144         while ((ch = getopt(argc, argv, valid_opts)) != -1) {
 145                 switch(ch) {
 146
 147
 148 #ifdef BFTPDAEMON
 149                 case 'B':
 150                         bftpd++;
 151                         break;
 152 #endif /* BFTPDAEMON */
 153
 154                 case 'd':
 155                         if (strcmp(optarg, "ebug") == 0) {
 156                                 debug++;
 157                                 break;
 158                         }
 159                         usage();
 160                         /* NOTREACHED */
 161                         break;
 162
 163 #ifdef DIAGNOSTICS
 164                 case 'D':
 165                         /*
 166                          * Check for desired diagnostics capabilities.
 167                          */
 168                         if (!strcmp(optarg, "report")) {
 169                                 diagnostic |= TD_REPORT|TD_OPTIONS;
 170                         } else if (!strcmp(optarg, "exercise")) {
 171                                 diagnostic |= TD_EXERCISE;
 172                         } else if (!strcmp(optarg, "netdata")) {
 173                                 diagnostic |= TD_NETDATA;
 174                         } else if (!strcmp(optarg, "ptydata")) {
 175                                 diagnostic |= TD_PTYDATA;
 176                         } else if (!strcmp(optarg, "options")) {
 177                                 diagnostic |= TD_OPTIONS;
 178                         } else {
 179                                 usage();
 180                                 /* NOT REACHED */
 181                         }
 182                         break;
 183 #endif /* DIAGNOSTICS */
 184
 185
 186                 case 'h':
 187                         hostinfo = 0;
 188                         break;
 189
 190 #ifdef  LINEMODE
 191                 case 'l':
 192                         alwayslinemode = 1;
 193                         break;
 194 #endif  /* LINEMODE */
 195
 196                 case 'k':
 197 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 198                         lmodetype = NO_AUTOKLUDGE;
 199 #else
 200                         /* ignore -k option if built without kludge linemode */
 201 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 202                         break;
 203
 204                 case 'n':
 205                         keepalive = 0;
 206                         break;
 207
 208                 case 'p':
 209                         altlogin = optarg;
 210                         break;
 211
 212                 case 'S':
 213 #ifdef  HAS_GETTOS
 214                         if ((tos = parsetos(optarg, "tcp")) < 0)
 215                                 warnx("%s%s%s",
 216                                         "bad TOS argument '", optarg,
 217                                         "'; will try to use default TOS");
 218 #else
 219                         warnx("TOS option unavailable; -S flag not supported");
 220 #endif
 221                         break;
 222
 223                 case 'u':
 224                         utmp_len = (size_t)atoi(optarg);
 225                         if (utmp_len >= sizeof(remote_hostname))
 226                                 utmp_len = sizeof(remote_hostname) - 1;
 227                         break;
 228
 229                 case 'U':
 230                         registerd_host_only = 1;
 231                         break;
 232
 233
 234                 case '4':
 235                         family = AF_INET;
 236                         break;
 237
 238 #ifdef INET6
 239                 case '6':
 240                         family = AF_INET6;
 241                         break;
 242 #endif
 243
 244                 default:
 245                         warnx("%c: unknown option", ch);
 246                         /* FALLTHROUGH */
 247                 case '?':
 248                         usage();
 249                         /* NOTREACHED */
 250                 }
 251         }
 252
 253         argc -= optind;
 254         argv += optind;
 255
 256         if (debug) {
 257             int s, ns, foo, error;
 258             const char *service = "telnet";
 259             struct addrinfo hints, *res;
 260
 261             if (argc > 1) {
 262                 usage();
 263                 /* NOT REACHED */
 264             } else if (argc == 1)
 265                 service = *argv;
 266
 267             memset(&hints, 0, sizeof(hints));
 268             hints.ai_flags = AI_PASSIVE;
 269             hints.ai_family = family;
 270             hints.ai_socktype = SOCK_STREAM;
 271             hints.ai_protocol = 0;
 272             error = getaddrinfo(NULL, service, &hints, &res);
 273
 274             if (error) {
 275                 errx(1, "tcp/%s: %s\n", service, gai_strerror(error));
 276                 if (error == EAI_SYSTEM)
 277                     errx(1, "tcp/%s: %s\n", service, strerror(errno));
 278                 usage();
 279             }
 280
 281             s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 282             if (s < 0)
 283                     err(1, "socket");
 284             (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
 285                                 (char *)&on, sizeof(on));
 286             if (bind(s, res->ai_addr, res->ai_addrlen) < 0)
 287                 err(1, "bind");
 288             if (listen(s, 1) < 0)
 289                 err(1, "listen");
 290             foo = res->ai_addrlen;
 291             ns = accept(s, res->ai_addr, &foo);
 292             if (ns < 0)
 293                 err(1, "accept");
 294             (void) dup2(ns, 0);
 295             (void) close(ns);
 296             (void) close(s);
 297 #ifdef convex
 298         } else if (argc == 1) {
 299                 ; /* VOID*/             /* Just ignore the host/port name */
 300 #endif
 301         } else if (argc > 0) {
 302                 usage();
 303                 /* NOT REACHED */
 304         }
 305
 306         openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
 307         fromlen = sizeof (from);
 308         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 309                 warn("getpeername");
 310                 _exit(1);
 311         }
 312         if (keepalive &&
 313             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE,
 314                         (char *)&on, sizeof (on)) < 0) {
 315                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 316         }
 317
 318 #if     defined(IPPROTO_IP) && defined(IP_TOS)
 319         if (from.ss_family == AF_INET) {
 320 # if    defined(HAS_GETTOS)
 321                 struct tosent *tp;
 322                 if (tos < 0 && (tp = gettosbyname("telnet", "tcp")))
 323                         tos = tp->t_tos;
 324 # endif
 325                 if (tos < 0)
 326                         tos = 020;      /* Low Delay bit */
 327                 if (tos
 328                    && (setsockopt(0, IPPROTO_IP, IP_TOS,
 329                                   (char *)&tos, sizeof(tos)) < 0)
 330                    && (errno != ENOPROTOOPT) )
 331                         syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 332         }
 333 #endif  /* defined(IPPROTO_IP) && defined(IP_TOS) */
 334         net = 0;
 335         doit((struct sockaddr *)&from);
 336         /* NOTREACHED */
 337         return(0);
 338 }  /* end of main */
 339
 340         void
 341 usage()
 342 {
 343         fprintf(stderr, "usage: telnetd");
 344 #ifdef BFTPDAEMON
 345         fprintf(stderr, " [-B]");
 346 #endif
 347         fprintf(stderr, " [-debug]");
 348 #ifdef DIAGNOSTICS
 349         fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t");
 350 #endif
 351         fprintf(stderr, " [-h]");
 352 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 353         fprintf(stderr, " [-k]");
 354 #endif
 355 #ifdef LINEMODE
 356         fprintf(stderr, " [-l]");
 357 #endif
 358         fprintf(stderr, " [-n]");
 359         fprintf(stderr, "\n\t");
 360 #ifdef  HAS_GETTOS
 361         fprintf(stderr, " [-S tos]");
 362 #endif
 363         fprintf(stderr, " [-u utmp_hostname_length] [-U]");
 364         fprintf(stderr, " [port]\n");
 365         exit(1);
 366 }
 367
 368 /*
 369  * getterminaltype
 370  *
 371  *      Ask the other end to send along its terminal type and speed.
 372  * Output is the variable terminaltype filled in.
 373  */
 374 static unsigned char ttytype_sbbuf[] = {
 375         IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
 376 };
 377
 378
 379 #define undef2 __unused
 380
 381 static int
 382 getterminaltype(char *name undef2)
 383 {
 384     int retval = -1;
 385
 386     settimer(baseline);
 387
 388     send_do(TELOPT_TTYPE, 1);
 389     send_do(TELOPT_TSPEED, 1);
 390     send_do(TELOPT_XDISPLOC, 1);
 391     send_do(TELOPT_NEW_ENVIRON, 1);
 392     send_do(TELOPT_OLD_ENVIRON, 1);
 393     while (
 394            his_will_wont_is_changing(TELOPT_TTYPE) ||
 395            his_will_wont_is_changing(TELOPT_TSPEED) ||
 396            his_will_wont_is_changing(TELOPT_XDISPLOC) ||
 397            his_will_wont_is_changing(TELOPT_NEW_ENVIRON) ||
 398            his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) {
 399         ttloop();
 400     }
 401     if (his_state_is_will(TELOPT_TSPEED)) {
 402         static unsigned char sb[] =
 403                         { IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE };
 404
 405         output_datalen(sb, sizeof sb);
 406         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 407     }
 408     if (his_state_is_will(TELOPT_XDISPLOC)) {
 409         static unsigned char sb[] =
 410                         { IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE };
 411
 412         output_datalen(sb, sizeof sb);
 413         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 414     }
 415     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 416         static unsigned char sb[] =
 417                         { IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE };
 418
 419         output_datalen(sb, sizeof sb);
 420         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 421     }
 422     else if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 423         static unsigned char sb[] =
 424                         { IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE };
 425
 426         output_datalen(sb, sizeof sb);
 427         DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
 428     }
 429     if (his_state_is_will(TELOPT_TTYPE)) {
 430
 431         output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 432         DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 433                                         sizeof ttytype_sbbuf - 2););
 434     }
 435     if (his_state_is_will(TELOPT_TSPEED)) {
 436         while (sequenceIs(tspeedsubopt, baseline))
 437             ttloop();
 438     }
 439     if (his_state_is_will(TELOPT_XDISPLOC)) {
 440         while (sequenceIs(xdisplocsubopt, baseline))
 441             ttloop();
 442     }
 443     if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
 444         while (sequenceIs(environsubopt, baseline))
 445             ttloop();
 446     }
 447     if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
 448         while (sequenceIs(oenvironsubopt, baseline))
 449             ttloop();
 450     }
 451     if (his_state_is_will(TELOPT_TTYPE)) {
 452         char first[256], last[256];
 453
 454         while (sequenceIs(ttypesubopt, baseline))
 455             ttloop();
 456
 457         /*
 458          * If the other side has already disabled the option, then
 459          * we have to just go with what we (might) have already gotten.
 460          */
 461         if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
 462             (void) strncpy(first, terminaltype, sizeof(first)-1);
 463             first[sizeof(first)-1] = '\0';
 464             for(;;) {
 465                 /*
 466                  * Save the unknown name, and request the next name.
 467                  */
 468                 (void) strncpy(last, terminaltype, sizeof(last)-1);
 469                 last[sizeof(last)-1] = '\0';
 470                 _gettermname();
 471                 if (terminaltypeok(terminaltype))
 472                     break;
 473                 if ((strncmp(last, terminaltype, sizeof(last)) == 0) ||
 474                     his_state_is_wont(TELOPT_TTYPE)) {
 475                     /*
 476                      * We've hit the end.  If this is the same as
 477                      * the first name, just go with it.
 478                      */
 479                     if (strncmp(first, terminaltype, sizeof(first)) == 0)
 480                         break;
 481                     /*
 482                      * Get the terminal name one more time, so that
 483                      * RFC1091 compliant telnets will cycle back to
 484                      * the start of the list.
 485                      */
 486                      _gettermname();
 487                     if (strncmp(first, terminaltype, sizeof(first)) != 0) {
 488                         (void) strncpy(terminaltype, first, sizeof(terminaltype)-1);
 489                         terminaltype[sizeof(terminaltype)-1] = '\0';
 490                     }
 491                     break;
 492                 }
 493             }
 494         }
 495     }
 496     return(retval);
 497 }  /* end of getterminaltype */
 498
 499 static void
 500 _gettermname(void)
 501 {
 502     /*
 503      * If the client turned off the option,
 504      * we can't send another request, so we
 505      * just return.
 506      */
 507     if (his_state_is_wont(TELOPT_TTYPE))
 508         return;
 509     settimer(baseline);
 510     output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
 511     DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
 512                                         sizeof ttytype_sbbuf - 2););
 513     while (sequenceIs(ttypesubopt, baseline))
 514         ttloop();
 515 }
 516
 517 int
 518 terminaltypeok(char *s)
 519 {
 520     char buf[1024];
 521
 522     if (terminaltype == NULL)
 523         return(1);
 524
 525     /*
 526      * tgetent() will return 1 if the type is known, and
 527      * 0 if it is not known.  If it returns -1, it couldn't
 528      * open the database.  But if we can't open the database,
 529      * it won't help to say we failed, because we won't be
 530      * able to verify anything else.  So, we treat -1 like 1.
 531      */
 532     if (tgetent(buf, s) == 0)
 533         return(0);
 534     return(1);
 535 }
 536
 537 /*
 538  * Get a pty, scan input lines.
 539  */
 540 void
 541 doit(struct sockaddr *who)
 542 {
 543         int err_; /* XXX */
 544         int ptynum;
 545
 546         /*
 547          * Find an available pty to use.
 548          */
 549 #ifndef convex
 550         pty = getpty(&ptynum);
 551         if (pty < 0)
 552                 fatal(net, "All network ports in use");
 553 #else
 554         for (;;) {
 555                 char *lp;
 556
 557                 if ((lp = getpty()) == NULL)
 558                         fatal(net, "Out of ptys");
 559
 560                 if ((pty = open(lp, 2)) >= 0) {
 561                         strlcpy(line,lp,sizeof(line));
 562                         line[5] = 't';
 563                         break;
 564                 }
 565         }
 566 #endif
 567
 568         /* get name of connected client */
 569         if (realhostname_sa(remote_hostname, sizeof(remote_hostname) - 1,
 570             who, who->sa_len) == HOSTNAME_INVALIDADDR && registerd_host_only)
 571                 fatal(net, "Couldn't resolve your address into a host name.\r\n\
 572         Please contact your net administrator");
 573         remote_hostname[sizeof(remote_hostname) - 1] = '\0';
 574
 575         trimdomain(remote_hostname, UT_HOSTSIZE);
 576         if (!isdigit(remote_hostname[0]) && strlen(remote_hostname) > utmp_len)
 577                 err_ = getnameinfo(who, who->sa_len, remote_hostname,
 578                                   sizeof(remote_hostname), NULL, 0,
 579                                   NI_NUMERICHOST|NI_WITHSCOPEID);
 580                 /* XXX: do 'err_' check */
 581
 582         (void) gethostname(host_name, sizeof(host_name) - 1);
 583         host_name[sizeof(host_name) - 1] = '\0';
 584         hostname = host_name;
 585
 586
 587         init_env();
 588         /*
 589          * get terminal type.
 590          */
 591         *user_name = 0;
 592         level = getterminaltype(user_name);
 593         if (setenv("TERM", terminaltype ? terminaltype : "network", 1) == -1)
 594                 syslog(LOG_ERR, "setenv: cannot set TERM=%s: %m", terminaltype ? terminaltype : "network");
 595
 596         telnet(net, pty, remote_hostname);      /* begin server process */
 597
 598         /*NOTREACHED*/
 599 }  /* end of doit */
 600
 601 /*
 602  * Main loop.  Select from pty and network, and
 603  * hand data to telnet receiver finite state machine.
 604  */
 605 void
 606 telnet(int f, int p, char *host)
 607 {
 608         int on = 1;
 609 #define TABBUFSIZ       512
 610         char    defent[TABBUFSIZ];
 611         char    defstrs[TABBUFSIZ];
 612 #undef  TABBUFSIZ
 613         char *HE;
 614         char *HN;
 615         char *IM;
 616         int nfd;
 617
 618         /*
 619          * Initialize the slc mapping table.
 620          */
 621         get_slc_defaults();
 622
 623         /*
 624          * Do some tests where it is desireable to wait for a response.
 625          * Rather than doing them slowly, one at a time, do them all
 626          * at once.
 627          */
 628         if (my_state_is_wont(TELOPT_SGA))
 629                 send_will(TELOPT_SGA, 1);
 630         /*
 631          * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
 632          * because 4.2 clients are unable to deal with TCP urgent data.
 633          *
 634          * To find out, we send out a "DO ECHO".  If the remote system
 635          * answers "WILL ECHO" it is probably a 4.2 client, and we note
 636          * that fact ("WILL ECHO" ==> that the client will echo what
 637          * WE, the server, sends it; it does NOT mean that the client will
 638          * echo the terminal input).
 639          */
 640         send_do(TELOPT_ECHO, 1);
 641
 642 #ifdef  LINEMODE
 643         if (his_state_is_wont(TELOPT_LINEMODE)) {
 644                 /* Query the peer for linemode support by trying to negotiate
 645                  * the linemode option.
 646                  */
 647                 linemode = 0;
 648                 editmode = 0;
 649                 send_do(TELOPT_LINEMODE, 1);  /* send do linemode */
 650         }
 651 #endif  /* LINEMODE */
 652
 653         /*
 654          * Send along a couple of other options that we wish to negotiate.
 655          */
 656         send_do(TELOPT_NAWS, 1);
 657         send_will(TELOPT_STATUS, 1);
 658         flowmode = 1;           /* default flow control state */
 659         restartany = -1;        /* uninitialized... */
 660         send_do(TELOPT_LFLOW, 1);
 661
 662         /*
 663          * Spin, waiting for a response from the DO ECHO.  However,
 664          * some REALLY DUMB telnets out there might not respond
 665          * to the DO ECHO.  So, we spin looking for NAWS, (most dumb
 666          * telnets so far seem to respond with WONT for a DO that
 667          * they don't understand...) because by the time we get the
 668          * response, it will already have processed the DO ECHO.
 669          * Kludge upon kludge.
 670          */
 671         while (his_will_wont_is_changing(TELOPT_NAWS))
 672                 ttloop();
 673
 674         /*
 675          * But...
 676          * The client might have sent a WILL NAWS as part of its
 677          * startup code; if so, we'll be here before we get the
 678          * response to the DO ECHO.  We'll make the assumption
 679          * that any implementation that understands about NAWS
 680          * is a modern enough implementation that it will respond
 681          * to our DO ECHO request; hence we'll do another spin
 682          * waiting for the ECHO option to settle down, which is
 683          * what we wanted to do in the first place...
 684          */
 685         if (his_want_state_is_will(TELOPT_ECHO) &&
 686             his_state_is_will(TELOPT_NAWS)) {
 687                 while (his_will_wont_is_changing(TELOPT_ECHO))
 688                         ttloop();
 689         }
 690         /*
 691          * On the off chance that the telnet client is broken and does not
 692          * respond to the DO ECHO we sent, (after all, we did send the
 693          * DO NAWS negotiation after the DO ECHO, and we won't get here
 694          * until a response to the DO NAWS comes back) simulate the
 695          * receipt of a will echo.  This will also send a WONT ECHO
 696          * to the client, since we assume that the client failed to
 697          * respond because it believes that it is already in DO ECHO
 698          * mode, which we do not want.
 699          */
 700         if (his_want_state_is_will(TELOPT_ECHO)) {
 701                 DIAG(TD_OPTIONS, output_data("td: simulating recv\r\n"));
 702                 willoption(TELOPT_ECHO);
 703         }
 704
 705         /*
 706          * Finally, to clean things up, we turn on our echo.  This
 707          * will break stupid 4.2 telnets out of local terminal echo.
 708          */
 709
 710         if (my_state_is_wont(TELOPT_ECHO))
 711                 send_will(TELOPT_ECHO, 1);
 712
 713         /*
 714          * Turn on packet mode
 715          */
 716         (void) ioctl(p, TIOCPKT, (char *)&on);
 717
 718 #if     defined(LINEMODE) && defined(KLUDGELINEMODE)
 719         /*
 720          * Continuing line mode support.  If client does not support
 721          * real linemode, attempt to negotiate kludge linemode by sending
 722          * the do timing mark sequence.
 723          */
 724         if (lmodetype < REAL_LINEMODE)
 725                 send_do(TELOPT_TM, 1);
 726 #endif  /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
 727
 728         /*
 729          * Call telrcv() once to pick up anything received during
 730          * terminal type negotiation, 4.2/4.3 determination, and
 731          * linemode negotiation.
 732          */
 733         telrcv();
 734
 735         (void) ioctl(f, FIONBIO, (char *)&on);
 736         (void) ioctl(p, FIONBIO, (char *)&on);
 737
 738 #if     defined(SO_OOBINLINE)
 739         (void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE,
 740                                 (char *)&on, sizeof on);
 741 #endif  /* defined(SO_OOBINLINE) */
 742
 743 #ifdef  SIGTSTP
 744         (void) signal(SIGTSTP, SIG_IGN);
 745 #endif
 746 #ifdef  SIGTTOU
 747         /*
 748          * Ignoring SIGTTOU keeps the kernel from blocking us
 749          * in ttioct() in /sys/tty.c.
 750          */
 751         (void) signal(SIGTTOU, SIG_IGN);
 752 #endif
 753
 754         (void) signal(SIGCHLD, cleanup);
 755
 756 #ifdef  TIOCNOTTY
 757         {
 758                 int t;
 759                 t = open(_PATH_TTY, O_RDWR);
 760                 if (t >= 0) {
 761                         (void) ioctl(t, TIOCNOTTY, (char *)0);
 762                         (void) close(t);
 763                 }
 764         }
 765 #endif
 766
 767         /*
 768          * Show banner that getty never gave.
 769          *
 770          * We put the banner in the pty input buffer.  This way, it
 771          * gets carriage return null processing, etc., just like all
 772          * other pty --> client data.
 773          */
 774
 775         if (getent(defent, "default") == 1) {
 776                 char *cp=defstrs;
 777
 778                 HE = Getstr("he", &cp);
 779                 HN = Getstr("hn", &cp);
 780                 IM = Getstr("im", &cp);
 781                 if (HN && *HN)
 782                         (void) strlcpy(host_name, HN, sizeof(host_name));
 783                 if (IM == 0)
 784                         IM = strdup("");
 785         } else {
 786                 IM = strdup(DEFAULT_IM);
 787                 HE = 0;
 788         }
 789         edithost(HE, host_name);
 790         if (hostinfo && *IM)
 791                 putf(IM, ptyibuf2);
 792
 793         if (pcc)
 794                 (void) strncat(ptyibuf2, ptyip, pcc+1);
 795         ptyip = ptyibuf2;
 796         pcc = strlen(ptyip);
 797 #ifdef  LINEMODE
 798         /*
 799          * Last check to make sure all our states are correct.
 800          */
 801         init_termbuf();
 802         localstat();
 803 #endif  /* LINEMODE */
 804
 805         DIAG(TD_REPORT, output_data("td: Entering processing loop\r\n"));
 806
 807         /*
 808          * Startup the login process on the slave side of the terminal
 809          * now.  We delay this until here to insure option negotiation
 810          * is complete.
 811          */
 812         startslave(host, level, user_name);
 813
 814         nfd = ((f > p) ? f : p) + 1;
 815         for (;;) {
 816                 fd_set ibits, obits, xbits;
 817                 int c;
 818
 819                 if (ncc < 0 && pcc < 0)
 820                         break;
 821
 822                 FD_ZERO(&ibits);
 823                 FD_ZERO(&obits);
 824                 FD_ZERO(&xbits);
 825                 /*
 826                  * Never look for input if there's still
 827                  * stuff in the corresponding output buffer
 828                  */
 829                 if (nfrontp - nbackp || pcc > 0) {
 830                         FD_SET(f, &obits);
 831                 } else {
 832                         FD_SET(p, &ibits);
 833                 }
 834                 if (pfrontp - pbackp || ncc > 0) {
 835                         FD_SET(p, &obits);
 836                 } else {
 837                         FD_SET(f, &ibits);
 838                 }
 839                 if (!SYNCHing) {
 840                         FD_SET(f, &xbits);
 841                 }
 842                 if ((c = select(nfd, &ibits, &obits, &xbits,
 843                                                 (struct timeval *)0)) < 1) {
 844                         if (c == -1) {
 845                                 if (errno == EINTR) {
 846                                         continue;
 847                                 }
 848                         }
 849                         sleep(5);
 850                         continue;
 851                 }
 852
 853                 /*
 854                  * Any urgent data?
 855                  */
 856                 if (FD_ISSET(net, &xbits)) {
 857                     SYNCHing = 1;
 858                 }
 859
 860                 /*
 861                  * Something to read from the network...
 862                  */
 863                 if (FD_ISSET(net, &ibits)) {
 864 #if     !defined(SO_OOBINLINE)
 865                         /*
 866                          * In 4.2 (and 4.3 beta) systems, the
 867                          * OOB indication and data handling in the kernel
 868                          * is such that if two separate TCP Urgent requests
 869                          * come in, one byte of TCP data will be overlaid.
 870                          * This is fatal for Telnet, but we try to live
 871                          * with it.
 872                          *
 873                          * In addition, in 4.2 (and...), a special protocol
 874                          * is needed to pick up the TCP Urgent data in
 875                          * the correct sequence.
 876                          *
 877                          * What we do is:  if we think we are in urgent
 878                          * mode, we look to see if we are "at the mark".
 879                          * If we are, we do an OOB receive.  If we run
 880                          * this twice, we will do the OOB receive twice,
 881                          * but the second will fail, since the second
 882                          * time we were "at the mark", but there wasn't
 883                          * any data there (the kernel doesn't reset
 884                          * "at the mark" until we do a normal read).
 885                          * Once we've read the OOB data, we go ahead
 886                          * and do normal reads.
 887                          *
 888                          * There is also another problem, which is that
 889                          * since the OOB byte we read doesn't put us
 890                          * out of OOB state, and since that byte is most
 891                          * likely the TELNET DM (data mark), we would
 892                          * stay in the TELNET SYNCH (SYNCHing) state.
 893                          * So, clocks to the rescue.  If we've "just"
 894                          * received a DM, then we test for the
 895                          * presence of OOB data when the receive OOB
 896                          * fails (and AFTER we did the normal mode read
 897                          * to clear "at the mark").
 898                          */
 899                     if (SYNCHing) {
 900                         int atmark;
 901
 902                         (void) ioctl(net, SIOCATMARK, (char *)&atmark);
 903                         if (atmark) {
 904                             ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
 905                             if ((ncc == -1) && (errno == EINVAL)) {
 906                                 ncc = read(net, netibuf, sizeof (netibuf));
 907                                 if (sequenceIs(didnetreceive, gotDM)) {
 908                                     SYNCHing = stilloob(net);
 909                                 }
 910                             }
 911                         } else {
 912                             ncc = read(net, netibuf, sizeof (netibuf));
 913                         }
 914                     } else {
 915                         ncc = read(net, netibuf, sizeof (netibuf));
 916                     }
 917                     settimer(didnetreceive);
 918 #else   /* !defined(SO_OOBINLINE)) */
 919                     ncc = read(net, netibuf, sizeof (netibuf));
 920 #endif  /* !defined(SO_OOBINLINE)) */
 921                     if (ncc < 0 && errno == EWOULDBLOCK)
 922                         ncc = 0;
 923                     else {
 924                         if (ncc <= 0) {
 925                             break;
 926                         }
 927                         netip = netibuf;
 928                     }
 929                     DIAG((TD_REPORT | TD_NETDATA),
 930                         output_data("td: netread %d chars\r\n", ncc));
 931                     DIAG(TD_NETDATA, printdata("nd", netip, ncc));
 932                 }
 933
 934                 /*
 935                  * Something to read from the pty...
 936                  */
 937                 if (FD_ISSET(p, &ibits)) {
 938                         pcc = read(p, ptyibuf, BUFSIZ);
 939                         /*
 940                          * On some systems, if we try to read something
 941                          * off the master side before the slave side is
 942                          * opened, we get EIO.
 943                          */
 944                         if (pcc < 0 && (errno == EWOULDBLOCK ||
 945 #ifdef  EAGAIN
 946                                         errno == EAGAIN ||
 947 #endif
 948                                         errno == EIO)) {
 949                                 pcc = 0;
 950                         } else {
 951                                 if (pcc <= 0)
 952                                         break;
 953 #ifdef  LINEMODE
 954                                 /*
 955                                  * If ioctl from pty, pass it through net
 956                                  */
 957                                 if (ptyibuf[0] & TIOCPKT_IOCTL) {
 958                                         copy_termbuf(ptyibuf+1, pcc-1);
 959                                         localstat();
 960                                         pcc = 1;
 961                                 }
 962 #endif  /* LINEMODE */
 963                                 if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
 964                                         netclear();     /* clear buffer back */
 965 #ifndef NO_URGENT
 966                                         /*
 967                                          * There are client telnets on some
 968                                          * operating systems get screwed up
 969                                          * royally if we send them urgent
 970                                          * mode data.
 971                                          */
 972                                         output_data("%c%c", IAC, DM);
 973                                         neturg = nfrontp-1; /* off by one XXX */
 974                                         DIAG(TD_OPTIONS,
 975                                             printoption("td: send IAC", DM));
 976
 977 #endif
 978                                 }
 979                                 if (his_state_is_will(TELOPT_LFLOW) &&
 980                                     (ptyibuf[0] &
 981                                      (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
 982                                         int newflow =
 983                                             ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
 984                                         if (newflow != flowmode) {
 985                                                 flowmode = newflow;
 986                                                 output_data("%c%c%c%c%c%c",
 987                                                         IAC, SB, TELOPT_LFLOW,
 988                                                         flowmode ? LFLOW_ON
 989                                                                  : LFLOW_OFF,
 990                                                         IAC, SE);
 991                                                 DIAG(TD_OPTIONS, printsub('>',
 992                                                     (unsigned char *)nfrontp-4,
 993                                                     4););
 994                                         }
 995                                 }
 996                                 pcc--;
 997                                 ptyip = ptyibuf+1;
 998                         }
 999                 }
1000
1001                 while (pcc > 0) {
1002                         if ((&netobuf[BUFSIZ] - nfrontp) < 2)
1003                                 break;
1004                         c = *ptyip++ & 0377, pcc--;
1005                         if (c == IAC)
1006                                 output_data("%c", c);
1007                         output_data("%c", c);
1008                         if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
1009                                 if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
1010                                         output_data("%c", *ptyip++ & 0377);
1011                                         pcc--;
1012                                 } else
1013                                         output_data("%c", '\0');
1014                         }
1015                 }
1016
1017                 if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
1018                         netflush();
1019                 if (ncc > 0)
1020                         telrcv();
1021                 if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
1022                         ptyflush();
1023         }
1024         cleanup(0);
1025 }  /* end of telnet */
1026
1027 #ifndef TCSIG
1028 # ifdef TIOCSIG
1029 #  define TCSIG TIOCSIG
1030 # endif
1031 #endif
1032
1033 /*
1034  * Send interrupt to process on other side of pty.
1035  * If it is in raw mode, just write NULL;
1036  * otherwise, write intr char.
1037  */
1038 void
1039 interrupt(void)
1040 {
1041         ptyflush();     /* half-hearted */
1042
1043 #ifdef  TCSIG
1044         (void) ioctl(pty, TCSIG, (char *)SIGINT);
1045 #else   /* TCSIG */
1046         init_termbuf();
1047         *pfrontp++ = slctab[SLC_IP].sptr ?
1048                         (unsigned char)*slctab[SLC_IP].sptr : '\177';
1049 #endif  /* TCSIG */
1050 }
1051
1052 /*
1053  * Send quit to process on other side of pty.
1054  * If it is in raw mode, just write NULL;
1055  * otherwise, write quit char.
1056  */
1057 void
1058 sendbrk(void)
1059 {
1060         ptyflush();     /* half-hearted */
1061 #ifdef  TCSIG
1062         (void) ioctl(pty, TCSIG, (char *)SIGQUIT);
1063 #else   /* TCSIG */
1064         init_termbuf();
1065         *pfrontp++ = slctab[SLC_ABORT].sptr ?
1066                         (unsigned char)*slctab[SLC_ABORT].sptr : '\034';
1067 #endif  /* TCSIG */
1068 }
1069
1070 void
1071 sendsusp(void)
1072 {
1073 #ifdef  SIGTSTP
1074         ptyflush();     /* half-hearted */
1075 # ifdef TCSIG
1076         (void) ioctl(pty, TCSIG, (char *)SIGTSTP);
1077 # else  /* TCSIG */
1078         *pfrontp++ = slctab[SLC_SUSP].sptr ?
1079                         (unsigned char)*slctab[SLC_SUSP].sptr : '\032';
1080 # endif /* TCSIG */
1081 #endif  /* SIGTSTP */
1082 }
1083
1084 /*
1085  * When we get an AYT, if ^T is enabled, use that.  Otherwise,
1086  * just send back "[Yes]".
1087  */
1088 void
1089 recv_ayt(void)
1090 {
1091 #if     defined(SIGINFO) && defined(TCSIG)
1092         if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
1093                 (void) ioctl(pty, TCSIG, (char *)SIGINFO);
1094                 return;
1095         }
1096 #endif
1097         output_data("\r\n[Yes]\r\n");
1098 }
1099
1100 void
1101 doeof(void)
1102 {
1103         init_termbuf();
1104
1105 #if     defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN)
1106         if (!tty_isediting()) {
1107                 extern char oldeofc;
1108                 *pfrontp++ = oldeofc;
1109                 return;
1110         }
1111 #endif
1112         *pfrontp++ = slctab[SLC_EOF].sptr ?
1113                         (unsigned char)*slctab[SLC_EOF].sptr : '\004';
1114 }