libexec/rshd/rshd.c

   1 /*-
   2  * Copyright (c) 1988, 1989, 1992, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1988, 1989, 1992, 1993, 1994 The Regents of the University of California.  All rights reserved.
  30  * @(#)rshd.c   8.2 (Berkeley) 4/6/94
  31  * $FreeBSD: src/libexec/rshd/rshd.c,v 1.30.2.5 2002/05/14 22:27:21 des Exp $
  32  */
  33
  34 /*
  35  * remote shell server:
  36  *      [port]\0
  37  *      remuser\0
  38  *      locuser\0
  39  *      command\0
  40  *      data
  41  */
  42 #include <sys/param.h>
  43 #include <sys/ioctl.h>
  44 #include <sys/time.h>
  45 #include <sys/socket.h>
  46
  47 #include <netinet/in_systm.h>
  48 #include <netinet/in.h>
  49 #include <netinet/ip.h>
  50 #include <netinet/tcp.h>
  51 #include <arpa/inet.h>
  52 #include <netdb.h>
  53
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <libutil.h>
  57 #include <paths.h>
  58 #include <pwd.h>
  59 #include <signal.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63 #include <syslog.h>
  64 #include <unistd.h>
  65 #include <stdarg.h>
  66 #ifdef  LOGIN_CAP
  67 #include <login_cap.h>
  68 #endif
  69
  70 /* wrapper for KAME-special getnameinfo() */
  71 #ifndef NI_WITHSCOPEID
  72 #define NI_WITHSCOPEID  0
  73 #endif
  74
  75 extern int __check_rhosts_file;
  76 extern char *__rcmd_errstr;     /* syslog hook from libc/net/rcmd.c. */
  77
  78 int     keepalive = 1;
  79 int     log_success;            /* If TRUE, log all successful accesses */
  80 int     sent_null;
  81 int     no_delay;
  82 #ifdef CRYPT
  83 int     doencrypt = 0;
  84 #endif
  85
  86 union sockunion {
  87         struct sockinet {
  88                 u_char si_len;
  89                 u_char si_family;
  90                 u_short si_port;
  91         } su_si;
  92         struct sockaddr_in  su_sin;
  93         struct sockaddr_in6 su_sin6;
  94 };
  95 #define su_len          su_si.si_len
  96 #define su_family       su_si.si_family
  97 #define su_port         su_si.si_port
  98
  99 void     doit(union sockunion *);
 100 void     error(const char *, ...) __printflike(1, 2);
 101 void     getstr(char *, int, const char *);
 102 int      local_domain(char *);
 103 char    *topdomain(char *);
 104 void     usage(void);
 105
 106 char    slash[] = "/";
 107 char    bshell[] = _PATH_BSHELL;
 108
 109 #define OPTIONS "alnDL"
 110
 111 int
 112 main(int argc, char *argv[])
 113 {
 114         struct linger linger;
 115         socklen_t fromlen;
 116         int ch, on = 1;
 117         struct sockaddr_storage from;
 118
 119         openlog("rshd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
 120
 121         opterr = 0;
 122         while ((ch = getopt(argc, argv, OPTIONS)) != -1)
 123                 switch (ch) {
 124                 case 'a':
 125                         /* ignored for compatibility */
 126                         break;
 127                 case 'l':
 128                         __check_rhosts_file = 0;
 129                         break;
 130                 case 'n':
 131                         keepalive = 0;
 132                         break;
 133 #ifdef CRYPT
 134                 case 'x':
 135                         doencrypt = 1;
 136                         break;
 137 #endif
 138                 case 'D':
 139                         no_delay = 1;
 140                         break;
 141                 case 'L':
 142                         log_success = 1;
 143                         break;
 144                 case '?':
 145                 default:
 146                         usage();
 147                         break;
 148                 }
 149
 150         argc -= optind;
 151         argv += optind;
 152
 153 #ifdef CRYPT
 154         if (doencrypt) {
 155                 syslog(LOG_ERR, "-k is required for -x");
 156                 exit(2);
 157         }
 158 #endif
 159
 160         fromlen = sizeof (from);
 161         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 162                 syslog(LOG_ERR, "getpeername: %m");
 163                 exit(1);
 164         }
 165         if (keepalive &&
 166             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on,
 167             sizeof(on)) < 0)
 168                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 169         linger.l_onoff = 1;
 170         linger.l_linger = 60;                   /* XXX */
 171         if (setsockopt(0, SOL_SOCKET, SO_LINGER, (char *)&linger,
 172             sizeof (linger)) < 0)
 173                 syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m");
 174         if (no_delay &&
 175             setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
 176                 syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
 177         doit((union sockunion *)&from);
 178         /* NOTREACHED */
 179         return(0);
 180 }
 181
 182 char    username[20] = "USER=";
 183 char    homedir[64] = "HOME=";
 184 char    shell[64] = "SHELL=";
 185 char    path[100] = "PATH=";
 186 char    *envinit[] =
 187             {homedir, shell, path, username, 0};
 188 char    **environ;
 189
 190 void
 191 doit(union sockunion *fromp)
 192 {
 193         struct passwd *pwd;
 194         u_short port;
 195         fd_set ready, readfrom;
 196         int cc, nfd, pv[2], pid, s;
 197         int one = 1;
 198         const char *errorstr;
 199         char *cp, sig, buf[BUFSIZ];
 200         char cmdbuf[NCARGS+1], locuser[16], remuser[16];
 201         char fromhost[2 * MAXHOSTNAMELEN + 1];
 202         char numericname[INET6_ADDRSTRLEN];
 203         int af = fromp->su_family, gaierror;
 204 #ifdef  CRYPT
 205         int rc;
 206         int pv1[2], pv2[2];
 207 #endif
 208 #ifdef  LOGIN_CAP
 209         login_cap_t *lc;
 210 #endif
 211
 212         signal(SIGINT, SIG_DFL);
 213         signal(SIGQUIT, SIG_DFL);
 214         signal(SIGTERM, SIG_DFL);
 215         fromp->su_port = ntohs((u_short)fromp->su_port);
 216         if (af != AF_INET
 217 #ifdef INET6
 218             && af != AF_INET6
 219 #endif
 220             ) {
 221                 syslog(LOG_ERR, "malformed \"from\" address (af %d)\n", af);
 222                 exit(1);
 223         }
 224         gaierror = getnameinfo((struct sockaddr *)fromp, fromp->su_len,
 225             numericname, sizeof(numericname), NULL, 0,
 226             NI_NUMERICHOST|NI_WITHSCOPEID);
 227         if (gaierror != 0) {
 228                 syslog(LOG_ERR, "malformed \"from\" address (af %d): %s", af,
 229                     gai_strerror(gaierror));
 230                 exit(1);
 231         }
 232 #ifdef IP_OPTIONS
 233       if (af == AF_INET) {
 234         u_char optbuf[BUFSIZ/3];
 235         socklen_t optsize = sizeof(optbuf), i;
 236         int ipproto;
 237         struct protoent *ip;
 238
 239         if ((ip = getprotobyname("ip")) != NULL)
 240                 ipproto = ip->p_proto;
 241         else
 242                 ipproto = IPPROTO_IP;
 243         if (!getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf, &optsize) &&
 244             optsize != 0) {
 245                 for (i = 0; i < optsize; ) {
 246                         u_char c = optbuf[i];
 247                         if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
 248                                 syslog(LOG_NOTICE,
 249                                         "connection refused from %s with IP option %s",
 250                                         numericname,
 251                                         c == IPOPT_LSRR ? "LSRR" : "SSRR");
 252                                 exit(1);
 253                         }
 254                         if (c == IPOPT_EOL)
 255                                 break;
 256                         i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
 257                 }
 258         }
 259       }
 260 #endif
 261
 262         if (fromp->su_port >= IPPORT_RESERVED ||
 263             fromp->su_port < IPPORT_RESERVED/2) {
 264                 syslog(LOG_NOTICE|LOG_AUTH,
 265                     "connection from %s on illegal port %u",
 266                     numericname,
 267                     fromp->su_port);
 268                 exit(1);
 269         }
 270
 271         alarm(60);
 272         port = 0;
 273         s = 0;          /* not set or used if port == 0 */
 274         for (;;) {
 275                 char c;
 276                 if ((cc = read(STDIN_FILENO, &c, 1)) != 1) {
 277                         if (cc < 0)
 278                                 syslog(LOG_NOTICE, "read: %m");
 279                         shutdown(0, SHUT_RDWR);
 280                         exit(1);
 281                 }
 282                 if (c == 0)
 283                         break;
 284                 port = port * 10 + c - '0';
 285         }
 286
 287         alarm(0);
 288         if (port != 0) {
 289                 int lport = IPPORT_RESERVED - 1;
 290                 s = rresvport_af(&lport, af);
 291                 if (s < 0) {
 292                         syslog(LOG_ERR, "can't get stderr port: %m");
 293                         exit(1);
 294                 }
 295                 if (port >= IPPORT_RESERVED ||
 296                     port < IPPORT_RESERVED/2) {
 297                         syslog(LOG_NOTICE|LOG_AUTH,
 298                             "2nd socket from %s on unreserved port %u",
 299                             numericname,
 300                             port);
 301                         exit(1);
 302                 }
 303                 fromp->su_port = htons(port);
 304                 if (connect(s, (struct sockaddr *)fromp, fromp->su_len) < 0) {
 305                         syslog(LOG_INFO, "connect second port %d: %m", port);
 306                         exit(1);
 307                 }
 308         }
 309
 310         errorstr = NULL;
 311         realhostname_sa(fromhost, sizeof(fromhost) - 1,
 312                         (struct sockaddr *)fromp,
 313                         fromp->su_len);
 314         fromhost[sizeof(fromhost) - 1] = '\0';
 315
 316 #ifdef CRYPT
 317         if (doencrypt && af == AF_INET) {
 318                 struct sockaddr_in local_addr;
 319                 rc = sizeof(local_addr);
 320                 if (getsockname(0, (struct sockaddr *)&local_addr,
 321                     &rc) < 0) {
 322                         syslog(LOG_ERR, "getsockname: %m");
 323                         error("rlogind: getsockname: %m");
 324                         exit(1);
 325                 }
 326                 authopts = KOPT_DO_MUTUAL;
 327                 rc = krb_recvauth(authopts, 0, ticket,
 328                         "rcmd", instance, &fromaddr,
 329                         &local_addr, kdata, "", schedule,
 330                         version);
 331                 des_set_key(&kdata->session, schedule);
 332         }
 333 #endif
 334         alarm(60);
 335         getstr(remuser, sizeof(remuser), "remuser");
 336         getstr(locuser, sizeof(locuser), "locuser");
 337         getstr(cmdbuf, sizeof(cmdbuf), "command");
 338         alarm(0);
 339         setpwent();
 340         pwd = getpwnam(locuser);
 341         if (pwd == NULL) {
 342                 syslog(LOG_INFO|LOG_AUTH,
 343                     "%s@%s as %s: unknown login. cmd='%.80s'",
 344                     remuser, fromhost, locuser, cmdbuf);
 345                 if (errorstr == NULL)
 346                         errorstr = "Login incorrect.\n";
 347                 goto fail;
 348         }
 349 #ifdef  LOGIN_CAP
 350         lc = login_getpwclass(pwd);
 351 #endif
 352         if (chdir(pwd->pw_dir) < 0) {
 353 #ifdef  LOGIN_CAP
 354                 if (chdir("/") < 0 ||
 355                     login_getcapbool(lc, "requirehome", !!pwd->pw_uid)) {
 356                         syslog(LOG_INFO|LOG_AUTH,
 357                         "%s@%s as %s: no home directory. cmd='%.80s'",
 358                         remuser, fromhost, locuser, cmdbuf);
 359                         error("No remote home directory.\n");
 360                         exit(0);
 361                 }
 362 #else
 363                 chdir("/");
 364 #ifdef notdef
 365                 syslog(LOG_INFO|LOG_AUTH,
 366                     "%s@%s as %s: no home directory. cmd='%.80s'",
 367                     remuser, fromhost, locuser, cmdbuf);
 368                 error("No remote directory.\n");
 369                 exit(1);
 370 #endif
 371 #endif
 372                 pwd->pw_dir = slash;
 373         }
 374
 375                 if (errorstr ||
 376                     (pwd->pw_expire && time(NULL) >= pwd->pw_expire) ||
 377                     iruserok_sa(fromp, fromp->su_len, pwd->pw_uid == 0,
 378                                  remuser, locuser) < 0) {
 379                         if (__rcmd_errstr) {
 380                                 syslog(LOG_INFO|LOG_AUTH,
 381                             "%s@%s as %s: permission denied (%s). cmd='%.80s'",
 382                                     remuser, fromhost, locuser, __rcmd_errstr,
 383                                     cmdbuf);
 384                         } else {
 385                                 syslog(LOG_INFO|LOG_AUTH,
 386                             "%s@%s as %s: permission denied. cmd='%.80s'",
 387                                     remuser, fromhost, locuser, cmdbuf);
 388                         }
 389 fail:
 390                         if (errorstr == NULL)
 391                                 errorstr = "Login incorrect.\n";
 392                         error(errorstr, fromhost);
 393                         exit(1);
 394                 }
 395
 396         if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK)) {
 397                 error("Logins currently disabled.\n");
 398                 exit(1);
 399         }
 400 #ifdef  LOGIN_CAP
 401         if (lc != NULL && fromp->su_family == AF_INET) {        /*XXX*/
 402                 char    remote_ip[MAXHOSTNAMELEN];
 403
 404                 strncpy(remote_ip, numericname,
 405                         sizeof(remote_ip) - 1);
 406                 remote_ip[sizeof(remote_ip) - 1] = 0;
 407                 if (!auth_hostok(lc, fromhost, remote_ip)) {
 408                         syslog(LOG_INFO|LOG_AUTH,
 409                             "%s@%s as %s: permission denied (%s). cmd='%.80s'",
 410                             remuser, fromhost, locuser, __rcmd_errstr,
 411                             cmdbuf);
 412                         error("Login incorrect.\n");
 413                         exit(1);
 414                 }
 415                 if (!auth_timeok(lc, time(NULL))) {
 416                         error("Logins not available right now\n");
 417                         exit(1);
 418                 }
 419         }
 420 #endif  /* !LOGIN_CAP */
 421 #if     BSD > 43
 422         /* before fork, while we're session leader */
 423         if (setlogin(pwd->pw_name) < 0)
 424                 syslog(LOG_ERR, "setlogin() failed: %m");
 425 #endif
 426
 427         write(STDERR_FILENO, "\0", 1);
 428         sent_null = 1;
 429
 430         if (port) {
 431                 if (pipe(pv) < 0) {
 432                         error("Can't make pipe.\n");
 433                         exit(1);
 434                 }
 435 #ifdef CRYPT
 436                 if (doencrypt) {
 437                         if (pipe(pv1) < 0) {
 438                                 error("Can't make 2nd pipe.\n");
 439                                 exit(1);
 440                         }
 441                         if (pipe(pv2) < 0) {
 442                                 error("Can't make 3rd pipe.\n");
 443                                 exit(1);
 444                         }
 445                 }
 446 #endif
 447                 pid = fork();
 448                 if (pid == -1)  {
 449                         error("Can't fork; try again.\n");
 450                         exit(1);
 451                 }
 452                 if (pid) {
 453 #ifdef CRYPT
 454                         if (doencrypt) {
 455                                 static char msg[] = SECURE_MESSAGE;
 456                                 close(pv1[1]);
 457                                 close(pv2[1]);
 458                                 des_enc_write(s, msg, sizeof(msg) - 1,
 459                                         schedule, &kdata->session);
 460
 461                         } else
 462 #endif
 463                         {
 464                                 close(0);
 465                                 close(1);
 466                         }
 467                         close(2);
 468                         close(pv[1]);
 469
 470                         FD_ZERO(&readfrom);
 471                         FD_SET(s, &readfrom);
 472                         FD_SET(pv[0], &readfrom);
 473                         if (pv[0] > s)
 474                                 nfd = pv[0];
 475                         else
 476                                 nfd = s;
 477 #ifdef CRYPT
 478                         if (doencrypt) {
 479                                 FD_ZERO(&writeto);
 480                                 FD_SET(pv2[0], &writeto);
 481                                 FD_SET(pv1[0], &readfrom);
 482
 483                                 nfd = MAX(nfd, pv2[0]);
 484                                 nfd = MAX(nfd, pv1[0]);
 485                         } else
 486 #endif
 487                                 ioctl(pv[0], FIONBIO, (char *)&one);
 488
 489                         /* should set s nbio! */
 490                         nfd++;
 491                         do {
 492                                 ready = readfrom;
 493 #ifdef CRYPT
 494                                 if (doencrypt) {
 495                                         wready = writeto;
 496                                         if (select(nfd, &ready,
 497                                             &wready, NULL,
 498                                             NULL) < 0)
 499                                                 break;
 500                                 } else
 501 #endif
 502                                         if (select(nfd, &ready, NULL,
 503                                           NULL, NULL) < 0)
 504                                                 break;
 505                                 if (FD_ISSET(s, &ready)) {
 506                                         int     ret;
 507 #ifdef CRYPT
 508                                         if (doencrypt)
 509                                                 ret = des_enc_read(s, &sig, 1,
 510                                                 schedule, &kdata->session);
 511                                         else
 512 #endif
 513                                                 ret = read(s, &sig, 1);
 514                                         if (ret <= 0)
 515                                                 FD_CLR(s, &readfrom);
 516                                         else
 517                                                 killpg(pid, sig);
 518                                 }
 519                                 if (FD_ISSET(pv[0], &ready)) {
 520                                         errno = 0;
 521                                         cc = read(pv[0], buf, sizeof(buf));
 522                                         if (cc <= 0) {
 523                                                 shutdown(s, SHUT_RDWR);
 524                                                 FD_CLR(pv[0], &readfrom);
 525                                         } else {
 526 #ifdef CRYPT
 527                                                 if (doencrypt) {
 528                                                         des_enc_write(s, buf,
 529                                                             cc, schedule,
 530                                                             &kdata->session);
 531                                                 } else
 532 #endif
 533                                                         write(s, buf, cc);
 534                                         }
 535                                 }
 536 #ifdef CRYPT
 537                                 if (doencrypt && FD_ISSET(pv1[0], &ready)) {
 538                                         errno = 0;
 539                                         cc = read(pv1[0], buf, sizeof(buf));
 540                                         if (cc <= 0) {
 541                                                 shutdown(pv1[0], SHUT_RDWR);
 542                                                 FD_CLR(pv1[0], &readfrom);
 543                                         } else {
 544                                                 des_enc_write(STDOUT_FILENO,
 545                                                     buf, cc, schedule,
 546                                                     &kdata->session);
 547                                         }
 548                                 }
 549
 550                                 if (doencrypt && FD_ISSET(pv2[0], &wready)) {
 551                                         errno = 0;
 552                                         cc = des_enc_read(STDIN_FILENO,
 553                                             buf, sizeof(buf),
 554                                                 schedule, &kdata->session);
 555                                         if (cc <= 0) {
 556                                                 shutdown(pv2[0], SHUT_RDWR);
 557                                                 FD_CLR(pv2[0], &writeto);
 558                                         } else {
 559                                                 write(pv2[0], buf, cc);
 560                                         }
 561                                 }
 562 #endif
 563
 564                         } while (FD_ISSET(s, &readfrom) ||
 565 #ifdef CRYPT
 566                             (doencrypt && FD_ISSET(pv1[0], &readfrom)) ||
 567 #endif
 568                             FD_ISSET(pv[0], &readfrom));
 569                         exit(0);
 570                 }
 571                 setpgrp(0, getpid());
 572                 close(s);
 573                 close(pv[0]);
 574 #ifdef CRYPT
 575                 if (doencrypt) {
 576                         close(pv1[0]); close(pv2[0]);
 577                         dup2(pv1[1], 1);
 578                         dup2(pv2[1], 0);
 579                         close(pv1[1]);
 580                         close(pv2[1]);
 581                 }
 582 #endif
 583                 dup2(pv[1], 2);
 584                 close(pv[1]);
 585         }
 586         if (*pwd->pw_shell == '\0')
 587                 pwd->pw_shell = bshell;
 588         environ = envinit;
 589         strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
 590         strcat(path, _PATH_DEFPATH);
 591         strncat(shell, pwd->pw_shell, sizeof(shell)-7);
 592         strncat(username, pwd->pw_name, sizeof(username)-6);
 593         cp = strrchr(pwd->pw_shell, '/');
 594         if (cp)
 595                 cp++;
 596         else
 597                 cp = pwd->pw_shell;
 598 #ifdef  LOGIN_CAP
 599         if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL) != 0) {
 600                 syslog(LOG_ERR, "setusercontext: %m");
 601                 exit(1);
 602         }
 603         login_close(lc);
 604 #else
 605         setgid((gid_t)pwd->pw_gid);
 606         initgroups(pwd->pw_name, pwd->pw_gid);
 607         setuid((uid_t)pwd->pw_uid);
 608 #endif
 609         endpwent();
 610         if (log_success || pwd->pw_uid == 0) {
 611                     syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'",
 612                         remuser, fromhost, locuser, cmdbuf);
 613         }
 614         execl(pwd->pw_shell, cp, "-c", cmdbuf, NULL);
 615         perror(pwd->pw_shell);
 616         exit(1);
 617 }
 618
 619 /*
 620  * Report error to client.  Note: can't be used until second socket has
 621  * connected to client, or older clients will hang waiting for that
 622  * connection first.
 623  */
 624
 625 void
 626 error(const char *fmt, ...)
 627 {
 628         va_list ap;
 629         int len;
 630         char *bp, buf[BUFSIZ];
 631         va_start(ap, fmt);
 632         bp = buf;
 633         if (sent_null == 0) {
 634                 *bp++ = 1;
 635                 len = 1;
 636         } else
 637                 len = 0;
 638         vsnprintf(bp, sizeof(buf) - 1, fmt, ap);
 639         write(STDERR_FILENO, buf, len + strlen(bp));
 640 }
 641
 642 void
 643 getstr(char *buf, int cnt, const char *err)
 644 {
 645         char c;
 646
 647         do {
 648                 if (read(STDIN_FILENO, &c, 1) != 1)
 649                         exit(1);
 650                 *buf++ = c;
 651                 if (--cnt == 0) {
 652                         error("%s too long\n", err);
 653                         exit(1);
 654                 }
 655         } while (c != 0);
 656 }
 657
 658 /*
 659  * Check whether host h is in our local domain,
 660  * defined as sharing the last two components of the domain part,
 661  * or the entire domain part if the local domain has only one component.
 662  * If either name is unqualified (contains no '.'),
 663  * assume that the host is local, as it will be
 664  * interpreted as such.
 665  */
 666 int
 667 local_domain(char *h)
 668 {
 669         char localhost[MAXHOSTNAMELEN];
 670         char *p1, *p2;
 671
 672         localhost[0] = 0;
 673         gethostname(localhost, sizeof(localhost) - 1);
 674         localhost[sizeof(localhost) - 1] = '\0';
 675         p1 = topdomain(localhost);
 676         p2 = topdomain(h);
 677         if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
 678                 return (1);
 679         return (0);
 680 }
 681
 682 char *
 683 topdomain(char *h)
 684 {
 685         char *p, *maybe = NULL;
 686         int dots = 0;
 687
 688         for (p = h + strlen(h); p >= h; p--) {
 689                 if (*p == '.') {
 690                         if (++dots == 2)
 691                                 return (p);
 692                         maybe = p;
 693                 }
 694         }
 695         return (maybe);
 696 }
 697
 698 void
 699 usage(void)
 700 {
 701
 702         syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS);
 703         exit(2);
 704 }