1 /* 2 * Copyright (c) 1995, 1996, 1998 Theo de Raadt. All rights reserved. 3 * Copyright (c) 1983, 1993, 1994 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #if defined(LIBC_SCCS) && !defined(lint) 32 static char *rcsid = "$OpenBSD: rcmd.c,v 1.47 2003/07/11 22:39:21 deraadt Exp $"; 33 #endif /* LIBC_SCCS and not lint */ 34 35 #include <sys/param.h> 36 #include <sys/socket.h> 37 #include <sys/stat.h> 38 39 #include <netinet/in.h> 40 #include <arpa/inet.h> 41 42 #include <signal.h> 43 #include <fcntl.h> 44 #include <netdb.h> 45 #include <unistd.h> 46 #include <pwd.h> 47 #include <errno.h> 48 #include <stdio.h> 49 #include <ctype.h> 50 #include <string.h> 51 #include <syslog.h> 52 #include <stdlib.h> 53 #include <netgroup.h> 54 55 int __ivaliduser(FILE *, in_addr_t, const char *, const char *); 56 int __ivaliduser_sa(FILE *, struct sockaddr *, socklen_t, 57 const char *, const char *); 58 static int __icheckhost(struct sockaddr *, socklen_t, const char *); 59 static char *__gethostloop(struct sockaddr *, socklen_t); 60 61 int 62 rcmd(ahost, rport, locuser, remuser, cmd, fd2p) 63 char **ahost; 64 in_port_t rport; 65 const char *locuser, *remuser, *cmd; 66 int *fd2p; 67 { 68 return rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, AF_INET); 69 } 70 71 int 72 rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, af) 73 char **ahost; 74 in_port_t rport; 75 const char *locuser, *remuser, *cmd; 76 int *fd2p; 77 int af; 78 { 79 static char hbuf[MAXHOSTNAMELEN]; 80 char pbuf[NI_MAXSERV]; 81 struct addrinfo hints, *res, *r; 82 int error; 83 struct sockaddr_storage from; 84 fd_set *readsp = NULL; 85 sigset_t oldmask, mask; 86 pid_t pid; 87 int s, lport, timo; 88 char c, *p; 89 int refused; 90 91 /* call rcmdsh() with specified remote shell if appropriate. */ 92 if (!issetugid() && (p = getenv("RSH")) && *p) { 93 struct servent *sp = getservbyname("shell", "tcp"); 94 95 if (sp && sp->s_port == rport) 96 return (rcmdsh(ahost, rport, locuser, remuser, 97 cmd, p)); 98 } 99 100 /* use rsh(1) if non-root and remote port is shell. */ 101 if (geteuid()) { 102 struct servent *sp = getservbyname("shell", "tcp"); 103 104 if (sp && sp->s_port == rport) 105 return (rcmdsh(ahost, rport, locuser, remuser, 106 cmd, NULL)); 107 } 108 109 pid = getpid(); 110 snprintf(pbuf, sizeof(pbuf), "%u", ntohs(rport)); 111 memset(&hints, 0, sizeof(hints)); 112 hints.ai_family = af; 113 hints.ai_socktype = SOCK_STREAM; 114 hints.ai_flags = AI_CANONNAME; 115 error = getaddrinfo(*ahost, pbuf, &hints, &res); 116 if (error) { 117 #if 0 118 warnx("%s: %s", *ahost, gai_strerror(error)); 119 #endif 120 return (-1); 121 } 122 if (res->ai_canonname) { 123 strlcpy(hbuf, res->ai_canonname, sizeof(hbuf)); 124 *ahost = hbuf; 125 } else 126 ; /*XXX*/ 127 128 r = res; 129 refused = 0; 130 sigemptyset(&mask); 131 sigaddset(&mask, SIGURG); 132 oldmask = sigprocmask(SIG_BLOCK, &mask, &oldmask); 133 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 134 s = rresvport_af(&lport, r->ai_family); 135 if (s < 0) { 136 if (errno == EAGAIN) 137 (void)fprintf(stderr, 138 "rcmd: socket: All ports in use\n"); 139 else 140 (void)fprintf(stderr, "rcmd: socket: %s\n", 141 strerror(errno)); 142 if (r->ai_next) { 143 r = r->ai_next; 144 continue; 145 } else { 146 sigprocmask(SIG_SETMASK, &oldmask, NULL); 147 freeaddrinfo(res); 148 return (-1); 149 } 150 } 151 fcntl(s, F_SETOWN, pid); 152 if (connect(s, r->ai_addr, r->ai_addrlen) >= 0) 153 break; 154 (void)close(s); 155 if (errno == EADDRINUSE) { 156 lport--; 157 continue; 158 } 159 if (errno == ECONNREFUSED) 160 refused++; 161 if (r->ai_next) { 162 int oerrno = errno; 163 char hbuf[NI_MAXHOST]; 164 #ifdef NI_WITHSCOPEID 165 const int niflags = NI_NUMERICHOST | NI_WITHSCOPEID; 166 #else 167 const int niflags = NI_NUMERICHOST; 168 #endif 169 170 hbuf[0] = '\0'; 171 if (getnameinfo(r->ai_addr, r->ai_addrlen, 172 hbuf, sizeof(hbuf), NULL, 0, niflags) != 0) 173 strlcpy(hbuf, "(invalid)", sizeof hbuf); 174 (void)fprintf(stderr, "connect to address %s: ", hbuf); 175 errno = oerrno; 176 perror(0); 177 r = r->ai_next; 178 hbuf[0] = '\0'; 179 if (getnameinfo(r->ai_addr, r->ai_addrlen, 180 hbuf, sizeof(hbuf), NULL, 0, niflags) != 0) 181 strlcpy(hbuf, "(invalid)", sizeof hbuf); 182 (void)fprintf(stderr, "Trying %s...\n", hbuf); 183 continue; 184 } 185 if (refused && timo <= 16) { 186 (void)sleep(timo); 187 timo *= 2; 188 r = res; 189 refused = 0; 190 continue; 191 } 192 (void)fprintf(stderr, "%s: %s\n", res->ai_canonname, 193 strerror(errno)); 194 sigprocmask(SIG_SETMASK, &oldmask, NULL); 195 freeaddrinfo(res); 196 return (-1); 197 } 198 /* given "af" can be PF_UNSPEC, we need the real af for "s" */ 199 af = r->ai_family; 200 freeaddrinfo(res); 201 #if 0 202 /* 203 * try to rresvport() to the same port. This will make rresvport() 204 * fail it's first bind, resulting in it choosing a random port. 205 */ 206 lport--; 207 #endif 208 if (fd2p == 0) { 209 write(s, "", 1); 210 lport = 0; 211 } else { 212 char num[8]; 213 int s2 = rresvport_af(&lport, af), s3; 214 socklen_t len = sizeof(from); 215 int fdssize = howmany(MAX(s, s2)+1, NFDBITS) * sizeof(fd_mask); 216 217 if (s2 < 0) 218 goto bad; 219 readsp = (fd_set *)malloc(fdssize); 220 if (readsp == NULL) 221 goto bad; 222 listen(s2, 1); 223 (void)snprintf(num, sizeof(num), "%d", lport); 224 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 225 (void)fprintf(stderr, 226 "rcmd: write (setting up stderr): %s\n", 227 strerror(errno)); 228 (void)close(s2); 229 goto bad; 230 } 231 again: 232 bzero(readsp, fdssize); 233 FD_SET(s, readsp); 234 FD_SET(s2, readsp); 235 errno = 0; 236 if (select(MAX(s, s2) + 1, readsp, 0, 0, 0) < 1 || 237 !FD_ISSET(s2, readsp)) { 238 if (errno != 0) 239 (void)fprintf(stderr, 240 "rcmd: select (setting up stderr): %s\n", 241 strerror(errno)); 242 else 243 (void)fprintf(stderr, 244 "select: protocol failure in circuit setup\n"); 245 (void)close(s2); 246 goto bad; 247 } 248 s3 = accept(s2, (struct sockaddr *)&from, &len); 249 /* 250 * XXX careful for ftp bounce attacks. If discovered, shut them 251 * down and check for the real auxiliary channel to connect. 252 */ 253 switch (from.ss_family) { 254 case AF_INET: 255 case AF_INET6: 256 if (getnameinfo((struct sockaddr *)&from, len, 257 NULL, 0, num, sizeof(num), NI_NUMERICSERV) == 0 && 258 atoi(num) != 20) { 259 break; 260 } 261 close(s3); 262 goto again; 263 default: 264 break; 265 } 266 (void)close(s2); 267 if (s3 < 0) { 268 (void)fprintf(stderr, 269 "rcmd: accept: %s\n", strerror(errno)); 270 lport = 0; 271 goto bad; 272 } 273 *fd2p = s3; 274 switch (from.ss_family) { 275 case AF_INET: 276 case AF_INET6: 277 if (getnameinfo((struct sockaddr *)&from, len, 278 NULL, 0, num, sizeof(num), NI_NUMERICSERV) != 0 || 279 (atoi(num) >= IPPORT_RESERVED || 280 atoi(num) < IPPORT_RESERVED / 2)) { 281 (void)fprintf(stderr, 282 "socket: protocol failure in circuit setup.\n"); 283 goto bad2; 284 } 285 break; 286 default: 287 break; 288 } 289 } 290 (void)write(s, locuser, strlen(locuser)+1); 291 (void)write(s, remuser, strlen(remuser)+1); 292 (void)write(s, cmd, strlen(cmd)+1); 293 if (read(s, &c, 1) != 1) { 294 (void)fprintf(stderr, 295 "rcmd: %s: %s\n", *ahost, strerror(errno)); 296 goto bad2; 297 } 298 if (c != 0) { 299 while (read(s, &c, 1) == 1) { 300 (void)write(STDERR_FILENO, &c, 1); 301 if (c == '\n') 302 break; 303 } 304 goto bad2; 305 } 306 sigprocmask(SIG_SETMASK, &oldmask, NULL); 307 free(readsp); 308 return (s); 309 bad2: 310 if (lport) 311 (void)close(*fd2p); 312 bad: 313 if (readsp) 314 free(readsp); 315 (void)close(s); 316 sigprocmask(SIG_SETMASK, &oldmask, NULL); 317 return (-1); 318 } 319 320 int __check_rhosts_file = 1; 321 char *__rcmd_errstr; 322 323 int 324 ruserok(rhost, superuser, ruser, luser) 325 const char *rhost, *ruser, *luser; 326 int superuser; 327 { 328 struct addrinfo hints, *res, *r; 329 int error; 330 331 memset(&hints, 0, sizeof(hints)); 332 hints.ai_family = PF_UNSPEC; 333 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 334 error = getaddrinfo(rhost, "0", &hints, &res); 335 if (error) 336 return (-1); 337 338 for (r = res; r; r = r->ai_next) { 339 if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser, 340 luser) == 0) { 341 freeaddrinfo(res); 342 return (0); 343 } 344 } 345 freeaddrinfo(res); 346 return (-1); 347 } 348 349 /* 350 * New .rhosts strategy: We are passed an ip address. We spin through 351 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 352 * has ip addresses, we don't have to trust a nameserver. When it 353 * contains hostnames, we spin through the list of addresses the nameserver 354 * gives us and look for a match. 355 * 356 * Returns 0 if ok, -1 if not ok. 357 */ 358 int 359 iruserok(raddr, superuser, ruser, luser) 360 u_int32_t raddr; 361 int superuser; 362 const char *ruser, *luser; 363 { 364 struct sockaddr_in sin; 365 366 memset(&sin, 0, sizeof(sin)); 367 sin.sin_family = AF_INET; 368 sin.sin_len = sizeof(struct sockaddr_in); 369 memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr)); 370 return iruserok_sa(&sin, sizeof(struct sockaddr_in), superuser, ruser, 371 luser); 372 } 373 374 int 375 iruserok_sa(raddr, rlen, superuser, ruser, luser) 376 const void *raddr; 377 int rlen; 378 int superuser; 379 const char *ruser, *luser; 380 { 381 struct sockaddr *sa; 382 register char *cp; 383 struct stat sbuf; 384 struct passwd *pwd; 385 FILE *hostf; 386 uid_t uid; 387 int first; 388 char pbuf[MAXPATHLEN]; 389 390 sa = (struct sockaddr *)raddr; 391 first = 1; 392 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 393 again: 394 if (hostf) { 395 if (__ivaliduser_sa(hostf, sa, rlen, luser, ruser) == 0) { 396 (void)fclose(hostf); 397 return (0); 398 } 399 (void)fclose(hostf); 400 } 401 if (first == 1 && (__check_rhosts_file || superuser)) { 402 first = 0; 403 if ((pwd = getpwnam(luser)) == NULL) 404 return (-1); 405 snprintf(pbuf, sizeof pbuf, "%s/.rhosts", pwd->pw_dir); 406 407 /* 408 * Change effective uid while opening .rhosts. If root and 409 * reading an NFS mounted file system, can't read files that 410 * are protected read/write owner only. 411 */ 412 uid = geteuid(); 413 (void)seteuid(pwd->pw_uid); 414 hostf = fopen(pbuf, "r"); 415 (void)seteuid(uid); 416 417 if (hostf == NULL) 418 return (-1); 419 /* 420 * If not a regular file, or is owned by someone other than 421 * user or root or if writeable by anyone but the owner, quit. 422 */ 423 cp = NULL; 424 if (lstat(pbuf, &sbuf) < 0) 425 cp = ".rhosts lstat failed"; 426 else if (!S_ISREG(sbuf.st_mode)) 427 cp = ".rhosts not regular file"; 428 else if (fstat(fileno(hostf), &sbuf) < 0) 429 cp = ".rhosts fstat failed"; 430 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 431 cp = "bad .rhosts owner"; 432 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 433 cp = ".rhosts writable by other than owner"; 434 /* If there were any problems, quit. */ 435 if (cp) { 436 __rcmd_errstr = cp; 437 (void)fclose(hostf); 438 return (-1); 439 } 440 goto again; 441 } 442 return (-1); 443 } 444 445 /* 446 * XXX 447 * Don't make static, used by lpd(8). 448 * 449 * Returns 0 if ok, -1 if not ok. 450 */ 451 int 452 __ivaliduser(hostf, raddrl, luser, ruser) 453 FILE *hostf; 454 in_addr_t raddrl; 455 const char *luser, *ruser; 456 { 457 struct sockaddr_in sin; 458 459 memset(&sin, 0, sizeof(sin)); 460 sin.sin_family = AF_INET; 461 sin.sin_len = sizeof(struct sockaddr_in); 462 memcpy(&sin.sin_addr, &raddrl, sizeof(sin.sin_addr)); 463 return __ivaliduser_sa(hostf, (struct sockaddr *)&sin, sin.sin_len, 464 luser, ruser); 465 } 466 467 int 468 __ivaliduser_sa(hostf, raddr, salen, luser, ruser) 469 FILE *hostf; 470 struct sockaddr *raddr; 471 socklen_t salen; 472 const char *luser, *ruser; 473 { 474 register char *user, *p; 475 char *buf; 476 const char *auser, *ahost; 477 int hostok, userok; 478 char *rhost = (char *)-1; 479 char domain[MAXHOSTNAMELEN]; 480 size_t buflen; 481 482 getdomainname(domain, sizeof(domain)); 483 484 while ((buf = fgetln(hostf, &buflen))) { 485 p = buf; 486 if (*p == '#') 487 continue; 488 while (*p != '\n' && *p != ' ' && *p != '\t' && p < buf + buflen) { 489 if (!isprint(*p)) 490 goto bail; 491 *p = isupper(*p) ? tolower(*p) : *p; 492 p++; 493 } 494 if (p >= buf + buflen) 495 continue; 496 if (*p == ' ' || *p == '\t') { 497 *p++ = '\0'; 498 while ((*p == ' ' || *p == '\t') && p < buf + buflen) 499 p++; 500 if (p >= buf + buflen) 501 continue; 502 user = p; 503 while (*p != '\n' && *p != ' ' && 504 *p != '\t' && p < buf + buflen) { 505 if (!isprint(*p)) 506 goto bail; 507 p++; 508 } 509 } else 510 user = p; 511 *p = '\0'; 512 513 if (p == buf) 514 continue; 515 516 auser = *user ? user : luser; 517 ahost = buf; 518 519 if (strlen(ahost) >= MAXHOSTNAMELEN) 520 continue; 521 522 /* 523 * innetgr() must lookup a hostname (we do not attempt 524 * to change the semantics so that netgroups may have 525 * #.#.#.# addresses in the list.) 526 */ 527 if (ahost[0] == '+') 528 switch (ahost[1]) { 529 case '\0': 530 hostok = 1; 531 break; 532 case '@': 533 if (rhost == (char *)-1) 534 rhost = __gethostloop(raddr, salen); 535 hostok = 0; 536 if (rhost) 537 hostok = innetgr(&ahost[2], rhost, 538 NULL, domain); 539 break; 540 default: 541 hostok = __icheckhost(raddr, salen, &ahost[1]); 542 break; 543 } 544 else if (ahost[0] == '-') 545 switch (ahost[1]) { 546 case '\0': 547 hostok = -1; 548 break; 549 case '@': 550 if (rhost == (char *)-1) 551 rhost = __gethostloop(raddr, salen); 552 hostok = 0; 553 if (rhost) 554 hostok = -innetgr(&ahost[2], rhost, 555 NULL, domain); 556 break; 557 default: 558 hostok = -__icheckhost(raddr, salen, &ahost[1]); 559 break; 560 } 561 else 562 hostok = __icheckhost(raddr, salen, ahost); 563 564 565 if (auser[0] == '+') 566 switch (auser[1]) { 567 case '\0': 568 userok = 1; 569 break; 570 case '@': 571 userok = innetgr(&auser[2], NULL, ruser, 572 domain); 573 break; 574 default: 575 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 576 break; 577 } 578 else if (auser[0] == '-') 579 switch (auser[1]) { 580 case '\0': 581 userok = -1; 582 break; 583 case '@': 584 userok = -innetgr(&auser[2], NULL, ruser, 585 domain); 586 break; 587 default: 588 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 589 break; 590 } 591 else 592 userok = strcmp(ruser, auser) ? 0 : 1; 593 594 /* Check if one component did not match */ 595 if (hostok == 0 || userok == 0) 596 continue; 597 598 /* Check if we got a forbidden pair */ 599 if (userok <= -1 || hostok <= -1) 600 return (-1); 601 602 /* Check if we got a valid pair */ 603 if (hostok >= 1 && userok >= 1) 604 return (0); 605 } 606 bail: 607 return (-1); 608 } 609 610 /* 611 * Returns "true" if match, 0 if no match. If we do not find any 612 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 613 * 614 * NI_WITHSCOPEID is useful for comparing sin6_scope_id portion 615 * if af == AF_INET6. 616 */ 617 static int 618 __icheckhost(raddr, salen, lhost) 619 struct sockaddr *raddr; 620 socklen_t salen; 621 const char *lhost; 622 { 623 struct addrinfo hints, *res, *r; 624 char h1[NI_MAXHOST], h2[NI_MAXHOST]; 625 int error; 626 #ifdef NI_WITHSCOPEID 627 const int niflags = NI_NUMERICHOST | NI_WITHSCOPEID; 628 #else 629 const int niflags = NI_NUMERICHOST; 630 #endif 631 632 h1[0] = '\0'; 633 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, 634 niflags) != 0) 635 return (0); 636 637 /* Resolve laddr into sockaddr */ 638 memset(&hints, 0, sizeof(hints)); 639 hints.ai_family = raddr->sa_family; 640 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 641 res = NULL; 642 error = getaddrinfo(lhost, "0", &hints, &res); 643 if (error) 644 return (0); 645 646 /* 647 * Try string comparisons between raddr and laddr. 648 */ 649 for (r = res; r; r = r->ai_next) { 650 h2[0] = '\0'; 651 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2), 652 NULL, 0, niflags) != 0) 653 continue; 654 if (strcmp(h1, h2) == 0) { 655 freeaddrinfo(res); 656 return (1); 657 } 658 } 659 660 /* No match. */ 661 freeaddrinfo(res); 662 return (0); 663 } 664 665 /* 666 * Return the hostname associated with the supplied address. 667 * Do a reverse lookup as well for security. If a loop cannot 668 * be found, pack the result of inet_ntoa() into the string. 669 * 670 * NI_WITHSCOPEID is useful for comparing sin6_scope_id portion 671 * if af == AF_INET6. 672 */ 673 static char * 674 __gethostloop(raddr, salen) 675 struct sockaddr *raddr; 676 socklen_t salen; 677 { 678 static char remotehost[NI_MAXHOST]; 679 char h1[NI_MAXHOST], h2[NI_MAXHOST]; 680 struct addrinfo hints, *res, *r; 681 int error; 682 #ifdef NI_WITHSCOPEID 683 const int niflags = NI_NUMERICHOST | NI_WITHSCOPEID; 684 #else 685 const int niflags = NI_NUMERICHOST; 686 #endif 687 688 h1[0] = remotehost[0] = '\0'; 689 if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost), 690 NULL, 0, NI_NAMEREQD) != 0) 691 return (NULL); 692 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, 693 niflags) != 0) 694 return (NULL); 695 696 /* 697 * Look up the name and check that the supplied 698 * address is in the list 699 */ 700 memset(&hints, 0, sizeof(hints)); 701 hints.ai_family = raddr->sa_family; 702 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 703 hints.ai_flags = AI_CANONNAME; 704 res = NULL; 705 error = getaddrinfo(remotehost, "0", &hints, &res); 706 if (error) 707 return (NULL); 708 709 for (r = res; r; r = r->ai_next) { 710 h2[0] = '\0'; 711 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2), 712 NULL, 0, niflags) != 0) 713 continue; 714 if (strcmp(h1, h2) == 0) { 715 freeaddrinfo(res); 716 return (remotehost); 717 } 718 } 719 720 /* 721 * either the DNS adminstrator has made a configuration 722 * mistake, or someone has attempted to spoof us 723 */ 724 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 725 h1, res->ai_canonname ? res->ai_canonname : remotehost); 726 freeaddrinfo(res); 727 return (NULL); 728 } 729