1 /* 2 * Copyright (c) 1990, 1991, 1992, 1993, 1996 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: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 */ 21 22 #ifndef lint 23 static const char copyright[] = 24 "@(#) Copyright (c) 1990, 1991, 1992, 1993, 1996\n\ 25 The Regents of the University of California. All rights reserved.\n"; 26 #endif /* not lint */ 27 28 #ifndef lint 29 static const char rcsid[] = 30 "$FreeBSD$"; 31 #endif /* not lint */ 32 33 /* 34 * rarpd - Reverse ARP Daemon 35 * 36 * Usage: rarpd -a [ -dfsv ] [ hostname ] 37 * rarpd [ -dfsv ] interface [ hostname ] 38 * 39 * 'hostname' is optional solely for backwards compatibility with Sun's rarpd. 40 * Currently, the argument is ignored. 41 */ 42 #include <sys/param.h> 43 #include <sys/file.h> 44 #include <sys/ioctl.h> 45 #include <sys/socket.h> 46 #include <sys/time.h> 47 48 #include <net/bpf.h> 49 #include <net/ethernet.h> 50 #include <net/if.h> 51 #include <net/if_types.h> 52 #include <net/if_dl.h> 53 #include <net/route.h> 54 55 #include <netinet/in.h> 56 #include <netinet/if_ether.h> 57 58 #include <arpa/inet.h> 59 60 #include <errno.h> 61 #include <netdb.h> 62 #include <stdarg.h> 63 #include <stdio.h> 64 #include <string.h> 65 #include <syslog.h> 66 #include <stdlib.h> 67 #include <unistd.h> 68 69 #if defined(SUNOS4) || defined(__FreeBSD__) /* XXX */ 70 #define HAVE_DIRENT_H 71 #endif 72 73 #ifdef HAVE_DIRENT_H 74 #include <dirent.h> 75 #else 76 #include <sys/dir.h> 77 #endif 78 79 /* Cast a struct sockaddr to a structaddr_in */ 80 #define SATOSIN(sa) ((struct sockaddr_in *)(sa)) 81 82 #ifndef TFTP_DIR 83 #define TFTP_DIR "/tftpboot" 84 #endif 85 86 #if BSD >= 199200 87 #define ARPSECS (20 * 60) /* as per code in netinet/if_ether.c */ 88 #define REVARP_REQUEST ARPOP_REVREQUEST 89 #define REVARP_REPLY ARPOP_REVREPLY 90 #endif 91 92 #ifndef ETHERTYPE_REVARP 93 #define ETHERTYPE_REVARP 0x8035 94 #define REVARP_REQUEST 3 95 #define REVARP_REPLY 4 96 #endif 97 98 /* 99 * Map field names in ether_arp struct. What a pain in the neck. 100 */ 101 #ifdef SUNOS3 102 #undef arp_sha 103 #undef arp_spa 104 #undef arp_tha 105 #undef arp_tpa 106 #define arp_sha arp_xsha 107 #define arp_spa arp_xspa 108 #define arp_tha arp_xtha 109 #define arp_tpa arp_xtpa 110 #endif 111 112 /* 113 * The structure for each interface. 114 */ 115 struct if_info { 116 struct if_info *ii_next; 117 int ii_fd; /* BPF file descriptor */ 118 u_long ii_ipaddr; /* IP address of this interface */ 119 u_long ii_netmask; /* subnet or net mask */ 120 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 121 char ii_ifname[sizeof(((struct ifreq *)0)->ifr_name) + 1]; 122 }; 123 124 /* 125 * The list of all interfaces that are being listened to. rarp_loop() 126 * "selects" on the descriptors in this list. 127 */ 128 struct if_info *iflist; 129 130 int verbose; /* verbose messages */ 131 int s; /* inet datagram socket */ 132 const char *tftp_dir = TFTP_DIR; /* tftp directory */ 133 134 int dflag; /* messages to stdout/stderr, not syslog(3) */ 135 int sflag; /* ignore /tftpboot */ 136 137 static u_char zero[6]; 138 139 static int bpf_open(void); 140 static u_long choose_ipaddr(u_long **, u_long, u_long); 141 static char *eatoa(u_char *); 142 static int expand_syslog_m(const char *fmt, char **newfmt); 143 static void init(char *); 144 static void init_one(struct ifreq *, char *); 145 static char *intoa(u_long); 146 static u_long ipaddrtonetmask(u_long); 147 static void logmsg(int, const char *, ...) __printflike(2, 3); 148 static int rarp_bootable(u_long); 149 static int rarp_check(u_char *, u_int); 150 static void rarp_loop(void); 151 static int rarp_open(char *); 152 static void rarp_process(struct if_info *, u_char *, u_int); 153 static void rarp_reply(struct if_info *, struct ether_header *, 154 u_long, u_int); 155 static void update_arptab(u_char *, u_long); 156 static void usage(void); 157 158 int 159 main(int argc, char *argv[]) 160 { 161 int op; 162 char *ifname, *hostname, *name; 163 164 int aflag = 0; /* listen on "all" interfaces */ 165 int fflag = 0; /* don't fork */ 166 167 if ((name = strrchr(argv[0], '/')) != NULL) 168 ++name; 169 else 170 name = argv[0]; 171 if (*name == '-') 172 ++name; 173 174 /* 175 * All error reporting is done through syslog, unless -d is specified 176 */ 177 openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON); 178 179 opterr = 0; 180 while ((op = getopt(argc, argv, "adfst:v")) != -1) { 181 switch (op) { 182 case 'a': 183 ++aflag; 184 break; 185 186 case 'd': 187 ++dflag; 188 break; 189 190 case 'f': 191 ++fflag; 192 break; 193 194 case 's': 195 ++sflag; 196 break; 197 198 case 't': 199 tftp_dir = optarg; 200 break; 201 202 case 'v': 203 ++verbose; 204 break; 205 206 default: 207 usage(); 208 /* NOTREACHED */ 209 } 210 } 211 ifname = argv[optind++]; 212 hostname = ifname ? argv[optind] : NULL; 213 if ((aflag && ifname) || (!aflag && ifname == NULL)) 214 usage(); 215 216 if (aflag) 217 init(NULL); 218 else 219 init(ifname); 220 221 if (!fflag) { 222 if (daemon(0,0)) { 223 logmsg(LOG_ERR, "cannot fork"); 224 exit(1); 225 } 226 } 227 rarp_loop(); 228 return(0); 229 } 230 231 /* 232 * Add to the interface list. 233 */ 234 void 235 init_one(struct ifreq *ifrp, char *target) 236 { 237 struct if_info *ii; 238 struct sockaddr_dl *ll; 239 int family; 240 struct ifreq ifr; 241 242 family = ifrp->ifr_addr.sa_family; 243 switch (family) { 244 245 case AF_INET: 246 #if BSD >= 199100 247 case AF_LINK: 248 #endif 249 (void)strncpy(ifr.ifr_name, ifrp->ifr_name, 250 sizeof(ifrp->ifr_name)); 251 if (ioctl(s, SIOCGIFFLAGS, (char *)&ifr) == -1) { 252 logmsg(LOG_ERR, 253 "SIOCGIFFLAGS: %.*s: %m", 254 (int)sizeof(ifrp->ifr_name), ifrp->ifr_name); 255 exit(1); 256 } 257 if ((ifr.ifr_flags & IFF_UP) == 0 || 258 (ifr.ifr_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) != 0) 259 return; 260 break; 261 262 263 default: 264 return; 265 } 266 267 /* Don't bother going any further if not the target interface */ 268 if (target != NULL && 269 strncmp(ifrp->ifr_name, target, sizeof(ifrp->ifr_name)) != 0) 270 return; 271 272 /* Look for interface in list */ 273 for (ii = iflist; ii != NULL; ii = ii->ii_next) 274 if (strncmp(ifrp->ifr_name, ii->ii_ifname, 275 sizeof(ifrp->ifr_name)) == 0) 276 break; 277 278 /* Allocate a new one if not found */ 279 if (ii == NULL) { 280 ii = (struct if_info *)malloc(sizeof(*ii)); 281 if (ii == NULL) { 282 logmsg(LOG_ERR, "malloc: %m"); 283 exit(1); 284 } 285 bzero(ii, sizeof(*ii)); 286 ii->ii_fd = -1; 287 (void)strncpy(ii->ii_ifname, ifrp->ifr_name, 288 sizeof(ifrp->ifr_name)); 289 ii->ii_ifname[sizeof(ii->ii_ifname) - 1] = '\0'; 290 ii->ii_next = iflist; 291 iflist = ii; 292 } 293 294 switch (family) { 295 296 case AF_INET: 297 if (ioctl(s, SIOCGIFADDR, (char *)&ifr) == -1) { 298 logmsg(LOG_ERR, "ipaddr SIOCGIFADDR: %s: %m", 299 ii->ii_ifname); 300 exit(1); 301 } 302 ii->ii_ipaddr = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr; 303 if (ioctl(s, SIOCGIFNETMASK, (char *)&ifr) == -1) { 304 logmsg(LOG_ERR, "SIOCGIFNETMASK: %m"); 305 exit(1); 306 } 307 ii->ii_netmask = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr; 308 if (ii->ii_netmask == 0) 309 ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr); 310 if (ii->ii_fd < 0) { 311 ii->ii_fd = rarp_open(ii->ii_ifname); 312 #if BSD < 199100 313 /* Use BPF descriptor to get ethernet address. */ 314 if (ioctl(ii->ii_fd, SIOCGIFADDR, (char *)&ifr) == -1) { 315 logmsg(LOG_ERR, "eaddr SIOCGIFADDR: %s: %m", 316 ii->ii_ifname); 317 exit(1); 318 } 319 bcopy(&ifr.ifr_addr.sa_data[0], ii->ii_eaddr, 6); 320 #endif 321 } 322 break; 323 324 #if BSD >= 199100 325 case AF_LINK: 326 ll = (struct sockaddr_dl *)&ifrp->ifr_addr; 327 if (ll->sdl_type == IFT_ETHER) 328 bcopy(LLADDR(ll), ii->ii_eaddr, 6); 329 break; 330 #endif 331 } 332 } 333 /* 334 * Initialize all "candidate" interfaces that are in the system 335 * configuration list. A "candidate" is up, not loopback and not 336 * point to point. 337 */ 338 void 339 init(char *target) 340 { 341 u_int n; 342 struct ifreq *ifrp, *ifend; 343 struct if_info *ii, *nii, *lii; 344 struct ifconf ifc; 345 struct ifreq ibuf[16]; 346 347 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 348 logmsg(LOG_ERR, "socket: %m"); 349 exit(1); 350 } 351 ifc.ifc_len = sizeof ibuf; 352 ifc.ifc_buf = (caddr_t)ibuf; 353 if ((ioctl(s, SIOCGIFCONF, (char *)&ifc) == -1) || 354 ((u_int)ifc.ifc_len < sizeof(struct ifreq))) { 355 logmsg(LOG_ERR, "SIOCGIFCONF: %m"); 356 exit(1); 357 } 358 ifrp = ibuf; 359 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); 360 while (ifrp < ifend) { 361 init_one(ifrp, target); 362 363 #if BSD >= 199100 364 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name); 365 if (n < sizeof(*ifrp)) 366 n = sizeof(*ifrp); 367 ifrp = (struct ifreq *)((char *)ifrp + n); 368 #else 369 ++ifrp; 370 #endif 371 } 372 373 /* Throw away incomplete interfaces */ 374 lii = NULL; 375 for (ii = iflist; ii != NULL; ii = nii) { 376 nii = ii->ii_next; 377 if (ii->ii_ipaddr == 0 || 378 bcmp(ii->ii_eaddr, zero, 6) == 0) { 379 if (lii == NULL) 380 iflist = nii; 381 else 382 lii->ii_next = nii; 383 if (ii->ii_fd >= 0) 384 close(ii->ii_fd); 385 free(ii); 386 continue; 387 } 388 lii = ii; 389 } 390 391 /* Verbose stuff */ 392 if (verbose) 393 for (ii = iflist; ii != NULL; ii = ii->ii_next) 394 logmsg(LOG_DEBUG, "%s %s 0x%08lx %s", 395 ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)), 396 (u_long)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr)); 397 } 398 399 void 400 usage(void) 401 { 402 (void)fprintf(stderr, "usage: rarpd [-adfsv] [interface]\n"); 403 exit(1); 404 } 405 406 int 407 bpf_open(void) 408 { 409 int fd; 410 int n = 0; 411 char device[sizeof "/dev/bpf000"]; 412 413 /* 414 * Go through all the minors and find one that isn't in use. 415 */ 416 do { 417 (void)sprintf(device, "/dev/bpf%d", n++); 418 fd = open(device, O_RDWR); 419 } while ((fd == -1) && (errno == EBUSY)); 420 421 if (fd == -1) { 422 logmsg(LOG_ERR, "%s: %m", device); 423 exit(1); 424 } 425 return fd; 426 } 427 428 /* 429 * Open a BPF file and attach it to the interface named 'device'. 430 * Set immediate mode, and set a filter that accepts only RARP requests. 431 */ 432 int 433 rarp_open(char *device) 434 { 435 int fd; 436 struct ifreq ifr; 437 u_int dlt; 438 int immediate; 439 440 static struct bpf_insn insns[] = { 441 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12), 442 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3), 443 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20), 444 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1), 445 BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) + 446 sizeof(struct ether_header)), 447 BPF_STMT(BPF_RET|BPF_K, 0), 448 }; 449 static struct bpf_program filter = { 450 sizeof insns / sizeof(insns[0]), 451 insns 452 }; 453 454 fd = bpf_open(); 455 /* 456 * Set immediate mode so packets are processed as they arrive. 457 */ 458 immediate = 1; 459 if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) { 460 logmsg(LOG_ERR, "BIOCIMMEDIATE: %m"); 461 exit(1); 462 } 463 (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); 464 if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) { 465 logmsg(LOG_ERR, "BIOCSETIF: %m"); 466 exit(1); 467 } 468 /* 469 * Check that the data link layer is an Ethernet; this code won't 470 * work with anything else. 471 */ 472 if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) { 473 logmsg(LOG_ERR, "BIOCGDLT: %m"); 474 exit(1); 475 } 476 if (dlt != DLT_EN10MB) { 477 logmsg(LOG_ERR, "%s is not an ethernet", device); 478 exit(1); 479 } 480 /* 481 * Set filter program. 482 */ 483 if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) { 484 logmsg(LOG_ERR, "BIOCSETF: %m"); 485 exit(1); 486 } 487 return fd; 488 } 489 490 /* 491 * Perform various sanity checks on the RARP request packet. Return 492 * false on failure and log the reason. 493 */ 494 int 495 rarp_check(u_char *p, u_int len) 496 { 497 struct ether_header *ep = (struct ether_header *)p; 498 struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep)); 499 500 if (len < sizeof(*ep) + sizeof(*ap)) { 501 logmsg(LOG_ERR, "truncated request, got %u, expected %lu", 502 len, (u_long)(sizeof(*ep) + sizeof(*ap))); 503 return 0; 504 } 505 /* 506 * XXX This test might be better off broken out... 507 */ 508 if (ntohs(ep->ether_type) != ETHERTYPE_REVARP || 509 ntohs(ap->arp_hrd) != ARPHRD_ETHER || 510 ntohs(ap->arp_op) != REVARP_REQUEST || 511 ntohs(ap->arp_pro) != ETHERTYPE_IP || 512 ap->arp_hln != 6 || ap->arp_pln != 4) { 513 logmsg(LOG_DEBUG, "request fails sanity check"); 514 return 0; 515 } 516 if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) { 517 logmsg(LOG_DEBUG, "ether/arp sender address mismatch"); 518 return 0; 519 } 520 if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) { 521 logmsg(LOG_DEBUG, "ether/arp target address mismatch"); 522 return 0; 523 } 524 return 1; 525 } 526 527 #ifndef FD_SETSIZE 528 #define FD_SET(n, fdp) ((fdp)->fds_bits[0] |= (1 << (n))) 529 #define FD_ISSET(n, fdp) ((fdp)->fds_bits[0] & (1 << (n))) 530 #define FD_ZERO(fdp) ((fdp)->fds_bits[0] = 0) 531 #endif 532 533 /* 534 * Loop indefinitely listening for RARP requests on the 535 * interfaces in 'iflist'. 536 */ 537 void 538 rarp_loop(void) 539 { 540 u_char *buf, *bp, *ep; 541 int cc, fd; 542 fd_set fds, listeners; 543 int bufsize, maxfd = 0; 544 struct if_info *ii; 545 546 if (iflist == NULL) { 547 logmsg(LOG_ERR, "no interfaces"); 548 exit(1); 549 } 550 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) { 551 logmsg(LOG_ERR, "BIOCGBLEN: %m"); 552 exit(1); 553 } 554 buf = malloc(bufsize); 555 if (buf == NULL) { 556 logmsg(LOG_ERR, "malloc: %m"); 557 exit(1); 558 } 559 560 while (1) { 561 /* 562 * Find the highest numbered file descriptor for select(). 563 * Initialize the set of descriptors to listen to. 564 */ 565 FD_ZERO(&fds); 566 for (ii = iflist; ii != NULL; ii = ii->ii_next) { 567 FD_SET(ii->ii_fd, &fds); 568 if (ii->ii_fd > maxfd) 569 maxfd = ii->ii_fd; 570 } 571 listeners = fds; 572 if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) { 573 /* Don't choke when we get ptraced */ 574 if (errno == EINTR) 575 continue; 576 logmsg(LOG_ERR, "select: %m"); 577 exit(1); 578 } 579 for (ii = iflist; ii != NULL; ii = ii->ii_next) { 580 fd = ii->ii_fd; 581 if (!FD_ISSET(fd, &listeners)) 582 continue; 583 again: 584 cc = read(fd, (char *)buf, bufsize); 585 /* Don't choke when we get ptraced */ 586 if ((cc == -1) && (errno == EINTR)) 587 goto again; 588 #if defined(SUNOS3) || defined(SUNOS4) 589 /* 590 * Due to a SunOS bug, after 2^31 bytes, the 591 * file offset overflows and read fails with 592 * EINVAL. The lseek() to 0 will fix things. 593 */ 594 if (cc == -1) { 595 if (errno == EINVAL && 596 (long)(tell(fd) + bufsize) < 0) { 597 (void)lseek(fd, 0, 0); 598 goto again; 599 } 600 logmsg(LOG_ERR, "read: %m"); 601 exit(1); 602 } 603 #endif 604 605 /* Loop through the packet(s) */ 606 #define bhp ((struct bpf_hdr *)bp) 607 bp = buf; 608 ep = bp + cc; 609 while (bp < ep) { 610 u_int caplen, hdrlen; 611 612 caplen = bhp->bh_caplen; 613 hdrlen = bhp->bh_hdrlen; 614 if (rarp_check(bp + hdrlen, caplen)) 615 rarp_process(ii, bp + hdrlen, caplen); 616 bp += BPF_WORDALIGN(hdrlen + caplen); 617 } 618 } 619 } 620 #undef bhp 621 } 622 623 /* 624 * True if this server can boot the host whose IP address is 'addr'. 625 * This check is made by looking in the tftp directory for the 626 * configuration file. 627 */ 628 int 629 rarp_bootable(u_long addr) 630 { 631 #ifdef HAVE_DIRENT_H 632 struct dirent *dent; 633 #else 634 struct direct *dent; 635 #endif 636 DIR *d; 637 char ipname[9]; 638 static DIR *dd = NULL; 639 640 (void)sprintf(ipname, "%08lX", (u_long)ntohl(addr)); 641 642 /* 643 * If directory is already open, rewind it. Otherwise, open it. 644 */ 645 if ((d = dd) != NULL) 646 rewinddir(d); 647 else { 648 if (chdir(tftp_dir) == -1) { 649 logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir); 650 exit(1); 651 } 652 d = opendir("."); 653 if (d == NULL) { 654 logmsg(LOG_ERR, "opendir: %m"); 655 exit(1); 656 } 657 dd = d; 658 } 659 while ((dent = readdir(d)) != NULL) 660 if (strncmp(dent->d_name, ipname, 8) == 0) 661 return 1; 662 return 0; 663 } 664 665 /* 666 * Given a list of IP addresses, 'alist', return the first address that 667 * is on network 'net'; 'netmask' is a mask indicating the network portion 668 * of the address. 669 */ 670 u_long 671 choose_ipaddr(u_long **alist, u_long net, u_long netmask) 672 { 673 for (; *alist; ++alist) 674 if ((**alist & netmask) == net) 675 return **alist; 676 return 0; 677 } 678 679 /* 680 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 681 * already been checked for validity. The reply is overlaid on the request. 682 */ 683 void 684 rarp_process(struct if_info *ii, u_char *pkt, u_int len) 685 { 686 struct ether_header *ep; 687 struct hostent *hp; 688 u_long target_ipaddr; 689 char ename[256]; 690 691 ep = (struct ether_header *)pkt; 692 /* should this be arp_tha? */ 693 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 694 logmsg(LOG_ERR, "cannot map %s to name", 695 eatoa(ep->ether_shost)); 696 return; 697 } 698 699 if ((hp = gethostbyname(ename)) == NULL) { 700 logmsg(LOG_ERR, "cannot map %s to IP address", ename); 701 return; 702 } 703 704 /* 705 * Choose correct address from list. 706 */ 707 if (hp->h_addrtype != AF_INET) { 708 logmsg(LOG_ERR, "cannot handle non IP addresses for %s", 709 ename); 710 return; 711 } 712 target_ipaddr = choose_ipaddr((u_long **)hp->h_addr_list, 713 ii->ii_ipaddr & ii->ii_netmask, 714 ii->ii_netmask); 715 if (target_ipaddr == 0) { 716 logmsg(LOG_ERR, "cannot find %s on net %s", 717 ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask))); 718 return; 719 } 720 if (sflag || rarp_bootable(target_ipaddr)) 721 rarp_reply(ii, ep, target_ipaddr, len); 722 else if (verbose > 1) 723 logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)", 724 ii->ii_ifname, 725 eatoa(ep->ether_shost), 726 intoa(ntohl(target_ipaddr))); 727 } 728 729 /* 730 * Poke the kernel arp tables with the ethernet/ip address combinataion 731 * given. When processing a reply, we must do this so that the booting 732 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 733 * address of the guy being booted (he cannot answer the ARP). 734 */ 735 #if BSD >= 199200 736 struct sockaddr_inarp sin_inarp = { 737 sizeof(struct sockaddr_inarp), AF_INET, 0, 738 {0}, 739 {0}, 740 0, 0 741 }; 742 struct sockaddr_dl sin_dl = { 743 sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6, 744 0, "" 745 }; 746 struct { 747 struct rt_msghdr rthdr; 748 char rtspace[512]; 749 } rtmsg; 750 751 void 752 update_arptab(u_char *ep, u_long ipaddr) 753 { 754 int cc; 755 struct sockaddr_inarp *ar, *ar2; 756 struct sockaddr_dl *ll, *ll2; 757 struct rt_msghdr *rt; 758 int xtype, xindex; 759 static pid_t pid; 760 int r; 761 static int seq; 762 763 r = socket(PF_ROUTE, SOCK_RAW, 0); 764 if (r == -1) { 765 logmsg(LOG_ERR, "raw route socket: %m"); 766 exit(1); 767 } 768 pid = getpid(); 769 770 ar = &sin_inarp; 771 ar->sin_addr.s_addr = ipaddr; 772 ll = &sin_dl; 773 bcopy(ep, LLADDR(ll), 6); 774 775 /* Get the type and interface index */ 776 rt = &rtmsg.rthdr; 777 bzero(rt, sizeof(rtmsg)); 778 rt->rtm_version = RTM_VERSION; 779 rt->rtm_addrs = RTA_DST; 780 rt->rtm_type = RTM_GET; 781 rt->rtm_seq = ++seq; 782 ar2 = (struct sockaddr_inarp *)rtmsg.rtspace; 783 bcopy(ar, ar2, sizeof(*ar)); 784 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar); 785 errno = 0; 786 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) { 787 logmsg(LOG_ERR, "rtmsg get write: %m"); 788 close(r); 789 return; 790 } 791 do { 792 cc = read(r, rt, sizeof(rtmsg)); 793 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); 794 if (cc == -1) { 795 logmsg(LOG_ERR, "rtmsg get read: %m"); 796 close(r); 797 return; 798 } 799 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len); 800 if (ll2->sdl_family != AF_LINK) { 801 /* 802 * XXX I think this means the ip address is not on a 803 * directly connected network (the family is AF_INET in 804 * this case). 805 */ 806 logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08lX?\n", 807 ll2->sdl_family, ipaddr); 808 close(r); 809 return; 810 } 811 xtype = ll2->sdl_type; 812 xindex = ll2->sdl_index; 813 814 /* Set the new arp entry */ 815 bzero(rt, sizeof(rtmsg)); 816 rt->rtm_version = RTM_VERSION; 817 rt->rtm_addrs = RTA_DST | RTA_GATEWAY; 818 rt->rtm_inits = RTV_EXPIRE; 819 rt->rtm_rmx.rmx_expire = time(0) + ARPSECS; 820 rt->rtm_flags = RTF_HOST | RTF_STATIC; 821 rt->rtm_type = RTM_ADD; 822 rt->rtm_seq = ++seq; 823 824 bcopy(ar, ar2, sizeof(*ar)); 825 826 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2)); 827 bcopy(ll, ll2, sizeof(*ll)); 828 ll2->sdl_type = xtype; 829 ll2->sdl_index = xindex; 830 831 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2); 832 errno = 0; 833 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) { 834 logmsg(LOG_ERR, "rtmsg add write: %m"); 835 close(r); 836 return; 837 } 838 do { 839 cc = read(r, rt, sizeof(rtmsg)); 840 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); 841 close(r); 842 if (cc == -1) { 843 logmsg(LOG_ERR, "rtmsg add read: %m"); 844 return; 845 } 846 } 847 #else 848 void 849 update_arptab(u_char *ep, u_long ipaddr) 850 { 851 struct arpreq request; 852 struct sockaddr_in *sin; 853 854 request.arp_flags = 0; 855 sin = (struct sockaddr_in *)&request.arp_pa; 856 sin->sin_family = AF_INET; 857 sin->sin_addr.s_addr = ipaddr; 858 request.arp_ha.sa_family = AF_UNSPEC; 859 bcopy((char *)ep, (char *)request.arp_ha.sa_data, 6); 860 861 if (ioctl(s, SIOCSARP, (caddr_t)&request) == -1) 862 logmsg(LOG_ERR, "SIOCSARP: %m"); 863 } 864 #endif 865 866 /* 867 * Build a reverse ARP packet and sent it out on the interface. 868 * 'ep' points to a valid REVARP_REQUEST. The REVARP_REPLY is built 869 * on top of the request, then written to the network. 870 * 871 * RFC 903 defines the ether_arp fields as follows. The following comments 872 * are taken (more or less) straight from this document. 873 * 874 * REVARP_REQUEST 875 * 876 * arp_sha is the hardware address of the sender of the packet. 877 * arp_spa is undefined. 878 * arp_tha is the 'target' hardware address. 879 * In the case where the sender wishes to determine his own 880 * protocol address, this, like arp_sha, will be the hardware 881 * address of the sender. 882 * arp_tpa is undefined. 883 * 884 * REVARP_REPLY 885 * 886 * arp_sha is the hardware address of the responder (the sender of the 887 * reply packet). 888 * arp_spa is the protocol address of the responder (see the note below). 889 * arp_tha is the hardware address of the target, and should be the same as 890 * that which was given in the request. 891 * arp_tpa is the protocol address of the target, that is, the desired address. 892 * 893 * Note that the requirement that arp_spa be filled in with the responder's 894 * protocol is purely for convenience. For instance, if a system were to use 895 * both ARP and RARP, then the inclusion of the valid protocol-hardware 896 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 897 * ARP request. 898 */ 899 void 900 rarp_reply(struct if_info *ii, struct ether_header *ep, u_long ipaddr, 901 u_int len) 902 { 903 u_int n; 904 struct ether_arp *ap = (struct ether_arp *)(ep + 1); 905 906 update_arptab((u_char *)&ap->arp_sha, ipaddr); 907 908 /* 909 * Build the rarp reply by modifying the rarp request in place. 910 */ 911 ap->arp_op = htons(REVARP_REPLY); 912 913 #ifdef BROKEN_BPF 914 ep->ether_type = ETHERTYPE_REVARP; 915 #endif 916 bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6); 917 bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6); 918 bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6); 919 920 bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4); 921 /* Target hardware is unchanged. */ 922 bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4); 923 924 /* Zero possible garbage after packet. */ 925 bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)), 926 len - (sizeof(*ep) + sizeof(*ap))); 927 n = write(ii->ii_fd, (char *)ep, len); 928 if (n != len) 929 logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len); 930 if (verbose) 931 logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname, 932 eatoa(ap->arp_tha), 933 intoa(ntohl(ipaddr))); 934 } 935 936 /* 937 * Get the netmask of an IP address. This routine is used if 938 * SIOCGIFNETMASK doesn't work. 939 */ 940 u_long 941 ipaddrtonetmask(u_long addr) 942 { 943 addr = ntohl(addr); 944 if (IN_CLASSA(addr)) 945 return htonl(IN_CLASSA_NET); 946 if (IN_CLASSB(addr)) 947 return htonl(IN_CLASSB_NET); 948 if (IN_CLASSC(addr)) 949 return htonl(IN_CLASSC_NET); 950 logmsg(LOG_DEBUG, "unknown IP address class: %08lX", addr); 951 return htonl(0xffffffff); 952 } 953 954 /* 955 * A faster replacement for inet_ntoa(). 956 */ 957 char * 958 intoa(u_long addr) 959 { 960 char *cp; 961 u_int byte; 962 int n; 963 static char buf[sizeof(".xxx.xxx.xxx.xxx")]; 964 965 cp = &buf[sizeof buf]; 966 *--cp = '\0'; 967 968 n = 4; 969 do { 970 byte = addr & 0xff; 971 *--cp = byte % 10 + '0'; 972 byte /= 10; 973 if (byte > 0) { 974 *--cp = byte % 10 + '0'; 975 byte /= 10; 976 if (byte > 0) 977 *--cp = byte + '0'; 978 } 979 *--cp = '.'; 980 addr >>= 8; 981 } while (--n > 0); 982 983 return cp + 1; 984 } 985 986 char * 987 eatoa(u_char *ea) 988 { 989 static char buf[sizeof("xx:xx:xx:xx:xx:xx")]; 990 991 (void)sprintf(buf, "%x:%x:%x:%x:%x:%x", 992 ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]); 993 return (buf); 994 } 995 996 void 997 logmsg(int pri, const char *fmt, ...) 998 { 999 va_list v; 1000 FILE *fp; 1001 char *newfmt; 1002 1003 va_start(v, fmt); 1004 if (dflag) { 1005 if (pri == LOG_ERR) 1006 fp = stderr; 1007 else 1008 fp = stdout; 1009 if (expand_syslog_m(fmt, &newfmt) == -1) { 1010 vfprintf(fp, fmt, v); 1011 } else { 1012 vfprintf(fp, newfmt, v); 1013 free(newfmt); 1014 } 1015 fputs("\n", fp); 1016 fflush(fp); 1017 } else { 1018 vsyslog(pri, fmt, v); 1019 } 1020 va_end(v); 1021 } 1022 1023 int 1024 expand_syslog_m(const char *fmt, char **newfmt) { 1025 const char *str, *m; 1026 char *p, *np; 1027 1028 p = strdup(""); 1029 str = fmt; 1030 while ((m = strstr(str, "%m")) != NULL) { 1031 asprintf(&np, "%s%.*s%s", p, (int)(m - str), 1032 str, strerror(errno)); 1033 free(p); 1034 if (np == NULL) { 1035 errno = ENOMEM; 1036 return (-1); 1037 } 1038 p = np; 1039 str = m + 2; 1040 } 1041 1042 if (*str != '\0') { 1043 asprintf(&np, "%s%s", p, str); 1044 free(p); 1045 if (np == NULL) { 1046 errno = ENOMEM; 1047 return (-1); 1048 } 1049 p = np; 1050 } 1051 1052 *newfmt = p; 1053 return (0); 1054 } 1055