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 11 * 12 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 13 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 14 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 15 */ 16 17 #if 0 18 #ifndef lint 19 static const char copyright[] = 20 "@(#) Copyright (c) 1990, 1991, 1992, 1993, 1996\n\ 21 The Regents of the University of California. All rights reserved.\n"; 22 #endif /* not lint */ 23 #endif 24 #include <sys/cdefs.h> 25 __FBSDID("$FreeBSD$"); 26 27 /* 28 * rarpd - Reverse ARP Daemon 29 * 30 * Usage: rarpd -a [-dfsv] [-t directory] [-P pidfile] [hostname] 31 * rarpd [-dfsv] [-t directory] [-P pidfile] interface [hostname] 32 * 33 * 'hostname' is optional solely for backwards compatibility with Sun's rarpd. 34 * Currently, the argument is ignored. 35 */ 36 #include <sys/param.h> 37 #include <sys/file.h> 38 #include <sys/ioctl.h> 39 #include <sys/socket.h> 40 #include <sys/time.h> 41 42 #include <net/bpf.h> 43 #include <net/ethernet.h> 44 #include <net/if.h> 45 #include <net/if_types.h> 46 #include <net/if_dl.h> 47 #include <net/route.h> 48 49 #include <netinet/in.h> 50 #include <netinet/if_ether.h> 51 52 #include <arpa/inet.h> 53 54 #include <dirent.h> 55 #include <errno.h> 56 #include <ifaddrs.h> 57 #include <netdb.h> 58 #include <stdarg.h> 59 #include <stdio.h> 60 #include <string.h> 61 #include <syslog.h> 62 #include <stdlib.h> 63 #include <unistd.h> 64 #include <libutil.h> 65 66 /* Cast a struct sockaddr to a struct sockaddr_in */ 67 #define SATOSIN(sa) ((struct sockaddr_in *)(sa)) 68 69 #ifndef TFTP_DIR 70 #define TFTP_DIR "/tftpboot" 71 #endif 72 73 #define ARPSECS (20 * 60) /* as per code in netinet/if_ether.c */ 74 #define REVARP_REQUEST ARPOP_REVREQUEST 75 #define REVARP_REPLY ARPOP_REVREPLY 76 77 /* 78 * The structure for each interface. 79 */ 80 struct if_info { 81 struct if_info *ii_next; 82 int ii_fd; /* BPF file descriptor */ 83 in_addr_t ii_ipaddr; /* IP address */ 84 in_addr_t ii_netmask; /* subnet or net mask */ 85 u_char ii_eaddr[ETHER_ADDR_LEN]; /* ethernet address */ 86 char ii_ifname[IF_NAMESIZE]; 87 }; 88 89 /* 90 * The list of all interfaces that are being listened to. rarp_loop() 91 * "selects" on the descriptors in this list. 92 */ 93 struct if_info *iflist; 94 95 int verbose; /* verbose messages */ 96 const char *tftp_dir = TFTP_DIR; /* tftp directory */ 97 98 int dflag; /* messages to stdout/stderr, not syslog(3) */ 99 int sflag; /* ignore /tftpboot */ 100 101 static u_char zero[6]; 102 103 static char pidfile_buf[PATH_MAX]; 104 static char *pidfile; 105 #define RARPD_PIDFILE "/var/run/rarpd.%s.pid" 106 static struct pidfh *pidfile_fh; 107 108 static int bpf_open(void); 109 static in_addr_t choose_ipaddr(in_addr_t **, in_addr_t, in_addr_t); 110 static char *eatoa(u_char *); 111 static int expand_syslog_m(const char *fmt, char **newfmt); 112 static void init(char *); 113 static void init_one(struct ifaddrs *, char *, int); 114 static char *intoa(in_addr_t); 115 static in_addr_t ipaddrtonetmask(in_addr_t); 116 static void logmsg(int, const char *, ...) __printflike(2, 3); 117 static int rarp_bootable(in_addr_t); 118 static int rarp_check(u_char *, u_int); 119 static void rarp_loop(void); 120 static int rarp_open(char *); 121 static void rarp_process(struct if_info *, u_char *, u_int); 122 static void rarp_reply(struct if_info *, struct ether_header *, 123 in_addr_t, u_int); 124 static void update_arptab(u_char *, in_addr_t); 125 static void usage(void); 126 127 int 128 main(int argc, char *argv[]) 129 { 130 int op; 131 char *ifname, *name; 132 133 int aflag = 0; /* listen on "all" interfaces */ 134 int fflag = 0; /* don't fork */ 135 136 if ((name = strrchr(argv[0], '/')) != NULL) 137 ++name; 138 else 139 name = argv[0]; 140 if (*name == '-') 141 ++name; 142 143 /* 144 * All error reporting is done through syslog, unless -d is specified 145 */ 146 openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON); 147 148 opterr = 0; 149 while ((op = getopt(argc, argv, "adfsP:t:v")) != -1) 150 switch (op) { 151 case 'a': 152 ++aflag; 153 break; 154 155 case 'd': 156 ++dflag; 157 break; 158 159 case 'f': 160 ++fflag; 161 break; 162 163 case 's': 164 ++sflag; 165 break; 166 167 case 'P': 168 strncpy(pidfile_buf, optarg, sizeof(pidfile_buf) - 1); 169 pidfile_buf[sizeof(pidfile_buf) - 1] = '\0'; 170 pidfile = pidfile_buf; 171 break; 172 173 case 't': 174 tftp_dir = optarg; 175 break; 176 177 case 'v': 178 ++verbose; 179 break; 180 181 default: 182 usage(); 183 /* NOTREACHED */ 184 } 185 argc -= optind; 186 argv += optind; 187 188 ifname = (aflag == 0) ? argv[0] : NULL; 189 190 if ((aflag && ifname) || (!aflag && ifname == NULL)) 191 usage(); 192 193 init(ifname); 194 195 if (!fflag) { 196 if (pidfile == NULL && ifname != NULL && aflag == 0) { 197 snprintf(pidfile_buf, sizeof(pidfile_buf) - 1, 198 RARPD_PIDFILE, ifname); 199 pidfile_buf[sizeof(pidfile_buf) - 1] = '\0'; 200 pidfile = pidfile_buf; 201 } 202 /* If pidfile == NULL, /var/run/<progname>.pid will be used. */ 203 pidfile_fh = pidfile_open(pidfile, 0600, NULL); 204 if (pidfile_fh == NULL) 205 logmsg(LOG_ERR, "Cannot open or create pidfile: %s", 206 (pidfile == NULL) ? "/var/run/rarpd.pid" : pidfile); 207 if (daemon(0,0)) { 208 logmsg(LOG_ERR, "cannot fork"); 209 pidfile_remove(pidfile_fh); 210 exit(1); 211 } 212 pidfile_write(pidfile_fh); 213 } 214 rarp_loop(); 215 return(0); 216 } 217 218 /* 219 * Add to the interface list. 220 */ 221 static void 222 init_one(struct ifaddrs *ifa, char *target, int pass1) 223 { 224 struct if_info *ii, *ii2; 225 struct sockaddr_dl *ll; 226 int family; 227 228 family = ifa->ifa_addr->sa_family; 229 switch (family) { 230 case AF_INET: 231 if (pass1) 232 /* Consider only AF_LINK during pass1. */ 233 return; 234 /* FALLTHROUGH */ 235 case AF_LINK: 236 if (!(ifa->ifa_flags & IFF_UP) || 237 (ifa->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) 238 return; 239 break; 240 default: 241 return; 242 } 243 244 /* Don't bother going any further if not the target interface */ 245 if (target != NULL && strcmp(ifa->ifa_name, target) != 0) 246 return; 247 248 /* Look for interface in list */ 249 for (ii = iflist; ii != NULL; ii = ii->ii_next) 250 if (strcmp(ifa->ifa_name, ii->ii_ifname) == 0) 251 break; 252 253 if (pass1 && ii != NULL) 254 /* We've already seen that interface once. */ 255 return; 256 257 /* Allocate a new one if not found */ 258 if (ii == NULL) { 259 ii = (struct if_info *)malloc(sizeof(*ii)); 260 if (ii == NULL) { 261 logmsg(LOG_ERR, "malloc: %m"); 262 pidfile_remove(pidfile_fh); 263 exit(1); 264 } 265 bzero(ii, sizeof(*ii)); 266 ii->ii_fd = -1; 267 strlcpy(ii->ii_ifname, ifa->ifa_name, sizeof(ii->ii_ifname)); 268 ii->ii_next = iflist; 269 iflist = ii; 270 } else if (!pass1 && ii->ii_ipaddr != 0) { 271 /* 272 * Second AF_INET definition for that interface: clone 273 * the existing one, and work on that cloned one. 274 * This must be another IP address for this interface, 275 * so avoid killing the previous configuration. 276 */ 277 ii2 = (struct if_info *)malloc(sizeof(*ii2)); 278 if (ii2 == NULL) { 279 logmsg(LOG_ERR, "malloc: %m"); 280 pidfile_remove(pidfile_fh); 281 exit(1); 282 } 283 memcpy(ii2, ii, sizeof(*ii2)); 284 ii2->ii_fd = -1; 285 ii2->ii_next = iflist; 286 iflist = ii2; 287 288 ii = ii2; 289 } 290 291 switch (family) { 292 case AF_INET: 293 ii->ii_ipaddr = SATOSIN(ifa->ifa_addr)->sin_addr.s_addr; 294 ii->ii_netmask = SATOSIN(ifa->ifa_netmask)->sin_addr.s_addr; 295 if (ii->ii_netmask == 0) 296 ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr); 297 if (ii->ii_fd < 0) 298 ii->ii_fd = rarp_open(ii->ii_ifname); 299 break; 300 301 case AF_LINK: 302 ll = (struct sockaddr_dl *)ifa->ifa_addr; 303 switch (ll->sdl_type) { 304 case IFT_ETHER: 305 case IFT_L2VLAN: 306 bcopy(LLADDR(ll), ii->ii_eaddr, 6); 307 } 308 break; 309 } 310 } 311 /* 312 * Initialize all "candidate" interfaces that are in the system 313 * configuration list. A "candidate" is up, not loopback and not 314 * point to point. 315 */ 316 static void 317 init(char *target) 318 { 319 struct if_info *ii, *nii, *lii; 320 struct ifaddrs *ifhead, *ifa; 321 int error; 322 323 error = getifaddrs(&ifhead); 324 if (error) { 325 logmsg(LOG_ERR, "getifaddrs: %m"); 326 pidfile_remove(pidfile_fh); 327 exit(1); 328 } 329 /* 330 * We make two passes over the list we have got. In the first 331 * one, we only collect AF_LINK interfaces, and initialize our 332 * list of interfaces from them. In the second pass, we 333 * collect the actual IP addresses from the AF_INET 334 * interfaces, and allow for the same interface name to appear 335 * multiple times (in case of more than one IP address). 336 */ 337 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next) 338 init_one(ifa, target, 1); 339 for (ifa = ifhead; ifa != NULL; ifa = ifa->ifa_next) 340 init_one(ifa, target, 0); 341 freeifaddrs(ifhead); 342 343 /* Throw away incomplete interfaces */ 344 lii = NULL; 345 for (ii = iflist; ii != NULL; ii = nii) { 346 nii = ii->ii_next; 347 if (ii->ii_ipaddr == 0 || 348 bcmp(ii->ii_eaddr, zero, 6) == 0) { 349 if (lii == NULL) 350 iflist = nii; 351 else 352 lii->ii_next = nii; 353 if (ii->ii_fd >= 0) 354 close(ii->ii_fd); 355 free(ii); 356 continue; 357 } 358 lii = ii; 359 } 360 361 /* Verbose stuff */ 362 if (verbose) 363 for (ii = iflist; ii != NULL; ii = ii->ii_next) 364 logmsg(LOG_DEBUG, "%s %s 0x%08x %s", 365 ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)), 366 (in_addr_t)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr)); 367 } 368 369 static void 370 usage(void) 371 { 372 (void)fprintf(stderr, "%s\n%s\n", 373 "usage: rarpd -a [-dfsv] [-t directory] [-P pidfile]", 374 " rarpd [-dfsv] [-t directory] [-P pidfile] interface"); 375 exit(1); 376 } 377 378 static int 379 bpf_open(void) 380 { 381 int fd; 382 int n = 0; 383 char device[sizeof "/dev/bpf000"]; 384 385 /* 386 * Go through all the minors and find one that isn't in use. 387 */ 388 do { 389 (void)sprintf(device, "/dev/bpf%d", n++); 390 fd = open(device, O_RDWR); 391 } while ((fd == -1) && (errno == EBUSY)); 392 393 if (fd == -1) { 394 logmsg(LOG_ERR, "%s: %m", device); 395 pidfile_remove(pidfile_fh); 396 exit(1); 397 } 398 return fd; 399 } 400 401 /* 402 * Open a BPF file and attach it to the interface named 'device'. 403 * Set immediate mode, and set a filter that accepts only RARP requests. 404 */ 405 static int 406 rarp_open(char *device) 407 { 408 int fd; 409 struct ifreq ifr; 410 u_int dlt; 411 int immediate; 412 413 static struct bpf_insn insns[] = { 414 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12), 415 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3), 416 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20), 417 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1), 418 BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) + 419 sizeof(struct ether_header)), 420 BPF_STMT(BPF_RET|BPF_K, 0), 421 }; 422 static struct bpf_program filter = { 423 sizeof insns / sizeof(insns[0]), 424 insns 425 }; 426 427 fd = bpf_open(); 428 /* 429 * Set immediate mode so packets are processed as they arrive. 430 */ 431 immediate = 1; 432 if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) { 433 logmsg(LOG_ERR, "BIOCIMMEDIATE: %m"); 434 goto rarp_open_err; 435 } 436 strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 437 if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) { 438 logmsg(LOG_ERR, "BIOCSETIF: %m"); 439 goto rarp_open_err; 440 } 441 /* 442 * Check that the data link layer is an Ethernet; this code won't 443 * work with anything else. 444 */ 445 if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) { 446 logmsg(LOG_ERR, "BIOCGDLT: %m"); 447 goto rarp_open_err; 448 } 449 if (dlt != DLT_EN10MB) { 450 logmsg(LOG_ERR, "%s is not an ethernet", device); 451 goto rarp_open_err; 452 } 453 /* 454 * Set filter program. 455 */ 456 if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) { 457 logmsg(LOG_ERR, "BIOCSETF: %m"); 458 goto rarp_open_err; 459 } 460 return fd; 461 462 rarp_open_err: 463 pidfile_remove(pidfile_fh); 464 exit(1); 465 } 466 467 /* 468 * Perform various sanity checks on the RARP request packet. Return 469 * false on failure and log the reason. 470 */ 471 static int 472 rarp_check(u_char *p, u_int len) 473 { 474 struct ether_header *ep = (struct ether_header *)p; 475 struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep)); 476 477 if (len < sizeof(*ep) + sizeof(*ap)) { 478 logmsg(LOG_ERR, "truncated request, got %u, expected %lu", 479 len, (u_long)(sizeof(*ep) + sizeof(*ap))); 480 return 0; 481 } 482 /* 483 * XXX This test might be better off broken out... 484 */ 485 if (ntohs(ep->ether_type) != ETHERTYPE_REVARP || 486 ntohs(ap->arp_hrd) != ARPHRD_ETHER || 487 ntohs(ap->arp_op) != REVARP_REQUEST || 488 ntohs(ap->arp_pro) != ETHERTYPE_IP || 489 ap->arp_hln != 6 || ap->arp_pln != 4) { 490 logmsg(LOG_DEBUG, "request fails sanity check"); 491 return 0; 492 } 493 if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) { 494 logmsg(LOG_DEBUG, "ether/arp sender address mismatch"); 495 return 0; 496 } 497 if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) { 498 logmsg(LOG_DEBUG, "ether/arp target address mismatch"); 499 return 0; 500 } 501 return 1; 502 } 503 504 /* 505 * Loop indefinitely listening for RARP requests on the 506 * interfaces in 'iflist'. 507 */ 508 static void 509 rarp_loop(void) 510 { 511 u_char *buf, *bp, *ep; 512 int cc, fd; 513 fd_set fds, listeners; 514 int bufsize, maxfd = 0; 515 struct if_info *ii; 516 517 if (iflist == NULL) { 518 logmsg(LOG_ERR, "no interfaces"); 519 goto rarpd_loop_err; 520 } 521 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) { 522 logmsg(LOG_ERR, "BIOCGBLEN: %m"); 523 goto rarpd_loop_err; 524 } 525 buf = malloc(bufsize); 526 if (buf == NULL) { 527 logmsg(LOG_ERR, "malloc: %m"); 528 goto rarpd_loop_err; 529 } 530 531 while (1) { 532 /* 533 * Find the highest numbered file descriptor for select(). 534 * Initialize the set of descriptors to listen to. 535 */ 536 FD_ZERO(&fds); 537 for (ii = iflist; ii != NULL; ii = ii->ii_next) { 538 FD_SET(ii->ii_fd, &fds); 539 if (ii->ii_fd > maxfd) 540 maxfd = ii->ii_fd; 541 } 542 listeners = fds; 543 if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) { 544 /* Don't choke when we get ptraced */ 545 if (errno == EINTR) 546 continue; 547 logmsg(LOG_ERR, "select: %m"); 548 goto rarpd_loop_err; 549 } 550 for (ii = iflist; ii != NULL; ii = ii->ii_next) { 551 fd = ii->ii_fd; 552 if (!FD_ISSET(fd, &listeners)) 553 continue; 554 again: 555 cc = read(fd, (char *)buf, bufsize); 556 /* Don't choke when we get ptraced */ 557 if ((cc == -1) && (errno == EINTR)) 558 goto again; 559 560 /* Loop through the packet(s) */ 561 #define bhp ((struct bpf_hdr *)bp) 562 bp = buf; 563 ep = bp + cc; 564 while (bp < ep) { 565 u_int caplen, hdrlen; 566 567 caplen = bhp->bh_caplen; 568 hdrlen = bhp->bh_hdrlen; 569 if (rarp_check(bp + hdrlen, caplen)) 570 rarp_process(ii, bp + hdrlen, caplen); 571 bp += BPF_WORDALIGN(hdrlen + caplen); 572 } 573 } 574 } 575 #undef bhp 576 return; 577 578 rarpd_loop_err: 579 pidfile_remove(pidfile_fh); 580 exit(1); 581 } 582 583 /* 584 * True if this server can boot the host whose IP address is 'addr'. 585 * This check is made by looking in the tftp directory for the 586 * configuration file. 587 */ 588 static int 589 rarp_bootable(in_addr_t addr) 590 { 591 struct dirent *dent; 592 DIR *d; 593 char ipname[9]; 594 static DIR *dd = NULL; 595 596 (void)sprintf(ipname, "%08X", (in_addr_t)ntohl(addr)); 597 598 /* 599 * If directory is already open, rewind it. Otherwise, open it. 600 */ 601 if ((d = dd) != NULL) 602 rewinddir(d); 603 else { 604 if (chdir(tftp_dir) == -1) { 605 logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir); 606 goto rarp_bootable_err; 607 } 608 d = opendir("."); 609 if (d == NULL) { 610 logmsg(LOG_ERR, "opendir: %m"); 611 goto rarp_bootable_err; 612 } 613 dd = d; 614 } 615 while ((dent = readdir(d)) != NULL) 616 if (strncmp(dent->d_name, ipname, 8) == 0) 617 return 1; 618 return 0; 619 620 rarp_bootable_err: 621 pidfile_remove(pidfile_fh); 622 exit(1); 623 } 624 625 /* 626 * Given a list of IP addresses, 'alist', return the first address that 627 * is on network 'net'; 'netmask' is a mask indicating the network portion 628 * of the address. 629 */ 630 static in_addr_t 631 choose_ipaddr(in_addr_t **alist, in_addr_t net, in_addr_t netmask) 632 { 633 for (; *alist; ++alist) 634 if ((**alist & netmask) == net) 635 return **alist; 636 return 0; 637 } 638 639 /* 640 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 641 * already been checked for validity. The reply is overlaid on the request. 642 */ 643 static void 644 rarp_process(struct if_info *ii, u_char *pkt, u_int len) 645 { 646 struct ether_header *ep; 647 struct hostent *hp; 648 in_addr_t target_ipaddr; 649 char ename[256]; 650 651 ep = (struct ether_header *)pkt; 652 /* should this be arp_tha? */ 653 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 654 logmsg(LOG_ERR, "cannot map %s to name", 655 eatoa(ep->ether_shost)); 656 return; 657 } 658 659 if ((hp = gethostbyname(ename)) == NULL) { 660 logmsg(LOG_ERR, "cannot map %s to IP address", ename); 661 return; 662 } 663 664 /* 665 * Choose correct address from list. 666 */ 667 if (hp->h_addrtype != AF_INET) { 668 logmsg(LOG_ERR, "cannot handle non IP addresses for %s", 669 ename); 670 return; 671 } 672 target_ipaddr = choose_ipaddr((in_addr_t **)hp->h_addr_list, 673 ii->ii_ipaddr & ii->ii_netmask, 674 ii->ii_netmask); 675 if (target_ipaddr == 0) { 676 logmsg(LOG_ERR, "cannot find %s on net %s", 677 ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask))); 678 return; 679 } 680 if (sflag || rarp_bootable(target_ipaddr)) 681 rarp_reply(ii, ep, target_ipaddr, len); 682 else if (verbose > 1) 683 logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)", 684 ii->ii_ifname, 685 eatoa(ep->ether_shost), 686 intoa(ntohl(target_ipaddr))); 687 } 688 689 /* 690 * Poke the kernel arp tables with the ethernet/ip address combinataion 691 * given. When processing a reply, we must do this so that the booting 692 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 693 * address of the guy being booted (he cannot answer the ARP). 694 */ 695 struct sockaddr_inarp sin_inarp = { 696 sizeof(struct sockaddr_inarp), AF_INET, 0, 697 {0}, 698 {0}, 699 0, 0 700 }; 701 struct sockaddr_dl sin_dl = { 702 sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6, 703 0, "" 704 }; 705 struct { 706 struct rt_msghdr rthdr; 707 char rtspace[512]; 708 } rtmsg; 709 710 static void 711 update_arptab(u_char *ep, in_addr_t ipaddr) 712 { 713 struct timespec tp; 714 int cc; 715 struct sockaddr_inarp *ar, *ar2; 716 struct sockaddr_dl *ll, *ll2; 717 struct rt_msghdr *rt; 718 int xtype, xindex; 719 static pid_t pid; 720 int r; 721 static int seq; 722 723 r = socket(PF_ROUTE, SOCK_RAW, 0); 724 if (r == -1) { 725 logmsg(LOG_ERR, "raw route socket: %m"); 726 pidfile_remove(pidfile_fh); 727 exit(1); 728 } 729 pid = getpid(); 730 731 ar = &sin_inarp; 732 ar->sin_addr.s_addr = ipaddr; 733 ll = &sin_dl; 734 bcopy(ep, LLADDR(ll), 6); 735 736 /* Get the type and interface index */ 737 rt = &rtmsg.rthdr; 738 bzero(rt, sizeof(rtmsg)); 739 rt->rtm_version = RTM_VERSION; 740 rt->rtm_addrs = RTA_DST; 741 rt->rtm_type = RTM_GET; 742 rt->rtm_seq = ++seq; 743 ar2 = (struct sockaddr_inarp *)rtmsg.rtspace; 744 bcopy(ar, ar2, sizeof(*ar)); 745 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar); 746 errno = 0; 747 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) { 748 logmsg(LOG_ERR, "rtmsg get write: %m"); 749 close(r); 750 return; 751 } 752 do { 753 cc = read(r, rt, sizeof(rtmsg)); 754 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); 755 if (cc == -1) { 756 logmsg(LOG_ERR, "rtmsg get read: %m"); 757 close(r); 758 return; 759 } 760 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len); 761 if (ll2->sdl_family != AF_LINK) { 762 /* 763 * XXX I think this means the ip address is not on a 764 * directly connected network (the family is AF_INET in 765 * this case). 766 */ 767 logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08X?\n", 768 ll2->sdl_family, ipaddr); 769 close(r); 770 return; 771 } 772 xtype = ll2->sdl_type; 773 xindex = ll2->sdl_index; 774 775 /* Set the new arp entry */ 776 bzero(rt, sizeof(rtmsg)); 777 rt->rtm_version = RTM_VERSION; 778 rt->rtm_addrs = RTA_DST | RTA_GATEWAY; 779 rt->rtm_inits = RTV_EXPIRE; 780 clock_gettime(CLOCK_MONOTONIC, &tp); 781 rt->rtm_rmx.rmx_expire = tp.tv_sec + ARPSECS; 782 rt->rtm_flags = RTF_HOST | RTF_STATIC; 783 rt->rtm_type = RTM_ADD; 784 rt->rtm_seq = ++seq; 785 786 bcopy(ar, ar2, sizeof(*ar)); 787 788 ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2)); 789 bcopy(ll, ll2, sizeof(*ll)); 790 ll2->sdl_type = xtype; 791 ll2->sdl_index = xindex; 792 793 rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2); 794 errno = 0; 795 if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) { 796 logmsg(LOG_ERR, "rtmsg add write: %m"); 797 close(r); 798 return; 799 } 800 do { 801 cc = read(r, rt, sizeof(rtmsg)); 802 } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid)); 803 close(r); 804 if (cc == -1) { 805 logmsg(LOG_ERR, "rtmsg add read: %m"); 806 return; 807 } 808 } 809 810 /* 811 * Build a reverse ARP packet and sent it out on the interface. 812 * 'ep' points to a valid REVARP_REQUEST. The REVARP_REPLY is built 813 * on top of the request, then written to the network. 814 * 815 * RFC 903 defines the ether_arp fields as follows. The following comments 816 * are taken (more or less) straight from this document. 817 * 818 * REVARP_REQUEST 819 * 820 * arp_sha is the hardware address of the sender of the packet. 821 * arp_spa is undefined. 822 * arp_tha is the 'target' hardware address. 823 * In the case where the sender wishes to determine his own 824 * protocol address, this, like arp_sha, will be the hardware 825 * address of the sender. 826 * arp_tpa is undefined. 827 * 828 * REVARP_REPLY 829 * 830 * arp_sha is the hardware address of the responder (the sender of the 831 * reply packet). 832 * arp_spa is the protocol address of the responder (see the note below). 833 * arp_tha is the hardware address of the target, and should be the same as 834 * that which was given in the request. 835 * arp_tpa is the protocol address of the target, that is, the desired address. 836 * 837 * Note that the requirement that arp_spa be filled in with the responder's 838 * protocol is purely for convenience. For instance, if a system were to use 839 * both ARP and RARP, then the inclusion of the valid protocol-hardware 840 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 841 * ARP request. 842 */ 843 static void 844 rarp_reply(struct if_info *ii, struct ether_header *ep, in_addr_t ipaddr, 845 u_int len) 846 { 847 u_int n; 848 struct ether_arp *ap = (struct ether_arp *)(ep + 1); 849 850 update_arptab((u_char *)&ap->arp_sha, ipaddr); 851 852 /* 853 * Build the rarp reply by modifying the rarp request in place. 854 */ 855 ap->arp_op = htons(REVARP_REPLY); 856 857 #ifdef BROKEN_BPF 858 ep->ether_type = ETHERTYPE_REVARP; 859 #endif 860 bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6); 861 bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6); 862 bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6); 863 864 bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4); 865 /* Target hardware is unchanged. */ 866 bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4); 867 868 /* Zero possible garbage after packet. */ 869 bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)), 870 len - (sizeof(*ep) + sizeof(*ap))); 871 n = write(ii->ii_fd, (char *)ep, len); 872 if (n != len) 873 logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len); 874 if (verbose) 875 logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname, 876 eatoa(ap->arp_tha), 877 intoa(ntohl(ipaddr))); 878 } 879 880 /* 881 * Get the netmask of an IP address. This routine is used if 882 * SIOCGIFNETMASK doesn't work. 883 */ 884 static in_addr_t 885 ipaddrtonetmask(in_addr_t addr) 886 { 887 addr = ntohl(addr); 888 if (IN_CLASSA(addr)) 889 return htonl(IN_CLASSA_NET); 890 if (IN_CLASSB(addr)) 891 return htonl(IN_CLASSB_NET); 892 if (IN_CLASSC(addr)) 893 return htonl(IN_CLASSC_NET); 894 logmsg(LOG_DEBUG, "unknown IP address class: %08X", addr); 895 return htonl(0xffffffff); 896 } 897 898 /* 899 * A faster replacement for inet_ntoa(). 900 */ 901 static char * 902 intoa(in_addr_t addr) 903 { 904 char *cp; 905 u_int byte; 906 int n; 907 static char buf[sizeof(".xxx.xxx.xxx.xxx")]; 908 909 cp = &buf[sizeof buf]; 910 *--cp = '\0'; 911 912 n = 4; 913 do { 914 byte = addr & 0xff; 915 *--cp = byte % 10 + '0'; 916 byte /= 10; 917 if (byte > 0) { 918 *--cp = byte % 10 + '0'; 919 byte /= 10; 920 if (byte > 0) 921 *--cp = byte + '0'; 922 } 923 *--cp = '.'; 924 addr >>= 8; 925 } while (--n > 0); 926 927 return cp + 1; 928 } 929 930 static char * 931 eatoa(u_char *ea) 932 { 933 static char buf[sizeof("xx:xx:xx:xx:xx:xx")]; 934 935 (void)sprintf(buf, "%x:%x:%x:%x:%x:%x", 936 ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]); 937 return (buf); 938 } 939 940 static void 941 logmsg(int pri, const char *fmt, ...) 942 { 943 va_list v; 944 FILE *fp; 945 char *newfmt; 946 947 va_start(v, fmt); 948 if (dflag) { 949 if (pri == LOG_ERR) 950 fp = stderr; 951 else 952 fp = stdout; 953 if (expand_syslog_m(fmt, &newfmt) == -1) { 954 vfprintf(fp, fmt, v); 955 } else { 956 vfprintf(fp, newfmt, v); 957 free(newfmt); 958 } 959 fputs("\n", fp); 960 fflush(fp); 961 } else { 962 vsyslog(pri, fmt, v); 963 } 964 va_end(v); 965 } 966 967 static int 968 expand_syslog_m(const char *fmt, char **newfmt) { 969 const char *str, *m; 970 char *p, *np; 971 972 p = strdup(""); 973 str = fmt; 974 while ((m = strstr(str, "%m")) != NULL) { 975 asprintf(&np, "%s%.*s%s", p, (int)(m - str), 976 str, strerror(errno)); 977 free(p); 978 if (np == NULL) { 979 errno = ENOMEM; 980 return (-1); 981 } 982 p = np; 983 str = m + 2; 984 } 985 986 if (*str != '\0') { 987 asprintf(&np, "%s%s", p, str); 988 free(p); 989 if (np == NULL) { 990 errno = ENOMEM; 991 return (-1); 992 } 993 p = np; 994 } 995 996 *newfmt = p; 997 return (0); 998 } 999