1 /* $NetBSD: rarpd.c,v 1.52 2004/09/07 13:20:40 jrf Exp $ */ 2 3 /* 4 * Copyright (c) 1990 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that: (1) source code distributions 9 * retain the above copyright notice and this paragraph in its entirety, (2) 10 * distributions including binary code include the above copyright notice and 11 * this paragraph in its entirety in the documentation or other materials 12 * provided with the distribution, and (3) all advertising materials mentioning 13 * features or use of this software display the following acknowledgement: 14 * ``This product includes software developed by the University of California, 15 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 16 * the University nor the names of its contributors may be used to endorse 17 * or promote products derived from this software without specific prior 18 * written permission. 19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 20 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 21 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 22 */ 23 #include <sys/cdefs.h> 24 #ifndef lint 25 __COPYRIGHT( 26 "@(#) Copyright (c) 1990 The Regents of the University of California.\n\ 27 All rights reserved.\n"); 28 #endif /* not lint */ 29 30 #ifndef lint 31 __RCSID("$NetBSD: rarpd.c,v 1.52 2004/09/07 13:20:40 jrf Exp $"); 32 #endif 33 34 35 /* 36 * rarpd - Reverse ARP Daemon 37 * 38 * Usage: rarpd -a [-d|-f] [-l] 39 * rarpd [-d|-f] [-l] interface [...] 40 */ 41 42 #include <sys/param.h> 43 #include <sys/file.h> 44 #include <sys/time.h> 45 #include <sys/socket.h> 46 #include <sys/ioctl.h> 47 48 #include <net/bpf.h> 49 #include <net/if.h> 50 #include <net/if_dl.h> 51 #ifdef __NetBSD__ 52 #include <net/if_ether.h> 53 #endif 54 #include <net/if_types.h> 55 #include <netinet/in.h> 56 #ifdef __NetBSD__ 57 #include <netinet/if_inarp.h> 58 #else 59 #include <netinet/if_ether.h> 60 #endif 61 62 #include <arpa/inet.h> 63 64 #include <errno.h> 65 #include <dirent.h> 66 #include <netdb.h> 67 #include <stdio.h> 68 #include <stdlib.h> 69 #include <string.h> 70 #include <syslog.h> 71 #include <unistd.h> 72 #include <util.h> 73 #include <ifaddrs.h> 74 75 #define FATAL 1 /* fatal error occurred */ 76 #define NONFATAL 0 /* non fatal error occurred */ 77 78 /* 79 * The structure for each interface. 80 */ 81 struct if_info { 82 int ii_fd; /* BPF file descriptor */ 83 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 84 u_int32_t ii_ipaddr; /* IP address of this interface */ 85 u_int32_t ii_netmask; /* subnet or net mask */ 86 char *ii_name; /* interface name */ 87 struct if_info *ii_alias; 88 struct if_info *ii_next; 89 }; 90 /* 91 * The list of all interfaces that are being listened to. rarp_loop() 92 * "selects" on the descriptors in this list. 93 */ 94 struct if_info *iflist; 95 96 u_int32_t choose_ipaddr(u_int32_t **, u_int32_t, u_int32_t); 97 void debug(const char *,...) 98 __attribute__((__format__(__printf__, 1, 2))); 99 void init_some(char *name); 100 void init_one(char *, u_int32_t); 101 u_int32_t ipaddrtonetmask(u_int32_t); 102 void lookup_eaddr(char *, u_char *); 103 void lookup_ipaddr(char *, u_int32_t *, u_int32_t *); 104 int main(int, char **); 105 void rarp_loop(void); 106 int rarp_open(char *); 107 void rarp_process(struct if_info *, u_char *); 108 void rarp_reply(struct if_info *, struct ether_header *, u_int32_t, 109 struct hostent *); 110 void rarperr(int, const char *,...) 111 __attribute__((__format__(__printf__, 2, 3))); 112 113 #if defined(__NetBSD__) 114 #include "mkarp.h" 115 #else 116 void update_arptab(u_char *, u_int32_t); 117 #endif 118 119 void usage(void); 120 121 static int bpf_open(void); 122 static int rarp_check(u_char *, int); 123 124 #ifdef REQUIRE_TFTPBOOT 125 int rarp_bootable(u_int32_t); 126 #endif 127 128 int aflag = 0; /* listen on "all" interfaces */ 129 int dflag = 0; /* print debugging messages */ 130 int fflag = 0; /* don't fork */ 131 int lflag = 0; /* log all replies */ 132 133 int 134 main(int argc, char **argv) 135 { 136 int op; 137 138 /* All error reporting is done through syslogs. */ 139 openlog("rarpd", LOG_PID, LOG_DAEMON); 140 141 opterr = 0; 142 while ((op = getopt(argc, argv, "adfl")) != -1) { 143 switch (op) { 144 case 'a': 145 ++aflag; 146 break; 147 148 case 'd': 149 ++dflag; 150 break; 151 152 case 'f': 153 ++fflag; 154 break; 155 156 case 'l': 157 ++lflag; 158 break; 159 160 default: 161 usage(); 162 /* NOTREACHED */ 163 } 164 } 165 argc -= optind; 166 argv += optind; 167 168 if ((aflag && argc != 0) || (!aflag && argc == 0)) 169 usage(); 170 171 if ((!fflag) && (!dflag)) { 172 if (daemon(0, 0)) 173 rarperr(FATAL, "daemon"); 174 pidfile(NULL); 175 } 176 177 if (aflag) 178 init_some(NULL); 179 else { 180 while (argc--) 181 init_some(*argv++); 182 } 183 184 rarp_loop(); 185 /* NOTREACHED */ 186 return (0); 187 } 188 189 /* 190 * Add 'ifname' to the interface list. Lookup its IP address and network 191 * mask and Ethernet address, and open a BPF file for it. 192 */ 193 void 194 init_one(char *ifname, u_int32_t ipaddr) 195 { 196 struct if_info *h; 197 struct if_info *p; 198 int fd; 199 200 for (h = iflist; h != NULL; h = h->ii_next) { 201 if (!strcmp(h->ii_name, ifname)) 202 break; 203 } 204 if (h == NULL) { 205 fd = rarp_open(ifname); 206 if (fd < 0) 207 return; 208 } else { 209 fd = h->ii_fd; 210 } 211 212 p = (struct if_info *)malloc(sizeof(*p)); 213 if (p == 0) { 214 rarperr(FATAL, "malloc: %s", strerror(errno)); 215 /* NOTREACHED */ 216 } 217 p->ii_name = strdup(ifname); 218 if (p->ii_name == 0) { 219 rarperr(FATAL, "malloc: %s", strerror(errno)); 220 /* NOTREACHED */ 221 } 222 if (h != NULL) { 223 p->ii_alias = h->ii_alias; 224 h->ii_alias = p; 225 } else { 226 p->ii_next = iflist; 227 iflist = p; 228 } 229 230 p->ii_fd = fd; 231 p->ii_ipaddr = ipaddr; 232 lookup_eaddr(ifname, p->ii_eaddr); 233 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 234 } 235 236 /* 237 * Initialize all "candidate" interfaces that are in the system 238 * configuration list. A "candidate" is up, not loopback and not 239 * point to point. 240 */ 241 void 242 init_some(char *name) 243 { 244 struct ifaddrs *ifap, *ifa, *p; 245 246 if (getifaddrs(&ifap) != 0) { 247 rarperr(FATAL, "getifaddrs: %s", strerror(errno)); 248 /* NOTREACHED */ 249 } 250 251 p = NULL; 252 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 253 #define SIN(s) ((struct sockaddr_in *) (s)) 254 if (ifa->ifa_addr->sa_family != AF_INET) 255 continue; 256 if (name && strcmp(name, ifa->ifa_name)) 257 continue; 258 if (p && !strcmp(p->ifa_name, ifa->ifa_name) && 259 SIN(p->ifa_addr)->sin_addr.s_addr == SIN(ifa->ifa_addr)->sin_addr.s_addr) 260 continue; 261 p = ifa; 262 if ((ifa->ifa_flags & 263 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 264 continue; 265 init_one(ifa->ifa_name, SIN(ifa->ifa_addr)->sin_addr.s_addr); 266 #undef SIN 267 } 268 freeifaddrs(ifap); 269 } 270 271 void 272 usage(void) 273 { 274 (void) fprintf(stderr, "usage: rarpd -a [-d|-f] [-l]\n"); 275 (void) fprintf(stderr, " rarpd [-d|-f] [-l] interface [...]\n"); 276 exit(1); 277 } 278 279 static int 280 bpf_open(void) 281 { 282 int fd; 283 int n = 0; 284 char device[sizeof "/dev/bpf000"]; 285 286 /* Go through all the minors and find one that isn't in use. */ 287 do { 288 (void)snprintf(device, sizeof(device), "/dev/bpf%d", n++); 289 fd = open(device, O_RDWR); 290 } while (fd < 0 && errno == EBUSY); 291 292 if (fd < 0) { 293 rarperr(FATAL, "%s: %s", device, strerror(errno)); 294 /* NOTREACHED */ 295 } 296 return fd; 297 } 298 /* 299 * Open a BPF file and attach it to the interface named 'device'. 300 * Set immediate mode, and set a filter that accepts only RARP requests. 301 */ 302 int 303 rarp_open(char *device) 304 { 305 int fd; 306 struct ifreq ifr; 307 u_int dlt; 308 int immediate; 309 u_int bufsize; 310 311 static struct bpf_insn insns[] = { 312 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 313 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 314 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 315 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 316 BPF_STMT(BPF_RET | BPF_K, 317 sizeof(struct arphdr) + 318 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 319 sizeof(struct ether_header)), 320 BPF_STMT(BPF_RET | BPF_K, 0), 321 }; 322 static struct bpf_program filter = { 323 sizeof insns / sizeof(insns[0]), 324 insns 325 }; 326 327 fd = bpf_open(); 328 329 /* Set immediate mode so packets are processed as they arrive. */ 330 immediate = 1; 331 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 332 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 333 /* NOTREACHED */ 334 } 335 /* Set a 32k buffer size for kernel use */ 336 bufsize = 32768; 337 if (ioctl(fd, BIOCSBLEN, &bufsize) < 0) { 338 rarperr(NONFATAL, "BIOCSBLEN:%d: %s", bufsize, strerror(errno)); 339 } 340 (void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 341 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 342 if (aflag) { /* for -a skip non-ethernet interfaces */ 343 close(fd); 344 return(-1); 345 } 346 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 347 /* NOTREACHED */ 348 } 349 /* Check that the data link layer is an Ethernet; this code won't work 350 * with anything else. */ 351 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 352 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 353 /* NOTREACHED */ 354 } 355 if (dlt != DLT_EN10MB) { 356 if (aflag) { /* for -a skip non-ethernet interfaces */ 357 close(fd); 358 return(-1); 359 } 360 rarperr(FATAL, "%s is not an ethernet", device); 361 /* NOTREACHED */ 362 } 363 /* Set filter program. */ 364 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 365 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 366 /* NOTREACHED */ 367 } 368 return fd; 369 } 370 /* 371 * Perform various sanity checks on the RARP request packet. Return 372 * false on failure and log the reason. 373 */ 374 static int 375 rarp_check(u_char *p, int len) 376 { 377 struct ether_header *ep = (struct ether_header *) p; 378 #ifdef __NetBSD__ 379 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 380 #else 381 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 382 #endif 383 384 if (len < sizeof(*ep) + sizeof(*ap)) { 385 rarperr(NONFATAL, "truncated request"); 386 return 0; 387 } 388 #ifdef __NetBSD__ 389 /* now that we know the fixed part of the ARP hdr is there: */ 390 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 391 rarperr(NONFATAL, "truncated request"); 392 return 0; 393 } 394 #endif 395 /* XXX This test might be better off broken out... */ 396 #ifdef __FreeBSD__ 397 /* BPF (incorrectly) returns this in host order. */ 398 if (ep->ether_type != ETHERTYPE_REVARP || 399 #else 400 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 401 #endif 402 #ifdef __NetBSD__ 403 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 404 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 405 ntohs (ap->ar_pro) != ETHERTYPE_IP || 406 ap->ar_hln != 6 || ap->ar_pln != 4) { 407 #else 408 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 409 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 410 ntohs (ap->arp_pro) != ETHERTYPE_IP || 411 ap->arp_hln != 6 || ap->arp_pln != 4) { 412 #endif 413 rarperr(NONFATAL, "request fails sanity check"); 414 return 0; 415 } 416 #ifdef __NetBSD__ 417 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 418 #else 419 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 420 #endif 421 rarperr(NONFATAL, "ether/arp sender address mismatch"); 422 return 0; 423 } 424 #ifdef __NetBSD__ 425 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 426 #else 427 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 428 #endif 429 rarperr(NONFATAL, "ether/arp target address mismatch"); 430 return 0; 431 } 432 return 1; 433 } 434 435 /* 436 * Loop indefinitely listening for RARP requests on the 437 * interfaces in 'iflist'. 438 */ 439 void 440 rarp_loop(void) 441 { 442 u_char *buf, *bp, *ep; 443 int cc, fd; 444 fd_set fds, listeners; 445 int bufsize, maxfd = 0; 446 struct if_info *ii; 447 448 if (iflist == 0) { 449 rarperr(FATAL, "no interfaces"); 450 /* NOTREACHED */ 451 } 452 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 453 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 454 /* NOTREACHED */ 455 } 456 buf = (u_char *) malloc((unsigned) bufsize); 457 if (buf == 0) { 458 rarperr(FATAL, "malloc: %s", strerror(errno)); 459 /* NOTREACHED */ 460 } 461 /* 462 * Find the highest numbered file descriptor for select(). 463 * Initialize the set of descriptors to listen to. 464 */ 465 FD_ZERO(&fds); 466 for (ii = iflist; ii; ii = ii->ii_next) { 467 FD_SET(ii->ii_fd, &fds); 468 if (ii->ii_fd > maxfd) 469 maxfd = ii->ii_fd; 470 } 471 while (1) { 472 listeners = fds; 473 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 474 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 475 rarperr(FATAL, "select: %s", strerror(errno)); 476 /* NOTREACHED */ 477 } 478 for (ii = iflist; ii; ii = ii->ii_next) { 479 fd = ii->ii_fd; 480 if (!FD_ISSET(fd, &listeners)) 481 continue; 482 again: 483 cc = read(fd, (char *) buf, bufsize); 484 /* Don't choke when we get ptraced */ 485 if (cc < 0 && errno == EINTR) 486 goto again; 487 /* Due to a SunOS bug, after 2^31 bytes, the file 488 * offset overflows and read fails with EINVAL. The 489 * lseek() to 0 will fix things. */ 490 if (cc < 0) { 491 if (errno == EINVAL && 492 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 493 (void)lseek(fd, 0, 0); 494 goto again; 495 } 496 rarperr(FATAL, "read: %s", strerror(errno)); 497 /* NOTREACHED */ 498 } 499 /* Loop through the packet(s) */ 500 #define bhp ((struct bpf_hdr *)bp) 501 bp = buf; 502 ep = bp + cc; 503 while (bp < ep) { 504 int caplen, hdrlen; 505 506 caplen = bhp->bh_caplen; 507 hdrlen = bhp->bh_hdrlen; 508 debug("received packet on %s", ii->ii_name); 509 510 if (rarp_check(bp + hdrlen, caplen)) 511 rarp_process(ii, bp + hdrlen); 512 bp += BPF_WORDALIGN(hdrlen + caplen); 513 } 514 } 515 } 516 } 517 518 #ifdef REQUIRE_TFTPBOOT 519 520 #ifndef TFTP_DIR 521 #define TFTP_DIR "/tftpboot" 522 #endif 523 524 /* 525 * True if this server can boot the host whose IP address is 'addr'. 526 * This check is made by looking in the tftp directory for the 527 * configuration file. 528 */ 529 int 530 rarp_bootable(u_int32_t addr) 531 { 532 struct dirent *dent; 533 DIR *d; 534 char ipname[9]; 535 static DIR *dd = 0; 536 537 (void)snprintf(ipname, sizeof(ipname), "%08X", addr); 538 /* If directory is already open, rewind it. Otherwise, open it. */ 539 if (d = dd) 540 rewinddir(d); 541 else { 542 if (chdir(TFTP_DIR) == -1) { 543 rarperr(FATAL, "chdir: %s", strerror(errno)); 544 /* NOTREACHED */ 545 } 546 d = opendir("."); 547 if (d == 0) { 548 rarperr(FATAL, "opendir: %s", strerror(errno)); 549 /* NOTREACHED */ 550 } 551 dd = d; 552 } 553 while (dent = readdir(d)) 554 if (strncmp(dent->d_name, ipname, 8) == 0) 555 return 1; 556 return 0; 557 } 558 #endif /* REQUIRE_TFTPBOOT */ 559 560 /* 561 * Given a list of IP addresses, 'alist', return the first address that 562 * is on network 'net'; 'netmask' is a mask indicating the network portion 563 * of the address. 564 */ 565 u_int32_t 566 choose_ipaddr(u_int32_t **alist, u_int32_t net, u_int32_t netmask) 567 { 568 569 for (; *alist; ++alist) { 570 if ((**alist & netmask) == net) 571 return **alist; 572 } 573 return 0; 574 } 575 /* 576 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 577 * already been checked for validity. The reply is overlaid on the request. 578 */ 579 void 580 rarp_process(struct if_info *ii, u_char *pkt) 581 { 582 struct ether_header *ep; 583 struct hostent *hp; 584 u_int32_t target_ipaddr = 0; 585 char ename[MAXHOSTNAMELEN + 1]; 586 struct in_addr in; 587 588 ep = (struct ether_header *) pkt; 589 590 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 591 debug("no IP address for %s", 592 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 593 return; 594 } 595 ename[sizeof(ename)-1] = '\0'; 596 597 if ((hp = gethostbyname(ename)) == 0) { 598 debug("gethostbyname(%s) failed: %s", ename, 599 hstrerror(h_errno)); 600 return; 601 } 602 603 /* Choose correct address from list. */ 604 if (hp->h_addrtype != AF_INET) { 605 rarperr(FATAL, "cannot handle non IP addresses"); 606 /* NOTREACHED */ 607 } 608 for (;; ii = ii->ii_alias) { 609 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 610 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 611 if (target_ipaddr != 0) 612 break; 613 if (ii->ii_alias == NULL) 614 break; 615 } 616 617 if (target_ipaddr == 0) { 618 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 619 rarperr(NONFATAL, "cannot find %s on net %s", 620 ename, inet_ntoa(in)); 621 return; 622 } 623 #ifdef REQUIRE_TFTPBOOT 624 if (rarp_bootable(htonl(target_ipaddr))) 625 #endif 626 rarp_reply(ii, ep, target_ipaddr, hp); 627 #ifdef REQUIRE_TFTPBOOT 628 else 629 debug("%08X not bootable", htonl(target_ipaddr)); 630 #endif 631 } 632 /* 633 * Lookup the ethernet address of the interface attached to the BPF 634 * file descriptor 'fd'; return it in 'eaddr'. 635 */ 636 void 637 lookup_eaddr(char *ifname, u_char *eaddr) 638 { 639 struct ifaddrs *ifap, *ifa; 640 struct sockaddr_dl *sdl; 641 642 if (getifaddrs(&ifap) != 0) { 643 rarperr(FATAL, "getifaddrs: %s", strerror(errno)); 644 /* NOTREACHED */ 645 } 646 647 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 648 sdl = (struct sockaddr_dl *)ifa->ifa_addr; 649 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 650 sdl->sdl_alen != 6) 651 continue; 652 if (!strcmp(ifa->ifa_name, ifname)) { 653 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 654 debug("%s: %x:%x:%x:%x:%x:%x", 655 ifa->ifa_name, eaddr[0], eaddr[1], 656 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 657 freeifaddrs(ifap); 658 return; 659 } 660 } 661 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 662 freeifaddrs(ifap); 663 } 664 /* 665 * Lookup the IP address and network mask of the interface named 'ifname'. 666 */ 667 void 668 lookup_ipaddr(char *ifname, u_int32_t *addrp, u_int32_t *netmaskp) 669 { 670 int fd; 671 672 /* Use datagram socket to get IP address. */ 673 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 674 rarperr(FATAL, "socket: %s", strerror(errno)); 675 /* NOTREACHED */ 676 } 677 if (*addrp == INADDR_ANY) { 678 struct ifreq ifr; 679 memset(&ifr, 0, sizeof(ifr)); 680 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 681 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 682 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 683 /* NOTREACHED */ 684 } 685 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 686 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 687 perror("SIOCGIFNETMASK"); 688 exit(1); 689 } 690 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 691 } else { 692 struct ifaliasreq ifra; 693 memset(&ifra, 0, sizeof(ifra)); 694 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 695 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 696 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 697 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 698 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 699 /* NOTREACHED */ 700 } 701 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 702 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 703 } 704 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 705 * address class. */ 706 if (*netmaskp == 0) 707 *netmaskp = ipaddrtonetmask(*addrp); 708 709 (void)close(fd); 710 } 711 /* 712 * Poke the kernel arp tables with the ethernet/ip address combinataion 713 * given. When processing a reply, we must do this so that the booting 714 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 715 * address of the guy being booted (he cannot answer the ARP). 716 */ 717 #ifndef __NetBSD__ 718 void 719 update_arptab(u_char *ep, u_int32_t ipaddr) 720 { 721 struct arpreq request; 722 struct sockaddr_in *sin; 723 724 request.arp_flags = 0; 725 sin = (struct sockaddr_in *) & request.arp_pa; 726 sin->sin_family = AF_INET; 727 sin->sin_addr.s_addr = ipaddr; 728 request.arp_ha.sa_family = AF_UNSPEC; 729 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 730 because AF_UNSPEC is zero and the kernel assumes that a zero 731 sa_family means that the real sa_family value is in sa_len. */ 732 request.arp_ha.sa_len = 16; /* XXX */ 733 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 734 735 #if 0 736 s = socket(AF_INET, SOCK_DGRAM, 0); 737 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 738 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 739 } 740 (void)close(s); 741 #endif 742 } 743 #endif 744 745 /* 746 * Build a reverse ARP packet and sent it out on the interface. 747 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 748 * on top of the request, then written to the network. 749 * 750 * RFC 903 defines the ether_arp fields as follows. The following comments 751 * are taken (more or less) straight from this document. 752 * 753 * ARPOP_REVREQUEST 754 * 755 * arp_sha is the hardware address of the sender of the packet. 756 * arp_spa is undefined. 757 * arp_tha is the 'target' hardware address. 758 * In the case where the sender wishes to determine his own 759 * protocol address, this, like arp_sha, will be the hardware 760 * address of the sender. 761 * arp_tpa is undefined. 762 * 763 * ARPOP_REVREPLY 764 * 765 * arp_sha is the hardware address of the responder (the sender of the 766 * reply packet). 767 * arp_spa is the protocol address of the responder (see the note below). 768 * arp_tha is the hardware address of the target, and should be the same as 769 * that which was given in the request. 770 * arp_tpa is the protocol address of the target, that is, the desired address. 771 * 772 * Note that the requirement that arp_spa be filled in with the responder's 773 * protocol is purely for convenience. For instance, if a system were to use 774 * both ARP and RARP, then the inclusion of the valid protocol-hardware 775 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 776 * ARP request. 777 */ 778 void 779 rarp_reply(struct if_info *ii, struct ether_header *ep, u_int32_t ipaddr, 780 struct hostent *hp) 781 { 782 int n; 783 #ifdef __NetBSD__ 784 struct arphdr *ap = (struct arphdr *) (ep + 1); 785 #else 786 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 787 #endif 788 789 int len; 790 791 #ifdef __NetBSD__ 792 (void)mkarp(ar_sha(ap), ipaddr); 793 #else 794 update_arptab((u_char *) & ap->arp_sha, ipaddr); 795 #endif 796 797 /* Build the rarp reply by modifying the rarp request in place. */ 798 #ifdef __FreeBSD__ 799 /* BPF (incorrectly) wants this in host order. */ 800 ep->ether_type = ETHERTYPE_REVARP; 801 #else 802 ep->ether_type = htons(ETHERTYPE_REVARP); 803 #endif 804 #ifdef __NetBSD__ 805 ap->ar_hrd = htons(ARPHRD_ETHER); 806 ap->ar_pro = htons(ETHERTYPE_IP); 807 ap->ar_op = htons(ARPOP_REVREPLY); 808 809 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 810 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 811 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 812 813 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 814 /* Target hardware is unchanged. */ 815 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 816 817 len = sizeof(*ep) + sizeof(*ap) + 818 2 * ap->ar_pln + 2 * ap->ar_hln; 819 #else 820 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 821 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 822 ap->arp_op = htons(ARPOP_REVREPLY); 823 824 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 825 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 826 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 827 828 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 829 /* Target hardware is unchanged. */ 830 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 831 832 len = sizeof(*ep) + sizeof(*ap); 833 #endif 834 835 debug("%s asked; %s replied", 836 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 837 if (lflag) 838 syslog(LOG_INFO, "%s asked; %s replied", 839 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 840 n = write(ii->ii_fd, (char *) ep, len); 841 if (n != len) { 842 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 843 } 844 } 845 /* 846 * Get the netmask of an IP address. This routine is used if 847 * SIOCGIFNETMASK doesn't work. 848 */ 849 u_int32_t 850 ipaddrtonetmask(u_int32_t addr) 851 { 852 853 if (IN_CLASSA(addr)) 854 return IN_CLASSA_NET; 855 if (IN_CLASSB(addr)) 856 return IN_CLASSB_NET; 857 if (IN_CLASSC(addr)) 858 return IN_CLASSC_NET; 859 rarperr(FATAL, "unknown IP address class: %08X", addr); 860 /* NOTREACHED */ 861 return(-1); 862 } 863 864 #include <stdarg.h> 865 866 void 867 rarperr(int fatal, const char *fmt,...) 868 { 869 va_list ap; 870 871 va_start(ap, fmt); 872 if (dflag) { 873 if (fatal) 874 (void)fprintf(stderr, "rarpd: error: "); 875 else 876 (void)fprintf(stderr, "rarpd: warning: "); 877 (void)vfprintf(stderr, fmt, ap); 878 va_end(ap); 879 va_start(ap, fmt); 880 (void)fprintf(stderr, "\n"); 881 } 882 vsyslog(LOG_ERR, fmt, ap); 883 va_end(ap); 884 if (fatal) 885 exit(1); 886 /* NOTREACHED */ 887 } 888 889 void 890 debug(const char *fmt,...) 891 { 892 va_list ap; 893 894 va_start(ap, fmt); 895 if (dflag) { 896 (void)fprintf(stderr, "rarpd: "); 897 (void)vfprintf(stderr, fmt, ap); 898 va_end(ap); 899 va_start(ap, fmt); 900 (void)fprintf(stderr, "\n"); 901 } 902 vsyslog(LOG_WARNING, fmt, ap); 903 va_end(ap); 904 } 905