1 /* $NetBSD: rarpd.c,v 1.48 2003/05/15 14:50:02 itojun 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 1.48 2003/05/15 14:50:02 itojun 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_all(void); 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_all(); 179 else { 180 while (argc--) 181 init_one(*argv++, INADDR_ANY); 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_all(void) 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 (p && !strcmp(p->ifa_name, ifa->ifa_name) && 257 SIN(p->ifa_addr)->sin_addr.s_addr == SIN(ifa->ifa_addr)->sin_addr.s_addr) 258 continue; 259 p = ifa; 260 if ((ifa->ifa_flags & 261 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 262 continue; 263 init_one(ifa->ifa_name, SIN(ifa->ifa_addr)->sin_addr.s_addr); 264 #undef SIN 265 } 266 freeifaddrs(ifap); 267 } 268 269 void 270 usage(void) 271 { 272 (void) fprintf(stderr, "usage: rarpd -a [-d|-f] [-l]\n"); 273 (void) fprintf(stderr, " rarpd [-d|-f] [-l] interface [...]\n"); 274 exit(1); 275 } 276 277 static int 278 bpf_open(void) 279 { 280 int fd; 281 int n = 0; 282 char device[sizeof "/dev/bpf000"]; 283 284 /* Go through all the minors and find one that isn't in use. */ 285 do { 286 (void)sprintf(device, "/dev/bpf%d", n++); 287 fd = open(device, O_RDWR); 288 } while (fd < 0 && errno == EBUSY); 289 290 if (fd < 0) { 291 rarperr(FATAL, "%s: %s", device, strerror(errno)); 292 /* NOTREACHED */ 293 } 294 return fd; 295 } 296 /* 297 * Open a BPF file and attach it to the interface named 'device'. 298 * Set immediate mode, and set a filter that accepts only RARP requests. 299 */ 300 int 301 rarp_open(char *device) 302 { 303 int fd; 304 struct ifreq ifr; 305 u_int dlt; 306 int immediate; 307 308 static struct bpf_insn insns[] = { 309 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 310 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 311 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 312 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 313 BPF_STMT(BPF_RET | BPF_K, 314 sizeof(struct arphdr) + 315 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 316 sizeof(struct ether_header)), 317 BPF_STMT(BPF_RET | BPF_K, 0), 318 }; 319 static struct bpf_program filter = { 320 sizeof insns / sizeof(insns[0]), 321 insns 322 }; 323 324 fd = bpf_open(); 325 326 /* Set immediate mode so packets are processed as they arrive. */ 327 immediate = 1; 328 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 329 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 330 /* NOTREACHED */ 331 } 332 (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name - 1); 333 ifr.ifr_name[sizeof ifr.ifr_name - 1] = '\0'; 334 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 335 if (aflag) { /* for -a skip non-ethernet interfaces */ 336 close(fd); 337 return(-1); 338 } 339 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 340 /* NOTREACHED */ 341 } 342 /* Check that the data link layer is an Ethernet; this code won't work 343 * with anything else. */ 344 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 345 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 346 /* NOTREACHED */ 347 } 348 if (dlt != DLT_EN10MB) { 349 if (aflag) { /* for -a skip non-ethernet interfaces */ 350 close(fd); 351 return(-1); 352 } 353 rarperr(FATAL, "%s is not an ethernet", device); 354 /* NOTREACHED */ 355 } 356 /* Set filter program. */ 357 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 358 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 359 /* NOTREACHED */ 360 } 361 return fd; 362 } 363 /* 364 * Perform various sanity checks on the RARP request packet. Return 365 * false on failure and log the reason. 366 */ 367 static int 368 rarp_check(u_char *p, int len) 369 { 370 struct ether_header *ep = (struct ether_header *) p; 371 #ifdef __NetBSD__ 372 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 373 #else 374 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 375 #endif 376 377 if (len < sizeof(*ep) + sizeof(*ap)) { 378 rarperr(NONFATAL, "truncated request"); 379 return 0; 380 } 381 #ifdef __NetBSD__ 382 /* now that we know the fixed part of the ARP hdr is there: */ 383 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 384 rarperr(NONFATAL, "truncated request"); 385 return 0; 386 } 387 #endif 388 /* XXX This test might be better off broken out... */ 389 #ifdef __FreeBSD__ 390 /* BPF (incorrectly) returns this in host order. */ 391 if (ep->ether_type != ETHERTYPE_REVARP || 392 #else 393 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 394 #endif 395 #ifdef __NetBSD__ 396 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 397 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 398 ntohs (ap->ar_pro) != ETHERTYPE_IP || 399 ap->ar_hln != 6 || ap->ar_pln != 4) { 400 #else 401 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 402 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 403 ntohs (ap->arp_pro) != ETHERTYPE_IP || 404 ap->arp_hln != 6 || ap->arp_pln != 4) { 405 #endif 406 rarperr(NONFATAL, "request fails sanity check"); 407 return 0; 408 } 409 #ifdef __NetBSD__ 410 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 411 #else 412 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 413 #endif 414 rarperr(NONFATAL, "ether/arp sender address mismatch"); 415 return 0; 416 } 417 #ifdef __NetBSD__ 418 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 419 #else 420 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 421 #endif 422 rarperr(NONFATAL, "ether/arp target address mismatch"); 423 return 0; 424 } 425 return 1; 426 } 427 428 /* 429 * Loop indefinitely listening for RARP requests on the 430 * interfaces in 'iflist'. 431 */ 432 void 433 rarp_loop(void) 434 { 435 u_char *buf, *bp, *ep; 436 int cc, fd; 437 fd_set fds, listeners; 438 int bufsize, maxfd = 0; 439 struct if_info *ii; 440 441 if (iflist == 0) { 442 rarperr(FATAL, "no interfaces"); 443 /* NOTREACHED */ 444 } 445 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 446 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 447 /* NOTREACHED */ 448 } 449 buf = (u_char *) malloc((unsigned) bufsize); 450 if (buf == 0) { 451 rarperr(FATAL, "malloc: %s", strerror(errno)); 452 /* NOTREACHED */ 453 } 454 /* 455 * Find the highest numbered file descriptor for select(). 456 * Initialize the set of descriptors to listen to. 457 */ 458 FD_ZERO(&fds); 459 for (ii = iflist; ii; ii = ii->ii_next) { 460 FD_SET(ii->ii_fd, &fds); 461 if (ii->ii_fd > maxfd) 462 maxfd = ii->ii_fd; 463 } 464 while (1) { 465 listeners = fds; 466 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 467 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 468 rarperr(FATAL, "select: %s", strerror(errno)); 469 /* NOTREACHED */ 470 } 471 for (ii = iflist; ii; ii = ii->ii_next) { 472 fd = ii->ii_fd; 473 if (!FD_ISSET(fd, &listeners)) 474 continue; 475 again: 476 cc = read(fd, (char *) buf, bufsize); 477 /* Don't choke when we get ptraced */ 478 if (cc < 0 && errno == EINTR) 479 goto again; 480 /* Due to a SunOS bug, after 2^31 bytes, the file 481 * offset overflows and read fails with EINVAL. The 482 * lseek() to 0 will fix things. */ 483 if (cc < 0) { 484 if (errno == EINVAL && 485 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 486 (void)lseek(fd, 0, 0); 487 goto again; 488 } 489 rarperr(FATAL, "read: %s", strerror(errno)); 490 /* NOTREACHED */ 491 } 492 /* Loop through the packet(s) */ 493 #define bhp ((struct bpf_hdr *)bp) 494 bp = buf; 495 ep = bp + cc; 496 while (bp < ep) { 497 int caplen, hdrlen; 498 499 caplen = bhp->bh_caplen; 500 hdrlen = bhp->bh_hdrlen; 501 debug("received packet on %s", ii->ii_name); 502 503 if (rarp_check(bp + hdrlen, caplen)) 504 rarp_process(ii, bp + hdrlen); 505 bp += BPF_WORDALIGN(hdrlen + caplen); 506 } 507 } 508 } 509 } 510 511 #ifdef REQUIRE_TFTPBOOT 512 513 #ifndef TFTP_DIR 514 #define TFTP_DIR "/tftpboot" 515 #endif 516 517 /* 518 * True if this server can boot the host whose IP address is 'addr'. 519 * This check is made by looking in the tftp directory for the 520 * configuration file. 521 */ 522 int 523 rarp_bootable(u_int32_t addr) 524 { 525 struct dirent *dent; 526 DIR *d; 527 char ipname[9]; 528 static DIR *dd = 0; 529 530 (void)sprintf(ipname, "%08X", addr); 531 /* If directory is already open, rewind it. Otherwise, open it. */ 532 if (d = dd) 533 rewinddir(d); 534 else { 535 if (chdir(TFTP_DIR) == -1) { 536 rarperr(FATAL, "chdir: %s", strerror(errno)); 537 /* NOTREACHED */ 538 } 539 d = opendir("."); 540 if (d == 0) { 541 rarperr(FATAL, "opendir: %s", strerror(errno)); 542 /* NOTREACHED */ 543 } 544 dd = d; 545 } 546 while (dent = readdir(d)) 547 if (strncmp(dent->d_name, ipname, 8) == 0) 548 return 1; 549 return 0; 550 } 551 #endif /* REQUIRE_TFTPBOOT */ 552 553 /* 554 * Given a list of IP addresses, 'alist', return the first address that 555 * is on network 'net'; 'netmask' is a mask indicating the network portion 556 * of the address. 557 */ 558 u_int32_t 559 choose_ipaddr(u_int32_t **alist, u_int32_t net, u_int32_t netmask) 560 { 561 562 for (; *alist; ++alist) { 563 if ((**alist & netmask) == net) 564 return **alist; 565 } 566 return 0; 567 } 568 /* 569 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 570 * already been checked for validity. The reply is overlaid on the request. 571 */ 572 void 573 rarp_process(struct if_info *ii, u_char *pkt) 574 { 575 struct ether_header *ep; 576 struct hostent *hp; 577 u_int32_t target_ipaddr = 0; 578 char ename[MAXHOSTNAMELEN + 1]; 579 struct in_addr in; 580 581 ep = (struct ether_header *) pkt; 582 583 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 584 debug("no IP address for %s", 585 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 586 return; 587 } 588 ename[sizeof(ename)-1] = '\0'; 589 590 if ((hp = gethostbyname(ename)) == 0) { 591 debug("gethostbyname(%s) failed: %s", ename, 592 hstrerror(h_errno)); 593 return; 594 } 595 596 /* Choose correct address from list. */ 597 if (hp->h_addrtype != AF_INET) { 598 rarperr(FATAL, "cannot handle non IP addresses"); 599 /* NOTREACHED */ 600 } 601 for (;; ii = ii->ii_alias) { 602 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 603 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 604 if (target_ipaddr != 0) 605 break; 606 if (ii->ii_alias == NULL) 607 break; 608 } 609 610 if (target_ipaddr == 0) { 611 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 612 rarperr(NONFATAL, "cannot find %s on net %s", 613 ename, inet_ntoa(in)); 614 return; 615 } 616 #ifdef REQUIRE_TFTPBOOT 617 if (rarp_bootable(htonl(target_ipaddr))) 618 #endif 619 rarp_reply(ii, ep, target_ipaddr, hp); 620 #ifdef REQUIRE_TFTPBOOT 621 else 622 debug("%08X not bootable", htonl(target_ipaddr)); 623 #endif 624 } 625 /* 626 * Lookup the ethernet address of the interface attached to the BPF 627 * file descriptor 'fd'; return it in 'eaddr'. 628 */ 629 void 630 lookup_eaddr(char *ifname, u_char *eaddr) 631 { 632 struct ifaddrs *ifap, *ifa; 633 struct sockaddr_dl *sdl; 634 635 if (getifaddrs(&ifap) != 0) { 636 rarperr(FATAL, "getifaddrs: %s", strerror(errno)); 637 /* NOTREACHED */ 638 } 639 640 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 641 sdl = (struct sockaddr_dl *)ifa->ifa_addr; 642 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 643 sdl->sdl_alen != 6) 644 continue; 645 if (!strcmp(ifa->ifa_name, ifname)) { 646 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 647 debug("%s: %x:%x:%x:%x:%x:%x", 648 ifa->ifa_name, eaddr[0], eaddr[1], 649 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 650 freeifaddrs(ifap); 651 return; 652 } 653 } 654 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 655 freeifaddrs(ifap); 656 } 657 /* 658 * Lookup the IP address and network mask of the interface named 'ifname'. 659 */ 660 void 661 lookup_ipaddr(char *ifname, u_int32_t *addrp, u_int32_t *netmaskp) 662 { 663 int fd; 664 665 /* Use datagram socket to get IP address. */ 666 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 667 rarperr(FATAL, "socket: %s", strerror(errno)); 668 /* NOTREACHED */ 669 } 670 if (*addrp == INADDR_ANY) { 671 struct ifreq ifr; 672 memset(&ifr, 0, sizeof(ifr)); 673 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 674 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 675 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 676 /* NOTREACHED */ 677 } 678 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 679 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 680 perror("SIOCGIFNETMASK"); 681 exit(1); 682 } 683 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 684 } else { 685 struct ifaliasreq ifra; 686 memset(&ifra, 0, sizeof(ifra)); 687 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 688 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 689 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 690 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 691 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 692 /* NOTREACHED */ 693 } 694 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 695 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 696 } 697 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 698 * address class. */ 699 if (*netmaskp == 0) 700 *netmaskp = ipaddrtonetmask(*addrp); 701 702 (void)close(fd); 703 } 704 /* 705 * Poke the kernel arp tables with the ethernet/ip address combinataion 706 * given. When processing a reply, we must do this so that the booting 707 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 708 * address of the guy being booted (he cannot answer the ARP). 709 */ 710 #ifndef __NetBSD__ 711 void 712 update_arptab(u_char *ep, u_int32_t ipaddr) 713 { 714 struct arpreq request; 715 struct sockaddr_in *sin; 716 717 request.arp_flags = 0; 718 sin = (struct sockaddr_in *) & request.arp_pa; 719 sin->sin_family = AF_INET; 720 sin->sin_addr.s_addr = ipaddr; 721 request.arp_ha.sa_family = AF_UNSPEC; 722 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 723 because AF_UNSPEC is zero and the kernel assumes that a zero 724 sa_family means that the real sa_family value is in sa_len. */ 725 request.arp_ha.sa_len = 16; /* XXX */ 726 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 727 728 #if 0 729 s = socket(AF_INET, SOCK_DGRAM, 0); 730 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 731 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 732 } 733 (void)close(s); 734 #endif 735 } 736 #endif 737 738 /* 739 * Build a reverse ARP packet and sent it out on the interface. 740 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 741 * on top of the request, then written to the network. 742 * 743 * RFC 903 defines the ether_arp fields as follows. The following comments 744 * are taken (more or less) straight from this document. 745 * 746 * ARPOP_REVREQUEST 747 * 748 * arp_sha is the hardware address of the sender of the packet. 749 * arp_spa is undefined. 750 * arp_tha is the 'target' hardware address. 751 * In the case where the sender wishes to determine his own 752 * protocol address, this, like arp_sha, will be the hardware 753 * address of the sender. 754 * arp_tpa is undefined. 755 * 756 * ARPOP_REVREPLY 757 * 758 * arp_sha is the hardware address of the responder (the sender of the 759 * reply packet). 760 * arp_spa is the protocol address of the responder (see the note below). 761 * arp_tha is the hardware address of the target, and should be the same as 762 * that which was given in the request. 763 * arp_tpa is the protocol address of the target, that is, the desired address. 764 * 765 * Note that the requirement that arp_spa be filled in with the responder's 766 * protocol is purely for convenience. For instance, if a system were to use 767 * both ARP and RARP, then the inclusion of the valid protocol-hardware 768 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 769 * ARP request. 770 */ 771 void 772 rarp_reply(struct if_info *ii, struct ether_header *ep, u_int32_t ipaddr, 773 struct hostent *hp) 774 { 775 int n; 776 #ifdef __NetBSD__ 777 struct arphdr *ap = (struct arphdr *) (ep + 1); 778 #else 779 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 780 #endif 781 782 int len; 783 784 #ifdef __NetBSD__ 785 (void)mkarp(ar_sha(ap), ipaddr); 786 #else 787 update_arptab((u_char *) & ap->arp_sha, ipaddr); 788 #endif 789 790 /* Build the rarp reply by modifying the rarp request in place. */ 791 #ifdef __FreeBSD__ 792 /* BPF (incorrectly) wants this in host order. */ 793 ep->ether_type = ETHERTYPE_REVARP; 794 #else 795 ep->ether_type = htons(ETHERTYPE_REVARP); 796 #endif 797 #ifdef __NetBSD__ 798 ap->ar_hrd = htons(ARPHRD_ETHER); 799 ap->ar_pro = htons(ETHERTYPE_IP); 800 ap->ar_op = htons(ARPOP_REVREPLY); 801 802 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 803 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 804 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 805 806 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 807 /* Target hardware is unchanged. */ 808 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 809 810 len = sizeof(*ep) + sizeof(*ap) + 811 2 * ap->ar_pln + 2 * ap->ar_hln; 812 #else 813 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 814 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 815 ap->arp_op = htons(ARPOP_REVREPLY); 816 817 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 818 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 819 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 820 821 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 822 /* Target hardware is unchanged. */ 823 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 824 825 len = sizeof(*ep) + sizeof(*ap); 826 #endif 827 828 debug("%s asked; %s replied", 829 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 830 if (lflag) 831 syslog(LOG_INFO, "%s asked; %s replied", 832 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 833 n = write(ii->ii_fd, (char *) ep, len); 834 if (n != len) { 835 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 836 } 837 } 838 /* 839 * Get the netmask of an IP address. This routine is used if 840 * SIOCGIFNETMASK doesn't work. 841 */ 842 u_int32_t 843 ipaddrtonetmask(u_int32_t addr) 844 { 845 846 if (IN_CLASSA(addr)) 847 return IN_CLASSA_NET; 848 if (IN_CLASSB(addr)) 849 return IN_CLASSB_NET; 850 if (IN_CLASSC(addr)) 851 return IN_CLASSC_NET; 852 rarperr(FATAL, "unknown IP address class: %08X", addr); 853 /* NOTREACHED */ 854 return(-1); 855 } 856 857 #include <stdarg.h> 858 859 void 860 rarperr(int fatal, const char *fmt,...) 861 { 862 va_list ap; 863 864 va_start(ap, fmt); 865 if (dflag) { 866 if (fatal) 867 (void)fprintf(stderr, "rarpd: error: "); 868 else 869 (void)fprintf(stderr, "rarpd: warning: "); 870 (void)vfprintf(stderr, fmt, ap); 871 va_end(ap); 872 va_start(ap, fmt); 873 (void)fprintf(stderr, "\n"); 874 } 875 vsyslog(LOG_ERR, fmt, ap); 876 va_end(ap); 877 if (fatal) 878 exit(1); 879 /* NOTREACHED */ 880 } 881 882 void 883 debug(const char *fmt,...) 884 { 885 va_list ap; 886 887 va_start(ap, fmt); 888 if (dflag) { 889 (void)fprintf(stderr, "rarpd: "); 890 (void)vfprintf(stderr, fmt, ap); 891 va_end(ap); 892 va_start(ap, fmt); 893 (void)fprintf(stderr, "\n"); 894 } 895 vsyslog(LOG_WARNING, fmt, ap); 896 va_end(ap); 897 } 898