1 /* $NetBSD: rarpd.c,v 1.18 1997/06/21 14:30:04 lukem 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 #ifndef lint 24 char copyright[] = 25 "@(#) Copyright (c) 1990 The Regents of the University of California.\n\ 26 All rights reserved.\n"; 27 #endif /* not lint */ 28 29 #ifndef lint 30 static char rcsid[] = "$NetBSD: rarpd.c,v 1.18 1997/06/21 14:30:04 lukem Exp $"; 31 #endif 32 33 34 /* 35 * rarpd - Reverse ARP Daemon 36 * 37 * Usage: rarpd -a [ -d -f ] 38 * rarpd [ -d -f ] interface 39 */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <syslog.h> 44 #include <string.h> 45 #include <strings.h> 46 #include <sys/types.h> 47 #include <unistd.h> 48 #include <sys/time.h> 49 #include <net/bpf.h> 50 #include <sys/socket.h> 51 #include <sys/ioctl.h> 52 #include <net/if.h> 53 #include <net/if_dl.h> 54 #ifdef __NetBSD__ 55 #include <net/if_ether.h> 56 #endif 57 #include <net/if_types.h> 58 #include <netinet/in.h> 59 #ifdef __NetBSD__ 60 #include <netinet/if_inarp.h> 61 #else 62 #include <netinet/if_ether.h> 63 #endif 64 #include <sys/errno.h> 65 #include <sys/file.h> 66 #include <netdb.h> 67 #include <arpa/inet.h> 68 #include <dirent.h> 69 70 #define FATAL 1 /* fatal error occurred */ 71 #define NONFATAL 0 /* non fatal error occurred */ 72 73 /* 74 * The structure for each interface. 75 */ 76 struct if_info { 77 int ii_fd; /* BPF file descriptor */ 78 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 79 u_long ii_ipaddr; /* IP address of this interface */ 80 u_long ii_netmask; /* subnet or net mask */ 81 struct if_info *ii_next; 82 }; 83 /* 84 * The list of all interfaces that are being listened to. rarp_loop() 85 * "selects" on the descriptors in this list. 86 */ 87 struct if_info *iflist; 88 89 int rarp_open __P((char *)); 90 void init_one __P((char *)); 91 void init_all __P((void)); 92 void rarp_loop __P((void)); 93 void lookup_eaddr __P((char *, u_char *)); 94 void lookup_ipaddr __P((char *, u_long *, u_long *)); 95 void usage __P((void)); 96 void rarp_process __P((struct if_info *, u_char *)); 97 void rarp_reply __P((struct if_info *, struct ether_header *, u_long)); 98 void update_arptab __P((u_char *, u_long)); 99 void err __P((int, const char *,...)); 100 void debug __P((const char *,...)); 101 u_long ipaddrtonetmask __P((u_long)); 102 103 #ifdef REQUIRE_TFTPBOOT 104 int rarp_bootable __P((u_long)); 105 #endif 106 107 int aflag = 0; /* listen on "all" interfaces */ 108 int dflag = 0; /* print debugging messages */ 109 int fflag = 0; /* don't fork */ 110 111 int 112 main(argc, argv) 113 int argc; 114 char **argv; 115 { 116 int op, pid, devnull, f; 117 char *ifname, *hostname, *name; 118 119 extern char *optarg; 120 extern int optind, opterr; 121 122 if (name = strrchr(argv[0], '/')) 123 ++name; 124 else 125 name = argv[0]; 126 if (*name == '-') 127 ++name; 128 129 /* All error reporting is done through syslogs. */ 130 openlog(name, LOG_PID, LOG_DAEMON); 131 132 opterr = 0; 133 while ((op = getopt(argc, argv, "adf")) != EOF) { 134 switch (op) { 135 case 'a': 136 ++aflag; 137 break; 138 139 case 'd': 140 ++dflag; 141 break; 142 143 case 'f': 144 ++fflag; 145 break; 146 147 default: 148 usage(); 149 /* NOTREACHED */ 150 } 151 } 152 ifname = argv[optind++]; 153 hostname = ifname ? argv[optind] : 0; 154 if ((aflag && ifname) || (!aflag && ifname == 0)) 155 usage(); 156 157 if (aflag) 158 init_all(); 159 else 160 init_one(ifname); 161 162 if ((!fflag) && (!dflag)) { 163 pid = fork(); 164 if (pid > 0) 165 /* Parent exits, leaving child in background. */ 166 exit(0); 167 else 168 if (pid == -1) { 169 err(FATAL, "cannot fork"); 170 /* NOTREACHED */ 171 } 172 /* Fade into the background */ 173 f = open("/dev/tty", O_RDWR); 174 if (f >= 0) { 175 if (ioctl(f, TIOCNOTTY, 0) < 0) { 176 err(FATAL, "TIOCNOTTY: %s", strerror(errno)); 177 /* NOTREACHED */ 178 } 179 (void) close(f); 180 } 181 (void) chdir("/"); 182 (void) setpgrp(0, getpid()); 183 devnull = open("/dev/null", O_RDWR); 184 if (devnull >= 0) { 185 (void) dup2(devnull, 0); 186 (void) dup2(devnull, 1); 187 (void) dup2(devnull, 2); 188 if (devnull > 2) 189 (void) close(devnull); 190 } 191 } 192 rarp_loop(); 193 } 194 /* 195 * Add 'ifname' to the interface list. Lookup its IP address and network 196 * mask and Ethernet address, and open a BPF file for it. 197 */ 198 void 199 init_one(ifname) 200 char *ifname; 201 { 202 struct if_info *p; 203 204 p = (struct if_info *)malloc(sizeof(*p)); 205 if (p == 0) { 206 err(FATAL, "malloc: %s", strerror(errno)); 207 /* NOTREACHED */ 208 } 209 p->ii_next = iflist; 210 iflist = p; 211 212 p->ii_fd = rarp_open(ifname); 213 lookup_eaddr(ifname, p->ii_eaddr); 214 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 215 } 216 /* 217 * Initialize all "candidate" interfaces that are in the system 218 * configuration list. A "candidate" is up, not loopback and not 219 * point to point. 220 */ 221 void 222 init_all() 223 { 224 char inbuf[8192]; 225 struct ifconf ifc; 226 struct ifreq ifreq, *ifr; 227 int fd; 228 int i, len; 229 230 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 231 err(FATAL, "socket: %s", strerror(errno)); 232 /* NOTREACHED */ 233 } 234 235 ifc.ifc_len = sizeof(inbuf); 236 ifc.ifc_buf = inbuf; 237 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 238 ifc.ifc_len < sizeof(struct ifreq)) { 239 err(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 240 /* NOTREACHED */ 241 } 242 ifr = ifc.ifc_req; 243 ifreq.ifr_name[0] = '\0'; 244 for (i = 0; i < ifc.ifc_len; 245 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 246 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 247 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name))) 248 continue; 249 ifreq = *ifr; 250 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 251 err(FATAL, "init_all: SIOCGIFFLAGS: %s", 252 strerror(errno)); 253 /* NOTREACHED */ 254 } 255 if ((ifr->ifr_flags & 256 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 257 continue; 258 init_one(ifr->ifr_name); 259 } 260 (void) close(fd); 261 } 262 263 void 264 usage() 265 { 266 (void) fprintf(stderr, "usage: rarpd -a [ -d -f ]\n"); 267 (void) fprintf(stderr, " rarpd [ -d -f ] interface\n"); 268 exit(1); 269 } 270 271 static int 272 bpf_open() 273 { 274 int fd; 275 int n = 0; 276 char device[sizeof "/dev/bpf000"]; 277 278 /* Go through all the minors and find one that isn't in use. */ 279 do { 280 (void) sprintf(device, "/dev/bpf%d", n++); 281 fd = open(device, O_RDWR); 282 } while (fd < 0 && errno == EBUSY); 283 284 if (fd < 0) { 285 err(FATAL, "%s: %s", device, strerror(errno)); 286 /* NOTREACHED */ 287 } 288 return fd; 289 } 290 /* 291 * Open a BPF file and attach it to the interface named 'device'. 292 * Set immediate mode, and set a filter that accepts only RARP requests. 293 */ 294 int 295 rarp_open(device) 296 char *device; 297 { 298 int fd; 299 struct ifreq ifr; 300 u_int dlt; 301 int immediate; 302 303 static struct bpf_insn insns[] = { 304 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 305 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 306 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 307 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 308 BPF_STMT(BPF_RET | BPF_K, 309 sizeof(struct arphdr) + 310 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 311 sizeof(struct ether_header)), 312 BPF_STMT(BPF_RET | BPF_K, 0), 313 }; 314 static struct bpf_program filter = { 315 sizeof insns / sizeof(insns[0]), 316 insns 317 }; 318 319 fd = bpf_open(); 320 321 /* Set immediate mode so packets are processed as they arrive. */ 322 immediate = 1; 323 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 324 err(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 325 /* NOTREACHED */ 326 } 327 (void) strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); 328 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 329 err(FATAL, "BIOCSETIF: %s", strerror(errno)); 330 /* NOTREACHED */ 331 } 332 /* Check that the data link layer is an Ethernet; this code won't work 333 * with anything else. */ 334 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 335 err(FATAL, "BIOCGDLT: %s", strerror(errno)); 336 /* NOTREACHED */ 337 } 338 if (dlt != DLT_EN10MB) { 339 err(FATAL, "%s is not an ethernet", device); 340 /* NOTREACHED */ 341 } 342 /* Set filter program. */ 343 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 344 err(FATAL, "BIOCSETF: %s", strerror(errno)); 345 /* NOTREACHED */ 346 } 347 return fd; 348 } 349 /* 350 * Perform various sanity checks on the RARP request packet. Return 351 * false on failure and log the reason. 352 */ 353 static int 354 rarp_check(p, len) 355 u_char *p; 356 int len; 357 { 358 struct ether_header *ep = (struct ether_header *) p; 359 #ifdef __NetBSD__ 360 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 361 #else 362 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 363 #endif 364 365 if (dflag) 366 fprintf(stderr, "got a packet\n"); 367 368 if (len < sizeof(*ep) + sizeof(*ap)) { 369 err(NONFATAL, "truncated request"); 370 return 0; 371 } 372 #ifdef __NetBSD__ 373 /* now that we know the fixed part of the ARP hdr is there: */ 374 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 375 err(NONFATAL, "truncated request"); 376 return 0; 377 } 378 #endif 379 /* XXX This test might be better off broken out... */ 380 #ifdef __FreeBSD__ 381 /* BPF (incorrectly) returns this in host order. */ 382 if (ep->ether_type != ETHERTYPE_REVARP || 383 #else 384 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 385 #endif 386 #ifdef __NetBSD__ 387 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 388 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 389 ntohs (ap->ar_pro) != ETHERTYPE_IP || 390 ap->ar_hln != 6 || ap->ar_pln != 4) { 391 #else 392 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 393 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 394 ntohs (ap->arp_pro) != ETHERTYPE_IP || 395 ap->arp_hln != 6 || ap->arp_pln != 4) { 396 #endif 397 err(NONFATAL, "request fails sanity check"); 398 return 0; 399 } 400 #ifdef __NetBSD__ 401 if (bcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 402 #else 403 if (bcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 404 #endif 405 err(NONFATAL, "ether/arp sender address mismatch"); 406 return 0; 407 } 408 #ifdef __NetBSD__ 409 if (bcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 410 #else 411 if (bcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 412 #endif 413 err(NONFATAL, "ether/arp target address mismatch"); 414 return 0; 415 } 416 return 1; 417 } 418 419 /* 420 * Loop indefinitely listening for RARP requests on the 421 * interfaces in 'iflist'. 422 */ 423 void 424 rarp_loop() 425 { 426 u_char *buf, *bp, *ep; 427 int cc, fd; 428 fd_set fds, listeners; 429 int bufsize, maxfd = 0; 430 struct if_info *ii; 431 432 if (iflist == 0) { 433 err(FATAL, "no interfaces"); 434 /* NOTREACHED */ 435 } 436 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 437 err(FATAL, "BIOCGBLEN: %s", strerror(errno)); 438 /* NOTREACHED */ 439 } 440 buf = (u_char *) malloc((unsigned) bufsize); 441 if (buf == 0) { 442 err(FATAL, "malloc: %s", strerror(errno)); 443 /* NOTREACHED */ 444 } 445 /* 446 * Find the highest numbered file descriptor for select(). 447 * Initialize the set of descriptors to listen to. 448 */ 449 FD_ZERO(&fds); 450 for (ii = iflist; ii; ii = ii->ii_next) { 451 FD_SET(ii->ii_fd, &fds); 452 if (ii->ii_fd > maxfd) 453 maxfd = ii->ii_fd; 454 } 455 while (1) { 456 listeners = fds; 457 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 458 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 459 err(FATAL, "select: %s", strerror(errno)); 460 /* NOTREACHED */ 461 } 462 for (ii = iflist; ii; ii = ii->ii_next) { 463 fd = ii->ii_fd; 464 if (!FD_ISSET(fd, &listeners)) 465 continue; 466 again: 467 cc = read(fd, (char *) buf, bufsize); 468 /* Don't choke when we get ptraced */ 469 if (cc < 0 && errno == EINTR) 470 goto again; 471 /* Due to a SunOS bug, after 2^31 bytes, the file 472 * offset overflows and read fails with EINVAL. The 473 * lseek() to 0 will fix things. */ 474 if (cc < 0) { 475 if (errno == EINVAL && 476 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 477 (void) lseek(fd, 0, 0); 478 goto again; 479 } 480 err(FATAL, "read: %s", strerror(errno)); 481 /* NOTREACHED */ 482 } 483 /* Loop through the packet(s) */ 484 #define bhp ((struct bpf_hdr *)bp) 485 bp = buf; 486 ep = bp + cc; 487 while (bp < ep) { 488 register int caplen, hdrlen; 489 490 caplen = bhp->bh_caplen; 491 hdrlen = bhp->bh_hdrlen; 492 if (rarp_check(bp + hdrlen, caplen)) 493 rarp_process(ii, bp + hdrlen); 494 bp += BPF_WORDALIGN(hdrlen + caplen); 495 } 496 } 497 } 498 } 499 500 #ifdef REQUIRE_TFTPBOOT 501 502 #ifndef TFTP_DIR 503 #define TFTP_DIR "/tftpboot" 504 #endif 505 506 /* 507 * True if this server can boot the host whose IP address is 'addr'. 508 * This check is made by looking in the tftp directory for the 509 * configuration file. 510 */ 511 int 512 rarp_bootable(addr) 513 u_long addr; 514 { 515 register struct dirent *dent; 516 register DIR *d; 517 char ipname[9]; 518 static DIR *dd = 0; 519 520 (void) sprintf(ipname, "%08X", addr); 521 /* If directory is already open, rewind it. Otherwise, open it. */ 522 if (d = dd) 523 rewinddir(d); 524 else { 525 if (chdir(TFTP_DIR) == -1) { 526 err(FATAL, "chdir: %s", strerror(errno)); 527 /* NOTREACHED */ 528 } 529 d = opendir("."); 530 if (d == 0) { 531 err(FATAL, "opendir: %s", strerror(errno)); 532 /* NOTREACHED */ 533 } 534 dd = d; 535 } 536 while (dent = readdir(d)) 537 if (strncmp(dent->d_name, ipname, 8) == 0) 538 return 1; 539 return 0; 540 } 541 #endif /* REQUIRE_TFTPBOOT */ 542 543 /* 544 * Given a list of IP addresses, 'alist', return the first address that 545 * is on network 'net'; 'netmask' is a mask indicating the network portion 546 * of the address. 547 */ 548 u_int32_t 549 choose_ipaddr(alist, net, netmask) 550 u_int32_t **alist; 551 u_int32_t net; 552 u_int32_t netmask; 553 { 554 for (; *alist; ++alist) { 555 if ((**alist & netmask) == net) 556 return **alist; 557 } 558 return 0; 559 } 560 /* 561 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 562 * already been checked for validity. The reply is overlaid on the request. 563 */ 564 void 565 rarp_process(ii, pkt) 566 struct if_info *ii; 567 u_char *pkt; 568 { 569 struct ether_header *ep; 570 struct hostent *hp; 571 u_long target_ipaddr; 572 char ename[MAXHOSTNAMELEN + 1]; 573 struct in_addr in; 574 575 ep = (struct ether_header *) pkt; 576 577 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 578 debug("no IP address for %s", 579 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 580 return; 581 } 582 ename[sizeof(ename)-1] = '\0'; 583 584 if ((hp = gethostbyname(ename)) == 0) { 585 debug("gethostbyname(%s) failed: %s", ename, 586 hstrerror(h_errno)); 587 return; 588 } 589 590 /* Choose correct address from list. */ 591 if (hp->h_addrtype != AF_INET) { 592 err(FATAL, "cannot handle non IP addresses"); 593 /* NOTREACHED */ 594 } 595 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 596 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 597 598 if (target_ipaddr == 0) { 599 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 600 err(NONFATAL, "cannot find %s on net %s\n", 601 ename, inet_ntoa(in)); 602 return; 603 } 604 #ifdef REQUIRE_TFTPBOOT 605 if (rarp_bootable(htonl(target_ipaddr))) 606 #endif 607 rarp_reply(ii, ep, target_ipaddr); 608 #ifdef REQUIRE_TFTPBOOT 609 else 610 debug("%08X not bootable", htonl(target_ipaddr)); 611 #endif 612 } 613 /* 614 * Lookup the ethernet address of the interface attached to the BPF 615 * file descriptor 'fd'; return it in 'eaddr'. 616 */ 617 void 618 lookup_eaddr(ifname, eaddr) 619 char *ifname; 620 u_char *eaddr; 621 { 622 char inbuf[8192]; 623 struct ifconf ifc; 624 struct ifreq *ifr; 625 struct sockaddr_dl *sdl; 626 int fd; 627 int i, len; 628 629 /* We cannot use SIOCGIFADDR on the BPF descriptor. 630 We must instead get all the interfaces with SIOCGIFCONF 631 and find the right one. */ 632 633 /* Use datagram socket to get Ethernet address. */ 634 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 635 err(FATAL, "socket: %s", strerror(errno)); 636 /* NOTREACHED */ 637 } 638 639 ifc.ifc_len = sizeof(inbuf); 640 ifc.ifc_buf = inbuf; 641 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 642 ifc.ifc_len < sizeof(struct ifreq)) { 643 err(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 644 /* NOTREACHED */ 645 } 646 ifr = ifc.ifc_req; 647 for (i = 0; i < ifc.ifc_len; 648 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 649 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 650 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 651 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 652 sdl->sdl_alen != 6) 653 continue; 654 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 655 bcopy((caddr_t)LLADDR(sdl), (caddr_t)eaddr, 6); 656 debug("%s: %x:%x:%x:%x:%x:%x", 657 ifr->ifr_name, eaddr[0], eaddr[1], 658 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 659 return; 660 } 661 } 662 663 err(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 664 } 665 /* 666 * Lookup the IP address and network mask of the interface named 'ifname'. 667 */ 668 void 669 lookup_ipaddr(ifname, addrp, netmaskp) 670 char *ifname; 671 u_long *addrp; 672 u_long *netmaskp; 673 { 674 int fd; 675 struct ifreq ifr; 676 677 /* Use datagram socket to get IP address. */ 678 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 679 err(FATAL, "socket: %s", strerror(errno)); 680 /* NOTREACHED */ 681 } 682 (void) strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 683 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 684 err(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 685 /* NOTREACHED */ 686 } 687 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 688 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 689 perror("SIOCGIFNETMASK"); 690 exit(1); 691 } 692 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 693 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 694 * address class. */ 695 if (*netmaskp == 0) 696 *netmaskp = ipaddrtonetmask(*addrp); 697 698 (void) close(fd); 699 } 700 /* 701 * Poke the kernel arp tables with the ethernet/ip address combinataion 702 * given. When processing a reply, we must do this so that the booting 703 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 704 * address of the guy being booted (he cannot answer the ARP). 705 */ 706 void 707 update_arptab(ep, ipaddr) 708 u_char *ep; 709 u_long ipaddr; 710 { 711 int s; 712 struct arpreq request; 713 struct sockaddr_in *sin; 714 715 request.arp_flags = 0; 716 sin = (struct sockaddr_in *) & request.arp_pa; 717 sin->sin_family = AF_INET; 718 sin->sin_addr.s_addr = ipaddr; 719 request.arp_ha.sa_family = AF_UNSPEC; 720 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 721 because AF_UNSPEC is zero and the kernel assumes that a zero 722 sa_family means that the real sa_family value is in sa_len. */ 723 request.arp_ha.sa_len = 16; /* XXX */ 724 bcopy((char *) ep, (char *) request.arp_ha.sa_data, 6); 725 726 #if 0 727 s = socket(AF_INET, SOCK_DGRAM, 0); 728 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 729 err(NONFATAL, "SIOCSARP: %s", strerror(errno)); 730 } 731 (void) close(s); 732 #endif 733 } 734 /* 735 * Build a reverse ARP packet and sent it out on the interface. 736 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 737 * on top of the request, then written to the network. 738 * 739 * RFC 903 defines the ether_arp fields as follows. The following comments 740 * are taken (more or less) straight from this document. 741 * 742 * ARPOP_REVREQUEST 743 * 744 * arp_sha is the hardware address of the sender of the packet. 745 * arp_spa is undefined. 746 * arp_tha is the 'target' hardware address. 747 * In the case where the sender wishes to determine his own 748 * protocol address, this, like arp_sha, will be the hardware 749 * address of the sender. 750 * arp_tpa is undefined. 751 * 752 * ARPOP_REVREPLY 753 * 754 * arp_sha is the hardware address of the responder (the sender of the 755 * reply packet). 756 * arp_spa is the protocol address of the responder (see the note below). 757 * arp_tha is the hardware address of the target, and should be the same as 758 * that which was given in the request. 759 * arp_tpa is the protocol address of the target, that is, the desired address. 760 * 761 * Note that the requirement that arp_spa be filled in with the responder's 762 * protocol is purely for convenience. For instance, if a system were to use 763 * both ARP and RARP, then the inclusion of the valid protocol-hardware 764 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 765 * ARP request. 766 */ 767 void 768 rarp_reply(ii, ep, ipaddr) 769 struct if_info *ii; 770 struct ether_header *ep; 771 u_long ipaddr; 772 { 773 int n; 774 #ifdef __NetBSD__ 775 struct arphdr *ap = (struct arphdr *) (ep + 1); 776 #else 777 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 778 #endif 779 780 int len; 781 782 #ifdef __NetBSD__ 783 update_arptab(ar_sha(ap), ipaddr); 784 #else 785 update_arptab((u_char *) & ap->arp_sha, ipaddr); 786 #endif 787 788 /* Build the rarp reply by modifying the rarp request in place. */ 789 #ifdef __FreeBSD__ 790 /* BPF (incorrectly) wants this in host order. */ 791 ep->ether_type = ETHERTYPE_REVARP; 792 #else 793 ep->ether_type = htons(ETHERTYPE_REVARP); 794 #endif 795 #ifdef __NetBSD__ 796 ap->ar_hrd = htons(ARPHRD_ETHER); 797 ap->ar_pro = htons(ETHERTYPE_IP); 798 ap->ar_op = htons(ARPOP_REVREPLY); 799 800 bcopy(ar_sha(ap), (char *) &ep->ether_dhost, 6); 801 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 802 bcopy((char *) ii->ii_eaddr, ar_sha(ap), 6); 803 804 bcopy((char *) &ipaddr, ar_tpa(ap), 4); 805 /* Target hardware is unchanged. */ 806 bcopy((char *) &ii->ii_ipaddr, ar_spa(ap), 4); 807 808 len = sizeof(*ep) + sizeof(*ap) + 809 2 * ap->ar_pln + 2 * ap->ar_hln; 810 #else 811 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 812 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 813 ap->arp_op = htons(ARPOP_REVREPLY); 814 815 bcopy((char *) &ap->arp_sha, (char *) &ep->ether_dhost, 6); 816 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 817 bcopy((char *) ii->ii_eaddr, (char *) &ap->arp_sha, 6); 818 819 bcopy((char *) &ipaddr, (char *) ap->arp_tpa, 4); 820 /* Target hardware is unchanged. */ 821 bcopy((char *) &ii->ii_ipaddr, (char *) ap->arp_spa, 4); 822 823 len = sizeof(*ep) + sizeof(*ap); 824 #endif 825 826 n = write(ii->ii_fd, (char *) ep, len); 827 if (n != len) { 828 err(NONFATAL, "write: only %d of %d bytes written", n, len); 829 } 830 } 831 /* 832 * Get the netmask of an IP address. This routine is used if 833 * SIOCGIFNETMASK doesn't work. 834 */ 835 u_long 836 ipaddrtonetmask(addr) 837 u_long addr; 838 { 839 if (IN_CLASSA(addr)) 840 return IN_CLASSA_NET; 841 if (IN_CLASSB(addr)) 842 return IN_CLASSB_NET; 843 if (IN_CLASSC(addr)) 844 return IN_CLASSC_NET; 845 err(FATAL, "unknown IP address class: %08X", addr); 846 /* NOTREACHED */ 847 } 848 849 #if __STDC__ 850 #include <stdarg.h> 851 #else 852 #include <varargs.h> 853 #endif 854 855 void 856 #if __STDC__ 857 err(int fatal, const char *fmt,...) 858 #else 859 err(fmt, va_alist) 860 int fatal; 861 char *fmt; 862 va_dcl 863 #endif 864 { 865 va_list ap; 866 #if __STDC__ 867 va_start(ap, fmt); 868 #else 869 va_start(ap); 870 #endif 871 if (dflag) { 872 if (fatal) 873 (void) fprintf(stderr, "rarpd: error: "); 874 else 875 (void) fprintf(stderr, "rarpd: warning: "); 876 (void) vfprintf(stderr, fmt, ap); 877 (void) fprintf(stderr, "\n"); 878 } 879 vsyslog(LOG_ERR, fmt, ap); 880 va_end(ap); 881 if (fatal) 882 exit(1); 883 /* NOTREACHED */ 884 } 885 886 void 887 #if __STDC__ 888 debug(const char *fmt,...) 889 #else 890 debug(fmt, va_alist) 891 char *fmt; 892 va_dcl 893 #endif 894 { 895 va_list ap; 896 897 #if __STDC__ 898 va_start(ap, fmt); 899 #else 900 va_start(ap); 901 #endif 902 if (dflag) { 903 (void) fprintf(stderr, "rarpd: "); 904 (void) vfprintf(stderr, fmt, ap); 905 (void) fprintf(stderr, "\n"); 906 } 907 vsyslog(LOG_WARNING, fmt, ap); 908 va_end(ap); 909 } 910