1 /* 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 */ 21 #ifndef lint 22 char copyright[] = 23 "@(#) Copyright (c) 1990 The Regents of the University of California.\n\ 24 All rights reserved.\n"; 25 #endif /* not lint */ 26 27 #ifndef lint 28 static char rcsid[] = 29 "@(#) $Id: rarpd.c,v 1.7 1994/05/25 20:01:15 mycroft Exp $"; 30 #endif 31 32 33 /* 34 * rarpd - Reverse ARP Daemon 35 * 36 * Usage: rarpd -a [ -d -f ] 37 * rarpd [ -d -f ] interface 38 */ 39 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <syslog.h> 43 #include <string.h> 44 #include <strings.h> 45 #include <sys/types.h> 46 #include <unistd.h> 47 #include <sys/time.h> 48 #include <net/bpf.h> 49 #include <sys/socket.h> 50 #include <sys/ioctl.h> 51 #include <net/if.h> 52 #include <net/if_dl.h> 53 #include <net/if_types.h> 54 #include <netinet/in.h> 55 #include <netinet/if_ether.h> 56 #include <sys/errno.h> 57 #include <sys/file.h> 58 #include <netdb.h> 59 #include <arpa/inet.h> 60 #include <dirent.h> 61 62 #define FATAL 1 /* fatal error occurred */ 63 #define NONFATAL 0 /* non fatal error occurred */ 64 65 /* 66 * The structure for each interface. 67 */ 68 struct if_info { 69 int ii_fd; /* BPF file descriptor */ 70 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 71 u_long ii_ipaddr; /* IP address of this interface */ 72 u_long ii_netmask; /* subnet or net mask */ 73 struct if_info *ii_next; 74 }; 75 /* 76 * The list of all interfaces that are being listened to. rarp_loop() 77 * "selects" on the descriptors in this list. 78 */ 79 struct if_info *iflist; 80 81 int rarp_open __P((char *)); 82 int rarp_bootable __P((u_long)); 83 void init_one __P((char *)); 84 void init_all __P((void)); 85 void rarp_loop __P((void)); 86 void lookup_eaddr __P((char *, u_char *)); 87 void lookup_ipaddr __P((char *, u_long *, u_long *)); 88 void usage __P((void)); 89 void rarp_process __P((struct if_info *, u_char *)); 90 void rarp_reply __P((struct if_info *, struct ether_header *, u_long)); 91 void update_arptab __P((u_char *, u_long)); 92 void err __P((int, const char *,...)); 93 void debug __P((const char *,...)); 94 u_long ipaddrtonetmask __P((u_long)); 95 96 int aflag = 0; /* listen on "all" interfaces */ 97 int dflag = 0; /* print debugging messages */ 98 int fflag = 0; /* don't fork */ 99 100 void 101 main(argc, argv) 102 int argc; 103 char **argv; 104 { 105 int op, pid, devnull, f; 106 char *ifname, *hostname, *name; 107 108 extern char *optarg; 109 extern int optind, opterr; 110 111 if (name = strrchr(argv[0], '/')) 112 ++name; 113 else 114 name = argv[0]; 115 if (*name == '-') 116 ++name; 117 118 /* All error reporting is done through syslogs. */ 119 openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON); 120 121 opterr = 0; 122 while ((op = getopt(argc, argv, "adf")) != EOF) { 123 switch (op) { 124 case 'a': 125 ++aflag; 126 break; 127 128 case 'd': 129 ++dflag; 130 break; 131 132 case 'f': 133 ++fflag; 134 break; 135 136 default: 137 usage(); 138 /* NOTREACHED */ 139 } 140 } 141 ifname = argv[optind++]; 142 hostname = ifname ? argv[optind] : 0; 143 if ((aflag && ifname) || (!aflag && ifname == 0)) 144 usage(); 145 146 if (aflag) 147 init_all(); 148 else 149 init_one(ifname); 150 151 if ((!fflag) && (!dflag)) { 152 pid = fork(); 153 if (pid > 0) 154 /* Parent exits, leaving child in background. */ 155 exit(0); 156 else 157 if (pid == -1) { 158 err(FATAL, "cannot fork"); 159 /* NOTREACHED */ 160 } 161 /* Fade into the background */ 162 f = open("/dev/tty", O_RDWR); 163 if (f >= 0) { 164 if (ioctl(f, TIOCNOTTY, 0) < 0) { 165 err(FATAL, "TIOCNOTTY: %s", strerror(errno)); 166 /* NOTREACHED */ 167 } 168 (void) close(f); 169 } 170 (void) chdir("/"); 171 (void) setpgrp(0, getpid()); 172 devnull = open("/dev/null", O_RDWR); 173 if (devnull >= 0) { 174 (void) dup2(devnull, 0); 175 (void) dup2(devnull, 1); 176 (void) dup2(devnull, 2); 177 if (devnull > 2) 178 (void) close(devnull); 179 } 180 } 181 rarp_loop(); 182 } 183 /* 184 * Add 'ifname' to the interface list. Lookup its IP address and network 185 * mask and Ethernet address, and open a BPF file for it. 186 */ 187 void 188 init_one(ifname) 189 char *ifname; 190 { 191 struct if_info *p; 192 193 p = (struct if_info *)malloc(sizeof(*p)); 194 if (p == 0) { 195 err(FATAL, "malloc: %s", strerror(errno)); 196 /* NOTREACHED */ 197 } 198 p->ii_next = iflist; 199 iflist = p; 200 201 p->ii_fd = rarp_open(ifname); 202 lookup_eaddr(ifname, p->ii_eaddr); 203 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 204 } 205 /* 206 * Initialize all "candidate" interfaces that are in the system 207 * configuration list. A "candidate" is up, not loopback and not 208 * point to point. 209 */ 210 void 211 init_all() 212 { 213 char inbuf[8192]; 214 struct ifconf ifc; 215 struct ifreq *ifr; 216 int fd; 217 int i, len; 218 219 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 220 err(FATAL, "socket: %s", strerror(errno)); 221 /* NOTREACHED */ 222 } 223 224 ifc.ifc_len = sizeof(inbuf); 225 ifc.ifc_buf = inbuf; 226 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 227 ifc.ifc_len < sizeof(struct ifreq)) { 228 err(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 229 /* NOTREACHED */ 230 } 231 ifr = ifc.ifc_req; 232 for (i = 0; i < ifc.ifc_len; 233 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 234 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 235 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 236 err(FATAL, "init_all: SIOCGIFFLAGS: %s", 237 strerror(errno)); 238 /* NOTREACHED */ 239 } 240 if ((ifr->ifr_flags & 241 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 242 continue; 243 init_one(ifr->ifr_name); 244 } 245 (void) close(fd); 246 } 247 248 void 249 usage() 250 { 251 (void) fprintf(stderr, "usage: rarpd -a [ -d -f ]\n"); 252 (void) fprintf(stderr, " rarpd [ -d -f ] interface\n"); 253 exit(1); 254 } 255 256 static int 257 bpf_open() 258 { 259 int fd; 260 int n = 0; 261 char device[sizeof "/dev/bpf000"]; 262 263 /* Go through all the minors and find one that isn't in use. */ 264 do { 265 (void) sprintf(device, "/dev/bpf%d", n++); 266 fd = open(device, O_RDWR); 267 } while (fd < 0 && errno == EBUSY); 268 269 if (fd < 0) { 270 err(FATAL, "%s: %s", device, strerror(errno)); 271 /* NOTREACHED */ 272 } 273 return fd; 274 } 275 /* 276 * Open a BPF file and attach it to the interface named 'device'. 277 * Set immediate mode, and set a filter that accepts only RARP requests. 278 */ 279 int 280 rarp_open(device) 281 char *device; 282 { 283 int fd; 284 struct ifreq ifr; 285 u_int dlt; 286 int immediate; 287 288 static struct bpf_insn insns[] = { 289 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 290 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 291 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 292 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 293 BPF_STMT(BPF_RET | BPF_K, sizeof(struct ether_arp) + 294 sizeof(struct ether_header)), 295 BPF_STMT(BPF_RET | BPF_K, 0), 296 }; 297 static struct bpf_program filter = { 298 sizeof insns / sizeof(insns[0]), 299 insns 300 }; 301 302 fd = bpf_open(); 303 304 /* Set immediate mode so packets are processed as they arrive. */ 305 immediate = 1; 306 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 307 err(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 308 /* NOTREACHED */ 309 } 310 (void) strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); 311 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 312 err(FATAL, "BIOCSETIF: %s", strerror(errno)); 313 /* NOTREACHED */ 314 } 315 /* Check that the data link layer is an Ethernet; this code won't work 316 * with anything else. */ 317 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 318 err(FATAL, "BIOCGDLT: %s", strerror(errno)); 319 /* NOTREACHED */ 320 } 321 if (dlt != DLT_EN10MB) { 322 err(FATAL, "%s is not an ethernet", device); 323 /* NOTREACHED */ 324 } 325 /* Set filter program. */ 326 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 327 err(FATAL, "BIOCSETF: %s", strerror(errno)); 328 /* NOTREACHED */ 329 } 330 return fd; 331 } 332 /* 333 * Perform various sanity checks on the RARP request packet. Return 334 * false on failure and log the reason. 335 */ 336 static int 337 rarp_check(p, len) 338 u_char *p; 339 int len; 340 { 341 struct ether_header *ep = (struct ether_header *) p; 342 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 343 344 (void) debug("got a packet"); 345 346 if (len < sizeof(*ep) + sizeof(*ap)) { 347 err(NONFATAL, "truncated request"); 348 return 0; 349 } 350 /* XXX This test might be better off broken out... */ 351 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 352 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 353 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 354 ntohs (ap->arp_pro) != ETHERTYPE_IP || 355 ap->arp_hln != 6 || ap->arp_pln != 4) { 356 err(NONFATAL, "request fails sanity check"); 357 return 0; 358 } 359 if (bcmp((char *) &ep->ether_shost, (char *) &ap->arp_sha, 6) != 0) { 360 err(NONFATAL, "ether/arp sender address mismatch"); 361 return 0; 362 } 363 if (bcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 364 err(NONFATAL, "ether/arp target address mismatch"); 365 return 0; 366 } 367 return 1; 368 } 369 370 /* 371 * Loop indefinitely listening for RARP requests on the 372 * interfaces in 'iflist'. 373 */ 374 void 375 rarp_loop() 376 { 377 u_char *buf, *bp, *ep; 378 int cc, fd; 379 fd_set fds, listeners; 380 int bufsize, maxfd = 0; 381 struct if_info *ii; 382 383 if (iflist == 0) { 384 err(FATAL, "no interfaces"); 385 /* NOTREACHED */ 386 } 387 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 388 err(FATAL, "BIOCGBLEN: %s", strerror(errno)); 389 /* NOTREACHED */ 390 } 391 buf = (u_char *) malloc((unsigned) bufsize); 392 if (buf == 0) { 393 err(FATAL, "malloc: %s", strerror(errno)); 394 /* NOTREACHED */ 395 } 396 /* 397 * Find the highest numbered file descriptor for select(). 398 * Initialize the set of descriptors to listen to. 399 */ 400 FD_ZERO(&fds); 401 for (ii = iflist; ii; ii = ii->ii_next) { 402 FD_SET(ii->ii_fd, &fds); 403 if (ii->ii_fd > maxfd) 404 maxfd = ii->ii_fd; 405 } 406 while (1) { 407 listeners = fds; 408 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 409 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 410 err(FATAL, "select: %s", strerror(errno)); 411 /* NOTREACHED */ 412 } 413 for (ii = iflist; ii; ii = ii->ii_next) { 414 fd = ii->ii_fd; 415 if (!FD_ISSET(fd, &listeners)) 416 continue; 417 again: 418 cc = read(fd, (char *) buf, bufsize); 419 /* Don't choke when we get ptraced */ 420 if (cc < 0 && errno == EINTR) 421 goto again; 422 /* Due to a SunOS bug, after 2^31 bytes, the file 423 * offset overflows and read fails with EINVAL. The 424 * lseek() to 0 will fix things. */ 425 if (cc < 0) { 426 if (errno == EINVAL && 427 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 428 (void) lseek(fd, 0, 0); 429 goto again; 430 } 431 err(FATAL, "read: %s", strerror(errno)); 432 /* NOTREACHED */ 433 } 434 /* Loop through the packet(s) */ 435 #define bhp ((struct bpf_hdr *)bp) 436 bp = buf; 437 ep = bp + cc; 438 while (bp < ep) { 439 register int caplen, hdrlen; 440 441 caplen = bhp->bh_caplen; 442 hdrlen = bhp->bh_hdrlen; 443 if (rarp_check(bp + hdrlen, caplen)) 444 rarp_process(ii, bp + hdrlen); 445 bp += BPF_WORDALIGN(hdrlen + caplen); 446 } 447 } 448 } 449 } 450 #ifndef TFTP_DIR 451 #define TFTP_DIR "/tftpboot" 452 #endif 453 454 /* 455 * True if this server can boot the host whose IP address is 'addr'. 456 * This check is made by looking in the tftp directory for the 457 * configuration file. 458 */ 459 int 460 rarp_bootable(addr) 461 u_long addr; 462 { 463 register struct dirent *dent; 464 register DIR *d; 465 char ipname[9]; 466 static DIR *dd = 0; 467 468 (void) sprintf(ipname, "%08X", addr); 469 /* If directory is already open, rewind it. Otherwise, open it. */ 470 if (d = dd) 471 rewinddir(d); 472 else { 473 if (chdir(TFTP_DIR) == -1) { 474 err(FATAL, "chdir: %s", strerror(errno)); 475 /* NOTREACHED */ 476 } 477 d = opendir("."); 478 if (d == 0) { 479 err(FATAL, "opendir: %s", strerror(errno)); 480 /* NOTREACHED */ 481 } 482 dd = d; 483 } 484 while (dent = readdir(d)) 485 if (strncmp(dent->d_name, ipname, 8) == 0) 486 return 1; 487 return 0; 488 } 489 /* 490 * Given a list of IP addresses, 'alist', return the first address that 491 * is on network 'net'; 'netmask' is a mask indicating the network portion 492 * of the address. 493 */ 494 u_long 495 choose_ipaddr(alist, net, netmask) 496 u_long **alist; 497 u_long net; 498 u_long netmask; 499 { 500 for (; *alist; ++alist) { 501 if ((**alist & netmask) == net) 502 return **alist; 503 } 504 return 0; 505 } 506 /* 507 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 508 * already been checked for validity. The reply is overlaid on the request. 509 */ 510 void 511 rarp_process(ii, pkt) 512 struct if_info *ii; 513 u_char *pkt; 514 { 515 struct ether_header *ep; 516 struct hostent *hp; 517 u_long target_ipaddr; 518 char ename[256]; 519 struct in_addr in; 520 521 ep = (struct ether_header *) pkt; 522 523 if (ether_ntohost(ename, &ep->ether_shost) != 0 || 524 (hp = gethostbyname(ename)) == 0) 525 return; 526 527 /* Choose correct address from list. */ 528 if (hp->h_addrtype != AF_INET) { 529 err(FATAL, "cannot handle non IP addresses"); 530 /* NOTREACHED */ 531 } 532 target_ipaddr = choose_ipaddr((u_long **) hp->h_addr_list, 533 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 534 535 if (target_ipaddr == 0) { 536 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 537 err(NONFATAL, "cannot find %s on net %s\n", 538 ename, inet_ntoa(in)); 539 return; 540 } 541 if (rarp_bootable(htonl(target_ipaddr))) 542 rarp_reply(ii, ep, target_ipaddr); 543 } 544 /* 545 * Lookup the ethernet address of the interface attached to the BPF 546 * file descriptor 'fd'; return it in 'eaddr'. 547 */ 548 void 549 lookup_eaddr(ifname, eaddr) 550 char *ifname; 551 u_char *eaddr; 552 { 553 char inbuf[8192]; 554 struct ifconf ifc; 555 struct ifreq *ifr; 556 struct sockaddr_dl *sdl; 557 int fd; 558 int i, len; 559 560 /* We cannot use SIOCGIFADDR on the BPF descriptor. 561 We must instead get all the interfaces with SIOCGIFCONF 562 and find the right one. */ 563 564 /* Use datagram socket to get Ethernet address. */ 565 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 566 err(FATAL, "socket: %s", strerror(errno)); 567 /* NOTREACHED */ 568 } 569 570 ifc.ifc_len = sizeof(inbuf); 571 ifc.ifc_buf = inbuf; 572 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 573 ifc.ifc_len < sizeof(struct ifreq)) { 574 err(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 575 /* NOTREACHED */ 576 } 577 ifr = ifc.ifc_req; 578 for (i = 0; i < ifc.ifc_len; 579 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 580 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 581 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 582 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 583 sdl->sdl_alen != 6) 584 continue; 585 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 586 bcopy((caddr_t)LLADDR(sdl), (caddr_t)eaddr, 6); 587 if (dflag) 588 fprintf(stderr, "%s: %x:%x:%x:%x:%x:%x\n", 589 ifr->ifr_name, eaddr[0], eaddr[1], 590 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 591 return; 592 } 593 } 594 595 err(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 596 } 597 /* 598 * Lookup the IP address and network mask of the interface named 'ifname'. 599 */ 600 void 601 lookup_ipaddr(ifname, addrp, netmaskp) 602 char *ifname; 603 u_long *addrp; 604 u_long *netmaskp; 605 { 606 int fd; 607 struct ifreq ifr; 608 609 /* Use datagram socket to get IP address. */ 610 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 611 err(FATAL, "socket: %s", strerror(errno)); 612 /* NOTREACHED */ 613 } 614 (void) strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 615 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 616 err(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 617 /* NOTREACHED */ 618 } 619 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 620 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 621 perror("SIOCGIFNETMASK"); 622 exit(1); 623 } 624 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 625 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 626 * address class. */ 627 if (*netmaskp == 0) 628 *netmaskp = ipaddrtonetmask(*addrp); 629 630 (void) close(fd); 631 } 632 /* 633 * Poke the kernel arp tables with the ethernet/ip address combinataion 634 * given. When processing a reply, we must do this so that the booting 635 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 636 * address of the guy being booted (he cannot answer the ARP). 637 */ 638 void 639 update_arptab(ep, ipaddr) 640 u_char *ep; 641 u_long ipaddr; 642 { 643 int s; 644 struct arpreq request; 645 struct sockaddr_in *sin; 646 647 request.arp_flags = 0; 648 sin = (struct sockaddr_in *) & request.arp_pa; 649 sin->sin_family = AF_INET; 650 sin->sin_addr.s_addr = ipaddr; 651 request.arp_ha.sa_family = AF_UNSPEC; 652 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 653 because AF_UNSPEC is zero and the kernel assumes that a zero 654 sa_family means that the real sa_family value is in sa_len. */ 655 request.arp_ha.sa_len = 16; /* XXX */ 656 bcopy((char *) ep, (char *) request.arp_ha.sa_data, 6); 657 658 #if 0 659 s = socket(AF_INET, SOCK_DGRAM, 0); 660 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 661 err(NONFATAL, "SIOCSARP: %s", strerror(errno)); 662 } 663 (void) close(s); 664 #endif 665 } 666 /* 667 * Build a reverse ARP packet and sent it out on the interface. 668 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 669 * on top of the request, then written to the network. 670 * 671 * RFC 903 defines the ether_arp fields as follows. The following comments 672 * are taken (more or less) straight from this document. 673 * 674 * ARPOP_REVREQUEST 675 * 676 * arp_sha is the hardware address of the sender of the packet. 677 * arp_spa is undefined. 678 * arp_tha is the 'target' hardware address. 679 * In the case where the sender wishes to determine his own 680 * protocol address, this, like arp_sha, will be the hardware 681 * address of the sender. 682 * arp_tpa is undefined. 683 * 684 * ARPOP_REVREPLY 685 * 686 * arp_sha is the hardware address of the responder (the sender of the 687 * reply packet). 688 * arp_spa is the protocol address of the responder (see the note below). 689 * arp_tha is the hardware address of the target, and should be the same as 690 * that which was given in the request. 691 * arp_tpa is the protocol address of the target, that is, the desired address. 692 * 693 * Note that the requirement that arp_spa be filled in with the responder's 694 * protocol is purely for convenience. For instance, if a system were to use 695 * both ARP and RARP, then the inclusion of the valid protocol-hardware 696 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 697 * ARP request. 698 */ 699 void 700 rarp_reply(ii, ep, ipaddr) 701 struct if_info *ii; 702 struct ether_header *ep; 703 u_long ipaddr; 704 { 705 int n; 706 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 707 int len; 708 709 update_arptab((u_char *) & ap->arp_sha, ipaddr); 710 711 /* Build the rarp reply by modifying the rarp request in place. */ 712 ep->ether_type = htons(ETHERTYPE_REVARP); 713 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 714 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 715 ap->arp_op = htons(ARPOP_REVREPLY); 716 717 bcopy((char *) &ap->arp_sha, (char *) &ep->ether_dhost, 6); 718 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 719 bcopy((char *) ii->ii_eaddr, (char *) &ap->arp_sha, 6); 720 721 bcopy((char *) &ipaddr, (char *) ap->arp_tpa, 4); 722 /* Target hardware is unchanged. */ 723 bcopy((char *) &ii->ii_ipaddr, (char *) ap->arp_spa, 4); 724 725 len = sizeof(*ep) + sizeof(*ap); 726 n = write(ii->ii_fd, (char *) ep, len); 727 if (n != len) { 728 err(NONFATAL, "write: only %d of %d bytes written", n, len); 729 } 730 } 731 /* 732 * Get the netmask of an IP address. This routine is used if 733 * SIOCGIFNETMASK doesn't work. 734 */ 735 u_long 736 ipaddrtonetmask(addr) 737 u_long addr; 738 { 739 if (IN_CLASSA(addr)) 740 return IN_CLASSA_NET; 741 if (IN_CLASSB(addr)) 742 return IN_CLASSB_NET; 743 if (IN_CLASSC(addr)) 744 return IN_CLASSC_NET; 745 err(FATAL, "unknown IP address class: %08X", addr); 746 /* NOTREACHED */ 747 } 748 749 #if __STDC__ 750 #include <stdarg.h> 751 #else 752 #include <varargs.h> 753 #endif 754 755 void 756 #if __STDC__ 757 err(int fatal, const char *fmt,...) 758 #else 759 err(fmt, va_alist) 760 int fatal; 761 char *fmt; 762 va_dcl 763 #endif 764 { 765 va_list ap; 766 #if __STDC__ 767 va_start(ap, fmt); 768 #else 769 va_start(ap); 770 #endif 771 if (dflag) { 772 if (fatal) 773 (void) fprintf(stderr, "rarpd: error: "); 774 else 775 (void) fprintf(stderr, "rarpd: warning: "); 776 (void) vfprintf(stderr, fmt, ap); 777 (void) fprintf(stderr, "\n"); 778 } 779 vsyslog(LOG_ERR, fmt, ap); 780 va_end(ap); 781 if (fatal) 782 exit(1); 783 /* NOTREACHED */ 784 } 785 786 void 787 #if __STDC__ 788 debug(const char *fmt,...) 789 #else 790 debug(fmt, va_alist) 791 char *fmt; 792 va_dcl 793 #endif 794 { 795 va_list ap; 796 797 if (dflag) { 798 #if __STDC__ 799 va_start(ap, fmt); 800 #else 801 va_start(ap); 802 #endif 803 (void) fprintf(stderr, "rarpd: "); 804 (void) vfprintf(stderr, fmt, ap); 805 va_end(ap); 806 (void) fprintf(stderr, "\n"); 807 } 808 } 809