rarpd.c revision 1.17
1/* $NetBSD: rarpd.c,v 1.17 1997/03/23 00:48:15 cgd 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 24char 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 30static char rcsid[] = "$NetBSD: rarpd.c,v 1.17 1997/03/23 00:48:15 cgd 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 */ 76struct 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 */ 87struct if_info *iflist; 88 89int rarp_open __P((char *)); 90void init_one __P((char *)); 91void init_all __P((void)); 92void rarp_loop __P((void)); 93void lookup_eaddr __P((char *, u_char *)); 94void lookup_ipaddr __P((char *, u_long *, u_long *)); 95void usage __P((void)); 96void rarp_process __P((struct if_info *, u_char *)); 97void rarp_reply __P((struct if_info *, struct ether_header *, u_long)); 98void update_arptab __P((u_char *, u_long)); 99void err __P((int, const char *,...)); 100void debug __P((const char *,...)); 101u_long ipaddrtonetmask __P((u_long)); 102 103#ifdef REQUIRE_TFTPBOOT 104int rarp_bootable __P((u_long)); 105#endif 106 107int aflag = 0; /* listen on "all" interfaces */ 108int dflag = 0; /* print debugging messages */ 109int fflag = 0; /* don't fork */ 110 111int 112main(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_CONS, 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 */ 198void 199init_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 */ 221void 222init_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 263void 264usage() 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 271static int 272bpf_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 */ 294int 295rarp_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 */ 353static int 354rarp_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 (void) debug("got a packet"); 366 367 if (len < sizeof(*ep) + sizeof(*ap)) { 368 err(NONFATAL, "truncated request"); 369 return 0; 370 } 371#ifdef __NetBSD__ 372 /* now that we know the fixed part of the ARP hdr is there: */ 373 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 374 err(NONFATAL, "truncated request"); 375 return 0; 376 } 377#endif 378 /* XXX This test might be better off broken out... */ 379#ifdef __FreeBSD__ 380 /* BPF (incorrectly) returns this in host order. */ 381 if (ep->ether_type != ETHERTYPE_REVARP || 382#else 383 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 384#endif 385#ifdef __NetBSD__ 386 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 387 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 388 ntohs (ap->ar_pro) != ETHERTYPE_IP || 389 ap->ar_hln != 6 || ap->ar_pln != 4) { 390#else 391 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 392 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 393 ntohs (ap->arp_pro) != ETHERTYPE_IP || 394 ap->arp_hln != 6 || ap->arp_pln != 4) { 395#endif 396 err(NONFATAL, "request fails sanity check"); 397 return 0; 398 } 399#ifdef __NetBSD__ 400 if (bcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 401#else 402 if (bcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 403#endif 404 err(NONFATAL, "ether/arp sender address mismatch"); 405 return 0; 406 } 407#ifdef __NetBSD__ 408 if (bcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 409#else 410 if (bcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 411#endif 412 err(NONFATAL, "ether/arp target address mismatch"); 413 return 0; 414 } 415 return 1; 416} 417 418/* 419 * Loop indefinitely listening for RARP requests on the 420 * interfaces in 'iflist'. 421 */ 422void 423rarp_loop() 424{ 425 u_char *buf, *bp, *ep; 426 int cc, fd; 427 fd_set fds, listeners; 428 int bufsize, maxfd = 0; 429 struct if_info *ii; 430 431 if (iflist == 0) { 432 err(FATAL, "no interfaces"); 433 /* NOTREACHED */ 434 } 435 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 436 err(FATAL, "BIOCGBLEN: %s", strerror(errno)); 437 /* NOTREACHED */ 438 } 439 buf = (u_char *) malloc((unsigned) bufsize); 440 if (buf == 0) { 441 err(FATAL, "malloc: %s", strerror(errno)); 442 /* NOTREACHED */ 443 } 444 /* 445 * Find the highest numbered file descriptor for select(). 446 * Initialize the set of descriptors to listen to. 447 */ 448 FD_ZERO(&fds); 449 for (ii = iflist; ii; ii = ii->ii_next) { 450 FD_SET(ii->ii_fd, &fds); 451 if (ii->ii_fd > maxfd) 452 maxfd = ii->ii_fd; 453 } 454 while (1) { 455 listeners = fds; 456 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 457 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 458 err(FATAL, "select: %s", strerror(errno)); 459 /* NOTREACHED */ 460 } 461 for (ii = iflist; ii; ii = ii->ii_next) { 462 fd = ii->ii_fd; 463 if (!FD_ISSET(fd, &listeners)) 464 continue; 465 again: 466 cc = read(fd, (char *) buf, bufsize); 467 /* Don't choke when we get ptraced */ 468 if (cc < 0 && errno == EINTR) 469 goto again; 470 /* Due to a SunOS bug, after 2^31 bytes, the file 471 * offset overflows and read fails with EINVAL. The 472 * lseek() to 0 will fix things. */ 473 if (cc < 0) { 474 if (errno == EINVAL && 475 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 476 (void) lseek(fd, 0, 0); 477 goto again; 478 } 479 err(FATAL, "read: %s", strerror(errno)); 480 /* NOTREACHED */ 481 } 482 /* Loop through the packet(s) */ 483#define bhp ((struct bpf_hdr *)bp) 484 bp = buf; 485 ep = bp + cc; 486 while (bp < ep) { 487 register int caplen, hdrlen; 488 489 caplen = bhp->bh_caplen; 490 hdrlen = bhp->bh_hdrlen; 491 if (rarp_check(bp + hdrlen, caplen)) 492 rarp_process(ii, bp + hdrlen); 493 bp += BPF_WORDALIGN(hdrlen + caplen); 494 } 495 } 496 } 497} 498 499#ifdef REQUIRE_TFTPBOOT 500 501#ifndef TFTP_DIR 502#define TFTP_DIR "/tftpboot" 503#endif 504 505/* 506 * True if this server can boot the host whose IP address is 'addr'. 507 * This check is made by looking in the tftp directory for the 508 * configuration file. 509 */ 510int 511rarp_bootable(addr) 512 u_long addr; 513{ 514 register struct dirent *dent; 515 register DIR *d; 516 char ipname[9]; 517 static DIR *dd = 0; 518 519 (void) sprintf(ipname, "%08X", addr); 520 /* If directory is already open, rewind it. Otherwise, open it. */ 521 if (d = dd) 522 rewinddir(d); 523 else { 524 if (chdir(TFTP_DIR) == -1) { 525 err(FATAL, "chdir: %s", strerror(errno)); 526 /* NOTREACHED */ 527 } 528 d = opendir("."); 529 if (d == 0) { 530 err(FATAL, "opendir: %s", strerror(errno)); 531 /* NOTREACHED */ 532 } 533 dd = d; 534 } 535 while (dent = readdir(d)) 536 if (strncmp(dent->d_name, ipname, 8) == 0) 537 return 1; 538 return 0; 539} 540#endif /* REQUIRE_TFTPBOOT */ 541 542/* 543 * Given a list of IP addresses, 'alist', return the first address that 544 * is on network 'net'; 'netmask' is a mask indicating the network portion 545 * of the address. 546 */ 547u_int32_t 548choose_ipaddr(alist, net, netmask) 549 u_int32_t **alist; 550 u_int32_t net; 551 u_int32_t netmask; 552{ 553 for (; *alist; ++alist) { 554 if ((**alist & netmask) == net) 555 return **alist; 556 } 557 return 0; 558} 559/* 560 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 561 * already been checked for validity. The reply is overlaid on the request. 562 */ 563void 564rarp_process(ii, pkt) 565 struct if_info *ii; 566 u_char *pkt; 567{ 568 struct ether_header *ep; 569 struct hostent *hp; 570 u_long target_ipaddr; 571 char ename[256]; 572 struct in_addr in; 573 574 ep = (struct ether_header *) pkt; 575 576 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0 || 577 (hp = gethostbyname(ename)) == 0) 578 return; 579 580 /* Choose correct address from list. */ 581 if (hp->h_addrtype != AF_INET) { 582 err(FATAL, "cannot handle non IP addresses"); 583 /* NOTREACHED */ 584 } 585 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 586 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 587 588 if (target_ipaddr == 0) { 589 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 590 err(NONFATAL, "cannot find %s on net %s\n", 591 ename, inet_ntoa(in)); 592 return; 593 } 594#ifdef REQUIRE_TFTPBOOT 595 if (rarp_bootable(htonl(target_ipaddr))) 596#endif 597 rarp_reply(ii, ep, target_ipaddr); 598} 599/* 600 * Lookup the ethernet address of the interface attached to the BPF 601 * file descriptor 'fd'; return it in 'eaddr'. 602 */ 603void 604lookup_eaddr(ifname, eaddr) 605 char *ifname; 606 u_char *eaddr; 607{ 608 char inbuf[8192]; 609 struct ifconf ifc; 610 struct ifreq *ifr; 611 struct sockaddr_dl *sdl; 612 int fd; 613 int i, len; 614 615 /* We cannot use SIOCGIFADDR on the BPF descriptor. 616 We must instead get all the interfaces with SIOCGIFCONF 617 and find the right one. */ 618 619 /* Use datagram socket to get Ethernet address. */ 620 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 621 err(FATAL, "socket: %s", strerror(errno)); 622 /* NOTREACHED */ 623 } 624 625 ifc.ifc_len = sizeof(inbuf); 626 ifc.ifc_buf = inbuf; 627 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 628 ifc.ifc_len < sizeof(struct ifreq)) { 629 err(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 630 /* NOTREACHED */ 631 } 632 ifr = ifc.ifc_req; 633 for (i = 0; i < ifc.ifc_len; 634 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 635 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 636 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 637 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 638 sdl->sdl_alen != 6) 639 continue; 640 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 641 bcopy((caddr_t)LLADDR(sdl), (caddr_t)eaddr, 6); 642 if (dflag) 643 fprintf(stderr, "%s: %x:%x:%x:%x:%x:%x\n", 644 ifr->ifr_name, eaddr[0], eaddr[1], 645 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 646 return; 647 } 648 } 649 650 err(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 651} 652/* 653 * Lookup the IP address and network mask of the interface named 'ifname'. 654 */ 655void 656lookup_ipaddr(ifname, addrp, netmaskp) 657 char *ifname; 658 u_long *addrp; 659 u_long *netmaskp; 660{ 661 int fd; 662 struct ifreq ifr; 663 664 /* Use datagram socket to get IP address. */ 665 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 666 err(FATAL, "socket: %s", strerror(errno)); 667 /* NOTREACHED */ 668 } 669 (void) strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 670 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 671 err(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 672 /* NOTREACHED */ 673 } 674 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 675 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 676 perror("SIOCGIFNETMASK"); 677 exit(1); 678 } 679 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 680 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 681 * address class. */ 682 if (*netmaskp == 0) 683 *netmaskp = ipaddrtonetmask(*addrp); 684 685 (void) close(fd); 686} 687/* 688 * Poke the kernel arp tables with the ethernet/ip address combinataion 689 * given. When processing a reply, we must do this so that the booting 690 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 691 * address of the guy being booted (he cannot answer the ARP). 692 */ 693void 694update_arptab(ep, ipaddr) 695 u_char *ep; 696 u_long ipaddr; 697{ 698 int s; 699 struct arpreq request; 700 struct sockaddr_in *sin; 701 702 request.arp_flags = 0; 703 sin = (struct sockaddr_in *) & request.arp_pa; 704 sin->sin_family = AF_INET; 705 sin->sin_addr.s_addr = ipaddr; 706 request.arp_ha.sa_family = AF_UNSPEC; 707 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 708 because AF_UNSPEC is zero and the kernel assumes that a zero 709 sa_family means that the real sa_family value is in sa_len. */ 710 request.arp_ha.sa_len = 16; /* XXX */ 711 bcopy((char *) ep, (char *) request.arp_ha.sa_data, 6); 712 713#if 0 714 s = socket(AF_INET, SOCK_DGRAM, 0); 715 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 716 err(NONFATAL, "SIOCSARP: %s", strerror(errno)); 717 } 718 (void) close(s); 719#endif 720} 721/* 722 * Build a reverse ARP packet and sent it out on the interface. 723 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 724 * on top of the request, then written to the network. 725 * 726 * RFC 903 defines the ether_arp fields as follows. The following comments 727 * are taken (more or less) straight from this document. 728 * 729 * ARPOP_REVREQUEST 730 * 731 * arp_sha is the hardware address of the sender of the packet. 732 * arp_spa is undefined. 733 * arp_tha is the 'target' hardware address. 734 * In the case where the sender wishes to determine his own 735 * protocol address, this, like arp_sha, will be the hardware 736 * address of the sender. 737 * arp_tpa is undefined. 738 * 739 * ARPOP_REVREPLY 740 * 741 * arp_sha is the hardware address of the responder (the sender of the 742 * reply packet). 743 * arp_spa is the protocol address of the responder (see the note below). 744 * arp_tha is the hardware address of the target, and should be the same as 745 * that which was given in the request. 746 * arp_tpa is the protocol address of the target, that is, the desired address. 747 * 748 * Note that the requirement that arp_spa be filled in with the responder's 749 * protocol is purely for convenience. For instance, if a system were to use 750 * both ARP and RARP, then the inclusion of the valid protocol-hardware 751 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 752 * ARP request. 753 */ 754void 755rarp_reply(ii, ep, ipaddr) 756 struct if_info *ii; 757 struct ether_header *ep; 758 u_long ipaddr; 759{ 760 int n; 761#ifdef __NetBSD__ 762 struct arphdr *ap = (struct arphdr *) (ep + 1); 763#else 764 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 765#endif 766 767 int len; 768 769#ifdef __NetBSD__ 770 update_arptab(ar_sha(ap), ipaddr); 771#else 772 update_arptab((u_char *) & ap->arp_sha, ipaddr); 773#endif 774 775 /* Build the rarp reply by modifying the rarp request in place. */ 776#ifdef __FreeBSD__ 777 /* BPF (incorrectly) wants this in host order. */ 778 ep->ether_type = ETHERTYPE_REVARP; 779#else 780 ep->ether_type = htons(ETHERTYPE_REVARP); 781#endif 782#ifdef __NetBSD__ 783 ap->ar_hrd = htons(ARPHRD_ETHER); 784 ap->ar_pro = htons(ETHERTYPE_IP); 785 ap->ar_op = htons(ARPOP_REVREPLY); 786 787 bcopy(ar_sha(ap), (char *) &ep->ether_dhost, 6); 788 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 789 bcopy((char *) ii->ii_eaddr, ar_sha(ap), 6); 790 791 bcopy((char *) &ipaddr, ar_tpa(ap), 4); 792 /* Target hardware is unchanged. */ 793 bcopy((char *) &ii->ii_ipaddr, ar_spa(ap), 4); 794 795 len = sizeof(*ep) + sizeof(*ap) + 796 2 * ap->ar_pln + 2 * ap->ar_hln; 797#else 798 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 799 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 800 ap->arp_op = htons(ARPOP_REVREPLY); 801 802 bcopy((char *) &ap->arp_sha, (char *) &ep->ether_dhost, 6); 803 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 804 bcopy((char *) ii->ii_eaddr, (char *) &ap->arp_sha, 6); 805 806 bcopy((char *) &ipaddr, (char *) ap->arp_tpa, 4); 807 /* Target hardware is unchanged. */ 808 bcopy((char *) &ii->ii_ipaddr, (char *) ap->arp_spa, 4); 809 810 len = sizeof(*ep) + sizeof(*ap); 811#endif 812 813 n = write(ii->ii_fd, (char *) ep, len); 814 if (n != len) { 815 err(NONFATAL, "write: only %d of %d bytes written", n, len); 816 } 817} 818/* 819 * Get the netmask of an IP address. This routine is used if 820 * SIOCGIFNETMASK doesn't work. 821 */ 822u_long 823ipaddrtonetmask(addr) 824 u_long addr; 825{ 826 if (IN_CLASSA(addr)) 827 return IN_CLASSA_NET; 828 if (IN_CLASSB(addr)) 829 return IN_CLASSB_NET; 830 if (IN_CLASSC(addr)) 831 return IN_CLASSC_NET; 832 err(FATAL, "unknown IP address class: %08X", addr); 833 /* NOTREACHED */ 834} 835 836#if __STDC__ 837#include <stdarg.h> 838#else 839#include <varargs.h> 840#endif 841 842void 843#if __STDC__ 844err(int fatal, const char *fmt,...) 845#else 846err(fmt, va_alist) 847 int fatal; 848 char *fmt; 849va_dcl 850#endif 851{ 852 va_list ap; 853#if __STDC__ 854 va_start(ap, fmt); 855#else 856 va_start(ap); 857#endif 858 if (dflag) { 859 if (fatal) 860 (void) fprintf(stderr, "rarpd: error: "); 861 else 862 (void) fprintf(stderr, "rarpd: warning: "); 863 (void) vfprintf(stderr, fmt, ap); 864 (void) fprintf(stderr, "\n"); 865 } 866 vsyslog(LOG_ERR, fmt, ap); 867 va_end(ap); 868 if (fatal) 869 exit(1); 870 /* NOTREACHED */ 871} 872 873void 874#if __STDC__ 875debug(const char *fmt,...) 876#else 877debug(fmt, va_alist) 878 char *fmt; 879va_dcl 880#endif 881{ 882 va_list ap; 883 884 if (dflag) { 885#if __STDC__ 886 va_start(ap, fmt); 887#else 888 va_start(ap); 889#endif 890 (void) fprintf(stderr, "rarpd: "); 891 (void) vfprintf(stderr, fmt, ap); 892 va_end(ap); 893 (void) fprintf(stderr, "\n"); 894 } 895} 896