rarpd.c revision 1.20
1/* $NetBSD: rarpd.c,v 1.20 1997/10/17 12:53:14 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#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 1.20 1997/10/17 12:53:14 lukem Exp $"); 32#endif 33 34 35/* 36 * rarpd - Reverse ARP Daemon 37 * 38 * Usage: rarpd -a [ -d -f ] 39 * rarpd [ -d -f ] interface 40 */ 41 42#include <stdio.h> 43#include <stdlib.h> 44#include <syslog.h> 45#include <string.h> 46#include <strings.h> 47#include <sys/types.h> 48#include <unistd.h> 49#include <sys/time.h> 50#include <net/bpf.h> 51#include <sys/socket.h> 52#include <sys/ioctl.h> 53#include <net/if.h> 54#include <net/if_dl.h> 55#ifdef __NetBSD__ 56#include <net/if_ether.h> 57#endif 58#include <net/if_types.h> 59#include <netinet/in.h> 60#ifdef __NetBSD__ 61#include <netinet/if_inarp.h> 62#else 63#include <netinet/if_ether.h> 64#endif 65#include <sys/errno.h> 66#include <sys/file.h> 67#include <netdb.h> 68#include <arpa/inet.h> 69#include <dirent.h> 70 71#define FATAL 1 /* fatal error occurred */ 72#define NONFATAL 0 /* non fatal error occurred */ 73 74/* 75 * The structure for each interface. 76 */ 77struct if_info { 78 int ii_fd; /* BPF file descriptor */ 79 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 80 u_long ii_ipaddr; /* IP address of this interface */ 81 u_long ii_netmask; /* subnet or net mask */ 82 struct if_info *ii_next; 83}; 84/* 85 * The list of all interfaces that are being listened to. rarp_loop() 86 * "selects" on the descriptors in this list. 87 */ 88struct if_info *iflist; 89 90u_int32_t choose_ipaddr __P((u_int32_t **, u_int32_t, u_int32_t)); 91void debug __P((const char *,...)); 92void init_all __P((void)); 93void init_one __P((char *)); 94u_long ipaddrtonetmask __P((u_long)); 95void lookup_eaddr __P((char *, u_char *)); 96void lookup_ipaddr __P((char *, u_long *, u_long *)); 97int main __P((int, char **)); 98void rarp_loop __P((void)); 99int rarp_open __P((char *)); 100void rarp_process __P((struct if_info *, u_char *)); 101void rarp_reply __P((struct if_info *, struct ether_header *, u_long)); 102void rarperr __P((int, const char *,...)); 103void update_arptab __P((u_char *, u_long)); 104void usage __P((void)); 105 106static int bpf_open __P((void)); 107static int rarp_check __P((u_char *, int)); 108 109#ifdef REQUIRE_TFTPBOOT 110int rarp_bootable __P((u_long)); 111#endif 112 113int aflag = 0; /* listen on "all" interfaces */ 114int dflag = 0; /* print debugging messages */ 115int fflag = 0; /* don't fork */ 116 117int 118main(argc, argv) 119 int argc; 120 char **argv; 121{ 122 extern char *__progname; 123 124 int op, pid, devnull, f; 125 char *ifname, *hostname; 126 127 /* All error reporting is done through syslogs. */ 128 openlog(__progname, LOG_PID, LOG_DAEMON); 129 130 opterr = 0; 131 while ((op = getopt(argc, argv, "adf")) != -1) { 132 switch (op) { 133 case 'a': 134 ++aflag; 135 break; 136 137 case 'd': 138 ++dflag; 139 break; 140 141 case 'f': 142 ++fflag; 143 break; 144 145 default: 146 usage(); 147 /* NOTREACHED */ 148 } 149 } 150 ifname = argv[optind++]; 151 hostname = ifname ? argv[optind] : 0; 152 if ((aflag && ifname) || (!aflag && ifname == 0)) 153 usage(); 154 155 if (aflag) 156 init_all(); 157 else 158 init_one(ifname); 159 160 if ((!fflag) && (!dflag)) { 161 pid = fork(); 162 if (pid > 0) 163 /* Parent exits, leaving child in background. */ 164 exit(0); 165 else 166 if (pid == -1) { 167 rarperr(FATAL, "cannot fork"); 168 /* NOTREACHED */ 169 } 170 /* Fade into the background */ 171 f = open("/dev/tty", O_RDWR); 172 if (f >= 0) { 173 if (ioctl(f, TIOCNOTTY, 0) < 0) { 174 rarperr(FATAL, 175 "TIOCNOTTY: %s", strerror(errno)); 176 /* NOTREACHED */ 177 } 178 (void) close(f); 179 } 180 (void) chdir("/"); 181 (void) setpgrp(0, getpid()); 182 devnull = open("/dev/null", O_RDWR); 183 if (devnull >= 0) { 184 (void) dup2(devnull, 0); 185 (void) dup2(devnull, 1); 186 (void) dup2(devnull, 2); 187 if (devnull > 2) 188 (void) close(devnull); 189 } 190 } 191 rarp_loop(); 192 /* NOTREACHED */ 193 return (0); 194} 195 196/* 197 * Add 'ifname' to the interface list. Lookup its IP address and network 198 * mask and Ethernet address, and open a BPF file for it. 199 */ 200void 201init_one(ifname) 202 char *ifname; 203{ 204 struct if_info *p; 205 206 p = (struct if_info *)malloc(sizeof(*p)); 207 if (p == 0) { 208 rarperr(FATAL, "malloc: %s", strerror(errno)); 209 /* NOTREACHED */ 210 } 211 p->ii_next = iflist; 212 iflist = p; 213 214 p->ii_fd = rarp_open(ifname); 215 lookup_eaddr(ifname, p->ii_eaddr); 216 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 217} 218 219/* 220 * Initialize all "candidate" interfaces that are in the system 221 * configuration list. A "candidate" is up, not loopback and not 222 * point to point. 223 */ 224void 225init_all() 226{ 227 char inbuf[8192]; 228 struct ifconf ifc; 229 struct ifreq ifreq, *ifr; 230 int fd; 231 int i, len; 232 233 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 234 rarperr(FATAL, "socket: %s", strerror(errno)); 235 /* NOTREACHED */ 236 } 237 238 ifc.ifc_len = sizeof(inbuf); 239 ifc.ifc_buf = inbuf; 240 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 241 ifc.ifc_len < sizeof(struct ifreq)) { 242 rarperr(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 243 /* NOTREACHED */ 244 } 245 ifr = ifc.ifc_req; 246 ifreq.ifr_name[0] = '\0'; 247 for (i = 0; i < ifc.ifc_len; 248 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 249 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 250 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name))) 251 continue; 252 ifreq = *ifr; 253 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 254 rarperr(FATAL, "init_all: SIOCGIFFLAGS: %s", 255 strerror(errno)); 256 /* NOTREACHED */ 257 } 258 if ((ifr->ifr_flags & 259 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 260 continue; 261 init_one(ifr->ifr_name); 262 } 263 (void) close(fd); 264} 265 266void 267usage() 268{ 269 (void) fprintf(stderr, "usage: rarpd -a [ -d -f ]\n"); 270 (void) fprintf(stderr, " rarpd [ -d -f ] interface\n"); 271 exit(1); 272} 273 274static int 275bpf_open() 276{ 277 int fd; 278 int n = 0; 279 char device[sizeof "/dev/bpf000"]; 280 281 /* Go through all the minors and find one that isn't in use. */ 282 do { 283 (void) sprintf(device, "/dev/bpf%d", n++); 284 fd = open(device, O_RDWR); 285 } while (fd < 0 && errno == EBUSY); 286 287 if (fd < 0) { 288 rarperr(FATAL, "%s: %s", device, strerror(errno)); 289 /* NOTREACHED */ 290 } 291 return fd; 292} 293/* 294 * Open a BPF file and attach it to the interface named 'device'. 295 * Set immediate mode, and set a filter that accepts only RARP requests. 296 */ 297int 298rarp_open(device) 299 char *device; 300{ 301 int fd; 302 struct ifreq ifr; 303 u_int dlt; 304 int immediate; 305 306 static struct bpf_insn insns[] = { 307 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 308 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 309 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 310 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 311 BPF_STMT(BPF_RET | BPF_K, 312 sizeof(struct arphdr) + 313 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 314 sizeof(struct ether_header)), 315 BPF_STMT(BPF_RET | BPF_K, 0), 316 }; 317 static struct bpf_program filter = { 318 sizeof insns / sizeof(insns[0]), 319 insns 320 }; 321 322 fd = bpf_open(); 323 324 /* Set immediate mode so packets are processed as they arrive. */ 325 immediate = 1; 326 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 327 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 328 /* NOTREACHED */ 329 } 330 (void) strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); 331 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 332 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 333 /* NOTREACHED */ 334 } 335 /* Check that the data link layer is an Ethernet; this code won't work 336 * with anything else. */ 337 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 338 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 339 /* NOTREACHED */ 340 } 341 if (dlt != DLT_EN10MB) { 342 rarperr(FATAL, "%s is not an ethernet", device); 343 /* NOTREACHED */ 344 } 345 /* Set filter program. */ 346 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 347 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 348 /* NOTREACHED */ 349 } 350 return fd; 351} 352/* 353 * Perform various sanity checks on the RARP request packet. Return 354 * false on failure and log the reason. 355 */ 356static int 357rarp_check(p, len) 358 u_char *p; 359 int len; 360{ 361 struct ether_header *ep = (struct ether_header *) p; 362#ifdef __NetBSD__ 363 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 364#else 365 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 366#endif 367 368 if (dflag) 369 fprintf(stderr, "got a packet\n"); 370 371 if (len < sizeof(*ep) + sizeof(*ap)) { 372 rarperr(NONFATAL, "truncated request"); 373 return 0; 374 } 375#ifdef __NetBSD__ 376 /* now that we know the fixed part of the ARP hdr is there: */ 377 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 378 rarperr(NONFATAL, "truncated request"); 379 return 0; 380 } 381#endif 382 /* XXX This test might be better off broken out... */ 383#ifdef __FreeBSD__ 384 /* BPF (incorrectly) returns this in host order. */ 385 if (ep->ether_type != ETHERTYPE_REVARP || 386#else 387 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 388#endif 389#ifdef __NetBSD__ 390 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 391 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 392 ntohs (ap->ar_pro) != ETHERTYPE_IP || 393 ap->ar_hln != 6 || ap->ar_pln != 4) { 394#else 395 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 396 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 397 ntohs (ap->arp_pro) != ETHERTYPE_IP || 398 ap->arp_hln != 6 || ap->arp_pln != 4) { 399#endif 400 rarperr(NONFATAL, "request fails sanity check"); 401 return 0; 402 } 403#ifdef __NetBSD__ 404 if (bcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 405#else 406 if (bcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 407#endif 408 rarperr(NONFATAL, "ether/arp sender address mismatch"); 409 return 0; 410 } 411#ifdef __NetBSD__ 412 if (bcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 413#else 414 if (bcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 415#endif 416 rarperr(NONFATAL, "ether/arp target address mismatch"); 417 return 0; 418 } 419 return 1; 420} 421 422/* 423 * Loop indefinitely listening for RARP requests on the 424 * interfaces in 'iflist'. 425 */ 426void 427rarp_loop() 428{ 429 u_char *buf, *bp, *ep; 430 int cc, fd; 431 fd_set fds, listeners; 432 int bufsize, maxfd = 0; 433 struct if_info *ii; 434 435 if (iflist == 0) { 436 rarperr(FATAL, "no interfaces"); 437 /* NOTREACHED */ 438 } 439 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 440 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 441 /* NOTREACHED */ 442 } 443 buf = (u_char *) malloc((unsigned) bufsize); 444 if (buf == 0) { 445 rarperr(FATAL, "malloc: %s", strerror(errno)); 446 /* NOTREACHED */ 447 } 448 /* 449 * Find the highest numbered file descriptor for select(). 450 * Initialize the set of descriptors to listen to. 451 */ 452 FD_ZERO(&fds); 453 for (ii = iflist; ii; ii = ii->ii_next) { 454 FD_SET(ii->ii_fd, &fds); 455 if (ii->ii_fd > maxfd) 456 maxfd = ii->ii_fd; 457 } 458 while (1) { 459 listeners = fds; 460 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 461 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 462 rarperr(FATAL, "select: %s", strerror(errno)); 463 /* NOTREACHED */ 464 } 465 for (ii = iflist; ii; ii = ii->ii_next) { 466 fd = ii->ii_fd; 467 if (!FD_ISSET(fd, &listeners)) 468 continue; 469 again: 470 cc = read(fd, (char *) buf, bufsize); 471 /* Don't choke when we get ptraced */ 472 if (cc < 0 && errno == EINTR) 473 goto again; 474 /* Due to a SunOS bug, after 2^31 bytes, the file 475 * offset overflows and read fails with EINVAL. The 476 * lseek() to 0 will fix things. */ 477 if (cc < 0) { 478 if (errno == EINVAL && 479 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 480 (void) lseek(fd, 0, 0); 481 goto again; 482 } 483 rarperr(FATAL, "read: %s", strerror(errno)); 484 /* NOTREACHED */ 485 } 486 /* Loop through the packet(s) */ 487#define bhp ((struct bpf_hdr *)bp) 488 bp = buf; 489 ep = bp + cc; 490 while (bp < ep) { 491 register int caplen, hdrlen; 492 493 caplen = bhp->bh_caplen; 494 hdrlen = bhp->bh_hdrlen; 495 if (rarp_check(bp + hdrlen, caplen)) 496 rarp_process(ii, bp + hdrlen); 497 bp += BPF_WORDALIGN(hdrlen + caplen); 498 } 499 } 500 } 501} 502 503#ifdef REQUIRE_TFTPBOOT 504 505#ifndef TFTP_DIR 506#define TFTP_DIR "/tftpboot" 507#endif 508 509/* 510 * True if this server can boot the host whose IP address is 'addr'. 511 * This check is made by looking in the tftp directory for the 512 * configuration file. 513 */ 514int 515rarp_bootable(addr) 516 u_long addr; 517{ 518 register struct dirent *dent; 519 register DIR *d; 520 char ipname[9]; 521 static DIR *dd = 0; 522 523 (void) sprintf(ipname, "%08X", addr); 524 /* If directory is already open, rewind it. Otherwise, open it. */ 525 if (d = dd) 526 rewinddir(d); 527 else { 528 if (chdir(TFTP_DIR) == -1) { 529 rarperr(FATAL, "chdir: %s", strerror(errno)); 530 /* NOTREACHED */ 531 } 532 d = opendir("."); 533 if (d == 0) { 534 rarperr(FATAL, "opendir: %s", strerror(errno)); 535 /* NOTREACHED */ 536 } 537 dd = d; 538 } 539 while (dent = readdir(d)) 540 if (strncmp(dent->d_name, ipname, 8) == 0) 541 return 1; 542 return 0; 543} 544#endif /* REQUIRE_TFTPBOOT */ 545 546/* 547 * Given a list of IP addresses, 'alist', return the first address that 548 * is on network 'net'; 'netmask' is a mask indicating the network portion 549 * of the address. 550 */ 551u_int32_t 552choose_ipaddr(alist, net, netmask) 553 u_int32_t **alist; 554 u_int32_t net; 555 u_int32_t netmask; 556{ 557 for (; *alist; ++alist) { 558 if ((**alist & netmask) == net) 559 return **alist; 560 } 561 return 0; 562} 563/* 564 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 565 * already been checked for validity. The reply is overlaid on the request. 566 */ 567void 568rarp_process(ii, pkt) 569 struct if_info *ii; 570 u_char *pkt; 571{ 572 struct ether_header *ep; 573 struct hostent *hp; 574 u_long target_ipaddr; 575 char ename[MAXHOSTNAMELEN + 1]; 576 struct in_addr in; 577 578 ep = (struct ether_header *) pkt; 579 580 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 581 debug("no IP address for %s", 582 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 583 return; 584 } 585 ename[sizeof(ename)-1] = '\0'; 586 587 if ((hp = gethostbyname(ename)) == 0) { 588 debug("gethostbyname(%s) failed: %s", ename, 589 hstrerror(h_errno)); 590 return; 591 } 592 593 /* Choose correct address from list. */ 594 if (hp->h_addrtype != AF_INET) { 595 rarperr(FATAL, "cannot handle non IP addresses"); 596 /* NOTREACHED */ 597 } 598 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 599 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 600 601 if (target_ipaddr == 0) { 602 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 603 rarperr(NONFATAL, "cannot find %s on net %s\n", 604 ename, inet_ntoa(in)); 605 return; 606 } 607#ifdef REQUIRE_TFTPBOOT 608 if (rarp_bootable(htonl(target_ipaddr))) 609#endif 610 rarp_reply(ii, ep, target_ipaddr); 611#ifdef REQUIRE_TFTPBOOT 612 else 613 debug("%08X not bootable", htonl(target_ipaddr)); 614#endif 615} 616/* 617 * Lookup the ethernet address of the interface attached to the BPF 618 * file descriptor 'fd'; return it in 'eaddr'. 619 */ 620void 621lookup_eaddr(ifname, eaddr) 622 char *ifname; 623 u_char *eaddr; 624{ 625 char inbuf[8192]; 626 struct ifconf ifc; 627 struct ifreq *ifr; 628 struct sockaddr_dl *sdl; 629 int fd; 630 int i, len; 631 632 /* We cannot use SIOCGIFADDR on the BPF descriptor. 633 We must instead get all the interfaces with SIOCGIFCONF 634 and find the right one. */ 635 636 /* Use datagram socket to get Ethernet address. */ 637 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 638 rarperr(FATAL, "socket: %s", strerror(errno)); 639 /* NOTREACHED */ 640 } 641 642 ifc.ifc_len = sizeof(inbuf); 643 ifc.ifc_buf = inbuf; 644 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 645 ifc.ifc_len < sizeof(struct ifreq)) { 646 rarperr(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 647 /* NOTREACHED */ 648 } 649 ifr = ifc.ifc_req; 650 for (i = 0; i < ifc.ifc_len; 651 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 652 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 653 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 654 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 655 sdl->sdl_alen != 6) 656 continue; 657 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 658 bcopy((caddr_t)LLADDR(sdl), (caddr_t)eaddr, 6); 659 debug("%s: %x:%x:%x:%x:%x:%x", 660 ifr->ifr_name, eaddr[0], eaddr[1], 661 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 662 return; 663 } 664 } 665 666 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 667} 668/* 669 * Lookup the IP address and network mask of the interface named 'ifname'. 670 */ 671void 672lookup_ipaddr(ifname, addrp, netmaskp) 673 char *ifname; 674 u_long *addrp; 675 u_long *netmaskp; 676{ 677 int fd; 678 struct ifreq ifr; 679 680 /* Use datagram socket to get IP address. */ 681 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 682 rarperr(FATAL, "socket: %s", strerror(errno)); 683 /* NOTREACHED */ 684 } 685 (void) strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 686 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 687 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 688 /* NOTREACHED */ 689 } 690 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 691 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 692 perror("SIOCGIFNETMASK"); 693 exit(1); 694 } 695 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 696 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 697 * address class. */ 698 if (*netmaskp == 0) 699 *netmaskp = ipaddrtonetmask(*addrp); 700 701 (void) close(fd); 702} 703/* 704 * Poke the kernel arp tables with the ethernet/ip address combinataion 705 * given. When processing a reply, we must do this so that the booting 706 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 707 * address of the guy being booted (he cannot answer the ARP). 708 */ 709void 710update_arptab(ep, ipaddr) 711 u_char *ep; 712 u_long 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 bcopy((char *) ep, (char *) request.arp_ha.sa_data, 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/* 737 * Build a reverse ARP packet and sent it out on the interface. 738 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 739 * on top of the request, then written to the network. 740 * 741 * RFC 903 defines the ether_arp fields as follows. The following comments 742 * are taken (more or less) straight from this document. 743 * 744 * ARPOP_REVREQUEST 745 * 746 * arp_sha is the hardware address of the sender of the packet. 747 * arp_spa is undefined. 748 * arp_tha is the 'target' hardware address. 749 * In the case where the sender wishes to determine his own 750 * protocol address, this, like arp_sha, will be the hardware 751 * address of the sender. 752 * arp_tpa is undefined. 753 * 754 * ARPOP_REVREPLY 755 * 756 * arp_sha is the hardware address of the responder (the sender of the 757 * reply packet). 758 * arp_spa is the protocol address of the responder (see the note below). 759 * arp_tha is the hardware address of the target, and should be the same as 760 * that which was given in the request. 761 * arp_tpa is the protocol address of the target, that is, the desired address. 762 * 763 * Note that the requirement that arp_spa be filled in with the responder's 764 * protocol is purely for convenience. For instance, if a system were to use 765 * both ARP and RARP, then the inclusion of the valid protocol-hardware 766 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 767 * ARP request. 768 */ 769void 770rarp_reply(ii, ep, ipaddr) 771 struct if_info *ii; 772 struct ether_header *ep; 773 u_long ipaddr; 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 update_arptab(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 bcopy(ar_sha(ap), (char *) &ep->ether_dhost, 6); 803 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 804 bcopy((char *) ii->ii_eaddr, ar_sha(ap), 6); 805 806 bcopy((char *) &ipaddr, ar_tpa(ap), 4); 807 /* Target hardware is unchanged. */ 808 bcopy((char *) &ii->ii_ipaddr, ar_spa(ap), 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 bcopy((char *) &ap->arp_sha, (char *) &ep->ether_dhost, 6); 818 bcopy((char *) ii->ii_eaddr, (char *) &ep->ether_shost, 6); 819 bcopy((char *) ii->ii_eaddr, (char *) &ap->arp_sha, 6); 820 821 bcopy((char *) &ipaddr, (char *) ap->arp_tpa, 4); 822 /* Target hardware is unchanged. */ 823 bcopy((char *) &ii->ii_ipaddr, (char *) ap->arp_spa, 4); 824 825 len = sizeof(*ep) + sizeof(*ap); 826#endif 827 828 n = write(ii->ii_fd, (char *) ep, len); 829 if (n != len) { 830 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 831 } 832} 833/* 834 * Get the netmask of an IP address. This routine is used if 835 * SIOCGIFNETMASK doesn't work. 836 */ 837u_long 838ipaddrtonetmask(addr) 839 u_long addr; 840{ 841 if (IN_CLASSA(addr)) 842 return IN_CLASSA_NET; 843 if (IN_CLASSB(addr)) 844 return IN_CLASSB_NET; 845 if (IN_CLASSC(addr)) 846 return IN_CLASSC_NET; 847 rarperr(FATAL, "unknown IP address class: %08X", addr); 848 /* NOTREACHED */ 849 return(-1); 850} 851 852#if __STDC__ 853#include <stdarg.h> 854#else 855#include <varargs.h> 856#endif 857 858void 859#if __STDC__ 860rarperr(int fatal, const char *fmt,...) 861#else 862rarperr(fmt, va_alist) 863 int fatal; 864 char *fmt; 865va_dcl 866#endif 867{ 868 va_list ap; 869#if __STDC__ 870 va_start(ap, fmt); 871#else 872 va_start(ap); 873#endif 874 if (dflag) { 875 if (fatal) 876 (void) fprintf(stderr, "rarpd: error: "); 877 else 878 (void) fprintf(stderr, "rarpd: warning: "); 879 (void) vfprintf(stderr, fmt, ap); 880 (void) fprintf(stderr, "\n"); 881 } 882 vsyslog(LOG_ERR, fmt, ap); 883 va_end(ap); 884 if (fatal) 885 exit(1); 886 /* NOTREACHED */ 887} 888 889void 890#if __STDC__ 891debug(const char *fmt,...) 892#else 893debug(fmt, va_alist) 894 char *fmt; 895va_dcl 896#endif 897{ 898 va_list ap; 899 900#if __STDC__ 901 va_start(ap, fmt); 902#else 903 va_start(ap); 904#endif 905 if (dflag) { 906 (void) fprintf(stderr, "rarpd: "); 907 (void) vfprintf(stderr, fmt, ap); 908 (void) fprintf(stderr, "\n"); 909 } 910 vsyslog(LOG_WARNING, fmt, ap); 911 va_end(ap); 912} 913