rarpd.c revision 1.35
1/* $NetBSD: rarpd.c,v 1.35 2000/02/07 01:15:52 nathanw 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 1.35 2000/02/07 01:15:52 nathanw Exp $"); 32#endif 33 34 35/* 36 * rarpd - Reverse ARP Daemon 37 * 38 * Usage: rarpd -a [-d|-f] [-l] 39 * rarpd [-d|-f] [-l] interface 40 */ 41 42#include <sys/param.h> 43#include <sys/file.h> 44#include <sys/time.h> 45#include <sys/socket.h> 46#include <sys/ioctl.h> 47 48#include <net/bpf.h> 49#include <net/if.h> 50#include <net/if_dl.h> 51#ifdef __NetBSD__ 52#include <net/if_ether.h> 53#endif 54#include <net/if_types.h> 55#include <netinet/in.h> 56#ifdef __NetBSD__ 57#include <netinet/if_inarp.h> 58#else 59#include <netinet/if_ether.h> 60#endif 61 62#include <arpa/inet.h> 63 64#include <errno.h> 65#include <dirent.h> 66#include <netdb.h> 67#include <stdio.h> 68#include <stdlib.h> 69#include <string.h> 70#include <syslog.h> 71#include <unistd.h> 72#include <util.h> 73 74#define FATAL 1 /* fatal error occurred */ 75#define NONFATAL 0 /* non fatal error occurred */ 76 77/* 78 * The structure for each interface. 79 */ 80struct if_info { 81 int ii_fd; /* BPF file descriptor */ 82 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 83 u_int32_t ii_ipaddr; /* IP address of this interface */ 84 u_int32_t ii_netmask; /* subnet or net mask */ 85 char *ii_name; /* interface name */ 86 struct if_info *ii_alias; 87 struct if_info *ii_next; 88}; 89/* 90 * The list of all interfaces that are being listened to. rarp_loop() 91 * "selects" on the descriptors in this list. 92 */ 93struct if_info *iflist; 94 95u_int32_t choose_ipaddr __P((u_int32_t **, u_int32_t, u_int32_t)); 96void debug __P((const char *,...)); 97void init_all __P((void)); 98void init_one __P((char *, u_int32_t)); 99u_int32_t ipaddrtonetmask __P((u_int32_t)); 100void lookup_eaddr __P((char *, u_char *)); 101void lookup_ipaddr __P((char *, u_int32_t *, u_int32_t *)); 102int main __P((int, char **)); 103void rarp_loop __P((void)); 104int rarp_open __P((char *)); 105void rarp_process __P((struct if_info *, u_char *)); 106void rarp_reply __P((struct if_info *, struct ether_header *, u_int32_t, 107 struct hostent *)); 108void rarperr __P((int, const char *,...)); 109 110#if defined(__NetBSD__) 111#include "mkarp.h" 112#else 113void update_arptab __P((u_char *, u_int32_t)); 114#endif 115 116void usage __P((void)); 117 118static int bpf_open __P((void)); 119static int rarp_check __P((u_char *, int)); 120 121#ifdef REQUIRE_TFTPBOOT 122int rarp_bootable __P((u_int32_t)); 123#endif 124 125int aflag = 0; /* listen on "all" interfaces */ 126int dflag = 0; /* print debugging messages */ 127int fflag = 0; /* don't fork */ 128int lflag = 0; /* log all replies */ 129 130int 131main(argc, argv) 132 int argc; 133 char **argv; 134{ 135 extern char *__progname; 136 137 int op; 138 char *ifname, *hostname; 139 140 /* All error reporting is done through syslogs. */ 141 openlog(__progname, LOG_PID, LOG_DAEMON); 142 143 opterr = 0; 144 while ((op = getopt(argc, argv, "adfl")) != -1) { 145 switch (op) { 146 case 'a': 147 ++aflag; 148 break; 149 150 case 'd': 151 ++dflag; 152 break; 153 154 case 'f': 155 ++fflag; 156 break; 157 158 case 'l': 159 ++lflag; 160 break; 161 162 default: 163 usage(); 164 /* NOTREACHED */ 165 } 166 } 167 ifname = argv[optind++]; 168 hostname = ifname ? argv[optind] : 0; 169 if ((aflag && ifname) || (!aflag && ifname == 0)) 170 usage(); 171 172 if (aflag) 173 init_all(); 174 else 175 init_one(ifname, INADDR_ANY); 176 177 if ((!fflag) && (!dflag)) { 178 if (daemon(0, 0)) 179 rarperr(FATAL, "daemon"); 180 pidfile(NULL); 181 } 182 rarp_loop(); 183 /* NOTREACHED */ 184 return (0); 185} 186 187/* 188 * Add 'ifname' to the interface list. Lookup its IP address and network 189 * mask and Ethernet address, and open a BPF file for it. 190 */ 191void 192init_one(ifname, ipaddr) 193 char *ifname; 194 u_int32_t ipaddr; 195{ 196 struct if_info *h; 197 struct if_info *p; 198 int fd; 199 200 for (h = iflist; h != NULL; h = h->ii_next) { 201 if (!strcmp(h->ii_name, ifname)) 202 break; 203 } 204 if (h == NULL) { 205 fd = rarp_open(ifname); 206 if (fd < 0) 207 return; 208 } else { 209 fd = h->ii_fd; 210 } 211 212 p = (struct if_info *)malloc(sizeof(*p)); 213 if (p == 0) { 214 rarperr(FATAL, "malloc: %s", strerror(errno)); 215 /* NOTREACHED */ 216 } 217 p->ii_name = strdup(ifname); 218 if (p->ii_name == 0) { 219 rarperr(FATAL, "malloc: %s", strerror(errno)); 220 /* NOTREACHED */ 221 } 222 if (h != NULL) { 223 p->ii_alias = h->ii_alias; 224 h->ii_alias = p; 225 } else { 226 p->ii_next = iflist; 227 iflist = p; 228 } 229 230 p->ii_fd = fd; 231 p->ii_ipaddr = ipaddr; 232 lookup_eaddr(ifname, p->ii_eaddr); 233 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 234} 235 236/* 237 * Initialize all "candidate" interfaces that are in the system 238 * configuration list. A "candidate" is up, not loopback and not 239 * point to point. 240 */ 241void 242init_all() 243{ 244 char inbuf[8192*2]; 245 struct ifconf ifc; 246 struct ifreq ifreq, ifrd, *ifr, *ifrp; 247 int fd; 248 int i, len; 249 250 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 251 rarperr(FATAL, "socket: %s", strerror(errno)); 252 /* NOTREACHED */ 253 } 254 255 ifc.ifc_len = sizeof(inbuf); 256 ifc.ifc_buf = inbuf; 257 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 258 ifc.ifc_len < sizeof(struct ifreq)) { 259 rarperr(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 260 /* NOTREACHED */ 261 } 262 ifr = &ifrd; 263 ifrp = ifc.ifc_req; 264 ifreq.ifr_name[0] = '\0'; 265 for (i = 0; i < ifc.ifc_len; 266 i += len, ifrp = (struct ifreq *)((caddr_t)ifrp + len)) { 267#define SIN(s) ((struct sockaddr_in *) (s)) 268 memcpy(&ifrd, ifrp, sizeof (ifrd)); 269 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 270 if (ifr->ifr_addr.sa_family != AF_INET) 271 continue; 272 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name)) 273 && SIN(&ifreq.ifr_addr)->sin_addr.s_addr == SIN(&ifr->ifr_addr)->sin_addr.s_addr) 274 continue; 275 ifreq = *ifr; 276 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 277 rarperr(FATAL, "init_all: SIOCGIFFLAGS: %s", 278 strerror(errno)); 279 /* NOTREACHED */ 280 } 281 if ((ifr->ifr_flags & 282 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 283 continue; 284 init_one(ifr->ifr_name, SIN(&ifreq.ifr_addr)->sin_addr.s_addr); 285#undef SIN 286 } 287 (void)close(fd); 288} 289 290void 291usage() 292{ 293 (void) fprintf(stderr, "usage: rarpd -a [-d|-f] [-l]\n"); 294 (void) fprintf(stderr, " rarpd [-d|-f] [-l] interface\n"); 295 exit(1); 296} 297 298static int 299bpf_open() 300{ 301 int fd; 302 int n = 0; 303 char device[sizeof "/dev/bpf000"]; 304 305 /* Go through all the minors and find one that isn't in use. */ 306 do { 307 (void)sprintf(device, "/dev/bpf%d", n++); 308 fd = open(device, O_RDWR); 309 } while (fd < 0 && errno == EBUSY); 310 311 if (fd < 0) { 312 rarperr(FATAL, "%s: %s", device, strerror(errno)); 313 /* NOTREACHED */ 314 } 315 return fd; 316} 317/* 318 * Open a BPF file and attach it to the interface named 'device'. 319 * Set immediate mode, and set a filter that accepts only RARP requests. 320 */ 321int 322rarp_open(device) 323 char *device; 324{ 325 int fd; 326 struct ifreq ifr; 327 u_int dlt; 328 int immediate; 329 330 static struct bpf_insn insns[] = { 331 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 332 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 333 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 334 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 335 BPF_STMT(BPF_RET | BPF_K, 336 sizeof(struct arphdr) + 337 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 338 sizeof(struct ether_header)), 339 BPF_STMT(BPF_RET | BPF_K, 0), 340 }; 341 static struct bpf_program filter = { 342 sizeof insns / sizeof(insns[0]), 343 insns 344 }; 345 346 fd = bpf_open(); 347 348 /* Set immediate mode so packets are processed as they arrive. */ 349 immediate = 1; 350 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 351 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 352 /* NOTREACHED */ 353 } 354 (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name - 1); 355 ifr.ifr_name[sizeof ifr.ifr_name - 1] = '\0'; 356 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 357 if (aflag) { /* for -a skip non-ethernet interfaces */ 358 close(fd); 359 return(-1); 360 } 361 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 362 /* NOTREACHED */ 363 } 364 /* Check that the data link layer is an Ethernet; this code won't work 365 * with anything else. */ 366 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 367 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 368 /* NOTREACHED */ 369 } 370 if (dlt != DLT_EN10MB) { 371 if (aflag) { /* for -a skip non-ethernet interfaces */ 372 close(fd); 373 return(-1); 374 } 375 rarperr(FATAL, "%s is not an ethernet", device); 376 /* NOTREACHED */ 377 } 378 /* Set filter program. */ 379 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 380 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 381 /* NOTREACHED */ 382 } 383 return fd; 384} 385/* 386 * Perform various sanity checks on the RARP request packet. Return 387 * false on failure and log the reason. 388 */ 389static int 390rarp_check(p, len) 391 u_char *p; 392 int len; 393{ 394 struct ether_header *ep = (struct ether_header *) p; 395#ifdef __NetBSD__ 396 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 397#else 398 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 399#endif 400 401 if (dflag) 402 fprintf(stderr, "got a packet\n"); 403 404 if (len < sizeof(*ep) + sizeof(*ap)) { 405 rarperr(NONFATAL, "truncated request"); 406 return 0; 407 } 408#ifdef __NetBSD__ 409 /* now that we know the fixed part of the ARP hdr is there: */ 410 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 411 rarperr(NONFATAL, "truncated request"); 412 return 0; 413 } 414#endif 415 /* XXX This test might be better off broken out... */ 416#ifdef __FreeBSD__ 417 /* BPF (incorrectly) returns this in host order. */ 418 if (ep->ether_type != ETHERTYPE_REVARP || 419#else 420 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 421#endif 422#ifdef __NetBSD__ 423 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 424 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 425 ntohs (ap->ar_pro) != ETHERTYPE_IP || 426 ap->ar_hln != 6 || ap->ar_pln != 4) { 427#else 428 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 429 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 430 ntohs (ap->arp_pro) != ETHERTYPE_IP || 431 ap->arp_hln != 6 || ap->arp_pln != 4) { 432#endif 433 rarperr(NONFATAL, "request fails sanity check"); 434 return 0; 435 } 436#ifdef __NetBSD__ 437 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 438#else 439 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 440#endif 441 rarperr(NONFATAL, "ether/arp sender address mismatch"); 442 return 0; 443 } 444#ifdef __NetBSD__ 445 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 446#else 447 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 448#endif 449 rarperr(NONFATAL, "ether/arp target address mismatch"); 450 return 0; 451 } 452 return 1; 453} 454 455/* 456 * Loop indefinitely listening for RARP requests on the 457 * interfaces in 'iflist'. 458 */ 459void 460rarp_loop() 461{ 462 u_char *buf, *bp, *ep; 463 int cc, fd; 464 fd_set fds, listeners; 465 int bufsize, maxfd = 0; 466 struct if_info *ii; 467 468 if (iflist == 0) { 469 rarperr(FATAL, "no interfaces"); 470 /* NOTREACHED */ 471 } 472 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 473 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 474 /* NOTREACHED */ 475 } 476 buf = (u_char *) malloc((unsigned) bufsize); 477 if (buf == 0) { 478 rarperr(FATAL, "malloc: %s", strerror(errno)); 479 /* NOTREACHED */ 480 } 481 /* 482 * Find the highest numbered file descriptor for select(). 483 * Initialize the set of descriptors to listen to. 484 */ 485 FD_ZERO(&fds); 486 for (ii = iflist; ii; ii = ii->ii_next) { 487 FD_SET(ii->ii_fd, &fds); 488 if (ii->ii_fd > maxfd) 489 maxfd = ii->ii_fd; 490 } 491 while (1) { 492 listeners = fds; 493 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 494 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 495 rarperr(FATAL, "select: %s", strerror(errno)); 496 /* NOTREACHED */ 497 } 498 for (ii = iflist; ii; ii = ii->ii_next) { 499 fd = ii->ii_fd; 500 if (!FD_ISSET(fd, &listeners)) 501 continue; 502 again: 503 cc = read(fd, (char *) buf, bufsize); 504 /* Don't choke when we get ptraced */ 505 if (cc < 0 && errno == EINTR) 506 goto again; 507 /* Due to a SunOS bug, after 2^31 bytes, the file 508 * offset overflows and read fails with EINVAL. The 509 * lseek() to 0 will fix things. */ 510 if (cc < 0) { 511 if (errno == EINVAL && 512 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 513 (void)lseek(fd, 0, 0); 514 goto again; 515 } 516 rarperr(FATAL, "read: %s", strerror(errno)); 517 /* NOTREACHED */ 518 } 519 /* Loop through the packet(s) */ 520#define bhp ((struct bpf_hdr *)bp) 521 bp = buf; 522 ep = bp + cc; 523 while (bp < ep) { 524 register int caplen, hdrlen; 525 526 caplen = bhp->bh_caplen; 527 hdrlen = bhp->bh_hdrlen; 528 if (rarp_check(bp + hdrlen, caplen)) 529 rarp_process(ii, bp + hdrlen); 530 bp += BPF_WORDALIGN(hdrlen + caplen); 531 } 532 } 533 } 534} 535 536#ifdef REQUIRE_TFTPBOOT 537 538#ifndef TFTP_DIR 539#define TFTP_DIR "/tftpboot" 540#endif 541 542/* 543 * True if this server can boot the host whose IP address is 'addr'. 544 * This check is made by looking in the tftp directory for the 545 * configuration file. 546 */ 547int 548rarp_bootable(addr) 549 u_int32_t addr; 550{ 551 register struct dirent *dent; 552 register DIR *d; 553 char ipname[9]; 554 static DIR *dd = 0; 555 556 (void)sprintf(ipname, "%08X", addr); 557 /* If directory is already open, rewind it. Otherwise, open it. */ 558 if (d = dd) 559 rewinddir(d); 560 else { 561 if (chdir(TFTP_DIR) == -1) { 562 rarperr(FATAL, "chdir: %s", strerror(errno)); 563 /* NOTREACHED */ 564 } 565 d = opendir("."); 566 if (d == 0) { 567 rarperr(FATAL, "opendir: %s", strerror(errno)); 568 /* NOTREACHED */ 569 } 570 dd = d; 571 } 572 while (dent = readdir(d)) 573 if (strncmp(dent->d_name, ipname, 8) == 0) 574 return 1; 575 return 0; 576} 577#endif /* REQUIRE_TFTPBOOT */ 578 579/* 580 * Given a list of IP addresses, 'alist', return the first address that 581 * is on network 'net'; 'netmask' is a mask indicating the network portion 582 * of the address. 583 */ 584u_int32_t 585choose_ipaddr(alist, net, netmask) 586 u_int32_t **alist; 587 u_int32_t net; 588 u_int32_t netmask; 589{ 590 591 for (; *alist; ++alist) { 592 if ((**alist & netmask) == net) 593 return **alist; 594 } 595 return 0; 596} 597/* 598 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 599 * already been checked for validity. The reply is overlaid on the request. 600 */ 601void 602rarp_process(ii, pkt) 603 struct if_info *ii; 604 u_char *pkt; 605{ 606 struct ether_header *ep; 607 struct hostent *hp; 608 u_int32_t target_ipaddr = 0; 609 char ename[MAXHOSTNAMELEN + 1]; 610 struct in_addr in; 611 612 ep = (struct ether_header *) pkt; 613 614 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 615 debug("no IP address for %s", 616 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 617 return; 618 } 619 ename[sizeof(ename)-1] = '\0'; 620 621 if ((hp = gethostbyname(ename)) == 0) { 622 debug("gethostbyname(%s) failed: %s", ename, 623 hstrerror(h_errno)); 624 return; 625 } 626 627 /* Choose correct address from list. */ 628 if (hp->h_addrtype != AF_INET) { 629 rarperr(FATAL, "cannot handle non IP addresses"); 630 /* NOTREACHED */ 631 } 632 for (;; ii = ii->ii_alias) { 633 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 634 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 635 if (target_ipaddr != 0) 636 break; 637 if (ii->ii_alias == NULL) 638 break; 639 } 640 641 if (target_ipaddr == 0) { 642 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 643 rarperr(NONFATAL, "cannot find %s on net %s", 644 ename, inet_ntoa(in)); 645 return; 646 } 647#ifdef REQUIRE_TFTPBOOT 648 if (rarp_bootable(htonl(target_ipaddr))) 649#endif 650 rarp_reply(ii, ep, target_ipaddr, hp); 651#ifdef REQUIRE_TFTPBOOT 652 else 653 debug("%08X not bootable", htonl(target_ipaddr)); 654#endif 655} 656/* 657 * Lookup the ethernet address of the interface attached to the BPF 658 * file descriptor 'fd'; return it in 'eaddr'. 659 */ 660void 661lookup_eaddr(ifname, eaddr) 662 char *ifname; 663 u_char *eaddr; 664{ 665 char inbuf[8192*2]; 666 struct ifconf ifc; 667 struct ifreq *ifr; 668 struct sockaddr_dl *sdl; 669 int fd; 670 int i, len; 671 672 /* We cannot use SIOCGIFADDR on the BPF descriptor. 673 We must instead get all the interfaces with SIOCGIFCONF 674 and find the right one. */ 675 676 /* Use datagram socket to get Ethernet address. */ 677 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 678 rarperr(FATAL, "socket: %s", strerror(errno)); 679 /* NOTREACHED */ 680 } 681 682 ifc.ifc_len = sizeof(inbuf); 683 ifc.ifc_buf = inbuf; 684 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 685 ifc.ifc_len < sizeof(struct ifreq)) { 686 rarperr(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 687 /* NOTREACHED */ 688 } 689 ifr = ifc.ifc_req; 690 for (i = 0; i < ifc.ifc_len; 691 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 692 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 693 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 694 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 695 sdl->sdl_alen != 6) 696 continue; 697 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 698 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 699 debug("%s: %x:%x:%x:%x:%x:%x", 700 ifr->ifr_name, eaddr[0], eaddr[1], 701 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 702 return; 703 } 704 } 705 706 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 707} 708/* 709 * Lookup the IP address and network mask of the interface named 'ifname'. 710 */ 711void 712lookup_ipaddr(ifname, addrp, netmaskp) 713 char *ifname; 714 u_int32_t *addrp; 715 u_int32_t *netmaskp; 716{ 717 int fd; 718 719 /* Use datagram socket to get IP address. */ 720 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 721 rarperr(FATAL, "socket: %s", strerror(errno)); 722 /* NOTREACHED */ 723 } 724 if (*addrp == INADDR_ANY) { 725 struct ifreq ifr; 726 memset(&ifr, 0, sizeof(ifr)); 727 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 728 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 729 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 730 /* NOTREACHED */ 731 } 732 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 733 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 734 perror("SIOCGIFNETMASK"); 735 exit(1); 736 } 737 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 738 } else { 739 struct ifaliasreq ifra; 740 memset(&ifra, 0, sizeof(ifra)); 741 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 742 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 743 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 744 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 745 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 746 /* NOTREACHED */ 747 } 748 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 749 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 750 } 751 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 752 * address class. */ 753 if (*netmaskp == 0) 754 *netmaskp = ipaddrtonetmask(*addrp); 755 756 (void)close(fd); 757} 758/* 759 * Poke the kernel arp tables with the ethernet/ip address combinataion 760 * given. When processing a reply, we must do this so that the booting 761 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 762 * address of the guy being booted (he cannot answer the ARP). 763 */ 764#ifndef __NetBSD__ 765void 766update_arptab(ep, ipaddr) 767 u_char *ep; 768 u_int32_t ipaddr; 769{ 770 struct arpreq request; 771 struct sockaddr_in *sin; 772 773 request.arp_flags = 0; 774 sin = (struct sockaddr_in *) & request.arp_pa; 775 sin->sin_family = AF_INET; 776 sin->sin_addr.s_addr = ipaddr; 777 request.arp_ha.sa_family = AF_UNSPEC; 778 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 779 because AF_UNSPEC is zero and the kernel assumes that a zero 780 sa_family means that the real sa_family value is in sa_len. */ 781 request.arp_ha.sa_len = 16; /* XXX */ 782 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 783 784#if 0 785 s = socket(AF_INET, SOCK_DGRAM, 0); 786 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 787 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 788 } 789 (void)close(s); 790#endif 791} 792#endif 793 794/* 795 * Build a reverse ARP packet and sent it out on the interface. 796 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 797 * on top of the request, then written to the network. 798 * 799 * RFC 903 defines the ether_arp fields as follows. The following comments 800 * are taken (more or less) straight from this document. 801 * 802 * ARPOP_REVREQUEST 803 * 804 * arp_sha is the hardware address of the sender of the packet. 805 * arp_spa is undefined. 806 * arp_tha is the 'target' hardware address. 807 * In the case where the sender wishes to determine his own 808 * protocol address, this, like arp_sha, will be the hardware 809 * address of the sender. 810 * arp_tpa is undefined. 811 * 812 * ARPOP_REVREPLY 813 * 814 * arp_sha is the hardware address of the responder (the sender of the 815 * reply packet). 816 * arp_spa is the protocol address of the responder (see the note below). 817 * arp_tha is the hardware address of the target, and should be the same as 818 * that which was given in the request. 819 * arp_tpa is the protocol address of the target, that is, the desired address. 820 * 821 * Note that the requirement that arp_spa be filled in with the responder's 822 * protocol is purely for convenience. For instance, if a system were to use 823 * both ARP and RARP, then the inclusion of the valid protocol-hardware 824 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 825 * ARP request. 826 */ 827void 828rarp_reply(ii, ep, ipaddr, hp) 829 struct if_info *ii; 830 struct ether_header *ep; 831 u_int32_t ipaddr; 832 struct hostent *hp; 833{ 834 int n; 835#ifdef __NetBSD__ 836 struct arphdr *ap = (struct arphdr *) (ep + 1); 837#else 838 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 839#endif 840 841 int len; 842 843#ifdef __NetBSD__ 844 (void)mkarp(ar_sha(ap), ipaddr); 845#else 846 update_arptab((u_char *) & ap->arp_sha, ipaddr); 847#endif 848 849 /* Build the rarp reply by modifying the rarp request in place. */ 850#ifdef __FreeBSD__ 851 /* BPF (incorrectly) wants this in host order. */ 852 ep->ether_type = ETHERTYPE_REVARP; 853#else 854 ep->ether_type = htons(ETHERTYPE_REVARP); 855#endif 856#ifdef __NetBSD__ 857 ap->ar_hrd = htons(ARPHRD_ETHER); 858 ap->ar_pro = htons(ETHERTYPE_IP); 859 ap->ar_op = htons(ARPOP_REVREPLY); 860 861 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 862 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 863 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 864 865 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 866 /* Target hardware is unchanged. */ 867 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 868 869 len = sizeof(*ep) + sizeof(*ap) + 870 2 * ap->ar_pln + 2 * ap->ar_hln; 871#else 872 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 873 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 874 ap->arp_op = htons(ARPOP_REVREPLY); 875 876 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 877 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 878 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 879 880 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 881 /* Target hardware is unchanged. */ 882 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 883 884 len = sizeof(*ep) + sizeof(*ap); 885#endif 886 887 if (lflag) 888 syslog(LOG_INFO, "%s asked; %s replied", hp->h_name, 889 ether_ntoa((struct ether_addr *)ar_tha(ap))); 890 n = write(ii->ii_fd, (char *) ep, len); 891 if (n != len) { 892 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 893 } 894} 895/* 896 * Get the netmask of an IP address. This routine is used if 897 * SIOCGIFNETMASK doesn't work. 898 */ 899u_int32_t 900ipaddrtonetmask(addr) 901 u_int32_t addr; 902{ 903 904 if (IN_CLASSA(addr)) 905 return IN_CLASSA_NET; 906 if (IN_CLASSB(addr)) 907 return IN_CLASSB_NET; 908 if (IN_CLASSC(addr)) 909 return IN_CLASSC_NET; 910 rarperr(FATAL, "unknown IP address class: %08X", addr); 911 /* NOTREACHED */ 912 return(-1); 913} 914 915#if __STDC__ 916#include <stdarg.h> 917#else 918#include <varargs.h> 919#endif 920 921void 922#if __STDC__ 923rarperr(int fatal, const char *fmt,...) 924#else 925rarperr(fmt, va_alist) 926 int fatal; 927 char *fmt; 928va_dcl 929#endif 930{ 931 va_list ap; 932 933#if __STDC__ 934 va_start(ap, fmt); 935#else 936 va_start(ap); 937#endif 938 if (dflag) { 939 if (fatal) 940 (void)fprintf(stderr, "rarpd: error: "); 941 else 942 (void)fprintf(stderr, "rarpd: warning: "); 943 (void)vfprintf(stderr, fmt, ap); 944 (void)fprintf(stderr, "\n"); 945 } 946 vsyslog(LOG_ERR, fmt, ap); 947 va_end(ap); 948 if (fatal) 949 exit(1); 950 /* NOTREACHED */ 951} 952 953void 954#if __STDC__ 955debug(const char *fmt,...) 956#else 957debug(fmt, va_alist) 958 char *fmt; 959va_dcl 960#endif 961{ 962 va_list ap; 963 964#if __STDC__ 965 va_start(ap, fmt); 966#else 967 va_start(ap); 968#endif 969 if (dflag) { 970 (void)fprintf(stderr, "rarpd: "); 971 (void)vfprintf(stderr, fmt, ap); 972 (void)fprintf(stderr, "\n"); 973 } 974 vsyslog(LOG_WARNING, fmt, ap); 975 va_end(ap); 976} 977