rarpd.c revision 1.33
1/* $NetBSD: rarpd.c,v 1.33 1999/06/06 02:58:23 thorpej 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 1.33 1999/06/06 02:58:23 thorpej 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/types.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, *ifr; 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 = ifc.ifc_req; 263 ifreq.ifr_name[0] = '\0'; 264 for (i = 0; i < ifc.ifc_len; 265 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 266#define SIN(s) ((struct sockaddr_in *) (s)) 267 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 268 if (ifr->ifr_addr.sa_family != AF_INET) 269 continue; 270 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name)) 271 && SIN(&ifreq.ifr_addr)->sin_addr.s_addr == SIN(&ifr->ifr_addr)->sin_addr.s_addr) 272 continue; 273 ifreq = *ifr; 274 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 275 rarperr(FATAL, "init_all: SIOCGIFFLAGS: %s", 276 strerror(errno)); 277 /* NOTREACHED */ 278 } 279 if ((ifr->ifr_flags & 280 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 281 continue; 282 init_one(ifr->ifr_name, SIN(&ifreq.ifr_addr)->sin_addr.s_addr); 283#undef SIN 284 } 285 (void)close(fd); 286} 287 288void 289usage() 290{ 291 (void) fprintf(stderr, "usage: rarpd -a [-d|-f] [-l]\n"); 292 (void) fprintf(stderr, " rarpd [-d|-f] [-l] interface\n"); 293 exit(1); 294} 295 296static int 297bpf_open() 298{ 299 int fd; 300 int n = 0; 301 char device[sizeof "/dev/bpf000"]; 302 303 /* Go through all the minors and find one that isn't in use. */ 304 do { 305 (void)sprintf(device, "/dev/bpf%d", n++); 306 fd = open(device, O_RDWR); 307 } while (fd < 0 && errno == EBUSY); 308 309 if (fd < 0) { 310 rarperr(FATAL, "%s: %s", device, strerror(errno)); 311 /* NOTREACHED */ 312 } 313 return fd; 314} 315/* 316 * Open a BPF file and attach it to the interface named 'device'. 317 * Set immediate mode, and set a filter that accepts only RARP requests. 318 */ 319int 320rarp_open(device) 321 char *device; 322{ 323 int fd; 324 struct ifreq ifr; 325 u_int dlt; 326 int immediate; 327 328 static struct bpf_insn insns[] = { 329 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 330 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 331 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 332 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 333 BPF_STMT(BPF_RET | BPF_K, 334 sizeof(struct arphdr) + 335 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 336 sizeof(struct ether_header)), 337 BPF_STMT(BPF_RET | BPF_K, 0), 338 }; 339 static struct bpf_program filter = { 340 sizeof insns / sizeof(insns[0]), 341 insns 342 }; 343 344 fd = bpf_open(); 345 346 /* Set immediate mode so packets are processed as they arrive. */ 347 immediate = 1; 348 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 349 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 350 /* NOTREACHED */ 351 } 352 (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name - 1); 353 ifr.ifr_name[sizeof ifr.ifr_name - 1] = '\0'; 354 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 355 if (aflag) { /* for -a skip non-ethernet interfaces */ 356 close(fd); 357 return(-1); 358 } 359 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 360 /* NOTREACHED */ 361 } 362 /* Check that the data link layer is an Ethernet; this code won't work 363 * with anything else. */ 364 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 365 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 366 /* NOTREACHED */ 367 } 368 if (dlt != DLT_EN10MB) { 369 if (aflag) { /* for -a skip non-ethernet interfaces */ 370 close(fd); 371 return(-1); 372 } 373 rarperr(FATAL, "%s is not an ethernet", device); 374 /* NOTREACHED */ 375 } 376 /* Set filter program. */ 377 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 378 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 379 /* NOTREACHED */ 380 } 381 return fd; 382} 383/* 384 * Perform various sanity checks on the RARP request packet. Return 385 * false on failure and log the reason. 386 */ 387static int 388rarp_check(p, len) 389 u_char *p; 390 int len; 391{ 392 struct ether_header *ep = (struct ether_header *) p; 393#ifdef __NetBSD__ 394 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 395#else 396 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 397#endif 398 399 if (dflag) 400 fprintf(stderr, "got a packet\n"); 401 402 if (len < sizeof(*ep) + sizeof(*ap)) { 403 rarperr(NONFATAL, "truncated request"); 404 return 0; 405 } 406#ifdef __NetBSD__ 407 /* now that we know the fixed part of the ARP hdr is there: */ 408 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 409 rarperr(NONFATAL, "truncated request"); 410 return 0; 411 } 412#endif 413 /* XXX This test might be better off broken out... */ 414#ifdef __FreeBSD__ 415 /* BPF (incorrectly) returns this in host order. */ 416 if (ep->ether_type != ETHERTYPE_REVARP || 417#else 418 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 419#endif 420#ifdef __NetBSD__ 421 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 422 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 423 ntohs (ap->ar_pro) != ETHERTYPE_IP || 424 ap->ar_hln != 6 || ap->ar_pln != 4) { 425#else 426 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 427 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 428 ntohs (ap->arp_pro) != ETHERTYPE_IP || 429 ap->arp_hln != 6 || ap->arp_pln != 4) { 430#endif 431 rarperr(NONFATAL, "request fails sanity check"); 432 return 0; 433 } 434#ifdef __NetBSD__ 435 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 436#else 437 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 438#endif 439 rarperr(NONFATAL, "ether/arp sender address mismatch"); 440 return 0; 441 } 442#ifdef __NetBSD__ 443 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 444#else 445 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 446#endif 447 rarperr(NONFATAL, "ether/arp target address mismatch"); 448 return 0; 449 } 450 return 1; 451} 452 453/* 454 * Loop indefinitely listening for RARP requests on the 455 * interfaces in 'iflist'. 456 */ 457void 458rarp_loop() 459{ 460 u_char *buf, *bp, *ep; 461 int cc, fd; 462 fd_set fds, listeners; 463 int bufsize, maxfd = 0; 464 struct if_info *ii; 465 466 if (iflist == 0) { 467 rarperr(FATAL, "no interfaces"); 468 /* NOTREACHED */ 469 } 470 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 471 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 472 /* NOTREACHED */ 473 } 474 buf = (u_char *) malloc((unsigned) bufsize); 475 if (buf == 0) { 476 rarperr(FATAL, "malloc: %s", strerror(errno)); 477 /* NOTREACHED */ 478 } 479 /* 480 * Find the highest numbered file descriptor for select(). 481 * Initialize the set of descriptors to listen to. 482 */ 483 FD_ZERO(&fds); 484 for (ii = iflist; ii; ii = ii->ii_next) { 485 FD_SET(ii->ii_fd, &fds); 486 if (ii->ii_fd > maxfd) 487 maxfd = ii->ii_fd; 488 } 489 while (1) { 490 listeners = fds; 491 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 492 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 493 rarperr(FATAL, "select: %s", strerror(errno)); 494 /* NOTREACHED */ 495 } 496 for (ii = iflist; ii; ii = ii->ii_next) { 497 fd = ii->ii_fd; 498 if (!FD_ISSET(fd, &listeners)) 499 continue; 500 again: 501 cc = read(fd, (char *) buf, bufsize); 502 /* Don't choke when we get ptraced */ 503 if (cc < 0 && errno == EINTR) 504 goto again; 505 /* Due to a SunOS bug, after 2^31 bytes, the file 506 * offset overflows and read fails with EINVAL. The 507 * lseek() to 0 will fix things. */ 508 if (cc < 0) { 509 if (errno == EINVAL && 510 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 511 (void)lseek(fd, 0, 0); 512 goto again; 513 } 514 rarperr(FATAL, "read: %s", strerror(errno)); 515 /* NOTREACHED */ 516 } 517 /* Loop through the packet(s) */ 518#define bhp ((struct bpf_hdr *)bp) 519 bp = buf; 520 ep = bp + cc; 521 while (bp < ep) { 522 register int caplen, hdrlen; 523 524 caplen = bhp->bh_caplen; 525 hdrlen = bhp->bh_hdrlen; 526 if (rarp_check(bp + hdrlen, caplen)) 527 rarp_process(ii, bp + hdrlen); 528 bp += BPF_WORDALIGN(hdrlen + caplen); 529 } 530 } 531 } 532} 533 534#ifdef REQUIRE_TFTPBOOT 535 536#ifndef TFTP_DIR 537#define TFTP_DIR "/tftpboot" 538#endif 539 540/* 541 * True if this server can boot the host whose IP address is 'addr'. 542 * This check is made by looking in the tftp directory for the 543 * configuration file. 544 */ 545int 546rarp_bootable(addr) 547 u_int32_t addr; 548{ 549 register struct dirent *dent; 550 register DIR *d; 551 char ipname[9]; 552 static DIR *dd = 0; 553 554 (void)sprintf(ipname, "%08X", addr); 555 /* If directory is already open, rewind it. Otherwise, open it. */ 556 if (d = dd) 557 rewinddir(d); 558 else { 559 if (chdir(TFTP_DIR) == -1) { 560 rarperr(FATAL, "chdir: %s", strerror(errno)); 561 /* NOTREACHED */ 562 } 563 d = opendir("."); 564 if (d == 0) { 565 rarperr(FATAL, "opendir: %s", strerror(errno)); 566 /* NOTREACHED */ 567 } 568 dd = d; 569 } 570 while (dent = readdir(d)) 571 if (strncmp(dent->d_name, ipname, 8) == 0) 572 return 1; 573 return 0; 574} 575#endif /* REQUIRE_TFTPBOOT */ 576 577/* 578 * Given a list of IP addresses, 'alist', return the first address that 579 * is on network 'net'; 'netmask' is a mask indicating the network portion 580 * of the address. 581 */ 582u_int32_t 583choose_ipaddr(alist, net, netmask) 584 u_int32_t **alist; 585 u_int32_t net; 586 u_int32_t netmask; 587{ 588 589 for (; *alist; ++alist) { 590 if ((**alist & netmask) == net) 591 return **alist; 592 } 593 return 0; 594} 595/* 596 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 597 * already been checked for validity. The reply is overlaid on the request. 598 */ 599void 600rarp_process(ii, pkt) 601 struct if_info *ii; 602 u_char *pkt; 603{ 604 struct ether_header *ep; 605 struct hostent *hp; 606 u_int32_t target_ipaddr = 0; 607 char ename[MAXHOSTNAMELEN + 1]; 608 struct in_addr in; 609 610 ep = (struct ether_header *) pkt; 611 612 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 613 debug("no IP address for %s", 614 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 615 return; 616 } 617 ename[sizeof(ename)-1] = '\0'; 618 619 if ((hp = gethostbyname(ename)) == 0) { 620 debug("gethostbyname(%s) failed: %s", ename, 621 hstrerror(h_errno)); 622 return; 623 } 624 625 /* Choose correct address from list. */ 626 if (hp->h_addrtype != AF_INET) { 627 rarperr(FATAL, "cannot handle non IP addresses"); 628 /* NOTREACHED */ 629 } 630 for (;; ii = ii->ii_alias) { 631 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 632 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 633 if (target_ipaddr != 0) 634 break; 635 if (ii->ii_alias == NULL) 636 break; 637 } 638 639 if (target_ipaddr == 0) { 640 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 641 rarperr(NONFATAL, "cannot find %s on net %s", 642 ename, inet_ntoa(in)); 643 return; 644 } 645#ifdef REQUIRE_TFTPBOOT 646 if (rarp_bootable(htonl(target_ipaddr))) 647#endif 648 rarp_reply(ii, ep, target_ipaddr, hp); 649#ifdef REQUIRE_TFTPBOOT 650 else 651 debug("%08X not bootable", htonl(target_ipaddr)); 652#endif 653} 654/* 655 * Lookup the ethernet address of the interface attached to the BPF 656 * file descriptor 'fd'; return it in 'eaddr'. 657 */ 658void 659lookup_eaddr(ifname, eaddr) 660 char *ifname; 661 u_char *eaddr; 662{ 663 char inbuf[8192*2]; 664 struct ifconf ifc; 665 struct ifreq *ifr; 666 struct sockaddr_dl *sdl; 667 int fd; 668 int i, len; 669 670 /* We cannot use SIOCGIFADDR on the BPF descriptor. 671 We must instead get all the interfaces with SIOCGIFCONF 672 and find the right one. */ 673 674 /* Use datagram socket to get Ethernet address. */ 675 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 676 rarperr(FATAL, "socket: %s", strerror(errno)); 677 /* NOTREACHED */ 678 } 679 680 ifc.ifc_len = sizeof(inbuf); 681 ifc.ifc_buf = inbuf; 682 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 683 ifc.ifc_len < sizeof(struct ifreq)) { 684 rarperr(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 685 /* NOTREACHED */ 686 } 687 ifr = ifc.ifc_req; 688 for (i = 0; i < ifc.ifc_len; 689 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 690 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 691 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 692 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 693 sdl->sdl_alen != 6) 694 continue; 695 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 696 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 697 debug("%s: %x:%x:%x:%x:%x:%x", 698 ifr->ifr_name, eaddr[0], eaddr[1], 699 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 700 return; 701 } 702 } 703 704 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 705} 706/* 707 * Lookup the IP address and network mask of the interface named 'ifname'. 708 */ 709void 710lookup_ipaddr(ifname, addrp, netmaskp) 711 char *ifname; 712 u_int32_t *addrp; 713 u_int32_t *netmaskp; 714{ 715 int fd; 716 717 /* Use datagram socket to get IP address. */ 718 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 719 rarperr(FATAL, "socket: %s", strerror(errno)); 720 /* NOTREACHED */ 721 } 722 if (*addrp == INADDR_ANY) { 723 struct ifreq ifr; 724 memset(&ifr, 0, sizeof(ifr)); 725 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 726 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 727 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 728 /* NOTREACHED */ 729 } 730 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 731 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 732 perror("SIOCGIFNETMASK"); 733 exit(1); 734 } 735 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 736 } else { 737 struct ifaliasreq ifra; 738 memset(&ifra, 0, sizeof(ifra)); 739 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 740 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 741 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 742 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 743 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 744 /* NOTREACHED */ 745 } 746 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 747 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 748 } 749 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 750 * address class. */ 751 if (*netmaskp == 0) 752 *netmaskp = ipaddrtonetmask(*addrp); 753 754 (void)close(fd); 755} 756/* 757 * Poke the kernel arp tables with the ethernet/ip address combinataion 758 * given. When processing a reply, we must do this so that the booting 759 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 760 * address of the guy being booted (he cannot answer the ARP). 761 */ 762#ifndef __NetBSD__ 763void 764update_arptab(ep, ipaddr) 765 u_char *ep; 766 u_int32_t ipaddr; 767{ 768 struct arpreq request; 769 struct sockaddr_in *sin; 770 771 request.arp_flags = 0; 772 sin = (struct sockaddr_in *) & request.arp_pa; 773 sin->sin_family = AF_INET; 774 sin->sin_addr.s_addr = ipaddr; 775 request.arp_ha.sa_family = AF_UNSPEC; 776 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 777 because AF_UNSPEC is zero and the kernel assumes that a zero 778 sa_family means that the real sa_family value is in sa_len. */ 779 request.arp_ha.sa_len = 16; /* XXX */ 780 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 781 782#if 0 783 s = socket(AF_INET, SOCK_DGRAM, 0); 784 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 785 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 786 } 787 (void)close(s); 788#endif 789} 790#endif 791 792/* 793 * Build a reverse ARP packet and sent it out on the interface. 794 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 795 * on top of the request, then written to the network. 796 * 797 * RFC 903 defines the ether_arp fields as follows. The following comments 798 * are taken (more or less) straight from this document. 799 * 800 * ARPOP_REVREQUEST 801 * 802 * arp_sha is the hardware address of the sender of the packet. 803 * arp_spa is undefined. 804 * arp_tha is the 'target' hardware address. 805 * In the case where the sender wishes to determine his own 806 * protocol address, this, like arp_sha, will be the hardware 807 * address of the sender. 808 * arp_tpa is undefined. 809 * 810 * ARPOP_REVREPLY 811 * 812 * arp_sha is the hardware address of the responder (the sender of the 813 * reply packet). 814 * arp_spa is the protocol address of the responder (see the note below). 815 * arp_tha is the hardware address of the target, and should be the same as 816 * that which was given in the request. 817 * arp_tpa is the protocol address of the target, that is, the desired address. 818 * 819 * Note that the requirement that arp_spa be filled in with the responder's 820 * protocol is purely for convenience. For instance, if a system were to use 821 * both ARP and RARP, then the inclusion of the valid protocol-hardware 822 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 823 * ARP request. 824 */ 825void 826rarp_reply(ii, ep, ipaddr, hp) 827 struct if_info *ii; 828 struct ether_header *ep; 829 u_int32_t ipaddr; 830 struct hostent *hp; 831{ 832 int n; 833#ifdef __NetBSD__ 834 struct arphdr *ap = (struct arphdr *) (ep + 1); 835#else 836 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 837#endif 838 839 int len; 840 841#ifdef __NetBSD__ 842 (void)mkarp(ar_sha(ap), ipaddr); 843#else 844 update_arptab((u_char *) & ap->arp_sha, ipaddr); 845#endif 846 847 /* Build the rarp reply by modifying the rarp request in place. */ 848#ifdef __FreeBSD__ 849 /* BPF (incorrectly) wants this in host order. */ 850 ep->ether_type = ETHERTYPE_REVARP; 851#else 852 ep->ether_type = htons(ETHERTYPE_REVARP); 853#endif 854#ifdef __NetBSD__ 855 ap->ar_hrd = htons(ARPHRD_ETHER); 856 ap->ar_pro = htons(ETHERTYPE_IP); 857 ap->ar_op = htons(ARPOP_REVREPLY); 858 859 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 860 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 861 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 862 863 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 864 /* Target hardware is unchanged. */ 865 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 866 867 len = sizeof(*ep) + sizeof(*ap) + 868 2 * ap->ar_pln + 2 * ap->ar_hln; 869#else 870 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 871 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 872 ap->arp_op = htons(ARPOP_REVREPLY); 873 874 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 875 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 876 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 877 878 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 879 /* Target hardware is unchanged. */ 880 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 881 882 len = sizeof(*ep) + sizeof(*ap); 883#endif 884 885 if (lflag) 886 syslog(LOG_INFO, "%s asked; %s replied", hp->h_name, 887 ether_ntoa((struct ether_addr *)ar_tha(ap))); 888 n = write(ii->ii_fd, (char *) ep, len); 889 if (n != len) { 890 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 891 } 892} 893/* 894 * Get the netmask of an IP address. This routine is used if 895 * SIOCGIFNETMASK doesn't work. 896 */ 897u_int32_t 898ipaddrtonetmask(addr) 899 u_int32_t addr; 900{ 901 902 if (IN_CLASSA(addr)) 903 return IN_CLASSA_NET; 904 if (IN_CLASSB(addr)) 905 return IN_CLASSB_NET; 906 if (IN_CLASSC(addr)) 907 return IN_CLASSC_NET; 908 rarperr(FATAL, "unknown IP address class: %08X", addr); 909 /* NOTREACHED */ 910 return(-1); 911} 912 913#if __STDC__ 914#include <stdarg.h> 915#else 916#include <varargs.h> 917#endif 918 919void 920#if __STDC__ 921rarperr(int fatal, const char *fmt,...) 922#else 923rarperr(fmt, va_alist) 924 int fatal; 925 char *fmt; 926va_dcl 927#endif 928{ 929 va_list ap; 930 931#if __STDC__ 932 va_start(ap, fmt); 933#else 934 va_start(ap); 935#endif 936 if (dflag) { 937 if (fatal) 938 (void)fprintf(stderr, "rarpd: error: "); 939 else 940 (void)fprintf(stderr, "rarpd: warning: "); 941 (void)vfprintf(stderr, fmt, ap); 942 (void)fprintf(stderr, "\n"); 943 } 944 vsyslog(LOG_ERR, fmt, ap); 945 va_end(ap); 946 if (fatal) 947 exit(1); 948 /* NOTREACHED */ 949} 950 951void 952#if __STDC__ 953debug(const char *fmt,...) 954#else 955debug(fmt, va_alist) 956 char *fmt; 957va_dcl 958#endif 959{ 960 va_list ap; 961 962#if __STDC__ 963 va_start(ap, fmt); 964#else 965 va_start(ap); 966#endif 967 if (dflag) { 968 (void)fprintf(stderr, "rarpd: "); 969 (void)vfprintf(stderr, fmt, ap); 970 (void)fprintf(stderr, "\n"); 971 } 972 vsyslog(LOG_WARNING, fmt, ap); 973 va_end(ap); 974} 975