rarpd.c revision 1.40
1 /* $NetBSD: rarpd.c,v 1.40 2000/11/20 14:59:30 is 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 1.40 2000/11/20 14:59:30 is 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 #ifdef HAVE_IFADDRS_H 74 #include <ifaddrs.h> 75 #endif 76 77 #define FATAL 1 /* fatal error occurred */ 78 #define NONFATAL 0 /* non fatal error occurred */ 79 80 /* 81 * The structure for each interface. 82 */ 83 struct if_info { 84 int ii_fd; /* BPF file descriptor */ 85 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 86 u_int32_t ii_ipaddr; /* IP address of this interface */ 87 u_int32_t ii_netmask; /* subnet or net mask */ 88 char *ii_name; /* interface name */ 89 struct if_info *ii_alias; 90 struct if_info *ii_next; 91 }; 92 /* 93 * The list of all interfaces that are being listened to. rarp_loop() 94 * "selects" on the descriptors in this list. 95 */ 96 struct if_info *iflist; 97 98 u_int32_t choose_ipaddr __P((u_int32_t **, u_int32_t, u_int32_t)); 99 void debug __P((const char *,...)) 100 __attribute__((__format__(__printf__, 1, 2))); 101 void init_all __P((void)); 102 void init_one __P((char *, u_int32_t)); 103 u_int32_t ipaddrtonetmask __P((u_int32_t)); 104 void lookup_eaddr __P((char *, u_char *)); 105 void lookup_ipaddr __P((char *, u_int32_t *, u_int32_t *)); 106 int main __P((int, char **)); 107 void rarp_loop __P((void)); 108 int rarp_open __P((char *)); 109 void rarp_process __P((struct if_info *, u_char *)); 110 void rarp_reply __P((struct if_info *, struct ether_header *, u_int32_t, 111 struct hostent *)); 112 void rarperr __P((int, const char *,...)) 113 __attribute__((__format__(__printf__, 2, 3))); 114 115 #if defined(__NetBSD__) 116 #include "mkarp.h" 117 #else 118 void update_arptab __P((u_char *, u_int32_t)); 119 #endif 120 121 void usage __P((void)); 122 123 static int bpf_open __P((void)); 124 static int rarp_check __P((u_char *, int)); 125 126 #ifdef REQUIRE_TFTPBOOT 127 int rarp_bootable __P((u_int32_t)); 128 #endif 129 130 int aflag = 0; /* listen on "all" interfaces */ 131 int dflag = 0; /* print debugging messages */ 132 int fflag = 0; /* don't fork */ 133 int lflag = 0; /* log all replies */ 134 135 int 136 main(argc, argv) 137 int argc; 138 char **argv; 139 { 140 extern char *__progname; 141 142 int op; 143 char *ifname, *hostname; 144 145 /* All error reporting is done through syslogs. */ 146 openlog(__progname, LOG_PID, LOG_DAEMON); 147 148 opterr = 0; 149 while ((op = getopt(argc, argv, "adfl")) != -1) { 150 switch (op) { 151 case 'a': 152 ++aflag; 153 break; 154 155 case 'd': 156 ++dflag; 157 break; 158 159 case 'f': 160 ++fflag; 161 break; 162 163 case 'l': 164 ++lflag; 165 break; 166 167 default: 168 usage(); 169 /* NOTREACHED */ 170 } 171 } 172 ifname = argv[optind++]; 173 hostname = ifname ? argv[optind] : 0; 174 if ((aflag && ifname) || (!aflag && ifname == 0)) 175 usage(); 176 177 if (aflag) 178 init_all(); 179 else 180 init_one(ifname, INADDR_ANY); 181 182 if ((!fflag) && (!dflag)) { 183 if (daemon(0, 0)) 184 rarperr(FATAL, "daemon"); 185 pidfile(NULL); 186 } 187 rarp_loop(); 188 /* NOTREACHED */ 189 return (0); 190 } 191 192 /* 193 * Add 'ifname' to the interface list. Lookup its IP address and network 194 * mask and Ethernet address, and open a BPF file for it. 195 */ 196 void 197 init_one(ifname, ipaddr) 198 char *ifname; 199 u_int32_t ipaddr; 200 { 201 struct if_info *h; 202 struct if_info *p; 203 int fd; 204 205 for (h = iflist; h != NULL; h = h->ii_next) { 206 if (!strcmp(h->ii_name, ifname)) 207 break; 208 } 209 if (h == NULL) { 210 fd = rarp_open(ifname); 211 if (fd < 0) 212 return; 213 } else { 214 fd = h->ii_fd; 215 } 216 217 p = (struct if_info *)malloc(sizeof(*p)); 218 if (p == 0) { 219 rarperr(FATAL, "malloc: %s", strerror(errno)); 220 /* NOTREACHED */ 221 } 222 p->ii_name = strdup(ifname); 223 if (p->ii_name == 0) { 224 rarperr(FATAL, "malloc: %s", strerror(errno)); 225 /* NOTREACHED */ 226 } 227 if (h != NULL) { 228 p->ii_alias = h->ii_alias; 229 h->ii_alias = p; 230 } else { 231 p->ii_next = iflist; 232 iflist = p; 233 } 234 235 p->ii_fd = fd; 236 p->ii_ipaddr = ipaddr; 237 lookup_eaddr(ifname, p->ii_eaddr); 238 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 239 } 240 241 /* 242 * Initialize all "candidate" interfaces that are in the system 243 * configuration list. A "candidate" is up, not loopback and not 244 * point to point. 245 */ 246 void 247 init_all() 248 { 249 #ifdef HAVE_IFADDRS_H 250 struct ifaddrs *ifap, *ifa, *p; 251 252 if (getifaddrs(&ifap) != 0) { 253 rarperr(FATAL, "getifaddrs: %s", strerror(errno)); 254 /* NOTREACHED */ 255 } 256 257 p = NULL; 258 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 259 #define SIN(s) ((struct sockaddr_in *) (s)) 260 if (ifa->ifa_addr->sa_family != AF_INET) 261 continue; 262 if (p && !strcmp(p->ifa_name, ifa->ifa_name) && 263 SIN(p->ifa_addr)->sin_addr.s_addr == SIN(ifa->ifa_addr)->sin_addr.s_addr) 264 continue; 265 p = ifa; 266 if ((ifa->ifa_flags & 267 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 268 continue; 269 init_one(ifa->ifa_name, SIN(ifa->ifa_addr)->sin_addr.s_addr); 270 #undef SIN 271 } 272 freeifaddrs(ifap); 273 #else 274 char inbuf[8192*2]; 275 struct ifconf ifc; 276 struct ifreq ifreq, ifrd, *ifr, *ifrp; 277 int fd; 278 int i, len; 279 280 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 281 rarperr(FATAL, "socket: %s", strerror(errno)); 282 /* NOTREACHED */ 283 } 284 285 ifc.ifc_len = sizeof(inbuf); 286 ifc.ifc_buf = inbuf; 287 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 288 ifc.ifc_len < sizeof(struct ifreq)) { 289 rarperr(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 290 /* NOTREACHED */ 291 } 292 ifr = &ifrd; 293 ifrp = ifc.ifc_req; 294 ifreq.ifr_name[0] = '\0'; 295 for (i = 0; i < ifc.ifc_len; 296 i += len, ifrp = (struct ifreq *)((caddr_t)ifrp + len)) { 297 #define SIN(s) ((struct sockaddr_in *) (s)) 298 memcpy(&ifrd, ifrp, sizeof (ifrd)); 299 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 300 if (ifr->ifr_addr.sa_family != AF_INET) 301 continue; 302 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name)) 303 && SIN(&ifreq.ifr_addr)->sin_addr.s_addr == SIN(&ifr->ifr_addr)->sin_addr.s_addr) 304 continue; 305 ifreq = *ifr; 306 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 307 rarperr(FATAL, "init_all: SIOCGIFFLAGS: %s", 308 strerror(errno)); 309 /* NOTREACHED */ 310 } 311 if ((ifr->ifr_flags & 312 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 313 continue; 314 init_one(ifr->ifr_name, SIN(&ifreq.ifr_addr)->sin_addr.s_addr); 315 #undef SIN 316 } 317 (void)close(fd); 318 #endif 319 } 320 321 void 322 usage() 323 { 324 (void) fprintf(stderr, "usage: rarpd -a [-d|-f] [-l]\n"); 325 (void) fprintf(stderr, " rarpd [-d|-f] [-l] interface\n"); 326 exit(1); 327 } 328 329 static int 330 bpf_open() 331 { 332 int fd; 333 int n = 0; 334 char device[sizeof "/dev/bpf000"]; 335 336 /* Go through all the minors and find one that isn't in use. */ 337 do { 338 (void)sprintf(device, "/dev/bpf%d", n++); 339 fd = open(device, O_RDWR); 340 } while (fd < 0 && errno == EBUSY); 341 342 if (fd < 0) { 343 rarperr(FATAL, "%s: %s", device, strerror(errno)); 344 /* NOTREACHED */ 345 } 346 return fd; 347 } 348 /* 349 * Open a BPF file and attach it to the interface named 'device'. 350 * Set immediate mode, and set a filter that accepts only RARP requests. 351 */ 352 int 353 rarp_open(device) 354 char *device; 355 { 356 int fd; 357 struct ifreq ifr; 358 u_int dlt; 359 int immediate; 360 361 static struct bpf_insn insns[] = { 362 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 363 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 364 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 365 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 366 BPF_STMT(BPF_RET | BPF_K, 367 sizeof(struct arphdr) + 368 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 369 sizeof(struct ether_header)), 370 BPF_STMT(BPF_RET | BPF_K, 0), 371 }; 372 static struct bpf_program filter = { 373 sizeof insns / sizeof(insns[0]), 374 insns 375 }; 376 377 fd = bpf_open(); 378 379 /* Set immediate mode so packets are processed as they arrive. */ 380 immediate = 1; 381 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 382 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 383 /* NOTREACHED */ 384 } 385 (void)strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name - 1); 386 ifr.ifr_name[sizeof ifr.ifr_name - 1] = '\0'; 387 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 388 if (aflag) { /* for -a skip non-ethernet interfaces */ 389 close(fd); 390 return(-1); 391 } 392 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 393 /* NOTREACHED */ 394 } 395 /* Check that the data link layer is an Ethernet; this code won't work 396 * with anything else. */ 397 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 398 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 399 /* NOTREACHED */ 400 } 401 if (dlt != DLT_EN10MB) { 402 if (aflag) { /* for -a skip non-ethernet interfaces */ 403 close(fd); 404 return(-1); 405 } 406 rarperr(FATAL, "%s is not an ethernet", device); 407 /* NOTREACHED */ 408 } 409 /* Set filter program. */ 410 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 411 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 412 /* NOTREACHED */ 413 } 414 return fd; 415 } 416 /* 417 * Perform various sanity checks on the RARP request packet. Return 418 * false on failure and log the reason. 419 */ 420 static int 421 rarp_check(p, len) 422 u_char *p; 423 int len; 424 { 425 struct ether_header *ep = (struct ether_header *) p; 426 #ifdef __NetBSD__ 427 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 428 #else 429 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 430 #endif 431 432 if (len < sizeof(*ep) + sizeof(*ap)) { 433 rarperr(NONFATAL, "truncated request"); 434 return 0; 435 } 436 #ifdef __NetBSD__ 437 /* now that we know the fixed part of the ARP hdr is there: */ 438 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 439 rarperr(NONFATAL, "truncated request"); 440 return 0; 441 } 442 #endif 443 /* XXX This test might be better off broken out... */ 444 #ifdef __FreeBSD__ 445 /* BPF (incorrectly) returns this in host order. */ 446 if (ep->ether_type != ETHERTYPE_REVARP || 447 #else 448 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 449 #endif 450 #ifdef __NetBSD__ 451 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 452 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 453 ntohs (ap->ar_pro) != ETHERTYPE_IP || 454 ap->ar_hln != 6 || ap->ar_pln != 4) { 455 #else 456 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 457 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 458 ntohs (ap->arp_pro) != ETHERTYPE_IP || 459 ap->arp_hln != 6 || ap->arp_pln != 4) { 460 #endif 461 rarperr(NONFATAL, "request fails sanity check"); 462 return 0; 463 } 464 #ifdef __NetBSD__ 465 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 466 #else 467 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 468 #endif 469 rarperr(NONFATAL, "ether/arp sender address mismatch"); 470 return 0; 471 } 472 #ifdef __NetBSD__ 473 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 474 #else 475 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 476 #endif 477 rarperr(NONFATAL, "ether/arp target address mismatch"); 478 return 0; 479 } 480 return 1; 481 } 482 483 /* 484 * Loop indefinitely listening for RARP requests on the 485 * interfaces in 'iflist'. 486 */ 487 void 488 rarp_loop() 489 { 490 u_char *buf, *bp, *ep; 491 int cc, fd; 492 fd_set fds, listeners; 493 int bufsize, maxfd = 0; 494 struct if_info *ii; 495 496 if (iflist == 0) { 497 rarperr(FATAL, "no interfaces"); 498 /* NOTREACHED */ 499 } 500 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 501 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 502 /* NOTREACHED */ 503 } 504 buf = (u_char *) malloc((unsigned) bufsize); 505 if (buf == 0) { 506 rarperr(FATAL, "malloc: %s", strerror(errno)); 507 /* NOTREACHED */ 508 } 509 /* 510 * Find the highest numbered file descriptor for select(). 511 * Initialize the set of descriptors to listen to. 512 */ 513 FD_ZERO(&fds); 514 for (ii = iflist; ii; ii = ii->ii_next) { 515 FD_SET(ii->ii_fd, &fds); 516 if (ii->ii_fd > maxfd) 517 maxfd = ii->ii_fd; 518 } 519 while (1) { 520 listeners = fds; 521 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 522 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 523 rarperr(FATAL, "select: %s", strerror(errno)); 524 /* NOTREACHED */ 525 } 526 for (ii = iflist; ii; ii = ii->ii_next) { 527 fd = ii->ii_fd; 528 if (!FD_ISSET(fd, &listeners)) 529 continue; 530 again: 531 cc = read(fd, (char *) buf, bufsize); 532 /* Don't choke when we get ptraced */ 533 if (cc < 0 && errno == EINTR) 534 goto again; 535 /* Due to a SunOS bug, after 2^31 bytes, the file 536 * offset overflows and read fails with EINVAL. The 537 * lseek() to 0 will fix things. */ 538 if (cc < 0) { 539 if (errno == EINVAL && 540 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 541 (void)lseek(fd, 0, 0); 542 goto again; 543 } 544 rarperr(FATAL, "read: %s", strerror(errno)); 545 /* NOTREACHED */ 546 } 547 /* Loop through the packet(s) */ 548 #define bhp ((struct bpf_hdr *)bp) 549 bp = buf; 550 ep = bp + cc; 551 while (bp < ep) { 552 register int caplen, hdrlen; 553 554 caplen = bhp->bh_caplen; 555 hdrlen = bhp->bh_hdrlen; 556 debug("received packet on %s", ii->ii_name); 557 558 if (rarp_check(bp + hdrlen, caplen)) 559 rarp_process(ii, bp + hdrlen); 560 bp += BPF_WORDALIGN(hdrlen + caplen); 561 } 562 } 563 } 564 } 565 566 #ifdef REQUIRE_TFTPBOOT 567 568 #ifndef TFTP_DIR 569 #define TFTP_DIR "/tftpboot" 570 #endif 571 572 /* 573 * True if this server can boot the host whose IP address is 'addr'. 574 * This check is made by looking in the tftp directory for the 575 * configuration file. 576 */ 577 int 578 rarp_bootable(addr) 579 u_int32_t addr; 580 { 581 register struct dirent *dent; 582 register DIR *d; 583 char ipname[9]; 584 static DIR *dd = 0; 585 586 (void)sprintf(ipname, "%08X", addr); 587 /* If directory is already open, rewind it. Otherwise, open it. */ 588 if (d = dd) 589 rewinddir(d); 590 else { 591 if (chdir(TFTP_DIR) == -1) { 592 rarperr(FATAL, "chdir: %s", strerror(errno)); 593 /* NOTREACHED */ 594 } 595 d = opendir("."); 596 if (d == 0) { 597 rarperr(FATAL, "opendir: %s", strerror(errno)); 598 /* NOTREACHED */ 599 } 600 dd = d; 601 } 602 while (dent = readdir(d)) 603 if (strncmp(dent->d_name, ipname, 8) == 0) 604 return 1; 605 return 0; 606 } 607 #endif /* REQUIRE_TFTPBOOT */ 608 609 /* 610 * Given a list of IP addresses, 'alist', return the first address that 611 * is on network 'net'; 'netmask' is a mask indicating the network portion 612 * of the address. 613 */ 614 u_int32_t 615 choose_ipaddr(alist, net, netmask) 616 u_int32_t **alist; 617 u_int32_t net; 618 u_int32_t netmask; 619 { 620 621 for (; *alist; ++alist) { 622 if ((**alist & netmask) == net) 623 return **alist; 624 } 625 return 0; 626 } 627 /* 628 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 629 * already been checked for validity. The reply is overlaid on the request. 630 */ 631 void 632 rarp_process(ii, pkt) 633 struct if_info *ii; 634 u_char *pkt; 635 { 636 struct ether_header *ep; 637 struct hostent *hp; 638 u_int32_t target_ipaddr = 0; 639 char ename[MAXHOSTNAMELEN + 1]; 640 struct in_addr in; 641 642 ep = (struct ether_header *) pkt; 643 644 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 645 debug("no IP address for %s", 646 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 647 return; 648 } 649 ename[sizeof(ename)-1] = '\0'; 650 651 if ((hp = gethostbyname(ename)) == 0) { 652 debug("gethostbyname(%s) failed: %s", ename, 653 hstrerror(h_errno)); 654 return; 655 } 656 657 /* Choose correct address from list. */ 658 if (hp->h_addrtype != AF_INET) { 659 rarperr(FATAL, "cannot handle non IP addresses"); 660 /* NOTREACHED */ 661 } 662 for (;; ii = ii->ii_alias) { 663 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 664 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 665 if (target_ipaddr != 0) 666 break; 667 if (ii->ii_alias == NULL) 668 break; 669 } 670 671 if (target_ipaddr == 0) { 672 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 673 rarperr(NONFATAL, "cannot find %s on net %s", 674 ename, inet_ntoa(in)); 675 return; 676 } 677 #ifdef REQUIRE_TFTPBOOT 678 if (rarp_bootable(htonl(target_ipaddr))) 679 #endif 680 rarp_reply(ii, ep, target_ipaddr, hp); 681 #ifdef REQUIRE_TFTPBOOT 682 else 683 debug("%08X not bootable", htonl(target_ipaddr)); 684 #endif 685 } 686 /* 687 * Lookup the ethernet address of the interface attached to the BPF 688 * file descriptor 'fd'; return it in 'eaddr'. 689 */ 690 void 691 lookup_eaddr(ifname, eaddr) 692 char *ifname; 693 u_char *eaddr; 694 { 695 #ifdef HAVE_IFADDRS_H 696 struct ifaddrs *ifap, *ifa; 697 struct sockaddr_dl *sdl; 698 699 if (getifaddrs(&ifap) != 0) { 700 rarperr(FATAL, "getifaddrs: %s", strerror(errno)); 701 /* NOTREACHED */ 702 } 703 704 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 705 sdl = (struct sockaddr_dl *)ifa->ifa_addr; 706 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 707 sdl->sdl_alen != 6) 708 continue; 709 if (!strcmp(ifa->ifa_name, ifname)) { 710 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 711 debug("%s: %x:%x:%x:%x:%x:%x", 712 ifa->ifa_name, eaddr[0], eaddr[1], 713 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 714 freeifaddrs(ifap); 715 return; 716 } 717 } 718 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 719 freeifaddrs(ifap); 720 #else 721 char inbuf[8192*2]; 722 struct ifconf ifc; 723 struct ifreq *ifr; 724 struct sockaddr_dl *sdl; 725 int fd; 726 int i, len; 727 728 /* We cannot use SIOCGIFADDR on the BPF descriptor. 729 We must instead get all the interfaces with SIOCGIFCONF 730 and find the right one. */ 731 732 /* Use datagram socket to get Ethernet address. */ 733 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 734 rarperr(FATAL, "socket: %s", strerror(errno)); 735 /* NOTREACHED */ 736 } 737 738 ifc.ifc_len = sizeof(inbuf); 739 ifc.ifc_buf = inbuf; 740 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 741 ifc.ifc_len < sizeof(struct ifreq)) { 742 rarperr(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 743 /* NOTREACHED */ 744 } 745 ifr = ifc.ifc_req; 746 for (i = 0; i < ifc.ifc_len; 747 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 748 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 749 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 750 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 751 sdl->sdl_alen != 6) 752 continue; 753 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 754 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 755 debug("%s: %x:%x:%x:%x:%x:%x", 756 ifr->ifr_name, eaddr[0], eaddr[1], 757 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 758 return; 759 } 760 } 761 762 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 763 #endif 764 } 765 /* 766 * Lookup the IP address and network mask of the interface named 'ifname'. 767 */ 768 void 769 lookup_ipaddr(ifname, addrp, netmaskp) 770 char *ifname; 771 u_int32_t *addrp; 772 u_int32_t *netmaskp; 773 { 774 int fd; 775 776 /* Use datagram socket to get IP address. */ 777 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 778 rarperr(FATAL, "socket: %s", strerror(errno)); 779 /* NOTREACHED */ 780 } 781 if (*addrp == INADDR_ANY) { 782 struct ifreq ifr; 783 memset(&ifr, 0, sizeof(ifr)); 784 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 785 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 786 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 787 /* NOTREACHED */ 788 } 789 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 790 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 791 perror("SIOCGIFNETMASK"); 792 exit(1); 793 } 794 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 795 } else { 796 struct ifaliasreq ifra; 797 memset(&ifra, 0, sizeof(ifra)); 798 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 799 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 800 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 801 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 802 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 803 /* NOTREACHED */ 804 } 805 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 806 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 807 } 808 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 809 * address class. */ 810 if (*netmaskp == 0) 811 *netmaskp = ipaddrtonetmask(*addrp); 812 813 (void)close(fd); 814 } 815 /* 816 * Poke the kernel arp tables with the ethernet/ip address combinataion 817 * given. When processing a reply, we must do this so that the booting 818 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 819 * address of the guy being booted (he cannot answer the ARP). 820 */ 821 #ifndef __NetBSD__ 822 void 823 update_arptab(ep, ipaddr) 824 u_char *ep; 825 u_int32_t ipaddr; 826 { 827 struct arpreq request; 828 struct sockaddr_in *sin; 829 830 request.arp_flags = 0; 831 sin = (struct sockaddr_in *) & request.arp_pa; 832 sin->sin_family = AF_INET; 833 sin->sin_addr.s_addr = ipaddr; 834 request.arp_ha.sa_family = AF_UNSPEC; 835 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 836 because AF_UNSPEC is zero and the kernel assumes that a zero 837 sa_family means that the real sa_family value is in sa_len. */ 838 request.arp_ha.sa_len = 16; /* XXX */ 839 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 840 841 #if 0 842 s = socket(AF_INET, SOCK_DGRAM, 0); 843 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 844 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 845 } 846 (void)close(s); 847 #endif 848 } 849 #endif 850 851 /* 852 * Build a reverse ARP packet and sent it out on the interface. 853 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 854 * on top of the request, then written to the network. 855 * 856 * RFC 903 defines the ether_arp fields as follows. The following comments 857 * are taken (more or less) straight from this document. 858 * 859 * ARPOP_REVREQUEST 860 * 861 * arp_sha is the hardware address of the sender of the packet. 862 * arp_spa is undefined. 863 * arp_tha is the 'target' hardware address. 864 * In the case where the sender wishes to determine his own 865 * protocol address, this, like arp_sha, will be the hardware 866 * address of the sender. 867 * arp_tpa is undefined. 868 * 869 * ARPOP_REVREPLY 870 * 871 * arp_sha is the hardware address of the responder (the sender of the 872 * reply packet). 873 * arp_spa is the protocol address of the responder (see the note below). 874 * arp_tha is the hardware address of the target, and should be the same as 875 * that which was given in the request. 876 * arp_tpa is the protocol address of the target, that is, the desired address. 877 * 878 * Note that the requirement that arp_spa be filled in with the responder's 879 * protocol is purely for convenience. For instance, if a system were to use 880 * both ARP and RARP, then the inclusion of the valid protocol-hardware 881 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 882 * ARP request. 883 */ 884 void 885 rarp_reply(ii, ep, ipaddr, hp) 886 struct if_info *ii; 887 struct ether_header *ep; 888 u_int32_t ipaddr; 889 struct hostent *hp; 890 { 891 int n; 892 #ifdef __NetBSD__ 893 struct arphdr *ap = (struct arphdr *) (ep + 1); 894 #else 895 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 896 #endif 897 898 int len; 899 900 #ifdef __NetBSD__ 901 (void)mkarp(ar_sha(ap), ipaddr); 902 #else 903 update_arptab((u_char *) & ap->arp_sha, ipaddr); 904 #endif 905 906 /* Build the rarp reply by modifying the rarp request in place. */ 907 #ifdef __FreeBSD__ 908 /* BPF (incorrectly) wants this in host order. */ 909 ep->ether_type = ETHERTYPE_REVARP; 910 #else 911 ep->ether_type = htons(ETHERTYPE_REVARP); 912 #endif 913 #ifdef __NetBSD__ 914 ap->ar_hrd = htons(ARPHRD_ETHER); 915 ap->ar_pro = htons(ETHERTYPE_IP); 916 ap->ar_op = htons(ARPOP_REVREPLY); 917 918 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 919 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 920 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 921 922 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 923 /* Target hardware is unchanged. */ 924 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 925 926 len = sizeof(*ep) + sizeof(*ap) + 927 2 * ap->ar_pln + 2 * ap->ar_hln; 928 #else 929 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 930 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 931 ap->arp_op = htons(ARPOP_REVREPLY); 932 933 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 934 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 935 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 936 937 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 938 /* Target hardware is unchanged. */ 939 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 940 941 len = sizeof(*ep) + sizeof(*ap); 942 #endif 943 944 debug("%s asked; %s replied", 945 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 946 if (lflag) 947 syslog(LOG_INFO, "%s asked; %s replied", 948 ether_ntoa((struct ether_addr *)ar_tha(ap)), hp->h_name); 949 n = write(ii->ii_fd, (char *) ep, len); 950 if (n != len) { 951 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 952 } 953 } 954 /* 955 * Get the netmask of an IP address. This routine is used if 956 * SIOCGIFNETMASK doesn't work. 957 */ 958 u_int32_t 959 ipaddrtonetmask(addr) 960 u_int32_t addr; 961 { 962 963 if (IN_CLASSA(addr)) 964 return IN_CLASSA_NET; 965 if (IN_CLASSB(addr)) 966 return IN_CLASSB_NET; 967 if (IN_CLASSC(addr)) 968 return IN_CLASSC_NET; 969 rarperr(FATAL, "unknown IP address class: %08X", addr); 970 /* NOTREACHED */ 971 return(-1); 972 } 973 974 #if __STDC__ 975 #include <stdarg.h> 976 #else 977 #include <varargs.h> 978 #endif 979 980 void 981 #if __STDC__ 982 rarperr(int fatal, const char *fmt,...) 983 #else 984 rarperr(fmt, va_alist) 985 int fatal; 986 char *fmt; 987 va_dcl 988 #endif 989 { 990 va_list ap; 991 992 #if __STDC__ 993 va_start(ap, fmt); 994 #else 995 va_start(ap); 996 #endif 997 if (dflag) { 998 if (fatal) 999 (void)fprintf(stderr, "rarpd: error: "); 1000 else 1001 (void)fprintf(stderr, "rarpd: warning: "); 1002 (void)vfprintf(stderr, fmt, ap); 1003 (void)fprintf(stderr, "\n"); 1004 } 1005 vsyslog(LOG_ERR, fmt, ap); 1006 va_end(ap); 1007 if (fatal) 1008 exit(1); 1009 /* NOTREACHED */ 1010 } 1011 1012 void 1013 #if __STDC__ 1014 debug(const char *fmt,...) 1015 #else 1016 debug(fmt, va_alist) 1017 char *fmt; 1018 va_dcl 1019 #endif 1020 { 1021 va_list ap; 1022 1023 #if __STDC__ 1024 va_start(ap, fmt); 1025 #else 1026 va_start(ap); 1027 #endif 1028 if (dflag) { 1029 (void)fprintf(stderr, "rarpd: "); 1030 (void)vfprintf(stderr, fmt, ap); 1031 (void)fprintf(stderr, "\n"); 1032 } 1033 vsyslog(LOG_WARNING, fmt, ap); 1034 va_end(ap); 1035 } 1036
Indexes created Thu Sep 25 16:09:42 GMT 2025