rarpd.c revision 1.36
1 /* $NetBSD: rarpd.c,v 1.36 2000/02/11 11:25:23 abs 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 1.36 2000/02/11 11:25:23 abs 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 */ 80 struct 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 */ 93 struct if_info *iflist; 94 95 u_int32_t choose_ipaddr __P((u_int32_t **, u_int32_t, u_int32_t)); 96 void debug __P((const char *,...)); 97 void init_all __P((void)); 98 void init_one __P((char *, u_int32_t)); 99 u_int32_t ipaddrtonetmask __P((u_int32_t)); 100 void lookup_eaddr __P((char *, u_char *)); 101 void lookup_ipaddr __P((char *, u_int32_t *, u_int32_t *)); 102 int main __P((int, char **)); 103 void rarp_loop __P((void)); 104 int rarp_open __P((char *)); 105 void rarp_process __P((struct if_info *, u_char *)); 106 void rarp_reply __P((struct if_info *, struct ether_header *, u_int32_t, 107 struct hostent *)); 108 void rarperr __P((int, const char *,...)); 109 110 #if defined(__NetBSD__) 111 #include "mkarp.h" 112 #else 113 void update_arptab __P((u_char *, u_int32_t)); 114 #endif 115 116 void usage __P((void)); 117 118 static int bpf_open __P((void)); 119 static int rarp_check __P((u_char *, int)); 120 121 #ifdef REQUIRE_TFTPBOOT 122 int rarp_bootable __P((u_int32_t)); 123 #endif 124 125 int aflag = 0; /* listen on "all" interfaces */ 126 int dflag = 0; /* print debugging messages */ 127 int fflag = 0; /* don't fork */ 128 int lflag = 0; /* log all replies */ 129 130 int 131 main(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 */ 191 void 192 init_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 */ 241 void 242 init_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 } 289 290 void 291 usage() 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 } 297 298 static int 299 bpf_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 */ 321 int 322 rarp_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 */ 389 static int 390 rarp_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 (len < sizeof(*ep) + sizeof(*ap)) { 402 rarperr(NONFATAL, "truncated request"); 403 return 0; 404 } 405 #ifdef __NetBSD__ 406 /* now that we know the fixed part of the ARP hdr is there: */ 407 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 408 rarperr(NONFATAL, "truncated request"); 409 return 0; 410 } 411 #endif 412 /* XXX This test might be better off broken out... */ 413 #ifdef __FreeBSD__ 414 /* BPF (incorrectly) returns this in host order. */ 415 if (ep->ether_type != ETHERTYPE_REVARP || 416 #else 417 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 418 #endif 419 #ifdef __NetBSD__ 420 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 421 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 422 ntohs (ap->ar_pro) != ETHERTYPE_IP || 423 ap->ar_hln != 6 || ap->ar_pln != 4) { 424 #else 425 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 426 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 427 ntohs (ap->arp_pro) != ETHERTYPE_IP || 428 ap->arp_hln != 6 || ap->arp_pln != 4) { 429 #endif 430 rarperr(NONFATAL, "request fails sanity check"); 431 return 0; 432 } 433 #ifdef __NetBSD__ 434 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 435 #else 436 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 437 #endif 438 rarperr(NONFATAL, "ether/arp sender address mismatch"); 439 return 0; 440 } 441 #ifdef __NetBSD__ 442 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 443 #else 444 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 445 #endif 446 rarperr(NONFATAL, "ether/arp target address mismatch"); 447 return 0; 448 } 449 return 1; 450 } 451 452 /* 453 * Loop indefinitely listening for RARP requests on the 454 * interfaces in 'iflist'. 455 */ 456 void 457 rarp_loop() 458 { 459 u_char *buf, *bp, *ep; 460 int cc, fd; 461 fd_set fds, listeners; 462 int bufsize, maxfd = 0; 463 struct if_info *ii; 464 465 if (iflist == 0) { 466 rarperr(FATAL, "no interfaces"); 467 /* NOTREACHED */ 468 } 469 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 470 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 471 /* NOTREACHED */ 472 } 473 buf = (u_char *) malloc((unsigned) bufsize); 474 if (buf == 0) { 475 rarperr(FATAL, "malloc: %s", strerror(errno)); 476 /* NOTREACHED */ 477 } 478 /* 479 * Find the highest numbered file descriptor for select(). 480 * Initialize the set of descriptors to listen to. 481 */ 482 FD_ZERO(&fds); 483 for (ii = iflist; ii; ii = ii->ii_next) { 484 FD_SET(ii->ii_fd, &fds); 485 if (ii->ii_fd > maxfd) 486 maxfd = ii->ii_fd; 487 } 488 while (1) { 489 listeners = fds; 490 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 491 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 492 rarperr(FATAL, "select: %s", strerror(errno)); 493 /* NOTREACHED */ 494 } 495 for (ii = iflist; ii; ii = ii->ii_next) { 496 fd = ii->ii_fd; 497 if (!FD_ISSET(fd, &listeners)) 498 continue; 499 again: 500 cc = read(fd, (char *) buf, bufsize); 501 /* Don't choke when we get ptraced */ 502 if (cc < 0 && errno == EINTR) 503 goto again; 504 /* Due to a SunOS bug, after 2^31 bytes, the file 505 * offset overflows and read fails with EINVAL. The 506 * lseek() to 0 will fix things. */ 507 if (cc < 0) { 508 if (errno == EINVAL && 509 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 510 (void)lseek(fd, 0, 0); 511 goto again; 512 } 513 rarperr(FATAL, "read: %s", strerror(errno)); 514 /* NOTREACHED */ 515 } 516 /* Loop through the packet(s) */ 517 #define bhp ((struct bpf_hdr *)bp) 518 bp = buf; 519 ep = bp + cc; 520 while (bp < ep) { 521 register int caplen, hdrlen; 522 523 caplen = bhp->bh_caplen; 524 hdrlen = bhp->bh_hdrlen; 525 debug("received packet on %s", ii->ii_name); 526 527 if (rarp_check(bp + hdrlen, caplen)) 528 rarp_process(ii, bp + hdrlen); 529 bp += BPF_WORDALIGN(hdrlen + caplen); 530 } 531 } 532 } 533 } 534 535 #ifdef REQUIRE_TFTPBOOT 536 537 #ifndef TFTP_DIR 538 #define TFTP_DIR "/tftpboot" 539 #endif 540 541 /* 542 * True if this server can boot the host whose IP address is 'addr'. 543 * This check is made by looking in the tftp directory for the 544 * configuration file. 545 */ 546 int 547 rarp_bootable(addr) 548 u_int32_t addr; 549 { 550 register struct dirent *dent; 551 register DIR *d; 552 char ipname[9]; 553 static DIR *dd = 0; 554 555 (void)sprintf(ipname, "%08X", addr); 556 /* If directory is already open, rewind it. Otherwise, open it. */ 557 if (d = dd) 558 rewinddir(d); 559 else { 560 if (chdir(TFTP_DIR) == -1) { 561 rarperr(FATAL, "chdir: %s", strerror(errno)); 562 /* NOTREACHED */ 563 } 564 d = opendir("."); 565 if (d == 0) { 566 rarperr(FATAL, "opendir: %s", strerror(errno)); 567 /* NOTREACHED */ 568 } 569 dd = d; 570 } 571 while (dent = readdir(d)) 572 if (strncmp(dent->d_name, ipname, 8) == 0) 573 return 1; 574 return 0; 575 } 576 #endif /* REQUIRE_TFTPBOOT */ 577 578 /* 579 * Given a list of IP addresses, 'alist', return the first address that 580 * is on network 'net'; 'netmask' is a mask indicating the network portion 581 * of the address. 582 */ 583 u_int32_t 584 choose_ipaddr(alist, net, netmask) 585 u_int32_t **alist; 586 u_int32_t net; 587 u_int32_t netmask; 588 { 589 590 for (; *alist; ++alist) { 591 if ((**alist & netmask) == net) 592 return **alist; 593 } 594 return 0; 595 } 596 /* 597 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 598 * already been checked for validity. The reply is overlaid on the request. 599 */ 600 void 601 rarp_process(ii, pkt) 602 struct if_info *ii; 603 u_char *pkt; 604 { 605 struct ether_header *ep; 606 struct hostent *hp; 607 u_int32_t target_ipaddr = 0; 608 char ename[MAXHOSTNAMELEN + 1]; 609 struct in_addr in; 610 611 ep = (struct ether_header *) pkt; 612 613 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 614 debug("no IP address for %s", 615 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 616 return; 617 } 618 ename[sizeof(ename)-1] = '\0'; 619 620 if ((hp = gethostbyname(ename)) == 0) { 621 debug("gethostbyname(%s) failed: %s", ename, 622 hstrerror(h_errno)); 623 return; 624 } 625 626 /* Choose correct address from list. */ 627 if (hp->h_addrtype != AF_INET) { 628 rarperr(FATAL, "cannot handle non IP addresses"); 629 /* NOTREACHED */ 630 } 631 for (;; ii = ii->ii_alias) { 632 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 633 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 634 if (target_ipaddr != 0) 635 break; 636 if (ii->ii_alias == NULL) 637 break; 638 } 639 640 if (target_ipaddr == 0) { 641 in.s_addr = ii->ii_ipaddr & ii->ii_netmask; 642 rarperr(NONFATAL, "cannot find %s on net %s", 643 ename, inet_ntoa(in)); 644 return; 645 } 646 #ifdef REQUIRE_TFTPBOOT 647 if (rarp_bootable(htonl(target_ipaddr))) 648 #endif 649 rarp_reply(ii, ep, target_ipaddr, hp); 650 #ifdef REQUIRE_TFTPBOOT 651 else 652 debug("%08X not bootable", htonl(target_ipaddr)); 653 #endif 654 } 655 /* 656 * Lookup the ethernet address of the interface attached to the BPF 657 * file descriptor 'fd'; return it in 'eaddr'. 658 */ 659 void 660 lookup_eaddr(ifname, eaddr) 661 char *ifname; 662 u_char *eaddr; 663 { 664 char inbuf[8192*2]; 665 struct ifconf ifc; 666 struct ifreq *ifr; 667 struct sockaddr_dl *sdl; 668 int fd; 669 int i, len; 670 671 /* We cannot use SIOCGIFADDR on the BPF descriptor. 672 We must instead get all the interfaces with SIOCGIFCONF 673 and find the right one. */ 674 675 /* Use datagram socket to get Ethernet address. */ 676 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 677 rarperr(FATAL, "socket: %s", strerror(errno)); 678 /* NOTREACHED */ 679 } 680 681 ifc.ifc_len = sizeof(inbuf); 682 ifc.ifc_buf = inbuf; 683 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 684 ifc.ifc_len < sizeof(struct ifreq)) { 685 rarperr(FATAL, "lookup_eaddr: SIOGIFCONF: %s", strerror(errno)); 686 /* NOTREACHED */ 687 } 688 ifr = ifc.ifc_req; 689 for (i = 0; i < ifc.ifc_len; 690 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 691 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 692 sdl = (struct sockaddr_dl *)&ifr->ifr_addr; 693 if (sdl->sdl_family != AF_LINK || sdl->sdl_type != IFT_ETHER || 694 sdl->sdl_alen != 6) 695 continue; 696 if (!strncmp(ifr->ifr_name, ifname, sizeof(ifr->ifr_name))) { 697 memmove((caddr_t)eaddr, (caddr_t)LLADDR(sdl), 6); 698 debug("%s: %x:%x:%x:%x:%x:%x", 699 ifr->ifr_name, eaddr[0], eaddr[1], 700 eaddr[2], eaddr[3], eaddr[4], eaddr[5]); 701 return; 702 } 703 } 704 705 rarperr(FATAL, "lookup_eaddr: Never saw interface `%s'!", ifname); 706 } 707 /* 708 * Lookup the IP address and network mask of the interface named 'ifname'. 709 */ 710 void 711 lookup_ipaddr(ifname, addrp, netmaskp) 712 char *ifname; 713 u_int32_t *addrp; 714 u_int32_t *netmaskp; 715 { 716 int fd; 717 718 /* Use datagram socket to get IP address. */ 719 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 720 rarperr(FATAL, "socket: %s", strerror(errno)); 721 /* NOTREACHED */ 722 } 723 if (*addrp == INADDR_ANY) { 724 struct ifreq ifr; 725 memset(&ifr, 0, sizeof(ifr)); 726 (void)strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 727 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 728 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 729 /* NOTREACHED */ 730 } 731 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 732 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 733 perror("SIOCGIFNETMASK"); 734 exit(1); 735 } 736 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 737 } else { 738 struct ifaliasreq ifra; 739 memset(&ifra, 0, sizeof(ifra)); 740 (void)strncpy(ifra.ifra_name, ifname, sizeof ifra.ifra_name); 741 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_family = AF_INET; 742 ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr = *addrp; 743 if (ioctl(fd, SIOCGIFALIAS, (char *) &ifra) < 0) { 744 rarperr(FATAL, "SIOCGIFALIAS: %s", strerror(errno)); 745 /* NOTREACHED */ 746 } 747 *addrp = ((struct sockaddr_in *) & ifra.ifra_addr)->sin_addr.s_addr; 748 *netmaskp = ((struct sockaddr_in *) & ifra.ifra_mask)->sin_addr.s_addr; 749 } 750 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 751 * address class. */ 752 if (*netmaskp == 0) 753 *netmaskp = ipaddrtonetmask(*addrp); 754 755 (void)close(fd); 756 } 757 /* 758 * Poke the kernel arp tables with the ethernet/ip address combinataion 759 * given. When processing a reply, we must do this so that the booting 760 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 761 * address of the guy being booted (he cannot answer the ARP). 762 */ 763 #ifndef __NetBSD__ 764 void 765 update_arptab(ep, ipaddr) 766 u_char *ep; 767 u_int32_t ipaddr; 768 { 769 struct arpreq request; 770 struct sockaddr_in *sin; 771 772 request.arp_flags = 0; 773 sin = (struct sockaddr_in *) & request.arp_pa; 774 sin->sin_family = AF_INET; 775 sin->sin_addr.s_addr = ipaddr; 776 request.arp_ha.sa_family = AF_UNSPEC; 777 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 778 because AF_UNSPEC is zero and the kernel assumes that a zero 779 sa_family means that the real sa_family value is in sa_len. */ 780 request.arp_ha.sa_len = 16; /* XXX */ 781 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 782 783 #if 0 784 s = socket(AF_INET, SOCK_DGRAM, 0); 785 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 786 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 787 } 788 (void)close(s); 789 #endif 790 } 791 #endif 792 793 /* 794 * Build a reverse ARP packet and sent it out on the interface. 795 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 796 * on top of the request, then written to the network. 797 * 798 * RFC 903 defines the ether_arp fields as follows. The following comments 799 * are taken (more or less) straight from this document. 800 * 801 * ARPOP_REVREQUEST 802 * 803 * arp_sha is the hardware address of the sender of the packet. 804 * arp_spa is undefined. 805 * arp_tha is the 'target' hardware address. 806 * In the case where the sender wishes to determine his own 807 * protocol address, this, like arp_sha, will be the hardware 808 * address of the sender. 809 * arp_tpa is undefined. 810 * 811 * ARPOP_REVREPLY 812 * 813 * arp_sha is the hardware address of the responder (the sender of the 814 * reply packet). 815 * arp_spa is the protocol address of the responder (see the note below). 816 * arp_tha is the hardware address of the target, and should be the same as 817 * that which was given in the request. 818 * arp_tpa is the protocol address of the target, that is, the desired address. 819 * 820 * Note that the requirement that arp_spa be filled in with the responder's 821 * protocol is purely for convenience. For instance, if a system were to use 822 * both ARP and RARP, then the inclusion of the valid protocol-hardware 823 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 824 * ARP request. 825 */ 826 void 827 rarp_reply(ii, ep, ipaddr, hp) 828 struct if_info *ii; 829 struct ether_header *ep; 830 u_int32_t ipaddr; 831 struct hostent *hp; 832 { 833 int n; 834 #ifdef __NetBSD__ 835 struct arphdr *ap = (struct arphdr *) (ep + 1); 836 #else 837 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 838 #endif 839 840 int len; 841 842 #ifdef __NetBSD__ 843 (void)mkarp(ar_sha(ap), ipaddr); 844 #else 845 update_arptab((u_char *) & ap->arp_sha, ipaddr); 846 #endif 847 848 /* Build the rarp reply by modifying the rarp request in place. */ 849 #ifdef __FreeBSD__ 850 /* BPF (incorrectly) wants this in host order. */ 851 ep->ether_type = ETHERTYPE_REVARP; 852 #else 853 ep->ether_type = htons(ETHERTYPE_REVARP); 854 #endif 855 #ifdef __NetBSD__ 856 ap->ar_hrd = htons(ARPHRD_ETHER); 857 ap->ar_pro = htons(ETHERTYPE_IP); 858 ap->ar_op = htons(ARPOP_REVREPLY); 859 860 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 861 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 862 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 863 864 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 865 /* Target hardware is unchanged. */ 866 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 867 868 len = sizeof(*ep) + sizeof(*ap) + 869 2 * ap->ar_pln + 2 * ap->ar_hln; 870 #else 871 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 872 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 873 ap->arp_op = htons(ARPOP_REVREPLY); 874 875 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 876 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 877 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 878 879 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 880 /* Target hardware is unchanged. */ 881 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 882 883 len = sizeof(*ep) + sizeof(*ap); 884 #endif 885 886 if (lflag) 887 syslog(LOG_INFO, "%s asked; %s replied", hp->h_name, 888 ether_ntoa((struct ether_addr *)ar_tha(ap))); 889 n = write(ii->ii_fd, (char *) ep, len); 890 if (n != len) { 891 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 892 } 893 } 894 /* 895 * Get the netmask of an IP address. This routine is used if 896 * SIOCGIFNETMASK doesn't work. 897 */ 898 u_int32_t 899 ipaddrtonetmask(addr) 900 u_int32_t addr; 901 { 902 903 if (IN_CLASSA(addr)) 904 return IN_CLASSA_NET; 905 if (IN_CLASSB(addr)) 906 return IN_CLASSB_NET; 907 if (IN_CLASSC(addr)) 908 return IN_CLASSC_NET; 909 rarperr(FATAL, "unknown IP address class: %08X", addr); 910 /* NOTREACHED */ 911 return(-1); 912 } 913 914 #if __STDC__ 915 #include <stdarg.h> 916 #else 917 #include <varargs.h> 918 #endif 919 920 void 921 #if __STDC__ 922 rarperr(int fatal, const char *fmt,...) 923 #else 924 rarperr(fmt, va_alist) 925 int fatal; 926 char *fmt; 927 va_dcl 928 #endif 929 { 930 va_list ap; 931 932 #if __STDC__ 933 va_start(ap, fmt); 934 #else 935 va_start(ap); 936 #endif 937 if (dflag) { 938 if (fatal) 939 (void)fprintf(stderr, "rarpd: error: "); 940 else 941 (void)fprintf(stderr, "rarpd: warning: "); 942 (void)vfprintf(stderr, fmt, ap); 943 (void)fprintf(stderr, "\n"); 944 } 945 vsyslog(LOG_ERR, fmt, ap); 946 va_end(ap); 947 if (fatal) 948 exit(1); 949 /* NOTREACHED */ 950 } 951 952 void 953 #if __STDC__ 954 debug(const char *fmt,...) 955 #else 956 debug(fmt, va_alist) 957 char *fmt; 958 va_dcl 959 #endif 960 { 961 va_list ap; 962 963 #if __STDC__ 964 va_start(ap, fmt); 965 #else 966 va_start(ap); 967 #endif 968 if (dflag) { 969 (void)fprintf(stderr, "rarpd: "); 970 (void)vfprintf(stderr, fmt, ap); 971 (void)fprintf(stderr, "\n"); 972 } 973 vsyslog(LOG_WARNING, fmt, ap); 974 va_end(ap); 975 } 976
Indexes created Wed Sep 24 05:09:52 GMT 2025