rarpd.c revision 1.25
1/* $NetBSD: rarpd.c,v 1.25 1998/04/23 02:48:33 mrg 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 1.25 1998/04/23 02:48:33 mrg Exp $"); 32#endif 33 34 35/* 36 * rarpd - Reverse ARP Daemon 37 * 38 * Usage: rarpd -a [ -d -f ] 39 * rarpd [ -d -f ] interface 40 */ 41 42#include <sys/types.h> 43#include <sys/errno.h> 44#include <sys/file.h> 45#include <sys/time.h> 46#include <sys/socket.h> 47#include <sys/ioctl.h> 48 49#include <net/bpf.h> 50#include <net/if.h> 51#include <net/if_dl.h> 52#ifdef __NetBSD__ 53#include <net/if_ether.h> 54#endif 55#include <net/if_types.h> 56#include <netinet/in.h> 57#ifdef __NetBSD__ 58#include <netinet/if_inarp.h> 59#else 60#include <netinet/if_ether.h> 61#endif 62 63#include <arpa/inet.h> 64 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 73#include "pathnames.h" 74 75#define FATAL 1 /* fatal error occurred */ 76#define NONFATAL 0 /* non fatal error occurred */ 77 78/* 79 * The structure for each interface. 80 */ 81struct if_info { 82 int ii_fd; /* BPF file descriptor */ 83 u_char ii_eaddr[6]; /* Ethernet address of this interface */ 84 u_long ii_ipaddr; /* IP address of this interface */ 85 u_long ii_netmask; /* subnet or net mask */ 86 struct if_info *ii_next; 87}; 88/* 89 * The list of all interfaces that are being listened to. rarp_loop() 90 * "selects" on the descriptors in this list. 91 */ 92struct if_info *iflist; 93 94u_int32_t choose_ipaddr __P((u_int32_t **, u_int32_t, u_int32_t)); 95void debug __P((const char *,...)); 96void init_all __P((void)); 97void init_one __P((char *)); 98u_long ipaddrtonetmask __P((u_long)); 99void lookup_eaddr __P((char *, u_char *)); 100void lookup_ipaddr __P((char *, u_long *, u_long *)); 101int main __P((int, char **)); 102void rarp_loop __P((void)); 103int rarp_open __P((char *)); 104void rarp_process __P((struct if_info *, u_char *)); 105void rarp_reply __P((struct if_info *, struct ether_header *, u_long, 106 struct hostent *)); 107void rarperr __P((int, const char *,...)); 108 109#if defined(__NetBSD__) 110#include "mkarp.h" 111#else 112void update_arptab __P((u_char *, u_long)); 113#endif 114 115void usage __P((void)); 116 117static int bpf_open __P((void)); 118static int rarp_check __P((u_char *, int)); 119 120#ifdef REQUIRE_TFTPBOOT 121int rarp_bootable __P((u_long)); 122#endif 123 124int aflag = 0; /* listen on "all" interfaces */ 125int dflag = 0; /* print debugging messages */ 126int fflag = 0; /* don't fork */ 127int lflag = 0; /* log all replies */ 128 129int 130main(argc, argv) 131 int argc; 132 char **argv; 133{ 134 extern char *__progname; 135 136 int op, pid, devnull, f; 137 char *ifname, *hostname; 138 139 /* All error reporting is done through syslogs. */ 140 openlog(__progname, LOG_PID, LOG_DAEMON); 141 142 opterr = 0; 143 while ((op = getopt(argc, argv, "adfl")) != -1) { 144 switch (op) { 145 case 'a': 146 ++aflag; 147 break; 148 149 case 'd': 150 ++dflag; 151 break; 152 153 case 'f': 154 ++fflag; 155 break; 156 157 case 'l': 158 ++lflag; 159 break; 160 161 default: 162 usage(); 163 /* NOTREACHED */ 164 } 165 } 166 ifname = argv[optind++]; 167 hostname = ifname ? argv[optind] : 0; 168 if ((aflag && ifname) || (!aflag && ifname == 0)) 169 usage(); 170 171 if (aflag) 172 init_all(); 173 else 174 init_one(ifname); 175 176 if ((!fflag) && (!dflag)) { 177 FILE *fp; 178 179 pid = fork(); 180 if (pid > 0) 181 /* Parent exits, leaving child in background. */ 182 exit(0); 183 else 184 if (pid == -1) { 185 rarperr(FATAL, "cannot fork"); 186 /* NOTREACHED */ 187 } 188 189 /* write pid file */ 190 if ((fp = fopen(_PATH_RARPDPID, "w")) != NULL) { 191 fprintf(fp, "%u\n", getpid()); 192 (void)fclose(fp); 193 } 194 195 /* Fade into the background */ 196 f = open("/dev/tty", O_RDWR); 197 if (f >= 0) { 198 if (ioctl(f, TIOCNOTTY, 0) < 0) { 199 rarperr(FATAL, 200 "TIOCNOTTY: %s", strerror(errno)); 201 /* NOTREACHED */ 202 } 203 (void) close(f); 204 } 205 (void) chdir("/"); 206 (void) setpgrp(0, getpid()); 207 devnull = open("/dev/null", O_RDWR); 208 if (devnull >= 0) { 209 (void) dup2(devnull, 0); 210 (void) dup2(devnull, 1); 211 (void) dup2(devnull, 2); 212 if (devnull > 2) 213 (void) close(devnull); 214 } 215 } 216 rarp_loop(); 217 /* NOTREACHED */ 218 return (0); 219} 220 221/* 222 * Add 'ifname' to the interface list. Lookup its IP address and network 223 * mask and Ethernet address, and open a BPF file for it. 224 */ 225void 226init_one(ifname) 227 char *ifname; 228{ 229 struct if_info *p; 230 int fd; 231 232 fd = rarp_open(ifname); 233 if (fd < 0) 234 return; 235 236 p = (struct if_info *)malloc(sizeof(*p)); 237 if (p == 0) { 238 rarperr(FATAL, "malloc: %s", strerror(errno)); 239 /* NOTREACHED */ 240 } 241 p->ii_next = iflist; 242 iflist = p; 243 244 p->ii_fd = fd; 245 lookup_eaddr(ifname, p->ii_eaddr); 246 lookup_ipaddr(ifname, &p->ii_ipaddr, &p->ii_netmask); 247} 248 249/* 250 * Initialize all "candidate" interfaces that are in the system 251 * configuration list. A "candidate" is up, not loopback and not 252 * point to point. 253 */ 254void 255init_all() 256{ 257 char inbuf[8192]; 258 struct ifconf ifc; 259 struct ifreq ifreq, *ifr; 260 int fd; 261 int i, len; 262 263 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 264 rarperr(FATAL, "socket: %s", strerror(errno)); 265 /* NOTREACHED */ 266 } 267 268 ifc.ifc_len = sizeof(inbuf); 269 ifc.ifc_buf = inbuf; 270 if (ioctl(fd, SIOCGIFCONF, (caddr_t)&ifc) < 0 || 271 ifc.ifc_len < sizeof(struct ifreq)) { 272 rarperr(FATAL, "init_all: SIOCGIFCONF: %s", strerror(errno)); 273 /* NOTREACHED */ 274 } 275 ifr = ifc.ifc_req; 276 ifreq.ifr_name[0] = '\0'; 277 for (i = 0; i < ifc.ifc_len; 278 i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) { 279 len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len; 280 if (!strncmp(ifreq.ifr_name, ifr->ifr_name, sizeof(ifr->ifr_name))) 281 continue; 282 ifreq = *ifr; 283 if (ioctl(fd, SIOCGIFFLAGS, (caddr_t)ifr) < 0) { 284 rarperr(FATAL, "init_all: SIOCGIFFLAGS: %s", 285 strerror(errno)); 286 /* NOTREACHED */ 287 } 288 if ((ifr->ifr_flags & 289 (IFF_UP | IFF_LOOPBACK | IFF_POINTOPOINT)) != IFF_UP) 290 continue; 291 init_one(ifr->ifr_name); 292 } 293 (void) close(fd); 294} 295 296void 297usage() 298{ 299 (void) fprintf(stderr, "usage: rarpd -a [ -d -f ]\n"); 300 (void) fprintf(stderr, " rarpd [ -d -f ] interface\n"); 301 exit(1); 302} 303 304static int 305bpf_open() 306{ 307 int fd; 308 int n = 0; 309 char device[sizeof "/dev/bpf000"]; 310 311 /* Go through all the minors and find one that isn't in use. */ 312 do { 313 (void) sprintf(device, "/dev/bpf%d", n++); 314 fd = open(device, O_RDWR); 315 } while (fd < 0 && errno == EBUSY); 316 317 if (fd < 0) { 318 rarperr(FATAL, "%s: %s", device, strerror(errno)); 319 /* NOTREACHED */ 320 } 321 return fd; 322} 323/* 324 * Open a BPF file and attach it to the interface named 'device'. 325 * Set immediate mode, and set a filter that accepts only RARP requests. 326 */ 327int 328rarp_open(device) 329 char *device; 330{ 331 int fd; 332 struct ifreq ifr; 333 u_int dlt; 334 int immediate; 335 336 static struct bpf_insn insns[] = { 337 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 12), 338 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ETHERTYPE_REVARP, 0, 3), 339 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 20), 340 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ARPOP_REVREQUEST, 0, 1), 341 BPF_STMT(BPF_RET | BPF_K, 342 sizeof(struct arphdr) + 343 2 * ETHER_ADDR_LEN + 2 * sizeof(struct in_addr) + 344 sizeof(struct ether_header)), 345 BPF_STMT(BPF_RET | BPF_K, 0), 346 }; 347 static struct bpf_program filter = { 348 sizeof insns / sizeof(insns[0]), 349 insns 350 }; 351 352 fd = bpf_open(); 353 354 /* Set immediate mode so packets are processed as they arrive. */ 355 immediate = 1; 356 if (ioctl(fd, BIOCIMMEDIATE, &immediate) < 0) { 357 rarperr(FATAL, "BIOCIMMEDIATE: %s", strerror(errno)); 358 /* NOTREACHED */ 359 } 360 (void) strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name); 361 if (ioctl(fd, BIOCSETIF, (caddr_t) & ifr) < 0) { 362 if (aflag) { /* for -a skip non-ethernet interfaces */ 363 close(fd); 364 return(-1); 365 } 366 rarperr(FATAL, "BIOCSETIF: %s", strerror(errno)); 367 /* NOTREACHED */ 368 } 369 /* Check that the data link layer is an Ethernet; this code won't work 370 * with anything else. */ 371 if (ioctl(fd, BIOCGDLT, (caddr_t) & dlt) < 0) { 372 rarperr(FATAL, "BIOCGDLT: %s", strerror(errno)); 373 /* NOTREACHED */ 374 } 375 if (dlt != DLT_EN10MB) { 376 if (aflag) { /* for -a skip non-ethernet interfaces */ 377 close(fd); 378 return(-1); 379 } 380 rarperr(FATAL, "%s is not an ethernet", device); 381 /* NOTREACHED */ 382 } 383 /* Set filter program. */ 384 if (ioctl(fd, BIOCSETF, (caddr_t) & filter) < 0) { 385 rarperr(FATAL, "BIOCSETF: %s", strerror(errno)); 386 /* NOTREACHED */ 387 } 388 return fd; 389} 390/* 391 * Perform various sanity checks on the RARP request packet. Return 392 * false on failure and log the reason. 393 */ 394static int 395rarp_check(p, len) 396 u_char *p; 397 int len; 398{ 399 struct ether_header *ep = (struct ether_header *) p; 400#ifdef __NetBSD__ 401 struct arphdr *ap = (struct arphdr *) (p + sizeof(*ep)); 402#else 403 struct ether_arp *ap = (struct ether_arp *) (p + sizeof(*ep)); 404#endif 405 406 if (dflag) 407 fprintf(stderr, "got a packet\n"); 408 409 if (len < sizeof(*ep) + sizeof(*ap)) { 410 rarperr(NONFATAL, "truncated request"); 411 return 0; 412 } 413#ifdef __NetBSD__ 414 /* now that we know the fixed part of the ARP hdr is there: */ 415 if (len < sizeof(*ap) + 2 * ap->ar_hln + 2 * ap->ar_pln) { 416 rarperr(NONFATAL, "truncated request"); 417 return 0; 418 } 419#endif 420 /* XXX This test might be better off broken out... */ 421#ifdef __FreeBSD__ 422 /* BPF (incorrectly) returns this in host order. */ 423 if (ep->ether_type != ETHERTYPE_REVARP || 424#else 425 if (ntohs (ep->ether_type) != ETHERTYPE_REVARP || 426#endif 427#ifdef __NetBSD__ 428 ntohs (ap->ar_hrd) != ARPHRD_ETHER || 429 ntohs (ap->ar_op) != ARPOP_REVREQUEST || 430 ntohs (ap->ar_pro) != ETHERTYPE_IP || 431 ap->ar_hln != 6 || ap->ar_pln != 4) { 432#else 433 ntohs (ap->arp_hrd) != ARPHRD_ETHER || 434 ntohs (ap->arp_op) != ARPOP_REVREQUEST || 435 ntohs (ap->arp_pro) != ETHERTYPE_IP || 436 ap->arp_hln != 6 || ap->arp_pln != 4) { 437#endif 438 rarperr(NONFATAL, "request fails sanity check"); 439 return 0; 440 } 441#ifdef __NetBSD__ 442 if (memcmp((char *) &ep->ether_shost, ar_sha(ap), 6) != 0) { 443#else 444 if (memcmp((char *) &ep->ether_shost, ap->arp_sha, 6) != 0) { 445#endif 446 rarperr(NONFATAL, "ether/arp sender address mismatch"); 447 return 0; 448 } 449#ifdef __NetBSD__ 450 if (memcmp(ar_sha(ap), ar_tha(ap), 6) != 0) { 451#else 452 if (memcmp((char *) &ap->arp_sha, (char *) &ap->arp_tha, 6) != 0) { 453#endif 454 rarperr(NONFATAL, "ether/arp target address mismatch"); 455 return 0; 456 } 457 return 1; 458} 459 460/* 461 * Loop indefinitely listening for RARP requests on the 462 * interfaces in 'iflist'. 463 */ 464void 465rarp_loop() 466{ 467 u_char *buf, *bp, *ep; 468 int cc, fd; 469 fd_set fds, listeners; 470 int bufsize, maxfd = 0; 471 struct if_info *ii; 472 473 if (iflist == 0) { 474 rarperr(FATAL, "no interfaces"); 475 /* NOTREACHED */ 476 } 477 if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t) & bufsize) < 0) { 478 rarperr(FATAL, "BIOCGBLEN: %s", strerror(errno)); 479 /* NOTREACHED */ 480 } 481 buf = (u_char *) malloc((unsigned) bufsize); 482 if (buf == 0) { 483 rarperr(FATAL, "malloc: %s", strerror(errno)); 484 /* NOTREACHED */ 485 } 486 /* 487 * Find the highest numbered file descriptor for select(). 488 * Initialize the set of descriptors to listen to. 489 */ 490 FD_ZERO(&fds); 491 for (ii = iflist; ii; ii = ii->ii_next) { 492 FD_SET(ii->ii_fd, &fds); 493 if (ii->ii_fd > maxfd) 494 maxfd = ii->ii_fd; 495 } 496 while (1) { 497 listeners = fds; 498 if (select(maxfd + 1, &listeners, (struct fd_set *) 0, 499 (struct fd_set *) 0, (struct timeval *) 0) < 0) { 500 rarperr(FATAL, "select: %s", strerror(errno)); 501 /* NOTREACHED */ 502 } 503 for (ii = iflist; ii; ii = ii->ii_next) { 504 fd = ii->ii_fd; 505 if (!FD_ISSET(fd, &listeners)) 506 continue; 507 again: 508 cc = read(fd, (char *) buf, bufsize); 509 /* Don't choke when we get ptraced */ 510 if (cc < 0 && errno == EINTR) 511 goto again; 512 /* Due to a SunOS bug, after 2^31 bytes, the file 513 * offset overflows and read fails with EINVAL. The 514 * lseek() to 0 will fix things. */ 515 if (cc < 0) { 516 if (errno == EINVAL && 517 (lseek(fd, 0, SEEK_CUR) + bufsize) < 0) { 518 (void) lseek(fd, 0, 0); 519 goto again; 520 } 521 rarperr(FATAL, "read: %s", strerror(errno)); 522 /* NOTREACHED */ 523 } 524 /* Loop through the packet(s) */ 525#define bhp ((struct bpf_hdr *)bp) 526 bp = buf; 527 ep = bp + cc; 528 while (bp < ep) { 529 register int caplen, hdrlen; 530 531 caplen = bhp->bh_caplen; 532 hdrlen = bhp->bh_hdrlen; 533 if (rarp_check(bp + hdrlen, caplen)) 534 rarp_process(ii, bp + hdrlen); 535 bp += BPF_WORDALIGN(hdrlen + caplen); 536 } 537 } 538 } 539} 540 541#ifdef REQUIRE_TFTPBOOT 542 543#ifndef TFTP_DIR 544#define TFTP_DIR "/tftpboot" 545#endif 546 547/* 548 * True if this server can boot the host whose IP address is 'addr'. 549 * This check is made by looking in the tftp directory for the 550 * configuration file. 551 */ 552int 553rarp_bootable(addr) 554 u_long addr; 555{ 556 register struct dirent *dent; 557 register DIR *d; 558 char ipname[9]; 559 static DIR *dd = 0; 560 561 (void) sprintf(ipname, "%08X", addr); 562 /* If directory is already open, rewind it. Otherwise, open it. */ 563 if (d = dd) 564 rewinddir(d); 565 else { 566 if (chdir(TFTP_DIR) == -1) { 567 rarperr(FATAL, "chdir: %s", strerror(errno)); 568 /* NOTREACHED */ 569 } 570 d = opendir("."); 571 if (d == 0) { 572 rarperr(FATAL, "opendir: %s", strerror(errno)); 573 /* NOTREACHED */ 574 } 575 dd = d; 576 } 577 while (dent = readdir(d)) 578 if (strncmp(dent->d_name, ipname, 8) == 0) 579 return 1; 580 return 0; 581} 582#endif /* REQUIRE_TFTPBOOT */ 583 584/* 585 * Given a list of IP addresses, 'alist', return the first address that 586 * is on network 'net'; 'netmask' is a mask indicating the network portion 587 * of the address. 588 */ 589u_int32_t 590choose_ipaddr(alist, net, netmask) 591 u_int32_t **alist; 592 u_int32_t net; 593 u_int32_t netmask; 594{ 595 for (; *alist; ++alist) { 596 if ((**alist & netmask) == net) 597 return **alist; 598 } 599 return 0; 600} 601/* 602 * Answer the RARP request in 'pkt', on the interface 'ii'. 'pkt' has 603 * already been checked for validity. The reply is overlaid on the request. 604 */ 605void 606rarp_process(ii, pkt) 607 struct if_info *ii; 608 u_char *pkt; 609{ 610 struct ether_header *ep; 611 struct hostent *hp; 612 u_long target_ipaddr; 613 char ename[MAXHOSTNAMELEN + 1]; 614 struct in_addr in; 615 616 ep = (struct ether_header *) pkt; 617 618 if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) { 619 debug("no IP address for %s", 620 ether_ntoa((struct ether_addr *)&ep->ether_shost)); 621 return; 622 } 623 ename[sizeof(ename)-1] = '\0'; 624 625 if ((hp = gethostbyname(ename)) == 0) { 626 debug("gethostbyname(%s) failed: %s", ename, 627 hstrerror(h_errno)); 628 return; 629 } 630 631 /* Choose correct address from list. */ 632 if (hp->h_addrtype != AF_INET) { 633 rarperr(FATAL, "cannot handle non IP addresses"); 634 /* NOTREACHED */ 635 } 636 target_ipaddr = choose_ipaddr((u_int32_t **) hp->h_addr_list, 637 ii->ii_ipaddr & ii->ii_netmask, ii->ii_netmask); 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\n", 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]; 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_long *addrp; 713 u_long *netmaskp; 714{ 715 int fd; 716 struct ifreq ifr; 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 (void) strncpy(ifr.ifr_name, ifname, sizeof ifr.ifr_name); 724 if (ioctl(fd, SIOCGIFADDR, (char *) &ifr) < 0) { 725 rarperr(FATAL, "SIOCGIFADDR: %s", strerror(errno)); 726 /* NOTREACHED */ 727 } 728 *addrp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 729 if (ioctl(fd, SIOCGIFNETMASK, (char *) &ifr) < 0) { 730 perror("SIOCGIFNETMASK"); 731 unlink(_PATH_RARPDPID); 732 exit(1); 733 } 734 *netmaskp = ((struct sockaddr_in *) & ifr.ifr_addr)->sin_addr.s_addr; 735 /* If SIOCGIFNETMASK didn't work, figure out a mask from the IP 736 * address class. */ 737 if (*netmaskp == 0) 738 *netmaskp = ipaddrtonetmask(*addrp); 739 740 (void) close(fd); 741} 742/* 743 * Poke the kernel arp tables with the ethernet/ip address combinataion 744 * given. When processing a reply, we must do this so that the booting 745 * host (i.e. the guy running rarpd), won't try to ARP for the hardware 746 * address of the guy being booted (he cannot answer the ARP). 747 */ 748#ifndef __NetBSD__ 749void 750update_arptab(ep, ipaddr) 751 u_char *ep; 752 u_long ipaddr; 753{ 754 struct arpreq request; 755 struct sockaddr_in *sin; 756 757 request.arp_flags = 0; 758 sin = (struct sockaddr_in *) & request.arp_pa; 759 sin->sin_family = AF_INET; 760 sin->sin_addr.s_addr = ipaddr; 761 request.arp_ha.sa_family = AF_UNSPEC; 762 /* This is needed #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN, 763 because AF_UNSPEC is zero and the kernel assumes that a zero 764 sa_family means that the real sa_family value is in sa_len. */ 765 request.arp_ha.sa_len = 16; /* XXX */ 766 memmove((char *) request.arp_ha.sa_data, (char *)ep, 6); 767 768#if 0 769 s = socket(AF_INET, SOCK_DGRAM, 0); 770 if (ioctl(s, SIOCSARP, (caddr_t) & request) < 0) { 771 rarperr(NONFATAL, "SIOCSARP: %s", strerror(errno)); 772 } 773 (void) close(s); 774#endif 775} 776#endif 777 778/* 779 * Build a reverse ARP packet and sent it out on the interface. 780 * 'ep' points to a valid ARPOP_REVREQUEST. The ARPOP_REVREPLY is built 781 * on top of the request, then written to the network. 782 * 783 * RFC 903 defines the ether_arp fields as follows. The following comments 784 * are taken (more or less) straight from this document. 785 * 786 * ARPOP_REVREQUEST 787 * 788 * arp_sha is the hardware address of the sender of the packet. 789 * arp_spa is undefined. 790 * arp_tha is the 'target' hardware address. 791 * In the case where the sender wishes to determine his own 792 * protocol address, this, like arp_sha, will be the hardware 793 * address of the sender. 794 * arp_tpa is undefined. 795 * 796 * ARPOP_REVREPLY 797 * 798 * arp_sha is the hardware address of the responder (the sender of the 799 * reply packet). 800 * arp_spa is the protocol address of the responder (see the note below). 801 * arp_tha is the hardware address of the target, and should be the same as 802 * that which was given in the request. 803 * arp_tpa is the protocol address of the target, that is, the desired address. 804 * 805 * Note that the requirement that arp_spa be filled in with the responder's 806 * protocol is purely for convenience. For instance, if a system were to use 807 * both ARP and RARP, then the inclusion of the valid protocol-hardware 808 * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent 809 * ARP request. 810 */ 811void 812rarp_reply(ii, ep, ipaddr, hp) 813 struct if_info *ii; 814 struct ether_header *ep; 815 u_long ipaddr; 816 struct hostent *hp; 817{ 818 int n; 819#ifdef __NetBSD__ 820 struct arphdr *ap = (struct arphdr *) (ep + 1); 821#else 822 struct ether_arp *ap = (struct ether_arp *) (ep + 1); 823#endif 824 825 int len; 826 827#ifdef __NetBSD__ 828 (void)mkarp(ar_sha(ap), ipaddr); 829#else 830 update_arptab((u_char *) & ap->arp_sha, ipaddr); 831#endif 832 833 /* Build the rarp reply by modifying the rarp request in place. */ 834#ifdef __FreeBSD__ 835 /* BPF (incorrectly) wants this in host order. */ 836 ep->ether_type = ETHERTYPE_REVARP; 837#else 838 ep->ether_type = htons(ETHERTYPE_REVARP); 839#endif 840#ifdef __NetBSD__ 841 ap->ar_hrd = htons(ARPHRD_ETHER); 842 ap->ar_pro = htons(ETHERTYPE_IP); 843 ap->ar_op = htons(ARPOP_REVREPLY); 844 845 memmove((char *) &ep->ether_dhost, ar_sha(ap), 6); 846 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 847 memmove(ar_sha(ap), (char *) ii->ii_eaddr, 6); 848 849 memmove(ar_tpa(ap), (char *) &ipaddr, 4); 850 /* Target hardware is unchanged. */ 851 memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4); 852 853 len = sizeof(*ep) + sizeof(*ap) + 854 2 * ap->ar_pln + 2 * ap->ar_hln; 855#else 856 ap->ea_hdr.ar_hrd = htons(ARPHRD_ETHER); 857 ap->ea_hdr.ar_pro = htons(ETHERTYPE_IP); 858 ap->arp_op = htons(ARPOP_REVREPLY); 859 860 memmove((char *) &ep->ether_dhost, (char *) &ap->arp_sha, 6); 861 memmove((char *) &ep->ether_shost, (char *) ii->ii_eaddr, 6); 862 memmove((char *) &ap->arp_sha, (char *) ii->ii_eaddr, 6); 863 864 memmove((char *) ap->arp_tpa, (char *) &ipaddr, 4); 865 /* Target hardware is unchanged. */ 866 memmove((char *) ap->arp_spa, (char *) &ii->ii_ipaddr, 4); 867 868 len = sizeof(*ep) + sizeof(*ap); 869#endif 870 871 if (lflag) 872 syslog(LOG_INFO, "%s asked; %s replied", hp->h_name, 873 ether_ntoa((struct ether_addr *)ar_tha(ap))); 874 n = write(ii->ii_fd, (char *) ep, len); 875 if (n != len) { 876 rarperr(NONFATAL, "write: only %d of %d bytes written", n, len); 877 } 878} 879/* 880 * Get the netmask of an IP address. This routine is used if 881 * SIOCGIFNETMASK doesn't work. 882 */ 883u_long 884ipaddrtonetmask(addr) 885 u_long addr; 886{ 887 if (IN_CLASSA(addr)) 888 return IN_CLASSA_NET; 889 if (IN_CLASSB(addr)) 890 return IN_CLASSB_NET; 891 if (IN_CLASSC(addr)) 892 return IN_CLASSC_NET; 893 rarperr(FATAL, "unknown IP address class: %08X", addr); 894 /* NOTREACHED */ 895 return(-1); 896} 897 898#if __STDC__ 899#include <stdarg.h> 900#else 901#include <varargs.h> 902#endif 903 904void 905#if __STDC__ 906rarperr(int fatal, const char *fmt,...) 907#else 908rarperr(fmt, va_alist) 909 int fatal; 910 char *fmt; 911va_dcl 912#endif 913{ 914 va_list ap; 915#if __STDC__ 916 va_start(ap, fmt); 917#else 918 va_start(ap); 919#endif 920 if (dflag) { 921 if (fatal) 922 (void) fprintf(stderr, "rarpd: error: "); 923 else 924 (void) fprintf(stderr, "rarpd: warning: "); 925 (void) vfprintf(stderr, fmt, ap); 926 (void) fprintf(stderr, "\n"); 927 } 928 vsyslog(LOG_ERR, fmt, ap); 929 va_end(ap); 930 if (fatal) { 931 unlink(_PATH_RARPDPID); 932 exit(1); 933 } 934 /* NOTREACHED */ 935} 936 937void 938#if __STDC__ 939debug(const char *fmt,...) 940#else 941debug(fmt, va_alist) 942 char *fmt; 943va_dcl 944#endif 945{ 946 va_list ap; 947 948#if __STDC__ 949 va_start(ap, fmt); 950#else 951 va_start(ap); 952#endif 953 if (dflag) { 954 (void) fprintf(stderr, "rarpd: "); 955 (void) vfprintf(stderr, fmt, ap); 956 (void) fprintf(stderr, "\n"); 957 } 958 vsyslog(LOG_WARNING, fmt, ap); 959 va_end(ap); 960} 961