usr.sbin/rarpd/rarpd.c

   1 /*
   2  * Copyright (c) 1990, 1991, 1992, 1993, 1996
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  *
  21  * @(#) Copyright (c) 1990, 1991, 1992, 1993, 1996 The Regents of the University of California.  All rights reserved.
  22  * $FreeBSD: src/usr.sbin/rarpd/rarpd.c,v 1.23.2.4 2002/12/01 19:19:34 dwmalone Exp $
  23  * $DragonFly: src/usr.sbin/rarpd/rarpd.c,v 1.4 2004/12/18 22:48:05 swildner Exp $
  24  */
  25
  26 /*
  27  * rarpd - Reverse ARP Daemon
  28  *
  29  * Usage:       rarpd -a [ -dfsv ] [-t directory] [ hostname ]
  30  *              rarpd [ -dfsv ] [-t directory] interface [ hostname ]
  31  *
  32  * 'hostname' is optional solely for backwards compatibility with Sun's rarpd.
  33  * Currently, the argument is ignored.
  34  */
  35 #include <sys/param.h>
  36 #include <sys/file.h>
  37 #include <sys/ioctl.h>
  38 #include <sys/socket.h>
  39 #include <sys/time.h>
  40
  41 #include <net/bpf.h>
  42 #include <net/ethernet.h>
  43 #include <net/if.h>
  44 #include <net/if_types.h>
  45 #include <net/if_dl.h>
  46 #include <net/route.h>
  47
  48 #include <netinet/in.h>
  49 #include <netinet/if_ether.h>
  50
  51 #include <arpa/inet.h>
  52
  53 #include <errno.h>
  54 #include <netdb.h>
  55 #include <stdarg.h>
  56 #include <stdio.h>
  57 #include <string.h>
  58 #include <syslog.h>
  59 #include <stdlib.h>
  60 #include <unistd.h>
  61
  62 #if defined(SUNOS4) || defined(__DragonFly__) /* XXX */
  63 #define HAVE_DIRENT_H
  64 #endif
  65
  66 #ifdef HAVE_DIRENT_H
  67 #include <dirent.h>
  68 #else
  69 #include <sys/dir.h>
  70 #endif
  71
  72 /* Cast a struct sockaddr to a structaddr_in */
  73 #define SATOSIN(sa) ((struct sockaddr_in *)(sa))
  74
  75 #ifndef TFTP_DIR
  76 #define TFTP_DIR "/tftpboot"
  77 #endif
  78
  79 #if BSD >= 199200
  80 #define ARPSECS (20 * 60)               /* as per code in netinet/if_ether.c */
  81 #define REVARP_REQUEST ARPOP_REVREQUEST
  82 #define REVARP_REPLY ARPOP_REVREPLY
  83 #endif
  84
  85 #ifndef ETHERTYPE_REVARP
  86 #define ETHERTYPE_REVARP 0x8035
  87 #define REVARP_REQUEST 3
  88 #define REVARP_REPLY 4
  89 #endif
  90
  91 /*
  92  * Map field names in ether_arp struct.  What a pain in the neck.
  93  */
  94 #ifdef SUNOS3
  95 #undef arp_sha
  96 #undef arp_spa
  97 #undef arp_tha
  98 #undef arp_tpa
  99 #define arp_sha arp_xsha
 100 #define arp_spa arp_xspa
 101 #define arp_tha arp_xtha
 102 #define arp_tpa arp_xtpa
 103 #endif
 104
 105 /*
 106  * The structure for each interface.
 107  */
 108 struct if_info {
 109         struct  if_info *ii_next;
 110         int     ii_fd;          /* BPF file descriptor */
 111         u_long  ii_ipaddr;      /* IP address of this interface */
 112         u_long  ii_netmask;     /* subnet or net mask */
 113         u_char  ii_eaddr[6];    /* Ethernet address of this interface */
 114         char ii_ifname[sizeof(((struct ifreq *)0)->ifr_name) + 1];
 115 };
 116
 117 /*
 118  * The list of all interfaces that are being listened to.  rarp_loop()
 119  * "selects" on the descriptors in this list.
 120  */
 121 struct if_info *iflist;
 122
 123 int verbose;                    /* verbose messages */
 124 int s;                          /* inet datagram socket */
 125 const char *tftp_dir = TFTP_DIR;        /* tftp directory */
 126
 127 int dflag;                      /* messages to stdout/stderr, not syslog(3) */
 128 int sflag;                      /* ignore /tftpboot */
 129
 130 static  u_char zero[6];
 131
 132 static int      bpf_open(void);
 133 static u_long   choose_ipaddr(u_long **, u_long, u_long);
 134 static char     *eatoa(u_char *);
 135 static int      expand_syslog_m(const char *fmt, char **newfmt);
 136 static void     init(char *);
 137 static void     init_one(struct ifreq *, char *);
 138 static char     *intoa(u_long);
 139 static u_long   ipaddrtonetmask(u_long);
 140 static void     logmsg(int, const char *, ...) __printflike(2, 3);
 141 static int      rarp_bootable(u_long);
 142 static int      rarp_check(u_char *, u_int);
 143 static void     rarp_loop(void);
 144 static int      rarp_open(char *);
 145 static void     rarp_process(struct if_info *, u_char *, u_int);
 146 static void     rarp_reply(struct if_info *, struct ether_header *,
 147                 u_long, u_int);
 148 static void     update_arptab(u_char *, u_long);
 149 static void     usage(void);
 150
 151 int
 152 main(int argc, char *argv[])
 153 {
 154         int op;
 155         char *ifname, *hostname, *name;
 156
 157         int aflag = 0;          /* listen on "all" interfaces  */
 158         int fflag = 0;          /* don't fork */
 159
 160         if ((name = strrchr(argv[0], '/')) != NULL)
 161                 ++name;
 162         else
 163                 name = argv[0];
 164         if (*name == '-')
 165                 ++name;
 166
 167         /*
 168          * All error reporting is done through syslog, unless -d is specified
 169          */
 170         openlog(name, LOG_PID | LOG_CONS, LOG_DAEMON);
 171
 172         opterr = 0;
 173         while ((op = getopt(argc, argv, "adfst:v")) != -1) {
 174                 switch (op) {
 175                 case 'a':
 176                         ++aflag;
 177                         break;
 178
 179                 case 'd':
 180                         ++dflag;
 181                         break;
 182
 183                 case 'f':
 184                         ++fflag;
 185                         break;
 186
 187                 case 's':
 188                         ++sflag;
 189                         break;
 190
 191                 case 't':
 192                         tftp_dir = optarg;
 193                         break;
 194
 195                 case 'v':
 196                         ++verbose;
 197                         break;
 198
 199                 default:
 200                         usage();
 201                         /* NOTREACHED */
 202                 }
 203         }
 204         ifname = argv[optind++];
 205         hostname =  ifname ? argv[optind] : NULL;
 206         if ((aflag && ifname) || (!aflag && ifname == NULL))
 207                 usage();
 208
 209         if (aflag)
 210                 init(NULL);
 211         else
 212                 init(ifname);
 213
 214         if (!fflag) {
 215                 if (daemon(0,0)) {
 216                         logmsg(LOG_ERR, "cannot fork");
 217                         exit(1);
 218                 }
 219         }
 220         rarp_loop();
 221         return(0);
 222 }
 223
 224 /*
 225  * Add to the interface list.
 226  */
 227 void
 228 init_one(struct ifreq *ifrp, char *target)
 229 {
 230         struct if_info *ii;
 231         struct sockaddr_dl *ll;
 232         int family;
 233         struct ifreq ifr;
 234
 235         family = ifrp->ifr_addr.sa_family;
 236         switch (family) {
 237
 238         case AF_INET:
 239 #if BSD >= 199100
 240         case AF_LINK:
 241 #endif
 242                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifrp->ifr_name));
 243                 if (ioctl(s, SIOCGIFFLAGS, (char *)&ifr) == -1) {
 244                         logmsg(LOG_ERR,
 245                             "SIOCGIFFLAGS: %.*s: %m",
 246                                 (int)sizeof(ifrp->ifr_name), ifrp->ifr_name);
 247                         exit(1);
 248                 }
 249                 if ((ifr.ifr_flags & IFF_UP) == 0 ||
 250                     (ifr.ifr_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) != 0)
 251                         return;
 252                 break;
 253
 254
 255         default:
 256                 return;
 257         }
 258
 259         /* Don't bother going any further if not the target interface */
 260         if (target != NULL &&
 261             strncmp(ifrp->ifr_name, target, sizeof(ifrp->ifr_name)) != 0)
 262                 return;
 263
 264         /* Look for interface in list */
 265         for (ii = iflist; ii != NULL; ii = ii->ii_next)
 266                 if (strncmp(ifrp->ifr_name, ii->ii_ifname,
 267                     sizeof(ifrp->ifr_name)) == 0)
 268                         break;
 269
 270         /* Allocate a new one if not found */
 271         if (ii == NULL) {
 272                 ii = (struct if_info *)malloc(sizeof(*ii));
 273                 if (ii == NULL) {
 274                         logmsg(LOG_ERR, "malloc: %m");
 275                         exit(1);
 276                 }
 277                 bzero(ii, sizeof(*ii));
 278                 ii->ii_fd = -1;
 279                 strncpy(ii->ii_ifname, ifrp->ifr_name, sizeof(ifrp->ifr_name));
 280                 ii->ii_ifname[sizeof(ii->ii_ifname) - 1] = '\0';
 281                 ii->ii_next = iflist;
 282                 iflist = ii;
 283         }
 284
 285         switch (family) {
 286
 287         case AF_INET:
 288                 if (ioctl(s, SIOCGIFADDR, (char *)&ifr) == -1) {
 289                         logmsg(LOG_ERR, "ipaddr SIOCGIFADDR: %s: %m",
 290                             ii->ii_ifname);
 291                         exit(1);
 292                 }
 293                 ii->ii_ipaddr = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr;
 294                 if (ioctl(s, SIOCGIFNETMASK, (char *)&ifr) == -1) {
 295                         logmsg(LOG_ERR, "SIOCGIFNETMASK: %m");
 296                         exit(1);
 297                 }
 298                 ii->ii_netmask = SATOSIN(&ifr.ifr_addr)->sin_addr.s_addr;
 299                 if (ii->ii_netmask == 0)
 300                         ii->ii_netmask = ipaddrtonetmask(ii->ii_ipaddr);
 301                 if (ii->ii_fd < 0) {
 302                         ii->ii_fd = rarp_open(ii->ii_ifname);
 303 #if BSD < 199100
 304                         /* Use BPF descriptor to get ethernet address. */
 305                         if (ioctl(ii->ii_fd, SIOCGIFADDR, (char *)&ifr) == -1) {
 306                                 logmsg(LOG_ERR, "eaddr SIOCGIFADDR: %s: %m",
 307                                     ii->ii_ifname);
 308                                 exit(1);
 309                         }
 310                         bcopy(&ifr.ifr_addr.sa_data[0], ii->ii_eaddr, 6);
 311 #endif
 312                 }
 313                 break;
 314
 315 #if BSD >= 199100
 316                 case AF_LINK:
 317                         ll = (struct sockaddr_dl *)&ifrp->ifr_addr;
 318                         if (ll->sdl_type == IFT_ETHER)
 319                                 bcopy(LLADDR(ll), ii->ii_eaddr, 6);
 320                         break;
 321 #endif
 322                 }
 323 }
 324 /*
 325  * Initialize all "candidate" interfaces that are in the system
 326  * configuration list.  A "candidate" is up, not loopback and not
 327  * point to point.
 328  */
 329 void
 330 init(char *target)
 331 {
 332         u_int n;
 333         struct ifreq *ifrp, *ifend;
 334         struct if_info *ii, *nii, *lii;
 335         struct ifconf ifc;
 336         struct ifreq ibuf[16];
 337
 338         if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
 339                 logmsg(LOG_ERR, "socket: %m");
 340                 exit(1);
 341         }
 342         ifc.ifc_len = sizeof ibuf;
 343         ifc.ifc_buf = (caddr_t)ibuf;
 344         if ((ioctl(s, SIOCGIFCONF, (char *)&ifc) == -1) ||
 345             ((u_int)ifc.ifc_len < sizeof(struct ifreq))) {
 346                 logmsg(LOG_ERR, "SIOCGIFCONF: %m");
 347                 exit(1);
 348         }
 349         ifrp = ibuf;
 350         ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 351         while (ifrp < ifend) {
 352                 init_one(ifrp, target);
 353
 354 #if BSD >= 199100
 355                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 356                 if (n < sizeof(*ifrp))
 357                         n = sizeof(*ifrp);
 358                 ifrp = (struct ifreq *)((char *)ifrp + n);
 359 #else
 360                 ++ifrp;
 361 #endif
 362         }
 363
 364         /* Throw away incomplete interfaces */
 365         lii = NULL;
 366         for (ii = iflist; ii != NULL; ii = nii) {
 367                 nii = ii->ii_next;
 368                 if (ii->ii_ipaddr == 0 ||
 369                     bcmp(ii->ii_eaddr, zero, 6) == 0) {
 370                         if (lii == NULL)
 371                                 iflist = nii;
 372                         else
 373                                 lii->ii_next = nii;
 374                         if (ii->ii_fd >= 0)
 375                                 close(ii->ii_fd);
 376                         free(ii);
 377                         continue;
 378                 }
 379                 lii = ii;
 380         }
 381
 382         /* Verbose stuff */
 383         if (verbose)
 384                 for (ii = iflist; ii != NULL; ii = ii->ii_next)
 385                         logmsg(LOG_DEBUG, "%s %s 0x%08lx %s",
 386                             ii->ii_ifname, intoa(ntohl(ii->ii_ipaddr)),
 387                             (u_long)ntohl(ii->ii_netmask), eatoa(ii->ii_eaddr));
 388 }
 389
 390 void
 391 usage(void)
 392 {
 393         fprintf(stderr, "usage: rarpd [-adfsv] [-t directory] [interface]\n");
 394         exit(1);
 395 }
 396
 397 int
 398 bpf_open(void)
 399 {
 400         int fd;
 401         int n = 0;
 402         char device[sizeof "/dev/bpf000"];
 403
 404         /*
 405          * Go through all the minors and find one that isn't in use.
 406          */
 407         do {
 408                 sprintf(device, "/dev/bpf%d", n++);
 409                 fd = open(device, O_RDWR);
 410         } while ((fd == -1) && (errno == EBUSY));
 411
 412         if (fd == -1) {
 413                 logmsg(LOG_ERR, "%s: %m", device);
 414                 exit(1);
 415         }
 416         return fd;
 417 }
 418
 419 /*
 420  * Open a BPF file and attach it to the interface named 'device'.
 421  * Set immediate mode, and set a filter that accepts only RARP requests.
 422  */
 423 int
 424 rarp_open(char *device)
 425 {
 426         int fd;
 427         struct ifreq ifr;
 428         u_int dlt;
 429         int immediate;
 430
 431         static struct bpf_insn insns[] = {
 432                 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 12),
 433                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ETHERTYPE_REVARP, 0, 3),
 434                 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 20),
 435                 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, REVARP_REQUEST, 0, 1),
 436                 BPF_STMT(BPF_RET|BPF_K, sizeof(struct ether_arp) +
 437                          sizeof(struct ether_header)),
 438                 BPF_STMT(BPF_RET|BPF_K, 0),
 439         };
 440         static struct bpf_program filter = {
 441                 sizeof insns / sizeof(insns[0]),
 442                 insns
 443         };
 444
 445         fd = bpf_open();
 446         /*
 447          * Set immediate mode so packets are processed as they arrive.
 448          */
 449         immediate = 1;
 450         if (ioctl(fd, BIOCIMMEDIATE, &immediate) == -1) {
 451                 logmsg(LOG_ERR, "BIOCIMMEDIATE: %m");
 452                 exit(1);
 453         }
 454         strncpy(ifr.ifr_name, device, sizeof ifr.ifr_name);
 455         if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) == -1) {
 456                 logmsg(LOG_ERR, "BIOCSETIF: %m");
 457                 exit(1);
 458         }
 459         /*
 460          * Check that the data link layer is an Ethernet; this code won't
 461          * work with anything else.
 462          */
 463         if (ioctl(fd, BIOCGDLT, (caddr_t)&dlt) == -1) {
 464                 logmsg(LOG_ERR, "BIOCGDLT: %m");
 465                 exit(1);
 466         }
 467         if (dlt != DLT_EN10MB) {
 468                 logmsg(LOG_ERR, "%s is not an ethernet", device);
 469                 exit(1);
 470         }
 471         /*
 472          * Set filter program.
 473          */
 474         if (ioctl(fd, BIOCSETF, (caddr_t)&filter) == -1) {
 475                 logmsg(LOG_ERR, "BIOCSETF: %m");
 476                 exit(1);
 477         }
 478         return fd;
 479 }
 480
 481 /*
 482  * Perform various sanity checks on the RARP request packet.  Return
 483  * false on failure and log the reason.
 484  */
 485 int
 486 rarp_check(u_char *p, u_int len)
 487 {
 488         struct ether_header *ep = (struct ether_header *)p;
 489         struct ether_arp *ap = (struct ether_arp *)(p + sizeof(*ep));
 490
 491         if (len < sizeof(*ep) + sizeof(*ap)) {
 492                 logmsg(LOG_ERR, "truncated request, got %u, expected %lu",
 493                                 len, (u_long)(sizeof(*ep) + sizeof(*ap)));
 494                 return 0;
 495         }
 496         /*
 497          * XXX This test might be better off broken out...
 498          */
 499         if (ntohs(ep->ether_type) != ETHERTYPE_REVARP ||
 500             ntohs(ap->arp_hrd) != ARPHRD_ETHER ||
 501             ntohs(ap->arp_op) != REVARP_REQUEST ||
 502             ntohs(ap->arp_pro) != ETHERTYPE_IP ||
 503             ap->arp_hln != 6 || ap->arp_pln != 4) {
 504                 logmsg(LOG_DEBUG, "request fails sanity check");
 505                 return 0;
 506         }
 507         if (bcmp((char *)&ep->ether_shost, (char *)&ap->arp_sha, 6) != 0) {
 508                 logmsg(LOG_DEBUG, "ether/arp sender address mismatch");
 509                 return 0;
 510         }
 511         if (bcmp((char *)&ap->arp_sha, (char *)&ap->arp_tha, 6) != 0) {
 512                 logmsg(LOG_DEBUG, "ether/arp target address mismatch");
 513                 return 0;
 514         }
 515         return 1;
 516 }
 517
 518 #ifndef FD_SETSIZE
 519 #define FD_SET(n, fdp) ((fdp)->fds_bits[0] |= (1 << (n)))
 520 #define FD_ISSET(n, fdp) ((fdp)->fds_bits[0] & (1 << (n)))
 521 #define FD_ZERO(fdp) ((fdp)->fds_bits[0] = 0)
 522 #endif
 523
 524 /*
 525  * Loop indefinitely listening for RARP requests on the
 526  * interfaces in 'iflist'.
 527  */
 528 void
 529 rarp_loop(void)
 530 {
 531         u_char *buf, *bp, *ep;
 532         int cc, fd;
 533         fd_set fds, listeners;
 534         int bufsize, maxfd = 0;
 535         struct if_info *ii;
 536
 537         if (iflist == NULL) {
 538                 logmsg(LOG_ERR, "no interfaces");
 539                 exit(1);
 540         }
 541         if (ioctl(iflist->ii_fd, BIOCGBLEN, (caddr_t)&bufsize) == -1) {
 542                 logmsg(LOG_ERR, "BIOCGBLEN: %m");
 543                 exit(1);
 544         }
 545         buf = malloc(bufsize);
 546         if (buf == NULL) {
 547                 logmsg(LOG_ERR, "malloc: %m");
 548                 exit(1);
 549         }
 550
 551         while (1) {
 552                 /*
 553                  * Find the highest numbered file descriptor for select().
 554                  * Initialize the set of descriptors to listen to.
 555                  */
 556                 FD_ZERO(&fds);
 557                 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
 558                         FD_SET(ii->ii_fd, &fds);
 559                         if (ii->ii_fd > maxfd)
 560                                 maxfd = ii->ii_fd;
 561                 }
 562                 listeners = fds;
 563                 if (select(maxfd + 1, &listeners, NULL, NULL, NULL) == -1) {
 564                         /* Don't choke when we get ptraced */
 565                         if (errno == EINTR)
 566                                 continue;
 567                         logmsg(LOG_ERR, "select: %m");
 568                         exit(1);
 569                 }
 570                 for (ii = iflist; ii != NULL; ii = ii->ii_next) {
 571                         fd = ii->ii_fd;
 572                         if (!FD_ISSET(fd, &listeners))
 573                                 continue;
 574                 again:
 575                         cc = read(fd, (char *)buf, bufsize);
 576                         /* Don't choke when we get ptraced */
 577                         if ((cc == -1) && (errno == EINTR))
 578                                 goto again;
 579 #if defined(SUNOS3) || defined(SUNOS4)
 580                         /*
 581                          * Due to a SunOS bug, after 2^31 bytes, the
 582                          * file offset overflows and read fails with
 583                          * EINVAL.  The lseek() to 0 will fix things.
 584                          */
 585                         if (cc == -1) {
 586                                 if (errno == EINVAL &&
 587                                     (long)(tell(fd) + bufsize) < 0) {
 588                                         lseek(fd, 0, 0);
 589                                         goto again;
 590                                 }
 591                                 logmsg(LOG_ERR, "read: %m");
 592                                 exit(1);
 593                         }
 594 #endif
 595
 596                         /* Loop through the packet(s) */
 597 #define bhp ((struct bpf_hdr *)bp)
 598                         bp = buf;
 599                         ep = bp + cc;
 600                         while (bp < ep) {
 601                                 u_int caplen, hdrlen;
 602
 603                                 caplen = bhp->bh_caplen;
 604                                 hdrlen = bhp->bh_hdrlen;
 605                                 if (rarp_check(bp + hdrlen, caplen))
 606                                         rarp_process(ii, bp + hdrlen, caplen);
 607                                 bp += BPF_WORDALIGN(hdrlen + caplen);
 608                         }
 609                 }
 610         }
 611 #undef bhp
 612 }
 613
 614 /*
 615  * True if this server can boot the host whose IP address is 'addr'.
 616  * This check is made by looking in the tftp directory for the
 617  * configuration file.
 618  */
 619 int
 620 rarp_bootable(u_long addr)
 621 {
 622 #ifdef HAVE_DIRENT_H
 623         struct dirent *dent;
 624 #else
 625         struct direct *dent;
 626 #endif
 627         DIR *d;
 628         char ipname[9];
 629         static DIR *dd = NULL;
 630
 631         sprintf(ipname, "%08lX", (u_long)ntohl(addr));
 632
 633         /*
 634          * If directory is already open, rewind it.  Otherwise, open it.
 635          */
 636         if ((d = dd) != NULL)
 637                 rewinddir(d);
 638         else {
 639                 if (chdir(tftp_dir) == -1) {
 640                         logmsg(LOG_ERR, "chdir: %s: %m", tftp_dir);
 641                         exit(1);
 642                 }
 643                 d = opendir(".");
 644                 if (d == NULL) {
 645                         logmsg(LOG_ERR, "opendir: %m");
 646                         exit(1);
 647                 }
 648                 dd = d;
 649         }
 650         while ((dent = readdir(d)) != NULL)
 651                 if (strncmp(dent->d_name, ipname, 8) == 0)
 652                         return 1;
 653         return 0;
 654 }
 655
 656 /*
 657  * Given a list of IP addresses, 'alist', return the first address that
 658  * is on network 'net'; 'netmask' is a mask indicating the network portion
 659  * of the address.
 660  */
 661 u_long
 662 choose_ipaddr(u_long **alist, u_long net, u_long netmask)
 663 {
 664         for (; *alist; ++alist)
 665                 if ((**alist & netmask) == net)
 666                         return **alist;
 667         return 0;
 668 }
 669
 670 /*
 671  * Answer the RARP request in 'pkt', on the interface 'ii'.  'pkt' has
 672  * already been checked for validity.  The reply is overlaid on the request.
 673  */
 674 void
 675 rarp_process(struct if_info *ii, u_char *pkt, u_int len)
 676 {
 677         struct ether_header *ep;
 678         struct hostent *hp;
 679         u_long target_ipaddr;
 680         char ename[256];
 681
 682         ep = (struct ether_header *)pkt;
 683         /* should this be arp_tha? */
 684         if (ether_ntohost(ename, (struct ether_addr *)&ep->ether_shost) != 0) {
 685                 logmsg(LOG_ERR, "cannot map %s to name",
 686                         eatoa(ep->ether_shost));
 687                 return;
 688         }
 689
 690         if ((hp = gethostbyname(ename)) == NULL) {
 691                 logmsg(LOG_ERR, "cannot map %s to IP address", ename);
 692                 return;
 693         }
 694
 695         /*
 696          * Choose correct address from list.
 697          */
 698         if (hp->h_addrtype != AF_INET) {
 699                 logmsg(LOG_ERR, "cannot handle non IP addresses for %s",
 700                                                                 ename);
 701                 return;
 702         }
 703         target_ipaddr = choose_ipaddr((u_long **)hp->h_addr_list,
 704                                       ii->ii_ipaddr & ii->ii_netmask,
 705                                       ii->ii_netmask);
 706         if (target_ipaddr == 0) {
 707                 logmsg(LOG_ERR, "cannot find %s on net %s",
 708                        ename, intoa(ntohl(ii->ii_ipaddr & ii->ii_netmask)));
 709                 return;
 710         }
 711         if (sflag || rarp_bootable(target_ipaddr))
 712                 rarp_reply(ii, ep, target_ipaddr, len);
 713         else if (verbose > 1)
 714                 logmsg(LOG_INFO, "%s %s at %s DENIED (not bootable)",
 715                     ii->ii_ifname,
 716                     eatoa(ep->ether_shost),
 717                     intoa(ntohl(target_ipaddr)));
 718 }
 719
 720 /*
 721  * Poke the kernel arp tables with the ethernet/ip address combinataion
 722  * given.  When processing a reply, we must do this so that the booting
 723  * host (i.e. the guy running rarpd), won't try to ARP for the hardware
 724  * address of the guy being booted (he cannot answer the ARP).
 725  */
 726 #if BSD >= 199200
 727 struct sockaddr_inarp sin_inarp = {
 728         sizeof(struct sockaddr_inarp), AF_INET, 0,
 729         {0},
 730         {0},
 731         0, 0
 732 };
 733 struct sockaddr_dl sin_dl = {
 734         sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
 735         0, ""
 736 };
 737 struct {
 738         struct rt_msghdr rthdr;
 739         char rtspace[512];
 740 } rtmsg;
 741
 742 void
 743 update_arptab(u_char *ep, u_long ipaddr)
 744 {
 745         int cc;
 746         struct sockaddr_inarp *ar, *ar2;
 747         struct sockaddr_dl *ll, *ll2;
 748         struct rt_msghdr *rt;
 749         int xtype, xindex;
 750         static pid_t pid;
 751         int r;
 752         static int seq;
 753
 754         r = socket(PF_ROUTE, SOCK_RAW, 0);
 755         if (r == -1) {
 756                 logmsg(LOG_ERR, "raw route socket: %m");
 757                 exit(1);
 758         }
 759         pid = getpid();
 760
 761         ar = &sin_inarp;
 762         ar->sin_addr.s_addr = ipaddr;
 763         ll = &sin_dl;
 764         bcopy(ep, LLADDR(ll), 6);
 765
 766         /* Get the type and interface index */
 767         rt = &rtmsg.rthdr;
 768         bzero(rt, sizeof(rtmsg));
 769         rt->rtm_version = RTM_VERSION;
 770         rt->rtm_addrs = RTA_DST;
 771         rt->rtm_type = RTM_GET;
 772         rt->rtm_seq = ++seq;
 773         ar2 = (struct sockaddr_inarp *)rtmsg.rtspace;
 774         bcopy(ar, ar2, sizeof(*ar));
 775         rt->rtm_msglen = sizeof(*rt) + sizeof(*ar);
 776         errno = 0;
 777         if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != ESRCH)) {
 778                 logmsg(LOG_ERR, "rtmsg get write: %m");
 779                 close(r);
 780                 return;
 781         }
 782         do {
 783                 cc = read(r, rt, sizeof(rtmsg));
 784         } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid));
 785         if (cc == -1) {
 786                 logmsg(LOG_ERR, "rtmsg get read: %m");
 787                 close(r);
 788                 return;
 789         }
 790         ll2 = (struct sockaddr_dl *)((u_char *)ar2 + ar2->sin_len);
 791         if (ll2->sdl_family != AF_LINK) {
 792                 /*
 793                  * XXX I think this means the ip address is not on a
 794                  * directly connected network (the family is AF_INET in
 795                  * this case).
 796                  */
 797                 logmsg(LOG_ERR, "bogus link family (%d) wrong net for %08lX?\n",
 798                     ll2->sdl_family, ipaddr);
 799                 close(r);
 800                 return;
 801         }
 802         xtype = ll2->sdl_type;
 803         xindex = ll2->sdl_index;
 804
 805         /* Set the new arp entry */
 806         bzero(rt, sizeof(rtmsg));
 807         rt->rtm_version = RTM_VERSION;
 808         rt->rtm_addrs = RTA_DST | RTA_GATEWAY;
 809         rt->rtm_inits = RTV_EXPIRE;
 810         rt->rtm_rmx.rmx_expire = time(0) + ARPSECS;
 811         rt->rtm_flags = RTF_HOST | RTF_STATIC;
 812         rt->rtm_type = RTM_ADD;
 813         rt->rtm_seq = ++seq;
 814
 815         bcopy(ar, ar2, sizeof(*ar));
 816
 817         ll2 = (struct sockaddr_dl *)((u_char *)ar2 + sizeof(*ar2));
 818         bcopy(ll, ll2, sizeof(*ll));
 819         ll2->sdl_type = xtype;
 820         ll2->sdl_index = xindex;
 821
 822         rt->rtm_msglen = sizeof(*rt) + sizeof(*ar2) + sizeof(*ll2);
 823         errno = 0;
 824         if ((write(r, rt, rt->rtm_msglen) == -1) && (errno != EEXIST)) {
 825                 logmsg(LOG_ERR, "rtmsg add write: %m");
 826                 close(r);
 827                 return;
 828         }
 829         do {
 830                 cc = read(r, rt, sizeof(rtmsg));
 831         } while (cc > 0 && (rt->rtm_seq != seq || rt->rtm_pid != pid));
 832         close(r);
 833         if (cc == -1) {
 834                 logmsg(LOG_ERR, "rtmsg add read: %m");
 835                 return;
 836         }
 837 }
 838 #else
 839 void
 840 update_arptab(u_char *ep, u_long ipaddr)
 841 {
 842         struct arpreq request;
 843         struct sockaddr_in *sin;
 844
 845         request.arp_flags = 0;
 846         sin = (struct sockaddr_in *)&request.arp_pa;
 847         sin->sin_family = AF_INET;
 848         sin->sin_addr.s_addr = ipaddr;
 849         request.arp_ha.sa_family = AF_UNSPEC;
 850         bcopy((char *)ep, (char *)request.arp_ha.sa_data, 6);
 851
 852         if (ioctl(s, SIOCSARP, (caddr_t)&request) == -1)
 853                 logmsg(LOG_ERR, "SIOCSARP: %m");
 854 }
 855 #endif
 856
 857 /*
 858  * Build a reverse ARP packet and sent it out on the interface.
 859  * 'ep' points to a valid REVARP_REQUEST.  The REVARP_REPLY is built
 860  * on top of the request, then written to the network.
 861  *
 862  * RFC 903 defines the ether_arp fields as follows.  The following comments
 863  * are taken (more or less) straight from this document.
 864  *
 865  * REVARP_REQUEST
 866  *
 867  * arp_sha is the hardware address of the sender of the packet.
 868  * arp_spa is undefined.
 869  * arp_tha is the 'target' hardware address.
 870  *   In the case where the sender wishes to determine his own
 871  *   protocol address, this, like arp_sha, will be the hardware
 872  *   address of the sender.
 873  * arp_tpa is undefined.
 874  *
 875  * REVARP_REPLY
 876  *
 877  * arp_sha is the hardware address of the responder (the sender of the
 878  *   reply packet).
 879  * arp_spa is the protocol address of the responder (see the note below).
 880  * arp_tha is the hardware address of the target, and should be the same as
 881  *   that which was given in the request.
 882  * arp_tpa is the protocol address of the target, that is, the desired address.
 883  *
 884  * Note that the requirement that arp_spa be filled in with the responder's
 885  * protocol is purely for convenience.  For instance, if a system were to use
 886  * both ARP and RARP, then the inclusion of the valid protocol-hardware
 887  * address pair (arp_spa, arp_sha) may eliminate the need for a subsequent
 888  * ARP request.
 889  */
 890 void
 891 rarp_reply(struct if_info *ii, struct ether_header *ep, u_long ipaddr,
 892                 u_int len)
 893 {
 894         u_int n;
 895         struct ether_arp *ap = (struct ether_arp *)(ep + 1);
 896
 897         update_arptab((u_char *)&ap->arp_sha, ipaddr);
 898
 899         /*
 900          * Build the rarp reply by modifying the rarp request in place.
 901          */
 902         ap->arp_op = htons(REVARP_REPLY);
 903
 904 #ifdef BROKEN_BPF
 905         ep->ether_type = ETHERTYPE_REVARP;
 906 #endif
 907         bcopy((char *)&ap->arp_sha, (char *)&ep->ether_dhost, 6);
 908         bcopy((char *)ii->ii_eaddr, (char *)&ep->ether_shost, 6);
 909         bcopy((char *)ii->ii_eaddr, (char *)&ap->arp_sha, 6);
 910
 911         bcopy((char *)&ipaddr, (char *)ap->arp_tpa, 4);
 912         /* Target hardware is unchanged. */
 913         bcopy((char *)&ii->ii_ipaddr, (char *)ap->arp_spa, 4);
 914
 915         /* Zero possible garbage after packet. */
 916         bzero((char *)ep + (sizeof(*ep) + sizeof(*ap)),
 917                         len - (sizeof(*ep) + sizeof(*ap)));
 918         n = write(ii->ii_fd, (char *)ep, len);
 919         if (n != len)
 920                 logmsg(LOG_ERR, "write: only %d of %d bytes written", n, len);
 921         if (verbose)
 922                 logmsg(LOG_INFO, "%s %s at %s REPLIED", ii->ii_ifname,
 923                     eatoa(ap->arp_tha),
 924                     intoa(ntohl(ipaddr)));
 925 }
 926
 927 /*
 928  * Get the netmask of an IP address.  This routine is used if
 929  * SIOCGIFNETMASK doesn't work.
 930  */
 931 u_long
 932 ipaddrtonetmask(u_long addr)
 933 {
 934         addr = ntohl(addr);
 935         if (IN_CLASSA(addr))
 936                 return htonl(IN_CLASSA_NET);
 937         if (IN_CLASSB(addr))
 938                 return htonl(IN_CLASSB_NET);
 939         if (IN_CLASSC(addr))
 940                 return htonl(IN_CLASSC_NET);
 941         logmsg(LOG_DEBUG, "unknown IP address class: %08lX", addr);
 942         return htonl(0xffffffff);
 943 }
 944
 945 /*
 946  * A faster replacement for inet_ntoa().
 947  */
 948 char *
 949 intoa(u_long addr)
 950 {
 951         char *cp;
 952         u_int byte;
 953         int n;
 954         static char buf[sizeof(".xxx.xxx.xxx.xxx")];
 955
 956         cp = &buf[sizeof buf];
 957         *--cp = '\0';
 958
 959         n = 4;
 960         do {
 961                 byte = addr & 0xff;
 962                 *--cp = byte % 10 + '0';
 963                 byte /= 10;
 964                 if (byte > 0) {
 965                         *--cp = byte % 10 + '0';
 966                         byte /= 10;
 967                         if (byte > 0)
 968                                 *--cp = byte + '0';
 969                 }
 970                 *--cp = '.';
 971                 addr >>= 8;
 972         } while (--n > 0);
 973
 974         return cp + 1;
 975 }
 976
 977 char *
 978 eatoa(u_char *ea)
 979 {
 980         static char buf[sizeof("xx:xx:xx:xx:xx:xx")];
 981
 982         sprintf(buf, "%x:%x:%x:%x:%x:%x",
 983             ea[0], ea[1], ea[2], ea[3], ea[4], ea[5]);
 984         return (buf);
 985 }
 986
 987 void
 988 logmsg(int pri, const char *fmt, ...)
 989 {
 990         va_list v;
 991         FILE *fp;
 992         char *newfmt;
 993
 994         va_start(v, fmt);
 995         if (dflag) {
 996                 if (pri == LOG_ERR)
 997                         fp = stderr;
 998                 else
 999                         fp = stdout;
1000                 if (expand_syslog_m(fmt, &newfmt) == -1) {
1001                         vfprintf(fp, fmt, v);
1002                 } else {
1003                         vfprintf(fp, newfmt, v);
1004                         free(newfmt);
1005                 }
1006                 fputs("\n", fp);
1007                 fflush(fp);
1008         } else {
1009                 vsyslog(pri, fmt, v);
1010         }
1011         va_end(v);
1012 }
1013
1014 int
1015 expand_syslog_m(const char *fmt, char **newfmt) {
1016         const char *str, *m;
1017         char *p, *np;
1018
1019         p = strdup("");
1020         str = fmt;
1021         while ((m = strstr(str, "%m")) != NULL) {
1022                 asprintf(&np, "%s%.*s%s", p, (int)(m - str),
1023                     str, strerror(errno));
1024                 free(p);
1025                 if (np == NULL) {
1026                         errno = ENOMEM;
1027                         return (-1);
1028                 }
1029                 p = np;
1030                 str = m + 2;
1031         }
1032
1033         if (*str != '\0') {
1034                 asprintf(&np, "%s%s", p, str);
1035                 free(p);
1036                 if (np == NULL) {
1037                         errno = ENOMEM;
1038                         return (-1);
1039                 }
1040                 p = np;
1041         }
1042
1043         *newfmt = p;
1044         return (0);
1045 }