bsd/netinet/in_bootp.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  *  Copyright (c) 1988-1999 Apple Computer, Inc. All Rights Reserved
  24  */
  25
  26 /*
  27  * bootp.c
  28  * - be a BOOTP client over a particular interface to retrieve
  29  *   the IP address, netmask, and router
  30  */
  31
  32 /*
  33  * Modification History
  34  *
  35  * February 19, 1999    Dieter Siegmund (dieter@apple.com)
  36  * - completely rewritten
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/types.h>
  41 #include <mach/boolean.h>
  42 #include <sys/kernel.h>
  43 #include <sys/errno.h>
  44 #include <sys/file.h>
  45 #include <sys/uio.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/time.h>
  48 #include <sys/mbuf.h>
  49 #include <sys/vnode.h>
  50 #include <sys/socket.h>
  51 #include <sys/socketvar.h>
  52 #include <net/if.h>
  53 #include <net/if_dl.h>
  54 #include <net/if_types.h>
  55 #include <net/route.h>
  56 #include <netinet/in.h>
  57 #include <netinet/in_systm.h>
  58 #include <netinet/if_ether.h>
  59 #include <netinet/ip.h>
  60 #include <netinet/ip_var.h>
  61 #include <netinet/udp.h>
  62 #include <netinet/udp_var.h>
  63 #include <netinet/ip_icmp.h>
  64 #include <netinet/bootp.h>
  65 #include <sys/systm.h>
  66 #include <sys/malloc.h>
  67
  68
  69 #ifdef  BOOTP_DEBUG
  70 #define dprintf(x) printf x;
  71 #else   BOOTP_DEBUG
  72 #define dprintf(x)
  73 #endif  BOOTP_DEBUG
  74
  75 /* ip address formatting macros */
  76 #define IP_FORMAT       "%d.%d.%d.%d"
  77 #define IP_CH(ip)       ((u_char *)ip)
  78 #define IP_LIST(ip)     IP_CH(ip)[0],IP_CH(ip)[1],IP_CH(ip)[2],IP_CH(ip)[3]
  79
  80 /* tag values (from RFC 2132) */
  81 #define TAG_PAD                 0
  82 #define TAG_END                 255
  83 #define TAG_SUBNET_MASK         1
  84 #define TAG_ROUTER              3
  85 #define RFC_OPTIONS_MAGIC       { 99, 130, 83, 99 }
  86 static unsigned char            rfc_magic[4] = RFC_OPTIONS_MAGIC;
  87
  88
  89 static struct sockaddr_in       blank_sin = { sizeof(struct sockaddr_in),
  90                                               AF_INET };
  91
  92 static __inline__ void
  93 print_reply(struct bootp *bp, int bp_len)
  94 {
  95         int i, j, len;
  96
  97         printf("bp_op = ");
  98         if (bp->bp_op == BOOTREQUEST) printf("BOOTREQUEST\n");
  99         else if (bp->bp_op == BOOTREPLY) printf("BOOTREPLY\n");
 100         else
 101         {
 102                 i = bp->bp_op;
 103                 printf("%d\n", i);
 104         }
 105
 106         i = bp->bp_htype;
 107         printf("bp_htype = %d\n", i);
 108
 109         len = bp->bp_hlen;
 110         printf("bp_hlen = %d\n", len);
 111
 112         i = bp->bp_hops;
 113         printf("bp_hops = %d\n", i);
 114
 115         printf("bp_xid = %lu\n", bp->bp_xid);
 116
 117         printf("bp_secs = %u\n", bp->bp_secs);
 118
 119         printf("bp_ciaddr = " IP_FORMAT "\n", IP_LIST(&bp->bp_ciaddr));
 120         printf("bp_yiaddr = " IP_FORMAT "\n", IP_LIST(&bp->bp_yiaddr));
 121         printf("bp_siaddr = " IP_FORMAT "\n", IP_LIST(&bp->bp_siaddr));
 122         printf("bp_giaddr = " IP_FORMAT "\n", IP_LIST(&bp->bp_giaddr));
 123
 124         printf("bp_chaddr = ");
 125         for (j = 0; j < len; j++)
 126         {
 127                 i = bp->bp_chaddr[j];
 128                 printf("%0x", i);
 129                 if (j < (len - 1)) printf(":");
 130         }
 131         printf("\n");
 132
 133         printf("bp_sname = %s\n", bp->bp_sname);
 134         printf("bp_file = %s\n", bp->bp_file);
 135 }
 136
 137 static __inline__ void
 138 print_reply_short(struct bootp *bp, int bp_len)
 139 {
 140         printf("bp_yiaddr = " IP_FORMAT "\n", IP_LIST(&bp->bp_yiaddr));
 141         printf("bp_sname = %s\n", bp->bp_sname);
 142 }
 143
 144
 145 static __inline__ long
 146 random_range(long bottom, long top)
 147 {
 148     long number = top - bottom + 1;
 149     long range_size = LONG_MAX / number;
 150     return (((long)random()) / range_size + bottom);
 151 }
 152
 153 /*
 154  * Function: make_bootp_request
 155  * Purpose:
 156  *   Create a "blank" bootp packet.
 157  */
 158 static void
 159 make_bootp_request(struct bootp_packet * pkt,
 160                    u_char * hwaddr, u_char hwtype, u_char hwlen)
 161 {
 162     bzero(pkt, sizeof (*pkt));
 163     pkt->bp_ip.ip_v = IPVERSION;
 164     pkt->bp_ip.ip_hl = sizeof (struct ip) >> 2;
 165     pkt->bp_ip.ip_id = htons(ip_id++);
 166     pkt->bp_ip.ip_ttl = MAXTTL;
 167     pkt->bp_ip.ip_p = IPPROTO_UDP;
 168     pkt->bp_ip.ip_src.s_addr = 0;
 169     pkt->bp_ip.ip_dst.s_addr = htonl(INADDR_BROADCAST);
 170     pkt->bp_udp.uh_sport = htons(IPPORT_BOOTPC);
 171     pkt->bp_udp.uh_dport = htons(IPPORT_BOOTPS);
 172     pkt->bp_udp.uh_sum = 0;
 173     pkt->bp_bootp.bp_op = BOOTREQUEST;
 174     pkt->bp_bootp.bp_htype = hwtype;
 175     pkt->bp_bootp.bp_hlen = hwlen;
 176     pkt->bp_bootp.bp_ciaddr.s_addr = 0;
 177     bcopy(hwaddr, pkt->bp_bootp.bp_chaddr, hwlen);
 178     bcopy(rfc_magic, pkt->bp_bootp.bp_vend, sizeof(rfc_magic));
 179     pkt->bp_bootp.bp_vend[4] = TAG_END;
 180     pkt->bp_udp.uh_ulen = htons(sizeof(pkt->bp_udp) + sizeof(pkt->bp_bootp));
 181     pkt->bp_ip.ip_len = htons(sizeof(struct ip) + ntohs(pkt->bp_udp.uh_ulen));
 182     pkt->bp_ip.ip_sum = 0;
 183     return;
 184 }
 185
 186 /*
 187  * Function: ip_pkt_to_mbuf
 188  * Purpose:
 189  *   Put the given IP packet into an mbuf, calculate the
 190  *   IP checksum.
 191  */
 192 struct mbuf *
 193 ip_pkt_to_mbuf(caddr_t pkt, int pktsize)
 194 {
 195     struct ip *         ip;
 196     struct mbuf *       m;
 197
 198     m = (struct mbuf *)m_devget(pkt, pktsize, 0, 0, 0);
 199     if (m == 0) {
 200         printf("bootp: ip_pkt_to_mbuf: m_devget failed\n");
 201         return 0;
 202     }
 203     m->m_flags |= M_BCAST;
 204     /* Compute the checksum */
 205     ip = mtod(m, struct ip *);
 206     ip->ip_sum = 0;
 207     ip->ip_sum = in_cksum(m, sizeof (struct ip));
 208     return (m);
 209 }
 210
 211 static __inline__ u_char *
 212 link_address(struct sockaddr_dl * dl_p)
 213 {
 214     return (dl_p->sdl_data + dl_p->sdl_nlen);
 215 }
 216
 217 static __inline__ void
 218 link_print(struct sockaddr_dl * dl_p)
 219 {
 220     int i;
 221
 222 #if 0
 223     printf("len %d index %d family %d type 0x%x nlen %d alen %d"
 224            " slen %d addr ", dl_p->sdl_len,
 225            dl_p->sdl_index,  dl_p->sdl_family, dl_p->sdl_type,
 226            dl_p->sdl_nlen, dl_p->sdl_alen, dl_p->sdl_slen);
 227 #endif 0
 228     for (i = 0; i < dl_p->sdl_alen; i++)
 229         printf("%s%x", i ? ":" : "",
 230                (link_address(dl_p))[i]);
 231     printf("\n");
 232     return;
 233 }
 234
 235 static struct sockaddr_dl *
 236 link_from_ifnet(struct ifnet * ifp)
 237 {
 238     struct ifaddr * addr;
 239
 240 /*    for (addr = ifp->if_addrlist; addr; addr = addr->ifa_next) */
 241
 242     TAILQ_FOREACH(addr, &ifp->if_addrhead, ifa_link) {
 243         if (addr->ifa_addr->sa_family == AF_LINK) {
 244             struct sockaddr_dl * dl_p = (struct sockaddr_dl *)(addr->ifa_addr);
 245
 246             return (dl_p);
 247         }
 248     }
 249     return (NULL);
 250 }
 251
 252 /*
 253  * Function: send_bootp_request
 254  * Purpose:
 255  *     Send the request by calling the interface's output routine
 256  *     bypassing routing code.
 257  */
 258 static int
 259 send_bootp_request(struct ifnet * ifp, struct socket * so,
 260                    struct bootp_packet * pkt)
 261 {
 262     struct mbuf *       m;
 263     struct sockaddr_in  sin;
 264
 265     /* Address to send to */
 266     sin = blank_sin;
 267     sin.sin_port = htons(IPPORT_BOOTPS);
 268     sin.sin_addr.s_addr = INADDR_BROADCAST;
 269
 270     m = ip_pkt_to_mbuf((caddr_t)pkt, sizeof(*pkt));
 271     return (dlil_output((u_long) ifp, m, 0, (struct sockaddr *)&sin, 0));
 272 }
 273
 274 /*
 275  * Function: receive_packet
 276  * Purpose:
 277  *   Return a received packet or an error if none available.
 278  */
 279 int
 280 receive_packet(struct socket * so, caddr_t pp, int psize)
 281 {
 282     struct iovec        aiov;
 283     struct uio          auio;
 284     int                 rcvflg;
 285     int                 error;
 286
 287     aiov.iov_base = pp;
 288     aiov.iov_len = psize;
 289     auio.uio_iov = &aiov;
 290     auio.uio_iovcnt = 1;
 291     auio.uio_segflg = UIO_SYSSPACE;
 292     auio.uio_offset = 0;
 293     auio.uio_resid = psize;
 294     auio.uio_rw = UIO_READ;
 295     rcvflg = MSG_WAITALL;
 296
 297     error = soreceive(so, (struct sockaddr **) 0, &auio, 0, 0, &rcvflg);
 298     return (error);
 299 }
 300
 301 /*
 302  * Function: bootp_timeout
 303  * Purpose:
 304  *   Wakeup the process waiting for something on a socket.
 305  */
 306 static void
 307 bootp_timeout(struct socket * * socketflag)
 308 {
 309     struct socket * so = *socketflag;
 310     boolean_t   funnel_state;
 311
 312     dprintf(("bootp: timeout\n"));
 313
 314     funnel_state = thread_funnel_set(network_flock,TRUE);
 315     *socketflag = NULL;
 316     sowakeup(so, &so->so_rcv);
 317     (void) thread_funnel_set(network_flock, FALSE);
 318     return;
 319 }
 320
 321 #define TAG_OFFSET      0
 322 #define LEN_OFFSET      1
 323 #define OPTION_OFFSET   2
 324
 325 void *
 326 packet_option(struct bootp * pkt, u_char t)
 327 {
 328     void *              buffer = pkt->bp_vend + sizeof(rfc_magic);
 329     int                 len;
 330     unsigned char       option_len;
 331     void *              ret = NULL;
 332     unsigned char *     scan;
 333     unsigned char       tag = TAG_PAD;
 334
 335     len = sizeof(pkt->bp_vend) - sizeof(rfc_magic);
 336     for (scan = buffer; len > 0; ) {
 337         tag = scan[TAG_OFFSET];
 338         if (tag == TAG_END) /* we hit the end of the options */
 339             break;
 340         if (tag == TAG_PAD) { /* discard pad characters */
 341             scan++;
 342             len--;
 343         }
 344         else {
 345             if (t == tag && ret == NULL)
 346                 ret = scan + OPTION_OFFSET;
 347             option_len = scan[LEN_OFFSET];
 348             len -= (option_len + 2);
 349             scan += (option_len + 2);
 350         }
 351     }
 352     if (len < 0 || tag != TAG_END) { /* we ran off the end */
 353         if (len < 0) {
 354             dprintf(("bootp: error parsing options\n"));
 355         }
 356         else {
 357             dprintf(("bootp: end tag missing\n"));
 358         }
 359         ret = NULL;
 360     }
 361     return (ret);
 362 }
 363
 364 /*
 365  * Function: rate_packet
 366  * Purpose:
 367  *   Return an integer point rating value for the given bootp packet.
 368  *   If yiaddr non-zero, the packet gets a rating of 1.
 369  *   Another point is given if the packet contains the subnet mask,
 370  *   and another if the router is present.
 371  */
 372 #define GOOD_RATING     3
 373 static __inline__ int
 374 rate_packet(struct bootp * pkt)
 375 {
 376     int rating = 0;
 377
 378     if (pkt->bp_yiaddr.s_addr) {
 379         struct in_addr * ip;
 380
 381         rating++;
 382         ip = (struct in_addr *)packet_option(pkt, TAG_SUBNET_MASK);
 383         if (ip)
 384             rating++;
 385         ip = (struct in_addr *)packet_option(pkt, TAG_ROUTER);
 386         if (ip)
 387             rating++;
 388     }
 389     return (rating);
 390 }
 391
 392 #define INITIAL_WAIT_SECS               4
 393 #define MAX_WAIT_SECS                   64
 394 #define GATHER_TIME_SECS                2
 395 #define RAND_TICKS                      (hz)    /* one second */
 396
 397 /*
 398  * Function: bootp_loop
 399  * Purpose:
 400  *   Do the actual BOOTP protocol.
 401  *   The algorithm sends out a packet, waits for a response.
 402  *   We try max_try times, waiting in an exponentially increasing
 403  *   amount of time.  Once we receive a good response, we start
 404  *   a new time period called the "gather time", during which we
 405  *   either find the perfect packet (one that has ip, mask and router)
 406  *   or we continue to gather responses.  At the end of the gather period,
 407  *   we use the best response gathered.
 408  */
 409 static int
 410 bootp_loop(struct socket * so, struct ifnet * ifp, int max_try,
 411            struct in_addr * iaddr_p, struct in_addr * netmask_p,
 412            struct in_addr * router_p)
 413 {
 414     struct timeval              current_time;
 415     struct sockaddr_dl *        dl_p;
 416     int                         error = 0;
 417     char *                      hwaddr;
 418     int                         hwlen;
 419     char                        hwtype = 0;
 420     struct bootp_packet *       request = NULL;
 421     struct bootp *              reply = NULL;
 422     struct bootp *              saved_reply = NULL;
 423     struct timeval              start_time;
 424     u_long                      xid;
 425     int                         retry;
 426     struct socket *             timeflag;
 427     int                         wait_ticks = INITIAL_WAIT_SECS * hz;
 428
 429     /* get the hardware address from the interface */
 430     dl_p = link_from_ifnet(ifp);
 431     if (dl_p == NULL) {
 432         printf("bootp: can't get link address\n");
 433         return (ENXIO);
 434     }
 435
 436     printf("bootp: h/w addr ");
 437     link_print(dl_p);
 438
 439     hwaddr = link_address(dl_p);
 440     hwlen = dl_p->sdl_alen;
 441     switch (dl_p->sdl_type) {
 442         case IFT_ETHER:
 443             hwtype = ARPHRD_ETHER;
 444             break;
 445         default:
 446             printf("bootp: hardware type %d not supported\n",
 447                    dl_p->sdl_type);
 448             panic("bootp: hardware type not supported");
 449             break;
 450     }
 451
 452     /* set transaction id and remember the start time */
 453     microtime(&start_time);
 454     current_time = start_time;
 455     xid = random();
 456
 457     /* make a request/reply packet */
 458     request = (struct bootp_packet *)kalloc(sizeof(*request));
 459     make_bootp_request(request, hwaddr, hwtype, hwlen);
 460     reply = (struct bootp *)kalloc(sizeof(*reply));
 461     saved_reply = (struct bootp *)kalloc(sizeof(*saved_reply));
 462     iaddr_p->s_addr = 0;
 463     printf("bootp: sending request");
 464     for (retry = 0; retry < max_try; retry++) {
 465         int             gather_count = 0;
 466         int             last_rating = 0;
 467
 468         /* Send the request */
 469         printf(".");
 470         request->bp_bootp.bp_secs = htons((u_short)(current_time.tv_sec
 471                                                     - start_time.tv_sec));
 472         request->bp_bootp.bp_xid = htonl(xid);
 473         error = send_bootp_request(ifp, so, request);
 474         if (error)
 475             goto cleanup;
 476
 477         timeflag = so;
 478         wait_ticks += random_range(-RAND_TICKS, RAND_TICKS);
 479         dprintf(("bootp: waiting %d ticks\n", wait_ticks));
 480         timeout(bootp_timeout, &timeflag, wait_ticks);
 481
 482         while (TRUE) {
 483             error = receive_packet(so, (caddr_t)reply, sizeof(*reply));
 484             if (error == 0) {
 485                 dprintf(("\nbootp: received packet\n"));
 486                 if (ntohl(reply->bp_xid) == xid
 487                     && reply->bp_yiaddr.s_addr
 488                     && bcmp(reply->bp_chaddr, hwaddr, hwlen) == 0) {
 489                     int rating;
 490 #ifdef  BOOTP_DEBUG
 491                     print_reply_short(reply, sizeof(*reply));
 492 #endif BOOTP_DEBUG
 493                     rating = rate_packet(reply);
 494                     if (rating > last_rating)
 495                         *saved_reply = *reply;
 496                     if (rating >= GOOD_RATING) {
 497                         untimeout(bootp_timeout, &timeflag);
 498                         goto save_values;
 499                     }
 500                     if (gather_count == 0) {
 501                         untimeout(bootp_timeout, &timeflag);
 502                         timeflag = so;
 503                         timeout(bootp_timeout, &timeflag,
 504                                 hz * GATHER_TIME_SECS);
 505                     }
 506                     gather_count++;
 507                 }
 508                 else {
 509                     dprintf(("bootp: packet ignored\n"));
 510                 }
 511             }
 512             else if ((error != EWOULDBLOCK)) {
 513                 break;
 514             }
 515             else if (timeflag == NULL) { /* timed out */
 516                 if (gather_count) {
 517                     dprintf(("bootp: gathering time has expired"));
 518                     goto save_values; /* we have a packet */
 519                 }
 520                 break; /* retry */
 521             }
 522             else
 523                 sbwait(&so->so_rcv);
 524         }
 525         if (error && (error != EWOULDBLOCK)) {
 526             dprintf(("bootp: failed to receive packets: %d\n", error));
 527             untimeout(bootp_timeout, &timeflag);
 528             goto cleanup;
 529         }
 530         wait_ticks *= 2;
 531         if (wait_ticks > (MAX_WAIT_SECS * hz))
 532             wait_ticks = MAX_WAIT_SECS * hz;
 533         xid++;
 534         microtime(&current_time);
 535     }
 536     error = ETIMEDOUT;
 537     goto cleanup;
 538
 539  save_values:
 540     error = 0;
 541     printf("\nbootp: got response from %s (" IP_FORMAT ")\n",
 542            saved_reply->bp_sname, IP_LIST(&saved_reply->bp_siaddr));
 543     /* return the ip address */
 544     *iaddr_p = saved_reply->bp_yiaddr;
 545     {
 546         struct in_addr * ip;
 547         ip = (struct in_addr *)packet_option(saved_reply, TAG_SUBNET_MASK);
 548         if (ip)
 549             *netmask_p = *ip;
 550         ip = (struct in_addr *)packet_option(saved_reply, TAG_ROUTER);
 551         if (ip)
 552             *router_p = *ip;
 553     }
 554
 555  cleanup:
 556     if (request)
 557         kfree((caddr_t)request, sizeof (*request));
 558     if (reply)
 559         kfree((caddr_t)reply, sizeof(*reply));
 560     if (saved_reply)
 561         kfree((caddr_t)saved_reply, sizeof(*saved_reply));
 562     return (error);
 563 }
 564
 565 /*
 566  * Routine: bootp
 567  * Function:
 568  *      Use the BOOTP protocol to resolve what our IP address should be
 569  *      on a particular interface.
 570  */
 571 int bootp(struct ifnet * ifp, struct in_addr * iaddr_p, int max_try,
 572           struct in_addr * netmask_p, struct in_addr * router_p,
 573           struct proc * procp)
 574 {
 575     boolean_t                   addr_set = FALSE;
 576     struct ifreq                ifr;
 577     int                         error;
 578     struct socket *             so = NULL;
 579
 580     /* get a socket */
 581     error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
 582     if (error) {
 583         dprintf(("bootp: socreate failed %d\n", error));
 584         return (error);
 585     }
 586
 587     /* assign the all-zeroes address */
 588     bzero(&ifr, sizeof(ifr));
 589     sprintf(ifr.ifr_name, "%s%d", ifp->if_name, ifp->if_unit);
 590     *((struct sockaddr_in *)&ifr.ifr_addr) = blank_sin;
 591     error = ifioctl(so, SIOCSIFADDR, (caddr_t)&ifr, procp);
 592     if (error) {
 593         dprintf(("bootp: SIOCSIFADDR all-zeroes IP failed: %d\n",
 594                  error));
 595         goto cleanup;
 596     }
 597     dprintf(("bootp: all-zeroes IP address assigned\n"));
 598     addr_set = TRUE;
 599
 600     { /* bind the socket */
 601         struct sockaddr_in * sin;
 602
 603         sin = _MALLOC(sizeof(struct sockaddr_in), M_IFADDR, M_NOWAIT);
 604         sin->sin_len = sizeof(struct sockaddr_in);
 605         sin->sin_family = AF_INET;
 606         sin->sin_port = htons(IPPORT_BOOTPC);
 607         sin->sin_addr.s_addr = INADDR_ANY;
 608         error = sobind(so, (struct sockaddr *) sin);
 609
 610         FREE(sin, M_IFADDR);
 611         if (error) {
 612             dprintf(("bootp: sobind failed, %d\n", error));
 613             goto cleanup;
 614         }
 615         so->so_state |= SS_NBIO;
 616     }
 617     /* do the protocol */
 618     error = bootp_loop(so, ifp, max_try, iaddr_p, netmask_p, router_p);
 619
 620  cleanup:
 621     if (so) {
 622         if (addr_set) {
 623             (void) ifioctl(so, SIOCDIFADDR, (caddr_t) &ifr, procp);
 624         }
 625         soclose(so);
 626     }
 627     return (error);
 628 }
 629
 630 /*
 631  * Function: in_bootp
 632  * Purpose:
 633  *   This is deprecated API.  Once SIOCAUTOADDR is eliminated from
 634  *   the system (IOEthernet class as well), this routine can be removed.
 635  */
 636 int
 637 in_bootp(struct ifnet * ifp, struct sockaddr_in * sin, u_char my_enaddr[6])
 638 {
 639     return (EOPNOTSUPP);
 640 }