slirp/ip_input.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1993
   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 the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
  30  * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp
  31  */
  32
  33 /*
  34  * Changes and additions relating to SLiRP are
  35  * Copyright (c) 1995 Danny Gasparovski.
  36  *
  37  * Please read the file COPYRIGHT for the
  38  * terms and conditions of the copyright.
  39  */
  40
  41 #include <slirp.h>
  42 #include <osdep.h>
  43 #include "ip_icmp.h"
  44
  45 static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp);
  46 static void ip_freef(Slirp *slirp, struct ipq *fp);
  47 static void ip_enq(register struct ipasfrag *p,
  48                    register struct ipasfrag *prev);
  49 static void ip_deq(register struct ipasfrag *p);
  50
  51 /*
  52  * IP initialization: fill in IP protocol switch table.
  53  * All protocols not implemented in kernel go to raw IP protocol handler.
  54  */
  55 void
  56 ip_init(Slirp *slirp)
  57 {
  58     slirp->ipq.ip_link.next = slirp->ipq.ip_link.prev = &slirp->ipq.ip_link;
  59     udp_init(slirp);
  60     tcp_init(slirp);
  61 }
  62
  63 /*
  64  * Ip input routine.  Checksum and byte swap header.  If fragmented
  65  * try to reassemble.  Process options.  Pass to next level.
  66  */
  67 void
  68 ip_input(struct mbuf *m)
  69 {
  70         Slirp *slirp = m->slirp;
  71         register struct ip *ip;
  72         int hlen;
  73
  74         DEBUG_CALL("ip_input");
  75         DEBUG_ARG("m = %lx", (long)m);
  76         DEBUG_ARG("m_len = %d", m->m_len);
  77
  78         if (m->m_len < sizeof (struct ip)) {
  79                 return;
  80         }
  81
  82         ip = mtod(m, struct ip *);
  83
  84         if (ip->ip_v != IPVERSION) {
  85                 goto bad;
  86         }
  87
  88         hlen = ip->ip_hl << 2;
  89         if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
  90           goto bad;                                  /* or packet too short */
  91         }
  92
  93         /* keep ip header intact for ICMP reply
  94          * ip->ip_sum = cksum(m, hlen);
  95          * if (ip->ip_sum) {
  96          */
  97         if(cksum(m,hlen)) {
  98           goto bad;
  99         }
 100
 101         /*
 102          * Convert fields to host representation.
 103          */
 104         NTOHS(ip->ip_len);
 105         if (ip->ip_len < hlen) {
 106                 goto bad;
 107         }
 108         NTOHS(ip->ip_id);
 109         NTOHS(ip->ip_off);
 110
 111         /*
 112          * Check that the amount of data in the buffers
 113          * is as at least much as the IP header would have us expect.
 114          * Trim mbufs if longer than we expect.
 115          * Drop packet if shorter than we expect.
 116          */
 117         if (m->m_len < ip->ip_len) {
 118                 goto bad;
 119         }
 120
 121         /* Should drop packet if mbuf too long? hmmm... */
 122         if (m->m_len > ip->ip_len)
 123            m_adj(m, ip->ip_len - m->m_len);
 124
 125         /* check ip_ttl for a correct ICMP reply */
 126         if(ip->ip_ttl==0) {
 127           icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
 128           goto bad;
 129         }
 130
 131         /*
 132          * If offset or IP_MF are set, must reassemble.
 133          * Otherwise, nothing need be done.
 134          * (We could look in the reassembly queue to see
 135          * if the packet was previously fragmented,
 136          * but it's not worth the time; just let them time out.)
 137          *
 138          * XXX This should fail, don't fragment yet
 139          */
 140         if (ip->ip_off &~ IP_DF) {
 141           register struct ipq *fp;
 142       struct qlink *l;
 143                 /*
 144                  * Look for queue of fragments
 145                  * of this datagram.
 146                  */
 147                 for (l = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link;
 148                      l = l->next) {
 149             fp = container_of(l, struct ipq, ip_link);
 150             if (ip->ip_id == fp->ipq_id &&
 151                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 152                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 153                     ip->ip_p == fp->ipq_p)
 154                     goto found;
 155         }
 156         fp = NULL;
 157         found:
 158
 159                 /*
 160                  * Adjust ip_len to not reflect header,
 161                  * set ip_mff if more fragments are expected,
 162                  * convert offset of this to bytes.
 163                  */
 164                 ip->ip_len -= hlen;
 165                 if (ip->ip_off & IP_MF)
 166                   ip->ip_tos |= 1;
 167                 else
 168                   ip->ip_tos &= ~1;
 169
 170                 ip->ip_off <<= 3;
 171
 172                 /*
 173                  * If datagram marked as having more fragments
 174                  * or if this is not the first fragment,
 175                  * attempt reassembly; if it succeeds, proceed.
 176                  */
 177                 if (ip->ip_tos & 1 || ip->ip_off) {
 178                         ip = ip_reass(slirp, ip, fp);
 179                         if (ip == NULL)
 180                                 return;
 181                         m = dtom(slirp, ip);
 182                 } else
 183                         if (fp)
 184                            ip_freef(slirp, fp);
 185
 186         } else
 187                 ip->ip_len -= hlen;
 188
 189         /*
 190          * Switch out to protocol's input routine.
 191          */
 192         switch (ip->ip_p) {
 193          case IPPROTO_TCP:
 194                 tcp_input(m, hlen, (struct socket *)NULL);
 195                 break;
 196          case IPPROTO_UDP:
 197                 udp_input(m, hlen);
 198                 break;
 199          case IPPROTO_ICMP:
 200                 icmp_input(m, hlen);
 201                 break;
 202          default:
 203                 m_free(m);
 204         }
 205         return;
 206 bad:
 207         m_freem(m);
 208         return;
 209 }
 210
 211 #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
 212 #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
 213 /*
 214  * Take incoming datagram fragment and try to
 215  * reassemble it into whole datagram.  If a chain for
 216  * reassembly of this datagram already exists, then it
 217  * is given as fp; otherwise have to make a chain.
 218  */
 219 static struct ip *
 220 ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
 221 {
 222         register struct mbuf *m = dtom(slirp, ip);
 223         register struct ipasfrag *q;
 224         int hlen = ip->ip_hl << 2;
 225         int i, next;
 226
 227         DEBUG_CALL("ip_reass");
 228         DEBUG_ARG("ip = %lx", (long)ip);
 229         DEBUG_ARG("fp = %lx", (long)fp);
 230         DEBUG_ARG("m = %lx", (long)m);
 231
 232         /*
 233          * Presence of header sizes in mbufs
 234          * would confuse code below.
 235          * Fragment m_data is concatenated.
 236          */
 237         m->m_data += hlen;
 238         m->m_len -= hlen;
 239
 240         /*
 241          * If first fragment to arrive, create a reassembly queue.
 242          */
 243         if (fp == NULL) {
 244           struct mbuf *t = m_get(slirp);
 245
 246           if (t == NULL) {
 247               goto dropfrag;
 248           }
 249           fp = mtod(t, struct ipq *);
 250           insque(&fp->ip_link, &slirp->ipq.ip_link);
 251           fp->ipq_ttl = IPFRAGTTL;
 252           fp->ipq_p = ip->ip_p;
 253           fp->ipq_id = ip->ip_id;
 254           fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
 255           fp->ipq_src = ip->ip_src;
 256           fp->ipq_dst = ip->ip_dst;
 257           q = (struct ipasfrag *)fp;
 258           goto insert;
 259         }
 260
 261         /*
 262          * Find a segment which begins after this one does.
 263          */
 264         for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
 265             q = q->ipf_next)
 266                 if (q->ipf_off > ip->ip_off)
 267                         break;
 268
 269         /*
 270          * If there is a preceding segment, it may provide some of
 271          * our data already.  If so, drop the data from the incoming
 272          * segment.  If it provides all of our data, drop us.
 273          */
 274         if (q->ipf_prev != &fp->frag_link) {
 275         struct ipasfrag *pq = q->ipf_prev;
 276                 i = pq->ipf_off + pq->ipf_len - ip->ip_off;
 277                 if (i > 0) {
 278                         if (i >= ip->ip_len)
 279                                 goto dropfrag;
 280                         m_adj(dtom(slirp, ip), i);
 281                         ip->ip_off += i;
 282                         ip->ip_len -= i;
 283                 }
 284         }
 285
 286         /*
 287          * While we overlap succeeding segments trim them or,
 288          * if they are completely covered, dequeue them.
 289          */
 290         while (q != (struct ipasfrag*)&fp->frag_link &&
 291             ip->ip_off + ip->ip_len > q->ipf_off) {
 292                 i = (ip->ip_off + ip->ip_len) - q->ipf_off;
 293                 if (i < q->ipf_len) {
 294                         q->ipf_len -= i;
 295                         q->ipf_off += i;
 296                         m_adj(dtom(slirp, q), i);
 297                         break;
 298                 }
 299                 q = q->ipf_next;
 300                 m_freem(dtom(slirp, q->ipf_prev));
 301                 ip_deq(q->ipf_prev);
 302         }
 303
 304 insert:
 305         /*
 306          * Stick new segment in its place;
 307          * check for complete reassembly.
 308          */
 309         ip_enq(iptofrag(ip), q->ipf_prev);
 310         next = 0;
 311         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link;
 312             q = q->ipf_next) {
 313                 if (q->ipf_off != next)
 314                         return NULL;
 315                 next += q->ipf_len;
 316         }
 317         if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
 318                 return NULL;
 319
 320         /*
 321          * Reassembly is complete; concatenate fragments.
 322          */
 323     q = fp->frag_link.next;
 324         m = dtom(slirp, q);
 325
 326         q = (struct ipasfrag *) q->ipf_next;
 327         while (q != (struct ipasfrag*)&fp->frag_link) {
 328           struct mbuf *t = dtom(slirp, q);
 329           q = (struct ipasfrag *) q->ipf_next;
 330           m_cat(m, t);
 331         }
 332
 333         /*
 334          * Create header for new ip packet by
 335          * modifying header of first packet;
 336          * dequeue and discard fragment reassembly header.
 337          * Make header visible.
 338          */
 339         q = fp->frag_link.next;
 340
 341         /*
 342          * If the fragments concatenated to an mbuf that's
 343          * bigger than the total size of the fragment, then and
 344          * m_ext buffer was alloced. But fp->ipq_next points to
 345          * the old buffer (in the mbuf), so we must point ip
 346          * into the new buffer.
 347          */
 348         if (m->m_flags & M_EXT) {
 349           int delta = (char *)q - m->m_dat;
 350           q = (struct ipasfrag *)(m->m_ext + delta);
 351         }
 352
 353     ip = fragtoip(q);
 354         ip->ip_len = next;
 355         ip->ip_tos &= ~1;
 356         ip->ip_src = fp->ipq_src;
 357         ip->ip_dst = fp->ipq_dst;
 358         remque(&fp->ip_link);
 359         (void) m_free(dtom(slirp, fp));
 360         m->m_len += (ip->ip_hl << 2);
 361         m->m_data -= (ip->ip_hl << 2);
 362
 363         return ip;
 364
 365 dropfrag:
 366         m_freem(m);
 367         return NULL;
 368 }
 369
 370 /*
 371  * Free a fragment reassembly header and all
 372  * associated datagrams.
 373  */
 374 static void
 375 ip_freef(Slirp *slirp, struct ipq *fp)
 376 {
 377         register struct ipasfrag *q, *p;
 378
 379         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) {
 380                 p = q->ipf_next;
 381                 ip_deq(q);
 382                 m_freem(dtom(slirp, q));
 383         }
 384         remque(&fp->ip_link);
 385         (void) m_free(dtom(slirp, fp));
 386 }
 387
 388 /*
 389  * Put an ip fragment on a reassembly chain.
 390  * Like insque, but pointers in middle of structure.
 391  */
 392 static void
 393 ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)
 394 {
 395         DEBUG_CALL("ip_enq");
 396         DEBUG_ARG("prev = %lx", (long)prev);
 397         p->ipf_prev =  prev;
 398         p->ipf_next = prev->ipf_next;
 399         ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
 400         prev->ipf_next = p;
 401 }
 402
 403 /*
 404  * To ip_enq as remque is to insque.
 405  */
 406 static void
 407 ip_deq(register struct ipasfrag *p)
 408 {
 409         ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
 410         ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
 411 }
 412
 413 /*
 414  * IP timer processing;
 415  * if a timer expires on a reassembly
 416  * queue, discard it.
 417  */
 418 void
 419 ip_slowtimo(Slirp *slirp)
 420 {
 421     struct qlink *l;
 422
 423         DEBUG_CALL("ip_slowtimo");
 424
 425     l = slirp->ipq.ip_link.next;
 426
 427         if (l == NULL)
 428            return;
 429
 430     while (l != &slirp->ipq.ip_link) {
 431         struct ipq *fp = container_of(l, struct ipq, ip_link);
 432         l = l->next;
 433                 if (--fp->ipq_ttl == 0) {
 434                         ip_freef(slirp, fp);
 435                 }
 436     }
 437 }
 438
 439 /*
 440  * Do option processing on a datagram,
 441  * possibly discarding it if bad options are encountered,
 442  * or forwarding it if source-routed.
 443  * Returns 1 if packet has been forwarded/freed,
 444  * 0 if the packet should be processed further.
 445  */
 446
 447 #ifdef notdef
 448
 449 int
 450 ip_dooptions(m)
 451         struct mbuf *m;
 452 {
 453         register struct ip *ip = mtod(m, struct ip *);
 454         register u_char *cp;
 455         register struct ip_timestamp *ipt;
 456         register struct in_ifaddr *ia;
 457         int opt, optlen, cnt, off, code, type, forward = 0;
 458         struct in_addr *sin, dst;
 459 typedef uint32_t n_time;
 460         n_time ntime;
 461
 462         dst = ip->ip_dst;
 463         cp = (u_char *)(ip + 1);
 464         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 465         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 466                 opt = cp[IPOPT_OPTVAL];
 467                 if (opt == IPOPT_EOL)
 468                         break;
 469                 if (opt == IPOPT_NOP)
 470                         optlen = 1;
 471                 else {
 472                         optlen = cp[IPOPT_OLEN];
 473                         if (optlen <= 0 || optlen > cnt) {
 474                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 475                                 goto bad;
 476                         }
 477                 }
 478                 switch (opt) {
 479
 480                 default:
 481                         break;
 482
 483                 /*
 484                  * Source routing with record.
 485                  * Find interface with current destination address.
 486                  * If none on this machine then drop if strictly routed,
 487                  * or do nothing if loosely routed.
 488                  * Record interface address and bring up next address
 489                  * component.  If strictly routed make sure next
 490                  * address is on directly accessible net.
 491                  */
 492                 case IPOPT_LSRR:
 493                 case IPOPT_SSRR:
 494                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 495                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 496                                 goto bad;
 497                         }
 498                         ipaddr.sin_addr = ip->ip_dst;
 499                         ia = (struct in_ifaddr *)
 500                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 501                         if (ia == 0) {
 502                                 if (opt == IPOPT_SSRR) {
 503                                         type = ICMP_UNREACH;
 504                                         code = ICMP_UNREACH_SRCFAIL;
 505                                         goto bad;
 506                                 }
 507                                 /*
 508                                  * Loose routing, and not at next destination
 509                                  * yet; nothing to do except forward.
 510                                  */
 511                                 break;
 512                         }
 513                         off--;                  / * 0 origin *  /
 514                         if (off > optlen - sizeof(struct in_addr)) {
 515                                 /*
 516                                  * End of source route.  Should be for us.
 517                                  */
 518                                 save_rte(cp, ip->ip_src);
 519                                 break;
 520                         }
 521                         /*
 522                          * locate outgoing interface
 523                          */
 524                         bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
 525                             sizeof(ipaddr.sin_addr));
 526                         if (opt == IPOPT_SSRR) {
 527 #define INA     struct in_ifaddr *
 528 #define SA      struct sockaddr *
 529                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
 530                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 531                         } else
 532                                 ia = ip_rtaddr(ipaddr.sin_addr);
 533                         if (ia == 0) {
 534                                 type = ICMP_UNREACH;
 535                                 code = ICMP_UNREACH_SRCFAIL;
 536                                 goto bad;
 537                         }
 538                         ip->ip_dst = ipaddr.sin_addr;
 539                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 540                             (caddr_t)(cp + off), sizeof(struct in_addr));
 541                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 542                         /*
 543                          * Let ip_intr's mcast routing check handle mcast pkts
 544                          */
 545                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 546                         break;
 547
 548                 case IPOPT_RR:
 549                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 550                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 551                                 goto bad;
 552                         }
 553                         /*
 554                          * If no space remains, ignore.
 555                          */
 556                         off--;                   * 0 origin *
 557                         if (off > optlen - sizeof(struct in_addr))
 558                                 break;
 559                         bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
 560                             sizeof(ipaddr.sin_addr));
 561                         /*
 562                          * locate outgoing interface; if we're the destination,
 563                          * use the incoming interface (should be same).
 564                          */
 565                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
 566                             (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
 567                                 type = ICMP_UNREACH;
 568                                 code = ICMP_UNREACH_HOST;
 569                                 goto bad;
 570                         }
 571                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 572                             (caddr_t)(cp + off), sizeof(struct in_addr));
 573                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 574                         break;
 575
 576                 case IPOPT_TS:
 577                         code = cp - (u_char *)ip;
 578                         ipt = (struct ip_timestamp *)cp;
 579                         if (ipt->ipt_len < 5)
 580                                 goto bad;
 581                         if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
 582                                 if (++ipt->ipt_oflw == 0)
 583                                         goto bad;
 584                                 break;
 585                         }
 586                         sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
 587                         switch (ipt->ipt_flg) {
 588
 589                         case IPOPT_TS_TSONLY:
 590                                 break;
 591
 592                         case IPOPT_TS_TSANDADDR:
 593                                 if (ipt->ipt_ptr + sizeof(n_time) +
 594                                     sizeof(struct in_addr) > ipt->ipt_len)
 595                                         goto bad;
 596                                 ipaddr.sin_addr = dst;
 597                                 ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
 598                                                             m->m_pkthdr.rcvif);
 599                                 if (ia == 0)
 600                                         continue;
 601                                 bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
 602                                     (caddr_t)sin, sizeof(struct in_addr));
 603                                 ipt->ipt_ptr += sizeof(struct in_addr);
 604                                 break;
 605
 606                         case IPOPT_TS_PRESPEC:
 607                                 if (ipt->ipt_ptr + sizeof(n_time) +
 608                                     sizeof(struct in_addr) > ipt->ipt_len)
 609                                         goto bad;
 610                                 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
 611                                     sizeof(struct in_addr));
 612                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
 613                                         continue;
 614                                 ipt->ipt_ptr += sizeof(struct in_addr);
 615                                 break;
 616
 617                         default:
 618                                 goto bad;
 619                         }
 620                         ntime = iptime();
 621                         bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
 622                             sizeof(n_time));
 623                         ipt->ipt_ptr += sizeof(n_time);
 624                 }
 625         }
 626         if (forward) {
 627                 ip_forward(m, 1);
 628                 return (1);
 629         }
 630         return (0);
 631 bad:
 632         icmp_error(m, type, code, 0, 0);
 633
 634         return (1);
 635 }
 636
 637 #endif /* notdef */
 638
 639 /*
 640  * Strip out IP options, at higher
 641  * level protocol in the kernel.
 642  * Second argument is buffer to which options
 643  * will be moved, and return value is their length.
 644  * (XXX) should be deleted; last arg currently ignored.
 645  */
 646 void
 647 ip_stripoptions(register struct mbuf *m, struct mbuf *mopt)
 648 {
 649         register int i;
 650         struct ip *ip = mtod(m, struct ip *);
 651         register caddr_t opts;
 652         int olen;
 653
 654         olen = (ip->ip_hl<<2) - sizeof (struct ip);
 655         opts = (caddr_t)(ip + 1);
 656         i = m->m_len - (sizeof (struct ip) + olen);
 657         memcpy(opts, opts  + olen, (unsigned)i);
 658         m->m_len -= olen;
 659
 660         ip->ip_hl = sizeof(struct ip) >> 2;
 661 }