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     icmp_init(slirp);
  62 }
  63
  64 /*
  65  * Ip input routine.  Checksum and byte swap header.  If fragmented
  66  * try to reassemble.  Process options.  Pass to next level.
  67  */
  68 void
  69 ip_input(struct mbuf *m)
  70 {
  71         Slirp *slirp = m->slirp;
  72         register struct ip *ip;
  73         int hlen;
  74
  75         DEBUG_CALL("ip_input");
  76         DEBUG_ARG("m = %lx", (long)m);
  77         DEBUG_ARG("m_len = %d", m->m_len);
  78
  79         if (m->m_len < sizeof (struct ip)) {
  80                 return;
  81         }
  82
  83         ip = mtod(m, struct ip *);
  84
  85         if (ip->ip_v != IPVERSION) {
  86                 goto bad;
  87         }
  88
  89         hlen = ip->ip_hl << 2;
  90         if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
  91           goto bad;                                  /* or packet too short */
  92         }
  93
  94         /* keep ip header intact for ICMP reply
  95          * ip->ip_sum = cksum(m, hlen);
  96          * if (ip->ip_sum) {
  97          */
  98         if(cksum(m,hlen)) {
  99           goto bad;
 100         }
 101
 102         /*
 103          * Convert fields to host representation.
 104          */
 105         NTOHS(ip->ip_len);
 106         if (ip->ip_len < hlen) {
 107                 goto bad;
 108         }
 109         NTOHS(ip->ip_id);
 110         NTOHS(ip->ip_off);
 111
 112         /*
 113          * Check that the amount of data in the buffers
 114          * is as at least much as the IP header would have us expect.
 115          * Trim mbufs if longer than we expect.
 116          * Drop packet if shorter than we expect.
 117          */
 118         if (m->m_len < ip->ip_len) {
 119                 goto bad;
 120         }
 121
 122         /* Should drop packet if mbuf too long? hmmm... */
 123         if (m->m_len > ip->ip_len)
 124            m_adj(m, ip->ip_len - m->m_len);
 125
 126         /* check ip_ttl for a correct ICMP reply */
 127         if(ip->ip_ttl==0) {
 128           icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
 129           goto bad;
 130         }
 131
 132         /*
 133          * If offset or IP_MF are set, must reassemble.
 134          * Otherwise, nothing need be done.
 135          * (We could look in the reassembly queue to see
 136          * if the packet was previously fragmented,
 137          * but it's not worth the time; just let them time out.)
 138          *
 139          * XXX This should fail, don't fragment yet
 140          */
 141         if (ip->ip_off &~ IP_DF) {
 142           register struct ipq *fp;
 143       struct qlink *l;
 144                 /*
 145                  * Look for queue of fragments
 146                  * of this datagram.
 147                  */
 148                 for (l = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link;
 149                      l = l->next) {
 150             fp = container_of(l, struct ipq, ip_link);
 151             if (ip->ip_id == fp->ipq_id &&
 152                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 153                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 154                     ip->ip_p == fp->ipq_p)
 155                     goto found;
 156         }
 157         fp = NULL;
 158         found:
 159
 160                 /*
 161                  * Adjust ip_len to not reflect header,
 162                  * set ip_mff if more fragments are expected,
 163                  * convert offset of this to bytes.
 164                  */
 165                 ip->ip_len -= hlen;
 166                 if (ip->ip_off & IP_MF)
 167                   ip->ip_tos |= 1;
 168                 else
 169                   ip->ip_tos &= ~1;
 170
 171                 ip->ip_off <<= 3;
 172
 173                 /*
 174                  * If datagram marked as having more fragments
 175                  * or if this is not the first fragment,
 176                  * attempt reassembly; if it succeeds, proceed.
 177                  */
 178                 if (ip->ip_tos & 1 || ip->ip_off) {
 179                         ip = ip_reass(slirp, ip, fp);
 180                         if (ip == NULL)
 181                                 return;
 182                         m = dtom(slirp, ip);
 183                 } else
 184                         if (fp)
 185                            ip_freef(slirp, fp);
 186
 187         } else
 188                 ip->ip_len -= hlen;
 189
 190         /*
 191          * Switch out to protocol's input routine.
 192          */
 193         switch (ip->ip_p) {
 194          case IPPROTO_TCP:
 195                 tcp_input(m, hlen, (struct socket *)NULL);
 196                 break;
 197          case IPPROTO_UDP:
 198                 udp_input(m, hlen);
 199                 break;
 200          case IPPROTO_ICMP:
 201                 icmp_input(m, hlen);
 202                 break;
 203          default:
 204                 m_free(m);
 205         }
 206         return;
 207 bad:
 208         m_free(m);
 209         return;
 210 }
 211
 212 #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
 213 #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
 214 /*
 215  * Take incoming datagram fragment and try to
 216  * reassemble it into whole datagram.  If a chain for
 217  * reassembly of this datagram already exists, then it
 218  * is given as fp; otherwise have to make a chain.
 219  */
 220 static struct ip *
 221 ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
 222 {
 223         register struct mbuf *m = dtom(slirp, ip);
 224         register struct ipasfrag *q;
 225         int hlen = ip->ip_hl << 2;
 226         int i, next;
 227
 228         DEBUG_CALL("ip_reass");
 229         DEBUG_ARG("ip = %lx", (long)ip);
 230         DEBUG_ARG("fp = %lx", (long)fp);
 231         DEBUG_ARG("m = %lx", (long)m);
 232
 233         /*
 234          * Presence of header sizes in mbufs
 235          * would confuse code below.
 236          * Fragment m_data is concatenated.
 237          */
 238         m->m_data += hlen;
 239         m->m_len -= hlen;
 240
 241         /*
 242          * If first fragment to arrive, create a reassembly queue.
 243          */
 244         if (fp == NULL) {
 245           struct mbuf *t = m_get(slirp);
 246
 247           if (t == NULL) {
 248               goto dropfrag;
 249           }
 250           fp = mtod(t, struct ipq *);
 251           insque(&fp->ip_link, &slirp->ipq.ip_link);
 252           fp->ipq_ttl = IPFRAGTTL;
 253           fp->ipq_p = ip->ip_p;
 254           fp->ipq_id = ip->ip_id;
 255           fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
 256           fp->ipq_src = ip->ip_src;
 257           fp->ipq_dst = ip->ip_dst;
 258           q = (struct ipasfrag *)fp;
 259           goto insert;
 260         }
 261
 262         /*
 263          * Find a segment which begins after this one does.
 264          */
 265         for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
 266             q = q->ipf_next)
 267                 if (q->ipf_off > ip->ip_off)
 268                         break;
 269
 270         /*
 271          * If there is a preceding segment, it may provide some of
 272          * our data already.  If so, drop the data from the incoming
 273          * segment.  If it provides all of our data, drop us.
 274          */
 275         if (q->ipf_prev != &fp->frag_link) {
 276         struct ipasfrag *pq = q->ipf_prev;
 277                 i = pq->ipf_off + pq->ipf_len - ip->ip_off;
 278                 if (i > 0) {
 279                         if (i >= ip->ip_len)
 280                                 goto dropfrag;
 281                         m_adj(dtom(slirp, ip), i);
 282                         ip->ip_off += i;
 283                         ip->ip_len -= i;
 284                 }
 285         }
 286
 287         /*
 288          * While we overlap succeeding segments trim them or,
 289          * if they are completely covered, dequeue them.
 290          */
 291         while (q != (struct ipasfrag*)&fp->frag_link &&
 292             ip->ip_off + ip->ip_len > q->ipf_off) {
 293                 i = (ip->ip_off + ip->ip_len) - q->ipf_off;
 294                 if (i < q->ipf_len) {
 295                         q->ipf_len -= i;
 296                         q->ipf_off += i;
 297                         m_adj(dtom(slirp, q), i);
 298                         break;
 299                 }
 300                 q = q->ipf_next;
 301                 m_free(dtom(slirp, q->ipf_prev));
 302                 ip_deq(q->ipf_prev);
 303         }
 304
 305 insert:
 306         /*
 307          * Stick new segment in its place;
 308          * check for complete reassembly.
 309          */
 310         ip_enq(iptofrag(ip), q->ipf_prev);
 311         next = 0;
 312         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link;
 313             q = q->ipf_next) {
 314                 if (q->ipf_off != next)
 315                         return NULL;
 316                 next += q->ipf_len;
 317         }
 318         if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
 319                 return NULL;
 320
 321         /*
 322          * Reassembly is complete; concatenate fragments.
 323          */
 324     q = fp->frag_link.next;
 325         m = dtom(slirp, q);
 326
 327         q = (struct ipasfrag *) q->ipf_next;
 328         while (q != (struct ipasfrag*)&fp->frag_link) {
 329           struct mbuf *t = dtom(slirp, q);
 330           q = (struct ipasfrag *) q->ipf_next;
 331           m_cat(m, t);
 332         }
 333
 334         /*
 335          * Create header for new ip packet by
 336          * modifying header of first packet;
 337          * dequeue and discard fragment reassembly header.
 338          * Make header visible.
 339          */
 340         q = fp->frag_link.next;
 341
 342         /*
 343          * If the fragments concatenated to an mbuf that's
 344          * bigger than the total size of the fragment, then and
 345          * m_ext buffer was alloced. But fp->ipq_next points to
 346          * the old buffer (in the mbuf), so we must point ip
 347          * into the new buffer.
 348          */
 349         if (m->m_flags & M_EXT) {
 350           int delta = (char *)q - m->m_dat;
 351           q = (struct ipasfrag *)(m->m_ext + delta);
 352         }
 353
 354     ip = fragtoip(q);
 355         ip->ip_len = next;
 356         ip->ip_tos &= ~1;
 357         ip->ip_src = fp->ipq_src;
 358         ip->ip_dst = fp->ipq_dst;
 359         remque(&fp->ip_link);
 360         (void) m_free(dtom(slirp, fp));
 361         m->m_len += (ip->ip_hl << 2);
 362         m->m_data -= (ip->ip_hl << 2);
 363
 364         return ip;
 365
 366 dropfrag:
 367         m_free(m);
 368         return NULL;
 369 }
 370
 371 /*
 372  * Free a fragment reassembly header and all
 373  * associated datagrams.
 374  */
 375 static void
 376 ip_freef(Slirp *slirp, struct ipq *fp)
 377 {
 378         register struct ipasfrag *q, *p;
 379
 380         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) {
 381                 p = q->ipf_next;
 382                 ip_deq(q);
 383                 m_free(dtom(slirp, q));
 384         }
 385         remque(&fp->ip_link);
 386         (void) m_free(dtom(slirp, fp));
 387 }
 388
 389 /*
 390  * Put an ip fragment on a reassembly chain.
 391  * Like insque, but pointers in middle of structure.
 392  */
 393 static void
 394 ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)
 395 {
 396         DEBUG_CALL("ip_enq");
 397         DEBUG_ARG("prev = %lx", (long)prev);
 398         p->ipf_prev =  prev;
 399         p->ipf_next = prev->ipf_next;
 400         ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
 401         prev->ipf_next = p;
 402 }
 403
 404 /*
 405  * To ip_enq as remque is to insque.
 406  */
 407 static void
 408 ip_deq(register struct ipasfrag *p)
 409 {
 410         ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
 411         ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
 412 }
 413
 414 /*
 415  * IP timer processing;
 416  * if a timer expires on a reassembly
 417  * queue, discard it.
 418  */
 419 void
 420 ip_slowtimo(Slirp *slirp)
 421 {
 422     struct qlink *l;
 423
 424         DEBUG_CALL("ip_slowtimo");
 425
 426     l = slirp->ipq.ip_link.next;
 427
 428         if (l == NULL)
 429            return;
 430
 431     while (l != &slirp->ipq.ip_link) {
 432         struct ipq *fp = container_of(l, struct ipq, ip_link);
 433         l = l->next;
 434                 if (--fp->ipq_ttl == 0) {
 435                         ip_freef(slirp, fp);
 436                 }
 437     }
 438 }
 439
 440 /*
 441  * Do option processing on a datagram,
 442  * possibly discarding it if bad options are encountered,
 443  * or forwarding it if source-routed.
 444  * Returns 1 if packet has been forwarded/freed,
 445  * 0 if the packet should be processed further.
 446  */
 447
 448 #ifdef notdef
 449
 450 int
 451 ip_dooptions(m)
 452         struct mbuf *m;
 453 {
 454         register struct ip *ip = mtod(m, struct ip *);
 455         register u_char *cp;
 456         register struct ip_timestamp *ipt;
 457         register struct in_ifaddr *ia;
 458         int opt, optlen, cnt, off, code, type, forward = 0;
 459         struct in_addr *sin, dst;
 460 typedef uint32_t n_time;
 461         n_time ntime;
 462
 463         dst = ip->ip_dst;
 464         cp = (u_char *)(ip + 1);
 465         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 466         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 467                 opt = cp[IPOPT_OPTVAL];
 468                 if (opt == IPOPT_EOL)
 469                         break;
 470                 if (opt == IPOPT_NOP)
 471                         optlen = 1;
 472                 else {
 473                         optlen = cp[IPOPT_OLEN];
 474                         if (optlen <= 0 || optlen > cnt) {
 475                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 476                                 goto bad;
 477                         }
 478                 }
 479                 switch (opt) {
 480
 481                 default:
 482                         break;
 483
 484                 /*
 485                  * Source routing with record.
 486                  * Find interface with current destination address.
 487                  * If none on this machine then drop if strictly routed,
 488                  * or do nothing if loosely routed.
 489                  * Record interface address and bring up next address
 490                  * component.  If strictly routed make sure next
 491                  * address is on directly accessible net.
 492                  */
 493                 case IPOPT_LSRR:
 494                 case IPOPT_SSRR:
 495                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 496                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 497                                 goto bad;
 498                         }
 499                         ipaddr.sin_addr = ip->ip_dst;
 500                         ia = (struct in_ifaddr *)
 501                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 502                         if (ia == 0) {
 503                                 if (opt == IPOPT_SSRR) {
 504                                         type = ICMP_UNREACH;
 505                                         code = ICMP_UNREACH_SRCFAIL;
 506                                         goto bad;
 507                                 }
 508                                 /*
 509                                  * Loose routing, and not at next destination
 510                                  * yet; nothing to do except forward.
 511                                  */
 512                                 break;
 513                         }
 514                         off--; /* 0 origin */
 515                         if (off > optlen - sizeof(struct in_addr)) {
 516                                 /*
 517                                  * End of source route.  Should be for us.
 518                                  */
 519                                 save_rte(cp, ip->ip_src);
 520                                 break;
 521                         }
 522                         /*
 523                          * locate outgoing interface
 524                          */
 525                         bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
 526                             sizeof(ipaddr.sin_addr));
 527                         if (opt == IPOPT_SSRR) {
 528 #define INA     struct in_ifaddr *
 529 #define SA      struct sockaddr *
 530                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
 531                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 532                         } else
 533                                 ia = ip_rtaddr(ipaddr.sin_addr);
 534                         if (ia == 0) {
 535                                 type = ICMP_UNREACH;
 536                                 code = ICMP_UNREACH_SRCFAIL;
 537                                 goto bad;
 538                         }
 539                         ip->ip_dst = ipaddr.sin_addr;
 540                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 541                             (caddr_t)(cp + off), sizeof(struct in_addr));
 542                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 543                         /*
 544                          * Let ip_intr's mcast routing check handle mcast pkts
 545                          */
 546                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 547                         break;
 548
 549                 case IPOPT_RR:
 550                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 551                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 552                                 goto bad;
 553                         }
 554                         /*
 555                          * If no space remains, ignore.
 556                          */
 557                         off--; /* 0 origin */
 558                         if (off > optlen - sizeof(struct in_addr))
 559                                 break;
 560                         bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
 561                             sizeof(ipaddr.sin_addr));
 562                         /*
 563                          * locate outgoing interface; if we're the destination,
 564                          * use the incoming interface (should be same).
 565                          */
 566                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
 567                             (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
 568                                 type = ICMP_UNREACH;
 569                                 code = ICMP_UNREACH_HOST;
 570                                 goto bad;
 571                         }
 572                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 573                             (caddr_t)(cp + off), sizeof(struct in_addr));
 574                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 575                         break;
 576
 577                 case IPOPT_TS:
 578                         code = cp - (u_char *)ip;
 579                         ipt = (struct ip_timestamp *)cp;
 580                         if (ipt->ipt_len < 5)
 581                                 goto bad;
 582                         if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
 583                                 if (++ipt->ipt_oflw == 0)
 584                                         goto bad;
 585                                 break;
 586                         }
 587                         sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
 588                         switch (ipt->ipt_flg) {
 589
 590                         case IPOPT_TS_TSONLY:
 591                                 break;
 592
 593                         case IPOPT_TS_TSANDADDR:
 594                                 if (ipt->ipt_ptr + sizeof(n_time) +
 595                                     sizeof(struct in_addr) > ipt->ipt_len)
 596                                         goto bad;
 597                                 ipaddr.sin_addr = dst;
 598                                 ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
 599                                                             m->m_pkthdr.rcvif);
 600                                 if (ia == 0)
 601                                         continue;
 602                                 bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
 603                                     (caddr_t)sin, sizeof(struct in_addr));
 604                                 ipt->ipt_ptr += sizeof(struct in_addr);
 605                                 break;
 606
 607                         case IPOPT_TS_PRESPEC:
 608                                 if (ipt->ipt_ptr + sizeof(n_time) +
 609                                     sizeof(struct in_addr) > ipt->ipt_len)
 610                                         goto bad;
 611                                 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
 612                                     sizeof(struct in_addr));
 613                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
 614                                         continue;
 615                                 ipt->ipt_ptr += sizeof(struct in_addr);
 616                                 break;
 617
 618                         default:
 619                                 goto bad;
 620                         }
 621                         ntime = iptime();
 622                         bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
 623                             sizeof(n_time));
 624                         ipt->ipt_ptr += sizeof(n_time);
 625                 }
 626         }
 627         if (forward) {
 628                 ip_forward(m, 1);
 629                 return (1);
 630         }
 631         return (0);
 632 bad:
 633         icmp_error(m, type, code, 0, 0);
 634
 635         return (1);
 636 }
 637
 638 #endif /* notdef */
 639
 640 /*
 641  * Strip out IP options, at higher
 642  * level protocol in the kernel.
 643  * Second argument is buffer to which options
 644  * will be moved, and return value is their length.
 645  * (XXX) should be deleted; last arg currently ignored.
 646  */
 647 void
 648 ip_stripoptions(register struct mbuf *m, struct mbuf *mopt)
 649 {
 650         register int i;
 651         struct ip *ip = mtod(m, struct ip *);
 652         register caddr_t opts;
 653         int olen;
 654
 655         olen = (ip->ip_hl<<2) - sizeof (struct ip);
 656         opts = (caddr_t)(ip + 1);
 657         i = m->m_len - (sizeof (struct ip) + olen);
 658         memcpy(opts, opts  + olen, (unsigned)i);
 659         m->m_len -= olen;
 660
 661         ip->ip_hl = sizeof(struct ip) >> 2;
 662 }