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 <qemu/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 void ip_cleanup(Slirp *slirp)
  65 {
  66     udp_cleanup(slirp);
  67     tcp_cleanup(slirp);
  68     icmp_cleanup(slirp);
  69 }
  70
  71 /*
  72  * Ip input routine.  Checksum and byte swap header.  If fragmented
  73  * try to reassemble.  Process options.  Pass to next level.
  74  */
  75 void
  76 ip_input(struct mbuf *m)
  77 {
  78         Slirp *slirp = m->slirp;
  79         register struct ip *ip;
  80         int hlen;
  81
  82         DEBUG_CALL("ip_input");
  83         DEBUG_ARG("m = %p", m);
  84         DEBUG_ARG("m_len = %d", m->m_len);
  85
  86         if (m->m_len < sizeof (struct ip)) {
  87                 return;
  88         }
  89
  90         ip = mtod(m, struct ip *);
  91
  92         if (ip->ip_v != IPVERSION) {
  93                 goto bad;
  94         }
  95
  96         hlen = ip->ip_hl << 2;
  97         if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
  98           goto bad;                                  /* or packet too short */
  99         }
 100
 101         /* keep ip header intact for ICMP reply
 102          * ip->ip_sum = cksum(m, hlen);
 103          * if (ip->ip_sum) {
 104          */
 105         if(cksum(m,hlen)) {
 106           goto bad;
 107         }
 108
 109         /*
 110          * Convert fields to host representation.
 111          */
 112         NTOHS(ip->ip_len);
 113         if (ip->ip_len < hlen) {
 114                 goto bad;
 115         }
 116         NTOHS(ip->ip_id);
 117         NTOHS(ip->ip_off);
 118
 119         /*
 120          * Check that the amount of data in the buffers
 121          * is as at least much as the IP header would have us expect.
 122          * Trim mbufs if longer than we expect.
 123          * Drop packet if shorter than we expect.
 124          */
 125         if (m->m_len < ip->ip_len) {
 126                 goto bad;
 127         }
 128
 129         /* Should drop packet if mbuf too long? hmmm... */
 130         if (m->m_len > ip->ip_len)
 131            m_adj(m, ip->ip_len - m->m_len);
 132
 133         /* check ip_ttl for a correct ICMP reply */
 134         if(ip->ip_ttl==0) {
 135           icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
 136           goto bad;
 137         }
 138
 139         /*
 140          * If offset or IP_MF are set, must reassemble.
 141          * Otherwise, nothing need be done.
 142          * (We could look in the reassembly queue to see
 143          * if the packet was previously fragmented,
 144          * but it's not worth the time; just let them time out.)
 145          *
 146          * XXX This should fail, don't fragment yet
 147          */
 148         if (ip->ip_off &~ IP_DF) {
 149           register struct ipq *fp;
 150       struct qlink *l;
 151                 /*
 152                  * Look for queue of fragments
 153                  * of this datagram.
 154                  */
 155                 for (l = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link;
 156                      l = l->next) {
 157             fp = container_of(l, struct ipq, ip_link);
 158             if (ip->ip_id == fp->ipq_id &&
 159                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 160                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 161                     ip->ip_p == fp->ipq_p)
 162                     goto found;
 163         }
 164         fp = NULL;
 165         found:
 166
 167                 /*
 168                  * Adjust ip_len to not reflect header,
 169                  * set ip_mff if more fragments are expected,
 170                  * convert offset of this to bytes.
 171                  */
 172                 ip->ip_len -= hlen;
 173                 if (ip->ip_off & IP_MF)
 174                   ip->ip_tos |= 1;
 175                 else
 176                   ip->ip_tos &= ~1;
 177
 178                 ip->ip_off <<= 3;
 179
 180                 /*
 181                  * If datagram marked as having more fragments
 182                  * or if this is not the first fragment,
 183                  * attempt reassembly; if it succeeds, proceed.
 184                  */
 185                 if (ip->ip_tos & 1 || ip->ip_off) {
 186                         ip = ip_reass(slirp, ip, fp);
 187                         if (ip == NULL)
 188                                 return;
 189                         m = dtom(slirp, ip);
 190                 } else
 191                         if (fp)
 192                            ip_freef(slirp, fp);
 193
 194         } else
 195                 ip->ip_len -= hlen;
 196
 197         /*
 198          * Switch out to protocol's input routine.
 199          */
 200         switch (ip->ip_p) {
 201          case IPPROTO_TCP:
 202                 tcp_input(m, hlen, (struct socket *)NULL);
 203                 break;
 204          case IPPROTO_UDP:
 205                 udp_input(m, hlen);
 206                 break;
 207          case IPPROTO_ICMP:
 208                 icmp_input(m, hlen);
 209                 break;
 210          default:
 211                 m_free(m);
 212         }
 213         return;
 214 bad:
 215         m_free(m);
 216 }
 217
 218 #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
 219 #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
 220 /*
 221  * Take incoming datagram fragment and try to
 222  * reassemble it into whole datagram.  If a chain for
 223  * reassembly of this datagram already exists, then it
 224  * is given as fp; otherwise have to make a chain.
 225  */
 226 static struct ip *
 227 ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
 228 {
 229         register struct mbuf *m = dtom(slirp, ip);
 230         register struct ipasfrag *q;
 231         int hlen = ip->ip_hl << 2;
 232         int i, next;
 233
 234         DEBUG_CALL("ip_reass");
 235         DEBUG_ARG("ip = %p", ip);
 236         DEBUG_ARG("fp = %p", fp);
 237         DEBUG_ARG("m = %p", m);
 238
 239         /*
 240          * Presence of header sizes in mbufs
 241          * would confuse code below.
 242          * Fragment m_data is concatenated.
 243          */
 244         m->m_data += hlen;
 245         m->m_len -= hlen;
 246
 247         /*
 248          * If first fragment to arrive, create a reassembly queue.
 249          */
 250         if (fp == NULL) {
 251           struct mbuf *t = m_get(slirp);
 252
 253           if (t == NULL) {
 254               goto dropfrag;
 255           }
 256           fp = mtod(t, struct ipq *);
 257           insque(&fp->ip_link, &slirp->ipq.ip_link);
 258           fp->ipq_ttl = IPFRAGTTL;
 259           fp->ipq_p = ip->ip_p;
 260           fp->ipq_id = ip->ip_id;
 261           fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
 262           fp->ipq_src = ip->ip_src;
 263           fp->ipq_dst = ip->ip_dst;
 264           q = (struct ipasfrag *)fp;
 265           goto insert;
 266         }
 267
 268         /*
 269          * Find a segment which begins after this one does.
 270          */
 271         for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
 272             q = q->ipf_next)
 273                 if (q->ipf_off > ip->ip_off)
 274                         break;
 275
 276         /*
 277          * If there is a preceding segment, it may provide some of
 278          * our data already.  If so, drop the data from the incoming
 279          * segment.  If it provides all of our data, drop us.
 280          */
 281         if (q->ipf_prev != &fp->frag_link) {
 282         struct ipasfrag *pq = q->ipf_prev;
 283                 i = pq->ipf_off + pq->ipf_len - ip->ip_off;
 284                 if (i > 0) {
 285                         if (i >= ip->ip_len)
 286                                 goto dropfrag;
 287                         m_adj(dtom(slirp, ip), i);
 288                         ip->ip_off += i;
 289                         ip->ip_len -= i;
 290                 }
 291         }
 292
 293         /*
 294          * While we overlap succeeding segments trim them or,
 295          * if they are completely covered, dequeue them.
 296          */
 297         while (q != (struct ipasfrag*)&fp->frag_link &&
 298             ip->ip_off + ip->ip_len > q->ipf_off) {
 299                 i = (ip->ip_off + ip->ip_len) - q->ipf_off;
 300                 if (i < q->ipf_len) {
 301                         q->ipf_len -= i;
 302                         q->ipf_off += i;
 303                         m_adj(dtom(slirp, q), i);
 304                         break;
 305                 }
 306                 q = q->ipf_next;
 307                 m_free(dtom(slirp, q->ipf_prev));
 308                 ip_deq(q->ipf_prev);
 309         }
 310
 311 insert:
 312         /*
 313          * Stick new segment in its place;
 314          * check for complete reassembly.
 315          */
 316         ip_enq(iptofrag(ip), q->ipf_prev);
 317         next = 0;
 318         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link;
 319             q = q->ipf_next) {
 320                 if (q->ipf_off != next)
 321                         return NULL;
 322                 next += q->ipf_len;
 323         }
 324         if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
 325                 return NULL;
 326
 327         /*
 328          * Reassembly is complete; concatenate fragments.
 329          */
 330     q = fp->frag_link.next;
 331         m = dtom(slirp, q);
 332
 333         q = (struct ipasfrag *) q->ipf_next;
 334         while (q != (struct ipasfrag*)&fp->frag_link) {
 335           struct mbuf *t = dtom(slirp, q);
 336           q = (struct ipasfrag *) q->ipf_next;
 337           m_cat(m, t);
 338         }
 339
 340         /*
 341          * Create header for new ip packet by
 342          * modifying header of first packet;
 343          * dequeue and discard fragment reassembly header.
 344          * Make header visible.
 345          */
 346         q = fp->frag_link.next;
 347
 348         /*
 349          * If the fragments concatenated to an mbuf that's
 350          * bigger than the total size of the fragment, then and
 351          * m_ext buffer was alloced. But fp->ipq_next points to
 352          * the old buffer (in the mbuf), so we must point ip
 353          * into the new buffer.
 354          */
 355         if (m->m_flags & M_EXT) {
 356           int delta = (char *)q - m->m_dat;
 357           q = (struct ipasfrag *)(m->m_ext + delta);
 358         }
 359
 360     ip = fragtoip(q);
 361         ip->ip_len = next;
 362         ip->ip_tos &= ~1;
 363         ip->ip_src = fp->ipq_src;
 364         ip->ip_dst = fp->ipq_dst;
 365         remque(&fp->ip_link);
 366         (void) m_free(dtom(slirp, fp));
 367         m->m_len += (ip->ip_hl << 2);
 368         m->m_data -= (ip->ip_hl << 2);
 369
 370         return ip;
 371
 372 dropfrag:
 373         m_free(m);
 374         return NULL;
 375 }
 376
 377 /*
 378  * Free a fragment reassembly header and all
 379  * associated datagrams.
 380  */
 381 static void
 382 ip_freef(Slirp *slirp, struct ipq *fp)
 383 {
 384         register struct ipasfrag *q, *p;
 385
 386         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) {
 387                 p = q->ipf_next;
 388                 ip_deq(q);
 389                 m_free(dtom(slirp, q));
 390         }
 391         remque(&fp->ip_link);
 392         (void) m_free(dtom(slirp, fp));
 393 }
 394
 395 /*
 396  * Put an ip fragment on a reassembly chain.
 397  * Like insque, but pointers in middle of structure.
 398  */
 399 static void
 400 ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)
 401 {
 402         DEBUG_CALL("ip_enq");
 403         DEBUG_ARG("prev = %p", prev);
 404         p->ipf_prev =  prev;
 405         p->ipf_next = prev->ipf_next;
 406         ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
 407         prev->ipf_next = p;
 408 }
 409
 410 /*
 411  * To ip_enq as remque is to insque.
 412  */
 413 static void
 414 ip_deq(register struct ipasfrag *p)
 415 {
 416         ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
 417         ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
 418 }
 419
 420 /*
 421  * IP timer processing;
 422  * if a timer expires on a reassembly
 423  * queue, discard it.
 424  */
 425 void
 426 ip_slowtimo(Slirp *slirp)
 427 {
 428     struct qlink *l;
 429
 430         DEBUG_CALL("ip_slowtimo");
 431
 432     l = slirp->ipq.ip_link.next;
 433
 434         if (l == NULL)
 435            return;
 436
 437     while (l != &slirp->ipq.ip_link) {
 438         struct ipq *fp = container_of(l, struct ipq, ip_link);
 439         l = l->next;
 440                 if (--fp->ipq_ttl == 0) {
 441                         ip_freef(slirp, fp);
 442                 }
 443     }
 444 }
 445
 446 /*
 447  * Do option processing on a datagram,
 448  * possibly discarding it if bad options are encountered,
 449  * or forwarding it if source-routed.
 450  * Returns 1 if packet has been forwarded/freed,
 451  * 0 if the packet should be processed further.
 452  */
 453
 454 #ifdef notdef
 455
 456 int
 457 ip_dooptions(m)
 458         struct mbuf *m;
 459 {
 460         register struct ip *ip = mtod(m, struct ip *);
 461         register u_char *cp;
 462         register struct ip_timestamp *ipt;
 463         register struct in_ifaddr *ia;
 464         int opt, optlen, cnt, off, code, type, forward = 0;
 465         struct in_addr *sin, dst;
 466 typedef uint32_t n_time;
 467         n_time ntime;
 468
 469         dst = ip->ip_dst;
 470         cp = (u_char *)(ip + 1);
 471         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 472         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 473                 opt = cp[IPOPT_OPTVAL];
 474                 if (opt == IPOPT_EOL)
 475                         break;
 476                 if (opt == IPOPT_NOP)
 477                         optlen = 1;
 478                 else {
 479                         optlen = cp[IPOPT_OLEN];
 480                         if (optlen <= 0 || optlen > cnt) {
 481                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 482                                 goto bad;
 483                         }
 484                 }
 485                 switch (opt) {
 486
 487                 default:
 488                         break;
 489
 490                 /*
 491                  * Source routing with record.
 492                  * Find interface with current destination address.
 493                  * If none on this machine then drop if strictly routed,
 494                  * or do nothing if loosely routed.
 495                  * Record interface address and bring up next address
 496                  * component.  If strictly routed make sure next
 497                  * address is on directly accessible net.
 498                  */
 499                 case IPOPT_LSRR:
 500                 case IPOPT_SSRR:
 501                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 502                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 503                                 goto bad;
 504                         }
 505                         ipaddr.sin_addr = ip->ip_dst;
 506                         ia = (struct in_ifaddr *)
 507                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 508                         if (ia == 0) {
 509                                 if (opt == IPOPT_SSRR) {
 510                                         type = ICMP_UNREACH;
 511                                         code = ICMP_UNREACH_SRCFAIL;
 512                                         goto bad;
 513                                 }
 514                                 /*
 515                                  * Loose routing, and not at next destination
 516                                  * yet; nothing to do except forward.
 517                                  */
 518                                 break;
 519                         }
 520                         off--; /* 0 origin */
 521                         if (off > optlen - sizeof(struct in_addr)) {
 522                                 /*
 523                                  * End of source route.  Should be for us.
 524                                  */
 525                                 save_rte(cp, ip->ip_src);
 526                                 break;
 527                         }
 528                         /*
 529                          * locate outgoing interface
 530                          */
 531                         bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
 532                             sizeof(ipaddr.sin_addr));
 533                         if (opt == IPOPT_SSRR) {
 534 #define INA     struct in_ifaddr *
 535 #define SA      struct sockaddr *
 536                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
 537                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 538                         } else
 539                                 ia = ip_rtaddr(ipaddr.sin_addr);
 540                         if (ia == 0) {
 541                                 type = ICMP_UNREACH;
 542                                 code = ICMP_UNREACH_SRCFAIL;
 543                                 goto bad;
 544                         }
 545                         ip->ip_dst = ipaddr.sin_addr;
 546                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 547                             (caddr_t)(cp + off), sizeof(struct in_addr));
 548                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 549                         /*
 550                          * Let ip_intr's mcast routing check handle mcast pkts
 551                          */
 552                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 553                         break;
 554
 555                 case IPOPT_RR:
 556                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 557                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 558                                 goto bad;
 559                         }
 560                         /*
 561                          * If no space remains, ignore.
 562                          */
 563                         off--; /* 0 origin */
 564                         if (off > optlen - sizeof(struct in_addr))
 565                                 break;
 566                         bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
 567                             sizeof(ipaddr.sin_addr));
 568                         /*
 569                          * locate outgoing interface; if we're the destination,
 570                          * use the incoming interface (should be same).
 571                          */
 572                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
 573                             (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
 574                                 type = ICMP_UNREACH;
 575                                 code = ICMP_UNREACH_HOST;
 576                                 goto bad;
 577                         }
 578                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 579                             (caddr_t)(cp + off), sizeof(struct in_addr));
 580                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 581                         break;
 582
 583                 case IPOPT_TS:
 584                         code = cp - (u_char *)ip;
 585                         ipt = (struct ip_timestamp *)cp;
 586                         if (ipt->ipt_len < 5)
 587                                 goto bad;
 588                         if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
 589                                 if (++ipt->ipt_oflw == 0)
 590                                         goto bad;
 591                                 break;
 592                         }
 593                         sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
 594                         switch (ipt->ipt_flg) {
 595
 596                         case IPOPT_TS_TSONLY:
 597                                 break;
 598
 599                         case IPOPT_TS_TSANDADDR:
 600                                 if (ipt->ipt_ptr + sizeof(n_time) +
 601                                     sizeof(struct in_addr) > ipt->ipt_len)
 602                                         goto bad;
 603                                 ipaddr.sin_addr = dst;
 604                                 ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
 605                                                             m->m_pkthdr.rcvif);
 606                                 if (ia == 0)
 607                                         continue;
 608                                 bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
 609                                     (caddr_t)sin, sizeof(struct in_addr));
 610                                 ipt->ipt_ptr += sizeof(struct in_addr);
 611                                 break;
 612
 613                         case IPOPT_TS_PRESPEC:
 614                                 if (ipt->ipt_ptr + sizeof(n_time) +
 615                                     sizeof(struct in_addr) > ipt->ipt_len)
 616                                         goto bad;
 617                                 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
 618                                     sizeof(struct in_addr));
 619                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
 620                                         continue;
 621                                 ipt->ipt_ptr += sizeof(struct in_addr);
 622                                 break;
 623
 624                         default:
 625                                 goto bad;
 626                         }
 627                         ntime = iptime();
 628                         bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
 629                             sizeof(n_time));
 630                         ipt->ipt_ptr += sizeof(n_time);
 631                 }
 632         }
 633         if (forward) {
 634                 ip_forward(m, 1);
 635                 return (1);
 636         }
 637         return (0);
 638 bad:
 639         icmp_error(m, type, code, 0, 0);
 640
 641         return (1);
 642 }
 643
 644 #endif /* notdef */
 645
 646 /*
 647  * Strip out IP options, at higher
 648  * level protocol in the kernel.
 649  * Second argument is buffer to which options
 650  * will be moved, and return value is their length.
 651  * (XXX) should be deleted; last arg currently ignored.
 652  */
 653 void
 654 ip_stripoptions(register struct mbuf *m, struct mbuf *mopt)
 655 {
 656         register int i;
 657         struct ip *ip = mtod(m, struct ip *);
 658         register caddr_t opts;
 659         int olen;
 660
 661         olen = (ip->ip_hl<<2) - sizeof (struct ip);
 662         opts = (caddr_t)(ip + 1);
 663         i = m->m_len - (sizeof (struct ip) + olen);
 664         memcpy(opts, opts  + olen, (unsigned)i);
 665         m->m_len -= olen;
 666
 667         ip->ip_hl = sizeof(struct ip) >> 2;
 668 }