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 "qemu/osdep.h"
  42 #include "slirp.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         if (!slirp->in_enabled) {
  83                 goto bad;
  84         }
  85
  86         DEBUG_CALL("ip_input");
  87         DEBUG_ARG("m = %p", m);
  88         DEBUG_ARG("m_len = %d", m->m_len);
  89
  90         if (m->m_len < sizeof (struct ip)) {
  91                 goto bad;
  92         }
  93
  94         ip = mtod(m, struct ip *);
  95
  96         if (ip->ip_v != IPVERSION) {
  97                 goto bad;
  98         }
  99
 100         hlen = ip->ip_hl << 2;
 101         if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
 102           goto bad;                                  /* or packet too short */
 103         }
 104
 105         /* keep ip header intact for ICMP reply
 106          * ip->ip_sum = cksum(m, hlen);
 107          * if (ip->ip_sum) {
 108          */
 109         if(cksum(m,hlen)) {
 110           goto bad;
 111         }
 112
 113         /*
 114          * Convert fields to host representation.
 115          */
 116         NTOHS(ip->ip_len);
 117         if (ip->ip_len < hlen) {
 118                 goto bad;
 119         }
 120         NTOHS(ip->ip_id);
 121         NTOHS(ip->ip_off);
 122
 123         /*
 124          * Check that the amount of data in the buffers
 125          * is as at least much as the IP header would have us expect.
 126          * Trim mbufs if longer than we expect.
 127          * Drop packet if shorter than we expect.
 128          */
 129         if (m->m_len < ip->ip_len) {
 130                 goto bad;
 131         }
 132
 133         /* Should drop packet if mbuf too long? hmmm... */
 134         if (m->m_len > ip->ip_len)
 135            m_adj(m, ip->ip_len - m->m_len);
 136
 137         /* check ip_ttl for a correct ICMP reply */
 138         if (ip->ip_ttl == 0) {
 139             icmp_send_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, "ttl");
 140             goto bad;
 141         }
 142
 143         /*
 144          * If offset or IP_MF are set, must reassemble.
 145          * Otherwise, nothing need be done.
 146          * (We could look in the reassembly queue to see
 147          * if the packet was previously fragmented,
 148          * but it's not worth the time; just let them time out.)
 149          *
 150          * XXX This should fail, don't fragment yet
 151          */
 152         if (ip->ip_off &~ IP_DF) {
 153           register struct ipq *fp;
 154       struct qlink *l;
 155                 /*
 156                  * Look for queue of fragments
 157                  * of this datagram.
 158                  */
 159                 for (l = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link;
 160                      l = l->next) {
 161             fp = container_of(l, struct ipq, ip_link);
 162             if (ip->ip_id == fp->ipq_id &&
 163                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 164                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 165                     ip->ip_p == fp->ipq_p)
 166                     goto found;
 167         }
 168         fp = NULL;
 169         found:
 170
 171                 /*
 172                  * Adjust ip_len to not reflect header,
 173                  * set ip_mff if more fragments are expected,
 174                  * convert offset of this to bytes.
 175                  */
 176                 ip->ip_len -= hlen;
 177                 if (ip->ip_off & IP_MF)
 178                   ip->ip_tos |= 1;
 179                 else
 180                   ip->ip_tos &= ~1;
 181
 182                 ip->ip_off <<= 3;
 183
 184                 /*
 185                  * If datagram marked as having more fragments
 186                  * or if this is not the first fragment,
 187                  * attempt reassembly; if it succeeds, proceed.
 188                  */
 189                 if (ip->ip_tos & 1 || ip->ip_off) {
 190                         ip = ip_reass(slirp, ip, fp);
 191                         if (ip == NULL)
 192                                 return;
 193                         m = dtom(slirp, ip);
 194                 } else
 195                         if (fp)
 196                            ip_freef(slirp, fp);
 197
 198         } else
 199                 ip->ip_len -= hlen;
 200
 201         /*
 202          * Switch out to protocol's input routine.
 203          */
 204         switch (ip->ip_p) {
 205          case IPPROTO_TCP:
 206                 tcp_input(m, hlen, (struct socket *)NULL, AF_INET);
 207                 break;
 208          case IPPROTO_UDP:
 209                 udp_input(m, hlen);
 210                 break;
 211          case IPPROTO_ICMP:
 212                 icmp_input(m, hlen);
 213                 break;
 214          default:
 215                 m_free(m);
 216         }
 217         return;
 218 bad:
 219         m_free(m);
 220 }
 221
 222 #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
 223 #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
 224 /*
 225  * Take incoming datagram fragment and try to
 226  * reassemble it into whole datagram.  If a chain for
 227  * reassembly of this datagram already exists, then it
 228  * is given as fp; otherwise have to make a chain.
 229  */
 230 static struct ip *
 231 ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
 232 {
 233         register struct mbuf *m = dtom(slirp, ip);
 234         register struct ipasfrag *q;
 235         int hlen = ip->ip_hl << 2;
 236         int i, next;
 237
 238         DEBUG_CALL("ip_reass");
 239         DEBUG_ARG("ip = %p", ip);
 240         DEBUG_ARG("fp = %p", fp);
 241         DEBUG_ARG("m = %p", m);
 242
 243         /*
 244          * Presence of header sizes in mbufs
 245          * would confuse code below.
 246          * Fragment m_data is concatenated.
 247          */
 248         m->m_data += hlen;
 249         m->m_len -= hlen;
 250
 251         /*
 252          * If first fragment to arrive, create a reassembly queue.
 253          */
 254         if (fp == NULL) {
 255           struct mbuf *t = m_get(slirp);
 256
 257           if (t == NULL) {
 258               goto dropfrag;
 259           }
 260           fp = mtod(t, struct ipq *);
 261           insque(&fp->ip_link, &slirp->ipq.ip_link);
 262           fp->ipq_ttl = IPFRAGTTL;
 263           fp->ipq_p = ip->ip_p;
 264           fp->ipq_id = ip->ip_id;
 265           fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
 266           fp->ipq_src = ip->ip_src;
 267           fp->ipq_dst = ip->ip_dst;
 268           q = (struct ipasfrag *)fp;
 269           goto insert;
 270         }
 271
 272         /*
 273          * Find a segment which begins after this one does.
 274          */
 275         for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
 276             q = q->ipf_next)
 277                 if (q->ipf_off > ip->ip_off)
 278                         break;
 279
 280         /*
 281          * If there is a preceding segment, it may provide some of
 282          * our data already.  If so, drop the data from the incoming
 283          * segment.  If it provides all of our data, drop us.
 284          */
 285         if (q->ipf_prev != &fp->frag_link) {
 286         struct ipasfrag *pq = q->ipf_prev;
 287                 i = pq->ipf_off + pq->ipf_len - ip->ip_off;
 288                 if (i > 0) {
 289                         if (i >= ip->ip_len)
 290                                 goto dropfrag;
 291                         m_adj(dtom(slirp, ip), i);
 292                         ip->ip_off += i;
 293                         ip->ip_len -= i;
 294                 }
 295         }
 296
 297         /*
 298          * While we overlap succeeding segments trim them or,
 299          * if they are completely covered, dequeue them.
 300          */
 301         while (q != (struct ipasfrag*)&fp->frag_link &&
 302             ip->ip_off + ip->ip_len > q->ipf_off) {
 303                 i = (ip->ip_off + ip->ip_len) - q->ipf_off;
 304                 if (i < q->ipf_len) {
 305                         q->ipf_len -= i;
 306                         q->ipf_off += i;
 307                         m_adj(dtom(slirp, q), i);
 308                         break;
 309                 }
 310                 q = q->ipf_next;
 311                 m_free(dtom(slirp, q->ipf_prev));
 312                 ip_deq(q->ipf_prev);
 313         }
 314
 315 insert:
 316         /*
 317          * Stick new segment in its place;
 318          * check for complete reassembly.
 319          */
 320         ip_enq(iptofrag(ip), q->ipf_prev);
 321         next = 0;
 322         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link;
 323             q = q->ipf_next) {
 324                 if (q->ipf_off != next)
 325                         return NULL;
 326                 next += q->ipf_len;
 327         }
 328         if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
 329                 return NULL;
 330
 331         /*
 332          * Reassembly is complete; concatenate fragments.
 333          */
 334     q = fp->frag_link.next;
 335         m = dtom(slirp, q);
 336
 337         q = (struct ipasfrag *) q->ipf_next;
 338         while (q != (struct ipasfrag*)&fp->frag_link) {
 339           struct mbuf *t = dtom(slirp, q);
 340           q = (struct ipasfrag *) q->ipf_next;
 341           m_cat(m, t);
 342         }
 343
 344         /*
 345          * Create header for new ip packet by
 346          * modifying header of first packet;
 347          * dequeue and discard fragment reassembly header.
 348          * Make header visible.
 349          */
 350         q = fp->frag_link.next;
 351
 352         /*
 353          * If the fragments concatenated to an mbuf that's
 354          * bigger than the total size of the fragment, then and
 355          * m_ext buffer was alloced. But fp->ipq_next points to
 356          * the old buffer (in the mbuf), so we must point ip
 357          * into the new buffer.
 358          */
 359         if (m->m_flags & M_EXT) {
 360           int delta = (char *)q - m->m_dat;
 361           q = (struct ipasfrag *)(m->m_ext + delta);
 362         }
 363
 364     ip = fragtoip(q);
 365         ip->ip_len = next;
 366         ip->ip_tos &= ~1;
 367         ip->ip_src = fp->ipq_src;
 368         ip->ip_dst = fp->ipq_dst;
 369         remque(&fp->ip_link);
 370         (void) m_free(dtom(slirp, fp));
 371         m->m_len += (ip->ip_hl << 2);
 372         m->m_data -= (ip->ip_hl << 2);
 373
 374         return ip;
 375
 376 dropfrag:
 377         m_free(m);
 378         return NULL;
 379 }
 380
 381 /*
 382  * Free a fragment reassembly header and all
 383  * associated datagrams.
 384  */
 385 static void
 386 ip_freef(Slirp *slirp, struct ipq *fp)
 387 {
 388         register struct ipasfrag *q, *p;
 389
 390         for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) {
 391                 p = q->ipf_next;
 392                 ip_deq(q);
 393                 m_free(dtom(slirp, q));
 394         }
 395         remque(&fp->ip_link);
 396         (void) m_free(dtom(slirp, fp));
 397 }
 398
 399 /*
 400  * Put an ip fragment on a reassembly chain.
 401  * Like insque, but pointers in middle of structure.
 402  */
 403 static void
 404 ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)
 405 {
 406         DEBUG_CALL("ip_enq");
 407         DEBUG_ARG("prev = %p", prev);
 408         p->ipf_prev =  prev;
 409         p->ipf_next = prev->ipf_next;
 410         ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
 411         prev->ipf_next = p;
 412 }
 413
 414 /*
 415  * To ip_enq as remque is to insque.
 416  */
 417 static void
 418 ip_deq(register struct ipasfrag *p)
 419 {
 420         ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
 421         ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
 422 }
 423
 424 /*
 425  * IP timer processing;
 426  * if a timer expires on a reassembly
 427  * queue, discard it.
 428  */
 429 void
 430 ip_slowtimo(Slirp *slirp)
 431 {
 432     struct qlink *l;
 433
 434         DEBUG_CALL("ip_slowtimo");
 435
 436     l = slirp->ipq.ip_link.next;
 437
 438         if (l == NULL)
 439            return;
 440
 441     while (l != &slirp->ipq.ip_link) {
 442         struct ipq *fp = container_of(l, struct ipq, ip_link);
 443         l = l->next;
 444                 if (--fp->ipq_ttl == 0) {
 445                         ip_freef(slirp, fp);
 446                 }
 447     }
 448 }
 449
 450 /*
 451  * Do option processing on a datagram,
 452  * possibly discarding it if bad options are encountered,
 453  * or forwarding it if source-routed.
 454  * Returns 1 if packet has been forwarded/freed,
 455  * 0 if the packet should be processed further.
 456  */
 457
 458 #ifdef notdef
 459
 460 int
 461 ip_dooptions(m)
 462         struct mbuf *m;
 463 {
 464         register struct ip *ip = mtod(m, struct ip *);
 465         register u_char *cp;
 466         register struct ip_timestamp *ipt;
 467         register struct in_ifaddr *ia;
 468         int opt, optlen, cnt, off, code, type, forward = 0;
 469         struct in_addr *sin, dst;
 470 typedef uint32_t n_time;
 471         n_time ntime;
 472
 473         dst = ip->ip_dst;
 474         cp = (u_char *)(ip + 1);
 475         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 476         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 477                 opt = cp[IPOPT_OPTVAL];
 478                 if (opt == IPOPT_EOL)
 479                         break;
 480                 if (opt == IPOPT_NOP)
 481                         optlen = 1;
 482                 else {
 483                         optlen = cp[IPOPT_OLEN];
 484                         if (optlen <= 0 || optlen > cnt) {
 485                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
 486                                 goto bad;
 487                         }
 488                 }
 489                 switch (opt) {
 490
 491                 default:
 492                         break;
 493
 494                 /*
 495                  * Source routing with record.
 496                  * Find interface with current destination address.
 497                  * If none on this machine then drop if strictly routed,
 498                  * or do nothing if loosely routed.
 499                  * Record interface address and bring up next address
 500                  * component.  If strictly routed make sure next
 501                  * address is on directly accessible net.
 502                  */
 503                 case IPOPT_LSRR:
 504                 case IPOPT_SSRR:
 505                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 506                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 507                                 goto bad;
 508                         }
 509                         ipaddr.sin_addr = ip->ip_dst;
 510                         ia = (struct in_ifaddr *)
 511                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
 512                         if (ia == 0) {
 513                                 if (opt == IPOPT_SSRR) {
 514                                         type = ICMP_UNREACH;
 515                                         code = ICMP_UNREACH_SRCFAIL;
 516                                         goto bad;
 517                                 }
 518                                 /*
 519                                  * Loose routing, and not at next destination
 520                                  * yet; nothing to do except forward.
 521                                  */
 522                                 break;
 523                         }
 524                         off--; /* 0 origin */
 525                         if (off > optlen - sizeof(struct in_addr)) {
 526                                 /*
 527                                  * End of source route.  Should be for us.
 528                                  */
 529                                 save_rte(cp, ip->ip_src);
 530                                 break;
 531                         }
 532                         /*
 533                          * locate outgoing interface
 534                          */
 535                         bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
 536                             sizeof(ipaddr.sin_addr));
 537                         if (opt == IPOPT_SSRR) {
 538 #define INA     struct in_ifaddr *
 539 #define SA      struct sockaddr *
 540                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
 541                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
 542                         } else
 543                                 ia = ip_rtaddr(ipaddr.sin_addr);
 544                         if (ia == 0) {
 545                                 type = ICMP_UNREACH;
 546                                 code = ICMP_UNREACH_SRCFAIL;
 547                                 goto bad;
 548                         }
 549                         ip->ip_dst = ipaddr.sin_addr;
 550                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 551                             (caddr_t)(cp + off), sizeof(struct in_addr));
 552                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 553                         /*
 554                          * Let ip_intr's mcast routing check handle mcast pkts
 555                          */
 556                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
 557                         break;
 558
 559                 case IPOPT_RR:
 560                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
 561                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
 562                                 goto bad;
 563                         }
 564                         /*
 565                          * If no space remains, ignore.
 566                          */
 567                         off--; /* 0 origin */
 568                         if (off > optlen - sizeof(struct in_addr))
 569                                 break;
 570                         bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
 571                             sizeof(ipaddr.sin_addr));
 572                         /*
 573                          * locate outgoing interface; if we're the destination,
 574                          * use the incoming interface (should be same).
 575                          */
 576                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
 577                             (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
 578                                 type = ICMP_UNREACH;
 579                                 code = ICMP_UNREACH_HOST;
 580                                 goto bad;
 581                         }
 582                         bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
 583                             (caddr_t)(cp + off), sizeof(struct in_addr));
 584                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
 585                         break;
 586
 587                 case IPOPT_TS:
 588                         code = cp - (u_char *)ip;
 589                         ipt = (struct ip_timestamp *)cp;
 590                         if (ipt->ipt_len < 5)
 591                                 goto bad;
 592                         if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
 593                                 if (++ipt->ipt_oflw == 0)
 594                                         goto bad;
 595                                 break;
 596                         }
 597                         sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
 598                         switch (ipt->ipt_flg) {
 599
 600                         case IPOPT_TS_TSONLY:
 601                                 break;
 602
 603                         case IPOPT_TS_TSANDADDR:
 604                                 if (ipt->ipt_ptr + sizeof(n_time) +
 605                                     sizeof(struct in_addr) > ipt->ipt_len)
 606                                         goto bad;
 607                                 ipaddr.sin_addr = dst;
 608                                 ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
 609                                                             m->m_pkthdr.rcvif);
 610                                 if (ia == 0)
 611                                         continue;
 612                                 bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
 613                                     (caddr_t)sin, sizeof(struct in_addr));
 614                                 ipt->ipt_ptr += sizeof(struct in_addr);
 615                                 break;
 616
 617                         case IPOPT_TS_PRESPEC:
 618                                 if (ipt->ipt_ptr + sizeof(n_time) +
 619                                     sizeof(struct in_addr) > ipt->ipt_len)
 620                                         goto bad;
 621                                 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
 622                                     sizeof(struct in_addr));
 623                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
 624                                         continue;
 625                                 ipt->ipt_ptr += sizeof(struct in_addr);
 626                                 break;
 627
 628                         default:
 629                                 goto bad;
 630                         }
 631                         ntime = iptime();
 632                         bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
 633                             sizeof(n_time));
 634                         ipt->ipt_ptr += sizeof(n_time);
 635                 }
 636         }
 637         if (forward) {
 638                 ip_forward(m, 1);
 639                 return (1);
 640         }
 641         return (0);
 642 bad:
 643         icmp_send_error(m, type, code, 0, 0);
 644
 645         return (1);
 646 }
 647
 648 #endif /* notdef */
 649
 650 /*
 651  * Strip out IP options, at higher
 652  * level protocol in the kernel.
 653  * Second argument is buffer to which options
 654  * will be moved, and return value is their length.
 655  * (XXX) should be deleted; last arg currently ignored.
 656  */
 657 void
 658 ip_stripoptions(register struct mbuf *m, struct mbuf *mopt)
 659 {
 660         register int i;
 661         struct ip *ip = mtod(m, struct ip *);
 662         register caddr_t opts;
 663         int olen;
 664
 665         olen = (ip->ip_hl<<2) - sizeof (struct ip);
 666         opts = (caddr_t)(ip + 1);
 667         i = m->m_len - (sizeof (struct ip) + olen);
 668         memcpy(opts, opts  + olen, (unsigned)i);
 669         m->m_len -= olen;
 670
 671         ip->ip_hl = sizeof(struct ip) >> 2;
 672 }