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#ifdef LOG_ENABLED 46struct ipstat ipstat; 47#endif 48 49struct ipq ipq; 50 51static struct ip *ip_reass(register struct ip *ip, 52 register struct ipq *fp); 53static void ip_freef(struct ipq *fp); 54static void ip_enq(register struct ipasfrag *p, 55 register struct ipasfrag *prev); 56static void ip_deq(register struct ipasfrag *p); 57 58/* 59 * IP initialization: fill in IP protocol switch table. 60 * All protocols not implemented in kernel go to raw IP protocol handler. 61 */ 62void 63ip_init(void) 64{ 65 ipq.ip_link.next = ipq.ip_link.prev = &ipq.ip_link; 66 ip_id = tt.tv_sec & 0xffff; 67 udp_init(); 68 tcp_init(); 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 */ 75void 76ip_input(struct mbuf *m) 77{ 78 register struct ip *ip; 79 int hlen; 80 81 DEBUG_CALL("ip_input"); 82 DEBUG_ARG("m = %lx", (long)m); 83 DEBUG_ARG("m_len = %d", m->m_len); 84 85 STAT(ipstat.ips_total++); 86 87 if (m->m_len < sizeof (struct ip)) { 88 STAT(ipstat.ips_toosmall++); 89 return; 90 } 91 92 ip = mtod(m, struct ip *); 93 94 if (ip->ip_v != IPVERSION) { 95 STAT(ipstat.ips_badvers++); 96 goto bad; 97 } 98 99 hlen = ip->ip_hl << 2; 100 if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */ 101 STAT(ipstat.ips_badhlen++); /* or packet too short */ 102 goto bad; 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 STAT(ipstat.ips_badsum++); 111 goto bad; 112 } 113 114 /* 115 * Convert fields to host representation. 116 */ 117 NTOHS(ip->ip_len); 118 if (ip->ip_len < hlen) { 119 STAT(ipstat.ips_badlen++); 120 goto bad; 121 } 122 NTOHS(ip->ip_id); 123 NTOHS(ip->ip_off); 124 125 /* 126 * Check that the amount of data in the buffers 127 * is as at least much as the IP header would have us expect. 128 * Trim mbufs if longer than we expect. 129 * Drop packet if shorter than we expect. 130 */ 131 if (m->m_len < ip->ip_len) { 132 STAT(ipstat.ips_tooshort++); 133 goto bad; 134 } 135 136 if (slirp_restrict) { 137 if (memcmp(&ip->ip_dst.s_addr, &special_addr, 3)) { 138 if (ip->ip_dst.s_addr == 0xffffffff && ip->ip_p != IPPROTO_UDP) 139 goto bad; 140 } else { 141 int host = ntohl(ip->ip_dst.s_addr) & 0xff; 142 struct ex_list *ex_ptr; 143 144 if (host == 0xff) 145 goto bad; 146 147 for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) 148 if (ex_ptr->ex_addr == host) 149 break; 150 151 if (!ex_ptr) 152 goto bad; 153 } 154 } 155 156 /* Should drop packet if mbuf too long? hmmm... */ 157 if (m->m_len > ip->ip_len) 158 m_adj(m, ip->ip_len - m->m_len); 159 160 /* check ip_ttl for a correct ICMP reply */ 161 if(ip->ip_ttl==0 || ip->ip_ttl==1) { 162 icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl"); 163 goto bad; 164 } 165 166 /* 167 * Process options and, if not destined for us, 168 * ship it on. ip_dooptions returns 1 when an 169 * error was detected (causing an icmp message 170 * to be sent and the original packet to be freed). 171 */ 172/* We do no IP options */ 173/* if (hlen > sizeof (struct ip) && ip_dooptions(m)) 174 * goto next; 175 */ 176 /* 177 * If offset or IP_MF are set, must reassemble. 178 * Otherwise, nothing need be done. 179 * (We could look in the reassembly queue to see 180 * if the packet was previously fragmented, 181 * but it's not worth the time; just let them time out.) 182 * 183 * XXX This should fail, don't fragment yet 184 */ 185 if (ip->ip_off &~ IP_DF) { 186 register struct ipq *fp; 187 struct qlink *l; 188 /* 189 * Look for queue of fragments 190 * of this datagram. 191 */ 192 for (l = ipq.ip_link.next; l != &ipq.ip_link; l = l->next) { 193 fp = container_of(l, struct ipq, ip_link); 194 if (ip->ip_id == fp->ipq_id && 195 ip->ip_src.s_addr == fp->ipq_src.s_addr && 196 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 197 ip->ip_p == fp->ipq_p) 198 goto found; 199 } 200 fp = NULL; 201 found: 202 203 /* 204 * Adjust ip_len to not reflect header, 205 * set ip_mff if more fragments are expected, 206 * convert offset of this to bytes. 207 */ 208 ip->ip_len -= hlen; 209 if (ip->ip_off & IP_MF) 210 ip->ip_tos |= 1; 211 else 212 ip->ip_tos &= ~1; 213 214 ip->ip_off <<= 3; 215 216 /* 217 * If datagram marked as having more fragments 218 * or if this is not the first fragment, 219 * attempt reassembly; if it succeeds, proceed. 220 */ 221 if (ip->ip_tos & 1 || ip->ip_off) { 222 STAT(ipstat.ips_fragments++); 223 ip = ip_reass(ip, fp); 224 if (ip == NULL) 225 return; 226 STAT(ipstat.ips_reassembled++); 227 m = dtom(ip); 228 } else 229 if (fp) 230 ip_freef(fp); 231 232 } else 233 ip->ip_len -= hlen; 234 235 /* 236 * Switch out to protocol's input routine. 237 */ 238 STAT(ipstat.ips_delivered++); 239 switch (ip->ip_p) { 240 case IPPROTO_TCP: 241 tcp_input(m, hlen, (struct socket *)NULL); 242 break; 243 case IPPROTO_UDP: 244 udp_input(m, hlen); 245 break; 246 case IPPROTO_ICMP: 247 icmp_input(m, hlen); 248 break; 249 default: 250 STAT(ipstat.ips_noproto++); 251 m_free(m); 252 } 253 return; 254bad: 255 m_freem(m); 256 return; 257} 258 259#define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink))) 260#define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink))) 261/* 262 * Take incoming datagram fragment and try to 263 * reassemble it into whole datagram. If a chain for 264 * reassembly of this datagram already exists, then it 265 * is given as fp; otherwise have to make a chain. 266 */ 267static struct ip * 268ip_reass(register struct ip *ip, register struct ipq *fp) 269{ 270 register struct mbuf *m = dtom(ip); 271 register struct ipasfrag *q; 272 int hlen = ip->ip_hl << 2; 273 int i, next; 274 275 DEBUG_CALL("ip_reass"); 276 DEBUG_ARG("ip = %lx", (long)ip); 277 DEBUG_ARG("fp = %lx", (long)fp); 278 DEBUG_ARG("m = %lx", (long)m); 279 280 /* 281 * Presence of header sizes in mbufs 282 * would confuse code below. 283 * Fragment m_data is concatenated. 284 */ 285 m->m_data += hlen; 286 m->m_len -= hlen; 287 288 /* 289 * If first fragment to arrive, create a reassembly queue. 290 */ 291 if (fp == NULL) { 292 struct mbuf *t; 293 if ((t = m_get()) == NULL) goto dropfrag; 294 fp = mtod(t, struct ipq *); 295 insque(&fp->ip_link, &ipq.ip_link); 296 fp->ipq_ttl = IPFRAGTTL; 297 fp->ipq_p = ip->ip_p; 298 fp->ipq_id = ip->ip_id; 299 fp->frag_link.next = fp->frag_link.prev = &fp->frag_link; 300 fp->ipq_src = ip->ip_src; 301 fp->ipq_dst = ip->ip_dst; 302 q = (struct ipasfrag *)fp; 303 goto insert; 304 } 305 306 /* 307 * Find a segment which begins after this one does. 308 */ 309 for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link; 310 q = q->ipf_next) 311 if (q->ipf_off > ip->ip_off) 312 break; 313 314 /* 315 * If there is a preceding segment, it may provide some of 316 * our data already. If so, drop the data from the incoming 317 * segment. If it provides all of our data, drop us. 318 */ 319 if (q->ipf_prev != &fp->frag_link) { 320 struct ipasfrag *pq = q->ipf_prev; 321 i = pq->ipf_off + pq->ipf_len - ip->ip_off; 322 if (i > 0) { 323 if (i >= ip->ip_len) 324 goto dropfrag; 325 m_adj(dtom(ip), i); 326 ip->ip_off += i; 327 ip->ip_len -= i; 328 } 329 } 330 331 /* 332 * While we overlap succeeding segments trim them or, 333 * if they are completely covered, dequeue them. 334 */ 335 while (q != (struct ipasfrag*)&fp->frag_link && 336 ip->ip_off + ip->ip_len > q->ipf_off) { 337 i = (ip->ip_off + ip->ip_len) - q->ipf_off; 338 if (i < q->ipf_len) { 339 q->ipf_len -= i; 340 q->ipf_off += i; 341 m_adj(dtom(q), i); 342 break; 343 } 344 q = q->ipf_next; 345 m_freem(dtom(q->ipf_prev)); 346 ip_deq(q->ipf_prev); 347 } 348 349insert: 350 /* 351 * Stick new segment in its place; 352 * check for complete reassembly. 353 */ 354 ip_enq(iptofrag(ip), q->ipf_prev); 355 next = 0; 356 for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; 357 q = q->ipf_next) { 358 if (q->ipf_off != next) 359 return NULL; 360 next += q->ipf_len; 361 } 362 if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1) 363 return NULL; 364 365 /* 366 * Reassembly is complete; concatenate fragments. 367 */ 368 q = fp->frag_link.next; 369 m = dtom(q); 370 371 q = (struct ipasfrag *) q->ipf_next; 372 while (q != (struct ipasfrag*)&fp->frag_link) { 373 struct mbuf *t = dtom(q); 374 q = (struct ipasfrag *) q->ipf_next; 375 m_cat(m, t); 376 } 377 378 /* 379 * Create header for new ip packet by 380 * modifying header of first packet; 381 * dequeue and discard fragment reassembly header. 382 * Make header visible. 383 */ 384 q = fp->frag_link.next; 385 386 /* 387 * If the fragments concatenated to an mbuf that's 388 * bigger than the total size of the fragment, then and 389 * m_ext buffer was alloced. But fp->ipq_next points to 390 * the old buffer (in the mbuf), so we must point ip 391 * into the new buffer. 392 */ 393 if (m->m_flags & M_EXT) { 394 int delta = (char *)q - m->m_dat; 395 q = (struct ipasfrag *)(m->m_ext + delta); 396 } 397 398 /* DEBUG_ARG("ip = %lx", (long)ip); 399 * ip=(struct ipasfrag *)m->m_data; */ 400 401 ip = fragtoip(q); 402 ip->ip_len = next; 403 ip->ip_tos &= ~1; 404 ip->ip_src = fp->ipq_src; 405 ip->ip_dst = fp->ipq_dst; 406 remque(&fp->ip_link); 407 (void) m_free(dtom(fp)); 408 m->m_len += (ip->ip_hl << 2); 409 m->m_data -= (ip->ip_hl << 2); 410 411 return ip; 412 413dropfrag: 414 STAT(ipstat.ips_fragdropped++); 415 m_freem(m); 416 return NULL; 417} 418 419/* 420 * Free a fragment reassembly header and all 421 * associated datagrams. 422 */ 423static void 424ip_freef(struct ipq *fp) 425{ 426 register struct ipasfrag *q, *p; 427 428 for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) { 429 p = q->ipf_next; 430 ip_deq(q); 431 m_freem(dtom(q)); 432 } 433 remque(&fp->ip_link); 434 (void) m_free(dtom(fp)); 435} 436 437/* 438 * Put an ip fragment on a reassembly chain. 439 * Like insque, but pointers in middle of structure. 440 */ 441static void 442ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev) 443{ 444 DEBUG_CALL("ip_enq"); 445 DEBUG_ARG("prev = %lx", (long)prev); 446 p->ipf_prev = prev; 447 p->ipf_next = prev->ipf_next; 448 ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p; 449 prev->ipf_next = p; 450} 451 452/* 453 * To ip_enq as remque is to insque. 454 */ 455static void 456ip_deq(register struct ipasfrag *p) 457{ 458 ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next; 459 ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev; 460} 461 462/* 463 * IP timer processing; 464 * if a timer expires on a reassembly 465 * queue, discard it. 466 */ 467void 468ip_slowtimo(void) 469{ 470 struct qlink *l; 471 472 DEBUG_CALL("ip_slowtimo"); 473 474 l = ipq.ip_link.next; 475 476 if (l == NULL) 477 return; 478 479 while (l != &ipq.ip_link) { 480 struct ipq *fp = container_of(l, struct ipq, ip_link); 481 l = l->next; 482 if (--fp->ipq_ttl == 0) { 483 STAT(ipstat.ips_fragtimeout++); 484 ip_freef(fp); 485 } 486 } 487} 488 489/* 490 * Do option processing on a datagram, 491 * possibly discarding it if bad options are encountered, 492 * or forwarding it if source-routed. 493 * Returns 1 if packet has been forwarded/freed, 494 * 0 if the packet should be processed further. 495 */ 496 497#ifdef notdef 498 499int 500ip_dooptions(m) 501 struct mbuf *m; 502{ 503 register struct ip *ip = mtod(m, struct ip *); 504 register u_char *cp; 505 register struct ip_timestamp *ipt; 506 register struct in_ifaddr *ia; 507/* int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; */ 508 int opt, optlen, cnt, off, code, type, forward = 0; 509 struct in_addr *sin, dst; 510typedef u_int32_t n_time; 511 n_time ntime; 512 513 dst = ip->ip_dst; 514 cp = (u_char *)(ip + 1); 515 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 516 for (; cnt > 0; cnt -= optlen, cp += optlen) { 517 opt = cp[IPOPT_OPTVAL]; 518 if (opt == IPOPT_EOL) 519 break; 520 if (opt == IPOPT_NOP) 521 optlen = 1; 522 else { 523 optlen = cp[IPOPT_OLEN]; 524 if (optlen <= 0 || optlen > cnt) { 525 code = &cp[IPOPT_OLEN] - (u_char *)ip; 526 goto bad; 527 } 528 } 529 switch (opt) { 530 531 default: 532 break; 533 534 /* 535 * Source routing with record. 536 * Find interface with current destination address. 537 * If none on this machine then drop if strictly routed, 538 * or do nothing if loosely routed. 539 * Record interface address and bring up next address 540 * component. If strictly routed make sure next 541 * address is on directly accessible net. 542 */ 543 case IPOPT_LSRR: 544 case IPOPT_SSRR: 545 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 546 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 547 goto bad; 548 } 549 ipaddr.sin_addr = ip->ip_dst; 550 ia = (struct in_ifaddr *) 551 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 552 if (ia == 0) { 553 if (opt == IPOPT_SSRR) { 554 type = ICMP_UNREACH; 555 code = ICMP_UNREACH_SRCFAIL; 556 goto bad; 557 } 558 /* 559 * Loose routing, and not at next destination 560 * yet; nothing to do except forward. 561 */ 562 break; 563 } 564 off--; / * 0 origin * / 565 if (off > optlen - sizeof(struct in_addr)) { 566 /* 567 * End of source route. Should be for us. 568 */ 569 save_rte(cp, ip->ip_src); 570 break; 571 } 572 /* 573 * locate outgoing interface 574 */ 575 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 576 sizeof(ipaddr.sin_addr)); 577 if (opt == IPOPT_SSRR) { 578#define INA struct in_ifaddr * 579#define SA struct sockaddr * 580 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 581 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 582 } else 583 ia = ip_rtaddr(ipaddr.sin_addr); 584 if (ia == 0) { 585 type = ICMP_UNREACH; 586 code = ICMP_UNREACH_SRCFAIL; 587 goto bad; 588 } 589 ip->ip_dst = ipaddr.sin_addr; 590 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 591 (caddr_t)(cp + off), sizeof(struct in_addr)); 592 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 593 /* 594 * Let ip_intr's mcast routing check handle mcast pkts 595 */ 596 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 597 break; 598 599 case IPOPT_RR: 600 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 601 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 602 goto bad; 603 } 604 /* 605 * If no space remains, ignore. 606 */ 607 off--; * 0 origin * 608 if (off > optlen - sizeof(struct in_addr)) 609 break; 610 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 611 sizeof(ipaddr.sin_addr)); 612 /* 613 * locate outgoing interface; if we're the destination, 614 * use the incoming interface (should be same). 615 */ 616 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 617 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 618 type = ICMP_UNREACH; 619 code = ICMP_UNREACH_HOST; 620 goto bad; 621 } 622 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 623 (caddr_t)(cp + off), sizeof(struct in_addr)); 624 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 625 break; 626 627 case IPOPT_TS: 628 code = cp - (u_char *)ip; 629 ipt = (struct ip_timestamp *)cp; 630 if (ipt->ipt_len < 5) 631 goto bad; 632 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) { 633 if (++ipt->ipt_oflw == 0) 634 goto bad; 635 break; 636 } 637 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 638 switch (ipt->ipt_flg) { 639 640 case IPOPT_TS_TSONLY: 641 break; 642 643 case IPOPT_TS_TSANDADDR: 644 if (ipt->ipt_ptr + sizeof(n_time) + 645 sizeof(struct in_addr) > ipt->ipt_len) 646 goto bad; 647 ipaddr.sin_addr = dst; 648 ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr, 649 m->m_pkthdr.rcvif); 650 if (ia == 0) 651 continue; 652 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 653 (caddr_t)sin, sizeof(struct in_addr)); 654 ipt->ipt_ptr += sizeof(struct in_addr); 655 break; 656 657 case IPOPT_TS_PRESPEC: 658 if (ipt->ipt_ptr + sizeof(n_time) + 659 sizeof(struct in_addr) > ipt->ipt_len) 660 goto bad; 661 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 662 sizeof(struct in_addr)); 663 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 664 continue; 665 ipt->ipt_ptr += sizeof(struct in_addr); 666 break; 667 668 default: 669 goto bad; 670 } 671 ntime = iptime(); 672 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 673 sizeof(n_time)); 674 ipt->ipt_ptr += sizeof(n_time); 675 } 676 } 677 if (forward) { 678 ip_forward(m, 1); 679 return (1); 680 } 681 } 682 } 683 return (0); 684bad: 685 /* ip->ip_len -= ip->ip_hl << 2; XXX icmp_error adds in hdr length */ 686 687/* Not yet */ 688 icmp_error(m, type, code, 0, 0); 689 690 STAT(ipstat.ips_badoptions++); 691 return (1); 692} 693 694#endif /* notdef */ 695 696/* 697 * Strip out IP options, at higher 698 * level protocol in the kernel. 699 * Second argument is buffer to which options 700 * will be moved, and return value is their length. 701 * (XXX) should be deleted; last arg currently ignored. 702 */ 703void 704ip_stripoptions(register struct mbuf *m, struct mbuf *mopt) 705{ 706 register int i; 707 struct ip *ip = mtod(m, struct ip *); 708 register caddr_t opts; 709 int olen; 710 711 olen = (ip->ip_hl<<2) - sizeof (struct ip); 712 opts = (caddr_t)(ip + 1); 713 i = m->m_len - (sizeof (struct ip) + olen); 714 memcpy(opts, opts + olen, (unsigned)i); 715 m->m_len -= olen; 716 717 ip->ip_hl = sizeof(struct ip) >> 2; 718} 719