ip_reass.c revision 1549
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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 34 */ 35 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/malloc.h> 39#include <sys/mbuf.h> 40#include <sys/domain.h> 41#include <sys/protosw.h> 42#include <sys/socket.h> 43#include <sys/errno.h> 44#include <sys/time.h> 45#include <sys/kernel.h> 46 47#include <net/if.h> 48#include <net/route.h> 49 50#include <netinet/in.h> 51#include <netinet/in_systm.h> 52#include <netinet/ip.h> 53#include <netinet/in_pcb.h> 54#include <netinet/in_var.h> 55#include <netinet/ip_var.h> 56#include <netinet/ip_icmp.h> 57 58#ifndef IPFORWARDING 59#ifdef GATEWAY 60#define IPFORWARDING 1 /* forward IP packets not for us */ 61#else /* GATEWAY */ 62#define IPFORWARDING 0 /* don't forward IP packets not for us */ 63#endif /* GATEWAY */ 64#endif /* IPFORWARDING */ 65#ifndef IPSENDREDIRECTS 66#define IPSENDREDIRECTS 1 67#endif 68int ipforwarding = IPFORWARDING; 69int ipsendredirects = IPSENDREDIRECTS; 70int ip_defttl = IPDEFTTL; 71#ifdef DIAGNOSTIC 72int ipprintfs = 0; 73#endif 74 75extern struct domain inetdomain; 76extern struct protosw inetsw[]; 77u_char ip_protox[IPPROTO_MAX]; 78int ipqmaxlen = IFQ_MAXLEN; 79struct in_ifaddr *in_ifaddr; /* first inet address */ 80struct ifqueue ipintrq; 81 82/* 83 * We need to save the IP options in case a protocol wants to respond 84 * to an incoming packet over the same route if the packet got here 85 * using IP source routing. This allows connection establishment and 86 * maintenance when the remote end is on a network that is not known 87 * to us. 88 */ 89int ip_nhops = 0; 90static struct ip_srcrt { 91 struct in_addr dst; /* final destination */ 92 char nop; /* one NOP to align */ 93 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 94 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 95} ip_srcrt; 96 97#ifdef GATEWAY 98extern int if_index; 99u_long *ip_ifmatrix; 100#endif 101 102static void save_rte __P((u_char *, struct in_addr)); 103/* 104 * IP initialization: fill in IP protocol switch table. 105 * All protocols not implemented in kernel go to raw IP protocol handler. 106 */ 107void 108ip_init() 109{ 110 register struct protosw *pr; 111 register int i; 112 113 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 114 if (pr == 0) 115 panic("ip_init"); 116 for (i = 0; i < IPPROTO_MAX; i++) 117 ip_protox[i] = pr - inetsw; 118 for (pr = inetdomain.dom_protosw; 119 pr < inetdomain.dom_protoswNPROTOSW; pr++) 120 if (pr->pr_domain->dom_family == PF_INET && 121 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 122 ip_protox[pr->pr_protocol] = pr - inetsw; 123 ipq.next = ipq.prev = &ipq; 124 ip_id = time.tv_sec & 0xffff; 125 ipintrq.ifq_maxlen = ipqmaxlen; 126#ifdef GATEWAY 127 i = (if_index + 1) * (if_index + 1) * sizeof (u_long); 128 ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK); 129 bzero((char *)ip_ifmatrix, i); 130#endif 131} 132 133struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 134struct route ipforward_rt; 135 136/* 137 * Ip input routine. Checksum and byte swap header. If fragmented 138 * try to reassemble. Process options. Pass to next level. 139 */ 140void 141ipintr() 142{ 143 register struct ip *ip; 144 register struct mbuf *m; 145 register struct ipq *fp; 146 register struct in_ifaddr *ia; 147 int hlen, s; 148 149next: 150 /* 151 * Get next datagram off input queue and get IP header 152 * in first mbuf. 153 */ 154 s = splimp(); 155 IF_DEQUEUE(&ipintrq, m); 156 splx(s); 157 if (m == 0) 158 return; 159#ifdef DIAGNOSTIC 160 if ((m->m_flags & M_PKTHDR) == 0) 161 panic("ipintr no HDR"); 162#endif 163 /* 164 * If no IP addresses have been set yet but the interfaces 165 * are receiving, can't do anything with incoming packets yet. 166 */ 167 if (in_ifaddr == NULL) 168 goto bad; 169 ipstat.ips_total++; 170 if (m->m_len < sizeof (struct ip) && 171 (m = m_pullup(m, sizeof (struct ip))) == 0) { 172 ipstat.ips_toosmall++; 173 goto next; 174 } 175 ip = mtod(m, struct ip *); 176 if (ip->ip_v != IPVERSION) { 177 ipstat.ips_badvers++; 178 goto bad; 179 } 180 hlen = ip->ip_hl << 2; 181 if (hlen < sizeof(struct ip)) { /* minimum header length */ 182 ipstat.ips_badhlen++; 183 goto bad; 184 } 185 if (hlen > m->m_len) { 186 if ((m = m_pullup(m, hlen)) == 0) { 187 ipstat.ips_badhlen++; 188 goto next; 189 } 190 ip = mtod(m, struct ip *); 191 } 192 if (ip->ip_sum = in_cksum(m, hlen)) { 193 ipstat.ips_badsum++; 194 goto bad; 195 } 196 197 /* 198 * Convert fields to host representation. 199 */ 200 NTOHS(ip->ip_len); 201 if (ip->ip_len < hlen) { 202 ipstat.ips_badlen++; 203 goto bad; 204 } 205 NTOHS(ip->ip_id); 206 NTOHS(ip->ip_off); 207 208 /* 209 * Check that the amount of data in the buffers 210 * is as at least much as the IP header would have us expect. 211 * Trim mbufs if longer than we expect. 212 * Drop packet if shorter than we expect. 213 */ 214 if (m->m_pkthdr.len < ip->ip_len) { 215 ipstat.ips_tooshort++; 216 goto bad; 217 } 218 if (m->m_pkthdr.len > ip->ip_len) { 219 if (m->m_len == m->m_pkthdr.len) { 220 m->m_len = ip->ip_len; 221 m->m_pkthdr.len = ip->ip_len; 222 } else 223 m_adj(m, ip->ip_len - m->m_pkthdr.len); 224 } 225 226 /* 227 * Process options and, if not destined for us, 228 * ship it on. ip_dooptions returns 1 when an 229 * error was detected (causing an icmp message 230 * to be sent and the original packet to be freed). 231 */ 232 ip_nhops = 0; /* for source routed packets */ 233 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 234 goto next; 235 236 /* 237 * Check our list of addresses, to see if the packet is for us. 238 */ 239 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 240#define satosin(sa) ((struct sockaddr_in *)(sa)) 241 242 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 243 goto ours; 244 if ( 245#ifdef DIRECTED_BROADCAST 246 ia->ia_ifp == m->m_pkthdr.rcvif && 247#endif 248 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 249 u_long t; 250 251 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 252 ip->ip_dst.s_addr) 253 goto ours; 254 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 255 goto ours; 256 /* 257 * Look for all-0's host part (old broadcast addr), 258 * either for subnet or net. 259 */ 260 t = ntohl(ip->ip_dst.s_addr); 261 if (t == ia->ia_subnet) 262 goto ours; 263 if (t == ia->ia_net) 264 goto ours; 265 } 266 } 267 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 268 struct in_multi *inm; 269#ifdef MROUTING 270 extern struct socket *ip_mrouter; 271 272 if (ip_mrouter) { 273 /* 274 * If we are acting as a multicast router, all 275 * incoming multicast packets are passed to the 276 * kernel-level multicast forwarding function. 277 * The packet is returned (relatively) intact; if 278 * ip_mforward() returns a non-zero value, the packet 279 * must be discarded, else it may be accepted below. 280 * 281 * (The IP ident field is put in the same byte order 282 * as expected when ip_mforward() is called from 283 * ip_output().) 284 */ 285 ip->ip_id = htons(ip->ip_id); 286 if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { 287 ipstat.ips_cantforward++; 288 m_freem(m); 289 goto next; 290 } 291 ip->ip_id = ntohs(ip->ip_id); 292 293 /* 294 * The process-level routing demon needs to receive 295 * all multicast IGMP packets, whether or not this 296 * host belongs to their destination groups. 297 */ 298 if (ip->ip_p == IPPROTO_IGMP) 299 goto ours; 300 ipstat.ips_forward++; 301 } 302#endif 303 /* 304 * See if we belong to the destination multicast group on the 305 * arrival interface. 306 */ 307 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 308 if (inm == NULL) { 309 ipstat.ips_cantforward++; 310 m_freem(m); 311 goto next; 312 } 313 goto ours; 314 } 315 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 316 goto ours; 317 if (ip->ip_dst.s_addr == INADDR_ANY) 318 goto ours; 319 320 /* 321 * Not for us; forward if possible and desirable. 322 */ 323 if (ipforwarding == 0) { 324 ipstat.ips_cantforward++; 325 m_freem(m); 326 } else 327 ip_forward(m, 0); 328 goto next; 329 330ours: 331 /* 332 * If offset or IP_MF are set, must reassemble. 333 * Otherwise, nothing need be done. 334 * (We could look in the reassembly queue to see 335 * if the packet was previously fragmented, 336 * but it's not worth the time; just let them time out.) 337 */ 338 if (ip->ip_off &~ IP_DF) { 339 if (m->m_flags & M_EXT) { /* XXX */ 340 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 341 ipstat.ips_toosmall++; 342 goto next; 343 } 344 ip = mtod(m, struct ip *); 345 } 346 /* 347 * Look for queue of fragments 348 * of this datagram. 349 */ 350 for (fp = ipq.next; fp != &ipq; fp = fp->next) 351 if (ip->ip_id == fp->ipq_id && 352 ip->ip_src.s_addr == fp->ipq_src.s_addr && 353 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 354 ip->ip_p == fp->ipq_p) 355 goto found; 356 fp = 0; 357found: 358 359 /* 360 * Adjust ip_len to not reflect header, 361 * set ip_mff if more fragments are expected, 362 * convert offset of this to bytes. 363 */ 364 ip->ip_len -= hlen; 365 ((struct ipasfrag *)ip)->ipf_mff &= ~1; 366 if (ip->ip_off & IP_MF) 367 ((struct ipasfrag *)ip)->ipf_mff |= 1; 368 ip->ip_off <<= 3; 369 370 /* 371 * If datagram marked as having more fragments 372 * or if this is not the first fragment, 373 * attempt reassembly; if it succeeds, proceed. 374 */ 375 if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) { 376 ipstat.ips_fragments++; 377 ip = ip_reass((struct ipasfrag *)ip, fp); 378 if (ip == 0) 379 goto next; 380 ipstat.ips_reassembled++; 381 m = dtom(ip); 382 } else 383 if (fp) 384 ip_freef(fp); 385 } else 386 ip->ip_len -= hlen; 387 388 /* 389 * Switch out to protocol's input routine. 390 */ 391 ipstat.ips_delivered++; 392 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 393 goto next; 394bad: 395 m_freem(m); 396 goto next; 397} 398 399/* 400 * Take incoming datagram fragment and try to 401 * reassemble it into whole datagram. If a chain for 402 * reassembly of this datagram already exists, then it 403 * is given as fp; otherwise have to make a chain. 404 */ 405struct ip * 406ip_reass(ip, fp) 407 register struct ipasfrag *ip; 408 register struct ipq *fp; 409{ 410 register struct mbuf *m = dtom(ip); 411 register struct ipasfrag *q; 412 struct mbuf *t; 413 int hlen = ip->ip_hl << 2; 414 int i, next; 415 416 /* 417 * Presence of header sizes in mbufs 418 * would confuse code below. 419 */ 420 m->m_data += hlen; 421 m->m_len -= hlen; 422 423 /* 424 * If first fragment to arrive, create a reassembly queue. 425 */ 426 if (fp == 0) { 427 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 428 goto dropfrag; 429 fp = mtod(t, struct ipq *); 430 insque(fp, &ipq); 431 fp->ipq_ttl = IPFRAGTTL; 432 fp->ipq_p = ip->ip_p; 433 fp->ipq_id = ip->ip_id; 434 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 435 fp->ipq_src = ((struct ip *)ip)->ip_src; 436 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 437 q = (struct ipasfrag *)fp; 438 goto insert; 439 } 440 441 /* 442 * Find a segment which begins after this one does. 443 */ 444 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 445 if (q->ip_off > ip->ip_off) 446 break; 447 448 /* 449 * If there is a preceding segment, it may provide some of 450 * our data already. If so, drop the data from the incoming 451 * segment. If it provides all of our data, drop us. 452 */ 453 if (q->ipf_prev != (struct ipasfrag *)fp) { 454 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 455 if (i > 0) { 456 if (i >= ip->ip_len) 457 goto dropfrag; 458 m_adj(dtom(ip), i); 459 ip->ip_off += i; 460 ip->ip_len -= i; 461 } 462 } 463 464 /* 465 * While we overlap succeeding segments trim them or, 466 * if they are completely covered, dequeue them. 467 */ 468 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 469 i = (ip->ip_off + ip->ip_len) - q->ip_off; 470 if (i < q->ip_len) { 471 q->ip_len -= i; 472 q->ip_off += i; 473 m_adj(dtom(q), i); 474 break; 475 } 476 q = q->ipf_next; 477 m_freem(dtom(q->ipf_prev)); 478 ip_deq(q->ipf_prev); 479 } 480 481insert: 482 /* 483 * Stick new segment in its place; 484 * check for complete reassembly. 485 */ 486 ip_enq(ip, q->ipf_prev); 487 next = 0; 488 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 489 if (q->ip_off != next) 490 return (0); 491 next += q->ip_len; 492 } 493 if (q->ipf_prev->ipf_mff & 1) 494 return (0); 495 496 /* 497 * Reassembly is complete; concatenate fragments. 498 */ 499 q = fp->ipq_next; 500 m = dtom(q); 501 t = m->m_next; 502 m->m_next = 0; 503 m_cat(m, t); 504 q = q->ipf_next; 505 while (q != (struct ipasfrag *)fp) { 506 t = dtom(q); 507 q = q->ipf_next; 508 m_cat(m, t); 509 } 510 511 /* 512 * Create header for new ip packet by 513 * modifying header of first packet; 514 * dequeue and discard fragment reassembly header. 515 * Make header visible. 516 */ 517 ip = fp->ipq_next; 518 ip->ip_len = next; 519 ip->ipf_mff &= ~1; 520 ((struct ip *)ip)->ip_src = fp->ipq_src; 521 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 522 remque(fp); 523 (void) m_free(dtom(fp)); 524 m = dtom(ip); 525 m->m_len += (ip->ip_hl << 2); 526 m->m_data -= (ip->ip_hl << 2); 527 /* some debugging cruft by sklower, below, will go away soon */ 528 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 529 register int plen = 0; 530 for (t = m; m; m = m->m_next) 531 plen += m->m_len; 532 t->m_pkthdr.len = plen; 533 } 534 return ((struct ip *)ip); 535 536dropfrag: 537 ipstat.ips_fragdropped++; 538 m_freem(m); 539 return (0); 540} 541 542/* 543 * Free a fragment reassembly header and all 544 * associated datagrams. 545 */ 546void 547ip_freef(fp) 548 struct ipq *fp; 549{ 550 register struct ipasfrag *q, *p; 551 552 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 553 p = q->ipf_next; 554 ip_deq(q); 555 m_freem(dtom(q)); 556 } 557 remque(fp); 558 (void) m_free(dtom(fp)); 559} 560 561/* 562 * Put an ip fragment on a reassembly chain. 563 * Like insque, but pointers in middle of structure. 564 */ 565void 566ip_enq(p, prev) 567 register struct ipasfrag *p, *prev; 568{ 569 570 p->ipf_prev = prev; 571 p->ipf_next = prev->ipf_next; 572 prev->ipf_next->ipf_prev = p; 573 prev->ipf_next = p; 574} 575 576/* 577 * To ip_enq as remque is to insque. 578 */ 579void 580ip_deq(p) 581 register struct ipasfrag *p; 582{ 583 584 p->ipf_prev->ipf_next = p->ipf_next; 585 p->ipf_next->ipf_prev = p->ipf_prev; 586} 587 588/* 589 * IP timer processing; 590 * if a timer expires on a reassembly 591 * queue, discard it. 592 */ 593void 594ip_slowtimo() 595{ 596 register struct ipq *fp; 597 int s = splnet(); 598 599 fp = ipq.next; 600 if (fp == 0) { 601 splx(s); 602 return; 603 } 604 while (fp != &ipq) { 605 --fp->ipq_ttl; 606 fp = fp->next; 607 if (fp->prev->ipq_ttl == 0) { 608 ipstat.ips_fragtimeout++; 609 ip_freef(fp->prev); 610 } 611 } 612 splx(s); 613} 614 615/* 616 * Drain off all datagram fragments. 617 */ 618void 619ip_drain() 620{ 621 622 while (ipq.next != &ipq) { 623 ipstat.ips_fragdropped++; 624 ip_freef(ipq.next); 625 } 626} 627 628/* 629 * Do option processing on a datagram, 630 * possibly discarding it if bad options are encountered, 631 * or forwarding it if source-routed. 632 * Returns 1 if packet has been forwarded/freed, 633 * 0 if the packet should be processed further. 634 */ 635int 636ip_dooptions(m) 637 struct mbuf *m; 638{ 639 register struct ip *ip = mtod(m, struct ip *); 640 register u_char *cp; 641 register struct ip_timestamp *ipt; 642 register struct in_ifaddr *ia; 643 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 644 struct in_addr *sin, dst; 645 n_time ntime; 646 647 dst = ip->ip_dst; 648 cp = (u_char *)(ip + 1); 649 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 650 for (; cnt > 0; cnt -= optlen, cp += optlen) { 651 opt = cp[IPOPT_OPTVAL]; 652 if (opt == IPOPT_EOL) 653 break; 654 if (opt == IPOPT_NOP) 655 optlen = 1; 656 else { 657 optlen = cp[IPOPT_OLEN]; 658 if (optlen <= 0 || optlen > cnt) { 659 code = &cp[IPOPT_OLEN] - (u_char *)ip; 660 goto bad; 661 } 662 } 663 switch (opt) { 664 665 default: 666 break; 667 668 /* 669 * Source routing with record. 670 * Find interface with current destination address. 671 * If none on this machine then drop if strictly routed, 672 * or do nothing if loosely routed. 673 * Record interface address and bring up next address 674 * component. If strictly routed make sure next 675 * address is on directly accessible net. 676 */ 677 case IPOPT_LSRR: 678 case IPOPT_SSRR: 679 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 680 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 681 goto bad; 682 } 683 ipaddr.sin_addr = ip->ip_dst; 684 ia = (struct in_ifaddr *) 685 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 686 if (ia == 0) { 687 if (opt == IPOPT_SSRR) { 688 type = ICMP_UNREACH; 689 code = ICMP_UNREACH_SRCFAIL; 690 goto bad; 691 } 692 /* 693 * Loose routing, and not at next destination 694 * yet; nothing to do except forward. 695 */ 696 break; 697 } 698 off--; /* 0 origin */ 699 if (off > optlen - sizeof(struct in_addr)) { 700 /* 701 * End of source route. Should be for us. 702 */ 703 save_rte(cp, ip->ip_src); 704 break; 705 } 706 /* 707 * locate outgoing interface 708 */ 709 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 710 sizeof(ipaddr.sin_addr)); 711 if (opt == IPOPT_SSRR) { 712#define INA struct in_ifaddr * 713#define SA struct sockaddr * 714 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 715 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 716 } else 717 ia = ip_rtaddr(ipaddr.sin_addr); 718 if (ia == 0) { 719 type = ICMP_UNREACH; 720 code = ICMP_UNREACH_SRCFAIL; 721 goto bad; 722 } 723 ip->ip_dst = ipaddr.sin_addr; 724 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 725 (caddr_t)(cp + off), sizeof(struct in_addr)); 726 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 727 /* 728 * Let ip_intr's mcast routing check handle mcast pkts 729 */ 730 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 731 break; 732 733 case IPOPT_RR: 734 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 735 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 736 goto bad; 737 } 738 /* 739 * If no space remains, ignore. 740 */ 741 off--; /* 0 origin */ 742 if (off > optlen - sizeof(struct in_addr)) 743 break; 744 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 745 sizeof(ipaddr.sin_addr)); 746 /* 747 * locate outgoing interface; if we're the destination, 748 * use the incoming interface (should be same). 749 */ 750 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 751 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 752 type = ICMP_UNREACH; 753 code = ICMP_UNREACH_HOST; 754 goto bad; 755 } 756 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 757 (caddr_t)(cp + off), sizeof(struct in_addr)); 758 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 759 break; 760 761 case IPOPT_TS: 762 code = cp - (u_char *)ip; 763 ipt = (struct ip_timestamp *)cp; 764 if (ipt->ipt_len < 5) 765 goto bad; 766 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 767 if (++ipt->ipt_oflw == 0) 768 goto bad; 769 break; 770 } 771 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 772 switch (ipt->ipt_flg) { 773 774 case IPOPT_TS_TSONLY: 775 break; 776 777 case IPOPT_TS_TSANDADDR: 778 if (ipt->ipt_ptr + sizeof(n_time) + 779 sizeof(struct in_addr) > ipt->ipt_len) 780 goto bad; 781 ipaddr.sin_addr = dst; 782 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 783 m->m_pkthdr.rcvif); 784 if (ia == 0) 785 continue; 786 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 787 (caddr_t)sin, sizeof(struct in_addr)); 788 ipt->ipt_ptr += sizeof(struct in_addr); 789 break; 790 791 case IPOPT_TS_PRESPEC: 792 if (ipt->ipt_ptr + sizeof(n_time) + 793 sizeof(struct in_addr) > ipt->ipt_len) 794 goto bad; 795 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 796 sizeof(struct in_addr)); 797 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 798 continue; 799 ipt->ipt_ptr += sizeof(struct in_addr); 800 break; 801 802 default: 803 goto bad; 804 } 805 ntime = iptime(); 806 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 807 sizeof(n_time)); 808 ipt->ipt_ptr += sizeof(n_time); 809 } 810 } 811 if (forward) { 812 ip_forward(m, 1); 813 return (1); 814 } 815 return (0); 816bad: 817 ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */ 818 icmp_error(m, type, code, 0, 0); 819 ipstat.ips_badoptions++; 820 return (1); 821} 822 823/* 824 * Given address of next destination (final or next hop), 825 * return internet address info of interface to be used to get there. 826 */ 827struct in_ifaddr * 828ip_rtaddr(dst) 829 struct in_addr dst; 830{ 831 register struct sockaddr_in *sin; 832 833 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 834 835 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 836 if (ipforward_rt.ro_rt) { 837 RTFREE(ipforward_rt.ro_rt); 838 ipforward_rt.ro_rt = 0; 839 } 840 sin->sin_family = AF_INET; 841 sin->sin_len = sizeof(*sin); 842 sin->sin_addr = dst; 843 844 rtalloc(&ipforward_rt); 845 } 846 if (ipforward_rt.ro_rt == 0) 847 return ((struct in_ifaddr *)0); 848 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 849} 850 851/* 852 * Save incoming source route for use in replies, 853 * to be picked up later by ip_srcroute if the receiver is interested. 854 */ 855void 856save_rte(option, dst) 857 u_char *option; 858 struct in_addr dst; 859{ 860 unsigned olen; 861 862 olen = option[IPOPT_OLEN]; 863#ifdef DIAGNOSTIC 864 if (ipprintfs) 865 printf("save_rte: olen %d\n", olen); 866#endif 867 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 868 return; 869 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 870 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 871 ip_srcrt.dst = dst; 872} 873 874/* 875 * Retrieve incoming source route for use in replies, 876 * in the same form used by setsockopt. 877 * The first hop is placed before the options, will be removed later. 878 */ 879struct mbuf * 880ip_srcroute() 881{ 882 register struct in_addr *p, *q; 883 register struct mbuf *m; 884 885 if (ip_nhops == 0) 886 return ((struct mbuf *)0); 887 m = m_get(M_DONTWAIT, MT_SOOPTS); 888 if (m == 0) 889 return ((struct mbuf *)0); 890 891#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 892 893 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 894 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 895 OPTSIZ; 896#ifdef DIAGNOSTIC 897 if (ipprintfs) 898 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 899#endif 900 901 /* 902 * First save first hop for return route 903 */ 904 p = &ip_srcrt.route[ip_nhops - 1]; 905 *(mtod(m, struct in_addr *)) = *p--; 906#ifdef DIAGNOSTIC 907 if (ipprintfs) 908 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 909#endif 910 911 /* 912 * Copy option fields and padding (nop) to mbuf. 913 */ 914 ip_srcrt.nop = IPOPT_NOP; 915 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 916 bcopy((caddr_t)&ip_srcrt.nop, 917 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 918 q = (struct in_addr *)(mtod(m, caddr_t) + 919 sizeof(struct in_addr) + OPTSIZ); 920#undef OPTSIZ 921 /* 922 * Record return path as an IP source route, 923 * reversing the path (pointers are now aligned). 924 */ 925 while (p >= ip_srcrt.route) { 926#ifdef DIAGNOSTIC 927 if (ipprintfs) 928 printf(" %lx", ntohl(q->s_addr)); 929#endif 930 *q++ = *p--; 931 } 932 /* 933 * Last hop goes to final destination. 934 */ 935 *q = ip_srcrt.dst; 936#ifdef DIAGNOSTIC 937 if (ipprintfs) 938 printf(" %lx\n", ntohl(q->s_addr)); 939#endif 940 return (m); 941} 942 943/* 944 * Strip out IP options, at higher 945 * level protocol in the kernel. 946 * Second argument is buffer to which options 947 * will be moved, and return value is their length. 948 * XXX should be deleted; last arg currently ignored. 949 */ 950void 951ip_stripoptions(m, mopt) 952 register struct mbuf *m; 953 struct mbuf *mopt; 954{ 955 register int i; 956 struct ip *ip = mtod(m, struct ip *); 957 register caddr_t opts; 958 int olen; 959 960 olen = (ip->ip_hl<<2) - sizeof (struct ip); 961 opts = (caddr_t)(ip + 1); 962 i = m->m_len - (sizeof (struct ip) + olen); 963 bcopy(opts + olen, opts, (unsigned)i); 964 m->m_len -= olen; 965 if (m->m_flags & M_PKTHDR) 966 m->m_pkthdr.len -= olen; 967 ip->ip_hl = sizeof(struct ip) >> 2; 968} 969 970u_char inetctlerrmap[PRC_NCMDS] = { 971 0, 0, 0, 0, 972 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 973 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 974 EMSGSIZE, EHOSTUNREACH, 0, 0, 975 0, 0, 0, 0, 976 ENOPROTOOPT 977}; 978 979/* 980 * Forward a packet. If some error occurs return the sender 981 * an icmp packet. Note we can't always generate a meaningful 982 * icmp message because icmp doesn't have a large enough repertoire 983 * of codes and types. 984 * 985 * If not forwarding, just drop the packet. This could be confusing 986 * if ipforwarding was zero but some routing protocol was advancing 987 * us as a gateway to somewhere. However, we must let the routing 988 * protocol deal with that. 989 * 990 * The srcrt parameter indicates whether the packet is being forwarded 991 * via a source route. 992 */ 993void 994ip_forward(m, srcrt) 995 struct mbuf *m; 996 int srcrt; 997{ 998 register struct ip *ip = mtod(m, struct ip *); 999 register struct sockaddr_in *sin; 1000 register struct rtentry *rt; 1001 int error, type = 0, code = 0; 1002 struct mbuf *mcopy; 1003 n_long dest; 1004 struct ifnet *destifp; 1005 1006 dest = 0; 1007#ifdef DIAGNOSTIC 1008 if (ipprintfs) 1009 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 1010 ip->ip_dst, ip->ip_ttl); 1011#endif 1012 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 1013 ipstat.ips_cantforward++; 1014 m_freem(m); 1015 return; 1016 } 1017 HTONS(ip->ip_id); 1018 if (ip->ip_ttl <= IPTTLDEC) { 1019 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); 1020 return; 1021 } 1022 ip->ip_ttl -= IPTTLDEC; 1023 1024 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 1025 if ((rt = ipforward_rt.ro_rt) == 0 || 1026 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1027 if (ipforward_rt.ro_rt) { 1028 RTFREE(ipforward_rt.ro_rt); 1029 ipforward_rt.ro_rt = 0; 1030 } 1031 sin->sin_family = AF_INET; 1032 sin->sin_len = sizeof(*sin); 1033 sin->sin_addr = ip->ip_dst; 1034 1035 rtalloc(&ipforward_rt); 1036 if (ipforward_rt.ro_rt == 0) { 1037 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); 1038 return; 1039 } 1040 rt = ipforward_rt.ro_rt; 1041 } 1042 1043 /* 1044 * Save at most 64 bytes of the packet in case 1045 * we need to generate an ICMP message to the src. 1046 */ 1047 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1048 1049#ifdef GATEWAY 1050 ip_ifmatrix[rt->rt_ifp->if_index + 1051 if_index * m->m_pkthdr.rcvif->if_index]++; 1052#endif 1053 /* 1054 * If forwarding packet using same interface that it came in on, 1055 * perhaps should send a redirect to sender to shortcut a hop. 1056 * Only send redirect if source is sending directly to us, 1057 * and if packet was not source routed (or has any options). 1058 * Also, don't send redirect if forwarding using a default route 1059 * or a route modified by a redirect. 1060 */ 1061#define satosin(sa) ((struct sockaddr_in *)(sa)) 1062 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1063 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1064 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1065 ipsendredirects && !srcrt) { 1066#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1067 u_long src = ntohl(ip->ip_src.s_addr); 1068 1069 if (RTA(rt) && 1070 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1071 if (rt->rt_flags & RTF_GATEWAY) 1072 dest = satosin(rt->rt_gateway)->sin_addr.s_addr; 1073 else 1074 dest = ip->ip_dst.s_addr; 1075 /* Router requirements says to only send host redirects */ 1076 type = ICMP_REDIRECT; 1077 code = ICMP_REDIRECT_HOST; 1078#ifdef DIAGNOSTIC 1079 if (ipprintfs) 1080 printf("redirect (%d) to %lx\n", code, (u_long)dest); 1081#endif 1082 } 1083 } 1084 1085 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING 1086#ifdef DIRECTED_BROADCAST 1087 | IP_ALLOWBROADCAST 1088#endif 1089 , 0); 1090 if (error) 1091 ipstat.ips_cantforward++; 1092 else { 1093 ipstat.ips_forward++; 1094 if (type) 1095 ipstat.ips_redirectsent++; 1096 else { 1097 if (mcopy) 1098 m_freem(mcopy); 1099 return; 1100 } 1101 } 1102 if (mcopy == NULL) 1103 return; 1104 destifp = NULL; 1105 1106 switch (error) { 1107 1108 case 0: /* forwarded, but need redirect */ 1109 /* type, code set above */ 1110 break; 1111 1112 case ENETUNREACH: /* shouldn't happen, checked above */ 1113 case EHOSTUNREACH: 1114 case ENETDOWN: 1115 case EHOSTDOWN: 1116 default: 1117 type = ICMP_UNREACH; 1118 code = ICMP_UNREACH_HOST; 1119 break; 1120 1121 case EMSGSIZE: 1122 type = ICMP_UNREACH; 1123 code = ICMP_UNREACH_NEEDFRAG; 1124 if (ipforward_rt.ro_rt) 1125 destifp = ipforward_rt.ro_rt->rt_ifp; 1126 ipstat.ips_cantfrag++; 1127 break; 1128 1129 case ENOBUFS: 1130 type = ICMP_SOURCEQUENCH; 1131 code = 0; 1132 break; 1133 } 1134 icmp_error(mcopy, type, code, dest, destifp); 1135} 1136 1137int 1138ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 1139 int *name; 1140 u_int namelen; 1141 void *oldp; 1142 size_t *oldlenp; 1143 void *newp; 1144 size_t newlen; 1145{ 1146 /* All sysctl names at this level are terminal. */ 1147 if (namelen != 1) 1148 return (ENOTDIR); 1149 1150 switch (name[0]) { 1151 case IPCTL_FORWARDING: 1152 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding)); 1153 case IPCTL_SENDREDIRECTS: 1154 return (sysctl_int(oldp, oldlenp, newp, newlen, 1155 &ipsendredirects)); 1156 case IPCTL_DEFTTL: 1157 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl)); 1158#ifdef notyet 1159 case IPCTL_DEFMTU: 1160 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); 1161#endif 1162 default: 1163 return (EOPNOTSUPP); 1164 } 1165 /* NOTREACHED */ 1166} 1167