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 * $Id: ip_input.c,v 1.3 1994/08/02 07:48:38 davidg Exp $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/malloc.h> 40 #include <sys/mbuf.h> 41 #include <sys/domain.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/errno.h> 45 #include <sys/time.h> 46 #include <sys/kernel.h> 47 48 #include <net/if.h> 49 #include <net/route.h> 50 51 #include <netinet/in.h> 52 #include <netinet/in_systm.h> 53 #include <netinet/ip.h> 54 #include <netinet/in_pcb.h> 55 #include <netinet/in_var.h> 56 #include <netinet/ip_var.h> 57 #include <netinet/ip_icmp.h> 58 59 #ifndef IPFORWARDING 60 #ifdef GATEWAY 61 #define IPFORWARDING 1 /* forward IP packets not for us */ 62 #else /* GATEWAY */ 63 #define IPFORWARDING 0 /* don't forward IP packets not for us */ 64 #endif /* GATEWAY */ 65 #endif /* IPFORWARDING */ 66 #ifndef IPSENDREDIRECTS 67 #define IPSENDREDIRECTS 1 68 #endif 69 int ipforwarding = IPFORWARDING; 70 int ipsendredirects = IPSENDREDIRECTS; 71 int ip_defttl = IPDEFTTL; 72 #ifdef DIAGNOSTIC 73 int ipprintfs = 0; 74 #endif 75 76 extern struct domain inetdomain; 77 extern struct protosw inetsw[]; 78 u_char ip_protox[IPPROTO_MAX]; 79 int ipqmaxlen = IFQ_MAXLEN; 80 struct in_ifaddr *in_ifaddr; /* first inet address */ 81 struct ifqueue ipintrq; 82 83 struct ipstat ipstat; 84 struct ipq ipq; 85 86 /* 87 * We need to save the IP options in case a protocol wants to respond 88 * to an incoming packet over the same route if the packet got here 89 * using IP source routing. This allows connection establishment and 90 * maintenance when the remote end is on a network that is not known 91 * to us. 92 */ 93 int ip_nhops = 0; 94 static struct ip_srcrt { 95 struct in_addr dst; /* final destination */ 96 char nop; /* one NOP to align */ 97 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 98 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 99 } ip_srcrt; 100 101 #ifdef GATEWAY 102 extern int if_index; 103 u_long *ip_ifmatrix; 104 #endif 105 106 static void save_rte __P((u_char *, struct in_addr)); 107 /* 108 * IP initialization: fill in IP protocol switch table. 109 * All protocols not implemented in kernel go to raw IP protocol handler. 110 */ 111 void 112 ip_init() 113 { 114 register struct protosw *pr; 115 register int i; 116 117 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 118 if (pr == 0) 119 panic("ip_init"); 120 for (i = 0; i < IPPROTO_MAX; i++) 121 ip_protox[i] = pr - inetsw; 122 for (pr = inetdomain.dom_protosw; 123 pr < inetdomain.dom_protoswNPROTOSW; pr++) 124 if (pr->pr_domain->dom_family == PF_INET && 125 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 126 ip_protox[pr->pr_protocol] = pr - inetsw; 127 ipq.next = ipq.prev = &ipq; 128 ip_id = time.tv_sec & 0xffff; 129 ipintrq.ifq_maxlen = ipqmaxlen; 130 #ifdef GATEWAY 131 i = (if_index + 1) * (if_index + 1) * sizeof (u_long); 132 ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK); 133 bzero((char *)ip_ifmatrix, i); 134 #endif 135 } 136 137 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 138 struct route ipforward_rt; 139 140 /* 141 * Ip input routine. Checksum and byte swap header. If fragmented 142 * try to reassemble. Process options. Pass to next level. 143 */ 144 void 145 ipintr() 146 { 147 register struct ip *ip; 148 register struct mbuf *m; 149 register struct ipq *fp; 150 register struct in_ifaddr *ia; 151 int hlen, s; 152 153 next: 154 /* 155 * Get next datagram off input queue and get IP header 156 * in first mbuf. 157 */ 158 s = splimp(); 159 IF_DEQUEUE(&ipintrq, m); 160 splx(s); 161 if (m == 0) 162 return; 163 #ifdef DIAGNOSTIC 164 if ((m->m_flags & M_PKTHDR) == 0) 165 panic("ipintr no HDR"); 166 #endif 167 /* 168 * If no IP addresses have been set yet but the interfaces 169 * are receiving, can't do anything with incoming packets yet. 170 */ 171 if (in_ifaddr == NULL) 172 goto bad; 173 ipstat.ips_total++; 174 if (m->m_len < sizeof (struct ip) && 175 (m = m_pullup(m, sizeof (struct ip))) == 0) { 176 ipstat.ips_toosmall++; 177 goto next; 178 } 179 ip = mtod(m, struct ip *); 180 if (ip->ip_v != IPVERSION) { 181 ipstat.ips_badvers++; 182 goto bad; 183 } 184 hlen = ip->ip_hl << 2; 185 if (hlen < sizeof(struct ip)) { /* minimum header length */ 186 ipstat.ips_badhlen++; 187 goto bad; 188 } 189 if (hlen > m->m_len) { 190 if ((m = m_pullup(m, hlen)) == 0) { 191 ipstat.ips_badhlen++; 192 goto next; 193 } 194 ip = mtod(m, struct ip *); 195 } 196 if (ip->ip_sum = in_cksum(m, hlen)) { 197 ipstat.ips_badsum++; 198 goto bad; 199 } 200 201 /* 202 * Convert fields to host representation. 203 */ 204 NTOHS(ip->ip_len); 205 if (ip->ip_len < hlen) { 206 ipstat.ips_badlen++; 207 goto bad; 208 } 209 NTOHS(ip->ip_id); 210 NTOHS(ip->ip_off); 211 212 /* 213 * Check that the amount of data in the buffers 214 * is as at least much as the IP header would have us expect. 215 * Trim mbufs if longer than we expect. 216 * Drop packet if shorter than we expect. 217 */ 218 if (m->m_pkthdr.len < ip->ip_len) { 219 ipstat.ips_tooshort++; 220 goto bad; 221 } 222 if (m->m_pkthdr.len > ip->ip_len) { 223 if (m->m_len == m->m_pkthdr.len) { 224 m->m_len = ip->ip_len; 225 m->m_pkthdr.len = ip->ip_len; 226 } else 227 m_adj(m, ip->ip_len - m->m_pkthdr.len); 228 } 229 230 /* 231 * Process options and, if not destined for us, 232 * ship it on. ip_dooptions returns 1 when an 233 * error was detected (causing an icmp message 234 * to be sent and the original packet to be freed). 235 */ 236 ip_nhops = 0; /* for source routed packets */ 237 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 238 goto next; 239 240 /* 241 * Check our list of addresses, to see if the packet is for us. 242 */ 243 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 244 #define satosin(sa) ((struct sockaddr_in *)(sa)) 245 246 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 247 goto ours; 248 if ( 249 #ifdef DIRECTED_BROADCAST 250 ia->ia_ifp == m->m_pkthdr.rcvif && 251 #endif 252 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 253 u_long t; 254 255 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 256 ip->ip_dst.s_addr) 257 goto ours; 258 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 259 goto ours; 260 /* 261 * Look for all-0's host part (old broadcast addr), 262 * either for subnet or net. 263 */ 264 t = ntohl(ip->ip_dst.s_addr); 265 if (t == ia->ia_subnet) 266 goto ours; 267 if (t == ia->ia_net) 268 goto ours; 269 } 270 } 271 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 272 struct in_multi *inm; 273 #ifdef MROUTING 274 extern struct socket *ip_mrouter; 275 276 if (ip_mrouter) { 277 /* 278 * If we are acting as a multicast router, all 279 * incoming multicast packets are passed to the 280 * kernel-level multicast forwarding function. 281 * The packet is returned (relatively) intact; if 282 * ip_mforward() returns a non-zero value, the packet 283 * must be discarded, else it may be accepted below. 284 * 285 * (The IP ident field is put in the same byte order 286 * as expected when ip_mforward() is called from 287 * ip_output().) 288 */ 289 ip->ip_id = htons(ip->ip_id); 290 if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { 291 ipstat.ips_cantforward++; 292 m_freem(m); 293 goto next; 294 } 295 ip->ip_id = ntohs(ip->ip_id); 296 297 /* 298 * The process-level routing demon needs to receive 299 * all multicast IGMP packets, whether or not this 300 * host belongs to their destination groups. 301 */ 302 if (ip->ip_p == IPPROTO_IGMP) 303 goto ours; 304 ipstat.ips_forward++; 305 } 306 #endif 307 /* 308 * See if we belong to the destination multicast group on the 309 * arrival interface. 310 */ 311 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 312 if (inm == NULL) { 313 ipstat.ips_cantforward++; 314 m_freem(m); 315 goto next; 316 } 317 goto ours; 318 } 319 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 320 goto ours; 321 if (ip->ip_dst.s_addr == INADDR_ANY) 322 goto ours; 323 324 /* 325 * Not for us; forward if possible and desirable. 326 */ 327 if (ipforwarding == 0) { 328 ipstat.ips_cantforward++; 329 m_freem(m); 330 } else 331 ip_forward(m, 0); 332 goto next; 333 334 ours: 335 /* 336 * If offset or IP_MF are set, must reassemble. 337 * Otherwise, nothing need be done. 338 * (We could look in the reassembly queue to see 339 * if the packet was previously fragmented, 340 * but it's not worth the time; just let them time out.) 341 */ 342 if (ip->ip_off &~ IP_DF) { 343 if (m->m_flags & M_EXT) { /* XXX */ 344 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 345 ipstat.ips_toosmall++; 346 goto next; 347 } 348 ip = mtod(m, struct ip *); 349 } 350 /* 351 * Look for queue of fragments 352 * of this datagram. 353 */ 354 for (fp = ipq.next; fp != &ipq; fp = fp->next) 355 if (ip->ip_id == fp->ipq_id && 356 ip->ip_src.s_addr == fp->ipq_src.s_addr && 357 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 358 ip->ip_p == fp->ipq_p) 359 goto found; 360 fp = 0; 361 found: 362 363 /* 364 * Adjust ip_len to not reflect header, 365 * set ip_mff if more fragments are expected, 366 * convert offset of this to bytes. 367 */ 368 ip->ip_len -= hlen; 369 ((struct ipasfrag *)ip)->ipf_mff &= ~1; 370 if (ip->ip_off & IP_MF) 371 ((struct ipasfrag *)ip)->ipf_mff |= 1; 372 ip->ip_off <<= 3; 373 374 /* 375 * If datagram marked as having more fragments 376 * or if this is not the first fragment, 377 * attempt reassembly; if it succeeds, proceed. 378 */ 379 if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) { 380 ipstat.ips_fragments++; 381 ip = ip_reass((struct ipasfrag *)ip, fp); 382 if (ip == 0) 383 goto next; 384 ipstat.ips_reassembled++; 385 m = dtom(ip); 386 } else 387 if (fp) 388 ip_freef(fp); 389 } else 390 ip->ip_len -= hlen; 391 392 /* 393 * Switch out to protocol's input routine. 394 */ 395 ipstat.ips_delivered++; 396 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 397 goto next; 398 bad: 399 m_freem(m); 400 goto next; 401 } 402 403 /* 404 * Take incoming datagram fragment and try to 405 * reassemble it into whole datagram. If a chain for 406 * reassembly of this datagram already exists, then it 407 * is given as fp; otherwise have to make a chain. 408 */ 409 struct ip * 410 ip_reass(ip, fp) 411 register struct ipasfrag *ip; 412 register struct ipq *fp; 413 { 414 register struct mbuf *m = dtom(ip); 415 register struct ipasfrag *q; 416 struct mbuf *t; 417 int hlen = ip->ip_hl << 2; 418 int i, next; 419 420 /* 421 * Presence of header sizes in mbufs 422 * would confuse code below. 423 */ 424 m->m_data += hlen; 425 m->m_len -= hlen; 426 427 /* 428 * If first fragment to arrive, create a reassembly queue. 429 */ 430 if (fp == 0) { 431 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 432 goto dropfrag; 433 fp = mtod(t, struct ipq *); 434 insque(fp, &ipq); 435 fp->ipq_ttl = IPFRAGTTL; 436 fp->ipq_p = ip->ip_p; 437 fp->ipq_id = ip->ip_id; 438 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 439 fp->ipq_src = ((struct ip *)ip)->ip_src; 440 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 441 q = (struct ipasfrag *)fp; 442 goto insert; 443 } 444 445 /* 446 * Find a segment which begins after this one does. 447 */ 448 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 449 if (q->ip_off > ip->ip_off) 450 break; 451 452 /* 453 * If there is a preceding segment, it may provide some of 454 * our data already. If so, drop the data from the incoming 455 * segment. If it provides all of our data, drop us. 456 */ 457 if (q->ipf_prev != (struct ipasfrag *)fp) { 458 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 459 if (i > 0) { 460 if (i >= ip->ip_len) 461 goto dropfrag; 462 m_adj(dtom(ip), i); 463 ip->ip_off += i; 464 ip->ip_len -= i; 465 } 466 } 467 468 /* 469 * While we overlap succeeding segments trim them or, 470 * if they are completely covered, dequeue them. 471 */ 472 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 473 i = (ip->ip_off + ip->ip_len) - q->ip_off; 474 if (i < q->ip_len) { 475 q->ip_len -= i; 476 q->ip_off += i; 477 m_adj(dtom(q), i); 478 break; 479 } 480 q = q->ipf_next; 481 m_freem(dtom(q->ipf_prev)); 482 ip_deq(q->ipf_prev); 483 } 484 485 insert: 486 /* 487 * Stick new segment in its place; 488 * check for complete reassembly. 489 */ 490 ip_enq(ip, q->ipf_prev); 491 next = 0; 492 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 493 if (q->ip_off != next) 494 return (0); 495 next += q->ip_len; 496 } 497 if (q->ipf_prev->ipf_mff & 1) 498 return (0); 499 500 /* 501 * Reassembly is complete; concatenate fragments. 502 */ 503 q = fp->ipq_next; 504 m = dtom(q); 505 t = m->m_next; 506 m->m_next = 0; 507 m_cat(m, t); 508 q = q->ipf_next; 509 while (q != (struct ipasfrag *)fp) { 510 t = dtom(q); 511 q = q->ipf_next; 512 m_cat(m, t); 513 } 514 515 /* 516 * Create header for new ip packet by 517 * modifying header of first packet; 518 * dequeue and discard fragment reassembly header. 519 * Make header visible. 520 */ 521 ip = fp->ipq_next; 522 ip->ip_len = next; 523 ip->ipf_mff &= ~1; 524 ((struct ip *)ip)->ip_src = fp->ipq_src; 525 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 526 remque(fp); 527 (void) m_free(dtom(fp)); 528 m = dtom(ip); 529 m->m_len += (ip->ip_hl << 2); 530 m->m_data -= (ip->ip_hl << 2); 531 /* some debugging cruft by sklower, below, will go away soon */ 532 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 533 register int plen = 0; 534 for (t = m; m; m = m->m_next) 535 plen += m->m_len; 536 t->m_pkthdr.len = plen; 537 } 538 return ((struct ip *)ip); 539 540 dropfrag: 541 ipstat.ips_fragdropped++; 542 m_freem(m); 543 return (0); 544 } 545 546 /* 547 * Free a fragment reassembly header and all 548 * associated datagrams. 549 */ 550 void 551 ip_freef(fp) 552 struct ipq *fp; 553 { 554 register struct ipasfrag *q, *p; 555 556 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 557 p = q->ipf_next; 558 ip_deq(q); 559 m_freem(dtom(q)); 560 } 561 remque(fp); 562 (void) m_free(dtom(fp)); 563 } 564 565 /* 566 * Put an ip fragment on a reassembly chain. 567 * Like insque, but pointers in middle of structure. 568 */ 569 void 570 ip_enq(p, prev) 571 register struct ipasfrag *p, *prev; 572 { 573 574 p->ipf_prev = prev; 575 p->ipf_next = prev->ipf_next; 576 prev->ipf_next->ipf_prev = p; 577 prev->ipf_next = p; 578 } 579 580 /* 581 * To ip_enq as remque is to insque. 582 */ 583 void 584 ip_deq(p) 585 register struct ipasfrag *p; 586 { 587 588 p->ipf_prev->ipf_next = p->ipf_next; 589 p->ipf_next->ipf_prev = p->ipf_prev; 590 } 591 592 /* 593 * IP timer processing; 594 * if a timer expires on a reassembly 595 * queue, discard it. 596 */ 597 void 598 ip_slowtimo() 599 { 600 register struct ipq *fp; 601 int s = splnet(); 602 603 fp = ipq.next; 604 if (fp == 0) { 605 splx(s); 606 return; 607 } 608 while (fp != &ipq) { 609 --fp->ipq_ttl; 610 fp = fp->next; 611 if (fp->prev->ipq_ttl == 0) { 612 ipstat.ips_fragtimeout++; 613 ip_freef(fp->prev); 614 } 615 } 616 splx(s); 617 } 618 619 /* 620 * Drain off all datagram fragments. 621 */ 622 void 623 ip_drain() 624 { 625 626 while (ipq.next != &ipq) { 627 ipstat.ips_fragdropped++; 628 ip_freef(ipq.next); 629 } 630 } 631 632 /* 633 * Do option processing on a datagram, 634 * possibly discarding it if bad options are encountered, 635 * or forwarding it if source-routed. 636 * Returns 1 if packet has been forwarded/freed, 637 * 0 if the packet should be processed further. 638 */ 639 int 640 ip_dooptions(m) 641 struct mbuf *m; 642 { 643 register struct ip *ip = mtod(m, struct ip *); 644 register u_char *cp; 645 register struct ip_timestamp *ipt; 646 register struct in_ifaddr *ia; 647 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 648 struct in_addr *sin, dst; 649 n_time ntime; 650 651 dst = ip->ip_dst; 652 cp = (u_char *)(ip + 1); 653 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 654 for (; cnt > 0; cnt -= optlen, cp += optlen) { 655 opt = cp[IPOPT_OPTVAL]; 656 if (opt == IPOPT_EOL) 657 break; 658 if (opt == IPOPT_NOP) 659 optlen = 1; 660 else { 661 optlen = cp[IPOPT_OLEN]; 662 if (optlen <= 0 || optlen > cnt) { 663 code = &cp[IPOPT_OLEN] - (u_char *)ip; 664 goto bad; 665 } 666 } 667 switch (opt) { 668 669 default: 670 break; 671 672 /* 673 * Source routing with record. 674 * Find interface with current destination address. 675 * If none on this machine then drop if strictly routed, 676 * or do nothing if loosely routed. 677 * Record interface address and bring up next address 678 * component. If strictly routed make sure next 679 * address is on directly accessible net. 680 */ 681 case IPOPT_LSRR: 682 case IPOPT_SSRR: 683 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 684 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 685 goto bad; 686 } 687 ipaddr.sin_addr = ip->ip_dst; 688 ia = (struct in_ifaddr *) 689 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 690 if (ia == 0) { 691 if (opt == IPOPT_SSRR) { 692 type = ICMP_UNREACH; 693 code = ICMP_UNREACH_SRCFAIL; 694 goto bad; 695 } 696 /* 697 * Loose routing, and not at next destination 698 * yet; nothing to do except forward. 699 */ 700 break; 701 } 702 off--; /* 0 origin */ 703 if (off > optlen - sizeof(struct in_addr)) { 704 /* 705 * End of source route. Should be for us. 706 */ 707 save_rte(cp, ip->ip_src); 708 break; 709 } 710 /* 711 * locate outgoing interface 712 */ 713 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 714 sizeof(ipaddr.sin_addr)); 715 if (opt == IPOPT_SSRR) { 716 #define INA struct in_ifaddr * 717 #define SA struct sockaddr * 718 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 719 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 720 } else 721 ia = ip_rtaddr(ipaddr.sin_addr); 722 if (ia == 0) { 723 type = ICMP_UNREACH; 724 code = ICMP_UNREACH_SRCFAIL; 725 goto bad; 726 } 727 ip->ip_dst = ipaddr.sin_addr; 728 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 729 (caddr_t)(cp + off), sizeof(struct in_addr)); 730 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 731 /* 732 * Let ip_intr's mcast routing check handle mcast pkts 733 */ 734 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 735 break; 736 737 case IPOPT_RR: 738 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 739 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 740 goto bad; 741 } 742 /* 743 * If no space remains, ignore. 744 */ 745 off--; /* 0 origin */ 746 if (off > optlen - sizeof(struct in_addr)) 747 break; 748 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 749 sizeof(ipaddr.sin_addr)); 750 /* 751 * locate outgoing interface; if we're the destination, 752 * use the incoming interface (should be same). 753 */ 754 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 755 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 756 type = ICMP_UNREACH; 757 code = ICMP_UNREACH_HOST; 758 goto bad; 759 } 760 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 761 (caddr_t)(cp + off), sizeof(struct in_addr)); 762 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 763 break; 764 765 case IPOPT_TS: 766 code = cp - (u_char *)ip; 767 ipt = (struct ip_timestamp *)cp; 768 if (ipt->ipt_len < 5) 769 goto bad; 770 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 771 if (++ipt->ipt_oflw == 0) 772 goto bad; 773 break; 774 } 775 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 776 switch (ipt->ipt_flg) { 777 778 case IPOPT_TS_TSONLY: 779 break; 780 781 case IPOPT_TS_TSANDADDR: 782 if (ipt->ipt_ptr + sizeof(n_time) + 783 sizeof(struct in_addr) > ipt->ipt_len) 784 goto bad; 785 ipaddr.sin_addr = dst; 786 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 787 m->m_pkthdr.rcvif); 788 if (ia == 0) 789 continue; 790 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 791 (caddr_t)sin, sizeof(struct in_addr)); 792 ipt->ipt_ptr += sizeof(struct in_addr); 793 break; 794 795 case IPOPT_TS_PRESPEC: 796 if (ipt->ipt_ptr + sizeof(n_time) + 797 sizeof(struct in_addr) > ipt->ipt_len) 798 goto bad; 799 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 800 sizeof(struct in_addr)); 801 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 802 continue; 803 ipt->ipt_ptr += sizeof(struct in_addr); 804 break; 805 806 default: 807 goto bad; 808 } 809 ntime = iptime(); 810 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 811 sizeof(n_time)); 812 ipt->ipt_ptr += sizeof(n_time); 813 } 814 } 815 if (forward) { 816 ip_forward(m, 1); 817 return (1); 818 } 819 return (0); 820 bad: 821 ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */ 822 icmp_error(m, type, code, 0, 0); 823 ipstat.ips_badoptions++; 824 return (1); 825 } 826 827 /* 828 * Given address of next destination (final or next hop), 829 * return internet address info of interface to be used to get there. 830 */ 831 struct in_ifaddr * 832 ip_rtaddr(dst) 833 struct in_addr dst; 834 { 835 register struct sockaddr_in *sin; 836 837 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 838 839 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 840 if (ipforward_rt.ro_rt) { 841 RTFREE(ipforward_rt.ro_rt); 842 ipforward_rt.ro_rt = 0; 843 } 844 sin->sin_family = AF_INET; 845 sin->sin_len = sizeof(*sin); 846 sin->sin_addr = dst; 847 848 rtalloc(&ipforward_rt); 849 } 850 if (ipforward_rt.ro_rt == 0) 851 return ((struct in_ifaddr *)0); 852 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 853 } 854 855 /* 856 * Save incoming source route for use in replies, 857 * to be picked up later by ip_srcroute if the receiver is interested. 858 */ 859 void 860 save_rte(option, dst) 861 u_char *option; 862 struct in_addr dst; 863 { 864 unsigned olen; 865 866 olen = option[IPOPT_OLEN]; 867 #ifdef DIAGNOSTIC 868 if (ipprintfs) 869 printf("save_rte: olen %d\n", olen); 870 #endif 871 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 872 return; 873 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 874 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 875 ip_srcrt.dst = dst; 876 } 877 878 /* 879 * Retrieve incoming source route for use in replies, 880 * in the same form used by setsockopt. 881 * The first hop is placed before the options, will be removed later. 882 */ 883 struct mbuf * 884 ip_srcroute() 885 { 886 register struct in_addr *p, *q; 887 register struct mbuf *m; 888 889 if (ip_nhops == 0) 890 return ((struct mbuf *)0); 891 m = m_get(M_DONTWAIT, MT_SOOPTS); 892 if (m == 0) 893 return ((struct mbuf *)0); 894 895 #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 896 897 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 898 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 899 OPTSIZ; 900 #ifdef DIAGNOSTIC 901 if (ipprintfs) 902 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 903 #endif 904 905 /* 906 * First save first hop for return route 907 */ 908 p = &ip_srcrt.route[ip_nhops - 1]; 909 *(mtod(m, struct in_addr *)) = *p--; 910 #ifdef DIAGNOSTIC 911 if (ipprintfs) 912 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 913 #endif 914 915 /* 916 * Copy option fields and padding (nop) to mbuf. 917 */ 918 ip_srcrt.nop = IPOPT_NOP; 919 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 920 bcopy((caddr_t)&ip_srcrt.nop, 921 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 922 q = (struct in_addr *)(mtod(m, caddr_t) + 923 sizeof(struct in_addr) + OPTSIZ); 924 #undef OPTSIZ 925 /* 926 * Record return path as an IP source route, 927 * reversing the path (pointers are now aligned). 928 */ 929 while (p >= ip_srcrt.route) { 930 #ifdef DIAGNOSTIC 931 if (ipprintfs) 932 printf(" %lx", ntohl(q->s_addr)); 933 #endif 934 *q++ = *p--; 935 } 936 /* 937 * Last hop goes to final destination. 938 */ 939 *q = ip_srcrt.dst; 940 #ifdef DIAGNOSTIC 941 if (ipprintfs) 942 printf(" %lx\n", ntohl(q->s_addr)); 943 #endif 944 return (m); 945 } 946 947 /* 948 * Strip out IP options, at higher 949 * level protocol in the kernel. 950 * Second argument is buffer to which options 951 * will be moved, and return value is their length. 952 * XXX should be deleted; last arg currently ignored. 953 */ 954 void 955 ip_stripoptions(m, mopt) 956 register struct mbuf *m; 957 struct mbuf *mopt; 958 { 959 register int i; 960 struct ip *ip = mtod(m, struct ip *); 961 register caddr_t opts; 962 int olen; 963 964 olen = (ip->ip_hl<<2) - sizeof (struct ip); 965 opts = (caddr_t)(ip + 1); 966 i = m->m_len - (sizeof (struct ip) + olen); 967 bcopy(opts + olen, opts, (unsigned)i); 968 m->m_len -= olen; 969 if (m->m_flags & M_PKTHDR) 970 m->m_pkthdr.len -= olen; 971 ip->ip_hl = sizeof(struct ip) >> 2; 972 } 973 974 u_char inetctlerrmap[PRC_NCMDS] = { 975 0, 0, 0, 0, 976 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 977 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 978 EMSGSIZE, EHOSTUNREACH, 0, 0, 979 0, 0, 0, 0, 980 ENOPROTOOPT 981 }; 982 983 /* 984 * Forward a packet. If some error occurs return the sender 985 * an icmp packet. Note we can't always generate a meaningful 986 * icmp message because icmp doesn't have a large enough repertoire 987 * of codes and types. 988 * 989 * If not forwarding, just drop the packet. This could be confusing 990 * if ipforwarding was zero but some routing protocol was advancing 991 * us as a gateway to somewhere. However, we must let the routing 992 * protocol deal with that. 993 * 994 * The srcrt parameter indicates whether the packet is being forwarded 995 * via a source route. 996 */ 997 void 998 ip_forward(m, srcrt) 999 struct mbuf *m; 1000 int srcrt; 1001 { 1002 register struct ip *ip = mtod(m, struct ip *); 1003 register struct sockaddr_in *sin; 1004 register struct rtentry *rt; 1005 int error, type = 0, code = 0; 1006 struct mbuf *mcopy; 1007 n_long dest; 1008 struct ifnet *destifp; 1009 1010 dest = 0; 1011 #ifdef DIAGNOSTIC 1012 if (ipprintfs) 1013 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 1014 ip->ip_dst, ip->ip_ttl); 1015 #endif 1016 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 1017 ipstat.ips_cantforward++; 1018 m_freem(m); 1019 return; 1020 } 1021 HTONS(ip->ip_id); 1022 if (ip->ip_ttl <= IPTTLDEC) { 1023 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); 1024 return; 1025 } 1026 ip->ip_ttl -= IPTTLDEC; 1027 1028 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 1029 if ((rt = ipforward_rt.ro_rt) == 0 || 1030 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1031 if (ipforward_rt.ro_rt) { 1032 RTFREE(ipforward_rt.ro_rt); 1033 ipforward_rt.ro_rt = 0; 1034 } 1035 sin->sin_family = AF_INET; 1036 sin->sin_len = sizeof(*sin); 1037 sin->sin_addr = ip->ip_dst; 1038 1039 rtalloc(&ipforward_rt); 1040 if (ipforward_rt.ro_rt == 0) { 1041 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); 1042 return; 1043 } 1044 rt = ipforward_rt.ro_rt; 1045 } 1046 1047 /* 1048 * Save at most 64 bytes of the packet in case 1049 * we need to generate an ICMP message to the src. 1050 */ 1051 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1052 1053 #ifdef GATEWAY 1054 ip_ifmatrix[rt->rt_ifp->if_index + 1055 if_index * m->m_pkthdr.rcvif->if_index]++; 1056 #endif 1057 /* 1058 * If forwarding packet using same interface that it came in on, 1059 * perhaps should send a redirect to sender to shortcut a hop. 1060 * Only send redirect if source is sending directly to us, 1061 * and if packet was not source routed (or has any options). 1062 * Also, don't send redirect if forwarding using a default route 1063 * or a route modified by a redirect. 1064 */ 1065 #define satosin(sa) ((struct sockaddr_in *)(sa)) 1066 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1067 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1068 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1069 ipsendredirects && !srcrt) { 1070 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1071 u_long src = ntohl(ip->ip_src.s_addr); 1072 1073 if (RTA(rt) && 1074 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1075 if (rt->rt_flags & RTF_GATEWAY) 1076 dest = satosin(rt->rt_gateway)->sin_addr.s_addr; 1077 else 1078 dest = ip->ip_dst.s_addr; 1079 /* Router requirements says to only send host redirects */ 1080 type = ICMP_REDIRECT; 1081 code = ICMP_REDIRECT_HOST; 1082 #ifdef DIAGNOSTIC 1083 if (ipprintfs) 1084 printf("redirect (%d) to %lx\n", code, (u_long)dest); 1085 #endif 1086 } 1087 } 1088 1089 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING 1090 #ifdef DIRECTED_BROADCAST 1091 | IP_ALLOWBROADCAST 1092 #endif 1093 , 0); 1094 if (error) 1095 ipstat.ips_cantforward++; 1096 else { 1097 ipstat.ips_forward++; 1098 if (type) 1099 ipstat.ips_redirectsent++; 1100 else { 1101 if (mcopy) 1102 m_freem(mcopy); 1103 return; 1104 } 1105 } 1106 if (mcopy == NULL) 1107 return; 1108 destifp = NULL; 1109 1110 switch (error) { 1111 1112 case 0: /* forwarded, but need redirect */ 1113 /* type, code set above */ 1114 break; 1115 1116 case ENETUNREACH: /* shouldn't happen, checked above */ 1117 case EHOSTUNREACH: 1118 case ENETDOWN: 1119 case EHOSTDOWN: 1120 default: 1121 type = ICMP_UNREACH; 1122 code = ICMP_UNREACH_HOST; 1123 break; 1124 1125 case EMSGSIZE: 1126 type = ICMP_UNREACH; 1127 code = ICMP_UNREACH_NEEDFRAG; 1128 if (ipforward_rt.ro_rt) 1129 destifp = ipforward_rt.ro_rt->rt_ifp; 1130 ipstat.ips_cantfrag++; 1131 break; 1132 1133 case ENOBUFS: 1134 type = ICMP_SOURCEQUENCH; 1135 code = 0; 1136 break; 1137 } 1138 icmp_error(mcopy, type, code, dest, destifp); 1139 } 1140 1141 int 1142 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 1143 int *name; 1144 u_int namelen; 1145 void *oldp; 1146 size_t *oldlenp; 1147 void *newp; 1148 size_t newlen; 1149 { 1150 /* All sysctl names at this level are terminal. */ 1151 if (namelen != 1) 1152 return (ENOTDIR); 1153 1154 switch (name[0]) { 1155 case IPCTL_FORWARDING: 1156 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding)); 1157 case IPCTL_SENDREDIRECTS: 1158 return (sysctl_int(oldp, oldlenp, newp, newlen, 1159 &ipsendredirects)); 1160 case IPCTL_DEFTTL: 1161 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl)); 1162 #ifdef notyet 1163 case IPCTL_DEFMTU: 1164 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); 1165 #endif 1166 default: 1167 return (EOPNOTSUPP); 1168 } 1169 /* NOTREACHED */ 1170 } 1171