1 /* 2 * Copyright (c) 1982, 1986, 1988, 1993 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)ip_input.c 7.29 (Berkeley) 06/04/93 8 */ 9 10 #include <sys/param.h> 11 #include <sys/systm.h> 12 #include <sys/malloc.h> 13 #include <sys/mbuf.h> 14 #include <sys/domain.h> 15 #include <sys/protosw.h> 16 #include <sys/socket.h> 17 #include <sys/errno.h> 18 #include <sys/time.h> 19 #include <sys/kernel.h> 20 21 #include <net/if.h> 22 #include <net/route.h> 23 24 #include <netinet/in.h> 25 #include <netinet/in_systm.h> 26 #include <netinet/ip.h> 27 #include <netinet/in_pcb.h> 28 #include <netinet/in_var.h> 29 #include <netinet/ip_var.h> 30 #include <netinet/ip_icmp.h> 31 32 #ifndef IPFORWARDING 33 #ifdef GATEWAY 34 #define IPFORWARDING 1 /* forward IP packets not for us */ 35 #else /* GATEWAY */ 36 #define IPFORWARDING 0 /* don't forward IP packets not for us */ 37 #endif /* GATEWAY */ 38 #endif /* IPFORWARDING */ 39 #ifndef IPSENDREDIRECTS 40 #define IPSENDREDIRECTS 1 41 #endif 42 int ipforwarding = IPFORWARDING; 43 int ipsendredirects = IPSENDREDIRECTS; 44 int ip_defttl = IPDEFTTL; 45 #ifdef DIAGNOSTIC 46 int ipprintfs = 0; 47 #endif 48 49 extern struct domain inetdomain; 50 extern struct protosw inetsw[]; 51 u_char ip_protox[IPPROTO_MAX]; 52 int ipqmaxlen = IFQ_MAXLEN; 53 struct in_ifaddr *in_ifaddr; /* first inet address */ 54 struct ifqueue ipintrq; 55 56 /* 57 * We need to save the IP options in case a protocol wants to respond 58 * to an incoming packet over the same route if the packet got here 59 * using IP source routing. This allows connection establishment and 60 * maintenance when the remote end is on a network that is not known 61 * to us. 62 */ 63 int ip_nhops = 0; 64 static struct ip_srcrt { 65 struct in_addr dst; /* final destination */ 66 char nop; /* one NOP to align */ 67 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 68 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 69 } ip_srcrt; 70 71 #ifdef GATEWAY 72 extern int if_index; 73 u_long *ip_ifmatrix; 74 #endif 75 76 static void save_rte __P((u_char *, struct in_addr)); 77 /* 78 * IP initialization: fill in IP protocol switch table. 79 * All protocols not implemented in kernel go to raw IP protocol handler. 80 */ 81 void 82 ip_init() 83 { 84 register struct protosw *pr; 85 register int i; 86 87 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 88 if (pr == 0) 89 panic("ip_init"); 90 for (i = 0; i < IPPROTO_MAX; i++) 91 ip_protox[i] = pr - inetsw; 92 for (pr = inetdomain.dom_protosw; 93 pr < inetdomain.dom_protoswNPROTOSW; pr++) 94 if (pr->pr_domain->dom_family == PF_INET && 95 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 96 ip_protox[pr->pr_protocol] = pr - inetsw; 97 ipq.next = ipq.prev = &ipq; 98 ip_id = time.tv_sec & 0xffff; 99 ipintrq.ifq_maxlen = ipqmaxlen; 100 #ifdef GATEWAY 101 i = (if_index + 1) * (if_index + 1) * sizeof (u_long); 102 ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK); 103 bzero((char *)ip_ifmatrix, i); 104 #endif 105 } 106 107 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 108 struct route ipforward_rt; 109 110 /* 111 * Ip input routine. Checksum and byte swap header. If fragmented 112 * try to reassemble. Process options. Pass to next level. 113 */ 114 void 115 ipintr() 116 { 117 register struct ip *ip; 118 register struct mbuf *m; 119 register struct ipq *fp; 120 register struct in_ifaddr *ia; 121 int hlen, s; 122 123 next: 124 /* 125 * Get next datagram off input queue and get IP header 126 * in first mbuf. 127 */ 128 s = splimp(); 129 IF_DEQUEUE(&ipintrq, m); 130 splx(s); 131 if (m == 0) 132 return; 133 #ifdef DIAGNOSTIC 134 if ((m->m_flags & M_PKTHDR) == 0) 135 panic("ipintr no HDR"); 136 #endif 137 /* 138 * If no IP addresses have been set yet but the interfaces 139 * are receiving, can't do anything with incoming packets yet. 140 */ 141 if (in_ifaddr == NULL) 142 goto bad; 143 ipstat.ips_total++; 144 if (m->m_len < sizeof (struct ip) && 145 (m = m_pullup(m, sizeof (struct ip))) == 0) { 146 ipstat.ips_toosmall++; 147 goto next; 148 } 149 ip = mtod(m, struct ip *); 150 if (ip->ip_v != IPVERSION) { 151 ipstat.ips_badvers++; 152 goto bad; 153 } 154 hlen = ip->ip_hl << 2; 155 if (hlen < sizeof(struct ip)) { /* minimum header length */ 156 ipstat.ips_badhlen++; 157 goto bad; 158 } 159 if (hlen > m->m_len) { 160 if ((m = m_pullup(m, hlen)) == 0) { 161 ipstat.ips_badhlen++; 162 goto next; 163 } 164 ip = mtod(m, struct ip *); 165 } 166 if (ip->ip_sum = in_cksum(m, hlen)) { 167 ipstat.ips_badsum++; 168 goto bad; 169 } 170 171 /* 172 * Convert fields to host representation. 173 */ 174 NTOHS(ip->ip_len); 175 if (ip->ip_len < hlen) { 176 ipstat.ips_badlen++; 177 goto bad; 178 } 179 NTOHS(ip->ip_id); 180 NTOHS(ip->ip_off); 181 182 /* 183 * Check that the amount of data in the buffers 184 * is as at least much as the IP header would have us expect. 185 * Trim mbufs if longer than we expect. 186 * Drop packet if shorter than we expect. 187 */ 188 if (m->m_pkthdr.len < ip->ip_len) { 189 ipstat.ips_tooshort++; 190 goto bad; 191 } 192 if (m->m_pkthdr.len > ip->ip_len) { 193 if (m->m_len == m->m_pkthdr.len) { 194 m->m_len = ip->ip_len; 195 m->m_pkthdr.len = ip->ip_len; 196 } else 197 m_adj(m, ip->ip_len - m->m_pkthdr.len); 198 } 199 200 /* 201 * Process options and, if not destined for us, 202 * ship it on. ip_dooptions returns 1 when an 203 * error was detected (causing an icmp message 204 * to be sent and the original packet to be freed). 205 */ 206 ip_nhops = 0; /* for source routed packets */ 207 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 208 goto next; 209 210 /* 211 * Check our list of addresses, to see if the packet is for us. 212 */ 213 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 214 #define satosin(sa) ((struct sockaddr_in *)(sa)) 215 216 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 217 goto ours; 218 if ( 219 #ifdef DIRECTED_BROADCAST 220 ia->ia_ifp == m->m_pkthdr.rcvif && 221 #endif 222 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 223 u_long t; 224 225 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 226 ip->ip_dst.s_addr) 227 goto ours; 228 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 229 goto ours; 230 /* 231 * Look for all-0's host part (old broadcast addr), 232 * either for subnet or net. 233 */ 234 t = ntohl(ip->ip_dst.s_addr); 235 if (t == ia->ia_subnet) 236 goto ours; 237 if (t == ia->ia_net) 238 goto ours; 239 } 240 } 241 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 242 struct in_multi *inm; 243 #ifdef MROUTING 244 extern struct socket *ip_mrouter; 245 246 if (ip_mrouter) { 247 /* 248 * If we are acting as a multicast router, all 249 * incoming multicast packets are passed to the 250 * kernel-level multicast forwarding function. 251 * The packet is returned (relatively) intact; if 252 * ip_mforward() returns a non-zero value, the packet 253 * must be discarded, else it may be accepted below. 254 * 255 * (The IP ident field is put in the same byte order 256 * as expected when ip_mforward() is called from 257 * ip_output().) 258 */ 259 ip->ip_id = htons(ip->ip_id); 260 if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { 261 ipstat.ips_cantforward++; 262 m_freem(m); 263 goto next; 264 } 265 ip->ip_id = ntohs(ip->ip_id); 266 267 /* 268 * The process-level routing demon needs to receive 269 * all multicast IGMP packets, whether or not this 270 * host belongs to their destination groups. 271 */ 272 if (ip->ip_p == IPPROTO_IGMP) 273 goto ours; 274 ipstat.ips_forward++; 275 } 276 #endif 277 /* 278 * See if we belong to the destination multicast group on the 279 * arrival interface. 280 */ 281 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 282 if (inm == NULL) { 283 ipstat.ips_cantforward++; 284 m_freem(m); 285 goto next; 286 } 287 goto ours; 288 } 289 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 290 goto ours; 291 if (ip->ip_dst.s_addr == INADDR_ANY) 292 goto ours; 293 294 /* 295 * Not for us; forward if possible and desirable. 296 */ 297 if (ipforwarding == 0) { 298 ipstat.ips_cantforward++; 299 m_freem(m); 300 } else 301 ip_forward(m, 0); 302 goto next; 303 304 ours: 305 /* 306 * If offset or IP_MF are set, must reassemble. 307 * Otherwise, nothing need be done. 308 * (We could look in the reassembly queue to see 309 * if the packet was previously fragmented, 310 * but it's not worth the time; just let them time out.) 311 */ 312 if (ip->ip_off &~ IP_DF) { 313 if (m->m_flags & M_EXT) { /* XXX */ 314 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 315 ipstat.ips_toosmall++; 316 goto next; 317 } 318 ip = mtod(m, struct ip *); 319 } 320 /* 321 * Look for queue of fragments 322 * of this datagram. 323 */ 324 for (fp = ipq.next; fp != &ipq; fp = fp->next) 325 if (ip->ip_id == fp->ipq_id && 326 ip->ip_src.s_addr == fp->ipq_src.s_addr && 327 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 328 ip->ip_p == fp->ipq_p) 329 goto found; 330 fp = 0; 331 found: 332 333 /* 334 * Adjust ip_len to not reflect header, 335 * set ip_mff if more fragments are expected, 336 * convert offset of this to bytes. 337 */ 338 ip->ip_len -= hlen; 339 ((struct ipasfrag *)ip)->ipf_mff &= ~1; 340 if (ip->ip_off & IP_MF) 341 ((struct ipasfrag *)ip)->ipf_mff |= 1; 342 ip->ip_off <<= 3; 343 344 /* 345 * If datagram marked as having more fragments 346 * or if this is not the first fragment, 347 * attempt reassembly; if it succeeds, proceed. 348 */ 349 if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) { 350 ipstat.ips_fragments++; 351 ip = ip_reass((struct ipasfrag *)ip, fp); 352 if (ip == 0) 353 goto next; 354 ipstat.ips_reassembled++; 355 m = dtom(ip); 356 } else 357 if (fp) 358 ip_freef(fp); 359 } else 360 ip->ip_len -= hlen; 361 362 /* 363 * Switch out to protocol's input routine. 364 */ 365 ipstat.ips_delivered++; 366 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 367 goto next; 368 bad: 369 m_freem(m); 370 goto next; 371 } 372 373 /* 374 * Take incoming datagram fragment and try to 375 * reassemble it into whole datagram. If a chain for 376 * reassembly of this datagram already exists, then it 377 * is given as fp; otherwise have to make a chain. 378 */ 379 struct ip * 380 ip_reass(ip, fp) 381 register struct ipasfrag *ip; 382 register struct ipq *fp; 383 { 384 register struct mbuf *m = dtom(ip); 385 register struct ipasfrag *q; 386 struct mbuf *t; 387 int hlen = ip->ip_hl << 2; 388 int i, next; 389 390 /* 391 * Presence of header sizes in mbufs 392 * would confuse code below. 393 */ 394 m->m_data += hlen; 395 m->m_len -= hlen; 396 397 /* 398 * If first fragment to arrive, create a reassembly queue. 399 */ 400 if (fp == 0) { 401 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 402 goto dropfrag; 403 fp = mtod(t, struct ipq *); 404 insque(fp, &ipq); 405 fp->ipq_ttl = IPFRAGTTL; 406 fp->ipq_p = ip->ip_p; 407 fp->ipq_id = ip->ip_id; 408 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 409 fp->ipq_src = ((struct ip *)ip)->ip_src; 410 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 411 q = (struct ipasfrag *)fp; 412 goto insert; 413 } 414 415 /* 416 * Find a segment which begins after this one does. 417 */ 418 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 419 if (q->ip_off > ip->ip_off) 420 break; 421 422 /* 423 * If there is a preceding segment, it may provide some of 424 * our data already. If so, drop the data from the incoming 425 * segment. If it provides all of our data, drop us. 426 */ 427 if (q->ipf_prev != (struct ipasfrag *)fp) { 428 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 429 if (i > 0) { 430 if (i >= ip->ip_len) 431 goto dropfrag; 432 m_adj(dtom(ip), i); 433 ip->ip_off += i; 434 ip->ip_len -= i; 435 } 436 } 437 438 /* 439 * While we overlap succeeding segments trim them or, 440 * if they are completely covered, dequeue them. 441 */ 442 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 443 i = (ip->ip_off + ip->ip_len) - q->ip_off; 444 if (i < q->ip_len) { 445 q->ip_len -= i; 446 q->ip_off += i; 447 m_adj(dtom(q), i); 448 break; 449 } 450 q = q->ipf_next; 451 m_freem(dtom(q->ipf_prev)); 452 ip_deq(q->ipf_prev); 453 } 454 455 insert: 456 /* 457 * Stick new segment in its place; 458 * check for complete reassembly. 459 */ 460 ip_enq(ip, q->ipf_prev); 461 next = 0; 462 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 463 if (q->ip_off != next) 464 return (0); 465 next += q->ip_len; 466 } 467 if (q->ipf_prev->ipf_mff & 1) 468 return (0); 469 470 /* 471 * Reassembly is complete; concatenate fragments. 472 */ 473 q = fp->ipq_next; 474 m = dtom(q); 475 t = m->m_next; 476 m->m_next = 0; 477 m_cat(m, t); 478 q = q->ipf_next; 479 while (q != (struct ipasfrag *)fp) { 480 t = dtom(q); 481 q = q->ipf_next; 482 m_cat(m, t); 483 } 484 485 /* 486 * Create header for new ip packet by 487 * modifying header of first packet; 488 * dequeue and discard fragment reassembly header. 489 * Make header visible. 490 */ 491 ip = fp->ipq_next; 492 ip->ip_len = next; 493 ip->ipf_mff &= ~1; 494 ((struct ip *)ip)->ip_src = fp->ipq_src; 495 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 496 remque(fp); 497 (void) m_free(dtom(fp)); 498 m = dtom(ip); 499 m->m_len += (ip->ip_hl << 2); 500 m->m_data -= (ip->ip_hl << 2); 501 /* some debugging cruft by sklower, below, will go away soon */ 502 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 503 register int plen = 0; 504 for (t = m; m; m = m->m_next) 505 plen += m->m_len; 506 t->m_pkthdr.len = plen; 507 } 508 return ((struct ip *)ip); 509 510 dropfrag: 511 ipstat.ips_fragdropped++; 512 m_freem(m); 513 return (0); 514 } 515 516 /* 517 * Free a fragment reassembly header and all 518 * associated datagrams. 519 */ 520 void 521 ip_freef(fp) 522 struct ipq *fp; 523 { 524 register struct ipasfrag *q, *p; 525 526 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 527 p = q->ipf_next; 528 ip_deq(q); 529 m_freem(dtom(q)); 530 } 531 remque(fp); 532 (void) m_free(dtom(fp)); 533 } 534 535 /* 536 * Put an ip fragment on a reassembly chain. 537 * Like insque, but pointers in middle of structure. 538 */ 539 void 540 ip_enq(p, prev) 541 register struct ipasfrag *p, *prev; 542 { 543 544 p->ipf_prev = prev; 545 p->ipf_next = prev->ipf_next; 546 prev->ipf_next->ipf_prev = p; 547 prev->ipf_next = p; 548 } 549 550 /* 551 * To ip_enq as remque is to insque. 552 */ 553 void 554 ip_deq(p) 555 register struct ipasfrag *p; 556 { 557 558 p->ipf_prev->ipf_next = p->ipf_next; 559 p->ipf_next->ipf_prev = p->ipf_prev; 560 } 561 562 /* 563 * IP timer processing; 564 * if a timer expires on a reassembly 565 * queue, discard it. 566 */ 567 void 568 ip_slowtimo() 569 { 570 register struct ipq *fp; 571 int s = splnet(); 572 573 fp = ipq.next; 574 if (fp == 0) { 575 splx(s); 576 return; 577 } 578 while (fp != &ipq) { 579 --fp->ipq_ttl; 580 fp = fp->next; 581 if (fp->prev->ipq_ttl == 0) { 582 ipstat.ips_fragtimeout++; 583 ip_freef(fp->prev); 584 } 585 } 586 splx(s); 587 } 588 589 /* 590 * Drain off all datagram fragments. 591 */ 592 void 593 ip_drain() 594 { 595 596 while (ipq.next != &ipq) { 597 ipstat.ips_fragdropped++; 598 ip_freef(ipq.next); 599 } 600 } 601 602 /* 603 * Do option processing on a datagram, 604 * possibly discarding it if bad options are encountered, 605 * or forwarding it if source-routed. 606 * Returns 1 if packet has been forwarded/freed, 607 * 0 if the packet should be processed further. 608 */ 609 int 610 ip_dooptions(m) 611 struct mbuf *m; 612 { 613 register struct ip *ip = mtod(m, struct ip *); 614 register u_char *cp; 615 register struct ip_timestamp *ipt; 616 register struct in_ifaddr *ia; 617 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 618 struct in_addr *sin, dst; 619 n_time ntime; 620 621 dst = ip->ip_dst; 622 cp = (u_char *)(ip + 1); 623 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 624 for (; cnt > 0; cnt -= optlen, cp += optlen) { 625 opt = cp[IPOPT_OPTVAL]; 626 if (opt == IPOPT_EOL) 627 break; 628 if (opt == IPOPT_NOP) 629 optlen = 1; 630 else { 631 optlen = cp[IPOPT_OLEN]; 632 if (optlen <= 0 || optlen > cnt) { 633 code = &cp[IPOPT_OLEN] - (u_char *)ip; 634 goto bad; 635 } 636 } 637 switch (opt) { 638 639 default: 640 break; 641 642 /* 643 * Source routing with record. 644 * Find interface with current destination address. 645 * If none on this machine then drop if strictly routed, 646 * or do nothing if loosely routed. 647 * Record interface address and bring up next address 648 * component. If strictly routed make sure next 649 * address is on directly accessible net. 650 */ 651 case IPOPT_LSRR: 652 case IPOPT_SSRR: 653 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 654 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 655 goto bad; 656 } 657 ipaddr.sin_addr = ip->ip_dst; 658 ia = (struct in_ifaddr *) 659 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 660 if (ia == 0) { 661 if (opt == IPOPT_SSRR) { 662 type = ICMP_UNREACH; 663 code = ICMP_UNREACH_SRCFAIL; 664 goto bad; 665 } 666 /* 667 * Loose routing, and not at next destination 668 * yet; nothing to do except forward. 669 */ 670 break; 671 } 672 off--; /* 0 origin */ 673 if (off > optlen - sizeof(struct in_addr)) { 674 /* 675 * End of source route. Should be for us. 676 */ 677 save_rte(cp, ip->ip_src); 678 break; 679 } 680 /* 681 * locate outgoing interface 682 */ 683 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 684 sizeof(ipaddr.sin_addr)); 685 if (opt == IPOPT_SSRR) { 686 #define INA struct in_ifaddr * 687 #define SA struct sockaddr * 688 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 689 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 690 } else 691 ia = ip_rtaddr(ipaddr.sin_addr); 692 if (ia == 0) { 693 type = ICMP_UNREACH; 694 code = ICMP_UNREACH_SRCFAIL; 695 goto bad; 696 } 697 ip->ip_dst = ipaddr.sin_addr; 698 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 699 (caddr_t)(cp + off), sizeof(struct in_addr)); 700 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 701 /* 702 * Let ip_intr's mcast routing check handle mcast pkts 703 */ 704 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 705 break; 706 707 case IPOPT_RR: 708 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 709 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 710 goto bad; 711 } 712 /* 713 * If no space remains, ignore. 714 */ 715 off--; /* 0 origin */ 716 if (off > optlen - sizeof(struct in_addr)) 717 break; 718 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 719 sizeof(ipaddr.sin_addr)); 720 /* 721 * locate outgoing interface; if we're the destination, 722 * use the incoming interface (should be same). 723 */ 724 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 725 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 726 type = ICMP_UNREACH; 727 code = ICMP_UNREACH_HOST; 728 goto bad; 729 } 730 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 731 (caddr_t)(cp + off), sizeof(struct in_addr)); 732 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 733 break; 734 735 case IPOPT_TS: 736 code = cp - (u_char *)ip; 737 ipt = (struct ip_timestamp *)cp; 738 if (ipt->ipt_len < 5) 739 goto bad; 740 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 741 if (++ipt->ipt_oflw == 0) 742 goto bad; 743 break; 744 } 745 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 746 switch (ipt->ipt_flg) { 747 748 case IPOPT_TS_TSONLY: 749 break; 750 751 case IPOPT_TS_TSANDADDR: 752 if (ipt->ipt_ptr + sizeof(n_time) + 753 sizeof(struct in_addr) > ipt->ipt_len) 754 goto bad; 755 ipaddr.sin_addr = dst; 756 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 757 m->m_pkthdr.rcvif); 758 if (ia == 0) 759 continue; 760 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 761 (caddr_t)sin, sizeof(struct in_addr)); 762 ipt->ipt_ptr += sizeof(struct in_addr); 763 break; 764 765 case IPOPT_TS_PRESPEC: 766 if (ipt->ipt_ptr + sizeof(n_time) + 767 sizeof(struct in_addr) > ipt->ipt_len) 768 goto bad; 769 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 770 sizeof(struct in_addr)); 771 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 772 continue; 773 ipt->ipt_ptr += sizeof(struct in_addr); 774 break; 775 776 default: 777 goto bad; 778 } 779 ntime = iptime(); 780 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 781 sizeof(n_time)); 782 ipt->ipt_ptr += sizeof(n_time); 783 } 784 } 785 if (forward) { 786 ip_forward(m, 1); 787 return (1); 788 } 789 return (0); 790 bad: 791 ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */ 792 icmp_error(m, type, code, 0, 0); 793 ipstat.ips_badoptions++; 794 return (1); 795 } 796 797 /* 798 * Given address of next destination (final or next hop), 799 * return internet address info of interface to be used to get there. 800 */ 801 struct in_ifaddr * 802 ip_rtaddr(dst) 803 struct in_addr dst; 804 { 805 register struct sockaddr_in *sin; 806 807 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 808 809 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 810 if (ipforward_rt.ro_rt) { 811 RTFREE(ipforward_rt.ro_rt); 812 ipforward_rt.ro_rt = 0; 813 } 814 sin->sin_family = AF_INET; 815 sin->sin_len = sizeof(*sin); 816 sin->sin_addr = dst; 817 818 rtalloc(&ipforward_rt); 819 } 820 if (ipforward_rt.ro_rt == 0) 821 return ((struct in_ifaddr *)0); 822 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 823 } 824 825 /* 826 * Save incoming source route for use in replies, 827 * to be picked up later by ip_srcroute if the receiver is interested. 828 */ 829 void 830 save_rte(option, dst) 831 u_char *option; 832 struct in_addr dst; 833 { 834 unsigned olen; 835 836 olen = option[IPOPT_OLEN]; 837 #ifdef DIAGNOSTIC 838 if (ipprintfs) 839 printf("save_rte: olen %d\n", olen); 840 #endif 841 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 842 return; 843 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 844 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 845 ip_srcrt.dst = dst; 846 } 847 848 /* 849 * Retrieve incoming source route for use in replies, 850 * in the same form used by setsockopt. 851 * The first hop is placed before the options, will be removed later. 852 */ 853 struct mbuf * 854 ip_srcroute() 855 { 856 register struct in_addr *p, *q; 857 register struct mbuf *m; 858 859 if (ip_nhops == 0) 860 return ((struct mbuf *)0); 861 m = m_get(M_DONTWAIT, MT_SOOPTS); 862 if (m == 0) 863 return ((struct mbuf *)0); 864 865 #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 866 867 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 868 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 869 OPTSIZ; 870 #ifdef DIAGNOSTIC 871 if (ipprintfs) 872 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 873 #endif 874 875 /* 876 * First save first hop for return route 877 */ 878 p = &ip_srcrt.route[ip_nhops - 1]; 879 *(mtod(m, struct in_addr *)) = *p--; 880 #ifdef DIAGNOSTIC 881 if (ipprintfs) 882 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 883 #endif 884 885 /* 886 * Copy option fields and padding (nop) to mbuf. 887 */ 888 ip_srcrt.nop = IPOPT_NOP; 889 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 890 bcopy((caddr_t)&ip_srcrt.nop, 891 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 892 q = (struct in_addr *)(mtod(m, caddr_t) + 893 sizeof(struct in_addr) + OPTSIZ); 894 #undef OPTSIZ 895 /* 896 * Record return path as an IP source route, 897 * reversing the path (pointers are now aligned). 898 */ 899 while (p >= ip_srcrt.route) { 900 #ifdef DIAGNOSTIC 901 if (ipprintfs) 902 printf(" %lx", ntohl(q->s_addr)); 903 #endif 904 *q++ = *p--; 905 } 906 /* 907 * Last hop goes to final destination. 908 */ 909 *q = ip_srcrt.dst; 910 #ifdef DIAGNOSTIC 911 if (ipprintfs) 912 printf(" %lx\n", ntohl(q->s_addr)); 913 #endif 914 return (m); 915 } 916 917 /* 918 * Strip out IP options, at higher 919 * level protocol in the kernel. 920 * Second argument is buffer to which options 921 * will be moved, and return value is their length. 922 * XXX should be deleted; last arg currently ignored. 923 */ 924 void 925 ip_stripoptions(m, mopt) 926 register struct mbuf *m; 927 struct mbuf *mopt; 928 { 929 register int i; 930 struct ip *ip = mtod(m, struct ip *); 931 register caddr_t opts; 932 int olen; 933 934 olen = (ip->ip_hl<<2) - sizeof (struct ip); 935 opts = (caddr_t)(ip + 1); 936 i = m->m_len - (sizeof (struct ip) + olen); 937 bcopy(opts + olen, opts, (unsigned)i); 938 m->m_len -= olen; 939 if (m->m_flags & M_PKTHDR) 940 m->m_pkthdr.len -= olen; 941 ip->ip_hl = sizeof(struct ip) >> 2; 942 } 943 944 u_char inetctlerrmap[PRC_NCMDS] = { 945 0, 0, 0, 0, 946 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 947 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 948 EMSGSIZE, EHOSTUNREACH, 0, 0, 949 0, 0, 0, 0, 950 ENOPROTOOPT 951 }; 952 953 /* 954 * Forward a packet. If some error occurs return the sender 955 * an icmp packet. Note we can't always generate a meaningful 956 * icmp message because icmp doesn't have a large enough repertoire 957 * of codes and types. 958 * 959 * If not forwarding, just drop the packet. This could be confusing 960 * if ipforwarding was zero but some routing protocol was advancing 961 * us as a gateway to somewhere. However, we must let the routing 962 * protocol deal with that. 963 * 964 * The srcrt parameter indicates whether the packet is being forwarded 965 * via a source route. 966 */ 967 void 968 ip_forward(m, srcrt) 969 struct mbuf *m; 970 int srcrt; 971 { 972 register struct ip *ip = mtod(m, struct ip *); 973 register struct sockaddr_in *sin; 974 register struct rtentry *rt; 975 int error, type = 0, code; 976 struct mbuf *mcopy; 977 n_long dest; 978 struct ifnet *destifp; 979 980 dest = 0; 981 #ifdef DIAGNOSTIC 982 if (ipprintfs) 983 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 984 ip->ip_dst, ip->ip_ttl); 985 #endif 986 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 987 ipstat.ips_cantforward++; 988 m_freem(m); 989 return; 990 } 991 HTONS(ip->ip_id); 992 if (ip->ip_ttl <= IPTTLDEC) { 993 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); 994 return; 995 } 996 ip->ip_ttl -= IPTTLDEC; 997 998 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 999 if ((rt = ipforward_rt.ro_rt) == 0 || 1000 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1001 if (ipforward_rt.ro_rt) { 1002 RTFREE(ipforward_rt.ro_rt); 1003 ipforward_rt.ro_rt = 0; 1004 } 1005 sin->sin_family = AF_INET; 1006 sin->sin_len = sizeof(*sin); 1007 sin->sin_addr = ip->ip_dst; 1008 1009 rtalloc(&ipforward_rt); 1010 if (ipforward_rt.ro_rt == 0) { 1011 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); 1012 return; 1013 } 1014 rt = ipforward_rt.ro_rt; 1015 } 1016 1017 /* 1018 * Save at most 64 bytes of the packet in case 1019 * we need to generate an ICMP message to the src. 1020 */ 1021 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1022 1023 #ifdef GATEWAY 1024 ip_ifmatrix[rt->rt_ifp->if_index + 1025 if_index * m->m_pkthdr.rcvif->if_index]++; 1026 #endif 1027 /* 1028 * If forwarding packet using same interface that it came in on, 1029 * perhaps should send a redirect to sender to shortcut a hop. 1030 * Only send redirect if source is sending directly to us, 1031 * and if packet was not source routed (or has any options). 1032 * Also, don't send redirect if forwarding using a default route 1033 * or a route modified by a redirect. 1034 */ 1035 #define satosin(sa) ((struct sockaddr_in *)(sa)) 1036 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1037 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1038 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1039 ipsendredirects && !srcrt) { 1040 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1041 u_long src = ntohl(ip->ip_src.s_addr); 1042 u_long dst = ntohl(ip->ip_dst.s_addr); 1043 1044 if (RTA(rt) && 1045 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1046 if (rt->rt_flags & RTF_GATEWAY) 1047 dest = satosin(rt->rt_gateway)->sin_addr.s_addr; 1048 else 1049 dest = ip->ip_dst.s_addr; 1050 /* Router requirements says to only send host redirects */ 1051 type = ICMP_REDIRECT; 1052 code = ICMP_REDIRECT_HOST; 1053 #ifdef DIAGNOSTIC 1054 if (ipprintfs) 1055 printf("redirect (%d) to %lx\n", code, (u_long)dest); 1056 #endif 1057 } 1058 } 1059 1060 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING 1061 #ifdef DIRECTED_BROADCAST 1062 | IP_ALLOWBROADCAST 1063 #endif 1064 , 0); 1065 if (error) 1066 ipstat.ips_cantforward++; 1067 else { 1068 ipstat.ips_forward++; 1069 if (type) 1070 ipstat.ips_redirectsent++; 1071 else { 1072 if (mcopy) 1073 m_freem(mcopy); 1074 return; 1075 } 1076 } 1077 if (mcopy == NULL) 1078 return; 1079 destifp = NULL; 1080 1081 switch (error) { 1082 1083 case 0: /* forwarded, but need redirect */ 1084 /* type, code set above */ 1085 break; 1086 1087 case ENETUNREACH: /* shouldn't happen, checked above */ 1088 case EHOSTUNREACH: 1089 case ENETDOWN: 1090 case EHOSTDOWN: 1091 default: 1092 type = ICMP_UNREACH; 1093 code = ICMP_UNREACH_HOST; 1094 break; 1095 1096 case EMSGSIZE: 1097 type = ICMP_UNREACH; 1098 code = ICMP_UNREACH_NEEDFRAG; 1099 if (ipforward_rt.ro_rt) 1100 destifp = ipforward_rt.ro_rt->rt_ifp; 1101 ipstat.ips_cantfrag++; 1102 break; 1103 1104 case ENOBUFS: 1105 type = ICMP_SOURCEQUENCH; 1106 code = 0; 1107 break; 1108 } 1109 icmp_error(mcopy, type, code, dest, destifp); 1110 } 1111 1112 int 1113 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 1114 int *name; 1115 u_int namelen; 1116 void *oldp; 1117 size_t *oldlenp; 1118 void *newp; 1119 size_t newlen; 1120 { 1121 extern int ip_ttl; 1122 1123 /* all sysctl names at this level are terminal */ 1124 if (namelen != 1) 1125 return (ENOTDIR); 1126 1127 switch (name[0]) { 1128 case IPCTL_FORWARDING: 1129 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding)); 1130 case IPCTL_SENDREDIRECTS: 1131 return (sysctl_int(oldp, oldlenp, newp, newlen, 1132 &ipsendredirects)); 1133 case IPCTL_DEFTTL: 1134 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl)); 1135 #ifdef notyet 1136 case IPCTL_DEFMTU: 1137 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); 1138 #endif 1139 default: 1140 return (EOPNOTSUPP); 1141 } 1142 /* NOTREACHED */ 1143 } 1144