ip_input.c revision 1.5
1/* 2 * Copyright (c) 1982, 1986, 1988 Regents of the University of California. 3 * 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 * from: @(#)ip_input.c 7.19 (Berkeley) 5/25/91 34 * $Id: ip_input.c,v 1.5 1993/12/18 00:41:57 mycroft 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 69int ipforwarding = IPFORWARDING; 70int ipsendredirects = IPSENDREDIRECTS; 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 */ 80 81/* 82 * We need to save the IP options in case a protocol wants to respond 83 * to an incoming packet over the same route if the packet got here 84 * using IP source routing. This allows connection establishment and 85 * maintenance when the remote end is on a network that is not known 86 * to us. 87 */ 88int ip_nhops = 0; 89static struct ip_srcrt { 90 struct in_addr dst; /* final destination */ 91 char nop; /* one NOP to align */ 92 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 93 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 94} ip_srcrt; 95 96#ifdef GATEWAY 97extern int if_index; 98u_long *ip_ifmatrix; 99#endif 100 101/* 102 * IP initialization: fill in IP protocol switch table. 103 * All protocols not implemented in kernel go to raw IP protocol handler. 104 */ 105ip_init() 106{ 107 register struct protosw *pr; 108 register int i; 109 110 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 111 if (pr == 0) 112 panic("ip_init"); 113 for (i = 0; i < IPPROTO_MAX; i++) 114 ip_protox[i] = pr - inetsw; 115 for (pr = inetdomain.dom_protosw; 116 pr < inetdomain.dom_protoswNPROTOSW; pr++) 117 if (pr->pr_domain->dom_family == PF_INET && 118 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 119 ip_protox[pr->pr_protocol] = pr - inetsw; 120 ipq.next = ipq.prev = &ipq; 121 ip_id = time.tv_sec & 0xffff; 122 ipintrq.ifq_maxlen = ipqmaxlen; 123#ifdef GATEWAY 124 i = (if_index + 1) * (if_index + 1) * sizeof (u_long); 125 if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0) 126 panic("no memory for ip_ifmatrix"); 127#endif 128} 129 130struct ip *ip_reass(); 131struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 132struct route ipforward_rt; 133 134/* 135 * Ip input routine. Checksum and byte swap header. If fragmented 136 * try to reassemble. Process options. Pass to next level. 137 */ 138ipintr() 139{ 140 register struct ip *ip; 141 register struct mbuf *m; 142 register struct ipq *fp; 143 register struct in_ifaddr *ia; 144 int hlen, s; 145#ifdef PARANOID 146 static int busy = 0; 147 148 if (busy) 149 panic("ipintr: called recursively\n"); 150 ++busy; 151#endif 152next: 153 /* 154 * Get next datagram off input queue and get IP header 155 * in first mbuf. 156 */ 157 s = splimp(); 158 IF_DEQUEUE(&ipintrq, m); 159 splx(s); 160 if (m == 0) { 161#ifdef PARANOID 162 --busy; 163#endif 164 return; 165 } 166#ifdef DIAGNOSTIC 167 if ((m->m_flags & M_PKTHDR) == 0) 168 panic("ipintr no HDR"); 169#endif 170 /* 171 * If no IP addresses have been set yet but the interfaces 172 * are receiving, can't do anything with incoming packets yet. 173 */ 174 if (in_ifaddr == NULL) 175 goto bad; 176 ipstat.ips_total++; 177 if (m->m_len < sizeof (struct ip) && 178 (m = m_pullup(m, sizeof (struct ip))) == 0) { 179 ipstat.ips_toosmall++; 180 goto next; 181 } 182 ip = mtod(m, struct ip *); 183 hlen = ip->ip_hl << 2; 184 if (hlen < sizeof(struct ip)) { /* minimum header length */ 185 ipstat.ips_badhlen++; 186 goto bad; 187 } 188 if (hlen > m->m_len) { 189 if ((m = m_pullup(m, hlen)) == 0) { 190 ipstat.ips_badhlen++; 191 goto next; 192 } 193 ip = mtod(m, struct ip *); 194 } 195 if (ip->ip_sum = in_cksum(m, hlen)) { 196 ipstat.ips_badsum++; 197 goto bad; 198 } 199 200 /* 201 * Convert fields to host representation. 202 */ 203 NTOHS(ip->ip_len); 204 if (ip->ip_len < hlen) { 205 ipstat.ips_badlen++; 206 goto bad; 207 } 208 NTOHS(ip->ip_id); 209 NTOHS(ip->ip_off); 210 211 /* 212 * Check that the amount of data in the buffers 213 * is as at least much as the IP header would have us expect. 214 * Trim mbufs if longer than we expect. 215 * Drop packet if shorter than we expect. 216 */ 217 if (m->m_pkthdr.len < ip->ip_len) { 218 ipstat.ips_tooshort++; 219 goto bad; 220 } 221 if (m->m_pkthdr.len > ip->ip_len) { 222 if (m->m_len == m->m_pkthdr.len) { 223 m->m_len = ip->ip_len; 224 m->m_pkthdr.len = ip->ip_len; 225 } else 226 m_adj(m, ip->ip_len - m->m_pkthdr.len); 227 } 228 229 /* 230 * Process options and, if not destined for us, 231 * ship it on. ip_dooptions returns 1 when an 232 * error was detected (causing an icmp message 233 * to be sent and the original packet to be freed). 234 */ 235 ip_nhops = 0; /* for source routed packets */ 236 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 237 goto next; 238 239 /* 240 * Check our list of addresses, to see if the packet is for us. 241 */ 242 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 243#define satosin(sa) ((struct sockaddr_in *)(sa)) 244 245 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 246 goto ours; 247 if ( 248#ifdef DIRECTED_BROADCAST 249 ia->ia_ifp == m->m_pkthdr.rcvif && 250#endif 251 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 252 u_long t; 253 254 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 255 ip->ip_dst.s_addr) 256 goto ours; 257 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 258 goto ours; 259 /* 260 * Look for all-0's host part (old broadcast addr), 261 * either for subnet or net. 262 */ 263 t = ntohl(ip->ip_dst.s_addr); 264 if (t == ia->ia_subnet) 265 goto ours; 266 if (t == ia->ia_net) 267 goto ours; 268 } 269 } 270#ifdef MULTICAST 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(ip, m->m_pkthdr.rcvif, m) != 0) { 291 m_freem(m); 292 goto next; 293 } 294 ip->ip_id = ntohs(ip->ip_id); 295 296 /* 297 * The process-level routing demon needs to receive 298 * all multicast IGMP packets, whether or not this 299 * host belongs to their destination groups. 300 */ 301 if (ip->ip_p == IPPROTO_IGMP) 302 goto ours; 303 } 304#endif 305 /* 306 * See if we belong to the destination multicast group on the 307 * arrival interface. 308 */ 309 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 310 if (inm == NULL) { 311 m_freem(m); 312 goto next; 313 } 314 goto ours; 315 } 316#endif 317 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 318 goto ours; 319 if (ip->ip_dst.s_addr == INADDR_ANY) 320 goto ours; 321 322 /* 323 * Not for us; forward if possible and desirable. 324 */ 325 if (ipforwarding == 0) { 326 ipstat.ips_cantforward++; 327 m_freem(m); 328 } else 329 ip_forward(m, 0); 330 goto next; 331 332ours: 333 /* 334 * If offset or IP_MF are set, must reassemble. 335 * Otherwise, nothing need be done. 336 * (We could look in the reassembly queue to see 337 * if the packet was previously fragmented, 338 * but it's not worth the time; just let them time out.) 339 */ 340 if (ip->ip_off &~ IP_DF) { 341 if (m->m_flags & M_EXT) { /* XXX */ 342 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 343 ipstat.ips_toosmall++; 344 goto next; 345 } 346 ip = mtod(m, struct ip *); 347 } 348 /* 349 * Look for queue of fragments 350 * of this datagram. 351 */ 352 for (fp = ipq.next; fp != &ipq; fp = fp->next) 353 if (ip->ip_id == fp->ipq_id && 354 ip->ip_src.s_addr == fp->ipq_src.s_addr && 355 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 356 ip->ip_p == fp->ipq_p) 357 goto found; 358 fp = 0; 359found: 360 361 /* 362 * Adjust ip_len to not reflect header, 363 * set ip_mff if more fragments are expected, 364 * convert offset of this to bytes. 365 */ 366 ip->ip_len -= hlen; 367 ((struct ipasfrag *)ip)->ipf_mff = 0; 368 if (ip->ip_off & IP_MF) 369 ((struct ipasfrag *)ip)->ipf_mff = 1; 370 ip->ip_off <<= 3; 371 372 /* 373 * If datagram marked as having more fragments 374 * or if this is not the first fragment, 375 * attempt reassembly; if it succeeds, proceed. 376 */ 377 if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) { 378 ipstat.ips_fragments++; 379 ip = ip_reass((struct ipasfrag *)ip, fp); 380 if (ip == 0) 381 goto next; 382 else 383 ipstat.ips_reassembled++; 384 m = dtom(ip); 385 } else 386 if (fp) 387 ip_freef(fp); 388 } else 389 ip->ip_len -= hlen; 390 391 /* 392 * Switch out to protocol's input routine. 393 */ 394 ipstat.ips_delivered++; 395 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 396 goto next; 397bad: 398 m_freem(m); 399 goto next; 400} 401 402/* 403 * Take incoming datagram fragment and try to 404 * reassemble it into whole datagram. If a chain for 405 * reassembly of this datagram already exists, then it 406 * is given as fp; otherwise have to make a chain. 407 */ 408struct ip * 409ip_reass(ip, fp) 410 register struct ipasfrag *ip; 411 register struct ipq *fp; 412{ 413 register struct mbuf *m = dtom(ip); 414 register struct ipasfrag *q; 415 struct mbuf *t; 416 int hlen = ip->ip_hl << 2; 417 int i, next; 418 419 /* 420 * Presence of header sizes in mbufs 421 * would confuse code below. 422 */ 423 m->m_data += hlen; 424 m->m_len -= hlen; 425 426 /* 427 * If first fragment to arrive, create a reassembly queue. 428 */ 429 if (fp == 0) { 430 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 431 goto dropfrag; 432 fp = mtod(t, struct ipq *); 433 insque(fp, &ipq); 434 fp->ipq_ttl = IPFRAGTTL; 435 fp->ipq_p = ip->ip_p; 436 fp->ipq_id = ip->ip_id; 437 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 438 fp->ipq_src = ((struct ip *)ip)->ip_src; 439 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 440 q = (struct ipasfrag *)fp; 441 goto insert; 442 } 443 444 /* 445 * Find a segment which begins after this one does. 446 */ 447 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 448 if (q->ip_off > ip->ip_off) 449 break; 450 451 /* 452 * If there is a preceding segment, it may provide some of 453 * our data already. If so, drop the data from the incoming 454 * segment. If it provides all of our data, drop us. 455 */ 456 if (q->ipf_prev != (struct ipasfrag *)fp) { 457 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 458 if (i > 0) { 459 if (i >= ip->ip_len) 460 goto dropfrag; 461 m_adj(dtom(ip), i); 462 ip->ip_off += i; 463 ip->ip_len -= i; 464 } 465 } 466 467 /* 468 * While we overlap succeeding segments trim them or, 469 * if they are completely covered, dequeue them. 470 */ 471 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 472 i = (ip->ip_off + ip->ip_len) - q->ip_off; 473 if (i < q->ip_len) { 474 q->ip_len -= i; 475 q->ip_off += i; 476 m_adj(dtom(q), i); 477 break; 478 } 479 q = q->ipf_next; 480 m_freem(dtom(q->ipf_prev)); 481 ip_deq(q->ipf_prev); 482 } 483 484insert: 485 /* 486 * Stick new segment in its place; 487 * check for complete reassembly. 488 */ 489 ip_enq(ip, q->ipf_prev); 490 next = 0; 491 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 492 if (q->ip_off != next) 493 return (0); 494 next += q->ip_len; 495 } 496 if (q->ipf_prev->ipf_mff) 497 return (0); 498 499 /* 500 * Reassembly is complete; concatenate fragments. 501 */ 502 q = fp->ipq_next; 503 m = dtom(q); 504 t = m->m_next; 505 m->m_next = 0; 506 m_cat(m, t); 507 q = q->ipf_next; 508 while (q != (struct ipasfrag *)fp) { 509 t = dtom(q); 510 q = q->ipf_next; 511 m_cat(m, t); 512 } 513 514 /* 515 * Create header for new ip packet by 516 * modifying header of first packet; 517 * dequeue and discard fragment reassembly header. 518 * Make header visible. 519 */ 520 ip = fp->ipq_next; 521 ip->ip_len = next; 522 ((struct ip *)ip)->ip_src = fp->ipq_src; 523 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 524 remque(fp); 525 (void) m_free(dtom(fp)); 526 m = dtom(ip); 527 m->m_len += (ip->ip_hl << 2); 528 m->m_data -= (ip->ip_hl << 2); 529 /* some debugging cruft by sklower, below, will go away soon */ 530 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 531 register int plen = 0; 532 for (t = m; m; m = m->m_next) 533 plen += m->m_len; 534 t->m_pkthdr.len = plen; 535 } 536 return ((struct ip *)ip); 537 538dropfrag: 539 ipstat.ips_fragdropped++; 540 m_freem(m); 541 return (0); 542} 543 544/* 545 * Free a fragment reassembly header and all 546 * associated datagrams. 547 */ 548ip_freef(fp) 549 struct ipq *fp; 550{ 551 register struct ipasfrag *q, *p; 552 553 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 554 p = q->ipf_next; 555 ip_deq(q); 556 m_freem(dtom(q)); 557 } 558 remque(fp); 559 (void) m_free(dtom(fp)); 560} 561 562/* 563 * Put an ip fragment on a reassembly chain. 564 * Like insque, but pointers in middle of structure. 565 */ 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 */ 579ip_deq(p) 580 register struct ipasfrag *p; 581{ 582 583 p->ipf_prev->ipf_next = p->ipf_next; 584 p->ipf_next->ipf_prev = p->ipf_prev; 585} 586 587/* 588 * IP timer processing; 589 * if a timer expires on a reassembly 590 * queue, discard it. 591 */ 592ip_slowtimo() 593{ 594 register struct ipq *fp; 595 int s = splnet(); 596 597 fp = ipq.next; 598 if (fp == 0) { 599 splx(s); 600 return; 601 } 602 while (fp != &ipq) { 603 --fp->ipq_ttl; 604 fp = fp->next; 605 if (fp->prev->ipq_ttl == 0) { 606 ipstat.ips_fragtimeout++; 607 ip_freef(fp->prev); 608 } 609 } 610 splx(s); 611} 612 613/* 614 * Drain off all datagram fragments. 615 */ 616ip_drain() 617{ 618 619 while (ipq.next != &ipq) { 620 ipstat.ips_fragdropped++; 621 ip_freef(ipq.next); 622 } 623} 624 625extern struct in_ifaddr *ifptoia(); 626struct in_ifaddr *ip_rtaddr(); 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 */ 635ip_dooptions(m) 636 struct mbuf *m; 637{ 638 register struct ip *ip = mtod(m, struct ip *); 639 register u_char *cp; 640 register struct ip_timestamp *ipt; 641 register struct in_ifaddr *ia; 642 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 643 struct in_addr *sin; 644 n_time ntime; 645 646 cp = (u_char *)(ip + 1); 647 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 648 for (; cnt > 0; cnt -= optlen, cp += optlen) { 649 opt = cp[IPOPT_OPTVAL]; 650 if (opt == IPOPT_EOL) 651 break; 652 if (opt == IPOPT_NOP) 653 optlen = 1; 654 else { 655 optlen = cp[IPOPT_OLEN]; 656 if (optlen <= 0 || optlen > cnt) { 657 code = &cp[IPOPT_OLEN] - (u_char *)ip; 658 goto bad; 659 } 660 } 661 switch (opt) { 662 663 default: 664 break; 665 666 /* 667 * Source routing with record. 668 * Find interface with current destination address. 669 * If none on this machine then drop if strictly routed, 670 * or do nothing if loosely routed. 671 * Record interface address and bring up next address 672 * component. If strictly routed make sure next 673 * address is on directly accessible net. 674 */ 675 case IPOPT_LSRR: 676 case IPOPT_SSRR: 677 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 678 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 679 goto bad; 680 } 681 ipaddr.sin_addr = ip->ip_dst; 682 ia = (struct in_ifaddr *) 683 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 684 if (ia == 0) { 685 if (opt == IPOPT_SSRR) { 686 type = ICMP_UNREACH; 687 code = ICMP_UNREACH_SRCFAIL; 688 goto bad; 689 } 690 /* 691 * Loose routing, and not at next destination 692 * yet; nothing to do except forward. 693 */ 694 break; 695 } 696 off--; /* 0 origin */ 697 if (off > optlen - sizeof(struct in_addr)) { 698 /* 699 * End of source route. Should be for us. 700 */ 701 save_rte(cp, ip->ip_src); 702 break; 703 } 704 /* 705 * locate outgoing interface 706 */ 707 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 708 sizeof(ipaddr.sin_addr)); 709 if (opt == IPOPT_SSRR) { 710#define INA struct in_ifaddr * 711#define SA struct sockaddr * 712 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 713 ia = in_iaonnetof(in_netof(ipaddr.sin_addr)); 714 } else 715 ia = ip_rtaddr(ipaddr.sin_addr); 716 if (ia == 0) { 717 type = ICMP_UNREACH; 718 code = ICMP_UNREACH_SRCFAIL; 719 goto bad; 720 } 721 ip->ip_dst = ipaddr.sin_addr; 722 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 723 (caddr_t)(cp + off), sizeof(struct in_addr)); 724 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 725 forward = 1; 726 break; 727 728 case IPOPT_RR: 729 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 730 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 731 goto bad; 732 } 733 /* 734 * If no space remains, ignore. 735 */ 736 off--; /* 0 origin */ 737 if (off > optlen - sizeof(struct in_addr)) 738 break; 739 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 740 sizeof(ipaddr.sin_addr)); 741 /* 742 * locate outgoing interface; if we're the destination, 743 * use the incoming interface (should be same). 744 */ 745 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 746 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 747 type = ICMP_UNREACH; 748 code = ICMP_UNREACH_HOST; 749 goto bad; 750 } 751 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 752 (caddr_t)(cp + off), sizeof(struct in_addr)); 753 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 754 break; 755 756 case IPOPT_TS: 757 code = cp - (u_char *)ip; 758 ipt = (struct ip_timestamp *)cp; 759 if (ipt->ipt_len < 5) 760 goto bad; 761 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 762 if (++ipt->ipt_oflw == 0) 763 goto bad; 764 break; 765 } 766 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 767 switch (ipt->ipt_flg) { 768 769 case IPOPT_TS_TSONLY: 770 break; 771 772 case IPOPT_TS_TSANDADDR: 773 if (ipt->ipt_ptr + sizeof(n_time) + 774 sizeof(struct in_addr) > ipt->ipt_len) 775 goto bad; 776 ia = ifptoia(m->m_pkthdr.rcvif); 777 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 778 (caddr_t)sin, sizeof(struct in_addr)); 779 ipt->ipt_ptr += sizeof(struct in_addr); 780 break; 781 782 case IPOPT_TS_PRESPEC: 783 if (ipt->ipt_ptr + sizeof(n_time) + 784 sizeof(struct in_addr) > ipt->ipt_len) 785 goto bad; 786 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 787 sizeof(struct in_addr)); 788 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 789 continue; 790 ipt->ipt_ptr += sizeof(struct in_addr); 791 break; 792 793 default: 794 goto bad; 795 } 796 ntime = iptime(); 797 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 798 sizeof(n_time)); 799 ipt->ipt_ptr += sizeof(n_time); 800 } 801 } 802 if (forward) { 803 ip_forward(m, 1); 804 return (1); 805 } else 806 return (0); 807bad: 808 icmp_error(m, type, code); 809 return (1); 810} 811 812/* 813 * Given address of next destination (final or next hop), 814 * return internet address info of interface to be used to get there. 815 */ 816struct in_ifaddr * 817ip_rtaddr(dst) 818 struct in_addr dst; 819{ 820 register struct sockaddr_in *sin; 821 822 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 823 824 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 825 if (ipforward_rt.ro_rt) { 826 RTFREE(ipforward_rt.ro_rt); 827 ipforward_rt.ro_rt = 0; 828 } 829 sin->sin_family = AF_INET; 830 sin->sin_len = sizeof(*sin); 831 sin->sin_addr = dst; 832 833 rtalloc(&ipforward_rt); 834 } 835 if (ipforward_rt.ro_rt == 0) 836 return ((struct in_ifaddr *)0); 837 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 838} 839 840/* 841 * Save incoming source route for use in replies, 842 * to be picked up later by ip_srcroute if the receiver is interested. 843 */ 844save_rte(option, dst) 845 u_char *option; 846 struct in_addr dst; 847{ 848 unsigned olen; 849 850 olen = option[IPOPT_OLEN]; 851#ifdef DIAGNOSTIC 852 if (ipprintfs) 853 printf("save_rte: olen %d\n", olen); 854#endif 855 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 856 return; 857 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 858 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 859 ip_srcrt.dst = dst; 860} 861 862/* 863 * Retrieve incoming source route for use in replies, 864 * in the same form used by setsockopt. 865 * The first hop is placed before the options, will be removed later. 866 */ 867struct mbuf * 868ip_srcroute() 869{ 870 register struct in_addr *p, *q; 871 register struct mbuf *m; 872 873 if (ip_nhops == 0) 874 return ((struct mbuf *)0); 875 m = m_get(M_DONTWAIT, MT_SOOPTS); 876 if (m == 0) 877 return ((struct mbuf *)0); 878 879#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 880 881 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 882 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 883 OPTSIZ; 884#ifdef DIAGNOSTIC 885 if (ipprintfs) 886 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 887#endif 888 889 /* 890 * First save first hop for return route 891 */ 892 p = &ip_srcrt.route[ip_nhops - 1]; 893 *(mtod(m, struct in_addr *)) = *p--; 894#ifdef DIAGNOSTIC 895 if (ipprintfs) 896 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 897#endif 898 899 /* 900 * Copy option fields and padding (nop) to mbuf. 901 */ 902 ip_srcrt.nop = IPOPT_NOP; 903 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 904 bcopy((caddr_t)&ip_srcrt.nop, 905 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 906 q = (struct in_addr *)(mtod(m, caddr_t) + 907 sizeof(struct in_addr) + OPTSIZ); 908#undef OPTSIZ 909 /* 910 * Record return path as an IP source route, 911 * reversing the path (pointers are now aligned). 912 */ 913 while (p >= ip_srcrt.route) { 914#ifdef DIAGNOSTIC 915 if (ipprintfs) 916 printf(" %lx", ntohl(q->s_addr)); 917#endif 918 *q++ = *p--; 919 } 920 /* 921 * Last hop goes to final destination. 922 */ 923 *q = ip_srcrt.dst; 924#ifdef DIAGNOSTIC 925 if (ipprintfs) 926 printf(" %lx\n", ntohl(q->s_addr)); 927#endif 928 return (m); 929} 930 931/* 932 * Strip out IP options, at higher 933 * level protocol in the kernel. 934 * Second argument is buffer to which options 935 * will be moved, and return value is their length. 936 * XXX should be deleted; last arg currently ignored. 937 */ 938ip_stripoptions(m, mopt) 939 register struct mbuf *m; 940 struct mbuf *mopt; 941{ 942 register int i; 943 struct ip *ip = mtod(m, struct ip *); 944 register caddr_t opts; 945 int olen; 946 947 olen = (ip->ip_hl<<2) - sizeof (struct ip); 948 opts = (caddr_t)(ip + 1); 949 i = m->m_len - (sizeof (struct ip) + olen); 950 bcopy(opts + olen, opts, (unsigned)i); 951 m->m_len -= olen; 952 if (m->m_flags & M_PKTHDR) 953 m->m_pkthdr.len -= olen; 954 ip->ip_hl = sizeof(struct ip) >> 2; 955} 956 957u_char inetctlerrmap[PRC_NCMDS] = { 958 0, 0, 0, 0, 959 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 960 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 961 EMSGSIZE, EHOSTUNREACH, 0, 0, 962 0, 0, 0, 0, 963 ENOPROTOOPT 964}; 965 966/* 967 * Forward a packet. If some error occurs return the sender 968 * an icmp packet. Note we can't always generate a meaningful 969 * icmp message because icmp doesn't have a large enough repertoire 970 * of codes and types. 971 * 972 * If not forwarding, just drop the packet. This could be confusing 973 * if ipforwarding was zero but some routing protocol was advancing 974 * us as a gateway to somewhere. However, we must let the routing 975 * protocol deal with that. 976 * 977 * The srcrt parameter indicates whether the packet is being forwarded 978 * via a source route. 979 */ 980ip_forward(m, srcrt) 981 struct mbuf *m; 982 int srcrt; 983{ 984 register struct ip *ip = mtod(m, struct ip *); 985 register struct sockaddr_in *sin; 986 register struct rtentry *rt; 987 int error, type = 0, code; 988 struct mbuf *mcopy; 989 struct in_addr dest; 990 991 dest.s_addr = 0; 992#ifdef DIAGNOSTIC 993 if (ipprintfs) 994 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 995 ip->ip_dst, ip->ip_ttl); 996#endif 997 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 998 ipstat.ips_cantforward++; 999 m_freem(m); 1000 return; 1001 } 1002 HTONS(ip->ip_id); 1003 if (ip->ip_ttl <= IPTTLDEC) { 1004 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest); 1005 return; 1006 } 1007 ip->ip_ttl -= IPTTLDEC; 1008 1009 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 1010 if ((rt = ipforward_rt.ro_rt) == 0 || 1011 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1012 if (ipforward_rt.ro_rt) { 1013 RTFREE(ipforward_rt.ro_rt); 1014 ipforward_rt.ro_rt = 0; 1015 } 1016 sin->sin_family = AF_INET; 1017 sin->sin_len = sizeof(*sin); 1018 sin->sin_addr = ip->ip_dst; 1019 1020 rtalloc(&ipforward_rt); 1021 if (ipforward_rt.ro_rt == 0) { 1022 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest); 1023 return; 1024 } 1025 rt = ipforward_rt.ro_rt; 1026 } 1027 1028 /* 1029 * Save at most 64 bytes of the packet in case 1030 * we need to generate an ICMP message to the src. 1031 */ 1032 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1033 1034#ifdef GATEWAY 1035 ip_ifmatrix[rt->rt_ifp->if_index + 1036 if_index * m->m_pkthdr.rcvif->if_index]++; 1037#endif 1038 /* 1039 * If forwarding packet using same interface that it came in on, 1040 * perhaps should send a redirect to sender to shortcut a hop. 1041 * Only send redirect if source is sending directly to us, 1042 * and if packet was not source routed (or has any options). 1043 * Also, don't send redirect if forwarding using a default route 1044 * or a route modified by a redirect. 1045 */ 1046#define satosin(sa) ((struct sockaddr_in *)(sa)) 1047 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1048 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1049 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1050 ipsendredirects && !srcrt) { 1051 struct in_ifaddr *ia; 1052 u_long src = ntohl(ip->ip_src.s_addr); 1053 u_long dst = ntohl(ip->ip_dst.s_addr); 1054 1055 if ((ia = ifptoia(m->m_pkthdr.rcvif)) && 1056 (src & ia->ia_subnetmask) == ia->ia_subnet) { 1057 if (rt->rt_flags & RTF_GATEWAY) 1058 dest = satosin(rt->rt_gateway)->sin_addr; 1059 else 1060 dest = ip->ip_dst; 1061 /* 1062 * If the destination is reached by a route to host, 1063 * is on a subnet of a local net, or is directly 1064 * on the attached net (!), use host redirect. 1065 * (We may be the correct first hop for other subnets.) 1066 */ 1067#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1068 type = ICMP_REDIRECT; 1069 if ((rt->rt_flags & RTF_HOST) || 1070 (rt->rt_flags & RTF_GATEWAY) == 0) 1071 code = ICMP_REDIRECT_HOST; 1072 else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask && 1073 (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net) 1074 code = ICMP_REDIRECT_HOST; 1075 else 1076 code = ICMP_REDIRECT_NET; 1077#ifdef DIAGNOSTIC 1078 if (ipprintfs) 1079 printf("redirect (%d) to %x\n", code, dest.s_addr); 1080#endif 1081 } 1082 } 1083 1084 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING); 1085 if (error) 1086 ipstat.ips_cantforward++; 1087 else { 1088 ipstat.ips_forward++; 1089 if (type) 1090 ipstat.ips_redirectsent++; 1091 else { 1092 if (mcopy) 1093 m_freem(mcopy); 1094 return; 1095 } 1096 } 1097 if (mcopy == NULL) 1098 return; 1099 switch (error) { 1100 1101 case 0: /* forwarded, but need redirect */ 1102 /* type, code set above */ 1103 break; 1104 1105 case ENETUNREACH: /* shouldn't happen, checked above */ 1106 case EHOSTUNREACH: 1107 case ENETDOWN: 1108 case EHOSTDOWN: 1109 default: 1110 type = ICMP_UNREACH; 1111 code = ICMP_UNREACH_HOST; 1112 break; 1113 1114 case EMSGSIZE: 1115 type = ICMP_UNREACH; 1116 code = ICMP_UNREACH_NEEDFRAG; 1117 ipstat.ips_cantfrag++; 1118 break; 1119 1120 case ENOBUFS: 1121 type = ICMP_SOURCEQUENCH; 1122 code = 0; 1123 break; 1124 } 1125 icmp_error(mcopy, type, code, dest); 1126} 1127