ip_input.c revision 1.2
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 * @(#)ip_input.c 7.19 (Berkeley) 5/25/91 34 */ 35 36#include "param.h" 37#include "systm.h" 38#include "malloc.h" 39#include "mbuf.h" 40#include "domain.h" 41#include "protosw.h" 42#include "socket.h" 43#include "errno.h" 44#include "time.h" 45#include "kernel.h" 46 47#include "../net/if.h" 48#include "../net/route.h" 49 50#include "in.h" 51#include "in_systm.h" 52#include "ip.h" 53#include "in_pcb.h" 54#include "in_var.h" 55#include "ip_var.h" 56#include "ip_icmp.h" 57 58#ifndef IPFORWARDING 59#ifdef GATEWAY 60#define IPFORWARDING 1 /* forward IP packets not for us */ 61#else /* GATEWAY */ 62#define IPFORWARDING 0 /* don't forward IP packets not for us */ 63#endif /* GATEWAY */ 64#endif /* IPFORWARDING */ 65#ifndef IPSENDREDIRECTS 66#define IPSENDREDIRECTS 1 67#endif 68int ipforwarding = IPFORWARDING; 69int ipsendredirects = IPSENDREDIRECTS; 70#ifdef DIAGNOSTIC 71int ipprintfs = 0; 72#endif 73 74extern struct domain inetdomain; 75extern struct protosw inetsw[]; 76u_char ip_protox[IPPROTO_MAX]; 77int ipqmaxlen = IFQ_MAXLEN; 78struct in_ifaddr *in_ifaddr; /* first inet address */ 79 80/* 81 * We need to save the IP options in case a protocol wants to respond 82 * to an incoming packet over the same route if the packet got here 83 * using IP source routing. This allows connection establishment and 84 * maintenance when the remote end is on a network that is not known 85 * to us. 86 */ 87int ip_nhops = 0; 88static struct ip_srcrt { 89 struct in_addr dst; /* final destination */ 90 char nop; /* one NOP to align */ 91 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 92 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 93} ip_srcrt; 94 95#ifdef GATEWAY 96extern int if_index; 97u_long *ip_ifmatrix; 98#endif 99 100/* 101 * IP initialization: fill in IP protocol switch table. 102 * All protocols not implemented in kernel go to raw IP protocol handler. 103 */ 104ip_init() 105{ 106 register struct protosw *pr; 107 register int i; 108 109 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 110 if (pr == 0) 111 panic("ip_init"); 112 for (i = 0; i < IPPROTO_MAX; i++) 113 ip_protox[i] = pr - inetsw; 114 for (pr = inetdomain.dom_protosw; 115 pr < inetdomain.dom_protoswNPROTOSW; pr++) 116 if (pr->pr_domain->dom_family == PF_INET && 117 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 118 ip_protox[pr->pr_protocol] = pr - inetsw; 119 ipq.next = ipq.prev = &ipq; 120 ip_id = time.tv_sec & 0xffff; 121 ipintrq.ifq_maxlen = ipqmaxlen; 122#ifdef GATEWAY 123 i = (if_index + 1) * (if_index + 1) * sizeof (u_long); 124 if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0) 125 panic("no memory for ip_ifmatrix"); 126#endif 127} 128 129struct ip *ip_reass(); 130struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 131struct route ipforward_rt; 132 133/* 134 * Ip input routine. Checksum and byte swap header. If fragmented 135 * try to reassemble. Process options. Pass to next level. 136 */ 137ipintr() 138{ 139 register struct ip *ip; 140 register struct mbuf *m; 141 register struct ipq *fp; 142 register struct in_ifaddr *ia; 143 int hlen, s; 144#ifdef PARANOID 145 static int busy = 0; 146 147 if (busy) 148 panic("ipintr: called recursively\n"); 149 ++busy; 150#endif 151next: 152 /* 153 * Get next datagram off input queue and get IP header 154 * in first mbuf. 155 */ 156 s = splimp(); 157 IF_DEQUEUE(&ipintrq, m); 158 splx(s); 159 if (m == 0) { 160#ifdef PARANOID 161 --busy; 162#endif 163 return; 164 } 165#ifdef DIAGNOSTIC 166 if ((m->m_flags & M_PKTHDR) == 0) 167 panic("ipintr no HDR"); 168#endif 169 /* 170 * If no IP addresses have been set yet but the interfaces 171 * are receiving, can't do anything with incoming packets yet. 172 */ 173 if (in_ifaddr == NULL) 174 goto bad; 175 ipstat.ips_total++; 176 if (m->m_len < sizeof (struct ip) && 177 (m = m_pullup(m, sizeof (struct ip))) == 0) { 178 ipstat.ips_toosmall++; 179 goto next; 180 } 181 ip = mtod(m, struct ip *); 182 hlen = ip->ip_hl << 2; 183 if (hlen < sizeof(struct ip)) { /* minimum header length */ 184 ipstat.ips_badhlen++; 185 goto bad; 186 } 187 if (hlen > m->m_len) { 188 if ((m = m_pullup(m, hlen)) == 0) { 189 ipstat.ips_badhlen++; 190 goto next; 191 } 192 ip = mtod(m, struct ip *); 193 } 194 if (ip->ip_sum = in_cksum(m, hlen)) { 195 ipstat.ips_badsum++; 196 goto bad; 197 } 198 199 /* 200 * Convert fields to host representation. 201 */ 202 NTOHS(ip->ip_len); 203 if (ip->ip_len < hlen) { 204 ipstat.ips_badlen++; 205 goto bad; 206 } 207 NTOHS(ip->ip_id); 208 NTOHS(ip->ip_off); 209 210 /* 211 * Check that the amount of data in the buffers 212 * is as at least much as the IP header would have us expect. 213 * Trim mbufs if longer than we expect. 214 * Drop packet if shorter than we expect. 215 */ 216 if (m->m_pkthdr.len < ip->ip_len) { 217 ipstat.ips_tooshort++; 218 goto bad; 219 } 220 if (m->m_pkthdr.len > ip->ip_len) { 221 if (m->m_len == m->m_pkthdr.len) { 222 m->m_len = ip->ip_len; 223 m->m_pkthdr.len = ip->ip_len; 224 } else 225 m_adj(m, ip->ip_len - m->m_pkthdr.len); 226 } 227 228 /* 229 * Process options and, if not destined for us, 230 * ship it on. ip_dooptions returns 1 when an 231 * error was detected (causing an icmp message 232 * to be sent and the original packet to be freed). 233 */ 234 ip_nhops = 0; /* for source routed packets */ 235 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 236 goto next; 237 238 /* 239 * Check our list of addresses, to see if the packet is for us. 240 */ 241 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 242#define satosin(sa) ((struct sockaddr_in *)(sa)) 243 244 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 245 goto ours; 246 if ( 247#ifdef DIRECTED_BROADCAST 248 ia->ia_ifp == m->m_pkthdr.rcvif && 249#endif 250 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 251 u_long t; 252 253 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 254 ip->ip_dst.s_addr) 255 goto ours; 256 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 257 goto ours; 258 /* 259 * Look for all-0's host part (old broadcast addr), 260 * either for subnet or net. 261 */ 262 t = ntohl(ip->ip_dst.s_addr); 263 if (t == ia->ia_subnet) 264 goto ours; 265 if (t == ia->ia_net) 266 goto ours; 267 } 268 } 269 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 270 goto ours; 271 if (ip->ip_dst.s_addr == INADDR_ANY) 272 goto ours; 273 274 /* 275 * Not for us; forward if possible and desirable. 276 */ 277 if (ipforwarding == 0) { 278 ipstat.ips_cantforward++; 279 m_freem(m); 280 } else 281 ip_forward(m, 0); 282 goto next; 283 284ours: 285 /* 286 * If offset or IP_MF are set, must reassemble. 287 * Otherwise, nothing need be done. 288 * (We could look in the reassembly queue to see 289 * if the packet was previously fragmented, 290 * but it's not worth the time; just let them time out.) 291 */ 292 if (ip->ip_off &~ IP_DF) { 293 if (m->m_flags & M_EXT) { /* XXX */ 294 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 295 ipstat.ips_toosmall++; 296 goto next; 297 } 298 ip = mtod(m, struct ip *); 299 } 300 /* 301 * Look for queue of fragments 302 * of this datagram. 303 */ 304 for (fp = ipq.next; fp != &ipq; fp = fp->next) 305 if (ip->ip_id == fp->ipq_id && 306 ip->ip_src.s_addr == fp->ipq_src.s_addr && 307 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 308 ip->ip_p == fp->ipq_p) 309 goto found; 310 fp = 0; 311found: 312 313 /* 314 * Adjust ip_len to not reflect header, 315 * set ip_mff if more fragments are expected, 316 * convert offset of this to bytes. 317 */ 318 ip->ip_len -= hlen; 319 ((struct ipasfrag *)ip)->ipf_mff = 0; 320 if (ip->ip_off & IP_MF) 321 ((struct ipasfrag *)ip)->ipf_mff = 1; 322 ip->ip_off <<= 3; 323 324 /* 325 * If datagram marked as having more fragments 326 * or if this is not the first fragment, 327 * attempt reassembly; if it succeeds, proceed. 328 */ 329 if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) { 330 ipstat.ips_fragments++; 331 ip = ip_reass((struct ipasfrag *)ip, fp); 332 if (ip == 0) 333 goto next; 334 else 335 ipstat.ips_reassembled++; 336 m = dtom(ip); 337 } else 338 if (fp) 339 ip_freef(fp); 340 } else 341 ip->ip_len -= hlen; 342 343 /* 344 * Switch out to protocol's input routine. 345 */ 346 ipstat.ips_delivered++; 347 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 348 goto next; 349bad: 350 m_freem(m); 351 goto next; 352} 353 354/* 355 * Take incoming datagram fragment and try to 356 * reassemble it into whole datagram. If a chain for 357 * reassembly of this datagram already exists, then it 358 * is given as fp; otherwise have to make a chain. 359 */ 360struct ip * 361ip_reass(ip, fp) 362 register struct ipasfrag *ip; 363 register struct ipq *fp; 364{ 365 register struct mbuf *m = dtom(ip); 366 register struct ipasfrag *q; 367 struct mbuf *t; 368 int hlen = ip->ip_hl << 2; 369 int i, next; 370 371 /* 372 * Presence of header sizes in mbufs 373 * would confuse code below. 374 */ 375 m->m_data += hlen; 376 m->m_len -= hlen; 377 378 /* 379 * If first fragment to arrive, create a reassembly queue. 380 */ 381 if (fp == 0) { 382 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 383 goto dropfrag; 384 fp = mtod(t, struct ipq *); 385 insque(fp, &ipq); 386 fp->ipq_ttl = IPFRAGTTL; 387 fp->ipq_p = ip->ip_p; 388 fp->ipq_id = ip->ip_id; 389 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 390 fp->ipq_src = ((struct ip *)ip)->ip_src; 391 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 392 q = (struct ipasfrag *)fp; 393 goto insert; 394 } 395 396 /* 397 * Find a segment which begins after this one does. 398 */ 399 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 400 if (q->ip_off > ip->ip_off) 401 break; 402 403 /* 404 * If there is a preceding segment, it may provide some of 405 * our data already. If so, drop the data from the incoming 406 * segment. If it provides all of our data, drop us. 407 */ 408 if (q->ipf_prev != (struct ipasfrag *)fp) { 409 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 410 if (i > 0) { 411 if (i >= ip->ip_len) 412 goto dropfrag; 413 m_adj(dtom(ip), i); 414 ip->ip_off += i; 415 ip->ip_len -= i; 416 } 417 } 418 419 /* 420 * While we overlap succeeding segments trim them or, 421 * if they are completely covered, dequeue them. 422 */ 423 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 424 i = (ip->ip_off + ip->ip_len) - q->ip_off; 425 if (i < q->ip_len) { 426 q->ip_len -= i; 427 q->ip_off += i; 428 m_adj(dtom(q), i); 429 break; 430 } 431 q = q->ipf_next; 432 m_freem(dtom(q->ipf_prev)); 433 ip_deq(q->ipf_prev); 434 } 435 436insert: 437 /* 438 * Stick new segment in its place; 439 * check for complete reassembly. 440 */ 441 ip_enq(ip, q->ipf_prev); 442 next = 0; 443 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 444 if (q->ip_off != next) 445 return (0); 446 next += q->ip_len; 447 } 448 if (q->ipf_prev->ipf_mff) 449 return (0); 450 451 /* 452 * Reassembly is complete; concatenate fragments. 453 */ 454 q = fp->ipq_next; 455 m = dtom(q); 456 t = m->m_next; 457 m->m_next = 0; 458 m_cat(m, t); 459 q = q->ipf_next; 460 while (q != (struct ipasfrag *)fp) { 461 t = dtom(q); 462 q = q->ipf_next; 463 m_cat(m, t); 464 } 465 466 /* 467 * Create header for new ip packet by 468 * modifying header of first packet; 469 * dequeue and discard fragment reassembly header. 470 * Make header visible. 471 */ 472 ip = fp->ipq_next; 473 ip->ip_len = next; 474 ((struct ip *)ip)->ip_src = fp->ipq_src; 475 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 476 remque(fp); 477 (void) m_free(dtom(fp)); 478 m = dtom(ip); 479 m->m_len += (ip->ip_hl << 2); 480 m->m_data -= (ip->ip_hl << 2); 481 /* some debugging cruft by sklower, below, will go away soon */ 482 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 483 register int plen = 0; 484 for (t = m; m; m = m->m_next) 485 plen += m->m_len; 486 t->m_pkthdr.len = plen; 487 } 488 return ((struct ip *)ip); 489 490dropfrag: 491 ipstat.ips_fragdropped++; 492 m_freem(m); 493 return (0); 494} 495 496/* 497 * Free a fragment reassembly header and all 498 * associated datagrams. 499 */ 500ip_freef(fp) 501 struct ipq *fp; 502{ 503 register struct ipasfrag *q, *p; 504 505 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 506 p = q->ipf_next; 507 ip_deq(q); 508 m_freem(dtom(q)); 509 } 510 remque(fp); 511 (void) m_free(dtom(fp)); 512} 513 514/* 515 * Put an ip fragment on a reassembly chain. 516 * Like insque, but pointers in middle of structure. 517 */ 518ip_enq(p, prev) 519 register struct ipasfrag *p, *prev; 520{ 521 522 p->ipf_prev = prev; 523 p->ipf_next = prev->ipf_next; 524 prev->ipf_next->ipf_prev = p; 525 prev->ipf_next = p; 526} 527 528/* 529 * To ip_enq as remque is to insque. 530 */ 531ip_deq(p) 532 register struct ipasfrag *p; 533{ 534 535 p->ipf_prev->ipf_next = p->ipf_next; 536 p->ipf_next->ipf_prev = p->ipf_prev; 537} 538 539/* 540 * IP timer processing; 541 * if a timer expires on a reassembly 542 * queue, discard it. 543 */ 544ip_slowtimo() 545{ 546 register struct ipq *fp; 547 int s = splnet(); 548 549 fp = ipq.next; 550 if (fp == 0) { 551 splx(s); 552 return; 553 } 554 while (fp != &ipq) { 555 --fp->ipq_ttl; 556 fp = fp->next; 557 if (fp->prev->ipq_ttl == 0) { 558 ipstat.ips_fragtimeout++; 559 ip_freef(fp->prev); 560 } 561 } 562 splx(s); 563} 564 565/* 566 * Drain off all datagram fragments. 567 */ 568ip_drain() 569{ 570 571 while (ipq.next != &ipq) { 572 ipstat.ips_fragdropped++; 573 ip_freef(ipq.next); 574 } 575} 576 577extern struct in_ifaddr *ifptoia(); 578struct in_ifaddr *ip_rtaddr(); 579 580/* 581 * Do option processing on a datagram, 582 * possibly discarding it if bad options are encountered, 583 * or forwarding it if source-routed. 584 * Returns 1 if packet has been forwarded/freed, 585 * 0 if the packet should be processed further. 586 */ 587ip_dooptions(m) 588 struct mbuf *m; 589{ 590 register struct ip *ip = mtod(m, struct ip *); 591 register u_char *cp; 592 register struct ip_timestamp *ipt; 593 register struct in_ifaddr *ia; 594 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 595 struct in_addr *sin; 596 n_time ntime; 597 598 cp = (u_char *)(ip + 1); 599 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 600 for (; cnt > 0; cnt -= optlen, cp += optlen) { 601 opt = cp[IPOPT_OPTVAL]; 602 if (opt == IPOPT_EOL) 603 break; 604 if (opt == IPOPT_NOP) 605 optlen = 1; 606 else { 607 optlen = cp[IPOPT_OLEN]; 608 if (optlen <= 0 || optlen > cnt) { 609 code = &cp[IPOPT_OLEN] - (u_char *)ip; 610 goto bad; 611 } 612 } 613 switch (opt) { 614 615 default: 616 break; 617 618 /* 619 * Source routing with record. 620 * Find interface with current destination address. 621 * If none on this machine then drop if strictly routed, 622 * or do nothing if loosely routed. 623 * Record interface address and bring up next address 624 * component. If strictly routed make sure next 625 * address is on directly accessible net. 626 */ 627 case IPOPT_LSRR: 628 case IPOPT_SSRR: 629 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 630 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 631 goto bad; 632 } 633 ipaddr.sin_addr = ip->ip_dst; 634 ia = (struct in_ifaddr *) 635 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 636 if (ia == 0) { 637 if (opt == IPOPT_SSRR) { 638 type = ICMP_UNREACH; 639 code = ICMP_UNREACH_SRCFAIL; 640 goto bad; 641 } 642 /* 643 * Loose routing, and not at next destination 644 * yet; nothing to do except forward. 645 */ 646 break; 647 } 648 off--; /* 0 origin */ 649 if (off > optlen - sizeof(struct in_addr)) { 650 /* 651 * End of source route. Should be for us. 652 */ 653 save_rte(cp, ip->ip_src); 654 break; 655 } 656 /* 657 * locate outgoing interface 658 */ 659 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 660 sizeof(ipaddr.sin_addr)); 661 if (opt == IPOPT_SSRR) { 662#define INA struct in_ifaddr * 663#define SA struct sockaddr * 664 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 665 ia = in_iaonnetof(in_netof(ipaddr.sin_addr)); 666 } else 667 ia = ip_rtaddr(ipaddr.sin_addr); 668 if (ia == 0) { 669 type = ICMP_UNREACH; 670 code = ICMP_UNREACH_SRCFAIL; 671 goto bad; 672 } 673 ip->ip_dst = ipaddr.sin_addr; 674 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 675 (caddr_t)(cp + off), sizeof(struct in_addr)); 676 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 677 forward = 1; 678 break; 679 680 case IPOPT_RR: 681 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 682 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 683 goto bad; 684 } 685 /* 686 * If no space remains, ignore. 687 */ 688 off--; /* 0 origin */ 689 if (off > optlen - sizeof(struct in_addr)) 690 break; 691 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 692 sizeof(ipaddr.sin_addr)); 693 /* 694 * locate outgoing interface; if we're the destination, 695 * use the incoming interface (should be same). 696 */ 697 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 698 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 699 type = ICMP_UNREACH; 700 code = ICMP_UNREACH_HOST; 701 goto bad; 702 } 703 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 704 (caddr_t)(cp + off), sizeof(struct in_addr)); 705 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 706 break; 707 708 case IPOPT_TS: 709 code = cp - (u_char *)ip; 710 ipt = (struct ip_timestamp *)cp; 711 if (ipt->ipt_len < 5) 712 goto bad; 713 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 714 if (++ipt->ipt_oflw == 0) 715 goto bad; 716 break; 717 } 718 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 719 switch (ipt->ipt_flg) { 720 721 case IPOPT_TS_TSONLY: 722 break; 723 724 case IPOPT_TS_TSANDADDR: 725 if (ipt->ipt_ptr + sizeof(n_time) + 726 sizeof(struct in_addr) > ipt->ipt_len) 727 goto bad; 728 ia = ifptoia(m->m_pkthdr.rcvif); 729 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 730 (caddr_t)sin, sizeof(struct in_addr)); 731 ipt->ipt_ptr += sizeof(struct in_addr); 732 break; 733 734 case IPOPT_TS_PRESPEC: 735 if (ipt->ipt_ptr + sizeof(n_time) + 736 sizeof(struct in_addr) > ipt->ipt_len) 737 goto bad; 738 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 739 sizeof(struct in_addr)); 740 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 741 continue; 742 ipt->ipt_ptr += sizeof(struct in_addr); 743 break; 744 745 default: 746 goto bad; 747 } 748 ntime = iptime(); 749 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 750 sizeof(n_time)); 751 ipt->ipt_ptr += sizeof(n_time); 752 } 753 } 754 if (forward) { 755 ip_forward(m, 1); 756 return (1); 757 } else 758 return (0); 759bad: 760 icmp_error(m, type, code); 761 return (1); 762} 763 764/* 765 * Given address of next destination (final or next hop), 766 * return internet address info of interface to be used to get there. 767 */ 768struct in_ifaddr * 769ip_rtaddr(dst) 770 struct in_addr dst; 771{ 772 register struct sockaddr_in *sin; 773 774 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 775 776 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 777 if (ipforward_rt.ro_rt) { 778 RTFREE(ipforward_rt.ro_rt); 779 ipforward_rt.ro_rt = 0; 780 } 781 sin->sin_family = AF_INET; 782 sin->sin_len = sizeof(*sin); 783 sin->sin_addr = dst; 784 785 rtalloc(&ipforward_rt); 786 } 787 if (ipforward_rt.ro_rt == 0) 788 return ((struct in_ifaddr *)0); 789 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 790} 791 792/* 793 * Save incoming source route for use in replies, 794 * to be picked up later by ip_srcroute if the receiver is interested. 795 */ 796save_rte(option, dst) 797 u_char *option; 798 struct in_addr dst; 799{ 800 unsigned olen; 801 802 olen = option[IPOPT_OLEN]; 803#ifdef DIAGNOSTIC 804 if (ipprintfs) 805 printf("save_rte: olen %d\n", olen); 806#endif 807 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 808 return; 809 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 810 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 811 ip_srcrt.dst = dst; 812} 813 814/* 815 * Retrieve incoming source route for use in replies, 816 * in the same form used by setsockopt. 817 * The first hop is placed before the options, will be removed later. 818 */ 819struct mbuf * 820ip_srcroute() 821{ 822 register struct in_addr *p, *q; 823 register struct mbuf *m; 824 825 if (ip_nhops == 0) 826 return ((struct mbuf *)0); 827 m = m_get(M_DONTWAIT, MT_SOOPTS); 828 if (m == 0) 829 return ((struct mbuf *)0); 830 831#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 832 833 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 834 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 835 OPTSIZ; 836#ifdef DIAGNOSTIC 837 if (ipprintfs) 838 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 839#endif 840 841 /* 842 * First save first hop for return route 843 */ 844 p = &ip_srcrt.route[ip_nhops - 1]; 845 *(mtod(m, struct in_addr *)) = *p--; 846#ifdef DIAGNOSTIC 847 if (ipprintfs) 848 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 849#endif 850 851 /* 852 * Copy option fields and padding (nop) to mbuf. 853 */ 854 ip_srcrt.nop = IPOPT_NOP; 855 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 856 bcopy((caddr_t)&ip_srcrt.nop, 857 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 858 q = (struct in_addr *)(mtod(m, caddr_t) + 859 sizeof(struct in_addr) + OPTSIZ); 860#undef OPTSIZ 861 /* 862 * Record return path as an IP source route, 863 * reversing the path (pointers are now aligned). 864 */ 865 while (p >= ip_srcrt.route) { 866#ifdef DIAGNOSTIC 867 if (ipprintfs) 868 printf(" %lx", ntohl(q->s_addr)); 869#endif 870 *q++ = *p--; 871 } 872 /* 873 * Last hop goes to final destination. 874 */ 875 *q = ip_srcrt.dst; 876#ifdef DIAGNOSTIC 877 if (ipprintfs) 878 printf(" %lx\n", ntohl(q->s_addr)); 879#endif 880 return (m); 881} 882 883/* 884 * Strip out IP options, at higher 885 * level protocol in the kernel. 886 * Second argument is buffer to which options 887 * will be moved, and return value is their length. 888 * XXX should be deleted; last arg currently ignored. 889 */ 890ip_stripoptions(m, mopt) 891 register struct mbuf *m; 892 struct mbuf *mopt; 893{ 894 register int i; 895 struct ip *ip = mtod(m, struct ip *); 896 register caddr_t opts; 897 int olen; 898 899 olen = (ip->ip_hl<<2) - sizeof (struct ip); 900 opts = (caddr_t)(ip + 1); 901 i = m->m_len - (sizeof (struct ip) + olen); 902 bcopy(opts + olen, opts, (unsigned)i); 903 m->m_len -= olen; 904 if (m->m_flags & M_PKTHDR) 905 m->m_pkthdr.len -= olen; 906 ip->ip_hl = sizeof(struct ip) >> 2; 907} 908 909u_char inetctlerrmap[PRC_NCMDS] = { 910 0, 0, 0, 0, 911 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 912 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 913 EMSGSIZE, EHOSTUNREACH, 0, 0, 914 0, 0, 0, 0, 915 ENOPROTOOPT 916}; 917 918/* 919 * Forward a packet. If some error occurs return the sender 920 * an icmp packet. Note we can't always generate a meaningful 921 * icmp message because icmp doesn't have a large enough repertoire 922 * of codes and types. 923 * 924 * If not forwarding, just drop the packet. This could be confusing 925 * if ipforwarding was zero but some routing protocol was advancing 926 * us as a gateway to somewhere. However, we must let the routing 927 * protocol deal with that. 928 * 929 * The srcrt parameter indicates whether the packet is being forwarded 930 * via a source route. 931 */ 932ip_forward(m, srcrt) 933 struct mbuf *m; 934 int srcrt; 935{ 936 register struct ip *ip = mtod(m, struct ip *); 937 register struct sockaddr_in *sin; 938 register struct rtentry *rt; 939 int error, type = 0, code; 940 struct mbuf *mcopy; 941 struct in_addr dest; 942 943 dest.s_addr = 0; 944#ifdef DIAGNOSTIC 945 if (ipprintfs) 946 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 947 ip->ip_dst, ip->ip_ttl); 948#endif 949 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 950 ipstat.ips_cantforward++; 951 m_freem(m); 952 return; 953 } 954 HTONS(ip->ip_id); 955 if (ip->ip_ttl <= IPTTLDEC) { 956 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest); 957 return; 958 } 959 ip->ip_ttl -= IPTTLDEC; 960 961 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 962 if ((rt = ipforward_rt.ro_rt) == 0 || 963 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 964 if (ipforward_rt.ro_rt) { 965 RTFREE(ipforward_rt.ro_rt); 966 ipforward_rt.ro_rt = 0; 967 } 968 sin->sin_family = AF_INET; 969 sin->sin_len = sizeof(*sin); 970 sin->sin_addr = ip->ip_dst; 971 972 rtalloc(&ipforward_rt); 973 if (ipforward_rt.ro_rt == 0) { 974 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest); 975 return; 976 } 977 rt = ipforward_rt.ro_rt; 978 } 979 980 /* 981 * Save at most 64 bytes of the packet in case 982 * we need to generate an ICMP message to the src. 983 */ 984 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 985 986#ifdef GATEWAY 987 ip_ifmatrix[rt->rt_ifp->if_index + 988 if_index * m->m_pkthdr.rcvif->if_index]++; 989#endif 990 /* 991 * If forwarding packet using same interface that it came in on, 992 * perhaps should send a redirect to sender to shortcut a hop. 993 * Only send redirect if source is sending directly to us, 994 * and if packet was not source routed (or has any options). 995 * Also, don't send redirect if forwarding using a default route 996 * or a route modified by a redirect. 997 */ 998#define satosin(sa) ((struct sockaddr_in *)(sa)) 999 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1000 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1001 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1002 ipsendredirects && !srcrt) { 1003 struct in_ifaddr *ia; 1004 u_long src = ntohl(ip->ip_src.s_addr); 1005 u_long dst = ntohl(ip->ip_dst.s_addr); 1006 1007 if ((ia = ifptoia(m->m_pkthdr.rcvif)) && 1008 (src & ia->ia_subnetmask) == ia->ia_subnet) { 1009 if (rt->rt_flags & RTF_GATEWAY) 1010 dest = satosin(rt->rt_gateway)->sin_addr; 1011 else 1012 dest = ip->ip_dst; 1013 /* 1014 * If the destination is reached by a route to host, 1015 * is on a subnet of a local net, or is directly 1016 * on the attached net (!), use host redirect. 1017 * (We may be the correct first hop for other subnets.) 1018 */ 1019#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1020 type = ICMP_REDIRECT; 1021 if ((rt->rt_flags & RTF_HOST) || 1022 (rt->rt_flags & RTF_GATEWAY) == 0) 1023 code = ICMP_REDIRECT_HOST; 1024 else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask && 1025 (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net) 1026 code = ICMP_REDIRECT_HOST; 1027 else 1028 code = ICMP_REDIRECT_NET; 1029#ifdef DIAGNOSTIC 1030 if (ipprintfs) 1031 printf("redirect (%d) to %x\n", code, dest.s_addr); 1032#endif 1033 } 1034 } 1035 1036 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING); 1037 if (error) 1038 ipstat.ips_cantforward++; 1039 else { 1040 ipstat.ips_forward++; 1041 if (type) 1042 ipstat.ips_redirectsent++; 1043 else { 1044 if (mcopy) 1045 m_freem(mcopy); 1046 return; 1047 } 1048 } 1049 if (mcopy == NULL) 1050 return; 1051 switch (error) { 1052 1053 case 0: /* forwarded, but need redirect */ 1054 /* type, code set above */ 1055 break; 1056 1057 case ENETUNREACH: /* shouldn't happen, checked above */ 1058 case EHOSTUNREACH: 1059 case ENETDOWN: 1060 case EHOSTDOWN: 1061 default: 1062 type = ICMP_UNREACH; 1063 code = ICMP_UNREACH_HOST; 1064 break; 1065 1066 case EMSGSIZE: 1067 type = ICMP_UNREACH; 1068 code = ICMP_UNREACH_NEEDFRAG; 1069 ipstat.ips_cantfrag++; 1070 break; 1071 1072 case ENOBUFS: 1073 type = ICMP_SOURCEQUENCH; 1074 code = 0; 1075 break; 1076 } 1077 icmp_error(mcopy, type, code, dest); 1078} 1079