ip_input.c revision 1.3
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 1.3 1993/05/20 03:50:25 cgd Exp $ 35 */ 36 37#include "param.h" 38#include "systm.h" 39#include "malloc.h" 40#include "mbuf.h" 41#include "domain.h" 42#include "protosw.h" 43#include "socket.h" 44#include "errno.h" 45#include "time.h" 46#include "kernel.h" 47 48#include "../net/if.h" 49#include "../net/route.h" 50 51#include "in.h" 52#include "in_systm.h" 53#include "ip.h" 54#include "in_pcb.h" 55#include "in_var.h" 56#include "ip_var.h" 57#include "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 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 271 goto ours; 272 if (ip->ip_dst.s_addr == INADDR_ANY) 273 goto ours; 274 275 /* 276 * Not for us; forward if possible and desirable. 277 */ 278 if (ipforwarding == 0) { 279 ipstat.ips_cantforward++; 280 m_freem(m); 281 } else 282 ip_forward(m, 0); 283 goto next; 284 285ours: 286 /* 287 * If offset or IP_MF are set, must reassemble. 288 * Otherwise, nothing need be done. 289 * (We could look in the reassembly queue to see 290 * if the packet was previously fragmented, 291 * but it's not worth the time; just let them time out.) 292 */ 293 if (ip->ip_off &~ IP_DF) { 294 if (m->m_flags & M_EXT) { /* XXX */ 295 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 296 ipstat.ips_toosmall++; 297 goto next; 298 } 299 ip = mtod(m, struct ip *); 300 } 301 /* 302 * Look for queue of fragments 303 * of this datagram. 304 */ 305 for (fp = ipq.next; fp != &ipq; fp = fp->next) 306 if (ip->ip_id == fp->ipq_id && 307 ip->ip_src.s_addr == fp->ipq_src.s_addr && 308 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 309 ip->ip_p == fp->ipq_p) 310 goto found; 311 fp = 0; 312found: 313 314 /* 315 * Adjust ip_len to not reflect header, 316 * set ip_mff if more fragments are expected, 317 * convert offset of this to bytes. 318 */ 319 ip->ip_len -= hlen; 320 ((struct ipasfrag *)ip)->ipf_mff = 0; 321 if (ip->ip_off & IP_MF) 322 ((struct ipasfrag *)ip)->ipf_mff = 1; 323 ip->ip_off <<= 3; 324 325 /* 326 * If datagram marked as having more fragments 327 * or if this is not the first fragment, 328 * attempt reassembly; if it succeeds, proceed. 329 */ 330 if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) { 331 ipstat.ips_fragments++; 332 ip = ip_reass((struct ipasfrag *)ip, fp); 333 if (ip == 0) 334 goto next; 335 else 336 ipstat.ips_reassembled++; 337 m = dtom(ip); 338 } else 339 if (fp) 340 ip_freef(fp); 341 } else 342 ip->ip_len -= hlen; 343 344 /* 345 * Switch out to protocol's input routine. 346 */ 347 ipstat.ips_delivered++; 348 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 349 goto next; 350bad: 351 m_freem(m); 352 goto next; 353} 354 355/* 356 * Take incoming datagram fragment and try to 357 * reassemble it into whole datagram. If a chain for 358 * reassembly of this datagram already exists, then it 359 * is given as fp; otherwise have to make a chain. 360 */ 361struct ip * 362ip_reass(ip, fp) 363 register struct ipasfrag *ip; 364 register struct ipq *fp; 365{ 366 register struct mbuf *m = dtom(ip); 367 register struct ipasfrag *q; 368 struct mbuf *t; 369 int hlen = ip->ip_hl << 2; 370 int i, next; 371 372 /* 373 * Presence of header sizes in mbufs 374 * would confuse code below. 375 */ 376 m->m_data += hlen; 377 m->m_len -= hlen; 378 379 /* 380 * If first fragment to arrive, create a reassembly queue. 381 */ 382 if (fp == 0) { 383 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 384 goto dropfrag; 385 fp = mtod(t, struct ipq *); 386 insque(fp, &ipq); 387 fp->ipq_ttl = IPFRAGTTL; 388 fp->ipq_p = ip->ip_p; 389 fp->ipq_id = ip->ip_id; 390 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 391 fp->ipq_src = ((struct ip *)ip)->ip_src; 392 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 393 q = (struct ipasfrag *)fp; 394 goto insert; 395 } 396 397 /* 398 * Find a segment which begins after this one does. 399 */ 400 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 401 if (q->ip_off > ip->ip_off) 402 break; 403 404 /* 405 * If there is a preceding segment, it may provide some of 406 * our data already. If so, drop the data from the incoming 407 * segment. If it provides all of our data, drop us. 408 */ 409 if (q->ipf_prev != (struct ipasfrag *)fp) { 410 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 411 if (i > 0) { 412 if (i >= ip->ip_len) 413 goto dropfrag; 414 m_adj(dtom(ip), i); 415 ip->ip_off += i; 416 ip->ip_len -= i; 417 } 418 } 419 420 /* 421 * While we overlap succeeding segments trim them or, 422 * if they are completely covered, dequeue them. 423 */ 424 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 425 i = (ip->ip_off + ip->ip_len) - q->ip_off; 426 if (i < q->ip_len) { 427 q->ip_len -= i; 428 q->ip_off += i; 429 m_adj(dtom(q), i); 430 break; 431 } 432 q = q->ipf_next; 433 m_freem(dtom(q->ipf_prev)); 434 ip_deq(q->ipf_prev); 435 } 436 437insert: 438 /* 439 * Stick new segment in its place; 440 * check for complete reassembly. 441 */ 442 ip_enq(ip, q->ipf_prev); 443 next = 0; 444 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 445 if (q->ip_off != next) 446 return (0); 447 next += q->ip_len; 448 } 449 if (q->ipf_prev->ipf_mff) 450 return (0); 451 452 /* 453 * Reassembly is complete; concatenate fragments. 454 */ 455 q = fp->ipq_next; 456 m = dtom(q); 457 t = m->m_next; 458 m->m_next = 0; 459 m_cat(m, t); 460 q = q->ipf_next; 461 while (q != (struct ipasfrag *)fp) { 462 t = dtom(q); 463 q = q->ipf_next; 464 m_cat(m, t); 465 } 466 467 /* 468 * Create header for new ip packet by 469 * modifying header of first packet; 470 * dequeue and discard fragment reassembly header. 471 * Make header visible. 472 */ 473 ip = fp->ipq_next; 474 ip->ip_len = next; 475 ((struct ip *)ip)->ip_src = fp->ipq_src; 476 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 477 remque(fp); 478 (void) m_free(dtom(fp)); 479 m = dtom(ip); 480 m->m_len += (ip->ip_hl << 2); 481 m->m_data -= (ip->ip_hl << 2); 482 /* some debugging cruft by sklower, below, will go away soon */ 483 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 484 register int plen = 0; 485 for (t = m; m; m = m->m_next) 486 plen += m->m_len; 487 t->m_pkthdr.len = plen; 488 } 489 return ((struct ip *)ip); 490 491dropfrag: 492 ipstat.ips_fragdropped++; 493 m_freem(m); 494 return (0); 495} 496 497/* 498 * Free a fragment reassembly header and all 499 * associated datagrams. 500 */ 501ip_freef(fp) 502 struct ipq *fp; 503{ 504 register struct ipasfrag *q, *p; 505 506 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 507 p = q->ipf_next; 508 ip_deq(q); 509 m_freem(dtom(q)); 510 } 511 remque(fp); 512 (void) m_free(dtom(fp)); 513} 514 515/* 516 * Put an ip fragment on a reassembly chain. 517 * Like insque, but pointers in middle of structure. 518 */ 519ip_enq(p, prev) 520 register struct ipasfrag *p, *prev; 521{ 522 523 p->ipf_prev = prev; 524 p->ipf_next = prev->ipf_next; 525 prev->ipf_next->ipf_prev = p; 526 prev->ipf_next = p; 527} 528 529/* 530 * To ip_enq as remque is to insque. 531 */ 532ip_deq(p) 533 register struct ipasfrag *p; 534{ 535 536 p->ipf_prev->ipf_next = p->ipf_next; 537 p->ipf_next->ipf_prev = p->ipf_prev; 538} 539 540/* 541 * IP timer processing; 542 * if a timer expires on a reassembly 543 * queue, discard it. 544 */ 545ip_slowtimo() 546{ 547 register struct ipq *fp; 548 int s = splnet(); 549 550 fp = ipq.next; 551 if (fp == 0) { 552 splx(s); 553 return; 554 } 555 while (fp != &ipq) { 556 --fp->ipq_ttl; 557 fp = fp->next; 558 if (fp->prev->ipq_ttl == 0) { 559 ipstat.ips_fragtimeout++; 560 ip_freef(fp->prev); 561 } 562 } 563 splx(s); 564} 565 566/* 567 * Drain off all datagram fragments. 568 */ 569ip_drain() 570{ 571 572 while (ipq.next != &ipq) { 573 ipstat.ips_fragdropped++; 574 ip_freef(ipq.next); 575 } 576} 577 578extern struct in_ifaddr *ifptoia(); 579struct in_ifaddr *ip_rtaddr(); 580 581/* 582 * Do option processing on a datagram, 583 * possibly discarding it if bad options are encountered, 584 * or forwarding it if source-routed. 585 * Returns 1 if packet has been forwarded/freed, 586 * 0 if the packet should be processed further. 587 */ 588ip_dooptions(m) 589 struct mbuf *m; 590{ 591 register struct ip *ip = mtod(m, struct ip *); 592 register u_char *cp; 593 register struct ip_timestamp *ipt; 594 register struct in_ifaddr *ia; 595 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 596 struct in_addr *sin; 597 n_time ntime; 598 599 cp = (u_char *)(ip + 1); 600 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 601 for (; cnt > 0; cnt -= optlen, cp += optlen) { 602 opt = cp[IPOPT_OPTVAL]; 603 if (opt == IPOPT_EOL) 604 break; 605 if (opt == IPOPT_NOP) 606 optlen = 1; 607 else { 608 optlen = cp[IPOPT_OLEN]; 609 if (optlen <= 0 || optlen > cnt) { 610 code = &cp[IPOPT_OLEN] - (u_char *)ip; 611 goto bad; 612 } 613 } 614 switch (opt) { 615 616 default: 617 break; 618 619 /* 620 * Source routing with record. 621 * Find interface with current destination address. 622 * If none on this machine then drop if strictly routed, 623 * or do nothing if loosely routed. 624 * Record interface address and bring up next address 625 * component. If strictly routed make sure next 626 * address is on directly accessible net. 627 */ 628 case IPOPT_LSRR: 629 case IPOPT_SSRR: 630 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 631 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 632 goto bad; 633 } 634 ipaddr.sin_addr = ip->ip_dst; 635 ia = (struct in_ifaddr *) 636 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 637 if (ia == 0) { 638 if (opt == IPOPT_SSRR) { 639 type = ICMP_UNREACH; 640 code = ICMP_UNREACH_SRCFAIL; 641 goto bad; 642 } 643 /* 644 * Loose routing, and not at next destination 645 * yet; nothing to do except forward. 646 */ 647 break; 648 } 649 off--; /* 0 origin */ 650 if (off > optlen - sizeof(struct in_addr)) { 651 /* 652 * End of source route. Should be for us. 653 */ 654 save_rte(cp, ip->ip_src); 655 break; 656 } 657 /* 658 * locate outgoing interface 659 */ 660 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 661 sizeof(ipaddr.sin_addr)); 662 if (opt == IPOPT_SSRR) { 663#define INA struct in_ifaddr * 664#define SA struct sockaddr * 665 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 666 ia = in_iaonnetof(in_netof(ipaddr.sin_addr)); 667 } else 668 ia = ip_rtaddr(ipaddr.sin_addr); 669 if (ia == 0) { 670 type = ICMP_UNREACH; 671 code = ICMP_UNREACH_SRCFAIL; 672 goto bad; 673 } 674 ip->ip_dst = ipaddr.sin_addr; 675 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 676 (caddr_t)(cp + off), sizeof(struct in_addr)); 677 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 678 forward = 1; 679 break; 680 681 case IPOPT_RR: 682 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 683 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 684 goto bad; 685 } 686 /* 687 * If no space remains, ignore. 688 */ 689 off--; /* 0 origin */ 690 if (off > optlen - sizeof(struct in_addr)) 691 break; 692 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 693 sizeof(ipaddr.sin_addr)); 694 /* 695 * locate outgoing interface; if we're the destination, 696 * use the incoming interface (should be same). 697 */ 698 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 699 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 700 type = ICMP_UNREACH; 701 code = ICMP_UNREACH_HOST; 702 goto bad; 703 } 704 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), 705 (caddr_t)(cp + off), sizeof(struct in_addr)); 706 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 707 break; 708 709 case IPOPT_TS: 710 code = cp - (u_char *)ip; 711 ipt = (struct ip_timestamp *)cp; 712 if (ipt->ipt_len < 5) 713 goto bad; 714 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 715 if (++ipt->ipt_oflw == 0) 716 goto bad; 717 break; 718 } 719 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 720 switch (ipt->ipt_flg) { 721 722 case IPOPT_TS_TSONLY: 723 break; 724 725 case IPOPT_TS_TSANDADDR: 726 if (ipt->ipt_ptr + sizeof(n_time) + 727 sizeof(struct in_addr) > ipt->ipt_len) 728 goto bad; 729 ia = ifptoia(m->m_pkthdr.rcvif); 730 bcopy((caddr_t)&IA_SIN(ia)->sin_addr, 731 (caddr_t)sin, sizeof(struct in_addr)); 732 ipt->ipt_ptr += sizeof(struct in_addr); 733 break; 734 735 case IPOPT_TS_PRESPEC: 736 if (ipt->ipt_ptr + sizeof(n_time) + 737 sizeof(struct in_addr) > ipt->ipt_len) 738 goto bad; 739 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 740 sizeof(struct in_addr)); 741 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 742 continue; 743 ipt->ipt_ptr += sizeof(struct in_addr); 744 break; 745 746 default: 747 goto bad; 748 } 749 ntime = iptime(); 750 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 751 sizeof(n_time)); 752 ipt->ipt_ptr += sizeof(n_time); 753 } 754 } 755 if (forward) { 756 ip_forward(m, 1); 757 return (1); 758 } else 759 return (0); 760bad: 761 icmp_error(m, type, code); 762 return (1); 763} 764 765/* 766 * Given address of next destination (final or next hop), 767 * return internet address info of interface to be used to get there. 768 */ 769struct in_ifaddr * 770ip_rtaddr(dst) 771 struct in_addr dst; 772{ 773 register struct sockaddr_in *sin; 774 775 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 776 777 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 778 if (ipforward_rt.ro_rt) { 779 RTFREE(ipforward_rt.ro_rt); 780 ipforward_rt.ro_rt = 0; 781 } 782 sin->sin_family = AF_INET; 783 sin->sin_len = sizeof(*sin); 784 sin->sin_addr = dst; 785 786 rtalloc(&ipforward_rt); 787 } 788 if (ipforward_rt.ro_rt == 0) 789 return ((struct in_ifaddr *)0); 790 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 791} 792 793/* 794 * Save incoming source route for use in replies, 795 * to be picked up later by ip_srcroute if the receiver is interested. 796 */ 797save_rte(option, dst) 798 u_char *option; 799 struct in_addr dst; 800{ 801 unsigned olen; 802 803 olen = option[IPOPT_OLEN]; 804#ifdef DIAGNOSTIC 805 if (ipprintfs) 806 printf("save_rte: olen %d\n", olen); 807#endif 808 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 809 return; 810 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 811 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 812 ip_srcrt.dst = dst; 813} 814 815/* 816 * Retrieve incoming source route for use in replies, 817 * in the same form used by setsockopt. 818 * The first hop is placed before the options, will be removed later. 819 */ 820struct mbuf * 821ip_srcroute() 822{ 823 register struct in_addr *p, *q; 824 register struct mbuf *m; 825 826 if (ip_nhops == 0) 827 return ((struct mbuf *)0); 828 m = m_get(M_DONTWAIT, MT_SOOPTS); 829 if (m == 0) 830 return ((struct mbuf *)0); 831 832#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 833 834 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 835 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 836 OPTSIZ; 837#ifdef DIAGNOSTIC 838 if (ipprintfs) 839 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 840#endif 841 842 /* 843 * First save first hop for return route 844 */ 845 p = &ip_srcrt.route[ip_nhops - 1]; 846 *(mtod(m, struct in_addr *)) = *p--; 847#ifdef DIAGNOSTIC 848 if (ipprintfs) 849 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 850#endif 851 852 /* 853 * Copy option fields and padding (nop) to mbuf. 854 */ 855 ip_srcrt.nop = IPOPT_NOP; 856 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 857 bcopy((caddr_t)&ip_srcrt.nop, 858 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 859 q = (struct in_addr *)(mtod(m, caddr_t) + 860 sizeof(struct in_addr) + OPTSIZ); 861#undef OPTSIZ 862 /* 863 * Record return path as an IP source route, 864 * reversing the path (pointers are now aligned). 865 */ 866 while (p >= ip_srcrt.route) { 867#ifdef DIAGNOSTIC 868 if (ipprintfs) 869 printf(" %lx", ntohl(q->s_addr)); 870#endif 871 *q++ = *p--; 872 } 873 /* 874 * Last hop goes to final destination. 875 */ 876 *q = ip_srcrt.dst; 877#ifdef DIAGNOSTIC 878 if (ipprintfs) 879 printf(" %lx\n", ntohl(q->s_addr)); 880#endif 881 return (m); 882} 883 884/* 885 * Strip out IP options, at higher 886 * level protocol in the kernel. 887 * Second argument is buffer to which options 888 * will be moved, and return value is their length. 889 * XXX should be deleted; last arg currently ignored. 890 */ 891ip_stripoptions(m, mopt) 892 register struct mbuf *m; 893 struct mbuf *mopt; 894{ 895 register int i; 896 struct ip *ip = mtod(m, struct ip *); 897 register caddr_t opts; 898 int olen; 899 900 olen = (ip->ip_hl<<2) - sizeof (struct ip); 901 opts = (caddr_t)(ip + 1); 902 i = m->m_len - (sizeof (struct ip) + olen); 903 bcopy(opts + olen, opts, (unsigned)i); 904 m->m_len -= olen; 905 if (m->m_flags & M_PKTHDR) 906 m->m_pkthdr.len -= olen; 907 ip->ip_hl = sizeof(struct ip) >> 2; 908} 909 910u_char inetctlerrmap[PRC_NCMDS] = { 911 0, 0, 0, 0, 912 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 913 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 914 EMSGSIZE, EHOSTUNREACH, 0, 0, 915 0, 0, 0, 0, 916 ENOPROTOOPT 917}; 918 919/* 920 * Forward a packet. If some error occurs return the sender 921 * an icmp packet. Note we can't always generate a meaningful 922 * icmp message because icmp doesn't have a large enough repertoire 923 * of codes and types. 924 * 925 * If not forwarding, just drop the packet. This could be confusing 926 * if ipforwarding was zero but some routing protocol was advancing 927 * us as a gateway to somewhere. However, we must let the routing 928 * protocol deal with that. 929 * 930 * The srcrt parameter indicates whether the packet is being forwarded 931 * via a source route. 932 */ 933ip_forward(m, srcrt) 934 struct mbuf *m; 935 int srcrt; 936{ 937 register struct ip *ip = mtod(m, struct ip *); 938 register struct sockaddr_in *sin; 939 register struct rtentry *rt; 940 int error, type = 0, code; 941 struct mbuf *mcopy; 942 struct in_addr dest; 943 944 dest.s_addr = 0; 945#ifdef DIAGNOSTIC 946 if (ipprintfs) 947 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 948 ip->ip_dst, ip->ip_ttl); 949#endif 950 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 951 ipstat.ips_cantforward++; 952 m_freem(m); 953 return; 954 } 955 HTONS(ip->ip_id); 956 if (ip->ip_ttl <= IPTTLDEC) { 957 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest); 958 return; 959 } 960 ip->ip_ttl -= IPTTLDEC; 961 962 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 963 if ((rt = ipforward_rt.ro_rt) == 0 || 964 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 965 if (ipforward_rt.ro_rt) { 966 RTFREE(ipforward_rt.ro_rt); 967 ipforward_rt.ro_rt = 0; 968 } 969 sin->sin_family = AF_INET; 970 sin->sin_len = sizeof(*sin); 971 sin->sin_addr = ip->ip_dst; 972 973 rtalloc(&ipforward_rt); 974 if (ipforward_rt.ro_rt == 0) { 975 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest); 976 return; 977 } 978 rt = ipforward_rt.ro_rt; 979 } 980 981 /* 982 * Save at most 64 bytes of the packet in case 983 * we need to generate an ICMP message to the src. 984 */ 985 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 986 987#ifdef GATEWAY 988 ip_ifmatrix[rt->rt_ifp->if_index + 989 if_index * m->m_pkthdr.rcvif->if_index]++; 990#endif 991 /* 992 * If forwarding packet using same interface that it came in on, 993 * perhaps should send a redirect to sender to shortcut a hop. 994 * Only send redirect if source is sending directly to us, 995 * and if packet was not source routed (or has any options). 996 * Also, don't send redirect if forwarding using a default route 997 * or a route modified by a redirect. 998 */ 999#define satosin(sa) ((struct sockaddr_in *)(sa)) 1000 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1001 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1002 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1003 ipsendredirects && !srcrt) { 1004 struct in_ifaddr *ia; 1005 u_long src = ntohl(ip->ip_src.s_addr); 1006 u_long dst = ntohl(ip->ip_dst.s_addr); 1007 1008 if ((ia = ifptoia(m->m_pkthdr.rcvif)) && 1009 (src & ia->ia_subnetmask) == ia->ia_subnet) { 1010 if (rt->rt_flags & RTF_GATEWAY) 1011 dest = satosin(rt->rt_gateway)->sin_addr; 1012 else 1013 dest = ip->ip_dst; 1014 /* 1015 * If the destination is reached by a route to host, 1016 * is on a subnet of a local net, or is directly 1017 * on the attached net (!), use host redirect. 1018 * (We may be the correct first hop for other subnets.) 1019 */ 1020#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1021 type = ICMP_REDIRECT; 1022 if ((rt->rt_flags & RTF_HOST) || 1023 (rt->rt_flags & RTF_GATEWAY) == 0) 1024 code = ICMP_REDIRECT_HOST; 1025 else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask && 1026 (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net) 1027 code = ICMP_REDIRECT_HOST; 1028 else 1029 code = ICMP_REDIRECT_NET; 1030#ifdef DIAGNOSTIC 1031 if (ipprintfs) 1032 printf("redirect (%d) to %x\n", code, dest.s_addr); 1033#endif 1034 } 1035 } 1036 1037 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING); 1038 if (error) 1039 ipstat.ips_cantforward++; 1040 else { 1041 ipstat.ips_forward++; 1042 if (type) 1043 ipstat.ips_redirectsent++; 1044 else { 1045 if (mcopy) 1046 m_freem(mcopy); 1047 return; 1048 } 1049 } 1050 if (mcopy == NULL) 1051 return; 1052 switch (error) { 1053 1054 case 0: /* forwarded, but need redirect */ 1055 /* type, code set above */ 1056 break; 1057 1058 case ENETUNREACH: /* shouldn't happen, checked above */ 1059 case EHOSTUNREACH: 1060 case ENETDOWN: 1061 case EHOSTDOWN: 1062 default: 1063 type = ICMP_UNREACH; 1064 code = ICMP_UNREACH_HOST; 1065 break; 1066 1067 case EMSGSIZE: 1068 type = ICMP_UNREACH; 1069 code = ICMP_UNREACH_NEEDFRAG; 1070 ipstat.ips_cantfrag++; 1071 break; 1072 1073 case ENOBUFS: 1074 type = ICMP_SOURCEQUENCH; 1075 code = 0; 1076 break; 1077 } 1078 icmp_error(mcopy, type, code, dest); 1079} 1080