ip_input.c revision 1.25
1/* $NetBSD: ip_input.c,v 1.25 1995/11/21 01:07:34 cgd Exp $ */ 2 3/* 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 36 */ 37 38#include <sys/param.h> 39#include <sys/systm.h> 40#include <sys/malloc.h> 41#include <sys/mbuf.h> 42#include <sys/domain.h> 43#include <sys/protosw.h> 44#include <sys/socket.h> 45#include <sys/errno.h> 46#include <sys/time.h> 47#include <sys/kernel.h> 48 49#include <net/if.h> 50#include <net/route.h> 51 52#include <netinet/in.h> 53#include <netinet/in_systm.h> 54#include <netinet/ip.h> 55#include <netinet/in_pcb.h> 56#include <netinet/in_var.h> 57#include <netinet/ip_var.h> 58#include <netinet/ip_icmp.h> 59 60#ifndef IPFORWARDING 61#ifdef GATEWAY 62#define IPFORWARDING 1 /* forward IP packets not for us */ 63#else /* GATEWAY */ 64#define IPFORWARDING 0 /* don't forward IP packets not for us */ 65#endif /* GATEWAY */ 66#endif /* IPFORWARDING */ 67#ifndef IPSENDREDIRECTS 68#define IPSENDREDIRECTS 1 69#endif 70int ipforwarding = IPFORWARDING; 71int ipsendredirects = IPSENDREDIRECTS; 72int ip_defttl = IPDEFTTL; 73#ifdef DIAGNOSTIC 74int ipprintfs = 0; 75#endif 76 77extern struct domain inetdomain; 78extern struct protosw inetsw[]; 79u_char ip_protox[IPPROTO_MAX]; 80int ipqmaxlen = IFQ_MAXLEN; 81struct in_ifaddrhead in_ifaddr; 82struct ifqueue ipintrq; 83 84/* 85 * We need to save the IP options in case a protocol wants to respond 86 * to an incoming packet over the same route if the packet got here 87 * using IP source routing. This allows connection establishment and 88 * maintenance when the remote end is on a network that is not known 89 * to us. 90 */ 91int ip_nhops = 0; 92static struct ip_srcrt { 93 struct in_addr dst; /* final destination */ 94 char nop; /* one NOP to align */ 95 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 96 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 97} ip_srcrt; 98 99static void save_rte __P((u_char *, struct in_addr)); 100/* 101 * IP initialization: fill in IP protocol switch table. 102 * All protocols not implemented in kernel go to raw IP protocol handler. 103 */ 104void 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 LIST_INIT(&ipq); 121 ip_id = time.tv_sec & 0xffff; 122 ipintrq.ifq_maxlen = ipqmaxlen; 123 TAILQ_INIT(&in_ifaddr); 124} 125 126struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 127struct route ipforward_rt; 128 129/* 130 * Ip input routine. Checksum and byte swap header. If fragmented 131 * try to reassemble. Process options. Pass to next level. 132 */ 133void 134ipintr() 135{ 136 register struct ip *ip; 137 register struct mbuf *m; 138 register struct ipq *fp; 139 register struct in_ifaddr *ia; 140 struct ipqent *ipqe; 141 int hlen, mff, s; 142 143next: 144 /* 145 * Get next datagram off input queue and get IP header 146 * in first mbuf. 147 */ 148 s = splimp(); 149 IF_DEQUEUE(&ipintrq, m); 150 splx(s); 151 if (m == 0) 152 return; 153#ifdef DIAGNOSTIC 154 if ((m->m_flags & M_PKTHDR) == 0) 155 panic("ipintr no HDR"); 156#endif 157 /* 158 * If no IP addresses have been set yet but the interfaces 159 * are receiving, can't do anything with incoming packets yet. 160 */ 161 if (in_ifaddr.tqh_first == 0) 162 goto bad; 163 ipstat.ips_total++; 164 if (m->m_len < sizeof (struct ip) && 165 (m = m_pullup(m, sizeof (struct ip))) == 0) { 166 ipstat.ips_toosmall++; 167 goto next; 168 } 169 ip = mtod(m, struct ip *); 170 if (ip->ip_v != IPVERSION) { 171 ipstat.ips_badvers++; 172 goto bad; 173 } 174 hlen = ip->ip_hl << 2; 175 if (hlen < sizeof(struct ip)) { /* minimum header length */ 176 ipstat.ips_badhlen++; 177 goto bad; 178 } 179 if (hlen > m->m_len) { 180 if ((m = m_pullup(m, hlen)) == 0) { 181 ipstat.ips_badhlen++; 182 goto next; 183 } 184 ip = mtod(m, struct ip *); 185 } 186 if (ip->ip_sum = in_cksum(m, hlen)) { 187 ipstat.ips_badsum++; 188 goto bad; 189 } 190 191 /* 192 * Convert fields to host representation. 193 */ 194 NTOHS(ip->ip_len); 195 if (ip->ip_len < hlen) { 196 ipstat.ips_badlen++; 197 goto bad; 198 } 199 NTOHS(ip->ip_id); 200 NTOHS(ip->ip_off); 201 202 /* 203 * Check that the amount of data in the buffers 204 * is as at least much as the IP header would have us expect. 205 * Trim mbufs if longer than we expect. 206 * Drop packet if shorter than we expect. 207 */ 208 if (m->m_pkthdr.len < ip->ip_len) { 209 ipstat.ips_tooshort++; 210 goto bad; 211 } 212 if (m->m_pkthdr.len > ip->ip_len) { 213 if (m->m_len == m->m_pkthdr.len) { 214 m->m_len = ip->ip_len; 215 m->m_pkthdr.len = ip->ip_len; 216 } else 217 m_adj(m, ip->ip_len - m->m_pkthdr.len); 218 } 219 220 /* 221 * Process options and, if not destined for us, 222 * ship it on. ip_dooptions returns 1 when an 223 * error was detected (causing an icmp message 224 * to be sent and the original packet to be freed). 225 */ 226 ip_nhops = 0; /* for source routed packets */ 227 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 228 goto next; 229 230 /* 231 * Check our list of addresses, to see if the packet is for us. 232 */ 233 for (ia = in_ifaddr.tqh_first; ia; ia = ia->ia_list.tqe_next) { 234 if (ip->ip_dst.s_addr == ia->ia_addr.sin_addr.s_addr) 235 goto ours; 236 if ( 237#ifdef DIRECTED_BROADCAST 238 ia->ia_ifp == m->m_pkthdr.rcvif && 239#endif 240 (ia->ia_ifp->if_flags & IFF_BROADCAST)) { 241 if (ip->ip_dst.s_addr == ia->ia_broadaddr.sin_addr.s_addr || 242 ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr || 243 /* 244 * Look for all-0's host part (old broadcast addr), 245 * either for subnet or net. 246 */ 247 ip->ip_dst.s_addr == ia->ia_subnet || 248 ip->ip_dst.s_addr == ia->ia_net) 249 goto ours; 250 } 251 } 252 if (IN_MULTICAST(ip->ip_dst.s_addr)) { 253 struct in_multi *inm; 254#ifdef MROUTING 255 extern struct socket *ip_mrouter; 256 257 if (m->m_flags & M_EXT) { 258 if ((m = m_pullup(m, hlen)) == 0) { 259 ipstat.ips_toosmall++; 260 goto next; 261 } 262 ip = mtod(m, struct ip *); 263 } 264 265 if (ip_mrouter) { 266 /* 267 * If we are acting as a multicast router, all 268 * incoming multicast packets are passed to the 269 * kernel-level multicast forwarding function. 270 * The packet is returned (relatively) intact; if 271 * ip_mforward() returns a non-zero value, the packet 272 * must be discarded, else it may be accepted below. 273 * 274 * (The IP ident field is put in the same byte order 275 * as expected when ip_mforward() is called from 276 * ip_output().) 277 */ 278 ip->ip_id = htons(ip->ip_id); 279 if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { 280 ipstat.ips_cantforward++; 281 m_freem(m); 282 goto next; 283 } 284 ip->ip_id = ntohs(ip->ip_id); 285 286 /* 287 * The process-level routing demon needs to receive 288 * all multicast IGMP packets, whether or not this 289 * host belongs to their destination groups. 290 */ 291 if (ip->ip_p == IPPROTO_IGMP) 292 goto ours; 293 ipstat.ips_forward++; 294 } 295#endif 296 /* 297 * See if we belong to the destination multicast group on the 298 * arrival interface. 299 */ 300 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 301 if (inm == NULL) { 302 ipstat.ips_cantforward++; 303 m_freem(m); 304 goto next; 305 } 306 goto ours; 307 } 308 if (ip->ip_dst.s_addr == INADDR_BROADCAST || 309 ip->ip_dst.s_addr == INADDR_ANY) 310 goto ours; 311 312 /* 313 * Not for us; forward if possible and desirable. 314 */ 315 if (ipforwarding == 0) { 316 ipstat.ips_cantforward++; 317 m_freem(m); 318 } else 319 ip_forward(m, 0); 320 goto next; 321 322ours: 323 /* 324 * If offset or IP_MF are set, must reassemble. 325 * Otherwise, nothing need be done. 326 * (We could look in the reassembly queue to see 327 * if the packet was previously fragmented, 328 * but it's not worth the time; just let them time out.) 329 */ 330 if (ip->ip_off &~ IP_DF) { 331 if (m->m_flags & M_EXT) { /* XXX */ 332 if ((m = m_pullup(m, sizeof (struct ip))) == 0) { 333 ipstat.ips_toosmall++; 334 goto next; 335 } 336 ip = mtod(m, struct ip *); 337 } 338 /* 339 * Look for queue of fragments 340 * of this datagram. 341 */ 342 for (fp = ipq.lh_first; fp != NULL; fp = fp->ipq_q.le_next) 343 if (ip->ip_id == fp->ipq_id && 344 ip->ip_src.s_addr == fp->ipq_src.s_addr && 345 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 346 ip->ip_p == fp->ipq_p) 347 goto found; 348 fp = 0; 349found: 350 351 /* 352 * Adjust ip_len to not reflect header, 353 * set ipqe_mff if more fragments are expected, 354 * convert offset of this to bytes. 355 */ 356 ip->ip_len -= hlen; 357 mff = (ip->ip_off & IP_MF) != 0; 358 if (mff) { 359 /* 360 * Make sure that fragments have a data length 361 * that's a non-zero multiple of 8 bytes. 362 */ 363 if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) { 364 ipstat.ips_badfrags++; 365 goto bad; 366 } 367 } 368 ip->ip_off <<= 3; 369 370 /* 371 * If datagram marked as having more fragments 372 * or if this is not the first fragment, 373 * attempt reassembly; if it succeeds, proceed. 374 */ 375 if (mff || ip->ip_off) { 376 ipstat.ips_fragments++; 377 MALLOC(ipqe, struct ipqent *, sizeof (struct ipqent), 378 M_IPQ, M_NOWAIT); 379 if (ipqe == NULL) { 380 ipstat.ips_rcvmemdrop++; 381 goto bad; 382 } 383 ipqe->ipqe_mff = mff; 384 ipqe->ipqe_ip = ip; 385 ip = ip_reass(ipqe, fp); 386 if (ip == 0) 387 goto next; 388 ipstat.ips_reassembled++; 389 m = dtom(ip); 390 } else 391 if (fp) 392 ip_freef(fp); 393 } else 394 ip->ip_len -= hlen; 395 396 /* 397 * Switch out to protocol's input routine. 398 */ 399 ipstat.ips_delivered++; 400 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 401 goto next; 402bad: 403 m_freem(m); 404 goto next; 405} 406 407/* 408 * Take incoming datagram fragment and try to 409 * reassemble it into whole datagram. If a chain for 410 * reassembly of this datagram already exists, then it 411 * is given as fp; otherwise have to make a chain. 412 */ 413struct ip * 414ip_reass(ipqe, fp) 415 register struct ipqent *ipqe; 416 register struct ipq *fp; 417{ 418 register struct mbuf *m = dtom(ipqe->ipqe_ip); 419 register struct ipqent *nq, *p, *q; 420 struct ip *ip; 421 struct mbuf *t; 422 int hlen = ipqe->ipqe_ip->ip_hl << 2; 423 int i, next; 424 425 /* 426 * Presence of header sizes in mbufs 427 * would confuse code below. 428 */ 429 m->m_data += hlen; 430 m->m_len -= hlen; 431 432 /* 433 * If first fragment to arrive, create a reassembly queue. 434 */ 435 if (fp == 0) { 436 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 437 goto dropfrag; 438 fp = mtod(t, struct ipq *); 439 LIST_INSERT_HEAD(&ipq, fp, ipq_q); 440 fp->ipq_ttl = IPFRAGTTL; 441 fp->ipq_p = ipqe->ipqe_ip->ip_p; 442 fp->ipq_id = ipqe->ipqe_ip->ip_id; 443 LIST_INIT(&fp->ipq_fragq); 444 fp->ipq_src = ipqe->ipqe_ip->ip_src; 445 fp->ipq_dst = ipqe->ipqe_ip->ip_dst; 446 p = NULL; 447 goto insert; 448 } 449 450 /* 451 * Find a segment which begins after this one does. 452 */ 453 for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL; 454 p = q, q = q->ipqe_q.le_next) 455 if (q->ipqe_ip->ip_off > ipqe->ipqe_ip->ip_off) 456 break; 457 458 /* 459 * If there is a preceding segment, it may provide some of 460 * our data already. If so, drop the data from the incoming 461 * segment. If it provides all of our data, drop us. 462 */ 463 if (p != NULL) { 464 i = p->ipqe_ip->ip_off + p->ipqe_ip->ip_len - 465 ipqe->ipqe_ip->ip_off; 466 if (i > 0) { 467 if (i >= ipqe->ipqe_ip->ip_len) 468 goto dropfrag; 469 m_adj(dtom(ipqe->ipqe_ip), i); 470 ipqe->ipqe_ip->ip_off += i; 471 ipqe->ipqe_ip->ip_len -= i; 472 } 473 } 474 475 /* 476 * While we overlap succeeding segments trim them or, 477 * if they are completely covered, dequeue them. 478 */ 479 for (; q != NULL && ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len > 480 q->ipqe_ip->ip_off; q = nq) { 481 i = (ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len) - 482 q->ipqe_ip->ip_off; 483 if (i < q->ipqe_ip->ip_len) { 484 q->ipqe_ip->ip_len -= i; 485 q->ipqe_ip->ip_off += i; 486 m_adj(dtom(q->ipqe_ip), i); 487 break; 488 } 489 nq = q->ipqe_q.le_next; 490 m_freem(dtom(q->ipqe_ip)); 491 LIST_REMOVE(q, ipqe_q); 492 FREE(q, M_IPQ); 493 } 494 495insert: 496 /* 497 * Stick new segment in its place; 498 * check for complete reassembly. 499 */ 500 if (p == NULL) { 501 LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q); 502 } else { 503 LIST_INSERT_AFTER(p, ipqe, ipqe_q); 504 } 505 next = 0; 506 for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL; 507 p = q, q = q->ipqe_q.le_next) { 508 if (q->ipqe_ip->ip_off != next) 509 return (0); 510 next += q->ipqe_ip->ip_len; 511 } 512 if (p->ipqe_mff) 513 return (0); 514 515 /* 516 * Reassembly is complete; concatenate fragments. 517 */ 518 q = fp->ipq_fragq.lh_first; 519 ip = q->ipqe_ip; 520 m = dtom(q->ipqe_ip); 521 t = m->m_next; 522 m->m_next = 0; 523 m_cat(m, t); 524 nq = q->ipqe_q.le_next; 525 FREE(q, M_IPQ); 526 for (q = nq; q != NULL; q = nq) { 527 t = dtom(q->ipqe_ip); 528 nq = q->ipqe_q.le_next; 529 FREE(q, M_IPQ); 530 m_cat(m, t); 531 } 532 533 /* 534 * Create header for new ip packet by 535 * modifying header of first packet; 536 * dequeue and discard fragment reassembly header. 537 * Make header visible. 538 */ 539 ip->ip_len = next; 540 ip->ip_src = fp->ipq_src; 541 ip->ip_dst = fp->ipq_dst; 542 LIST_REMOVE(fp, ipq_q); 543 (void) m_free(dtom(fp)); 544 m->m_len += (ip->ip_hl << 2); 545 m->m_data -= (ip->ip_hl << 2); 546 /* some debugging cruft by sklower, below, will go away soon */ 547 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 548 register int plen = 0; 549 for (t = m; m; m = m->m_next) 550 plen += m->m_len; 551 t->m_pkthdr.len = plen; 552 } 553 return (ip); 554 555dropfrag: 556 ipstat.ips_fragdropped++; 557 m_freem(m); 558 FREE(ipqe, M_IPQ); 559 return (0); 560} 561 562/* 563 * Free a fragment reassembly header and all 564 * associated datagrams. 565 */ 566void 567ip_freef(fp) 568 struct ipq *fp; 569{ 570 register struct ipqent *q, *p; 571 572 for (q = fp->ipq_fragq.lh_first; q != NULL; q = p) { 573 p = q->ipqe_q.le_next; 574 m_freem(dtom(q->ipqe_ip)); 575 LIST_REMOVE(q, ipqe_q); 576 FREE(q, M_IPQ); 577 } 578 LIST_REMOVE(fp, ipq_q); 579 (void) m_free(dtom(fp)); 580} 581 582/* 583 * IP timer processing; 584 * if a timer expires on a reassembly 585 * queue, discard it. 586 */ 587void 588ip_slowtimo() 589{ 590 register struct ipq *fp, *nfp; 591 int s = splsoftnet(); 592 593 for (fp = ipq.lh_first; fp != NULL; fp = nfp) { 594 nfp = fp->ipq_q.le_next; 595 if (--fp->ipq_ttl == 0) { 596 ipstat.ips_fragtimeout++; 597 ip_freef(fp); 598 } 599 } 600 splx(s); 601} 602 603/* 604 * Drain off all datagram fragments. 605 */ 606void 607ip_drain() 608{ 609 610 while (ipq.lh_first != NULL) { 611 ipstat.ips_fragdropped++; 612 ip_freef(ipq.lh_first); 613 } 614} 615 616/* 617 * Do option processing on a datagram, 618 * possibly discarding it if bad options are encountered, 619 * or forwarding it if source-routed. 620 * Returns 1 if packet has been forwarded/freed, 621 * 0 if the packet should be processed further. 622 */ 623int 624ip_dooptions(m) 625 struct mbuf *m; 626{ 627 register struct ip *ip = mtod(m, struct ip *); 628 register u_char *cp; 629 register struct ip_timestamp *ipt; 630 register struct in_ifaddr *ia; 631 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 632 struct in_addr *sin, dst; 633 n_time ntime; 634 635 dst = ip->ip_dst; 636 cp = (u_char *)(ip + 1); 637 cnt = (ip->ip_hl << 2) - sizeof (struct ip); 638 for (; cnt > 0; cnt -= optlen, cp += optlen) { 639 opt = cp[IPOPT_OPTVAL]; 640 if (opt == IPOPT_EOL) 641 break; 642 if (opt == IPOPT_NOP) 643 optlen = 1; 644 else { 645 optlen = cp[IPOPT_OLEN]; 646 if (optlen <= 0 || optlen > cnt) { 647 code = &cp[IPOPT_OLEN] - (u_char *)ip; 648 goto bad; 649 } 650 } 651 switch (opt) { 652 653 default: 654 break; 655 656 /* 657 * Source routing with record. 658 * Find interface with current destination address. 659 * If none on this machine then drop if strictly routed, 660 * or do nothing if loosely routed. 661 * Record interface address and bring up next address 662 * component. If strictly routed make sure next 663 * address is on directly accessible net. 664 */ 665 case IPOPT_LSRR: 666 case IPOPT_SSRR: 667 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 668 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 669 goto bad; 670 } 671 ipaddr.sin_addr = ip->ip_dst; 672 ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))); 673 if (ia == 0) { 674 if (opt == IPOPT_SSRR) { 675 type = ICMP_UNREACH; 676 code = ICMP_UNREACH_SRCFAIL; 677 goto bad; 678 } 679 /* 680 * Loose routing, and not at next destination 681 * yet; nothing to do except forward. 682 */ 683 break; 684 } 685 off--; /* 0 origin */ 686 if (off > optlen - sizeof(struct in_addr)) { 687 /* 688 * End of source route. Should be for us. 689 */ 690 save_rte(cp, ip->ip_src); 691 break; 692 } 693 /* 694 * locate outgoing interface 695 */ 696 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 697 sizeof(ipaddr.sin_addr)); 698 if (opt == IPOPT_SSRR) { 699#define INA struct in_ifaddr * 700#define SA struct sockaddr * 701 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 702 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 703 } else 704 ia = ip_rtaddr(ipaddr.sin_addr); 705 if (ia == 0) { 706 type = ICMP_UNREACH; 707 code = ICMP_UNREACH_SRCFAIL; 708 goto bad; 709 } 710 ip->ip_dst = ipaddr.sin_addr; 711 bcopy((caddr_t)&ia->ia_addr.sin_addr, 712 (caddr_t)(cp + off), sizeof(struct in_addr)); 713 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 714 /* 715 * Let ip_intr's mcast routing check handle mcast pkts 716 */ 717 forward = !IN_MULTICAST(ip->ip_dst.s_addr); 718 break; 719 720 case IPOPT_RR: 721 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 722 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 723 goto bad; 724 } 725 /* 726 * If no space remains, ignore. 727 */ 728 off--; /* 0 origin */ 729 if (off > optlen - sizeof(struct in_addr)) 730 break; 731 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 732 sizeof(ipaddr.sin_addr)); 733 /* 734 * locate outgoing interface; if we're the destination, 735 * use the incoming interface (should be same). 736 */ 737 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 738 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 739 type = ICMP_UNREACH; 740 code = ICMP_UNREACH_HOST; 741 goto bad; 742 } 743 bcopy((caddr_t)&ia->ia_addr.sin_addr, 744 (caddr_t)(cp + off), sizeof(struct in_addr)); 745 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 746 break; 747 748 case IPOPT_TS: 749 code = cp - (u_char *)ip; 750 ipt = (struct ip_timestamp *)cp; 751 if (ipt->ipt_len < 5) 752 goto bad; 753 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) { 754 if (++ipt->ipt_oflw == 0) 755 goto bad; 756 break; 757 } 758 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 759 switch (ipt->ipt_flg) { 760 761 case IPOPT_TS_TSONLY: 762 break; 763 764 case IPOPT_TS_TSANDADDR: 765 if (ipt->ipt_ptr + sizeof(n_time) + 766 sizeof(struct in_addr) > ipt->ipt_len) 767 goto bad; 768 ipaddr.sin_addr = dst; 769 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 770 m->m_pkthdr.rcvif); 771 if (ia == 0) 772 continue; 773 bcopy((caddr_t)&ia->ia_addr.sin_addr, 774 (caddr_t)sin, sizeof(struct in_addr)); 775 ipt->ipt_ptr += sizeof(struct in_addr); 776 break; 777 778 case IPOPT_TS_PRESPEC: 779 if (ipt->ipt_ptr + sizeof(n_time) + 780 sizeof(struct in_addr) > ipt->ipt_len) 781 goto bad; 782 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, 783 sizeof(struct in_addr)); 784 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 785 continue; 786 ipt->ipt_ptr += sizeof(struct in_addr); 787 break; 788 789 default: 790 goto bad; 791 } 792 ntime = iptime(); 793 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, 794 sizeof(n_time)); 795 ipt->ipt_ptr += sizeof(n_time); 796 } 797 } 798 if (forward) { 799 ip_forward(m, 1); 800 return (1); 801 } 802 return (0); 803bad: 804 ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */ 805 icmp_error(m, type, code, 0, 0); 806 ipstat.ips_badoptions++; 807 return (1); 808} 809 810/* 811 * Given address of next destination (final or next hop), 812 * return internet address info of interface to be used to get there. 813 */ 814struct in_ifaddr * 815ip_rtaddr(dst) 816 struct in_addr dst; 817{ 818 register struct sockaddr_in *sin; 819 820 sin = satosin(&ipforward_rt.ro_dst); 821 822 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 823 if (ipforward_rt.ro_rt) { 824 RTFREE(ipforward_rt.ro_rt); 825 ipforward_rt.ro_rt = 0; 826 } 827 sin->sin_family = AF_INET; 828 sin->sin_len = sizeof(*sin); 829 sin->sin_addr = dst; 830 831 rtalloc(&ipforward_rt); 832 } 833 if (ipforward_rt.ro_rt == 0) 834 return ((struct in_ifaddr *)0); 835 return (ifatoia(ipforward_rt.ro_rt->rt_ifa)); 836} 837 838/* 839 * Save incoming source route for use in replies, 840 * to be picked up later by ip_srcroute if the receiver is interested. 841 */ 842void 843save_rte(option, dst) 844 u_char *option; 845 struct in_addr dst; 846{ 847 unsigned olen; 848 849 olen = option[IPOPT_OLEN]; 850#ifdef DIAGNOSTIC 851 if (ipprintfs) 852 printf("save_rte: olen %d\n", olen); 853#endif 854 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 855 return; 856 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); 857 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 858 ip_srcrt.dst = dst; 859} 860 861/* 862 * Retrieve incoming source route for use in replies, 863 * in the same form used by setsockopt. 864 * The first hop is placed before the options, will be removed later. 865 */ 866struct mbuf * 867ip_srcroute() 868{ 869 register struct in_addr *p, *q; 870 register struct mbuf *m; 871 872 if (ip_nhops == 0) 873 return ((struct mbuf *)0); 874 m = m_get(M_DONTWAIT, MT_SOOPTS); 875 if (m == 0) 876 return ((struct mbuf *)0); 877 878#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 879 880 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 881 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 882 OPTSIZ; 883#ifdef DIAGNOSTIC 884 if (ipprintfs) 885 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 886#endif 887 888 /* 889 * First save first hop for return route 890 */ 891 p = &ip_srcrt.route[ip_nhops - 1]; 892 *(mtod(m, struct in_addr *)) = *p--; 893#ifdef DIAGNOSTIC 894 if (ipprintfs) 895 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 896#endif 897 898 /* 899 * Copy option fields and padding (nop) to mbuf. 900 */ 901 ip_srcrt.nop = IPOPT_NOP; 902 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 903 bcopy((caddr_t)&ip_srcrt.nop, 904 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); 905 q = (struct in_addr *)(mtod(m, caddr_t) + 906 sizeof(struct in_addr) + OPTSIZ); 907#undef OPTSIZ 908 /* 909 * Record return path as an IP source route, 910 * reversing the path (pointers are now aligned). 911 */ 912 while (p >= ip_srcrt.route) { 913#ifdef DIAGNOSTIC 914 if (ipprintfs) 915 printf(" %lx", ntohl(q->s_addr)); 916#endif 917 *q++ = *p--; 918 } 919 /* 920 * Last hop goes to final destination. 921 */ 922 *q = ip_srcrt.dst; 923#ifdef DIAGNOSTIC 924 if (ipprintfs) 925 printf(" %lx\n", ntohl(q->s_addr)); 926#endif 927 return (m); 928} 929 930/* 931 * Strip out IP options, at higher 932 * level protocol in the kernel. 933 * Second argument is buffer to which options 934 * will be moved, and return value is their length. 935 * XXX should be deleted; last arg currently ignored. 936 */ 937void 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 957int 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 */ 980void 981ip_forward(m, srcrt) 982 struct mbuf *m; 983 int srcrt; 984{ 985 register struct ip *ip = mtod(m, struct ip *); 986 register struct sockaddr_in *sin; 987 register struct rtentry *rt; 988 int error, type = 0, code; 989 struct mbuf *mcopy; 990 n_long dest; 991 struct ifnet *destifp; 992 993 dest = 0; 994#ifdef DIAGNOSTIC 995 if (ipprintfs) 996 printf("forward: src %x dst %x ttl %x\n", ip->ip_src, 997 ip->ip_dst, ip->ip_ttl); 998#endif 999 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 1000 ipstat.ips_cantforward++; 1001 m_freem(m); 1002 return; 1003 } 1004 HTONS(ip->ip_id); 1005 if (ip->ip_ttl <= IPTTLDEC) { 1006 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); 1007 return; 1008 } 1009 ip->ip_ttl -= IPTTLDEC; 1010 1011 sin = satosin(&ipforward_rt.ro_dst); 1012 if ((rt = ipforward_rt.ro_rt) == 0 || 1013 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1014 if (ipforward_rt.ro_rt) { 1015 RTFREE(ipforward_rt.ro_rt); 1016 ipforward_rt.ro_rt = 0; 1017 } 1018 sin->sin_family = AF_INET; 1019 sin->sin_len = sizeof(*sin); 1020 sin->sin_addr = ip->ip_dst; 1021 1022 rtalloc(&ipforward_rt); 1023 if (ipforward_rt.ro_rt == 0) { 1024 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); 1025 return; 1026 } 1027 rt = ipforward_rt.ro_rt; 1028 } 1029 1030 /* 1031 * Save at most 64 bytes of the packet in case 1032 * we need to generate an ICMP message to the src. 1033 */ 1034 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1035 1036 /* 1037 * If forwarding packet using same interface that it came in on, 1038 * perhaps should send a redirect to sender to shortcut a hop. 1039 * Only send redirect if source is sending directly to us, 1040 * and if packet was not source routed (or has any options). 1041 * Also, don't send redirect if forwarding using a default route 1042 * or a route modified by a redirect. 1043 */ 1044 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1045 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1046 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1047 ipsendredirects && !srcrt) { 1048 if (rt->rt_ifa && 1049 (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) == 1050 ifatoia(rt->rt_ifa)->ia_subnet) { 1051 if (rt->rt_flags & RTF_GATEWAY) 1052 dest = satosin(rt->rt_gateway)->sin_addr.s_addr; 1053 else 1054 dest = ip->ip_dst.s_addr; 1055 /* Router requirements says to only send host redirects */ 1056 type = ICMP_REDIRECT; 1057 code = ICMP_REDIRECT_HOST; 1058#ifdef DIAGNOSTIC 1059 if (ipprintfs) 1060 printf("redirect (%d) to %lx\n", code, (u_int32_t)dest); 1061#endif 1062 } 1063 } 1064 1065 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING 1066#ifdef DIRECTED_BROADCAST 1067 | IP_ALLOWBROADCAST 1068#endif 1069 , 0); 1070 if (error) 1071 ipstat.ips_cantforward++; 1072 else { 1073 ipstat.ips_forward++; 1074 if (type) 1075 ipstat.ips_redirectsent++; 1076 else { 1077 if (mcopy) 1078 m_freem(mcopy); 1079 return; 1080 } 1081 } 1082 if (mcopy == NULL) 1083 return; 1084 destifp = NULL; 1085 1086 switch (error) { 1087 1088 case 0: /* forwarded, but need redirect */ 1089 /* type, code set above */ 1090 break; 1091 1092 case ENETUNREACH: /* shouldn't happen, checked above */ 1093 case EHOSTUNREACH: 1094 case ENETDOWN: 1095 case EHOSTDOWN: 1096 default: 1097 type = ICMP_UNREACH; 1098 code = ICMP_UNREACH_HOST; 1099 break; 1100 1101 case EMSGSIZE: 1102 type = ICMP_UNREACH; 1103 code = ICMP_UNREACH_NEEDFRAG; 1104 if (ipforward_rt.ro_rt) 1105 destifp = ipforward_rt.ro_rt->rt_ifp; 1106 ipstat.ips_cantfrag++; 1107 break; 1108 1109 case ENOBUFS: 1110 type = ICMP_SOURCEQUENCH; 1111 code = 0; 1112 break; 1113 } 1114 icmp_error(mcopy, type, code, dest, destifp); 1115} 1116 1117int 1118ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 1119 int *name; 1120 u_int namelen; 1121 void *oldp; 1122 size_t *oldlenp; 1123 void *newp; 1124 size_t newlen; 1125{ 1126 /* All sysctl names at this level are terminal. */ 1127 if (namelen != 1) 1128 return (ENOTDIR); 1129 1130 switch (name[0]) { 1131 case IPCTL_FORWARDING: 1132 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding)); 1133 case IPCTL_SENDREDIRECTS: 1134 return (sysctl_int(oldp, oldlenp, newp, newlen, 1135 &ipsendredirects)); 1136 case IPCTL_DEFTTL: 1137 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl)); 1138#ifdef notyet 1139 case IPCTL_DEFMTU: 1140 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); 1141#endif 1142 default: 1143 return (EOPNOTSUPP); 1144 } 1145 /* NOTREACHED */ 1146} 1147