Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/ip_input.c
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1 /* 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. 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 8.2 (Berkeley) 1/4/94 34 * $FreeBSD: src/sys/netinet/ip_input.c,v 1.50.2.25 2000/06/26 20:49:21 alfred Exp $ 35 * $ANA: ip_input.c,v 1.5 1996/09/18 14:34:59 wollman Exp $ 36 */ 37 38 #define _IP_VHL 39 40 #include "opt_ipfw.h" 41 42 #include <stddef.h> 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/malloc.h> 47 #include <sys/mbuf.h> 48 #include <sys/domain.h> 49 #include <sys/protosw.h> 50 #include <sys/socket.h> 51 #include <sys/errno.h> 52 #include <sys/time.h> 53 #include <sys/kernel.h> 54 #include <sys/syslog.h> 55 #include <sys/sysctl.h> 56 57 #include <net/if.h> 58 #include <net/if_dl.h> 59 #include <net/route.h> 60 #include <net/netisr.h> 61 62 #include <netinet/in.h> 63 #include <netinet/in_systm.h> 64 #include <netinet/in_var.h> 65 #include <netinet/ip.h> 66 #include <netinet/in_pcb.h> 67 #include <netinet/in_var.h> 68 #include <netinet/ip_var.h> 69 #include <netinet/ip_icmp.h> 70 #include <machine/in_cksum.h> 71 72 #include <sys/socketvar.h> 73 74 #ifdef IPFIREWALL 75 #include <netinet/ip_fw.h> 76 #endif 77 78 #ifdef DUMMYNET 79 #include <netinet/ip_dummynet.h> 80 #endif 81 int rsvp_on = 0; 82 static int ip_rsvp_on; 83 struct socket *ip_rsvpd; 84 85 static int ipforwarding = 0; 86 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW, 87 &ipforwarding, 0, ""); 88 89 static int ipsendredirects = 1; /* XXX */ 90 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW, 91 &ipsendredirects, 0, ""); 92 93 int ip_defttl = IPDEFTTL; 94 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW, 95 &ip_defttl, 0, ""); 96 97 static int ip_dosourceroute = 0; 98 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW, 99 &ip_dosourceroute, 0, ""); 100 101 static int ip_acceptsourceroute = 0; 102 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, 103 CTLFLAG_RW, &ip_acceptsourceroute, 0, ""); 104 #ifdef DIAGNOSTIC 105 static int ipprintfs = 0; 106 #endif 107 108 extern struct domain inetdomain; 109 extern struct protosw inetsw[]; 110 u_char ip_protox[IPPROTO_MAX]; 111 static int ipqmaxlen = IFQ_MAXLEN; 112 struct in_ifaddr *in_ifaddr; /* first inet address */ 113 struct ifqueue ipintrq; 114 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RD, 115 &ipintrq.ifq_maxlen, 0, ""); 116 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD, 117 &ipintrq.ifq_drops, 0, ""); 118 119 struct ipstat ipstat; 120 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RD, 121 &ipstat , ipstat, ""); 122 123 /* Packet reassembly stuff */ 124 #define IPREASS_NHASH_LOG2 6 125 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2) 126 #define IPREASS_HMASK (IPREASS_NHASH - 1) 127 #define IPREASS_HASH(x,y) \ 128 ((((x) & 0xF | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK) 129 130 static struct ipq ipq[IPREASS_NHASH]; 131 static int nipq = 0; /* total # of reass queues */ 132 static int maxnipq; 133 134 #ifdef IPCTL_DEFMTU 135 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, 136 &ip_mtu, 0, ""); 137 #endif 138 139 #if !defined(COMPAT_IPFW) || COMPAT_IPFW == 1 140 #undef COMPAT_IPFW 141 #define COMPAT_IPFW 1 142 #else 143 #undef COMPAT_IPFW 144 #endif 145 146 #ifdef COMPAT_IPFW 147 /* Firewall hooks */ 148 ip_fw_chk_t *ip_fw_chk_ptr = NULL ; 149 ip_fw_ctl_t *ip_fw_ctl_ptr = NULL ; 150 151 #ifdef DUMMYNET 152 ip_dn_ctl_t *ip_dn_ctl_ptr; 153 #endif 154 155 /* IP Network Address Translation (NAT) hooks */ 156 /* there is no kernel nat in 2.2... */ 157 ip_nat_t *ip_nat_ptr = NULL; 158 ip_nat_ctl_t *ip_nat_ctl_ptr = NULL; 159 #endif 160 161 /* 162 * We need to save the IP options in case a protocol wants to respond 163 * to an incoming packet over the same route if the packet got here 164 * using IP source routing. This allows connection establishment and 165 * maintenance when the remote end is on a network that is not known 166 * to us. 167 */ 168 static int ip_nhops = 0; 169 static struct ip_srcrt { 170 struct in_addr dst; /* final destination */ 171 char nop; /* one NOP to align */ 172 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ 173 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; 174 } ip_srcrt; 175 176 #ifdef IPDIVERT 177 /* 178 * Shared variable between ip_input() and ip_reass() to communicate 179 * about which packets, once assembled from fragments, get diverted, 180 * and to which port. 181 */ 182 static u_short frag_divert_port; 183 #endif 184 185 static void save_rte __P((u_char *, struct in_addr)); 186 static void ip_deq __P((struct ipasfrag *)); 187 static int ip_dooptions __P((struct mbuf *)); 188 static void ip_enq __P((struct ipasfrag *, struct ipasfrag *)); 189 static void ip_forward __P((struct mbuf *, int)); 190 static void ip_freef __P((struct ipq *)); 191 static struct ip * 192 ip_reass __P((struct ipasfrag *, struct ipq *, struct ipq *)); 193 static struct in_ifaddr * 194 ip_rtaddr __P((struct in_addr)); 195 static void ipintr __P((void)); 196 /* 197 * IP initialization: fill in IP protocol switch table. 198 * All protocols not implemented in kernel go to raw IP protocol handler. 199 */ 200 void 201 ip_init() 202 { 203 register struct protosw *pr; 204 register int i; 205 206 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); 207 if (pr == 0) 208 panic("ip_init"); 209 for (i = 0; i < IPPROTO_MAX; i++) 210 ip_protox[i] = pr - inetsw; 211 for (pr = inetdomain.dom_protosw; 212 pr < inetdomain.dom_protoswNPROTOSW; pr++) 213 if (pr->pr_domain->dom_family == PF_INET && 214 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) 215 ip_protox[pr->pr_protocol] = pr - inetsw; 216 217 for (i = 0; i < IPREASS_NHASH; i++) 218 ipq[i].next = ipq[i].prev = &ipq[i]; 219 220 maxnipq = nmbclusters/4; 221 222 ip_id = time.tv_sec & 0xffff; 223 ipintrq.ifq_maxlen = ipqmaxlen; 224 #ifdef IPFIREWALL 225 ip_fw_init(); 226 #endif 227 #ifdef IPNAT 228 ip_nat_init(); 229 #endif 230 #ifdef DUMMYNET 231 ip_dn_init(); 232 #endif 233 234 } 235 236 static struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; 237 static struct route ipforward_rt; 238 239 /* 240 * Ip input routine. Checksum and byte swap header. If fragmented 241 * try to reassemble. Process options. Pass to next level. 242 */ 243 void 244 ip_input(struct mbuf *m) 245 { 246 struct ip *ip; 247 struct ipq *fp; 248 struct in_ifaddr *ia; 249 int i, hlen; 250 u_short sum; 251 #ifndef IPDIVERT /* dummy variable for the firewall code to play with */ 252 u_short ip_divert_cookie = 0 ; 253 #endif 254 #ifdef COMPAT_IPFW 255 struct ip_fw_chain *rule = NULL ; 256 #endif 257 258 #if defined(IPFIREWALL) && defined(DUMMYNET) 259 /* 260 * dummynet packet are prepended a vestigial mbuf with 261 * m_type = MT_DUMMYNET and m_data pointing to the matching 262 * rule. 263 */ 264 if (m->m_type == MT_DUMMYNET) { 265 rule = (struct ip_fw_chain *)(m->m_data) ; 266 m = m->m_next ; 267 ip = mtod(m, struct ip *); 268 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 269 goto iphack ; 270 } 271 #endif 272 #ifdef DIAGNOSTIC 273 if ((m->m_flags & M_PKTHDR) == 0) 274 panic("ip_input no HDR"); 275 #endif 276 /* 277 * If no IP addresses have been set yet but the interfaces 278 * are receiving, can't do anything with incoming packets yet. 279 */ 280 if (in_ifaddr == NULL) 281 goto bad; 282 ipstat.ips_total++; 283 284 if (m->m_pkthdr.len < sizeof(struct ip)) 285 goto tooshort; 286 287 #ifdef DIAGNOSTIC 288 if (m->m_len < sizeof(struct ip)) 289 panic("ipintr mbuf too short"); 290 #endif 291 292 if (m->m_len < sizeof (struct ip) && 293 (m = m_pullup(m, sizeof (struct ip))) == 0) { 294 ipstat.ips_toosmall++; 295 return; 296 } 297 ip = mtod(m, struct ip *); 298 299 if (IP_VHL_V(ip->ip_vhl) != IPVERSION) { 300 ipstat.ips_badvers++; 301 goto bad; 302 } 303 304 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 305 if (hlen < sizeof(struct ip)) { /* minimum header length */ 306 ipstat.ips_badhlen++; 307 goto bad; 308 } 309 if (hlen > m->m_len) { 310 if ((m = m_pullup(m, hlen)) == 0) { 311 ipstat.ips_badhlen++; 312 return; 313 } 314 ip = mtod(m, struct ip *); 315 } 316 if (hlen == sizeof(struct ip)) { 317 sum = in_cksum_hdr(ip); 318 } else { 319 sum = in_cksum(m, hlen); 320 } 321 if (sum) { 322 ipstat.ips_badsum++; 323 goto bad; 324 } 325 326 /* 327 * Convert fields to host representation. 328 */ 329 NTOHS(ip->ip_len); 330 if (ip->ip_len < hlen) { 331 ipstat.ips_badlen++; 332 goto bad; 333 } 334 NTOHS(ip->ip_id); 335 NTOHS(ip->ip_off); 336 337 /* 338 * Check that the amount of data in the buffers 339 * is as at least much as the IP header would have us expect. 340 * Trim mbufs if longer than we expect. 341 * Drop packet if shorter than we expect. 342 */ 343 if (m->m_pkthdr.len < ip->ip_len) { 344 tooshort: 345 ipstat.ips_tooshort++; 346 goto bad; 347 } 348 if (m->m_pkthdr.len > ip->ip_len) { 349 if (m->m_len == m->m_pkthdr.len) { 350 m->m_len = ip->ip_len; 351 m->m_pkthdr.len = ip->ip_len; 352 } else 353 m_adj(m, ip->ip_len - m->m_pkthdr.len); 354 } 355 /* 356 * IpHack's section. 357 * Right now when no processing on packet has done 358 * and it is still fresh out of network we do our black 359 * deals with it. 360 * - Firewall: deny/allow/divert 361 * - Xlate: translate packet's addr/port (NAT). 362 * - Pipe: pass pkt through dummynet. 363 * - Wrap: fake packet's addr/port <unimpl.> 364 * - Encapsulate: put it in another IP and send out. <unimp.> 365 */ 366 367 iphack: 368 #ifdef COMPAT_IPFW 369 if (ip_fw_chk_ptr) { 370 i = (*ip_fw_chk_ptr)(&ip,hlen,NULL, &ip_divert_cookie, &m, &rule); 371 if (!m) /* packet discarded by firewall */ 372 return; 373 if (i) { /* divert, dummynet, and other hacks... */ 374 #ifdef DUMMYNET 375 if (i & 0x10000) { 376 /* send packet to the appropriate pipe */ 377 dummynet_io(i&0xffff, DN_TO_IP_IN, m, NULL, NULL,0, rule); 378 return ; 379 } 380 #endif 381 #ifdef IPDIVERT 382 if (i <= 0xffff) { /* Divert packet */ 383 frag_divert_port = i; 384 goto ours; 385 } 386 #endif 387 /* no match above, we have to just drop packet */ 388 m_freem(m); 389 m = NULL; 390 return ; 391 } 392 } 393 394 if (ip_nat_ptr && !(*ip_nat_ptr)(&ip, &m, m->m_pkthdr.rcvif, IP_NAT_IN)) 395 return; 396 #endif 397 398 /* 399 * Process options and, if not destined for us, 400 * ship it on. ip_dooptions returns 1 when an 401 * error was detected (causing an icmp message 402 * to be sent and the original packet to be freed). 403 */ 404 ip_nhops = 0; /* for source routed packets */ 405 if (hlen > sizeof (struct ip) && ip_dooptions(m)) 406 return; 407 408 /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no 409 * matter if it is destined to another node, or whether it is 410 * a multicast one, RSVP wants it! and prevents it from being forwarded 411 * anywhere else. Also checks if the rsvp daemon is running before 412 * grabbing the packet. 413 */ 414 if (rsvp_on && ip->ip_p==IPPROTO_RSVP) 415 goto ours; 416 417 /* 418 * Check our list of addresses, to see if the packet is for us. 419 */ 420 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 421 #define satosin(sa) ((struct sockaddr_in *)(sa)) 422 423 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) 424 goto ours; 425 #ifdef BOOTP_COMPAT 426 if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) 427 goto ours; 428 #endif 429 if (ia->ia_ifp && ia->ia_ifp->if_flags & IFF_BROADCAST) { 430 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 431 ip->ip_dst.s_addr) 432 goto ours; 433 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) 434 goto ours; 435 } 436 } 437 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { 438 struct in_multi *inm; 439 if (ip_mrouter) { 440 /* 441 * If we are acting as a multicast router, all 442 * incoming multicast packets are passed to the 443 * kernel-level multicast forwarding function. 444 * The packet is returned (relatively) intact; if 445 * ip_mforward() returns a non-zero value, the packet 446 * must be discarded, else it may be accepted below. 447 * 448 * (The IP ident field is put in the same byte order 449 * as expected when ip_mforward() is called from 450 * ip_output().) 451 */ 452 ip->ip_id = htons(ip->ip_id); 453 if (ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) { 454 ipstat.ips_cantforward++; 455 m_freem(m); 456 return; 457 } 458 ip->ip_id = ntohs(ip->ip_id); 459 460 /* 461 * The process-level routing demon needs to receive 462 * all multicast IGMP packets, whether or not this 463 * host belongs to their destination groups. 464 */ 465 if (ip->ip_p == IPPROTO_IGMP) 466 goto ours; 467 ipstat.ips_forward++; 468 } 469 /* 470 * See if we belong to the destination multicast group on the 471 * arrival interface. 472 */ 473 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); 474 if (inm == NULL) { 475 ipstat.ips_cantforward++; 476 m_freem(m); 477 return; 478 } 479 goto ours; 480 } 481 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) 482 goto ours; 483 if (ip->ip_dst.s_addr == INADDR_ANY) 484 goto ours; 485 486 /* 487 * Not for us; forward if possible and desirable. 488 */ 489 if (ipforwarding == 0) { 490 ipstat.ips_cantforward++; 491 m_freem(m); 492 } else 493 ip_forward(m, 0); 494 return; 495 496 ours: 497 498 /* 499 * If offset or IP_MF are set, must reassemble. 500 * Otherwise, nothing need be done. 501 * (We could look in the reassembly queue to see 502 * if the packet was previously fragmented, 503 * but it's not worth the time; just let them time out.) 504 */ 505 if (ip->ip_off &~ (IP_DF | IP_RF)) { 506 if (m->m_flags & M_EXT) { /* XXX */ 507 if ((m = m_pullup(m, hlen)) == 0) { 508 ipstat.ips_toosmall++; 509 #ifdef IPDIVERT 510 frag_divert_port = 0; 511 ip_divert_cookie = 0; 512 #endif 513 return; 514 } 515 ip = mtod(m, struct ip *); 516 } 517 sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); 518 /* 519 * Look for queue of fragments 520 * of this datagram. 521 */ 522 for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next) 523 if (ip->ip_id == fp->ipq_id && 524 ip->ip_src.s_addr == fp->ipq_src.s_addr && 525 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 526 ip->ip_p == fp->ipq_p) 527 goto found; 528 529 fp = 0; 530 531 /* check if there's a place for the new queue */ 532 if (nipq > maxnipq) { 533 /* 534 * drop something from the tail of the current queue 535 * before proceeding further 536 */ 537 if (ipq[sum].prev == &ipq[sum]) { /* gak */ 538 for (i = 0; i < IPREASS_NHASH; i++) { 539 if (ipq[i].prev != &ipq[i]) { 540 ip_freef(ipq[i].prev); 541 break; 542 } 543 } 544 } else 545 ip_freef(ipq[sum].prev); 546 } 547 found: 548 /* 549 * Adjust ip_len to not reflect header, 550 * set ip_mff if more fragments are expected, 551 * convert offset of this to bytes. 552 */ 553 ip->ip_len -= hlen; 554 ((struct ipasfrag *)ip)->ipf_mff &= ~1; 555 if (ip->ip_off & IP_MF) 556 ((struct ipasfrag *)ip)->ipf_mff |= 1; 557 ip->ip_off <<= 3; 558 559 /* 560 * If datagram marked as having more fragments 561 * or if this is not the first fragment, 562 * attempt reassembly; if it succeeds, proceed. 563 */ 564 if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) { 565 ipstat.ips_fragments++; 566 ip = ip_reass((struct ipasfrag *)ip, fp, &ipq[sum]); 567 if (ip == 0) 568 return; 569 ipstat.ips_reassembled++; 570 m = dtom(ip); 571 #ifdef IPDIVERT 572 if (frag_divert_port) { 573 ip->ip_len += hlen; 574 HTONS(ip->ip_len); 575 HTONS(ip->ip_off); 576 HTONS(ip->ip_id); 577 ip->ip_sum = 0; 578 ip->ip_sum = in_cksum_hdr(ip); 579 NTOHS(ip->ip_id); 580 NTOHS(ip->ip_off); 581 NTOHS(ip->ip_len); 582 ip->ip_len -= hlen; 583 } 584 #endif 585 } else 586 if (fp) 587 ip_freef(fp); 588 } else 589 ip->ip_len -= hlen; 590 591 #ifdef IPDIVERT 592 /* 593 * Divert reassembled packets to the divert protocol if required 594 * If divert port is null then cookie should be too, 595 * so we shouldn't need to clear them here. Assume ip_divert does so. 596 */ 597 if (frag_divert_port) { 598 ipstat.ips_delivered++; 599 ip_divert_port = frag_divert_port; 600 frag_divert_port = 0; 601 (*inetsw[ip_protox[IPPROTO_DIVERT]].pr_input)(m, hlen); 602 return; 603 } 604 605 /* Don't let packets divert themselves */ 606 if (ip->ip_p == IPPROTO_DIVERT) { 607 ipstat.ips_noproto++; 608 goto bad; 609 } 610 #endif 611 612 /* 613 * Switch out to protocol's input routine. 614 */ 615 ipstat.ips_delivered++; 616 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); 617 return; 618 bad: 619 m_freem(m); 620 } 621 622 /* 623 * IP software interrupt routine - to go away sometime soon 624 */ 625 static void 626 ipintr(void) 627 { 628 int s; 629 struct mbuf *m; 630 631 while(1) { 632 s = splimp(); 633 IF_DEQUEUE(&ipintrq, m); 634 splx(s); 635 if (m == 0) 636 return; 637 ip_input(m); 638 } 639 } 640 641 NETISR_SET(NETISR_IP, ipintr); 642 643 /* 644 * Take incoming datagram fragment and try to 645 * reassemble it into whole datagram. If a chain for 646 * reassembly of this datagram already exists, then it 647 * is given as fp; otherwise have to make a chain. 648 */ 649 static struct ip * 650 ip_reass(ip, fp, where) 651 register struct ipasfrag *ip; 652 register struct ipq *fp; 653 struct ipq *where; 654 { 655 register struct mbuf *m = dtom(ip); 656 register struct ipasfrag *q; 657 struct mbuf *t; 658 int hlen = ip->ip_hl << 2; 659 int i, next; 660 661 /* 662 * Presence of header sizes in mbufs 663 * would confuse code below. 664 */ 665 m->m_data += hlen; 666 m->m_len -= hlen; 667 668 /* 669 * If first fragment to arrive, create a reassembly queue. 670 */ 671 if (fp == 0) { 672 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) 673 goto dropfrag; 674 fp = mtod(t, struct ipq *); 675 insque(fp, where); 676 nipq++; 677 fp->ipq_ttl = IPFRAGTTL; 678 fp->ipq_p = ip->ip_p; 679 fp->ipq_id = ip->ip_id; 680 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; 681 fp->ipq_src = ((struct ip *)ip)->ip_src; 682 fp->ipq_dst = ((struct ip *)ip)->ip_dst; 683 #ifdef IPDIVERT 684 fp->ipq_divert = 0; 685 #ifdef IPFW_DIVERT_RESTART 686 fp->ipq_div_cookie = 0; 687 #endif /* IPFW_DIVERT_RESTART */ 688 #endif 689 q = (struct ipasfrag *)fp; 690 goto insert; 691 } 692 693 /* 694 * Find a segment which begins after this one does. 695 */ 696 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) 697 if (q->ip_off > ip->ip_off) 698 break; 699 700 /* 701 * If there is a preceding segment, it may provide some of 702 * our data already. If so, drop the data from the incoming 703 * segment. If it provides all of our data, drop us. 704 */ 705 if (q->ipf_prev != (struct ipasfrag *)fp) { 706 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; 707 if (i > 0) { 708 if (i >= ip->ip_len) 709 goto dropfrag; 710 m_adj(dtom(ip), i); 711 ip->ip_off += i; 712 ip->ip_len -= i; 713 } 714 } 715 716 /* 717 * While we overlap succeeding segments trim them or, 718 * if they are completely covered, dequeue them. 719 */ 720 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { 721 struct mbuf *m0; 722 723 i = (ip->ip_off + ip->ip_len) - q->ip_off; 724 if (i < q->ip_len) { 725 q->ip_len -= i; 726 q->ip_off += i; 727 m_adj(dtom(q), i); 728 break; 729 } 730 m0 = dtom(q); 731 q = q->ipf_next; 732 ip_deq(q->ipf_prev); 733 m_freem(m0); 734 } 735 736 insert: 737 738 #ifdef IPDIVERT 739 /* 740 * Any fragment diverting causes the whole packet to divert 741 */ 742 if (frag_divert_port) { 743 fp->ipq_divert = frag_divert_port; 744 #ifdef IPFW_DIVERT_RESTART 745 fp->ipq_div_cookie = ip_divert_cookie; 746 #endif /* IPFW_DIVERT_RESTART */ 747 } 748 frag_divert_port = 0; 749 ip_divert_cookie = 0; 750 #endif 751 752 /* 753 * Stick new segment in its place; 754 * check for complete reassembly. 755 */ 756 ip_enq(ip, q->ipf_prev); 757 next = 0; 758 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { 759 if (q->ip_off != next) 760 return (0); 761 next += q->ip_len; 762 } 763 if (q->ipf_prev->ipf_mff & 1) 764 return (0); 765 766 /* 767 * Reassembly is complete. Make sure the packet is a sane size. 768 */ 769 if (next + (IP_VHL_HL(((struct ip *)fp->ipq_next)->ip_vhl) << 2) 770 > IP_MAXPACKET) { 771 ipstat.ips_toolong++; 772 ip_freef(fp); 773 return (0); 774 } 775 776 /* 777 * Concatenate fragments. 778 */ 779 q = fp->ipq_next; 780 m = dtom(q); 781 t = m->m_next; 782 m->m_next = 0; 783 m_cat(m, t); 784 q = q->ipf_next; 785 while (q != (struct ipasfrag *)fp) { 786 t = dtom(q); 787 q = q->ipf_next; 788 m_cat(m, t); 789 } 790 791 #ifdef IPDIVERT 792 /* 793 * Record divert port for packet, if any 794 */ 795 frag_divert_port = fp->ipq_divert; 796 #ifdef IPFW_DIVERT_RESTART 797 ip_divert_cookie = fp->ipq_div_cookie; 798 #endif /* IPFW_DIVERT_RESTART */ 799 #endif 800 801 /* 802 * Create header for new ip packet by 803 * modifying header of first packet; 804 * dequeue and discard fragment reassembly header. 805 * Make header visible. 806 */ 807 ip = fp->ipq_next; 808 ip->ip_len = next; 809 ip->ipf_mff &= ~1; 810 ((struct ip *)ip)->ip_src = fp->ipq_src; 811 ((struct ip *)ip)->ip_dst = fp->ipq_dst; 812 remque(fp); 813 nipq--; 814 (void) m_free(dtom(fp)); 815 m = dtom(ip); 816 m->m_len += (ip->ip_hl << 2); 817 m->m_data -= (ip->ip_hl << 2); 818 /* some debugging cruft by sklower, below, will go away soon */ 819 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 820 register int plen = 0; 821 for (t = m; m; m = m->m_next) 822 plen += m->m_len; 823 t->m_pkthdr.len = plen; 824 } 825 return ((struct ip *)ip); 826 827 dropfrag: 828 #ifdef IPDIVERT 829 frag_divert_port = 0; 830 ip_divert_cookie = 0; 831 #endif 832 ipstat.ips_fragdropped++; 833 m_freem(m); 834 return (0); 835 } 836 837 /* 838 * Free a fragment reassembly header and all 839 * associated datagrams. 840 */ 841 static void 842 ip_freef(fp) 843 struct ipq *fp; 844 { 845 register struct ipasfrag *q, *p; 846 847 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { 848 p = q->ipf_next; 849 ip_deq(q); 850 m_freem(dtom(q)); 851 } 852 remque(fp); 853 (void) m_free(dtom(fp)); 854 nipq--; 855 } 856 857 /* 858 * Put an ip fragment on a reassembly chain. 859 * Like insque, but pointers in middle of structure. 860 */ 861 static void 862 ip_enq(p, prev) 863 register struct ipasfrag *p, *prev; 864 { 865 866 p->ipf_prev = prev; 867 p->ipf_next = prev->ipf_next; 868 prev->ipf_next->ipf_prev = p; 869 prev->ipf_next = p; 870 } 871 872 /* 873 * To ip_enq as remque is to insque. 874 */ 875 static void 876 ip_deq(p) 877 register struct ipasfrag *p; 878 { 879 880 p->ipf_prev->ipf_next = p->ipf_next; 881 p->ipf_next->ipf_prev = p->ipf_prev; 882 } 883 884 /* 885 * IP timer processing; 886 * if a timer expires on a reassembly 887 * queue, discard it. 888 */ 889 void 890 ip_slowtimo() 891 { 892 register struct ipq *fp; 893 int s = splnet(); 894 int i; 895 896 for (i = 0; i < IPREASS_NHASH; i++) { 897 fp = ipq[i].next; 898 if (fp == 0) 899 continue; 900 while (fp != &ipq[i]) { 901 --fp->ipq_ttl; 902 fp = fp->next; 903 if (fp->prev->ipq_ttl == 0) { 904 ipstat.ips_fragtimeout++; 905 ip_freef(fp->prev); 906 } 907 } 908 } 909 splx(s); 910 } 911 912 /* 913 * Drain off all datagram fragments. 914 */ 915 void 916 ip_drain() 917 { 918 int i; 919 920 for (i = 0; i < IPREASS_NHASH; i++) { 921 while (ipq[i].next != &ipq[i]) { 922 ipstat.ips_fragdropped++; 923 ip_freef(ipq[i].next); 924 } 925 } 926 in_rtqdrain(); 927 } 928 929 /* 930 * Do option processing on a datagram, 931 * possibly discarding it if bad options are encountered, 932 * or forwarding it if source-routed. 933 * Returns 1 if packet has been forwarded/freed, 934 * 0 if the packet should be processed further. 935 */ 936 static int 937 ip_dooptions(m) 938 struct mbuf *m; 939 { 940 register struct ip *ip = mtod(m, struct ip *); 941 register u_char *cp; 942 register struct ip_timestamp *ipt; 943 register struct in_ifaddr *ia; 944 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; 945 struct in_addr *sin, dst; 946 n_time ntime; 947 948 dst = ip->ip_dst; 949 cp = (u_char *)(ip + 1); 950 cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip); 951 for (; cnt > 0; cnt -= optlen, cp += optlen) { 952 opt = cp[IPOPT_OPTVAL]; 953 if (opt == IPOPT_EOL) 954 break; 955 if (opt == IPOPT_NOP) 956 optlen = 1; 957 else { 958 if (cnt < IPOPT_OLEN + sizeof(*cp)) { 959 code = &cp[IPOPT_OLEN] - (u_char *)ip; 960 goto bad; 961 } 962 optlen = cp[IPOPT_OLEN]; 963 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { 964 code = &cp[IPOPT_OLEN] - (u_char *)ip; 965 goto bad; 966 } 967 } 968 switch (opt) { 969 970 default: 971 break; 972 973 /* 974 * Source routing with record. 975 * Find interface with current destination address. 976 * If none on this machine then drop if strictly routed, 977 * or do nothing if loosely routed. 978 * Record interface address and bring up next address 979 * component. If strictly routed make sure next 980 * address is on directly accessible net. 981 */ 982 case IPOPT_LSRR: 983 case IPOPT_SSRR: 984 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 985 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 986 goto bad; 987 } 988 ipaddr.sin_addr = ip->ip_dst; 989 ia = (struct in_ifaddr *) 990 ifa_ifwithaddr((struct sockaddr *)&ipaddr); 991 if (ia == 0) { 992 if (opt == IPOPT_SSRR) { 993 type = ICMP_UNREACH; 994 code = ICMP_UNREACH_SRCFAIL; 995 goto bad; 996 } 997 if (!ip_dosourceroute) 998 goto nosourcerouting; 999 /* 1000 * Loose routing, and not at next destination 1001 * yet; nothing to do except forward. 1002 */ 1003 break; 1004 } 1005 off--; /* 0 origin */ 1006 if (off > optlen - sizeof(struct in_addr)) { 1007 /* 1008 * End of source route. Should be for us. 1009 */ 1010 if (!ip_acceptsourceroute) 1011 goto nosourcerouting; 1012 save_rte(cp, ip->ip_src); 1013 break; 1014 } 1015 1016 if (!ip_dosourceroute) { 1017 if (ipforwarding) { 1018 char buf[16]; /* aaa.bbb.ccc.ddd\0 */ 1019 /* 1020 * Acting as a router, so generate ICMP 1021 */ 1022 nosourcerouting: 1023 strcpy(buf, inet_ntoa(ip->ip_dst)); 1024 log(LOG_WARNING, 1025 "attempted source route from %s to %s\n", 1026 inet_ntoa(ip->ip_src), buf); 1027 type = ICMP_UNREACH; 1028 code = ICMP_UNREACH_SRCFAIL; 1029 goto bad; 1030 } else { 1031 /* 1032 * Not acting as a router, so silently drop. 1033 */ 1034 ipstat.ips_cantforward++; 1035 m_freem(m); 1036 return (1); 1037 } 1038 } 1039 1040 /* 1041 * locate outgoing interface 1042 */ 1043 (void)memcpy(&ipaddr.sin_addr, cp + off, 1044 sizeof(ipaddr.sin_addr)); 1045 1046 if (opt == IPOPT_SSRR) { 1047 #define INA struct in_ifaddr * 1048 #define SA struct sockaddr * 1049 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) 1050 ia = (INA)ifa_ifwithnet((SA)&ipaddr); 1051 } else 1052 ia = ip_rtaddr(ipaddr.sin_addr); 1053 if (ia == 0) { 1054 type = ICMP_UNREACH; 1055 code = ICMP_UNREACH_SRCFAIL; 1056 goto bad; 1057 } 1058 ip->ip_dst = ipaddr.sin_addr; 1059 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 1060 sizeof(struct in_addr)); 1061 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 1062 /* 1063 * Let ip_intr's mcast routing check handle mcast pkts 1064 */ 1065 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); 1066 break; 1067 1068 case IPOPT_RR: 1069 if (optlen < IPOPT_OFFSET + sizeof(*cp)) { 1070 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 1071 goto bad; 1072 } 1073 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { 1074 code = &cp[IPOPT_OFFSET] - (u_char *)ip; 1075 goto bad; 1076 } 1077 /* 1078 * If no space remains, ignore. 1079 */ 1080 off--; /* 0 origin */ 1081 if (off > optlen - sizeof(struct in_addr)) 1082 break; 1083 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, 1084 sizeof(ipaddr.sin_addr)); 1085 /* 1086 * locate outgoing interface; if we're the destination, 1087 * use the incoming interface (should be same). 1088 */ 1089 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && 1090 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { 1091 type = ICMP_UNREACH; 1092 code = ICMP_UNREACH_HOST; 1093 goto bad; 1094 } 1095 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), 1096 sizeof(struct in_addr)); 1097 cp[IPOPT_OFFSET] += sizeof(struct in_addr); 1098 break; 1099 1100 case IPOPT_TS: 1101 code = cp - (u_char *)ip; 1102 ipt = (struct ip_timestamp *)cp; 1103 if (ipt->ipt_len < 5) 1104 goto bad; 1105 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { 1106 if (++ipt->ipt_oflw == 0) 1107 goto bad; 1108 break; 1109 } 1110 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); 1111 switch (ipt->ipt_flg) { 1112 1113 case IPOPT_TS_TSONLY: 1114 break; 1115 1116 case IPOPT_TS_TSANDADDR: 1117 if (ipt->ipt_ptr - 1 + sizeof(n_time) + 1118 sizeof(struct in_addr) > ipt->ipt_len) 1119 goto bad; 1120 ipaddr.sin_addr = dst; 1121 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, 1122 m->m_pkthdr.rcvif); 1123 if (ia == 0) 1124 continue; 1125 (void)memcpy(sin, &IA_SIN(ia)->sin_addr, 1126 sizeof(struct in_addr)); 1127 ipt->ipt_ptr += sizeof(struct in_addr); 1128 break; 1129 1130 case IPOPT_TS_PRESPEC: 1131 if (ipt->ipt_ptr - 1 + sizeof(n_time) + 1132 sizeof(struct in_addr) > ipt->ipt_len) 1133 goto bad; 1134 (void)memcpy(&ipaddr.sin_addr, sin, 1135 sizeof(struct in_addr)); 1136 if (ifa_ifwithaddr((SA)&ipaddr) == 0) 1137 continue; 1138 ipt->ipt_ptr += sizeof(struct in_addr); 1139 break; 1140 1141 default: 1142 goto bad; 1143 } 1144 ntime = iptime(); 1145 (void)memcpy(cp + ipt->ipt_ptr - 1, &ntime, 1146 sizeof(n_time)); 1147 ipt->ipt_ptr += sizeof(n_time); 1148 } 1149 } 1150 if (forward && ipforwarding) { 1151 ip_forward(m, 1); 1152 return (1); 1153 } 1154 return (0); 1155 bad: 1156 ip->ip_len -= IP_VHL_HL(ip->ip_vhl) << 2; /* XXX icmp_error adds in hdr length */ 1157 icmp_error(m, type, code, 0, 0); 1158 ipstat.ips_badoptions++; 1159 return (1); 1160 } 1161 1162 /* 1163 * Given address of next destination (final or next hop), 1164 * return internet address info of interface to be used to get there. 1165 */ 1166 static struct in_ifaddr * 1167 ip_rtaddr(dst) 1168 struct in_addr dst; 1169 { 1170 register struct sockaddr_in *sin; 1171 1172 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; 1173 1174 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { 1175 if (ipforward_rt.ro_rt) { 1176 RTFREE(ipforward_rt.ro_rt); 1177 ipforward_rt.ro_rt = 0; 1178 } 1179 sin->sin_family = AF_INET; 1180 sin->sin_len = sizeof(*sin); 1181 sin->sin_addr = dst; 1182 1183 rtalloc_ign(&ipforward_rt, RTF_PRCLONING); 1184 } 1185 if (ipforward_rt.ro_rt == 0) 1186 return ((struct in_ifaddr *)0); 1187 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); 1188 } 1189 1190 /* 1191 * Save incoming source route for use in replies, 1192 * to be picked up later by ip_srcroute if the receiver is interested. 1193 */ 1194 void 1195 save_rte(option, dst) 1196 u_char *option; 1197 struct in_addr dst; 1198 { 1199 unsigned olen; 1200 1201 olen = option[IPOPT_OLEN]; 1202 #ifdef DIAGNOSTIC 1203 if (ipprintfs) 1204 printf("save_rte: olen %d\n", olen); 1205 #endif 1206 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) 1207 return; 1208 bcopy(option, ip_srcrt.srcopt, olen); 1209 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); 1210 ip_srcrt.dst = dst; 1211 } 1212 1213 /* 1214 * Retrieve incoming source route for use in replies, 1215 * in the same form used by setsockopt. 1216 * The first hop is placed before the options, will be removed later. 1217 */ 1218 struct mbuf * 1219 ip_srcroute() 1220 { 1221 register struct in_addr *p, *q; 1222 register struct mbuf *m; 1223 1224 if (ip_nhops == 0) 1225 return ((struct mbuf *)0); 1226 m = m_get(M_DONTWAIT, MT_SOOPTS); 1227 if (m == 0) 1228 return ((struct mbuf *)0); 1229 1230 #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) 1231 1232 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ 1233 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + 1234 OPTSIZ; 1235 #ifdef DIAGNOSTIC 1236 if (ipprintfs) 1237 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); 1238 #endif 1239 1240 /* 1241 * First save first hop for return route 1242 */ 1243 p = &ip_srcrt.route[ip_nhops - 1]; 1244 *(mtod(m, struct in_addr *)) = *p--; 1245 #ifdef DIAGNOSTIC 1246 if (ipprintfs) 1247 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); 1248 #endif 1249 1250 /* 1251 * Copy option fields and padding (nop) to mbuf. 1252 */ 1253 ip_srcrt.nop = IPOPT_NOP; 1254 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; 1255 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), 1256 &ip_srcrt.nop, OPTSIZ); 1257 q = (struct in_addr *)(mtod(m, caddr_t) + 1258 sizeof(struct in_addr) + OPTSIZ); 1259 #undef OPTSIZ 1260 /* 1261 * Record return path as an IP source route, 1262 * reversing the path (pointers are now aligned). 1263 */ 1264 while (p >= ip_srcrt.route) { 1265 #ifdef DIAGNOSTIC 1266 if (ipprintfs) 1267 printf(" %lx", ntohl(q->s_addr)); 1268 #endif 1269 *q++ = *p--; 1270 } 1271 /* 1272 * Last hop goes to final destination. 1273 */ 1274 *q = ip_srcrt.dst; 1275 #ifdef DIAGNOSTIC 1276 if (ipprintfs) 1277 printf(" %lx\n", ntohl(q->s_addr)); 1278 #endif 1279 return (m); 1280 } 1281 1282 /* 1283 * Strip out IP options, at higher 1284 * level protocol in the kernel. 1285 * Second argument is buffer to which options 1286 * will be moved, and return value is their length. 1287 * XXX should be deleted; last arg currently ignored. 1288 */ 1289 void 1290 ip_stripoptions(m, mopt) 1291 register struct mbuf *m; 1292 struct mbuf *mopt; 1293 { 1294 register int i; 1295 struct ip *ip = mtod(m, struct ip *); 1296 register caddr_t opts; 1297 int olen; 1298 1299 olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip); 1300 opts = (caddr_t)(ip + 1); 1301 i = m->m_len - (sizeof (struct ip) + olen); 1302 bcopy(opts + olen, opts, (unsigned)i); 1303 m->m_len -= olen; 1304 if (m->m_flags & M_PKTHDR) 1305 m->m_pkthdr.len -= olen; 1306 ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2); 1307 } 1308 1309 u_char inetctlerrmap[PRC_NCMDS] = { 1310 0, 0, 0, 0, 1311 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, 1312 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, 1313 EMSGSIZE, EHOSTUNREACH, 0, 0, 1314 0, 0, 0, 0, 1315 ENOPROTOOPT 1316 }; 1317 1318 /* 1319 * Forward a packet. If some error occurs return the sender 1320 * an icmp packet. Note we can't always generate a meaningful 1321 * icmp message because icmp doesn't have a large enough repertoire 1322 * of codes and types. 1323 * 1324 * If not forwarding, just drop the packet. This could be confusing 1325 * if ipforwarding was zero but some routing protocol was advancing 1326 * us as a gateway to somewhere. However, we must let the routing 1327 * protocol deal with that. 1328 * 1329 * The srcrt parameter indicates whether the packet is being forwarded 1330 * via a source route. 1331 */ 1332 static void 1333 ip_forward(m, srcrt) 1334 struct mbuf *m; 1335 int srcrt; 1336 { 1337 register struct ip *ip = mtod(m, struct ip *); 1338 register struct sockaddr_in *sin; 1339 register struct rtentry *rt; 1340 int error, type = 0, code = 0; 1341 struct mbuf *mcopy; 1342 n_long dest; 1343 struct ifnet *destifp; 1344 1345 dest = 0; 1346 #ifdef DIAGNOSTIC 1347 if (ipprintfs) 1348 printf("forward: src %lx dst %lx ttl %x\n", 1349 ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl); 1350 #endif 1351 1352 1353 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { 1354 ipstat.ips_cantforward++; 1355 m_freem(m); 1356 return; 1357 } 1358 HTONS(ip->ip_id); 1359 if (ip->ip_ttl <= IPTTLDEC) { 1360 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); 1361 return; 1362 } 1363 ip->ip_ttl -= IPTTLDEC; 1364 1365 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; 1366 if ((rt = ipforward_rt.ro_rt) == 0 || 1367 ip->ip_dst.s_addr != sin->sin_addr.s_addr) { 1368 if (ipforward_rt.ro_rt) { 1369 RTFREE(ipforward_rt.ro_rt); 1370 ipforward_rt.ro_rt = 0; 1371 } 1372 sin->sin_family = AF_INET; 1373 sin->sin_len = sizeof(*sin); 1374 sin->sin_addr = ip->ip_dst; 1375 1376 rtalloc_ign(&ipforward_rt, RTF_PRCLONING); 1377 if (ipforward_rt.ro_rt == 0) { 1378 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); 1379 return; 1380 } 1381 rt = ipforward_rt.ro_rt; 1382 } 1383 1384 /* 1385 * Save at most 64 bytes of the packet in case 1386 * we need to generate an ICMP message to the src. 1387 */ 1388 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); 1389 1390 /* 1391 * If forwarding packet using same interface that it came in on, 1392 * perhaps should send a redirect to sender to shortcut a hop. 1393 * Only send redirect if source is sending directly to us, 1394 * and if packet was not source routed (or has any options). 1395 * Also, don't send redirect if forwarding using a default route 1396 * or a route modified by a redirect. 1397 */ 1398 #define satosin(sa) ((struct sockaddr_in *)(sa)) 1399 if (rt->rt_ifp == m->m_pkthdr.rcvif && 1400 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && 1401 satosin(rt_key(rt))->sin_addr.s_addr != 0 && 1402 ipsendredirects && !srcrt) { 1403 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) 1404 u_long src = ntohl(ip->ip_src.s_addr); 1405 1406 if (RTA(rt) && 1407 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { 1408 if (rt->rt_flags & RTF_GATEWAY) 1409 dest = satosin(rt->rt_gateway)->sin_addr.s_addr; 1410 else 1411 dest = ip->ip_dst.s_addr; 1412 /* Router requirements says to only send host redirects */ 1413 type = ICMP_REDIRECT; 1414 code = ICMP_REDIRECT_HOST; 1415 #ifdef DIAGNOSTIC 1416 if (ipprintfs) 1417 printf("redirect (%d) to %lx\n", code, (u_long)dest); 1418 #endif 1419 } 1420 } 1421 1422 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, 1423 IP_FORWARDING, 0); 1424 if (error) 1425 ipstat.ips_cantforward++; 1426 else { 1427 ipstat.ips_forward++; 1428 if (type) 1429 ipstat.ips_redirectsent++; 1430 else { 1431 if (mcopy) 1432 m_freem(mcopy); 1433 return; 1434 } 1435 } 1436 if (mcopy == NULL) 1437 return; 1438 destifp = NULL; 1439 1440 switch (error) { 1441 1442 case 0: /* forwarded, but need redirect */ 1443 /* type, code set above */ 1444 break; 1445 1446 case ENETUNREACH: /* shouldn't happen, checked above */ 1447 case EHOSTUNREACH: 1448 case ENETDOWN: 1449 case EHOSTDOWN: 1450 default: 1451 type = ICMP_UNREACH; 1452 code = ICMP_UNREACH_HOST; 1453 break; 1454 1455 case EMSGSIZE: 1456 type = ICMP_UNREACH; 1457 code = ICMP_UNREACH_NEEDFRAG; 1458 if (ipforward_rt.ro_rt) 1459 destifp = ipforward_rt.ro_rt->rt_ifp; 1460 ipstat.ips_cantfrag++; 1461 break; 1462 1463 case ENOBUFS: 1464 type = ICMP_SOURCEQUENCH; 1465 code = 0; 1466 break; 1467 } 1468 icmp_error(mcopy, type, code, dest, destifp); 1469 } 1470 1471 void 1472 ip_savecontrol(inp, mp, ip, m) 1473 register struct inpcb *inp; 1474 register struct mbuf **mp; 1475 register struct ip *ip; 1476 register struct mbuf *m; 1477 { 1478 if (inp->inp_socket->so_options & SO_TIMESTAMP) { 1479 struct timeval tv; 1480 1481 microtime(&tv); 1482 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv), 1483 SCM_TIMESTAMP, SOL_SOCKET); 1484 if (*mp) 1485 mp = &(*mp)->m_next; 1486 } 1487 if (inp->inp_flags & INP_RECVDSTADDR) { 1488 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst, 1489 sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP); 1490 if (*mp) 1491 mp = &(*mp)->m_next; 1492 } 1493 #ifdef notyet 1494 /* XXX 1495 * Moving these out of udp_input() made them even more broken 1496 * than they already were. 1497 */ 1498 /* options were tossed already */ 1499 if (inp->inp_flags & INP_RECVOPTS) { 1500 *mp = sbcreatecontrol((caddr_t) opts_deleted_above, 1501 sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP); 1502 if (*mp) 1503 mp = &(*mp)->m_next; 1504 } 1505 /* ip_srcroute doesn't do what we want here, need to fix */ 1506 if (inp->inp_flags & INP_RECVRETOPTS) { 1507 *mp = sbcreatecontrol((caddr_t) ip_srcroute(), 1508 sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP); 1509 if (*mp) 1510 mp = &(*mp)->m_next; 1511 } 1512 #endif 1513 if (inp->inp_flags & INP_RECVIF) { 1514 struct sockaddr_dl sdl; 1515 1516 sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]); 1517 sdl.sdl_family = AF_LINK; 1518 sdl.sdl_index = m->m_pkthdr.rcvif ? 1519 m->m_pkthdr.rcvif->if_index : 0; 1520 sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0; 1521 *mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len, 1522 IP_RECVIF, IPPROTO_IP); 1523 if (*mp) 1524 mp = &(*mp)->m_next; 1525 } 1526 } 1527 1528 int 1529 ip_rsvp_init(struct socket *so) 1530 { 1531 if (so->so_type != SOCK_RAW || 1532 so->so_proto->pr_protocol != IPPROTO_RSVP) 1533 return EOPNOTSUPP; 1534 1535 if (ip_rsvpd != NULL) 1536 return EADDRINUSE; 1537 1538 ip_rsvpd = so; 1539 /* 1540 * This may seem silly, but we need to be sure we don't over-increment 1541 * the RSVP counter, in case something slips up. 1542 */ 1543 if (!ip_rsvp_on) { 1544 ip_rsvp_on = 1; 1545 rsvp_on++; 1546 } 1547 1548 return 0; 1549 } 1550 1551 int 1552 ip_rsvp_done(void) 1553 { 1554 ip_rsvpd = NULL; 1555 /* 1556 * This may seem silly, but we need to be sure we don't over-decrement 1557 * the RSVP counter, in case something slips up. 1558 */ 1559 if (ip_rsvp_on) { 1560 ip_rsvp_on = 0; 1561 rsvp_on--; 1562 } 1563 return 0; 1564 }
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