ip_input.c revision 1.1.1.2 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 */
35
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/malloc.h>
39 #include <sys/mbuf.h>
40 #include <sys/domain.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/errno.h>
44 #include <sys/time.h>
45 #include <sys/kernel.h>
46
47 #include <net/if.h>
48 #include <net/route.h>
49
50 #include <netinet/in.h>
51 #include <netinet/in_systm.h>
52 #include <netinet/ip.h>
53 #include <netinet/in_pcb.h>
54 #include <netinet/in_var.h>
55 #include <netinet/ip_var.h>
56 #include <netinet/ip_icmp.h>
57
58 #ifndef IPFORWARDING
59 #ifdef GATEWAY
60 #define IPFORWARDING 1 /* forward IP packets not for us */
61 #else /* GATEWAY */
62 #define IPFORWARDING 0 /* don't forward IP packets not for us */
63 #endif /* GATEWAY */
64 #endif /* IPFORWARDING */
65 #ifndef IPSENDREDIRECTS
66 #define IPSENDREDIRECTS 1
67 #endif
68 int ipforwarding = IPFORWARDING;
69 int ipsendredirects = IPSENDREDIRECTS;
70 int ip_defttl = IPDEFTTL;
71 #ifdef DIAGNOSTIC
72 int ipprintfs = 0;
73 #endif
74
75 extern struct domain inetdomain;
76 extern struct protosw inetsw[];
77 u_char ip_protox[IPPROTO_MAX];
78 int ipqmaxlen = IFQ_MAXLEN;
79 struct in_ifaddr *in_ifaddr; /* first inet address */
80 struct ifqueue ipintrq;
81
82 /*
83 * We need to save the IP options in case a protocol wants to respond
84 * to an incoming packet over the same route if the packet got here
85 * using IP source routing. This allows connection establishment and
86 * maintenance when the remote end is on a network that is not known
87 * to us.
88 */
89 int ip_nhops = 0;
90 static struct ip_srcrt {
91 struct in_addr dst; /* final destination */
92 char nop; /* one NOP to align */
93 char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
94 struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
95 } ip_srcrt;
96
97 #ifdef GATEWAY
98 extern int if_index;
99 u_long *ip_ifmatrix;
100 #endif
101
102 static void save_rte __P((u_char *, struct in_addr));
103 /*
104 * IP initialization: fill in IP protocol switch table.
105 * All protocols not implemented in kernel go to raw IP protocol handler.
106 */
107 void
108 ip_init()
109 {
110 register struct protosw *pr;
111 register int i;
112
113 pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
114 if (pr == 0)
115 panic("ip_init");
116 for (i = 0; i < IPPROTO_MAX; i++)
117 ip_protox[i] = pr - inetsw;
118 for (pr = inetdomain.dom_protosw;
119 pr < inetdomain.dom_protoswNPROTOSW; pr++)
120 if (pr->pr_domain->dom_family == PF_INET &&
121 pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
122 ip_protox[pr->pr_protocol] = pr - inetsw;
123 ipq.next = ipq.prev = &ipq;
124 ip_id = time.tv_sec & 0xffff;
125 ipintrq.ifq_maxlen = ipqmaxlen;
126 #ifdef GATEWAY
127 i = (if_index + 1) * (if_index + 1) * sizeof (u_long);
128 ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK);
129 bzero((char *)ip_ifmatrix, i);
130 #endif
131 }
132
133 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
134 struct route ipforward_rt;
135
136 /*
137 * Ip input routine. Checksum and byte swap header. If fragmented
138 * try to reassemble. Process options. Pass to next level.
139 */
140 void
141 ipintr()
142 {
143 register struct ip *ip;
144 register struct mbuf *m;
145 register struct ipq *fp;
146 register struct in_ifaddr *ia;
147 int hlen, s;
148
149 next:
150 /*
151 * Get next datagram off input queue and get IP header
152 * in first mbuf.
153 */
154 s = splimp();
155 IF_DEQUEUE(&ipintrq, m);
156 splx(s);
157 if (m == 0)
158 return;
159 #ifdef DIAGNOSTIC
160 if ((m->m_flags & M_PKTHDR) == 0)
161 panic("ipintr no HDR");
162 #endif
163 /*
164 * If no IP addresses have been set yet but the interfaces
165 * are receiving, can't do anything with incoming packets yet.
166 */
167 if (in_ifaddr == NULL)
168 goto bad;
169 ipstat.ips_total++;
170 if (m->m_len < sizeof (struct ip) &&
171 (m = m_pullup(m, sizeof (struct ip))) == 0) {
172 ipstat.ips_toosmall++;
173 goto next;
174 }
175 ip = mtod(m, struct ip *);
176 if (ip->ip_v != IPVERSION) {
177 ipstat.ips_badvers++;
178 goto bad;
179 }
180 hlen = ip->ip_hl << 2;
181 if (hlen < sizeof(struct ip)) { /* minimum header length */
182 ipstat.ips_badhlen++;
183 goto bad;
184 }
185 if (hlen > m->m_len) {
186 if ((m = m_pullup(m, hlen)) == 0) {
187 ipstat.ips_badhlen++;
188 goto next;
189 }
190 ip = mtod(m, struct ip *);
191 }
192 if (ip->ip_sum = in_cksum(m, hlen)) {
193 ipstat.ips_badsum++;
194 goto bad;
195 }
196
197 /*
198 * Convert fields to host representation.
199 */
200 NTOHS(ip->ip_len);
201 if (ip->ip_len < hlen) {
202 ipstat.ips_badlen++;
203 goto bad;
204 }
205 NTOHS(ip->ip_id);
206 NTOHS(ip->ip_off);
207
208 /*
209 * Check that the amount of data in the buffers
210 * is as at least much as the IP header would have us expect.
211 * Trim mbufs if longer than we expect.
212 * Drop packet if shorter than we expect.
213 */
214 if (m->m_pkthdr.len < ip->ip_len) {
215 ipstat.ips_tooshort++;
216 goto bad;
217 }
218 if (m->m_pkthdr.len > ip->ip_len) {
219 if (m->m_len == m->m_pkthdr.len) {
220 m->m_len = ip->ip_len;
221 m->m_pkthdr.len = ip->ip_len;
222 } else
223 m_adj(m, ip->ip_len - m->m_pkthdr.len);
224 }
225
226 /*
227 * Process options and, if not destined for us,
228 * ship it on. ip_dooptions returns 1 when an
229 * error was detected (causing an icmp message
230 * to be sent and the original packet to be freed).
231 */
232 ip_nhops = 0; /* for source routed packets */
233 if (hlen > sizeof (struct ip) && ip_dooptions(m))
234 goto next;
235
236 /*
237 * Check our list of addresses, to see if the packet is for us.
238 */
239 for (ia = in_ifaddr; ia; ia = ia->ia_next) {
240 #define satosin(sa) ((struct sockaddr_in *)(sa))
241
242 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
243 goto ours;
244 if (
245 #ifdef DIRECTED_BROADCAST
246 ia->ia_ifp == m->m_pkthdr.rcvif &&
247 #endif
248 (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
249 u_long t;
250
251 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
252 ip->ip_dst.s_addr)
253 goto ours;
254 if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
255 goto ours;
256 /*
257 * Look for all-0's host part (old broadcast addr),
258 * either for subnet or net.
259 */
260 t = ntohl(ip->ip_dst.s_addr);
261 if (t == ia->ia_subnet)
262 goto ours;
263 if (t == ia->ia_net)
264 goto ours;
265 }
266 }
267 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
268 struct in_multi *inm;
269 #ifdef MROUTING
270 extern struct socket *ip_mrouter;
271
272 if (ip_mrouter) {
273 /*
274 * If we are acting as a multicast router, all
275 * incoming multicast packets are passed to the
276 * kernel-level multicast forwarding function.
277 * The packet is returned (relatively) intact; if
278 * ip_mforward() returns a non-zero value, the packet
279 * must be discarded, else it may be accepted below.
280 *
281 * (The IP ident field is put in the same byte order
282 * as expected when ip_mforward() is called from
283 * ip_output().)
284 */
285 ip->ip_id = htons(ip->ip_id);
286 if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
287 ipstat.ips_cantforward++;
288 m_freem(m);
289 goto next;
290 }
291 ip->ip_id = ntohs(ip->ip_id);
292
293 /*
294 * The process-level routing demon needs to receive
295 * all multicast IGMP packets, whether or not this
296 * host belongs to their destination groups.
297 */
298 if (ip->ip_p == IPPROTO_IGMP)
299 goto ours;
300 ipstat.ips_forward++;
301 }
302 #endif
303 /*
304 * See if we belong to the destination multicast group on the
305 * arrival interface.
306 */
307 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
308 if (inm == NULL) {
309 ipstat.ips_cantforward++;
310 m_freem(m);
311 goto next;
312 }
313 goto ours;
314 }
315 if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
316 goto ours;
317 if (ip->ip_dst.s_addr == INADDR_ANY)
318 goto ours;
319
320 /*
321 * Not for us; forward if possible and desirable.
322 */
323 if (ipforwarding == 0) {
324 ipstat.ips_cantforward++;
325 m_freem(m);
326 } else
327 ip_forward(m, 0);
328 goto next;
329
330 ours:
331 /*
332 * If offset or IP_MF are set, must reassemble.
333 * Otherwise, nothing need be done.
334 * (We could look in the reassembly queue to see
335 * if the packet was previously fragmented,
336 * but it's not worth the time; just let them time out.)
337 */
338 if (ip->ip_off &~ IP_DF) {
339 if (m->m_flags & M_EXT) { /* XXX */
340 if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
341 ipstat.ips_toosmall++;
342 goto next;
343 }
344 ip = mtod(m, struct ip *);
345 }
346 /*
347 * Look for queue of fragments
348 * of this datagram.
349 */
350 for (fp = ipq.next; fp != &ipq; fp = fp->next)
351 if (ip->ip_id == fp->ipq_id &&
352 ip->ip_src.s_addr == fp->ipq_src.s_addr &&
353 ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
354 ip->ip_p == fp->ipq_p)
355 goto found;
356 fp = 0;
357 found:
358
359 /*
360 * Adjust ip_len to not reflect header,
361 * set ip_mff if more fragments are expected,
362 * convert offset of this to bytes.
363 */
364 ip->ip_len -= hlen;
365 ((struct ipasfrag *)ip)->ipf_mff &= ~1;
366 if (ip->ip_off & IP_MF)
367 ((struct ipasfrag *)ip)->ipf_mff |= 1;
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 (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) {
376 ipstat.ips_fragments++;
377 ip = ip_reass((struct ipasfrag *)ip, fp);
378 if (ip == 0)
379 goto next;
380 ipstat.ips_reassembled++;
381 m = dtom(ip);
382 } else
383 if (fp)
384 ip_freef(fp);
385 } else
386 ip->ip_len -= hlen;
387
388 /*
389 * Switch out to protocol's input routine.
390 */
391 ipstat.ips_delivered++;
392 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
393 goto next;
394 bad:
395 m_freem(m);
396 goto next;
397 }
398
399 /*
400 * Take incoming datagram fragment and try to
401 * reassemble it into whole datagram. If a chain for
402 * reassembly of this datagram already exists, then it
403 * is given as fp; otherwise have to make a chain.
404 */
405 struct ip *
406 ip_reass(ip, fp)
407 register struct ipasfrag *ip;
408 register struct ipq *fp;
409 {
410 register struct mbuf *m = dtom(ip);
411 register struct ipasfrag *q;
412 struct mbuf *t;
413 int hlen = ip->ip_hl << 2;
414 int i, next;
415
416 /*
417 * Presence of header sizes in mbufs
418 * would confuse code below.
419 */
420 m->m_data += hlen;
421 m->m_len -= hlen;
422
423 /*
424 * If first fragment to arrive, create a reassembly queue.
425 */
426 if (fp == 0) {
427 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
428 goto dropfrag;
429 fp = mtod(t, struct ipq *);
430 insque(fp, &ipq);
431 fp->ipq_ttl = IPFRAGTTL;
432 fp->ipq_p = ip->ip_p;
433 fp->ipq_id = ip->ip_id;
434 fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
435 fp->ipq_src = ((struct ip *)ip)->ip_src;
436 fp->ipq_dst = ((struct ip *)ip)->ip_dst;
437 q = (struct ipasfrag *)fp;
438 goto insert;
439 }
440
441 /*
442 * Find a segment which begins after this one does.
443 */
444 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
445 if (q->ip_off > ip->ip_off)
446 break;
447
448 /*
449 * If there is a preceding segment, it may provide some of
450 * our data already. If so, drop the data from the incoming
451 * segment. If it provides all of our data, drop us.
452 */
453 if (q->ipf_prev != (struct ipasfrag *)fp) {
454 i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
455 if (i > 0) {
456 if (i >= ip->ip_len)
457 goto dropfrag;
458 m_adj(dtom(ip), i);
459 ip->ip_off += i;
460 ip->ip_len -= i;
461 }
462 }
463
464 /*
465 * While we overlap succeeding segments trim them or,
466 * if they are completely covered, dequeue them.
467 */
468 while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
469 i = (ip->ip_off + ip->ip_len) - q->ip_off;
470 if (i < q->ip_len) {
471 q->ip_len -= i;
472 q->ip_off += i;
473 m_adj(dtom(q), i);
474 break;
475 }
476 q = q->ipf_next;
477 m_freem(dtom(q->ipf_prev));
478 ip_deq(q->ipf_prev);
479 }
480
481 insert:
482 /*
483 * Stick new segment in its place;
484 * check for complete reassembly.
485 */
486 ip_enq(ip, q->ipf_prev);
487 next = 0;
488 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
489 if (q->ip_off != next)
490 return (0);
491 next += q->ip_len;
492 }
493 if (q->ipf_prev->ipf_mff & 1)
494 return (0);
495
496 /*
497 * Reassembly is complete; concatenate fragments.
498 */
499 q = fp->ipq_next;
500 m = dtom(q);
501 t = m->m_next;
502 m->m_next = 0;
503 m_cat(m, t);
504 q = q->ipf_next;
505 while (q != (struct ipasfrag *)fp) {
506 t = dtom(q);
507 q = q->ipf_next;
508 m_cat(m, t);
509 }
510
511 /*
512 * Create header for new ip packet by
513 * modifying header of first packet;
514 * dequeue and discard fragment reassembly header.
515 * Make header visible.
516 */
517 ip = fp->ipq_next;
518 ip->ip_len = next;
519 ip->ipf_mff &= ~1;
520 ((struct ip *)ip)->ip_src = fp->ipq_src;
521 ((struct ip *)ip)->ip_dst = fp->ipq_dst;
522 remque(fp);
523 (void) m_free(dtom(fp));
524 m = dtom(ip);
525 m->m_len += (ip->ip_hl << 2);
526 m->m_data -= (ip->ip_hl << 2);
527 /* some debugging cruft by sklower, below, will go away soon */
528 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
529 register int plen = 0;
530 for (t = m; m; m = m->m_next)
531 plen += m->m_len;
532 t->m_pkthdr.len = plen;
533 }
534 return ((struct ip *)ip);
535
536 dropfrag:
537 ipstat.ips_fragdropped++;
538 m_freem(m);
539 return (0);
540 }
541
542 /*
543 * Free a fragment reassembly header and all
544 * associated datagrams.
545 */
546 void
547 ip_freef(fp)
548 struct ipq *fp;
549 {
550 register struct ipasfrag *q, *p;
551
552 for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
553 p = q->ipf_next;
554 ip_deq(q);
555 m_freem(dtom(q));
556 }
557 remque(fp);
558 (void) m_free(dtom(fp));
559 }
560
561 /*
562 * Put an ip fragment on a reassembly chain.
563 * Like insque, but pointers in middle of structure.
564 */
565 void
566 ip_enq(p, prev)
567 register struct ipasfrag *p, *prev;
568 {
569
570 p->ipf_prev = prev;
571 p->ipf_next = prev->ipf_next;
572 prev->ipf_next->ipf_prev = p;
573 prev->ipf_next = p;
574 }
575
576 /*
577 * To ip_enq as remque is to insque.
578 */
579 void
580 ip_deq(p)
581 register struct ipasfrag *p;
582 {
583
584 p->ipf_prev->ipf_next = p->ipf_next;
585 p->ipf_next->ipf_prev = p->ipf_prev;
586 }
587
588 /*
589 * IP timer processing;
590 * if a timer expires on a reassembly
591 * queue, discard it.
592 */
593 void
594 ip_slowtimo()
595 {
596 register struct ipq *fp;
597 int s = splnet();
598
599 fp = ipq.next;
600 if (fp == 0) {
601 splx(s);
602 return;
603 }
604 while (fp != &ipq) {
605 --fp->ipq_ttl;
606 fp = fp->next;
607 if (fp->prev->ipq_ttl == 0) {
608 ipstat.ips_fragtimeout++;
609 ip_freef(fp->prev);
610 }
611 }
612 splx(s);
613 }
614
615 /*
616 * Drain off all datagram fragments.
617 */
618 void
619 ip_drain()
620 {
621
622 while (ipq.next != &ipq) {
623 ipstat.ips_fragdropped++;
624 ip_freef(ipq.next);
625 }
626 }
627
628 /*
629 * Do option processing on a datagram,
630 * possibly discarding it if bad options are encountered,
631 * or forwarding it if source-routed.
632 * Returns 1 if packet has been forwarded/freed,
633 * 0 if the packet should be processed further.
634 */
635 int
636 ip_dooptions(m)
637 struct mbuf *m;
638 {
639 register struct ip *ip = mtod(m, struct ip *);
640 register u_char *cp;
641 register struct ip_timestamp *ipt;
642 register struct in_ifaddr *ia;
643 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
644 struct in_addr *sin, dst;
645 n_time ntime;
646
647 dst = ip->ip_dst;
648 cp = (u_char *)(ip + 1);
649 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
650 for (; cnt > 0; cnt -= optlen, cp += optlen) {
651 opt = cp[IPOPT_OPTVAL];
652 if (opt == IPOPT_EOL)
653 break;
654 if (opt == IPOPT_NOP)
655 optlen = 1;
656 else {
657 optlen = cp[IPOPT_OLEN];
658 if (optlen <= 0 || optlen > cnt) {
659 code = &cp[IPOPT_OLEN] - (u_char *)ip;
660 goto bad;
661 }
662 }
663 switch (opt) {
664
665 default:
666 break;
667
668 /*
669 * Source routing with record.
670 * Find interface with current destination address.
671 * If none on this machine then drop if strictly routed,
672 * or do nothing if loosely routed.
673 * Record interface address and bring up next address
674 * component. If strictly routed make sure next
675 * address is on directly accessible net.
676 */
677 case IPOPT_LSRR:
678 case IPOPT_SSRR:
679 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
680 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
681 goto bad;
682 }
683 ipaddr.sin_addr = ip->ip_dst;
684 ia = (struct in_ifaddr *)
685 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
686 if (ia == 0) {
687 if (opt == IPOPT_SSRR) {
688 type = ICMP_UNREACH;
689 code = ICMP_UNREACH_SRCFAIL;
690 goto bad;
691 }
692 /*
693 * Loose routing, and not at next destination
694 * yet; nothing to do except forward.
695 */
696 break;
697 }
698 off--; /* 0 origin */
699 if (off > optlen - sizeof(struct in_addr)) {
700 /*
701 * End of source route. Should be for us.
702 */
703 save_rte(cp, ip->ip_src);
704 break;
705 }
706 /*
707 * locate outgoing interface
708 */
709 bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
710 sizeof(ipaddr.sin_addr));
711 if (opt == IPOPT_SSRR) {
712 #define INA struct in_ifaddr *
713 #define SA struct sockaddr *
714 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
715 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
716 } else
717 ia = ip_rtaddr(ipaddr.sin_addr);
718 if (ia == 0) {
719 type = ICMP_UNREACH;
720 code = ICMP_UNREACH_SRCFAIL;
721 goto bad;
722 }
723 ip->ip_dst = ipaddr.sin_addr;
724 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
725 (caddr_t)(cp + off), sizeof(struct in_addr));
726 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
727 /*
728 * Let ip_intr's mcast routing check handle mcast pkts
729 */
730 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
731 break;
732
733 case IPOPT_RR:
734 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
735 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
736 goto bad;
737 }
738 /*
739 * If no space remains, ignore.
740 */
741 off--; /* 0 origin */
742 if (off > optlen - sizeof(struct in_addr))
743 break;
744 bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
745 sizeof(ipaddr.sin_addr));
746 /*
747 * locate outgoing interface; if we're the destination,
748 * use the incoming interface (should be same).
749 */
750 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
751 (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
752 type = ICMP_UNREACH;
753 code = ICMP_UNREACH_HOST;
754 goto bad;
755 }
756 bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
757 (caddr_t)(cp + off), sizeof(struct in_addr));
758 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
759 break;
760
761 case IPOPT_TS:
762 code = cp - (u_char *)ip;
763 ipt = (struct ip_timestamp *)cp;
764 if (ipt->ipt_len < 5)
765 goto bad;
766 if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
767 if (++ipt->ipt_oflw == 0)
768 goto bad;
769 break;
770 }
771 sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
772 switch (ipt->ipt_flg) {
773
774 case IPOPT_TS_TSONLY:
775 break;
776
777 case IPOPT_TS_TSANDADDR:
778 if (ipt->ipt_ptr + sizeof(n_time) +
779 sizeof(struct in_addr) > ipt->ipt_len)
780 goto bad;
781 ipaddr.sin_addr = dst;
782 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
783 m->m_pkthdr.rcvif);
784 if (ia == 0)
785 continue;
786 bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
787 (caddr_t)sin, sizeof(struct in_addr));
788 ipt->ipt_ptr += sizeof(struct in_addr);
789 break;
790
791 case IPOPT_TS_PRESPEC:
792 if (ipt->ipt_ptr + sizeof(n_time) +
793 sizeof(struct in_addr) > ipt->ipt_len)
794 goto bad;
795 bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
796 sizeof(struct in_addr));
797 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
798 continue;
799 ipt->ipt_ptr += sizeof(struct in_addr);
800 break;
801
802 default:
803 goto bad;
804 }
805 ntime = iptime();
806 bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
807 sizeof(n_time));
808 ipt->ipt_ptr += sizeof(n_time);
809 }
810 }
811 if (forward) {
812 ip_forward(m, 1);
813 return (1);
814 }
815 return (0);
816 bad:
817 ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */
818 icmp_error(m, type, code, 0, 0);
819 ipstat.ips_badoptions++;
820 return (1);
821 }
822
823 /*
824 * Given address of next destination (final or next hop),
825 * return internet address info of interface to be used to get there.
826 */
827 struct in_ifaddr *
828 ip_rtaddr(dst)
829 struct in_addr dst;
830 {
831 register struct sockaddr_in *sin;
832
833 sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
834
835 if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
836 if (ipforward_rt.ro_rt) {
837 RTFREE(ipforward_rt.ro_rt);
838 ipforward_rt.ro_rt = 0;
839 }
840 sin->sin_family = AF_INET;
841 sin->sin_len = sizeof(*sin);
842 sin->sin_addr = dst;
843
844 rtalloc(&ipforward_rt);
845 }
846 if (ipforward_rt.ro_rt == 0)
847 return ((struct in_ifaddr *)0);
848 return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
849 }
850
851 /*
852 * Save incoming source route for use in replies,
853 * to be picked up later by ip_srcroute if the receiver is interested.
854 */
855 void
856 save_rte(option, dst)
857 u_char *option;
858 struct in_addr dst;
859 {
860 unsigned olen;
861
862 olen = option[IPOPT_OLEN];
863 #ifdef DIAGNOSTIC
864 if (ipprintfs)
865 printf("save_rte: olen %d\n", olen);
866 #endif
867 if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
868 return;
869 bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
870 ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
871 ip_srcrt.dst = dst;
872 }
873
874 /*
875 * Retrieve incoming source route for use in replies,
876 * in the same form used by setsockopt.
877 * The first hop is placed before the options, will be removed later.
878 */
879 struct mbuf *
880 ip_srcroute()
881 {
882 register struct in_addr *p, *q;
883 register struct mbuf *m;
884
885 if (ip_nhops == 0)
886 return ((struct mbuf *)0);
887 m = m_get(M_DONTWAIT, MT_SOOPTS);
888 if (m == 0)
889 return ((struct mbuf *)0);
890
891 #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
892
893 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
894 m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
895 OPTSIZ;
896 #ifdef DIAGNOSTIC
897 if (ipprintfs)
898 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
899 #endif
900
901 /*
902 * First save first hop for return route
903 */
904 p = &ip_srcrt.route[ip_nhops - 1];
905 *(mtod(m, struct in_addr *)) = *p--;
906 #ifdef DIAGNOSTIC
907 if (ipprintfs)
908 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
909 #endif
910
911 /*
912 * Copy option fields and padding (nop) to mbuf.
913 */
914 ip_srcrt.nop = IPOPT_NOP;
915 ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
916 bcopy((caddr_t)&ip_srcrt.nop,
917 mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
918 q = (struct in_addr *)(mtod(m, caddr_t) +
919 sizeof(struct in_addr) + OPTSIZ);
920 #undef OPTSIZ
921 /*
922 * Record return path as an IP source route,
923 * reversing the path (pointers are now aligned).
924 */
925 while (p >= ip_srcrt.route) {
926 #ifdef DIAGNOSTIC
927 if (ipprintfs)
928 printf(" %lx", ntohl(q->s_addr));
929 #endif
930 *q++ = *p--;
931 }
932 /*
933 * Last hop goes to final destination.
934 */
935 *q = ip_srcrt.dst;
936 #ifdef DIAGNOSTIC
937 if (ipprintfs)
938 printf(" %lx\n", ntohl(q->s_addr));
939 #endif
940 return (m);
941 }
942
943 /*
944 * Strip out IP options, at higher
945 * level protocol in the kernel.
946 * Second argument is buffer to which options
947 * will be moved, and return value is their length.
948 * XXX should be deleted; last arg currently ignored.
949 */
950 void
951 ip_stripoptions(m, mopt)
952 register struct mbuf *m;
953 struct mbuf *mopt;
954 {
955 register int i;
956 struct ip *ip = mtod(m, struct ip *);
957 register caddr_t opts;
958 int olen;
959
960 olen = (ip->ip_hl<<2) - sizeof (struct ip);
961 opts = (caddr_t)(ip + 1);
962 i = m->m_len - (sizeof (struct ip) + olen);
963 bcopy(opts + olen, opts, (unsigned)i);
964 m->m_len -= olen;
965 if (m->m_flags & M_PKTHDR)
966 m->m_pkthdr.len -= olen;
967 ip->ip_hl = sizeof(struct ip) >> 2;
968 }
969
970 u_char inetctlerrmap[PRC_NCMDS] = {
971 0, 0, 0, 0,
972 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
973 EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
974 EMSGSIZE, EHOSTUNREACH, 0, 0,
975 0, 0, 0, 0,
976 ENOPROTOOPT
977 };
978
979 /*
980 * Forward a packet. If some error occurs return the sender
981 * an icmp packet. Note we can't always generate a meaningful
982 * icmp message because icmp doesn't have a large enough repertoire
983 * of codes and types.
984 *
985 * If not forwarding, just drop the packet. This could be confusing
986 * if ipforwarding was zero but some routing protocol was advancing
987 * us as a gateway to somewhere. However, we must let the routing
988 * protocol deal with that.
989 *
990 * The srcrt parameter indicates whether the packet is being forwarded
991 * via a source route.
992 */
993 void
994 ip_forward(m, srcrt)
995 struct mbuf *m;
996 int srcrt;
997 {
998 register struct ip *ip = mtod(m, struct ip *);
999 register struct sockaddr_in *sin;
1000 register struct rtentry *rt;
1001 int error, type = 0, code;
1002 struct mbuf *mcopy;
1003 n_long dest;
1004 struct ifnet *destifp;
1005
1006 dest = 0;
1007 #ifdef DIAGNOSTIC
1008 if (ipprintfs)
1009 printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
1010 ip->ip_dst, ip->ip_ttl);
1011 #endif
1012 if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
1013 ipstat.ips_cantforward++;
1014 m_freem(m);
1015 return;
1016 }
1017 HTONS(ip->ip_id);
1018 if (ip->ip_ttl <= IPTTLDEC) {
1019 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1020 return;
1021 }
1022 ip->ip_ttl -= IPTTLDEC;
1023
1024 sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1025 if ((rt = ipforward_rt.ro_rt) == 0 ||
1026 ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
1027 if (ipforward_rt.ro_rt) {
1028 RTFREE(ipforward_rt.ro_rt);
1029 ipforward_rt.ro_rt = 0;
1030 }
1031 sin->sin_family = AF_INET;
1032 sin->sin_len = sizeof(*sin);
1033 sin->sin_addr = ip->ip_dst;
1034
1035 rtalloc(&ipforward_rt);
1036 if (ipforward_rt.ro_rt == 0) {
1037 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1038 return;
1039 }
1040 rt = ipforward_rt.ro_rt;
1041 }
1042
1043 /*
1044 * Save at most 64 bytes of the packet in case
1045 * we need to generate an ICMP message to the src.
1046 */
1047 mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
1048
1049 #ifdef GATEWAY
1050 ip_ifmatrix[rt->rt_ifp->if_index +
1051 if_index * m->m_pkthdr.rcvif->if_index]++;
1052 #endif
1053 /*
1054 * If forwarding packet using same interface that it came in on,
1055 * perhaps should send a redirect to sender to shortcut a hop.
1056 * Only send redirect if source is sending directly to us,
1057 * and if packet was not source routed (or has any options).
1058 * Also, don't send redirect if forwarding using a default route
1059 * or a route modified by a redirect.
1060 */
1061 #define satosin(sa) ((struct sockaddr_in *)(sa))
1062 if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1063 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1064 satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1065 ipsendredirects && !srcrt) {
1066 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1067 u_long src = ntohl(ip->ip_src.s_addr);
1068
1069 if (RTA(rt) &&
1070 (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1071 if (rt->rt_flags & RTF_GATEWAY)
1072 dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1073 else
1074 dest = ip->ip_dst.s_addr;
1075 /* Router requirements says to only send host redirects */
1076 type = ICMP_REDIRECT;
1077 code = ICMP_REDIRECT_HOST;
1078 #ifdef DIAGNOSTIC
1079 if (ipprintfs)
1080 printf("redirect (%d) to %lx\n", code, (u_long)dest);
1081 #endif
1082 }
1083 }
1084
1085 error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING
1086 #ifdef DIRECTED_BROADCAST
1087 | IP_ALLOWBROADCAST
1088 #endif
1089 , 0);
1090 if (error)
1091 ipstat.ips_cantforward++;
1092 else {
1093 ipstat.ips_forward++;
1094 if (type)
1095 ipstat.ips_redirectsent++;
1096 else {
1097 if (mcopy)
1098 m_freem(mcopy);
1099 return;
1100 }
1101 }
1102 if (mcopy == NULL)
1103 return;
1104 destifp = NULL;
1105
1106 switch (error) {
1107
1108 case 0: /* forwarded, but need redirect */
1109 /* type, code set above */
1110 break;
1111
1112 case ENETUNREACH: /* shouldn't happen, checked above */
1113 case EHOSTUNREACH:
1114 case ENETDOWN:
1115 case EHOSTDOWN:
1116 default:
1117 type = ICMP_UNREACH;
1118 code = ICMP_UNREACH_HOST;
1119 break;
1120
1121 case EMSGSIZE:
1122 type = ICMP_UNREACH;
1123 code = ICMP_UNREACH_NEEDFRAG;
1124 if (ipforward_rt.ro_rt)
1125 destifp = ipforward_rt.ro_rt->rt_ifp;
1126 ipstat.ips_cantfrag++;
1127 break;
1128
1129 case ENOBUFS:
1130 type = ICMP_SOURCEQUENCH;
1131 code = 0;
1132 break;
1133 }
1134 icmp_error(mcopy, type, code, dest, destifp);
1135 }
1136
1137 int
1138 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
1139 int *name;
1140 u_int namelen;
1141 void *oldp;
1142 size_t *oldlenp;
1143 void *newp;
1144 size_t newlen;
1145 {
1146 /* All sysctl names at this level are terminal. */
1147 if (namelen != 1)
1148 return (ENOTDIR);
1149
1150 switch (name[0]) {
1151 case IPCTL_FORWARDING:
1152 return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
1153 case IPCTL_SENDREDIRECTS:
1154 return (sysctl_int(oldp, oldlenp, newp, newlen,
1155 &ipsendredirects));
1156 case IPCTL_DEFTTL:
1157 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
1158 #ifdef notyet
1159 case IPCTL_DEFMTU:
1160 return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
1161 #endif
1162 default:
1163 return (EOPNOTSUPP);
1164 }
1165 /* NOTREACHED */
1166 }
1167