ip_input.c revision 12296
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 * $Id: ip_input.c,v 1.27 1995/11/01 17:18:27 wollman Exp $
35 */
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/malloc.h>
40#include <sys/mbuf.h>
41#include <sys/domain.h>
42#include <sys/protosw.h>
43#include <sys/socket.h>
44#include <sys/errno.h>
45#include <sys/time.h>
46#include <sys/kernel.h>
47#include <sys/syslog.h>
48
49#include <vm/vm.h>
50#include <sys/sysctl.h>
51
52#include <net/if.h>
53#include <net/route.h>
54#include <net/netisr.h>
55
56#include <netinet/in.h>
57#include <netinet/in_systm.h>
58#include <netinet/in_var.h>
59#include <netinet/ip.h>
60#include <netinet/in_pcb.h>
61#include <netinet/in_var.h>
62#include <netinet/ip_var.h>
63#include <netinet/ip_icmp.h>
64
65#include <netinet/ip_fw.h>
66
67#include <sys/socketvar.h>
68int rsvp_on = 0;
69int ip_rsvp_on;
70struct socket *ip_rsvpd;
71
72#ifndef	IPFORWARDING
73#ifdef GATEWAY
74#define	IPFORWARDING	1	/* forward IP packets not for us */
75#else /* GATEWAY */
76#define	IPFORWARDING	0	/* don't forward IP packets not for us */
77#endif /* GATEWAY */
78#endif /* IPFORWARDING */
79#ifndef	IPSENDREDIRECTS
80#define	IPSENDREDIRECTS	1
81#endif
82#ifndef	DIRECTED_BROADCAST
83#define	DIRECTED_BROADCAST	0
84#endif
85
86static int	ipforwarding = IPFORWARDING;
87SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
88	&ipforwarding, 0, "");
89
90static int	ipsendredirects = IPSENDREDIRECTS;
91SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
92	&ipsendredirects, 0, "");
93
94static int	ipdirbroadcast = DIRECTED_BROADCAST;
95SYSCTL_INT(_net_inet_ip, IPCTL_DIRECTEDBROADCAST, directed_broadcast,
96	CTLFLAG_RW, &ipdirbroadcast, 0, "");
97
98int	ip_defttl = IPDEFTTL;
99SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
100	&ip_defttl, 0, "");
101
102static int	ip_dosourceroute = 0;
103SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
104	&ip_dosourceroute, 0, "");
105#ifdef DIAGNOSTIC
106static int	ipprintfs = 0;
107#endif
108
109extern	struct domain inetdomain;
110extern	struct protosw inetsw[];
111u_char	ip_protox[IPPROTO_MAX];
112static int	ipqmaxlen = IFQ_MAXLEN;
113struct	in_ifaddr *in_ifaddr;			/* first inet address */
114struct	ifqueue ipintrq;
115SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RD,
116	&ipintrq.ifq_maxlen, 0, "");
117SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
118	&ipintrq.ifq_drops, 0, "");
119
120struct ipstat ipstat;
121struct ipq ipq;
122
123#ifdef IPCTL_DEFMTU
124SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
125	&ip_mtu, 0, "");
126#endif
127
128/*
129 * We need to save the IP options in case a protocol wants to respond
130 * to an incoming packet over the same route if the packet got here
131 * using IP source routing.  This allows connection establishment and
132 * maintenance when the remote end is on a network that is not known
133 * to us.
134 */
135static int	ip_nhops = 0;
136static	struct ip_srcrt {
137	struct	in_addr dst;			/* final destination */
138	char	nop;				/* one NOP to align */
139	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
140	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
141} ip_srcrt;
142
143static void save_rte __P((u_char *, struct in_addr));
144static void	 ip_deq __P((struct ipasfrag *));
145static int	 ip_dooptions __P((struct mbuf *));
146static void	 ip_enq __P((struct ipasfrag *, struct ipasfrag *));
147static void	 ip_forward __P((struct mbuf *, int));
148static void	 ip_freef __P((struct ipq *));
149static struct ip *
150	 ip_reass __P((struct ipasfrag *, struct ipq *));
151static struct in_ifaddr *
152	 ip_rtaddr __P((struct in_addr));
153static void	 ipintr __P((void));
154/*
155 * IP initialization: fill in IP protocol switch table.
156 * All protocols not implemented in kernel go to raw IP protocol handler.
157 */
158void
159ip_init()
160{
161	register struct protosw *pr;
162	register int i;
163
164	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
165	if (pr == 0)
166		panic("ip_init");
167	for (i = 0; i < IPPROTO_MAX; i++)
168		ip_protox[i] = pr - inetsw;
169	for (pr = inetdomain.dom_protosw;
170	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
171		if (pr->pr_domain->dom_family == PF_INET &&
172		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
173			ip_protox[pr->pr_protocol] = pr - inetsw;
174	ipq.next = ipq.prev = &ipq;
175	ip_id = time.tv_sec & 0xffff;
176	ipintrq.ifq_maxlen = ipqmaxlen;
177}
178
179static struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
180struct	route ipforward_rt;
181
182/*
183 * Ip input routine.  Checksum and byte swap header.  If fragmented
184 * try to reassemble.  Process options.  Pass to next level.
185 */
186static void
187ipintr(void)
188{
189	register struct ip *ip;
190	register struct mbuf *m;
191	register struct ipq *fp;
192	register struct in_ifaddr *ia;
193	int hlen, s;
194
195next:
196	/*
197	 * Get next datagram off input queue and get IP header
198	 * in first mbuf.
199	 */
200	s = splimp();
201	IF_DEQUEUE(&ipintrq, m);
202	splx(s);
203	if (m == 0)
204		return;
205#ifdef	DIAGNOSTIC
206	if ((m->m_flags & M_PKTHDR) == 0)
207		panic("ipintr no HDR");
208#endif
209	/*
210	 * If no IP addresses have been set yet but the interfaces
211	 * are receiving, can't do anything with incoming packets yet.
212	 */
213	if (in_ifaddr == NULL)
214		goto bad;
215	ipstat.ips_total++;
216	if (m->m_len < sizeof (struct ip) &&
217	    (m = m_pullup(m, sizeof (struct ip))) == 0) {
218		ipstat.ips_toosmall++;
219		goto next;
220	}
221	ip = mtod(m, struct ip *);
222	if (ip->ip_v != IPVERSION) {
223		ipstat.ips_badvers++;
224		goto bad;
225	}
226	hlen = ip->ip_hl << 2;
227	if (hlen < sizeof(struct ip)) {	/* minimum header length */
228		ipstat.ips_badhlen++;
229		goto bad;
230	}
231	if (hlen > m->m_len) {
232		if ((m = m_pullup(m, hlen)) == 0) {
233			ipstat.ips_badhlen++;
234			goto next;
235		}
236		ip = mtod(m, struct ip *);
237	}
238	ip->ip_sum = in_cksum(m, hlen);
239	if (ip->ip_sum) {
240		ipstat.ips_badsum++;
241		goto bad;
242	}
243
244	/*
245	 * Convert fields to host representation.
246	 */
247	NTOHS(ip->ip_len);
248	if (ip->ip_len < hlen) {
249		ipstat.ips_badlen++;
250		goto bad;
251	}
252	NTOHS(ip->ip_id);
253	NTOHS(ip->ip_off);
254
255	/*
256	 * Check that the amount of data in the buffers
257	 * is as at least much as the IP header would have us expect.
258	 * Trim mbufs if longer than we expect.
259	 * Drop packet if shorter than we expect.
260	 */
261	if (m->m_pkthdr.len < ip->ip_len) {
262		ipstat.ips_tooshort++;
263		goto bad;
264	}
265	if (m->m_pkthdr.len > ip->ip_len) {
266		if (m->m_len == m->m_pkthdr.len) {
267			m->m_len = ip->ip_len;
268			m->m_pkthdr.len = ip->ip_len;
269		} else
270			m_adj(m, ip->ip_len - m->m_pkthdr.len);
271	}
272	/*
273	 * IpHack's section.
274	 * Right now when no processing on packet has done
275	 * and it is still fresh out of network we do our black
276	 * deals with it.
277	 * - Firewall: deny/allow
278	 * - Wrap: fake packet's addr/port <unimpl.>
279	 * - Encapsulate: put it in another IP and send out. <unimp.>
280 	 */
281
282        if (ip_fw_chk_ptr!=NULL)
283               if (!(*ip_fw_chk_ptr)(m,ip,m->m_pkthdr.rcvif,ip_fw_chain) ) {
284                       goto next;
285               }
286
287	/*
288	 * Process options and, if not destined for us,
289	 * ship it on.  ip_dooptions returns 1 when an
290	 * error was detected (causing an icmp message
291	 * to be sent and the original packet to be freed).
292	 */
293	ip_nhops = 0;		/* for source routed packets */
294	if (hlen > sizeof (struct ip) && ip_dooptions(m))
295		goto next;
296
297        /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
298         * matter if it is destined to another node, or whether it is
299         * a multicast one, RSVP wants it! and prevents it from being forwarded
300         * anywhere else. Also checks if the rsvp daemon is running before
301	 * grabbing the packet.
302         */
303	if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
304		goto ours;
305
306	/*
307	 * Check our list of addresses, to see if the packet is for us.
308	 */
309	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
310#define	satosin(sa)	((struct sockaddr_in *)(sa))
311
312		if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
313			goto ours;
314		if ((!ipdirbroadcast || ia->ia_ifp == m->m_pkthdr.rcvif) &&
315		    (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
316			u_long t;
317
318			if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
319			    ip->ip_dst.s_addr)
320				goto ours;
321			if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
322				goto ours;
323			/*
324			 * Look for all-0's host part (old broadcast addr),
325			 * either for subnet or net.
326			 */
327			t = ntohl(ip->ip_dst.s_addr);
328			if (t == ia->ia_subnet)
329				goto ours;
330			if (t == ia->ia_net)
331				goto ours;
332		}
333	}
334	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
335		struct in_multi *inm;
336		if (ip_mrouter) {
337			/*
338			 * If we are acting as a multicast router, all
339			 * incoming multicast packets are passed to the
340			 * kernel-level multicast forwarding function.
341			 * The packet is returned (relatively) intact; if
342			 * ip_mforward() returns a non-zero value, the packet
343			 * must be discarded, else it may be accepted below.
344			 *
345			 * (The IP ident field is put in the same byte order
346			 * as expected when ip_mforward() is called from
347			 * ip_output().)
348			 */
349			ip->ip_id = htons(ip->ip_id);
350			if (ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
351				ipstat.ips_cantforward++;
352				m_freem(m);
353				goto next;
354			}
355			ip->ip_id = ntohs(ip->ip_id);
356
357			/*
358			 * The process-level routing demon needs to receive
359			 * all multicast IGMP packets, whether or not this
360			 * host belongs to their destination groups.
361			 */
362			if (ip->ip_p == IPPROTO_IGMP)
363				goto ours;
364			ipstat.ips_forward++;
365		}
366		/*
367		 * See if we belong to the destination multicast group on the
368		 * arrival interface.
369		 */
370		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
371		if (inm == NULL) {
372			ipstat.ips_cantforward++;
373			m_freem(m);
374			goto next;
375		}
376		goto ours;
377	}
378	if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
379		goto ours;
380	if (ip->ip_dst.s_addr == INADDR_ANY)
381		goto ours;
382
383	/*
384	 * Not for us; forward if possible and desirable.
385	 */
386	if (ipforwarding == 0) {
387		ipstat.ips_cantforward++;
388		m_freem(m);
389	} else
390		ip_forward(m, 0);
391	goto next;
392
393ours:
394
395		/*
396		 * If packet came to us we count it...
397		 * This way we count all incoming packets which has
398		 * not been forwarded...
399		 * Do not convert ip_len to host byte order when
400		 * counting,ppl already made it for us before..
401		 */
402	if (ip_acct_cnt_ptr!=NULL)
403		(*ip_acct_cnt_ptr)(ip,m->m_pkthdr.rcvif,ip_acct_chain,0);
404
405	/*
406	 * If offset or IP_MF are set, must reassemble.
407	 * Otherwise, nothing need be done.
408	 * (We could look in the reassembly queue to see
409	 * if the packet was previously fragmented,
410	 * but it's not worth the time; just let them time out.)
411	 */
412	if (ip->ip_off &~ IP_DF) {
413		if (m->m_flags & M_EXT) {		/* XXX */
414			if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
415				ipstat.ips_toosmall++;
416				goto next;
417			}
418			ip = mtod(m, struct ip *);
419		}
420		/*
421		 * Look for queue of fragments
422		 * of this datagram.
423		 */
424		for (fp = ipq.next; fp != &ipq; fp = fp->next)
425			if (ip->ip_id == fp->ipq_id &&
426			    ip->ip_src.s_addr == fp->ipq_src.s_addr &&
427			    ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
428			    ip->ip_p == fp->ipq_p)
429				goto found;
430		fp = 0;
431found:
432
433		/*
434		 * Adjust ip_len to not reflect header,
435		 * set ip_mff if more fragments are expected,
436		 * convert offset of this to bytes.
437		 */
438		ip->ip_len -= hlen;
439		((struct ipasfrag *)ip)->ipf_mff &= ~1;
440		if (ip->ip_off & IP_MF)
441			((struct ipasfrag *)ip)->ipf_mff |= 1;
442		ip->ip_off <<= 3;
443
444		/*
445		 * If datagram marked as having more fragments
446		 * or if this is not the first fragment,
447		 * attempt reassembly; if it succeeds, proceed.
448		 */
449		if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) {
450			ipstat.ips_fragments++;
451			ip = ip_reass((struct ipasfrag *)ip, fp);
452			if (ip == 0)
453				goto next;
454			ipstat.ips_reassembled++;
455			m = dtom(ip);
456		} else
457			if (fp)
458				ip_freef(fp);
459	} else
460		ip->ip_len -= hlen;
461
462	/*
463	 * Switch out to protocol's input routine.
464	 */
465	ipstat.ips_delivered++;
466	(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
467	goto next;
468bad:
469	m_freem(m);
470	goto next;
471}
472
473NETISR_SET(NETISR_IP, ipintr);
474
475/*
476 * Take incoming datagram fragment and try to
477 * reassemble it into whole datagram.  If a chain for
478 * reassembly of this datagram already exists, then it
479 * is given as fp; otherwise have to make a chain.
480 */
481static struct ip *
482ip_reass(ip, fp)
483	register struct ipasfrag *ip;
484	register struct ipq *fp;
485{
486	register struct mbuf *m = dtom(ip);
487	register struct ipasfrag *q;
488	struct mbuf *t;
489	int hlen = ip->ip_hl << 2;
490	int i, next;
491
492	/*
493	 * Presence of header sizes in mbufs
494	 * would confuse code below.
495	 */
496	m->m_data += hlen;
497	m->m_len -= hlen;
498
499	/*
500	 * If first fragment to arrive, create a reassembly queue.
501	 */
502	if (fp == 0) {
503		if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
504			goto dropfrag;
505		fp = mtod(t, struct ipq *);
506		insque(fp, &ipq);
507		fp->ipq_ttl = IPFRAGTTL;
508		fp->ipq_p = ip->ip_p;
509		fp->ipq_id = ip->ip_id;
510		fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
511		fp->ipq_src = ((struct ip *)ip)->ip_src;
512		fp->ipq_dst = ((struct ip *)ip)->ip_dst;
513		q = (struct ipasfrag *)fp;
514		goto insert;
515	}
516
517	/*
518	 * Find a segment which begins after this one does.
519	 */
520	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
521		if (q->ip_off > ip->ip_off)
522			break;
523
524	/*
525	 * If there is a preceding segment, it may provide some of
526	 * our data already.  If so, drop the data from the incoming
527	 * segment.  If it provides all of our data, drop us.
528	 */
529	if (q->ipf_prev != (struct ipasfrag *)fp) {
530		i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
531		if (i > 0) {
532			if (i >= ip->ip_len)
533				goto dropfrag;
534			m_adj(dtom(ip), i);
535			ip->ip_off += i;
536			ip->ip_len -= i;
537		}
538	}
539
540	/*
541	 * While we overlap succeeding segments trim them or,
542	 * if they are completely covered, dequeue them.
543	 */
544	while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
545		i = (ip->ip_off + ip->ip_len) - q->ip_off;
546		if (i < q->ip_len) {
547			q->ip_len -= i;
548			q->ip_off += i;
549			m_adj(dtom(q), i);
550			break;
551		}
552		q = q->ipf_next;
553		m_freem(dtom(q->ipf_prev));
554		ip_deq(q->ipf_prev);
555	}
556
557insert:
558	/*
559	 * Stick new segment in its place;
560	 * check for complete reassembly.
561	 */
562	ip_enq(ip, q->ipf_prev);
563	next = 0;
564	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
565		if (q->ip_off != next)
566			return (0);
567		next += q->ip_len;
568	}
569	if (q->ipf_prev->ipf_mff & 1)
570		return (0);
571
572	/*
573	 * Reassembly is complete; concatenate fragments.
574	 */
575	q = fp->ipq_next;
576	m = dtom(q);
577	t = m->m_next;
578	m->m_next = 0;
579	m_cat(m, t);
580	q = q->ipf_next;
581	while (q != (struct ipasfrag *)fp) {
582		t = dtom(q);
583		q = q->ipf_next;
584		m_cat(m, t);
585	}
586
587	/*
588	 * Create header for new ip packet by
589	 * modifying header of first packet;
590	 * dequeue and discard fragment reassembly header.
591	 * Make header visible.
592	 */
593	ip = fp->ipq_next;
594	ip->ip_len = next;
595	ip->ipf_mff &= ~1;
596	((struct ip *)ip)->ip_src = fp->ipq_src;
597	((struct ip *)ip)->ip_dst = fp->ipq_dst;
598	remque(fp);
599	(void) m_free(dtom(fp));
600	m = dtom(ip);
601	m->m_len += (ip->ip_hl << 2);
602	m->m_data -= (ip->ip_hl << 2);
603	/* some debugging cruft by sklower, below, will go away soon */
604	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
605		register int plen = 0;
606		for (t = m; m; m = m->m_next)
607			plen += m->m_len;
608		t->m_pkthdr.len = plen;
609	}
610	return ((struct ip *)ip);
611
612dropfrag:
613	ipstat.ips_fragdropped++;
614	m_freem(m);
615	return (0);
616}
617
618/*
619 * Free a fragment reassembly header and all
620 * associated datagrams.
621 */
622static void
623ip_freef(fp)
624	struct ipq *fp;
625{
626	register struct ipasfrag *q, *p;
627
628	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
629		p = q->ipf_next;
630		ip_deq(q);
631		m_freem(dtom(q));
632	}
633	remque(fp);
634	(void) m_free(dtom(fp));
635}
636
637/*
638 * Put an ip fragment on a reassembly chain.
639 * Like insque, but pointers in middle of structure.
640 */
641static void
642ip_enq(p, prev)
643	register struct ipasfrag *p, *prev;
644{
645
646	p->ipf_prev = prev;
647	p->ipf_next = prev->ipf_next;
648	prev->ipf_next->ipf_prev = p;
649	prev->ipf_next = p;
650}
651
652/*
653 * To ip_enq as remque is to insque.
654 */
655static void
656ip_deq(p)
657	register struct ipasfrag *p;
658{
659
660	p->ipf_prev->ipf_next = p->ipf_next;
661	p->ipf_next->ipf_prev = p->ipf_prev;
662}
663
664/*
665 * IP timer processing;
666 * if a timer expires on a reassembly
667 * queue, discard it.
668 */
669void
670ip_slowtimo()
671{
672	register struct ipq *fp;
673	int s = splnet();
674
675	fp = ipq.next;
676	if (fp == 0) {
677		splx(s);
678		return;
679	}
680	while (fp != &ipq) {
681		--fp->ipq_ttl;
682		fp = fp->next;
683		if (fp->prev->ipq_ttl == 0) {
684			ipstat.ips_fragtimeout++;
685			ip_freef(fp->prev);
686		}
687	}
688	splx(s);
689}
690
691/*
692 * Drain off all datagram fragments.
693 */
694void
695ip_drain()
696{
697
698	while (ipq.next != &ipq) {
699		ipstat.ips_fragdropped++;
700		ip_freef(ipq.next);
701	}
702}
703
704/*
705 * Do option processing on a datagram,
706 * possibly discarding it if bad options are encountered,
707 * or forwarding it if source-routed.
708 * Returns 1 if packet has been forwarded/freed,
709 * 0 if the packet should be processed further.
710 */
711static int
712ip_dooptions(m)
713	struct mbuf *m;
714{
715	register struct ip *ip = mtod(m, struct ip *);
716	register u_char *cp;
717	register struct ip_timestamp *ipt;
718	register struct in_ifaddr *ia;
719	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
720	struct in_addr *sin, dst;
721	n_time ntime;
722
723	dst = ip->ip_dst;
724	cp = (u_char *)(ip + 1);
725	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
726	for (; cnt > 0; cnt -= optlen, cp += optlen) {
727		opt = cp[IPOPT_OPTVAL];
728		if (opt == IPOPT_EOL)
729			break;
730		if (opt == IPOPT_NOP)
731			optlen = 1;
732		else {
733			optlen = cp[IPOPT_OLEN];
734			if (optlen <= 0 || optlen > cnt) {
735				code = &cp[IPOPT_OLEN] - (u_char *)ip;
736				goto bad;
737			}
738		}
739		switch (opt) {
740
741		default:
742			break;
743
744		/*
745		 * Source routing with record.
746		 * Find interface with current destination address.
747		 * If none on this machine then drop if strictly routed,
748		 * or do nothing if loosely routed.
749		 * Record interface address and bring up next address
750		 * component.  If strictly routed make sure next
751		 * address is on directly accessible net.
752		 */
753		case IPOPT_LSRR:
754		case IPOPT_SSRR:
755			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
756				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
757				goto bad;
758			}
759			ipaddr.sin_addr = ip->ip_dst;
760			ia = (struct in_ifaddr *)
761				ifa_ifwithaddr((struct sockaddr *)&ipaddr);
762			if (ia == 0) {
763				if (opt == IPOPT_SSRR) {
764					type = ICMP_UNREACH;
765					code = ICMP_UNREACH_SRCFAIL;
766					goto bad;
767				}
768				/*
769				 * Loose routing, and not at next destination
770				 * yet; nothing to do except forward.
771				 */
772				break;
773			}
774			off--;			/* 0 origin */
775			if (off > optlen - sizeof(struct in_addr)) {
776				/*
777				 * End of source route.  Should be for us.
778				 */
779				save_rte(cp, ip->ip_src);
780				break;
781			}
782
783			if (!ip_dosourceroute) {
784				char buf[4*sizeof "123"];
785				strcpy(buf, inet_ntoa(ip->ip_dst));
786
787				log(LOG_WARNING,
788				    "attempted source route from %s to %s\n",
789				    inet_ntoa(ip->ip_src), buf);
790				type = ICMP_UNREACH;
791				code = ICMP_UNREACH_SRCFAIL;
792				goto bad;
793			}
794
795			/*
796			 * locate outgoing interface
797			 */
798			(void)memcpy(&ipaddr.sin_addr, cp + off,
799			    sizeof(ipaddr.sin_addr));
800
801			if (opt == IPOPT_SSRR) {
802#define	INA	struct in_ifaddr *
803#define	SA	struct sockaddr *
804			    if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
805				ia = (INA)ifa_ifwithnet((SA)&ipaddr);
806			} else
807				ia = ip_rtaddr(ipaddr.sin_addr);
808			if (ia == 0) {
809				type = ICMP_UNREACH;
810				code = ICMP_UNREACH_SRCFAIL;
811				goto bad;
812			}
813			ip->ip_dst = ipaddr.sin_addr;
814			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
815			    sizeof(struct in_addr));
816			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
817			/*
818			 * Let ip_intr's mcast routing check handle mcast pkts
819			 */
820			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
821			break;
822
823		case IPOPT_RR:
824			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
825				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
826				goto bad;
827			}
828			/*
829			 * If no space remains, ignore.
830			 */
831			off--;			/* 0 origin */
832			if (off > optlen - sizeof(struct in_addr))
833				break;
834			(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
835			    sizeof(ipaddr.sin_addr));
836			/*
837			 * locate outgoing interface; if we're the destination,
838			 * use the incoming interface (should be same).
839			 */
840			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
841			    (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
842				type = ICMP_UNREACH;
843				code = ICMP_UNREACH_HOST;
844				goto bad;
845			}
846			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
847			    sizeof(struct in_addr));
848			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
849			break;
850
851		case IPOPT_TS:
852			code = cp - (u_char *)ip;
853			ipt = (struct ip_timestamp *)cp;
854			if (ipt->ipt_len < 5)
855				goto bad;
856			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
857				if (++ipt->ipt_oflw == 0)
858					goto bad;
859				break;
860			}
861			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
862			switch (ipt->ipt_flg) {
863
864			case IPOPT_TS_TSONLY:
865				break;
866
867			case IPOPT_TS_TSANDADDR:
868				if (ipt->ipt_ptr + sizeof(n_time) +
869				    sizeof(struct in_addr) > ipt->ipt_len)
870					goto bad;
871				ipaddr.sin_addr = dst;
872				ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
873							    m->m_pkthdr.rcvif);
874				if (ia == 0)
875					continue;
876				(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
877				    sizeof(struct in_addr));
878				ipt->ipt_ptr += sizeof(struct in_addr);
879				break;
880
881			case IPOPT_TS_PRESPEC:
882				if (ipt->ipt_ptr + sizeof(n_time) +
883				    sizeof(struct in_addr) > ipt->ipt_len)
884					goto bad;
885				(void)memcpy(&ipaddr.sin_addr, sin,
886				    sizeof(struct in_addr));
887				if (ifa_ifwithaddr((SA)&ipaddr) == 0)
888					continue;
889				ipt->ipt_ptr += sizeof(struct in_addr);
890				break;
891
892			default:
893				goto bad;
894			}
895			ntime = iptime();
896			(void)memcpy(cp + ipt->ipt_ptr - 1, &ntime,
897			    sizeof(n_time));
898			ipt->ipt_ptr += sizeof(n_time);
899		}
900	}
901	if (forward) {
902		ip_forward(m, 1);
903		return (1);
904	}
905	return (0);
906bad:
907	ip->ip_len -= ip->ip_hl << 2;   /* XXX icmp_error adds in hdr length */
908	icmp_error(m, type, code, 0, 0);
909	ipstat.ips_badoptions++;
910	return (1);
911}
912
913/*
914 * Given address of next destination (final or next hop),
915 * return internet address info of interface to be used to get there.
916 */
917static struct in_ifaddr *
918ip_rtaddr(dst)
919	 struct in_addr dst;
920{
921	register struct sockaddr_in *sin;
922
923	sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
924
925	if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
926		if (ipforward_rt.ro_rt) {
927			RTFREE(ipforward_rt.ro_rt);
928			ipforward_rt.ro_rt = 0;
929		}
930		sin->sin_family = AF_INET;
931		sin->sin_len = sizeof(*sin);
932		sin->sin_addr = dst;
933
934		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
935	}
936	if (ipforward_rt.ro_rt == 0)
937		return ((struct in_ifaddr *)0);
938	return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
939}
940
941/*
942 * Save incoming source route for use in replies,
943 * to be picked up later by ip_srcroute if the receiver is interested.
944 */
945void
946save_rte(option, dst)
947	u_char *option;
948	struct in_addr dst;
949{
950	unsigned olen;
951
952	olen = option[IPOPT_OLEN];
953#ifdef DIAGNOSTIC
954	if (ipprintfs)
955		printf("save_rte: olen %d\n", olen);
956#endif
957	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
958		return;
959	(void)memcpy(ip_srcrt.srcopt, option, olen);
960	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
961	ip_srcrt.dst = dst;
962}
963
964/*
965 * Retrieve incoming source route for use in replies,
966 * in the same form used by setsockopt.
967 * The first hop is placed before the options, will be removed later.
968 */
969struct mbuf *
970ip_srcroute()
971{
972	register struct in_addr *p, *q;
973	register struct mbuf *m;
974
975	if (ip_nhops == 0)
976		return ((struct mbuf *)0);
977	m = m_get(M_DONTWAIT, MT_SOOPTS);
978	if (m == 0)
979		return ((struct mbuf *)0);
980
981#define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
982
983	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
984	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
985	    OPTSIZ;
986#ifdef DIAGNOSTIC
987	if (ipprintfs)
988		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
989#endif
990
991	/*
992	 * First save first hop for return route
993	 */
994	p = &ip_srcrt.route[ip_nhops - 1];
995	*(mtod(m, struct in_addr *)) = *p--;
996#ifdef DIAGNOSTIC
997	if (ipprintfs)
998		printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
999#endif
1000
1001	/*
1002	 * Copy option fields and padding (nop) to mbuf.
1003	 */
1004	ip_srcrt.nop = IPOPT_NOP;
1005	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1006	(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1007	    &ip_srcrt.nop, OPTSIZ);
1008	q = (struct in_addr *)(mtod(m, caddr_t) +
1009	    sizeof(struct in_addr) + OPTSIZ);
1010#undef OPTSIZ
1011	/*
1012	 * Record return path as an IP source route,
1013	 * reversing the path (pointers are now aligned).
1014	 */
1015	while (p >= ip_srcrt.route) {
1016#ifdef DIAGNOSTIC
1017		if (ipprintfs)
1018			printf(" %lx", ntohl(q->s_addr));
1019#endif
1020		*q++ = *p--;
1021	}
1022	/*
1023	 * Last hop goes to final destination.
1024	 */
1025	*q = ip_srcrt.dst;
1026#ifdef DIAGNOSTIC
1027	if (ipprintfs)
1028		printf(" %lx\n", ntohl(q->s_addr));
1029#endif
1030	return (m);
1031}
1032
1033/*
1034 * Strip out IP options, at higher
1035 * level protocol in the kernel.
1036 * Second argument is buffer to which options
1037 * will be moved, and return value is their length.
1038 * XXX should be deleted; last arg currently ignored.
1039 */
1040void
1041ip_stripoptions(m, mopt)
1042	register struct mbuf *m;
1043	struct mbuf *mopt;
1044{
1045	register int i;
1046	struct ip *ip = mtod(m, struct ip *);
1047	register caddr_t opts;
1048	int olen;
1049
1050	olen = (ip->ip_hl<<2) - sizeof (struct ip);
1051	opts = (caddr_t)(ip + 1);
1052	i = m->m_len - (sizeof (struct ip) + olen);
1053	bcopy(opts + olen, opts, (unsigned)i);
1054	m->m_len -= olen;
1055	if (m->m_flags & M_PKTHDR)
1056		m->m_pkthdr.len -= olen;
1057	ip->ip_hl = sizeof(struct ip) >> 2;
1058}
1059
1060u_char inetctlerrmap[PRC_NCMDS] = {
1061	0,		0,		0,		0,
1062	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
1063	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
1064	EMSGSIZE,	EHOSTUNREACH,	0,		0,
1065	0,		0,		0,		0,
1066	ENOPROTOOPT
1067};
1068
1069/*
1070 * Forward a packet.  If some error occurs return the sender
1071 * an icmp packet.  Note we can't always generate a meaningful
1072 * icmp message because icmp doesn't have a large enough repertoire
1073 * of codes and types.
1074 *
1075 * If not forwarding, just drop the packet.  This could be confusing
1076 * if ipforwarding was zero but some routing protocol was advancing
1077 * us as a gateway to somewhere.  However, we must let the routing
1078 * protocol deal with that.
1079 *
1080 * The srcrt parameter indicates whether the packet is being forwarded
1081 * via a source route.
1082 */
1083static void
1084ip_forward(m, srcrt)
1085	struct mbuf *m;
1086	int srcrt;
1087{
1088	register struct ip *ip = mtod(m, struct ip *);
1089	register struct sockaddr_in *sin;
1090	register struct rtentry *rt;
1091	int error, type = 0, code = 0;
1092	struct mbuf *mcopy;
1093	n_long dest;
1094	struct ifnet *destifp;
1095
1096	dest = 0;
1097#ifdef DIAGNOSTIC
1098	if (ipprintfs)
1099		printf("forward: src %lx dst %lx ttl %x\n",
1100			ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl);
1101#endif
1102
1103
1104	if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
1105		ipstat.ips_cantforward++;
1106		m_freem(m);
1107		return;
1108	}
1109	HTONS(ip->ip_id);
1110	if (ip->ip_ttl <= IPTTLDEC) {
1111		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1112		return;
1113	}
1114	ip->ip_ttl -= IPTTLDEC;
1115
1116	sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1117	if ((rt = ipforward_rt.ro_rt) == 0 ||
1118	    ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
1119		if (ipforward_rt.ro_rt) {
1120			RTFREE(ipforward_rt.ro_rt);
1121			ipforward_rt.ro_rt = 0;
1122		}
1123		sin->sin_family = AF_INET;
1124		sin->sin_len = sizeof(*sin);
1125		sin->sin_addr = ip->ip_dst;
1126
1127		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1128		if (ipforward_rt.ro_rt == 0) {
1129			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1130			return;
1131		}
1132		rt = ipforward_rt.ro_rt;
1133	}
1134
1135	/*
1136	 * Save at most 64 bytes of the packet in case
1137	 * we need to generate an ICMP message to the src.
1138	 */
1139	mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
1140
1141	/*
1142	 * If forwarding packet using same interface that it came in on,
1143	 * perhaps should send a redirect to sender to shortcut a hop.
1144	 * Only send redirect if source is sending directly to us,
1145	 * and if packet was not source routed (or has any options).
1146	 * Also, don't send redirect if forwarding using a default route
1147	 * or a route modified by a redirect.
1148	 */
1149#define	satosin(sa)	((struct sockaddr_in *)(sa))
1150	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1151	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1152	    satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1153	    ipsendredirects && !srcrt) {
1154#define	RTA(rt)	((struct in_ifaddr *)(rt->rt_ifa))
1155		u_long src = ntohl(ip->ip_src.s_addr);
1156
1157		if (RTA(rt) &&
1158		    (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1159		    if (rt->rt_flags & RTF_GATEWAY)
1160			dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1161		    else
1162			dest = ip->ip_dst.s_addr;
1163		    /* Router requirements says to only send host redirects */
1164		    type = ICMP_REDIRECT;
1165		    code = ICMP_REDIRECT_HOST;
1166#ifdef DIAGNOSTIC
1167		    if (ipprintfs)
1168		        printf("redirect (%d) to %lx\n", code, (u_long)dest);
1169#endif
1170		}
1171	}
1172
1173	error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING
1174#ifdef DIRECTED_BROADCAST
1175			    | IP_ALLOWBROADCAST
1176#endif
1177						, 0);
1178	if (error)
1179		ipstat.ips_cantforward++;
1180	else {
1181		ipstat.ips_forward++;
1182		if (type)
1183			ipstat.ips_redirectsent++;
1184		else {
1185			if (mcopy)
1186				m_freem(mcopy);
1187			return;
1188		}
1189	}
1190	if (mcopy == NULL)
1191		return;
1192	destifp = NULL;
1193
1194	switch (error) {
1195
1196	case 0:				/* forwarded, but need redirect */
1197		/* type, code set above */
1198		break;
1199
1200	case ENETUNREACH:		/* shouldn't happen, checked above */
1201	case EHOSTUNREACH:
1202	case ENETDOWN:
1203	case EHOSTDOWN:
1204	default:
1205		type = ICMP_UNREACH;
1206		code = ICMP_UNREACH_HOST;
1207		break;
1208
1209	case EMSGSIZE:
1210		type = ICMP_UNREACH;
1211		code = ICMP_UNREACH_NEEDFRAG;
1212		if (ipforward_rt.ro_rt)
1213			destifp = ipforward_rt.ro_rt->rt_ifp;
1214		ipstat.ips_cantfrag++;
1215		break;
1216
1217	case ENOBUFS:
1218		type = ICMP_SOURCEQUENCH;
1219		code = 0;
1220		break;
1221	}
1222	icmp_error(mcopy, type, code, dest, destifp);
1223}
1224
1225int
1226ip_rsvp_init(struct socket *so)
1227{
1228	if (so->so_type != SOCK_RAW ||
1229	    so->so_proto->pr_protocol != IPPROTO_RSVP)
1230	  return EOPNOTSUPP;
1231
1232	if (ip_rsvpd != NULL)
1233	  return EADDRINUSE;
1234
1235	ip_rsvpd = so;
1236	/*
1237	 * This may seem silly, but we need to be sure we don't over-increment
1238	 * the RSVP counter, in case something slips up.
1239	 */
1240	if (!ip_rsvp_on) {
1241		ip_rsvp_on = 1;
1242		rsvp_on++;
1243	}
1244
1245	return 0;
1246}
1247
1248int
1249ip_rsvp_done(void)
1250{
1251	ip_rsvpd = NULL;
1252	/*
1253	 * This may seem silly, but we need to be sure we don't over-decrement
1254	 * the RSVP counter, in case something slips up.
1255	 */
1256	if (ip_rsvp_on) {
1257		ip_rsvp_on = 0;
1258		rsvp_on--;
1259	}
1260	return 0;
1261}
1262