xref: /freebsd/sys/netinet/ip_input.c (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
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  * $FreeBSD$
35  */
36 
37 #define	_IP_VHL
38 
39 #include "opt_bootp.h"
40 #include "opt_ipfw.h"
41 #include "opt_ipdn.h"
42 #include "opt_ipdivert.h"
43 #include "opt_ipfilter.h"
44 #include "opt_ipstealth.h"
45 #include "opt_ipsec.h"
46 #include "opt_pfil_hooks.h"
47 #include "opt_random_ip_id.h"
48 
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/mbuf.h>
52 #include <sys/malloc.h>
53 #include <sys/domain.h>
54 #include <sys/protosw.h>
55 #include <sys/socket.h>
56 #include <sys/time.h>
57 #include <sys/kernel.h>
58 #include <sys/syslog.h>
59 #include <sys/sysctl.h>
60 
61 #include <net/pfil.h>
62 #include <net/if.h>
63 #include <net/if_var.h>
64 #include <net/if_dl.h>
65 #include <net/route.h>
66 #include <net/netisr.h>
67 #include <net/intrq.h>
68 
69 #include <netinet/in.h>
70 #include <netinet/in_systm.h>
71 #include <netinet/in_var.h>
72 #include <netinet/ip.h>
73 #include <netinet/in_pcb.h>
74 #include <netinet/ip_var.h>
75 #include <netinet/ip_icmp.h>
76 #include <machine/in_cksum.h>
77 
78 #include <sys/socketvar.h>
79 
80 #include <netinet/ip_fw.h>
81 
82 #ifdef IPSEC
83 #include <netinet6/ipsec.h>
84 #include <netkey/key.h>
85 #endif
86 
87 #include "faith.h"
88 #if defined(NFAITH) && NFAITH > 0
89 #include <net/if_types.h>
90 #endif
91 
92 #ifdef DUMMYNET
93 #include <netinet/ip_dummynet.h>
94 #endif
95 
96 int rsvp_on = 0;
97 static int ip_rsvp_on;
98 struct socket *ip_rsvpd;
99 
100 int	ipforwarding = 0;
101 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
102     &ipforwarding, 0, "Enable IP forwarding between interfaces");
103 
104 static int	ipsendredirects = 1; /* XXX */
105 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
106     &ipsendredirects, 0, "Enable sending IP redirects");
107 
108 int	ip_defttl = IPDEFTTL;
109 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
110     &ip_defttl, 0, "Maximum TTL on IP packets");
111 
112 static int	ip_dosourceroute = 0;
113 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
114     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
115 
116 static int	ip_acceptsourceroute = 0;
117 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
118     CTLFLAG_RW, &ip_acceptsourceroute, 0,
119     "Enable accepting source routed IP packets");
120 
121 static int	ip_keepfaith = 0;
122 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
123 	&ip_keepfaith,	0,
124 	"Enable packet capture for FAITH IPv4->IPv6 translater daemon");
125 
126 static int	ip_nfragpackets = 0;
127 static int	ip_maxfragpackets;	/* initialized in ip_init() */
128 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
129 	&ip_maxfragpackets, 0,
130 	"Maximum number of IPv4 fragment reassembly queue entries");
131 
132 /*
133  * XXX - Setting ip_checkinterface mostly implements the receive side of
134  * the Strong ES model described in RFC 1122, but since the routing table
135  * and transmit implementation do not implement the Strong ES model,
136  * setting this to 1 results in an odd hybrid.
137  *
138  * XXX - ip_checkinterface currently must be disabled if you use ipnat
139  * to translate the destination address to another local interface.
140  *
141  * XXX - ip_checkinterface must be disabled if you add IP aliases
142  * to the loopback interface instead of the interface where the
143  * packets for those addresses are received.
144  */
145 static int	ip_checkinterface = 1;
146 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
147     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
148 
149 #ifdef DIAGNOSTIC
150 static int	ipprintfs = 0;
151 #endif
152 
153 extern	struct domain inetdomain;
154 extern	struct protosw inetsw[];
155 u_char	ip_protox[IPPROTO_MAX];
156 static int	ipqmaxlen = IFQ_MAXLEN;
157 struct	in_ifaddrhead in_ifaddrhead; /* first inet address */
158 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
159     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
160 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
161     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
162 
163 struct ipstat ipstat;
164 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
165     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
166 
167 /* Packet reassembly stuff */
168 #define IPREASS_NHASH_LOG2      6
169 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
170 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
171 #define IPREASS_HASH(x,y) \
172 	(((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
173 
174 static TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH];
175 static int    nipq = 0;         /* total # of reass queues */
176 static int    maxnipq;
177 const  int    ipintrq_present = 1;
178 
179 #ifdef IPCTL_DEFMTU
180 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
181     &ip_mtu, 0, "Default MTU");
182 #endif
183 
184 #ifdef IPSTEALTH
185 static int	ipstealth = 0;
186 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
187     &ipstealth, 0, "");
188 #endif
189 
190 
191 /* Firewall hooks */
192 ip_fw_chk_t *ip_fw_chk_ptr;
193 ip_fw_ctl_t *ip_fw_ctl_ptr;
194 int fw_enable = 1 ;
195 
196 #ifdef DUMMYNET
197 ip_dn_ctl_t *ip_dn_ctl_ptr;
198 #endif
199 
200 
201 /*
202  * We need to save the IP options in case a protocol wants to respond
203  * to an incoming packet over the same route if the packet got here
204  * using IP source routing.  This allows connection establishment and
205  * maintenance when the remote end is on a network that is not known
206  * to us.
207  */
208 static int	ip_nhops = 0;
209 static	struct ip_srcrt {
210 	struct	in_addr dst;			/* final destination */
211 	char	nop;				/* one NOP to align */
212 	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
213 	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
214 } ip_srcrt;
215 
216 struct sockaddr_in *ip_fw_fwd_addr;
217 
218 static void	save_rte __P((u_char *, struct in_addr));
219 static int	ip_dooptions __P((struct mbuf *));
220 static void	ip_forward __P((struct mbuf *, int));
221 static void	ip_freef __P((struct ipqhead *, struct ipq *));
222 #ifdef IPDIVERT
223 static struct	mbuf *ip_reass __P((struct mbuf *, struct ipqhead *, struct ipq *, u_int32_t *, u_int16_t *));
224 #else
225 static struct	mbuf *ip_reass __P((struct mbuf *, struct ipqhead *, struct ipq *));
226 #endif
227 static struct	in_ifaddr *ip_rtaddr __P((struct in_addr));
228 static void	ipintr __P((void));
229 
230 /*
231  * IP initialization: fill in IP protocol switch table.
232  * All protocols not implemented in kernel go to raw IP protocol handler.
233  */
234 void
235 ip_init()
236 {
237 	register struct protosw *pr;
238 	register int i;
239 
240 	TAILQ_INIT(&in_ifaddrhead);
241 	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
242 	if (pr == 0)
243 		panic("ip_init");
244 	for (i = 0; i < IPPROTO_MAX; i++)
245 		ip_protox[i] = pr - inetsw;
246 	for (pr = inetdomain.dom_protosw;
247 	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
248 		if (pr->pr_domain->dom_family == PF_INET &&
249 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
250 			ip_protox[pr->pr_protocol] = pr - inetsw;
251 
252 	for (i = 0; i < IPREASS_NHASH; i++)
253 	    TAILQ_INIT(&ipq[i]);
254 
255 	maxnipq = nmbclusters / 4;
256 	ip_maxfragpackets = nmbclusters / 4;
257 
258 #ifndef RANDOM_IP_ID
259 	ip_id = time_second & 0xffff;
260 #endif
261 	ipintrq.ifq_maxlen = ipqmaxlen;
262 	mtx_init(&ipintrq.ifq_mtx, "ip_inq", MTX_DEF);
263 
264 	register_netisr(NETISR_IP, ipintr);
265 }
266 
267 static struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
268 struct	route ipforward_rt;
269 
270 /*
271  * Ip input routine.  Checksum and byte swap header.  If fragmented
272  * try to reassemble.  Process options.  Pass to next level.
273  */
274 void
275 ip_input(struct mbuf *m)
276 {
277 	struct ip *ip;
278 	struct ipq *fp;
279 	struct in_ifaddr *ia = NULL;
280 	int    i, hlen, checkif;
281 	u_short sum;
282 	u_int16_t divert_cookie;		/* firewall cookie */
283 	struct in_addr pkt_dst;
284 #ifdef IPDIVERT
285 	u_int32_t divert_info = 0;		/* packet divert/tee info */
286 #endif
287 	struct ip_fw_chain *rule = NULL;
288 #ifdef PFIL_HOOKS
289 	struct packet_filter_hook *pfh;
290 	struct mbuf *m0;
291 	int rv;
292 #endif /* PFIL_HOOKS */
293 
294 #ifdef IPDIVERT
295 	/* Get and reset firewall cookie */
296 	divert_cookie = ip_divert_cookie;
297 	ip_divert_cookie = 0;
298 #else
299 	divert_cookie = 0;
300 #endif
301 
302 #if defined(IPFIREWALL) && defined(DUMMYNET)
303         /*
304          * dummynet packet are prepended a vestigial mbuf with
305          * m_type = MT_DUMMYNET and m_data pointing to the matching
306          * rule.
307          */
308         if (m->m_type == MT_DUMMYNET) {
309             rule = (struct ip_fw_chain *)(m->m_data) ;
310             m = m->m_next ;
311             ip = mtod(m, struct ip *);
312             hlen = IP_VHL_HL(ip->ip_vhl) << 2;
313             goto iphack ;
314         } else
315             rule = NULL ;
316 #endif
317 
318 #ifdef	DIAGNOSTIC
319 	if (m == NULL || (m->m_flags & M_PKTHDR) == 0)
320 		panic("ip_input no HDR");
321 #endif
322 	ipstat.ips_total++;
323 
324 	if (m->m_pkthdr.len < sizeof(struct ip))
325 		goto tooshort;
326 
327 	if (m->m_len < sizeof (struct ip) &&
328 	    (m = m_pullup(m, sizeof (struct ip))) == 0) {
329 		ipstat.ips_toosmall++;
330 		return;
331 	}
332 	ip = mtod(m, struct ip *);
333 
334 	if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
335 		ipstat.ips_badvers++;
336 		goto bad;
337 	}
338 
339 	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
340 	if (hlen < sizeof(struct ip)) {	/* minimum header length */
341 		ipstat.ips_badhlen++;
342 		goto bad;
343 	}
344 	if (hlen > m->m_len) {
345 		if ((m = m_pullup(m, hlen)) == 0) {
346 			ipstat.ips_badhlen++;
347 			return;
348 		}
349 		ip = mtod(m, struct ip *);
350 	}
351 
352 	/* 127/8 must not appear on wire - RFC1122 */
353 	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
354 	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
355 		if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
356 			ipstat.ips_badaddr++;
357 			goto bad;
358 		}
359 	}
360 
361 	if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
362 		sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
363 	} else {
364 		if (hlen == sizeof(struct ip)) {
365 			sum = in_cksum_hdr(ip);
366 		} else {
367 			sum = in_cksum(m, hlen);
368 		}
369 	}
370 	if (sum) {
371 		ipstat.ips_badsum++;
372 		goto bad;
373 	}
374 
375 	/*
376 	 * Convert fields to host representation.
377 	 */
378 	NTOHS(ip->ip_len);
379 	if (ip->ip_len < hlen) {
380 		ipstat.ips_badlen++;
381 		goto bad;
382 	}
383 	NTOHS(ip->ip_off);
384 
385 	/*
386 	 * Check that the amount of data in the buffers
387 	 * is as at least much as the IP header would have us expect.
388 	 * Trim mbufs if longer than we expect.
389 	 * Drop packet if shorter than we expect.
390 	 */
391 	if (m->m_pkthdr.len < ip->ip_len) {
392 tooshort:
393 		ipstat.ips_tooshort++;
394 		goto bad;
395 	}
396 	if (m->m_pkthdr.len > ip->ip_len) {
397 		if (m->m_len == m->m_pkthdr.len) {
398 			m->m_len = ip->ip_len;
399 			m->m_pkthdr.len = ip->ip_len;
400 		} else
401 			m_adj(m, ip->ip_len - m->m_pkthdr.len);
402 	}
403 
404 #ifdef IPSEC
405 	if (ipsec_gethist(m, NULL))
406 		goto pass;
407 #endif
408 
409 	/*
410 	 * IpHack's section.
411 	 * Right now when no processing on packet has done
412 	 * and it is still fresh out of network we do our black
413 	 * deals with it.
414 	 * - Firewall: deny/allow/divert
415 	 * - Xlate: translate packet's addr/port (NAT).
416 	 * - Pipe: pass pkt through dummynet.
417 	 * - Wrap: fake packet's addr/port <unimpl.>
418 	 * - Encapsulate: put it in another IP and send out. <unimp.>
419  	 */
420 
421 #if defined(IPFIREWALL) && defined(DUMMYNET)
422 iphack:
423 #endif
424 
425 #ifdef PFIL_HOOKS
426 	/*
427 	 * Run through list of hooks for input packets.  If there are any
428 	 * filters which require that additional packets in the flow are
429 	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
430 	 * Note that filters must _never_ set this flag, as another filter
431 	 * in the list may have previously cleared it.
432 	 */
433 	m0 = m;
434 	pfh = pfil_hook_get(PFIL_IN, &inetsw[ip_protox[IPPROTO_IP]].pr_pfh);
435 	for (; pfh; pfh = TAILQ_NEXT(pfh, pfil_link))
436 		if (pfh->pfil_func) {
437 			rv = pfh->pfil_func(ip, hlen,
438 					    m->m_pkthdr.rcvif, 0, &m0);
439 			if (rv)
440 				return;
441 			m = m0;
442 			if (m == NULL)
443 				return;
444 			ip = mtod(m, struct ip *);
445 		}
446 #endif /* PFIL_HOOKS */
447 
448 	if (fw_enable && ip_fw_chk_ptr) {
449 #ifdef IPFIREWALL_FORWARD
450 		/*
451 		 * If we've been forwarded from the output side, then
452 		 * skip the firewall a second time
453 		 */
454 		if (ip_fw_fwd_addr)
455 			goto ours;
456 #endif	/* IPFIREWALL_FORWARD */
457 		/*
458 		 * See the comment in ip_output for the return values
459 		 * produced by the firewall.
460 		 */
461 		i = (*ip_fw_chk_ptr)(&ip,
462 		    hlen, NULL, &divert_cookie, &m, &rule, &ip_fw_fwd_addr);
463 		if (i & IP_FW_PORT_DENY_FLAG) { /* XXX new interface-denied */
464 		    if (m)
465 			m_freem(m);
466 		    return ;
467 		}
468 		if (m == NULL) {	/* Packet discarded by firewall */
469 		    static int __debug=10;
470 		    if (__debug >0) {
471 			printf("firewall returns NULL, please update!\n");
472 			__debug-- ;
473 		    }
474 		    return;
475 		}
476 		if (i == 0 && ip_fw_fwd_addr == NULL)	/* common case */
477 			goto pass;
478 #ifdef DUMMYNET
479                 if ((i & IP_FW_PORT_DYNT_FLAG) != 0) {
480                         /* Send packet to the appropriate pipe */
481                         dummynet_io(i&0xffff,DN_TO_IP_IN,m,NULL,NULL,0, rule,
482 				    0);
483 			return;
484 		}
485 #endif
486 #ifdef IPDIVERT
487 		if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) {
488 			/* Divert or tee packet */
489 			divert_info = i;
490 			goto ours;
491 		}
492 #endif
493 #ifdef IPFIREWALL_FORWARD
494 		if (i == 0 && ip_fw_fwd_addr != NULL)
495 			goto pass;
496 #endif
497 		/*
498 		 * if we get here, the packet must be dropped
499 		 */
500 		m_freem(m);
501 		return;
502 	}
503 pass:
504 
505 	/*
506 	 * Process options and, if not destined for us,
507 	 * ship it on.  ip_dooptions returns 1 when an
508 	 * error was detected (causing an icmp message
509 	 * to be sent and the original packet to be freed).
510 	 */
511 	ip_nhops = 0;		/* for source routed packets */
512 	if (hlen > sizeof (struct ip) && ip_dooptions(m)) {
513 #ifdef IPFIREWALL_FORWARD
514 		ip_fw_fwd_addr = NULL;
515 #endif
516 		return;
517 	}
518 
519         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
520          * matter if it is destined to another node, or whether it is
521          * a multicast one, RSVP wants it! and prevents it from being forwarded
522          * anywhere else. Also checks if the rsvp daemon is running before
523 	 * grabbing the packet.
524          */
525 	if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
526 		goto ours;
527 
528 	/*
529 	 * Check our list of addresses, to see if the packet is for us.
530 	 * If we don't have any addresses, assume any unicast packet
531 	 * we receive might be for us (and let the upper layers deal
532 	 * with it).
533 	 */
534 	if (TAILQ_EMPTY(&in_ifaddrhead) &&
535 	    (m->m_flags & (M_MCAST|M_BCAST)) == 0)
536 		goto ours;
537 
538 	/*
539 	 * Cache the destination address of the packet; this may be
540 	 * changed by use of 'ipfw fwd'.
541 	 */
542 	pkt_dst = ip_fw_fwd_addr == NULL ?
543 	    ip->ip_dst : ip_fw_fwd_addr->sin_addr;
544 
545 	/*
546 	 * Enable a consistency check between the destination address
547 	 * and the arrival interface for a unicast packet (the RFC 1122
548 	 * strong ES model) if IP forwarding is disabled and the packet
549 	 * is not locally generated and the packet is not subject to
550 	 * 'ipfw fwd'.
551 	 *
552          * XXX - Checking also should be disabled if the destination
553 	 * address is ipnat'ed to a different interface.
554 	 *
555 	 * XXX - Checking is incompatible with IP aliases added
556 	 * to the loopback interface instead of the interface where
557 	 * the packets are received.
558 	 */
559 	checkif = ip_checkinterface && (ipforwarding == 0) &&
560 	    ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
561 	    (ip_fw_fwd_addr == NULL);
562 
563 	TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) {
564 #define	satosin(sa)	((struct sockaddr_in *)(sa))
565 
566 #ifdef BOOTP_COMPAT
567 		if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
568 			goto ours;
569 #endif
570 		/*
571 		 * If the address matches, verify that the packet
572 		 * arrived via the correct interface if checking is
573 		 * enabled.
574 		 */
575 		if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr &&
576 		    (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
577 			goto ours;
578 		/*
579 		 * Only accept broadcast packets that arrive via the
580 		 * matching interface.  Reception of forwarded directed
581 		 * broadcasts would be handled via ip_forward() and
582 		 * ether_output() with the loopback into the stack for
583 		 * SIMPLEX interfaces handled by ether_output().
584 		 */
585 		if (ia->ia_ifp == m->m_pkthdr.rcvif &&
586 		    ia->ia_ifp && ia->ia_ifp->if_flags & IFF_BROADCAST) {
587 			if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
588 			    pkt_dst.s_addr)
589 				goto ours;
590 			if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr)
591 				goto ours;
592 		}
593 	}
594 	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
595 		struct in_multi *inm;
596 		if (ip_mrouter) {
597 			/*
598 			 * If we are acting as a multicast router, all
599 			 * incoming multicast packets are passed to the
600 			 * kernel-level multicast forwarding function.
601 			 * The packet is returned (relatively) intact; if
602 			 * ip_mforward() returns a non-zero value, the packet
603 			 * must be discarded, else it may be accepted below.
604 			 */
605 			if (ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
606 				ipstat.ips_cantforward++;
607 				m_freem(m);
608 				return;
609 			}
610 
611 			/*
612 			 * The process-level routing demon needs to receive
613 			 * all multicast IGMP packets, whether or not this
614 			 * host belongs to their destination groups.
615 			 */
616 			if (ip->ip_p == IPPROTO_IGMP)
617 				goto ours;
618 			ipstat.ips_forward++;
619 		}
620 		/*
621 		 * See if we belong to the destination multicast group on the
622 		 * arrival interface.
623 		 */
624 		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
625 		if (inm == NULL) {
626 			ipstat.ips_notmember++;
627 			m_freem(m);
628 			return;
629 		}
630 		goto ours;
631 	}
632 	if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
633 		goto ours;
634 	if (ip->ip_dst.s_addr == INADDR_ANY)
635 		goto ours;
636 
637 #if defined(NFAITH) && 0 < NFAITH
638 	/*
639 	 * FAITH(Firewall Aided Internet Translator)
640 	 */
641 	if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
642 		if (ip_keepfaith) {
643 			if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
644 				goto ours;
645 		}
646 		m_freem(m);
647 		return;
648 	}
649 #endif
650 	/*
651 	 * Not for us; forward if possible and desirable.
652 	 */
653 	if (ipforwarding == 0) {
654 		ipstat.ips_cantforward++;
655 		m_freem(m);
656 	} else
657 		ip_forward(m, 0);
658 #ifdef IPFIREWALL_FORWARD
659 	ip_fw_fwd_addr = NULL;
660 #endif
661 	return;
662 
663 ours:
664 	/* Count the packet in the ip address stats */
665 	if (ia != NULL) {
666 		ia->ia_ifa.if_ipackets++;
667 		ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
668 	}
669 
670 	/*
671 	 * If offset or IP_MF are set, must reassemble.
672 	 * Otherwise, nothing need be done.
673 	 * (We could look in the reassembly queue to see
674 	 * if the packet was previously fragmented,
675 	 * but it's not worth the time; just let them time out.)
676 	 */
677 	if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
678 
679 		sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
680 		/*
681 		 * Look for queue of fragments
682 		 * of this datagram.
683 		 */
684 		TAILQ_FOREACH(fp, &ipq[sum], ipq_list)
685 			if (ip->ip_id == fp->ipq_id &&
686 			    ip->ip_src.s_addr == fp->ipq_src.s_addr &&
687 			    ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
688 			    ip->ip_p == fp->ipq_p)
689 				goto found;
690 
691 		fp = 0;
692 
693 		/* check if there's a place for the new queue */
694 		if (nipq > maxnipq) {
695 		    /*
696 		     * drop something from the tail of the current queue
697 		     * before proceeding further
698 		     */
699 		    struct ipq *q = TAILQ_LAST(&ipq[sum], ipqhead);
700 		    if (q == NULL) {   /* gak */
701 			for (i = 0; i < IPREASS_NHASH; i++) {
702 			    struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead);
703 			    if (r) {
704 				ip_freef(&ipq[i], r);
705 				break;
706 			    }
707 			}
708 		    } else
709 			ip_freef(&ipq[sum], q);
710 		}
711 found:
712 		/*
713 		 * Adjust ip_len to not reflect header,
714 		 * convert offset of this to bytes.
715 		 */
716 		ip->ip_len -= hlen;
717 		if (ip->ip_off & IP_MF) {
718 		        /*
719 		         * Make sure that fragments have a data length
720 			 * that's a non-zero multiple of 8 bytes.
721 		         */
722 			if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
723 				ipstat.ips_toosmall++; /* XXX */
724 				goto bad;
725 			}
726 			m->m_flags |= M_FRAG;
727 		}
728 		ip->ip_off <<= 3;
729 
730 		/*
731 		 * Attempt reassembly; if it succeeds, proceed.
732 		 */
733 		ipstat.ips_fragments++;
734 		m->m_pkthdr.header = ip;
735 #ifdef IPDIVERT
736 		m = ip_reass(m,
737 		    &ipq[sum], fp, &divert_info, &divert_cookie);
738 #else
739 		m = ip_reass(m, &ipq[sum], fp);
740 #endif
741 		if (m == 0) {
742 #ifdef IPFIREWALL_FORWARD
743 			ip_fw_fwd_addr = NULL;
744 #endif
745 			return;
746 		}
747 		ipstat.ips_reassembled++;
748 		ip = mtod(m, struct ip *);
749 		/* Get the header length of the reassembled packet */
750 		hlen = IP_VHL_HL(ip->ip_vhl) << 2;
751 #ifdef IPDIVERT
752 		/* Restore original checksum before diverting packet */
753 		if (divert_info != 0) {
754 			ip->ip_len += hlen;
755 			HTONS(ip->ip_len);
756 			HTONS(ip->ip_off);
757 			ip->ip_sum = 0;
758 			if (hlen == sizeof(struct ip))
759 				ip->ip_sum = in_cksum_hdr(ip);
760 			else
761 				ip->ip_sum = in_cksum(m, hlen);
762 			NTOHS(ip->ip_off);
763 			NTOHS(ip->ip_len);
764 			ip->ip_len -= hlen;
765 		}
766 #endif
767 	} else
768 		ip->ip_len -= hlen;
769 
770 #ifdef IPDIVERT
771 	/*
772 	 * Divert or tee packet to the divert protocol if required.
773 	 *
774 	 * If divert_info is zero then cookie should be too, so we shouldn't
775 	 * need to clear them here.  Assume divert_packet() does so also.
776 	 */
777 	if (divert_info != 0) {
778 		struct mbuf *clone = NULL;
779 
780 		/* Clone packet if we're doing a 'tee' */
781 		if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0)
782 			clone = m_dup(m, M_DONTWAIT);
783 
784 		/* Restore packet header fields to original values */
785 		ip->ip_len += hlen;
786 		HTONS(ip->ip_len);
787 		HTONS(ip->ip_off);
788 
789 		/* Deliver packet to divert input routine */
790 		ip_divert_cookie = divert_cookie;
791 		divert_packet(m, 1, divert_info & 0xffff);
792 		ipstat.ips_delivered++;
793 
794 		/* If 'tee', continue with original packet */
795 		if (clone == NULL)
796 			return;
797 		m = clone;
798 		ip = mtod(m, struct ip *);
799 	}
800 #endif
801 
802 #ifdef IPSEC
803 	/*
804 	 * enforce IPsec policy checking if we are seeing last header.
805 	 * note that we do not visit this with protocols with pcb layer
806 	 * code - like udp/tcp/raw ip.
807 	 */
808 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
809 	    ipsec4_in_reject(m, NULL)) {
810 		ipsecstat.in_polvio++;
811 		goto bad;
812 	}
813 #endif
814 
815 	/*
816 	 * Switch out to protocol's input routine.
817 	 */
818 	ipstat.ips_delivered++;
819     {
820 	int off = hlen;
821 
822 	(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, off);
823 #ifdef	IPFIREWALL_FORWARD
824 	ip_fw_fwd_addr = NULL;	/* tcp needed it */
825 #endif
826 	return;
827     }
828 bad:
829 #ifdef	IPFIREWALL_FORWARD
830 	ip_fw_fwd_addr = NULL;
831 #endif
832 	m_freem(m);
833 }
834 
835 /*
836  * IP software interrupt routine - to go away sometime soon
837  */
838 static void
839 ipintr(void)
840 {
841 	struct mbuf *m;
842 
843 	while (1) {
844 		IF_DEQUEUE(&ipintrq, m);
845 		if (m == 0)
846 			return;
847 		ip_input(m);
848 	}
849 }
850 
851 /*
852  * Take incoming datagram fragment and try to reassemble it into
853  * whole datagram.  If a chain for reassembly of this datagram already
854  * exists, then it is given as fp; otherwise have to make a chain.
855  *
856  * When IPDIVERT enabled, keep additional state with each packet that
857  * tells us if we need to divert or tee the packet we're building.
858  */
859 
860 static struct mbuf *
861 #ifdef IPDIVERT
862 ip_reass(m, head, fp, divinfo, divcookie)
863 #else
864 ip_reass(m, head, fp)
865 #endif
866 	struct mbuf *m;
867 	struct ipqhead *head;
868 	struct ipq *fp;
869 #ifdef IPDIVERT
870 	u_int32_t *divinfo;
871 	u_int16_t *divcookie;
872 #endif
873 {
874 	struct ip *ip = mtod(m, struct ip *);
875 	register struct mbuf *p, *q, *nq;
876 	struct mbuf *t;
877 	int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
878 	int i, next;
879 
880 	/*
881 	 * Presence of header sizes in mbufs
882 	 * would confuse code below.
883 	 */
884 	m->m_data += hlen;
885 	m->m_len -= hlen;
886 
887 	/*
888 	 * If first fragment to arrive, create a reassembly queue.
889 	 */
890 	if (fp == 0) {
891 		/*
892 		 * Enforce upper bound on number of fragmented packets
893 		 * for which we attempt reassembly;
894 		 * If maxfrag is 0, never accept fragments.
895 		 * If maxfrag is -1, accept all fragments without limitation.
896 		 */
897 		if ((ip_maxfragpackets >= 0) && (ip_nfragpackets >= ip_maxfragpackets))
898 			goto dropfrag;
899 		ip_nfragpackets++;
900 		if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
901 			goto dropfrag;
902 		fp = mtod(t, struct ipq *);
903 		TAILQ_INSERT_HEAD(head, fp, ipq_list);
904 		nipq++;
905 		fp->ipq_ttl = IPFRAGTTL;
906 		fp->ipq_p = ip->ip_p;
907 		fp->ipq_id = ip->ip_id;
908 		fp->ipq_src = ip->ip_src;
909 		fp->ipq_dst = ip->ip_dst;
910 		fp->ipq_frags = m;
911 		m->m_nextpkt = NULL;
912 #ifdef IPDIVERT
913 		fp->ipq_div_info = 0;
914 		fp->ipq_div_cookie = 0;
915 #endif
916 		goto inserted;
917 	}
918 
919 #define GETIP(m)	((struct ip*)((m)->m_pkthdr.header))
920 
921 	/*
922 	 * Find a segment which begins after this one does.
923 	 */
924 	for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
925 		if (GETIP(q)->ip_off > ip->ip_off)
926 			break;
927 
928 	/*
929 	 * If there is a preceding segment, it may provide some of
930 	 * our data already.  If so, drop the data from the incoming
931 	 * segment.  If it provides all of our data, drop us, otherwise
932 	 * stick new segment in the proper place.
933 	 *
934 	 * If some of the data is dropped from the the preceding
935 	 * segment, then it's checksum is invalidated.
936 	 */
937 	if (p) {
938 		i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
939 		if (i > 0) {
940 			if (i >= ip->ip_len)
941 				goto dropfrag;
942 			m_adj(m, i);
943 			m->m_pkthdr.csum_flags = 0;
944 			ip->ip_off += i;
945 			ip->ip_len -= i;
946 		}
947 		m->m_nextpkt = p->m_nextpkt;
948 		p->m_nextpkt = m;
949 	} else {
950 		m->m_nextpkt = fp->ipq_frags;
951 		fp->ipq_frags = m;
952 	}
953 
954 	/*
955 	 * While we overlap succeeding segments trim them or,
956 	 * if they are completely covered, dequeue them.
957 	 */
958 	for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
959 	     q = nq) {
960 		i = (ip->ip_off + ip->ip_len) -
961 		    GETIP(q)->ip_off;
962 		if (i < GETIP(q)->ip_len) {
963 			GETIP(q)->ip_len -= i;
964 			GETIP(q)->ip_off += i;
965 			m_adj(q, i);
966 			q->m_pkthdr.csum_flags = 0;
967 			break;
968 		}
969 		nq = q->m_nextpkt;
970 		m->m_nextpkt = nq;
971 		m_freem(q);
972 	}
973 
974 inserted:
975 
976 #ifdef IPDIVERT
977 	/*
978 	 * Transfer firewall instructions to the fragment structure.
979 	 * Any fragment diverting causes the whole packet to divert.
980 	 */
981 	fp->ipq_div_info = *divinfo;
982 	fp->ipq_div_cookie = *divcookie;
983 	*divinfo = 0;
984 	*divcookie = 0;
985 #endif
986 
987 	/*
988 	 * Check for complete reassembly.
989 	 */
990 	next = 0;
991 	for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
992 		if (GETIP(q)->ip_off != next)
993 			return (0);
994 		next += GETIP(q)->ip_len;
995 	}
996 	/* Make sure the last packet didn't have the IP_MF flag */
997 	if (p->m_flags & M_FRAG)
998 		return (0);
999 
1000 	/*
1001 	 * Reassembly is complete.  Make sure the packet is a sane size.
1002 	 */
1003 	q = fp->ipq_frags;
1004 	ip = GETIP(q);
1005 	if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) {
1006 		ipstat.ips_toolong++;
1007 		ip_freef(head, fp);
1008 		return (0);
1009 	}
1010 
1011 	/*
1012 	 * Concatenate fragments.
1013 	 */
1014 	m = q;
1015 	t = m->m_next;
1016 	m->m_next = 0;
1017 	m_cat(m, t);
1018 	nq = q->m_nextpkt;
1019 	q->m_nextpkt = 0;
1020 	for (q = nq; q != NULL; q = nq) {
1021 		nq = q->m_nextpkt;
1022 		q->m_nextpkt = NULL;
1023 		m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1024 		m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1025 		m_cat(m, q);
1026 	}
1027 
1028 #ifdef IPDIVERT
1029 	/*
1030 	 * Extract firewall instructions from the fragment structure.
1031 	 */
1032 	*divinfo = fp->ipq_div_info;
1033 	*divcookie = fp->ipq_div_cookie;
1034 #endif
1035 
1036 	/*
1037 	 * Create header for new ip packet by
1038 	 * modifying header of first packet;
1039 	 * dequeue and discard fragment reassembly header.
1040 	 * Make header visible.
1041 	 */
1042 	ip->ip_len = next;
1043 	ip->ip_src = fp->ipq_src;
1044 	ip->ip_dst = fp->ipq_dst;
1045 	TAILQ_REMOVE(head, fp, ipq_list);
1046 	nipq--;
1047 	(void) m_free(dtom(fp));
1048 	ip_nfragpackets--;
1049 	m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2);
1050 	m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2);
1051 	/* some debugging cruft by sklower, below, will go away soon */
1052 	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
1053 		register int plen = 0;
1054 		for (t = m; t; t = t->m_next)
1055 			plen += t->m_len;
1056 		m->m_pkthdr.len = plen;
1057 	}
1058 	return (m);
1059 
1060 dropfrag:
1061 #ifdef IPDIVERT
1062 	*divinfo = 0;
1063 	*divcookie = 0;
1064 #endif
1065 	ipstat.ips_fragdropped++;
1066 	m_freem(m);
1067 	return (0);
1068 
1069 #undef GETIP
1070 }
1071 
1072 /*
1073  * Free a fragment reassembly header and all
1074  * associated datagrams.
1075  */
1076 static void
1077 ip_freef(fhp, fp)
1078 	struct ipqhead *fhp;
1079 	struct ipq *fp;
1080 {
1081 	register struct mbuf *q;
1082 
1083 	while (fp->ipq_frags) {
1084 		q = fp->ipq_frags;
1085 		fp->ipq_frags = q->m_nextpkt;
1086 		m_freem(q);
1087 	}
1088 	TAILQ_REMOVE(fhp, fp, ipq_list);
1089 	(void) m_free(dtom(fp));
1090 	ip_nfragpackets--;
1091 	nipq--;
1092 }
1093 
1094 /*
1095  * IP timer processing;
1096  * if a timer expires on a reassembly
1097  * queue, discard it.
1098  */
1099 void
1100 ip_slowtimo()
1101 {
1102 	register struct ipq *fp;
1103 	int s = splnet();
1104 	int i;
1105 
1106 	for (i = 0; i < IPREASS_NHASH; i++) {
1107 		for(fp = TAILQ_FIRST(&ipq[i]); fp;) {
1108 			struct ipq *fpp;
1109 
1110 			fpp = fp;
1111 			fp = TAILQ_NEXT(fp, ipq_list);
1112 			if(--fpp->ipq_ttl == 0) {
1113 				ipstat.ips_fragtimeout++;
1114 				ip_freef(&ipq[i], fpp);
1115 			}
1116 		}
1117 	}
1118 	/*
1119 	 * If we are over the maximum number of fragments
1120 	 * (due to the limit being lowered), drain off
1121 	 * enough to get down to the new limit.
1122 	 */
1123 	for (i = 0; i < IPREASS_NHASH; i++) {
1124 		if (ip_maxfragpackets >= 0) {
1125 			while (ip_nfragpackets > ip_maxfragpackets &&
1126 				!TAILQ_EMPTY(&ipq[i])) {
1127 				ipstat.ips_fragdropped++;
1128 				ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1129 			}
1130 		}
1131 	}
1132 	ipflow_slowtimo();
1133 	splx(s);
1134 }
1135 
1136 /*
1137  * Drain off all datagram fragments.
1138  */
1139 void
1140 ip_drain()
1141 {
1142 	int     i;
1143 
1144 	for (i = 0; i < IPREASS_NHASH; i++) {
1145 		while(!TAILQ_EMPTY(&ipq[i])) {
1146 			ipstat.ips_fragdropped++;
1147 			ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1148 		}
1149 	}
1150 	in_rtqdrain();
1151 }
1152 
1153 /*
1154  * Do option processing on a datagram,
1155  * possibly discarding it if bad options are encountered,
1156  * or forwarding it if source-routed.
1157  * Returns 1 if packet has been forwarded/freed,
1158  * 0 if the packet should be processed further.
1159  */
1160 static int
1161 ip_dooptions(m)
1162 	struct mbuf *m;
1163 {
1164 	register struct ip *ip = mtod(m, struct ip *);
1165 	register u_char *cp;
1166 	register struct ip_timestamp *ipt;
1167 	register struct in_ifaddr *ia;
1168 	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1169 	struct in_addr *sin, dst;
1170 	n_time ntime;
1171 
1172 	dst = ip->ip_dst;
1173 	cp = (u_char *)(ip + 1);
1174 	cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1175 	for (; cnt > 0; cnt -= optlen, cp += optlen) {
1176 		opt = cp[IPOPT_OPTVAL];
1177 		if (opt == IPOPT_EOL)
1178 			break;
1179 		if (opt == IPOPT_NOP)
1180 			optlen = 1;
1181 		else {
1182 			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1183 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
1184 				goto bad;
1185 			}
1186 			optlen = cp[IPOPT_OLEN];
1187 			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1188 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
1189 				goto bad;
1190 			}
1191 		}
1192 		switch (opt) {
1193 
1194 		default:
1195 			break;
1196 
1197 		/*
1198 		 * Source routing with record.
1199 		 * Find interface with current destination address.
1200 		 * If none on this machine then drop if strictly routed,
1201 		 * or do nothing if loosely routed.
1202 		 * Record interface address and bring up next address
1203 		 * component.  If strictly routed make sure next
1204 		 * address is on directly accessible net.
1205 		 */
1206 		case IPOPT_LSRR:
1207 		case IPOPT_SSRR:
1208 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1209 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
1210 				goto bad;
1211 			}
1212 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1213 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1214 				goto bad;
1215 			}
1216 			ipaddr.sin_addr = ip->ip_dst;
1217 			ia = (struct in_ifaddr *)
1218 				ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1219 			if (ia == 0) {
1220 				if (opt == IPOPT_SSRR) {
1221 					type = ICMP_UNREACH;
1222 					code = ICMP_UNREACH_SRCFAIL;
1223 					goto bad;
1224 				}
1225 				if (!ip_dosourceroute)
1226 					goto nosourcerouting;
1227 				/*
1228 				 * Loose routing, and not at next destination
1229 				 * yet; nothing to do except forward.
1230 				 */
1231 				break;
1232 			}
1233 			off--;			/* 0 origin */
1234 			if (off > optlen - (int)sizeof(struct in_addr)) {
1235 				/*
1236 				 * End of source route.  Should be for us.
1237 				 */
1238 				if (!ip_acceptsourceroute)
1239 					goto nosourcerouting;
1240 				save_rte(cp, ip->ip_src);
1241 				break;
1242 			}
1243 
1244 			if (!ip_dosourceroute) {
1245 				if (ipforwarding) {
1246 					char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1247 					/*
1248 					 * Acting as a router, so generate ICMP
1249 					 */
1250 nosourcerouting:
1251 					strcpy(buf, inet_ntoa(ip->ip_dst));
1252 					log(LOG_WARNING,
1253 					    "attempted source route from %s to %s\n",
1254 					    inet_ntoa(ip->ip_src), buf);
1255 					type = ICMP_UNREACH;
1256 					code = ICMP_UNREACH_SRCFAIL;
1257 					goto bad;
1258 				} else {
1259 					/*
1260 					 * Not acting as a router, so silently drop.
1261 					 */
1262 					ipstat.ips_cantforward++;
1263 					m_freem(m);
1264 					return (1);
1265 				}
1266 			}
1267 
1268 			/*
1269 			 * locate outgoing interface
1270 			 */
1271 			(void)memcpy(&ipaddr.sin_addr, cp + off,
1272 			    sizeof(ipaddr.sin_addr));
1273 
1274 			if (opt == IPOPT_SSRR) {
1275 #define	INA	struct in_ifaddr *
1276 #define	SA	struct sockaddr *
1277 			    if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
1278 				ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1279 			} else
1280 				ia = ip_rtaddr(ipaddr.sin_addr);
1281 			if (ia == 0) {
1282 				type = ICMP_UNREACH;
1283 				code = ICMP_UNREACH_SRCFAIL;
1284 				goto bad;
1285 			}
1286 			ip->ip_dst = ipaddr.sin_addr;
1287 			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1288 			    sizeof(struct in_addr));
1289 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1290 			/*
1291 			 * Let ip_intr's mcast routing check handle mcast pkts
1292 			 */
1293 			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1294 			break;
1295 
1296 		case IPOPT_RR:
1297 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1298 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1299 				goto bad;
1300 			}
1301 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1302 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1303 				goto bad;
1304 			}
1305 			/*
1306 			 * If no space remains, ignore.
1307 			 */
1308 			off--;			/* 0 origin */
1309 			if (off > optlen - (int)sizeof(struct in_addr))
1310 				break;
1311 			(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1312 			    sizeof(ipaddr.sin_addr));
1313 			/*
1314 			 * locate outgoing interface; if we're the destination,
1315 			 * use the incoming interface (should be same).
1316 			 */
1317 			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
1318 			    (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
1319 				type = ICMP_UNREACH;
1320 				code = ICMP_UNREACH_HOST;
1321 				goto bad;
1322 			}
1323 			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1324 			    sizeof(struct in_addr));
1325 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1326 			break;
1327 
1328 		case IPOPT_TS:
1329 			code = cp - (u_char *)ip;
1330 			ipt = (struct ip_timestamp *)cp;
1331 			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
1332 				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
1333 				goto bad;
1334 			}
1335 			if (ipt->ipt_ptr < 5) {
1336 				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
1337 				goto bad;
1338 			}
1339 			if (ipt->ipt_ptr >
1340 			    ipt->ipt_len - (int)sizeof(int32_t)) {
1341 				if (++ipt->ipt_oflw == 0) {
1342 					code = (u_char *)&ipt->ipt_ptr -
1343 					    (u_char *)ip;
1344 					goto bad;
1345 				}
1346 				break;
1347 			}
1348 			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
1349 			switch (ipt->ipt_flg) {
1350 
1351 			case IPOPT_TS_TSONLY:
1352 				break;
1353 
1354 			case IPOPT_TS_TSANDADDR:
1355 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
1356 				    sizeof(struct in_addr) > ipt->ipt_len) {
1357 					code = (u_char *)&ipt->ipt_ptr -
1358 					    (u_char *)ip;
1359 					goto bad;
1360 				}
1361 				ipaddr.sin_addr = dst;
1362 				ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1363 							    m->m_pkthdr.rcvif);
1364 				if (ia == 0)
1365 					continue;
1366 				(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1367 				    sizeof(struct in_addr));
1368 				ipt->ipt_ptr += sizeof(struct in_addr);
1369 				break;
1370 
1371 			case IPOPT_TS_PRESPEC:
1372 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
1373 				    sizeof(struct in_addr) > ipt->ipt_len) {
1374 					code = (u_char *)&ipt->ipt_ptr -
1375 					    (u_char *)ip;
1376 					goto bad;
1377 				}
1378 				(void)memcpy(&ipaddr.sin_addr, sin,
1379 				    sizeof(struct in_addr));
1380 				if (ifa_ifwithaddr((SA)&ipaddr) == 0)
1381 					continue;
1382 				ipt->ipt_ptr += sizeof(struct in_addr);
1383 				break;
1384 
1385 			default:
1386 				/* XXX can't take &ipt->ipt_flg */
1387 				code = (u_char *)&ipt->ipt_ptr -
1388 				    (u_char *)ip + 1;
1389 				goto bad;
1390 			}
1391 			ntime = iptime();
1392 			(void)memcpy(cp + ipt->ipt_ptr - 1, &ntime,
1393 			    sizeof(n_time));
1394 			ipt->ipt_ptr += sizeof(n_time);
1395 		}
1396 	}
1397 	if (forward && ipforwarding) {
1398 		ip_forward(m, 1);
1399 		return (1);
1400 	}
1401 	return (0);
1402 bad:
1403 	icmp_error(m, type, code, 0, 0);
1404 	ipstat.ips_badoptions++;
1405 	return (1);
1406 }
1407 
1408 /*
1409  * Given address of next destination (final or next hop),
1410  * return internet address info of interface to be used to get there.
1411  */
1412 static struct in_ifaddr *
1413 ip_rtaddr(dst)
1414 	 struct in_addr dst;
1415 {
1416 	register struct sockaddr_in *sin;
1417 
1418 	sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
1419 
1420 	if (ipforward_rt.ro_rt == 0 ||
1421 	    !(ipforward_rt.ro_rt->rt_flags & RTF_UP) ||
1422 	    dst.s_addr != sin->sin_addr.s_addr) {
1423 		if (ipforward_rt.ro_rt) {
1424 			RTFREE(ipforward_rt.ro_rt);
1425 			ipforward_rt.ro_rt = 0;
1426 		}
1427 		sin->sin_family = AF_INET;
1428 		sin->sin_len = sizeof(*sin);
1429 		sin->sin_addr = dst;
1430 
1431 		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1432 	}
1433 	if (ipforward_rt.ro_rt == 0)
1434 		return ((struct in_ifaddr *)0);
1435 	return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
1436 }
1437 
1438 /*
1439  * Save incoming source route for use in replies,
1440  * to be picked up later by ip_srcroute if the receiver is interested.
1441  */
1442 void
1443 save_rte(option, dst)
1444 	u_char *option;
1445 	struct in_addr dst;
1446 {
1447 	unsigned olen;
1448 
1449 	olen = option[IPOPT_OLEN];
1450 #ifdef DIAGNOSTIC
1451 	if (ipprintfs)
1452 		printf("save_rte: olen %d\n", olen);
1453 #endif
1454 	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1455 		return;
1456 	bcopy(option, ip_srcrt.srcopt, olen);
1457 	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1458 	ip_srcrt.dst = dst;
1459 }
1460 
1461 /*
1462  * Retrieve incoming source route for use in replies,
1463  * in the same form used by setsockopt.
1464  * The first hop is placed before the options, will be removed later.
1465  */
1466 struct mbuf *
1467 ip_srcroute()
1468 {
1469 	register struct in_addr *p, *q;
1470 	register struct mbuf *m;
1471 
1472 	if (ip_nhops == 0)
1473 		return ((struct mbuf *)0);
1474 	m = m_get(M_DONTWAIT, MT_HEADER);
1475 	if (m == 0)
1476 		return ((struct mbuf *)0);
1477 
1478 #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1479 
1480 	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1481 	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1482 	    OPTSIZ;
1483 #ifdef DIAGNOSTIC
1484 	if (ipprintfs)
1485 		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1486 #endif
1487 
1488 	/*
1489 	 * First save first hop for return route
1490 	 */
1491 	p = &ip_srcrt.route[ip_nhops - 1];
1492 	*(mtod(m, struct in_addr *)) = *p--;
1493 #ifdef DIAGNOSTIC
1494 	if (ipprintfs)
1495 		printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1496 #endif
1497 
1498 	/*
1499 	 * Copy option fields and padding (nop) to mbuf.
1500 	 */
1501 	ip_srcrt.nop = IPOPT_NOP;
1502 	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1503 	(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1504 	    &ip_srcrt.nop, OPTSIZ);
1505 	q = (struct in_addr *)(mtod(m, caddr_t) +
1506 	    sizeof(struct in_addr) + OPTSIZ);
1507 #undef OPTSIZ
1508 	/*
1509 	 * Record return path as an IP source route,
1510 	 * reversing the path (pointers are now aligned).
1511 	 */
1512 	while (p >= ip_srcrt.route) {
1513 #ifdef DIAGNOSTIC
1514 		if (ipprintfs)
1515 			printf(" %lx", (u_long)ntohl(q->s_addr));
1516 #endif
1517 		*q++ = *p--;
1518 	}
1519 	/*
1520 	 * Last hop goes to final destination.
1521 	 */
1522 	*q = ip_srcrt.dst;
1523 #ifdef DIAGNOSTIC
1524 	if (ipprintfs)
1525 		printf(" %lx\n", (u_long)ntohl(q->s_addr));
1526 #endif
1527 	return (m);
1528 }
1529 
1530 /*
1531  * Strip out IP options, at higher
1532  * level protocol in the kernel.
1533  * Second argument is buffer to which options
1534  * will be moved, and return value is their length.
1535  * XXX should be deleted; last arg currently ignored.
1536  */
1537 void
1538 ip_stripoptions(m, mopt)
1539 	register struct mbuf *m;
1540 	struct mbuf *mopt;
1541 {
1542 	register int i;
1543 	struct ip *ip = mtod(m, struct ip *);
1544 	register caddr_t opts;
1545 	int olen;
1546 
1547 	olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1548 	opts = (caddr_t)(ip + 1);
1549 	i = m->m_len - (sizeof (struct ip) + olen);
1550 	bcopy(opts + olen, opts, (unsigned)i);
1551 	m->m_len -= olen;
1552 	if (m->m_flags & M_PKTHDR)
1553 		m->m_pkthdr.len -= olen;
1554 	ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
1555 }
1556 
1557 u_char inetctlerrmap[PRC_NCMDS] = {
1558 	0,		0,		0,		0,
1559 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
1560 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
1561 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
1562 	0,		0,		0,		0,
1563 	ENOPROTOOPT,	ECONNREFUSED
1564 };
1565 
1566 /*
1567  * Forward a packet.  If some error occurs return the sender
1568  * an icmp packet.  Note we can't always generate a meaningful
1569  * icmp message because icmp doesn't have a large enough repertoire
1570  * of codes and types.
1571  *
1572  * If not forwarding, just drop the packet.  This could be confusing
1573  * if ipforwarding was zero but some routing protocol was advancing
1574  * us as a gateway to somewhere.  However, we must let the routing
1575  * protocol deal with that.
1576  *
1577  * The srcrt parameter indicates whether the packet is being forwarded
1578  * via a source route.
1579  */
1580 static void
1581 ip_forward(m, srcrt)
1582 	struct mbuf *m;
1583 	int srcrt;
1584 {
1585 	register struct ip *ip = mtod(m, struct ip *);
1586 	register struct rtentry *rt;
1587 	int error, type = 0, code = 0;
1588 	struct mbuf *mcopy;
1589 	n_long dest;
1590 	struct ifnet *destifp;
1591 #ifdef IPSEC
1592 	struct ifnet dummyifp;
1593 #endif
1594 
1595 	dest = 0;
1596 #ifdef DIAGNOSTIC
1597 	if (ipprintfs)
1598 		printf("forward: src %lx dst %lx ttl %x\n",
1599 		    (u_long)ip->ip_src.s_addr, (u_long)ip->ip_dst.s_addr,
1600 		    ip->ip_ttl);
1601 #endif
1602 
1603 
1604 	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
1605 		ipstat.ips_cantforward++;
1606 		m_freem(m);
1607 		return;
1608 	}
1609 #ifdef IPSTEALTH
1610 	if (!ipstealth) {
1611 #endif
1612 		if (ip->ip_ttl <= IPTTLDEC) {
1613 			icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1614 			    dest, 0);
1615 			return;
1616 		}
1617 #ifdef IPSTEALTH
1618 	}
1619 #endif
1620 
1621 	if (ip_rtaddr(ip->ip_dst) == 0) {
1622 		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1623 		return;
1624 	} else
1625 		rt = ipforward_rt.ro_rt;
1626 
1627 	/*
1628 	 * Save the IP header and at most 8 bytes of the payload,
1629 	 * in case we need to generate an ICMP message to the src.
1630 	 *
1631 	 * We don't use m_copy() because it might return a reference
1632 	 * to a shared cluster. Both this function and ip_output()
1633 	 * assume exclusive access to the IP header in `m', so any
1634 	 * data in a cluster may change before we reach icmp_error().
1635 	 */
1636 	MGET(mcopy, M_DONTWAIT, m->m_type);
1637 	if (mcopy != NULL) {
1638 		M_COPY_PKTHDR(mcopy, m);
1639 		mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8,
1640 		    (int)ip->ip_len);
1641 		m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1642 	}
1643 
1644 #ifdef IPSTEALTH
1645 	if (!ipstealth) {
1646 #endif
1647 		ip->ip_ttl -= IPTTLDEC;
1648 #ifdef IPSTEALTH
1649 	}
1650 #endif
1651 
1652 	/*
1653 	 * If forwarding packet using same interface that it came in on,
1654 	 * perhaps should send a redirect to sender to shortcut a hop.
1655 	 * Only send redirect if source is sending directly to us,
1656 	 * and if packet was not source routed (or has any options).
1657 	 * Also, don't send redirect if forwarding using a default route
1658 	 * or a route modified by a redirect.
1659 	 */
1660 #define	satosin(sa)	((struct sockaddr_in *)(sa))
1661 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1662 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1663 	    satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1664 	    ipsendredirects && !srcrt) {
1665 #define	RTA(rt)	((struct in_ifaddr *)(rt->rt_ifa))
1666 		u_long src = ntohl(ip->ip_src.s_addr);
1667 
1668 		if (RTA(rt) &&
1669 		    (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1670 		    if (rt->rt_flags & RTF_GATEWAY)
1671 			dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1672 		    else
1673 			dest = ip->ip_dst.s_addr;
1674 		    /* Router requirements says to only send host redirects */
1675 		    type = ICMP_REDIRECT;
1676 		    code = ICMP_REDIRECT_HOST;
1677 #ifdef DIAGNOSTIC
1678 		    if (ipprintfs)
1679 		        printf("redirect (%d) to %lx\n", code, (u_long)dest);
1680 #endif
1681 		}
1682 	}
1683 
1684 	error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
1685 			  IP_FORWARDING, 0);
1686 	if (error)
1687 		ipstat.ips_cantforward++;
1688 	else {
1689 		ipstat.ips_forward++;
1690 		if (type)
1691 			ipstat.ips_redirectsent++;
1692 		else {
1693 			if (mcopy) {
1694 				ipflow_create(&ipforward_rt, mcopy);
1695 				m_freem(mcopy);
1696 			}
1697 			return;
1698 		}
1699 	}
1700 	if (mcopy == NULL)
1701 		return;
1702 	destifp = NULL;
1703 
1704 	switch (error) {
1705 
1706 	case 0:				/* forwarded, but need redirect */
1707 		/* type, code set above */
1708 		break;
1709 
1710 	case ENETUNREACH:		/* shouldn't happen, checked above */
1711 	case EHOSTUNREACH:
1712 	case ENETDOWN:
1713 	case EHOSTDOWN:
1714 	default:
1715 		type = ICMP_UNREACH;
1716 		code = ICMP_UNREACH_HOST;
1717 		break;
1718 
1719 	case EMSGSIZE:
1720 		type = ICMP_UNREACH;
1721 		code = ICMP_UNREACH_NEEDFRAG;
1722 #ifndef IPSEC
1723 		if (ipforward_rt.ro_rt)
1724 			destifp = ipforward_rt.ro_rt->rt_ifp;
1725 #else
1726 		/*
1727 		 * If the packet is routed over IPsec tunnel, tell the
1728 		 * originator the tunnel MTU.
1729 		 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1730 		 * XXX quickhack!!!
1731 		 */
1732 		if (ipforward_rt.ro_rt) {
1733 			struct secpolicy *sp = NULL;
1734 			int ipsecerror;
1735 			int ipsechdr;
1736 			struct route *ro;
1737 
1738 			sp = ipsec4_getpolicybyaddr(mcopy,
1739 						    IPSEC_DIR_OUTBOUND,
1740 			                            IP_FORWARDING,
1741 			                            &ipsecerror);
1742 
1743 			if (sp == NULL)
1744 				destifp = ipforward_rt.ro_rt->rt_ifp;
1745 			else {
1746 				/* count IPsec header size */
1747 				ipsechdr = ipsec4_hdrsiz(mcopy,
1748 							 IPSEC_DIR_OUTBOUND,
1749 							 NULL);
1750 
1751 				/*
1752 				 * find the correct route for outer IPv4
1753 				 * header, compute tunnel MTU.
1754 				 *
1755 				 * XXX BUG ALERT
1756 				 * The "dummyifp" code relies upon the fact
1757 				 * that icmp_error() touches only ifp->if_mtu.
1758 				 */
1759 				/*XXX*/
1760 				destifp = NULL;
1761 				if (sp->req != NULL
1762 				 && sp->req->sav != NULL
1763 				 && sp->req->sav->sah != NULL) {
1764 					ro = &sp->req->sav->sah->sa_route;
1765 					if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1766 						dummyifp.if_mtu =
1767 						    ro->ro_rt->rt_ifp->if_mtu;
1768 						dummyifp.if_mtu -= ipsechdr;
1769 						destifp = &dummyifp;
1770 					}
1771 				}
1772 
1773 				key_freesp(sp);
1774 			}
1775 		}
1776 #endif /*IPSEC*/
1777 		ipstat.ips_cantfrag++;
1778 		break;
1779 
1780 	case ENOBUFS:
1781 		type = ICMP_SOURCEQUENCH;
1782 		code = 0;
1783 		break;
1784 
1785 	case EACCES:			/* ipfw denied packet */
1786 		m_freem(mcopy);
1787 		return;
1788 	}
1789 	icmp_error(mcopy, type, code, dest, destifp);
1790 }
1791 
1792 void
1793 ip_savecontrol(inp, mp, ip, m)
1794 	register struct inpcb *inp;
1795 	register struct mbuf **mp;
1796 	register struct ip *ip;
1797 	register struct mbuf *m;
1798 {
1799 	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
1800 		struct timeval tv;
1801 
1802 		microtime(&tv);
1803 		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
1804 			SCM_TIMESTAMP, SOL_SOCKET);
1805 		if (*mp)
1806 			mp = &(*mp)->m_next;
1807 	}
1808 	if (inp->inp_flags & INP_RECVDSTADDR) {
1809 		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
1810 		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
1811 		if (*mp)
1812 			mp = &(*mp)->m_next;
1813 	}
1814 #ifdef notyet
1815 	/* XXX
1816 	 * Moving these out of udp_input() made them even more broken
1817 	 * than they already were.
1818 	 */
1819 	/* options were tossed already */
1820 	if (inp->inp_flags & INP_RECVOPTS) {
1821 		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
1822 		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
1823 		if (*mp)
1824 			mp = &(*mp)->m_next;
1825 	}
1826 	/* ip_srcroute doesn't do what we want here, need to fix */
1827 	if (inp->inp_flags & INP_RECVRETOPTS) {
1828 		*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
1829 		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
1830 		if (*mp)
1831 			mp = &(*mp)->m_next;
1832 	}
1833 #endif
1834 	if (inp->inp_flags & INP_RECVIF) {
1835 		struct ifnet *ifp;
1836 		struct sdlbuf {
1837 			struct sockaddr_dl sdl;
1838 			u_char	pad[32];
1839 		} sdlbuf;
1840 		struct sockaddr_dl *sdp;
1841 		struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
1842 
1843 		if (((ifp = m->m_pkthdr.rcvif))
1844 		&& ( ifp->if_index && (ifp->if_index <= if_index))) {
1845 			sdp = (struct sockaddr_dl *)
1846 			    (ifaddr_byindex(ifp->if_index)->ifa_addr);
1847 			/*
1848 			 * Change our mind and don't try copy.
1849 			 */
1850 			if ((sdp->sdl_family != AF_LINK)
1851 			|| (sdp->sdl_len > sizeof(sdlbuf))) {
1852 				goto makedummy;
1853 			}
1854 			bcopy(sdp, sdl2, sdp->sdl_len);
1855 		} else {
1856 makedummy:
1857 			sdl2->sdl_len
1858 				= offsetof(struct sockaddr_dl, sdl_data[0]);
1859 			sdl2->sdl_family = AF_LINK;
1860 			sdl2->sdl_index = 0;
1861 			sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
1862 		}
1863 		*mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
1864 			IP_RECVIF, IPPROTO_IP);
1865 		if (*mp)
1866 			mp = &(*mp)->m_next;
1867 	}
1868 }
1869 
1870 int
1871 ip_rsvp_init(struct socket *so)
1872 {
1873 	if (so->so_type != SOCK_RAW ||
1874 	    so->so_proto->pr_protocol != IPPROTO_RSVP)
1875 	  return EOPNOTSUPP;
1876 
1877 	if (ip_rsvpd != NULL)
1878 	  return EADDRINUSE;
1879 
1880 	ip_rsvpd = so;
1881 	/*
1882 	 * This may seem silly, but we need to be sure we don't over-increment
1883 	 * the RSVP counter, in case something slips up.
1884 	 */
1885 	if (!ip_rsvp_on) {
1886 		ip_rsvp_on = 1;
1887 		rsvp_on++;
1888 	}
1889 
1890 	return 0;
1891 }
1892 
1893 int
1894 ip_rsvp_done(void)
1895 {
1896 	ip_rsvpd = NULL;
1897 	/*
1898 	 * This may seem silly, but we need to be sure we don't over-decrement
1899 	 * the RSVP counter, in case something slips up.
1900 	 */
1901 	if (ip_rsvp_on) {
1902 		ip_rsvp_on = 0;
1903 		rsvp_on--;
1904 	}
1905 	return 0;
1906 }
1907