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source: rtems/cpukit/libnetworking/netinet/ip_icmp.c @ 2a94c85

4.104.114.84.95

Last change on this file since 2a94c85 was 2a94c85, checked in by Eric Norum <WENorum@…>, on 05/24/05 at 00:36:35
Add "ICMP panic avoided" diagnostic counter.
Property mode set to `100644`
File size: 18.4 KB

Line
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	* 4. Neither the name of the University nor the names of its contributors
14	* may be used to endorse or promote products derived from this software
15	* without specific prior written permission.
16	*
17	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27	* SUCH DAMAGE.
28	*
29	* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
30	* $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.101 2005/05/04 13:23:54 andre Exp $
31	*/
32
33	/*
34	* $Id$
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/protosw.h>
42	#include <sys/socket.h>
43	#include <sys/time.h>
44	#include <sys/kernel.h>
45	#include <sys/socket.h>
46	#include <sys/sysctl.h>
47
48	#include <net/if.h>
49	#include <net/route.h>
50
51	#define _IP_VHL
52	#include <netinet/in.h>
53	#include <netinet/in_systm.h>
54	#include <netinet/in_var.h>
55	#include <netinet/ip.h>
56	#include <netinet/ip_icmp.h>
57	#include <netinet/ip_var.h>
58	#include <netinet/icmp_var.h>
59
60	#ifdef IPSEC
61	#include <netinet6/ipsec.h>
62	#include <netkey/key.h>
63	#endif
64
65	#ifdef FAST_IPSEC
66	#include <netipsec/ipsec.h>
67	#include <netipsec/key.h>
68	#define IPSEC
69	#endif
70
71	#include <machine/in_cksum.h>
72
73	/*
74	* ICMP routines: error generation, receive packet processing, and
75	* routines to turnaround packets back to the originator, and
76	* host table maintenance routines.
77	*/
78
79	struct icmpstat icmpstat;
80	SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RD,
81	&icmpstat, icmpstat, "");
82
83	static int icmpmaskrepl = 0;
84	SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
85	&icmpmaskrepl, 0, "");
86
87	static int icmpbmcastecho = 1;
88	SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, &icmpbmcastecho,
89	0, "");
90
91	/* #define ICMPPRINTFS 1 */
92	#ifdef ICMPPRINTFS
93	int icmpprintfs = 0;
94	#endif
95
96	static void icmp_reflect(struct mbuf *);
97	static void icmp_send(struct mbuf , struct mbuf );
98
99	extern struct protosw inetsw[];
100	unsigned int icmplenPanicAvoided;
101
102	/*
103	* Generate an error packet of type error
104	* in response to bad packet ip.
105	*/
106	void
107	icmp_error(n, type, code, dest, destifp)
108	struct mbuf *n;
109	int type, code;
110	n_long dest;
111	struct ifnet *destifp;
112	{
113	register struct ip oip = mtod(n, struct ip ), *nip;
114	register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
115	register struct icmp *icp;
116	register struct mbuf *m;
117	unsigned icmplen;
118
119	#ifdef ICMPPRINTFS
120	if (icmpprintfs)
121	printf("icmp_error(%p, %x, %d)\n", oip, type, code);
122	#endif
123	if (type != ICMP_REDIRECT)
124	icmpstat.icps_error++;
125	/*
126	* Don't send error if not the first fragment of message.
127	* Don't error if the old packet protocol was ICMP
128	* error message, only known informational types.
129	*/
130	if (oip->ip_off &~ (IP_MF\|IP_DF))
131	goto freeit;
132	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
133	n->m_len >= oiplen + ICMP_MINLEN &&
134	!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
135	icmpstat.icps_oldicmp++;
136	goto freeit;
137	}
138	/* Don't send error in response to a multicast or broadcast packet */
139	if (n->m_flags & (M_BCAST\|M_MCAST))
140	goto freeit;
141	/* Don't send error in response to malicious packet */
142	icmplen = min(oiplen + 8, oip->ip_len);
143	if (icmplen < sizeof(struct ip)) {
144	icmplenPanicAvoided++;
145	goto freeit;
146	}
147
148	/*
149	* First, formulate icmp message
150	*/
151	m = m_gethdr(M_DONTWAIT, MT_HEADER);
152	if (m == NULL)
153	goto freeit;
154	#ifdef MAC
155	mac_create_mbuf_netlayer(n, m);
156	#endif
157	m->m_len = icmplen + ICMP_MINLEN;
158	MH_ALIGN(m, m->m_len);
159	icp = mtod(m, struct icmp *);
160	if ((u_int)type > ICMP_MAXTYPE)
161	panic("icmp_error");
162	icmpstat.icps_outhist[type]++;
163	icp->icmp_type = type;
164	if (type == ICMP_REDIRECT)
165	icp->icmp_gwaddr.s_addr = dest;
166	else {
167	icp->icmp_void = 0;
168	/*
169	* The following assignments assume an overlay with the
170	* zeroed icmp_void field.
171	*/
172	if (type == ICMP_PARAMPROB) {
173	icp->icmp_pptr = code;
174	code = 0;
175	} else if (type == ICMP_UNREACH &&
176	code == ICMP_UNREACH_NEEDFRAG && destifp) {
177	icp->icmp_nextmtu = htons(destifp->if_mtu);
178	}
179	}
180
181	icp->icmp_code = code;
182	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
183	nip = &icp->icmp_ip;
184	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
185
186	/*
187	* Now, copy old ip header (without options)
188	* in front of icmp message.
189	*/
190	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
191	panic("icmp len");
192	m->m_data -= sizeof(struct ip);
193	m->m_len += sizeof(struct ip);
194	m->m_pkthdr.len = m->m_len;
195	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
196	nip = mtod(m, struct ip *);
197	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
198	nip->ip_len = m->m_len;
199	nip->ip_vhl = IP_VHL_BORING;
200	nip->ip_p = IPPROTO_ICMP;
201	nip->ip_tos = 0;
202	icmp_reflect(m);
203
204	freeit:
205	m_freem(n);
206	}
207
208	static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
209	static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
210	static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
211
212	/*
213	* Process a received ICMP message.
214	*/
215	void
216	icmp_input(m, off)
217	struct mbuf *m;
218	int off;
219	{
220	struct icmp *icp;
221	struct in_ifaddr *ia;
222	struct ip ip = mtod(m, struct ip );
223	int hlen = off;
224	int icmplen = ip->ip_len;
225	int i, code;
226	void (ctlfunc)(int, struct sockaddr , void *);
227
228	/*
229	* Locate icmp structure in mbuf, and check
230	* that not corrupted and of at least minimum length.
231	*/
232	#ifdef ICMPPRINTFS
233	if (icmpprintfs) {
234	char buf[4 * sizeof "123"];
235	strcpy(buf, inet_ntoa(ip->ip_src));
236	printf("icmp_input from %s to %s, len %d\n",
237	buf, inet_ntoa(ip->ip_dst), icmplen);
238	}
239	#endif
240	if (icmplen < ICMP_MINLEN) {
241	icmpstat.icps_tooshort++;
242	goto freeit;
243	}
244	i = hlen + min(icmplen, ICMP_ADVLENMIN);
245	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
246	icmpstat.icps_tooshort++;
247	return;
248	}
249	ip = mtod(m, struct ip *);
250	m->m_len -= hlen;
251	m->m_data += hlen;
252	icp = mtod(m, struct icmp *);
253	if (in_cksum(m, icmplen)) {
254	icmpstat.icps_checksum++;
255	goto freeit;
256	}
257	m->m_len += hlen;
258	m->m_data -= hlen;
259
260	#ifdef ICMPPRINTFS
261	if (icmpprintfs)
262	printf("icmp_input, type %d code %d\n", icp->icmp_type,
263	icp->icmp_code);
264	#endif
265
266	/*
267	* Message type specific processing.
268	*/
269	if (icp->icmp_type > ICMP_MAXTYPE)
270	goto raw;
271	icmpstat.icps_inhist[icp->icmp_type]++;
272	code = icp->icmp_code;
273	switch (icp->icmp_type) {
274
275	case ICMP_UNREACH:
276	switch (code) {
277	case ICMP_UNREACH_NET:
278	case ICMP_UNREACH_HOST:
279	case ICMP_UNREACH_PROTOCOL:
280	case ICMP_UNREACH_PORT:
281	case ICMP_UNREACH_SRCFAIL:
282	code = PRC_UNREACH_NET;
283	break;
284
285	case ICMP_UNREACH_NEEDFRAG:
286	code = PRC_MSGSIZE;
287	break;
288
289	case ICMP_UNREACH_NET_UNKNOWN:
290	case ICMP_UNREACH_NET_PROHIB:
291	case ICMP_UNREACH_TOSNET:
292	code = PRC_UNREACH_NET;
293	break;
294
295	case ICMP_UNREACH_HOST_UNKNOWN:
296	case ICMP_UNREACH_ISOLATED:
297	case ICMP_UNREACH_HOST_PROHIB:
298	case ICMP_UNREACH_TOSHOST:
299	code = PRC_UNREACH_HOST;
300	break;
301
302	case ICMP_UNREACH_FILTER_PROHIB:
303	case ICMP_UNREACH_HOST_PRECEDENCE:
304	case ICMP_UNREACH_PRECEDENCE_CUTOFF:
305	code = PRC_UNREACH_PORT;
306	break;
307
308	default:
309	goto badcode;
310	}
311	goto deliver;
312
313	case ICMP_TIMXCEED:
314	if (code > 1)
315	goto badcode;
316	code += PRC_TIMXCEED_INTRANS;
317	goto deliver;
318
319	case ICMP_PARAMPROB:
320	if (code > 1)
321	goto badcode;
322	code = PRC_PARAMPROB;
323	goto deliver;
324
325	case ICMP_SOURCEQUENCH:
326	if (code)
327	goto badcode;
328	code = PRC_QUENCH;
329	deliver:
330	/*
331	* Problem with datagram; advise higher level routines.
332	*/
333	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
334	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
335	icmpstat.icps_badlen++;
336	goto freeit;
337	}
338	NTOHS(icp->icmp_ip.ip_len);
339	/* Discard ICMP's in response to multicast packets */
340	if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
341	goto badcode;
342	#ifdef ICMPPRINTFS
343	if (icmpprintfs)
344	printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
345	#endif
346	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
347	#if 1
348	/*
349	* MTU discovery:
350	* If we got a needfrag and there is a host route to the
351	* original destination, and the MTU is not locked, then
352	* set the MTU in the route to the suggested new value
353	* (if given) and then notify as usual. The ULPs will
354	* notice that the MTU has changed and adapt accordingly.
355	* If no new MTU was suggested, then we guess a new one
356	* less than the current value. If the new MTU is
357	* unreasonably small (arbitrarily set at 296), then
358	* we reset the MTU to the interface value and enable the
359	* lock bit, indicating that we are no longer doing MTU
360	* discovery.
361	*/
362	if (code == PRC_MSGSIZE) {
363	struct rtentry *rt;
364	int mtu;
365
366	rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
367	RTF_CLONING \| RTF_PRCLONING);
368	if (rt && (rt->rt_flags & RTF_HOST)
369	&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
370	mtu = ntohs(icp->icmp_nextmtu);
371	if (!mtu)
372	mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
373	1);
374	#ifdef DEBUG_MTUDISC
375	printf("MTU for %s reduced to %d\n",
376	inet_ntoa(icmpsrc.sin_addr), mtu);
377	#endif
378	if (mtu < 296) {
379	/* rt->rt_rmx.rmx_mtu =
380	rt->rt_ifp->if_mtu; */
381	rt->rt_rmx.rmx_locks \|= RTV_MTU;
382	} else if (rt->rt_rmx.rmx_mtu > mtu) {
383	rt->rt_rmx.rmx_mtu = mtu;
384	}
385	}
386	if (rt)
387	RTFREE(rt);
388	}
389
390	#endif
391	ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
392	if (ctlfunc)
393	(ctlfunc)(code, (struct sockaddr )&icmpsrc,
394	(void *)&icp->icmp_ip);
395	break;
396
397	badcode:
398	icmpstat.icps_badcode++;
399	break;
400
401	case ICMP_ECHO:
402	if (!icmpbmcastecho
403	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
404	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
405	icmpstat.icps_bmcastecho++;
406	break;
407	}
408	icp->icmp_type = ICMP_ECHOREPLY;
409	goto reflect;
410
411	case ICMP_TSTAMP:
412	if (!icmpbmcastecho
413	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
414	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
415	icmpstat.icps_bmcasttstamp++;
416	break;
417	}
418	if (icmplen < ICMP_TSLEN) {
419	icmpstat.icps_badlen++;
420	break;
421	}
422	icp->icmp_type = ICMP_TSTAMPREPLY;
423	icp->icmp_rtime = iptime();
424	icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
425	goto reflect;
426
427	case ICMP_MASKREQ:
428	#define satosin(sa) ((struct sockaddr_in *)(sa))
429	if (icmpmaskrepl == 0)
430	break;
431	/*
432	* We are not able to respond with all ones broadcast
433	* unless we receive it over a point-to-point interface.
434	*/
435	if (icmplen < ICMP_MASKLEN)
436	break;
437	switch (ip->ip_dst.s_addr) {
438
439	case INADDR_BROADCAST:
440	case INADDR_ANY:
441	icmpdst.sin_addr = ip->ip_src;
442	break;
443
444	default:
445	icmpdst.sin_addr = ip->ip_dst;
446	}
447	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
448	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
449	if (ia == 0)
450	break;
451	if (ia->ia_ifp == 0)
452	break;
453	icp->icmp_type = ICMP_MASKREPLY;
454	icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
455	if (ip->ip_src.s_addr == 0) {
456	if (ia->ia_ifp->if_flags & IFF_BROADCAST)
457	ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
458	else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
459	ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
460	}
461	reflect:
462	ip->ip_len += hlen; /* since ip_input deducts this */
463	icmpstat.icps_reflect++;
464	icmpstat.icps_outhist[icp->icmp_type]++;
465	icmp_reflect(m);
466	return;
467
468	case ICMP_REDIRECT:
469	if (code > 3)
470	goto badcode;
471	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
472	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
473	icmpstat.icps_badlen++;
474	break;
475	}
476	/*
477	* Short circuit routing redirects to force
478	* immediate change in the kernel's routing
479	* tables. The message is also handed to anyone
480	* listening on a raw socket (e.g. the routing
481	* daemon for use in updating its tables).
482	*/
483	icmpgw.sin_addr = ip->ip_src;
484	icmpdst.sin_addr = icp->icmp_gwaddr;
485	#ifdef ICMPPRINTFS
486	if (icmpprintfs) {
487	char buf[4 * sizeof "123"];
488	strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
489
490	printf("redirect dst %s to %s\n",
491	buf, inet_ntoa(icp->icmp_gwaddr));
492	}
493	#endif
494	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
495	rtredirect((struct sockaddr *)&icmpsrc,
496	(struct sockaddr *)&icmpdst,
497	(struct sockaddr *)0, RTF_GATEWAY \| RTF_HOST,
498	(struct sockaddr )&icmpgw, (struct rtentry *)0);
499	pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
500	break;
501
502	/*
503	* No kernel processing for the following;
504	* just fall through to send to raw listener.
505	*/
506	case ICMP_ECHOREPLY:
507	case ICMP_ROUTERADVERT:
508	case ICMP_ROUTERSOLICIT:
509	case ICMP_TSTAMPREPLY:
510	case ICMP_IREQREPLY:
511	case ICMP_MASKREPLY:
512	default:
513	break;
514	}
515
516	raw:
517	rip_input(m, hlen);
518	return;
519
520	freeit:
521	m_freem(m);
522	}
523
524	/*
525	* Reflect the ip packet back to the source
526	*/
527	static void
528	icmp_reflect(m)
529	struct mbuf *m;
530	{
531	struct ip ip = mtod(m, struct ip );
532	struct in_ifaddr *ia;
533	struct in_addr t;
534	struct mbuf *opts = 0;
535	int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
536
537	if (!in_canforward(ip->ip_src) &&
538	((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
539	(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
540	m_freem(m); /* Bad return address */
541	goto done; /* Ip_output() will check for broadcast */
542	}
543	t = ip->ip_dst;
544	ip->ip_dst = ip->ip_src;
545	/*
546	* If the incoming packet was addressed directly to us,
547	* use dst as the src for the reply. Otherwise (broadcast
548	* or anonymous), use the address which corresponds
549	* to the incoming interface.
550	*/
551	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
552	if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
553	break;
554	if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
555	t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
556	break;
557	}
558	icmpdst.sin_addr = t;
559	if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
560	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
561	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
562	/*
563	* The following happens if the packet was not addressed to us,
564	* and was received on an interface with no IP address.
565	*/
566	if (ia == (struct in_ifaddr *)0)
567	ia = in_ifaddr;
568	t = IA_SIN(ia)->sin_addr;
569	ip->ip_src = t;
570	ip->ip_ttl = MAXTTL;
571
572	if (optlen > 0) {
573	register u_char *cp;
574	int opt, cnt;
575	u_int len;
576
577	/*
578	* Retrieve any source routing from the incoming packet;
579	* add on any record-route or timestamp options.
580	*/
581	cp = (u_char *) (ip + 1);
582	if ((opts = ip_srcroute()) == 0 &&
583	(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
584	opts->m_len = sizeof(struct in_addr);
585	mtod(opts, struct in_addr *)->s_addr = 0;
586	}
587	if (opts) {
588	#ifdef ICMPPRINTFS
589	if (icmpprintfs)
590	printf("icmp_reflect optlen %d rt %d => ",
591	optlen, opts->m_len);
592	#endif
593	for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
594	opt = cp[IPOPT_OPTVAL];
595	if (opt == IPOPT_EOL)
596	break;
597	if (opt == IPOPT_NOP)
598	len = 1;
599	else {
600	if (cnt < IPOPT_OLEN + sizeof(*cp))
601	break;
602	len = cp[IPOPT_OLEN];
603	if (len < IPOPT_OLEN + sizeof(*cp) \|\|
604	len > cnt)
605	break;
606	}
607	/*
608	* Should check for overflow, but it "can't happen"
609	*/
610	if (opt == IPOPT_RR \|\| opt == IPOPT_TS \|\|
611	opt == IPOPT_SECURITY) {
612	bcopy((caddr_t)cp,
613	mtod(opts, caddr_t) + opts->m_len, len);
614	opts->m_len += len;
615	}
616	}
617	/* Terminate & pad, if necessary */
618	cnt = opts->m_len % 4;
619	if (cnt) {
620	for (; cnt < 4; cnt++) {
621	*(mtod(opts, caddr_t) + opts->m_len) =
622	IPOPT_EOL;
623	opts->m_len++;
624	}
625	}
626	#ifdef ICMPPRINTFS
627	if (icmpprintfs)
628	printf("%d\n", opts->m_len);
629	#endif
630	}
631	/*
632	* Now strip out original options by copying rest of first
633	* mbuf's data back, and adjust the IP length.
634	*/
635	ip->ip_len -= optlen;
636	ip->ip_vhl = IP_VHL_BORING;
637	m->m_len -= optlen;
638	if (m->m_flags & M_PKTHDR)
639	m->m_pkthdr.len -= optlen;
640	optlen += sizeof(struct ip);
641	bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
642	(unsigned)(m->m_len - sizeof(struct ip)));
643	}
644	m->m_flags &= ~(M_BCAST\|M_MCAST);
645	icmp_send(m, opts);
646	done:
647	if (opts)
648	(void)m_free(opts);
649	}
650
651	/*
652	* Send an icmp packet back to the ip level,
653	* after supplying a checksum.
654	*/
655	static void
656	icmp_send(m, opts)
657	register struct mbuf *m;
658	struct mbuf *opts;
659	{
660	register struct ip ip = mtod(m, struct ip );
661	register int hlen;
662	register struct icmp *icp;
663	struct route ro;
664
665	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
666	m->m_data += hlen;
667	m->m_len -= hlen;
668	icp = mtod(m, struct icmp *);
669	icp->icmp_cksum = 0;
670	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
671	m->m_data -= hlen;
672	m->m_len += hlen;
673	#ifdef ICMPPRINTFS
674	if (icmpprintfs) {
675	char buf[4 * sizeof "123"];
676	strcpy(buf, inet_ntoa(ip->ip_dst));
677	printf("icmp_send dst %s src %s\n",
678	buf, inet_ntoa(ip->ip_src));
679	}
680	#endif
681	bzero(&ro, sizeof ro);
682	(void) ip_output(m, opts, &ro, 0, NULL);
683	if (ro.ro_rt)
684	RTFREE(ro.ro_rt);
685	}
686
687	n_time
688	iptime()
689	{
690	struct timeval atv;
691	u_long t;
692
693	microtime(&atv);
694	t = (atv.tv_sec % (246060)) * 1000 + atv.tv_usec / 1000;
695	return (htonl(t));
696	}
697
698	/*
699	* Return the next larger or smaller MTU plateau (table from RFC 1191)
700	* given current value MTU. If DIR is less than zero, a larger plateau
701	* is returned; otherwise, a smaller value is returned.
702	*/
703	int
704	ip_next_mtu(mtu, dir)
705	int mtu;
706	int dir;
707	{
708	static int mtutab[] = {
709	65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
710	296, 68, 0
711	};
712	int i;
713
714	for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
715	if (mtu >= mtutab[i])
716	break;
717	}
718
719	if (dir < 0) {
720	if (i == 0) {
721	return 0;
722	} else {
723	return mtutab[i - 1];
724	}
725	} else {
726	if (mtutab[i] == 0) {
727	return 0;
728	} else if(mtu > mtutab[i]) {
729	return mtutab[i];
730	} else {
731	return mtutab[i + 1];
732	}
733	}
734	}

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