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source: rtems/cpukit/libnetworking/netinet/ip_icmp.c @ dd967330

4.104.114.95

Last change on this file since dd967330 was dd967330, checked in by Ralf Corsepius <ralf.corsepius@…>, on 09/01/08 at 06:36:17
Stop using old-style function definitions.
Property mode set to `100644`
File size: 19.0 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	static int icmpallecho = 1;
92	SYSCTL_INT(_net_inet_icmp, OID_AUTO, allecho, CTLFLAG_RW, &icmpallecho,
93	0, "");
94
95	/* #define ICMPPRINTFS 1 */
96	#ifdef ICMPPRINTFS
97	int icmpprintfs = 0;
98	#endif
99
100	static void icmp_reflect(struct mbuf *);
101	static void icmp_send(struct mbuf , struct mbuf );
102
103	extern struct protosw inetsw[];
104	unsigned int icmplenPanicAvoided;
105
106	/*
107	* Generate an error packet of type error
108	* in response to bad packet ip.
109	*/
110	void
111	icmp_error(struct mbuf *n, int type, int code, n_long dest,
112	struct ifnet *destifp)
113	{
114	register struct ip oip = mtod(n, struct ip ), *nip;
115	#ifdef _IP_VHL
116	register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
117	#else
118	register unsigned oiplen = oip->ip_hl << 2;
119	#endif
120	register struct icmp *icp;
121	register struct mbuf *m;
122	unsigned icmplen;
123
124	#ifdef ICMPPRINTFS
125	if (icmpprintfs)
126	printf("icmp_error(%p, %x, %d)\n", oip, type, code);
127	#endif
128	if (type != ICMP_REDIRECT)
129	icmpstat.icps_error++;
130	/*
131	* Don't send error if not the first fragment of message.
132	* Don't error if the old packet protocol was ICMP
133	* error message, only known informational types.
134	*/
135	if (oip->ip_off &~ (IP_MF\|IP_DF))
136	goto freeit;
137	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
138	n->m_len >= oiplen + ICMP_MINLEN &&
139	!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
140	icmpstat.icps_oldicmp++;
141	goto freeit;
142	}
143	/* Don't send error in response to a multicast or broadcast packet */
144	if (n->m_flags & (M_BCAST\|M_MCAST))
145	goto freeit;
146	/* Don't send error in response to malicious packet */
147	icmplen = min(oiplen + 8, oip->ip_len);
148	if (icmplen < sizeof(struct ip)) {
149	icmplenPanicAvoided++;
150	goto freeit;
151	}
152
153	/*
154	* First, formulate icmp message
155	*/
156	m = m_gethdr(M_DONTWAIT, MT_HEADER);
157	if (m == NULL)
158	goto freeit;
159	#ifdef MAC
160	mac_create_mbuf_netlayer(n, m);
161	#endif
162	m->m_len = icmplen + ICMP_MINLEN;
163	MH_ALIGN(m, m->m_len);
164	icp = mtod(m, struct icmp *);
165	if ((u_int)type > ICMP_MAXTYPE)
166	panic("icmp_error");
167	icmpstat.icps_outhist[type]++;
168	icp->icmp_type = type;
169	if (type == ICMP_REDIRECT)
170	icp->icmp_gwaddr.s_addr = dest;
171	else {
172	icp->icmp_void = 0;
173	/*
174	* The following assignments assume an overlay with the
175	* zeroed icmp_void field.
176	*/
177	if (type == ICMP_PARAMPROB) {
178	icp->icmp_pptr = code;
179	code = 0;
180	} else if (type == ICMP_UNREACH &&
181	code == ICMP_UNREACH_NEEDFRAG && destifp) {
182	icp->icmp_nextmtu = htons(destifp->if_mtu);
183	}
184	}
185
186	icp->icmp_code = code;
187	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
188	nip = &icp->icmp_ip;
189	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
190
191	/*
192	* Now, copy old ip header (without options)
193	* in front of icmp message.
194	*/
195	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
196	panic("icmp len");
197	m->m_data -= sizeof(struct ip);
198	m->m_len += sizeof(struct ip);
199	m->m_pkthdr.len = m->m_len;
200	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
201	nip = mtod(m, struct ip *);
202	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
203	nip->ip_len = m->m_len;
204	#ifdef _IP_VHL
205	nip->ip_vhl = IP_VHL_BORING;
206	#else
207	nip->ip_v = IPVERSION;
208	nip->ip_hl = 5;
209	#endif
210	nip->ip_p = IPPROTO_ICMP;
211	nip->ip_tos = 0;
212	icmp_reflect(m);
213
214	freeit:
215	m_freem(n);
216	}
217
218	static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
219	static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
220	static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
221
222	/*
223	* Process a received ICMP message.
224	*/
225	void
226	icmp_input(struct mbuf *m, int off)
227	{
228	struct icmp *icp;
229	struct in_ifaddr *ia;
230	struct ip ip = mtod(m, struct ip );
231	int hlen = off;
232	int icmplen = ip->ip_len;
233	int i, code;
234	void (ctlfunc)(int, struct sockaddr , void *);
235
236	/*
237	* Locate icmp structure in mbuf, and check
238	* that not corrupted and of at least minimum length.
239	*/
240	#ifdef ICMPPRINTFS
241	if (icmpprintfs) {
242	char buf[4 * sizeof "123"];
243	strcpy(buf, inet_ntoa(ip->ip_src));
244	printf("icmp_input from %s to %s, len %d\n",
245	buf, inet_ntoa(ip->ip_dst), icmplen);
246	}
247	#endif
248	if (icmplen < ICMP_MINLEN) {
249	icmpstat.icps_tooshort++;
250	goto freeit;
251	}
252	i = hlen + min(icmplen, ICMP_ADVLENMIN);
253	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
254	icmpstat.icps_tooshort++;
255	return;
256	}
257	ip = mtod(m, struct ip *);
258	m->m_len -= hlen;
259	m->m_data += hlen;
260	icp = mtod(m, struct icmp *);
261	if (in_cksum(m, icmplen)) {
262	icmpstat.icps_checksum++;
263	goto freeit;
264	}
265	m->m_len += hlen;
266	m->m_data -= hlen;
267
268	#ifdef ICMPPRINTFS
269	if (icmpprintfs)
270	printf("icmp_input, type %d code %d\n", icp->icmp_type,
271	icp->icmp_code);
272	#endif
273
274	/*
275	* Message type specific processing.
276	*/
277	if (icp->icmp_type > ICMP_MAXTYPE)
278	goto raw;
279	icmpstat.icps_inhist[icp->icmp_type]++;
280	code = icp->icmp_code;
281	switch (icp->icmp_type) {
282
283	case ICMP_UNREACH:
284	switch (code) {
285	case ICMP_UNREACH_NET:
286	case ICMP_UNREACH_HOST:
287	case ICMP_UNREACH_PROTOCOL:
288	case ICMP_UNREACH_PORT:
289	case ICMP_UNREACH_SRCFAIL:
290	code = PRC_UNREACH_NET;
291	break;
292
293	case ICMP_UNREACH_NEEDFRAG:
294	code = PRC_MSGSIZE;
295	break;
296
297	case ICMP_UNREACH_NET_UNKNOWN:
298	case ICMP_UNREACH_NET_PROHIB:
299	case ICMP_UNREACH_TOSNET:
300	code = PRC_UNREACH_NET;
301	break;
302
303	case ICMP_UNREACH_HOST_UNKNOWN:
304	case ICMP_UNREACH_ISOLATED:
305	case ICMP_UNREACH_HOST_PROHIB:
306	case ICMP_UNREACH_TOSHOST:
307	code = PRC_UNREACH_HOST;
308	break;
309
310	case ICMP_UNREACH_FILTER_PROHIB:
311	case ICMP_UNREACH_HOST_PRECEDENCE:
312	case ICMP_UNREACH_PRECEDENCE_CUTOFF:
313	code = PRC_UNREACH_PORT;
314	break;
315
316	default:
317	goto badcode;
318	}
319	goto deliver;
320
321	case ICMP_TIMXCEED:
322	if (code > 1)
323	goto badcode;
324	code += PRC_TIMXCEED_INTRANS;
325	goto deliver;
326
327	case ICMP_PARAMPROB:
328	if (code > 1)
329	goto badcode;
330	code = PRC_PARAMPROB;
331	goto deliver;
332
333	case ICMP_SOURCEQUENCH:
334	if (code)
335	goto badcode;
336	code = PRC_QUENCH;
337	deliver:
338	/*
339	* Problem with datagram; advise higher level routines.
340	*/
341	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
342	#ifdef _IP_VHL
343	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
344	#else
345	icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
346	#endif
347	icmpstat.icps_badlen++;
348	goto freeit;
349	}
350	NTOHS(icp->icmp_ip.ip_len);
351	/* Discard ICMP's in response to multicast packets */
352	if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
353	goto badcode;
354	#ifdef ICMPPRINTFS
355	if (icmpprintfs)
356	printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
357	#endif
358	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
359	#if 1
360	/*
361	* MTU discovery:
362	* If we got a needfrag and there is a host route to the
363	* original destination, and the MTU is not locked, then
364	* set the MTU in the route to the suggested new value
365	* (if given) and then notify as usual. The ULPs will
366	* notice that the MTU has changed and adapt accordingly.
367	* If no new MTU was suggested, then we guess a new one
368	* less than the current value. If the new MTU is
369	* unreasonably small (arbitrarily set at 296), then
370	* we reset the MTU to the interface value and enable the
371	* lock bit, indicating that we are no longer doing MTU
372	* discovery.
373	*/
374	if (code == PRC_MSGSIZE) {
375	struct rtentry *rt;
376	int mtu;
377
378	rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
379	RTF_CLONING \| RTF_PRCLONING);
380	if (rt && (rt->rt_flags & RTF_HOST)
381	&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
382	mtu = ntohs(icp->icmp_nextmtu);
383	if (!mtu)
384	mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
385	1);
386	#ifdef DEBUG_MTUDISC
387	printf("MTU for %s reduced to %d\n",
388	inet_ntoa(icmpsrc.sin_addr), mtu);
389	#endif
390	if (mtu < 296) {
391	/* rt->rt_rmx.rmx_mtu =
392	rt->rt_ifp->if_mtu; */
393	rt->rt_rmx.rmx_locks \|= RTV_MTU;
394	} else if (rt->rt_rmx.rmx_mtu > mtu) {
395	rt->rt_rmx.rmx_mtu = mtu;
396	}
397	}
398	if (rt)
399	RTFREE(rt);
400	}
401
402	#endif
403	ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
404	if (ctlfunc)
405	(ctlfunc)(code, (struct sockaddr )&icmpsrc,
406	(void *)&icp->icmp_ip);
407	break;
408
409	badcode:
410	icmpstat.icps_badcode++;
411	break;
412
413	case ICMP_ECHO:
414	if (!icmpallecho) {
415	icmpstat.icps_allecho++;
416	break;
417	}
418	if (!icmpbmcastecho
419	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
420	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
421	icmpstat.icps_bmcastecho++;
422	break;
423	}
424	icp->icmp_type = ICMP_ECHOREPLY;
425	goto reflect;
426
427	case ICMP_TSTAMP:
428	if (!icmpbmcastecho
429	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
430	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
431	icmpstat.icps_bmcasttstamp++;
432	break;
433	}
434	if (icmplen < ICMP_TSLEN) {
435	icmpstat.icps_badlen++;
436	break;
437	}
438	icp->icmp_type = ICMP_TSTAMPREPLY;
439	icp->icmp_rtime = iptime();
440	icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
441	goto reflect;
442
443	case ICMP_MASKREQ:
444	#define satosin(sa) ((struct sockaddr_in *)(sa))
445	if (icmpmaskrepl == 0)
446	break;
447	/*
448	* We are not able to respond with all ones broadcast
449	* unless we receive it over a point-to-point interface.
450	*/
451	if (icmplen < ICMP_MASKLEN)
452	break;
453	switch (ip->ip_dst.s_addr) {
454
455	case INADDR_BROADCAST:
456	case INADDR_ANY:
457	icmpdst.sin_addr = ip->ip_src;
458	break;
459
460	default:
461	icmpdst.sin_addr = ip->ip_dst;
462	}
463	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
464	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
465	if (ia == 0)
466	break;
467	if (ia->ia_ifp == 0)
468	break;
469	icp->icmp_type = ICMP_MASKREPLY;
470	icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
471	if (ip->ip_src.s_addr == 0) {
472	if (ia->ia_ifp->if_flags & IFF_BROADCAST)
473	ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
474	else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
475	ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
476	}
477	reflect:
478	ip->ip_len += hlen; /* since ip_input deducts this */
479	icmpstat.icps_reflect++;
480	icmpstat.icps_outhist[icp->icmp_type]++;
481	icmp_reflect(m);
482	return;
483
484	case ICMP_REDIRECT:
485	if (code > 3)
486	goto badcode;
487	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
488	#ifdef _IP_VHL
489	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
490	#else
491	icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
492	#endif
493	icmpstat.icps_badlen++;
494	break;
495	}
496	/*
497	* Short circuit routing redirects to force
498	* immediate change in the kernel's routing
499	* tables. The message is also handed to anyone
500	* listening on a raw socket (e.g. the routing
501	* daemon for use in updating its tables).
502	*/
503	icmpgw.sin_addr = ip->ip_src;
504	icmpdst.sin_addr = icp->icmp_gwaddr;
505	#ifdef ICMPPRINTFS
506	if (icmpprintfs) {
507	char buf[4 * sizeof "123"];
508	strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
509
510	printf("redirect dst %s to %s\n",
511	buf, inet_ntoa(icp->icmp_gwaddr));
512	}
513	#endif
514	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
515	rtredirect((struct sockaddr *)&icmpsrc,
516	(struct sockaddr *)&icmpdst,
517	(struct sockaddr *)0, RTF_GATEWAY \| RTF_HOST,
518	(struct sockaddr )&icmpgw, (struct rtentry *)0);
519	pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
520	break;
521
522	/*
523	* No kernel processing for the following;
524	* just fall through to send to raw listener.
525	*/
526	case ICMP_ECHOREPLY:
527	case ICMP_ROUTERADVERT:
528	case ICMP_ROUTERSOLICIT:
529	case ICMP_TSTAMPREPLY:
530	case ICMP_IREQREPLY:
531	case ICMP_MASKREPLY:
532	default:
533	break;
534	}
535
536	raw:
537	rip_input(m, hlen);
538	return;
539
540	freeit:
541	m_freem(m);
542	}
543
544	/*
545	* Reflect the ip packet back to the source
546	*/
547	static void
548	icmp_reflect(struct mbuf *m)
549	{
550	struct ip ip = mtod(m, struct ip );
551	struct in_ifaddr *ia;
552	struct in_addr t;
553	struct mbuf *opts = 0;
554	#ifdef _IP_VHL
555	int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
556	#else
557	int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
558	#endif
559	if (!in_canforward(ip->ip_src) &&
560	((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
561	(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
562	m_freem(m); /* Bad return address */
563	goto done; /* Ip_output() will check for broadcast */
564	}
565	t = ip->ip_dst;
566	ip->ip_dst = ip->ip_src;
567	/*
568	* If the incoming packet was addressed directly to us,
569	* use dst as the src for the reply. Otherwise (broadcast
570	* or anonymous), use the address which corresponds
571	* to the incoming interface.
572	*/
573	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
574	if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
575	break;
576	if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
577	t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
578	break;
579	}
580	icmpdst.sin_addr = t;
581	if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
582	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
583	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
584	/*
585	* The following happens if the packet was not addressed to us,
586	* and was received on an interface with no IP address.
587	*/
588	if (ia == (struct in_ifaddr *)0)
589	ia = in_ifaddr;
590	t = IA_SIN(ia)->sin_addr;
591	ip->ip_src = t;
592	ip->ip_ttl = MAXTTL;
593
594	if (optlen > 0) {
595	register u_char *cp;
596	int opt, cnt;
597	u_int len;
598
599	/*
600	* Retrieve any source routing from the incoming packet;
601	* add on any record-route or timestamp options.
602	*/
603	cp = (u_char *) (ip + 1);
604	if ((opts = ip_srcroute()) == 0 &&
605	(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
606	opts->m_len = sizeof(struct in_addr);
607	mtod(opts, struct in_addr *)->s_addr = 0;
608	}
609	if (opts) {
610	#ifdef ICMPPRINTFS
611	if (icmpprintfs)
612	printf("icmp_reflect optlen %d rt %d => ",
613	optlen, opts->m_len);
614	#endif
615	for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
616	opt = cp[IPOPT_OPTVAL];
617	if (opt == IPOPT_EOL)
618	break;
619	if (opt == IPOPT_NOP)
620	len = 1;
621	else {
622	if (cnt < IPOPT_OLEN + sizeof(*cp))
623	break;
624	len = cp[IPOPT_OLEN];
625	if (len < IPOPT_OLEN + sizeof(*cp) \|\|
626	len > cnt)
627	break;
628	}
629	/*
630	* Should check for overflow, but it "can't happen"
631	*/
632	if (opt == IPOPT_RR \|\| opt == IPOPT_TS \|\|
633	opt == IPOPT_SECURITY) {
634	bcopy((caddr_t)cp,
635	mtod(opts, caddr_t) + opts->m_len, len);
636	opts->m_len += len;
637	}
638	}
639	/* Terminate & pad, if necessary */
640	cnt = opts->m_len % 4;
641	if (cnt) {
642	for (; cnt < 4; cnt++) {
643	*(mtod(opts, caddr_t) + opts->m_len) =
644	IPOPT_EOL;
645	opts->m_len++;
646	}
647	}
648	#ifdef ICMPPRINTFS
649	if (icmpprintfs)
650	printf("%d\n", opts->m_len);
651	#endif
652	}
653	/*
654	* Now strip out original options by copying rest of first
655	* mbuf's data back, and adjust the IP length.
656	*/
657	ip->ip_len -= optlen;
658	#ifdef _IP_VHL
659	ip->ip_vhl = IP_VHL_BORING;
660	#else
661	ip->ip_v = IPVERSION;
662	ip->ip_hl = 5;
663	#endif
664	m->m_len -= optlen;
665	if (m->m_flags & M_PKTHDR)
666	m->m_pkthdr.len -= optlen;
667	optlen += sizeof(struct ip);
668	bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
669	(unsigned)(m->m_len - sizeof(struct ip)));
670	}
671	m->m_flags &= ~(M_BCAST\|M_MCAST);
672	icmp_send(m, opts);
673	done:
674	if (opts)
675	(void)m_free(opts);
676	}
677
678	/*
679	* Send an icmp packet back to the ip level,
680	* after supplying a checksum.
681	*/
682	static void
683	icmp_send(struct mbuf m, struct mbuf opts)
684	{
685	register struct ip ip = mtod(m, struct ip );
686	register int hlen;
687	register struct icmp *icp;
688	struct route ro;
689
690	#ifdef _IP_VHL
691	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
692	#else
693	hlen = ip->ip_hl << 2;
694	#endif
695	m->m_data += hlen;
696	m->m_len -= hlen;
697	icp = mtod(m, struct icmp *);
698	icp->icmp_cksum = 0;
699	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
700	m->m_data -= hlen;
701	m->m_len += hlen;
702	#ifdef ICMPPRINTFS
703	if (icmpprintfs) {
704	char buf[4 * sizeof "123"];
705	strcpy(buf, inet_ntoa(ip->ip_dst));
706	printf("icmp_send dst %s src %s\n",
707	buf, inet_ntoa(ip->ip_src));
708	}
709	#endif
710	bzero(&ro, sizeof ro);
711	(void) ip_output(m, opts, &ro, 0, NULL);
712	if (ro.ro_rt)
713	RTFREE(ro.ro_rt);
714	}
715
716	n_time
717	iptime(void)
718	{
719	struct timeval atv;
720	u_long t;
721
722	microtime(&atv);
723	t = (atv.tv_sec % (24L60L60L)) * 1000L + atv.tv_usec / 1000L;
724	return (htonl(t));
725	}
726
727	/*
728	* Return the next larger or smaller MTU plateau (table from RFC 1191)
729	* given current value MTU. If DIR is less than zero, a larger plateau
730	* is returned; otherwise, a smaller value is returned.
731	*/
732	int
733	ip_next_mtu(int mtu, int dir)
734	{
735	static int mtutab[] = {
736	65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
737	296, 68, 0
738	};
739	int i;
740
741	for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
742	if (mtu >= mtutab[i])
743	break;
744	}
745
746	if (dir < 0) {
747	if (i == 0) {
748	return 0;
749	} else {
750	return mtutab[i - 1];
751	}
752	} else {
753	if (mtutab[i] == 0) {
754	return 0;
755	} else if(mtu > mtutab[i]) {
756	return mtutab[i];
757	} else {
758	return mtutab[i + 1];
759	}
760	}
761	}

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