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source: rtems/cpukit/libnetworking/netinet/ip_icmp.c @ 261e743

4.104.114.84.95

Last change on this file since 261e743 was 261e743, checked in by Eric Norum <WENorum@…>, on 05/30/06 at 15:12:54
Add flag to inhibit ICMP replies.
Property mode set to `100644`
File size: 18.5 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(n, type, code, dest, destifp)
112	struct mbuf *n;
113	int type, code;
114	n_long dest;
115	struct ifnet *destifp;
116	{
117	register struct ip oip = mtod(n, struct ip ), *nip;
118	register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
119	register struct icmp *icp;
120	register struct mbuf *m;
121	unsigned icmplen;
122
123	#ifdef ICMPPRINTFS
124	if (icmpprintfs)
125	printf("icmp_error(%p, %x, %d)\n", oip, type, code);
126	#endif
127	if (type != ICMP_REDIRECT)
128	icmpstat.icps_error++;
129	/*
130	* Don't send error if not the first fragment of message.
131	* Don't error if the old packet protocol was ICMP
132	* error message, only known informational types.
133	*/
134	if (oip->ip_off &~ (IP_MF\|IP_DF))
135	goto freeit;
136	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
137	n->m_len >= oiplen + ICMP_MINLEN &&
138	!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
139	icmpstat.icps_oldicmp++;
140	goto freeit;
141	}
142	/* Don't send error in response to a multicast or broadcast packet */
143	if (n->m_flags & (M_BCAST\|M_MCAST))
144	goto freeit;
145	/* Don't send error in response to malicious packet */
146	icmplen = min(oiplen + 8, oip->ip_len);
147	if (icmplen < sizeof(struct ip)) {
148	icmplenPanicAvoided++;
149	goto freeit;
150	}
151
152	/*
153	* First, formulate icmp message
154	*/
155	m = m_gethdr(M_DONTWAIT, MT_HEADER);
156	if (m == NULL)
157	goto freeit;
158	#ifdef MAC
159	mac_create_mbuf_netlayer(n, m);
160	#endif
161	m->m_len = icmplen + ICMP_MINLEN;
162	MH_ALIGN(m, m->m_len);
163	icp = mtod(m, struct icmp *);
164	if ((u_int)type > ICMP_MAXTYPE)
165	panic("icmp_error");
166	icmpstat.icps_outhist[type]++;
167	icp->icmp_type = type;
168	if (type == ICMP_REDIRECT)
169	icp->icmp_gwaddr.s_addr = dest;
170	else {
171	icp->icmp_void = 0;
172	/*
173	* The following assignments assume an overlay with the
174	* zeroed icmp_void field.
175	*/
176	if (type == ICMP_PARAMPROB) {
177	icp->icmp_pptr = code;
178	code = 0;
179	} else if (type == ICMP_UNREACH &&
180	code == ICMP_UNREACH_NEEDFRAG && destifp) {
181	icp->icmp_nextmtu = htons(destifp->if_mtu);
182	}
183	}
184
185	icp->icmp_code = code;
186	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
187	nip = &icp->icmp_ip;
188	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
189
190	/*
191	* Now, copy old ip header (without options)
192	* in front of icmp message.
193	*/
194	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
195	panic("icmp len");
196	m->m_data -= sizeof(struct ip);
197	m->m_len += sizeof(struct ip);
198	m->m_pkthdr.len = m->m_len;
199	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
200	nip = mtod(m, struct ip *);
201	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
202	nip->ip_len = m->m_len;
203	nip->ip_vhl = IP_VHL_BORING;
204	nip->ip_p = IPPROTO_ICMP;
205	nip->ip_tos = 0;
206	icmp_reflect(m);
207
208	freeit:
209	m_freem(n);
210	}
211
212	static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
213	static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
214	static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
215
216	/*
217	* Process a received ICMP message.
218	*/
219	void
220	icmp_input(m, off)
221	struct mbuf *m;
222	int off;
223	{
224	struct icmp *icp;
225	struct in_ifaddr *ia;
226	struct ip ip = mtod(m, struct ip );
227	int hlen = off;
228	int icmplen = ip->ip_len;
229	int i, code;
230	void (ctlfunc)(int, struct sockaddr , void *);
231
232	/*
233	* Locate icmp structure in mbuf, and check
234	* that not corrupted and of at least minimum length.
235	*/
236	#ifdef ICMPPRINTFS
237	if (icmpprintfs) {
238	char buf[4 * sizeof "123"];
239	strcpy(buf, inet_ntoa(ip->ip_src));
240	printf("icmp_input from %s to %s, len %d\n",
241	buf, inet_ntoa(ip->ip_dst), icmplen);
242	}
243	#endif
244	if (icmplen < ICMP_MINLEN) {
245	icmpstat.icps_tooshort++;
246	goto freeit;
247	}
248	i = hlen + min(icmplen, ICMP_ADVLENMIN);
249	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
250	icmpstat.icps_tooshort++;
251	return;
252	}
253	ip = mtod(m, struct ip *);
254	m->m_len -= hlen;
255	m->m_data += hlen;
256	icp = mtod(m, struct icmp *);
257	if (in_cksum(m, icmplen)) {
258	icmpstat.icps_checksum++;
259	goto freeit;
260	}
261	m->m_len += hlen;
262	m->m_data -= hlen;
263
264	#ifdef ICMPPRINTFS
265	if (icmpprintfs)
266	printf("icmp_input, type %d code %d\n", icp->icmp_type,
267	icp->icmp_code);
268	#endif
269
270	/*
271	* Message type specific processing.
272	*/
273	if (icp->icmp_type > ICMP_MAXTYPE)
274	goto raw;
275	icmpstat.icps_inhist[icp->icmp_type]++;
276	code = icp->icmp_code;
277	switch (icp->icmp_type) {
278
279	case ICMP_UNREACH:
280	switch (code) {
281	case ICMP_UNREACH_NET:
282	case ICMP_UNREACH_HOST:
283	case ICMP_UNREACH_PROTOCOL:
284	case ICMP_UNREACH_PORT:
285	case ICMP_UNREACH_SRCFAIL:
286	code = PRC_UNREACH_NET;
287	break;
288
289	case ICMP_UNREACH_NEEDFRAG:
290	code = PRC_MSGSIZE;
291	break;
292
293	case ICMP_UNREACH_NET_UNKNOWN:
294	case ICMP_UNREACH_NET_PROHIB:
295	case ICMP_UNREACH_TOSNET:
296	code = PRC_UNREACH_NET;
297	break;
298
299	case ICMP_UNREACH_HOST_UNKNOWN:
300	case ICMP_UNREACH_ISOLATED:
301	case ICMP_UNREACH_HOST_PROHIB:
302	case ICMP_UNREACH_TOSHOST:
303	code = PRC_UNREACH_HOST;
304	break;
305
306	case ICMP_UNREACH_FILTER_PROHIB:
307	case ICMP_UNREACH_HOST_PRECEDENCE:
308	case ICMP_UNREACH_PRECEDENCE_CUTOFF:
309	code = PRC_UNREACH_PORT;
310	break;
311
312	default:
313	goto badcode;
314	}
315	goto deliver;
316
317	case ICMP_TIMXCEED:
318	if (code > 1)
319	goto badcode;
320	code += PRC_TIMXCEED_INTRANS;
321	goto deliver;
322
323	case ICMP_PARAMPROB:
324	if (code > 1)
325	goto badcode;
326	code = PRC_PARAMPROB;
327	goto deliver;
328
329	case ICMP_SOURCEQUENCH:
330	if (code)
331	goto badcode;
332	code = PRC_QUENCH;
333	deliver:
334	/*
335	* Problem with datagram; advise higher level routines.
336	*/
337	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
338	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
339	icmpstat.icps_badlen++;
340	goto freeit;
341	}
342	NTOHS(icp->icmp_ip.ip_len);
343	/* Discard ICMP's in response to multicast packets */
344	if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
345	goto badcode;
346	#ifdef ICMPPRINTFS
347	if (icmpprintfs)
348	printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
349	#endif
350	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
351	#if 1
352	/*
353	* MTU discovery:
354	* If we got a needfrag and there is a host route to the
355	* original destination, and the MTU is not locked, then
356	* set the MTU in the route to the suggested new value
357	* (if given) and then notify as usual. The ULPs will
358	* notice that the MTU has changed and adapt accordingly.
359	* If no new MTU was suggested, then we guess a new one
360	* less than the current value. If the new MTU is
361	* unreasonably small (arbitrarily set at 296), then
362	* we reset the MTU to the interface value and enable the
363	* lock bit, indicating that we are no longer doing MTU
364	* discovery.
365	*/
366	if (code == PRC_MSGSIZE) {
367	struct rtentry *rt;
368	int mtu;
369
370	rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
371	RTF_CLONING \| RTF_PRCLONING);
372	if (rt && (rt->rt_flags & RTF_HOST)
373	&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
374	mtu = ntohs(icp->icmp_nextmtu);
375	if (!mtu)
376	mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
377	1);
378	#ifdef DEBUG_MTUDISC
379	printf("MTU for %s reduced to %d\n",
380	inet_ntoa(icmpsrc.sin_addr), mtu);
381	#endif
382	if (mtu < 296) {
383	/* rt->rt_rmx.rmx_mtu =
384	rt->rt_ifp->if_mtu; */
385	rt->rt_rmx.rmx_locks \|= RTV_MTU;
386	} else if (rt->rt_rmx.rmx_mtu > mtu) {
387	rt->rt_rmx.rmx_mtu = mtu;
388	}
389	}
390	if (rt)
391	RTFREE(rt);
392	}
393
394	#endif
395	ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
396	if (ctlfunc)
397	(ctlfunc)(code, (struct sockaddr )&icmpsrc,
398	(void *)&icp->icmp_ip);
399	break;
400
401	badcode:
402	icmpstat.icps_badcode++;
403	break;
404
405	case ICMP_ECHO:
406	if (!icmpallecho
407	\|\| (!icmpbmcastecho
408	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
409	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))) {
410	icmpstat.icps_bmcastecho++;
411	break;
412	}
413	icp->icmp_type = ICMP_ECHOREPLY;
414	goto reflect;
415
416	case ICMP_TSTAMP:
417	if (!icmpbmcastecho
418	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
419	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
420	icmpstat.icps_bmcasttstamp++;
421	break;
422	}
423	if (icmplen < ICMP_TSLEN) {
424	icmpstat.icps_badlen++;
425	break;
426	}
427	icp->icmp_type = ICMP_TSTAMPREPLY;
428	icp->icmp_rtime = iptime();
429	icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
430	goto reflect;
431
432	case ICMP_MASKREQ:
433	#define satosin(sa) ((struct sockaddr_in *)(sa))
434	if (icmpmaskrepl == 0)
435	break;
436	/*
437	* We are not able to respond with all ones broadcast
438	* unless we receive it over a point-to-point interface.
439	*/
440	if (icmplen < ICMP_MASKLEN)
441	break;
442	switch (ip->ip_dst.s_addr) {
443
444	case INADDR_BROADCAST:
445	case INADDR_ANY:
446	icmpdst.sin_addr = ip->ip_src;
447	break;
448
449	default:
450	icmpdst.sin_addr = ip->ip_dst;
451	}
452	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
453	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
454	if (ia == 0)
455	break;
456	if (ia->ia_ifp == 0)
457	break;
458	icp->icmp_type = ICMP_MASKREPLY;
459	icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
460	if (ip->ip_src.s_addr == 0) {
461	if (ia->ia_ifp->if_flags & IFF_BROADCAST)
462	ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
463	else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
464	ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
465	}
466	reflect:
467	ip->ip_len += hlen; /* since ip_input deducts this */
468	icmpstat.icps_reflect++;
469	icmpstat.icps_outhist[icp->icmp_type]++;
470	icmp_reflect(m);
471	return;
472
473	case ICMP_REDIRECT:
474	if (code > 3)
475	goto badcode;
476	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
477	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
478	icmpstat.icps_badlen++;
479	break;
480	}
481	/*
482	* Short circuit routing redirects to force
483	* immediate change in the kernel's routing
484	* tables. The message is also handed to anyone
485	* listening on a raw socket (e.g. the routing
486	* daemon for use in updating its tables).
487	*/
488	icmpgw.sin_addr = ip->ip_src;
489	icmpdst.sin_addr = icp->icmp_gwaddr;
490	#ifdef ICMPPRINTFS
491	if (icmpprintfs) {
492	char buf[4 * sizeof "123"];
493	strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
494
495	printf("redirect dst %s to %s\n",
496	buf, inet_ntoa(icp->icmp_gwaddr));
497	}
498	#endif
499	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
500	rtredirect((struct sockaddr *)&icmpsrc,
501	(struct sockaddr *)&icmpdst,
502	(struct sockaddr *)0, RTF_GATEWAY \| RTF_HOST,
503	(struct sockaddr )&icmpgw, (struct rtentry *)0);
504	pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
505	break;
506
507	/*
508	* No kernel processing for the following;
509	* just fall through to send to raw listener.
510	*/
511	case ICMP_ECHOREPLY:
512	case ICMP_ROUTERADVERT:
513	case ICMP_ROUTERSOLICIT:
514	case ICMP_TSTAMPREPLY:
515	case ICMP_IREQREPLY:
516	case ICMP_MASKREPLY:
517	default:
518	break;
519	}
520
521	raw:
522	rip_input(m, hlen);
523	return;
524
525	freeit:
526	m_freem(m);
527	}
528
529	/*
530	* Reflect the ip packet back to the source
531	*/
532	static void
533	icmp_reflect(m)
534	struct mbuf *m;
535	{
536	struct ip ip = mtod(m, struct ip );
537	struct in_ifaddr *ia;
538	struct in_addr t;
539	struct mbuf *opts = 0;
540	int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
541
542	if (!in_canforward(ip->ip_src) &&
543	((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
544	(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
545	m_freem(m); /* Bad return address */
546	goto done; /* Ip_output() will check for broadcast */
547	}
548	t = ip->ip_dst;
549	ip->ip_dst = ip->ip_src;
550	/*
551	* If the incoming packet was addressed directly to us,
552	* use dst as the src for the reply. Otherwise (broadcast
553	* or anonymous), use the address which corresponds
554	* to the incoming interface.
555	*/
556	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
557	if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
558	break;
559	if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
560	t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
561	break;
562	}
563	icmpdst.sin_addr = t;
564	if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
565	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
566	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
567	/*
568	* The following happens if the packet was not addressed to us,
569	* and was received on an interface with no IP address.
570	*/
571	if (ia == (struct in_ifaddr *)0)
572	ia = in_ifaddr;
573	t = IA_SIN(ia)->sin_addr;
574	ip->ip_src = t;
575	ip->ip_ttl = MAXTTL;
576
577	if (optlen > 0) {
578	register u_char *cp;
579	int opt, cnt;
580	u_int len;
581
582	/*
583	* Retrieve any source routing from the incoming packet;
584	* add on any record-route or timestamp options.
585	*/
586	cp = (u_char *) (ip + 1);
587	if ((opts = ip_srcroute()) == 0 &&
588	(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
589	opts->m_len = sizeof(struct in_addr);
590	mtod(opts, struct in_addr *)->s_addr = 0;
591	}
592	if (opts) {
593	#ifdef ICMPPRINTFS
594	if (icmpprintfs)
595	printf("icmp_reflect optlen %d rt %d => ",
596	optlen, opts->m_len);
597	#endif
598	for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
599	opt = cp[IPOPT_OPTVAL];
600	if (opt == IPOPT_EOL)
601	break;
602	if (opt == IPOPT_NOP)
603	len = 1;
604	else {
605	if (cnt < IPOPT_OLEN + sizeof(*cp))
606	break;
607	len = cp[IPOPT_OLEN];
608	if (len < IPOPT_OLEN + sizeof(*cp) \|\|
609	len > cnt)
610	break;
611	}
612	/*
613	* Should check for overflow, but it "can't happen"
614	*/
615	if (opt == IPOPT_RR \|\| opt == IPOPT_TS \|\|
616	opt == IPOPT_SECURITY) {
617	bcopy((caddr_t)cp,
618	mtod(opts, caddr_t) + opts->m_len, len);
619	opts->m_len += len;
620	}
621	}
622	/* Terminate & pad, if necessary */
623	cnt = opts->m_len % 4;
624	if (cnt) {
625	for (; cnt < 4; cnt++) {
626	*(mtod(opts, caddr_t) + opts->m_len) =
627	IPOPT_EOL;
628	opts->m_len++;
629	}
630	}
631	#ifdef ICMPPRINTFS
632	if (icmpprintfs)
633	printf("%d\n", opts->m_len);
634	#endif
635	}
636	/*
637	* Now strip out original options by copying rest of first
638	* mbuf's data back, and adjust the IP length.
639	*/
640	ip->ip_len -= optlen;
641	ip->ip_vhl = IP_VHL_BORING;
642	m->m_len -= optlen;
643	if (m->m_flags & M_PKTHDR)
644	m->m_pkthdr.len -= optlen;
645	optlen += sizeof(struct ip);
646	bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
647	(unsigned)(m->m_len - sizeof(struct ip)));
648	}
649	m->m_flags &= ~(M_BCAST\|M_MCAST);
650	icmp_send(m, opts);
651	done:
652	if (opts)
653	(void)m_free(opts);
654	}
655
656	/*
657	* Send an icmp packet back to the ip level,
658	* after supplying a checksum.
659	*/
660	static void
661	icmp_send(m, opts)
662	register struct mbuf *m;
663	struct mbuf *opts;
664	{
665	register struct ip ip = mtod(m, struct ip );
666	register int hlen;
667	register struct icmp *icp;
668	struct route ro;
669
670	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
671	m->m_data += hlen;
672	m->m_len -= hlen;
673	icp = mtod(m, struct icmp *);
674	icp->icmp_cksum = 0;
675	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
676	m->m_data -= hlen;
677	m->m_len += hlen;
678	#ifdef ICMPPRINTFS
679	if (icmpprintfs) {
680	char buf[4 * sizeof "123"];
681	strcpy(buf, inet_ntoa(ip->ip_dst));
682	printf("icmp_send dst %s src %s\n",
683	buf, inet_ntoa(ip->ip_src));
684	}
685	#endif
686	bzero(&ro, sizeof ro);
687	(void) ip_output(m, opts, &ro, 0, NULL);
688	if (ro.ro_rt)
689	RTFREE(ro.ro_rt);
690	}
691
692	n_time
693	iptime()
694	{
695	struct timeval atv;
696	u_long t;
697
698	microtime(&atv);
699	t = (atv.tv_sec % (246060)) * 1000 + atv.tv_usec / 1000;
700	return (htonl(t));
701	}
702
703	/*
704	* Return the next larger or smaller MTU plateau (table from RFC 1191)
705	* given current value MTU. If DIR is less than zero, a larger plateau
706	* is returned; otherwise, a smaller value is returned.
707	*/
708	int
709	ip_next_mtu(mtu, dir)
710	int mtu;
711	int dir;
712	{
713	static int mtutab[] = {
714	65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
715	296, 68, 0
716	};
717	int i;
718
719	for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
720	if (mtu >= mtutab[i])
721	break;
722	}
723
724	if (dir < 0) {
725	if (i == 0) {
726	return 0;
727	} else {
728	return mtutab[i - 1];
729	}
730	} else {
731	if (mtutab[i] == 0) {
732	return 0;
733	} else if(mtu > mtutab[i]) {
734	return mtutab[i];
735	} else {
736	return mtutab[i + 1];
737	}
738	}
739	}

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