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source: rtems/c/src/lib/libnetworking/netinet/ip_icmp.c @ 13e11f6

4.104.114.84.95

Last change on this file since 13e11f6 was 13e11f6, checked in by Joel Sherrill <joel.sherrill@…>, on 02/02/99 at 21:15:15
Added debug #define and commented it out.
Property mode set to `100644`
File size: 18.2 KB

Rev	Line
[39e6e65a]	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_icmp.c 8.2 (Berkeley) 1/4/94
	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	/*
	61	* ICMP routines: error generation, receive packet processing, and
	62	* routines to turnaround packets back to the originator, and
	63	* host table maintenance routines.
	64	*/
	65
	66	struct icmpstat icmpstat;
	67	SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RD,
	68	&icmpstat, icmpstat, "");
	69
	70	static int icmpmaskrepl = 0;
	71	SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
	72	&icmpmaskrepl, 0, "");
	73
	74	static int icmpbmcastecho = 1;
	75	SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, &icmpbmcastecho,
	76	0, "");
	77
[13e11f6]	78	/* #define ICMPPRINTFS 1 */
[39e6e65a]	79	#ifdef ICMPPRINTFS
	80	int icmpprintfs = 0;
	81	#endif
	82
	83	static void icmp_reflect __P((struct mbuf *));
	84	static void icmp_send __P((struct mbuf , struct mbuf ));
	85	static int ip_next_mtu __P((int, int));
	86
	87	extern struct protosw inetsw[];
	88
	89	/*
	90	* Generate an error packet of type error
	91	* in response to bad packet ip.
	92	*/
	93	void
	94	icmp_error(n, type, code, dest, destifp)
	95	struct mbuf *n;
	96	int type, code;
	97	n_long dest;
	98	struct ifnet *destifp;
	99	{
	100	register struct ip oip = mtod(n, struct ip ), *nip;
	101	register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
	102	register struct icmp *icp;
	103	register struct mbuf *m;
	104	unsigned icmplen;
	105
	106	#ifdef ICMPPRINTFS
	107	if (icmpprintfs)
	108	printf("icmp_error(%p, %x, %d)\n", oip, type, code);
	109	#endif
	110	if (type != ICMP_REDIRECT)
	111	icmpstat.icps_error++;
	112	/*
	113	* Don't send error if not the first fragment of message.
	114	* Don't error if the old packet protocol was ICMP
	115	* error message, only known informational types.
	116	*/
	117	if (oip->ip_off &~ (IP_MF\|IP_DF))
	118	goto freeit;
	119	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
	120	n->m_len >= oiplen + ICMP_MINLEN &&
	121	!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
	122	icmpstat.icps_oldicmp++;
	123	goto freeit;
	124	}
	125	/* Don't send error in response to a multicast or broadcast packet */
	126	if (n->m_flags & (M_BCAST\|M_MCAST))
	127	goto freeit;
	128	/*
	129	* First, formulate icmp message
	130	*/
	131	m = m_gethdr(M_DONTWAIT, MT_HEADER);
	132	if (m == NULL)
	133	goto freeit;
	134	icmplen = oiplen + min(8, oip->ip_len);
	135	m->m_len = icmplen + ICMP_MINLEN;
	136	MH_ALIGN(m, m->m_len);
	137	icp = mtod(m, struct icmp *);
	138	if ((u_int)type > ICMP_MAXTYPE)
	139	panic("icmp_error");
	140	icmpstat.icps_outhist[type]++;
	141	icp->icmp_type = type;
	142	if (type == ICMP_REDIRECT)
	143	icp->icmp_gwaddr.s_addr = dest;
	144	else {
	145	icp->icmp_void = 0;
	146	/*
	147	* The following assignments assume an overlay with the
	148	* zeroed icmp_void field.
	149	*/
	150	if (type == ICMP_PARAMPROB) {
	151	icp->icmp_pptr = code;
	152	code = 0;
	153	} else if (type == ICMP_UNREACH &&
	154	code == ICMP_UNREACH_NEEDFRAG && destifp) {
	155	icp->icmp_nextmtu = htons(destifp->if_mtu);
	156	}
	157	}
	158
	159	icp->icmp_code = code;
	160	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
	161	nip = &icp->icmp_ip;
	162	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
	163
	164	/*
	165	* Now, copy old ip header (without options)
	166	* in front of icmp message.
	167	*/
	168	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
	169	panic("icmp len");
	170	m->m_data -= sizeof(struct ip);
	171	m->m_len += sizeof(struct ip);
	172	m->m_pkthdr.len = m->m_len;
	173	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
	174	nip = mtod(m, struct ip *);
	175	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
	176	nip->ip_len = m->m_len;
	177	nip->ip_vhl = IP_VHL_BORING;
	178	nip->ip_p = IPPROTO_ICMP;
	179	nip->ip_tos = 0;
	180	icmp_reflect(m);
	181
	182	freeit:
	183	m_freem(n);
	184	}
	185
	186	static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
	187	static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
	188	static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
	189
	190	/*
	191	* Process a received ICMP message.
	192	*/
	193	void
	194	icmp_input(m, hlen)
	195	register struct mbuf *m;
	196	int hlen;
	197	{
	198	register struct icmp *icp;
	199	register struct ip ip = mtod(m, struct ip );
	200	int icmplen = ip->ip_len;
	201	register int i;
	202	struct in_ifaddr *ia;
	203	void (ctlfunc) __P((int, struct sockaddr , void *));
	204	int code;
	205
	206	/*
	207	* Locate icmp structure in mbuf, and check
	208	* that not corrupted and of at least minimum length.
	209	*/
	210	#ifdef ICMPPRINTFS
	211	if (icmpprintfs) {
	212	char buf[4 * sizeof "123"];
	213	strcpy(buf, inet_ntoa(ip->ip_src));
	214	printf("icmp_input from %s to %s, len %d\n",
	215	buf, inet_ntoa(ip->ip_dst), icmplen);
	216	}
	217	#endif
	218	if (icmplen < ICMP_MINLEN) {
	219	icmpstat.icps_tooshort++;
	220	goto freeit;
	221	}
	222	i = hlen + min(icmplen, ICMP_ADVLENMIN);
	223	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
	224	icmpstat.icps_tooshort++;
	225	return;
	226	}
	227	ip = mtod(m, struct ip *);
	228	m->m_len -= hlen;
	229	m->m_data += hlen;
	230	icp = mtod(m, struct icmp *);
	231	if (in_cksum(m, icmplen)) {
	232	icmpstat.icps_checksum++;
	233	goto freeit;
	234	}
	235	m->m_len += hlen;
	236	m->m_data -= hlen;
	237
	238	#ifdef ICMPPRINTFS
	239	if (icmpprintfs)
	240	printf("icmp_input, type %d code %d\n", icp->icmp_type,
	241	icp->icmp_code);
	242	#endif
	243
	244	/*
	245	* Message type specific processing.
	246	*/
	247	if (icp->icmp_type > ICMP_MAXTYPE)
	248	goto raw;
	249	icmpstat.icps_inhist[icp->icmp_type]++;
	250	code = icp->icmp_code;
	251	switch (icp->icmp_type) {
	252
	253	case ICMP_UNREACH:
	254	switch (code) {
	255	case ICMP_UNREACH_NET:
	256	case ICMP_UNREACH_HOST:
	257	case ICMP_UNREACH_PROTOCOL:
	258	case ICMP_UNREACH_PORT:
	259	case ICMP_UNREACH_SRCFAIL:
	260	code += PRC_UNREACH_NET;
	261	break;
	262
	263	case ICMP_UNREACH_NEEDFRAG:
	264	code = PRC_MSGSIZE;
	265	break;
	266
	267	case ICMP_UNREACH_NET_UNKNOWN:
	268	case ICMP_UNREACH_NET_PROHIB:
	269	case ICMP_UNREACH_TOSNET:
	270	code = PRC_UNREACH_NET;
	271	break;
	272
	273	case ICMP_UNREACH_HOST_UNKNOWN:
	274	case ICMP_UNREACH_ISOLATED:
	275	case ICMP_UNREACH_HOST_PROHIB:
	276	case ICMP_UNREACH_TOSHOST:
	277	code = PRC_UNREACH_HOST;
	278	break;
	279
	280	case ICMP_UNREACH_FILTER_PROHIB:
	281	case ICMP_UNREACH_HOST_PRECEDENCE:
	282	case ICMP_UNREACH_PRECEDENCE_CUTOFF:
	283	code = PRC_UNREACH_PORT;
	284	break;
	285
	286	default:
	287	goto badcode;
	288	}
	289	goto deliver;
	290
	291	case ICMP_TIMXCEED:
	292	if (code > 1)
	293	goto badcode;
	294	code += PRC_TIMXCEED_INTRANS;
	295	goto deliver;
	296
	297	case ICMP_PARAMPROB:
	298	if (code > 1)
	299	goto badcode;
	300	code = PRC_PARAMPROB;
	301	goto deliver;
	302
	303	case ICMP_SOURCEQUENCH:
	304	if (code)
	305	goto badcode;
	306	code = PRC_QUENCH;
	307	deliver:
	308	/*
	309	* Problem with datagram; advise higher level routines.
	310	*/
	311	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
	312	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
	313	icmpstat.icps_badlen++;
	314	goto freeit;
	315	}
	316	NTOHS(icp->icmp_ip.ip_len);
	317	/* Discard ICMP's in response to multicast packets */
	318	if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
	319	goto badcode;
	320	#ifdef ICMPPRINTFS
	321	if (icmpprintfs)
	322	printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
	323	#endif
	324	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
	325	#if 1
	326	/*
	327	* MTU discovery:
	328	* If we got a needfrag and there is a host route to the
	329	* original destination, and the MTU is not locked, then
	330	* set the MTU in the route to the suggested new value
	331	* (if given) and then notify as usual. The ULPs will
	332	* notice that the MTU has changed and adapt accordingly.
	333	* If no new MTU was suggested, then we guess a new one
	334	* less than the current value. If the new MTU is
	335	* unreasonably small (arbitrarily set at 296), then
	336	* we reset the MTU to the interface value and enable the
	337	* lock bit, indicating that we are no longer doing MTU
	338	* discovery.
	339	*/
	340	if (code == PRC_MSGSIZE) {
	341	struct rtentry *rt;
	342	int mtu;
	343
	344	rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
	345	RTF_CLONING \| RTF_PRCLONING);
	346	if (rt && (rt->rt_flags & RTF_HOST)
	347	&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
	348	mtu = ntohs(icp->icmp_nextmtu);
	349	if (!mtu)
	350	mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
	351	1);
	352	#ifdef DEBUG_MTUDISC
	353	printf("MTU for %s reduced to %d\n",
	354	inet_ntoa(icmpsrc.sin_addr), mtu);
	355	#endif
	356	if (mtu < 296) {
	357	/* rt->rt_rmx.rmx_mtu =
	358	rt->rt_ifp->if_mtu; */
	359	rt->rt_rmx.rmx_locks \|= RTV_MTU;
	360	} else if (rt->rt_rmx.rmx_mtu > mtu) {
	361	rt->rt_rmx.rmx_mtu = mtu;
	362	}
	363	}
	364	if (rt)
	365	RTFREE(rt);
	366	}
	367
	368	#endif
	369	ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
	370	if (ctlfunc)
	371	(ctlfunc)(code, (struct sockaddr )&icmpsrc,
	372	(void *)&icp->icmp_ip);
	373	break;
	374
	375	badcode:
	376	icmpstat.icps_badcode++;
	377	break;
	378
	379	case ICMP_ECHO:
	380	if (!icmpbmcastecho
	381	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
	382	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
	383	icmpstat.icps_bmcastecho++;
	384	break;
	385	}
	386	icp->icmp_type = ICMP_ECHOREPLY;
	387	goto reflect;
	388
	389	case ICMP_TSTAMP:
	390	if (!icmpbmcastecho
	391	&& (m->m_flags & (M_MCAST \| M_BCAST)) != 0
	392	&& IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
	393	icmpstat.icps_bmcasttstamp++;
	394	break;
	395	}
	396	if (icmplen < ICMP_TSLEN) {
	397	icmpstat.icps_badlen++;
	398	break;
	399	}
	400	icp->icmp_type = ICMP_TSTAMPREPLY;
	401	icp->icmp_rtime = iptime();
	402	icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
	403	goto reflect;
	404
	405	case ICMP_MASKREQ:
	406	#define satosin(sa) ((struct sockaddr_in *)(sa))
	407	if (icmpmaskrepl == 0)
	408	break;
	409	/*
	410	* We are not able to respond with all ones broadcast
	411	* unless we receive it over a point-to-point interface.
	412	*/
	413	if (icmplen < ICMP_MASKLEN)
	414	break;
	415	switch (ip->ip_dst.s_addr) {
	416
	417	case INADDR_BROADCAST:
	418	case INADDR_ANY:
	419	icmpdst.sin_addr = ip->ip_src;
	420	break;
	421
	422	default:
	423	icmpdst.sin_addr = ip->ip_dst;
	424	}
	425	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
	426	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
	427	if (ia == 0)
	428	break;
	429	if (ia->ia_ifp == 0)
	430	break;
	431	icp->icmp_type = ICMP_MASKREPLY;
	432	icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
	433	if (ip->ip_src.s_addr == 0) {
	434	if (ia->ia_ifp->if_flags & IFF_BROADCAST)
	435	ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
	436	else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
	437	ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
	438	}
	439	reflect:
	440	ip->ip_len += hlen; /* since ip_input deducts this */
	441	icmpstat.icps_reflect++;
	442	icmpstat.icps_outhist[icp->icmp_type]++;
	443	icmp_reflect(m);
	444	return;
	445
	446	case ICMP_REDIRECT:
	447	if (code > 3)
	448	goto badcode;
	449	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp) \|\|
	450	IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
	451	icmpstat.icps_badlen++;
	452	break;
	453	}
	454	/*
	455	* Short circuit routing redirects to force
	456	* immediate change in the kernel's routing
	457	* tables. The message is also handed to anyone
	458	* listening on a raw socket (e.g. the routing
	459	* daemon for use in updating its tables).
	460	*/
	461	icmpgw.sin_addr = ip->ip_src;
	462	icmpdst.sin_addr = icp->icmp_gwaddr;
	463	#ifdef ICMPPRINTFS
	464	if (icmpprintfs) {
	465	char buf[4 * sizeof "123"];
	466	strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
	467
	468	printf("redirect dst %s to %s\n",
	469	buf, inet_ntoa(icp->icmp_gwaddr));
	470	}
	471	#endif
	472	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
	473	rtredirect((struct sockaddr *)&icmpsrc,
	474	(struct sockaddr *)&icmpdst,
	475	(struct sockaddr *)0, RTF_GATEWAY \| RTF_HOST,
	476	(struct sockaddr )&icmpgw, (struct rtentry *)0);
	477	pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
	478	break;
	479
	480	/*
	481	* No kernel processing for the following;
	482	* just fall through to send to raw listener.
	483	*/
	484	case ICMP_ECHOREPLY:
	485	case ICMP_ROUTERADVERT:
	486	case ICMP_ROUTERSOLICIT:
	487	case ICMP_TSTAMPREPLY:
	488	case ICMP_IREQREPLY:
	489	case ICMP_MASKREPLY:
	490	default:
	491	break;
	492	}
	493
	494	raw:
	495	rip_input(m, hlen);
	496	return;
	497
	498	freeit:
	499	m_freem(m);
	500	}
	501
	502	/*
	503	* Reflect the ip packet back to the source
	504	*/
	505	static void
	506	icmp_reflect(m)
	507	struct mbuf *m;
	508	{
	509	register struct ip ip = mtod(m, struct ip );
	510	register struct in_ifaddr *ia;
	511	struct in_addr t;
	512	struct mbuf *opts = 0;
	513	int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
	514
	515	if (!in_canforward(ip->ip_src) &&
	516	((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
	517	(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
	518	m_freem(m); /* Bad return address */
	519	goto done; /* Ip_output() will check for broadcast */
	520	}
	521	t = ip->ip_dst;
	522	ip->ip_dst = ip->ip_src;
	523	/*
	524	* If the incoming packet was addressed directly to us,
	525	* use dst as the src for the reply. Otherwise (broadcast
	526	* or anonymous), use the address which corresponds
	527	* to the incoming interface.
	528	*/
	529	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
	530	if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
	531	break;
	532	if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
	533	t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
	534	break;
	535	}
	536	icmpdst.sin_addr = t;
	537	if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
	538	ia = (struct in_ifaddr *)ifaof_ifpforaddr(
	539	(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
	540	/*
	541	* The following happens if the packet was not addressed to us,
	542	* and was received on an interface with no IP address.
	543	*/
	544	if (ia == (struct in_ifaddr *)0)
	545	ia = in_ifaddr;
	546	t = IA_SIN(ia)->sin_addr;
	547	ip->ip_src = t;
	548	ip->ip_ttl = MAXTTL;
	549
	550	if (optlen > 0) {
	551	register u_char *cp;
	552	int opt, cnt;
	553	u_int len;
	554
	555	/*
	556	* Retrieve any source routing from the incoming packet;
	557	* add on any record-route or timestamp options.
	558	*/
	559	cp = (u_char *) (ip + 1);
	560	if ((opts = ip_srcroute()) == 0 &&
	561	(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
	562	opts->m_len = sizeof(struct in_addr);
	563	mtod(opts, struct in_addr *)->s_addr = 0;
	564	}
	565	if (opts) {
	566	#ifdef ICMPPRINTFS
	567	if (icmpprintfs)
	568	printf("icmp_reflect optlen %d rt %d => ",
	569	optlen, opts->m_len);
	570	#endif
	571	for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
	572	opt = cp[IPOPT_OPTVAL];
	573	if (opt == IPOPT_EOL)
	574	break;
	575	if (opt == IPOPT_NOP)
	576	len = 1;
	577	else {
	578	len = cp[IPOPT_OLEN];
	579	if (len <= 0 \|\| len > cnt)
	580	break;
	581	}
	582	/*
	583	* Should check for overflow, but it "can't happen"
	584	*/
	585	if (opt == IPOPT_RR \|\| opt == IPOPT_TS \|\|
	586	opt == IPOPT_SECURITY) {
	587	bcopy((caddr_t)cp,
	588	mtod(opts, caddr_t) + opts->m_len, len);
	589	opts->m_len += len;
	590	}
	591	}
	592	/* Terminate & pad, if necessary */
	593	cnt = opts->m_len % 4;
	594	if (cnt) {
	595	for (; cnt < 4; cnt++) {
	596	*(mtod(opts, caddr_t) + opts->m_len) =
	597	IPOPT_EOL;
	598	opts->m_len++;
	599	}
	600	}
	601	#ifdef ICMPPRINTFS
	602	if (icmpprintfs)
	603	printf("%d\n", opts->m_len);
	604	#endif
	605	}
	606	/*
	607	* Now strip out original options by copying rest of first
	608	* mbuf's data back, and adjust the IP length.
	609	*/
	610	ip->ip_len -= optlen;
	611	ip->ip_vhl = IP_VHL_BORING;
	612	m->m_len -= optlen;
	613	if (m->m_flags & M_PKTHDR)
	614	m->m_pkthdr.len -= optlen;
	615	optlen += sizeof(struct ip);
	616	bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
	617	(unsigned)(m->m_len - sizeof(struct ip)));
	618	}
	619	m->m_flags &= ~(M_BCAST\|M_MCAST);
	620	icmp_send(m, opts);
	621	done:
	622	if (opts)
	623	(void)m_free(opts);
	624	}
	625
	626	/*
	627	* Send an icmp packet back to the ip level,
	628	* after supplying a checksum.
	629	*/
	630	static void
	631	icmp_send(m, opts)
	632	register struct mbuf *m;
	633	struct mbuf *opts;
	634	{
	635	register struct ip ip = mtod(m, struct ip );
	636	register int hlen;
	637	register struct icmp *icp;
	638	struct route ro;
	639
	640	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
	641	m->m_data += hlen;
	642	m->m_len -= hlen;
	643	icp = mtod(m, struct icmp *);
	644	icp->icmp_cksum = 0;
	645	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
	646	m->m_data -= hlen;
	647	m->m_len += hlen;
	648	#ifdef ICMPPRINTFS
	649	if (icmpprintfs) {
	650	char buf[4 * sizeof "123"];
	651	strcpy(buf, inet_ntoa(ip->ip_dst));
	652	printf("icmp_send dst %s src %s\n",
	653	buf, inet_ntoa(ip->ip_src));
	654	}
	655	#endif
	656	bzero(&ro, sizeof ro);
	657	(void) ip_output(m, opts, &ro, 0, NULL);
	658	if (ro.ro_rt)
	659	RTFREE(ro.ro_rt);
	660	}
	661
	662	n_time
	663	iptime()
	664	{
	665	struct timeval atv;
	666	u_long t;
	667
	668	microtime(&atv);
	669	t = (atv.tv_sec % (246060)) * 1000 + atv.tv_usec / 1000;
	670	return (htonl(t));
	671	}
	672
	673	#if 1
	674	/*
	675	* Return the next larger or smaller MTU plateau (table from RFC 1191)
	676	* given current value MTU. If DIR is less than zero, a larger plateau
	677	* is returned; otherwise, a smaller value is returned.
	678	*/
	679	static int
	680	ip_next_mtu(mtu, dir)
	681	int mtu;
	682	int dir;
	683	{
	684	static int mtutab[] = {
	685	65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
	686	68, 0
	687	};
	688	int i;
	689
	690	for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
	691	if (mtu >= mtutab[i])
	692	break;
	693	}
	694
	695	if (dir < 0) {
	696	if (i == 0) {
	697	return 0;
	698	} else {
	699	return mtutab[i - 1];
	700	}
	701	} else {
	702	if (mtutab[i] == 0) {
	703	return 0;
	704	} else if(mtu > mtutab[i]) {
	705	return mtutab[i];
	706	} else {
	707	return mtutab[i + 1];
	708	}
	709	}
	710	}
	711	#endif

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