usr/src/sys/netinet/ip_icmp.c

/*
 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	@(#)ip_icmp.c	7.8.1.3 (Berkeley) %G%
 */

#include "param.h"
#include "systm.h"
#include "malloc.h"
#include "mbuf.h"
#include "protosw.h"
#include "socket.h"
#include "time.h"
#include "kernel.h"

#include "../net/route.h"
#include "../net/if.h"

#include "in.h"
#include "in_systm.h"
#include "in_var.h"
#include "ip.h"
#include "ip_icmp.h"
#include "icmp_var.h"

/*
 * ICMP routines: error generation, receive packet processing, and
 * routines to turnaround packets back to the originator, and
 * host table maintenance routines.
 */
#ifdef ICMPPRINTFS
int	icmpprintfs = 0;
#endif

/*
 * Generate an error packet of type error
 * in response to bad packet ip.
 */
/*VARARGS3*/
icmp_error(n, type, code, dest)
	struct mbuf *n;
	int type, code;
	struct in_addr dest;
{
	register struct ip *oip = mtod(n, struct ip *), *nip;
	register unsigned oiplen = oip->ip_hl << 2;
	register struct icmp *icp;
	register struct mbuf *m;
	unsigned icmplen;

#ifdef ICMPPRINTFS
	if (icmpprintfs)
		printf("icmp_error(%x, %d, %d)\n", oip, type, code);
#endif
	if (type != ICMP_REDIRECT)
		icmpstat.icps_error++;
	/*
	 * Don't send error if not the first fragment of message.
	 * Don't error if the old packet protocol was ICMP
	 * error message, only known informational types.
	 */
	if (oip->ip_off &~ (IP_MF|IP_DF))
		goto freeit;
	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
	  dtom(oip)->m_len >= oiplen + ICMP_MINLEN &&
	  n->m_len >= oiplen + ICMP_MINLEN &&
	  !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
		icmpstat.icps_oldicmp++;
		goto freeit;
	}

	/*
	 * First, formulate icmp message
	 */
	m = m_gethdr(M_DONTWAIT, MT_HEADER);
	if (m == NULL)
		goto freeit;
	icmplen = oiplen + min(8, oip->ip_len);
	m->m_len = icmplen + ICMP_MINLEN;
	MH_ALIGN(m, m->m_len);
	icp = mtod(m, struct icmp *);
	if ((u_int)type > ICMP_MAXTYPE)
		panic("icmp_error");
	icmpstat.icps_outhist[type]++;
	icp->icmp_type = type;
	if (type == ICMP_REDIRECT)
		icp->icmp_gwaddr = dest;
	else
		icp->icmp_void = 0;
	if (type == ICMP_PARAMPROB) {
		icp->icmp_pptr = code;
		code = 0;
	}
	icp->icmp_code = code;
	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
	nip = &icp->icmp_ip;
	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));

	/*
	 * Now, copy old ip header (without options)
	 * in front of icmp message.
	 */
	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
		panic("icmp len");
	m->m_data -= sizeof(struct ip);
	m->m_len += sizeof(struct ip);
	m->m_pkthdr.len = m->m_len;
	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
	nip = mtod(m, struct ip *);
	bcopy((caddr_t)oip, (caddr_t)nip, oiplen);
	nip->ip_len = m->m_len;
	nip->ip_hl = sizeof(struct ip) >> 2;
	nip->ip_hl = sizeof(struct ip) >> 2;
	nip->ip_p = IPPROTO_ICMP;
	icmp_reflect(m);

freeit:
	m_freem(n);
}

static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP };
static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
struct sockaddr_in icmpmask = { 8, 0 };
struct in_ifaddr *ifptoia();

/*
 * Process a received ICMP message.
 */
icmp_input(m, hlen)
	register struct mbuf *m;
	int hlen;
{
	register struct icmp *icp;
	register struct ip *ip = mtod(m, struct ip *);
	int icmplen = ip->ip_len;
	register int i;
	struct in_ifaddr *ia;
	int (*ctlfunc)(), code;
	extern u_char ip_protox[];
	extern struct in_addr in_makeaddr();

	/*
	 * Locate icmp structure in mbuf, and check
	 * that not corrupted and of at least minimum length.
	 */
#ifdef ICMPPRINTFS
	if (icmpprintfs)
		printf("icmp_input from %x, len %d\n", ip->ip_src, icmplen);
#endif
	if (icmplen < ICMP_MINLEN) {
		icmpstat.icps_tooshort++;
		goto freeit;
	}
	i = hlen + MIN(icmplen, ICMP_ADVLENMIN);
 	if (m->m_len < i && (m = m_pullup(m, i)) == 0)  {
		icmpstat.icps_tooshort++;
		return;
	}
 	ip = mtod(m, struct ip *);
	m->m_len -= hlen;
	m->m_data += hlen;
	icp = mtod(m, struct icmp *);
	if (in_cksum(m, icmplen)) {
		icmpstat.icps_checksum++;
		goto freeit;
	}
	m->m_len += hlen;
	m->m_data -= hlen;

#ifdef ICMPPRINTFS
	/*
	 * Message type specific processing.
	 */
	if (icmpprintfs)
		printf("icmp_input, type %d code %d\n", icp->icmp_type,
		    icp->icmp_code);
#endif
	if (icp->icmp_type > ICMP_MAXTYPE)
		goto raw;
	icmpstat.icps_inhist[icp->icmp_type]++;
	code = icp->icmp_code;
	switch (icp->icmp_type) {

	case ICMP_UNREACH:
		if (code > 5)
			goto badcode;
		code += PRC_UNREACH_NET;
		goto deliver;

	case ICMP_TIMXCEED:
		if (code > 1)
			goto badcode;
		code += PRC_TIMXCEED_INTRANS;
		goto deliver;

	case ICMP_PARAMPROB:
		if (code)
			goto badcode;
		code = PRC_PARAMPROB;
		goto deliver;

	case ICMP_SOURCEQUENCH:
		if (code)
			goto badcode;
		code = PRC_QUENCH;
	deliver:
		/*
		 * Problem with datagram; advise higher level routines.
		 */
		icp->icmp_ip.ip_len = ntohs((u_short)icp->icmp_ip.ip_len);
		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) {
			icmpstat.icps_badlen++;
			goto freeit;
		}
#ifdef ICMPPRINTFS
		if (icmpprintfs)
			printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
#endif
		icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
		if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput)
			(*ctlfunc)(code, (struct sockaddr *)&icmpsrc);
		break;

	badcode:
		icmpstat.icps_badcode++;
		break;

	case ICMP_ECHO:
		icp->icmp_type = ICMP_ECHOREPLY;
		goto reflect;

	case ICMP_TSTAMP:
		if (icmplen < ICMP_TSLEN) {
			icmpstat.icps_badlen++;
			break;
		}
		icp->icmp_type = ICMP_TSTAMPREPLY;
		icp->icmp_rtime = iptime();
		icp->icmp_ttime = icp->icmp_rtime;	/* bogus, do later! */
		goto reflect;

	case ICMP_IREQ:
#define	satosin(sa)	((struct sockaddr_in *)(sa))
		if (in_netof(ip->ip_src) == 0 &&
		    (ia = ifptoia(m->m_pkthdr.rcvif)))
			ip->ip_src = in_makeaddr(in_netof(IA_SIN(ia)->sin_addr),
			    in_lnaof(ip->ip_src));
		icp->icmp_type = ICMP_IREQREPLY;
		goto reflect;

	case ICMP_MASKREQ:
		if (icmplen < ICMP_MASKLEN ||
		    (ia = ifptoia(m->m_pkthdr.rcvif)) == 0)
			break;
		icp->icmp_type = ICMP_MASKREPLY;
		icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
		if (ip->ip_src.s_addr == 0) {
			if (ia->ia_ifp->if_flags & IFF_BROADCAST)
			    ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
			else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
			    ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
		}
reflect:
		ip->ip_len += hlen;	/* since ip_input deducts this */
		icmpstat.icps_reflect++;
		icmpstat.icps_outhist[icp->icmp_type]++;
		icmp_reflect(m);
		return;

	case ICMP_REDIRECT:
		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) {
			icmpstat.icps_badlen++;
			break;
		}
		/*
		 * Short circuit routing redirects to force
		 * immediate change in the kernel's routing
		 * tables.  The message is also handed to anyone
		 * listening on a raw socket (e.g. the routing
		 * daemon for use in updating its tables).
		 */
		icmpgw.sin_addr = ip->ip_src;
		icmpdst.sin_addr = icp->icmp_gwaddr;
#ifdef	ICMPPRINTFS
		if (icmpprintfs)
			printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst,
				icp->icmp_gwaddr);
#endif
		if (code == ICMP_REDIRECT_NET || code == ICMP_REDIRECT_TOSNET) {
			u_long in_netof();
			icmpsrc.sin_addr =
			 in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY);
			in_sockmaskof(icp->icmp_ip.ip_dst, &icmpmask);
			rtredirect((struct sockaddr *)&icmpsrc,
			  (struct sockaddr *)&icmpdst,
			  (struct sockaddr *)&icmpmask, RTF_GATEWAY,
			  (struct sockaddr *)&icmpgw, (struct rtentry **)0);
			icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
			pfctlinput(PRC_REDIRECT_NET,
			  (struct sockaddr *)&icmpsrc);
		} else {
			icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
			rtredirect((struct sockaddr *)&icmpsrc,
			  (struct sockaddr *)&icmpdst,
			  (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
			  (struct sockaddr *)&icmpgw, (struct rtentry **)0);
			pfctlinput(PRC_REDIRECT_HOST,
			  (struct sockaddr *)&icmpsrc);
		}
		break;

	/*
	 * No kernel processing for the following;
	 * just fall through to send to raw listener.
	 */
	case ICMP_ECHOREPLY:
	case ICMP_TSTAMPREPLY:
	case ICMP_IREQREPLY:
	case ICMP_MASKREPLY:
	default:
		break;
	}

raw:
	icmpsrc.sin_addr = ip->ip_src;
	icmpdst.sin_addr = ip->ip_dst;
	raw_input(m, &icmproto, (struct sockaddr *)&icmpsrc,
	    (struct sockaddr *)&icmpdst);
	return;

freeit:
	m_freem(m);
}

/*
 * Reflect the ip packet back to the source
 */
icmp_reflect(m)
	struct mbuf *m;
{
	register struct ip *ip = mtod(m, struct ip *);
	register struct in_ifaddr *ia;
	struct in_addr t;
	struct mbuf *opts = 0, *ip_srcroute();
	int optlen = (ip->ip_hl << 2) - sizeof(struct ip);

	t = ip->ip_dst;
	ip->ip_dst = ip->ip_src;
	/*
	 * If the incoming packet was addressed directly to us,
	 * use dst as the src for the reply.  Otherwise (broadcast
	 * or anonymous), use the address which corresponds
	 * to the incoming interface.
	 */
	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
		if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
			break;
		if ((ia->ia_ifp->if_flags & IFF_BROADCAST) &&
		    t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
			break;
	}
	if (ia == (struct in_ifaddr *)0)
		ia = ifptoia(m->m_pkthdr.rcvif);
	if (ia == (struct in_ifaddr *)0)
		ia = in_ifaddr;
	t = IA_SIN(ia)->sin_addr;
	ip->ip_src = t;
	ip->ip_ttl = MAXTTL;

	if (optlen > 0) {
		register u_char *cp;
		struct mbuf *m = dtom(ip);
		int opt, cnt, off;
		u_int len;

		register u_char *cp;
		int opt, cnt;
		u_int len;

		/*
		 * Retrieve any source routing from the incoming packet;
		 * add on any record-route or timestamp options.
		 */
		cp = (u_char *) (ip + 1);
		if ((opts = ip_srcroute()) == 0 &&
		    (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
			opts->m_len = sizeof(struct in_addr);
			mtod(opts, struct in_addr *)->s_addr = 0;
		}
		if (opts) {
#ifdef ICMPPRINTFS
		    if (icmpprintfs)
			    printf("icmp_reflect optlen %d rt %d => ",
				optlen, opts->m_len);
#endif
		    for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
			    opt = cp[IPOPT_OPTVAL];
			    if (opt == IPOPT_EOL)
				    break;
			    if (opt == IPOPT_NOP)
				    len = 1;
			    else {
				    len = cp[IPOPT_OLEN];
				    if (len <= 0 || len > cnt)
					    break;
			    }
			    /*
			     * should check for overflow, but it "can't happen"
			     */
			    if (opt == IPOPT_RR || opt == IPOPT_TS) {
				    bcopy((caddr_t)cp,
					mtod(opts, caddr_t) + opts->m_len, len);
				    opts->m_len += len;
			    }
		    }
		    if (opts->m_len % 4 != 0) {
			    *(mtod(opts, caddr_t) + opts->m_len) = IPOPT_EOL;
			    opts->m_len++;
		    }
#ifdef ICMPPRINTFS
		    if (icmpprintfs)
			    printf("%d\n", opts->m_len);
#endif
		}
		/*
		 * Now strip out original options by copying rest of first
		 * mbuf's data back, and adjust the IP length.
		 */
		ip->ip_len -= optlen;
		ip->ip_hl = sizeof(struct ip) >> 2;
		m->m_len -= optlen;
		if (m->m_flags & M_PKTHDR)
			m->m_pkthdr.len -= optlen;
		optlen += sizeof(struct ip);
		bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
			 (unsigned)(m->m_len - sizeof(struct ip)));
	}

	icmp_send(m, opts);
	if (opts)
		(void)m_free(opts);
}

struct in_ifaddr *
ifptoia(ifp)
	struct ifnet *ifp;
{
	register struct in_ifaddr *ia;

	for (ia = in_ifaddr; ia; ia = ia->ia_next)
		if (ia->ia_ifp == ifp)
			return (ia);
	return ((struct in_ifaddr *)0);
}

/*
 * Send an icmp packet back to the ip level,
 * after supplying a checksum.
 */
icmp_send(m, opts)
	register struct mbuf *m;
	struct mbuf *opts;
{
	register struct ip *ip = mtod(m, struct ip *);
	register int hlen;
	register struct icmp *icp;

	hlen = ip->ip_hl << 2;
	m->m_data += hlen;
	m->m_len -= hlen;
	icp = mtod(m, struct icmp *);
	icp->icmp_cksum = 0;
	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
	m->m_data -= hlen;
	m->m_len += hlen;
#ifdef ICMPPRINTFS
	if (icmpprintfs)
		printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src);
#endif
	(void) ip_output(m, opts, (struct route *)0, 0);
}

n_time
iptime()
{
	struct timeval atv;
	u_long t;

	microtime(&atv);
	t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
	return (htonl(t));
}
Commit	Line	Data
	1	/*
	2	* Copyright (c) 1982, 1986, 1988 Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms are permitted
	6	* provided that the above copyright notice and this paragraph are
	7	* duplicated in all such forms and that any documentation,
	8	* advertising materials, and other materials related to such
	9	* distribution and use acknowledge that the software was developed
	10	* by the University of California, Berkeley. The name of the
	11	* University may not be used to endorse or promote products derived
	12	* from this software without specific prior written permission.
	13	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	15	* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	16	*
	17	* @(#)ip_icmp.c 7.8.1.3 (Berkeley) %G%
	18	*/
	19
	20	#include "param.h"
	21	#include "systm.h"
	22	#include "malloc.h"
	23	#include "mbuf.h"
	24	#include "protosw.h"
	25	#include "socket.h"
	26	#include "time.h"
	27	#include "kernel.h"
	28
	29	#include "../net/route.h"
	30	#include "../net/if.h"
	31
	32	#include "in.h"
	33	#include "in_systm.h"
	34	#include "in_var.h"
	35	#include "ip.h"
	36	#include "ip_icmp.h"
	37	#include "icmp_var.h"
	38
	39	/*
	40	* ICMP routines: error generation, receive packet processing, and
	41	* routines to turnaround packets back to the originator, and
	42	* host table maintenance routines.
	43	*/
	44	#ifdef ICMPPRINTFS
	45	int icmpprintfs = 0;
	46	#endif
	47
	48	/*
	49	* Generate an error packet of type error
	50	* in response to bad packet ip.
	51	*/
	52	/VARARGS3/
	53	icmp_error(n, type, code, dest)
	54	struct mbuf *n;
	55	int type, code;
	56	struct in_addr dest;
	57	{
	58	register struct ip oip = mtod(n, struct ip ), *nip;
	59	register unsigned oiplen = oip->ip_hl << 2;
	60	register struct icmp *icp;
	61	register struct mbuf *m;
	62	unsigned icmplen;
	63
	64	#ifdef ICMPPRINTFS
	65	if (icmpprintfs)
	66	printf("icmp_error(%x, %d, %d)\n", oip, type, code);
	67	#endif
	68	if (type != ICMP_REDIRECT)
	69	icmpstat.icps_error++;
	70	/*
	71	* Don't send error if not the first fragment of message.
	72	* Don't error if the old packet protocol was ICMP
	73	* error message, only known informational types.
	74	*/
	75	if (oip->ip_off &~ (IP_MF\|IP_DF))
	76	goto freeit;
	77	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
	78	dtom(oip)->m_len >= oiplen + ICMP_MINLEN &&
	79	n->m_len >= oiplen + ICMP_MINLEN &&
	80	!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
	81	icmpstat.icps_oldicmp++;
	82	goto freeit;
	83	}
	84
	85	/*
	86	* First, formulate icmp message
	87	*/
	88	m = m_gethdr(M_DONTWAIT, MT_HEADER);
	89	if (m == NULL)
	90	goto freeit;
	91	icmplen = oiplen + min(8, oip->ip_len);
	92	m->m_len = icmplen + ICMP_MINLEN;
	93	MH_ALIGN(m, m->m_len);
	94	icp = mtod(m, struct icmp *);
	95	if ((u_int)type > ICMP_MAXTYPE)
	96	panic("icmp_error");
	97	icmpstat.icps_outhist[type]++;
	98	icp->icmp_type = type;
	99	if (type == ICMP_REDIRECT)
	100	icp->icmp_gwaddr = dest;
	101	else
	102	icp->icmp_void = 0;
	103	if (type == ICMP_PARAMPROB) {
	104	icp->icmp_pptr = code;
	105	code = 0;
	106	}
	107	icp->icmp_code = code;
	108	bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
	109	nip = &icp->icmp_ip;
	110	nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
	111
	112	/*
	113	* Now, copy old ip header (without options)
	114	* in front of icmp message.
	115	*/
	116	if (m->m_data - sizeof(struct ip) < m->m_pktdat)
	117	panic("icmp len");
	118	m->m_data -= sizeof(struct ip);
	119	m->m_len += sizeof(struct ip);
	120	m->m_pkthdr.len = m->m_len;
	121	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
	122	nip = mtod(m, struct ip *);
	123	bcopy((caddr_t)oip, (caddr_t)nip, oiplen);
	124	nip->ip_len = m->m_len;
	125	nip->ip_hl = sizeof(struct ip) >> 2;
	126	nip->ip_hl = sizeof(struct ip) >> 2;
	127	nip->ip_p = IPPROTO_ICMP;
	128	icmp_reflect(m);
	129
	130	freeit:
	131	m_freem(n);
	132	}
	133
	134	static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP };
	135	static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
	136	static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
	137	static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
	138	struct sockaddr_in icmpmask = { 8, 0 };
	139	struct in_ifaddr *ifptoia();
	140
	141	/*
	142	* Process a received ICMP message.
	143	*/
	144	icmp_input(m, hlen)
	145	register struct mbuf *m;
	146	int hlen;
	147	{
	148	register struct icmp *icp;
	149	register struct ip ip = mtod(m, struct ip );
	150	int icmplen = ip->ip_len;
	151	register int i;
	152	struct in_ifaddr *ia;
	153	int (*ctlfunc)(), code;
	154	extern u_char ip_protox[];
	155	extern struct in_addr in_makeaddr();
	156
	157	/*
	158	* Locate icmp structure in mbuf, and check
	159	* that not corrupted and of at least minimum length.
	160	*/
	161	#ifdef ICMPPRINTFS
	162	if (icmpprintfs)
	163	printf("icmp_input from %x, len %d\n", ip->ip_src, icmplen);
	164	#endif
	165	if (icmplen < ICMP_MINLEN) {
	166	icmpstat.icps_tooshort++;
	167	goto freeit;
	168	}
	169	i = hlen + MIN(icmplen, ICMP_ADVLENMIN);
	170	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
	171	icmpstat.icps_tooshort++;
	172	return;
	173	}
	174	ip = mtod(m, struct ip *);
	175	m->m_len -= hlen;
	176	m->m_data += hlen;
	177	icp = mtod(m, struct icmp *);
	178	if (in_cksum(m, icmplen)) {
	179	icmpstat.icps_checksum++;
	180	goto freeit;
	181	}
	182	m->m_len += hlen;
	183	m->m_data -= hlen;
	184
	185	#ifdef ICMPPRINTFS
	186	/*
	187	* Message type specific processing.
	188	*/
	189	if (icmpprintfs)
	190	printf("icmp_input, type %d code %d\n", icp->icmp_type,
	191	icp->icmp_code);
	192	#endif
	193	if (icp->icmp_type > ICMP_MAXTYPE)
	194	goto raw;
	195	icmpstat.icps_inhist[icp->icmp_type]++;
	196	code = icp->icmp_code;
	197	switch (icp->icmp_type) {
	198
	199	case ICMP_UNREACH:
	200	if (code > 5)
	201	goto badcode;
	202	code += PRC_UNREACH_NET;
	203	goto deliver;
	204
	205	case ICMP_TIMXCEED:
	206	if (code > 1)
	207	goto badcode;
	208	code += PRC_TIMXCEED_INTRANS;
	209	goto deliver;
	210
	211	case ICMP_PARAMPROB:
	212	if (code)
	213	goto badcode;
	214	code = PRC_PARAMPROB;
	215	goto deliver;
	216
	217	case ICMP_SOURCEQUENCH:
	218	if (code)
	219	goto badcode;
	220	code = PRC_QUENCH;
	221	deliver:
	222	/*
	223	* Problem with datagram; advise higher level routines.
	224	*/
	225	icp->icmp_ip.ip_len = ntohs((u_short)icp->icmp_ip.ip_len);
	226	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp)) {
	227	icmpstat.icps_badlen++;
	228	goto freeit;
	229	}
	230	#ifdef ICMPPRINTFS
	231	if (icmpprintfs)
	232	printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
	233	#endif
	234	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
	235	if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput)
	236	(ctlfunc)(code, (struct sockaddr )&icmpsrc);
	237	break;
	238
	239	badcode:
	240	icmpstat.icps_badcode++;
	241	break;
	242
	243	case ICMP_ECHO:
	244	icp->icmp_type = ICMP_ECHOREPLY;
	245	goto reflect;
	246
	247	case ICMP_TSTAMP:
	248	if (icmplen < ICMP_TSLEN) {
	249	icmpstat.icps_badlen++;
	250	break;
	251	}
	252	icp->icmp_type = ICMP_TSTAMPREPLY;
	253	icp->icmp_rtime = iptime();
	254	icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
	255	goto reflect;
	256
	257	case ICMP_IREQ:
	258	#define satosin(sa) ((struct sockaddr_in *)(sa))
	259	if (in_netof(ip->ip_src) == 0 &&
	260	(ia = ifptoia(m->m_pkthdr.rcvif)))
	261	ip->ip_src = in_makeaddr(in_netof(IA_SIN(ia)->sin_addr),
	262	in_lnaof(ip->ip_src));
	263	icp->icmp_type = ICMP_IREQREPLY;
	264	goto reflect;
	265
	266	case ICMP_MASKREQ:
	267	if (icmplen < ICMP_MASKLEN \|\|
	268	(ia = ifptoia(m->m_pkthdr.rcvif)) == 0)
	269	break;
	270	icp->icmp_type = ICMP_MASKREPLY;
	271	icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
	272	if (ip->ip_src.s_addr == 0) {
	273	if (ia->ia_ifp->if_flags & IFF_BROADCAST)
	274	ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
	275	else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
	276	ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
	277	}
	278	reflect:
	279	ip->ip_len += hlen; /* since ip_input deducts this */
	280	icmpstat.icps_reflect++;
	281	icmpstat.icps_outhist[icp->icmp_type]++;
	282	icmp_reflect(m);
	283	return;
	284
	285	case ICMP_REDIRECT:
	286	if (icmplen < ICMP_ADVLENMIN \|\| icmplen < ICMP_ADVLEN(icp)) {
	287	icmpstat.icps_badlen++;
	288	break;
	289	}
	290	/*
	291	* Short circuit routing redirects to force
	292	* immediate change in the kernel's routing
	293	* tables. The message is also handed to anyone
	294	* listening on a raw socket (e.g. the routing
	295	* daemon for use in updating its tables).
	296	*/
	297	icmpgw.sin_addr = ip->ip_src;
	298	icmpdst.sin_addr = icp->icmp_gwaddr;
	299	#ifdef ICMPPRINTFS
	300	if (icmpprintfs)
	301	printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst,
	302	icp->icmp_gwaddr);
	303	#endif
	304	if (code == ICMP_REDIRECT_NET \|\| code == ICMP_REDIRECT_TOSNET) {
	305	u_long in_netof();
	306	icmpsrc.sin_addr =
	307	in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY);
	308	in_sockmaskof(icp->icmp_ip.ip_dst, &icmpmask);
	309	rtredirect((struct sockaddr *)&icmpsrc,
	310	(struct sockaddr *)&icmpdst,
	311	(struct sockaddr *)&icmpmask, RTF_GATEWAY,
	312	(struct sockaddr )&icmpgw, (struct rtentry *)0);
	313	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
	314	pfctlinput(PRC_REDIRECT_NET,
	315	(struct sockaddr *)&icmpsrc);
	316	} else {
	317	icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
	318	rtredirect((struct sockaddr *)&icmpsrc,
	319	(struct sockaddr *)&icmpdst,
	320	(struct sockaddr *)0, RTF_GATEWAY \| RTF_HOST,
	321	(struct sockaddr )&icmpgw, (struct rtentry *)0);
	322	pfctlinput(PRC_REDIRECT_HOST,
	323	(struct sockaddr *)&icmpsrc);
	324	}
	325	break;
	326
	327	/*
	328	* No kernel processing for the following;
	329	* just fall through to send to raw listener.
	330	*/
	331	case ICMP_ECHOREPLY:
	332	case ICMP_TSTAMPREPLY:
	333	case ICMP_IREQREPLY:
	334	case ICMP_MASKREPLY:
	335	default:
	336	break;
	337	}
	338
	339	raw:
	340	icmpsrc.sin_addr = ip->ip_src;
	341	icmpdst.sin_addr = ip->ip_dst;
	342	raw_input(m, &icmproto, (struct sockaddr *)&icmpsrc,
	343	(struct sockaddr *)&icmpdst);
	344	return;
	345
	346	freeit:
	347	m_freem(m);
	348	}
	349
	350	/*
	351	* Reflect the ip packet back to the source
	352	*/
	353	icmp_reflect(m)
	354	struct mbuf *m;
	355	{
	356	register struct ip ip = mtod(m, struct ip );
	357	register struct in_ifaddr *ia;
	358	struct in_addr t;
	359	struct mbuf opts = 0, ip_srcroute();
	360	int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
	361
	362	t = ip->ip_dst;
	363	ip->ip_dst = ip->ip_src;
	364	/*
	365	* If the incoming packet was addressed directly to us,
	366	* use dst as the src for the reply. Otherwise (broadcast
	367	* or anonymous), use the address which corresponds
	368	* to the incoming interface.
	369	*/
	370	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
	371	if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
	372	break;
	373	if ((ia->ia_ifp->if_flags & IFF_BROADCAST) &&
	374	t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
	375	break;
	376	}
	377	if (ia == (struct in_ifaddr *)0)
	378	ia = ifptoia(m->m_pkthdr.rcvif);
	379	if (ia == (struct in_ifaddr *)0)
	380	ia = in_ifaddr;
	381	t = IA_SIN(ia)->sin_addr;
	382	ip->ip_src = t;
	383	ip->ip_ttl = MAXTTL;
	384
	385	if (optlen > 0) {
	386	register u_char *cp;
	387	struct mbuf *m = dtom(ip);
	388	int opt, cnt, off;
	389	u_int len;
	390
	391	register u_char *cp;
	392	int opt, cnt;
	393	u_int len;
	394
	395	/*
	396	* Retrieve any source routing from the incoming packet;
	397	* add on any record-route or timestamp options.
	398	*/
	399	cp = (u_char *) (ip + 1);
	400	if ((opts = ip_srcroute()) == 0 &&
	401	(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
	402	opts->m_len = sizeof(struct in_addr);
	403	mtod(opts, struct in_addr *)->s_addr = 0;
	404	}
	405	if (opts) {
	406	#ifdef ICMPPRINTFS
	407	if (icmpprintfs)
	408	printf("icmp_reflect optlen %d rt %d => ",
	409	optlen, opts->m_len);
	410	#endif
	411	for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
	412	opt = cp[IPOPT_OPTVAL];
	413	if (opt == IPOPT_EOL)
	414	break;
	415	if (opt == IPOPT_NOP)
	416	len = 1;
	417	else {
	418	len = cp[IPOPT_OLEN];
	419	if (len <= 0 \|\| len > cnt)
	420	break;
	421	}
	422	/*
	423	* should check for overflow, but it "can't happen"
	424	*/
	425	if (opt == IPOPT_RR \|\| opt == IPOPT_TS) {
	426	bcopy((caddr_t)cp,
	427	mtod(opts, caddr_t) + opts->m_len, len);
	428	opts->m_len += len;
	429	}
	430	}
	431	if (opts->m_len % 4 != 0) {
	432	*(mtod(opts, caddr_t) + opts->m_len) = IPOPT_EOL;
	433	opts->m_len++;
	434	}
	435	#ifdef ICMPPRINTFS
	436	if (icmpprintfs)
	437	printf("%d\n", opts->m_len);
	438	#endif
	439	}
	440	/*
	441	* Now strip out original options by copying rest of first
	442	* mbuf's data back, and adjust the IP length.
	443	*/
	444	ip->ip_len -= optlen;
	445	ip->ip_hl = sizeof(struct ip) >> 2;
	446	m->m_len -= optlen;
	447	if (m->m_flags & M_PKTHDR)
	448	m->m_pkthdr.len -= optlen;
	449	optlen += sizeof(struct ip);
	450	bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
	451	(unsigned)(m->m_len - sizeof(struct ip)));
	452	}
	453
	454	icmp_send(m, opts);
	455	if (opts)
	456	(void)m_free(opts);
	457	}
	458
	459	struct in_ifaddr *
	460	ifptoia(ifp)
	461	struct ifnet *ifp;
	462	{
	463	register struct in_ifaddr *ia;
	464
	465	for (ia = in_ifaddr; ia; ia = ia->ia_next)
	466	if (ia->ia_ifp == ifp)
	467	return (ia);
	468	return ((struct in_ifaddr *)0);
	469	}
	470
	471	/*
	472	* Send an icmp packet back to the ip level,
	473	* after supplying a checksum.
	474	*/
	475	icmp_send(m, opts)
	476	register struct mbuf *m;
	477	struct mbuf *opts;
	478	{
	479	register struct ip ip = mtod(m, struct ip );
	480	register int hlen;
	481	register struct icmp *icp;
	482
	483	hlen = ip->ip_hl << 2;
	484	m->m_data += hlen;
	485	m->m_len -= hlen;
	486	icp = mtod(m, struct icmp *);
	487	icp->icmp_cksum = 0;
	488	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
	489	m->m_data -= hlen;
	490	m->m_len += hlen;
	491	#ifdef ICMPPRINTFS
	492	if (icmpprintfs)
	493	printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src);
	494	#endif
	495	(void) ip_output(m, opts, (struct route *)0, 0);
	496	}
	497
	498	n_time
	499	iptime()
	500	{
	501	struct timeval atv;
	502	u_long t;
	503
	504	microtime(&atv);
	505	t = (atv.tv_sec % (246060)) * 1000 + atv.tv_usec / 1000;
	506	return (htonl(t));
	507	}