ip_icmp.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static  char    *sccsid = "@(#)ip_icmp.c	4.2          (ULTRIX)                7/17/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1985 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
 *			Modification History				*
 *	14-11-89	Ursula Sinkewicz
 *		Removed lk_in_ifaddr and lk_ifnet to coincide with
 *		slip changes.	
 *
 *	10-17-89 	Uttam Shikarpur					*
 *		Made MAXTTL a writeable entity, by introducing maxttl   *
 *									*
 *	28-May-89	Matt Thomas					*
 *		Fix panic on ICMP_INFOTYPE messages.  Also fix option	*
 *		probnlems in icmp_reflect()				*
 *									*
 *	27-Mar-89	U. Sinkewicz
 *		Lowered ipl of lk_rtentry, lk_ifnet, lk_in_ifaddr, as per
 *		lp changes made 3/16/89.
 *
 *	3-Mar-89	U. Sinkewicz
 *		Put new directory layout into smp file.
 *	
 *	15-Jan-88	lp
 *		Merge of final 43BSD changes.
 *
 *	Larry Cohen  -	09/16/85					*
 * 		Add 43bsd alpha tape changes for subnet routing		*
 *									*
 ************************************************************************/

/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *	ip_icmp.c	7.6 (Berkeley) 8/31/87
 */

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

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

#include "../net/netinet/in.h"
#include "../net/netinet/in_systm.h"
#include "../net/netinet/in_var.h"
#include "../net/netinet/ip.h"
#include "../net/netinet/ip_icmp.h"
#include "../net/netinet/icmp_var.h"

#ifdef ICMPPRINTFS
/*
 * ICMP routines: error generation, receive packet processing, and
 * routines to turnaround packets back to the originator, and
 * host table maintenance routines.
 */
int	icmpprintfs = 0;
#endif
/* initialize maxttl to MAXTTL, defined in ip.h */
int maxttl = MAXTTL;
/*
 * Generate an error packet of type error
 * in response to bad packet ip.
 */
/*VARARGS4*/
icmp_error(oip, type, code, ifp, dest)
	struct ip *oip;
	int type, code;
	struct ifnet *ifp;
	struct in_addr dest;
{
	register unsigned oiplen = oip->ip_hl << 2;
	register struct icmp *icp;
	struct mbuf *m;
	struct ip *nip;
	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 free;
	/*
	 * Pullup what we need into a single mbuf since the first
	 * mbuf could contain only the IP header, which results
	 * in a panic when attempting to point beyond end of data
	 * when we execute the ICMP_INFOTYPE macro or copy the old
	 * header.
	 */
	m = dtom(oip);
	/* Always need to see the stuff we're sending back */
	icmplen = oiplen + MIN(8, oip->ip_len);

	if (oip->ip_p == IPPROTO_ICMP)
		/* need to see first word (or less) of orginal ICMP */
		icmplen = MAX(icmplen, (oiplen + sizeof(long)));

	if (m->m_len < icmplen) {
		m = m_pullup(m, icmplen);
		if (m == 0) {
			return;
		}
		oip = mtod(m, struct ip *);
	}
	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
	  !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
		icmpstat.icps_oldicmp++;
		goto free;
	}

	/*
	 * First, formulate icmp message
	 */
	m = m_get(M_DONTWAIT, MT_DATA);
	if (m == NULL)
		goto free;
	icmplen = oiplen + MIN(8, oip->ip_len);
	m->m_len = icmplen + ICMP_MINLEN;
	m->m_off = MMAXOFF - 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 += oiplen;
	nip->ip_len = htons((u_short)nip->ip_len);

	/*
	 * Now, copy old ip header in front of icmp message.  
	 */
	if (m->m_len + oiplen > MLEN)
		oiplen = sizeof(struct ip);
	if (m->m_len + oiplen > MLEN)
		panic("icmp len");
	m->m_off -= oiplen;
	m->m_len += oiplen;
	nip = mtod(m, struct ip *);
	bcopy((caddr_t)oip, (caddr_t)nip, oiplen);
	nip->ip_len = m->m_len;
	nip->ip_p = IPPROTO_ICMP;
	nip->ip_off = 0;	/* keep DF flag for return packet */
	icmp_reflect(nip, ifp);

free:
	m_freem(dtom(oip));
}

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

/*
 * Process a received ICMP message.
 */
icmp_input(m, ifp)
	register struct mbuf *m;
	struct ifnet *ifp;
{
	register struct icmp *icp;
	register struct ip *ip = mtod(m, struct ip *);
	int icmplen = ip->ip_len, hlen = ip->ip_hl << 2;
	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 free;
	}
	i = hlen + MIN(icmplen, ICMP_ADVLENMIN);
 	if ((m->m_off > MMAXOFF || 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_off += hlen;
	icp = mtod(m, struct icmp *);
	if (in_cksum(m, icmplen)) {
		icmpstat.icps_checksum++;
		goto free;
	}
	m->m_len += hlen;
	m->m_off -= 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 free;
		}
#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(ifp))){	
			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(ifp)) == 0){
			break;
		}
		icp->icmp_type = ICMP_MASKREPLY;
		icp->icmp_mask = htonl(ia->ia_subnetmask);
		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(ip, ifp);
		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) {
			icmpsrc.sin_addr =
			 in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY);
			rtredirect((struct sockaddr *)&icmpsrc,
			  (struct sockaddr *)&icmpdst, RTF_GATEWAY,
				(struct sockaddr *)&icmpgw);
			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, RTF_GATEWAY | RTF_HOST,
			  (struct sockaddr *)&icmpgw);
			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;

free:
	m_freem(m);
}

/*
 * Reflect the ip packet back to the source
 */
icmp_reflect(ip, ifp)
	register struct ip *ip;
	struct ifnet *ifp;
{
	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(ifp);
	if (ia == (struct in_ifaddr *)0){
		ia = in_ifaddr;
	}
	t = IA_SIN(ia)->sin_addr;
	ip->ip_src = t;
	ip->ip_ttl = maxttl;
	ip->ip_off = 0;	/* clear DF flag */

	if (optlen > 0) {
		/*
		 * Retrieve any source routing from the incoming packet
		 * and imerge in the other non-routing options.  Adjust
		 * the IP length.
		 */
		opts = ip_srcroute();
		if (!opts && (opts = m_get(M_DONTWAIT, MT_SOOPTS)))
			opts->m_len = 0;
		ip_stripoptions(ip, opts);
		ip->ip_len -= optlen;
	}
	icmp_send(ip, 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(ip, opts)
	register struct ip *ip;
	struct mbuf *opts;
{
	register int hlen;
	register struct icmp *icp;
	register struct mbuf *m;

	m = dtom(ip);
	hlen = ip->ip_hl << 2;
	m->m_off += 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_off -= 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, 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));
}