icmp6.c

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		m = m_pullup(m, preplen);
	if (m == NULL) {
		nd6log((LOG_DEBUG, "ENOBUFS in icmp6_error %d\n", __LINE__));
		return;
	}

	nip6 = mtod(m, struct ip6_hdr *);
	nip6->ip6_src  = *nip6_srcp;
	nip6->ip6_dst  = oip6->ip6_dst;

	if (IN6_IS_SCOPE_LINKLOCAL(&oip6->ip6_src))
		oip6->ip6_src.s6_addr16[1] = 0;
	if (IN6_IS_SCOPE_LINKLOCAL(&oip6->ip6_dst))
		oip6->ip6_dst.s6_addr16[1] = 0;

	icmp6 = (struct icmp6_hdr *)(nip6 + 1);
	icmp6->icmp6_type = type;
	icmp6->icmp6_code = code;
	icmp6->icmp6_pptr = htonl((u_int32_t)param);

	/*
	 * icmp6_reflect() is designed to be in the input path.
	 * icmp6_error() can be called from both input and outut path,
	 * and if we are in output path rcvif could contain bogus value.
	 * clear m->m_pkthdr.rcvif for safety, we should have enough scope
	 * information in ip header (nip6).
	 */
	m->m_pkthdr.rcvif = NULL;

	icmp6stat.icp6s_outhist[type]++;
	icmp6_reflect(m, sizeof(struct ip6_hdr)); /* header order: IPv6 - ICMPv6 */

	return;

  freeit:
	/*
	 * If we can't tell wheter or not we can generate ICMP6, free it.
	 */
	m_freem(m);
}

/*
 * Process a received ICMP6 message.
 */
int
icmp6_input(mp, offp, proto)
	struct mbuf **mp;
	int *offp, proto;
{
	struct mbuf *m = *mp, *n;
	struct ip6_hdr *ip6, *nip6;
	struct icmp6_hdr *icmp6, *nicmp6;
	int off = *offp;
	int icmp6len = m->m_pkthdr.len - *offp;
	int code, sum, noff;

	icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_msg);

#ifndef PULLDOWN_TEST
	IP6_EXTHDR_CHECK(m, off, sizeof(struct icmp6_hdr), IPPROTO_DONE);
	/* m might change if M_LOOP.  So, call mtod after this */
#endif

	/*
	 * Locate icmp6 structure in mbuf, and check
	 * that not corrupted and of at least minimum length
	 */

	ip6 = mtod(m, struct ip6_hdr *);
	if (icmp6len < sizeof(struct icmp6_hdr)) {
		icmp6stat.icp6s_tooshort++;
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_error);
		goto freeit;
	}

	/*
	 * calculate the checksum
	 */
#ifndef PULLDOWN_TEST
	icmp6 = (struct icmp6_hdr *)((caddr_t)ip6 + off);
#else
	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off, sizeof(*icmp6));
	if (icmp6 == NULL) {
		icmp6stat.icp6s_tooshort++;
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_error);
		return IPPROTO_DONE;
	}
#endif
	code = icmp6->icmp6_code;

	if ((sum = in6_cksum(m, IPPROTO_ICMPV6, off, icmp6len)) != 0) {
		nd6log((LOG_ERR,
		    "ICMP6 checksum error(%d|%x) %s\n",
		    icmp6->icmp6_type, sum, ip6_sprintf(&ip6->ip6_src)));
		icmp6stat.icp6s_checksum++;
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_error);
		goto freeit;
	}

#if defined(NFAITH) && 0 < NFAITH
	if (faithprefix(&ip6->ip6_dst)) {
		/*
		 * Deliver very specific ICMP6 type only.
		 * This is important to deilver TOOBIG.  Otherwise PMTUD
		 * will not work.
		 */
		switch (icmp6->icmp6_type) {
		case ICMP6_DST_UNREACH:
		case ICMP6_PACKET_TOO_BIG:
		case ICMP6_TIME_EXCEEDED:
			break;
		default:
			goto freeit;
		}
	}
#endif

	icmp6stat.icp6s_inhist[icmp6->icmp6_type]++;

#ifdef MIP6
	if (mip6_icmp6_tunnel_input(m, off, icmp6len)) {
		goto freeit;
	}
#endif /* MIP6 */
	switch (icmp6->icmp6_type) {
	case ICMP6_DST_UNREACH:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_dstunreach);
#ifdef MIP6
		if (mip6_icmp6_input(m, off, icmp6len))
			goto freeit;
#endif /* MIP6 */
		switch (code) {
		case ICMP6_DST_UNREACH_NOROUTE:
			code = PRC_UNREACH_NET;
			break;
		case ICMP6_DST_UNREACH_ADMIN:
			icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_adminprohib);
			code = PRC_UNREACH_PROTOCOL; /* is this a good code? */
			break;
		case ICMP6_DST_UNREACH_ADDR:
			code = PRC_HOSTDEAD;
			break;
#ifdef COMPAT_RFC1885
		case ICMP6_DST_UNREACH_NOTNEIGHBOR:
			code = PRC_UNREACH_SRCFAIL;
			break;
#else
		case ICMP6_DST_UNREACH_BEYONDSCOPE:
			/* I mean "source address was incorrect." */
			code = PRC_UNREACH_NET;
			break;
#endif
		case ICMP6_DST_UNREACH_NOPORT:
			code = PRC_UNREACH_PORT;
			break;
		default:
			goto badcode;
		}
		goto deliver;
		break;

	case ICMP6_PACKET_TOO_BIG:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_pkttoobig);
		if (code != 0)
			goto badcode;

		code = PRC_MSGSIZE;

		/*
		 * Updating the path MTU will be done after examining
		 * intermediate extension headers.
		 */
		goto deliver;
		break;

	case ICMP6_TIME_EXCEEDED:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_timeexceed);
		switch (code) {
		case ICMP6_TIME_EXCEED_TRANSIT:
			code = PRC_TIMXCEED_INTRANS;
			break;
		case ICMP6_TIME_EXCEED_REASSEMBLY:
			code = PRC_TIMXCEED_REASS;
			break;
		default:
			goto badcode;
		}
		goto deliver;
		break;

	case ICMP6_PARAM_PROB:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_paramprob);
		switch (code) {
		case ICMP6_PARAMPROB_NEXTHEADER:
			code = PRC_UNREACH_PROTOCOL;
			break;
		case ICMP6_PARAMPROB_HEADER:
		case ICMP6_PARAMPROB_OPTION:
#ifdef MIP6
			if (mip6_icmp6_input(m, off, icmp6len))
				goto freeit;
#endif /* MIP6 */
			code = PRC_PARAMPROB;
			break;
		default:
			goto badcode;
		}
		goto deliver;
		break;

	case ICMP6_ECHO_REQUEST:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_echo);
		if (code != 0)
			goto badcode;
		/*
		 * Copy mbuf to send to two data paths: userland socket(s),
		 * and to the querier (echo reply).
		 * m: a copy for socket, n: a copy for querier
		 */
		if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
			/* Give up local */
			n = m;
			m = NULL;
			goto deliverecho;
		}
		/*
		 * If the first mbuf is shared, or the first mbuf is too short,
		 * copy the first part of the data into a fresh mbuf.
		 * Otherwise, we will wrongly overwrite both copies.
		 */
		if ((n->m_flags & M_EXT) != 0 ||
		    n->m_len < off + sizeof(struct icmp6_hdr)) {
			struct mbuf *n0 = n;
			const int maxlen = sizeof(*nip6) + sizeof(*nicmp6);

			/*
			 * Prepare an internal mbuf.  m_pullup() doesn't
			 * always copy the length we specified.
			 */
			if (maxlen >= MCLBYTES) {
				/* Give up remote */
				m_freem(n0);
				break;
			}
			MGETHDR(n, M_DONTWAIT, n0->m_type);
			if (n && maxlen >= MHLEN) {
				MCLGET(n, M_DONTWAIT);
				if ((n->m_flags & M_EXT) == 0) {
					m_free(n);
					n = NULL;
				}
			}
			if (n == NULL) {
				/* Give up local */
				m_freem(n0);
				n = m;
				m = NULL;
				goto deliverecho;
			}
#ifdef __OpenBSD__
			M_MOVE_PKTHDR(n, n0);
#else
			M_COPY_PKTHDR(n, n0);
#endif
			/*
			 * Copy IPv6 and ICMPv6 only.
			 */
			nip6 = mtod(n, struct ip6_hdr *);
			bcopy(ip6, nip6, sizeof(struct ip6_hdr));
			nicmp6 = (struct icmp6_hdr *)(nip6 + 1);
			bcopy(icmp6, nicmp6, sizeof(struct icmp6_hdr));
			noff = sizeof(struct ip6_hdr);
			n->m_len = noff + sizeof(struct icmp6_hdr);
			/*
			 * Adjust mbuf.  ip6_plen will be adjusted in
			 * ip6_output().
			 * n->m_pkthdr.len == n0->m_pkthdr.len at this point.
			 */
			n->m_pkthdr.len += noff + sizeof(struct icmp6_hdr);
			n->m_pkthdr.len -= (off + sizeof(struct icmp6_hdr));
			m_adj(n0, off + sizeof(struct icmp6_hdr));
			n->m_next = n0;
			n0->m_flags &= ~M_PKTHDR;
		} else {
	 deliverecho:
			nip6 = mtod(n, struct ip6_hdr *);
			nicmp6 = (struct icmp6_hdr *)((caddr_t)nip6 + off);
			noff = off;
		}
		nicmp6->icmp6_type = ICMP6_ECHO_REPLY;
		nicmp6->icmp6_code = 0;
		if (n) {
			icmp6stat.icp6s_reflect++;
			icmp6stat.icp6s_outhist[ICMP6_ECHO_REPLY]++;
			icmp6_reflect(n, noff);
		}
		if (!m)
			goto freeit;
		break;

	case ICMP6_ECHO_REPLY:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_echoreply);
		if (code != 0)
			goto badcode;
		break;

#ifdef MIP6
	case ICMP6_HADISCOV_REQUEST:
		if (icmp6len < sizeof(struct ha_discov_req))
			goto badlen;
		if (code != 0)
			goto badcode;
		if (mip6_icmp6_input(m, off, icmp6len))
			goto freeit;
		break;
	case ICMP6_HADISCOV_REPLY:
		if (icmp6len < sizeof(struct ha_discov_rep))
			goto badlen;
		if (code != 0)
			goto badcode;
		if (mip6_icmp6_input(m, off, icmp6len))
			goto freeit;
		break;
#ifndef MIP6_DRAFT13
	case ICMP6_MOBILEPREFIX_SOLICIT:
		if (icmp6len < sizeof(struct mobile_prefix_solicit))
			goto badlen;
		if (code != 0)
			goto badcode;
		if (mip6_icmp6_input(m, off, icmp6len))
			goto freeit;
		break;

	case ICMP6_MOBILEPREFIX_ADVERT:
		if (icmp6len < sizeof (struct mobile_prefix_advert))
			goto badlen;
		if (code != 0)
			goto badcode;
		if (mip6_icmp6_input(m, off, icmp6len))
			goto freeit;
		break;
#endif /* !MIP6_DRAFT13 */
#endif /* MIP6 */

	case MLD_LISTENER_QUERY:
	case MLD_LISTENER_REPORT:
		if (icmp6len < sizeof(struct mld_hdr))
			goto badlen;
		if (icmp6->icmp6_type == MLD_LISTENER_QUERY) /* XXX: ugly... */
			icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mldquery);
		else
			icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mldreport);
		if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
			/* give up local */
			mld6_input(m, off);
			m = NULL;
			goto freeit;
		}
		mld6_input(n, off);
		/* m stays. */
		break;

	case MLD_LISTENER_DONE:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_mlddone);
		if (icmp6len < sizeof(struct mld_hdr))	/* necessary? */
			goto badlen;
		break;		/* nothing to be done in kernel */

	case MLD_MTRACE_RESP:
	case MLD_MTRACE:
		/* XXX: these two are experimental.  not officially defined. */
		/* XXX: per-interface statistics? */
		break;		/* just pass it to applications */

	case ICMP6_WRUREQUEST:	/* ICMP6_FQDN_QUERY */
	    {
		enum { WRU, FQDN } mode;

		if (!icmp6_nodeinfo)
			break;

		if (icmp6len == sizeof(struct icmp6_hdr) + 4)
			mode = WRU;
		else if (icmp6len >= sizeof(struct icmp6_nodeinfo))
			mode = FQDN;
		else
			goto badlen;

#ifdef __FreeBSD__
#define hostnamelen	strlen(hostname)
#endif
		if (mode == FQDN) {
#ifndef PULLDOWN_TEST
			IP6_EXTHDR_CHECK(m, off, sizeof(struct icmp6_nodeinfo),
					 IPPROTO_DONE);
#endif
			n = m_copym(m, 0, M_COPYALL, M_DONTWAIT);
			if (n)
				n = ni6_input(n, off);
			/* XXX meaningless if n == NULL */
			noff = sizeof(struct ip6_hdr);
		} else {
			u_char *p;
			int maxlen, maxhlen;

			if ((icmp6_nodeinfo & 5) != 5) 
				break;

			if (code != 0)
				goto badcode;
			maxlen = sizeof(*nip6) + sizeof(*nicmp6) + 4;
			if (maxlen >= MCLBYTES) {
				/* Give up remote */
				break;
			}
			MGETHDR(n, M_DONTWAIT, m->m_type);
			if (n && maxlen > MHLEN) {
				MCLGET(n, M_DONTWAIT);
				if ((n->m_flags & M_EXT) == 0) {
					m_free(n);
					n = NULL;
				}
			}
			if (n == NULL) {
				/* Give up remote */
				break;
			}
			n->m_pkthdr.rcvif = NULL;
			n->m_len = 0;
			maxhlen = M_TRAILINGSPACE(n) - maxlen;
			if (maxhlen > hostnamelen)
				maxhlen = hostnamelen;
			/*
			 * Copy IPv6 and ICMPv6 only.
			 */
			nip6 = mtod(n, struct ip6_hdr *);
			bcopy(ip6, nip6, sizeof(struct ip6_hdr));
			nicmp6 = (struct icmp6_hdr *)(nip6 + 1);
			bcopy(icmp6, nicmp6, sizeof(struct icmp6_hdr));
			p = (u_char *)(nicmp6 + 1);
			bzero(p, 4);
			bcopy(hostname, p + 4, maxhlen); /* meaningless TTL */
			noff = sizeof(struct ip6_hdr);
#ifdef __OpenBSD__
			M_DUP_PKTHDR(n, m); /* just for rcvif */
#else
			M_COPY_PKTHDR(n, m); /* just for rcvif */
#endif
			n->m_pkthdr.len = n->m_len = sizeof(struct ip6_hdr) +
				sizeof(struct icmp6_hdr) + 4 + maxhlen;
			nicmp6->icmp6_type = ICMP6_WRUREPLY;
			nicmp6->icmp6_code = 0;
		}
#undef hostnamelen
		if (n) {
			icmp6stat.icp6s_reflect++;
			icmp6stat.icp6s_outhist[ICMP6_WRUREPLY]++;
			icmp6_reflect(n, noff);
		}
		break;
	    }

	case ICMP6_WRUREPLY:
		if (code != 0)
			goto badcode;
		break;

	case ND_ROUTER_SOLICIT:
		icmp6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_routersolicit);
		if (code != 0)
			goto badcode;
		if (icmp6len < sizeof(struct nd_router_solicit))
			goto badlen;
		if ((n = m_copym(m, 0, M_COPYALL, M_DONTWAIT)) == NULL) {
			/* give up local */
			nd6_rs_input(m, off, icmp6len);
			m = NULL;
			goto freeit;