nd6_nbr.c

来自「eCos操作系统源码」· C语言 代码 · 共 1,526 行 · 第 1/3 页

		else {
			ia = in6_ifawithifp(ifp, &ip6->ip6_dst);
			if (ia == NULL) {
				m_freem(m);
				return;
			}
			ip6->ip6_src = ia->ia_addr.sin6_addr;
		}
	} else {
		/*
		 * Source address for DAD packet must always be IPv6
		 * unspecified address. (0::0)
		 */
		bzero(&ip6->ip6_src, sizeof(ip6->ip6_src));
	}
	nd_ns = (struct nd_neighbor_solicit *)(ip6 + 1);
	nd_ns->nd_ns_type = ND_NEIGHBOR_SOLICIT;
	nd_ns->nd_ns_code = 0;
	nd_ns->nd_ns_reserved = 0;
	nd_ns->nd_ns_target = *taddr6;

	if (IN6_IS_SCOPE_LINKLOCAL(&nd_ns->nd_ns_target))
		nd_ns->nd_ns_target.s6_addr16[1] = 0;

	/*
	 * Add source link-layer address option.
	 *
	 *				spec		implementation
	 *				---		---
	 * DAD packet			MUST NOT	do not add the option
	 * there's no link layer address:
	 *				impossible	do not add the option
	 * there's link layer address:
	 *	Multicast NS		MUST add one	add the option
	 *	Unicast NS		SHOULD add one	add the option
	 */
	if (!dad && (mac = nd6_ifptomac(ifp))) {
		int optlen = sizeof(struct nd_opt_hdr) + ifp->if_addrlen;
		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_ns + 1);
		/* 8 byte alignments... */
		optlen = (optlen + 7) & ~7;
		
		m->m_pkthdr.len += optlen;
		m->m_len += optlen;
		icmp6len += optlen;
		bzero((caddr_t)nd_opt, optlen);
		nd_opt->nd_opt_type = ND_OPT_SOURCE_LINKADDR;
		nd_opt->nd_opt_len = optlen >> 3;
		bcopy(mac, (caddr_t)(nd_opt + 1), ifp->if_addrlen);
	}

	ip6->ip6_plen = htons((u_short)icmp6len);
	nd_ns->nd_ns_cksum = 0;
	nd_ns->nd_ns_cksum
		= in6_cksum(m, IPPROTO_ICMPV6, sizeof(*ip6), icmp6len);

#ifdef IPSEC
	/* Don't lookup socket */
	(void)ipsec_setsocket(m, NULL);
#endif
	ip6_output(m, NULL, NULL, dad ? IPV6_UNSPECSRC : 0, &im6o, NULL);
	icmp6_ifstat_inc(ifp, ifs6_out_msg);
	icmp6_ifstat_inc(ifp, ifs6_out_neighborsolicit);
	icmp6stat.icp6s_outhist[ND_NEIGHBOR_SOLICIT]++;

	return;

  bad:
	m_freem(m);
	return;
}

/*
 * Neighbor advertisement input handling.
 *
 * Based on RFC 2461
 * Based on RFC 2462 (duplicated address detection)
 *
 * the following items are not implemented yet:
 * - proxy advertisement delay rule (RFC2461 7.2.8, last paragraph, SHOULD)
 * - anycast advertisement delay rule (RFC2461 7.2.7, SHOULD)
 */
void
nd6_na_input(m, off, icmp6len)
	struct mbuf *m;
	int off, icmp6len;
{
	struct ifnet *ifp = m->m_pkthdr.rcvif;
	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
	struct nd_neighbor_advert *nd_na;
#if 0
	struct in6_addr saddr6 = ip6->ip6_src;
#endif
	struct in6_addr daddr6 = ip6->ip6_dst;
	struct in6_addr taddr6;
	int flags;
	int is_router;
	int is_solicited;
	int is_override;
	char *lladdr = NULL;
	int lladdrlen = 0;
	struct ifaddr *ifa;
	struct llinfo_nd6 *ln;
	struct rtentry *rt;
	struct sockaddr_dl *sdl;
	union nd_opts ndopts;
#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3)
	long time_second = time.tv_sec;
#endif

	if (ip6->ip6_hlim != 255) {
		nd6log((LOG_ERR,
		    "nd6_na_input: invalid hlim (%d) from %s to %s on %s\n",
		    ip6->ip6_hlim, ip6_sprintf(&ip6->ip6_src),
		    ip6_sprintf(&ip6->ip6_dst), if_name(ifp)));
		goto bad;
	}

#ifndef PULLDOWN_TEST
	IP6_EXTHDR_CHECK(m, off, icmp6len,);
	nd_na = (struct nd_neighbor_advert *)((caddr_t)ip6 + off);
#else
	IP6_EXTHDR_GET(nd_na, struct nd_neighbor_advert *, m, off, icmp6len);
	if (nd_na == NULL) {
		icmp6stat.icp6s_tooshort++;
		return;
	}
#endif
	taddr6 = nd_na->nd_na_target;
	flags = nd_na->nd_na_flags_reserved;
	is_router = ((flags & ND_NA_FLAG_ROUTER) != 0);
	is_solicited = ((flags & ND_NA_FLAG_SOLICITED) != 0);
	is_override = ((flags & ND_NA_FLAG_OVERRIDE) != 0);

	if (IN6_IS_SCOPE_LINKLOCAL(&taddr6))
		taddr6.s6_addr16[1] = htons(ifp->if_index);

	if (IN6_IS_ADDR_MULTICAST(&taddr6)) {
		nd6log((LOG_ERR,
		    "nd6_na_input: invalid target address %s\n",
		    ip6_sprintf(&taddr6)));
		goto bad;
	}
	if (IN6_IS_ADDR_MULTICAST(&daddr6))
		if (is_solicited) {
			nd6log((LOG_ERR,
			    "nd6_na_input: a solicited adv is multicasted\n"));
			goto bad;
		}

	icmp6len -= sizeof(*nd_na);
	nd6_option_init(nd_na + 1, icmp6len, &ndopts);
	if (nd6_options(&ndopts) < 0) {
		nd6log((LOG_INFO,
		    "nd6_na_input: invalid ND option, ignored\n"));
		/* nd6_options have incremented stats */
		goto freeit;
	}

	if (ndopts.nd_opts_tgt_lladdr) {
		lladdr = (char *)(ndopts.nd_opts_tgt_lladdr + 1);
		lladdrlen = ndopts.nd_opts_tgt_lladdr->nd_opt_len << 3;
	}

	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
#ifdef MIP6
	if (!ifa) {
		ifa = mip6_dad_find(&taddr6, ifp);
	}
#endif

	/*
	 * Target address matches one of my interface address.
	 *
	 * If my address is tentative, this means that there's somebody
	 * already using the same address as mine.  This indicates DAD failure.
	 * This is defined in RFC 2462.
	 *
	 * Otherwise, process as defined in RFC 2461.
	 */
	if (ifa
	 && (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_TENTATIVE)) {
		nd6_dad_na_input(ifa);
		goto freeit;
	}

	/* Just for safety, maybe unnecessary. */
	if (ifa) {
		log(LOG_ERR,
		    "nd6_na_input: duplicate IP6 address %s\n",
		    ip6_sprintf(&taddr6));
		goto freeit;
	}

	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
		nd6log((LOG_INFO,
		    "nd6_na_input: lladdrlen mismatch for %s "
		    "(if %d, NA packet %d)\n",
			ip6_sprintf(&taddr6), ifp->if_addrlen, lladdrlen - 2));
		goto bad;
	}

	/*
	 * If no neighbor cache entry is found, NA SHOULD silently be discarded.
	 */
	rt = nd6_lookup(&taddr6, 0, ifp);
	if ((rt == NULL) ||
	   ((ln = (struct llinfo_nd6 *)rt->rt_llinfo) == NULL) ||
	   ((sdl = SDL(rt->rt_gateway)) == NULL))
		goto freeit;

	if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
		/*
		 * If the link-layer has address, and no lladdr option came,
		 * discard the packet.
		 */
		if (ifp->if_addrlen && !lladdr)
			goto freeit;

		/*
		 * Record link-layer address, and update the state.
		 */
		sdl->sdl_alen = ifp->if_addrlen;
		bcopy(lladdr, LLADDR(sdl), ifp->if_addrlen);
		if (is_solicited) {
			ln->ln_state = ND6_LLINFO_REACHABLE;
			ln->ln_byhint = 0;
			if (ln->ln_expire)
				ln->ln_expire = time_second +
				    nd_ifinfo[rt->rt_ifp->if_index].reachable;
		} else {
			ln->ln_state = ND6_LLINFO_STALE;
			ln->ln_expire = time_second + nd6_gctimer;
		}
		if ((ln->ln_router = is_router) != 0) {
			/*
			 * This means a router's state has changed from
			 * non-reachable to probably reachable, and might
			 * affect the status of associated prefixes..
			 */
			pfxlist_onlink_check();
		}
	} else {
		int llchange;

		/*
		 * Check if the link-layer address has changed or not.
		 */
		if (!lladdr)
			llchange = 0;
		else {
			if (sdl->sdl_alen) {
				if (bcmp(lladdr, LLADDR(sdl), ifp->if_addrlen))
					llchange = 1;
				else
					llchange = 0;
			} else
				llchange = 1;
		}

		/*
		 * This is VERY complex.  Look at it with care.
		 *
		 * override solicit lladdr llchange	action
		 *					(L: record lladdr)
		 *
		 *	0	0	n	--	(2c)
		 *	0	0	y	n	(2b) L
		 *	0	0	y	y	(1)    REACHABLE->STALE
		 *	0	1	n	--	(2c)   *->REACHABLE
		 *	0	1	y	n	(2b) L *->REACHABLE
		 *	0	1	y	y	(1)    REACHABLE->STALE
		 *	1	0	n	--	(2a)
		 *	1	0	y	n	(2a) L
		 *	1	0	y	y	(2a) L *->STALE
		 *	1	1	n	--	(2a)   *->REACHABLE
		 *	1	1	y	n	(2a) L *->REACHABLE
		 *	1	1	y	y	(2a) L *->REACHABLE
		 */
		if (!is_override && (lladdr && llchange)) {	   /* (1) */
			/*
			 * If state is REACHABLE, make it STALE.
			 * no other updates should be done.
			 */
			if (ln->ln_state == ND6_LLINFO_REACHABLE) {
				ln->ln_state = ND6_LLINFO_STALE;
				ln->ln_expire = time_second + nd6_gctimer;
			}
			goto freeit;
		} else if (is_override				   /* (2a) */
			|| (!is_override && (lladdr && !llchange)) /* (2b) */
			|| !lladdr) {				   /* (2c) */
			/*
			 * Update link-local address, if any.
			 */
			if (lladdr) {
				sdl->sdl_alen = ifp->if_addrlen;
				bcopy(lladdr, LLADDR(sdl), ifp->if_addrlen);
			}

			/*
			 * If solicited, make the state REACHABLE.
			 * If not solicited and the link-layer address was
			 * changed, make it STALE.
			 */
			if (is_solicited) {
				ln->ln_state = ND6_LLINFO_REACHABLE;
				ln->ln_byhint = 0;
				if (ln->ln_expire) {
					ln->ln_expire = time_second +
					    nd_ifinfo[ifp->if_index].reachable;
				}
			} else {
				if (lladdr && llchange) {
					ln->ln_state = ND6_LLINFO_STALE;
					ln->ln_expire = time_second + nd6_gctimer;
				}
			}
		}

		if (ln->ln_router && !is_router) {
			/*
			 * The peer dropped the router flag.
			 * Remove the sender from the Default Router List and
			 * update the Destination Cache entries.
			 */
			struct nd_defrouter *dr;
			struct in6_addr *in6;
			int s;

			in6 = &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr;

			/*
			 * Lock to protect the default router list.
			 * XXX: this might be unnecessary, since this function
			 * is only called under the network software interrupt
			 * context.  However, we keep it just for safety.  
			 */
#ifdef __NetBSD__
			s = splsoftnet();
#else
			s = splnet();
#endif
			dr = defrouter_lookup(in6, rt->rt_ifp);
			if (dr)
				defrtrlist_del(dr);
			else if (!ip6_forwarding && ip6_accept_rtadv) {
				/*
				 * Even if the neighbor is not in the default
				 * router list, the neighbor may be used
				 * as a next hop for some destinations
				 * (e.g. redirect case). So we must
				 * call rt6_flush explicitly.
				 */
				rt6_flush(&ip6->ip6_src, rt->rt_ifp);
			}
			splx(s);
		}
		ln->ln_router = is_router;
	}
	rt->rt_flags &= ~RTF_REJECT;
	ln->ln_asked = 0;
	if (ln->ln_hold) {
		/*
		 * we assume ifp is not a p2p here, so just set the 2nd
		 * argument as the 1st one.
		 */
		nd6_output(ifp, ifp, ln->ln_hold,
			   (struct sockaddr_in6 *)rt_key(rt), rt);
		ln->ln_hold = 0;
	}

 freeit:
	m_freem(m);
	return;

 bad:
	icmp6stat.icp6s_badna++;
	m_freem(m);
}

/*
 * Neighbor advertisement output handling.
 *
 * Based on RFC 2461
 *
 * the following items are not implemented yet:
 * - proxy advertisement delay rule (RFC2461 7.2.8, last paragraph, SHOULD)
 * - anycast advertisement delay rule (RFC2461 7.2.7, SHOULD)
 */
void
nd6_na_output(ifp, daddr6, taddr6, flags, tlladdr, sdl0)
	struct ifnet *ifp;
	const struct in6_addr *daddr6, *taddr6;
	u_long flags;
	int tlladdr;		/* 1 if include target link-layer address */
	struct sockaddr *sdl0;	/* sockaddr_dl (= proxy NA) or NULL */
{
	struct mbuf *m;
	struct ip6_hdr *ip6;
	struct nd_neighbor_advert *nd_na;
	struct in6_ifaddr *ia = NULL;
	struct ip6_moptions im6o;
	int icmp6len;
	int maxlen;
	caddr_t mac = NULL;

	/* estimate the size of message */
	maxlen = sizeof(*ip6) + sizeof(*nd_na);
	maxlen += (sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7;
#ifdef DIAGNOSTIC
	if (max_linkhdr + maxlen >= MCLBYTES) {
		printf("nd6_na_output: max_linkhdr + maxlen >= MCLBYTES "
		    "(%d + %d > %d)\n", max_linkhdr, maxlen, MCLBYTES);
		panic("nd6_na_output: insufficient MCLBYTES");
		/* NOTREACHED */
	}
#endif

	MGETHDR(m, M_DONTWAIT, MT_DATA);
	if (m && max_linkhdr + maxlen >= MHLEN) {
		MCLGET(m, M_DONTWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			m = NULL;
		}
	}
	if (m == NULL)
		return;
	m->m_pkthdr.rcvif = NULL;

	if (IN6_IS_ADDR_MULTICAST(daddr6)) {
		m->m_flags |= M_MCAST;
		im6o.im6o_multicast_ifp = ifp;
		im6o.im6o_multicast_hlim = 255;
		im6o.im6o_multicast_loop = 0;
	}

	icmp6len = sizeof(*nd_na);
	m->m_pkthdr.len = m->m_len = sizeof(struct ip6_hdr) + icmp6len;
	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */

	/* fill neighbor advertisement packet */
	ip6 = mtod(m, struct ip6_hdr *);
	ip6->ip6_flow = 0;
	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
	ip6->ip6_vfc |= IPV6_VERSION;
	ip6->ip6_nxt = IPPROTO_ICMPV6;
	ip6->ip6_hlim = 255;
	if (IN6_IS_ADDR_UNSPECIFIED(daddr6)) {
		/* reply to DAD */
		ip6->ip6_dst.s6_addr16[0] = IPV6_ADDR_INT16_MLL;
		ip6->ip6_dst.s6_addr16[1] = htons(ifp->if_index);
		ip6->ip6_dst.s6_addr32[1] = 0;
		ip6->ip6_dst.s6_addr32[2] = 0;
		ip6->ip6_dst.s6_addr32[3] = IPV6_ADDR_INT32_ONE;
		flags &= ~ND_NA_FLAG_SOLICITED;
	} else
		ip6->ip6_dst = *daddr6;

	/*
	 * Select a source whose scope is the same as that of the dest.
	 */
	ia = in6_ifawithifp(ifp, &ip6->ip6_dst);
	if (ia == NULL) {
		m_freem(m);
		return;
	}
	ip6->ip6_src = ia->ia_addr.sin6_addr;
	nd_na = (struct nd_neighbor_advert *)(ip6 + 1);
	nd_na->nd_na_type = ND_NEIGHBOR_ADVERT;
	nd_na->nd_na_code = 0;
	nd_na->nd_na_target = *taddr6;
	if (IN6_IS_SCOPE_LINKLOCAL(&nd_na->nd_na_target))
		nd_na->nd_na_target.s6_addr16[1] = 0;

	/*
	 * "tlladdr" indicates NS's condition for adding tlladdr or not.
	 * see nd6_ns_input() for details.
	 * Basically, if NS packet is sent to unicast/anycast addr,
	 * target lladdr option SHOULD NOT be included.
	 */
	if (tlladdr) {
		mac = NULL;
		/*
		 * sdl0 != NULL indicates proxy NA.  If we do proxy, use
		 * lladdr in sdl0.  If we are not proxying (sending NA for
		 * my address) use lladdr configured for the interface.
		 */
		if (sdl0 == NULL)
			mac = nd6_ifptomac(ifp);
		else if (sdl0->sa_family == AF_LINK) {
			struct sockaddr_dl *sdl;
			sdl = (struct sockaddr_dl *)sdl0;
			if (sdl->sdl_alen == ifp->if_addrlen)
				mac = LLADDR(sdl);
		}
	}
	if (tlladdr && mac) {
		int optlen = sizeof(struct nd_opt_hdr) + ifp->if_addrlen;
		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_na + 1);
		
		/* roundup to 8 bytes alignment! */
		optlen = (optlen + 7) & ~7;

		m->m_pkthdr.len += optlen;
		m->m_len += optlen;
		icmp6len += optlen;
		bzero((caddr_t)nd_opt, optlen);