bring in KAME IPv6 code, dated 19991208.

replaces NRL IPv6 layer.  reuses NRL pcb layer.  no IPsec-on-v6 support.
see sys/netinet6/{TODO,IMPLEMENTATION} for more details.

GENERIC configuration should work fine as before.  GENERIC.v6 works fine
as well, but you'll need KAME userland tools to play with IPv6 (will be
bringed into soon).

1 files changed, 668 insertions, 0 deletions

diff --git a/sys/netinet6/frag6.c b/sys/netinet6/frag6.c
new file mode 100644
index 00000000000..bf0612d9bef
--- /dev/null
+++ b/sys/netinet6/frag6.c
@@ -0,0 +1,668 @@
+/*	$OpenBSD: frag6.c,v 1.1 1999/12/08 06:50:20 itojun Exp $	*/
+
+/*
+ * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/domain.h>
+#include <sys/protosw.h>
+#include <sys/socket.h>
+#include <sys/errno.h>
+#include <sys/time.h>
+#include <sys/kernel.h>
+#include <sys/syslog.h>
+
+#include <net/if.h>
+#include <net/route.h>
+
+#include <netinet/in.h>
+#include <netinet/in_var.h>
+#include <netinet6/ip6.h>
+#if !(defined(__FreeBSD__) && __FreeBSD__ >= 3) && !defined(__OpenBSD__)
+#include <netinet6/in6_pcb.h>
+#endif
+#include <netinet6/ip6_var.h>
+#include <netinet6/icmp6.h>
+
+#include <net/net_osdep.h>
+
+/*
+ * Define it to get a correct behavior on per-interface statistics.
+ * You will need to perform an extra routing table lookup, per fragment,
+ * to do it.  This may, or may not be, a performance hit.
+ */
+#define IN6_IFSTAT_STRICT
+
+static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
+static void frag6_deq __P((struct ip6asfrag *));
+static void frag6_insque __P((struct ip6q *, struct ip6q *));
+static void frag6_remque __P((struct ip6q *));
+static void frag6_freef __P((struct ip6q *));
+
+int frag6_doing_reass;
+u_int frag6_nfragpackets;
+struct	ip6q ip6q;	/* ip6 reassemble queue */
+
+/* FreeBSD tweak */
+#if !defined(M_FTABLE) && (defined(__FreeBSD__) && __FreeBSD__ >= 3)
+MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
+#endif
+
+/*
+ * Initialise reassembly queue and fragment identifier.
+ */
+void
+frag6_init()
+{
+	struct timeval tv;
+
+	/*
+	 * in many cases, random() here does NOT return random number
+	 * as initialization during bootstrap time occur in fixed order.
+	 */
+	microtime(&tv);
+	ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
+	ip6_id = random() ^ tv.tv_usec;
+}
+
+/*
+ * Fragment input
+ */
+int
+frag6_input(mp, offp, proto)
+	struct mbuf **mp;
+	int *offp, proto;
+{
+	struct mbuf *m = *mp, *t;
+	struct ip6_hdr *ip6;
+	struct ip6_frag *ip6f;
+	struct ip6q *q6;
+	struct ip6asfrag *af6, *ip6af;
+	int offset = *offp, nxt, i, next;
+	int first_frag = 0;
+	u_short fragoff, frgpartlen;
+	struct ifnet *dstifp;
+#ifdef IN6_IFSTAT_STRICT
+	static struct route_in6 ro;
+	struct sockaddr_in6 *dst;
+#endif
+
+	ip6 = mtod(m, struct ip6_hdr *);
+#ifndef PULLDOWN_TEST
+	IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
+	ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
+#else
+	IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
+	if (ip6f == NULL)
+		return IPPROTO_DONE;
+#endif
+
+	dstifp = NULL;
+#ifdef IN6_IFSTAT_STRICT
+	/* find the destination interface of the packet. */
+	dst = (struct sockaddr_in6 *)&ro.ro_dst;
+	if (ro.ro_rt
+	 && ((ro.ro_rt->rt_flags & RTF_UP) == 0
+	  || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
+		RTFREE(ro.ro_rt);
+		ro.ro_rt = (struct rtentry *)0;
+	}
+	if (ro.ro_rt == NULL) {
+		bzero(dst, sizeof(*dst));
+		dst->sin6_family = AF_INET6;
+		dst->sin6_len = sizeof(struct sockaddr_in6);
+		dst->sin6_addr = ip6->ip6_dst;
+	}
+#if defined(__NetBSD__) || defined(__OpenBSD__)
+	rtalloc((struct route *)&ro);
+#else
+	rtcalloc((struct route *)&ro);
+#endif
+	if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
+		dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
+#else
+	/* we are violating the spec, this is not the destination interface */
+	if ((m->m_flags & M_PKTHDR) != 0)
+		dstifp = m->m_pkthdr.rcvif;
+#endif
+
+	/* jumbo payload can't contain a fragment header */
+	if (ip6->ip6_plen == 0) {
+		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
+		in6_ifstat_inc(dstifp, ifs6_reass_fail);
+		return IPPROTO_DONE;
+	}
+
+	/*
+	 * check whether fragment packet's fragment length is
+	 * multiple of 8 octets. 
+	 * sizeof(struct ip6_frag) == 8
+	 * sizeof(struct ip6_hdr) = 40
+	 */
+	if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
+	    (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
+		icmp6_error(m, ICMP6_PARAM_PROB,
+			    ICMP6_PARAMPROB_HEADER,
+			    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
+		in6_ifstat_inc(dstifp, ifs6_reass_fail);
+		return IPPROTO_DONE;
+	}
+
+	ip6stat.ip6s_fragments++;
+	in6_ifstat_inc(dstifp, ifs6_reass_reqd);
+	
+	/*
+	 * Presence of header sizes in mbufs
+	 * would confuse code below.
+	 */
+#ifdef PULLDOWN_TEST
+	/* XXX too strong mbuf requirement in m_pulldown() world */
+#endif
+	offset += sizeof(struct ip6_frag);
+	m->m_data += offset;
+	m->m_len -= offset;
+
+	for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
+		if (ip6f->ip6f_ident == q6->ip6q_ident &&
+		    IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
+		    IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
+			break;
+
+	if (q6 == &ip6q) {
+		/*
+		 * the first fragment to arrive, create a reassembly queue.
+		 */
+		first_frag = 1;
+		frag6_nfragpackets++;
+
+		/*
+		 * Enforce upper bound on number of fragmented packets
+		 * for which we attempt reassembly; 
+		 * If maxfrag is 0, never accept fragments.
+		 * If maxfrag is -1, accept all fragments without limitation.
+		 */
+		if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) {
+			ip6stat.ip6s_fragoverflow++;
+			in6_ifstat_inc(dstifp, ifs6_reass_fail);
+			frag6_freef(ip6q.ip6q_prev);
+		}
+		q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
+			M_DONTWAIT);
+		if (q6 == NULL)
+			goto dropfrag;
+
+		frag6_insque(q6, &ip6q);
+
+		q6->ip6q_down	= q6->ip6q_up = (struct ip6asfrag *)q6;
+#if 0
+		/*
+		 * It is not necessarily the first segment; fragment offset
+		 * might be non-0.
+		 */
+		q6->ip6q_nxt	= ip6f->ip6f_nxt;
+#endif
+#ifdef notyet
+		q6->ip6q_nxtp	= (u_char *)nxtp;
+#endif
+		q6->ip6q_ident	= ip6f->ip6f_ident;
+		q6->ip6q_arrive = 0; /* Is it used anywhere? */
+		q6->ip6q_ttl 	= IPV6_FRAGTTL;
+		q6->ip6q_src	= ip6->ip6_src;
+		q6->ip6q_dst	= ip6->ip6_dst;
+		q6->ip6q_unfrglen = -1;	/* The 1st fragment has not arrived. */
+	}
+
+	/*
+	 * If it's the 1st fragment, record the length of the
+	 * unfragmentable part and the next header of the fragment header.
+	 */
+	fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
+	if (fragoff == 0) {
+		q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
+			- sizeof(struct ip6_frag);
+		q6->ip6q_nxt = ip6f->ip6f_nxt;
+	}
+
+	/*
+	 * Check that the reassembled packet would not exceed 65535 bytes
+	 * in size.
+	 * If it would exceed, discard the fragment and return an ICMP error.
+	 */
+	frgpartlen =  sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
+	if (q6->ip6q_unfrglen >= 0) {
+		/* The 1st fragment has already arrived. */
+		if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
+			m->m_data -= offset;
+			m->m_len += offset;
+			icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
+				    offset - sizeof(struct ip6_frag) + 2);
+			return(IPPROTO_DONE);
+		}
+	}
+	else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
+		m->m_data -= offset;
+		m->m_len += offset;
+		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
+			    offset - sizeof(struct ip6_frag) + 2);
+		return(IPPROTO_DONE);
+	}
+	/*
+	 * If it's the first fragment, do the above check for each
+	 * fragment already stored in the reassembly queue.
+	 */
+	if (fragoff == 0) {
+		struct ip6asfrag *af6dwn;
+		
+		for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
+		     af6 = af6dwn) {
+			af6dwn = af6->ip6af_down;
+
+			if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
+			    IPV6_MAXPACKET) {
+				struct mbuf *merr = IP6_REASS_MBUF(af6);
+				struct ip6_hdr *ip6err;
+				int erroff = af6->ip6af_offset;
+
+				/* dequeue the fragment. */
+				frag6_deq(af6);
+
+				/* adjust pointer. */
+				merr->m_data -= af6->ip6af_offset;
+				merr->m_len += af6->ip6af_offset;
+				ip6err = mtod(merr, struct ip6_hdr *);
+
+				/*
+				 * Restore source and destination addresses
+				 * in the erroneous IPv6 header.
+				 */
+				ip6err->ip6_src = q6->ip6q_src;
+				ip6err->ip6_dst = q6->ip6q_dst;
+
+				icmp6_error(merr, ICMP6_PARAM_PROB,
+					    ICMP6_PARAMPROB_HEADER,
+					    erroff - sizeof(struct ip6_frag) + 2);
+			}
+		}
+	}
+
+	/* Override the IPv6 header */
+	ip6af = (struct ip6asfrag *)ip6;
+	ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
+	ip6af->ip6af_off = fragoff;
+	ip6af->ip6af_frglen = frgpartlen;
+	ip6af->ip6af_offset = offset;
+	IP6_REASS_MBUF(ip6af) = m;
+
+	if (first_frag) {
+		af6 = (struct ip6asfrag *)q6;
+		goto insert;
+	}
+
+	/*
+	 * Find a segment which begins after this one does.
+	 */
+	for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
+	     af6 = af6->ip6af_down)
+		if (af6->ip6af_off > ip6af->ip6af_off)
+			break;
+
+#if 0
+	/*
+	 * If there is a preceding segment, it may provide some of
+	 * our data already.  If so, drop the data from the incoming
+	 * segment.  If it provides all of our data, drop us.
+	 */
+	if (af6->ip6af_up != (struct ip6asfrag *)q6) {
+		i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
+			- ip6af->ip6af_off;
+		if (i > 0) {
+			if (i >= ip6af->ip6af_frglen)
+				goto dropfrag;
+			m_adj(IP6_REASS_MBUF(ip6af), i);
+			ip6af->ip6af_off += i;
+			ip6af->ip6af_frglen -= i;
+		}
+	}
+
+	/*
+	 * While we overlap succeeding segments trim them or,
+	 * if they are completely covered, dequeue them.
+	 */
+	while (af6 != (struct ip6asfrag *)q6 &&
+	       ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
+		i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
+		if (i < af6->ip6af_frglen) {
+			af6->ip6af_frglen -= i;
+			af6->ip6af_off += i;
+			m_adj(IP6_REASS_MBUF(af6), i);
+			break;
+		}
+		af6 = af6->ip6af_down;
+		m_freem(IP6_REASS_MBUF(af6->ip6af_up));
+		frag6_deq(af6->ip6af_up);
+	}
+#else
+	/*
+	 * If the incoming framgent overlaps some existing fragments in
+	 * the reassembly queue, drop it, since it is dangerous to override
+	 * existing fragments from a security point of view.
+	 */
+	if (af6->ip6af_up != (struct ip6asfrag *)q6) {
+		i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
+			- ip6af->ip6af_off;
+		if (i > 0) {
+			log(LOG_ERR, "%d bytes of a fragment from %s "
+			    "overlaps the previous fragment\n",
+			    i, ip6_sprintf(&q6->ip6q_src));
+			goto dropfrag;
+		}
+	}
+	if (af6 != (struct ip6asfrag *)q6) {
+		i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
+		if (i > 0) {
+			log(LOG_ERR, "%d bytes of a fragment from %s "
+			    "overlaps the succeeding fragment",
+			    i, ip6_sprintf(&q6->ip6q_src));
+			goto dropfrag;
+		}
+	}
+#endif
+
+insert:
+
+	/*
+	 * Stick new segment in its place;
+	 * check for complete reassembly.
+	 * Move to front of packet queue, as we are
+	 * the most recently active fragmented packet.
+	 */
+	frag6_enq(ip6af, af6->ip6af_up);
+#if 0 /* xxx */
+	if (q6 != ip6q.ip6q_next) {
+		frag6_remque(q6);
+		frag6_insque(q6, &ip6q);
+	}
+#endif
+	next = 0;
+	for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
+	     af6 = af6->ip6af_down) {
+		if (af6->ip6af_off != next) {
+			frag6_doing_reass = 0;
+			return IPPROTO_DONE;
+		}
+		next += af6->ip6af_frglen;
+	}
+	if (af6->ip6af_up->ip6af_mff) {
+		frag6_doing_reass = 0;
+		return IPPROTO_DONE;
+	}
+
+	/*
+	 * Reassembly is complete; concatenate fragments.
+	 */
+
+	ip6af = q6->ip6q_down;
+	t = m = IP6_REASS_MBUF(ip6af);
+	af6 = ip6af->ip6af_down;
+	while (af6 != (struct ip6asfrag *)q6) {
+		while (t->m_next)
+			t = t->m_next;
+		t->m_next = IP6_REASS_MBUF(af6);
+		af6 = af6->ip6af_down;
+	}
+
+	/* adjust offset to point where the original next header starts */
+	offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
+	ip6 = (struct ip6_hdr *)ip6af;
+	ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
+	ip6->ip6_src = q6->ip6q_src;
+	ip6->ip6_dst = q6->ip6q_dst;
+	nxt = q6->ip6q_nxt;
+#ifdef notyet
+	*q6->ip6q_nxtp = (u_char)(nxt & 0xff);
+#endif
+
+	/*
+	 * Delete frag6 header with as a few cost as possible.
+	 */
+
+	if (offset < m->m_len)
+		ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
+			offset);
+	else {
+		ovbcopy(mtod(m, caddr_t), (caddr_t)ip6 + offset, m->m_len);
+		m->m_data -= sizeof(struct ip6_frag);
+	}
+	m->m_data -= offset;	
+	m->m_len += offset; 
+
+	/*
+	 * Store NXT to the original.
+	 */
+	{
+		char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
+		*prvnxtp = nxt;
+	}
+
+	frag6_remque(q6);
+	free(q6, M_FTABLE);
+	frag6_nfragpackets--;
+
+	if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
+		int plen = 0;
+		for (t = m; t; t = t->m_next)
+			plen += t->m_len;
+		m->m_pkthdr.len = plen;
+	}
+	
+	ip6stat.ip6s_reassembled++;
+	in6_ifstat_inc(dstifp, ifs6_reass_ok);
+
+	/*
+	 * Tell launch routine the next header
+	 */
+
+	*mp = m;
+	*offp = offset;
+
+	frag6_doing_reass = 0;
+	return nxt;
+
+ dropfrag:
+	in6_ifstat_inc(dstifp, ifs6_reass_fail);
+	ip6stat.ip6s_fragdropped++;
+	m_freem(m);
+	return IPPROTO_DONE;
+}
+
+/*
+ * Free a fragment reassembly header and all
+ * associated datagrams.
+ */
+void
+frag6_freef(q6)
+	struct ip6q *q6;
+{
+	struct ip6asfrag *af6, *down6;
+
+	for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
+	     af6 = down6) {
+		struct mbuf *m = IP6_REASS_MBUF(af6);
+
+		down6 = af6->ip6af_down;
+		frag6_deq(af6);
+
+		/*
+		 * Return ICMP time exceeded error for the 1st fragment.
+		 * Just free other fragments.
+		 */
+		if (af6->ip6af_off == 0) {
+			struct ip6_hdr *ip6;
+
+			/* adjust pointer */
+			m->m_data -= af6->ip6af_offset;
+			m->m_len += af6->ip6af_offset;
+			ip6 = mtod(m, struct ip6_hdr *);
+
+			/* restoure source and destination addresses */
+			ip6->ip6_src = q6->ip6q_src;
+			ip6->ip6_dst = q6->ip6q_dst;
+
+			icmp6_error(m, ICMP6_TIME_EXCEEDED,
+				    ICMP6_TIME_EXCEED_REASSEMBLY, 0);
+		}
+		else
+			m_freem(m);
+	}
+	frag6_remque(q6);
+	free(q6, M_FTABLE);
+	frag6_nfragpackets--;
+}
+
+/*
+ * Put an ip fragment on a reassembly chain.
+ * Like insque, but pointers in middle of structure.
+ */
+void
+frag6_enq(af6, up6)
+	struct ip6asfrag *af6, *up6;
+{
+	af6->ip6af_up = up6;
+	af6->ip6af_down = up6->ip6af_down;
+	up6->ip6af_down->ip6af_up = af6;
+	up6->ip6af_down = af6;
+}
+
+/*
+ * To frag6_enq as remque is to insque.
+ */
+void
+frag6_deq(af6)
+	struct ip6asfrag *af6;
+{
+	af6->ip6af_up->ip6af_down = af6->ip6af_down;
+	af6->ip6af_down->ip6af_up = af6->ip6af_up;
+}
+
+void 
+frag6_insque(new, old)
+	struct ip6q *new, *old;
+{
+	new->ip6q_prev = old;
+	new->ip6q_next = old->ip6q_next;
+	old->ip6q_next->ip6q_prev= new;
+	old->ip6q_next = new;
+}
+
+void
+frag6_remque(p6)
+	struct ip6q *p6;
+{
+	p6->ip6q_prev->ip6q_next = p6->ip6q_next;
+	p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
+}
+
+/*
+ * IP timer processing;
+ * if a timer expires on a reassembly
+ * queue, discard it.
+ */
+void
+frag6_slowtimo()
+{
+	struct ip6q *q6;
+#ifdef __NetBSD__
+	int s = splsoftnet();
+#else
+	int s = splnet();
+#endif
+#if 0
+	extern struct	route_in6 ip6_forward_rt;
+#endif
+
+	frag6_doing_reass = 1;
+	q6 = ip6q.ip6q_next;
+	if (q6)
+		while (q6 != &ip6q) {
+			--q6->ip6q_ttl;
+			q6 = q6->ip6q_next;
+			if (q6->ip6q_prev->ip6q_ttl == 0) {
+				ip6stat.ip6s_fragtimeout++;
+				/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
+				frag6_freef(q6->ip6q_prev);
+			}
+		}
+	/*
+	 * If we are over the maximum number of fragments
+	 * (due to the limit being lowered), drain off
+	 * enough to get down to the new limit.
+	 */
+	while (frag6_nfragpackets > (u_int)ip6_maxfragpackets) {
+		ip6stat.ip6s_fragoverflow++;
+		/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
+		frag6_freef(ip6q.ip6q_prev);
+	}
+	frag6_doing_reass = 0;
+
+#if 0
+	/*
+	 * Routing changes might produce a better route than we last used;
+	 * make sure we notice eventually, even if forwarding only for one
+	 * destination and the cache is never replaced.
+	 */
+	if (ip6_forward_rt.ro_rt) {
+		RTFREE(ip6_forward_rt.ro_rt);
+		ip6_forward_rt.ro_rt = 0;
+	}
+	if (ipsrcchk_rt.ro_rt) {
+		RTFREE(ipsrcchk_rt.ro_rt);
+		ipsrcchk_rt.ro_rt = 0;
+	}
+#endif
+
+	splx(s);
+}
+
+/*
+ * Drain off all datagram fragments.
+ */
+void
+frag6_drain()
+{
+	if (frag6_doing_reass)
+		return;
+	while (ip6q.ip6q_next != &ip6q) {
+		ip6stat.ip6s_fragdropped++;
+		/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
+		frag6_freef(ip6q.ip6q_next);
+	}
+}