xref: /illumos-gate/usr/src/cmd/cmd-inet/usr.sbin/in.routed/radix.c (revision 7c478bd9)

/*
 * Copyright 2001-2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 1988, 1989, 1993
 *	The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgment:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 *
 *	@(#)radix.c	8.4 (Berkeley) 11/2/94
 *
 * $FreeBSD: src/sbin/routed/radix.c,v 1.6 2000/08/11 08:24:38 sheldonh Exp $
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * Routines to build and maintain radix trees for routing lookups.
 */

#include "defs.h"

static const size_t max_keylen = sizeof (struct sockaddr_in);
static struct radix_mask *rn_mkfreelist;
static struct radix_node_head *mask_rnhead;
static uint8_t *rn_zeros, *rn_ones, *addmask_key;

#define	rn_masktop (mask_rnhead->rnh_treetop)

static boolean_t rn_satisfies_leaf(uint8_t *, struct radix_node *, int);

static boolean_t rn_refines(void *, void *);

static struct radix_node
	 *rn_addmask(void *, uint_t, uint_t),
	 *rn_addroute(void *, void *, struct radix_node_head *,
	    struct radix_node [2]),
	 *rn_delete(void *, void *, struct radix_node_head *),
	 *rn_insert(void *, struct radix_node_head *, boolean_t *,
	    struct radix_node [2]),
	 *rn_match(void *, struct radix_node_head *),
	 *rn_newpair(void *, uint_t, struct radix_node[2]),
	 *rn_search(void *, struct radix_node *),
	 *rn_search_m(void *, struct radix_node *, void *);

static struct radix_node *rn_lookup(void *, void *, struct radix_node_head *);

#ifdef DEBUG
#define	DBGMSG(x)	msglog x
#else
#define	DBGMSG(x)	(void) 0
#endif

/*
 * The data structure for the keys is a radix tree with one way
 * branching removed.  The index rn_b at an internal node n represents a bit
 * position to be tested.  The tree is arranged so that all descendants
 * of a node n have keys whose bits all agree up to position rn_b - 1.
 * (We say the index of n is rn_b.)
 *
 * There is at least one descendant which has a one bit at position rn_b,
 * and at least one with a zero there.
 *
 * A route is determined by a pair of key and mask.  We require that the
 * bit-wise logical and of the key and mask to be the key.
 * We define the index of a route to associated with the mask to be
 * the first bit number in the mask where 0 occurs (with bit number 0
 * representing the highest order bit).
 *
 * We say a mask is normal if every bit is 0, past the index of the mask.
 * If a node n has a descendant (k, m) with index(m) == index(n) == rn_b,
 * and m is a normal mask, then the route applies to every descendant of n.
 * If the index(m) < rn_b, this implies the trailing last few bits of k
 * before bit b are all 0, (and hence consequently true of every descendant
 * of n), so the route applies to all descendants of the node as well.
 *
 * Similar logic shows that a non-normal mask m such that
 * index(m) <= index(n) could potentially apply to many children of n.
 * Thus, for each non-host route, we attach its mask to a list at an internal
 * node as high in the tree as we can go.
 *
 * The present version of the code makes use of normal routes in short-
 * circuiting an explict mask and compare operation when testing whether
 * a key satisfies a normal route, and also in remembering the unique leaf
 * that governs a subtree.
 */

static struct radix_node *
rn_search(void *v_arg, struct radix_node *head)
{
	struct radix_node *x;
	uint8_t *v;

	for (x = head, v = v_arg; x->rn_b >= 0; ) {
		if (x->rn_bmask & v[x->rn_off])
			x = x->rn_r;
		else
			x = x->rn_l;
	}
	return (x);
}

static struct radix_node *
rn_search_m(void *v_arg, struct radix_node *head, void *m_arg)
{
	struct radix_node *x;
	uint8_t *v = v_arg, *m = m_arg;

	for (x = head; x->rn_b >= 0; ) {
		if (x->rn_bmask & m[x->rn_off] & v[x->rn_off])
			x = x->rn_r;
		else
			x = x->rn_l;
	}
	return (x);
}

/*
 * Returns true if there are no bits set in n_arg that are zero in
 * m_arg and the masks aren't equal.  In other words, it returns true
 * when m_arg is a finer-granularity netmask -- it represents a subset
 * of the destinations implied by n_arg.
 */
static boolean_t
rn_refines(void* m_arg, void *n_arg)
{
	uint8_t *m = m_arg, *n = n_arg;
	uint8_t *lim;
	boolean_t masks_are_equal = _B_TRUE;

	lim = n + sizeof (struct sockaddr);

	while (n < lim) {
		if (*n & ~(*m))
			return (_B_FALSE);
		if (*n++ != *m++)
			masks_are_equal = _B_FALSE;
	}
	return (!masks_are_equal);
}

static struct radix_node *
rn_lookup(void *v_arg, void *m_arg, struct radix_node_head *head)
{
	struct radix_node *x;
	uint8_t *netmask = NULL;

	if (m_arg) {
		if ((x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_off)) ==
		    NULL) {
			DBGMSG(("rn_lookup: failed to add mask"));
			return (NULL);
		}
		netmask = x->rn_key;
	}
	x = rn_match(v_arg, head);
	if (x && netmask) {
		while (x && x->rn_mask != netmask)
			x = x->rn_dupedkey;
	}
	return (x);
}

/*
 * Returns true if address 'trial' has no bits differing from the
 * leaf's key when compared under the leaf's mask.  In other words,
 * returns true when 'trial' matches leaf.
 */
static boolean_t
rn_satisfies_leaf(uint8_t *trial,
    struct radix_node *leaf,
    int skip)
{
	uint8_t *cp = trial, *cp2 = leaf->rn_key, *cp3 = leaf->rn_mask;
	uint8_t *cplim;
	size_t length;

	length = sizeof (struct sockaddr);

	if (cp3 == NULL)
		cp3 = rn_ones;
	cplim = cp + length;
	cp3 += skip;
	cp2 += skip;
	for (cp += skip; cp < cplim; cp++, cp2++, cp3++)
		if ((*cp ^ *cp2) & *cp3)
			return (_B_FALSE);
	return (_B_TRUE);
}

static struct radix_node *
rn_match(void *v_arg, struct radix_node_head *head)
{
	uint8_t *v = v_arg;
	struct radix_node *t = head->rnh_treetop, *x;
	uint8_t *cp = v, *cp2;
	uint8_t *cplim;
	struct radix_node *saved_t, *top = t;
	uint_t off = t->rn_off, vlen, matched_off;
	int test, b, rn_b;

	vlen = sizeof (struct sockaddr);

	/*
	 * Open code rn_search(v, top) to avoid overhead of extra
	 * subroutine call.
	 */
	for (; t->rn_b >= 0; ) {
		if (t->rn_bmask & cp[t->rn_off])
			t = t->rn_r;
		else
			t = t->rn_l;
	}

	cp += off;
	cp2 = t->rn_key + off;
	cplim = v + vlen;
	for (; cp < cplim; cp++, cp2++)
		if (*cp != *cp2)
			goto found_difference_with_key;
	/*
	 * This extra grot is in case we are explicitly asked
	 * to look up the default.  Ugh!
	 * Or 255.255.255.255
	 *
	 * In this case, we have a complete match of the key.  Unless
	 * the node is one of the roots, we are finished.
	 * If it is the zeros root, then take what we have, prefering
	 * any real data.
	 * If it is the ones root, then pretend the target key was followed
	 * by a byte of zeros.
	 */
	if (!(t->rn_flags & RNF_ROOT))
		return (t);		/* not a root */
	if (t->rn_dupedkey) {
		t = t->rn_dupedkey;
		return (t);		/* have some real data */
	}
	if (*(cp-1) == 0)
		return (t);		/* not the ones root */
	b = 0;				/* fake a zero after 255.255.255.255 */
	goto calculated_differing_bit;
found_difference_with_key:
	test = (*cp ^ *cp2) & 0xff; /* find first bit that differs */
	for (b = 7; (test >>= 1) > 0; )
		b--;
calculated_differing_bit:
	matched_off = cp - v;
	b += matched_off << 3;
	rn_b = -1 - b;
	/*
	 * If there is a host route in a duped-key chain, it will be first.
	 */
	if ((saved_t = t)->rn_mask == NULL)
		t = t->rn_dupedkey;
	for (; t; t = t->rn_dupedkey) {
		/*
		 * Even if we don't match exactly as a host,
		 * we may match if the leaf we wound up at is
		 * a route to a net.
		 */
		if (t->rn_flags & RNF_NORMAL) {
			if (rn_b <= t->rn_b)
				return (t);
		} else if (rn_satisfies_leaf(v, t, matched_off)) {
			return (t);
		}
	}
	t = saved_t;
	/* start searching up the tree */
	do {
		struct radix_mask *m;
		t = t->rn_p;
		if ((m = t->rn_mklist) != NULL) {
			/*
			 * If non-contiguous masks ever become important
			 * we can restore the masking and open coding of
			 * the search and satisfaction test and put the
			 * calculation of "off" back before the "do".
			 */
			do {
				if (m->rm_flags & RNF_NORMAL) {
					if (rn_b <= m->rm_b)
						return (m->rm_leaf);
				} else {
					off = MIN(t->rn_off, matched_off);
					x = rn_search_m(v, t, m->rm_mask);
					while (x != NULL &&
					    x->rn_mask != m->rm_mask)
						x = x->rn_dupedkey;
					if (x != NULL &&
					    rn_satisfies_leaf(v, x, off))
						return (x);
				}
			} while ((m = m->rm_mklist) != NULL);
		}
	} while (t != top);
	return (NULL);
}

#ifdef RN_DEBUG
int	rn_nodenum;
struct	radix_node *rn_clist;
int	rn_saveinfo;
boolean_t	rn_debug =  1;
#endif

static struct radix_node *
rn_newpair(void *v, uint_t b, struct radix_node nodes[2])
{
	struct radix_node *tt = nodes, *t = tt + 1;

	t->rn_b = b;
	t->rn_bmask = 0x80 >> (b & 7);
	t->rn_l = tt;
	t->rn_off = b >> 3;
	tt->rn_b = -1;
	tt->rn_key = v;
	tt->rn_p = t;
	tt->rn_flags = t->rn_flags = RNF_ACTIVE;
#ifdef RN_DEBUG
	tt->rn_info = rn_nodenum++;
	t->rn_info = rn_nodenum++;
	tt->rn_twin = t;
	tt->rn_ybro = rn_clist;
	rn_clist = tt;
#endif
	return (t);
}

static struct radix_node *
rn_insert(void* v_arg, struct radix_node_head *head, boolean_t *dupentry,
    struct radix_node nodes[2])
{
	uint8_t *v = v_arg;
	struct radix_node *top = head->rnh_treetop;
	uint_t head_off = top->rn_off, vlen;
	struct radix_node *t = rn_search(v_arg, top);
	uint8_t *cp = v + head_off, b;
	struct radix_node *tt;

	vlen = sizeof (struct sockaddr);

	/*
	 * Find first bit at which v and t->rn_key differ
	 */
	{
		uint8_t *cp2 = t->rn_key + head_off;
		uint8_t cmp_res;
		uint8_t *cplim = v + vlen;

		while (cp < cplim)
			if (*cp2++ != *cp++)
				goto found_differing_byte;
		/* handle adding 255.255.255.255 */
		if (!(t->rn_flags & RNF_ROOT) || *(cp2-1) == 0) {
			*dupentry = _B_TRUE;
			return (t);
		}
found_differing_byte:
		*dupentry = _B_FALSE;
		cmp_res = cp[-1] ^ cp2[-1];
		for (b = (cp - v) << 3; cmp_res != 0; b--)
			cmp_res >>= 1;
	}
	{
		struct radix_node *p, *x = top;
		cp = v;
		do {
			p = x;
			if (cp[x->rn_off] & x->rn_bmask)
				x = x->rn_r;
			else
				x = x->rn_l;
		} while (b > (unsigned)x->rn_b);
#ifdef RN_DEBUG
		if (rn_debug) {
			msglog("rn_insert: Going In:");
			traverse(p);
		}
#endif
		t = rn_newpair(v_arg, b, nodes);
		tt = t->rn_l;
		if (!(cp[p->rn_off] & p->rn_bmask))
			p->rn_l = t;
		else
			p->rn_r = t;
		x->rn_p = t; /* frees x, p as temp vars below */
		t->rn_p = p;
		if (!(cp[t->rn_off] & t->rn_bmask)) {
			t->rn_r = x;
		} else {
			t->rn_r = tt;
			t->rn_l = x;
		}
#ifdef RN_DEBUG
		if (rn_debug) {
			msglog("rn_insert: Coming Out:");
			traverse(p);
		}
#endif
	}
	return (tt);
}

static struct radix_node *
rn_addmask(void *n_arg, uint_t search, uint_t skip)
{
	uint8_t *netmask = n_arg;
	struct radix_node *x;
	uint8_t *cp, *cplim;
	int b = 0, mlen, j, m0;
	boolean_t maskduplicated;
	struct radix_node *saved_x;
	static int last_zeroed = 0;

	mlen = sizeof (struct sockaddr);
	if (skip == 0)
		skip = 1;
	if (mlen <= skip)
		return (mask_rnhead->rnh_nodes);
	if (skip > 1)
		(void) memmove(addmask_key + 1, rn_ones + 1, skip - 1);
	if ((m0 = mlen) > skip)
		(void) memmove(addmask_key + skip, netmask + skip, mlen - skip);
	/*
	 * Trim trailing zeroes.
	 */
	for (cp = addmask_key + mlen; (cp > addmask_key) && cp[-1] == 0; )
		cp--;
	mlen = cp - addmask_key;
	if (mlen <= skip) {
		if (m0 >= last_zeroed)
			last_zeroed = mlen;
		return (mask_rnhead->rnh_nodes);
	}
	if (m0 < last_zeroed)
		(void) memset(addmask_key + m0, 0, last_zeroed - m0);
	*addmask_key = last_zeroed = mlen;
	x = rn_search(addmask_key, rn_masktop);
	if (memcmp(addmask_key, x->rn_key, mlen) != 0)
		x = NULL;
	if (x != NULL || search != 0)
		return (x);
	x = rtmalloc(max_keylen + 2*sizeof (*x), "rn_addmask");
	saved_x = x;
	(void) memset(x, 0, max_keylen + 2 * sizeof (*x));
	netmask = cp = (uint8_t *)(x + 2);
	(void) memmove(cp, addmask_key, mlen);
	x = rn_insert(cp, mask_rnhead, &maskduplicated, x);
	if (maskduplicated) {
#ifdef DEBUG
		logbad(1, "rn_addmask: mask impossibly already in tree");
#else
		msglog("rn_addmask: mask impossibly already in tree");
#endif
		free(saved_x);
		return (x);
	}
	/*
	 * Calculate index of mask, and check for normalcy.
	 */
	cplim = netmask + mlen;
	x->rn_flags |= RNF_NORMAL;
	for (cp = netmask + skip; (cp < cplim) && *cp == 0xff; )
		cp++;
	if (cp != cplim) {
		for (j = 0x80; (j & *cp) != 0; j >>= 1)
			b++;
		if (*cp != (0xFF & ~(0xFF >> b)) || cp != (cplim - 1))
			x->rn_flags &= ~RNF_NORMAL;
	}
	b += (cp - netmask) << 3;
	x->rn_b = -1 - b;
	return (x);
}

static boolean_t /* Note: arbitrary ordering for non-contiguous masks */
rn_lexobetter(void *m_arg, void *n_arg)
{
	uint8_t *mp = m_arg, *np = n_arg, *lim;

	lim = mp + sizeof (struct sockaddr);
	while (mp < lim)
		if (*mp++ > *np++)
			return (_B_TRUE);
	return (_B_FALSE);
}

static struct radix_mask *
rn_new_radix_mask(struct radix_node *tt,
    struct radix_mask *next)
{
	struct radix_mask *m;

	MKGet(m);
	if (m == NULL) {
#ifdef DEBUG
		logbad(1, "Mask for route not entered");
#else
		msglog("Mask for route not entered");
#endif
		return (NULL);
	}
	(void) memset(m, 0, sizeof (*m));
	m->rm_b = tt->rn_b;
	m->rm_flags = tt->rn_flags;
	if (tt->rn_flags & RNF_NORMAL)
		m->rm_leaf = tt;
	else
		m->rm_mask = tt->rn_mask;
	m->rm_mklist = next;
	tt->rn_mklist = m;
	return (m);
}

static struct radix_node *
rn_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
    struct radix_node treenodes[2])
{
	uint8_t *v = v_arg, *netmask = n_arg;
	struct radix_node *t, *x = 0, *tt;
	struct radix_node *saved_tt, *top = head->rnh_treetop;
	short b = 0, b_leaf = 0;
	boolean_t keyduplicated;
	uint8_t *mmask;
	struct radix_mask *m, **mp;

	/*
	 * In dealing with non-contiguous masks, there may be
	 * many different routes which have the same mask.
	 * We will find it useful to have a unique pointer to
	 * the mask to speed avoiding duplicate references at
	 * nodes and possibly save time in calculating indices.
	 */
	if (netmask)  {
		if ((x = rn_addmask(netmask, 0, top->rn_off)) == NULL) {
			DBGMSG(("rn_addroute: addmask failed"));
			return (NULL);
		}
		b_leaf = x->rn_b;
		b = -1 - x->rn_b;
		netmask = x->rn_key;
	}
	/*
	 * Deal with duplicated keys: attach node to previous instance
	 */
	saved_tt = tt = rn_insert(v, head, &keyduplicated, treenodes);
	if (keyduplicated) {
		for (t = tt; tt; t = tt, tt = tt->rn_dupedkey) {
			if (tt->rn_mask == netmask) {
				DBGMSG(("rn_addroute: duplicated route and "
				    "mask"));
				return (NULL);
			}
			if (netmask == NULL ||
			    (tt->rn_mask &&
				((b_leaf < tt->rn_b) ||
				    rn_refines(netmask, tt->rn_mask) ||
				    rn_lexobetter(netmask, tt->rn_mask))))
				break;
		}
		/*
		 * If the mask is not duplicated, we wouldn't
		 * find it among possible duplicate key entries
		 * anyway, so the above test doesn't hurt.
		 *
		 * We sort the masks for a duplicated key the same way as
		 * in a masklist -- most specific to least specific.
		 * This may require the unfortunate nuisance of relocating
		 * the head of the list.
		 */
		if (tt == saved_tt) {
			struct	radix_node *xx = x;
			/* link in at head of list */
			(tt = treenodes)->rn_dupedkey = t;
			tt->rn_flags = t->rn_flags;
			tt->rn_p = x = t->rn_p;
			if (x->rn_l == t)
				x->rn_l = tt;
			else
				x->rn_r = tt;
			saved_tt = tt;
			x = xx;
		} else {
			(tt = treenodes)->rn_dupedkey = t->rn_dupedkey;
			t->rn_dupedkey = tt;
		}
#ifdef RN_DEBUG
		t = tt + 1;
		tt->rn_info = rn_nodenum++;
		t->rn_info = rn_nodenum++;
		tt->rn_twin = t;
		tt->rn_ybro = rn_clist;
		rn_clist = tt;
#endif
		tt->rn_key = v;
		tt->rn_b = -1;
		tt->rn_flags = RNF_ACTIVE;
	}
	/*
	 * Put mask in tree.
	 */
	if (netmask) {
		tt->rn_mask = netmask;
		tt->rn_b = x->rn_b;
		tt->rn_flags |= x->rn_flags & RNF_NORMAL;
	}
	t = saved_tt->rn_p;
	if (keyduplicated)
		goto key_already_in_tree;
	b_leaf = -1 - t->rn_b;
	if (t->rn_r == saved_tt)
		x = t->rn_l;
	else
		x = t->rn_r;
	/* Promote general routes from below */
	if (x->rn_b < 0) {
		for (mp = &t->rn_mklist; x; x = x->rn_dupedkey)
			if (x->rn_mask != NULL && (x->rn_b >= b_leaf) &&
			    x->rn_mklist == NULL) {
				if ((*mp = m = rn_new_radix_mask(x, 0)) != NULL)
					mp = &m->rm_mklist;
			}
	} else if (x->rn_mklist) {
		/*
		 * Skip over masks whose index is > that of new node
		 */
		for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist)
			if (m->rm_b >= b_leaf)
				break;
		t->rn_mklist = m;
		*mp = 0;
	}
key_already_in_tree:
	/* Add new route to highest possible ancestor's list */
	if ((netmask == NULL) || (b > t->rn_b)) {
		return (tt); /* can't lift at all */
	}
	b_leaf = tt->rn_b;
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != top);
	/*
	 * Search through routes associated with node to
	 * insert new route according to index.
	 * Need same criteria as when sorting dupedkeys to avoid
	 * double loop on deletion.
	 */
	for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist) {
		if (m->rm_b < b_leaf)
			continue;
		if (m->rm_b > b_leaf)
			break;
		if (m->rm_flags & RNF_NORMAL) {
			mmask = m->rm_leaf->rn_mask;
			if (tt->rn_flags & RNF_NORMAL) {
#ifdef DEBUG
				logbad(1, "Non-unique normal route, mask "
				    "not entered");
#else
				msglog("Non-unique normal route, mask "
				    "not entered");
#endif
				return (tt);
			}
		} else
			mmask = m->rm_mask;
		if (mmask == netmask) {
			m->rm_refs++;
			tt->rn_mklist = m;
			return (tt);
		}
		if (rn_refines(netmask, mmask) || rn_lexobetter(netmask, mmask))
			break;
	}
	*mp = rn_new_radix_mask(tt, *mp);
	return (tt);
}

static struct radix_node *
rn_delete(void *v_arg, void *netmask_arg, struct radix_node_head *head)
{
	struct radix_node *t, *p, *x, *tt;
	struct radix_mask *m, *saved_m, **mp;
	struct radix_node *dupedkey, *saved_tt, *top;
	uint8_t *v, *netmask;
	int b;
	uint_t head_off, vlen;

	v = v_arg;
	netmask = netmask_arg;
	x = head->rnh_treetop;
	tt = rn_search(v, x);
	head_off = x->rn_off;
	vlen = sizeof (struct sockaddr);
	saved_tt = tt;
	top = x;
	if (tt == NULL ||
	    memcmp(v + head_off, tt->rn_key + head_off, vlen - head_off) != 0) {
		DBGMSG(("rn_delete: unable to locate route to delete"));
		return (NULL);
	}
	/*
	 * Delete our route from mask lists.
	 */
	if (netmask) {
		if ((x = rn_addmask(netmask, 1, head_off)) == NULL) {
			DBGMSG(("rn_delete: cannot add mask"));
			return (NULL);
		}
		netmask = x->rn_key;
		while (tt->rn_mask != netmask)
			if ((tt = tt->rn_dupedkey) == NULL) {
				DBGMSG(("rn_delete: cannot locate mask"));
				return (NULL);
			}
	}
	if (tt->rn_mask == NULL || (saved_m = m = tt->rn_mklist) == NULL)
		goto annotation_removed;
	if (tt->rn_flags & RNF_NORMAL) {
		if (m->rm_leaf != tt || m->rm_refs > 0) {
#ifdef DEBUG
			logbad(1, "rn_delete: inconsistent annotation");
#else
			msglog("rn_delete: inconsistent annotation");
#endif
			return (NULL);  /* dangling ref could cause disaster */
		}
	} else {
		if (m->rm_mask != tt->rn_mask) {
#ifdef DEBUG
			logbad(1, "rn_delete: inconsistent annotation");
#else
			msglog("rn_delete: inconsistent annotation");
#endif
			goto annotation_removed;
		}
		if (--m->rm_refs >= 0)
			goto annotation_removed;
	}
	b = -1 - tt->rn_b;
	t = saved_tt->rn_p;
	if (b > t->rn_b)
		goto annotation_removed; /* Wasn't lifted at all */
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != top);
	for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist)
		if (m == saved_m) {
			*mp = m->rm_mklist;
			MKFree(m);
			break;
		}
	if (m == NULL) {
#ifdef DEBUG
		logbad(1, "rn_delete: couldn't find our annotation");
#else
		msglog("rn_delete: couldn't find our annotation");
#endif
		if (tt->rn_flags & RNF_NORMAL)
			return (NULL); /* Dangling ref to us */
	}
annotation_removed:
	/*
	 * Eliminate us from tree
	 */
	if (tt->rn_flags & RNF_ROOT) {
		DBGMSG(("rn_delete: cannot delete root"));
		return (NULL);
	}
#ifdef RN_DEBUG
	/* Get us out of the creation list */
	for (t = rn_clist; t && t->rn_ybro != tt; t = t->rn_ybro) {}
	if (t != NULL)
		t->rn_ybro = tt->rn_ybro;
#endif
	t = tt->rn_p;
	if ((dupedkey = saved_tt->rn_dupedkey) != NULL) {
		if (tt == saved_tt) {
			x = dupedkey;
			x->rn_p = t;
			if (t->rn_l == tt)
				t->rn_l = x;
			else
				t->rn_r = x;
		} else {
			for (x = p = saved_tt; p && p->rn_dupedkey != tt; )
				p = p->rn_dupedkey;
			if (p != NULL) {
				p->rn_dupedkey = tt->rn_dupedkey;
			} else {
#ifdef DEBUG
				logbad(1, "rn_delete: couldn't find us");
#else
				msglog("rn_delete: couldn't find us");
#endif
			}
		}
		t = tt + 1;
		if (t->rn_flags & RNF_ACTIVE) {
#ifndef RN_DEBUG
			*++x = *t;
			p = t->rn_p;
#else
			b = t->rn_info;
			*++x = *t;
			t->rn_info = b;
			p = t->rn_p;
#endif
			if (p->rn_l == t)
				p->rn_l = x;
			else
				p->rn_r = x;
			x->rn_l->rn_p = x;
			x->rn_r->rn_p = x;
		}
		goto out;
	}
	if (t->rn_l == tt)
		x = t->rn_r;
	else
		x = t->rn_l;
	p = t->rn_p;
	if (p->rn_r == t)
		p->rn_r = x;
	else
		p->rn_l = x;
	x->rn_p = p;
	/*
	 * Demote routes attached to us.
	 */
	if (t->rn_mklist) {
		if (x->rn_b >= 0) {
			for (mp = &x->rn_mklist; (m = *mp) != NULL; )
				mp = &m->rm_mklist;
			*mp = t->rn_mklist;
		} else {
			/*
			 * If there are any key,mask pairs in a sibling
			 * duped-key chain, some subset will appear sorted
			 * in the same order attached to our mklist
			 */
			for (m = t->rn_mklist; m && x; x = x->rn_dupedkey)
				if (m == x->rn_mklist) {
					struct radix_mask *mm = m->rm_mklist;
					x->rn_mklist = 0;
					if (--(m->rm_refs) < 0)
						MKFree(m);
					m = mm;
				}
			if (m != NULL) {
#ifdef DEBUG
				logbad(1, "rn_delete: Orphaned Mask %p at %p\n",
				    m, x);
#else
				msglog("rn_delete: Orphaned Mask %p at %p\n", m,
				    x);
#endif
			}
		}
	}
	/*
	 * We may be holding an active internal node in the tree.
	 */
	x = tt + 1;
	if (t != x) {
#ifndef RN_DEBUG
		*t = *x;
#else
		b = t->rn_info;
		*t = *x;
		t->rn_info = b;
#endif
		t->rn_l->rn_p = t;
		t->rn_r->rn_p = t;
		p = x->rn_p;
		if (p->rn_l == x)
			p->rn_l = t;
		else
			p->rn_r = t;
	}
out:
	tt->rn_flags &= ~RNF_ACTIVE;
	tt[1].rn_flags &= ~RNF_ACTIVE;
	return (tt);
}

int
rn_walktree(struct radix_node_head *h,
    int (*f)(struct radix_node *, void *),
    void *w)
{
	int error;
	struct radix_node *base, *next;
	struct radix_node *rn = h->rnh_treetop;
	/*
	 * This gets complicated because we may delete the node
	 * while applying the function f to it, so we need to calculate
	 * the successor node in advance.
	 */
	/* First time through node, go left */
	while (rn->rn_b >= 0)
		rn = rn->rn_l;
	do {
		base = rn;
		/* If at right child go back up, otherwise, go right */
		while (rn->rn_p->rn_r == rn && !(rn->rn_flags & RNF_ROOT))
			rn = rn->rn_p;
		/* Find the next *leaf* since next node might vanish, too */
		for (rn = rn->rn_p->rn_r; rn->rn_b >= 0; )
			rn = rn->rn_l;
		next = rn;
		/* Process leaves */
		while ((rn = base) != NULL) {
			base = rn->rn_dupedkey;
			if (!(rn->rn_flags & RNF_ROOT) && (error = (*f)(rn, w)))
				return (error);
		}
		rn = next;
	} while (!(rn->rn_flags & RNF_ROOT));
	return (0);
}

int
rn_inithead(void **head, uint_t off)
{
	struct radix_node_head *rnh;
	struct radix_node *t, *tt, *ttt;
	if (*head)
		return (1);
	rnh = rtmalloc(sizeof (*rnh), "rn_inithead");
	(void) memset(rnh, 0, sizeof (*rnh));
	*head = rnh;
	t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
	ttt = rnh->rnh_nodes + 2;
	t->rn_r = ttt;
	t->rn_p = t;
	tt = t->rn_l;
	tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
	tt->rn_b = -1 - off;
	*ttt = *tt;
	ttt->rn_key = rn_ones;
	rnh->rnh_addaddr = rn_addroute;
	rnh->rnh_deladdr = rn_delete;
	rnh->rnh_matchaddr = rn_match;
	rnh->rnh_lookup = rn_lookup;
	rnh->rnh_walktree = rn_walktree;
	rnh->rnh_treetop = t;
	return (1);
}

void
rn_init(void)
{
	uint8_t *cp, *cplim;

	if (max_keylen == 0) {
		logbad(1, "radix functions require max_keylen be set");
		return;
	}
	rn_zeros = rtmalloc(3 * max_keylen, "rn_init");
	(void) memset(rn_zeros, 0, 3 * max_keylen);
	rn_ones = cp = rn_zeros + max_keylen;
	addmask_key = cplim = rn_ones + max_keylen;
	while (cp < cplim)
		*cp++ = 0xFF;
	if (rn_inithead((void **)&mask_rnhead, 0) == 0) {
		logbad(0, "rn_init: could not initialize radix tree");
	}
}