usr.sbin/in.routed/radix.c

	radix.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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");
    }
}