net/patricia/radix.c

	radix.c revision f4b3ec61df05330d25f55a36b975b4d7519fdeb1
/*
 * Copyright 2007 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.
 * 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 8.5 (Berkeley) 5/19/95
 * $FreeBSD: /repoman/r/ncvs/src/sys/net/radix.c,v 1.36.2.1 2005/01/31 23:26:23
 * imp Exp $
 */

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

/*
 * Routines to build and maintain radix trees for routing lookups.
 */
#include <sys/types.h>

#ifndef _RADIX_H_
#include <sys/param.h>
#ifdef  _KERNEL
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/systm.h>
#include <sys/cmn_err.h>
#else
#include <assert.h>
#define ASSERT assert
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <strings.h>
#endif  /* _KERNEL */
#include <net/radix.h>
#endif

#ifndef _KERNEL
void
panic(const char *str)
{
    fprintf(stderr, "Panic - %s\n", str);
    abort();
}
#endif  /* _KERNEL */

static int  rn_walktree(struct radix_node_head *, walktree_f_t *, void *);
static int  rn_walktree_mt(struct radix_node_head *, walktree_f_t *,
    void *, lockf_t, lockf_t);
static struct radix_node
    *rn_insert(void *, struct radix_node_head *, int *,
        struct radix_node [2]),
    *rn_newpair(void *, int, struct radix_node[2]),
    *rn_search(void *, struct radix_node *),
    *rn_search_m(void *, struct radix_node *, void *),
    *rn_lookup(void *, void *, struct radix_node_head *),
    *rn_match(void *, struct radix_node_head *),
    *rn_match_args(void *, struct radix_node_head *, match_leaf_t *,
        void *),
    *rn_addmask(void *, int, int),
    *rn_addroute(void *, void *, struct radix_node_head *,
        struct radix_node [2]),
    *rn_delete(void *, void *, struct radix_node_head *);
static  boolean_t rn_refines(void *, void *);

#define MAX_KEYLEN  16
static int  max_keylen = MAX_KEYLEN;

#ifdef  _KERNEL
static struct kmem_cache *radix_mask_cache; /* for rn_mkfreelist */
static struct kmem_cache *radix_node_cache;
#else
static char *radix_mask_cache, *radix_node_cache; /* dummy vars. never inited */
#endif  /* _KERNEL */

static struct radix_mask *rn_mkfreelist;
static struct radix_node_head *mask_rnhead;
/*
 * Work area -- the following point to 2 buffers of size max_keylen,
 * allocated in this order in a block of memory malloc'ed by rn_init.
 * A third buffer of size MAX_KEYLEN is allocated from the stack.
 */
static char *rn_zeros, *rn_ones;

#define MKGet(m)  R_Malloc(m, radix_mask_cache, sizeof (struct radix_mask))
#define MKFree(m) Free(m, radix_mask_cache)
#define rn_masktop (mask_rnhead->rnh_treetop)

static boolean_t    rn_lexobetter(void *m_arg, void *n_arg);
static struct radix_mask *
        rn_new_radix_mask(struct radix_node *tt,
            struct radix_mask *next);
static boolean_t
        rn_satisfies_leaf(char *trial, struct radix_node *leaf,
            int skip, match_leaf_t *rn_leaf_fn, void *rn_leaf_arg);

#define RN_MATCHF(rn, f, arg)   (f == NULL || (*f)((rn), arg))

/*
 * The data structure for the keys is a radix tree with one way
 * branching removed.  The index rn_bit 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_bit - 1.
 * (We say the index of n is rn_bit.)
 *
 * There is at least one descendant which has a one bit at position rn_bit,
 * 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 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_bit,
 * and m is a normal mask, then the route applies to every descendant of n.
 * If the index(m) < rn_bit, 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.
 */

/*
 * Most of the functions in this code assume that the key/mask arguments
 * are sockaddr-like structures, where the first byte is an uchar_t
 * indicating the size of the entire structure.
 *
 * To make the assumption more explicit, we use the LEN() macro to access
 * this field. It is safe to pass an expression with side effects
 * to LEN() as the argument is evaluated only once.
 */
#define LEN(x) (*(const uchar_t *)(x))


/*
 * Search a node in the tree matching the key.
 */
static struct radix_node *
rn_search(v_arg, head)
    void *v_arg;
    struct radix_node *head;
{
    struct radix_node *x;
    caddr_t v;

    for (x = head, v = v_arg; x->rn_bit >= 0; ) {
        if (x->rn_bmask & v[x->rn_offset])
            x = x->rn_right;
        else
            x = x->rn_left;
    }
    return (x);
}

/*
 * Same as above, but with an additional mask.
 */
static struct radix_node *
rn_search_m(v_arg, head, m_arg)
    struct radix_node *head;
    void *v_arg, *m_arg;
{
    struct radix_node *x;
    caddr_t v = v_arg, m = m_arg;

    for (x = head; x->rn_bit >= 0; ) {
        if ((x->rn_bmask & m[x->rn_offset]) &&
            (x->rn_bmask & v[x->rn_offset]))
            x = x->rn_right;
        else
            x = x->rn_left;
    }
    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(m_arg, n_arg)
    void *m_arg, *n_arg;
{
    caddr_t m = m_arg, n = n_arg;
    caddr_t lim = n + LEN(n), lim2 = lim;
    int longer = LEN(n++) - (int)LEN(m++);
    boolean_t masks_are_equal = B_TRUE;

    if (longer > 0)
        lim -= longer;
    while (n < lim) {
        if (*n & ~(*m))
            return (0);
        if (*n++ != *m++)
            masks_are_equal = B_FALSE;
    }
    while (n < lim2)
        if (*n++)
            return (B_FALSE);
    if (masks_are_equal && (longer < 0))
        for (lim2 = m - longer; m < lim2; )
            if (*m++)
                return (B_TRUE);
    return (!masks_are_equal);
}

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

    if (m_arg) {
        x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_offset);
        if (x == NULL)
            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.
 * In addition, if a rn_leaf_fn is passed in, that is used to find
 * a match on conditions defined by the caller of rn_match.  This is
 * used by the kernel ftable to match on IRE_MATCH_* conditions.
 */
static boolean_t
rn_satisfies_leaf(trial, leaf, skip, rn_leaf_fn, rn_leaf_arg)
    caddr_t trial;
    struct radix_node *leaf;
    int skip;
    match_leaf_t *rn_leaf_fn;
    void *rn_leaf_arg;
{
    char *cp = trial, *cp2 = leaf->rn_key, *cp3 = leaf->rn_mask;
    char *cplim;
    int length = min(LEN(cp), LEN(cp2));

    if (cp3 == 0)
        cp3 = rn_ones;
    else
        length = min(length, LEN(cp3));
    cplim = cp + length;
    cp3 += skip;
    cp2 += skip;

    for (cp += skip; cp < cplim; cp++, cp2++, cp3++)
        if ((*cp ^ *cp2) & *cp3)
            return (B_FALSE);

    return (RN_MATCHF(leaf, rn_leaf_fn, rn_leaf_arg));
}

static struct radix_node *
rn_match(v_arg, head)
    void *v_arg;
    struct radix_node_head *head;
{
    return (rn_match_args(v_arg, head, NULL, NULL));
}

static struct radix_node *
rn_match_args(v_arg, head, rn_leaf_fn, rn_leaf_arg)
    void *v_arg;
    struct radix_node_head *head;
    match_leaf_t *rn_leaf_fn;
    void *rn_leaf_arg;
{
    caddr_t v = v_arg;
    struct radix_node *t = head->rnh_treetop, *x;
    caddr_t cp = v, cp2;
    caddr_t cplim;
    struct radix_node *saved_t, *top = t;
    int off = t->rn_offset, vlen = LEN(cp), matched_off;
    int test, b, rn_bit;

    /*
     * Open code rn_search(v, top) to avoid overhead of extra
     * subroutine call.
     */
    for (; t->rn_bit >= 0; ) {
        if (t->rn_bmask & cp[t->rn_offset])
            t = t->rn_right;
        else
            t = t->rn_left;
    }
    /*
     * See if we match exactly as a host destination
     * or at least learn how many bits match, for normal mask finesse.
     *
     * It doesn't hurt us to limit how many bytes to check
     * to the length of the mask, since if it matches we had a genuine
     * match and the leaf we have is the most specific one anyway;
     * if it didn't match with a shorter length it would fail
     * with a long one.  This wins big for class B&C netmasks which
     * are probably the most common case...
     */
    if (t->rn_mask)
        vlen = LEN(t->rn_mask);
    cp += off; cp2 = t->rn_key + off; cplim = v + vlen;
    for (; cp < cplim; cp++, cp2++)
        if (*cp != *cp2)
            goto keydiff;
    /*
     * This extra grot is in case we are explicitly asked
     * to look up the default.  Ugh!
     *
     * Never return the root node itself, it seems to cause a
     * lot of confusion.
     */
    if (t->rn_flags & RNF_ROOT)
        t = t->rn_dupedkey;
    if (t == NULL || RN_MATCHF(t, rn_leaf_fn, rn_leaf_arg)) {
        return (t);
    } else {
        /*
         * Although we found an exact match on the key, rn_leaf_fn
         * is looking for some other criteria as well. Continue
         * looking as if the exact match failed.
         */
        if (t->rn_parent->rn_flags & RNF_ROOT) {
            /* hit the top. have to give up */
            return (NULL);
        }
        b = 0;
        goto keeplooking;

    }
keydiff:
    test = (*cp ^ *cp2) & 0xff; /* find first bit that differs */
    for (b = 7; (test >>= 1) > 0; )
        b--;
keeplooking:
    matched_off = cp - v;
    b += matched_off << 3;
    rn_bit = -1 - b;

    /*
     * If there is a host route in a duped-key chain, it will be first.
     */
    if ((saved_t = t)->rn_mask == 0)
        t = t->rn_dupedkey;
    for (; t != NULL; 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_bit <= t->rn_bit) &&
                RN_MATCHF(t, rn_leaf_fn, rn_leaf_arg)) {
                return (t);
            }
        } else if (rn_satisfies_leaf(v, t, matched_off, rn_leaf_fn,
            rn_leaf_arg)) {
            return (t);
        }
    }
    t = saved_t;
    /* start searching up the tree */
    do {
        struct radix_mask *m;

        t = t->rn_parent;
        m = t->rn_mklist;
        /*
         * 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".
         */
        while (m) {
            if (m->rm_flags & RNF_NORMAL) {
                if ((rn_bit <= m->rm_bit) &&
                    RN_MATCHF(m->rm_leaf, rn_leaf_fn,
                    rn_leaf_arg)) {
                    return (m->rm_leaf);
                }
            } else {
                off = min(t->rn_offset, 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 && rn_satisfies_leaf(v, x, off,
                    rn_leaf_fn, rn_leaf_arg)) {
                    return (x);
                }
            }
            m = m->rm_mklist;
        }
    } while (t != top);
    return (0);
}

/*
 * Whenever we add a new leaf to the tree, we also add a parent node,
 * so we allocate them as an array of two elements: the first one must be
 * the leaf (see RNTORT() in route.c), the second one is the parent.
 * This routine initializes the relevant fields of the nodes, so that
 * the leaf is the left child of the parent node, and both nodes have
 * (almost) all all fields filled as appropriate.
 * The function returns a pointer to the parent node.
 */

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

    t->rn_bit = b;
    t->rn_bmask = 0x80 >> (b & 7);
    t->rn_left = tt;
    t->rn_offset = b >> 3;

    /*
     * t->rn_parent, r->rn_right, tt->rn_mask, tt->rn_dupedkey
     * and tt->rn_bmask must have been zeroed by caller.
     */
    tt->rn_bit = -1;
    tt->rn_key = v;
    tt->rn_parent = t;
    tt->rn_flags = t->rn_flags = RNF_ACTIVE;
    tt->rn_mklist = t->rn_mklist = 0;
    return (t);
}

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

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

        while (cp < cplim)
            if (*cp2++ != *cp++)
                goto on1;
        *dupentry = 1;
        return (t);
on1:
        *dupentry = 0;
        cmp_res = (cp[-1] ^ cp2[-1]) & 0xff;
        for (b = (cp - v) << 3; cmp_res; b--)
            cmp_res >>= 1;
    }
    {
        struct radix_node *p, *x = top;
        cp = v;
        do {
            p = x;
            if (cp[x->rn_offset] & x->rn_bmask)
                x = x->rn_right;
            else
                x = x->rn_left;
        } while (b > (unsigned)x->rn_bit);
                /* x->rn_bit < b && x->rn_bit >= 0 */
        t = rn_newpair(v_arg, b, nodes);
        tt = t->rn_left;
        if ((cp[p->rn_offset] & p->rn_bmask) == 0)
            p->rn_left = t;
        else
            p->rn_right = t;
        x->rn_parent = t;
        t->rn_parent = p;
        if ((cp[t->rn_offset] & t->rn_bmask) == 0) {
            t->rn_right = x;
        } else {
            t->rn_right = tt;
            t->rn_left = x;
        }
    }
    return (tt);
}

static struct radix_node *
rn_addmask(n_arg, search, skip)
    int search, skip;
    void *n_arg;
{
    caddr_t netmask = (caddr_t)n_arg;
    struct radix_node *x;
    caddr_t cp, cplim;
    int b = 0, mlen, j;
    int maskduplicated, m0, isnormal;
    struct radix_node *saved_x;
    int last_zeroed = 0;
    char addmask_key[MAX_KEYLEN];

    if ((mlen = LEN(netmask)) > max_keylen)
        mlen = max_keylen;
    if (skip == 0)
        skip = 1;
    if (mlen <= skip)
        return (mask_rnhead->rnh_nodes);
    if (skip > 1)
        bcopy(rn_ones + 1, addmask_key + 1, skip - 1);
    if ((m0 = mlen) > skip)
        bcopy(netmask + skip, addmask_key + 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)
        bzero(addmask_key + m0, last_zeroed - m0);
    *addmask_key = last_zeroed = mlen;
    x = rn_search(addmask_key, rn_masktop);
    if (bcmp(addmask_key, x->rn_key, mlen) != 0)
        x = 0;
    if (x || search)
        return (x);
    R_Zalloc(x, radix_node_cache, max_keylen + 2 * sizeof (*x));

    if ((saved_x = x) == 0)
        return (0);
    netmask = cp = (caddr_t)(x + 2);
    bcopy(addmask_key, cp, mlen);
    x = rn_insert(cp, mask_rnhead, &maskduplicated, x);
    if (maskduplicated) {
#ifdef  _KERNEL
        cmn_err(CE_WARN, "rn_addmask: mask impossibly already in tree");
#else
        syslog(LOG_ERR, "rn_addmask: mask impossibly already in tree");
#endif  /* _KERNEL */
        Free(saved_x, radix_node_cache);
        return (x);
    }
    /*
     * Calculate index of mask, and check for normalcy.
     * First find the first byte with a 0 bit, then if there are
     * more bits left (remember we already trimmed the trailing 0's),
     * the pattern must be one of those in normal_chars[], or we have
     * a non-contiguous mask.
     */
    cplim = netmask + mlen;
    isnormal = 1;
    for (cp = netmask + skip; (cp < cplim) && *(uchar_t *)cp == 0xff; )
        cp++;
    if (cp != cplim) {
        static uint8_t normal_chars[] = {
            0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff};

        for (j = 0x80; (j & *cp) != 0; j >>= 1)
            b++;
        if (*cp != normal_chars[b] || cp != (cplim - 1))
            isnormal = 0;
    }
    b += (cp - netmask) << 3;
    x->rn_bit = -1 - b;
    if (isnormal)
        x->rn_flags |= RNF_NORMAL;
    return (x);
}

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

    if (LEN(mp) > LEN(np))
        /* not really, but need to check longer one first */
        return (B_TRUE);
    if (LEN(mp) == LEN(np))
        for (lim = mp + LEN(mp); mp < lim; )
            if (*mp++ > *np++)
                return (B_TRUE);
    return (B_FALSE);
}

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

    MKGet(m);
    if (m == 0) {
#ifndef _KERNEL
        syslog(LOG_ERR, "Mask for route not entered\n");
#endif  /* _KERNEL */
        return (0);
    }
    bzero(m, sizeof (*m));
    m->rm_bit = tt->rn_bit;
    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(v_arg, n_arg, head, treenodes)
    void *v_arg, *n_arg;
    struct radix_node_head *head;
    struct radix_node treenodes[2];
{
    caddr_t v = (caddr_t)v_arg, netmask = (caddr_t)n_arg;
    struct radix_node *t, *x = 0, *tt;
    struct radix_node *saved_tt, *top = head->rnh_treetop;
    short b = 0, b_leaf = 0;
    int keyduplicated;
    caddr_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_offset)) == 0)
            return (0);
        b_leaf = x->rn_bit;
        b = -1 - x->rn_bit;
        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)
                return (0);
            if (netmask == 0 ||
                (tt->rn_mask &&
                /* index (netmask) > node */
                ((b_leaf < tt->rn_bit) ||
                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.
         *
         * We also reverse, or doubly link the list through the
         * parent pointer.
         */
        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_parent = x = t->rn_parent;
            t->rn_parent = tt; /* parent */
            if (x->rn_left == t)
                x->rn_left = tt;
            else
                x->rn_right = tt;
            saved_tt = tt; x = xx;
        } else {
            (tt = treenodes)->rn_dupedkey = t->rn_dupedkey;
            t->rn_dupedkey = tt;
            /* Set rn_parent value for tt and tt->rn_dupedkey */
            tt->rn_parent = t;
            if (tt->rn_dupedkey)
                tt->rn_dupedkey->rn_parent = tt;
        }
        tt->rn_key = v;
        tt->rn_bit = -1;
        tt->rn_flags = RNF_ACTIVE;
    }
    /*
     * Put mask in tree.
     */
    if (netmask) {
        tt->rn_mask = netmask;
        tt->rn_bit = x->rn_bit;
        tt->rn_flags |= x->rn_flags & RNF_NORMAL;
    }
    t = saved_tt->rn_parent;
    if (keyduplicated)
        goto key_exists;
    b_leaf = -1 - t->rn_bit;
    if (t->rn_right == saved_tt)
        x = t->rn_left;
    else
        x = t->rn_right;
    /* Promote general routes from below */
    if (x->rn_bit < 0) {
        for (mp = &t->rn_mklist; x; x = x->rn_dupedkey)
        if (x->rn_mask && (x->rn_bit >= b_leaf) && x->rn_mklist == 0) {
            *mp = m = rn_new_radix_mask(x, 0);
            if (m)
                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_bit >= b_leaf)
                break;
        t->rn_mklist = m; *mp = 0;
    }
key_exists:
    /* Add new route to highest possible ancestor's list */
    if ((netmask == 0) || (b > t->rn_bit))
        return (tt); /* can't lift at all */
    b_leaf = tt->rn_bit;
    do {
        x = t;
        t = t->rn_parent;
    } while (b <= t->rn_bit && 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_bit < b_leaf)
            continue;
        if (m->rm_bit > b_leaf)
            break;
        if (m->rm_flags & RNF_NORMAL) {
            mmask = m->rm_leaf->rn_mask;
            if (tt->rn_flags & RNF_NORMAL) {
#ifdef  _KERNEL
                cmn_err(CE_WARN, "Non-unique normal route, "
                    "mask not entered\n");
#else
                syslog(LOG_ERR, "Non-unique normal route, "
                    "mask not entered\n");
#endif  /* _KERNEL */
                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(v_arg, netmask_arg, head)
    void *v_arg, *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;
    caddr_t v, netmask;
    int b, head_off, vlen;

    v = v_arg;
    netmask = netmask_arg;
    x = head->rnh_treetop;
    tt = rn_search(v, x);
    head_off = x->rn_offset;
    vlen =  LEN(v);
    saved_tt = tt;
    top = x;
    if (tt == 0 ||
        bcmp(v + head_off, tt->rn_key + head_off, vlen - head_off))
        return (0);
    /*
     * Delete our route from mask lists.
     */
    if (netmask) {
        if ((x = rn_addmask(netmask, 1, head_off)) == 0)
            return (0);
        netmask = x->rn_key;
        while (tt->rn_mask != netmask)
            if ((tt = tt->rn_dupedkey) == 0)
                return (0);
    }
    if (tt->rn_mask == 0 || (saved_m = m = tt->rn_mklist) == 0)
        goto on1;
    if (tt->rn_flags & RNF_NORMAL) {
        if (m->rm_leaf != tt || m->rm_refs > 0) {
#ifdef  _KERNEL
            cmn_err(CE_WARN,
                "rn_delete: inconsistent annotation\n");
#else
            syslog(LOG_ERR, "rn_delete: inconsistent annotation\n");
#endif  /* _KERNEL */
            return (0);  /* dangling ref could cause disaster */
        }
    } else {
        if (m->rm_mask != tt->rn_mask) {
#ifdef  _KERNEL
            cmn_err(CE_WARN,
                "rn_delete: inconsistent annotation 2\n");
#else
            syslog(LOG_ERR,
                "rn_delete: inconsistent annotation 2\n");
#endif  /* _KERNEL */
            goto on1;
        }
        if (--m->rm_refs >= 0)
            goto on1;
    }
    b = -1 - tt->rn_bit;
    t = saved_tt->rn_parent;
    if (b > t->rn_bit)
        goto on1; /* Wasn't lifted at all */
    do {
        x = t;
        t = t->rn_parent;
    } while (b <= t->rn_bit && 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 == 0) {
#ifdef  _KERNEL
        cmn_err(CE_WARN, "rn_delete: couldn't find our annotation\n");
#else
        syslog(LOG_ERR, "rn_delete: couldn't find our annotation\n");
#endif  /* _KERNEL */
        if (tt->rn_flags & RNF_NORMAL)
            return (0); /* Dangling ref to us */
    }
on1:
    /*
     * Eliminate us from tree
     */
    if (tt->rn_flags & RNF_ROOT)
        return (0);
    t = tt->rn_parent;
    dupedkey = saved_tt->rn_dupedkey;
    if (dupedkey) {
        /*
         * Here, tt is the deletion target and
         * saved_tt is the head of the dupekey chain.
         */
        if (tt == saved_tt) {
            /* remove from head of chain */
            x = dupedkey; x->rn_parent = t;
            if (t->rn_left == tt)
                t->rn_left = x;
            else
                t->rn_right = x;
        } else {
            /* find node in front of tt on the chain */
            for (x = p = saved_tt; p && p->rn_dupedkey != tt; )
                p = p->rn_dupedkey;
            if (p) {
                p->rn_dupedkey = tt->rn_dupedkey;
                if (tt->rn_dupedkey)        /* parent */
                    tt->rn_dupedkey->rn_parent = p;
                                /* parent */
            } else
#ifdef  _KERNEL
                cmn_err(CE_WARN,
                    "rn_delete: couldn't find us\n");
#else
                syslog(LOG_ERR,
                    "rn_delete: couldn't find us\n");
#endif  /* _KERNEL */
        }
        t = tt + 1;
        if (t->rn_flags & RNF_ACTIVE) {
            *++x = *t;
            p = t->rn_parent;
            if (p->rn_left == t)
                p->rn_left = x;
            else
                p->rn_right = x;
            x->rn_left->rn_parent = x;
            x->rn_right->rn_parent = x;
        }
        goto out;
    }
    if (t->rn_left == tt)
        x = t->rn_right;
    else
        x = t->rn_left;
    p = t->rn_parent;
    if (p->rn_right == t)
        p->rn_right = x;
    else
        p->rn_left = x;
    x->rn_parent = p;
    /*
     * Demote routes attached to us.
     */
    if (t->rn_mklist) {
        if (x->rn_bit >= 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)
#ifdef  _KERNEL
                cmn_err(CE_WARN,
                    "rn_delete: Orphaned Mask %p at %p\n",
                    (void *)m, (void *)x);
#else
                syslog(LOG_ERR,
                    "rn_delete: Orphaned Mask %p at %p\n",
                    (void *)m, (void *)x);
#endif  /* _KERNEL */
        }
    }
    /*
     * We may be holding an active internal node in the tree.
     */
    x = tt + 1;
    if (t != x) {
        *t = *x;
        t->rn_left->rn_parent = t;
        t->rn_right->rn_parent = t;
        p = x->rn_parent;
        if (p->rn_left == x)
            p->rn_left = t;
        else
            p->rn_right = t;
    }
out:
    tt->rn_flags &= ~RNF_ACTIVE;
    tt[1].rn_flags &= ~RNF_ACTIVE;
    return (tt);
}

/*
 * Walk the radix tree; For the kernel routing table, we hold additional
 * refs on the ire_bucket to ensure that the walk function f() does not
 * run into trashed memory. The kernel routing table is identified by
 * a rnh_treetop that has RNF_SUNW_FT set in the rn_flags.
 * Note that all refs takein in rn_walktree are released before it returns,
 * so that f() will need to take any additional references on memory
 * to be passed back to the caller of rn_walktree.
 */
static int
rn_walktree(h, f, w)
    struct radix_node_head *h;
    walktree_f_t *f;
    void *w;
{
    return (rn_walktree_mt(h, f, w, NULL, NULL));
}
static int
rn_walktree_mt(h, f, w, lockf, unlockf)
    struct radix_node_head *h;
    walktree_f_t *f;
    void *w;
    lockf_t lockf, unlockf;
{
    int error;
    struct radix_node *base, *next;
    struct radix_node *rn = h->rnh_treetop;
    boolean_t is_mt = B_FALSE;

    if (lockf != NULL) {
        ASSERT(unlockf != NULL);
        is_mt = B_TRUE;
    }
    /*
     * 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.
     */
    RADIX_NODE_HEAD_RLOCK(h);
    /* First time through node, go left */
    while (rn->rn_bit >= 0) {
        rn = rn->rn_left;
    }

    if (is_mt)
        (*lockf)(rn);

    for (;;) {
        base = rn;
        /* If at right child go back up, otherwise, go right */
        while (rn->rn_parent->rn_right == rn &&
            (rn->rn_flags & RNF_ROOT) == 0) {
            rn = rn->rn_parent;
        }
        /* Find the next *leaf* since next node might vanish, too */
        for (rn = rn->rn_parent->rn_right; rn->rn_bit >= 0; ) {
            rn = rn->rn_left;
        }
        next = rn;

        if (is_mt && next != NULL)
            (*lockf)(next);

        /* Process leaves */
        while ((rn = base) != NULL) {
            base = rn->rn_dupedkey;

            if (is_mt && base != NULL)
                (*lockf)(base);

            RADIX_NODE_HEAD_UNLOCK(h);
            if (!(rn->rn_flags & RNF_ROOT) &&
                (error = (*f)(rn, w))) {
                if (is_mt) {
                    (*unlockf)(rn);
                    if (base != NULL)
                        (*unlockf)(base);
                    if (next != NULL)
                        (*unlockf)(next);
                }
                return (error);
            }
            if (is_mt)
                (*unlockf)(rn);
            RADIX_NODE_HEAD_RLOCK(h);
        }
        rn = next;
        if (rn->rn_flags & RNF_ROOT) {
            RADIX_NODE_HEAD_UNLOCK(h);
            /*
             * no ref to release, since we never take a ref
             * on the root node- it can't be deleted.
             */
            return (0);
        }
    }
    /* NOTREACHED */
}

/*
 * Allocate and initialize an empty tree. This has 3 nodes, which are
 * part of the radix_node_head (in the order <left,root,right>) and are
 * marked RNF_ROOT so they cannot be freed.
 * The leaves have all-zero and all-one keys, with significant
 * bits starting at 'off'.
 * Return 1 on success, 0 on error.
 */
int
rn_inithead(head, off)
    void **head;
    int off;
{
    struct radix_node_head *rnh;
    struct radix_node *t, *tt, *ttt;
    if (*head)
        return (1);
    R_ZallocSleep(rnh, struct radix_node_head *, sizeof (*rnh));
    if (rnh == 0)
        return (0);
#ifdef _KERNEL
    RADIX_NODE_HEAD_LOCK_INIT(rnh);
#endif
    *head = rnh;
    t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
    ttt = rnh->rnh_nodes + 2;
    t->rn_right = ttt;
    t->rn_parent = t;
    tt = t->rn_left;    /* ... which in turn is rnh->rnh_nodes */
    tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
    tt->rn_bit = -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_matchaddr_args = rn_match_args;
    rnh->rnh_lookup = rn_lookup;
    rnh->rnh_walktree = rn_walktree;
    rnh->rnh_walktree_mt = rn_walktree_mt;
    rnh->rnh_walktree_from = NULL;  /* not implemented */
    rnh->rnh_treetop = t;
    return (1);
}

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

#ifdef  _KERNEL
    radix_mask_cache = kmem_cache_create("radix_mask",
        sizeof (struct radix_mask), 0, NULL, NULL, NULL, NULL, NULL, 0);
    radix_node_cache = kmem_cache_create("radix_node",
        max_keylen + 2 * sizeof (struct radix_node),
        0, NULL, NULL, NULL, NULL, NULL, 0);
#endif /* _KERNEL */
    R_ZallocSleep(rn_zeros, char *, 2 * max_keylen);

    ASSERT(rn_zeros != NULL);
    bzero(rn_zeros, 2 * max_keylen);
    rn_ones = cp = rn_zeros + max_keylen;
    cplim = rn_ones + max_keylen;
    while (cp < cplim)
        *cp++ = -1;
    if (rn_inithead((void **)(void *)&mask_rnhead, 0) == 0)
        panic("rn_init: could not init mask_rnhead ");
}

int
rn_freenode(n, p)
    struct radix_node *n;
    void *p;
{
    struct  radix_node_head *rnh = p;
    struct  radix_node *d;

    d = rnh->rnh_deladdr(n->rn_key, NULL, rnh);
    if (d != NULL) {
        Free(d, radix_node_cache);
    }
    return (0);
}


void
rn_freehead(rnh)
    struct radix_node_head *rnh;
{
    (void) rn_walktree(rnh, rn_freenode, rnh);

    rnh->rnh_addaddr = NULL;
    rnh->rnh_deladdr = NULL;
    rnh->rnh_matchaddr = NULL;
    rnh->rnh_lookup = NULL;
    rnh->rnh_walktree = NULL;

#ifdef  _KERNEL
    RADIX_NODE_HEAD_DESTROY(rnh);
    FreeHead(rnh, sizeof (*rnh));
#else
    Free(rnh, NULL);
#endif  /* _KERNEL */
}

void
rn_fini()
{
    struct radix_mask *m;

    if (rn_zeros != NULL) {
#ifdef _KERNEL
        FreeHead(rn_zeros, 2 * max_keylen);
#else
        Free(rn_zeros, NULL);
#endif
        rn_zeros = NULL;
    }


    if (mask_rnhead != NULL) {
        rn_freehead(mask_rnhead);
        mask_rnhead = NULL;
    }

    while ((m = rn_mkfreelist) != NULL) {
        rn_mkfreelist = m->rm_mklist;
        Free(m, NULL);
    }
}