source: rtems/cpukit/libnetworking/net/radix.c @ b25b88e7

/*
 * 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: src/sys/net/radix.c,v 1.36 2004/04/21 15:27:36 luigi Exp $
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/*
 * Routines to build and maintain radix trees for routing lookups.
 */
#ifndef _RADIX_H_
#include <sys/param.h>
#ifdef  _KERNEL
#include <sys/systm.h>
#include <sys/malloc.h>
#define M_DONTWAIT M_NOWAIT
#include <sys/domain.h>
#else
#include <stdlib.h>
#endif
#include <sys/syslog.h>
#include <net/radix.h>
#endif

static int      rn_walktree_from(struct radix_node_head *h, void *a, void *m,
                    walktree_f_t *f, void *w);
static int rn_walktree(struct radix_node_head *, walktree_f_t *, void *);
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 *);

static int      max_keylen;
static struct radix_mask *rn_mkfreelist;
static struct radix_node_head *mask_rnhead;
static char *addmask_key;
static char normal_chars[] = {0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, -1};
static char *rn_zeros, *rn_ones;

#define rn_masktop (mask_rnhead->rnh_treetop)
#undef Bcmp
#define Bcmp(a, b, l) \
        (l == 0 ? 0 : bcmp((caddr_t)(a), (caddr_t)(b), (u_long)l))

static int      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 int      rn_satisfies_leaf(char *trial, struct radix_node *leaf,
                                       int skip);

/*
 * 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 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_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.
 */

static struct radix_node *
rn_search(void *v_arg, struct radix_node *head)
{
        register struct radix_node *x;
        register 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);
}

static struct radix_node *
rn_search_m(void *v_arg, struct radix_node *head, void *m_arg)
{
        register struct radix_node *x;
        register 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;
}

int
rn_refines(void *m_arg, void *n_arg)
{
        register caddr_t m = m_arg, n = n_arg;
        register caddr_t lim, lim2 = lim = n + *(u_char *)n;
        int longer = (*(u_char *)n++) - (int)(*(u_char *)m++);
        int masks_are_equal = 1;

        if (longer > 0)
                lim -= longer;
        while (n < lim) {
                if (*n & ~(*m))
                        return 0;
                if (*n++ != *m++)
                        masks_are_equal = 0;
        }
        while (n < lim2)
                if (*n++)
                        return 0;
        if (masks_are_equal && (longer < 0))
                for (lim2 = m - longer; m < lim2; )
                        if (*m++)
                                return 1;
        return (!masks_are_equal);
}

struct radix_node *
rn_lookup(void *v_arg, void *m_arg, struct radix_node_head *head)
{
        register struct radix_node *x;
        caddr_t netmask = 0;

        if (m_arg) {
                x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_offset);
                if (x == 0)
                        return (0);
                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;
}

static int
rn_satisfies_leaf(char *trial, struct radix_node *leaf, int skip)
{
        register char *cp = trial, *cp2 = leaf->rn_key, *cp3 = leaf->rn_mask;
        char *cplim;
        int length = min(*(u_char *)cp, *(u_char *)cp2);

        if (cp3 == 0)
                cp3 = rn_ones;
        else
                length = min(length, *(u_char *)cp3);
        cplim = cp + length; cp3 += skip; cp2 += skip;
        for (cp += skip; cp < cplim; cp++, cp2++, cp3++)
                if ((*cp ^ *cp2) & *cp3)
                        return 0;
        return 1;
}

struct radix_node *
rn_match(void *v_arg, struct radix_node_head *head)
{
        caddr_t v = v_arg;
        register struct radix_node *t = head->rnh_treetop, *x;
        register caddr_t cp = v, cp2;
        caddr_t cplim;
        struct radix_node *saved_t, *top = t;
        int off = t->rn_offset, vlen = *(u_char *)cp, matched_off;
        register 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 = *(u_char *)t->rn_mask;
        cp += off; cp2 = t->rn_key + off; cplim = v + vlen;
        for (; cp < cplim; cp++, cp2++)
                if (*cp != *cp2)
                        goto on1;
        /*
         * 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;
        return t;
on1:
        test = (*cp ^ *cp2) & 0xff; /* find first bit that differs */
        for (b = 7; (test >>= 1) > 0;)
                b--;
        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; 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)
                                return t;
                } else if (rn_satisfies_leaf(v, t, matched_off))
                                return t;
        t = saved_t;
        /* start searching up the tree */
        do {
                register struct radix_mask *m;
                t = t->rn_parent;
                m = t->rn_mklist;
                if (m) {
                        /*
                         * 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_bit <= m->rm_bit)
                                                return (m->rm_leaf);
                                } else {
                                        off = min(t->rn_offset, matched_off);
                                        x = rn_search_m(v, t, m->rm_mask);
                                        while (x && x->rn_mask != m->rm_mask)
                                                x = x->rn_dupedkey;
                                        if (x && rn_satisfies_leaf(v, x, off))
                                                    return x;
                                }
                                m = m->rm_mklist;
                        } while (m);
                }
        } while (t != top);
        return 0;
}

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

static struct radix_node *
rn_newpair(void *v, int b, struct radix_node nodes[2])
{
        register 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;
        tt->rn_bit = -1;
        tt->rn_key = (caddr_t)v;
        tt->rn_parent = 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, 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)*((u_char *)v);
        register struct radix_node *t = rn_search(v_arg, top);
        register caddr_t cp = v + head_off;
        register int b;
        struct radix_node *tt;
        /*
         * Find first bit at which v and t->rn_key differ
         */
    {
        register caddr_t cp2 = t->rn_key + head_off;
        register 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;
    }
    {
        register 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 */
#ifdef RN_DEBUG
        if (rn_debug)
                log(LOG_DEBUG, "rn_insert: Going In:\n"), traverse(p);
#endif
        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; /* frees x, p as temp vars below */
        if ((cp[t->rn_offset] & t->rn_bmask) == 0) {
                t->rn_right = x;
        } else {
                t->rn_right = tt;
                t->rn_left = x;
        }
#ifdef RN_DEBUG
        if (rn_debug)
                log(LOG_DEBUG, "rn_insert: Coming Out:\n"), traverse(p);
#endif
    }
        return (tt);
}

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

        if ((mlen = *(u_char *)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_Malloc(x, struct radix_node *, max_keylen + 2 * sizeof (*x));
        if ((saved_x = x) == 0)
                return (0);
        Bzero(x, max_keylen + 2 * sizeof (*x));
        netmask = cp = (caddr_t)(x + 2);
        Bcopy(addmask_key, cp, mlen);
        x = rn_insert(cp, mask_rnhead, &maskduplicated, x);
        if (maskduplicated) {
                log(LOG_ERR, "rn_addmask: mask impossibly already in tree");
                Free(saved_x);
                return (x);
        }
        /*
         * Calculate index of mask, and check for normalcy.
         */
        cplim = netmask + mlen; isnormal = 1;
        for (cp = netmask + skip; (cp < cplim) && *(u_char *)cp == 0xff;)
                cp++;
        if (cp != cplim) {
                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);
}

static int      /* XXX: arbitrary ordering for non-contiguous masks */
rn_lexobetter(void *m_arg, void *n_arg)
{
        register u_char *mp = m_arg, *np = n_arg, *lim;

        if (*mp > *np)
                return 1;  /* not really, but need to check longer one first */
        if (*mp == *np)
                for (lim = mp + *mp; mp < lim;)
                        if (*mp++ > *np++)
                                return 1;
        return 0;
}

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

        MKGet(m);
        if (m == 0) {
                log(LOG_ERR, "Mask for route not entered\n");
                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;
}

struct radix_node *
rn_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
     struct radix_node treenodes[2])
{
        caddr_t v = (caddr_t)v_arg, netmask = (caddr_t)n_arg;
        register 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 &&
                             ((b_leaf < tt->rn_bit) /* index(netmask) > node */
                              || 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;
                        tt->rn_parent = t;                              /* parent */
                        if (tt->rn_dupedkey)                    /* parent */
                                tt->rn_dupedkey->rn_parent = tt;        /* parent */
                }
#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 = (caddr_t) 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 on2;
        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); mp = &m->rm_mklist)
                        if (m->rm_bit >= b_leaf)
                                break;
                t->rn_mklist = m; *mp = 0;
        }
on2:
        /* 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); 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) {
                                log(LOG_ERR,
                                "Non-unique normal route, mask not entered\n");
                                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;
}

struct radix_node *
rn_delete(void *v_arg, void *netmask_arg, struct radix_node_head *head)
{
        register 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 =  *(u_char *)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) {
                        log(LOG_ERR, "rn_delete: inconsistent annotation\n");
                        return 0;  /* dangling ref could cause disaster */
                }
        } else {
                if (m->rm_mask != tt->rn_mask) {
                        log(LOG_ERR, "rn_delete: inconsistent annotation\n");
                        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); mp = &m->rm_mklist)
                if (m == saved_m) {
                        *mp = m->rm_mklist;
                        MKFree(m);
                        break;
                }
        if (m == 0) {
                log(LOG_ERR, "rn_delete: couldn't find our annotation\n");
                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);
#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) t->rn_ybro = tt->rn_ybro;
#endif
        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 log(LOG_ERR, "rn_delete: couldn't find us\n");
                }
                t = tt + 1;
                if  (t->rn_flags & RNF_ACTIVE) {
#ifndef RN_DEBUG
                        *++x = *t;
                        p = t->rn_parent;
#else
                        b = t->rn_info;
                        *++x = *t;
                        t->rn_info = b;
                        p = t->rn_parent;
#endif
                        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);)
                                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)
                                log(LOG_ERR,
                                    "rn_delete: Orphaned Mask %p at %p\n",
                                    (void *)m, (void *)x);
                }
        }
        /*
         * 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_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);
}

/*
 * This is the same as rn_walktree() except for the parameters and the
 * exit.
 */
static int
rn_walktree_from(struct radix_node_head *h, void *a, void *m,
     walktree_f_t *f, void *w)
{
        int error;
        struct radix_node *base, *next;
        u_char *xa = (u_char *)a;
        u_char *xm = (u_char *)m;
        register struct radix_node *rn, *last = 0 /* shut up gcc */;
        int stopping = 0;
        int lastb;

        /*
         * rn_search_m is sort-of-open-coded here.
         */
        /* printf("about to search\n"); */
        for (rn = h->rnh_treetop; rn->rn_bit >= 0; ) {
                last = rn;
                /* printf("rn_bit %d, rn_bmask %x, xm[rn_offset] %x\n",
                       rn->rn_bit, rn->rn_bmask, xm[rn->rn_offset]); */
                if (!(rn->rn_bmask & xm[rn->rn_offset])) {
                        break;
                }
                if (rn->rn_bmask & xa[rn->rn_offset]) {
                        rn = rn->rn_right;
                } else {
                        rn = rn->rn_left;
                }
        }
        /* printf("done searching\n"); */

        /*
         * Two cases: either we stepped off the end of our mask,
         * in which case last == rn, or we reached a leaf, in which
         * case we want to start from the last node we looked at.
         * Either way, last is the node we want to start from.
         */
        rn = last;
        lastb = rn->rn_bit;

        /* printf("rn %p, lastb %d\n", rn, lastb);*/

        /*
         * 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.
         */
        while (rn->rn_bit >= 0)
                rn = rn->rn_left;

        while (!stopping) {
                /* printf("node %p (%d)\n", rn, rn->rn_bit); */
                base = rn;
                /* If at right child go back up, otherwise, go right */
                while (rn->rn_parent->rn_right == rn
                       && !(rn->rn_flags & RNF_ROOT)) {
                        rn = rn->rn_parent;

                        /* if went up beyond last, stop */
                        if (rn->rn_bit < lastb) {
                                stopping = 1;
                                /* printf("up too far\n"); */
                        }
                }

                /* 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;
                /* Process leaves */
                while ((rn = base) != 0) {
                        base = rn->rn_dupedkey;
                        /* printf("leaf %p\n", rn); */
                        if (!(rn->rn_flags & RNF_ROOT)
                            && (error = (*f)(rn, w)))
                                return (error);
                }
                rn = next;

                if (rn->rn_flags & RNF_ROOT) {
                        /* printf("root, stopping"); */
                        stopping = 1;
                }

        }
        return 0;
}

static int
rn_walktree(struct radix_node_head *h, walktree_f_t *f, void *w)
{
        int error;
        struct radix_node *base, *next;
        register 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_bit >= 0)
                rn = rn->rn_left;
        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;
                /* Process leaves */
                while ((rn = base)) {
                        base = rn->rn_dupedkey;
                        if (!(rn->rn_flags & RNF_ROOT)
                            && (error = (*f)(rn, w)))
                                return (error);
                }
                rn = next;
                if (rn->rn_flags & RNF_ROOT)
                        return (0);
        }
        /* NOTREACHED */
}

int
rn_inithead(void **head, int off)
{
        register struct radix_node_head *rnh;
        register struct radix_node *t, *tt, *ttt;
        if (*head)
                return (1);
        R_Malloc(rnh, struct radix_node_head *, sizeof (*rnh));
        if (rnh == 0)
                return (0);
        Bzero(rnh, sizeof (*rnh));
        *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;
        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_lookup = rn_lookup;
        rnh->rnh_walktree = rn_walktree;
        rnh->rnh_walktree_from = rn_walktree_from;
        rnh->rnh_treetop = t;
        return (1);
}

void
rn_init(void)
{
        char *cp, *cplim;
#ifdef _KERNEL
        struct domain *dom;

        for (dom = domains; dom; dom = dom->dom_next)
                if (dom->dom_maxrtkey > max_keylen)
                        max_keylen = dom->dom_maxrtkey;
#endif
        if (max_keylen == 0) {
                log(LOG_ERR,
                    "rn_init: radix functions require max_keylen be set\n");
                return;
        }
        R_Malloc(rn_zeros, char *, 3 * max_keylen);
        if (rn_zeros == NULL)
                panic("rn_init");
        Bzero(rn_zeros, 3 * max_keylen);
        rn_ones = cp = rn_zeros + max_keylen;
        addmask_key = cplim = rn_ones + max_keylen;
        while (cp < cplim)
                *cp++ = -1;
        if (rn_inithead((void **)(void*)&mask_rnhead, 0) == 0)
                panic("rn_init 2");
}