[dragonfly.git] / sys / net / radix.c

/*
 * 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 acknowledgement:
 *      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/sys/net/radix.c,v 1.20.2.3 2002/04/28 05:40:25 suz Exp $
 * $DragonFly: src/sys/net/radix.c,v 1.7 2004/12/15 00:11:04 hsu Exp $
 */

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

/*
 * The arguments to the radix functions are really counted byte arrays with
 * the length in the first byte.  struct sockaddr's fit this type structurally.
 */
#define clen(c) (*(u_char *)(c))

static int rn_walktree_from(struct radix_node_head *h, u_char *a, u_char *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(char *, struct radix_node_head *, boolean_t *,
               struct radix_node [2]),
    *rn_newpair(char *, int, struct radix_node[2]),
    *rn_search(const char *, struct radix_node *),
    *rn_search_m(const char *, struct radix_node *, const char *);

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)

static int rn_lexobetter(char *m, char *n);
static struct radix_mask *
    rn_new_radix_mask(struct radix_node *tt, struct radix_mask *nextmask);
static int
    rn_satisfies_leaf(char *trial, struct radix_node *leaf, int skip);

static __inline struct radix_mask *
MKGet(struct radix_mask **l)
{
        struct radix_mask *m;

        if (*l != NULL) {
                m = *l;
                *l = m->rm_next;
        } else {
                R_Malloc(m, struct radix_mask *, sizeof (*(m)));
        }
        return m;
}

static __inline void
MKFree(struct radix_mask **l, struct radix_mask *m)
{
        m->rm_next = *l;
        *l = m;
}

/*
 * 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(const char *v, struct radix_node *head)
{
        struct radix_node *x;

        x = head;
        while (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(const char *v, struct radix_node *head, const char *m)
{
        struct radix_node *x;

        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;
}

boolean_t
rn_refines(char *m, char *n)
{
        char *lim, *lim2;
        int longer = clen(n++) - clen(m++);
        boolean_t masks_are_equal = TRUE;

        lim2 = lim = n + clen(n);
        if (longer > 0)
                lim -= longer;
        while (n < lim) {
                if (*n & ~(*m))
                        return 0;
                if (*n++ != *m++)
                        masks_are_equal = FALSE;
        }
        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(char *key, char *mask, struct radix_node_head *head)
{
        struct radix_node *x;
        char *netmask = NULL;

        if (mask != NULL) {
                x = rn_addmask(mask, TRUE, head->rnh_treetop->rn_offset);
                if (x == NULL)
                        return (NULL);
                netmask = x->rn_key;
        }
        x = rn_match(key, head);
        if (x != NULL && netmask != NULL) {
                while (x != NULL && x->rn_mask != netmask)
                        x = x->rn_dupedkey;
        }
        return x;
}

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

        if (cp3 == NULL)
                cp3 = rn_ones;
        else
                length = min(length, clen(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(char *key, struct radix_node_head *head)
{
        struct radix_node *t, *x;
        char *cp = key, *cp2;
        char *cplim;
        struct radix_node *saved_t, *top = head->rnh_treetop;
        int off = top->rn_offset, klen, matched_off;
        int test, b, rn_bit;

        t = rn_search(key, top);
        /*
         * 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 != NULL)
                klen = clen(t->rn_mask);
        else
                klen = clen(key);
        cp += off; cp2 = t->rn_key + off; cplim = key + klen;
        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 - key;
        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 == 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_bit <= t->rn_bit)
                                return t;
                } else if (rn_satisfies_leaf(key, t, matched_off))
                                return t;
        }
        t = saved_t;
        /* start searching up the tree */
        do {
                struct radix_mask *m;

                t = t->rn_parent;
                /*
                 * 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".
                 */
                m = t->rn_mklist;
                while (m != NULL) {
                        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(key, t, m->rm_mask);
                                while (x != NULL && x->rn_mask != m->rm_mask)
                                        x = x->rn_dupedkey;
                                if (x && rn_satisfies_leaf(key, x, off))
                                        return x;
                        }
                        m = m->rm_next;
                }
        } while (t != top);
        return NULL;
}

#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(char *key, int indexbit, struct radix_node nodes[2])
{
        struct radix_node *leaf = nodes, *interior = leaf + 1;

        interior->rn_bit = indexbit;
        interior->rn_bmask = 0x80 >> (indexbit & 0x7);
        interior->rn_offset = indexbit >> 3;
        interior->rn_left = leaf;
        interior->rn_mklist = NULL;

        leaf->rn_bit = -1;
        leaf->rn_key = key;
        leaf->rn_parent = interior;
        leaf->rn_flags = interior->rn_flags = RNF_ACTIVE;
        leaf->rn_mklist = NULL;

#ifdef RN_DEBUG
        leaf->rn_info = rn_nodenum++;
        interior->rn_info = rn_nodenum++;
        leaf->rn_twin = interior;
        leaf->rn_ybro = rn_clist;
        rn_clist = leaf;
#endif
        return interior;
}

static struct radix_node *
rn_insert(
        char *key,
        struct radix_node_head *head,
        boolean_t *dupentry,
        struct radix_node nodes[2])
{
        struct radix_node *top = head->rnh_treetop;
        int head_off = top->rn_offset, klen = clen(key);
        struct radix_node *t = rn_search(key, top);
        char *cp = key + head_off;
        int b;
        struct radix_node *tt;
        /*
         * Find first bit at which the key and t->rn_key differ
         */
    {
        char *cp2 = t->rn_key + head_off;
        int cmp_res;
        char *cplim = key + klen;

        while (cp < cplim)
                if (*cp2++ != *cp++)
                        goto on1;
        *dupentry = TRUE;
        return t;
on1:
        *dupentry = FALSE;
        cmp_res = (cp[-1] ^ cp2[-1]) & 0xff;
        for (b = (cp - key) << 3; cmp_res; b--)
                cmp_res >>= 1;
    }
    {
        struct radix_node *p, *x = top;

        cp = key;
        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(key, 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(char *netmask, boolean_t search, int skip)
{
        struct radix_node *x, *saved_x;
        char *cp, *cplim;
        int b = 0, mlen, m0, j;
        boolean_t maskduplicated, isnormal;
        static int last_zeroed = 0;

        if ((mlen = clen(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 = NULL;
        if (x != NULL || search)
                return (x);
        R_Malloc(x, struct radix_node *, max_keylen + 2 * sizeof (*x));
        if ((saved_x = x) == NULL)
                return (NULL);
        bzero(x, max_keylen + 2 * sizeof (*x));
        netmask = cp = (char *)(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.
         */
        isnormal = TRUE;
        cplim = netmask + mlen;
        for (cp = netmask + skip; cp < cplim && clen(cp) == 0xff;)
                cp++;
        if (cp != cplim) {
                for (j = 0x80; (j & *cp) != 0; j >>= 1)
                        b++;
                if (*cp != normal_chars[b] || cp != (cplim - 1))
                        isnormal = FALSE;
        }
        b += (cp - netmask) << 3;
        x->rn_bit = -1 - b;
        if (isnormal)
                x->rn_flags |= RNF_NORMAL;
        return (x);
}

static boolean_t        /* XXX: arbitrary ordering for non-contiguous masks */
rn_lexobetter(char *mp, char *np)
{
        char *lim;

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

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

        m = MKGet(&rn_mkfreelist);
        if (m == NULL) {
                log(LOG_ERR, "Mask for route not entered\n");
                return (NULL);
        }
        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_next = nextmask;
        tt->rn_mklist = m;
        return m;
}

struct radix_node *
rn_addroute(char *key, char *netmask, struct radix_node_head *head,
            struct radix_node treenodes[2])
{
        struct radix_node *t, *x = NULL, *tt;
        struct radix_node *saved_tt, *top = head->rnh_treetop;
        short b = 0, b_leaf = 0;
        boolean_t keyduplicated;
        char *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 != NULL)  {
                if ((x = rn_addmask(netmask, FALSE, top->rn_offset)) == NULL)
                        return (NULL);
                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(key, head, &keyduplicated, treenodes);
        if (keyduplicated) {
                for (t = tt; tt; t = tt, tt = tt->rn_dupedkey) {
                        if (tt->rn_mask == netmask)
                                return (NULL);
                        if (netmask == NULL ||
                            (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.
                 */
                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 != NULL)            /* 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 = key;
                tt->rn_bit = -1;
                tt->rn_flags = RNF_ACTIVE;
        }
        /*
         * Put mask in tree.
         */
        if (netmask != NULL) {
                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) {
                mp = &t->rn_mklist;
                while (x != NULL) {
                        if (x->rn_mask != NULL &&
                            x->rn_bit >= b_leaf &&
                            x->rn_mklist == NULL) {
                                *mp = m = rn_new_radix_mask(x, NULL);
                                if (m != NULL)
                                        mp = &m->rm_next;
                        }
                        x = x->rn_dupedkey;
                }
        } else if (x->rn_mklist != NULL) {
                /*
                 * Skip over masks whose index is > that of new node
                 */
                for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_next)
                        if (m->rm_bit >= b_leaf)
                                break;
                t->rn_mklist = m;
                *mp = NULL;
        }
on2:
        /* Add new route to highest possible ancestor's list */
        if ((netmask == NULL) || (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_next) {
                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(char *key, char *netmask, 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;
        int b, head_off, klen;

        x = head->rnh_treetop;
        tt = rn_search(key, x);
        head_off = x->rn_offset;
        klen =  clen(key);
        saved_tt = tt;
        top = x;
        if (tt == NULL ||
            bcmp(key + head_off, tt->rn_key + head_off, klen - head_off))
                return (NULL);
        /*
         * Delete our route from mask lists.
         */
        if (netmask != NULL) {
                if ((x = rn_addmask(netmask, TRUE, head_off)) == NULL)
                        return (NULL);
                netmask = x->rn_key;
                while (tt->rn_mask != netmask)
                        if ((tt = tt->rn_dupedkey) == NULL)
                                return (NULL);
        }
        if (tt->rn_mask == NULL || (saved_m = m = tt->rn_mklist) == NULL)
                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 (NULL);  /* 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_next)
                if (m == saved_m) {
                        *mp = m->rm_next;
                        MKFree(&rn_mkfreelist, m);
                        break;
                }
        if (m == NULL) {
                log(LOG_ERR, "rn_delete: couldn't find our annotation\n");
                if (tt->rn_flags & RNF_NORMAL)
                        return (NULL); /* Dangling ref to us */
        }
on1:
        /*
         * Eliminate us from tree
         */
        if (tt->rn_flags & RNF_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) t->rn_ybro = tt->rn_ybro;
#endif
        t = tt->rn_parent;
        dupedkey = saved_tt->rn_dupedkey;
        if (dupedkey != NULL) {
                /*
                 * at this point, 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 != NULL) {
                if (x->rn_bit >= 0) {
                        for (mp = &x->rn_mklist; (m = *mp);)
                                mp = &m->rm_next;
                        *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_next;

                                        x->rn_mklist = NULL;
                                        if (--(m->rm_refs) < 0)
                                                MKFree(&rn_mkfreelist, 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, u_char *xa, u_char *xm,
                 walktree_f_t *f, void *w)
{
        struct radix_node *base, *next;
        struct radix_node *rn, *last = NULL /* shut up gcc */;
        int stopping = 0;
        int lastb, error;

        /*
         * 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) != NULL) {
                        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)
{
        struct radix_node *base, *next;
        struct radix_node *rn = h->rnh_treetop;
        int error;

        /*
         * 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))
                        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)
{
        struct radix_node_head *rnh;
        struct radix_node *t, *left, *right;

        if (*head)
                return (1);
        R_Malloc(rnh, struct radix_node_head *, sizeof (*rnh));
        if (rnh == NULL)
                return (0);
        bzero(rnh, sizeof (*rnh));
        *head = rnh;

        t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
        right = rnh->rnh_nodes + 2;
        t->rn_right = right;
        t->rn_parent = t;

        left = t->rn_left;
        left->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
        left->rn_bit = -1 - off;

        *right = *left;
        right->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()
{
        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 **)&mask_rnhead, 0) == 0)
                panic("rn_init 2");
}