/*      $OpenBSD: radix.c,v 1.61 2022/01/02 22:36:04 jsg Exp $  */
/*      $NetBSD: radix.c,v 1.20 2003/08/07 16:32:56 agc Exp $   */

/*
 * 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. 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     8.6 (Berkeley) 10/17/95
 */

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

#ifndef _KERNEL
#include "kern_compat.h"
#else
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/syslog.h>
#include <sys/pool.h>
#endif

#include <net/radix.h>

#define SALEN(sa)       (*(u_char *)(sa))

/*
 * Read-only variables, allocated & filled during rn_init().
 */
static char             *rn_zeros;      /* array of 0s */
static char             *rn_ones;       /* array of 1s */
static unsigned int      max_keylen;    /* size of the above arrays */
#define KEYLEN_LIMIT     64             /* maximum allowed keylen */


struct radix_node_head  *mask_rnhead;   /* head of shared mask tree */
struct pool              rtmask_pool;   /* pool for radix_mask structures */

static inline int rn_satisfies_leaf(char *, struct radix_node *, int);
static inline int rn_lexobetter(void *, void *);
static inline struct radix_mask *rn_new_radix_mask(struct radix_node *,
    struct radix_mask *);

int rn_refines(void *, void *);
int rn_inithead0(struct radix_node_head *, int);
struct radix_node *rn_addmask(void *, int, int);
struct radix_node *rn_insert(void *, struct radix_node_head *, int *,
    struct radix_node [2]);
struct radix_node *rn_newpair(void *, int, struct radix_node[2]);
void rn_link_dupedkey(struct radix_node *, struct radix_node *, int);

static inline struct radix_node *rn_search(void *, struct radix_node *);
struct radix_node *rn_search_m(void *, struct radix_node *, void *);
int rn_add_dupedkey(struct radix_node *, struct radix_node_head *,
    struct radix_node [2], u_int8_t);
void rn_fixup_nodes(struct radix_node *);
static inline struct radix_node *rn_lift_node(struct radix_node *);
void rn_add_radix_mask(struct radix_node *, int);
int rn_del_radix_mask(struct radix_node *);
static inline void rn_swap_nodes(struct radix_node *, struct radix_node *);

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

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

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

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

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

        lim2 = lim = n + *(u_char *)n;
        longer = (*(u_char *)n++) - (int)(*(u_char *)m++);
        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);
}

/* return a perfect match if m_arg is set, else do a regular rn_match */
struct radix_node *
rn_lookup(void *v_arg, void *m_arg, struct radix_node_head *head)
{
        struct radix_node *x, *tm;
        caddr_t netmask = 0;

        if (m_arg) {
                tm = rn_addmask(m_arg, 1, head->rnh_treetop->rn_off);
                if (tm == NULL)
                        return (NULL);
                netmask = tm->rn_key;
        }
        x = rn_match(v_arg, head);
        if (x && netmask) {
                while (x && x->rn_mask != netmask)
                        x = x->rn_dupedkey;
        }
        /* Never return internal nodes to the upper layer. */
        if (x && (x->rn_flags & RNF_ROOT))
                return (NULL);
        return x;
}

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

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

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

        t = rn_search(v, 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)
                vlen = SALEN(t->rn_mask);
        else
                vlen = SALEN(v);
        cp = v + 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!
         */
        if (t->rn_flags & RNF_ROOT)
                t = t->rn_dupedkey;

        KASSERT(t == NULL || (t->rn_flags & RNF_ROOT) == 0);
        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_b = -1 - b;
        /*
         * If there is a host route in a duped-key chain, it will be first.
         */
        saved_t = t;
        if (t->rn_mask == NULL)
                t = t->rn_dupedkey;
        for (; t; t = t->rn_dupedkey)
                /*
                 * Even if we don't match exactly as a host,
                 * we may match if the leaf we wound up at is
                 * a route to a net.
                 */
                if (t->rn_flags & RNF_NORMAL) {
                        if (rn_b <= t->rn_b) {
                                KASSERT((t->rn_flags & RNF_ROOT) == 0);
                                return t;
                        }
                } else if (rn_satisfies_leaf(v, t, matched_off)) {
                        KASSERT((t->rn_flags & RNF_ROOT) == 0);
                        return t;
                }
        t = saved_t;
        /* start searching up the tree */
        do {
                struct radix_mask *m;
                t = t->rn_p;
                m = t->rn_mklist;
                while (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".
                         */
                        if (m->rm_flags & RNF_NORMAL) {
                                if (rn_b <= m->rm_b) {
                                        KASSERT((m->rm_leaf->rn_flags &
                                            RNF_ROOT) == 0);
                                        return (m->rm_leaf);
                                }
                        } else {
                                struct radix_node *x;
                                off = min(t->rn_off, 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)) {
                                        KASSERT((x->rn_flags & RNF_ROOT) == 0);
                                        return x;
                                }
                        }
                        m = m->rm_mklist;
                }
        } while (t != top);
        return NULL;
}

struct radix_node *
rn_newpair(void *v, int b, struct radix_node nodes[2])
{
        struct radix_node *tt = nodes, *t = nodes + 1;
        t->rn_b = b;
        t->rn_bmask = 0x80 >> (b & 7);
        t->rn_l = tt;
        t->rn_off = b >> 3;
        tt->rn_b = -1;
        tt->rn_key = v;
        tt->rn_p = t;
        tt->rn_flags = t->rn_flags = RNF_ACTIVE;
        return t;
}

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;
        struct radix_node *t, *tt;
        int off = top->rn_off;
        int b;

        t = rn_search(v_arg, top);
        /*
         * Find first bit at which v and t->rn_key differ
         */
    {
        caddr_t cp, cp2, cplim;
        int vlen, cmp_res;

        vlen =  SALEN(v);
        cp = v + off;
        cp2 = t->rn_key + off;
        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;
        caddr_t cp = v;
        do {
                p = x;
                if (cp[x->rn_off] & x->rn_bmask)
                        x = x->rn_r;
                else
                        x = x->rn_l;
        } while (b > (unsigned int) x->rn_b); /* x->rn_b < b && x->rn_b >= 0 */
        t = rn_newpair(v_arg, b, nodes);
        tt = t->rn_l;
        if ((cp[p->rn_off] & p->rn_bmask) == 0)
                p->rn_l = t;
        else
                p->rn_r = t;
        x->rn_p = t;
        t->rn_p = p; /* frees x, p as temp vars below */
        if ((cp[t->rn_off] & t->rn_bmask) == 0) {
                t->rn_r = x;
        } else {
                t->rn_r = tt;
                t->rn_l = x;
        }
    }
        return (tt);
}

struct radix_node *
rn_addmask(void *n_arg, int search, int skip)
{
        caddr_t netmask = n_arg;
        struct radix_node *tm, *saved_tm;
        caddr_t cp, cplim;
        int b = 0, mlen, j;
        int maskduplicated, m0, isnormal;
        char addmask_key[KEYLEN_LIMIT];

        if ((mlen = SALEN(netmask)) > max_keylen)
                mlen = max_keylen;
        if (skip == 0)
                skip = 1;
        if (mlen <= skip)
                return (mask_rnhead->rnh_nodes);        /* rn_zero root node */
        if (skip > 1)
                memcpy(addmask_key + 1, rn_ones + 1, skip - 1);
        if ((m0 = mlen) > skip)
                memcpy(addmask_key + skip, netmask + skip, mlen - skip);
        /*
         * Trim trailing zeroes.
         */
        for (cp = addmask_key + mlen; (cp > addmask_key) && cp[-1] == 0;)
                cp--;
        mlen = cp - addmask_key;
        if (mlen <= skip)
                return (mask_rnhead->rnh_nodes);
        memset(addmask_key + m0, 0, max_keylen - m0);
        SALEN(addmask_key) = mlen;
        tm = rn_search(addmask_key, mask_rnhead->rnh_treetop);
        if (memcmp(addmask_key, tm->rn_key, mlen) != 0)
                tm = NULL;
        if (tm || search)
                return (tm);
        tm = malloc(max_keylen + 2 * sizeof(*tm), M_RTABLE, M_NOWAIT | M_ZERO);
        if (tm == NULL)
                return (0);
        saved_tm = tm;
        netmask = cp = (caddr_t)(tm + 2);
        memcpy(cp, addmask_key, mlen);
        tm = rn_insert(cp, mask_rnhead, &maskduplicated, tm);
        if (maskduplicated) {
                log(LOG_ERR, "%s: mask impossibly already in tree\n", __func__);
                free(saved_tm, M_RTABLE, max_keylen + 2 * sizeof(*saved_tm));
                return (tm);
        }
        /*
         * 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) {
                static const char normal_chars[] = {
                        0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, -1
                };
                for (j = 0x80; (j & *cp) != 0; j >>= 1)
                        b++;
                if (*cp != normal_chars[b] || cp != (cplim - 1))
                        isnormal = 0;
        }
        b += (cp - netmask) << 3;
        tm->rn_b = -1 - b;
        if (isnormal)
                tm->rn_flags |= RNF_NORMAL;
        return (tm);
}

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

        /*
         * Longer masks might not really be lexicographically better,
         * but longer masks always have precedence since they must be checked
         * first. The netmasks were normalized before calling this function and
         * don't have unneeded trailing zeros.
         */
        if (SALEN(mp) > SALEN(np))
                return 1;
        if (SALEN(mp) < SALEN(np))
                return 0;
        /*
         * Must return the first difference between the masks
         * to ensure deterministic sorting.
         */
        return (memcmp(mp, np, *mp) > 0);
}

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

        m = pool_get(&rtmask_pool, PR_NOWAIT | PR_ZERO);
        if (m == NULL) {
                log(LOG_ERR, "Mask for route not entered\n");
                return (0);
        }
        m->rm_b = tt->rn_b;
        m->rm_flags = tt->rn_flags;
        if (tt->rn_flags & RNF_NORMAL)
                m->rm_leaf = tt;
        else
                m->rm_mask = tt->rn_mask;
        m->rm_mklist = next;
        tt->rn_mklist = m;
        return m;
}

/*
 * Find the point where the rn_mklist needs to be changed.
 */
static inline struct radix_node *
rn_lift_node(struct radix_node *t)
{
        struct radix_node *x = t;
        int b = -1 - t->rn_b;

        /* rewind possible dupedkey list to head */
        while (t->rn_b < 0)
                t = t->rn_p;

        /* can't lift node above head of dupedkey list, give up */
        if (b > t->rn_b)
                return (NULL);

        do {
                x = t;
                t = t->rn_p;
        } while (b <= t->rn_b && x != t);

        return (x);
}

void
rn_add_radix_mask(struct radix_node *tt, int keyduplicated)
{
        caddr_t netmask, mmask;
        struct radix_node *x;
        struct radix_mask *m, **mp;
        int b_leaf = tt->rn_b;

        /* Add new route to highest possible ancestor's list */
        if (tt->rn_mask == NULL)
                return; /* can't lift at all */
        x = rn_lift_node(tt);
        if (x == NULL)
                return; /* didn't lift either */

        /*
         * 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.
         */
        netmask = tt->rn_mask;
        for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist) {
                if (m->rm_b < b_leaf)
                        continue;
                if (m->rm_b > b_leaf)
                        break;
                if (m->rm_flags & RNF_NORMAL) {
                        if (keyduplicated) {
                                if (m->rm_leaf->rn_p == tt)
                                        /* new route is better */
                                        m->rm_leaf = tt;
#ifdef DIAGNOSTIC
                                else {
                                        struct radix_node *t;

                                        for (t = m->rm_leaf;
                                            t && t->rn_mklist == m;
                                            t = t->rn_dupedkey)
                                                if (t == tt)
                                                        break;
                                        if (t == NULL) {
                                                log(LOG_ERR, "Non-unique "
                                                    "normal route on dupedkey, "
                                                    "mask not entered\n");
                                                return;
                                        }
                                }
#endif
                                m->rm_refs++;
                                tt->rn_mklist = m;
                                return;
                        } else if (tt->rn_flags & RNF_NORMAL) {
                                log(LOG_ERR, "Non-unique normal route,"
                                    " mask not entered\n");
                                return;
                        }
                        mmask = m->rm_leaf->rn_mask;
                } else
                        mmask = m->rm_mask;
                if (mmask == netmask) {
                        m->rm_refs++;
                        tt->rn_mklist = m;
                        return;
                }
                if (rn_refines(netmask, mmask) || rn_lexobetter(netmask, mmask))
                        break;
        }
        *mp = rn_new_radix_mask(tt, *mp);
}

int
rn_add_dupedkey(struct radix_node *saved_tt, struct radix_node_head *head,
    struct radix_node *tt, u_int8_t prio)
{
        caddr_t netmask = tt->rn_mask;
        struct radix_node *x = saved_tt, *xp;
        int before = -1;
        int b_leaf = 0;

        if (netmask)
                b_leaf = tt->rn_b;

        for (xp = x; x; xp = x, x = x->rn_dupedkey) {
                if (x->rn_mask == netmask)
                        return (-1);
                if (netmask == NULL ||
                    (x->rn_mask &&
                     ((b_leaf < x->rn_b) || /* index(netmask) > node */
                       rn_refines(netmask, x->rn_mask) ||
                       rn_lexobetter(netmask, x->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 ((x == saved_tt && before) || before == 1)
                before = 1;
        else
                before = 0;
        rn_link_dupedkey(tt, xp, before);

        return (0);
}

/*
 * Insert tt after x or in place of x if before is true.
 */
void
rn_link_dupedkey(struct radix_node *tt, struct radix_node *x, int before)
{
        if (before) {
                if (x->rn_p->rn_b > 0) {
                        /* link in at head of list */
                        tt->rn_dupedkey = x;
                        tt->rn_flags = x->rn_flags;
                        tt->rn_p = x->rn_p;
                        x->rn_p = tt;
                        if (tt->rn_p->rn_l == x)
                                tt->rn_p->rn_l = tt;
                        else
                                tt->rn_p->rn_r = tt;
                } else {
                        tt->rn_dupedkey = x;
                        x->rn_p->rn_dupedkey = tt;
                        tt->rn_p = x->rn_p;
                        x->rn_p = tt;
                }
        } else {
                tt->rn_dupedkey = x->rn_dupedkey;
                x->rn_dupedkey = tt;
                tt->rn_p = x;
                if (tt->rn_dupedkey)
                        tt->rn_dupedkey->rn_p = tt;
        }
}

/*
 * This function ensures that routes are properly promoted upwards.
 * It adjusts the rn_mklist of the parent node to make sure overlapping
 * routes can be found.
 *
 * There are two cases:
 * - leaf nodes with possible rn_dupedkey list
 * - internal nodes with maybe their own mklist
 * If the mask of the route is bigger than the current branch bit then
 * a rn_mklist entry needs to be made.
 */
void
rn_fixup_nodes(struct radix_node *tt)
{
        struct radix_node *tp, *x;
        struct radix_mask *m, **mp;
        int b_leaf;

        tp = tt->rn_p;
        if (tp->rn_r == tt)
                x = tp->rn_l;
        else
                x = tp->rn_r;

        b_leaf = -1 - tp->rn_b;
        if (x->rn_b < 0) {      /* x is a leaf node */
                struct  radix_node *xx = NULL;

                for (mp = &tp->rn_mklist; x; xx = x, x = x->rn_dupedkey) {
                        if (xx && xx->rn_mklist && xx->rn_mask == x->rn_mask &&
                            x->rn_mklist == 0) {
                                /* multipath route */
                                x->rn_mklist = xx->rn_mklist;
                                x->rn_mklist->rm_refs++;
                        }
                        if (x->rn_mask && (x->rn_b >= 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) {      /* x is an internal node */
                /*
                 * Skip over masks whose index is > that of new node
                 */
                for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist)
                        if (m->rm_b >= b_leaf)
                                break;
                tp->rn_mklist = m;
                *mp = 0;
        }
}

struct radix_node *
rn_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
    struct radix_node treenodes[2], u_int8_t prio)
{
        caddr_t v = v_arg;
        struct radix_node *top = head->rnh_treetop;
        struct radix_node *tt, *saved_tt, *tm = NULL;
        int keyduplicated;

        /*
         * 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 (n_arg)  {
                if ((tm = rn_addmask(n_arg, 0, top->rn_off)) == 0)
                        return (0);
        }

        tt = rn_insert(v, head, &keyduplicated, treenodes);

        if (keyduplicated) {
                saved_tt = tt;
                tt = treenodes;

                tt->rn_key = v_arg;
                tt->rn_b = -1;
                tt->rn_flags = RNF_ACTIVE;
        }

        /* Put mask into the node. */
        if (tm) {
                tt->rn_mask = tm->rn_key;
                tt->rn_b = tm->rn_b;
                tt->rn_flags |= tm->rn_flags & RNF_NORMAL;
        }

        /* Either insert into dupedkey list or as a leaf node.  */
        if (keyduplicated) {
                if (rn_add_dupedkey(saved_tt, head, tt, prio))
                        return (NULL);
        } else {
                rn_fixup_nodes(tt);
        }

        /* finally insert a radix_mask element if needed */
        rn_add_radix_mask(tt, keyduplicated);
        return (tt);
}

/*
 * Cleanup mask list, tt points to route that needs to be cleaned
 */
int
rn_del_radix_mask(struct radix_node *tt)
{
        struct radix_node *x;
        struct radix_mask *m, *saved_m, **mp;

        /*
         * Cleanup mask list from possible references to this route.
         */
        saved_m = m = tt->rn_mklist;
        if (tt->rn_mask == NULL || m == NULL)
                return (0);

        if (tt->rn_flags & RNF_NORMAL) {
                if (m->rm_leaf != tt && m->rm_refs == 0) {
                        log(LOG_ERR, "rn_delete: inconsistent normal "
                            "annotation\n");
                        return (-1);
                }
                if (m->rm_leaf != tt) {
                        if (--m->rm_refs >= 0)
                                return (0);
                        else
                                log(LOG_ERR, "rn_delete: "
                                    "inconsistent mklist refcount\n");
                }
                /*
                 * If we end up here tt should be m->rm_leaf and therefore
                 * tt should be the head of a multipath chain.
                 * If this is not the case the table is no longer consistent.
                 */
                if (m->rm_refs > 0) {
                        if (tt->rn_dupedkey == NULL ||
                            tt->rn_dupedkey->rn_mklist != m) {
                                log(LOG_ERR, "rn_delete: inconsistent "
                                    "dupedkey list\n");
                                return (-1);
                        }
                        m->rm_leaf = tt->rn_dupedkey;
                        --m->rm_refs;
                        return (0);
                }
                /* else tt is last and only route */
        } else {
                if (m->rm_mask != tt->rn_mask) {
                        log(LOG_ERR, "rn_delete: inconsistent annotation\n");
                        return (0);
                }
                if (--m->rm_refs >= 0)
                        return (0);
        }

        /*
         * No other references hold to the radix_mask remove it from
         * the tree.
         */
        x = rn_lift_node(tt);
        if (x == NULL)
                return (0);     /* Wasn't lifted at all */

        /* Finally eliminate the radix_mask from the tree */
        for (mp = &x->rn_mklist; (m = *mp); mp = &m->rm_mklist)
                if (m == saved_m) {
                        *mp = m->rm_mklist;
                        pool_put(&rtmask_pool, m);
                        break;
                }

        if (m == NULL) {
                log(LOG_ERR, "rn_delete: couldn't find our annotation\n");
                if (tt->rn_flags & RNF_NORMAL)
                        return (-1); /* Dangling ref to us */
        }

        return (0);
}

/* swap two internal nodes and fixup the parent and child pointers */
static inline void
rn_swap_nodes(struct radix_node *from, struct radix_node *to)
{
        *to = *from;
        if (from->rn_p->rn_l == from)
                from->rn_p->rn_l = to;
        else
                from->rn_p->rn_r = to;

        to->rn_l->rn_p = to;
        to->rn_r->rn_p = to;
}

struct radix_node *
rn_delete(void *v_arg, void *n_arg, struct radix_node_head *head,
    struct radix_node *rn)
{
        caddr_t v = v_arg;
        caddr_t netmask = n_arg;
        struct radix_node *top = head->rnh_treetop;
        struct radix_node *tt, *tp, *pp, *x;
        struct radix_node *dupedkey_tt, *saved_tt;
        int off = top->rn_off;
        int vlen;

        vlen = SALEN(v);

        /*
         * Implement a lookup similar to rn_lookup but we need to save
         * the radix leaf node (where th rn_dupedkey list starts) so
         * it is not possible to use rn_lookup.
         */
        tt = rn_search(v, top);
        /* make sure the key is a perfect match */
        if (memcmp(v + off, tt->rn_key + off, vlen - off))
                return (NULL);

        /*
         * Here, tt is the deletion target, and
         * saved_tt is the head of the dupedkey chain.
         * dupedkey_tt will point to the start of the multipath chain.
         */
        saved_tt = tt;

        /*
         * make tt point to the start of the rn_dupedkey list of multipath
         * routes.
         */
        if (netmask) {
                struct radix_node *tm;

                if ((tm = rn_addmask(netmask, 1, off)) == NULL)
                        return (NULL);
                netmask = tm->rn_key;
                while (tt->rn_mask != netmask)
                        if ((tt = tt->rn_dupedkey) == NULL)
                                return (NULL);
        }

        /* save start of multi path chain for later use */
        dupedkey_tt = tt;

        KASSERT((tt->rn_flags & RNF_ROOT) == 0);

        /* remove possible radix_mask */
        if (rn_del_radix_mask(tt))
                return (NULL);

        /*
         * Finally eliminate us from tree
         */
        tp = tt->rn_p;
        if (saved_tt->rn_dupedkey) {
                if (tt == saved_tt) {
                        x = saved_tt->rn_dupedkey;
                        x->rn_p = tp;
                        if (tp->rn_l == tt)
                                tp->rn_l = x;
                        else
                                tp->rn_r = x;
                        /* head changed adjust dupedkey pointer */
                        dupedkey_tt = x;
                } else {
                        x = saved_tt;
                        /* dupedkey will change so adjust pointer */
                        if (dupedkey_tt == tt)
                                dupedkey_tt = tt->rn_dupedkey;
                        tp->rn_dupedkey = tt->rn_dupedkey;
                        if (tt->rn_dupedkey)
                                tt->rn_dupedkey->rn_p = tp;
                }

                /*
                 * We may be holding an active internal node in the tree.
                 */
                if  (tt[1].rn_flags & RNF_ACTIVE)
                        rn_swap_nodes(&tt[1], &x[1]);

                /* over and out */
                goto out;
        }

        /* non-rn_dupedkey case, remove tt and tp node from the tree */
        if (tp->rn_l == tt)
                x = tp->rn_r;
        else
                x = tp->rn_l;
        pp = tp->rn_p;
        if (pp->rn_r == tp)
                pp->rn_r = x;
        else
                pp->rn_l = x;
        x->rn_p = pp;

        /*
         * Demote routes attached to us (actually on the internal parent node).
         */
        if (tp->rn_mklist) {
                struct radix_mask *m, **mp;
                if (x->rn_b >= 0) {
                        for (mp = &x->rn_mklist; (m = *mp);)
                                mp = &m->rm_mklist;
                        *mp = tp->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 = tp->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)
                                                pool_put(&rtmask_pool, m);
                                        else if (m->rm_flags & RNF_NORMAL)
                                                /*
                                                 * don't progress because this
                                                 * a multipath route. Next
                                                 * route will use the same m.
                                                 */
                                                mm = m;
                                        m = mm;
                                }
                        if (m)
                                log(LOG_ERR, "%s %p at %p\n",
                                    "rn_delete: Orphaned Mask", m, x);
                }
        }

        /*
         * We may be holding an active internal node in the tree.
         * If so swap our internal node (t) with the parent node (tp)
         * since that one was just removed from the tree.
         */
        if (tp != &tt[1])
                rn_swap_nodes(&tt[1], tp);

        /* no rn_dupedkey list so no need to fixup multipath chains */
out:
        tt[0].rn_flags &= ~RNF_ACTIVE;
        tt[1].rn_flags &= ~RNF_ACTIVE;
        return (tt);
}

int
rn_walktree(struct radix_node_head *h, int (*f)(struct radix_node *, void *,
    u_int), void *w)
{
        int error;
        struct radix_node *base, *next;
        struct radix_node *rn = h->rnh_treetop;

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

int
rn_initmask(void)
{
        if (mask_rnhead != NULL)
                return (0);

        KASSERT(max_keylen > 0);

        mask_rnhead = malloc(sizeof(*mask_rnhead), M_RTABLE, M_NOWAIT);
        if (mask_rnhead == NULL)
                return (1);

        rn_inithead0(mask_rnhead, 0);
        return (0);
}

int
rn_inithead(void **head, int off)
{
        struct radix_node_head *rnh;

        if (*head != NULL)
                return (1);

        if (rn_initmask())
                panic("failed to initialize the mask tree");

        rnh = malloc(sizeof(*rnh), M_RTABLE, M_NOWAIT);
        if (rnh == NULL)
                return (0);
        *head = rnh;
        rn_inithead0(rnh, off);
        return (1);
}

int
rn_inithead0(struct radix_node_head *rnh, int offset)
{
        struct radix_node *t, *tt, *ttt;
        int off = offset * NBBY;

        memset(rnh, 0, sizeof(*rnh));
        t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
        ttt = rnh->rnh_nodes + 2;
        t->rn_r = ttt;
        t->rn_p = t;
        tt = t->rn_l;
        tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
        tt->rn_b = -1 - off;
        *ttt = *tt;
        ttt->rn_key = rn_ones;
        rnh->rnh_treetop = t;
        return (1);
}

/*
 * rn_init() can be called multiple time with a different key length
 * as long as no radix tree head has been allocated.
 */
void
rn_init(unsigned int keylen)
{
        char *cp, *cplim;

        KASSERT(keylen <= KEYLEN_LIMIT);

        if (max_keylen == 0) {
                pool_init(&rtmask_pool, sizeof(struct radix_mask), 0,
                    IPL_SOFTNET, 0, "rtmask", NULL);
        }

        if (keylen <= max_keylen)
                return;

        KASSERT(mask_rnhead == NULL);

        free(rn_zeros, M_RTABLE, 2 * max_keylen);
        rn_zeros = mallocarray(2, keylen, M_RTABLE, M_NOWAIT | M_ZERO);
        if (rn_zeros == NULL)
                panic("cannot initialize a radix tree without memory");
        max_keylen = keylen;

        cp = rn_ones = rn_zeros + max_keylen;
        cplim = rn_ones + max_keylen;
        while (cp < cplim)
                *cp++ = -1;
}