/*      $NetBSD: radix.c,v 1.49 2020/10/18 13:07:31 gson 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: radix.c,v 1.49 2020/10/18 13:07:31 gson Exp $");

#ifndef _NET_RADIX_H_
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/kmem.h>
#ifdef  _KERNEL
#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#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

typedef void (*rn_printer_t)(void *, const char *fmt, ...);

int     max_keylen;
struct radix_mask *rn_mkfreelist;
struct radix_node_head *mask_rnhead;
static char *addmask_key;
static const 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_satisfies_leaf(const char *, struct radix_node *, int);
static int rn_lexobetter(const void *, const void *);
static struct radix_mask *rn_new_radix_mask(struct radix_node *,
    struct radix_mask *);
static struct radix_node *rn_walknext(struct radix_node *, rn_printer_t,
    void *);
static struct radix_node *rn_walkfirst(struct radix_node *, rn_printer_t,
    void *);
static void rn_nodeprint(struct radix_node *, rn_printer_t, void *,
    const char *);

#define SUBTREE_OPEN    "[ "
#define SUBTREE_CLOSE   " ]"

#ifdef RN_DEBUG
static void rn_treeprint(struct radix_node_head *, rn_printer_t, void *);
#endif /* RN_DEBUG */

/*
 * 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.
 */

struct radix_node *
rn_search(
        const void *v_arg,
        struct radix_node *head)
{
        const u_char * const v = v_arg;
        struct radix_node *x;

        for (x = head; 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(
        const void *v_arg,
        struct radix_node *head,
        const void *m_arg)
{
        struct radix_node *x;
        const u_char * const v = v_arg;
        const u_char * const m = m_arg;

        for (x = head; 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(
        const void *m_arg,
        const void *n_arg)
{
        const char *m = m_arg;
        const char *n = n_arg;
        const char *lim = n + *(const u_char *)n;
        const char *lim2 = lim;
        int longer = (*(const u_char *)n++) - (int)(*(const 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(
        const void *v_arg,
        const void *m_arg,
        struct radix_node_head *head)
{
        struct radix_node *x;
        const char *netmask = NULL;

        if (m_arg) {
                if ((x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_off)) == 0)
                        return NULL;
                netmask = x->rn_key;
        }
        x = rn_match(v_arg, head);
        if (x != NULL && netmask != NULL) {
                while (x != NULL && x->rn_mask != netmask)
                        x = x->rn_dupedkey;
        }
        return x;
}

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

        if (cp3 == 0)
                cp3 = rn_ones;
        else
                length = uimin(length, *(const 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(
        const void *v_arg,
        struct radix_node_head *head)
{
        const char * const v = v_arg;
        struct radix_node *t = head->rnh_treetop;
        struct radix_node *top = t;
        struct radix_node *x;
        struct radix_node *saved_t;
        const char *cp = v;
        const char *cp2;
        const char *cplim;
        int off = t->rn_off;
        int vlen = *(const u_char *)cp;
        int matched_off;
        int test, b, rn_b;

        /*
         * Open code rn_search(v, top) to avoid overhead of extra
         * subroutine call.
         */
        for (; t->rn_b >= 0; ) {
                if (t->rn_bmask & cp[t->rn_off])
                        t = t->rn_r;
                else
                        t = t->rn_l;
        }
        /*
         * 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 = *(const 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!
         */
        if ((t->rn_flags & RNF_ROOT) && t->rn_dupedkey)
                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_b = -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_b <= t->rn_b)
                                return t;
                } else if (rn_satisfies_leaf(v, t, matched_off))
                                return t;
        t = saved_t;
        /* start searching up the tree */
        do {
                struct radix_mask *m;
                t = t->rn_p;
                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_b <= m->rm_b)
                                                return m->rm_leaf;
                                } else {
                                        off = uimin(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))
                                                return x;
                                }
                                m = m->rm_mklist;
                        } while (m);
                }
        } while (t != top);
        return NULL;
}

static void
rn_nodeprint(struct radix_node *rn, rn_printer_t printer, void *arg,
    const char *delim)
{
        (*printer)(arg, "%s(%s%p: p<%p> l<%p> r<%p>)",
            delim, ((void *)rn == arg) ? "*" : "", rn, rn->rn_p,
            rn->rn_l, rn->rn_r);
}

#ifdef RN_DEBUG
int     rn_debug =  1;

static void
rn_dbg_print(void *arg, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vlog(LOG_DEBUG, fmt, ap);
        va_end(ap);
}

static void
rn_treeprint(struct radix_node_head *h, rn_printer_t printer, void *arg)
{
        struct radix_node *dup, *rn;
        const char *delim;

        if (printer == NULL)
                return;

        rn = rn_walkfirst(h->rnh_treetop, printer, arg);
        for (;;) {
                /* Process leaves */
                delim = "";
                for (dup = rn; dup != NULL; dup = dup->rn_dupedkey) {
                        if ((dup->rn_flags & RNF_ROOT) != 0)
                                continue;
                        rn_nodeprint(dup, printer, arg, delim);
                        delim = ", ";
                }
                rn = rn_walknext(rn, printer, arg);
                if (rn->rn_flags & RNF_ROOT)
                        return;
        }
        /* NOTREACHED */
}

#define traverse(__head, __rn)  rn_treeprint((__head), rn_dbg_print, (__rn))
#endif /* RN_DEBUG */

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

struct radix_node *
rn_insert(
        const void *v_arg,
        struct radix_node_head *head,
        int *dupentry,
        struct radix_node nodes[2])
{
        struct radix_node *top = head->rnh_treetop;
        struct radix_node *t = rn_search(v_arg, top);
        struct radix_node *tt;
        const char *v = v_arg;
        int head_off = top->rn_off;
        int vlen = *((const u_char *)v);
        const char *cp = v + head_off;
        int b;
        /*
         * Find first bit at which v and t->rn_key differ
         */
    {
        const char *cp2 = t->rn_key + head_off;
        const char *cplim = v + vlen;
        int cmp_res;

        while (cp < cplim)
                if (*cp2++ != *cp++)
                        goto on1;
        *dupentry = 1;
        return t;
on1:
        *dupentry = 0;
        cmp_res = (cp[-1] ^ cp2[-1]) & 0xff;
        for (b = (cp - v) << 3; cmp_res; b--)
                cmp_res >>= 1;
    }
    {
        struct radix_node *p, *x = top;
        cp = v;
        do {
                p = x;
                if (cp[x->rn_off] & x->rn_bmask)
                        x = x->rn_r;
                else x = x->rn_l;
        } while (b > (unsigned) x->rn_b); /* x->rn_b < b && x->rn_b >= 0 */
#ifdef RN_DEBUG
        if (rn_debug)
                log(LOG_DEBUG, "%s: Going In:\n", __func__), traverse(head, p);
#endif
        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;
        }
#ifdef RN_DEBUG
        if (rn_debug) {
                log(LOG_DEBUG, "%s: Coming Out:\n", __func__),
                    traverse(head, p);
        }
#endif /* RN_DEBUG */
    }
        return tt;
}

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

        if ((mlen = *(const u_char *)netmask) > max_keylen)
                mlen = max_keylen;
        if (skip == 0)
                skip = 1;
        if (mlen <= skip)
                return mask_rnhead->rnh_nodes;
        if (skip > 1)
                memmove(addmask_key + 1, rn_ones + 1, skip - 1);
        if ((m0 = mlen) > skip)
                memmove(addmask_key + skip, netmask + skip, mlen - skip);
        /*
         * Trim trailing zeroes.
         */
        for (cp = addmask_key + mlen; (cp > addmask_key) && cp[-1] == 0;)
                cp--;
        mlen = cp - addmask_key;
        if (mlen <= skip) {
                if (m0 >= last_zeroed)
                        last_zeroed = mlen;
                return mask_rnhead->rnh_nodes;
        }
        if (m0 < last_zeroed)
                memset(addmask_key + m0, 0, last_zeroed - m0);
        *addmask_key = last_zeroed = mlen;
        x = rn_search(addmask_key, rn_masktop);
        if (memcmp(addmask_key, x->rn_key, mlen) != 0)
                x = 0;
        if (x || search)
                return x;
        R_Malloc(x, struct radix_node *, max_keylen + 2 * sizeof (*x));
        if ((saved_x = x) == NULL)
                return NULL;
        memset(x, 0, max_keylen + 2 * sizeof (*x));
        cp = netmask = (void *)(x + 2);
        memmove(x + 2, addmask_key, mlen);
        x = rn_insert(cp, mask_rnhead, &maskduplicated, x);
        if (maskduplicated) {
                log(LOG_ERR, "rn_addmask: mask impossibly already in tree\n");
                Free(saved_x);
                return x;
        }
        /*
         * Calculate index of mask, and check for normalcy.
         */
        cplim = netmask + mlen; isnormal = 1;
        for (cp = netmask + skip; (cp < cplim) && *(const 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_b = -1 - b;
        if (isnormal)
                x->rn_flags |= RNF_NORMAL;
        return x;
}

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

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

struct radix_node *
rn_addroute(
        const void *v_arg,
        const void *n_arg,
        struct radix_node_head *head,
        struct radix_node treenodes[2])
{
        const char *v = v_arg, *netmask = n_arg;
        struct radix_node *t, *x = NULL, *tt;
        struct radix_node *saved_tt, *top = head->rnh_treetop;
        short b = 0, b_leaf = 0;
        int keyduplicated;
        const 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, 0, top->rn_off)) == NULL)
                        return NULL;
                b_leaf = x->rn_b;
                b = -1 - x->rn_b;
                netmask = x->rn_key;
        }
        /*
         * Deal with duplicated keys: attach node to previous instance
         */
        saved_tt = tt = rn_insert(v, head, &keyduplicated, treenodes);
        if (keyduplicated) {
                for (t = tt; tt != NULL; t = tt, tt = tt->rn_dupedkey) {
                        if (tt->rn_mask == netmask)
                                return NULL;
                        if (netmask == NULL ||
                            (tt->rn_mask != NULL &&
                             (b_leaf < tt->rn_b || /* 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_p = x = t->rn_p;
                        t->rn_p = tt;
                        if (x->rn_l == t)
                                x->rn_l = tt;
                        else
                                x->rn_r = tt;
                        saved_tt = tt;
                        x = xx;
                } else {
                        (tt = treenodes)->rn_dupedkey = t->rn_dupedkey;
                        t->rn_dupedkey = tt;
                        tt->rn_p = t;
                        if (tt->rn_dupedkey)
                                tt->rn_dupedkey->rn_p = tt;
                }
                tt->rn_key = v;
                tt->rn_b = -1;
                tt->rn_flags = RNF_ACTIVE;
        }
        /*
         * Put mask in tree.
         */
        if (netmask != NULL) {
                tt->rn_mask = netmask;
                tt->rn_b = x->rn_b;
                tt->rn_flags |= x->rn_flags & RNF_NORMAL;
        }
        t = saved_tt->rn_p;
        if (keyduplicated)
                goto on2;
        b_leaf = -1 - t->rn_b;
        if (t->rn_r == saved_tt)
                x = t->rn_l;
        else
                x = t->rn_r;
        /* Promote general routes from below */
        if (x->rn_b < 0) {
                for (mp = &t->rn_mklist; x != NULL; x = x->rn_dupedkey) {
                        if (x->rn_mask != NULL && x->rn_b >= b_leaf &&
                            x->rn_mklist == NULL) {
                                *mp = m = rn_new_radix_mask(x, NULL);
                                if (m != NULL)
                                        mp = &m->rm_mklist;
                        }
                }
        } else if (x->rn_mklist != NULL) {
                /*
                 * Skip over masks whose index is > that of new node
                 */
                for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist)
                        if (m->rm_b >= b_leaf)
                                break;
                t->rn_mklist = m;
                *mp = NULL;
        }
on2:
        /* Add new route to highest possible ancestor's list */
        if (netmask == NULL || b > t->rn_b)
                return tt; /* can't lift at all */
        b_leaf = tt->rn_b;
        do {
                x = t;
                t = t->rn_p;
        } while (b <= t->rn_b && x != top);
        /*
         * Search through routes associated with node to
         * insert new route according to index.
         * Need same criteria as when sorting dupedkeys to avoid
         * double loop on deletion.
         */
        for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist) {
                if (m->rm_b < b_leaf)
                        continue;
                if (m->rm_b > b_leaf)
                        break;
                if (m->rm_flags & RNF_NORMAL) {
                        mmask = m->rm_leaf->rn_mask;
                        if (tt->rn_flags & RNF_NORMAL) {
                                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_delete1(
        const void *v_arg,
        const void *netmask_arg,
        struct radix_node_head *head,
        struct radix_node *rn)
{
        struct radix_node *t, *p, *x, *tt;
        struct radix_mask *m, *saved_m, **mp;
        struct radix_node *dupedkey, *saved_tt, *top;
        const char *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_off;
        vlen =  *(const u_char *)v;
        saved_tt = tt;
        top = x;
        if (tt == NULL ||
            memcmp(v + head_off, tt->rn_key + head_off, vlen - head_off) != 0)
                return NULL;
        /*
         * Delete our route from mask lists.
         */
        if (netmask != NULL) {
                if ((x = rn_addmask(netmask, 1, 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_b;
        t = saved_tt->rn_p;
        if (b > t->rn_b)
                goto on1; /* Wasn't lifted at all */
        do {
                x = t;
                t = t->rn_p;
        } while (b <= t->rn_b && x != top);
        for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist) {
                if (m == saved_m) {
                        *mp = m->rm_mklist;
                        MKFree(m);
                        break;
                }
        }
        if (m == NULL) {
                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
        if (rn_debug)
                log(LOG_DEBUG, "%s: Going In:\n", __func__), traverse(head, tt);
#endif
        t = tt->rn_p;
        dupedkey = saved_tt->rn_dupedkey;
        if (dupedkey != NULL) {
                /*
                 * Here, tt is the deletion target, and
                 * saved_tt is the head of the dupedkey chain.
                 */
                if (tt == saved_tt) {
                        x = dupedkey;
                        x->rn_p = t;
                        if (t->rn_l == tt)
                                t->rn_l = x;
                        else
                                t->rn_r = x;
                } else {
                        /* find node in front of tt on the chain */
                        for (x = p = saved_tt;
                             p != NULL && p->rn_dupedkey != tt;)
                                p = p->rn_dupedkey;
                        if (p != NULL) {
                                p->rn_dupedkey = tt->rn_dupedkey;
                                if (tt->rn_dupedkey != NULL)
                                        tt->rn_dupedkey->rn_p = p;
                        } else
                                log(LOG_ERR, "rn_delete: couldn't find us\n");
                }
                t = tt + 1;
                if  (t->rn_flags & RNF_ACTIVE) {
                        *++x = *t;
                        p = t->rn_p;
                        if (p->rn_l == t)
                                p->rn_l = x;
                        else
                                p->rn_r = x;
                        x->rn_l->rn_p = x;
                        x->rn_r->rn_p = x;
                }
                goto out;
        }
        if (t->rn_l == tt)
                x = t->rn_r;
        else
                x = t->rn_l;
        p = t->rn_p;
        if (p->rn_r == t)
                p->rn_r = x;
        else
                p->rn_l = x;
        x->rn_p = p;
        /*
         * Demote routes attached to us.
         */
        if (t->rn_mklist == NULL)
                ;
        else if (x->rn_b >= 0) {
                for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_mklist)
                        ;
                *mp = t->rn_mklist;
        } else {
                /* If there are any key,mask pairs in a sibling
                   duped-key chain, some subset will appear sorted
                   in the same order attached to our mklist */
                for (m = t->rn_mklist;
                     m != NULL && x != NULL;
                     x = x->rn_dupedkey) {
                        if (m == x->rn_mklist) {
                                struct radix_mask *mm = m->rm_mklist;
                                x->rn_mklist = NULL;
                                if (--(m->rm_refs) < 0)
                                        MKFree(m);
                                m = mm;
                        }
                }
                if (m != NULL) {
                        log(LOG_ERR, "rn_delete: Orphaned Mask %p at %p\n",
                            m, x);
                }
        }
        /*
         * We may be holding an active internal node in the tree.
         */
        x = tt + 1;
        if (t != x) {
                *t = *x;
                t->rn_l->rn_p = t;
                t->rn_r->rn_p = t;
                p = x->rn_p;
                if (p->rn_l == x)
                        p->rn_l = t;
                else
                        p->rn_r = t;
        }
out:
#ifdef RN_DEBUG
        if (rn_debug) {
                log(LOG_DEBUG, "%s: Coming Out:\n", __func__),
                    traverse(head, tt);
        }
#endif /* RN_DEBUG */
        tt->rn_flags &= ~RNF_ACTIVE;
        tt[1].rn_flags &= ~RNF_ACTIVE;
        return tt;
}

struct radix_node *
rn_delete(
        const void *v_arg,
        const void *netmask_arg,
        struct radix_node_head *head)
{
        return rn_delete1(v_arg, netmask_arg, head, NULL);
}

static struct radix_node *
rn_walknext(struct radix_node *rn, rn_printer_t printer, void *arg)
{
        /* If at right child go back up, otherwise, go right */
        while (rn->rn_p->rn_r == rn && (rn->rn_flags & RNF_ROOT) == 0) {
                if (printer != NULL)
                        (*printer)(arg, SUBTREE_CLOSE);
                rn = rn->rn_p;
        }
        if (printer)
                rn_nodeprint(rn->rn_p, printer, arg, "");
        /* Find the next *leaf* since next node might vanish, too */
        for (rn = rn->rn_p->rn_r; rn->rn_b >= 0;) {
                if (printer != NULL)
                        (*printer)(arg, SUBTREE_OPEN);
                rn = rn->rn_l;
        }
        return rn;
}

static struct radix_node *
rn_walkfirst(struct radix_node *rn, rn_printer_t printer, void *arg)
{
        /* First time through node, go left */
        while (rn->rn_b >= 0) {
                if (printer != NULL)
                        (*printer)(arg, SUBTREE_OPEN);
                rn = rn->rn_l;
        }
        return rn;
}

int
rn_walktree(
        struct radix_node_head *h,
        int (*f)(struct radix_node *, void *),
        void *w)
{
        int error;
        struct radix_node *base, *next, *rn;
        /*
         * 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.
         */
        rn = rn_walkfirst(h->rnh_treetop, NULL, NULL);
        for (;;) {
                base = rn;
                next = rn_walknext(rn, NULL, NULL);
                /* Process leaves */
                while ((rn = base) != NULL) {
                        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 */
}

struct radix_node *
rn_search_matched(struct radix_node_head *h,
    int (*matcher)(struct radix_node *, void *), void *w)
{
        bool matched;
        struct radix_node *base, *next, *rn;
        /*
         * 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.
         */
        rn = rn_walkfirst(h->rnh_treetop, NULL, NULL);
        for (;;) {
                base = rn;
                next = rn_walknext(rn, NULL, NULL);
                /* Process leaves */
                while ((rn = base) != NULL) {
                        base = rn->rn_dupedkey;
                        if (!(rn->rn_flags & RNF_ROOT)) {
                                matched = (*matcher)(rn, w);
                                if (matched)
                                        return rn;
                        }
                }
                rn = next;
                if (rn->rn_flags & RNF_ROOT)
                        return NULL;
        }
        /* NOTREACHED */
}

struct delayinit {
        void **head;
        int off;
        SLIST_ENTRY(delayinit) entries;
};
static SLIST_HEAD(, delayinit) delayinits = SLIST_HEAD_INITIALIZER(delayheads);
static int radix_initialized;

/*
 * Initialize a radix tree once radix is initialized.  Only for bootstrap.
 * Assume that no concurrency protection is necessary at this stage.
 */
void
rn_delayedinit(void **head, int off)
{
        struct delayinit *di;

        if (radix_initialized)
                return;

        di = kmem_alloc(sizeof(*di), KM_SLEEP);
        di->head = head;
        di->off = off;
        SLIST_INSERT_HEAD(&delayinits, di, entries);
}

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

        if (*head != NULL)
                return 1;
        R_Malloc(rnh, struct radix_node_head *, sizeof (*rnh));
        if (rnh == NULL)
                return 0;
        *head = rnh;
        return rn_inithead0(rnh, off);
}

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

        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_addaddr = rn_addroute;
        rnh->rnh_deladdr = rn_delete;
        rnh->rnh_matchaddr = rn_match;
        rnh->rnh_lookup = rn_lookup;
        rnh->rnh_treetop = t;
        return 1;
}

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

        if (radix_initialized)
                panic("radix already initialized");
        radix_initialized = 1;

        DOMAIN_FOREACH(dp) {
                if (dp->dom_maxrtkey > max_keylen)
                        max_keylen = dp->dom_maxrtkey;
        }
#endif
        if (max_keylen == 0) {
#ifndef _KERNEL
                log(LOG_ERR,
                    "rn_init: radix functions require max_keylen be set\n");
#endif
                return;
        }

        R_Malloc(rn_zeros, char *, 3 * max_keylen);
        if (rn_zeros == NULL)
                panic("rn_init");
        memset(rn_zeros, 0, 3 * max_keylen);
        rn_ones = cp = rn_zeros + max_keylen;
        addmask_key = cplim = rn_ones + max_keylen;
        while (cp < cplim)
                *cp++ = -1;
        if (rn_inithead((void *)&mask_rnhead, 0) == 0)
                panic("rn_init 2");

        while ((di = SLIST_FIRST(&delayinits)) != NULL) {
                if (!rn_inithead(di->head, di->off))
                        panic("delayed rn_inithead failed");
                SLIST_REMOVE_HEAD(&delayinits, entries);
                kmem_free(di, sizeof(*di));
        }
}