/*
 * 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     8.4 (Berkeley) 11/2/94
 * $FreeBSD: src/sys/net/radix.c,v 1.20.2.3 2002/04/28 05:40:25 suz Exp $
 */

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

#include <sys/param.h>
#ifdef  _KERNEL
#include <sys/systm.h>
#include <sys/domain.h>
#include <sys/globaldata.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/syslog.h>
#include <sys/thread.h>
#include <net/netisr2.h>
#include <net/netmsg2.h>
#else
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <syslog.h>
#endif
#include <net/radix.h>

#ifndef _KERNEL
#undef MAXCPU
#define MAXCPU                  1
#define mycpuid                 0
#define log(l, ...)             syslog(l, __VA_ARGS__)
#define kprintf(fmt, ...)       printf(fmt, ##__VA_ARGS__)
#define print_backtrace(...)    /* nothing */
#define panic(fmt, ...) \
        do { \
                fprintf(stderr, "PANIC: " fmt "\n", ##__VA_ARGS__); \
                abort(); \
        } while (0)
#endif

/*
 * 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.
 * Cast the result to int as this is the dominant usage.
 */
#define clen(c) (int)(*(const u_char *)(c))


static struct radix_mask *rn_mkfreelist[MAXCPU];
static struct radix_node_head *mask_rnheads[MAXCPU];

static const u_char rn_zeros[RN_MAXKEYLEN];
static const u_char rn_ones[RN_MAXKEYLEN] = RN_MAXKEYONES;

#ifdef RN_DEBUG
static int rn_nodenum;
static struct radix_node *rn_clist;
static bool rn_debug = true;
#endif


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 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 rn_bit 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.
 */

/*
 * Search key <key> in the subtree from <head> until encountering
 * a leaf node and return it.
 *
 * NOTE: Will never return NULL because the embedded default root node.
 */
static struct radix_node *
rn_search(const void *_key, struct radix_node *head)
{
        struct radix_node *x;
        const u_char *key;

        key = _key;
        x = head;
        while (x->rn_bit >= 0) {
                if (x->rn_bmask & key[x->rn_offset])
                        x = x->rn_right;
                else
                        x = x->rn_left;
        }
        return (x);
}

/*
 * Similar to rn_search() but with the netmask <mask> applied.
 *
 * NOTE: The netmask can be the all-zero default mask.
 */
static struct radix_node *
rn_search_m(const void *_key, const void *_mask, struct radix_node *head)
{
        struct radix_node *x;
        const u_char *key, *mask;

        key = _key;
        mask = _mask;
        x = head;
        while (x->rn_bit >= 0) {
                if ((x->rn_bmask & mask[x->rn_offset]) &&
                    (x->rn_bmask & key[x->rn_offset]))
                        x = x->rn_right;
                else
                        x = x->rn_left;
        }
        return (x);
}

/*
 * Compare the two netmasks and return true if netmask <m> is strictly more
 * specific than netmask <n>.
 *
 * NOTE: Non-contiguous netmask is supported.
 */
bool
rn_refines(const void *_m, const void *_n)
{
        const u_char *m, *n, *lim, *lim2;
        int longer;
        bool equal;

        m = _m;
        n = _n;
        lim2 = lim = n + clen(n);
        longer = clen(n++) - clen(m++);
        if (longer > 0)
                lim -= longer;

        equal = true;
        while (n < lim) {
                if (*n & ~(*m))
                        return (false);
                if (*n++ != *m++)
                        equal = false;
        }
        while (n < lim2) {
                if (*n++) /* n is longer and more specific */
                        return (false);
        }
        if (equal && (longer < 0)) {
                lim2 = m - longer;
                while (m < lim2) {
                        if (*m++) /* m is longer and more specific */
                                return (true);
                }
        }

        return (!equal);
}

/*
 * Lookup the longest-prefix match of the key <key> in the tree <head>.
 * The netmask <mask> can be NULL; if specified, the result must have the
 * same mask, or NULL is returned.
 */
struct radix_node *
rn_lookup(const void *_key, const void *_mask, struct radix_node_head *head)
{
        struct radix_node *x;
        const u_char *key, *mask, *netmask;

        key = _key;
        mask = _mask;
        netmask = NULL;

        if (mask != NULL) {
                x = rn_addmask(mask, true, head->rnh_treetop->rn_offset,
                               head->rnh_maskhead);
                if (x == NULL) /* mask doesn't exist in the mask tree */
                        return (NULL);
                netmask = x->rn_key;
        }

        x = rn_match(key, head);
        if (x != NULL && netmask != NULL) {
                /* check the duped-key chain for different masks */
                while (x != NULL && x->rn_mask != netmask)
                        x = x->rn_dupedkey;
        }

        return (x);
}

/*
 * Check whether the key <key> matches the (key, mask) of the given
 * radix node <leaf>.  The <skip> parameter gives the number of bytes
 * to skip for the keys and mask.
 */
static bool
rn_satisfies_leaf(const void *key, struct radix_node *leaf, int skip)
{
        const u_char *cp, *cp2, *cp3, *cplim;
        int length;

        cp = key;
        cp2 = leaf->rn_key;
        cp3 = leaf->rn_mask;

        length = MIN(clen(cp), clen(cp2));
        if (cp3 == NULL)
                cp3 = rn_ones;
        else
                length = MIN(length, clen(cp3));

        cplim = cp + length;
        cp2 += skip;
        cp3 += skip;
        for (cp += skip; cp < cplim; cp++, cp2++, cp3++) {
                if ((*cp ^ *cp2) & *cp3)
                        return (false);
        }

        return (true);
}


/*
 * Search for the longest-prefix match of the key <key>.
 */
struct radix_node *
rn_match(const void *key, struct radix_node_head *head)
{
        struct radix_node *top, *t, *saved_t;
        const u_char *cp, *cp2, *cplim;
        int klen, matched_off, test, bit, rn_bit;

        top = head->rnh_treetop;

        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 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);
        cplim = (const u_char *)key + klen;
        cp = (const u_char *)key + top->rn_offset;
        cp2 = t->rn_key + top->rn_offset;
        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 (i.e., all-zero address).  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:
        /* Find the first bit that differs. */
        test = (*cp ^ *cp2) & 0xff;
        for (bit = 7; (test >>= 1) > 0;)
                bit--;
        matched_off = cp - (const u_char *)key;
        bit += matched_off << 3;
        rn_bit = -1 - bit;

        /*
         * Even if we don't match exactly as a host, we may match if the leaf
         * we wound up at has routes to networks.  Check those routes.
         */
        saved_t = t;
        /* Skip the host route, which might only appear at the first. */
        if (t->rn_mask == NULL)
                t = t->rn_dupedkey;
        for (; t != NULL; t = t->rn_dupedkey) {
                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 for network routes.
         */
        do {
                struct radix_node *x;
                struct radix_mask *m;
                int skip;

                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 "skip" back before the "do".
                 */
                for (m = t->rn_mklist; m != NULL; m = m->rm_next) {
                        if (m->rm_flags & RNF_NORMAL) {
                                if (rn_bit <= m->rm_bit)
                                        return (m->rm_leaf);
                        } else {
                                skip = MIN(t->rn_offset, matched_off);
                                x = rn_search_m(key, m->rm_mask, t);
                                while (x != NULL && x->rn_mask != m->rm_mask)
                                        x = x->rn_dupedkey;
                                if (x != NULL &&
                                    rn_satisfies_leaf(key, x, skip))
                                        return (x);
                        }
                }
        } while (t != top);

        return (NULL);
}

/*
 * Whenever to add a new leaf to the tree, another parent node is needed.
 * So they are allocated as an array of two elements: the first element is
 * the leaf, the second one is the parent node.
 *
 * This function initializes the given pair of nodes <nodes>, so that the
 * leaf is the left child of the parent node.
 */
static struct radix_node *
rn_newpair(const void *key, int bit, struct radix_node nodes[2])
{
        struct radix_node *left, *parent;

        left = &nodes[0];
        parent = &nodes[1];

        parent->rn_bit = bit;
        parent->rn_bmask = 0x80 >> (bit & 0x7);
        parent->rn_offset = bit >> 3;
        parent->rn_left = left;
        parent->rn_flags = RNF_ACTIVE;
        parent->rn_mklist = NULL;

        left->rn_bit = -1;
        left->rn_key = key;
        left->rn_parent = parent;
        left->rn_flags = parent->rn_flags;
        left->rn_mklist = NULL;

#ifdef RN_DEBUG
        left->rn_info = rn_nodenum++;
        parent->rn_info = rn_nodenum++;
        left->rn_twin = parent;
        left->rn_ybro = rn_clist;
        rn_clist = left;
#endif

        return (parent);
}

/*
 * Insert the key <key> to the radix tree <head>.
 *
 * If the key already exists, then set <dupentry> to 'true' and return the
 * node of the existing duped key.  Otherwise, set <dupentry> to 'false',
 * insert the key to the tree by making use of the given nodes <nodes>, and
 * return the node of the inserted key (i.e., &nodes[0]).
 */
static struct radix_node *
rn_insert(const void *key, struct radix_node_head *head, bool *dupentry,
          struct radix_node nodes[2])
{
        struct radix_node *top, *t, *tt;
        const u_char *cp;
        unsigned int bit;
        int head_off, klen;

        top = head->rnh_treetop;
        head_off = top->rn_offset;
        klen = clen(key);
        cp = (const u_char *)key + head_off;
        t = rn_search(key, top);

        /*
         * Find the first bit where the key and t->rn_key differ.
         */
    {
        const u_char *cp2 = t->rn_key + head_off;
        const u_char *cplim = (const u_char *)key + klen;
        int cmp_res;

        while (cp < cplim) {
                if (*cp2++ != *cp++)
                        goto on1;
        }

        *dupentry = true;
        return (t);

on1:
        *dupentry = false;
        cmp_res = (cp[-1] ^ cp2[-1]) & 0xff;
        for (bit = (cp - (const u_char *)key) << 3; cmp_res; bit--)
                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 (bit > (unsigned int)x->rn_bit);
                /* shortcut of: x->rn_bit < bit && x->rn_bit >= 0 */
#ifdef RN_DEBUG
        if (rn_debug) {
                log(LOG_DEBUG, "%s: Going In:\n", __func__);
                traverse(p);
        }
#endif
        t = rn_newpair(key, bit, 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, "%s: Coming Out:\n", __func__);
                traverse(p);
        }
#endif
    }
        return (tt);
}

/*
 * Add the netmask <mask> to the mask tree <maskhead>.  If <search> is
 * 'true', then only check the existence of the given mask but don't
 * actually add it.
 *
 * The <skip> parameter specifies the number of bytes to skip in <mask>
 * to obtain the mask data.  (NOTE: The length of a mask key doesn't
 * count the trailing zero bytes.)
 *
 * Return a pointer to the mask node on success; otherwise NULL on error.
 */
struct radix_node *
rn_addmask(const void *_mask, bool search, int skip,
           struct radix_node_head *maskhead)
{
        struct radix_node *x, *saved_x;
        const u_char *mask, *cp, *cplim;
        u_char *p, addmask_key[RN_MAXKEYLEN];
        int bit, mlen;
        bool maskduplicated, isnormal;

        mask = _mask;
        if ((mlen = clen(mask)) > RN_MAXKEYLEN)
                mlen = RN_MAXKEYLEN;
        if (skip == 0)
                skip = 1;
        if (mlen <= skip)
                return (maskhead->rnh_nodes); /* all-zero key */

        bzero(addmask_key, sizeof(addmask_key));
        if (skip > 1)
                bcopy(rn_ones + 1, addmask_key + 1, skip - 1);
        bcopy(mask + 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)
                return (maskhead->rnh_nodes); /* all-zero key */

        *addmask_key = mlen;
        x = rn_search(addmask_key, maskhead->rnh_treetop);
        if (x->rn_key == NULL) {
                kprintf("WARNING: radix_node->rn_key is NULL rn=%p\n", x);
                print_backtrace(-1);
                x = NULL;
        } else if (bcmp(addmask_key, x->rn_key, mlen) != 0) {
                x = NULL;
        }
        if (x != NULL || search)
                return (x);

        R_Malloc(x, struct radix_node *, RN_MAXKEYLEN + 2 * (sizeof *x));
        if ((saved_x = x) == NULL)
                return (NULL);

        bzero(x, RN_MAXKEYLEN + 2 * (sizeof *x));
        mask = p = (u_char *)(x + 2);
        bcopy(addmask_key, p, mlen);
        x = rn_insert(mask, maskhead, &maskduplicated, x);
        if (maskduplicated) {
                log(LOG_ERR, "%s: mask impossibly already in tree", __func__);
                R_Free(saved_x);
                return (x);
        }

        /*
         * Calculate the index of mask, and check for normalcy.
         *
         * First find the first byte with a 0 bit, then if there are more
         * bits left (remember we already trimmed the trailing zeros),
         * the pattern must be one of those in normal_chars[], or we have
         * a non-contiguous mask.
         */
        bit = 0;
        isnormal = true;
        cplim = mask + mlen;
        for (cp = mask + skip; cp < cplim; cp++) {
                if (*cp != 0xff)
                        break;
        }
        if (cp != cplim) {
                static const u_char normal_chars[] = {
                        0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff
                };
                u_char j;

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

/*
 * Compare the two netmasks and return true if netmask <m> is more
 * specific than netmask <n>.
 *
 * NOTE: arbitrary ordering for non-contiguous masks.
 */
static bool
rn_lexobetter(const void *_m, const void *_n)
{
        const u_char *m, *n, *lim;

        m = _m;
        n = _n;

        if (clen(m) > clen(n)) {
                /* not really, but need to check longer one first */
                return (true);
        }

        if (clen(m) == clen(n)) {
                for (lim = m + clen(m); m < lim; m++, n++) {
                        if (*m > *n)
                                return (true);
                }
        }

        return (false);
}

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

        m = MKGet(&rn_mkfreelist[mycpuid]);
        if (m == NULL) {
                log(LOG_ERR, "Mask for route not entered\n");
                return (NULL);
        }

        bzero(m, sizeof(*m));
        m->rm_bit = node->rn_bit;
        m->rm_flags = node->rn_flags;
        if (m->rm_flags & RNF_NORMAL)
                m->rm_leaf = node;
        else
                m->rm_mask = node->rn_mask;
        m->rm_next = nextmask;
        node->rn_mklist = m;

        return (m);
}

/*
 * Add the route (key, mask) to the radix tree <head> using the given
 * nodes <nodes>.  The netmask <mask> is NULL for a host route.
 *
 * Return the node of the inserted route on success.  Otherwise, return
 * NULL if the following happened:
 * - failed to add the netmask to the mask tree (e.g., out of memory)
 * - the identical route already exists
 *
 * NOTE: The address <key> and netmask <mask> must be of the same data
 *       structure (e.g., both 'struct sockaddr_in') so that they have the
 *       same skip bytes and data length.
 */
struct radix_node *
rn_addroute(const void *key, const void *mask,
            struct radix_node_head *head, struct radix_node nodes[2])
{
        struct radix_node *top, *t, *x, *tt, *saved_tt;
        struct radix_mask *m, **mp;
        int bit, bit_leaf;
        bool keyduplicated;
        const void *mmask;

        top = head->rnh_treetop;
        x = NULL;
        bit = bit_leaf = 0;

        /*
         * 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 (mask != NULL) {
                if ((x = rn_addmask(mask, false, top->rn_offset,
                                    head->rnh_maskhead)) == NULL)
                        return (NULL);
                bit_leaf = x->rn_bit;
                bit = -1 - x->rn_bit;
                mask = x->rn_key;
        }
        /*
         * Deal with duplicated keys: attach node to previous instance
         */
        saved_tt = tt = rn_insert(key, head, &keyduplicated, nodes);
        if (keyduplicated) {
                /*
                 * Deal with duplicated key: attach node to previous instance.
                 *
                 * The masks for a duplicated key are sorted in the same way
                 * as in a mask list -- most specific to least specific.
                 * This may require the unfortunate nuisance of relocating
                 * the head of the list.
                 *
                 * If the mask is NULL (i.e., a host route), it's placed at
                 * the beginning (i.e., list head).
                 *
                 * If the mask is not duplicated, we wouldn't find it among
                 * possible duplicate key entries anyway, so the test below
                 * doesn't hurt.
                 */
                for (t = tt; tt != NULL; t = tt, tt = tt->rn_dupedkey) {
                        if (tt->rn_mask == mask)
                                return (NULL); /* same route already exists */
                        if (mask == NULL /* host route */ ||
                            (tt->rn_mask != NULL &&
                             ((bit_leaf < tt->rn_bit) /* index(mask) > node */
                              || rn_refines(mask, tt->rn_mask)
                              || rn_lexobetter(mask, tt->rn_mask))))
                                break;
                }
                if (tt == saved_tt) {
                        struct  radix_node *xx = x;
                        /* link in at head of list */
                        (tt = nodes)->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 = nodes)->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 */
                }
                tt->rn_key = key;
                tt->rn_bit = -1;
                tt->rn_flags = RNF_ACTIVE;
#ifdef RN_DEBUG
                tt->rn_info = rn_nodenum++;
                tt->rn_twin = tt + 1;
                tt->rn_twin->rn_info = rn_nodenum++;
                tt->rn_ybro = rn_clist;
                rn_clist = tt;
#endif
        }

        /*
         * Put mask in tree.
         */
        if (mask != NULL) {
                tt->rn_mask = mask;
                tt->rn_bit = x->rn_bit;
                tt->rn_flags |= x->rn_flags & RNF_NORMAL;
        }
        t = saved_tt->rn_parent;
        if (keyduplicated)
                goto on2;
        bit_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 >= bit_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) != NULL; mp = &m->rm_next) {
                        if (m->rm_bit >= bit_leaf)
                                break;
                }
                t->rn_mklist = m;
                *mp = NULL;
        }

on2:
        if (mask == NULL || bit > t->rn_bit)
                return (tt); /* can't lift at all */

        /*
         * Add new route to the highest possible ancestor's list.
         */
        bit_leaf = tt->rn_bit;
        do {
                x = t;
                t = t->rn_parent;
        } while (bit <= t->rn_bit && x != top);
        /*
         * Search through routes associated with node to
         * insert new route according to index.
         * Need same criteria as when sorting dupedkeys to avoid
         * double loop on deletion.
         */
        for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_next) {
                if (m->rm_bit < bit_leaf)
                        continue;
                if (m->rm_bit > bit_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 == mask) {
                        m->rm_refs++;
                        tt->rn_mklist = m;
                        return (tt);
                }
                if (rn_refines(mask, mmask) || rn_lexobetter(mask, mmask))
                        break;
        }
        *mp = rn_new_radix_mask(tt, *mp);
        return (tt);
}

struct radix_node *
rn_delete(const void *key, const void *mask, struct radix_node_head *head)
{
        struct radix_node *top, *t, *p, *x, *tt, *saved_tt, *dupedkey;
        struct radix_mask *m, *saved_m, **mp;
        int bit, head_off, klen, cpu;

        cpu = mycpuid;
        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((const u_char *)key + head_off, tt->rn_key + head_off,
                 klen - head_off) != 0)
                return (NULL);

        /*
         * Delete our route from mask lists.
         */
        if (mask != NULL) {
                if ((x = rn_addmask(mask, true, head_off,
                                    head->rnh_maskhead)) == NULL)
                        return (NULL);
                mask = x->rn_key;
                while (tt->rn_mask != mask) {
                        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;
        }
        bit = -1 - tt->rn_bit;
        t = saved_tt->rn_parent;
        if (bit > t->rn_bit)
                goto on1; /* Wasn't lifted at all */

        do {
                x = t;
                t = t->rn_parent;
        } while (bit <= t->rn_bit && x != top);
        for (mp = &x->rn_mklist; (m = *mp) != NULL; mp = &m->rm_next)
                if (m == saved_m) {
                        *mp = m->rm_next;
                        MKFree(&rn_mkfreelist[cpu], 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 != NULL && t->rn_ybro != tt; t = t->rn_ybro)
                ;
        if (t != NULL)
                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 != NULL && 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
                        bit = t->rn_info;
                        *++x = *t;
                        t->rn_info = bit;
                        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) != NULL;)
                                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[cpu], 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
                bit = t->rn_info;
                *t = *x;
                t->rn_info = bit;
#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[0].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, const void *_addr,
                 const void *_mask, walktree_f_t *f, void *w)
{
        struct radix_node *rn, *base, *next, *last;
        const u_char *addr, *mask;
        bool stopping;
        int lastb, error;

        addr = _addr;
        mask = _mask;
        last = NULL;
        stopping = false;

        /*
         * rn_search_m() is sort-of-open-coded here.  We cannot use that
         * function because we need to keep track of the last node seen.
         */
        /* kprintf("about to search\n"); */
        for (rn = h->rnh_treetop; rn->rn_bit >= 0; ) {
                last = rn;
                /* kprintf("rn_bit %d, rn_bmask %x, mask[rn_offset] %x\n",
                       rn->rn_bit, rn->rn_bmask, mask[rn->rn_offset]); */
                if (!(rn->rn_bmask & mask[rn->rn_offset])) {
                        break;
                }
                if (rn->rn_bmask & addr[rn->rn_offset]) {
                        rn = rn->rn_right;
                } else {
                        rn = rn->rn_left;
                }
        }
        /* kprintf("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;

        /* kprintf("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) {
                /* kprintf("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 = true;
                                /* kprintf("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;
                        /* kprintf("leaf %p\n", rn); */
                        if (!(rn->rn_flags & RNF_ROOT) && (error = (*f)(rn, w)))
                                return (error);
                }
                rn = next;

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

        return 0;
}

static int
rn_walktree_at(struct radix_node_head *h, const void *addr, const void *mask,
               walktree_f_t *f, void *w)
{
        struct radix_node *rn, *base, *next;
        int error;

        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.
         */
        if (addr == NULL) {
                /* First time through node, go left */
                while (rn->rn_bit >= 0)
                        rn = rn->rn_left;
        } else {
                if (mask != NULL)
                        rn = rn_search_m(addr, mask, rn);
                else
                        rn = rn_search(addr, rn);
        }
        for (;;) {
                base = rn;
                /* If at right child go back up, otherwise, go right */
                while (rn->rn_parent->rn_right == rn &&
                    !(rn->rn_flags & RNF_ROOT))
                        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 */
}

static int
rn_walktree(struct radix_node_head *h, walktree_f_t *f, void *w)
{
        return rn_walktree_at(h, NULL, NULL, f, w);
}

/*
 * Allocate and initialize an empty radix tree at <head>.
 *
 * The created radix_node_head embeds 3 nodes in the order of
 * {left,root,right}.  These nodes are flagged with RNF_ROOT and thus
 * cannot be freed.  The left and right leaves are initialized with
 * all-zero and all-one keys, respectively, and with the significant
 * byte starting at <off_bytes>.
 *
 * The <maskhead> refers to another radix tree for storing the network
 * masks (so aka mask tree).  It is also created by this function with
 * <maskhead>=NULL; the <off_bytes> parameter is ignored and auto set
 * to be zero (0).  The reason of requiring <off_bytes> be zero is that
 * a mask tree can be shared with multiple radix trees of different
 * address families that have different offset bytes; e.g.,
 * offsetof(struct sockaddr_in, sin_addr) !=
 * offsetof(struct sockaddr_in6, sin6_addr).
 *
 * Return 1 on success, 0 on error.
 */
int
rn_inithead(struct radix_node_head **head, struct radix_node_head *maskhead,
            int off_bytes)
{
        struct radix_node_head *rnh;
        struct radix_node *root, *left, *right;

        if (*head != NULL)      /* already initialized */
                return (1);

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

        if (maskhead == NULL)   /* mask tree initialization */
                off_bytes = 0;
        if (off_bytes >= RN_MAXKEYLEN)  /* prevent possible misuse */
                panic("%s: invalid off_bytes=%d", __func__, off_bytes);

        bzero(rnh, sizeof *rnh);
        *head = rnh;

        root = rn_newpair(rn_zeros, off_bytes * NBBY, rnh->rnh_nodes);
        right = &rnh->rnh_nodes[2];
        root->rn_parent = root;
        root->rn_flags = RNF_ROOT | RNF_ACTIVE;
        root->rn_right = right;

        left = root->rn_left;
        left->rn_bit = -1 - off_bytes * NBBY;
        left->rn_flags = root->rn_flags;

        *right = *left;
        right->rn_key = rn_ones;

        rnh->rnh_treetop = root;
        rnh->rnh_maskhead = maskhead;

        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_walktree_at = rn_walktree_at;

        return (1);
}

/*
 * Callback function to be used in rn_flush() to empty a mask tree.
 */
void
rn_freemask(struct radix_node *rn)
{
        if (rn->rn_mask != NULL)
                panic("%s: not a mask node", __func__);

        R_Free(rn);
}

struct rn_flush_ctx {
        struct radix_node_head *head;
        freenode_f_t *f;
};

static int
rn_flush_walker(struct radix_node *rn, void *arg)
{
        struct rn_flush_ctx *ctx = arg;
        struct radix_node *node;

        node = ctx->head->rnh_deladdr(rn->rn_key, rn->rn_mask, ctx->head);
        if (node != rn) {
                panic("%s: deleted wrong node: %p, want: %p",
                      __func__, node, rn);
        }
        if (ctx->f)
                ctx->f(rn);

        return 0;
}

#define IS_EMPTY(head) \
        (((head)->rnh_treetop == &(head)->rnh_nodes[1]) && \
         ((head)->rnh_treetop->rn_left == &(head)->rnh_nodes[0]) && \
         ((head)->rnh_treetop->rn_right == &(head)->rnh_nodes[2]))

/*
 * Flush all nodes in the radix tree at <head>.
 * If the callback function <f> is specified, it is called against every
 * flushed node to allow the caller to do extra cleanups.
 */
void
rn_flush(struct radix_node_head *head, freenode_f_t *f)
{
        struct rn_flush_ctx ctx;

        if (f == rn_freemask && head->rnh_maskhead != NULL)
                panic("%s: rn_freemask() used with non-mask tree", __func__);

        ctx.head = head;
        ctx.f = f;
        head->rnh_walktree(head, rn_flush_walker, &ctx);

        if (!IS_EMPTY(head))
                panic("%s: failed to flush all nodes", __func__);
}

/*
 * Free an empty radix tree at <head>.
 *
 * NOTE: The radix tree must be first emptied by rn_flush().
 */
void
rn_freehead(struct radix_node_head *head)
{
        if (!IS_EMPTY(head))
                panic("%s: radix tree not empty", __func__);

        R_Free(head);
}

#ifdef _KERNEL

static void
rn_init_handler(netmsg_t msg)
{
        int cpu = mycpuid;

        ASSERT_NETISR_NCPUS(cpu);
        if (rn_inithead(&mask_rnheads[cpu], NULL, 0) == 0)
                panic("%s: failed to create mask tree", __func__);

        netisr_forwardmsg(&msg->base, cpu + 1);
}

void
rn_init(void)
{
        struct netmsg_base msg;
        struct domain *dom;

        SLIST_FOREACH(dom, &domains, dom_next) {
                if (dom->dom_maxrtkey > RN_MAXKEYLEN) {
                        panic("domain %s maxkey too big %d/%d",
                              dom->dom_name, dom->dom_maxrtkey, RN_MAXKEYLEN);
                }
        }

        netmsg_init(&msg, NULL, &curthread->td_msgport, 0, rn_init_handler);
        netisr_domsg_global(&msg);
}

struct radix_node_head *
rn_cpumaskhead(int cpu)
{
        ASSERT_NETISR_NCPUS(cpu);
        KKASSERT(mask_rnheads[cpu] != NULL);
        return mask_rnheads[cpu];
}

#else /* !_KERNEL */

void
rn_init(void)
{
        if (rn_inithead(&mask_rnheads[0], NULL, 0) == 0)
                panic("%s: failed to create mask tree", __func__);
}

struct radix_node_head *
rn_cpumaskhead(int cpu __unused)
{
        return mask_rnheads[0];
}

#endif /* _KERNEL */