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//==========================================================================

//

//      src/sys/net/radix.c

//

//==========================================================================

//####BSDCOPYRIGHTBEGIN####

//

// -------------------------------------------

//

// Portions of this software may have been derived from OpenBSD, 

// FreeBSD or other sources, and are covered by the appropriate

// copyright disclaimers included herein.

//

// Portions created by Red Hat are

// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.

//

// -------------------------------------------

//

//####BSDCOPYRIGHTEND####

//==========================================================================

/*

 * Copyright (c) 1988, 1989, 1993

 *      The Regents of the University of California.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *      This product includes software developed by the University of

 *      California, Berkeley and its contributors.

 * 4. Neither the name of the University nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 *      @(#)radix.c     8.4 (Berkeley) 11/2/94

 * $FreeBSD: src/sys/net/radix.c,v 1.20.2.2 2001/03/06 00:56:50 obrien Exp $

 */

/*

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

 */

#ifndef _RADIX_H_

#include <sys/param.h>

#ifdef  _KERNEL

#include <sys/malloc.h>

#define M_DONTWAIT M_NOWAIT

#include <sys/domain.h>

#else

#include <stdlib.h>

#endif

#include <net/radix.h>

#endif

static int      rn_walktree_from __P((struct radix_node_head *h, void *a,

                                      void *m, walktree_f_t *f, void *w));

static int rn_walktree __P((struct radix_node_head *, walktree_f_t *, void *));

static struct radix_node

         *rn_insert __P((void *, struct radix_node_head *, int *,

                        struct radix_node [2])),

         *rn_newpair __P((void *, int, struct radix_node[2])),

         *rn_search __P((void *, struct radix_node *)),

         *rn_search_m __P((void *, struct radix_node *, void *));

static int      max_keylen;

static struct radix_mask *rn_mkfreelist;

static struct radix_node_head *mask_rnhead;

static char *addmask_key;

static char normal_chars[] = {0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, -1};

static char *rn_zeros, *rn_ones;

#define rn_masktop (mask_rnhead->rnh_treetop)

#undef Bcmp

#define Bcmp(a, b, l) \

        (l == 0 ? 0 : bcmp((caddr_t)(a), (caddr_t)(b), (u_long)l))

static int      rn_lexobetter __P((void *m_arg, void *n_arg));

static struct radix_mask *

                rn_new_radix_mask __P((struct radix_node *tt,

                                       struct radix_mask *next));

static int      rn_satsifies_leaf __P((char *trial, struct radix_node *leaf,

                                       int skip));

/*

 * The data structure for the keys is a radix tree with one way

 * branching removed.  The index rn_bit at an internal node n represents a bit

 * position to be tested.  The tree is arranged so that all descendants

 * of a node n have keys whose bits all agree up to position rn_bit - 1.

 * (We say the index of n is rn_bit.)

 *

 * There is at least one descendant which has a one bit at position rn_bit,

 * and at least one with a zero there.

 *

 * A route is determined by a pair of key and mask.  We require that the

 * bit-wise logical and of the key and mask to be the key.

 * We define the index of a route to associated with the mask to be

 * the first bit number in the mask where 0 occurs (with bit number 0

 * representing the highest order bit).

 *

 * We say a mask is normal if every bit is 0, past the index of the mask.

 * If a node n has a descendant (k, m) with index(m) == index(n) == rn_bit,

 * and m is a normal mask, then the route applies to every descendant of n.

 * If the index(m) < rn_bit, this implies the trailing last few bits of k

 * before bit b are all 0, (and hence consequently true of every descendant

 * of n), so the route applies to all descendants of the node as well.

 *

 * Similar logic shows that a non-normal mask m such that

 * index(m) <= index(n) could potentially apply to many children of n.

 * Thus, for each non-host route, we attach its mask to a list at an internal

 * node as high in the tree as we can go.

 *

 * The present version of the code makes use of normal routes in short-

 * circuiting an explict mask and compare operation when testing whether

 * a key satisfies a normal route, and also in remembering the unique leaf

 * that governs a subtree.

 */

static struct radix_node *

rn_search(v_arg, head)

        void *v_arg;

        struct radix_node *head;

{

        register struct radix_node *x;

        register caddr_t v;

        for (x = head, v = v_arg; x->rn_bit >= 0;) {

                if (x->rn_bmask & v[x->rn_offset])

                        x = x->rn_right;

                else

                        x = x->rn_left;

        }

        return (x);

}

static struct radix_node *

rn_search_m(v_arg, head, m_arg)

        struct radix_node *head;

        void *v_arg, *m_arg;

{

        register struct radix_node *x;

        register caddr_t v = v_arg, m = m_arg;

        for (x = head; x->rn_bit >= 0;) {

                if ((x->rn_bmask & m[x->rn_offset]) &&

                    (x->rn_bmask & v[x->rn_offset]))

                        x = x->rn_right;

                else

                        x = x->rn_left;

        }

        return x;

}

int

rn_refines(m_arg, n_arg)

        void *m_arg, *n_arg;

{

        register caddr_t m = m_arg, n = n_arg;

        register caddr_t lim, lim2 = lim = n + *(u_char *)n;

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

        int masks_are_equal = 1;

        if (longer > 0)

                lim -= longer;

        while (n < lim) {

                if (*n & ~(*m))

                        return 0;

                if (*n++ != *m++)

                        masks_are_equal = 0;

        }

        while (n < lim2)

                if (*n++)

                        return 0;

        if (masks_are_equal && (longer < 0))

                for (lim2 = m - longer; m < lim2; )

                        if (*m++)

                                return 1;

        return (!masks_are_equal);

}

struct radix_node *

rn_lookup(v_arg, m_arg, head)

        void *v_arg, *m_arg;

        struct radix_node_head *head;

{

        register struct radix_node *x;

        caddr_t netmask = 0;

        if (m_arg) {

                x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_offset);

                if (x == 0)

                        return (0);

                netmask = x->rn_key;

        }

        x = rn_match(v_arg, head);

        if (x && netmask) {

                while (x && x->rn_mask != netmask)

                        x = x->rn_dupedkey;

        }

        return x;

}

static int

rn_satsifies_leaf(trial, leaf, skip)

        char *trial;

        register struct radix_node *leaf;

        int skip;

{

        register char *cp = trial, *cp2 = leaf->rn_key, *cp3 = leaf->rn_mask;

        char *cplim;

        int length = min(*(u_char *)cp, *(u_char *)cp2);

        if (cp3 == 0)

                cp3 = rn_ones;

        else

                length = min(length, *(u_char *)cp3);

        cplim = cp + length; cp3 += skip; cp2 += skip;

        for (cp += skip; cp < cplim; cp++, cp2++, cp3++)

                if ((*cp ^ *cp2) & *cp3)

                        return 0;

        return 1;

}

struct radix_node *

rn_match(v_arg, head)

        void *v_arg;

        struct radix_node_head *head;

{

        caddr_t v = v_arg;

        register struct radix_node *t = head->rnh_treetop, *x;

        register caddr_t cp = v, cp2;

        caddr_t cplim;

        struct radix_node *saved_t, *top = t;

        int off = t->rn_offset, vlen = *(u_char *)cp, matched_off;

        register int test, b, rn_bit;

        /*

         * Open code rn_search(v, top) to avoid overhead of extra

         * subroutine call.

         */

        for (; t->rn_bit >= 0; ) {

                if (t->rn_bmask & cp[t->rn_offset])

                        t = t->rn_right;

                else

                        t = t->rn_left;

        }

        /*

         * See if we match exactly as a host destination

         * or at least learn how many bits match, for normal mask finesse.

         *

         * It doesn't hurt us to limit how many bytes to check

         * to the length of the mask, since if it matches we had a genuine

         * match and the leaf we have is the most specific one anyway;

         * if it didn't match with a shorter length it would fail

         * with a long one.  This wins big for class B&C netmasks which

         * are probably the most common case...

         */

        if (t->rn_mask)

                vlen = *(u_char *)t->rn_mask;

        cp += off; cp2 = t->rn_key + off; cplim = v + vlen;

        for (; cp < cplim; cp++, cp2++)

                if (*cp != *cp2)

                        goto on1;

        /*

         * This extra grot is in case we are explicitly asked

         * to look up the default.  Ugh!

         *

         * Never return the root node itself, it seems to cause a

         * lot of confusion.

         */

        if (t->rn_flags & RNF_ROOT)

                t = t->rn_dupedkey;

        return t;

on1:

        test = (*cp ^ *cp2) & 0xff; /* find first bit that differs */

        for (b = 7; (test >>= 1) > 0;)

                b--;

        matched_off = cp - v;

        b += matched_off << 3;

        rn_bit = -1 - b;

        /*

         * If there is a host route in a duped-key chain, it will be first.

         */

        if ((saved_t = t)->rn_mask == 0)

                t = t->rn_dupedkey;

        for (; t; t = t->rn_dupedkey)

                /*

                 * Even if we don't match exactly as a host,

                 * we may match if the leaf we wound up at is

                 * a route to a net.

                 */

                if (t->rn_flags & RNF_NORMAL) {

                        if (rn_bit <= t->rn_bit)

                                return t;

                } else if (rn_satsifies_leaf(v, t, matched_off))

                                return t;

        t = saved_t;

        /* start searching up the tree */

        do {

                register struct radix_mask *m;

                t = t->rn_parent;

                m = t->rn_mklist;

                /*

                 * If 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".

                 */

                while (m) {

                        if (m->rm_flags & RNF_NORMAL) {

                                if (rn_bit <= m->rm_bit)

                                        return (m->rm_leaf);

                        } else {

                                off = min(t->rn_offset, matched_off);

                                x = rn_search_m(v, t, m->rm_mask);

                                while (x && x->rn_mask != m->rm_mask)

                                        x = x->rn_dupedkey;

                                if (x && rn_satsifies_leaf(v, x, off))

                                        return x;

                        }

                        m = m->rm_mklist;

                }

        } while (t != top);

        return 0;

}

#ifdef RN_DEBUG

int     rn_nodenum;

struct  radix_node *rn_clist;

int     rn_saveinfo;

int     rn_debug =  1;

#endif

static struct radix_node *

rn_newpair(v, b, nodes)

        void *v;

        int b;

        struct radix_node nodes[2];

{

        register struct radix_node *tt = nodes, *t = tt + 1;

        t->rn_bit = b;

        t->rn_bmask = 0x80 >> (b & 7);

        t->rn_left = tt;

        t->rn_offset = b >> 3;

        tt->rn_bit = -1;

        tt->rn_key = (caddr_t)v;

        tt->rn_parent = t;

        tt->rn_flags = t->rn_flags = RNF_ACTIVE;

        tt->rn_mklist = t->rn_mklist = 0;

#ifdef RN_DEBUG

        tt->rn_info = rn_nodenum++; t->rn_info = rn_nodenum++;

        tt->rn_twin = t;

        tt->rn_ybro = rn_clist;

        rn_clist = tt;

#endif

        return t;

}

static struct radix_node *

rn_insert(v_arg, head, dupentry, nodes)

        void *v_arg;

        struct radix_node_head *head;

        int *dupentry;

        struct radix_node nodes[2];

{

        caddr_t v = v_arg;

        struct radix_node *top = head->rnh_treetop;

        int head_off = top->rn_offset, vlen = (int)*((u_char *)v);

        register struct radix_node *t = rn_search(v_arg, top);

        register caddr_t cp = v + head_off;

        register int b;

        struct radix_node *tt;

        /*

         * Find first bit at which v and t->rn_key differ

         */

    {

        register caddr_t cp2 = t->rn_key + head_off;

        register int cmp_res;

        caddr_t cplim = v + vlen;

        while (cp < cplim)

                if (*cp2++ != *cp++)

                        goto on1;

        *dupentry = 1;

        return t;

on1:

        *dupentry = 0;

        cmp_res = (cp[-1] ^ cp2[-1]) & 0xff;

        for (b = (cp - v) << 3; cmp_res; b--)

                cmp_res >>= 1;

    }

    {

        register struct radix_node *p, *x = top;

        cp = v;

        do {

                p = x;

                if (cp[x->rn_offset] & x->rn_bmask)

                        x = x->rn_right;

                else

                        x = x->rn_left;

        } while (b > (unsigned) x->rn_bit);

                                /* x->rn_bit < b && x->rn_bit >= 0 */

#ifdef RN_DEBUG

        if (rn_debug)

                log(LOG_DEBUG, "rn_insert: Going In:\n"), traverse(p);

#endif

        t = rn_newpair(v_arg, b, nodes);

        tt = t->rn_left;

        if ((cp[p->rn_offset] & p->rn_bmask) == 0)

                p->rn_left = t;

        else

                p->rn_right = t;

        x->rn_parent = t;

        t->rn_parent = p; /* frees x, p as temp vars below */

        if ((cp[t->rn_offset] & t->rn_bmask) == 0) {

                t->rn_right = x;

        } else {

                t->rn_right = tt;

                t->rn_left = x;

        }

#ifdef RN_DEBUG

        if (rn_debug)

                log(LOG_DEBUG, "rn_insert: Coming Out:\n"), traverse(p);

#endif

    }

        return (tt);

}

struct radix_node *

rn_addmask(n_arg, search, skip)

        int search, skip;

        void *n_arg;

{

        caddr_t netmask = (caddr_t)n_arg;

        register struct radix_node *x;

        register caddr_t cp, cplim;

        register int b = 0, mlen, j;

        int maskduplicated, m0, isnormal;

        struct radix_node *saved_x;

        static int last_zeroed = 0;

        if ((mlen = *(u_char *)netmask) > max_keylen)

                mlen = max_keylen;

        if (skip == 0)

                skip = 1;

        if (mlen <= skip)

                return (mask_rnhead->rnh_nodes);

        if (skip > 1)

                Bcopy(rn_ones + 1, addmask_key + 1, skip - 1);

        if ((m0 = mlen) > skip)

                Bcopy(netmask + skip, addmask_key + skip, mlen - skip);

        /*

         * Trim trailing zeroes.

         */

        for (cp = addmask_key + mlen; (cp > addmask_key) && cp[-1] == 0;)

                cp--;

        mlen = cp - addmask_key;

        if (mlen <= skip) {

                if (m0 >= last_zeroed)

                        last_zeroed = mlen;

                return (mask_rnhead->rnh_nodes);

        }

        if (m0 < last_zeroed)

                Bzero(addmask_key + m0, last_zeroed - m0);

        *addmask_key = last_zeroed = mlen;

        x = rn_search(addmask_key, rn_masktop);

        if (Bcmp(addmask_key, x->rn_key, mlen) != 0)

                x = 0;

        if (x || search)

                return (x);

        R_Malloc(x, struct radix_node *, max_keylen + 2 * sizeof (*x));

        if ((saved_x = x) == 0)

                return (0);

        Bzero(x, max_keylen + 2 * sizeof (*x));

        netmask = cp = (caddr_t)(x + 2);

        Bcopy(addmask_key, cp, mlen);

        x = rn_insert(cp, mask_rnhead, &maskduplicated, x);

        if (maskduplicated) {

                log(LOG_ERR, "rn_addmask: mask impossibly already in tree");

                Free(saved_x);

                return (x);

        }

        /*

         * Calculate index of mask, and check for normalcy.

         */

        cplim = netmask + mlen; isnormal = 1;

        for (cp = netmask + skip; (cp < cplim) && *(u_char *)cp == 0xff;)

                cp++;

        if (cp != cplim) {

                for (j = 0x80; (j & *cp) != 0; j >>= 1)

                        b++;

                if (*cp != normal_chars[b] || cp != (cplim - 1))

                        isnormal = 0;

        }

        b += (cp - netmask) << 3;

        x->rn_bit = -1 - b;

        if (isnormal)

                x->rn_flags |= RNF_NORMAL;

        return (x);

}

static int      /* XXX: arbitrary ordering for non-contiguous masks */

rn_lexobetter(m_arg, n_arg)

        void *m_arg, *n_arg;

{

        register u_char *mp = m_arg, *np = n_arg, *lim;

        if (*mp > *np)

                return 1;  /* not really, but need to check longer one first */

        if (*mp == *np)

                for (lim = mp + *mp; mp < lim;)

                        if (*mp++ > *np++)

                                return 1;

        return 0;

}

static struct radix_mask *

rn_new_radix_mask(tt, next)

        register struct radix_node *tt;

        register struct radix_mask *next;

{

        register struct radix_mask *m;

        MKGet(m);

        if (m == 0) {

                log(LOG_ERR, "Mask for route not entered\n");

                return (0);

        }

        Bzero(m, sizeof *m);

        m->rm_bit = tt->rn_bit;

        m->rm_flags = tt->rn_flags;

        if (tt->rn_flags & RNF_NORMAL)

                m->rm_leaf = tt;

        else

                m->rm_mask = tt->rn_mask;

        m->rm_mklist = next;

        tt->rn_mklist = m;

        return m;

}

struct radix_node *

rn_addroute(v_arg, n_arg, head, treenodes)

        void *v_arg, *n_arg;

        struct radix_node_head *head;

        struct radix_node treenodes[2];

{

        caddr_t v = (caddr_t)v_arg, netmask = (caddr_t)n_arg;

        register struct radix_node *t, *x = 0, *tt;

        struct radix_node *saved_tt, *top = head->rnh_treetop;

        short b = 0, b_leaf = 0;

        int keyduplicated;

        caddr_t mmask;

        struct radix_mask *m, **mp;

        /*

         * In dealing with non-contiguous masks, there may be

         * many different routes which have the same mask.

         * We will find it useful to have a unique pointer to

         * the mask to speed avoiding duplicate references at

         * nodes and possibly save time in calculating indices.

         */

        if (netmask)  {

                if ((x = rn_addmask(netmask, 0, top->rn_offset)) == 0)

                        return (0);

                b_leaf = x->rn_bit;

                b = -1 - x->rn_bit;

                netmask = x->rn_key;

        }

        /*

         * Deal with duplicated keys: attach node to previous instance

         */

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

        if (keyduplicated) {

                for (t = tt; tt; t = tt, tt = tt->rn_dupedkey) {

                        if (tt->rn_mask == netmask)

                                return (0);

                        if (netmask == 0 ||

                            (tt->rn_mask &&

                             ((b_leaf < tt->rn_bit) /* index(netmask) > node */

                              || rn_refines(netmask, tt->rn_mask)

                              || rn_lexobetter(netmask, tt->rn_mask))))

                                break;

                }

                /*

                 * If the mask is not duplicated, we wouldn't

                 * find it among possible duplicate key entries

                 * anyway, so the above test doesn't hurt.

                 *

                 * We sort the masks for a duplicated key the same way as

                 * in a masklist -- most specific to least specific.

                 * This may require the unfortunate nuisance of relocating

                 * the head of the list.

                 */

                if (tt == saved_tt) {

                        struct  radix_node *xx = x;

                        /* link in at head of list */

                        (tt = treenodes)->rn_dupedkey = t;

                        tt->rn_flags = t->rn_flags;

                        tt->rn_parent = x = t->rn_parent;

                        t->rn_parent = tt;                      /* parent */

                        if (x->rn_left == t)

                                x->rn_left = tt;

                        else

                                x->rn_right = tt;

                        saved_tt = tt; x = xx;

                } else {

                        (tt = treenodes)->rn_dupedkey = t->rn_dupedkey;

                        t->rn_dupedkey = tt;

                        tt->rn_parent = t;                      /* parent */

                        if (tt->rn_dupedkey)                    /* parent */

                                tt->rn_dupedkey->rn_parent = tt; /* parent */

                }

#ifdef RN_DEBUG

                t=tt+1; tt->rn_info = rn_nodenum++; t->rn_info = rn_nodenum++;

                tt->rn_twin = t; tt->rn_ybro = rn_clist; rn_clist = tt;

#endif

                tt->rn_key = (caddr_t) v;

                tt->rn_bit = -1;

                tt->rn_flags = RNF_ACTIVE;

        }

        /*

         * Put mask in tree.

         */

        if (netmask) {

                tt->rn_mask = netmask;

                tt->rn_bit = x->rn_bit;