radix.c

-

/*
 * $Id: radix.c,v 1.9 1998/11/12 06:30:14 wessels Exp $
 *
 * DEBUG: section 53     Radix tree data structure implementation
 * AUTHOR: NetBSD Derived
 *
 * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from the
 *  Internet community.  Development is led by Duane Wessels of the
 *  National Laboratory for Applied Network Research and funded by the
 *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
 *  Duane Wessels and the University of California San Diego.  Please
 *  see the COPYRIGHT file for full details.  Squid incorporates
 *  software developed and/or copyrighted by other sources.  Please see
 *  the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */


/*
 * 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
 */

#include "config.h"

#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_STDIO_H
#include <stdio.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_CTYPE_H
#include <ctype.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#if HAVE_GRP_H
#include <grp.h>
#endif
#if HAVE_GNUMALLOC_H
#include <gnumalloc.h>
#elif HAVE_MALLOC_H && !defined(_SQUID_FREEBSD_) && !defined(_SQUID_NEXT_)
#include <malloc.h>
#endif
#if HAVE_MEMORY_H
#include <memory.h>
#endif
#if HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#if HAVE_ASSERT_H
#include <assert.h>
#endif

#include "util.h"

#include "radix.h"

int max_keylen;
struct radix_mask *rn_mkfreelist;
struct radix_node_head *mask_rnhead;
static char *addmask_key;
static unsigned char normal_chars[] =
{0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xFF};
static char *rn_zeros, *rn_ones;

#define rn_masktop (mask_rnhead->rnh_treetop)
#undef Bcmp
#define Bcmp(a, b, l) (l == 0 ? 0 : memcmp((caddr_t)(a), (caddr_t)(b), (u_long)l))
/*
 * 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 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.
 */

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_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(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_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(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) {
	if ((x = rn_addmask(m_arg, 1, head->rnh_treetop->rn_off)) == 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_off, vlen = *(u_char *) cp, matched_off;
    register 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 = *(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_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_p;
	if ((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".
	     */
	    do {
		if (m->rm_flags & RNF_NORMAL) {
		    if (rn_b <= m->rm_b)
			return (m->rm_leaf);
		} else {
		    off = min(t->rn_off, matched_off);
		    x = rn_search_m(v, t, m->rm_mask);
		    while (x && x->rn_mask != m->rm_mask)
			x = x->rn_dupedkey;
		    if (x && rn_satsifies_leaf(v, x, off))
			return x;
		}
	    } while ((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

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_b = b;
    t->rn_bmask = 0x80 >> (b & 7);
    t->rn_l = tt;
    t->rn_off = b >> 3;
    tt->rn_b = -1;
    tt->rn_key = (caddr_t) v;
    tt->rn_p = t;
    tt->rn_flags = t->rn_flags = RNF_ACTIVE;
#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;
}

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_off, 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_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)
	    fprintf(stderr, "rn_insert: Going In:\n");
	traverse(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, "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)
	memcpy(addmask_key + 1, rn_ones + 1, skip - 1);
    if ((m0 = mlen) > skip)
	memcpy(addmask_key + skip, netmask + skip, mlen - skip);
    /*
     * Trim trailing zeroes.
     */
    for (cp = addmask_key + mlen; (cp > addmask_key) && cp[-1] == 0;)
	cp--;
    mlen = cp - addmask_key;
    if (mlen <= skip) {
	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)