radix.c

netflow,抓包

/*
 * 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 acknowledgment:
 *	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
 *
 */

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

#include "ftconfig.h"
#include "ftlib.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>


#if !defined(sgi) && !defined(__NetBSD__)
static char sccsid[] __attribute__((unused)) = "@(#)rdisc.c	8.1 (Berkeley) x/y/95";
#elif defined(__NetBSD__)
__RCSID("$NetBSD$");
#endif
#ident "$FreeBSD: src/sbin/routed/radix.c,v 1.5 1999/09/05 17:49:11 peter Exp $"

#define LOG_ERR 0
#define LOG_DEBUG 0

#define log(x, msg) fterr_warnx(msg);
#define panic(s) {log(1,s); exit(1);}

#define min(a,b) (((a)<(b))?(a):(b))

static void *rtmalloc(size_t size, const char *msg);

static void *rtmalloc(size_t size, const char *msg)
{
  void *p;

  if (!(p = malloc(size)))
    fterr_err(1, "malloc(): %s", msg);
  return p;
} /* rtmalloc */


int	max_keylen;
struct radix_mask *rn_mkfreelist;
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 \
		       : memcmp((caddr_t)(a), (caddr_t)(b), (size_t)l))

static int rn_satisfies_leaf(char *, struct radix_node *, int);

/*
 * 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(void *v_arg,
	  struct radix_node *head)
{
	struct radix_node *x;
	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(void *v_arg,
	    struct radix_node *head,
	    void *m_arg)
{
	struct radix_node *x;
	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(void* m_arg, void *n_arg)
{
	caddr_t m = m_arg, n = n_arg;
	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(void *v_arg, void *m_arg, struct radix_node_head *head)
{
	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_satisfies_leaf(char *trial,
		  struct radix_node *leaf,
		  int skip)
{
	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(void *v_arg,
	 struct radix_node_head *head)
{
	caddr_t v = v_arg;
	struct radix_node *t = head->rnh_treetop, *x;
	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;
	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!
	 * Or 255.255.255.255
	 *
	 * In this case, we have a complete match of the key.  Unless
	 * the node is one of the roots, we are finished.
	 * If it is the zeros root, then take what we have, prefering
	 * any real data.
	 * If it is the ones root, then pretend the target key was followed
	 * by a byte of zeros.
	 */
	if (!(t->rn_flags & RNF_ROOT))
		return t;		/* not a root */
	if (t->rn_dupedkey) {
		t = t->rn_dupedkey;
		return t;		/* have some real data */
	}
	if (*(cp-1) == 0)
		return t;		/* not the ones root */
	b = 0;				/* fake a zero after 255.255.255.255 */
	goto on2;
on1:
	test = (*cp ^ *cp2) & 0xff; /* find first bit that differs */
	for (b = 7; (test >>= 1) > 0;)
		b--;
on2:
	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;
		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_satisfies_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(void *v, int b, struct radix_node nodes[2])
{
	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(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);
	struct radix_node *t = rn_search(v_arg, top);
	caddr_t cp = v + head_off;
	int b;
	struct radix_node *tt;

	/*
	 * Find first bit at which v and t->rn_key differ
	 */
    {
		caddr_t cp2 = t->rn_key + head_off;
		int cmp_res;
	caddr_t cplim = v + vlen;

	while (cp < cplim)
		if (*cp2++ != *cp++)
			goto on1;
	/* handle adding 255.255.255.255 */
	if (!(t->rn_flags & RNF_ROOT) || *(cp2-1) == 0) {
		*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 ((unsigned)b > (unsigned)x->rn_b);
#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_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(void *n_arg, int search, int skip)
{
	caddr_t netmask = (caddr_t)n_arg;
	struct radix_node *x;
	caddr_t cp, cplim;
	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--;