patricia.c

/*
 * Dave Plonka <plonka@doit.wisc.edu>
 *
 * This product includes software developed by the University of Michigan,
 * Merit Network, Inc., and their contributors.
 *
 * This file had been called "radix.c" in the MRT sources.
 *
 * I renamed it to "patricia.c" since it's not an implementation of a general
 * radix trie.  Also I pulled in various requirements from "prefix.c" and
 * "demo.c" so that it could be used as a standalone API.
 */

/* From copyright.txt:
 *
 * Copyright (c) 1997, 1998, 1999
 *
 *
 * The Regents of the University of Michigan ("The Regents") and Merit Network,
 * Inc.  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 Michigan, Merit
 * Network, Inc., and their contributors.
 * 4.  Neither the name of the University, Merit Network, nor the
 *     names of their 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.
 */

static char copyright[] =
"This product includes software developed by the University of Michigan, Merit"
"Network, Inc., and their contributors.";

#include <assert.h> /* assert */
#include <ctype.h> /* isdigit */
#include <errno.h> /* errno */
#include <math.h> /* sin */
#include <stddef.h> /* NULL */
#include <stdio.h> /* sprintf, fprintf, stderr */
#include <stdlib.h> /* free, atol, calloc */
#include <string.h> /* memcpy, strchr, strlen */
#include <arpa/inet.h> /* for inet_addr */
#include <sys/types.h> /* for u_short, etc. */

#include "patricia.h"

#define Delete free

/* { from prefix.c */

/* prefix_tochar
 * convert prefix information to bytes
 */
u_char *
prefix_tochar (prefix_t * prefix)
{
    if (prefix == NULL)
	return (NULL);

    return ((u_char *) & prefix->add.sin);
}

int
comp_with_mask (void *addr, void *dest, u_int mask)
{

    if ( /* mask/8 == 0 || */ memcmp (addr, dest, mask / 8) == 0) {
	int n = mask / 8;
	int m = ((-1) << (8 - (mask % 8)));

	if (mask % 8 == 0 || (((u_char *)addr)[n] & m) == (((u_char *)dest)[n] & m))
	    return (1);
    }
    return (0);
}

/* inet_pton substitute implementation
 * Uses inet_addr to convert an IP address in dotted decimal notation into
 * unsigned long and copies the result to dst.
 * Only supports AF_INET.  Follows standard error return conventions of
 * inet_pton.
 */
int
local_inet_pton (int af, const char *src, void *dst)
{
    u_long result;

    if (af == AF_INET) {
	result = inet_addr(src);
	if (result == -1)
	    return 0;
	else {
			memcpy (dst, &result, 4);
	    return 1;
		}
	}
#ifdef NT
	else if (af == AF_INET6) {
		struct in6_addr Address;
		return (inet6_addr(src, &Address));
	}
#else
    else {
   	errno = EAFNOSUPPORT;
	return -1;
    }
#endif /* NT */
}

/* this allows imcomplete prefix */
int
my_inet_pton (int af, const char *src, void *dst)
{
    if (af == AF_INET) {
        int i, c, val;
        u_char xp[4] = {0, 0, 0, 0};

        for (i = 0; ; i++) {
	    c = *src++;
	    if (!isdigit (c))
		return (-1);
	    val = 0;
	    do {
		val = val * 10 + c - '0';
		if (val > 255)
		    return (0);
		c = *src++;
	    } while (c && isdigit (c));
            xp[i] = val;
	    if (c == '\0')
		break;
            if (c != '.')
                return (0);
	    if (i >= 3)
		return (0);
        }
	memcpy (dst, xp, 4);
        return (1);
    } else if (af == AF_INET6) {
        return (local_inet_pton (af, src, dst));
    } else {
#ifndef NT
	errno = EAFNOSUPPORT;
#endif /* NT */
	return -1;
    }
}

/*
 * convert prefix information to ascii string with length
 * thread safe and (almost) re-entrant implementation
 */
char *
prefix_toa2x (prefix_t *prefix, char *buff, int with_len)
{
    if (prefix == NULL)
	return ("(Null)");
    assert (prefix->ref_count >= 0);
    if (buff == NULL) {

        struct buffer {
            char buffs[16][48+5];
            u_int i;
        } *buffp;

#    if 0
	THREAD_SPECIFIC_DATA (struct buffer, buffp, 1);
#    else
        { /* for scope only */
	   static struct buffer local_buff;
           buffp = &local_buff;
	}
#    endif
	if (buffp == NULL) {
	    /* XXX should we report an error? */
	    return (NULL);
	}

	buff = buffp->buffs[buffp->i++%16];
    }
    if (prefix->family == AF_INET) {
	u_char *a;
	assert (prefix->bitlen <= 32);
	a = prefix_touchar (prefix);
	if (with_len) {
	    sprintf (buff, "%d.%d.%d.%d/%d", a[0], a[1], a[2], a[3],
		     prefix->bitlen);
	}
	else {
	    sprintf (buff, "%d.%d.%d.%d", a[0], a[1], a[2], a[3]);
	}
	return (buff);
    }
    else if (prefix->family == AF_INET6) {
	char *r;
	r = (char *) inet_ntop (AF_INET6, &prefix->add.sin6, buff, 48 /* a guess value */ );
	if (r && with_len) {
	    assert (prefix->bitlen <= 128);
	    sprintf (buff + strlen (buff), "/%d", prefix->bitlen);
	}
	return (buff);
    }
    else
	return (NULL);
}

/* prefix_toa2
 * convert prefix information to ascii string
 */
char *
prefix_toa2 (prefix_t *prefix, char *buff)
{
    return (prefix_toa2x (prefix, buff, 0));
}

/* prefix_toa
 */
char *
prefix_toa (prefix_t * prefix)
{
    return (prefix_toa2 (prefix, (char *) NULL));
}

prefix_t *
New_Prefix2 (int family, void *dest, int bitlen, prefix_t *prefix)
{
    int dynamic_allocated = 0;
    int default_bitlen = 32;

    if (family == AF_INET6) {
        default_bitlen = 128;
	if (prefix == NULL) {
            prefix = calloc(1, sizeof (prefix_t));
	    dynamic_allocated++;
	}
	memcpy (&prefix->add.sin6, dest, 16);
    }
    else
    if (family == AF_INET) {
		if (prefix == NULL) {
#ifndef NT
            prefix = calloc(1, sizeof (prefix4_t));
#else
			//for some reason, compiler is getting
			//prefix4_t size incorrect on NT
			prefix = calloc(1, sizeof (prefix_t));
#endif /* NT */

			dynamic_allocated++;
		}
		memcpy (&prefix->add.sin, dest, 4);
    }
    else {
        return (NULL);
    }

    prefix->bitlen = (bitlen >= 0)? bitlen: default_bitlen;
    prefix->family = family;
    prefix->ref_count = 0;
    if (dynamic_allocated) {
        prefix->ref_count++;
   }
/* fprintf(stderr, "[C %s, %d]\n", prefix_toa (prefix), prefix->ref_count); */
    return (prefix);
}

prefix_t *
New_Prefix (int family, void *dest, int bitlen)
{
    return (New_Prefix2 (family, dest, bitlen, NULL));
}

/* ascii2prefix
 */
prefix_t *
ascii2prefix (int family, char *string)
{
    u_long bitlen, maxbitlen = 0;
    char *cp;
    struct in_addr sin;
    struct in6_addr sin6;
    int result;
    char save[MAXLINE];

    if (string == NULL)
		return (NULL);

    /* easy way to handle both families */
    if (family == 0) {
       family = AF_INET;
       if (strchr (string, ':')) family = AF_INET6;
    }

    if (family == AF_INET) {
		maxbitlen = 32;
    }
    else if (family == AF_INET6) {
		maxbitlen = 128;
    }

    if ((cp = strchr (string, '/')) != NULL) {
		bitlen = atol (cp + 1);
		/* *cp = '\0'; */
		/* copy the string to save. Avoid destroying the string */
		assert (cp - string < MAXLINE);
		memcpy (save, string, cp - string);
		save[cp - string] = '\0';
		string = save;
		if (bitlen > maxbitlen)
			bitlen = maxbitlen;
		}
		else {
			bitlen = maxbitlen;
		}

		if (family == AF_INET) {
			if ((result = my_inet_pton (AF_INET, string, &sin)) <= 0)
				return (NULL);
			return (New_Prefix (AF_INET, &sin, bitlen));
		}

		else if (family == AF_INET6) {
// Get rid of this with next IPv6 upgrade
#if defined(NT) && !defined(HAVE_INET_NTOP)
			inet6_addr(string, &sin6);
			return (New_Prefix (AF_INET6, &sin6, bitlen));
#else
			if ((result = local_inet_pton (AF_INET6, string, &sin6)) <= 0)
				return (NULL);
#endif /* NT */
			return (New_Prefix (AF_INET6, &sin6, bitlen));
		}
		else
			return (NULL);
}

prefix_t *
Ref_Prefix (prefix_t * prefix)
{
    if (prefix == NULL)
	return (NULL);
    if (prefix->ref_count == 0) {
	/* make a copy in case of a static prefix */
        return (New_Prefix2 (prefix->family, &prefix->add, prefix->bitlen, NULL));
    }
    prefix->ref_count++;
/* fprintf(stderr, "[A %s, %d]\n", prefix_toa (prefix), prefix->ref_count); */
    return (prefix);
}

void
Deref_Prefix (prefix_t * prefix)
{
    if (prefix == NULL)
	return;
    /* for secure programming, raise an assert. no static prefix can call this */
    assert (prefix->ref_count > 0);

    prefix->ref_count--;
    assert (prefix->ref_count >= 0);
    if (prefix->ref_count <= 0) {
	Delete (prefix);
	return;
    }
}

/* } */

/* #define PATRICIA_DEBUG 1 */

static int num_active_patricia = 0;

/* these routines support continuous mask only */

patricia_tree_t *
New_Patricia (int maxbits)
{
    patricia_tree_t *patricia = calloc(1, sizeof *patricia);

    patricia->maxbits = maxbits;
    patricia->head = NULL;
    patricia->num_active_node = 0;
    assert (maxbits <= PATRICIA_MAXBITS); /* XXX */
    num_active_patricia++;
    return (patricia);
}


/*
 * if func is supplied, it will be called as func(node->data)
 * before deleting the node
 */

void
Clear_Patricia (patricia_tree_t *patricia, void_fn_t func)
{
    assert (patricia);
    if (patricia->head) {

        patricia_node_t *Xstack[PATRICIA_MAXBITS+1];
        patricia_node_t **Xsp = Xstack;
        patricia_node_t *Xrn = patricia->head;

        while (Xrn) {
            patricia_node_t *l = Xrn->l;
            patricia_node_t *r = Xrn->r;

    	    if (Xrn->prefix) {
		Deref_Prefix (Xrn->prefix);
		if (Xrn->data && func)
	    	    func (Xrn->data);
    	    }
    	    else {
		assert (Xrn->data == NULL);
    	    }
    	    Delete (Xrn);
	    patricia->num_active_node--;

            if (l) {
                if (r) {
                    *Xsp++ = r;
                }
                Xrn = l;
            } else if (r) {
                Xrn = r;
            } else if (Xsp != Xstack) {
                Xrn = *(--Xsp);
            } else {
                Xrn = (patricia_node_t *) 0;
            }
        }
    }
    assert (patricia->num_active_node == 0);
    /* Delete (patricia); */
}


void
Destroy_Patricia (patricia_tree_t *patricia, void_fn_t func)
{
    Clear_Patricia (patricia, func);
    Delete (patricia);
    num_active_patricia--;
}


/*
 * if func is supplied, it will be called as func(node->prefix, node->data)
 */

void
patricia_process (patricia_tree_t *patricia, void_fn_t func)
{
    patricia_node_t *node;
    assert (func);

    PATRICIA_WALK (patricia->head, node) {
	func (node->prefix, node->data);
    } PATRICIA_WALK_END;
}


patricia_node_t *
patricia_search_exact (patricia_tree_t *patricia, prefix_t *prefix)
{
    patricia_node_t *node;
    u_char *addr;
    u_int bitlen;

    assert (patricia);
    assert (prefix);
    assert (prefix->bitlen <= patricia->maxbits);

    if (patricia->head == NULL)
	return (NULL);

    node = patricia->head;
    addr = prefix_touchar (prefix);
    bitlen = prefix->bitlen;

    while (node->bit < bitlen) {

	if (BIT_TEST (addr[node->bit >> 3], 0x80 >> (node->bit & 0x07))) {
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_search_exact: take right %s/%d\n",
	                 prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_search_exact: take right at %d\n",
			 node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->r;
	}
	else {
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_search_exact: take left %s/%d\n",
	                 prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_search_exact: take left at %d\n",
			 node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->l;
	}

	if (node == NULL)
	    return (NULL);
    }

#ifdef PATRICIA_DEBUG
    if (node->prefix)
        fprintf (stderr, "patricia_search_exact: stop at %s/%d\n",
	         prefix_toa (node->prefix), node->prefix->bitlen);
    else
        fprintf (stderr, "patricia_search_exact: stop at %d\n", node->bit);
#endif /* PATRICIA_DEBUG */
    if (node->bit > bitlen || node->prefix == NULL)
	return (NULL);
    assert (node->bit == bitlen);
    assert (node->bit == node->prefix->bitlen);
    if (comp_with_mask (prefix_tochar (node->prefix), prefix_tochar (prefix),
			bitlen)) {
#ifdef PATRICIA_DEBUG
        fprintf (stderr, "patricia_search_exact: found %s/%d\n",
	         prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	return (node);
    }
    return (NULL);
}


/* if inclusive != 0, "best" may be the given prefix itself */
patricia_node_t *
patricia_search_best2 (patricia_tree_t *patricia, prefix_t *prefix, int inclusive)
{
    patricia_node_t *node;
    patricia_node_t *stack[PATRICIA_MAXBITS + 1];
    u_char *addr;
    u_int bitlen;
    int cnt = 0;

    assert (patricia);
    assert (prefix);
    assert (prefix->bitlen <= patricia->maxbits);

    if (patricia->head == NULL)
	return (NULL);

    node = patricia->head;
    addr = prefix_touchar (prefix);
    bitlen = prefix->bitlen;

    while (node->bit < bitlen) {

	if (node->prefix) {
#ifdef PATRICIA_DEBUG
            fprintf (stderr, "patricia_search_best: push %s/%d\n",
	             prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	    stack[cnt++] = node;
	}

	if (BIT_TEST (addr[node->bit >> 3], 0x80 >> (node->bit & 0x07))) {
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_search_best: take right %s/%d\n",
	                 prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_search_best: take right at %d\n",
			 node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->r;
	}
	else {
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_search_best: take left %s/%d\n",
	                 prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_search_best: take left at %d\n",
			 node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->l;
	}

	if (node == NULL)
	    break;
    }

    if (inclusive && node && node->prefix)
	stack[cnt++] = node;

#ifdef PATRICIA_DEBUG
    if (node == NULL)
        fprintf (stderr, "patricia_search_best: stop at null\n");
    else if (node->prefix)
        fprintf (stderr, "patricia_search_best: stop at %s/%d\n",
	         prefix_toa (node->prefix), node->prefix->bitlen);
    else
        fprintf (stderr, "patricia_search_best: stop at %d\n", node->bit);
#endif /* PATRICIA_DEBUG */

    if (cnt <= 0)
	return (NULL);

    while (--cnt >= 0) {
	node = stack[cnt];
#ifdef PATRICIA_DEBUG
        fprintf (stderr, "patricia_search_best: pop %s/%d\n",
	         prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	if (comp_with_mask (prefix_tochar (node->prefix),
			    prefix_tochar (prefix),
			    node->prefix->bitlen)) {
#ifdef PATRICIA_DEBUG
            fprintf (stderr, "patricia_search_best: found %s/%d\n",
	             prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	    return (node);
	}
    }
    return (NULL);
}


patricia_node_t *
patricia_search_best (patricia_tree_t *patricia, prefix_t *prefix)
{
    return (patricia_search_best2 (patricia, prefix, 1));
}


patricia_node_t *
patricia_lookup (patricia_tree_t *patricia, prefix_t *prefix)
{
    patricia_node_t *node, *new_node, *parent, *glue;
    u_char *addr, *test_addr;
    u_int bitlen, check_bit, differ_bit;
    int i, j, r;

    assert (patricia);
    assert (prefix);
    assert (prefix->bitlen <= patricia->maxbits);

    if (patricia->head == NULL) {
	node = calloc(1, sizeof *node);
	node->bit = prefix->bitlen;
	node->prefix = Ref_Prefix (prefix);
	node->parent = NULL;
	node->l = node->r = NULL;
	node->data = NULL;
	patricia->head = node;
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_lookup: new_node #0 %s/%d (head)\n",
		 prefix_toa (prefix), prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	patricia->num_active_node++;
	return (node);
    }

    addr = prefix_touchar (prefix);
    bitlen = prefix->bitlen;
    node = patricia->head;

    while (node->bit < bitlen || node->prefix == NULL) {

	if (node->bit < patricia->maxbits &&
	    BIT_TEST (addr[node->bit >> 3], 0x80 >> (node->bit & 0x07))) {
	    if (node->r == NULL)
		break;
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_lookup: take right %s/%d\n",
	                 prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_lookup: take right at %d\n", node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->r;
	}
	else {
	    if (node->l == NULL)
		break;
#ifdef PATRICIA_DEBUG
	    if (node->prefix)
    	        fprintf (stderr, "patricia_lookup: take left %s/%d\n",
	             prefix_toa (node->prefix), node->prefix->bitlen);
	    else
    	        fprintf (stderr, "patricia_lookup: take left at %d\n", node->bit);
#endif /* PATRICIA_DEBUG */
	    node = node->l;
	}

	assert (node);
    }

    assert (node->prefix);
#ifdef PATRICIA_DEBUG
    fprintf (stderr, "patricia_lookup: stop at %s/%d\n",
	     prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */

    test_addr = prefix_touchar (node->prefix);
    /* find the first bit different */
    check_bit = (node->bit < bitlen)? node->bit: bitlen;
    differ_bit = 0;
    for (i = 0; i*8 < check_bit; i++) {
	if ((r = (addr[i] ^ test_addr[i])) == 0) {
	    differ_bit = (i + 1) * 8;
	    continue;
	}
	/* I know the better way, but for now */
	for (j = 0; j < 8; j++) {
	    if (BIT_TEST (r, (0x80 >> j)))
		break;
	}
	/* must be found */
	assert (j < 8);
	differ_bit = i * 8 + j;
	break;
    }
    if (differ_bit > check_bit)
	differ_bit = check_bit;
#ifdef PATRICIA_DEBUG
    fprintf (stderr, "patricia_lookup: differ_bit %d\n", differ_bit);
#endif /* PATRICIA_DEBUG */

    parent = node->parent;
    while (parent && parent->bit >= differ_bit) {
	node = parent;
	parent = node->parent;
#ifdef PATRICIA_DEBUG
	if (node->prefix)
            fprintf (stderr, "patricia_lookup: up to %s/%d\n",
	             prefix_toa (node->prefix), node->prefix->bitlen);
	else
            fprintf (stderr, "patricia_lookup: up to %d\n", node->bit);
#endif /* PATRICIA_DEBUG */
    }

    if (differ_bit == bitlen && node->bit == bitlen) {
	if (node->prefix) {
#ifdef PATRICIA_DEBUG
    	    fprintf (stderr, "patricia_lookup: found %s/%d\n",
		     prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	    return (node);
	}
	node->prefix = Ref_Prefix (prefix);
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_lookup: new node #1 %s/%d (glue mod)\n",
		 prefix_toa (prefix), prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	assert (node->data == NULL);
	return (node);
    }

    new_node = calloc(1, sizeof *new_node);
    new_node->bit = prefix->bitlen;
    new_node->prefix = Ref_Prefix (prefix);
    new_node->parent = NULL;
    new_node->l = new_node->r = NULL;
    new_node->data = NULL;
    patricia->num_active_node++;

    if (node->bit == differ_bit) {
	new_node->parent = node;
	if (node->bit < patricia->maxbits &&
	    BIT_TEST (addr[node->bit >> 3], 0x80 >> (node->bit & 0x07))) {
	    assert (node->r == NULL);
	    node->r = new_node;
	}
	else {
	    assert (node->l == NULL);
	    node->l = new_node;
	}
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_lookup: new_node #2 %s/%d (child)\n",
		 prefix_toa (prefix), prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	return (new_node);
    }

    if (bitlen == differ_bit) {
	if (bitlen < patricia->maxbits &&
	    BIT_TEST (test_addr[bitlen >> 3], 0x80 >> (bitlen & 0x07))) {
	    new_node->r = node;
	}
	else {
	    new_node->l = node;
	}
	new_node->parent = node->parent;
	if (node->parent == NULL) {
	    assert (patricia->head == node);
	    patricia->head = new_node;
	}
	else if (node->parent->r == node) {
	    node->parent->r = new_node;
	}
	else {
	    node->parent->l = new_node;
	}
	node->parent = new_node;
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_lookup: new_node #3 %s/%d (parent)\n",
		 prefix_toa (prefix), prefix->bitlen);
#endif /* PATRICIA_DEBUG */
    }
    else {
        glue = calloc(1, sizeof *glue);
        glue->bit = differ_bit;
        glue->prefix = NULL;
        glue->parent = node->parent;
        glue->data = NULL;
        patricia->num_active_node++;
	if (differ_bit < patricia->maxbits &&
	    BIT_TEST (addr[differ_bit >> 3], 0x80 >> (differ_bit & 0x07))) {
	    glue->r = new_node;
	    glue->l = node;
	}
	else {
	    glue->r = node;
	    glue->l = new_node;
	}
	new_node->parent = glue;

	if (node->parent == NULL) {
	    assert (patricia->head == node);
	    patricia->head = glue;
	}
	else if (node->parent->r == node) {
	    node->parent->r = glue;
	}
	else {
	    node->parent->l = glue;
	}
	node->parent = glue;
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_lookup: new_node #4 %s/%d (glue+node)\n",
		 prefix_toa (prefix), prefix->bitlen);
#endif /* PATRICIA_DEBUG */
    }
    return (new_node);
}


void
patricia_remove (patricia_tree_t *patricia, patricia_node_t *node)
{
    patricia_node_t *parent, *child;

    assert (patricia);
    assert (node);

    if (node->r && node->l) {
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_remove: #0 %s/%d (r & l)\n",
		 prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */

	/* this might be a placeholder node -- have to check and make sure
	 * there is a prefix aossciated with it ! */
	if (node->prefix != NULL)
	  Deref_Prefix (node->prefix);
	node->prefix = NULL;
	/* Also I needed to clear data pointer -- masaki */
	node->data = NULL;
	return;
    }

    if (node->r == NULL && node->l == NULL) {
#ifdef PATRICIA_DEBUG
	fprintf (stderr, "patricia_remove: #1 %s/%d (!r & !l)\n",
		 prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
	parent = node->parent;
	Deref_Prefix (node->prefix);
	Delete (node);
        patricia->num_active_node--;

	if (parent == NULL) {
	    assert (patricia->head == node);
	    patricia->head = NULL;
	    return;
	}

	if (parent->r == node) {
	    parent->r = NULL;
	    child = parent->l;
	}
	else {
	    assert (parent->l == node);
	    parent->l = NULL;
	    child = parent->r;
	}

	if (parent->prefix)
	    return;

	/* we need to remove parent too */

	if (parent->parent == NULL) {
	    assert (patricia->head == parent);
	    patricia->head = child;
	}
	else if (parent->parent->r == parent) {
	    parent->parent->r = child;
	}
	else {
	    assert (parent->parent->l == parent);
	    parent->parent->l = child;
	}
	child->parent = parent->parent;
	Delete (parent);
        patricia->num_active_node--;
	return;
    }

#ifdef PATRICIA_DEBUG
    fprintf (stderr, "patricia_remove: #2 %s/%d (r ^ l)\n",
	     prefix_toa (node->prefix), node->prefix->bitlen);
#endif /* PATRICIA_DEBUG */
    if (node->r) {
	child = node->r;
    }
    else {
	assert (node->l);
	child = node->l;
    }
    parent = node->parent;
    child->parent = parent;

    Deref_Prefix (node->prefix);
    Delete (node);
    patricia->num_active_node--;

    if (parent == NULL) {
	assert (patricia->head == node);
	patricia->head = child;
	return;
    }

    if (parent->r == node) {
	parent->r = child;
    }
    else {
        assert (parent->l == node);
	parent->l = child;
    }
}

/* { from demo.c */

patricia_node_t *
make_and_lookup (patricia_tree_t *tree, char *string)
{
    prefix_t *prefix;
    patricia_node_t *node;

    prefix = ascii2prefix (AF_INET, string);
    printf ("make_and_lookup: %s/%d\n", prefix_toa (prefix), prefix->bitlen);
    node = patricia_lookup (tree, prefix);
    Deref_Prefix (prefix);
    return (node);
}

patricia_node_t *
try_search_exact (patricia_tree_t *tree, char *string)
{
    prefix_t *prefix;
    patricia_node_t *node;

    prefix = ascii2prefix (AF_INET, string);
    printf ("try_search_exact: %s/%d\n", prefix_toa (prefix), prefix->bitlen);
    if ((node = patricia_search_exact (tree, prefix)) == NULL) {
        printf ("try_search_exact: not found\n");
    }
    else {
        printf ("try_search_exact: %s/%d found\n",
	        prefix_toa (node->prefix), node->prefix->bitlen);
    }
    Deref_Prefix (prefix);
    return (node);
}

void
lookup_then_remove (patricia_tree_t *tree, char *string)
{
    patricia_node_t *node;

    if ((node = try_search_exact (tree, string)))
        patricia_remove (tree, node);
}

patricia_node_t *
try_search_best (patricia_tree_t *tree, char *string)
{
    prefix_t *prefix;
    patricia_node_t *node;

    prefix = ascii2prefix (AF_INET, string);
    printf ("try_search_best: %s/%d\n", prefix_toa (prefix), prefix->bitlen);
    if ((node = patricia_search_best (tree, prefix)) == NULL)
        printf ("try_search_best: not found\n");
    else
        printf ("try_search_best: %s/%d found\n",
	        prefix_toa (node->prefix), node->prefix->bitlen);
    Deref_Prefix (prefix);
    return 0; // [RS] What is supposed to be returned here?
 }

/* } */