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/* hash.c
Routines for manipulating hash tables... */
/*
* Copyright (c) 1995, 1996 The Internet Software Consortium.
* 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 Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
*
* This software has been written for the Internet Software Consortium
* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
* Enterprises. To learn more about the Internet Software Consortium,
* see ``http://www.vix.com/isc''. To learn more about Vixie
* Enterprises, see ``http://www.vix.com''.
*/
#ifndef lint
static char copyright[] =
"$Id: hash.c,v 1.9 1996/09/09 07:04:45 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
static INLINE int do_hash PROTO ((char *, int, int));
struct hash_table *new_hash ()
{
struct hash_table *rv = new_hash_table (DEFAULT_HASH_SIZE, "new_hash");
if (!rv)
return rv;
memset (&rv -> buckets [0], 0,
DEFAULT_HASH_SIZE * sizeof (struct hash_bucket *));
return rv;
}
static INLINE int do_hash (name, len, size)
char *name;
int len;
int size;
{
register int accum = 0;
register unsigned char *s = (unsigned char *)name;
int i = len;
if (i) {
while (i--) {
/* Add the character in... */
accum += *s++;
/* Add carry back in... */
while (accum > 255) {
accum = (accum & 255) + (accum >> 8);
}
}
} else {
while (*s) {
/* Add the character in... */
accum += *s++;
/* Add carry back in... */
while (accum > 255) {
accum = (accum & 255) + (accum >> 8);
}
}
}
return accum % size;
}
void add_hash (table, name, len, pointer)
struct hash_table *table;
int len;
char *name;
unsigned char *pointer;
{
int hashno;
struct hash_bucket *bp;
if (!table)
return;
hashno = do_hash (name, len, table -> hash_count);
bp = new_hash_bucket ("add_hash");
if (!bp) {
warn ("Can't add %s to hash table.", name);
return;
}
bp -> name = name;
bp -> value = pointer;
bp -> next = table -> buckets [hashno];
bp -> len = len;
table -> buckets [hashno] = bp;
}
void delete_hash_entry (table, name, len)
struct hash_table *table;
int len;
char *name;
{
int hashno;
struct hash_bucket *bp, *pbp = (struct hash_bucket *)0;
if (!table)
return;
hashno = do_hash (name, len, table -> hash_count);
/* Go through the list looking for an entry that matches;
if we find it, delete it. */
for (bp = table -> buckets [hashno]; bp; bp = bp -> next) {
if ((!bp -> len && !strcmp (bp -> name, name)) ||
(bp -> len == len &&
!memcmp (bp -> name, name, len))) {
if (pbp) {
pbp -> next = bp -> next;
} else {
table -> buckets [hashno] = bp -> next;
}
free_hash_bucket (bp, "delete_hash_entry");
break;
}
pbp = bp; /* jwg, 9/6/96 - nice catch! */
}
}
unsigned char *hash_lookup (table, name, len)
struct hash_table *table;
char *name;
int len;
{
int hashno;
struct hash_bucket *bp;
if (!table)
return (unsigned char *)0;
hashno = do_hash (name, len, table -> hash_count);
if (len) {
for (bp = table -> buckets [hashno]; bp; bp = bp -> next) {
if (len == bp -> len
&& !memcmp (bp -> name, name, len))
return bp -> value;
}
} else {
for (bp = table -> buckets [hashno]; bp; bp = bp -> next)
if (!strcmp (bp -> name, name))
return bp -> value;
}
return (unsigned char *)0;
}
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