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166 lines
4.6 KiB
C
166 lines
4.6 KiB
C
/* hash.c
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Routines for manipulating hash tables... */
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/*
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* Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This software has been written for the Internet Software Consortium
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* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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* Enterprises. To learn more about the Internet Software Consortium,
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* see ``http://www.vix.com/isc''. To learn more about Vixie
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* Enterprises, see ``http://www.vix.com''.
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*/
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#define lint
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#ifndef lint
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static char copyright[] =
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"$Id: hash.c,v 1.9.2.3 1999/04/09 17:39:41 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium. All rights reserved.\n";
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#endif /* not lint */
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#include <rosdhcp.h>
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static __inline int do_hash PROTO ((unsigned char *, int, int));
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struct hash_table *new_hash ()
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{
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struct hash_table *rv = new_hash_table (DEFAULT_HASH_SIZE);
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if (!rv)
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return rv;
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memset (&rv -> buckets [0], 0,
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DEFAULT_HASH_SIZE * sizeof (struct hash_bucket *));
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return rv;
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}
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static __inline int do_hash (name, len, size)
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unsigned char *name;
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int len;
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int size;
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{
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register int accum = 0;
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register unsigned char *s = name;
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int i = len;
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while (i--) {
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/* Add the character in... */
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accum += *s++;
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/* Add carry back in... */
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while (accum > 255) {
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accum = (accum & 255) + (accum >> 8);
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}
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}
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return accum % size;
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}
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void add_hash (table, name, len, pointer)
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struct hash_table *table;
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int len;
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unsigned char *name;
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unsigned char *pointer;
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{
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int hashno;
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struct hash_bucket *bp;
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if (!table)
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return;
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if (!len)
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len = strlen ((char *)name);
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hashno = do_hash (name, len, table -> hash_count);
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bp = new_hash_bucket ();
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if (!bp) {
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warn ("Can't add %s to hash table.", name);
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return;
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}
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bp -> name = name;
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bp -> value = pointer;
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bp -> next = table -> buckets [hashno];
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bp -> len = len;
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table -> buckets [hashno] = bp;
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}
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void delete_hash_entry (table, name, len)
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struct hash_table *table;
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int len;
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unsigned char *name;
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{
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int hashno;
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struct hash_bucket *bp, *pbp = (struct hash_bucket *)0;
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if (!table)
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return;
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if (!len)
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len = strlen ((char *)name);
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hashno = do_hash (name, len, table -> hash_count);
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/* Go through the list looking for an entry that matches;
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if we find it, delete it. */
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for (bp = table -> buckets [hashno]; bp; bp = bp -> next) {
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if ((!bp -> len &&
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!strcmp ((char *)bp -> name, (char *)name)) ||
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(bp -> len == len &&
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!memcmp (bp -> name, name, len))) {
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if (pbp) {
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pbp -> next = bp -> next;
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} else {
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table -> buckets [hashno] = bp -> next;
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}
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free_hash_bucket (bp, "delete_hash_entry");
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break;
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}
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pbp = bp; /* jwg, 9/6/96 - nice catch! */
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}
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}
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unsigned char *hash_lookup (table, name, len)
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struct hash_table *table;
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unsigned char *name;
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int len;
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{
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int hashno;
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struct hash_bucket *bp;
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if (!table)
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return (unsigned char *)0;
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if (!len)
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len = strlen ((char *)name);
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hashno = do_hash (name, len, table -> hash_count);
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for (bp = table -> buckets [hashno]; bp; bp = bp -> next) {
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if (len == bp -> len && !memcmp (bp -> name, name, len))
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return bp -> value;
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}
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return (unsigned char *)0;
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}
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