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Diffstat (limited to 'usr.sbin/dhcpd/hash.c')
| -rw-r--r-- | usr.sbin/dhcpd/hash.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/usr.sbin/dhcpd/hash.c b/usr.sbin/dhcpd/hash.c new file mode 100644 index 00000000000..b4bba2186c9 --- /dev/null +++ b/usr.sbin/dhcpd/hash.c @@ -0,0 +1,159 @@ +/* hash.c + + Routines for manipulating hash tables... */ + +/* + * Copyright (c) 1995, 1996, 1997, 1998 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''. + */ + +#include "dhcpd.h" + +static int do_hash PROTO ((unsigned 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 int do_hash (name, len, size) + unsigned char *name; + int len; + int size; +{ + register int accum = 0; + register unsigned char *s = name; + int i = len; + while (i--) { + /* 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; + unsigned char *name; + unsigned char *pointer; +{ + int hashno; + struct hash_bucket *bp; + + if (!table) + return; + if (!len) + len = strlen ((char *)name); + + 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; + unsigned char *name; +{ + int hashno; + struct hash_bucket *bp, *pbp = (struct hash_bucket *)0; + + if (!table) + return; + if (!len) + len = strlen ((char *)name); + + 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 ((char *)bp -> name, (char *)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; + unsigned char *name; + int len; +{ + int hashno; + struct hash_bucket *bp; + + if (!table) + return (unsigned char *)0; + + if (!len) + len = strlen ((char *)name); + + hashno = do_hash (name, len, table -> hash_count); + + for (bp = table -> buckets [hashno]; bp; bp = bp -> next) { + if (len == bp -> len && !memcmp (bp -> name, name, len)) + return bp -> value; + } + return (unsigned char *)0; +} |