/* 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 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''. */ #define lint #ifndef lint static char copyright[] = "$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"; #endif /* not lint */ #include static __inline int do_hash PROTO ((unsigned char *, int, int)); struct hash_table *new_hash () { struct hash_table *rv = new_hash_table (DEFAULT_HASH_SIZE); 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) 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 (); 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; }