/* hash.c Routines for manipulating hash tables... */ /* * Copyright (c) 1995-2000 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 and Nominum, Inc. * To learn more about the Internet Software Consortium, see * ``http://www.isc.org/''. To learn more about Vixie Enterprises, * see ``http://www.vix.com''. To learn more about Nominum, Inc., see * ``http://www.nominum.com''. */ #ifndef lint static char copyright[] = "$Id: hash.c,v 1.2 2000/04/23 02:47:58 sommerfeld Exp $ Copyright (c) 1995-2000 The Internet Software Consortium. All rights reserved.\n"; #endif /* not lint */ #include "dhcpd.h" #include static int do_hash PROTO ((const unsigned char *, unsigned, unsigned)); static int do_case_hash PROTO ((const unsigned char *, unsigned, unsigned)); struct hash_table *new_hash (hash_reference referencer, hash_dereference dereferencer, int casep) { struct hash_table *rv = new_hash_table (DEFAULT_HASH_SIZE, MDL); if (!rv) return rv; memset (&rv -> buckets [0], 0, DEFAULT_HASH_SIZE * sizeof (struct hash_bucket *)); rv -> referencer = referencer; rv -> dereferencer = dereferencer; if (casep) { rv -> cmp = casecmp; rv -> do_hash = do_case_hash; } else { rv -> cmp = (hash_comparator_t)memcmp; rv -> do_hash = do_hash; } return rv; } static int do_case_hash (name, len, size) const unsigned char *name; unsigned len; unsigned size; { register int accum = 0; register const unsigned char *s = (const unsigned char *)name; int i = len; register unsigned c; while (i--) { /* Make the hash case-insensitive. */ c = *s++; if (isascii (c) && isupper (c)) c = tolower (c); /* Add the character in... */ accum += c; /* Add carry back in... */ while (accum > 255) { accum = (accum & 255) + (accum >> 8); } } return accum % size; } static int do_hash (name, len, size) const unsigned char *name; unsigned len; unsigned size; { register int accum = 0; register const unsigned char *s = (const unsigned char *)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; unsigned len; const unsigned char *name; void *pointer; { int hashno; struct hash_bucket *bp; void *foo; if (!table) return; if (!len) len = strlen ((const char *)name); hashno = (*table -> do_hash) (name, len, table -> hash_count); bp = new_hash_bucket (MDL); if (!bp) { log_error ("Can't add %s to hash table.", name); return; } bp -> name = name; if (table -> referencer) { foo = &bp -> value; (*(table -> referencer)) (foo, pointer, MDL); } else 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; unsigned len; const unsigned char *name; { int hashno; struct hash_bucket *bp, *pbp = (struct hash_bucket *)0; void *foo; if (!table) return; if (!len) len = strlen ((const char *)name); hashno = (*table -> 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 ((const char *)bp -> name, (const char *)name)) || (bp -> len == len && !(*table -> cmp) (bp -> name, name, len))) { if (pbp) { pbp -> next = bp -> next; } else { table -> buckets [hashno] = bp -> next; } if (table -> dereferencer) { foo = &bp -> value; (*(table -> dereferencer)) (foo, MDL); } free_hash_bucket (bp, MDL); break; } pbp = bp; /* jwg, 9/6/96 - nice catch! */ } } void *hash_lookup (table, name, len) struct hash_table *table; const unsigned char *name; unsigned len; { int hashno; struct hash_bucket *bp; if (!table) return (unsigned char *)0; if (!len) len = strlen ((const char *)name); hashno = (*table -> do_hash) (name, len, table -> hash_count); for (bp = table -> buckets [hashno]; bp; bp = bp -> next) { if (len == bp -> len && !(*table -> cmp) (bp -> name, name, len)) return bp -> value; } return (unsigned char *)0; } int casecmp (const void *v1, const void *v2, size_t len) { unsigned i; const char *s = v1; const char *t = v2; for (i = 0; i < len; i++) { int c1, c2; if (isascii (s [i]) && isupper (s [i])) c1 = tolower (s [i]); else c1 = s [i]; if (isascii (t [i]) && isupper (t [i])) c2 = tolower (t [i]); else c2 = t [i]; if (c1 < c2) return -1; if (c1 > c2) return 1; } return 0; }