1 /* $OpenBSD: hash.c,v 1.9 2004/05/10 15:30:47 deraadt Exp $ */ 2 3 /* Routines for manipulating hash tables... */ 4 5 /* 6 * Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of The Internet Software Consortium nor the names 19 * of its contributors may be used to endorse or promote products derived 20 * from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND 23 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 24 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 26 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR 27 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 30 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 31 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * This software has been written for the Internet Software Consortium 37 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie 38 * Enterprises. To learn more about the Internet Software Consortium, 39 * see ``http://www.vix.com/isc''. To learn more about Vixie 40 * Enterprises, see ``http://www.vix.com''. 41 */ 42 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD$"); 45 46 #include "dhcpd.h" 47 48 static int do_hash(unsigned char *, int, int); 49 50 struct hash_table * 51 new_hash(void) 52 { 53 struct hash_table *rv = new_hash_table(DEFAULT_HASH_SIZE); 54 55 if (!rv) 56 return (rv); 57 memset(&rv->buckets[0], 0, 58 DEFAULT_HASH_SIZE * sizeof(struct hash_bucket *)); 59 return (rv); 60 } 61 62 static int 63 do_hash(unsigned char *name, int len, int size) 64 { 65 unsigned char *s = name; 66 int accum = 0, i = len; 67 68 while (i--) { 69 /* Add the character in... */ 70 accum += *s++; 71 /* Add carry back in... */ 72 while (accum > 255) 73 accum = (accum & 255) + (accum >> 8); 74 } 75 return (accum % size); 76 } 77 78 void add_hash(struct hash_table *table, unsigned char *name, int len, 79 unsigned char *pointer) 80 { 81 struct hash_bucket *bp; 82 int hashno; 83 84 if (!table) 85 return; 86 if (!len) 87 len = strlen((char *)name); 88 89 hashno = do_hash(name, len, table->hash_count); 90 bp = new_hash_bucket(); 91 92 if (!bp) { 93 warning("Can't add %s to hash table.", name); 94 return; 95 } 96 bp->name = name; 97 bp->value = pointer; 98 bp->next = table->buckets[hashno]; 99 bp->len = len; 100 table->buckets[hashno] = bp; 101 } 102 103 unsigned char * 104 hash_lookup(struct hash_table *table, unsigned char *name, int len) 105 { 106 struct hash_bucket *bp; 107 int hashno; 108 109 if (!table) 110 return (NULL); 111 112 if (!len) 113 len = strlen((char *)name); 114 115 hashno = do_hash(name, len, table->hash_count); 116 117 for (bp = table->buckets[hashno]; bp; bp = bp->next) 118 if (len == bp->len && !memcmp(bp->name, name, len)) 119 return (bp->value); 120 121 return (NULL); 122 } 123