1 /* $OpenBSD: hash.c,v 1.7 2009/10/27 23:59:58 deraadt Exp $ */ 2 /* 3 * Copyright (c) 1995 4 * Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Bill Paul. 17 * 4. Neither the name of the author nor the names of any co-contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: hash.c,v 1.4 1997/02/22 14:22:01 peter Exp $ 34 */ 35 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <sys/types.h> 40 #include "hash.h" 41 42 /* 43 * This hash function is stolen directly from the 44 * Berkeley DB package. It already exists inside libc, but 45 * it's declared static which prevents us from calling it 46 * from here. 47 */ 48 /* 49 * OZ's original sdbm hash 50 */ 51 static u_int32_t 52 hash(const void *keyarg, size_t len) 53 { 54 const u_char *key; 55 size_t loop; 56 u_int32_t h; 57 58 #define HASHC h = *key++ + 65599 * h 59 60 h = 0; 61 key = keyarg; 62 if (len > 0) { 63 loop = (len + 8 - 1) >> 3; 64 65 switch (len & (8 - 1)) { 66 case 0: 67 do { 68 HASHC; 69 /* FALLTHROUGH */ 70 case 7: 71 HASHC; 72 /* FALLTHROUGH */ 73 case 6: 74 HASHC; 75 /* FALLTHROUGH */ 76 case 5: 77 HASHC; 78 /* FALLTHROUGH */ 79 case 4: 80 HASHC; 81 /* FALLTHROUGH */ 82 case 3: 83 HASHC; 84 /* FALLTHROUGH */ 85 case 2: 86 HASHC; 87 /* FALLTHROUGH */ 88 case 1: 89 HASHC; 90 } while (--loop); 91 } 92 } 93 return (h); 94 } 95 96 /* 97 * Generate a hash value for a given key (character string). 98 * We mask off all but the lower 8 bits since our table array 99 * can only hold 256 elements. 100 */ 101 static u_int32_t 102 hashkey(char *key) 103 { 104 105 if (key == NULL) 106 return (-1); 107 return(hash(key, strlen(key)) & HASH_MASK); 108 } 109 110 /* Find an entry in the hash table (may be hanging off a linked list). */ 111 char * 112 lookup(struct group_entry *table[], char *key) 113 { 114 struct group_entry *cur; 115 116 cur = table[hashkey(key)]; 117 118 while (cur) { 119 if (!strcmp(cur->key, key)) 120 return(cur->data); 121 cur = cur->next; 122 } 123 124 return(NULL); 125 } 126 127 /* 128 * Store an entry in the main netgroup hash table. Here's how this 129 * works: the table can only be so big when we initialize it (TABLESIZE) 130 * but the number of netgroups in the /etc/netgroup file could easily be 131 * much larger than the table. Since our hash values are adjusted to 132 * never be greater than TABLESIZE too, this means it won't be long before 133 * we find ourselves with two keys that hash to the same value. 134 * 135 * One way to deal with this is to malloc(2) a second table and start 136 * doing indirection, but this is a pain in the butt and it's not worth 137 * going to all that trouble for a dinky little program like this. Instead, 138 * we turn each table entry into a linked list and simply link keys 139 * with the same hash value together at the same index location within 140 * the table. 141 * 142 * That's a lot of comment for such a small piece of code, isn't it. 143 */ 144 void 145 ngstore(struct group_entry *table[], char *key, char *data) 146 { 147 struct group_entry *new; 148 u_int32_t i; 149 150 i = hashkey(key); 151 152 new = malloc(sizeof(struct group_entry)); 153 new->key = strdup(key); 154 new->data = strdup(data); 155 new->next = table[i]; 156 table[i] = new; 157 } 158 159 /* 160 * Store a group member entry and/or update its grouplist. This is 161 * a bit more complicated than the previous function since we have to 162 * maintain not only the hash table of group members, each group member 163 * structure also has a linked list of groups hung off it. If handed 164 * a member name that we haven't encountered before, we have to do 165 * two things: add that member to the table (possibly hanging them 166 * off the end of a linked list, as above), and add a group name to 167 * the member's grouplist list. If we're handed a name that already has 168 * an entry in the table, then we just have to do one thing, which is 169 * to update its grouplist. 170 */ 171 void 172 mstore(struct member_entry *table[], char *key, char *data, char *domain) 173 { 174 struct member_entry *cur, *new; 175 struct grouplist *tmp,*p; 176 u_int32_t i; 177 178 i = hashkey(key); 179 cur = table[i]; 180 181 tmp = malloc(sizeof(struct grouplist)); 182 tmp->groupname = strdup(data); 183 tmp->next = NULL; 184 185 /* Check if all we have to do is insert a new groupname. */ 186 while (cur) { 187 if (!strcmp(cur->key, key) && !strcmp(cur->domain, domain)) { 188 p = cur->groups; 189 while (p) { 190 if (!strcmp(p->groupname, data)) { 191 free(tmp->groupname); 192 free(tmp); 193 return; 194 } 195 p = p->next; 196 } 197 tmp->next = cur->groups; 198 cur->groups = tmp; 199 return; 200 } 201 cur = cur->next; 202 } 203 204 /* Didn't find a match -- add the whole mess to the table. */ 205 new = malloc(sizeof(struct member_entry)); 206 new->key = strdup(key); 207 new->domain = strdup(domain); 208 new->groups = tmp; 209 new->next = table[i]; 210 table[i] = new; 211 } 212