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
hash(const void * keyarg,size_t len)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
hashkey(char * key)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 *
lookup(struct group_entry * table[],char * key)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
ngstore(struct group_entry * table[],char * key,char * data)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
mstore(struct member_entry * table[],char * key,char * data,char * domain)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