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