1/*
2 * Copyright (c) 1995
3 *	Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by Bill Paul.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34__attribute__((__used__))
35static const char rcsid[] =
36  "$FreeBSD: src/libexec/revnetgroup/hash.c,v 1.7 2002/02/07 23:57:01 imp Exp $";
37#endif /* not lint */
38
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42#include <sys/types.h>
43#include "hash.h"
44
45/*
46 * This hash function is stolen directly from the
47 * Berkeley DB package. It already exists inside libc, but
48 * it's declared static which prevents us from calling it
49 * from here.
50 */
51/*
52 * OZ's original sdbm hash
53 */
54u_int32_t
55hash(const void *keyarg, size_t len)
56{
57	const u_char *key;
58	size_t loop;
59	u_int32_t h;
60
61#define HASHC   h = *key++ + 65599 * h
62
63	h = 0;
64	key = keyarg;
65	if (len > 0) {
66		loop = (len + 8 - 1) >> 3;
67
68		switch (len & (8 - 1)) {
69		case 0:
70			do {
71				HASHC;
72				/* FALLTHROUGH */
73		case 7:
74				HASHC;
75				/* FALLTHROUGH */
76		case 6:
77				HASHC;
78				/* FALLTHROUGH */
79		case 5:
80				HASHC;
81				/* FALLTHROUGH */
82		case 4:
83				HASHC;
84				/* FALLTHROUGH */
85		case 3:
86				HASHC;
87				/* FALLTHROUGH */
88		case 2:
89				HASHC;
90				/* FALLTHROUGH */
91		case 1:
92				HASHC;
93			} while (--loop);
94		}
95	}
96	return (h);
97}
98
99/*
100 * Generate a hash value for a given key (character string).
101 * We mask off all but the lower 8 bits since our table array
102 * can only hold 256 elements.
103 */
104u_int32_t
105hashkey(char *key)
106{
107
108	if (key == NULL)
109		return (-1);
110	return(hash((void *)key, strlen(key)) & HASH_MASK);
111}
112
113/* Find an entry in the hash table (may be hanging off a linked list). */
114char *
115lookup(struct group_entry *table[], char *key)
116{
117	struct group_entry *cur;
118
119	cur = table[hashkey(key)];
120
121	while (cur) {
122		if (!strcmp(cur->key, key))
123			return(cur->data);
124		cur = cur->next;
125	}
126
127	return(NULL);
128}
129
130/*
131 * Store an entry in the main netgroup hash table. Here's how this
132 * works: the table can only be so big when we initialize it (TABLESIZE)
133 * but the number of netgroups in the /etc/netgroup file could easily be
134 * much larger than the table. Since our hash values are adjusted to
135 * never be greater than TABLESIZE too, this means it won't be long before
136 * we find ourselves with two keys that hash to the same value.
137 *
138 * One way to deal with this is to malloc(2) a second table and start
139 * doing indirection, but this is a pain in the butt and it's not worth
140 * going to all that trouble for a dinky little program like this. Instead,
141 * we turn each table entry into a linked list and simply link keys
142 * with the same hash value together at the same index location within
143 * the table.
144 *
145 * That's a lot of comment for such a small piece of code, isn't it.
146 */
147void
148store(struct group_entry *table[], char *key, char *data)
149{
150	struct group_entry *new;
151	u_int32_t i;
152
153	i = hashkey(key);
154
155	new = (struct group_entry *)malloc(sizeof(struct group_entry));
156	new->key = strdup(key);
157	new->data = strdup(data);
158	new->next = table[i];
159	table[i] = new;
160
161	return;
162}
163
164/*
165 * Store a group member entry and/or update its grouplist. This is
166 * a bit more complicated than the previous function since we have to
167 * maintain not only the hash table of group members, each group member
168 * structure also has a linked list of groups hung off it. If handed
169 * a member name that we haven't encountered before, we have to do
170 * two things: add that member to the table (possibly hanging them
171 * off the end of a linked list, as above), and add a group name to
172 * the member's grouplist list. If we're handed a name that already has
173 * an entry in the table, then we just have to do one thing, which is
174 * to update its grouplist.
175 */
176void
177mstore(struct member_entry *table[], char *key, char *data, char *domain)
178{
179	struct member_entry *cur, *new;
180	struct grouplist *tmp,*p;
181	u_int32_t i;
182
183	i = hashkey(key);
184	cur = table[i];
185
186	tmp = (struct grouplist *)malloc(sizeof(struct grouplist));
187	tmp->groupname = strdup(data);
188	tmp->next = NULL;
189
190	/* Check if all we have to do is insert a new groupname. */
191	while (cur) {
192		if (!strcmp(cur->key, key) && !strcmp(cur->domain,domain)) {
193		  	p = cur->groups;
194			while(p) {
195				if (!strcmp(p->groupname,data))
196					return;
197				p = p->next;
198			}
199			tmp->next = cur->groups;
200			cur->groups = tmp;
201			return;
202		}
203		cur = cur->next;
204	}
205
206	/* Didn't find a match -- add the whole mess to the table. */
207	new = (struct member_entry *)malloc(sizeof(struct member_entry));
208	new->key = strdup(key);
209	new->domain = domain ? strdup(domain) : "*";
210	new->groups = tmp;
211	new->next = table[i];
212	table[i] = new;
213
214	return;
215}
216