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