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 * $Id$ 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 51 hash(keyarg, len) 52 const void *keyarg; 53 register size_t len; 54 { 55 register const u_char *key; 56 register size_t loop; 57 register u_int32_t h; 58 59 #define HASHC h = *key++ + 65599 * h 60 61 h = 0; 62 key = keyarg; 63 if (len > 0) { 64 loop = (len + 8 - 1) >> 3; 65 66 switch (len & (8 - 1)) { 67 case 0: 68 do { 69 HASHC; 70 /* FALLTHROUGH */ 71 case 7: 72 HASHC; 73 /* FALLTHROUGH */ 74 case 6: 75 HASHC; 76 /* FALLTHROUGH */ 77 case 5: 78 HASHC; 79 /* FALLTHROUGH */ 80 case 4: 81 HASHC; 82 /* FALLTHROUGH */ 83 case 3: 84 HASHC; 85 /* FALLTHROUGH */ 86 case 2: 87 HASHC; 88 /* FALLTHROUGH */ 89 case 1: 90 HASHC; 91 } while (--loop); 92 } 93 } 94 return (h); 95 } 96 97 /* 98 * Generate a hash value for a given key (character string). 99 * We mask off all but the lower 8 bits since our table array 100 * can only hole 256 elements. 101 */ 102 u_int32_t hashkey(key) 103 char *key; 104 { 105 106 if (key == NULL) 107 return (-1); 108 return(hash((void *)key, strlen(key)) & HASH_MASK); 109 } 110 111 /* Find an entry in the hash table (may be hanging off a linked list). */ 112 char *lookup(table, key) 113 struct group_entry *table[]; 114 char *key; 115 { 116 struct group_entry *cur; 117 118 cur = table[hashkey(key)]; 119 120 while (cur) { 121 if (!strcmp(cur->key, key)) 122 return(cur->data); 123 cur = cur->next; 124 } 125 126 return(NULL); 127 } 128 129 /* 130 * Store an entry in the main netgroup hash table. Here's how this 131 * works: the table can only be so big when we initialize it (TABLESIZE) 132 * but the number of netgroups in the /etc/netgroup file could easily be 133 * much larger than the table. Since our hash values are adjusted to 134 * never be greater than TABLESIZE too, this means it won't be long before 135 * we find ourselves with two keys that hash to the same value. 136 * 137 * One way to deal with this is to malloc(2) a second table and start 138 * doing indirection, but this is a pain in the butt and it's not worth 139 * going to all that trouble for a dinky littke program like this. Instead, 140 * we turn each table entry into a linked list and simply link keys 141 * with the same hash value together at the same index location within 142 * the table. 143 * 144 * That's a lot of comment for such a small piece of code, isn't it. 145 */ 146 void store (table, key, data) 147 struct group_entry *table[]; 148 char *key, *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 an 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 */ 176 void mstore (table, key, data, domain) 177 struct member_entry *table[]; 178 char *key, *data, *domain; 179 { 180 struct member_entry *cur, *new; 181 struct grouplist *tmp; 182 u_int32_t i; 183 184 i = hashkey(key); 185 cur = table[i]; 186 187 tmp = (struct grouplist *)malloc(sizeof(struct grouplist)); 188 tmp->groupname = strdup(data); 189 tmp->next = NULL; 190 191 /* Check if all we have to do is insert a new groupname. */ 192 while (cur) { 193 if (!strcmp(cur->key, key)) { 194 tmp->next = cur->groups; 195 cur->groups = tmp; 196 return; 197 } 198 cur = cur->next; 199 } 200 201 /* Didn't find a match -- add the whole mess to the table. */ 202 new = (struct member_entry *)malloc(sizeof(struct member_entry)); 203 new->key = strdup(key); 204 new->domain = domain ? strdup(domain) : "*"; 205 new->groups = tmp; 206 new->next = table[i]; 207 table[i] = new; 208 209 return; 210 } 211