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 #ifndef lint 42 static const char rcsid[] = "$Id$"; 43 #endif 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 */ 54 u_int32_t 55 hash(keyarg, len) 56 const void *keyarg; 57 register size_t len; 58 { 59 register const u_char *key; 60 register size_t loop; 61 register u_int32_t h; 62 63 #define HASHC h = *key++ + 65599 * h 64 65 h = 0; 66 key = keyarg; 67 if (len > 0) { 68 loop = (len + 8 - 1) >> 3; 69 70 switch (len & (8 - 1)) { 71 case 0: 72 do { 73 HASHC; 74 /* FALLTHROUGH */ 75 case 7: 76 HASHC; 77 /* FALLTHROUGH */ 78 case 6: 79 HASHC; 80 /* FALLTHROUGH */ 81 case 5: 82 HASHC; 83 /* FALLTHROUGH */ 84 case 4: 85 HASHC; 86 /* FALLTHROUGH */ 87 case 3: 88 HASHC; 89 /* FALLTHROUGH */ 90 case 2: 91 HASHC; 92 /* FALLTHROUGH */ 93 case 1: 94 HASHC; 95 } while (--loop); 96 } 97 } 98 return (h); 99 } 100 101 /* 102 * Generate a hash value for a given key (character string). 103 * We mask off all but the lower 8 bits since our table array 104 * can only hold 256 elements. 105 */ 106 u_int32_t hashkey(key) 107 char *key; 108 { 109 110 if (key == NULL) 111 return (-1); 112 return(hash((void *)key, strlen(key)) & HASH_MASK); 113 } 114 115 /* Find an entry in the hash table (may be hanging off a linked list). */ 116 char *lookup(table, key) 117 struct group_entry *table[]; 118 char *key; 119 { 120 struct group_entry *cur; 121 122 cur = table[hashkey(key)]; 123 124 while (cur) { 125 if (!strcmp(cur->key, key)) 126 return(cur->data); 127 cur = cur->next; 128 } 129 130 return(NULL); 131 } 132 133 /* 134 * Store an entry in the main netgroup hash table. Here's how this 135 * works: the table can only be so big when we initialize it (TABLESIZE) 136 * but the number of netgroups in the /etc/netgroup file could easily be 137 * much larger than the table. Since our hash values are adjusted to 138 * never be greater than TABLESIZE too, this means it won't be long before 139 * we find ourselves with two keys that hash to the same value. 140 * 141 * One way to deal with this is to malloc(2) a second table and start 142 * doing indirection, but this is a pain in the butt and it's not worth 143 * going to all that trouble for a dinky little program like this. Instead, 144 * we turn each table entry into a linked list and simply link keys 145 * with the same hash value together at the same index location within 146 * the table. 147 * 148 * That's a lot of comment for such a small piece of code, isn't it. 149 */ 150 void store (table, key, data) 151 struct group_entry *table[]; 152 char *key, *data; 153 { 154 struct group_entry *new; 155 u_int32_t i; 156 157 i = hashkey(key); 158 159 new = (struct group_entry *)malloc(sizeof(struct group_entry)); 160 new->key = strdup(key); 161 new->data = strdup(data); 162 new->next = table[i]; 163 table[i] = new; 164 165 return; 166 } 167 168 /* 169 * Store a group member entry and/or update its grouplist. This is 170 * a bit more complicated than the previous function since we have to 171 * maintain not only the hash table of group members, each group member 172 * structure also has a linked list of groups hung off it. If handed 173 * a member name that we haven't encountered before, we have to do 174 * two things: add that member to the table (possibly hanging them 175 * off the end of a linked list, as above), and add a group name to 176 * the member's grouplist list. If we're handed a name that already has 177 * an entry in the table, then we just have to do one thing, which is 178 * to update its grouplist. 179 */ 180 void mstore (table, key, data, domain) 181 struct member_entry *table[]; 182 char *key, *data, *domain; 183 { 184 struct member_entry *cur, *new; 185 struct grouplist *tmp; 186 u_int32_t i; 187 188 i = hashkey(key); 189 cur = table[i]; 190 191 tmp = (struct grouplist *)malloc(sizeof(struct grouplist)); 192 tmp->groupname = strdup(data); 193 tmp->next = NULL; 194 195 /* Check if all we have to do is insert a new groupname. */ 196 while (cur) { 197 if (!strcmp(cur->key, key)) { 198 tmp->next = cur->groups; 199 cur->groups = tmp; 200 return; 201 } 202 cur = cur->next; 203 } 204 205 /* Didn't find a match -- add the whole mess to the table. */ 206 new = (struct member_entry *)malloc(sizeof(struct member_entry)); 207 new->key = strdup(key); 208 new->domain = domain ? strdup(domain) : "*"; 209 new->groups = tmp; 210 new->next = table[i]; 211 table[i] = new; 212 213 return; 214 } 215