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 static const char rcsid[] = 35 "$FreeBSD$"; 36 #endif /* not lint */ 37 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include <string.h> 41 #include <sys/types.h> 42 #include "hash.h" 43 44 /* 45 * This hash function is stolen directly from the 46 * Berkeley DB package. It already exists inside libc, but 47 * it's declared static which prevents us from calling it 48 * from here. 49 */ 50 /* 51 * OZ's original sdbm hash 52 */ 53 u_int32_t 54 hash(const void *keyarg, size_t len) 55 { 56 const u_char *key; 57 size_t loop; 58 u_int32_t h; 59 60 #define HASHC h = *key++ + 65599 * h 61 62 h = 0; 63 key = keyarg; 64 if (len > 0) { 65 loop = (len + 8 - 1) >> 3; 66 67 switch (len & (8 - 1)) { 68 case 0: 69 do { 70 HASHC; 71 /* FALLTHROUGH */ 72 case 7: 73 HASHC; 74 /* FALLTHROUGH */ 75 case 6: 76 HASHC; 77 /* FALLTHROUGH */ 78 case 5: 79 HASHC; 80 /* FALLTHROUGH */ 81 case 4: 82 HASHC; 83 /* FALLTHROUGH */ 84 case 3: 85 HASHC; 86 /* FALLTHROUGH */ 87 case 2: 88 HASHC; 89 /* FALLTHROUGH */ 90 case 1: 91 HASHC; 92 } while (--loop); 93 } 94 } 95 return (h); 96 } 97 98 /* 99 * Generate a hash value for a given key (character string). 100 * We mask off all but the lower 8 bits since our table array 101 * can only hold 256 elements. 102 */ 103 u_int32_t 104 hashkey(char *key) 105 { 106 107 if (key == NULL) 108 return (-1); 109 return(hash((void *)key, strlen(key)) & HASH_MASK); 110 } 111 112 /* Find an entry in the hash table (may be hanging off a linked list). */ 113 char * 114 lookup(struct group_entry *table[], 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 little 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 147 store(struct group_entry *table[], char *key, char *data) 148 { 149 struct group_entry *new; 150 u_int32_t i; 151 152 i = hashkey(key); 153 154 new = (struct group_entry *)malloc(sizeof(struct group_entry)); 155 new->key = strdup(key); 156 new->data = strdup(data); 157 new->next = table[i]; 158 table[i] = new; 159 160 return; 161 } 162 163 /* 164 * Store a group member entry and/or update its grouplist. This is 165 * a bit more complicated than the previous function since we have to 166 * maintain not only the hash table of group members, each group member 167 * structure also has a linked list of groups hung off it. If handed 168 * a member name that we haven't encountered before, we have to do 169 * two things: add that member to the table (possibly hanging them 170 * off the end of a linked list, as above), and add a group name to 171 * the member's grouplist list. If we're handed a name that already has 172 * an entry in the table, then we just have to do one thing, which is 173 * to update its grouplist. 174 */ 175 void 176 mstore(struct member_entry *table[], char *key, char *data, char *domain) 177 { 178 struct member_entry *cur, *new; 179 struct grouplist *tmp; 180 u_int32_t i; 181 182 i = hashkey(key); 183 cur = table[i]; 184 185 tmp = (struct grouplist *)malloc(sizeof(struct grouplist)); 186 tmp->groupname = strdup(data); 187 tmp->next = NULL; 188 189 /* Check if all we have to do is insert a new groupname. */ 190 while (cur) { 191 if (!strcmp(cur->key, key)) { 192 tmp->next = cur->groups; 193 cur->groups = tmp; 194 return; 195 } 196 cur = cur->next; 197 } 198 199 /* Didn't find a match -- add the whole mess to the table. */ 200 new = (struct member_entry *)malloc(sizeof(struct member_entry)); 201 new->key = strdup(key); 202 new->domain = domain ? strdup(domain) : "*"; 203 new->groups = tmp; 204 new->next = table[i]; 205 table[i] = new; 206 207 return; 208 } 209