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 * $FreeBSD: src/libexec/revnetgroup/hash.c,v 1.6 1999/08/28 00:09:47 peter Exp $ 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 static u_int32_t 51 hash(const void *keyarg, size_t len) 52 { 53 const u_char *key; 54 size_t loop; 55 u_int32_t h; 56 57 #define HASHC h = *key++ + 65599 * h 58 59 h = 0; 60 key = keyarg; 61 if (len > 0) { 62 loop = (len + 8 - 1) >> 3; 63 64 switch (len & (8 - 1)) { 65 case 0: 66 do { 67 HASHC; 68 /* FALLTHROUGH */ 69 case 7: 70 HASHC; 71 /* FALLTHROUGH */ 72 case 6: 73 HASHC; 74 /* FALLTHROUGH */ 75 case 5: 76 HASHC; 77 /* FALLTHROUGH */ 78 case 4: 79 HASHC; 80 /* FALLTHROUGH */ 81 case 3: 82 HASHC; 83 /* FALLTHROUGH */ 84 case 2: 85 HASHC; 86 /* FALLTHROUGH */ 87 case 1: 88 HASHC; 89 } while (--loop); 90 } 91 } 92 return (h); 93 } 94 95 /* 96 * Generate a hash value for a given key (character string). 97 * We mask off all but the lower 8 bits since our table array 98 * can only hold 256 elements. 99 */ 100 static u_int32_t 101 hashkey(char *key) 102 { 103 104 if (key == NULL) 105 return (-1); 106 return(hash(key, strlen(key)) & HASH_MASK); 107 } 108 109 /* Find an entry in the hash table (may be hanging off a linked list). */ 110 char * 111 lookup(struct group_entry *table[], char *key) 112 { 113 struct group_entry *cur; 114 115 cur = table[hashkey(key)]; 116 117 while (cur) { 118 if (!strcmp(cur->key, key)) 119 return(cur->data); 120 cur = cur->next; 121 } 122 123 return(NULL); 124 } 125 126 /* 127 * Store an entry in the main netgroup hash table. Here's how this 128 * works: the table can only be so big when we initialize it (TABLESIZE) 129 * but the number of netgroups in the /etc/netgroup file could easily be 130 * much larger than the table. Since our hash values are adjusted to 131 * never be greater than TABLESIZE too, this means it won't be long before 132 * we find ourselves with two keys that hash to the same value. 133 * 134 * One way to deal with this is to malloc(2) a second table and start 135 * doing indirection, but this is a pain in the butt and it's not worth 136 * going to all that trouble for a dinky little program like this. Instead, 137 * we turn each table entry into a linked list and simply link keys 138 * with the same hash value together at the same index location within 139 * the table. 140 * 141 * That's a lot of comment for such a small piece of code, isn't it. 142 */ 143 void 144 store(struct group_entry *table[], char *key, char *data) 145 { 146 struct group_entry *new; 147 u_int32_t i; 148 149 i = hashkey(key); 150 151 new = (struct group_entry *)malloc(sizeof(struct group_entry)); 152 new->key = strdup(key); 153 new->data = strdup(data); 154 new->next = table[i]; 155 table[i] = new; 156 157 return; 158 } 159 160 /* 161 * Store a group member entry and/or update its grouplist. This is 162 * a bit more complicated than the previous function since we have to 163 * maintain not only the hash table of group members, each group member 164 * structure also has a linked list of groups hung off it. If handed 165 * a member name that we haven't encountered before, we have to do 166 * two things: add that member to the table (possibly hanging them 167 * off the end of a linked list, as above), and add a group name to 168 * the member's grouplist list. If we're handed a name that already has 169 * an entry in the table, then we just have to do one thing, which is 170 * to update its grouplist. 171 */ 172 void 173 mstore(struct member_entry *table[], char *key, char *data, char *domain) 174 { 175 struct member_entry *cur, *new; 176 struct grouplist *tmp; 177 u_int32_t i; 178 179 i = hashkey(key); 180 cur = table[i]; 181 182 tmp = (struct grouplist *)malloc(sizeof(struct grouplist)); 183 tmp->groupname = strdup(data); 184 tmp->next = NULL; 185 186 /* Check if all we have to do is insert a new groupname. */ 187 while (cur) { 188 if (!strcmp(cur->key, key)) { 189 tmp->next = cur->groups; 190 cur->groups = tmp; 191 return; 192 } 193 cur = cur->next; 194 } 195 196 /* Didn't find a match -- add the whole mess to the table. */ 197 new = (struct member_entry *)malloc(sizeof(struct member_entry)); 198 new->key = strdup(key); 199 new->domain = domain ? strdup(domain) : "*"; 200 new->groups = tmp; 201 new->next = table[i]; 202 table[i] = new; 203 204 return; 205 } 206