1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) * All rights reserved. 2 * 3 * This package is an SSL implementation written 4 * by Eric Young (eay (at) cryptsoft.com). 5 * The implementation was written so as to conform with Netscapes SSL. 6 * 7 * This library is free for commercial and non-commercial use as long as 8 * the following conditions are aheared to. The following conditions 9 * apply to all code found in this distribution, be it the RC4, RSA, 10 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 11 * included with this distribution is covered by the same copyright terms 12 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 13 * 14 * Copyright remains Eric Young's, and as such any Copyright notices in 15 * the code are not to be removed. 16 * If this package is used in a product, Eric Young should be given attribution 17 * as the author of the parts of the library used. 18 * This can be in the form of a textual message at program startup or 19 * in documentation (online or textual) provided with the package. 20 * 21 * Redistribution and use in source and binary forms, with or without 22 * modification, are permitted provided that the following conditions 23 * are met: 24 * 1. Redistributions of source code must retain the copyright 25 * notice, this list of conditions and the following disclaimer. 26 * 2. Redistributions in binary form must reproduce the above copyright 27 * notice, this list of conditions and the following disclaimer in the 28 * documentation and/or other materials provided with the distribution. 29 * 3. All advertising materials mentioning features or use of this software 30 * must display the following acknowledgement: 31 * "This product includes cryptographic software written by 32 * Eric Young (eay (at) cryptsoft.com)" 33 * The word 'cryptographic' can be left out if the rouines from the library 34 * being used are not cryptographic related :-). 35 * 4. If you include any Windows specific code (or a derivative thereof) from 36 * the apps directory (application code) you must include an acknowledgement: 37 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 40 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 42 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 43 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 44 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 45 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 47 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 48 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 49 * SUCH DAMAGE. 50 * 51 * The licence and distribution terms for any publically available version or 52 * derivative of this code cannot be changed. i.e. this code cannot simply be 53 * copied and put under another distribution licence 54 * [including the GNU Public Licence.] */ 55 56 #include <openssl/lhash.h> 57 58 #include <assert.h> 59 #include <limits.h> 60 61 #include <openssl/mem.h> 62 63 /* kMinNumBuckets is the minimum size of the buckets array in an |_LHASH|. */ 64 static const size_t kMinNumBuckets = 16; 65 66 /* kMaxAverageChainLength contains the maximum, average chain length. When the 67 * average chain length exceeds this value, the hash table will be resized. */ 68 static const size_t kMaxAverageChainLength = 2; 69 static const size_t kMinAverageChainLength = 1; 70 71 _LHASH *lh_new(lhash_hash_func hash, lhash_cmp_func comp) { 72 _LHASH *ret; 73 74 ret = OPENSSL_malloc(sizeof(_LHASH)); 75 if (ret == NULL) { 76 return NULL; 77 } 78 memset(ret, 0, sizeof(_LHASH)); 79 80 ret->num_buckets = kMinNumBuckets; 81 ret->buckets = OPENSSL_malloc(sizeof(LHASH_ITEM *) * ret->num_buckets); 82 if (ret->buckets == NULL) { 83 OPENSSL_free(ret); 84 return NULL; 85 } 86 memset(ret->buckets, 0, sizeof(LHASH_ITEM *) * ret->num_buckets); 87 88 ret->comp = comp; 89 if (ret->comp == NULL) { 90 ret->comp = (lhash_cmp_func) strcmp; 91 } 92 ret->hash = hash; 93 if (ret->hash == NULL) { 94 ret->hash = (lhash_hash_func) lh_strhash; 95 } 96 97 return ret; 98 } 99 100 void lh_free(_LHASH *lh) { 101 size_t i; 102 LHASH_ITEM *n, *next; 103 104 if (lh == NULL) { 105 return; 106 } 107 108 for (i = 0; i < lh->num_buckets; i++) { 109 for (n = lh->buckets[i]; n != NULL; n = next) { 110 next = n->next; 111 OPENSSL_free(n); 112 } 113 } 114 115 OPENSSL_free(lh->buckets); 116 OPENSSL_free(lh); 117 } 118 119 size_t lh_num_items(const _LHASH *lh) { return lh->num_items; } 120 121 /* get_next_ptr_and_hash returns a pointer to the pointer that points to the 122 * item equal to |data|. In other words, it searches for an item equal to |data| 123 * and, if it's at the start of a chain, then it returns a pointer to an 124 * element of |lh->buckets|, otherwise it returns a pointer to the |next| 125 * element of the previous item in the chain. If an element equal to |data| is 126 * not found, it returns a pointer that points to a NULL pointer. If |out_hash| 127 * is not NULL, then it also puts the hash value of |data| in |*out_hash|. */ 128 static LHASH_ITEM **get_next_ptr_and_hash(const _LHASH *lh, uint32_t *out_hash, 129 const void *data) { 130 const uint32_t hash = lh->hash(data); 131 LHASH_ITEM *cur, **ret; 132 133 if (out_hash != NULL) { 134 *out_hash = hash; 135 } 136 137 ret = &lh->buckets[hash % lh->num_buckets]; 138 for (cur = *ret; cur != NULL; cur = *ret) { 139 if (lh->comp(cur->data, data) == 0) { 140 break; 141 } 142 ret = &cur->next; 143 } 144 145 return ret; 146 } 147 148 void *lh_retrieve(const _LHASH *lh, const void *data) { 149 LHASH_ITEM **next_ptr; 150 151 next_ptr = get_next_ptr_and_hash(lh, NULL, data); 152 153 if (*next_ptr == NULL) { 154 return NULL; 155 } 156 157 return (*next_ptr)->data; 158 } 159 160 /* lh_rebucket allocates a new array of |new_num_buckets| pointers and 161 * redistributes the existing items into it before making it |lh->buckets| and 162 * freeing the old array. */ 163 static void lh_rebucket(_LHASH *lh, const size_t new_num_buckets) { 164 LHASH_ITEM **new_buckets, *cur, *next; 165 size_t i, alloc_size; 166 167 alloc_size = sizeof(LHASH_ITEM *) * new_num_buckets; 168 if (alloc_size / sizeof(LHASH_ITEM*) != new_num_buckets) { 169 return; 170 } 171 172 new_buckets = OPENSSL_malloc(alloc_size); 173 if (new_buckets == NULL) { 174 return; 175 } 176 memset(new_buckets, 0, alloc_size); 177 178 for (i = 0; i < lh->num_buckets; i++) { 179 for (cur = lh->buckets[i]; cur != NULL; cur = next) { 180 const size_t new_bucket = cur->hash % new_num_buckets; 181 next = cur->next; 182 cur->next = new_buckets[new_bucket]; 183 new_buckets[new_bucket] = cur; 184 } 185 } 186 187 OPENSSL_free(lh->buckets); 188 189 lh->num_buckets = new_num_buckets; 190 lh->buckets = new_buckets; 191 } 192 193 /* lh_maybe_resize resizes the |buckets| array if needed. */ 194 static void lh_maybe_resize(_LHASH *lh) { 195 size_t avg_chain_length; 196 197 if (lh->callback_depth > 0) { 198 /* Don't resize the hash if we are currently iterating over it. */ 199 return; 200 } 201 202 assert(lh->num_buckets >= kMinNumBuckets); 203 avg_chain_length = lh->num_items / lh->num_buckets; 204 205 if (avg_chain_length > kMaxAverageChainLength) { 206 const size_t new_num_buckets = lh->num_buckets * 2; 207 208 if (new_num_buckets > lh->num_buckets) { 209 lh_rebucket(lh, new_num_buckets); 210 } 211 } else if (avg_chain_length < kMinAverageChainLength && 212 lh->num_buckets > kMinNumBuckets) { 213 size_t new_num_buckets = lh->num_buckets / 2; 214 215 if (new_num_buckets < kMinNumBuckets) { 216 new_num_buckets = kMinNumBuckets; 217 } 218 219 lh_rebucket(lh, new_num_buckets); 220 } 221 } 222 223 int lh_insert(_LHASH *lh, void **old_data, void *data) { 224 uint32_t hash; 225 LHASH_ITEM **next_ptr, *item; 226 227 *old_data = NULL; 228 next_ptr = get_next_ptr_and_hash(lh, &hash, data); 229 230 231 if (*next_ptr != NULL) { 232 /* An element equal to |data| already exists in the hash table. It will be 233 * replaced. */ 234 *old_data = (*next_ptr)->data; 235 (*next_ptr)->data = data; 236 return 1; 237 } 238 239 /* An element equal to |data| doesn't exist in the hash table yet. */ 240 item = OPENSSL_malloc(sizeof(LHASH_ITEM)); 241 if (item == NULL) { 242 return 0; 243 } 244 245 item->data = data; 246 item->hash = hash; 247 item->next = NULL; 248 *next_ptr = item; 249 lh->num_items++; 250 lh_maybe_resize(lh); 251 252 return 1; 253 } 254 255 void *lh_delete(_LHASH *lh, const void *data) { 256 LHASH_ITEM **next_ptr, *item, *ret; 257 258 next_ptr = get_next_ptr_and_hash(lh, NULL, data); 259 260 if (*next_ptr == NULL) { 261 /* No such element. */ 262 return NULL; 263 } 264 265 item = *next_ptr; 266 *next_ptr = item->next; 267 ret = item->data; 268 OPENSSL_free(item); 269 270 lh->num_items--; 271 lh_maybe_resize(lh); 272 273 return ret; 274 } 275 276 static void lh_doall_internal(_LHASH *lh, void (*no_arg_func)(void *), 277 void (*arg_func)(void *, void *), void *arg) { 278 size_t i; 279 LHASH_ITEM *cur, *next; 280 281 if (lh == NULL) { 282 return; 283 } 284 285 if (lh->callback_depth < UINT_MAX) { 286 /* |callback_depth| is a saturating counter. */ 287 lh->callback_depth++; 288 } 289 290 for (i = 0; i < lh->num_buckets; i++) { 291 for (cur = lh->buckets[i]; cur != NULL; cur = next) { 292 next = cur->next; 293 if (arg_func) { 294 arg_func(cur->data, arg); 295 } else { 296 no_arg_func(cur->data); 297 } 298 } 299 } 300 301 if (lh->callback_depth < UINT_MAX) { 302 lh->callback_depth--; 303 } 304 305 /* The callback may have added or removed elements and the non-zero value of 306 * |callback_depth| will have suppressed any resizing. Thus any needed 307 * resizing is done here. */ 308 lh_maybe_resize(lh); 309 } 310 311 void lh_doall(_LHASH *lh, void (*func)(void *)) { 312 lh_doall_internal(lh, func, NULL, NULL); 313 } 314 315 void lh_doall_arg(_LHASH *lh, void (*func)(void *, void *), void *arg) { 316 lh_doall_internal(lh, NULL, func, arg); 317 } 318 319 uint32_t lh_strhash(const char *c) { 320 /* The following hash seems to work very well on normal text strings 321 * no collisions on /usr/dict/words and it distributes on %2^n quite 322 * well, not as good as MD5, but still good. */ 323 unsigned long ret = 0; 324 long n; 325 unsigned long v; 326 int r; 327 328 if ((c == NULL) || (*c == '\0')) { 329 return (ret); 330 } 331 332 n = 0x100; 333 while (*c) { 334 v = n | (*c); 335 n += 0x100; 336 r = (int)((v >> 2) ^ v) & 0x0f; 337 ret = (ret << r) | (ret >> (32 - r)); 338 ret &= 0xFFFFFFFFL; 339 ret ^= v * v; 340 c++; 341 } 342 343 return ((ret >> 16) ^ ret); 344 } 345