diff options
Diffstat (limited to 'src/crypto/lhash/lhash.c')
-rw-r--r-- | src/crypto/lhash/lhash.c | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/src/crypto/lhash/lhash.c b/src/crypto/lhash/lhash.c new file mode 100644 index 0000000..c282fa8 --- /dev/null +++ b/src/crypto/lhash/lhash.c @@ -0,0 +1,345 @@ +/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. + * + * This package is an SSL implementation written + * by Eric Young (eay@cryptsoft.com). + * The implementation was written so as to conform with Netscapes SSL. + * + * This library is free for commercial and non-commercial use as long as + * the following conditions are aheared to. The following conditions + * apply to all code found in this distribution, be it the RC4, RSA, + * lhash, DES, etc., code; not just the SSL code. The SSL documentation + * included with this distribution is covered by the same copyright terms + * except that the holder is Tim Hudson (tjh@cryptsoft.com). + * + * Copyright remains Eric Young's, and as such any Copyright notices in + * the code are not to be removed. + * If this package is used in a product, Eric Young should be given attribution + * as the author of the parts of the library used. + * This can be in the form of a textual message at program startup or + * in documentation (online or textual) provided with the package. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * "This product includes cryptographic software written by + * Eric Young (eay@cryptsoft.com)" + * The word 'cryptographic' can be left out if the rouines from the library + * being used are not cryptographic related :-). + * 4. If you include any Windows specific code (or a derivative thereof) from + * the apps directory (application code) you must include an acknowledgement: + * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" + * + * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * The licence and distribution terms for any publically available version or + * derivative of this code cannot be changed. i.e. this code cannot simply be + * copied and put under another distribution licence + * [including the GNU Public Licence.] */ + +#include <openssl/lhash.h> + +#include <assert.h> +#include <limits.h> +#include <string.h> + +#include <openssl/mem.h> + +/* kMinNumBuckets is the minimum size of the buckets array in an |_LHASH|. */ +static const size_t kMinNumBuckets = 16; + +/* kMaxAverageChainLength contains the maximum, average chain length. When the + * average chain length exceeds this value, the hash table will be resized. */ +static const size_t kMaxAverageChainLength = 2; +static const size_t kMinAverageChainLength = 1; + +_LHASH *lh_new(lhash_hash_func hash, lhash_cmp_func comp) { + _LHASH *ret; + + ret = OPENSSL_malloc(sizeof(_LHASH)); + if (ret == NULL) { + return NULL; + } + memset(ret, 0, sizeof(_LHASH)); + + ret->num_buckets = kMinNumBuckets; + ret->buckets = OPENSSL_malloc(sizeof(LHASH_ITEM *) * ret->num_buckets); + if (ret->buckets == NULL) { + OPENSSL_free(ret); + return NULL; + } + memset(ret->buckets, 0, sizeof(LHASH_ITEM *) * ret->num_buckets); + + ret->comp = comp; + if (ret->comp == NULL) { + ret->comp = (lhash_cmp_func) strcmp; + } + ret->hash = hash; + if (ret->hash == NULL) { + ret->hash = (lhash_hash_func) lh_strhash; + } + + return ret; +} + +void lh_free(_LHASH *lh) { + size_t i; + LHASH_ITEM *n, *next; + + if (lh == NULL) { + return; + } + + for (i = 0; i < lh->num_buckets; i++) { + for (n = lh->buckets[i]; n != NULL; n = next) { + next = n->next; + OPENSSL_free(n); + } + } + + OPENSSL_free(lh->buckets); + OPENSSL_free(lh); +} + +size_t lh_num_items(const _LHASH *lh) { return lh->num_items; } + +/* get_next_ptr_and_hash returns a pointer to the pointer that points to the + * item equal to |data|. In other words, it searches for an item equal to |data| + * and, if it's at the start of a chain, then it returns a pointer to an + * element of |lh->buckets|, otherwise it returns a pointer to the |next| + * element of the previous item in the chain. If an element equal to |data| is + * not found, it returns a pointer that points to a NULL pointer. If |out_hash| + * is not NULL, then it also puts the hash value of |data| in |*out_hash|. */ +static LHASH_ITEM **get_next_ptr_and_hash(const _LHASH *lh, uint32_t *out_hash, + const void *data) { + const uint32_t hash = lh->hash(data); + LHASH_ITEM *cur, **ret; + + if (out_hash != NULL) { + *out_hash = hash; + } + + ret = &lh->buckets[hash % lh->num_buckets]; + for (cur = *ret; cur != NULL; cur = *ret) { + if (lh->comp(cur->data, data) == 0) { + break; + } + ret = &cur->next; + } + + return ret; +} + +void *lh_retrieve(const _LHASH *lh, const void *data) { + LHASH_ITEM **next_ptr; + + next_ptr = get_next_ptr_and_hash(lh, NULL, data); + + if (*next_ptr == NULL) { + return NULL; + } + + return (*next_ptr)->data; +} + +/* lh_rebucket allocates a new array of |new_num_buckets| pointers and + * redistributes the existing items into it before making it |lh->buckets| and + * freeing the old array. */ +static void lh_rebucket(_LHASH *lh, const size_t new_num_buckets) { + LHASH_ITEM **new_buckets, *cur, *next; + size_t i, alloc_size; + + alloc_size = sizeof(LHASH_ITEM *) * new_num_buckets; + if (alloc_size / sizeof(LHASH_ITEM*) != new_num_buckets) { + return; + } + + new_buckets = OPENSSL_malloc(alloc_size); + if (new_buckets == NULL) { + return; + } + memset(new_buckets, 0, alloc_size); + + for (i = 0; i < lh->num_buckets; i++) { + for (cur = lh->buckets[i]; cur != NULL; cur = next) { + const size_t new_bucket = cur->hash % new_num_buckets; + next = cur->next; + cur->next = new_buckets[new_bucket]; + new_buckets[new_bucket] = cur; + } + } + + OPENSSL_free(lh->buckets); + + lh->num_buckets = new_num_buckets; + lh->buckets = new_buckets; +} + +/* lh_maybe_resize resizes the |buckets| array if needed. */ +static void lh_maybe_resize(_LHASH *lh) { + size_t avg_chain_length; + + if (lh->callback_depth > 0) { + /* Don't resize the hash if we are currently iterating over it. */ + return; + } + + assert(lh->num_buckets >= kMinNumBuckets); + avg_chain_length = lh->num_items / lh->num_buckets; + + if (avg_chain_length > kMaxAverageChainLength) { + const size_t new_num_buckets = lh->num_buckets * 2; + + if (new_num_buckets > lh->num_buckets) { + lh_rebucket(lh, new_num_buckets); + } + } else if (avg_chain_length < kMinAverageChainLength && + lh->num_buckets > kMinNumBuckets) { + size_t new_num_buckets = lh->num_buckets / 2; + + if (new_num_buckets < kMinNumBuckets) { + new_num_buckets = kMinNumBuckets; + } + + lh_rebucket(lh, new_num_buckets); + } +} + +int lh_insert(_LHASH *lh, void **old_data, void *data) { + uint32_t hash; + LHASH_ITEM **next_ptr, *item; + + *old_data = NULL; + next_ptr = get_next_ptr_and_hash(lh, &hash, data); + + + if (*next_ptr != NULL) { + /* An element equal to |data| already exists in the hash table. It will be + * replaced. */ + *old_data = (*next_ptr)->data; + (*next_ptr)->data = data; + return 1; + } + + /* An element equal to |data| doesn't exist in the hash table yet. */ + item = OPENSSL_malloc(sizeof(LHASH_ITEM)); + if (item == NULL) { + return 0; + } + + item->data = data; + item->hash = hash; + item->next = NULL; + *next_ptr = item; + lh->num_items++; + lh_maybe_resize(lh); + + return 1; +} + +void *lh_delete(_LHASH *lh, const void *data) { + LHASH_ITEM **next_ptr, *item, *ret; + + next_ptr = get_next_ptr_and_hash(lh, NULL, data); + + if (*next_ptr == NULL) { + /* No such element. */ + return NULL; + } + + item = *next_ptr; + *next_ptr = item->next; + ret = item->data; + OPENSSL_free(item); + + lh->num_items--; + lh_maybe_resize(lh); + + return ret; +} + +static void lh_doall_internal(_LHASH *lh, void (*no_arg_func)(void *), + void (*arg_func)(void *, void *), void *arg) { + size_t i; + LHASH_ITEM *cur, *next; + + if (lh == NULL) { + return; + } + + if (lh->callback_depth < UINT_MAX) { + /* |callback_depth| is a saturating counter. */ + lh->callback_depth++; + } + + for (i = 0; i < lh->num_buckets; i++) { + for (cur = lh->buckets[i]; cur != NULL; cur = next) { + next = cur->next; + if (arg_func) { + arg_func(cur->data, arg); + } else { + no_arg_func(cur->data); + } + } + } + + if (lh->callback_depth < UINT_MAX) { + lh->callback_depth--; + } + + /* The callback may have added or removed elements and the non-zero value of + * |callback_depth| will have suppressed any resizing. Thus any needed + * resizing is done here. */ + lh_maybe_resize(lh); +} + +void lh_doall(_LHASH *lh, void (*func)(void *)) { + lh_doall_internal(lh, func, NULL, NULL); +} + +void lh_doall_arg(_LHASH *lh, void (*func)(void *, void *), void *arg) { + lh_doall_internal(lh, NULL, func, arg); +} + +uint32_t lh_strhash(const char *c) { + /* The following hash seems to work very well on normal text strings + * no collisions on /usr/dict/words and it distributes on %2^n quite + * well, not as good as MD5, but still good. */ + unsigned long ret = 0; + long n; + unsigned long v; + int r; + + if ((c == NULL) || (*c == '\0')) { + return (ret); + } + + n = 0x100; + while (*c) { + v = n | (*c); + n += 0x100; + r = (int)((v >> 2) ^ v) & 0x0f; + ret = (ret << r) | (ret >> (32 - r)); + ret &= 0xFFFFFFFFL; + ret ^= v * v; + c++; + } + + return ((ret >> 16) ^ ret); +} |