373 lines
9.3 KiB
C
373 lines
9.3 KiB
C
/*
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* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <openssl/crypto.h>
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#include <openssl/lhash.h>
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#include "lhash_lcl.h"
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/*
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* A hashing implementation that appears to be based on the linear hashing
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* alogrithm:
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* https://en.wikipedia.org/wiki/Linear_hashing
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*
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* Litwin, Witold (1980), "Linear hashing: A new tool for file and table
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* addressing", Proc. 6th Conference on Very Large Databases: 212–223
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* http://hackthology.com/pdfs/Litwin-1980-Linear_Hashing.pdf
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*
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* From the wikipedia article "Linear hashing is used in the BDB Berkeley
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* database system, which in turn is used by many software systems such as
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* OpenLDAP, using a C implementation derived from the CACM article and first
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* published on the Usenet in 1988 by Esmond Pitt."
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*
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* The CACM paper is available here:
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* https://pdfs.semanticscholar.org/ff4d/1c5deca6269cc316bfd952172284dbf610ee.pdf
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*/
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#undef MIN_NODES
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#define MIN_NODES 16
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#define UP_LOAD (2*LH_LOAD_MULT) /* load times 256 (default 2) */
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#define DOWN_LOAD (LH_LOAD_MULT) /* load times 256 (default 1) */
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static int expand(OPENSSL_LHASH *lh);
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static void contract(OPENSSL_LHASH *lh);
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static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh, const void *data, unsigned long *rhash);
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OPENSSL_LHASH *OPENSSL_LH_new(OPENSSL_LH_HASHFUNC h, OPENSSL_LH_COMPFUNC c)
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{
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OPENSSL_LHASH *ret;
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if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL)
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return NULL;
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if ((ret->b = OPENSSL_zalloc(sizeof(*ret->b) * MIN_NODES)) == NULL)
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goto err;
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if ((ret->retrieve_stats_lock = CRYPTO_THREAD_lock_new()) == NULL)
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goto err;
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ret->comp = ((c == NULL) ? (OPENSSL_LH_COMPFUNC)strcmp : c);
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ret->hash = ((h == NULL) ? (OPENSSL_LH_HASHFUNC)OPENSSL_LH_strhash : h);
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ret->num_nodes = MIN_NODES / 2;
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ret->num_alloc_nodes = MIN_NODES;
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ret->pmax = MIN_NODES / 2;
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ret->up_load = UP_LOAD;
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ret->down_load = DOWN_LOAD;
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return (ret);
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err:
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OPENSSL_free(ret->b);
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OPENSSL_free(ret);
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return NULL;
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}
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void OPENSSL_LH_free(OPENSSL_LHASH *lh)
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{
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unsigned int i;
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OPENSSL_LH_NODE *n, *nn;
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if (lh == NULL)
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return;
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for (i = 0; i < lh->num_nodes; i++) {
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n = lh->b[i];
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while (n != NULL) {
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nn = n->next;
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OPENSSL_free(n);
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n = nn;
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}
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}
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CRYPTO_THREAD_lock_free(lh->retrieve_stats_lock);
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OPENSSL_free(lh->b);
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OPENSSL_free(lh);
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}
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void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data)
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{
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unsigned long hash;
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OPENSSL_LH_NODE *nn, **rn;
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void *ret;
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lh->error = 0;
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if ((lh->up_load <= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)) && !expand(lh))
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return NULL; /* 'lh->error++' already done in 'expand' */
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rn = getrn(lh, data, &hash);
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if (*rn == NULL) {
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if ((nn = OPENSSL_malloc(sizeof(*nn))) == NULL) {
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lh->error++;
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return (NULL);
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}
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nn->data = data;
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nn->next = NULL;
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nn->hash = hash;
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*rn = nn;
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ret = NULL;
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lh->num_insert++;
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lh->num_items++;
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} else { /* replace same key */
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ret = (*rn)->data;
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(*rn)->data = data;
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lh->num_replace++;
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}
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return (ret);
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}
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void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data)
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{
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unsigned long hash;
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OPENSSL_LH_NODE *nn, **rn;
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void *ret;
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lh->error = 0;
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rn = getrn(lh, data, &hash);
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if (*rn == NULL) {
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lh->num_no_delete++;
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return (NULL);
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} else {
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nn = *rn;
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*rn = nn->next;
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ret = nn->data;
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OPENSSL_free(nn);
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lh->num_delete++;
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}
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lh->num_items--;
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if ((lh->num_nodes > MIN_NODES) &&
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(lh->down_load >= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)))
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contract(lh);
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return (ret);
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}
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void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data)
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{
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unsigned long hash;
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OPENSSL_LH_NODE **rn;
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void *ret;
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int scratch;
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lh->error = 0;
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rn = getrn(lh, data, &hash);
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if (*rn == NULL) {
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CRYPTO_atomic_add(&lh->num_retrieve_miss, 1, &scratch, lh->retrieve_stats_lock);
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return NULL;
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} else {
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ret = (*rn)->data;
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CRYPTO_atomic_add(&lh->num_retrieve, 1, &scratch, lh->retrieve_stats_lock);
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}
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return ret;
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}
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static void doall_util_fn(OPENSSL_LHASH *lh, int use_arg,
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OPENSSL_LH_DOALL_FUNC func,
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OPENSSL_LH_DOALL_FUNCARG func_arg, void *arg)
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{
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int i;
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OPENSSL_LH_NODE *a, *n;
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if (lh == NULL)
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return;
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/*
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* reverse the order so we search from 'top to bottom' We were having
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* memory leaks otherwise
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*/
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for (i = lh->num_nodes - 1; i >= 0; i--) {
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a = lh->b[i];
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while (a != NULL) {
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n = a->next;
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if (use_arg)
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func_arg(a->data, arg);
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else
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func(a->data);
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a = n;
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}
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}
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}
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void OPENSSL_LH_doall(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNC func)
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{
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doall_util_fn(lh, 0, func, (OPENSSL_LH_DOALL_FUNCARG)0, NULL);
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}
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void OPENSSL_LH_doall_arg(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNCARG func, void *arg)
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{
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doall_util_fn(lh, 1, (OPENSSL_LH_DOALL_FUNC)0, func, arg);
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}
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static int expand(OPENSSL_LHASH *lh)
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{
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OPENSSL_LH_NODE **n, **n1, **n2, *np;
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unsigned int p, pmax, nni, j;
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unsigned long hash;
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nni = lh->num_alloc_nodes;
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p = lh->p;
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pmax = lh->pmax;
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if (p + 1 >= pmax) {
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j = nni * 2;
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n = OPENSSL_realloc(lh->b, sizeof(OPENSSL_LH_NODE *) * j);
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if (n == NULL) {
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lh->error++;
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return 0;
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}
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lh->b = n;
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memset(n + nni, 0, sizeof(*n) * (j - nni));
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lh->pmax = nni;
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lh->num_alloc_nodes = j;
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lh->num_expand_reallocs++;
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lh->p = 0;
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} else {
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lh->p++;
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}
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lh->num_nodes++;
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lh->num_expands++;
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n1 = &(lh->b[p]);
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n2 = &(lh->b[p + pmax]);
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*n2 = NULL;
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for (np = *n1; np != NULL;) {
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hash = np->hash;
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if ((hash % nni) != p) { /* move it */
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*n1 = (*n1)->next;
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np->next = *n2;
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*n2 = np;
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} else
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n1 = &((*n1)->next);
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np = *n1;
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}
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return 1;
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}
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static void contract(OPENSSL_LHASH *lh)
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{
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OPENSSL_LH_NODE **n, *n1, *np;
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np = lh->b[lh->p + lh->pmax - 1];
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lh->b[lh->p + lh->pmax - 1] = NULL; /* 24/07-92 - eay - weird but :-( */
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if (lh->p == 0) {
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n = OPENSSL_realloc(lh->b,
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(unsigned int)(sizeof(OPENSSL_LH_NODE *) * lh->pmax));
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if (n == NULL) {
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/* fputs("realloc error in lhash",stderr); */
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lh->error++;
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return;
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}
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lh->num_contract_reallocs++;
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lh->num_alloc_nodes /= 2;
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lh->pmax /= 2;
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lh->p = lh->pmax - 1;
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lh->b = n;
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} else
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lh->p--;
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lh->num_nodes--;
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lh->num_contracts++;
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n1 = lh->b[(int)lh->p];
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if (n1 == NULL)
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lh->b[(int)lh->p] = np;
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else {
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while (n1->next != NULL)
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n1 = n1->next;
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n1->next = np;
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}
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}
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static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh,
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const void *data, unsigned long *rhash)
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{
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OPENSSL_LH_NODE **ret, *n1;
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unsigned long hash, nn;
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OPENSSL_LH_COMPFUNC cf;
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int scratch;
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hash = (*(lh->hash)) (data);
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CRYPTO_atomic_add(&lh->num_hash_calls, 1, &scratch, lh->retrieve_stats_lock);
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*rhash = hash;
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nn = hash % lh->pmax;
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if (nn < lh->p)
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nn = hash % lh->num_alloc_nodes;
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cf = lh->comp;
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ret = &(lh->b[(int)nn]);
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for (n1 = *ret; n1 != NULL; n1 = n1->next) {
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CRYPTO_atomic_add(&lh->num_hash_comps, 1, &scratch, lh->retrieve_stats_lock);
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if (n1->hash != hash) {
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ret = &(n1->next);
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continue;
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}
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CRYPTO_atomic_add(&lh->num_comp_calls, 1, &scratch, lh->retrieve_stats_lock);
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if (cf(n1->data, data) == 0)
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break;
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ret = &(n1->next);
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}
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return (ret);
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}
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/*
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* The following hash seems to work very well on normal text strings no
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* collisions on /usr/dict/words and it distributes on %2^n quite well, not
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* as good as MD5, but still good.
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*/
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unsigned long OPENSSL_LH_strhash(const char *c)
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{
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unsigned long ret = 0;
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long n;
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unsigned long v;
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int r;
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if ((c == NULL) || (*c == '\0'))
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return (ret);
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/*-
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unsigned char b[16];
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MD5(c,strlen(c),b);
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return(b[0]|(b[1]<<8)|(b[2]<<16)|(b[3]<<24));
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*/
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n = 0x100;
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while (*c) {
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v = n | (*c);
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n += 0x100;
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r = (int)((v >> 2) ^ v) & 0x0f;
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ret = (ret << r) | (ret >> (32 - r));
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ret &= 0xFFFFFFFFL;
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ret ^= v * v;
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c++;
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}
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return ((ret >> 16) ^ ret);
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}
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unsigned long OPENSSL_LH_num_items(const OPENSSL_LHASH *lh)
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{
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return lh ? lh->num_items : 0;
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}
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unsigned long OPENSSL_LH_get_down_load(const OPENSSL_LHASH *lh)
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{
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return lh->down_load;
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}
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void OPENSSL_LH_set_down_load(OPENSSL_LHASH *lh, unsigned long down_load)
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{
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lh->down_load = down_load;
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}
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int OPENSSL_LH_error(OPENSSL_LHASH *lh)
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{
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return lh->error;
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}
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