/* crypto/lhash/lhash.c */

/* 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.]

 */

/*-

 * Code for dynamic hash table routines

 * Author - Eric Young v 2.0

 *

 * 2.2 eay - added #include "crypto.h" so the memory leak checking code is

 *           present. eay 18-Jun-98

 *

 * 2.1 eay - Added an 'error in last operation' flag. eay 6-May-98

 *

 * 2.0 eay - Fixed a bug that occurred when using lh_delete

 *           from inside lh_doall().  As entries were deleted,

 *           the 'table' was 'contract()ed', making some entries

 *           jump from the end of the table to the start, there by

 *           skipping the lh_doall() processing. eay - 4/12/95

 *

 * 1.9 eay - Fixed a memory leak in lh_free, the LHASH_NODEs

 *           were not being free()ed. 21/11/95

 *

 * 1.8 eay - Put the stats routines into a separate file, lh_stats.c

 *           19/09/95

 *

 * 1.7 eay - Removed the fputs() for realloc failures - the code

 *           should silently tolerate them.  I have also fixed things

 *           lint complained about 04/05/95

 *

 * 1.6 eay - Fixed an invalid pointers in contract/expand 27/07/92

 *

 * 1.5 eay - Fixed a misuse of realloc in expand 02/03/1992

 *

 * 1.4 eay - Fixed lh_doall so the function can call lh_delete 28/05/91

 *

 * 1.3 eay - Fixed a few lint problems 19/3/1991

 *

 * 1.2 eay - Fixed lh_doall problem 13/3/1991

 *

 * 1.1 eay - Added lh_doall

 *

 * 1.0 eay - First version

 */

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <openssl/crypto.h>

#include <openssl/lhash.h>

/*

 * A hashing implementation that appears to be based on the linear hashing

 * alogrithm:

 * https://en.wikipedia.org/wiki/Linear_hashing

 *

 * Litwin, Witold (1980), "Linear hashing: A new tool for file and table

 * addressing", Proc. 6th Conference on Very Large Databases: 212–223

 * http://hackthology.com/pdfs/Litwin-1980-Linear_Hashing.pdf

 *

 * From the wikipedia article "Linear hashing is used in the BDB Berkeley

 * database system, which in turn is used by many software systems such as

 * OpenLDAP, using a C implementation derived from the CACM article and first

 * published on the Usenet in 1988 by Esmond Pitt."

 *

 * The CACM paper is available here:

 * https://pdfs.semanticscholar.org/ff4d/1c5deca6269cc316bfd952172284dbf610ee.pdf

 */

const char lh_version[] = "lhash" OPENSSL_VERSION_PTEXT;

#undef MIN_NODES

#define MIN_NODES       16

#define UP_LOAD         (2*LH_LOAD_MULT) /* load times 256 (default 2) */

#define DOWN_LOAD       (LH_LOAD_MULT) /* load times 256 (default 1) */

static int expand(_LHASH *lh);

static void contract(_LHASH *lh);

static LHASH_NODE **getrn(_LHASH *lh, const void *data, unsigned long *rhash);

_LHASH *lh_new(LHASH_HASH_FN_TYPE h, LHASH_COMP_FN_TYPE c)

{

    _LHASH *ret;

    int i;

    if ((ret = OPENSSL_malloc(sizeof(_LHASH))) == NULL)

        goto err0;

    if ((ret->b = OPENSSL_malloc(sizeof(LHASH_NODE *) * MIN_NODES)) == NULL)

        goto err1;

    for (i = 0; i < MIN_NODES; i++)

        ret->b[i] = NULL;

    ret->comp = ((c == NULL) ? (LHASH_COMP_FN_TYPE)strcmp : c);

    ret->hash = ((h == NULL) ? (LHASH_HASH_FN_TYPE)lh_strhash : h);

    ret->num_nodes = MIN_NODES / 2;

    ret->num_alloc_nodes = MIN_NODES;

    ret->p = 0;

    ret->pmax = MIN_NODES / 2;

    ret->up_load = UP_LOAD;

    ret->down_load = DOWN_LOAD;

    ret->num_items = 0;

    ret->num_expands = 0;

    ret->num_expand_reallocs = 0;

    ret->num_contracts = 0;

    ret->num_contract_reallocs = 0;

    ret->num_hash_calls = 0;

    ret->num_comp_calls = 0;

    ret->num_insert = 0;

    ret->num_replace = 0;

    ret->num_delete = 0;

    ret->num_no_delete = 0;

    ret->num_retrieve = 0;

    ret->num_retrieve_miss = 0;

    ret->num_hash_comps = 0;

    ret->error = 0;

    return (ret);

 err1:

    OPENSSL_free(ret);

 err0:

    return (NULL);

}

void lh_free(_LHASH *lh)

{

    unsigned int i;

    LHASH_NODE *n, *nn;

    if (lh == NULL)

        return;

    for (i = 0; i < lh->num_nodes; i++) {

        n = lh->b[i];

        while (n != NULL) {

            nn = n->next;

            OPENSSL_free(n);

            n = nn;

        }

    }

    OPENSSL_free(lh->b);

    OPENSSL_free(lh);

}

void *lh_insert(_LHASH *lh, void *data)

{

    unsigned long hash;

    LHASH_NODE *nn, **rn;

    void *ret;

    lh->error = 0;

    if (lh->up_load <= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)

            && !expand(lh))

        return NULL;

    rn = getrn(lh, data, &hash);

    if (*rn == NULL) {

        if ((nn = (LHASH_NODE *)OPENSSL_malloc(sizeof(LHASH_NODE))) == NULL) {

            lh->error++;

            return (NULL);

        }

        nn->data = data;

        nn->next = NULL;

#ifndef OPENSSL_NO_HASH_COMP

        nn->hash = hash;

#endif

        *rn = nn;

        ret = NULL;

        lh->num_insert++;

        lh->num_items++;

    } else {                    /* replace same key */

        ret = (*rn)->data;

        (*rn)->data = data;

        lh->num_replace++;

    }

    return (ret);

}

void *lh_delete(_LHASH *lh, const void *data)

{

    unsigned long hash;

    LHASH_NODE *nn, **rn;

    void *ret;

    lh->error = 0;

    rn = getrn(lh, data, &hash);

    if (*rn == NULL) {

        lh->num_no_delete++;

        return (NULL);

    } else {

        nn = *rn;

        *rn = nn->next;

        ret = nn->data;

        OPENSSL_free(nn);

        lh->num_delete++;

    }

    lh->num_items--;

    if ((lh->num_nodes > MIN_NODES) &&

        (lh->down_load >= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)))

        contract(lh);

    return (ret);

}

void *lh_retrieve(_LHASH *lh, const void *data)

{

    unsigned long hash;

    LHASH_NODE **rn;

    void *ret;

    lh->error = 0;

    rn = getrn(lh, data, &hash);

    if (*rn == NULL) {

        lh->num_retrieve_miss++;

        return (NULL);

    } else {

        ret = (*rn)->data;

        lh->num_retrieve++;

    }

    return (ret);

}

static void doall_util_fn(_LHASH *lh, int use_arg, LHASH_DOALL_FN_TYPE func,

                          LHASH_DOALL_ARG_FN_TYPE func_arg, void *arg)

{

    int i;

    LHASH_NODE *a, *n;

    if (lh == NULL)

        return;

    /*

     * reverse the order so we search from 'top to bottom' We were having

     * memory leaks otherwise

     */

    for (i = lh->num_nodes - 1; i >= 0; i--) {

        a = lh->b[i];

        while (a != NULL) {

            /*

             * 28/05/91 - eay - n added so items can be deleted via lh_doall

             */

            /*

             * 22/05/08 - ben - eh? since a is not passed, this should not be

             * needed

             */

            n = a->next;

            if (use_arg)

                func_arg(a->data, arg);

            else

                func(a->data);

            a = n;

        }

    }

}

void lh_doall(_LHASH *lh, LHASH_DOALL_FN_TYPE func)

{

    doall_util_fn(lh, 0, func, (LHASH_DOALL_ARG_FN_TYPE)0, NULL);

}

void lh_doall_arg(_LHASH *lh, LHASH_DOALL_ARG_FN_TYPE func, void *arg)

{

    doall_util_fn(lh, 1, (LHASH_DOALL_FN_TYPE)0, func, arg);

}

static int expand(_LHASH *lh)

{

    LHASH_NODE **n, **n1, **n2, *np;

    unsigned int p, pmax, nni, j;

    unsigned long hash;

    nni = lh->num_alloc_nodes;

    p = lh->p;

    pmax = lh->pmax;

    if (p + 1 >= pmax) {

        j = nni * 2;

        n = OPENSSL_realloc(lh->b, (int)(sizeof(LHASH_NODE *) * j));

        if (n == NULL) {

            lh->error++;

            return 0;

        }

        lh->b = n;

        memset(n + nni, 0, sizeof(*n) * (j - nni));

        lh->pmax = nni;

        lh->num_alloc_nodes = j;

        lh->num_expand_reallocs++;

        lh->p = 0;

    } else {

        lh->p++;

    }

    lh->num_nodes++;

    lh->num_expands++;

    n1 = &(lh->b[p]);

    n2 = &(lh->b[p + pmax]);

    *n2 = NULL;

    for (np = *n1; np != NULL;) {

#ifndef OPENSSL_NO_HASH_COMP

        hash = np->hash;

#else

        hash = lh->hash(np->data);

        lh->num_hash_calls++;

#endif

        if ((hash % nni) != p) { /* move it */

            *n1 = (*n1)->next;

            np->next = *n2;

            *n2 = np;

        } else

            n1 = &((*n1)->next);

        np = *n1;

    }

    return 1;

}

static void contract(_LHASH *lh)

{

    LHASH_NODE **n, *n1, *np;

    np = lh->b[lh->p + lh->pmax - 1];

    lh->b[lh->p + lh->pmax - 1] = NULL; /* 24/07-92 - eay - weird but :-( */

    if (lh->p == 0) {

        n = (LHASH_NODE **)OPENSSL_realloc(lh->b,

                                           (unsigned int)(sizeof(LHASH_NODE *)

                                                          * lh->pmax));

        if (n == NULL) {

/*                      fputs("realloc error in lhash",stderr); */

            lh->error++;

            return;

        }

        lh->num_contract_reallocs++;

        lh->num_alloc_nodes /= 2;

        lh->pmax /= 2;

        lh->p = lh->pmax - 1;

        lh->b = n;

    } else

        lh->p--;

    lh->num_nodes--;

    lh->num_contracts++;

    n1 = lh->b[(int)lh->p];

    if (n1 == NULL)

        lh->b[(int)lh->p] = np;

    else {

        while (n1->next != NULL)

            n1 = n1->next;

        n1->next = np;

    }

}

static LHASH_NODE **getrn(_LHASH *lh, const void *data, unsigned long *rhash)

{

    LHASH_NODE **ret, *n1;

    unsigned long hash, nn;

    LHASH_COMP_FN_TYPE cf;

    hash = (*(lh->hash)) (data);

    lh->num_hash_calls++;

    *rhash = hash;

    nn = hash % lh->pmax;

    if (nn < lh->p)

        nn = hash % lh->num_alloc_nodes;

    cf = lh->comp;

    ret = &(lh->b[(int)nn]);

    for (n1 = *ret; n1 != NULL; n1 = n1->next) {

#ifndef OPENSSL_NO_HASH_COMP

        lh->num_hash_comps++;

        if (n1->hash != hash) {

            ret = &(n1->next);

            continue;

        }

#endif

        lh->num_comp_calls++;

        if (cf(n1->data, data) == 0)

            break;

        ret = &(n1->next);

    }

    return (ret);

}

/*

 * 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 lh_strhash(const char *c)

{

    unsigned long ret = 0;

    long n;

    unsigned long v;

    int r;

    if ((c == NULL) || (*c == '\0'))

        return (ret);

/*-

    unsigned char b[16];

    MD5(c,strlen(c),b);

    return(b[0]|(b[1]<<8)|(b[2]<<16)|(b[3]<<24));

*/

    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);

}

unsigned long lh_num_items(const _LHASH *lh)

{

    return lh ? lh->num_items : 0;

}