lhash.c

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/* crypto/lhash/lhash.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * 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 ([email protected]).
 * 
 * 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 ([email protected])"
 *    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 ([email protected])"
 * 
 * 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>

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 void 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);

    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 void expand(_LHASH *lh)
    {
    LHASH_NODE **n,**n1,**n2,*np;
    unsigned int p,i,j;
    unsigned long hash,nni;

    lh->num_nodes++;
    lh->num_expands++;
    p=(int)lh->p++;
    n1= &(lh->b[p]);
    n2= &(lh->b[p+(int)lh->pmax]);
    *n2=NULL;        /* 27/07/92 - eay - undefined pointer bug */
    nni=lh->num_alloc_nodes;
    
    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;
        }

    if ((lh->p) >= lh->pmax)
        {
        j=(int)lh->num_alloc_nodes*2;
        n=(LHASH_NODE **)OPENSSL_realloc(lh->b,
            (int)(sizeof(LHASH_NODE *)*j));
        if (n == NULL)
            {
/*          fputs("realloc error in lhash",stderr); */
            lh->error++;
            lh->p=0;
            return;
            }
        /* else */
        for (i=(int)lh->num_alloc_nodes; i<j; i++)/* 26/02/92 eay */
            n[i]=NULL;            /* 02/03/92 eay */
        lh->pmax=lh->num_alloc_nodes;
        lh->num_alloc_nodes=j;
        lh->num_expand_reallocs++;
        lh->p=0;
        lh->b=n;
        }
    }

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;
    }