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lhash.c

/* 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>

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=(LHASH *)OPENSSL_malloc(sizeof(LHASH))) == NULL)
            goto err0;
      if ((ret->b=(LHASH_NODE **)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, const void *data)
      {
      unsigned long hash;
      LHASH_NODE *nn,**rn;
      const 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((void *)ret);
      }

void *lh_delete(LHASH *lh, const void *data)
      {
      unsigned long hash;
      LHASH_NODE *nn,**rn;
      const 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((void *)ret);
      }

void *lh_retrieve(LHASH *lh, const void *data)
      {
      unsigned long hash;
      LHASH_NODE **rn;
      const 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((void *)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;

      /* 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 */
                  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,
                  (unsigned 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;
      int (*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;
      }

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