crypto/lhash/lhash.c

   1 /*
   2  * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <stdlib.h>
  13 #include <openssl/crypto.h>
  14 #include <openssl/lhash.h>
  15 #include <openssl/err.h>
  16 #include "internal/ctype.h"
  17 #include "internal/lhash.h"
  18 #include "lhash_lcl.h"
  19
  20 /*
  21  * A hashing implementation that appears to be based on the linear hashing
  22  * alogrithm:
  23  * https://en.wikipedia.org/wiki/Linear_hashing
  24  *
  25  * Litwin, Witold (1980), "Linear hashing: A new tool for file and table
  26  * addressing", Proc. 6th Conference on Very Large Databases: 212-223
  27  * http://hackthology.com/pdfs/Litwin-1980-Linear_Hashing.pdf
  28  *
  29  * From the wikipedia article "Linear hashing is used in the BDB Berkeley
  30  * database system, which in turn is used by many software systems such as
  31  * OpenLDAP, using a C implementation derived from the CACM article and first
  32  * published on the Usenet in 1988 by Esmond Pitt."
  33  *
  34  * The CACM paper is available here:
  35  * https://pdfs.semanticscholar.org/ff4d/1c5deca6269cc316bfd952172284dbf610ee.pdf
  36  */
  37
  38 #undef MIN_NODES
  39 #define MIN_NODES       16
  40 #define UP_LOAD         (2*LH_LOAD_MULT) /* load times 256 (default 2) */
  41 #define DOWN_LOAD       (LH_LOAD_MULT) /* load times 256 (default 1) */
  42
  43 static int expand(OPENSSL_LHASH *lh);
  44 static void contract(OPENSSL_LHASH *lh);
  45 static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh, const void *data, unsigned long *rhash);
  46
  47 OPENSSL_LHASH *OPENSSL_LH_new(OPENSSL_LH_HASHFUNC h, OPENSSL_LH_COMPFUNC c)
  48 {
  49     OPENSSL_LHASH *ret;
  50
  51     if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
  52         /*
  53          * Do not set the error code, because the ERR code uses LHASH
  54          * and we want to avoid possible endless error loop.
  55          * CRYPTOerr(CRYPTO_F_OPENSSL_LH_NEW, ERR_R_MALLOC_FAILURE);
  56          */
  57         return NULL;
  58     }
  59     if ((ret->b = OPENSSL_zalloc(sizeof(*ret->b) * MIN_NODES)) == NULL)
  60         goto err;
  61     ret->comp = ((c == NULL) ? (OPENSSL_LH_COMPFUNC)strcmp : c);
  62     ret->hash = ((h == NULL) ? (OPENSSL_LH_HASHFUNC)OPENSSL_LH_strhash : h);
  63     ret->num_nodes = MIN_NODES / 2;
  64     ret->num_alloc_nodes = MIN_NODES;
  65     ret->pmax = MIN_NODES / 2;
  66     ret->up_load = UP_LOAD;
  67     ret->down_load = DOWN_LOAD;
  68     return ret;
  69
  70 err:
  71     OPENSSL_free(ret->b);
  72     OPENSSL_free(ret);
  73     return NULL;
  74 }
  75
  76 void OPENSSL_LH_free(OPENSSL_LHASH *lh)
  77 {
  78     unsigned int i;
  79     OPENSSL_LH_NODE *n, *nn;
  80
  81     if (lh == NULL)
  82         return;
  83
  84     for (i = 0; i < lh->num_nodes; i++) {
  85         n = lh->b[i];
  86         while (n != NULL) {
  87             nn = n->next;
  88             OPENSSL_free(n);
  89             n = nn;
  90         }
  91     }
  92     OPENSSL_free(lh->b);
  93     OPENSSL_free(lh);
  94 }
  95
  96 void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data)
  97 {
  98     unsigned long hash;
  99     OPENSSL_LH_NODE *nn, **rn;
 100     void *ret;
 101
 102     lh->error = 0;
 103     if ((lh->up_load <= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)) && !expand(lh))
 104         return NULL;        /* 'lh->error++' already done in 'expand' */
 105
 106     rn = getrn(lh, data, &hash);
 107
 108     if (*rn == NULL) {
 109         if ((nn = OPENSSL_malloc(sizeof(*nn))) == NULL) {
 110             lh->error++;
 111             return NULL;
 112         }
 113         nn->data = data;
 114         nn->next = NULL;
 115         nn->hash = hash;
 116         *rn = nn;
 117         ret = NULL;
 118         lh->num_insert++;
 119         lh->num_items++;
 120     } else {                    /* replace same key */
 121         ret = (*rn)->data;
 122         (*rn)->data = data;
 123         lh->num_replace++;
 124     }
 125     return ret;
 126 }
 127
 128 void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data)
 129 {
 130     unsigned long hash;
 131     OPENSSL_LH_NODE *nn, **rn;
 132     void *ret;
 133
 134     lh->error = 0;
 135     rn = getrn(lh, data, &hash);
 136
 137     if (*rn == NULL) {
 138         lh->num_no_delete++;
 139         return NULL;
 140     } else {
 141         nn = *rn;
 142         *rn = nn->next;
 143         ret = nn->data;
 144         OPENSSL_free(nn);
 145         lh->num_delete++;
 146     }
 147
 148     lh->num_items--;
 149     if ((lh->num_nodes > MIN_NODES) &&
 150         (lh->down_load >= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)))
 151         contract(lh);
 152
 153     return ret;
 154 }
 155
 156 void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data)
 157 {
 158     unsigned long hash;
 159     OPENSSL_LH_NODE **rn;
 160     void *ret;
 161
 162     tsan_store((TSAN_QUALIFIER int *)&lh->error, 0);
 163
 164     rn = getrn(lh, data, &hash);
 165
 166     if (*rn == NULL) {
 167         tsan_counter(&lh->num_retrieve_miss);
 168         return NULL;
 169     } else {
 170         ret = (*rn)->data;
 171         tsan_counter(&lh->num_retrieve);
 172     }
 173
 174     return ret;
 175 }
 176
 177 static void doall_util_fn(OPENSSL_LHASH *lh, int use_arg,
 178                           OPENSSL_LH_DOALL_FUNC func,
 179                           OPENSSL_LH_DOALL_FUNCARG func_arg, void *arg)
 180 {
 181     int i;
 182     OPENSSL_LH_NODE *a, *n;
 183
 184     if (lh == NULL)
 185         return;
 186
 187     /*
 188      * reverse the order so we search from 'top to bottom' We were having
 189      * memory leaks otherwise
 190      */
 191     for (i = lh->num_nodes - 1; i >= 0; i--) {
 192         a = lh->b[i];
 193         while (a != NULL) {
 194             n = a->next;
 195             if (use_arg)
 196                 func_arg(a->data, arg);
 197             else
 198                 func(a->data);
 199             a = n;
 200         }
 201     }
 202 }
 203
 204 void OPENSSL_LH_doall(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNC func)
 205 {
 206     doall_util_fn(lh, 0, func, (OPENSSL_LH_DOALL_FUNCARG)0, NULL);
 207 }
 208
 209 void OPENSSL_LH_doall_arg(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNCARG func, void *arg)
 210 {
 211     doall_util_fn(lh, 1, (OPENSSL_LH_DOALL_FUNC)0, func, arg);
 212 }
 213
 214 static int expand(OPENSSL_LHASH *lh)
 215 {
 216     OPENSSL_LH_NODE **n, **n1, **n2, *np;
 217     unsigned int p, pmax, nni, j;
 218     unsigned long hash;
 219
 220     nni = lh->num_alloc_nodes;
 221     p = lh->p;
 222     pmax = lh->pmax;
 223     if (p + 1 >= pmax) {
 224         j = nni * 2;
 225         n = OPENSSL_realloc(lh->b, sizeof(OPENSSL_LH_NODE *) * j);
 226         if (n == NULL) {
 227             lh->error++;
 228             return 0;
 229         }
 230         lh->b = n;
 231         memset(n + nni, 0, sizeof(*n) * (j - nni));
 232         lh->pmax = nni;
 233         lh->num_alloc_nodes = j;
 234         lh->num_expand_reallocs++;
 235         lh->p = 0;
 236     } else {
 237         lh->p++;
 238     }
 239
 240     lh->num_nodes++;
 241     lh->num_expands++;
 242     n1 = &(lh->b[p]);
 243     n2 = &(lh->b[p + pmax]);
 244     *n2 = NULL;
 245
 246     for (np = *n1; np != NULL;) {
 247         hash = np->hash;
 248         if ((hash % nni) != p) { /* move it */
 249             *n1 = (*n1)->next;
 250             np->next = *n2;
 251             *n2 = np;
 252         } else
 253             n1 = &((*n1)->next);
 254         np = *n1;
 255     }
 256
 257     return 1;
 258 }
 259
 260 static void contract(OPENSSL_LHASH *lh)
 261 {
 262     OPENSSL_LH_NODE **n, *n1, *np;
 263
 264     np = lh->b[lh->p + lh->pmax - 1];
 265     lh->b[lh->p + lh->pmax - 1] = NULL; /* 24/07-92 - eay - weird but :-( */
 266     if (lh->p == 0) {
 267         n = OPENSSL_realloc(lh->b,
 268                             (unsigned int)(sizeof(OPENSSL_LH_NODE *) * lh->pmax));
 269         if (n == NULL) {
 270             /* fputs("realloc error in lhash",stderr); */
 271             lh->error++;
 272             return;
 273         }
 274         lh->num_contract_reallocs++;
 275         lh->num_alloc_nodes /= 2;
 276         lh->pmax /= 2;
 277         lh->p = lh->pmax - 1;
 278         lh->b = n;
 279     } else
 280         lh->p--;
 281
 282     lh->num_nodes--;
 283     lh->num_contracts++;
 284
 285     n1 = lh->b[(int)lh->p];
 286     if (n1 == NULL)
 287         lh->b[(int)lh->p] = np;
 288     else {
 289         while (n1->next != NULL)
 290             n1 = n1->next;
 291         n1->next = np;
 292     }
 293 }
 294
 295 static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh,
 296                                const void *data, unsigned long *rhash)
 297 {
 298     OPENSSL_LH_NODE **ret, *n1;
 299     unsigned long hash, nn;
 300     OPENSSL_LH_COMPFUNC cf;
 301
 302     hash = (*(lh->hash)) (data);
 303     tsan_counter(&lh->num_hash_calls);
 304     *rhash = hash;
 305
 306     nn = hash % lh->pmax;
 307     if (nn < lh->p)
 308         nn = hash % lh->num_alloc_nodes;
 309
 310     cf = lh->comp;
 311     ret = &(lh->b[(int)nn]);
 312     for (n1 = *ret; n1 != NULL; n1 = n1->next) {
 313         tsan_counter(&lh->num_hash_comps);
 314         if (n1->hash != hash) {
 315             ret = &(n1->next);
 316             continue;
 317         }
 318         tsan_counter(&lh->num_comp_calls);
 319         if (cf(n1->data, data) == 0)
 320             break;
 321         ret = &(n1->next);
 322     }
 323     return ret;
 324 }
 325
 326 /*
 327  * The following hash seems to work very well on normal text strings no
 328  * collisions on /usr/dict/words and it distributes on %2^n quite well, not
 329  * as good as MD5, but still good.
 330  */
 331 unsigned long OPENSSL_LH_strhash(const char *c)
 332 {
 333     unsigned long ret = 0;
 334     long n;
 335     unsigned long v;
 336     int r;
 337
 338     if ((c == NULL) || (*c == '\0'))
 339         return ret;
 340
 341     n = 0x100;
 342     while (*c) {
 343         v = n | (*c);
 344         n += 0x100;
 345         r = (int)((v >> 2) ^ v) & 0x0f;
 346         ret = (ret << r) | (ret >> (32 - r));
 347         ret &= 0xFFFFFFFFL;
 348         ret ^= v * v;
 349         c++;
 350     }
 351     return (ret >> 16) ^ ret;
 352 }
 353
 354 unsigned long openssl_lh_strcasehash(const char *c)
 355 {
 356     unsigned long ret = 0;
 357     long n;
 358     unsigned long v;
 359     int r;
 360
 361     if (c == NULL || *c == '\0')
 362         return ret;
 363
 364     for (n = 0x100; *c != '\0'; n += 0x100) {
 365         v = n | ossl_tolower(*c);
 366         r = (int)((v >> 2) ^ v) & 0x0f;
 367         ret = (ret << r) | (ret >> (32 - r));
 368         ret &= 0xFFFFFFFFL;
 369         ret ^= v * v;
 370         c++;
 371     }
 372     return (ret >> 16) ^ ret;
 373 }
 374
 375 unsigned long OPENSSL_LH_num_items(const OPENSSL_LHASH *lh)
 376 {
 377     return lh ? lh->num_items : 0;
 378 }
 379
 380 unsigned long OPENSSL_LH_get_down_load(const OPENSSL_LHASH *lh)
 381 {
 382     return lh->down_load;
 383 }
 384
 385 void OPENSSL_LH_set_down_load(OPENSSL_LHASH *lh, unsigned long down_load)
 386 {
 387     lh->down_load = down_load;
 388 }
 389
 390 int OPENSSL_LH_error(OPENSSL_LHASH *lh)
 391 {
 392     return lh->error;
 393 }