1/*
2 * Copyright 1995-2019 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 "crypto/ctype.h"
17#include "crypto/lhash.h"
18#include "lhash_local.h"
19
20/*
21 * A hashing implementation that appears to be based on the linear hashing
22 * algorithm:
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 * https://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
43static int expand(OPENSSL_LHASH *lh);
44static void contract(OPENSSL_LHASH *lh);
45static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh, const void *data, unsigned long *rhash);
46
47OPENSSL_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
70err:
71    OPENSSL_free(ret->b);
72    OPENSSL_free(ret);
73    return NULL;
74}
75
76void 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
96void *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
128void *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
156void *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
177static 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
204void 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
209void 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
214static 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
260static 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
295static 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 */
331unsigned 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
354unsigned 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
375unsigned long OPENSSL_LH_num_items(const OPENSSL_LHASH *lh)
376{
377    return lh ? lh->num_items : 0;
378}
379
380unsigned long OPENSSL_LH_get_down_load(const OPENSSL_LHASH *lh)
381{
382    return lh->down_load;
383}
384
385void OPENSSL_LH_set_down_load(OPENSSL_LHASH *lh, unsigned long down_load)
386{
387    lh->down_load = down_load;
388}
389
390int OPENSSL_LH_error(OPENSSL_LHASH *lh)
391{
392    return lh->error;
393}
394