1/*
2 * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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         * ERR_raise(ERR_LIB_CRYPTO, 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    if (lh == NULL)
79        return;
80
81    OPENSSL_LH_flush(lh);
82    OPENSSL_free(lh->b);
83    OPENSSL_free(lh);
84}
85
86void OPENSSL_LH_flush(OPENSSL_LHASH *lh)
87{
88    unsigned int i;
89    OPENSSL_LH_NODE *n, *nn;
90
91    if (lh == NULL)
92        return;
93
94    for (i = 0; i < lh->num_nodes; i++) {
95        n = lh->b[i];
96        while (n != NULL) {
97            nn = n->next;
98            OPENSSL_free(n);
99            n = nn;
100        }
101        lh->b[i] = NULL;
102    }
103
104    lh->num_items = 0;
105}
106
107void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data)
108{
109    unsigned long hash;
110    OPENSSL_LH_NODE *nn, **rn;
111    void *ret;
112
113    lh->error = 0;
114    if ((lh->up_load <= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)) && !expand(lh))
115        return NULL;        /* 'lh->error++' already done in 'expand' */
116
117    rn = getrn(lh, data, &hash);
118
119    if (*rn == NULL) {
120        if ((nn = OPENSSL_malloc(sizeof(*nn))) == NULL) {
121            lh->error++;
122            return NULL;
123        }
124        nn->data = data;
125        nn->next = NULL;
126        nn->hash = hash;
127        *rn = nn;
128        ret = NULL;
129        lh->num_items++;
130    } else {                    /* replace same key */
131        ret = (*rn)->data;
132        (*rn)->data = data;
133    }
134    return ret;
135}
136
137void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data)
138{
139    unsigned long hash;
140    OPENSSL_LH_NODE *nn, **rn;
141    void *ret;
142
143    lh->error = 0;
144    rn = getrn(lh, data, &hash);
145
146    if (*rn == NULL) {
147        return NULL;
148    } else {
149        nn = *rn;
150        *rn = nn->next;
151        ret = nn->data;
152        OPENSSL_free(nn);
153    }
154
155    lh->num_items--;
156    if ((lh->num_nodes > MIN_NODES) &&
157        (lh->down_load >= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)))
158        contract(lh);
159
160    return ret;
161}
162
163void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data)
164{
165    unsigned long hash;
166    OPENSSL_LH_NODE **rn;
167
168    if (lh->error != 0)
169        lh->error = 0;
170
171    rn = getrn(lh, data, &hash);
172
173    return *rn == NULL ? NULL : (*rn)->data;
174}
175
176static void doall_util_fn(OPENSSL_LHASH *lh, int use_arg,
177                          OPENSSL_LH_DOALL_FUNC func,
178                          OPENSSL_LH_DOALL_FUNCARG func_arg, void *arg)
179{
180    int i;
181    OPENSSL_LH_NODE *a, *n;
182
183    if (lh == NULL)
184        return;
185
186    /*
187     * reverse the order so we search from 'top to bottom' We were having
188     * memory leaks otherwise
189     */
190    for (i = lh->num_nodes - 1; i >= 0; i--) {
191        a = lh->b[i];
192        while (a != NULL) {
193            n = a->next;
194            if (use_arg)
195                func_arg(a->data, arg);
196            else
197                func(a->data);
198            a = n;
199        }
200    }
201}
202
203void OPENSSL_LH_doall(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNC func)
204{
205    doall_util_fn(lh, 0, func, (OPENSSL_LH_DOALL_FUNCARG)0, NULL);
206}
207
208void OPENSSL_LH_doall_arg(OPENSSL_LHASH *lh, OPENSSL_LH_DOALL_FUNCARG func, void *arg)
209{
210    doall_util_fn(lh, 1, (OPENSSL_LH_DOALL_FUNC)0, func, arg);
211}
212
213static int expand(OPENSSL_LHASH *lh)
214{
215    OPENSSL_LH_NODE **n, **n1, **n2, *np;
216    unsigned int p, pmax, nni, j;
217    unsigned long hash;
218
219    nni = lh->num_alloc_nodes;
220    p = lh->p;
221    pmax = lh->pmax;
222    if (p + 1 >= pmax) {
223        j = nni * 2;
224        n = OPENSSL_realloc(lh->b, sizeof(OPENSSL_LH_NODE *) * j);
225        if (n == NULL) {
226            lh->error++;
227            return 0;
228        }
229        lh->b = n;
230        memset(n + nni, 0, sizeof(*n) * (j - nni));
231        lh->pmax = nni;
232        lh->num_alloc_nodes = j;
233        lh->p = 0;
234    } else {
235        lh->p++;
236    }
237
238    lh->num_nodes++;
239    n1 = &(lh->b[p]);
240    n2 = &(lh->b[p + pmax]);
241    *n2 = NULL;
242
243    for (np = *n1; np != NULL;) {
244        hash = np->hash;
245        if ((hash % nni) != p) { /* move it */
246            *n1 = (*n1)->next;
247            np->next = *n2;
248            *n2 = np;
249        } else
250            n1 = &((*n1)->next);
251        np = *n1;
252    }
253
254    return 1;
255}
256
257static void contract(OPENSSL_LHASH *lh)
258{
259    OPENSSL_LH_NODE **n, *n1, *np;
260
261    np = lh->b[lh->p + lh->pmax - 1];
262    lh->b[lh->p + lh->pmax - 1] = NULL; /* 24/07-92 - eay - weird but :-( */
263    if (lh->p == 0) {
264        n = OPENSSL_realloc(lh->b,
265                            (unsigned int)(sizeof(OPENSSL_LH_NODE *) * lh->pmax));
266        if (n == NULL) {
267            /* fputs("realloc error in lhash",stderr); */
268            lh->error++;
269        } else {
270            lh->b = n;
271        }
272        lh->num_alloc_nodes /= 2;
273        lh->pmax /= 2;
274        lh->p = lh->pmax - 1;
275    } else
276        lh->p--;
277
278    lh->num_nodes--;
279
280    n1 = lh->b[(int)lh->p];
281    if (n1 == NULL)
282        lh->b[(int)lh->p] = np;
283    else {
284        while (n1->next != NULL)
285            n1 = n1->next;
286        n1->next = np;
287    }
288}
289
290static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh,
291                               const void *data, unsigned long *rhash)
292{
293    OPENSSL_LH_NODE **ret, *n1;
294    unsigned long hash, nn;
295    OPENSSL_LH_COMPFUNC cf;
296
297    hash = (*(lh->hash)) (data);
298    *rhash = hash;
299
300    nn = hash % lh->pmax;
301    if (nn < lh->p)
302        nn = hash % lh->num_alloc_nodes;
303
304    cf = lh->comp;
305    ret = &(lh->b[(int)nn]);
306    for (n1 = *ret; n1 != NULL; n1 = n1->next) {
307        if (n1->hash != hash) {
308            ret = &(n1->next);
309            continue;
310        }
311        if (cf(n1->data, data) == 0)
312            break;
313        ret = &(n1->next);
314    }
315    return ret;
316}
317
318/*
319 * The following hash seems to work very well on normal text strings no
320 * collisions on /usr/dict/words and it distributes on %2^n quite well, not
321 * as good as MD5, but still good.
322 */
323unsigned long OPENSSL_LH_strhash(const char *c)
324{
325    unsigned long ret = 0;
326    long n;
327    unsigned long v;
328    int r;
329
330    if ((c == NULL) || (*c == '\0'))
331        return ret;
332
333    n = 0x100;
334    while (*c) {
335        v = n | (*c);
336        n += 0x100;
337        r = (int)((v >> 2) ^ v) & 0x0f;
338        /* cast to uint64_t to avoid 32 bit shift of 32 bit value */
339        ret = (ret << r) | (unsigned long)((uint64_t)ret >> (32 - r));
340        ret &= 0xFFFFFFFFL;
341        ret ^= v * v;
342        c++;
343    }
344    return (ret >> 16) ^ ret;
345}
346
347unsigned long ossl_lh_strcasehash(const char *c)
348{
349    unsigned long ret = 0;
350    long n;
351    unsigned long v;
352    int r;
353
354    if (c == NULL || *c == '\0')
355        return ret;
356
357    for (n = 0x100; *c != '\0'; n += 0x100) {
358        v = n | ossl_tolower(*c);
359        r = (int)((v >> 2) ^ v) & 0x0f;
360        /* cast to uint64_t to avoid 32 bit shift of 32 bit value */
361        ret = (ret << r) | (unsigned long)((uint64_t)ret >> (32 - r));
362        ret &= 0xFFFFFFFFL;
363        ret ^= v * v;
364        c++;
365    }
366    return (ret >> 16) ^ ret;
367}
368
369unsigned long OPENSSL_LH_num_items(const OPENSSL_LHASH *lh)
370{
371    return lh ? lh->num_items : 0;
372}
373
374unsigned long OPENSSL_LH_get_down_load(const OPENSSL_LHASH *lh)
375{
376    return lh->down_load;
377}
378
379void OPENSSL_LH_set_down_load(OPENSSL_LHASH *lh, unsigned long down_load)
380{
381    lh->down_load = down_load;
382}
383
384int OPENSSL_LH_error(OPENSSL_LHASH *lh)
385{
386    return lh->error;
387}
388