1/*
2 * Copyright (C) 2004-2007, 2009, 2013, 2014  Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 2003  Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/* $Id: hash.c,v 1.16 2009/09/01 00:22:28 jinmei Exp $ */
19
20/*! \file
21 * Some portion of this code was derived from universal hash function
22 * libraries of Rice University.
23\section license UH Universal Hashing Library
24
25Copyright ((c)) 2002, Rice University
26All rights reserved.
27
28Redistribution and use in source and binary forms, with or without
29modification, are permitted provided that the following conditions are
30met:
31
32    * Redistributions of source code must retain the above copyright
33    notice, this list of conditions and the following disclaimer.
34
35    * Redistributions in binary form must reproduce the above
36    copyright notice, this list of conditions and the following
37    disclaimer in the documentation and/or other materials provided
38    with the distribution.
39
40    * Neither the name of Rice University (RICE) nor the names of its
41    contributors may be used to endorse or promote products derived
42    from this software without specific prior written permission.
43
44
45This software is provided by RICE and the contributors on an "as is"
46basis, without any representations or warranties of any kind, express
47or implied including, but not limited to, representations or
48warranties of non-infringement, merchantability or fitness for a
49particular purpose. In no event shall RICE or contributors be liable
50for any direct, indirect, incidental, special, exemplary, or
51consequential damages (including, but not limited to, procurement of
52substitute goods or services; loss of use, data, or profits; or
53business interruption) however caused and on any theory of liability,
54whether in contract, strict liability, or tort (including negligence
55or otherwise) arising in any way out of the use of this software, even
56if advised of the possibility of such damage.
57*/
58
59#include <config.h>
60
61#include <isc/entropy.h>
62#include <isc/hash.h>
63#include <isc/mem.h>
64#include <isc/magic.h>
65#include <isc/mutex.h>
66#include <isc/once.h>
67#include <isc/random.h>
68#include <isc/refcount.h>
69#include <isc/string.h>
70#include <isc/util.h>
71
72#define HASH_MAGIC		ISC_MAGIC('H', 'a', 's', 'h')
73#define VALID_HASH(h)		ISC_MAGIC_VALID((h), HASH_MAGIC)
74
75/*%
76 * A large 32-bit prime number that specifies the range of the hash output.
77 */
78#define PRIME32 0xFFFFFFFB              /* 2^32 -  5 */
79
80/*@{*/
81/*%
82 * Types of random seed and hash accumulator.  Perhaps they can be system
83 * dependent.
84 */
85typedef isc_uint32_t hash_accum_t;
86typedef isc_uint16_t hash_random_t;
87/*@}*/
88
89/*% isc hash structure */
90struct isc_hash {
91	unsigned int	magic;
92	isc_mem_t	*mctx;
93	isc_mutex_t	lock;
94	isc_boolean_t	initialized;
95	isc_refcount_t	refcnt;
96	isc_entropy_t	*entropy; /*%< entropy source */
97	size_t		limit;	/*%< upper limit of key length */
98	size_t		vectorlen; /*%< size of the vector below */
99	hash_random_t	*rndvector; /*%< random vector for universal hashing */
100};
101
102static isc_mutex_t createlock;
103static isc_once_t once = ISC_ONCE_INIT;
104static isc_hash_t *hash = NULL;
105
106static unsigned char maptolower[] = {
107	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
108	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
109	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
110	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
111	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
112	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
113	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
114	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
115	0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
116	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
117	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
118	0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
119	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
120	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
121	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
122	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
123	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
124	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
125	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
126	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
127	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
128	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
129	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
130	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
131	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
132	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
133	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
134	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
135	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
136	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
137	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
138	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
139};
140
141isc_result_t
142isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
143		   size_t limit, isc_hash_t **hctxp)
144{
145	isc_result_t result;
146	isc_hash_t *hctx;
147	size_t vlen;
148	hash_random_t *rv;
149	hash_accum_t overflow_limit;
150
151	REQUIRE(mctx != NULL);
152	REQUIRE(hctxp != NULL && *hctxp == NULL);
153
154	/*
155	 * Overflow check.  Since our implementation only does a modulo
156	 * operation at the last stage of hash calculation, the accumulator
157	 * must not overflow.
158	 */
159	overflow_limit =
160		1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8);
161	if (overflow_limit < (limit + 1) * 0xff)
162		return (ISC_R_RANGE);
163
164	hctx = isc_mem_get(mctx, sizeof(isc_hash_t));
165	if (hctx == NULL)
166		return (ISC_R_NOMEMORY);
167
168	vlen = sizeof(hash_random_t) * (limit + 1);
169	rv = isc_mem_get(mctx, vlen);
170	if (rv == NULL) {
171		result = ISC_R_NOMEMORY;
172		goto errout;
173	}
174
175	/*
176	 * We need a lock.
177	 */
178	result = isc_mutex_init(&hctx->lock);
179	if (result != ISC_R_SUCCESS)
180		goto errout;
181
182	/*
183	 * From here down, no failures will/can occur.
184	 */
185	hctx->magic = HASH_MAGIC;
186	hctx->mctx = NULL;
187	isc_mem_attach(mctx, &hctx->mctx);
188	hctx->initialized = ISC_FALSE;
189	result = isc_refcount_init(&hctx->refcnt, 1);
190	if (result != ISC_R_SUCCESS)
191		goto cleanup_lock;
192	hctx->entropy = NULL;
193	hctx->limit = limit;
194	hctx->vectorlen = vlen;
195	hctx->rndvector = rv;
196
197#ifdef BIND9
198	if (entropy != NULL)
199		isc_entropy_attach(entropy, &hctx->entropy);
200#else
201	UNUSED(entropy);
202#endif
203
204	*hctxp = hctx;
205	return (ISC_R_SUCCESS);
206
207 cleanup_lock:
208	DESTROYLOCK(&hctx->lock);
209 errout:
210	isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
211	if (rv != NULL)
212		isc_mem_put(mctx, rv, vlen);
213
214	return (result);
215}
216
217static void
218initialize_lock(void) {
219	RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
220}
221
222isc_result_t
223isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
224	isc_result_t result = ISC_R_SUCCESS;
225
226	REQUIRE(mctx != NULL);
227	INSIST(hash == NULL);
228
229	RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
230
231	LOCK(&createlock);
232
233	if (hash == NULL)
234		result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
235
236	UNLOCK(&createlock);
237
238	return (result);
239}
240
241void
242isc_hash_ctxinit(isc_hash_t *hctx) {
243	LOCK(&hctx->lock);
244
245	if (hctx->initialized == ISC_TRUE)
246		goto out;
247
248	if (hctx->entropy) {
249#ifdef BIND9
250		isc_result_t result;
251
252		result = isc_entropy_getdata(hctx->entropy,
253					     hctx->rndvector,
254					     (unsigned int)hctx->vectorlen,
255					     NULL, 0);
256		INSIST(result == ISC_R_SUCCESS);
257#else
258		INSIST(0);
259#endif
260	} else {
261		isc_uint32_t pr;
262		size_t i, copylen;
263		unsigned char *p;
264
265		p = (unsigned char *)hctx->rndvector;
266		for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
267			isc_random_get(&pr);
268			if (i + sizeof(pr) <= hctx->vectorlen)
269				copylen = sizeof(pr);
270			else
271				copylen = hctx->vectorlen - i;
272
273			memmove(p, &pr, copylen);
274		}
275		INSIST(p == (unsigned char *)hctx->rndvector +
276		       hctx->vectorlen);
277	}
278
279	hctx->initialized = ISC_TRUE;
280
281 out:
282	UNLOCK(&hctx->lock);
283}
284
285void
286isc_hash_init() {
287	INSIST(hash != NULL && VALID_HASH(hash));
288
289	isc_hash_ctxinit(hash);
290}
291
292void
293isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
294	REQUIRE(VALID_HASH(hctx));
295	REQUIRE(hctxp != NULL && *hctxp == NULL);
296
297	isc_refcount_increment(&hctx->refcnt, NULL);
298	*hctxp = hctx;
299}
300
301static void
302destroy(isc_hash_t **hctxp) {
303	isc_hash_t *hctx;
304	isc_mem_t *mctx;
305	unsigned char canary0[4], canary1[4];
306
307	REQUIRE(hctxp != NULL && *hctxp != NULL);
308	hctx = *hctxp;
309	*hctxp = NULL;
310
311	LOCK(&hctx->lock);
312
313	isc_refcount_destroy(&hctx->refcnt);
314
315	mctx = hctx->mctx;
316#ifdef BIND9
317	if (hctx->entropy != NULL)
318		isc_entropy_detach(&hctx->entropy);
319#endif
320	if (hctx->rndvector != NULL)
321		isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
322
323	UNLOCK(&hctx->lock);
324
325	DESTROYLOCK(&hctx->lock);
326
327	memmove(canary0, hctx + 1, sizeof(canary0));
328	memset(hctx, 0, sizeof(isc_hash_t));
329	memmove(canary1, hctx + 1, sizeof(canary1));
330	INSIST(memcmp(canary0, canary1, sizeof(canary0)) == 0);
331	isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
332	isc_mem_detach(&mctx);
333}
334
335void
336isc_hash_ctxdetach(isc_hash_t **hctxp) {
337	isc_hash_t *hctx;
338	unsigned int refs;
339
340	REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
341	hctx = *hctxp;
342
343	isc_refcount_decrement(&hctx->refcnt, &refs);
344	if (refs == 0)
345		destroy(&hctx);
346
347	*hctxp = NULL;
348}
349
350void
351isc_hash_destroy() {
352	unsigned int refs;
353
354	INSIST(hash != NULL && VALID_HASH(hash));
355
356	isc_refcount_decrement(&hash->refcnt, &refs);
357	INSIST(refs == 0);
358
359	destroy(&hash);
360}
361
362static inline unsigned int
363hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
364	  isc_boolean_t case_sensitive)
365{
366	hash_accum_t partial_sum = 0;
367	hash_random_t *p = hctx->rndvector;
368	unsigned int i = 0;
369
370	/* Make it sure that the hash context is initialized. */
371	if (hctx->initialized == ISC_FALSE)
372		isc_hash_ctxinit(hctx);
373
374	if (case_sensitive) {
375		for (i = 0; i < keylen; i++)
376			partial_sum += key[i] * (hash_accum_t)p[i];
377	} else {
378		for (i = 0; i < keylen; i++)
379			partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
380	}
381
382	partial_sum += p[i];
383
384	return ((unsigned int)(partial_sum % PRIME32));
385}
386
387unsigned int
388isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
389		 unsigned int keylen, isc_boolean_t case_sensitive)
390{
391	REQUIRE(hctx != NULL && VALID_HASH(hctx));
392	REQUIRE(keylen <= hctx->limit);
393
394	return (hash_calc(hctx, key, keylen, case_sensitive));
395}
396
397unsigned int
398isc_hash_calc(const unsigned char *key, unsigned int keylen,
399	      isc_boolean_t case_sensitive)
400{
401	INSIST(hash != NULL && VALID_HASH(hash));
402	REQUIRE(keylen <= hash->limit);
403
404	return (hash_calc(hash, key, keylen, case_sensitive));
405}
406