/contrib/bind9/lib/isc/hash.c

  1/*
  2 * Copyright (C) 2004-2007, 2009  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	unsigned int	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		   unsigned int 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, hctx->vectorlen,
254					     NULL, 0);
255		INSIST(result == ISC_R_SUCCESS);
256#else
257		INSIST(0);
258#endif
259	} else {
260		isc_uint32_t pr;
261		unsigned int i, copylen;
262		unsigned char *p;
263
264		p = (unsigned char *)hctx->rndvector;
265		for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
266			isc_random_get(&pr);
267			if (i + sizeof(pr) <= hctx->vectorlen)
268				copylen = sizeof(pr);
269			else
270				copylen = hctx->vectorlen - i;
271
272			memcpy(p, &pr, copylen);
273		}
274		INSIST(p == (unsigned char *)hctx->rndvector +
275		       hctx->vectorlen);
276	}
277
278	hctx->initialized = ISC_TRUE;
279
280 out:
281	UNLOCK(&hctx->lock);
282}
283
284void
285isc_hash_init() {
286	INSIST(hash != NULL && VALID_HASH(hash));
287
288	isc_hash_ctxinit(hash);
289}
290
291void
292isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
293	REQUIRE(VALID_HASH(hctx));
294	REQUIRE(hctxp != NULL && *hctxp == NULL);
295
296	isc_refcount_increment(&hctx->refcnt, NULL);
297	*hctxp = hctx;
298}
299
300static void
301destroy(isc_hash_t **hctxp) {
302	isc_hash_t *hctx;
303	isc_mem_t *mctx;
304	unsigned char canary0[4], canary1[4];
305
306	REQUIRE(hctxp != NULL && *hctxp != NULL);
307	hctx = *hctxp;
308	*hctxp = NULL;
309
310	LOCK(&hctx->lock);
311
312	isc_refcount_destroy(&hctx->refcnt);
313
314	mctx = hctx->mctx;
315#ifdef BIND9
316	if (hctx->entropy != NULL)
317		isc_entropy_detach(&hctx->entropy);
318#endif
319	if (hctx->rndvector != NULL)
320		isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
321
322	UNLOCK(&hctx->lock);
323
324	DESTROYLOCK(&hctx->lock);
325
326	memcpy(canary0, hctx + 1, sizeof(canary0));
327	memset(hctx, 0, sizeof(isc_hash_t));
328	memcpy(canary1, hctx + 1, sizeof(canary1));
329	INSIST(memcmp(canary0, canary1, sizeof(canary0)) == 0);
330	isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
331	isc_mem_detach(&mctx);
332}
333
334void
335isc_hash_ctxdetach(isc_hash_t **hctxp) {
336	isc_hash_t *hctx;
337	unsigned int refs;
338
339	REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
340	hctx = *hctxp;
341
342	isc_refcount_decrement(&hctx->refcnt, &refs);
343	if (refs == 0)
344		destroy(&hctx);
345
346	*hctxp = NULL;
347}
348
349void
350isc_hash_destroy() {
351	unsigned int refs;
352
353	INSIST(hash != NULL && VALID_HASH(hash));
354
355	isc_refcount_decrement(&hash->refcnt, &refs);
356	INSIST(refs == 0);
357
358	destroy(&hash);
359}
360
361static inline unsigned int
362hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
363	  isc_boolean_t case_sensitive)
364{
365	hash_accum_t partial_sum = 0;
366	hash_random_t *p = hctx->rndvector;
367	unsigned int i = 0;
368
369	/* Make it sure that the hash context is initialized. */
370	if (hctx->initialized == ISC_FALSE)
371		isc_hash_ctxinit(hctx);
372
373	if (case_sensitive) {
374		for (i = 0; i < keylen; i++)
375			partial_sum += key[i] * (hash_accum_t)p[i];
376	} else {
377		for (i = 0; i < keylen; i++)
378			partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
379	}
380
381	partial_sum += p[i];
382
383	return ((unsigned int)(partial_sum % PRIME32));
384}
385
386unsigned int
387isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
388		 unsigned int keylen, isc_boolean_t case_sensitive)
389{
390	REQUIRE(hctx != NULL && VALID_HASH(hctx));
391	REQUIRE(keylen <= hctx->limit);
392
393	return (hash_calc(hctx, key, keylen, case_sensitive));
394}
395
396unsigned int
397isc_hash_calc(const unsigned char *key, unsigned int keylen,
398	      isc_boolean_t case_sensitive)
399{
400	INSIST(hash != NULL && VALID_HASH(hash));
401	REQUIRE(keylen <= hash->limit);
402
403	return (hash_calc(hash, key, keylen, case_sensitive));
404}