Annotation of embedaddon/ntp/lib/isc/hash.c, revision 1.1.1.1
1.1 misho 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 1.13.332.3 2009/05/07 23:47:12 tbox 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:
25: Copyright ((c)) 2002, Rice University
26: All rights reserved.
27:
28: Redistribution and use in source and binary forms, with or without
29: modification, are permitted provided that the following conditions are
30: met:
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:
45: This software is provided by RICE and the contributors on an "as is"
46: basis, without any representations or warranties of any kind, express
47: or implied including, but not limited to, representations or
48: warranties of non-infringement, merchantability or fitness for a
49: particular purpose. In no event shall RICE or contributors be liable
50: for any direct, indirect, incidental, special, exemplary, or
51: consequential damages (including, but not limited to, procurement of
52: substitute goods or services; loss of use, data, or profits; or
53: business interruption) however caused and on any theory of liability,
54: whether in contract, strict liability, or tort (including negligence
55: or otherwise) arising in any way out of the use of this software, even
56: if 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: */
85: typedef isc_uint32_t hash_accum_t;
86: typedef isc_uint16_t hash_random_t;
87: /*@}*/
88:
89: /*% isc hash structure */
90: struct 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:
102: static isc_mutex_t createlock;
103: static isc_once_t once = ISC_ONCE_INIT;
104: static isc_hash_t *hash = NULL;
105:
106: static 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:
141: isc_result_t
142: isc_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: if (entropy != NULL)
198: isc_entropy_attach(entropy, &hctx->entropy);
199:
200: *hctxp = hctx;
201: return (ISC_R_SUCCESS);
202:
203: cleanup_lock:
204: DESTROYLOCK(&hctx->lock);
205: errout:
206: isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
207: if (rv != NULL)
208: isc_mem_put(mctx, rv, vlen);
209:
210: return (result);
211: }
212:
213: static void
214: initialize_lock(void) {
215: RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
216: }
217:
218: isc_result_t
219: isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
220: isc_result_t result = ISC_R_SUCCESS;
221:
222: REQUIRE(mctx != NULL);
223: INSIST(hash == NULL);
224:
225: RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
226:
227: LOCK(&createlock);
228:
229: if (hash == NULL)
230: result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
231:
232: UNLOCK(&createlock);
233:
234: return (result);
235: }
236:
237: void
238: isc_hash_ctxinit(isc_hash_t *hctx) {
239: isc_result_t result;
240:
241: LOCK(&hctx->lock);
242:
243: if (hctx->initialized == ISC_TRUE)
244: goto out;
245:
246: if (hctx->entropy) {
247: result = isc_entropy_getdata(hctx->entropy,
248: hctx->rndvector, hctx->vectorlen,
249: NULL, 0);
250: INSIST(result == ISC_R_SUCCESS);
251: } else {
252: isc_uint32_t pr;
253: unsigned int i, copylen;
254: unsigned char *p;
255:
256: p = (unsigned char *)hctx->rndvector;
257: for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
258: isc_random_get(&pr);
259: if (i + sizeof(pr) <= hctx->vectorlen)
260: copylen = sizeof(pr);
261: else
262: copylen = hctx->vectorlen - i;
263:
264: memcpy(p, &pr, copylen);
265: }
266: INSIST(p == (unsigned char *)hctx->rndvector +
267: hctx->vectorlen);
268: }
269:
270: hctx->initialized = ISC_TRUE;
271:
272: out:
273: UNLOCK(&hctx->lock);
274: }
275:
276: void
277: isc_hash_init() {
278: INSIST(hash != NULL && VALID_HASH(hash));
279:
280: isc_hash_ctxinit(hash);
281: }
282:
283: void
284: isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
285: REQUIRE(VALID_HASH(hctx));
286: REQUIRE(hctxp != NULL && *hctxp == NULL);
287:
288: isc_refcount_increment(&hctx->refcnt, NULL);
289: *hctxp = hctx;
290: }
291:
292: static void
293: destroy(isc_hash_t **hctxp) {
294: isc_hash_t *hctx;
295: isc_mem_t *mctx;
296:
297: REQUIRE(hctxp != NULL && *hctxp != NULL);
298: hctx = *hctxp;
299: *hctxp = NULL;
300:
301: LOCK(&hctx->lock);
302:
303: isc_refcount_destroy(&hctx->refcnt);
304:
305: mctx = hctx->mctx;
306: if (hctx->entropy != NULL)
307: isc_entropy_detach(&hctx->entropy);
308: if (hctx->rndvector != NULL)
309: isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
310:
311: UNLOCK(&hctx->lock);
312:
313: DESTROYLOCK(&hctx->lock);
314:
315: memset(hctx, 0, sizeof(isc_hash_t));
316: isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
317: isc_mem_detach(&mctx);
318: }
319:
320: void
321: isc_hash_ctxdetach(isc_hash_t **hctxp) {
322: isc_hash_t *hctx;
323: unsigned int refs;
324:
325: REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
326: hctx = *hctxp;
327:
328: isc_refcount_decrement(&hctx->refcnt, &refs);
329: if (refs == 0)
330: destroy(&hctx);
331:
332: *hctxp = NULL;
333: }
334:
335: void
336: isc_hash_destroy() {
337: unsigned int refs;
338:
339: INSIST(hash != NULL && VALID_HASH(hash));
340:
341: isc_refcount_decrement(&hash->refcnt, &refs);
342: INSIST(refs == 0);
343:
344: destroy(&hash);
345: }
346:
347: static inline unsigned int
348: hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
349: isc_boolean_t case_sensitive)
350: {
351: hash_accum_t partial_sum = 0;
352: hash_random_t *p = hctx->rndvector;
353: unsigned int i = 0;
354:
355: /* Make it sure that the hash context is initialized. */
356: if (hctx->initialized == ISC_FALSE)
357: isc_hash_ctxinit(hctx);
358:
359: if (case_sensitive) {
360: for (i = 0; i < keylen; i++)
361: partial_sum += key[i] * (hash_accum_t)p[i];
362: } else {
363: for (i = 0; i < keylen; i++)
364: partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
365: }
366:
367: partial_sum += p[i];
368:
369: return ((unsigned int)(partial_sum % PRIME32));
370: }
371:
372: unsigned int
373: isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
374: unsigned int keylen, isc_boolean_t case_sensitive)
375: {
376: REQUIRE(hctx != NULL && VALID_HASH(hctx));
377: REQUIRE(keylen <= hctx->limit);
378:
379: return (hash_calc(hctx, key, keylen, case_sensitive));
380: }
381:
382: unsigned int
383: isc_hash_calc(const unsigned char *key, unsigned int keylen,
384: isc_boolean_t case_sensitive)
385: {
386: INSIST(hash != NULL && VALID_HASH(hash));
387: REQUIRE(keylen <= hash->limit);
388:
389: return (hash_calc(hash, key, keylen, case_sensitive));
390: }
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