1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
|
/*
This file is part of GNUnet
Copyright (C) 2012 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published
by the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
*/
/**
* @file set/ibf.c
* @brief implementation of the invertible bloom filter
* @author Florian Dold
*/
#include "ibf.h"
/**
* Compute the key's hash from the key.
* Redefine to use a different hash function.
*/
#define IBF_KEY_HASH_VAL(k) (GNUNET_CRYPTO_crc32_n (&(k), sizeof (struct IBF_KeyHash)))
/**
* Create a key from a hashcode.
*
* @param hash the hashcode
* @return a key
*/
struct IBF_Key
ibf_key_from_hashcode (const struct GNUNET_HashCode *hash)
{
return *(struct IBF_Key *) hash;
}
/**
* Create a hashcode from a key, by replicating the key
* until the hascode is filled
*
* @param key the key
* @param dst hashcode to store the result in
*/
void
ibf_hashcode_from_key (struct IBF_Key key,
struct GNUNET_HashCode *dst)
{
struct IBF_Key *p;
unsigned int i;
const unsigned int keys_per_hashcode = sizeof (struct GNUNET_HashCode) / sizeof (struct IBF_Key);
p = (struct IBF_Key *) dst;
for (i = 0; i < keys_per_hashcode; i++)
*p++ = key;
}
/**
* Create an invertible bloom filter.
*
* @param size number of IBF buckets
* @param hash_num number of buckets one element is hashed in
* @return the newly created invertible bloom filter, NULL on error
*/
struct InvertibleBloomFilter *
ibf_create (uint32_t size, uint8_t hash_num)
{
struct InvertibleBloomFilter *ibf;
GNUNET_assert (0 != size);
ibf = GNUNET_new (struct InvertibleBloomFilter);
ibf->count = GNUNET_malloc_large (size * sizeof (uint8_t));
if (NULL == ibf->count)
{
GNUNET_free (ibf);
return NULL;
}
ibf->key_sum = GNUNET_malloc_large (size * sizeof (struct IBF_Key));
if (NULL == ibf->key_sum)
{
GNUNET_free (ibf->count);
GNUNET_free (ibf);
return NULL;
}
ibf->key_hash_sum = GNUNET_malloc_large (size * sizeof (struct IBF_KeyHash));
if (NULL == ibf->key_hash_sum)
{
GNUNET_free (ibf->key_sum);
GNUNET_free (ibf->count);
GNUNET_free (ibf);
return NULL;
}
ibf->size = size;
ibf->hash_num = hash_num;
return ibf;
}
/**
* Store unique bucket indices for the specified key in dst.
*/
static void
ibf_get_indices (const struct InvertibleBloomFilter *ibf,
struct IBF_Key key,
int *dst)
{
uint32_t filled;
uint32_t i;
uint32_t bucket;
bucket = GNUNET_CRYPTO_crc32_n (&key, sizeof key);
for (i = 0, filled=0; filled < ibf->hash_num; i++)
{
unsigned int j;
uint64_t x;
for (j = 0; j < filled; j++)
if (dst[j] == bucket)
goto try_next;
dst[filled++] = bucket % ibf->size;
try_next: ;
x = ((uint64_t) bucket << 32) | i;
bucket = GNUNET_CRYPTO_crc32_n (&x, sizeof x);
}
}
static void
ibf_insert_into (struct InvertibleBloomFilter *ibf,
struct IBF_Key key,
const int *buckets, int side)
{
int i;
for (i = 0; i < ibf->hash_num; i++)
{
const int bucket = buckets[i];
ibf->count[bucket].count_val += side;
ibf->key_sum[bucket].key_val ^= key.key_val;
ibf->key_hash_sum[bucket].key_hash_val
^= IBF_KEY_HASH_VAL (key);
}
}
/**
* Insert a key into an IBF.
*
* @param ibf the IBF
* @param key the element's hash code
*/
void
ibf_insert (struct InvertibleBloomFilter *ibf, struct IBF_Key key)
{
int buckets[ibf->hash_num];
GNUNET_assert (ibf->hash_num <= ibf->size);
ibf_get_indices (ibf, key, buckets);
ibf_insert_into (ibf, key, buckets, 1);
}
/**
* Remove a key from an IBF.
*
* @param ibf the IBF
* @param key the element's hash code
*/
void
ibf_remove (struct InvertibleBloomFilter *ibf, struct IBF_Key key)
{
int buckets[ibf->hash_num];
GNUNET_assert (ibf->hash_num <= ibf->size);
ibf_get_indices (ibf, key, buckets);
ibf_insert_into (ibf, key, buckets, -1);
}
/**
* Test is the IBF is empty, i.e. all counts, keys and key hashes are zero.
*/
static int
ibf_is_empty (struct InvertibleBloomFilter *ibf)
{
int i;
for (i = 0; i < ibf->size; i++)
{
if (0 != ibf->count[i].count_val)
return GNUNET_NO;
if (0 != ibf->key_hash_sum[i].key_hash_val)
return GNUNET_NO;
if (0 != ibf->key_sum[i].key_val)
return GNUNET_NO;
}
return GNUNET_YES;
}
/**
* Decode and remove an element from the IBF, if possible.
*
* @param ibf the invertible bloom filter to decode
* @param ret_side sign of the cell's count where the decoded element came from.
* A negative sign indicates that the element was recovered
* resides in an IBF that was previously subtracted from.
* @param ret_id receives the hash code of the decoded element, if successful
* @return GNUNET_YES if decoding an element was successful,
* GNUNET_NO if the IBF is empty,
* GNUNET_SYSERR if the decoding has failed
*/
int
ibf_decode (struct InvertibleBloomFilter *ibf,
int *ret_side, struct IBF_Key *ret_id)
{
struct IBF_KeyHash hash;
int i;
int buckets[ibf->hash_num];
GNUNET_assert (NULL != ibf);
for (i = 0; i < ibf->size; i++)
{
int j;
int hit;
/* we can only decode from pure buckets */
if ((1 != ibf->count[i].count_val) && (-1 != ibf->count[i].count_val))
continue;
hash.key_hash_val = IBF_KEY_HASH_VAL (ibf->key_sum[i]);
/* test if the hash matches the key */
if (hash.key_hash_val != ibf->key_hash_sum[i].key_hash_val)
continue;
/* test if key in bucket hits its own location,
* if not, the key hash was subject to collision */
hit = GNUNET_NO;
ibf_get_indices (ibf, ibf->key_sum[i], buckets);
for (j = 0; j < ibf->hash_num; j++)
if (buckets[j] == i)
hit = GNUNET_YES;
if (GNUNET_NO == hit)
continue;
if (NULL != ret_side)
*ret_side = ibf->count[i].count_val;
if (NULL != ret_id)
*ret_id = ibf->key_sum[i];
/* insert on the opposite side, effectively removing the element */
ibf_insert_into (ibf, ibf->key_sum[i], buckets, -ibf->count[i].count_val);
return GNUNET_YES;
}
if (GNUNET_YES == ibf_is_empty (ibf))
return GNUNET_NO;
return GNUNET_SYSERR;
}
/**
* Write buckets from an ibf to a buffer.
* Exactly (IBF_BUCKET_SIZE*ibf->size) bytes are written to buf.
*
* @param ibf the ibf to write
* @param start with which bucket to start
* @param count how many buckets to write
* @param buf buffer to write the data to
*/
void
ibf_write_slice (const struct InvertibleBloomFilter *ibf, uint32_t start, uint32_t count, void *buf)
{
struct IBF_Key *key_dst;
struct IBF_KeyHash *key_hash_dst;
struct IBF_Count *count_dst;
GNUNET_assert (start + count <= ibf->size);
/* copy keys */
key_dst = (struct IBF_Key *) buf;
GNUNET_memcpy (key_dst, ibf->key_sum + start, count * sizeof *key_dst);
key_dst += count;
/* copy key hashes */
key_hash_dst = (struct IBF_KeyHash *) key_dst;
GNUNET_memcpy (key_hash_dst, ibf->key_hash_sum + start, count * sizeof *key_hash_dst);
key_hash_dst += count;
/* copy counts */
count_dst = (struct IBF_Count *) key_hash_dst;
GNUNET_memcpy (count_dst, ibf->count + start, count * sizeof *count_dst);
}
/**
* Read buckets from a buffer into an ibf.
*
* @param buf pointer to the buffer to read from
* @param start which bucket to start at
* @param count how many buckets to read
* @param ibf the ibf to read from
*/
void
ibf_read_slice (const void *buf, uint32_t start, uint32_t count, struct InvertibleBloomFilter *ibf)
{
struct IBF_Key *key_src;
struct IBF_KeyHash *key_hash_src;
struct IBF_Count *count_src;
GNUNET_assert (count > 0);
GNUNET_assert (start + count <= ibf->size);
/* copy keys */
key_src = (struct IBF_Key *) buf;
GNUNET_memcpy (ibf->key_sum + start, key_src, count * sizeof *key_src);
key_src += count;
/* copy key hashes */
key_hash_src = (struct IBF_KeyHash *) key_src;
GNUNET_memcpy (ibf->key_hash_sum + start, key_hash_src, count * sizeof *key_hash_src);
key_hash_src += count;
/* copy counts */
count_src = (struct IBF_Count *) key_hash_src;
GNUNET_memcpy (ibf->count + start, count_src, count * sizeof *count_src);
}
/**
* Subtract ibf2 from ibf1, storing the result in ibf1.
* The two IBF's must have the same parameters size and hash_num.
*
* @param ibf1 IBF that is subtracted from
* @param ibf2 IBF that will be subtracted from ibf1
*/
void
ibf_subtract (struct InvertibleBloomFilter *ibf1, const struct InvertibleBloomFilter *ibf2)
{
int i;
GNUNET_assert (ibf1->size == ibf2->size);
GNUNET_assert (ibf1->hash_num == ibf2->hash_num);
for (i = 0; i < ibf1->size; i++)
{
ibf1->count[i].count_val -= ibf2->count[i].count_val;
ibf1->key_hash_sum[i].key_hash_val ^= ibf2->key_hash_sum[i].key_hash_val;
ibf1->key_sum[i].key_val ^= ibf2->key_sum[i].key_val;
}
}
/**
* Create a copy of an IBF, the copy has to be destroyed properly.
*
* @param ibf the IBF to copy
*/
struct InvertibleBloomFilter *
ibf_dup (const struct InvertibleBloomFilter *ibf)
{
struct InvertibleBloomFilter *copy;
copy = GNUNET_malloc (sizeof *copy);
copy->hash_num = ibf->hash_num;
copy->size = ibf->size;
copy->key_hash_sum = GNUNET_memdup (ibf->key_hash_sum, ibf->size * sizeof (struct IBF_KeyHash));
copy->key_sum = GNUNET_memdup (ibf->key_sum, ibf->size * sizeof (struct IBF_Key));
copy->count = GNUNET_memdup (ibf->count, ibf->size * sizeof (struct IBF_Count));
return copy;
}
/**
* Destroy all resources associated with the invertible bloom filter.
* No more ibf_*-functions may be called on ibf after calling destroy.
*
* @param ibf the intertible bloom filter to destroy
*/
void
ibf_destroy (struct InvertibleBloomFilter *ibf)
{
GNUNET_free (ibf->key_sum);
GNUNET_free (ibf->key_hash_sum);
GNUNET_free (ibf->count);
GNUNET_free (ibf);
}
|