2 This file is part of GNUnet
3 (C) 2012 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file consensus/ibf.c
23 * @brief implementation of the invertible bloom filter
24 * @author Florian Dold
30 * Create a key from a hashcode.
32 * @param hash the hashcode
36 ibf_key_from_hashcode (const struct GNUNET_HashCode *hash)
38 /* FIXME: endianess */
39 return *(struct IBF_Key *) hash;
43 * Create a hashcode from a key, by replicating the key
44 * until the hascode is filled
47 * @param dst hashcode to store the result in
50 ibf_hashcode_from_key (struct IBF_Key key, struct GNUNET_HashCode *dst)
54 const unsigned int keys_per_hashcode = sizeof (struct GNUNET_HashCode) / sizeof (struct IBF_Key);
55 p = (struct IBF_Key *) dst;
56 for (i = 0; i < keys_per_hashcode; i++)
62 * Create an invertible bloom filter.
64 * @param size number of IBF buckets
65 * @param hash_num number of buckets one element is hashed in
66 * @param salt salt for mingling hashes, different salt may
67 * result in less (or more) collisions
68 * @return the newly created invertible bloom filter
70 struct InvertibleBloomFilter *
71 ibf_create (uint32_t size, uint8_t hash_num, uint32_t salt)
73 struct InvertibleBloomFilter *ibf;
75 /* TODO: use malloc_large */
77 ibf = GNUNET_malloc (sizeof (struct InvertibleBloomFilter));
78 ibf->count = GNUNET_malloc (size * sizeof (uint8_t));
79 ibf->key_sum = GNUNET_malloc (size * sizeof (struct GNUNET_HashCode));
80 ibf->key_hash_sum = GNUNET_malloc (size * sizeof (struct GNUNET_HashCode));
82 ibf->hash_num = hash_num;
88 * Store unique bucket indices for the specified key in dst.
91 ibf_get_indices (const struct InvertibleBloomFilter *ibf,
92 struct IBF_Key key, int *dst)
94 struct GNUNET_HashCode bucket_indices;
97 GNUNET_CRYPTO_hash (&key, sizeof key, &bucket_indices);
99 for (i = 0; filled < ibf->hash_num; i++)
103 if ( (0 != i) && (0 == (i % 16)) )
104 GNUNET_CRYPTO_hash (&bucket_indices, sizeof (struct GNUNET_HashCode), &bucket_indices);
105 bucket = bucket_indices.bits[i % 16] % ibf->size;
106 for (j = 0; j < filled; j++)
107 if (dst[j] == bucket)
109 dst[filled++] = bucket;
116 ibf_insert_into (struct InvertibleBloomFilter *ibf,
118 const int *buckets, int side)
121 struct GNUNET_HashCode key_hash_sha;
122 struct IBF_KeyHash key_hash;
123 GNUNET_CRYPTO_hash (&key, sizeof key, &key_hash_sha);
124 key_hash.key_hash_val = key_hash_sha.bits[0];
125 for (i = 0; i < ibf->hash_num; i++)
127 const int bucket = buckets[i];
128 ibf->count[bucket].count_val += side;
129 ibf->key_sum[bucket].key_val ^= key.key_val;
130 ibf->key_hash_sum[bucket].key_hash_val ^= key_hash.key_hash_val;
136 * Insert an element into an IBF.
139 * @param key the element's hash code
142 ibf_insert (struct InvertibleBloomFilter *ibf, struct IBF_Key key)
144 int buckets[ibf->hash_num];
145 GNUNET_assert (ibf->hash_num <= ibf->size);
146 ibf_get_indices (ibf, key, buckets);
147 ibf_insert_into (ibf, key, buckets, 1);
151 * Test is the IBF is empty, i.e. all counts, keys and key hashes are zero.
154 ibf_is_empty (struct InvertibleBloomFilter *ibf)
157 for (i = 0; i < ibf->size; i++)
159 if (0 != ibf->count[i].count_val)
161 if (0 != ibf->key_hash_sum[i].key_hash_val)
163 if (0 != ibf->key_sum[i].key_val)
171 * Decode and remove an element from the IBF, if possible.
173 * @param ibf the invertible bloom filter to decode
174 * @param ret_side sign of the cell's count where the decoded element came from.
175 * A negative sign indicates that the element was recovered
176 * resides in an IBF that was previously subtracted from.
177 * @param ret_id receives the hash code of the decoded element, if successful
178 * @return GNUNET_YES if decoding an element was successful,
179 * GNUNET_NO if the IBF is empty,
180 * GNUNET_SYSERR if the decoding has failed
183 ibf_decode (struct InvertibleBloomFilter *ibf,
184 int *ret_side, struct IBF_Key *ret_id)
186 struct IBF_KeyHash hash;
188 struct GNUNET_HashCode key_hash_sha;
189 int buckets[ibf->hash_num];
191 GNUNET_assert (NULL != ibf);
193 for (i = 0; i < ibf->size; i++)
198 /* we can only decode from pure buckets */
199 if ((1 != ibf->count[i].count_val) && (-1 != ibf->count[i].count_val))
202 GNUNET_CRYPTO_hash (&ibf->key_sum[i], sizeof (struct IBF_Key), &key_hash_sha);
203 hash.key_hash_val = key_hash_sha.bits[0];
205 /* test if the hash matches the key */
206 if (hash.key_hash_val != ibf->key_hash_sum[i].key_hash_val)
209 /* test if key in bucket hits its own location,
210 * if not, the key hash was subject to collision */
212 ibf_get_indices (ibf, ibf->key_sum[i], buckets);
213 for (j = 0; j < ibf->hash_num; j++)
217 if (GNUNET_NO == hit)
220 if (NULL != ret_side)
221 *ret_side = ibf->count[i].count_val;
223 *ret_id = ibf->key_sum[i];
225 /* insert on the opposite side, effectively removing the element */
226 ibf_insert_into (ibf, ibf->key_sum[i], buckets, -ibf->count[i].count_val);
231 if (GNUNET_YES == ibf_is_empty (ibf))
233 return GNUNET_SYSERR;
240 * @param ibf the ibf to write
241 * @param start with which bucket to start
242 * @param count how many buckets to write
243 * @param buf buffer to write the data to, will be updated to point to the
244 * first byte after the written data
245 * @param size pointer to the size of the buffer, will be updated, can be NULL
248 ibf_write_slice (const struct InvertibleBloomFilter *ibf, uint32_t start, uint32_t count, void **buf, size_t *size)
250 struct IBF_Key *key_dst;
251 struct IBF_KeyHash *key_hash_dst;
252 struct IBF_Count *count_dst;
254 /* update size and check for overflow */
259 *size = *size - count * IBF_BUCKET_SIZE;
260 GNUNET_assert (*size < old_size);
263 key_dst = (struct IBF_Key *) *buf;
264 memcpy (key_dst, ibf->key_sum + start, count * sizeof *key_dst);
266 /* copy key hashes */
267 key_hash_dst = (struct IBF_KeyHash *) key_dst;
268 memcpy (key_hash_dst, ibf->key_hash_sum + start, count * sizeof *key_hash_dst);
269 key_hash_dst += count;
271 count_dst = (struct IBF_Count *) key_hash_dst;
272 memcpy (count_dst, ibf->count + start, count * sizeof *count_dst);
274 /* returned buffer is at the end of written data*/
275 *buf = (void *) count_dst;
282 * @param buf pointer to the buffer to write to, will point to first
283 * byte after the written data // FIXME: take 'const void *buf' for input, return number of bytes READ
284 * @param size size of the buffer, will be updated
285 * @param start which bucket to start at
286 * @param count how many buckets to read
287 * @param ibf the ibf to read from
288 * @return GNUNET_OK on success // FIXME: return 0 on error (or -1/ssize_t), number of bytes read otherwise
291 ibf_read_slice (void **buf, size_t *size, uint32_t start, uint32_t count, struct InvertibleBloomFilter *ibf)
293 struct IBF_Key *key_src;
294 struct IBF_KeyHash *key_hash_src;
295 struct IBF_Count *count_src;
297 /* update size and check for overflow */
302 *size = *size - count * IBF_BUCKET_SIZE;
303 if (*size > old_size)
304 return GNUNET_SYSERR;
307 key_src = (struct IBF_Key *) *buf;
308 memcpy (ibf->key_sum + start, key_src, count * sizeof *key_src);
310 /* copy key hashes */
311 key_hash_src = (struct IBF_KeyHash *) key_src;
312 memcpy (ibf->key_hash_sum + start, key_hash_src, count * sizeof *key_hash_src);
313 key_hash_src += count;
315 count_src = (struct IBF_Count *) key_hash_src;
316 memcpy (ibf->count + start, count_src, count * sizeof *count_src);
318 /* returned buffer is at the end of written data*/
319 *buf = (void *) count_src;
327 * @param ibf the ibf to write
328 * @param buf buffer to write the data to, will be updated to point to the
329 * first byte after the written data
330 * @param size pointer to the size of the buffer, will be updated, can be NULL
333 ibf_write (const struct InvertibleBloomFilter *ibf, void **buf, size_t *size)
335 ibf_write_slice (ibf, 0, ibf->size, buf, size);
342 * @param buf pointer to the buffer to write to, will point to first
343 * byte after the written data
344 * @param size size of the buffer, will be updated
345 * @param dst ibf to write buckets to
346 * @return GNUNET_OK on success
349 ibf_read (void **buf, size_t *size, struct InvertibleBloomFilter *dst)
351 return ibf_read_slice (buf, size, 0, dst->size, dst);
356 * Subtract ibf2 from ibf1, storing the result in ibf1.
357 * The two IBF's must have the same parameters size and hash_num.
359 * @param ibf1 IBF that is subtracted from
360 * @param ibf2 IBF that will be subtracted from ibf1
363 ibf_subtract (struct InvertibleBloomFilter *ibf1, const struct InvertibleBloomFilter *ibf2)
367 GNUNET_assert (ibf1->size == ibf2->size);
368 GNUNET_assert (ibf1->hash_num == ibf2->hash_num);
369 GNUNET_assert (ibf1->salt == ibf2->salt);
371 for (i = 0; i < ibf1->size; i++)
373 ibf1->count[i].count_val -= ibf2->count[i].count_val;
374 ibf1->key_hash_sum[i].key_hash_val ^= ibf2->key_hash_sum[i].key_hash_val;
375 ibf1->key_sum[i].key_val ^= ibf2->key_sum[i].key_val;
381 * Create a copy of an IBF, the copy has to be destroyed properly.
383 * @param ibf the IBF to copy
385 struct InvertibleBloomFilter *
386 ibf_dup (const struct InvertibleBloomFilter *ibf)
388 struct InvertibleBloomFilter *copy;
389 copy = GNUNET_malloc (sizeof *copy);
390 copy->hash_num = ibf->hash_num;
391 copy->salt = ibf->salt;
392 copy->size = ibf->size;
393 copy->key_hash_sum = GNUNET_memdup (ibf->key_hash_sum, ibf->size * sizeof (struct IBF_KeyHash));
394 copy->key_sum = GNUNET_memdup (ibf->key_sum, ibf->size * sizeof (struct IBF_Key));
395 copy->count = GNUNET_memdup (ibf->count, ibf->size * sizeof (struct IBF_Count));
401 * Destroy all resources associated with the invertible bloom filter.
402 * No more ibf_*-functions may be called on ibf after calling destroy.
404 * @param ibf the intertible bloom filter to destroy
407 ibf_destroy (struct InvertibleBloomFilter *ibf)
409 GNUNET_free (ibf->key_sum);
410 GNUNET_free (ibf->key_hash_sum);
411 GNUNET_free (ibf->count);