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13 Affero General Public License for more details.
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18 SPDX-License-Identifier: AGPL3.0-or-later
23 * @brief implementation of the invertible bloom filter
24 * @author Florian Dold
30 * Compute the key's hash from the key.
31 * Redefine to use a different hash function.
33 #define IBF_KEY_HASH_VAL(k) (GNUNET_CRYPTO_crc32_n (&(k), sizeof(struct \
37 * Create a key from a hashcode.
39 * @param hash the hashcode
43 ibf_key_from_hashcode (const struct GNUNET_HashCode *hash)
45 return *(struct IBF_Key *) hash;
50 * Create a hashcode from a key, by replicating the key
51 * until the hascode is filled
54 * @param dst hashcode to store the result in
57 ibf_hashcode_from_key (struct IBF_Key key,
58 struct GNUNET_HashCode *dst)
62 const unsigned int keys_per_hashcode = sizeof(struct GNUNET_HashCode)
63 / sizeof(struct IBF_Key);
65 p = (struct IBF_Key *) dst;
66 for (i = 0; i < keys_per_hashcode; i++)
72 * Create an invertible bloom filter.
74 * @param size number of IBF buckets
75 * @param hash_num number of buckets one element is hashed in
76 * @return the newly created invertible bloom filter, NULL on error
78 struct InvertibleBloomFilter *
79 ibf_create (uint32_t size, uint8_t hash_num)
81 struct InvertibleBloomFilter *ibf;
83 GNUNET_assert (0 != size);
85 ibf = GNUNET_new (struct InvertibleBloomFilter);
86 ibf->count = GNUNET_malloc_large (size * sizeof(uint8_t));
87 if (NULL == ibf->count)
92 ibf->key_sum = GNUNET_malloc_large (size * sizeof(struct IBF_Key));
93 if (NULL == ibf->key_sum)
95 GNUNET_free (ibf->count);
99 ibf->key_hash_sum = GNUNET_malloc_large (size * sizeof(struct IBF_KeyHash));
100 if (NULL == ibf->key_hash_sum)
102 GNUNET_free (ibf->key_sum);
103 GNUNET_free (ibf->count);
108 ibf->hash_num = hash_num;
115 * Store unique bucket indices for the specified key in dst.
118 ibf_get_indices (const struct InvertibleBloomFilter *ibf,
126 bucket = GNUNET_CRYPTO_crc32_n (&key, sizeof key);
127 for (i = 0, filled = 0; filled < ibf->hash_num; i++)
131 for (j = 0; j < filled; j++)
132 if (dst[j] == bucket)
134 dst[filled++] = bucket % ibf->size;
136 x = ((uint64_t) bucket << 32) | i;
137 bucket = GNUNET_CRYPTO_crc32_n (&x, sizeof x);
143 ibf_insert_into (struct InvertibleBloomFilter *ibf,
145 const int *buckets, int side)
149 for (i = 0; i < ibf->hash_num; i++)
151 const int bucket = buckets[i];
152 ibf->count[bucket].count_val += side;
153 ibf->key_sum[bucket].key_val ^= key.key_val;
154 ibf->key_hash_sum[bucket].key_hash_val
155 ^= IBF_KEY_HASH_VAL (key);
161 * Insert a key into an IBF.
164 * @param key the element's hash code
167 ibf_insert (struct InvertibleBloomFilter *ibf, struct IBF_Key key)
169 int buckets[ibf->hash_num];
171 GNUNET_assert (ibf->hash_num <= ibf->size);
172 ibf_get_indices (ibf, key, buckets);
173 ibf_insert_into (ibf, key, buckets, 1);
178 * Remove a key from an IBF.
181 * @param key the element's hash code
184 ibf_remove (struct InvertibleBloomFilter *ibf, struct IBF_Key key)
186 int buckets[ibf->hash_num];
188 GNUNET_assert (ibf->hash_num <= ibf->size);
189 ibf_get_indices (ibf, key, buckets);
190 ibf_insert_into (ibf, key, buckets, -1);
195 * Test is the IBF is empty, i.e. all counts, keys and key hashes are zero.
198 ibf_is_empty (struct InvertibleBloomFilter *ibf)
202 for (i = 0; i < ibf->size; i++)
204 if (0 != ibf->count[i].count_val)
206 if (0 != ibf->key_hash_sum[i].key_hash_val)
208 if (0 != ibf->key_sum[i].key_val)
216 * Decode and remove an element from the IBF, if possible.
218 * @param ibf the invertible bloom filter to decode
219 * @param ret_side sign of the cell's count where the decoded element came from.
220 * A negative sign indicates that the element was recovered
221 * resides in an IBF that was previously subtracted from.
222 * @param ret_id receives the hash code of the decoded element, if successful
223 * @return GNUNET_YES if decoding an element was successful,
224 * GNUNET_NO if the IBF is empty,
225 * GNUNET_SYSERR if the decoding has failed
228 ibf_decode (struct InvertibleBloomFilter *ibf,
229 int *ret_side, struct IBF_Key *ret_id)
231 struct IBF_KeyHash hash;
233 int buckets[ibf->hash_num];
235 GNUNET_assert (NULL != ibf);
237 for (i = 0; i < ibf->size; i++)
242 /* we can only decode from pure buckets */
243 if ((1 != ibf->count[i].count_val) && (-1 != ibf->count[i].count_val))
246 hash.key_hash_val = IBF_KEY_HASH_VAL (ibf->key_sum[i]);
248 /* test if the hash matches the key */
249 if (hash.key_hash_val != ibf->key_hash_sum[i].key_hash_val)
252 /* test if key in bucket hits its own location,
253 * if not, the key hash was subject to collision */
255 ibf_get_indices (ibf, ibf->key_sum[i], buckets);
256 for (j = 0; j < ibf->hash_num; j++)
260 if (GNUNET_NO == hit)
263 if (NULL != ret_side)
264 *ret_side = ibf->count[i].count_val;
266 *ret_id = ibf->key_sum[i];
268 /* insert on the opposite side, effectively removing the element */
269 ibf_insert_into (ibf, ibf->key_sum[i], buckets, -ibf->count[i].count_val);
274 if (GNUNET_YES == ibf_is_empty (ibf))
276 return GNUNET_SYSERR;
281 * Write buckets from an ibf to a buffer.
282 * Exactly (IBF_BUCKET_SIZE*ibf->size) bytes are written to buf.
284 * @param ibf the ibf to write
285 * @param start with which bucket to start
286 * @param count how many buckets to write
287 * @param buf buffer to write the data to
290 ibf_write_slice (const struct InvertibleBloomFilter *ibf, uint32_t start,
291 uint32_t count, void *buf)
293 struct IBF_Key *key_dst;
294 struct IBF_KeyHash *key_hash_dst;
295 struct IBF_Count *count_dst;
297 GNUNET_assert (start + count <= ibf->size);
300 key_dst = (struct IBF_Key *) buf;
301 GNUNET_memcpy (key_dst, ibf->key_sum + start, count * sizeof *key_dst);
303 /* copy key hashes */
304 key_hash_dst = (struct IBF_KeyHash *) key_dst;
305 GNUNET_memcpy (key_hash_dst, ibf->key_hash_sum + start, count
306 * sizeof *key_hash_dst);
307 key_hash_dst += count;
309 count_dst = (struct IBF_Count *) key_hash_dst;
310 GNUNET_memcpy (count_dst, ibf->count + start, count * sizeof *count_dst);
315 * Read buckets from a buffer into an ibf.
317 * @param buf pointer to the buffer to read from
318 * @param start which bucket to start at
319 * @param count how many buckets to read
320 * @param ibf the ibf to read from
323 ibf_read_slice (const void *buf, uint32_t start, uint32_t count, struct
324 InvertibleBloomFilter *ibf)
326 struct IBF_Key *key_src;
327 struct IBF_KeyHash *key_hash_src;
328 struct IBF_Count *count_src;
330 GNUNET_assert (count > 0);
331 GNUNET_assert (start + count <= ibf->size);
334 key_src = (struct IBF_Key *) buf;
335 GNUNET_memcpy (ibf->key_sum + start, key_src, count * sizeof *key_src);
337 /* copy key hashes */
338 key_hash_src = (struct IBF_KeyHash *) key_src;
339 GNUNET_memcpy (ibf->key_hash_sum + start, key_hash_src, count
340 * sizeof *key_hash_src);
341 key_hash_src += count;
343 count_src = (struct IBF_Count *) key_hash_src;
344 GNUNET_memcpy (ibf->count + start, count_src, count * sizeof *count_src);
349 * Subtract ibf2 from ibf1, storing the result in ibf1.
350 * The two IBF's must have the same parameters size and hash_num.
352 * @param ibf1 IBF that is subtracted from
353 * @param ibf2 IBF that will be subtracted from ibf1
356 ibf_subtract (struct InvertibleBloomFilter *ibf1, const struct
357 InvertibleBloomFilter *ibf2)
361 GNUNET_assert (ibf1->size == ibf2->size);
362 GNUNET_assert (ibf1->hash_num == ibf2->hash_num);
364 for (i = 0; i < ibf1->size; i++)
366 ibf1->count[i].count_val -= ibf2->count[i].count_val;
367 ibf1->key_hash_sum[i].key_hash_val ^= ibf2->key_hash_sum[i].key_hash_val;
368 ibf1->key_sum[i].key_val ^= ibf2->key_sum[i].key_val;
374 * Create a copy of an IBF, the copy has to be destroyed properly.
376 * @param ibf the IBF to copy
378 struct InvertibleBloomFilter *
379 ibf_dup (const struct InvertibleBloomFilter *ibf)
381 struct InvertibleBloomFilter *copy;
383 copy = GNUNET_malloc (sizeof *copy);
384 copy->hash_num = ibf->hash_num;
385 copy->size = ibf->size;
386 copy->key_hash_sum = GNUNET_memdup (ibf->key_hash_sum, ibf->size
387 * sizeof(struct IBF_KeyHash));
388 copy->key_sum = GNUNET_memdup (ibf->key_sum, ibf->size * sizeof(struct
390 copy->count = GNUNET_memdup (ibf->count, ibf->size * sizeof(struct
397 * Destroy all resources associated with the invertible bloom filter.
398 * No more ibf_*-functions may be called on ibf after calling destroy.
400 * @param ibf the intertible bloom filter to destroy
403 ibf_destroy (struct InvertibleBloomFilter *ibf)
405 GNUNET_free (ibf->key_sum);
406 GNUNET_free (ibf->key_hash_sum);
407 GNUNET_free (ibf->count);