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13 Affero General Public License for more details.
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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 IBF_KeyHash)))
36 * Create a key from a hashcode.
38 * @param hash the hashcode
42 ibf_key_from_hashcode(const struct GNUNET_HashCode *hash)
44 return *(struct IBF_Key *)hash;
48 * Create a hashcode from a key, by replicating the key
49 * until the hascode is filled
52 * @param dst hashcode to store the result in
55 ibf_hashcode_from_key(struct IBF_Key key,
56 struct GNUNET_HashCode *dst)
60 const unsigned int keys_per_hashcode = sizeof(struct GNUNET_HashCode) / sizeof(struct IBF_Key);
62 p = (struct IBF_Key *)dst;
63 for (i = 0; i < keys_per_hashcode; i++)
69 * Create an invertible bloom filter.
71 * @param size number of IBF buckets
72 * @param hash_num number of buckets one element is hashed in
73 * @return the newly created invertible bloom filter, NULL on error
75 struct InvertibleBloomFilter *
76 ibf_create(uint32_t size, uint8_t hash_num)
78 struct InvertibleBloomFilter *ibf;
80 GNUNET_assert(0 != size);
82 ibf = GNUNET_new(struct InvertibleBloomFilter);
83 ibf->count = GNUNET_malloc_large(size * sizeof(uint8_t));
84 if (NULL == ibf->count)
89 ibf->key_sum = GNUNET_malloc_large(size * sizeof(struct IBF_Key));
90 if (NULL == ibf->key_sum)
92 GNUNET_free(ibf->count);
96 ibf->key_hash_sum = GNUNET_malloc_large(size * sizeof(struct IBF_KeyHash));
97 if (NULL == ibf->key_hash_sum)
99 GNUNET_free(ibf->key_sum);
100 GNUNET_free(ibf->count);
105 ibf->hash_num = hash_num;
112 * Store unique bucket indices for the specified key in dst.
115 ibf_get_indices(const struct InvertibleBloomFilter *ibf,
123 bucket = GNUNET_CRYPTO_crc32_n(&key, sizeof key);
124 for (i = 0, filled = 0; filled < ibf->hash_num; i++)
128 for (j = 0; j < filled; j++)
129 if (dst[j] == bucket)
131 dst[filled++] = bucket % ibf->size;
133 x = ((uint64_t)bucket << 32) | i;
134 bucket = GNUNET_CRYPTO_crc32_n(&x, sizeof x);
140 ibf_insert_into(struct InvertibleBloomFilter *ibf,
142 const int *buckets, int side)
146 for (i = 0; i < ibf->hash_num; i++)
148 const int bucket = buckets[i];
149 ibf->count[bucket].count_val += side;
150 ibf->key_sum[bucket].key_val ^= key.key_val;
151 ibf->key_hash_sum[bucket].key_hash_val
152 ^= IBF_KEY_HASH_VAL(key);
158 * Insert a key into an IBF.
161 * @param key the element's hash code
164 ibf_insert(struct InvertibleBloomFilter *ibf, struct IBF_Key key)
166 int buckets[ibf->hash_num];
168 GNUNET_assert(ibf->hash_num <= ibf->size);
169 ibf_get_indices(ibf, key, buckets);
170 ibf_insert_into(ibf, key, buckets, 1);
175 * Remove a key from an IBF.
178 * @param key the element's hash code
181 ibf_remove(struct InvertibleBloomFilter *ibf, struct IBF_Key key)
183 int buckets[ibf->hash_num];
185 GNUNET_assert(ibf->hash_num <= ibf->size);
186 ibf_get_indices(ibf, key, buckets);
187 ibf_insert_into(ibf, key, buckets, -1);
192 * Test is the IBF is empty, i.e. all counts, keys and key hashes are zero.
195 ibf_is_empty(struct InvertibleBloomFilter *ibf)
199 for (i = 0; i < ibf->size; i++)
201 if (0 != ibf->count[i].count_val)
203 if (0 != ibf->key_hash_sum[i].key_hash_val)
205 if (0 != ibf->key_sum[i].key_val)
213 * Decode and remove an element from the IBF, if possible.
215 * @param ibf the invertible bloom filter to decode
216 * @param ret_side sign of the cell's count where the decoded element came from.
217 * A negative sign indicates that the element was recovered
218 * resides in an IBF that was previously subtracted from.
219 * @param ret_id receives the hash code of the decoded element, if successful
220 * @return GNUNET_YES if decoding an element was successful,
221 * GNUNET_NO if the IBF is empty,
222 * GNUNET_SYSERR if the decoding has failed
225 ibf_decode(struct InvertibleBloomFilter *ibf,
226 int *ret_side, struct IBF_Key *ret_id)
228 struct IBF_KeyHash hash;
230 int buckets[ibf->hash_num];
232 GNUNET_assert(NULL != ibf);
234 for (i = 0; i < ibf->size; i++)
239 /* we can only decode from pure buckets */
240 if ((1 != ibf->count[i].count_val) && (-1 != ibf->count[i].count_val))
243 hash.key_hash_val = IBF_KEY_HASH_VAL(ibf->key_sum[i]);
245 /* test if the hash matches the key */
246 if (hash.key_hash_val != ibf->key_hash_sum[i].key_hash_val)
249 /* test if key in bucket hits its own location,
250 * if not, the key hash was subject to collision */
252 ibf_get_indices(ibf, ibf->key_sum[i], buckets);
253 for (j = 0; j < ibf->hash_num; j++)
257 if (GNUNET_NO == hit)
260 if (NULL != ret_side)
261 *ret_side = ibf->count[i].count_val;
263 *ret_id = ibf->key_sum[i];
265 /* insert on the opposite side, effectively removing the element */
266 ibf_insert_into(ibf, ibf->key_sum[i], buckets, -ibf->count[i].count_val);
271 if (GNUNET_YES == ibf_is_empty(ibf))
273 return GNUNET_SYSERR;
278 * Write buckets from an ibf to a buffer.
279 * Exactly (IBF_BUCKET_SIZE*ibf->size) bytes are written to buf.
281 * @param ibf the ibf to write
282 * @param start with which bucket to start
283 * @param count how many buckets to write
284 * @param buf buffer to write the data to
287 ibf_write_slice(const struct InvertibleBloomFilter *ibf, uint32_t start, uint32_t count, void *buf)
289 struct IBF_Key *key_dst;
290 struct IBF_KeyHash *key_hash_dst;
291 struct IBF_Count *count_dst;
293 GNUNET_assert(start + count <= ibf->size);
296 key_dst = (struct IBF_Key *)buf;
297 GNUNET_memcpy(key_dst, ibf->key_sum + start, count * sizeof *key_dst);
299 /* copy key hashes */
300 key_hash_dst = (struct IBF_KeyHash *)key_dst;
301 GNUNET_memcpy(key_hash_dst, ibf->key_hash_sum + start, count * sizeof *key_hash_dst);
302 key_hash_dst += count;
304 count_dst = (struct IBF_Count *)key_hash_dst;
305 GNUNET_memcpy(count_dst, ibf->count + start, count * sizeof *count_dst);
310 * Read buckets from a buffer into an ibf.
312 * @param buf pointer to the buffer to read from
313 * @param start which bucket to start at
314 * @param count how many buckets to read
315 * @param ibf the ibf to read from
318 ibf_read_slice(const void *buf, uint32_t start, uint32_t count, struct InvertibleBloomFilter *ibf)
320 struct IBF_Key *key_src;
321 struct IBF_KeyHash *key_hash_src;
322 struct IBF_Count *count_src;
324 GNUNET_assert(count > 0);
325 GNUNET_assert(start + count <= ibf->size);
328 key_src = (struct IBF_Key *)buf;
329 GNUNET_memcpy(ibf->key_sum + start, key_src, count * sizeof *key_src);
331 /* copy key hashes */
332 key_hash_src = (struct IBF_KeyHash *)key_src;
333 GNUNET_memcpy(ibf->key_hash_sum + start, key_hash_src, count * sizeof *key_hash_src);
334 key_hash_src += count;
336 count_src = (struct IBF_Count *)key_hash_src;
337 GNUNET_memcpy(ibf->count + start, count_src, count * sizeof *count_src);
342 * Subtract ibf2 from ibf1, storing the result in ibf1.
343 * The two IBF's must have the same parameters size and hash_num.
345 * @param ibf1 IBF that is subtracted from
346 * @param ibf2 IBF that will be subtracted from ibf1
349 ibf_subtract(struct InvertibleBloomFilter *ibf1, const struct InvertibleBloomFilter *ibf2)
353 GNUNET_assert(ibf1->size == ibf2->size);
354 GNUNET_assert(ibf1->hash_num == ibf2->hash_num);
356 for (i = 0; i < ibf1->size; i++)
358 ibf1->count[i].count_val -= ibf2->count[i].count_val;
359 ibf1->key_hash_sum[i].key_hash_val ^= ibf2->key_hash_sum[i].key_hash_val;
360 ibf1->key_sum[i].key_val ^= ibf2->key_sum[i].key_val;
366 * Create a copy of an IBF, the copy has to be destroyed properly.
368 * @param ibf the IBF to copy
370 struct InvertibleBloomFilter *
371 ibf_dup(const struct InvertibleBloomFilter *ibf)
373 struct InvertibleBloomFilter *copy;
375 copy = GNUNET_malloc(sizeof *copy);
376 copy->hash_num = ibf->hash_num;
377 copy->size = ibf->size;
378 copy->key_hash_sum = GNUNET_memdup(ibf->key_hash_sum, ibf->size * sizeof(struct IBF_KeyHash));
379 copy->key_sum = GNUNET_memdup(ibf->key_sum, ibf->size * sizeof(struct IBF_Key));
380 copy->count = GNUNET_memdup(ibf->count, ibf->size * sizeof(struct IBF_Count));
386 * Destroy all resources associated with the invertible bloom filter.
387 * No more ibf_*-functions may be called on ibf after calling destroy.
389 * @param ibf the intertible bloom filter to destroy
392 ibf_destroy(struct InvertibleBloomFilter *ibf)
394 GNUNET_free(ibf->key_sum);
395 GNUNET_free(ibf->key_hash_sum);
396 GNUNET_free(ibf->count);