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- /*
- 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 Affero 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.
- You should have received a copy of the GNU Affero General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
- SPDX-License-Identifier: AGPL3.0-or-later
- */
- /**
- * @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;
- const unsigned int keys_per_hashcode = sizeof(struct GNUNET_HashCode)
- / sizeof(struct IBF_Key);
- p = (struct IBF_Key *) dst;
- for (unsigned int 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 @a key in @a 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++)
- {
- uint64_t x;
- for (unsigned int j = 0; j < filled; j++)
- if (dst[j] == bucket % ibf->size)
- 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)
- {
- for (unsigned int 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)
- {
- for (uint32_t 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 buckets[ibf->hash_num];
- for (uint32_t i = 0; i < ibf->size; i++)
- {
- /* 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 */
- {
- bool hit = false;
- ibf_get_indices (ibf,
- ibf->key_sum[i],
- buckets);
- for (int j = 0; j < ibf->hash_num; j++)
- if (buckets[j] == i)
- {
- hit = true;
- break;
- }
- if (! 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)
- {
- GNUNET_assert (ibf1->size == ibf2->size);
- GNUNET_assert (ibf1->hash_num == ibf2->hash_num);
- for (uint32_t 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);
- }
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