1 files changed, 409 insertions, 0 deletions

diff --git a/src/setu/ibf.c b/src/setu/ibf.c
new file mode 100644
index 000000000..1532afceb
--- /dev/null
+++ b/src/setu/ibf.c
@@ -0,0 +1,409 @@
+/*
+      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;
+  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);
+}