Refactor bloom filter logic not to be digest-specific.

Now the address-set code and the digest-set code share the same
backend.

Closes ticket 26510

1 files changed, 58 insertions, 0 deletions

diff --git a/src/lib/crypt_ops/digestset.c b/src/lib/crypt_ops/digestset.c
new file mode 100644
index 0000000000..89dd377a9c
--- /dev/null
+++ b/src/lib/crypt_ops/digestset.c
@@ -0,0 +1,58 @@
+/* Copyright (c) 2018-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file digestset.c
+ * \brief Implementation for a set of digests
+ **/
+
+#include "orconfig.h"
+#include "lib/container/bloomfilt.h"
+#include "lib/crypt_ops/crypto_rand.h"
+#include "lib/defs/digest_sizes.h"
+#include "lib/crypt_ops/digestset.h"
+#include "siphash.h"
+
+/* Wrap our hash function to have the signature that the bloom filter
+ * needs. */
+static uint64_t
+bloomfilt_digest_hash(const struct sipkey *key,
+                      const void *item)
+{
+  return siphash24(item, DIGEST_LEN, key);
+}
+
+/**
+ * Allocate and return an digestset, suitable for holding up to
+ * <b>max_guess</b> distinct values.
+ */
+digestset_t *
+digestset_new(int max_guess)
+{
+  uint8_t k[BLOOMFILT_KEY_LEN];
+  crypto_rand((void*)k, sizeof(k));
+  return bloomfilt_new(max_guess, bloomfilt_digest_hash, k);
+}
+
+/**
+ * Add <b>digest</b> to <b>set</b>.
+ *
+ * All future queries for <b>digest</b> in set will return true. Removing
+ * items is not possible.
+ */
+void
+digestset_add(digestset_t *set, const char *digest)
+{
+  bloomfilt_add(set, digest);
+}
+
+/**
+ * Return true if <b>digest</b> is a member of <b>set</b>.  (And probably,
+ * return false if <b>digest</b> is not a member of set.)
+ */
+int
+digestset_probably_contains(const digestset_t *set,
+                            const char *digest)
+{
+  return bloomfilt_probably_contains(set, digest);
+}