src/lib/crypt_ops/digestset.c

   1 /* Copyright (c) 2018-2021, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /**
   5  * \file digestset.c
   6  * \brief Implementation for a set of digests
   7  **/
   8
   9 #include "orconfig.h"
  10 #include "lib/container/bloomfilt.h"
  11 #include "lib/crypt_ops/crypto_rand.h"
  12 #include "lib/defs/digest_sizes.h"
  13 #include "lib/crypt_ops/digestset.h"
  14 #include "ext/siphash.h"
  15
  16 /* Wrap our hash function to have the signature that the bloom filter
  17  * needs. */
  18 static uint64_t
  19 bloomfilt_digest_hash(const struct sipkey *key,
  20                       const void *item)
  21 {
  22   return siphash24(item, DIGEST_LEN, key);
  23 }
  24
  25 /**
  26  * Allocate and return an digestset, suitable for holding up to
  27  * <b>max_guess</b> distinct values.
  28  */
  29 digestset_t *
  30 digestset_new(int max_guess)
  31 {
  32   uint8_t k[BLOOMFILT_KEY_LEN];
  33   crypto_rand((void*)k, sizeof(k));
  34   return bloomfilt_new(max_guess, bloomfilt_digest_hash, k);
  35 }
  36
  37 /**
  38  * Add <b>digest</b> to <b>set</b>.
  39  *
  40  * All future queries for <b>digest</b> in set will return true. Removing
  41  * items is not possible.
  42  */
  43 void
  44 digestset_add(digestset_t *set, const char *digest)
  45 {
  46   bloomfilt_add(set, digest);
  47 }
  48
  49 /**
  50  * Return true if <b>digest</b> is a member of <b>set</b>.  (And probably,
  51  * return false if <b>digest</b> is not a member of set.)
  52  */
  53 int
  54 digestset_probably_contains(const digestset_t *set,
  55                             const char *digest)
  56 {
  57   return bloomfilt_probably_contains(set, digest);
  58 }