Add an address-set backend using a bloom filter.

  }

}

/** As tor_addr_hash, but use a particular siphash key. */

uint64_t

tor_addr_keyed_hash(const struct sipkey *key, const tor_addr_t *addr)

{

  /* This is duplicate code with tor_addr_hash, since this function needs to

   * be backportable all the way to 0.2.9. */

  switch (tor_addr_family(addr)) {

  case AF_INET:

    return siphash24(&addr->addr.in_addr.s_addr, 4, key);

  case AF_UNSPEC:

    return 0x4e4d5342;

  case AF_INET6:

    return siphash24(&addr->addr.in6_addr.s6_addr, 16, key);

  default:

    /* LCOV_EXCL_START */

    tor_fragile_assert();

    return 0;

    /* LCOV_EXCL_END */

  }

}

/** Return a newly allocated string with a representation of <b>addr</b>. */

char *

tor_addr_to_str_dup(const tor_addr_t *addr)

#define tor_addr_eq(a,b) (0==tor_addr_compare((a),(b),CMP_EXACT))

uint64_t tor_addr_hash(const tor_addr_t *addr);

struct sipkey;

uint64_t tor_addr_keyed_hash(const struct sipkey *key, const tor_addr_t *addr);

int tor_addr_is_v4(const tor_addr_t *addr);

int tor_addr_is_internal_(const tor_addr_t *ip, int for_listening,

                          const char *filename, int lineno);

/* Copyright (c) 2018, The Tor Project, Inc. */

/* See LICENSE for licensing information */

/**

 * \file address_set.c

 * \brief Implementation for a set of addresses.

 *

 * This module was first written on a semi-emergency basis to improve the

 * robustness of the anti-DoS module.  As such, it's written in a pretty

 * conservative way, and should be susceptible to improvement later on.

 **/

#include "orconfig.h"

#include "address_set.h"

#include "address.h"

#include "compat.h"

#include "container.h"

#include "crypto.h"

#include "util.h"

#include "siphash.h"

/** How many 64-bit siphash values to extract per address */

#define N_HASHES 2

/** How many bloom-filter bits we set per address. This is twice the N_HASHES

 * value, since we split the siphash outcome two 32-bit values. */

#define N_BITS_PER_ITEM (N_HASHES * 2)

/* XXXX This code is largely duplicated with digestset_t.  We should merge

 * them together into a common bloom-filter implementation.  I'm keeping

 * them separate for now, though, since this module needs to be backported

 * all the way to 0.2.9.

 *

 * The main difference between digestset_t and this code is that we use

 * independent siphashes rather than messing around with bit-shifts.  The

 * approach here is probably more sound, and we should prefer it if&when we

 * unify the implementations.

 **/

struct address_set_t {

  /** siphash keys to make N_HASHES independent hashes for each address. */

  struct sipkey key[N_HASHES];

  int mask; /**< One less than the number of bits in <b>ba</b>; always one less

             * than a power of two. */

  bitarray_t *ba; /**< A bit array to implement the Bloom filter. */

};

/**

 * Allocate and return an address_set, suitable for holding up to

 * <b>max_address_guess</b> distinct values.

 */

address_set_t *

address_set_new(int max_addresses_guess)

{

  /* See digestset_new() for rationale on this equation. */

  int n_bits = 1u << (tor_log2(max_addresses_guess)+5);

  address_set_t *set = tor_malloc_zero(sizeof(address_set_t));

  set->mask = n_bits - 1;

  set->ba = bitarray_init_zero(n_bits);

  crypto_rand((char*) set->key, sizeof(set->key));

  return set;

}

/**

 * Release all storage associated with <b>set</b>

 */

void

address_set_free(address_set_t *set)

{

  if (! set)

    return;

  bitarray_free(set->ba);

  tor_free(set);

}

/** Yield the bit index corresponding to 'val' for set. */

#define BIT(set, val) ((val) & (set)->mask)

/**

 * Add <b>addr</b> to <b>set</b>.

 *

 * All future queries for <b>addr</b> in set will return true. Removing

 * items is not possible.

 */

void

address_set_add(address_set_t *set, const struct tor_addr_t *addr)

{

  int i;

  for (i = 0; i < N_HASHES; ++i) {

    uint64_t h = tor_addr_keyed_hash(&set->key[i], addr);

    uint32_t high_bits = (uint32_t)(h >> 32);

    uint32_t low_bits = (uint32_t)(h);

    bitarray_set(set->ba, BIT(set, high_bits));

    bitarray_set(set->ba, BIT(set, low_bits));

  }

}

/**

 * Return true if <b>addr</b> if a member of <b>set</b>.  (And probably,

 * return false if <b>addr</b> is not a member of set.)

 */

int

address_set_probably_contains(address_set_t *set,

                              const struct tor_addr_t *addr)

{

  int i, matches = 0;

  for (i = 0; i < N_HASHES; ++i) {

    uint64_t h = tor_addr_keyed_hash(&set->key[i], addr);

    uint32_t high_bits = (uint32_t)(h >> 32);

    uint32_t low_bits = (uint32_t)(h);

    // Note that !! is necessary here, since bitarray_is_set does not

    // necessarily return 1 on true.

    matches += !! bitarray_is_set(set->ba, BIT(set, high_bits));

    matches += !! bitarray_is_set(set->ba, BIT(set, low_bits));

  }

  return matches == N_BITS_PER_ITEM;

}

/* Copyright (c) 2018, The Tor Project, Inc. */

/* See LICENSE for licensing information */

/**

 * \file addressset.h

 * \brief Types to handle sets of addresses.

 *

 * This module was first written on a semi-emergency basis to improve the

 * robustness of the anti-DoS module.  As such, it's written in a pretty

 * conservative way, and should be susceptible to improvement later on.

 **/

#ifndef TOR_ADDRESS_SET_H

#define TOR_ADDRESS_SET_H

#include "orconfig.h"

/**

 * An address_set_t represents a set of tor_addr_t values. The implementation

 * is probabilistic: false negatives cannot occur but false positives are

 * possible.

 */

typedef struct address_set_t address_set_t;

struct tor_addr_t;

address_set_t *address_set_new(int max_addresses_guess);

void address_set_free(address_set_t *set);

void address_set_add(address_set_t *set, const struct tor_addr_t *addr);

int address_set_probably_contains(address_set_t *set,

                                  const struct tor_addr_t *addr);

#endif

LIBOR_A_SRC = \

  src/common/address.c					\

  src/common/address_set.c				\

  src/common/backtrace.c				\

  src/common/compat.c					\

  src/common/compat_threads.c				\

COMMONHEADERS = \

  src/common/address.h				\

  src/common/address_set.h			\

  src/common/backtrace.h			\

  src/common/aes.h				\

  src/common/ciphers.inc			\