crypto: replace rand<T>()%N idiom with unbiased rand_idx(N)

This commit is contained in:
stoffu 2019-04-03 14:10:24 +09:00
parent b6726aaa6c
commit a2195b9b7f
No known key found for this signature in database
GPG Key ID: 41DAB8343A9EC012
5 changed files with 36 additions and 12 deletions

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@ -33,7 +33,7 @@
#include <stdlib.h>
#include "include_base_utils.h"
#include "common/threadpool.h"
#include <random>
#include "crypto/crypto.h"
#include <boost/thread/mutex.hpp>
#include <boost/algorithm/string/join.hpp>
#include <boost/optional.hpp>
@ -517,10 +517,7 @@ bool load_txt_records_from_dns(std::vector<std::string> &good_records, const std
std::vector<std::vector<std::string> > records;
records.resize(dns_urls.size());
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<int> dis(0, dns_urls.size() - 1);
size_t first_index = dis(gen);
size_t first_index = crypto::rand_idx(dns_urls.size());
// send all requests in parallel
std::deque<bool> avail(dns_urls.size(), false), valid(dns_urls.size(), false);

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@ -35,6 +35,7 @@
#include <boost/optional.hpp>
#include <type_traits>
#include <vector>
#include <random>
#include "common/pod-class.h"
#include "memwipe.h"
@ -162,6 +163,32 @@ namespace crypto {
return res;
}
/* UniformRandomBitGenerator using crypto::rand<uint64_t>()
*/
struct random_device
{
typedef uint64_t result_type;
static constexpr result_type min() { return 0; }
static constexpr result_type max() { return result_type(-1); }
result_type operator()() const { return crypto::rand<result_type>(); }
};
/* Generate a random value between range_min and range_max
*/
template<typename T>
typename std::enable_if<std::is_integral<T>::value, T>::type rand_range(T range_min, T range_max) {
crypto::random_device rd;
std::uniform_int_distribution<T> dis(range_min, range_max);
return dis(rd);
}
/* Generate a random index between 0 and sz-1
*/
template<typename T>
typename std::enable_if<std::is_unsigned<T>::value, T>::type rand_idx(T sz) {
return crypto::rand_range<T>(0, sz-1);
}
/* Generate a new key pair
*/
inline secret_key generate_keys(public_key &pub, secret_key &sec, const secret_key& recovery_key = secret_key(), bool recover = false) {

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@ -1259,7 +1259,7 @@ namespace nodetool
}
}
else
random_index = crypto::rand<size_t>() % filtered.size();
random_index = crypto::rand_idx(filtered.size());
CHECK_AND_ASSERT_MES(random_index < filtered.size(), false, "random_index < filtered.size() failed!!");
random_index = filtered[random_index];
@ -1313,7 +1313,7 @@ namespace nodetool
return true;
size_t try_count = 0;
size_t current_index = crypto::rand<size_t>()%m_seed_nodes.size();
size_t current_index = crypto::rand_idx(m_seed_nodes.size());
const net_server& server = m_network_zones.at(epee::net_utils::zone::public_).m_net_server;
while(true)
{

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@ -398,7 +398,7 @@ namespace nodetool
return false;
}
size_t random_index = crypto::rand<size_t>() % m_peers_gray.size();
size_t random_index = crypto::rand_idx(m_peers_gray.size());
peers_indexed::index<by_time>::type& by_time_index = m_peers_gray.get<by_time>();
pe = *epee::misc_utils::move_it_backward(--by_time_index.end(), random_index);

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@ -5719,7 +5719,7 @@ namespace
{
CHECK_AND_ASSERT_MES(!vec.empty(), T(), "Vector must be non-empty");
size_t idx = crypto::rand<size_t>() % vec.size();
size_t idx = crypto::rand_idx(vec.size());
return pop_index (vec, idx);
}
@ -5822,7 +5822,7 @@ size_t wallet2::pop_best_value_from(const transfer_container &transfers, std::ve
}
else
{
idx = crypto::rand<size_t>() % candidates.size();
idx = crypto::rand_idx(candidates.size());
}
return pop_index (unused_indices, candidates[idx]);
}
@ -7474,7 +7474,7 @@ void wallet2::get_outs(std::vector<std::vector<tools::wallet2::get_outs_entry>>
if (n_rct == 0)
return rct_offsets[block_offset] ? rct_offsets[block_offset] - 1 : 0;
MDEBUG("Picking 1/" << n_rct << " in " << (last_block_offset - first_block_offset + 1) << " blocks centered around " << block_offset + rct_start_height);
return first_rct + crypto::rand<uint64_t>() % n_rct;
return first_rct + crypto::rand_idx(n_rct);
};
size_t num_selected_transfers = 0;
@ -9603,7 +9603,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_all(uint64_t below
if (unused_transfer_dust_indices_per_subaddr.count(0) == 1 && unused_transfer_dust_indices_per_subaddr.size() > 1)
unused_transfer_dust_indices_per_subaddr.erase(0);
auto i = unused_transfer_dust_indices_per_subaddr.begin();
std::advance(i, crypto::rand<size_t>() % unused_transfer_dust_indices_per_subaddr.size());
std::advance(i, crypto::rand_idx(unused_transfer_dust_indices_per_subaddr.size()));
unused_transfers_indices = i->second.first;
unused_dust_indices = i->second.second;
LOG_PRINT_L2("Spending from subaddress index " << i->first);