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|
// Copyright (c) 2019-2020, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "levin_notify.h"
#include <boost/asio/steady_timer.hpp>
#include <boost/system/system_error.hpp>
#include <boost/uuid/uuid_io.hpp>
#include <chrono>
#include <deque>
#include <stdexcept>
#include <utility>
#include "byte_slice.h"
#include "common/expect.h"
#include "common/varint.h"
#include "cryptonote_config.h"
#include "crypto/crypto.h"
#include "crypto/duration.h"
#include "cryptonote_basic/connection_context.h"
#include "cryptonote_core/i_core_events.h"
#include "cryptonote_protocol/cryptonote_protocol_defs.h"
#include "net/dandelionpp.h"
#include "p2p/net_node.h"
#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "net.p2p.tx"
namespace cryptonote
{
namespace levin
{
namespace
{
constexpr const std::size_t connection_id_reserve_size = 100;
constexpr const std::chrono::minutes noise_min_epoch{CRYPTONOTE_NOISE_MIN_EPOCH};
constexpr const std::chrono::seconds noise_epoch_range{CRYPTONOTE_NOISE_EPOCH_RANGE};
constexpr const std::chrono::minutes dandelionpp_min_epoch{CRYPTONOTE_DANDELIONPP_MIN_EPOCH};
constexpr const std::chrono::seconds dandelionpp_epoch_range{CRYPTONOTE_DANDELIONPP_EPOCH_RANGE};
constexpr const std::chrono::seconds noise_min_delay{CRYPTONOTE_NOISE_MIN_DELAY};
constexpr const std::chrono::seconds noise_delay_range{CRYPTONOTE_NOISE_DELAY_RANGE};
/* A custom duration is used for the poisson distribution because of the
variance. If 5 seconds is given to `std::poisson_distribution`, 95% of
the values fall between 1-9s in 1s increments (not granular enough). If
5000 milliseconds is given, 95% of the values fall between 4859ms-5141ms
in 1ms increments (not enough time variance). Providing 20 quarter
seconds yields 95% of the values between 3s-7.25s in 1/4s increments. */
using fluff_stepsize = std::chrono::duration<std::chrono::milliseconds::rep, std::ratio<1, 4>>;
constexpr const std::chrono::seconds fluff_average_in{CRYPTONOTE_DANDELIONPP_FLUSH_AVERAGE};
/*! Bitcoin Core is using 1/2 average seconds for outgoing connections
compared to incoming. The thinking is that the user controls outgoing
connections (Dandelion++ makes similar assumptions in its stem
algorithm). The randomization yields 95% values between 1s-4s in
1/4s increments. */
using fluff_duration = crypto::random_poisson_subseconds::result_type;
constexpr const fluff_duration fluff_average_out{fluff_duration{fluff_average_in} / 2};
/*! Select a randomized duration from 0 to `range`. The precision will be to
the systems `steady_clock`. As an example, supplying 3 seconds to this
function will select a duration from [0, 3] seconds, and the increments
for the selection will be determined by the `steady_clock` precision
(typically nanoseconds).
\return A randomized duration from 0 to `range`. */
std::chrono::steady_clock::duration random_duration(std::chrono::steady_clock::duration range)
{
using rep = std::chrono::steady_clock::rep;
return std::chrono::steady_clock::duration{crypto::rand_range(rep(0), range.count())};
}
uint64_t get_median_remote_height(connections& p2p)
{
std::vector<uint64_t> remote_heights;
remote_heights.reserve(connection_id_reserve_size);
p2p.foreach_connection([&remote_heights] (detail::p2p_context& context) {
if (!context.m_is_income)
{
remote_heights.emplace_back(context.m_remote_blockchain_height);
}
return true;
});
if (remote_heights.empty())
{
return 0;
}
const size_t n = remote_heights.size() / 2;
std::sort(remote_heights.begin(), remote_heights.end());
if (remote_heights.size() % 2 != 0)
{
return remote_heights[n];
}
return remote_heights[n-1];
}
uint64_t get_blockchain_height(connections& p2p, const i_core_events* core)
{
const uint64_t local_blockchain_height = core->get_current_blockchain_height();
if (core->is_synchronized())
{
return local_blockchain_height;
}
return std::max(local_blockchain_height, get_median_remote_height(p2p));
}
//! \return Outgoing connections supporting fragments in `connections` filtered by blockchain height.
std::vector<boost::uuids::uuid> get_out_connections(connections& p2p, uint64_t blockchain_height)
{
std::vector<boost::uuids::uuid> outs;
outs.reserve(connection_id_reserve_size);
/* The foreach call is serialized with a lock, but should be quick due to
the reserve call so a strand is not used. Investigate if there is lots
of waiting in here. */
p2p.foreach_connection([&outs, blockchain_height] (detail::p2p_context& context) {
if (!context.m_is_income && context.m_remote_blockchain_height >= blockchain_height)
outs.emplace_back(context.m_connection_id);
return true;
});
MDEBUG("Found " << outs.size() << " out connections having height >= " << blockchain_height);
return outs;
}
std::vector<boost::uuids::uuid> get_out_connections(connections& p2p, const i_core_events* core)
{
return get_out_connections(p2p, get_blockchain_height(p2p, core));
}
epee::levin::message_writer make_tx_message(std::vector<blobdata>&& txs, const bool pad, const bool fluff)
{
NOTIFY_NEW_TRANSACTIONS::request request{};
request.txs = std::move(txs);
request.dandelionpp_fluff = fluff;
if (pad)
{
size_t bytes = 9 /* header */ + 4 /* 1 + 'txs' */ + tools::get_varint_data(request.txs.size()).size();
for(auto tx_blob_it = request.txs.begin(); tx_blob_it!=request.txs.end(); ++tx_blob_it)
bytes += tools::get_varint_data(tx_blob_it->size()).size() + tx_blob_it->size();
// stuff some dummy bytes in to stay safe from traffic volume analysis
static constexpr const size_t granularity = 1024;
size_t padding = granularity - bytes % granularity;
const size_t overhead = 2 /* 1 + '_' */ + tools::get_varint_data(padding).size();
if (overhead > padding)
padding = 0;
else
padding -= overhead;
request._ = std::string(padding, ' ');
epee::byte_slice arg_buff;
epee::serialization::store_t_to_binary(request, arg_buff);
// we probably lowballed the payload size a bit, so added a but too much. Fix this now.
size_t remove = arg_buff.size() % granularity;
if (remove > request._.size())
request._.clear();
else
request._.resize(request._.size() - remove);
// if the size of _ moved enough, we might lose byte in size encoding, we don't care
}
epee::levin::message_writer out;
if (!epee::serialization::store_t_to_binary(request, out.buffer))
throw std::runtime_error{"Failed to serialize to epee binary format"};
return out;
}
bool make_payload_send_txs(connections& p2p, std::vector<blobdata>&& txs, const boost::uuids::uuid& destination, const bool pad, const bool fluff)
{
epee::byte_slice blob = make_tx_message(std::move(txs), pad, fluff).finalize_notify(NOTIFY_NEW_TRANSACTIONS::ID);
return p2p.send(std::move(blob), destination);
}
/* The current design uses `asio::strand`s. The documentation isn't as clear
as it should be - a `strand` has an internal `mutex` and `bool`. The
`mutex` synchronizes thread access and the `bool` is set when a thread is
executing something "in the strand". Therefore, if a callback has lots of
work to do in a `strand`, asio can switch to some other task instead of
blocking 1+ threads to wait for the original thread to complete the task
(as is the case when client code has a `mutex` inside the callback). The
downside is that asio _always_ allocates for the callback, even if it can
be immediately executed. So if all work in a strand is minimal, a lock
may be better.
This code uses a strand per "zone" and a strand per "channel in a zone".
`dispatch` is used heavily, which means "execute immediately in _this_
thread if the strand is not in use, otherwise queue the callback to be
executed immediately after the strand completes its current task".
`post` is used where deferred execution to an `asio::io_service::run`
thread is preferred.
The strand per "zone" is useful because the levin
`foreach_connection` is blocked with a mutex anyway. So this primarily
helps with reducing blocking of a thread attempting a "flood"
notification. Updating/merging the outgoing connections in the
Dandelion++ map is also somewhat expensive.
The strand per "channel" may need a re-visit. The most "expensive" code
is figuring out the noise/notification to send. If levin code is
optimized further, it might be better to just use standard locks per
channel. */
//! A queue of levin messages for a noise i2p/tor link
struct noise_channel
{
explicit noise_channel(boost::asio::io_service& io_service)
: active(nullptr),
queue(),
strand(io_service),
next_noise(io_service),
connection(boost::uuids::nil_uuid())
{}
// `asio::io_service::strand` cannot be copied or moved
noise_channel(const noise_channel&) = delete;
noise_channel& operator=(const noise_channel&) = delete;
// Only read/write these values "inside the strand"
epee::byte_slice active;
std::deque<epee::byte_slice> queue;
boost::asio::io_service::strand strand;
boost::asio::steady_timer next_noise;
boost::uuids::uuid connection;
};
} // anonymous
namespace detail
{
struct zone
{
explicit zone(boost::asio::io_service& io_service, std::shared_ptr<connections> p2p, epee::byte_slice noise_in, epee::net_utils::zone zone, bool pad_txs)
: p2p(std::move(p2p)),
noise(std::move(noise_in)),
next_epoch(io_service),
flush_txs(io_service),
strand(io_service),
map(),
channels(),
connection_count(0),
flush_callbacks(0),
nzone(zone),
pad_txs(pad_txs),
fluffing(false)
{
for (std::size_t count = 0; !noise.empty() && count < CRYPTONOTE_NOISE_CHANNELS; ++count)
channels.emplace_back(io_service);
}
const std::shared_ptr<connections> p2p;
const epee::byte_slice noise; //!< `!empty()` means zone is using noise channels
boost::asio::steady_timer next_epoch;
boost::asio::steady_timer flush_txs;
boost::asio::io_service::strand strand;
struct context_t {
std::vector<cryptonote::blobdata> fluff_txs;
std::chrono::steady_clock::time_point flush_time;
bool m_is_income;
};
boost::unordered_map<boost::uuids::uuid, context_t> contexts;
net::dandelionpp::connection_map map;//!< Tracks outgoing uuid's for noise channels or Dandelion++ stems
std::deque<noise_channel> channels; //!< Never touch after init; only update elements on `noise_channel.strand`
std::atomic<std::size_t> connection_count; //!< Only update in strand, can be read at any time
std::uint32_t flush_callbacks; //!< Number of active fluff flush callbacks queued
const epee::net_utils::zone nzone; //!< Zone is public ipv4/ipv6 connections, or i2p or tor
const bool pad_txs; //!< Pad txs to the next boundary for privacy
bool fluffing; //!< Zone is in Dandelion++ fluff epoch
};
} // detail
namespace
{
//! Adds a message to the sending queue of the channel.
class queue_covert_notify
{
std::shared_ptr<detail::zone> zone_;
epee::byte_slice message_; // Requires manual copy constructor
const std::size_t destination_;
public:
queue_covert_notify(std::shared_ptr<detail::zone> zone, epee::byte_slice message, std::size_t destination)
: zone_(std::move(zone)), message_(std::move(message)), destination_(destination)
{}
queue_covert_notify(queue_covert_notify&&) = default;
queue_covert_notify(const queue_covert_notify& source)
: zone_(source.zone_), message_(source.message_.clone()), destination_(source.destination_)
{}
//! \pre Called within `zone_->channels[destionation_].strand`.
void operator()()
{
if (!zone_)
return;
noise_channel& channel = zone_->channels.at(destination_);
assert(channel.strand.running_in_this_thread());
if (!channel.connection.is_nil())
channel.queue.push_back(std::move(message_));
else if (destination_ == 0 && zone_->connection_count == 0)
MWARNING("Unable to send transaction(s) to " << epee::net_utils::zone_to_string(zone_->nzone) <<
" - no available outbound connections");
}
};
//! Sends txs on connections with expired timers, and queues callback for next timer expiration (if any).
struct fluff_flush
{
std::shared_ptr<detail::zone> zone_;
static void queue(std::shared_ptr<detail::zone> zone, const std::chrono::steady_clock::time_point flush_time)
{
assert(zone != nullptr);
assert(zone->strand.running_in_this_thread());
detail::zone& this_zone = *zone;
++this_zone.flush_callbacks;
this_zone.flush_txs.expires_at(flush_time);
this_zone.flush_txs.async_wait(this_zone.strand.wrap(fluff_flush{std::move(zone)}));
}
void operator()(const boost::system::error_code error)
{
if (!zone_ || !zone_->flush_callbacks || --zone_->flush_callbacks || !zone_->p2p)
return;
assert(zone_->strand.running_in_this_thread());
const bool timer_error = bool(error);
if (timer_error && error != boost::system::errc::operation_canceled)
throw boost::system::system_error{error, "fluff_flush timer failed"};
const auto now = std::chrono::steady_clock::now();
auto next_flush = std::chrono::steady_clock::time_point::max();
std::vector<std::pair<std::vector<blobdata>, boost::uuids::uuid>> connections{};
for (auto &e: zone_->contexts)
{
auto &id = e.first;
auto &context = e.second;
if (!context.fluff_txs.empty())
{
if (context.flush_time <= now || timer_error) // flush on canceled timer
{
context.flush_time = std::chrono::steady_clock::time_point::max();
connections.emplace_back(std::move(context.fluff_txs), id);
context.fluff_txs.clear();
}
else // not flushing yet
next_flush = std::min(next_flush, context.flush_time);
}
else // nothing to flush
context.flush_time = std::chrono::steady_clock::time_point::max();
}
/* Always send with `fluff` flag, even over i2p/tor. The hidden service
will disable the forwarding delay and immediately fluff. The i2p/tor
network is therefore replacing the sybil protection of Dandelion++.
Dandelion++ stem phase over i2p/tor is also worth investigating
(with/without "noise"?). */
for (auto& connection : connections)
{
std::sort(connection.first.begin(), connection.first.end()); // don't leak receive order
make_payload_send_txs(*zone_->p2p, std::move(connection.first), connection.second, zone_->pad_txs, true);
}
if (next_flush != std::chrono::steady_clock::time_point::max())
fluff_flush::queue(std::move(zone_), next_flush);
}
};
/*! The "fluff" portion of the Dandelion++ algorithm. Every tx is queued
per-connection and flushed with a randomized poisson timer. This
implementation only has one system timer per-zone, and instead tracks
the lowest flush time. */
struct fluff_notify
{
std::shared_ptr<detail::zone> zone_;
std::vector<blobdata> txs_;
boost::uuids::uuid source_;
void operator()()
{
run(std::move(zone_), epee::to_span(txs_), source_);
}
static void run(std::shared_ptr<detail::zone> zone, epee::span<const blobdata> txs, const boost::uuids::uuid& source)
{
if (!zone || !zone->p2p || txs.empty())
return;
assert(zone->strand.running_in_this_thread());
const auto now = std::chrono::steady_clock::now();
auto next_flush = std::chrono::steady_clock::time_point::max();
crypto::random_poisson_subseconds in_duration(fluff_average_in);
crypto::random_poisson_subseconds out_duration(fluff_average_out);
MDEBUG("Queueing " << txs.size() << " transaction(s) for Dandelion++ fluffing");
for (auto &e: zone->contexts)
{
auto &id = e.first;
auto &context = e.second;
// When i2p/tor, only fluff to outbound connections
if (source != id && (zone->nzone == epee::net_utils::zone::public_ || !context.m_is_income))
{
if (context.fluff_txs.empty())
context.flush_time = now + (context.m_is_income ? in_duration() : out_duration());
next_flush = std::min(next_flush, context.flush_time);
context.fluff_txs.reserve(context.fluff_txs.size() + txs.size());
context.fluff_txs.insert(context.fluff_txs.end(), txs.begin(), txs.end());
}
}
if (next_flush == std::chrono::steady_clock::time_point::max())
MWARNING("Unable to send transaction(s), no available connections");
else if (!zone->flush_callbacks || next_flush < zone->flush_txs.expires_at())
fluff_flush::queue(std::move(zone), next_flush);
}
};
//! Updates the connection for a channel.
struct update_channel
{
std::shared_ptr<detail::zone> zone_;
const std::size_t channel_;
const boost::uuids::uuid connection_;
//! \pre Called within `stem_.strand`.
void operator()() const
{
if (!zone_)
return;
noise_channel& channel = zone_->channels.at(channel_);
assert(channel.strand.running_in_this_thread());
static_assert(
CRYPTONOTE_MAX_FRAGMENTS <= (noise_min_epoch / (noise_min_delay + noise_delay_range)),
"Max fragments more than the max that can be sent in an epoch"
);
/* This clears the active message so that a message "in-flight" is
restarted. DO NOT try to send the remainder of the fragments, this
additional send time can leak that this node was sending out a real
notify (tx) instead of dummy noise. */
channel.connection = connection_;
channel.active = nullptr;
if (connection_.is_nil())
channel.queue.clear();
}
};
//! Merges `out_connections_` into the existing `zone_->map`.
struct update_channels
{
std::shared_ptr<detail::zone> zone_;
std::vector<boost::uuids::uuid> out_connections_;
//! \pre Called within `zone->strand`.
static void post(std::shared_ptr<detail::zone> zone)
{
if (!zone)
return;
assert(zone->strand.running_in_this_thread());
zone->connection_count = zone->map.size();
// only noise uses the "noise channels", only update when enabled
if (zone->noise.empty())
return;
for (auto id = zone->map.begin(); id != zone->map.end(); ++id)
{
const std::size_t i = id - zone->map.begin();
zone->channels[i].strand.post(update_channel{zone, i, *id});
}
}
//! \pre Called within `zone_->strand`.
static void run(std::shared_ptr<detail::zone> zone, std::vector<boost::uuids::uuid> out_connections)
{
if (!zone)
return;
assert(zone->strand.running_in_this_thread());
if (zone->map.update(std::move(out_connections)))
post(std::move(zone));
}
//! \pre Called within `zone_->strand`.
void operator()()
{
run(std::move(zone_), std::move(out_connections_));
}
};
//! Checks fluff status for this node, and then does stem or fluff for txes
struct dandelionpp_notify
{
std::shared_ptr<detail::zone> zone_;
i_core_events* core_;
std::vector<blobdata> txs_;
boost::uuids::uuid source_;
//! \pre Called in `zone_->strand`
void operator()()
{
if (!zone_ || !core_ || txs_.empty())
return;
if (!zone_->fluffing)
{
core_->on_transactions_relayed(epee::to_span(txs_), relay_method::stem);
for (int tries = 2; 0 < tries; tries--)
{
const boost::uuids::uuid destination = zone_->map.get_stem(source_);
if (!destination.is_nil() && make_payload_send_txs(*zone_->p2p, std::vector<blobdata>{txs_}, destination, zone_->pad_txs, false))
{
/* Source is intentionally omitted in debug log for privacy - a
nil uuid indicates source is that node. */
MDEBUG("Sent " << txs_.size() << " transaction(s) to " << destination << " using Dandelion++ stem");
return;
}
// connection list may be outdated, try again
update_channels::run(zone_, get_out_connections(*zone_->p2p, core_));
}
MERROR("Unable to send transaction(s) via Dandelion++ stem");
}
core_->on_transactions_relayed(epee::to_span(txs_), relay_method::fluff);
fluff_notify::run(std::move(zone_), epee::to_span(txs_), source_);
}
};
//! Swaps out noise/dandelionpp channels entirely; new epoch start.
class change_channels
{
std::shared_ptr<detail::zone> zone_;
net::dandelionpp::connection_map map_; // Requires manual copy constructor
bool fluffing_;
public:
explicit change_channels(std::shared_ptr<detail::zone> zone, net::dandelionpp::connection_map map, const bool fluffing)
: zone_(std::move(zone)), map_(std::move(map)), fluffing_(fluffing)
{}
change_channels(change_channels&&) = default;
change_channels(const change_channels& source)
: zone_(source.zone_), map_(source.map_.clone())
{}
//! \pre Called within `zone_->strand`.
void operator()()
{
if (!zone_)
return;
assert(zone_->strand.running_in_this_thread());
if (zone_->nzone == epee::net_utils::zone::public_)
MDEBUG("Starting new Dandelion++ epoch: " << (fluffing_ ? "fluff" : "stem"));
zone_->map = std::move(map_);
zone_->fluffing = fluffing_;
update_channels::post(std::move(zone_));
}
};
//! Sends a noise packet or real notification and sets timer for next call.
struct send_noise
{
std::shared_ptr<detail::zone> zone_;
const std::size_t channel_;
const i_core_events* core_;
static void wait(const std::chrono::steady_clock::time_point start, std::shared_ptr<detail::zone> zone, const std::size_t index, const i_core_events* core)
{
if (!zone)
return;
noise_channel& channel = zone->channels.at(index);
channel.next_noise.expires_at(start + noise_min_delay + random_duration(noise_delay_range));
channel.next_noise.async_wait(
channel.strand.wrap(send_noise{std::move(zone), index, core})
);
}
//! \pre Called within `zone_->channels[channel_].strand`.
void operator()(boost::system::error_code error)
{
if (!zone_ || !zone_->p2p || zone_->noise.empty())
return;
if (error && error != boost::system::errc::operation_canceled)
throw boost::system::system_error{error, "send_noise timer failed"};
assert(zone_->channels.at(channel_).strand.running_in_this_thread());
const auto start = std::chrono::steady_clock::now();
noise_channel& channel = zone_->channels.at(channel_);
if (!channel.connection.is_nil())
{
epee::byte_slice message = nullptr;
if (!channel.active.empty())
message = channel.active.take_slice(zone_->noise.size());
else if (!channel.queue.empty())
{
channel.active = channel.queue.front().clone();
message = channel.active.take_slice(zone_->noise.size());
}
else
message = zone_->noise.clone();
if (zone_->p2p->send(std::move(message), channel.connection))
{
if (!channel.queue.empty() && channel.active.empty())
channel.queue.pop_front();
}
else
{
channel.active = nullptr;
channel.connection = boost::uuids::nil_uuid();
auto height = get_blockchain_height(*zone_->p2p, core_);
auto connections = get_out_connections(*zone_->p2p, height);
if (connections.empty())
MWARNING("Unable to send transaction(s) to " << epee::net_utils::zone_to_string(zone_->nzone) <<
" - no suitable outbound connections at height " << height);
zone_->strand.post(update_channels{zone_, std::move(connections)});
}
}
wait(start, std::move(zone_), channel_, core_);
}
};
//! Prepares connections for new channel/dandelionpp epoch and sets timer for next epoch
struct start_epoch
{
// Variables allow for Dandelion++ extension
std::shared_ptr<detail::zone> zone_;
std::chrono::seconds min_epoch_;
std::chrono::seconds epoch_range_;
std::size_t count_;
const i_core_events* core_;
//! \pre Should not be invoked within any strand to prevent blocking.
void operator()(const boost::system::error_code error = {})
{
if (!zone_ || !zone_->p2p)
return;
if (error && error != boost::system::errc::operation_canceled)
throw boost::system::system_error{error, "start_epoch timer failed"};
const bool fluffing = crypto::rand_idx(unsigned(100)) < CRYPTONOTE_DANDELIONPP_FLUFF_PROBABILITY;
const auto start = std::chrono::steady_clock::now();
auto connections = get_out_connections(*(zone_->p2p), core_);
zone_->strand.dispatch(
change_channels{zone_, net::dandelionpp::connection_map{std::move(connections), count_}, fluffing}
);
detail::zone& alias = *zone_;
alias.next_epoch.expires_at(start + min_epoch_ + random_duration(epoch_range_));
alias.next_epoch.async_wait(start_epoch{std::move(*this)});
}
};
} // anonymous
notify::notify(boost::asio::io_service& service, std::shared_ptr<connections> p2p, epee::byte_slice noise, epee::net_utils::zone zone, const bool pad_txs, i_core_events& core)
: zone_(std::make_shared<detail::zone>(service, std::move(p2p), std::move(noise), zone, pad_txs))
, core_(std::addressof(core))
{
if (!zone_->p2p)
throw std::logic_error{"cryptonote::levin::notify cannot have nullptr p2p argument"};
const bool noise_enabled = !zone_->noise.empty();
if (noise_enabled || zone == epee::net_utils::zone::public_)
{
const auto now = std::chrono::steady_clock::now();
const auto min_epoch = noise_enabled ? noise_min_epoch : dandelionpp_min_epoch;
const auto epoch_range = noise_enabled ? noise_epoch_range : dandelionpp_epoch_range;
const std::size_t out_count = noise_enabled ? CRYPTONOTE_NOISE_CHANNELS : CRYPTONOTE_DANDELIONPP_STEMS;
start_epoch{zone_, min_epoch, epoch_range, out_count, core_}();
for (std::size_t channel = 0; channel < zone_->channels.size(); ++channel)
send_noise::wait(now, zone_, channel, core_);
}
}
notify::~notify() noexcept
{}
notify::status notify::get_status() const noexcept
{
if (!zone_)
return {false, false};
return {!zone_->noise.empty(), CRYPTONOTE_NOISE_CHANNELS <= zone_->connection_count};
}
void notify::new_out_connection()
{
if (!zone_ || zone_->noise.empty() || CRYPTONOTE_NOISE_CHANNELS <= zone_->connection_count)
return;
zone_->strand.dispatch(
update_channels{zone_, get_out_connections(*(zone_->p2p), core_)}
);
}
void notify::on_handshake_complete(const boost::uuids::uuid &id, bool is_income)
{
if (!zone_)
return;
auto& zone = zone_;
zone_->strand.dispatch([zone, id, is_income]{
zone->contexts[id] = {
.fluff_txs = {},
.flush_time = std::chrono::steady_clock::time_point::max(),
.m_is_income = is_income,
};
});
}
void notify::on_connection_close(const boost::uuids::uuid &id)
{
if (!zone_)
return;
auto& zone = zone_;
zone_->strand.dispatch([zone, id]{
zone->contexts.erase(id);
});
}
void notify::run_epoch()
{
if (!zone_)
return;
zone_->next_epoch.cancel();
}
void notify::run_stems()
{
if (!zone_)
return;
for (noise_channel& channel : zone_->channels)
channel.next_noise.cancel();
}
void notify::run_fluff()
{
if (!zone_)
return;
zone_->flush_txs.cancel();
}
bool notify::send_txs(std::vector<blobdata> txs, const boost::uuids::uuid& source, relay_method tx_relay)
{
if (txs.empty())
return true;
if (!zone_)
return false;
/* If noise is enabled in a zone, it always takes precedence. The technique
provides good protection against ISP adversaries, but not sybil
adversaries. Noise is currently only enabled over I2P/Tor - those
networks provide protection against sybil attacks (we only send to
outgoing connections).
If noise is disabled, Dandelion++ is used for public networks only.
Dandelion++ over I2P/Tor should be an interesting case to investigate,
but the mempool/stempool needs to know the zone a tx originated from to
work properly. */
if (!zone_->noise.empty() && !zone_->channels.empty())
{
// covert send in "noise" channel
static_assert(
CRYPTONOTE_MAX_FRAGMENTS * CRYPTONOTE_NOISE_BYTES <= LEVIN_DEFAULT_MAX_PACKET_SIZE, "most nodes will reject this fragment setting"
);
if (tx_relay == relay_method::stem)
{
MWARNING("Dandelion++ stem not supported over noise networks");
tx_relay = relay_method::local; // do not put into stempool embargo (hopefully not there already!).
}
core_->on_transactions_relayed(epee::to_span(txs), tx_relay);
// Padding is not useful when using noise mode. Send as stem so receiver
// forwards in Dandelion++ mode.
epee::byte_slice message = epee::levin::make_fragmented_notify(
zone_->noise.size(), NOTIFY_NEW_TRANSACTIONS::ID, make_tx_message(std::move(txs), false, false)
);
if (CRYPTONOTE_MAX_FRAGMENTS * zone_->noise.size() < message.size())
{
MERROR("notify::send_txs provided message exceeding covert fragment size");
return false;
}
for (std::size_t channel = 0; channel < zone_->channels.size(); ++channel)
{
zone_->channels[channel].strand.dispatch(
queue_covert_notify{zone_, message.clone(), channel}
);
}
}
else
{
switch (tx_relay)
{
default:
case relay_method::none:
case relay_method::block:
return false;
case relay_method::stem:
case relay_method::forward:
case relay_method::local:
if (zone_->nzone == epee::net_utils::zone::public_)
{
// this will change a local/forward tx to stem or fluff ...
zone_->strand.dispatch(
dandelionpp_notify{zone_, core_, std::move(txs), source}
);
break;
}
/* fallthrough */
case relay_method::fluff:
/* If sending stem/forward/local txes over non public networks,
continue to claim that relay mode even though it used the "fluff"
routine. A "fluff" over i2p/tor is not the same as a "fluff" over
ipv4/6. Marking it as "fluff" here will make the tx immediately
visible externally from this node, which is not desired. */
core_->on_transactions_relayed(epee::to_span(txs), tx_relay);
zone_->strand.dispatch(fluff_notify{zone_, std::move(txs), source});
break;
}
}
return true;
}
} // levin
} // net
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