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/*
This file is part of cpp-ethereum.
cpp-ethereum is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
cpp-ethereum is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file NodeTable.h
* @author Alex Leverington <nessence@gmail.com>
* @date 2014
*/
#pragma once
#include <algorithm>
#include <deque>
#include <boost/integer/static_log2.hpp>
#include <libp2p/UDP.h>
#include "Common.h"
namespace dev
{
namespace p2p
{
/**
* NodeEntry
* @brief Entry in Node Table
*/
struct NodeEntry: public Node
{
NodeEntry(Node _src, Public _pubk, NodeIPEndpoint _gw);
NodeEntry(Node _src, Public _pubk, bi::udp::endpoint _udp);
unsigned const distance; ///< Node's distance (xor of _src as integer).
};
enum NodeTableEventType {
NodeEntryAdded,
NodeEntryRemoved
};
class NodeTable;
class NodeTableEventHandler
{
friend class NodeTable;
public:
virtual void processEvent(NodeId const& _n, NodeTableEventType const& _e) = 0;
protected:
/// Called by NodeTable on behalf of an implementation (Host) to process new events without blocking nodetable.
void processEvents()
{
std::list<std::pair<NodeId, NodeTableEventType>> events;
{
Guard l(x_events);
if (!m_nodeEventHandler.size())
return;
m_nodeEventHandler.unique();
for (auto const& n: m_nodeEventHandler)
events.push_back(std::make_pair(n,m_events[n]));
m_nodeEventHandler.clear();
m_events.clear();
}
for (auto const& e: events)
processEvent(e.first, e.second);
}
/// Called by NodeTable to append event.
virtual void appendEvent(NodeId _n, NodeTableEventType _e) { Guard l(x_events); m_nodeEventHandler.push_back(_n); m_events[_n] = _e; }
Mutex x_events;
std::list<NodeId> m_nodeEventHandler;
std::map<NodeId, NodeTableEventType> m_events;
};
class NodeTable;
inline std::ostream& operator<<(std::ostream& _out, NodeTable const& _nodeTable);
/**
* NodeTable using modified kademlia for node discovery and preference.
* Node table requires an IO service, creates a socket for incoming
* UDP messages and implements a kademlia-like protocol. Node requests and
* responses are used to build a node table which can be queried to
* obtain a list of potential nodes to connect to, and, passes events to
* Host whenever a node is added or removed to/from the table.
*
* Thread-safety is ensured by modifying NodeEntry details via
* shared_ptr replacement instead of mutating values.
*
* NodeTable accepts a port for UDP and will listen to the port on all available
* interfaces.
*
* [Integration]
* @todo restore nodes: affects refreshbuckets
* @todo TCP endpoints
* @todo makeRequired: don't try to evict node if node isRequired.
* @todo makeRequired: exclude bucket from refresh if we have node as peer.
*
* [Optimization]
* @todo serialize evictions per-bucket
* @todo store evictions in map, unit-test eviction logic
* @todo store root node in table
* @todo encapsulate discover into NetworkAlgorithm (task)
* @todo Pong to include ip:port where ping was received
* @todo expiration and sha3(id) 'to' for messages which are replies (prevents replay)
* @todo cache Ping and FindSelf
*
* [Networking]
* @todo node-endpoint updates
* @todo TCP endpoints
* @todo eth/upnp/natpmp/stun/ice/etc for public-discovery
* @todo firewall
*
* [Protocol]
* @todo optimize knowledge at opposite edges; eg, s_bitsPerStep lookups. (Can be done via pointers to NodeBucket)
* @todo ^ s_bitsPerStep = 8; // Denoted by b in [Kademlia]. Bits by which address space is divided.
*/
class NodeTable: UDPSocketEvents, public std::enable_shared_from_this<NodeTable>
{
friend std::ostream& operator<<(std::ostream& _out, NodeTable const& _nodeTable);
using NodeSocket = UDPSocket<NodeTable, 1280>;
using TimePoint = std::chrono::steady_clock::time_point;
using EvictionTimeout = std::pair<std::pair<NodeId, TimePoint>, NodeId>; ///< First NodeId may be evicted and replaced with second NodeId.
public:
NodeTable(ba::io_service& _io, KeyPair _alias, uint16_t _udpPort = 30303);
~NodeTable();
/// Returns distance based on xor metric two node ids. Used by NodeEntry and NodeTable.
static unsigned distance(NodeId const& _a, NodeId const& _b) { u512 d = _a ^ _b; unsigned ret; for (ret = 0; d >>= 1; ++ret) {}; return ret; }
/// Set event handler for NodeEntryAdded and NodeEntryRemoved events.
void setEventHandler(NodeTableEventHandler* _handler) { m_nodeEventHandler.reset(_handler); }
/// Called by implementation which provided handler to process NodeEntryAdded/NodeEntryRemoved events. Events are coalesced by type whereby old events are ignored.
void processEvents();
/// Add node. Node will be pinged if it's not already known.
std::shared_ptr<NodeEntry> addNode(Public const& _pubk, bi::udp::endpoint const& _udp, bi::tcp::endpoint const& _tcp);
/// Add node. Node will be pinged if it's not already known.
std::shared_ptr<NodeEntry> addNode(Node const& _node);
/// To be called when node table is empty. Runs node discovery with m_node.id as the target in order to populate node-table.
void discover();
/// Returns list of node ids active in node table.
std::list<NodeId> nodes() const;
/// Returns node count.
unsigned count() const { return m_nodes.size(); }
/// Returns snapshot of table.
std::list<NodeEntry> snapshot() const;
/// Returns true if node id is in node table.
bool haveNode(NodeId const& _id) { Guard l(x_nodes); return m_nodes.count(_id) > 0; }
/// Returns the Node to the corresponding node id or the empty Node if that id is not found.
Node node(NodeId const& _id);
#if defined(BOOST_AUTO_TEST_SUITE) || defined(_MSC_VER) // MSVC includes access specifier in symbol name
protected:
#else
private:
#endif
/// Constants for Kademlia, derived from address space.
static unsigned const s_addressByteSize = sizeof(NodeId); ///< Size of address type in bytes.
static unsigned const s_bits = 8 * s_addressByteSize; ///< Denoted by n in [Kademlia].
static unsigned const s_bins = s_bits - 1; ///< Size of m_state (excludes root, which is us).
static unsigned const s_maxSteps = boost::static_log2<s_bits>::value; ///< Max iterations of discovery. (discover)
/// Chosen constants
static unsigned const s_bucketSize = 16; ///< Denoted by k in [Kademlia]. Number of nodes stored in each bucket.
static unsigned const s_alpha = 3; ///< Denoted by \alpha in [Kademlia]. Number of concurrent FindNode requests.
/// Intervals
/* todo: replace boost::posix_time; change constants to upper camelcase */
boost::posix_time::milliseconds const c_evictionCheckInterval = boost::posix_time::milliseconds(75); ///< Interval at which eviction timeouts are checked.
std::chrono::milliseconds const c_reqTimeout = std::chrono::milliseconds(300); ///< How long to wait for requests (evict, find iterations).
std::chrono::seconds const c_bucketRefresh = std::chrono::seconds(3600); ///< Refresh interval prevents bucket from becoming stale. [Kademlia]
struct NodeBucket
{
unsigned distance;
TimePoint modified;
std::list<std::weak_ptr<NodeEntry>> nodes;
void touch() { modified = std::chrono::steady_clock::now(); }
};
/// Used to ping endpoint.
void ping(bi::udp::endpoint _to) const;
/// Used ping known node. Used by node table when refreshing buckets and as part of eviction process (see evict).
void ping(NodeEntry* _n) const;
/// Returns center node entry which describes this node and used with dist() to calculate xor metric for node table nodes.
NodeEntry center() const { return NodeEntry(m_node, m_node.publicKey(), m_node.endpoint.udp); }
/// Used by asynchronous operations to return NodeEntry which is active and managed by node table.
std::shared_ptr<NodeEntry> nodeEntry(NodeId _id);
/// Used to discovery nodes on network which are close to the given target.
/// Sends s_alpha concurrent requests to nodes nearest to target, for nodes nearest to target, up to s_maxSteps rounds.
void discover(NodeId _target, unsigned _round = 0, std::shared_ptr<std::set<std::shared_ptr<NodeEntry>>> _tried = std::shared_ptr<std::set<std::shared_ptr<NodeEntry>>>());
/// Returns nodes from node table which are closest to target.
std::vector<std::shared_ptr<NodeEntry>> nearestNodeEntries(NodeId _target);
/// Asynchronously drops _leastSeen node if it doesn't reply and adds _new node, otherwise _new node is thrown away.
void evict(std::shared_ptr<NodeEntry> _leastSeen, std::shared_ptr<NodeEntry> _new);
/// Called whenever activity is received from an unknown node in order to maintain node table.
void noteActiveNode(Public const& _pubk, bi::udp::endpoint const& _endpoint);
/// Used to drop node when timeout occurs or when evict() result is to keep previous node.
void dropNode(std::shared_ptr<NodeEntry> _n);
/// Returns references to bucket which corresponds to distance of node id.
/// @warning Only use the return reference locked x_state mutex.
// TODO p2p: Remove this method after removing offset-by-one functionality.
NodeBucket& bucket_UNSAFE(NodeEntry const* _n);
/// General Network Events
/// Called by m_socket when packet is received.
void onReceived(UDPSocketFace*, bi::udp::endpoint const& _from, bytesConstRef _packet);
/// Called by m_socket when socket is disconnected.
void onDisconnected(UDPSocketFace*) {}
/// Tasks
/// Called by evict() to ensure eviction check is scheduled to run and terminates when no evictions remain. Asynchronous.
void doCheckEvictions(boost::system::error_code const& _ec);
/// Purges and pings nodes for any buckets which haven't been touched for c_bucketRefresh seconds.
void doRefreshBuckets(boost::system::error_code const& _ec);
std::unique_ptr<NodeTableEventHandler> m_nodeEventHandler; ///< Event handler for node events.
Node m_node; ///< This node.
Secret m_secret; ///< This nodes secret key.
mutable Mutex x_nodes; ///< LOCK x_state first if both locks are required. Mutable for thread-safe copy in nodes() const.
std::map<NodeId, std::shared_ptr<NodeEntry>> m_nodes; ///< Nodes
mutable Mutex x_state; ///< LOCK x_state first if both x_nodes and x_state locks are required.
std::array<NodeBucket, s_bins> m_state; ///< State of p2p node network.
Mutex x_evictions; ///< LOCK x_nodes first if both x_nodes and x_evictions locks are required.
std::deque<EvictionTimeout> m_evictions; ///< Eviction timeouts.
ba::io_service& m_io; ///< Used by bucket refresh timer.
std::shared_ptr<NodeSocket> m_socket; ///< Shared pointer for our UDPSocket; ASIO requires shared_ptr.
NodeSocket* m_socketPointer; ///< Set to m_socket.get(). Socket is created in constructor and disconnected in destructor to ensure access to pointer is safe.
boost::asio::deadline_timer m_bucketRefreshTimer; ///< Timer which schedules and enacts bucket refresh.
boost::asio::deadline_timer m_evictionCheckTimer; ///< Timer for handling node evictions.
};
inline std::ostream& operator<<(std::ostream& _out, NodeTable const& _nodeTable)
{
_out << _nodeTable.center().address() << "\t" << "0\t" << _nodeTable.center().endpoint.udp.address() << ":" << _nodeTable.center().endpoint.udp.port() << std::endl;
auto s = _nodeTable.snapshot();
for (auto n: s)
_out << n.address() << "\t" << n.distance << "\t" << n.endpoint.udp.address() << ":" << n.endpoint.udp.port() << std::endl;
return _out;
}
/**
* Ping packet: Sent to check if node is alive.
* PingNode is cached and regenerated after expiration - t, where t is timeout.
*
* Ping is used to implement evict. When a new node is seen for
* a given bucket which is full, the least-responsive node is pinged.
* If the pinged node doesn't respond, then it is removed and the new
* node is inserted.
*
* RLP Encoded Items: 3
* Minimum Encoded Size: 18 bytes
* Maximum Encoded Size: bytes // todo after u128 addresses
*
* signature: Signature of message.
* ipAddress: Our IP address.
* port: Our port.
* expiration: Triggers regeneration of packet. May also provide control over synchronization.
*
* @todo uint128_t for ip address (<->integer ipv4/6, asio-address, asio-endpoint)
*
*/
struct PingNode: RLPXDatagram<PingNode>
{
PingNode(bi::udp::endpoint _ep): RLPXDatagram<PingNode>(_ep) {}
PingNode(bi::udp::endpoint _ep, std::string _src, uint16_t _srcPort, std::chrono::seconds _expiration = std::chrono::seconds(60)): RLPXDatagram<PingNode>(_ep), ipAddress(_src), port(_srcPort), expiration(futureFromEpoch(_expiration)) {}
static const uint8_t type = 1;
unsigned version = 1;
std::string ipAddress;
unsigned port;
unsigned expiration;
void streamRLP(RLPStream& _s) const { _s.appendList(3); _s << ipAddress << port << expiration; }
void interpretRLP(bytesConstRef _bytes) { RLP r(_bytes); ipAddress = r[0].toString(); port = r[1].toInt<unsigned>(); expiration = r[2].toInt<unsigned>(); }
};
/**
* Pong packet: Sent in response to ping
*
* RLP Encoded Items: 2
* Minimum Encoded Size: 33 bytes
* Maximum Encoded Size: 33 bytes
*/
struct Pong: RLPXDatagram<Pong>
{
Pong(bi::udp::endpoint _ep): RLPXDatagram<Pong>(_ep), expiration(futureFromEpoch(std::chrono::seconds(60))) {}
static const uint8_t type = 2;
h256 echo; ///< MCD of PingNode
unsigned expiration;
void streamRLP(RLPStream& _s) const { _s.appendList(2); _s << echo << expiration; }
void interpretRLP(bytesConstRef _bytes) { RLP r(_bytes); echo = (h256)r[0]; expiration = r[1].toInt<unsigned>(); }
};
/**
* FindNode Packet: Request k-nodes, closest to the target.
* FindNode is cached and regenerated after expiration - t, where t is timeout.
* FindNode implicitly results in finding neighbours of a given node.
*
* RLP Encoded Items: 2
* Minimum Encoded Size: 21 bytes
* Maximum Encoded Size: 30 bytes
*
* target: NodeId of node. The responding node will send back nodes closest to the target.
* expiration: Triggers regeneration of packet. May also provide control over synchronization.
*
*/
struct FindNode: RLPXDatagram<FindNode>
{
FindNode(bi::udp::endpoint _ep): RLPXDatagram<FindNode>(_ep) {}
FindNode(bi::udp::endpoint _ep, NodeId _target, std::chrono::seconds _expiration = std::chrono::seconds(30)): RLPXDatagram<FindNode>(_ep), target(_target), expiration(futureFromEpoch(_expiration)) {}
static const uint8_t type = 3;
h512 target;
unsigned expiration;
void streamRLP(RLPStream& _s) const { _s.appendList(2); _s << target << expiration; }
void interpretRLP(bytesConstRef _bytes) { RLP r(_bytes); target = r[0].toHash<h512>(); expiration = r[1].toInt<unsigned>(); }
};
/**
* Node Packet: Multiple node packets are sent in response to FindNode.
*
* RLP Encoded Items: 2 (first item is list)
* Minimum Encoded Size: 10 bytes
*/
struct Neighbours: RLPXDatagram<Neighbours>
{
struct Node
{
Node() = default;
Node(RLP const& _r) { interpretRLP(_r); }
std::string ipAddress;
unsigned port;
NodeId node;
void streamRLP(RLPStream& _s) const { _s.appendList(3); _s << ipAddress << port << node; }
void interpretRLP(RLP const& _r) { ipAddress = _r[0].toString(); port = _r[1].toInt<unsigned>(); node = h512(_r[2].toBytes()); }
};
Neighbours(bi::udp::endpoint _ep): RLPXDatagram<Neighbours>(_ep), expiration(futureFromEpoch(std::chrono::seconds(30))) {}
Neighbours(bi::udp::endpoint _to, std::vector<std::shared_ptr<NodeEntry>> const& _nearest, unsigned _offset = 0, unsigned _limit = 0): RLPXDatagram<Neighbours>(_to), expiration(futureFromEpoch(std::chrono::seconds(30)))
{
auto limit = _limit ? std::min(_nearest.size(), (size_t)(_offset + _limit)) : _nearest.size();
for (auto i = _offset; i < limit; i++)
{
Node node;
node.ipAddress = _nearest[i]->endpoint.udp.address().to_string();
node.port = _nearest[i]->endpoint.udp.port();
node.node = _nearest[i]->publicKey();
nodes.push_back(node);
}
}
static const uint8_t type = 4;
std::vector<Node> nodes;
unsigned expiration = 1;
void streamRLP(RLPStream& _s) const { _s.appendList(2); _s.appendList(nodes.size()); for (auto& n: nodes) n.streamRLP(_s); _s << expiration; }
void interpretRLP(bytesConstRef _bytes) { RLP r(_bytes); for (auto n: r[0]) nodes.push_back(Node(n)); expiration = r[1].toInt<unsigned>(); }
};
struct NodeTableWarn: public LogChannel { static const char* name() { return "!P!"; } static const int verbosity = 0; };
struct NodeTableNote: public LogChannel { static const char* name() { return "*P*"; } static const int verbosity = 1; };
struct NodeTableMessageSummary: public LogChannel { static const char* name() { return "-P-"; } static const int verbosity = 2; };
struct NodeTableConnect: public LogChannel { static const char* name() { return "+P+"; } static const int verbosity = 10; };
struct NodeTableMessageDetail: public LogChannel { static const char* name() { return "=P="; } static const int verbosity = 5; };
struct NodeTableTriviaSummary: public LogChannel { static const char* name() { return "-P-"; } static const int verbosity = 10; };
struct NodeTableTriviaDetail: public LogChannel { static const char* name() { return "=P="; } static const int verbosity = 11; };
struct NodeTableAllDetail: public LogChannel { static const char* name() { return "=P="; } static const int verbosity = 13; };
struct NodeTableEgress: public LogChannel { static const char* name() { return ">>P"; } static const int verbosity = 14; };
struct NodeTableIngress: public LogChannel { static const char* name() { return "<<P"; } static const int verbosity = 15; };
}
}