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subtly 2014-12-22 03:56:07 +01:00
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commit 88f7ff617d
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net.cpp
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@ -23,500 +23,13 @@
#include <libdevcore/Worker.h>
#include <libdevcrypto/Common.h>
#include <libp2p/UDP.h>
#include <libp2p/NodeTable.h>
using namespace std;
using namespace dev;
using namespace dev::p2p;
namespace ba = boost::asio;
namespace bi = ba::ip;
/**
* Ping packet: Check if node is alive.
* PingNode is cached and regenerated after expiration - t, where t is timeout.
*
* signature: Signature of message.
* ipAddress: Our IP address.
* port: Our port.
* expiration: Triggers regeneration of packet. May also provide control over synchronization.
*
* 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.
*/
struct PingNode: RLPDatagram
{
bytes ipAddress;
uint16_t port;
uint64_t expiration;
Signature signature;
// void streamRLP(RLPStream& _s) const { _s.appendList(3); _s << ipAddress << port << expiration; }
};
struct Pong: RLPDatagram
{
// todo: weak-signed pong
Address from;
uint64_t replyTo; /// expiration from PingNode
void streamRLP(RLPStream& _s) const { _s.appendList(2); _s << from << replyTo; }
};
/**
* FindNeighbors Packet: Request k-nodes, closest to the target.
* FindNeighbors is cached and regenerated after expiration - t, where t is timeout.
*
* signature: Signature of message.
* target: Address of NodeId. The responding node will send back nodes closest to the target.
* expiration: Triggers regeneration of packet. May also provide control over synchronization.
*
*/
struct FindNeighbors: RLPDatagram
{
h160 target;
uint64_t expiration;
Signature signature;
void streamRLP(RLPStream& _s) const { _s.appendList(2); _s << target << expiration; }
};
/**
* Node Packet: Multiple node packets are sent in response to FindNeighbors.
*/
struct Neighbors: RLPDatagram
{
struct Node
{
bytes ipAddress;
uint16_t port;
NodeId node;
// void streamRLP(RLPStream& _s) const { _s.appendList(3); _s << ipAddress << port << node; }
};
std::set<Node> nodes;
h256 nonce;
Signature signature;
// void streamRLP(RLPStream& _s) const { _s.appendList(2); _s.appendList(nodes.size()); for (auto& n: nodes) n.streamRLP(_s); _s << nonce; }
};
/**
* NodeTable using S/Kademlia system for node discovery and preference.
* untouched buckets are refreshed if they have not been touched within an hour
*
* Thread-safety is ensured by modifying NodeEntry details via
* shared_ptr replacement instead of mutating values.
*
* @todo don't try to evict node if node isRequired. (support for makeRequired)
* @todo optimize (use tree for state (or set w/custom compare for cache))
* @todo constructor support for m_node, m_secret
* @todo use s_bitsPerStep for find and refresh/ping
* @todo exclude bucket from refresh if we have node as peer
* @todo restore nodes
*/
class NodeTable: UDPSocketEvents, public std::enable_shared_from_this<NodeTable>
{
using nodeSocket = UDPSocket<NodeTable, 1024>;
using timePoint = std::chrono::steady_clock::time_point;
static unsigned const s_bucketSize = 16; // Denoted by k in [Kademlia]. Number of nodes stored in each bucket.
// const unsigned s_bitsPerStep = 5; // @todo Denoted by b in [Kademlia]. Bits by which address space will be divided for find responses.
static unsigned const s_alpha = 3; // Denoted by \alpha in [Kademlia]. Number of concurrent FindNeighbors requests.
const unsigned s_findTimout = 300; // How long to wait between find queries.
// const unsigned s_siblings = 5; // @todo Denoted by s in [S/Kademlia]. User-defined by sub-protocols.
const unsigned s_bucketRefresh = 3600; // Refresh interval prevents bucket from becoming stale. [Kademlia]
const unsigned s_bits = sizeof(Address); // Denoted by n.
const unsigned s_buckets = 8 * s_bits - 1;
const unsigned s_evictionCheckInterval = 75; // Interval by which eviction timeouts are checked.
const unsigned s_pingTimeout = 500;
static size_t const s_tableSize = Address::size * 8 - 1; // Address::size
public:
static unsigned dist(Address const& _a, Address const& _b) { u160 d = _a ^ _b; unsigned ret; for (ret = 0; d >>= 1; ++ret) {}; return ret; }
protected:
struct NodeDefaultEndpoint
{
NodeDefaultEndpoint(bi::udp::endpoint _udp): udp(_udp) {}
bi::udp::endpoint udp;
};
struct NodeEntry
{
NodeEntry(Address _id, Public _pubk, bi::udp::endpoint _udp): id(_id), pubk(_pubk), endpoint(NodeDefaultEndpoint(_udp)), distance(0) {}
NodeEntry(NodeEntry _src, Address _id, Public _pubk, bi::udp::endpoint _udp): id(_id), pubk(_pubk), endpoint(NodeDefaultEndpoint(_udp)), distance(dist(_src.id,_id)) {}
NodeEntry(NodeEntry _src, Address _id, Public _pubk, NodeDefaultEndpoint _gw): id(_id), pubk(_pubk), endpoint(_gw), distance(dist(_src.id,_id)) {}
Address id;
Public pubk;
NodeDefaultEndpoint endpoint; ///< How we've previously connected to this node. (must match node's reported endpoint)
const unsigned distance;
timePoint activePing;
};
struct NodeBucket
{
unsigned distance;
timePoint modified;
std::list<std::weak_ptr<NodeEntry>> nodes;
};
using EvictionTimeout = std::pair<std::pair<Address,timePoint>,Address>;
public:
NodeTable(ba::io_service& _io):
m_node(NodeEntry(Address(), Public(), bi::udp::endpoint())),
m_socket(new nodeSocket(_io, *this, 30300)),
m_socketPtr(m_socket.get()),
m_io(_io),
m_bucketRefreshTimer(m_io),
m_evictionCheckTimer(m_io)
{
for (unsigned i = 0; i < s_buckets; i++)
m_state[i].distance = i, m_state[i].modified = chrono::steady_clock::now() - chrono::seconds(1);
doRefreshBuckets(boost::system::error_code());
}
~NodeTable() {
m_evictionCheckTimer.cancel();
m_bucketRefreshTimer.cancel();
m_socketPtr->disconnect();
}
void join() { doFindNode(m_node.id); }
std::list<Address> nodes() const
{
std::list<Address> nodes;
Guard l(x_nodes);
for (auto& i: m_nodes)
nodes.push_back(i.second->id);
return std::move(nodes);
}
NodeEntry operator[](Address _id)
{
Guard l(x_nodes);
return *m_nodes[_id];
}
protected:
void requestNeighbors(NodeEntry const& _node, Address _target) const
{
FindNeighbors p;
p.target = _target;
p.to = _node.endpoint.udp;
p.seal(m_secret);
m_socketPtr->send(p);
}
/// Dispatches udp requests in order to populate node table to be as close as possible to _node.
void doFindNode(Address _node, unsigned _round = 0, std::shared_ptr<std::set<std::shared_ptr<NodeEntry>>> _tried = std::shared_ptr<std::set<std::shared_ptr<NodeEntry>>>())
{
if (!m_socketPtr->isOpen() || _round == 7)
return;
auto nearest = findNearest(_node);
std::list<std::shared_ptr<NodeEntry>> tried;
for (unsigned i = 0; i < nearest.size() && tried.size() < s_alpha; i++)
if (!_tried->count(nearest[i]))
{
tried.push_back(nearest[i]);
requestNeighbors(*nearest[i], _node);
}
else
continue;
while (auto n = tried.front())
{
_tried->insert(n);
tried.pop_front();
}
auto self(shared_from_this());
m_evictionCheckTimer.expires_from_now(boost::posix_time::milliseconds(s_findTimout));
m_evictionCheckTimer.async_wait([this, self, _node, _round, _tried](boost::system::error_code const& _ec)
{
if (_ec)
return;
doFindNode(_node, _round + 1, _tried);
});
}
std::vector<std::shared_ptr<NodeEntry>> findNearest(Address _target)
{
// send s_alpha FindNeighbors packets to nodes we know, closest to target
unsigned head = dist(m_node.id, _target);
unsigned tail = (head - 1) % (s_tableSize - 1);
// todo: optimize with tree
std::map<unsigned, std::list<std::shared_ptr<NodeEntry>>> found;
unsigned count = 0;
// if d is 0, then we roll look forward, if last, we reverse, else, spread from d
if (head != 0 && tail != s_tableSize)
while (head != tail && count < s_bucketSize)
{
Guard l(x_state);
for (auto& n: m_state[head].nodes)
if (auto p = n.lock())
{
if (count < s_bucketSize)
found[dist(_target, p->id)].push_back(p);
else
break;
}
if (count < s_bucketSize && head)
for (auto& n: m_state[tail].nodes)
if (auto p = n.lock())
{
if (count < s_bucketSize)
found[dist(_target, p->id)].push_back(p);
else
break;
}
head++;
tail = (tail - 1) % (s_tableSize - 1);
}
else if (head == 0)
while (head < s_bucketSize && count < s_bucketSize)
{
Guard l(x_state);
for (auto& n: m_state[head].nodes)
if (auto p = n.lock())
{
if (count < s_bucketSize)
found[dist(_target, p->id)].push_back(p);
else
break;
}
head--;
}
else if (tail == s_tableSize - 1)
while (tail > 0 && count < s_bucketSize)
{
Guard l(x_state);
for (auto& n: m_state[tail].nodes)
if (auto p = n.lock())
{
if (count < s_bucketSize)
found[dist(_target, p->id)].push_back(p);
else
break;
}
tail--;
}
std::vector<std::shared_ptr<NodeEntry>> ret;
for (auto& nodes: found)
for (auto& n: nodes.second)
ret.push_back(n);
return std::move(ret);
}
void ping(bi::address _address, unsigned _port) const
{
PingNode p;
string ip = m_node.endpoint.udp.address().to_string();
p.ipAddress = asBytes(ip);
p.port = m_node.endpoint.udp.port();
// p.expiration;
p.seal(m_secret);
m_socketPtr->send(p);
}
void ping(NodeEntry* _n) const
{
if (_n && _n->endpoint.udp.address().is_v4())
ping(_n->endpoint.udp.address(), _n->endpoint.udp.port());
}
void evict(std::shared_ptr<NodeEntry> _leastSeen, std::shared_ptr<NodeEntry> _new)
{
if (!m_socketPtr->isOpen())
return;
Guard l(x_evictions);
m_evictions.push_back(EvictionTimeout(make_pair(_leastSeen->id,chrono::steady_clock::now()), _new->id));
if (m_evictions.size() == 1)
doCheckEvictions(boost::system::error_code());
m_evictions.push_back(EvictionTimeout(make_pair(_leastSeen->id,chrono::steady_clock::now()), _new->id));
ping(_leastSeen.get());
}
void noteNode(Public _pubk, bi::udp::endpoint _endpoint)
{
Address id = right160(sha3(_pubk));
std::shared_ptr<NodeEntry> node;
{
Guard l(x_nodes);
auto n = m_nodes.find(id);
if (n == m_nodes.end())
{
m_nodes[id] = std::shared_ptr<NodeEntry>(new NodeEntry(m_node, id, _pubk, _endpoint));
node = m_nodes[id];
}
else
node = n->second;
}
noteNode(node);
}
void noteNode(std::shared_ptr<NodeEntry> _n)
{
std::shared_ptr<NodeEntry> contested;
{
NodeBucket s = bucket(_n.get());
Guard l(x_state);
s.nodes.remove_if([&_n](std::weak_ptr<NodeEntry> n)
{
auto p = n.lock();
if (!p || p == _n)
return true;
return false;
});
if (s.nodes.size() >= s_bucketSize)
{
contested = s.nodes.front().lock();
if (!contested)
{
s.nodes.pop_front();
s.nodes.push_back(_n);
}
}
else
s.nodes.push_back(_n);
}
if (contested)
evict(contested, _n);
}
void dropNode(std::shared_ptr<NodeEntry> _n)
{
NodeBucket s = bucket(_n.get());
{
Guard l(x_state);
s.nodes.remove_if([&_n](std::weak_ptr<NodeEntry> n) { return n.lock() == _n; });
}
Guard l(x_nodes);
m_nodes.erase(_n->id);
}
NodeBucket const& bucket(NodeEntry* _n) const
{
return m_state[_n->distance];
}
void onReceived(UDPSocketFace*, bi::udp::endpoint const& _from, bytesConstRef _packet)
{
RLP rlp(_packet);
// whenever a pong is received, first check if it's in m_evictions, if so, remove it
Guard l(x_evictions);
}
void onDisconnected(UDPSocketFace*)
{
}
void doCheckEvictions(boost::system::error_code const& _ec)
{
if (_ec || !m_socketPtr->isOpen())
return;
m_evictionCheckTimer.expires_from_now(boost::posix_time::milliseconds(s_evictionCheckInterval));
auto self(shared_from_this());
m_evictionCheckTimer.async_wait([this, self](boost::system::error_code const& _ec)
{
if (_ec)
return;
bool evictionsRemain = false;
std::list<shared_ptr<NodeEntry>> drop;
{
Guard l(x_evictions);
for (auto& e: m_evictions)
if (chrono::steady_clock::now() - e.first.second > chrono::milliseconds(s_pingTimeout))
{
Guard l(x_nodes);
drop.push_back(m_nodes[e.second]);
}
evictionsRemain = m_evictions.size() - drop.size() > 0;
}
for (auto& n: drop)
dropNode(n);
if (evictionsRemain)
doCheckEvictions(boost::system::error_code());
});
}
void doRefreshBuckets(boost::system::error_code const& _ec)
{
cout << "refreshing buckets" << endl;
if (_ec)
return;
// first check if there are any pending evictions
bool connected = m_socketPtr->isOpen();
bool refreshed = false;
if (connected)
{
Guard l(x_state);
for (auto& d: m_state)
if (chrono::steady_clock::now() - d.modified > chrono::seconds(s_bucketRefresh))
while (!d.nodes.empty())
{
auto n = d.nodes.front();
if (auto p = n.lock())
{
refreshed = true;
ping(p.get());
break;
}
d.nodes.pop_front();
}
}
unsigned nextRefresh = connected ? (refreshed ? 200 : s_bucketRefresh*1000) : 10000;
auto runcb = [this](boost::system::error_code const& error) -> void { doRefreshBuckets(error); };
m_bucketRefreshTimer.expires_from_now(boost::posix_time::milliseconds(nextRefresh));
m_bucketRefreshTimer.async_wait(runcb);
}
private:
NodeEntry m_node; ///< This node.
Secret m_secret; ///< This nodes secret key.
mutable Mutex x_nodes; ///< Mutable for thread-safe copy in nodes() const.
std::map<Address, std::shared_ptr<NodeEntry>> m_nodes; ///< Address -> Node table (most common lookup path)
Mutex x_state;
std::array<NodeBucket, s_tableSize> m_state; ///< State table; logbinned nodes.
Mutex x_evictions;
std::deque<EvictionTimeout> m_evictions; ///< Eviction timeouts.
shared_ptr<nodeSocket> m_socket; ///< Shared pointer for our UDPSocket; ASIO requires shared_ptr.
nodeSocket* m_socketPtr; ///< Set to m_socket.get().
ba::io_service& m_io; ///< Used by bucket refresh timer.
boost::asio::deadline_timer m_bucketRefreshTimer; ///< Timer which schedules and enacts bucket refresh.
boost::asio::deadline_timer m_evictionCheckTimer; ///< Timer for handling node evictions.
};
/**
* Only used for testing. Not useful beyond tests.
*/