private DhtRpcPacket Query(DhtRpcPacket query, NodeContact contact)
{
Stream s = null;
try
{
if (contact.IsCurrentNode)
{
return(ProcessQuery(query, contact.NodeEP));
}
s = _manager.GetConnection(contact.NodeEP);
//set timeout
s.WriteTimeout = _queryTimeout;
s.ReadTimeout = _queryTimeout;
//send query
query.WriteTo(new BinaryWriter(s));
s.Flush();
Debug.Write(this.GetType().Name, "query sent to: " + contact.ToString());
//read response
DhtRpcPacket response = new DhtRpcPacket(new BinaryReader(s));
Debug.Write(this.GetType().Name, "response received from: " + contact.ToString());
//auto add contact or update last seen time
{
NodeContact bucketContact = _routingTable.FindContact(contact.NodeId);
if (bucketContact == null)
{
contact.UpdateLastSeenTime();
_routingTable.AddContact(contact);
}
else
{
bucketContact.UpdateLastSeenTime();
}
}
return(response);
}
catch (Exception ex)
{
Debug.Write(this.GetType().Name, ex);
contact.IncrementRpcFailCount();
return(null);
}
finally
{
if (s != null)
{
s.Dispose();
}
}
}
private EndPoint[] QueryAnnounce(NodeContact[] initialContacts, BinaryNumber networkId, EndPoint serviceEP)
{
NodeContact[] contacts = QueryFindNode(initialContacts, networkId);
if ((contacts == null) || (contacts.Length == 0))
{
return(null);
}
List <EndPoint> peers = new List <EndPoint>();
lock (peers)
{
int respondedContacts = 0;
foreach (NodeContact contact in contacts)
{
ThreadPool.QueueUserWorkItem(delegate(object state)
{
DhtRpcPacket response = Query(DhtRpcPacket.CreateAnnouncePeerPacketQuery(_currentNode, networkId, serviceEP), contact);
if ((response != null) && (response.Type == DhtRpcType.ANNOUNCE_PEER) && (response.Peers.Length > 0))
{
lock (peers)
{
foreach (EndPoint peer in response.Peers)
{
if (!peers.Contains(peer))
{
peers.Add(peer);
}
}
respondedContacts++;
if (respondedContacts == contacts.Length)
{
Monitor.Pulse(peers);
}
}
}
});
}
if (Monitor.Wait(peers, _queryTimeout))
{
return(peers.ToArray());
}
return(null);
}
}
public void AddNode(NodeContact contact)
{
if (contact.NodeEP.AddressFamily != _currentNode.NodeEP.AddressFamily)
{
return;
}
if (_routingTable.AddContact(contact))
{
Debug.Write(this.GetType().Name, "node contact added: " + contact.ToString());
ThreadPool.QueueUserWorkItem(delegate(object state)
{
Query(DhtRpcPacket.CreatePingPacket(_currentNode), contact);
});
}
}
public void AcceptConnection(Stream s, EndPoint remoteNodeEP)
{
//set timeout
s.WriteTimeout = _queryTimeout;
s.ReadTimeout = _queryTimeout;
BinaryReader bR = new BinaryReader(s);
BinaryWriter bW = new BinaryWriter(s);
DhtRpcPacket response = ProcessQuery(new DhtRpcPacket(bR), remoteNodeEP);
if (response == null)
{
return;
}
response.WriteTo(bW);
s.Flush();
}
private object QueryFind(NodeContact[] initialContacts, BinaryNumber nodeId, DhtRpcType queryType)
{
if (initialContacts.Length < 1)
{
return(null);
}
List <NodeContact> seenContacts = new List <NodeContact>(initialContacts);
List <NodeContact> learnedNotQueriedContacts = new List <NodeContact>(initialContacts);
List <NodeContact> respondedContacts = new List <NodeContact>();
List <EndPoint> receivedPeers = null;
int alpha = KADEMLIA_ALPHA;
bool finalRound = false;
bool checkTerminationCondition = false;
if (queryType == DhtRpcType.FIND_PEERS)
{
receivedPeers = new List <EndPoint>();
}
NodeContact previousClosestSeenContact = KBucket.SelectClosestContacts(seenContacts, nodeId, 1)[0];
while (true)
{
NodeContact[] alphaContacts;
//pick alpha contacts to query from learned contacts
lock (learnedNotQueriedContacts)
{
alphaContacts = KBucket.SelectClosestContacts(learnedNotQueriedContacts, nodeId, alpha);
//remove selected alpha contacts from learned not queries contacts list
foreach (NodeContact alphaContact in alphaContacts)
{
learnedNotQueriedContacts.Remove(alphaContact);
}
}
if (alphaContacts.Length < 1)
{
checkTerminationCondition = true;
}
else
{
object lockObj = new object();
lock (lockObj)
{
int respondedAlphaContacts = 0;
//query each alpha contact async
foreach (NodeContact alphaContact in alphaContacts)
{
ThreadPool.QueueUserWorkItem(delegate(object state)
{
DhtRpcPacket response;
if (queryType == DhtRpcType.FIND_NODE)
{
response = Query(DhtRpcPacket.CreateFindNodePacketQuery(_currentNode, nodeId), alphaContact);
}
else
{
response = Query(DhtRpcPacket.CreateFindPeersPacketQuery(_currentNode, nodeId), alphaContact);
}
if ((response == null) || (response.Type != queryType))
{
//time out or error
//ignore contact by removing from seen contacts list
lock (seenContacts)
{
seenContacts.Remove(alphaContact);
}
}
else
{
//got reply!
if ((queryType == DhtRpcType.FIND_PEERS) && (response.Peers.Length > 0))
{
lock (receivedPeers)
{
foreach (EndPoint peer in response.Peers)
{
if (!receivedPeers.Contains(peer))
{
receivedPeers.Add(peer);
}
}
}
}
//add alpha contact to responded contacts list
lock (respondedContacts)
{
if (!respondedContacts.Contains(alphaContact))
{
respondedContacts.Add(alphaContact);
}
}
//add received contacts to learned contacts list
lock (seenContacts)
{
lock (learnedNotQueriedContacts)
{
foreach (NodeContact contact in response.Contacts)
{
if (!seenContacts.Contains(contact))
{
seenContacts.Add(contact);
learnedNotQueriedContacts.Add(contact);
}
}
}
}
}
//wait for all alpha contacts to respond and signal only when all contacts responded
lock (lockObj)
{
respondedAlphaContacts++;
if (respondedAlphaContacts == alphaContacts.Length)
{
Monitor.Pulse(lockObj);
}
}
});
}
//wait for any of the node contact to return new contacts
if (Monitor.Wait(lockObj, _queryTimeout))
{
//got reply or final round!
NodeContact currentClosestSeenContact;
lock (seenContacts)
{
currentClosestSeenContact = KBucket.SelectClosestContacts(seenContacts, nodeId, 1)[0];
}
BinaryNumber previousDistance = nodeId ^ previousClosestSeenContact.NodeId;
BinaryNumber currentDistance = nodeId ^ currentClosestSeenContact.NodeId;
if (previousDistance <= currentDistance)
{
//current round failed to return a node contact any closer than the closest already seen
if (finalRound)
{
//final round over, check for termination condition
checkTerminationCondition = true;
}
else
{
//resend query to k closest node not already queried
finalRound = true;
alpha = KADEMLIA_K;
}
}
else
{
//current closest seen contact is closer than previous closest seen contact
previousClosestSeenContact = currentClosestSeenContact;
finalRound = false;
alpha = KADEMLIA_ALPHA;
}
}
}
}
if (checkTerminationCondition)
{
checkTerminationCondition = false; //reset
if (queryType == DhtRpcType.FIND_PEERS)
{
//check only in final round to get most peers
lock (receivedPeers)
{
if (receivedPeers.Count > 0)
{
return(receivedPeers.ToArray());
}
return(null);
}
}
//lookup terminates when k closest seen contacts have responded
NodeContact[] kClosestSeenContacts;
lock (seenContacts)
{
kClosestSeenContacts = KBucket.SelectClosestContacts(seenContacts, nodeId, KADEMLIA_K);
}
lock (respondedContacts)
{
bool success = true;
foreach (NodeContact contact in kClosestSeenContacts)
{
if (!respondedContacts.Contains(contact))
{
success = false;
break;
}
}
if (success)
{
return(kClosestSeenContacts);
}
if (alphaContacts.Length < 1)
{
return(KBucket.SelectClosestContacts(respondedContacts, nodeId, KADEMLIA_K));
}
}
}
}
}
internal bool Ping(NodeContact contact)
{
DhtRpcPacket response = Query(DhtRpcPacket.CreatePingPacket(_currentNode), contact);
return(response != null);
}
private DhtRpcPacket ProcessQuery(DhtRpcPacket query, EndPoint remoteNodeEP)
{
//in case of remote node querying via Tor, remoteNodeEP.Address will be loopback IP. Use the onion address from the query as remote end point
if (!_currentNode.NodeEP.Equals(remoteNodeEP))
{
switch (remoteNodeEP.AddressFamily)
{
case AddressFamily.InterNetwork:
case AddressFamily.InterNetworkV6:
IPAddress remoteNodeAddress = (remoteNodeEP as IPEndPoint).Address;
if (IPAddress.IsLoopback(remoteNodeAddress) && (query.SourceNodeEP.AddressFamily == AddressFamily.Unspecified) && (query.SourceNodeEP as DomainEndPoint).Address.EndsWith(".onion", StringComparison.OrdinalIgnoreCase))
{
AddNode(query.SourceNodeEP); //use the tor hidden end point claimed by remote node
}
else
{
AddNode(new IPEndPoint(remoteNodeAddress, query.SourceNodeEP.GetPort())); //use remote node end point as seen by connection manager and use port from query
}
break;
default:
throw new NotSupportedException();
}
}
Debug.Write(this.GetType().Name, "query received from: " + remoteNodeEP.ToString() + "; type: " + query.Type.ToString());
//process query
switch (query.Type)
{
case DhtRpcType.PING:
return(DhtRpcPacket.CreatePingPacket(_currentNode));
case DhtRpcType.FIND_NODE:
return(DhtRpcPacket.CreateFindNodePacketResponse(_currentNode, query.NetworkId, _routingTable.GetKClosestContacts(query.NetworkId, false)));
case DhtRpcType.FIND_PEERS:
EndPoint[] peers = _currentNode.GetPeers(query.NetworkId);
if (peers.Length == 0)
{
return(DhtRpcPacket.CreateFindPeersPacketResponse(_currentNode, query.NetworkId, _routingTable.GetKClosestContacts(query.NetworkId, false), peers));
}
else
{
return(DhtRpcPacket.CreateFindPeersPacketResponse(_currentNode, query.NetworkId, new NodeContact[] { }, peers));
}
case DhtRpcType.ANNOUNCE_PEER:
if ((query.Peers != null) && (query.Peers.Length > 0))
{
EndPoint peerEP;
if (query.Peers[0].AddressFamily == AddressFamily.Unspecified)
{
peerEP = query.Peers[0];
}
else
{
peerEP = new IPEndPoint((remoteNodeEP as IPEndPoint).Address, query.Peers[0].GetPort());
}
_currentNode.StorePeer(query.NetworkId, peerEP);
}
return(DhtRpcPacket.CreateAnnouncePeerPacketResponse(_currentNode, query.NetworkId, _currentNode.GetPeers(query.NetworkId)));
default:
throw new Exception("Invalid DHT-RPC type.");
}
}