public static NodeContact[] SelectClosestContacts(ICollection <NodeContact> contacts, BinaryNumber nodeID, int count)
{
if (contacts.Count < count)
{
count = contacts.Count;
}
NodeContact[] closestContacts = new NodeContact[count];
BinaryNumber[] closestContactDistances = new BinaryNumber[count];
foreach (NodeContact contact in contacts)
{
BinaryNumber distance = nodeID ^ contact.NodeId;
for (int i = 0; i < count; i++)
{
if ((closestContactDistances[i] == null) || (distance < closestContactDistances[i]))
{
//demote existing values
for (int j = count - 1; j > i; j--)
{
closestContactDistances[j] = closestContactDistances[j - 1];
closestContacts[j] = closestContacts[j - 1];
}
//place current on top
closestContactDistances[i] = distance;
closestContacts[i] = contact;
break;
}
}
}
return(closestContacts);
}
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();
}
}
}
public override bool Equals(object obj)
{
if (obj is null)
{
return(false);
}
if (ReferenceEquals(this, obj))
{
return(true);
}
NodeContact contact = obj as NodeContact;
if (contact == null)
{
return(false);
}
if (_nodeEP.Equals(contact._nodeEP))
{
return(true);
}
return(_nodeId.Equals(contact._nodeId));
}
public KBucket(NodeContact currentNode)
{
_bucketDepth = 0;
_contacts = new NodeContact[DhtNode.KADEMLIA_K * 2];
_contacts[0] = currentNode;
_contactCount = 1;
_lastChanged = DateTime.UtcNow;
}
private static void SplitBucket(KBucket bucket, NodeContact newContact)
{
if (bucket._contacts == null)
{
return;
}
KBucket leftBucket = new KBucket(bucket, true);
KBucket rightBucket = new KBucket(bucket, false);
foreach (NodeContact contact in bucket._contacts)
{
if (contact != null)
{
if ((leftBucket._bucketID & contact.NodeId) == leftBucket._bucketID)
{
leftBucket._contacts[leftBucket._contactCount++] = contact;
}
else
{
rightBucket._contacts[rightBucket._contactCount++] = contact;
}
}
}
KBucket selectedBucket;
if ((leftBucket._bucketID & newContact.NodeId) == leftBucket._bucketID)
{
selectedBucket = leftBucket;
}
else
{
selectedBucket = rightBucket;
}
if (selectedBucket._contactCount == selectedBucket._contacts.Length)
{
SplitBucket(selectedBucket, newContact);
selectedBucket._contactCount++;
}
else
{
selectedBucket._contacts[selectedBucket._contactCount++] = newContact;
}
bucket._contacts = null;
bucket._leftBucket = leftBucket;
bucket._rightBucket = rightBucket;
}
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 static DhtRpcPacket CreateAnnouncePeerPacketResponse(NodeContact sourceNode, BinaryNumber networkId, EndPoint[] peers)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.ANNOUNCE_PEER, networkId, null, peers));
}
public DhtRpcPacket(BinaryReader bR)
{
int version = bR.ReadByte();
switch (version)
{
case 1:
_sourceNodeEP = EndPointExtension.Parse(bR);
_type = (DhtRpcType)bR.ReadByte();
switch (_type)
{
case DhtRpcType.PING:
break;
case DhtRpcType.FIND_NODE:
_networkId = new BinaryNumber(bR.BaseStream);
_contacts = new NodeContact[bR.ReadByte()];
for (int i = 0; i < _contacts.Length; i++)
{
_contacts[i] = new NodeContact(bR);
}
break;
case DhtRpcType.FIND_PEERS:
_networkId = new BinaryNumber(bR.BaseStream);
_contacts = new NodeContact[bR.ReadByte()];
for (int i = 0; i < _contacts.Length; i++)
{
_contacts[i] = new NodeContact(bR);
}
_peers = new EndPoint[bR.ReadByte()];
for (int i = 0; i < _peers.Length; i++)
{
_peers[i] = EndPointExtension.Parse(bR);
}
break;
case DhtRpcType.ANNOUNCE_PEER:
_networkId = new BinaryNumber(bR.BaseStream);
_peers = new EndPoint[bR.ReadByte()];
for (int i = 0; i < _peers.Length; i++)
{
_peers[i] = EndPointExtension.Parse(bR);
}
break;
default:
throw new IOException("Invalid DHT-RPC type.");
}
break;
default:
throw new InvalidDataException("DHT-RPC packet version not supported: " + version);
}
}
public static DhtRpcPacket CreateFindPeersPacketResponse(NodeContact sourceNode, BinaryNumber networkId, NodeContact[] contacts, EndPoint[] peers)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.FIND_PEERS, networkId, contacts, peers));
}
public static DhtRpcPacket CreateAnnouncePeerPacketQuery(NodeContact sourceNode, BinaryNumber networkId, EndPoint serviceEP)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.ANNOUNCE_PEER, networkId, null, new EndPoint[] { serviceEP }));
}
public static DhtRpcPacket CreateFindNodePacketResponse(NodeContact sourceNode, BinaryNumber networkId, NodeContact[] contacts)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.FIND_NODE, networkId, contacts, null));
}
public static DhtRpcPacket CreateFindPeersPacketQuery(NodeContact sourceNode, BinaryNumber networkId)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.FIND_PEERS, networkId, null, null));
}
public static DhtRpcPacket CreatePingPacket(NodeContact sourceNode)
{
return(new DhtRpcPacket(sourceNode.NodeEP, DhtRpcType.PING, null, null, null));
}
public bool RemoveStaleContact(NodeContact contact)
{
KBucket currentBucket = this;
while (true)
{
NodeContact[] contacts;
KBucket leftBucket;
KBucket rightBucket;
lock (currentBucket)
{
contacts = currentBucket._contacts;
leftBucket = currentBucket._leftBucket;
rightBucket = currentBucket._rightBucket;
if (contacts != null)
{
#region remove contact from this bucket
if (currentBucket._contactCount <= DhtNode.KADEMLIA_K)
{
return(false); //k-bucket is not full and replacement cache is empty
}
//check if there is more deserving contact to be removed than the current one
foreach (NodeContact testContact in contacts)
{
if ((testContact != null) && testContact.IsStale() && (contact.SuccessfulRpcCount > testContact.SuccessfulRpcCount))
{
//set test contact for removal
contact = testContact;
break;
}
}
for (int i = 0; i < contacts.Length; i++)
{
if (contact.Equals(contacts[i]))
{
if (contacts[i].IsStale())
{
//remove stale contact
contacts[i] = null;
currentBucket._lastChanged = DateTime.UtcNow;
KBucket bucket = currentBucket;
do
{
Interlocked.Decrement(ref bucket._contactCount);
bucket = bucket._parentBucket;
}while (bucket != null);
return(true);
}
break;
}
}
return(false); //contact was not found or was not stale
#endregion
}
}
if ((leftBucket._bucketID & contact.NodeId) == leftBucket._bucketID)
{
currentBucket = leftBucket;
}
else
{
currentBucket = rightBucket;
}
}
}
public bool AddContact(NodeContact contact)
{
KBucket currentBucket = this;
while (true)
{
NodeContact[] contacts;
KBucket leftBucket;
KBucket rightBucket;
lock (currentBucket)
{
contacts = currentBucket._contacts;
leftBucket = currentBucket._leftBucket;
rightBucket = currentBucket._rightBucket;
if (contacts != null)
{
#region add contact in this bucket
//search if contact already exists
for (int i = 0; i < contacts.Length; i++)
{
if (contact.Equals(contacts[i]))
{
return(false); //contact already exists
}
}
//try add contact
for (int i = 0; i < contacts.Length; i++)
{
if (contacts[i] == null)
{
contacts[i] = contact;
currentBucket._lastChanged = DateTime.UtcNow;
KBucket bucket = currentBucket;
do
{
Interlocked.Increment(ref bucket._contactCount);
bucket = bucket._parentBucket;
}while (bucket != null);
return(true);
}
}
//k-bucket is full so contact was not added
//if current contact is not stale then find and replace with any existing stale contact
if (!contact.IsStale())
{
for (int i = 0; i < contacts.Length; i++)
{
if (contacts[i].IsStale())
{
contacts[i] = contact;
currentBucket._lastChanged = DateTime.UtcNow;
KBucket bucket = currentBucket;
do
{
Interlocked.Increment(ref bucket._contactCount);
bucket = bucket._parentBucket;
}while (bucket != null);
return(true);
}
}
}
//no stale contact in this k-bucket to replace!
if (contacts[0].IsCurrentNode || (currentBucket._bucketDepth < (DhtNode.KADEMLIA_B - 1)))
{
//split current bucket and add contact!
SplitBucket(currentBucket, contact);
KBucket bucket = currentBucket;
do
{
Interlocked.Increment(ref bucket._contactCount);
bucket = bucket._parentBucket;
}while (bucket != null);
return(true);
}
//k-bucket is full!
return(false);
#endregion
}
}
if ((leftBucket._bucketID & contact.NodeId) == leftBucket._bucketID)
{
currentBucket = leftBucket;
}
else
{
currentBucket = rightBucket;
}
}
}
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);
}