// Returns whether or not a peer is connected already
private bool IsPeerConnected(PeerCandidate Peer)
{
// Check whether the peer candidate is this node
if (Peer.Id == Id)
{
return(true);
}
// Lock peer list to prevent race conditions
lock (PeerList)
{
// Check if the connected peer list contains this peer
if (PeerList.Any(x => x.Id == Peer.Id))
{
return(true);
}
// Check if any incoming connections have this address + port
if (P2pServer.PendingConnections.Any(x => x.Client.RemoteEndPoint.ToString() == $"{Peer.Address}:{Peer.Port}"))
{
return(true);
}
}
// Peer is not connected
return(false);
}
// Adds a peer to the candidate list or updates an existing candidate
private void AddPeerCandidate(PeerCandidate Peer)
{
// Lock peer candidate list to prevent race conditions
lock (PeerCandidatesGreyList)
{
// Peer exists in the list already
if (PeerCandidatesGreyList.Any(x => x.Id == Peer.Id))
{
// Find peer in the list
var LocalPeer = PeerCandidatesGreyList.First(x => x.Id == Peer.Id);
// Update peer's last seen time
if (LocalPeer.LastSeen < Peer.LastSeen)
{
LocalPeer.LastSeen = Peer.LastSeen;
}
}
// Peer has not yet been added
else
{
// Add peer to the candidate list
PeerCandidatesGreyList.Add(Peer);
}
}
}
// Returns whether or not a peer is blacklisted
private bool IsPeerAllowed(PeerCandidate Peer)
{
// Lock list to prevent race conditions
lock (RecentlyTriedPeerCandidates)
{
// Return whether or not the recently tried peer list contains this peer
return(RecentlyTriedPeerCandidates.Contains(Peer.Id));
}
}
// Adds a peer to the list of recently tried peers
private void AddRecentlyTriedPeer(PeerCandidate Peer)
{
// Lock list to prevent race conditions
lock (RecentlyTriedPeerCandidates)
{
// Add the peer id to the list
RecentlyTriedPeerCandidates.Add(Peer.Id);
}
}
// Attempts to connect to a new peer on the peer candidate list
private void DiscoverNewPeer()
{
// Do nothing if not running
if (Stopped)
{
return;
}
// Check if discovery is enabled
if (!Globals.P2P_DISCOVERY_ENABLED)
{
return;
}
// Check if discovery is already active
if (DiscoveryActive)
{
return;
}
DiscoveryActive = true;
// Check if the peer list has space for a new peer
if (GetPeerCount() >= Globals.P2P_MAX_PEER_CONNECTIONS)
{
return;
}
// Get the peer candidate list
List <PeerCandidate> Candidates = GetPeerCandidates();
// Check if there are candidates in the list
if (Candidates.Count == 0)
{
return;
}
// Setup variables
int TryCount = 0;
int RandomCount = 0;
int MaxIndex = Math.Min(Candidates.Count - 1, 50);
List <int> TriedIndexes = new List <int>();
// Loop to try a selection of candidates
while (RandomCount < (MaxIndex + 1) * 3 && TryCount < 10 && !Stopped)
{
// Increment random count and get net random index
RandomCount++;
int RandomIndex = SecureRandom.Integer(0, MaxIndex + 1);
RandomIndex = (RandomIndex * RandomIndex * RandomIndex) / (MaxIndex * MaxIndex);
// Check if this index has been tried previously
if (TriedIndexes.Contains(RandomIndex))
{
continue;
}
// Add this index to the tried indexes list
TriedIndexes.Add(RandomIndex);
// Get the peer candidate
PeerCandidate Peer = Candidates[RandomIndex];
// Increment try count
TryCount++;
// Check if this peer is already connected
if (IsPeerConnected(Peer))
{
continue;
}
// TODO - check if we are allowing remote connections??
// Check if this peer has previously been blacklists
if (IsPeerAllowed(Peer))
{
return;
}
// Attempt to add this peer candidate
Logger.Debug($"[{TryCount}/10] Trying candidate #{RandomIndex} {Peer.Address}:{Peer.Port}, last seen {GetTimeDelta(Peer.LastSeen)} seconds ago");
if (!AddPeer(Peer.Address, (int)Peer.Port))
{
// Add to failed connection list
AddRecentlyTriedPeer(Peer);
}
}
// Discovery process finished
DiscoveryActive = false;
}
