// encrypts a packet and sends it to the endpoint
private void sendPacketToClient(NetcodePacketHeader packetHeader, byte[] packetData, int packetDataLen, EndPoint endpoint, byte[] key)
{
// assign a sequence number to this packet
packetHeader.SequenceNumber = this.nextSequenceNumber++;
// encrypt packet data
byte[] encryptedPacketBuffer = BufferPool.GetBuffer(2048);
int encryptedBytes = PacketIO.EncryptPacketData(packetHeader, protocolID, packetData, packetDataLen, key, encryptedPacketBuffer);
int packetLen = 0;
// write packet to byte array
var packetBuffer = BufferPool.GetBuffer(2048);
using (var packetWriter = ByteArrayReaderWriter.Get(packetBuffer))
{
packetHeader.Write(packetWriter);
packetWriter.WriteBuffer(encryptedPacketBuffer, encryptedBytes);
packetLen = (int)packetWriter.WritePosition;
}
// send packet
listenSocket.SendTo(packetBuffer, packetLen, endpoint);
BufferPool.ReturnBuffer(packetBuffer);
BufferPool.ReturnBuffer(encryptedPacketBuffer);
}
private void processConnectionKeepAlive(NetcodePacketHeader header, int length, ByteArrayReaderWriter stream)
{
if (checkReplay(header))
{
return;
}
var decryptKey = serverToClientKey;
var keepAlive = new NetcodeKeepAlivePacket()
{
Header = header
};
if (!keepAlive.Read(stream, length, decryptKey, connectToken.ProtocolID))
{
return;
}
if (this.state == ClientState.Connected || this.state == ClientState.SendingChallengeResponse)
{
lastResponseTime = time;
}
if (this.state == ClientState.SendingChallengeResponse)
{
this.clientIndex = keepAlive.ClientIndex;
this.maxSlots = keepAlive.MaxSlots;
changeState(ClientState.Connected);
}
}
private void processConnectionPayload(NetcodePacketHeader header, int length, ByteArrayReaderWriter stream)
{
if (checkReplay(header))
{
return;
}
if (this.state != ClientState.Connected)
{
return;
}
var decryptKey = serverToClientKey;
var payloadPacket = new NetcodePayloadPacket()
{
Header = header
};
if (!payloadPacket.Read(stream, length, decryptKey, connectToken.ProtocolID))
{
return;
}
lastResponseTime = time;
if (OnMessageReceived != null)
{
OnMessageReceived(payloadPacket.Payload, payloadPacket.Length);
}
payloadPacket.Release();
}
private void serializePacket(NetcodePacketHeader packetHeader, Action <ByteArrayReaderWriter> write, EndPoint endpoint, byte[] key)
{
byte[] tempPacket = BufferPool.GetBuffer(2048);
int writeLen = 0;
using (var writer = ByteArrayReaderWriter.Get(tempPacket))
{
write(writer);
writeLen = (int)writer.WritePosition;
}
sendPacketToClient(packetHeader, tempPacket, writeLen, endpoint, key);
BufferPool.ReturnBuffer(tempPacket);
}
private void processConnectionDenied(NetcodePacketHeader header, int length, ByteArrayReaderWriter stream)
{
var decryptKey = serverToClientKey;
var denyPacket = new NetcodeDenyConnectionPacket()
{
Header = header
};
if (!denyPacket.Read(stream, length, decryptKey, connectToken.ProtocolID))
{
return;
}
pendingDisconnectState = ClientState.ConnectionDenied;
// move onto the next server
timer = 0.0;
connectionTimer = 0.0;
connectionMoveNextEndpoint();
}
// check the packet against the client's replay protection, returning true if packet was replayed, false otherwise
private bool checkReplay(NetcodePacketHeader header, EndPoint sender)
{
var cryptIdx = encryptionManager.FindEncryptionMapping(sender, time);
if (cryptIdx == -1)
{
log("Replay protection failed to find encryption mapping", NetcodeLogLevel.Debug);
return(true);
}
var clientIndex = encryptionManager.GetClientID(cryptIdx);
var client = clientSlots[clientIndex];
if (client == null)
{
log("Replay protection failed to find client", NetcodeLogLevel.Debug);
return(true);
}
return(client.replayProtection.AlreadyReceived(header.SequenceNumber));
}
// process an incoming payload
private void processConnectionPayload(ByteArrayReaderWriter reader, NetcodePacketHeader header, int size, EndPoint sender)
{
if (checkReplay(header, sender))
{
return;
}
// encryption mapping was not registered, so don't bother
int cryptIdx = encryptionManager.FindEncryptionMapping(sender, time);
if (cryptIdx == -1)
{
log("No crytpo key for sender", NetcodeLogLevel.Debug);
return;
}
// grab the decryption key and decrypt the packet
var decryptKey = encryptionManager.GetReceiveKey(cryptIdx);
var payloadPacket = new NetcodePayloadPacket()
{
Header = header
};
if (!payloadPacket.Read(reader, size - (int)reader.ReadPosition, decryptKey, protocolID))
{
return;
}
var clientIndex = encryptionManager.GetClientID(cryptIdx);
var client = clientSlots[clientIndex];
// trigger callback
if (OnClientMessageReceived != null)
{
OnClientMessageReceived(client, payloadPacket.Payload, payloadPacket.Length);
}
payloadPacket.Release();
}
// process a received datagram
private void processDatagram(byte[] payload, int size, EndPoint sender)
{
using (var reader = ByteArrayReaderWriter.Get(payload))
{
NetcodePacketHeader packetHeader = new NetcodePacketHeader();
packetHeader.Read(reader);
if (packetHeader.PacketType == NetcodePacketType.ConnectionRequest)
{
if (!debugIgnoreConnectionRequest)
{
processConnectionRequest(reader, size, sender);
}
}
else
{
switch (packetHeader.PacketType)
{
case NetcodePacketType.ChallengeResponse:
if (!debugIgnoreChallengeResponse)
{
processConnectionResponse(reader, packetHeader, size, sender);
}
break;
case NetcodePacketType.ConnectionKeepAlive:
processConnectionKeepAlive(reader, packetHeader, size, sender);
break;
case NetcodePacketType.ConnectionPayload:
processConnectionPayload(reader, packetHeader, size, sender);
break;
case NetcodePacketType.ConnectionDisconnect:
processConnectionDisconnect(reader, packetHeader, size, sender);
break;
}
}
}
}
private void processDatagram(Datagram datagram)
{
if (!MiscUtils.AddressEqual(datagram.sender, currentServerEndpoint))
{
return;
}
using (var reader = ByteArrayReaderWriter.Get(datagram.payload))
{
NetcodePacketHeader packetHeader = new NetcodePacketHeader();
packetHeader.Read(reader);
int length = datagram.payloadSize - (int)reader.ReadPosition;
switch (packetHeader.PacketType)
{
case NetcodePacketType.ConnectionChallenge:
processChallengePacket(packetHeader, length, reader);
break;
case NetcodePacketType.ConnectionDenied:
processConnectionDenied(packetHeader, length, reader);
break;
case NetcodePacketType.ConnectionKeepAlive:
processConnectionKeepAlive(packetHeader, length, reader);
break;
case NetcodePacketType.ConnectionPayload:
processConnectionPayload(packetHeader, length, reader);
break;
case NetcodePacketType.ConnectionDisconnect:
processConnectionDisconnect(packetHeader, length, reader);
break;
}
}
}
private void processChallengePacket(NetcodePacketHeader header, int length, ByteArrayReaderWriter stream)
{
var decryptKey = serverToClientKey;
var challengePacket = new NetcodeConnectionChallengeResponsePacket()
{
Header = header
};
if (!challengePacket.Read(stream, length, decryptKey, connectToken.ProtocolID))
{
return;
}
if (state == ClientState.SendingConnectionRequest)
{
this.challengeResponse = challengePacket;
this.challengeResponse.Header.PacketType = NetcodePacketType.ChallengeResponse;
// move onto sending challenge response
timer = 0.0;
connectionTimer = 0.0;
changeState(ClientState.SendingChallengeResponse);
}
}
private void processConnectionDisconnect(NetcodePacketHeader header, int length, ByteArrayReaderWriter stream)
{
if (checkReplay(header))
{
return;
}
if (this.state != ClientState.Connected)
{
return;
}
var decryptKey = serverToClientKey;
var disconnectPacket = new NetcodeDisconnectPacket()
{
Header = header
};
if (!disconnectPacket.Read(stream, length, decryptKey, connectToken.ProtocolID))
{
return;
}
Disconnect();
}
// process an incoming connection response packet
private void processConnectionResponse(ByteArrayReaderWriter reader, NetcodePacketHeader header, int size, EndPoint sender)
{
log("Got connection response", NetcodeLogLevel.Debug);
// encryption mapping was not registered, so don't bother
int cryptIdx = encryptionManager.FindEncryptionMapping(sender, time);
if (cryptIdx == -1)
{
log("No crytpo key for sender", NetcodeLogLevel.Debug);
return;
}
// grab the decryption key and decrypt the packet
var decryptKey = encryptionManager.GetReceiveKey(cryptIdx);
var connectionResponsePacket = new NetcodeConnectionChallengeResponsePacket()
{
Header = header
};
if (!connectionResponsePacket.Read(reader, size - (int)reader.ReadPosition, decryptKey, protocolID))
{
log("Failed to decrypt packet", NetcodeLogLevel.Debug);
return;
}
var challengeToken = new NetcodeChallengeToken();
if (!challengeToken.Read(connectionResponsePacket.ChallengeTokenBytes, connectionResponsePacket.ChallengeTokenSequence, challengeKey))
{
log("Failed to read challenge token", NetcodeLogLevel.Debug);
connectionResponsePacket.Release();
return;
}
// if a client from packet source IP / port is already connected, ignore the packet
if (clientSlots.Any(x => x != null && x.RemoteEndpoint.Equals(sender)))
{
log("Client {0} already connected", NetcodeLogLevel.Debug, sender.ToString());
return;
}
// if a client with the same id is already connected, ignore the packet
if (clientSlots.Any(x => x != null && x.ClientID == challengeToken.ClientID))
{
log("Client ID {0} already connected", NetcodeLogLevel.Debug, challengeToken.ClientID);
return;
}
// if the server is full, deny the connection
int nextSlot = getFreeClientSlot();
if (nextSlot == -1)
{
log("Server full, denying connection", NetcodeLogLevel.Info);
denyConnection(sender, encryptionManager.GetSendKey(cryptIdx));
return;
}
// assign the endpoint and client ID to a free client slot and set connected to true
RemoteClient client = new RemoteClient(this);
client.ClientID = challengeToken.ClientID;
client.RemoteEndpoint = sender;
client.Connected = true;
client.replayProtection = new NetcodeReplayProtection();
// assign timeout to client
client.timeoutSeconds = encryptionManager.GetTimeoutSeconds(cryptIdx);
// assign client to a free slot
client.ClientIndex = (uint)nextSlot;
this.clientSlots[nextSlot] = client;
encryptionManager.SetClientID(cryptIdx, client.ClientIndex);
// copy user data so application can make use of it, and set confirmed to false
client.UserData = challengeToken.UserData;
client.Confirmed = false;
client.Touch(time);
// respond with a connection keep alive packet
sendKeepAlive(client);
}
// process an incoming connection keep alive packet
private void processConnectionKeepAlive(ByteArrayReaderWriter reader, NetcodePacketHeader header, int size, EndPoint sender)
{
if (checkReplay(header, sender))
{
log("Detected replay in keep-alive", NetcodeLogLevel.Debug);
return;
}
// encryption mapping was not registered, so don't bother
int cryptIdx = encryptionManager.FindEncryptionMapping(sender, time);
if (cryptIdx == -1)
{
log("No crytpo key for sender", NetcodeLogLevel.Debug);
return;
}
// grab the decryption key and decrypt the packet
var decryptKey = encryptionManager.GetReceiveKey(cryptIdx);
var keepAlivePacket = new NetcodeKeepAlivePacket()
{
Header = header
};
if (!keepAlivePacket.Read(reader, size - (int)reader.ReadPosition, decryptKey, protocolID))
{
log("Failed to decrypt", NetcodeLogLevel.Debug);
return;
}
if (keepAlivePacket.ClientIndex >= maxSlots)
{
log("Invalid client index", NetcodeLogLevel.Debug);
return;
}
var client = this.clientSlots[(int)keepAlivePacket.ClientIndex];
if (client == null)
{
log("Failed to find client for endpoint", NetcodeLogLevel.Debug);
return;
}
if (!client.RemoteEndpoint.Equals(sender))
{
log("Client does not match sender", NetcodeLogLevel.Debug);
return;
}
if (!client.Confirmed)
{
// trigger callback
if (OnClientConnected != null)
{
OnClientConnected(client);
}
log("Client {0} connected", NetcodeLogLevel.Info, client.RemoteEndpoint);
}
client.Confirmed = true;
client.Touch(time);
int idx = encryptionManager.FindEncryptionMapping(client.RemoteEndpoint, time);
encryptionManager.Touch(idx, client.RemoteEndpoint, time);
}
// process an incoming disconnect message
private void processConnectionDisconnect(ByteArrayReaderWriter reader, NetcodePacketHeader header, int size, EndPoint sender)
{
if (checkReplay(header, sender))
{
return;
}
// encryption mapping was not registered, so don't bother
int cryptIdx = encryptionManager.FindEncryptionMapping(sender, time);
if (cryptIdx == -1)
{
log("No crytpo key for sender", NetcodeLogLevel.Debug);
return;
}
var decryptKey = encryptionManager.GetReceiveKey(cryptIdx);
var disconnectPacket = new NetcodeDisconnectPacket()
{
Header = header
};
if (!disconnectPacket.Read(reader, size - (int)reader.ReadPosition, decryptKey, protocolID))
{
return;
}
// locate the client by endpoint and free their slot
var clientIndex = encryptionManager.GetClientID(cryptIdx);
var client = clientSlots[clientIndex];
if (client == null)
{
return;
}
clientSlots[clientIndex] = null;
// remove encryption mapping
encryptionManager.RemoveEncryptionMapping(sender, time);
// make sure all other clients still have their encryption mappings
foreach (RemoteClient otherClient in clientSlots)
{
if (otherClient == null)
{
continue;
}
if (encryptionManager.FindEncryptionMapping(otherClient.RemoteEndpoint, time) == -1)
{
log("Encryption mapping removed wrong mapping!", NetcodeLogLevel.Debug);
}
}
// trigger client disconnect callback
if (OnClientDisconnected != null)
{
OnClientDisconnected(client);
}
log("Client {0} disconnected", NetcodeLogLevel.Info, client.RemoteEndpoint);
}
private bool checkReplay(NetcodePacketHeader packetHeader)
{
return(replayProtection.AlreadyReceived(packetHeader.SequenceNumber));
}