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Copy pathServer.cs
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1061 lines (849 loc) · 30.3 KB
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using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using NetcodeIO.NET.Utils;
using NetcodeIO.NET.Utils.IO;
using NetcodeIO.NET.Internal;
namespace NetcodeIO.NET
{
/// <summary>
/// Represents a remote client connected to a server
/// </summary>
public class RemoteClient
{
/// <summary>
/// The unique ID of the client as assigned by the token server
/// </summary>
public ulong ClientID;
/// <summary>
/// The index as assigned by the server
/// </summary>
public uint ClientIndex;
/// <summary>
/// The remote endpoint of the client
/// </summary>
public EndPoint RemoteEndpoint;
/// <summary>
/// 256 bytes of arbitrary user data
/// </summary>
public byte[] UserData;
internal bool Connected;
internal bool Confirmed;
internal NetcodeReplayProtection replayProtection;
internal Server server;
internal double lastResponseTime;
internal int timeoutSeconds;
public RemoteClient(Server server)
{
this.server = server;
}
/// <summary>
/// Send a payload to this client
/// </summary>
public void SendPayload(byte[] payload, int payloadSize)
{
server.SendPayload(this, payload, payloadSize);
}
internal void Touch(double time)
{
lastResponseTime = time;
}
}
/// <summary>
/// Event handler for when a client connects to the server
/// </summary>
public delegate void RemoteClientConnectedEventHandler(RemoteClient client);
/// <summary>
/// Event handler for when a client disconnects from the server
/// </summary>
public delegate void RemoteClientDisconnectedEventHandler(RemoteClient client);
/// <summary>
/// Event handler for when payload packets are received from a connected client
/// </summary>
public delegate void RemoteClientMessageReceivedEventHandler(RemoteClient sender, byte[] payload, int payloadSize);
/// <summary>
/// Class for starting a Netcode.IO server and accepting connections from remote clients
/// </summary>
public sealed class Server
{
#region embedded types
private struct usedConnectToken
{
public byte[] mac;
public EndPoint endpoint;
public double time;
}
#endregion
#region Public fields/properties
/// <summary>
/// Event triggered when a remote client connects
/// </summary>
public event RemoteClientConnectedEventHandler OnClientConnected;
/// <summary>
/// Event triggered when a remote client disconnects
/// </summary>
public event RemoteClientDisconnectedEventHandler OnClientDisconnected;
/// <summary>
/// Event triggered when a payload is received from a remote client
/// </summary>
public event RemoteClientMessageReceivedEventHandler OnClientMessageReceived;
/// <summary>
/// Log level for messages
/// </summary>
public NetcodeLogLevel LogLevel = NetcodeLogLevel.Error;
/// <summary>
/// Gets the port this server is listening on (or -1 if not listening)
/// </summary>
public int Port
{
get
{
if (listenSocket == null)
return -1;
return listenSocket.BoundPort;
}
}
/// <summary>
/// Gets or sets the internal tickrate of the server in ticks per second. Value must be between 1 and 1000.
/// </summary>
public int Tickrate
{
get { return tickrate; }
set
{
if (value < 1 || value > 1000) throw new ArgumentOutOfRangeException();
tickrate = value;
}
}
/// <summary>
/// Gets the current number of connected clients
/// </summary>
public int NumConnectedClients
{
get
{
int connectedClients = 0;
for (int i = 0; i < clientSlots.Length; i++)
if (clientSlots[i] != null && clientSlots[i].Confirmed) connectedClients++;
return connectedClients;
}
}
#endregion
#region Private fields
internal bool debugIgnoreConnectionRequest = false;
internal bool debugIgnoreChallengeResponse = false;
private ISocketContext listenSocket;
private IPEndPoint listenEndpoint;
private bool isRunning = false;
private ulong protocolID;
private RemoteClient[] clientSlots;
private int maxSlots;
private usedConnectToken[] connectTokenHistory;
private int maxConnectTokenEntries;
private ulong nextSequenceNumber = 0;
private ulong nextChallengeSequenceNumber = 0;
private byte[] privateKey;
private byte[] challengeKey;
private EncryptionManager encryptionManager;
private int tickrate;
internal double time;
private bool disposed = false;
#endregion
public Server(int maxSlots, string address, int port, ulong protocolID, byte[] privateKey)
{
this.tickrate = 60;
this.maxSlots = maxSlots;
this.maxConnectTokenEntries = this.maxSlots * 8;
this.connectTokenHistory = new usedConnectToken[this.maxConnectTokenEntries];
initConnectTokenHistory();
this.clientSlots = new RemoteClient[maxSlots];
this.encryptionManager = new EncryptionManager(maxSlots);
this.listenEndpoint = new IPEndPoint(IPAddress.Parse(address), port);
if (this.listenEndpoint.AddressFamily == AddressFamily.InterNetwork)
this.listenSocket = new UDPSocketContext(AddressFamily.InterNetwork);
else
this.listenSocket = new UDPSocketContext(AddressFamily.InterNetworkV6);
this.protocolID = protocolID;
this.privateKey = privateKey;
// generate a random challenge key
this.challengeKey = new byte[32];
KeyUtils.GenerateKey(this.challengeKey);
}
internal Server(ISocketContext socketContext, int maxSlots, string address, int port, ulong protocolID, byte[] privateKey)
{
this.tickrate = 60;
this.time = 0.0;
this.maxSlots = maxSlots;
this.maxConnectTokenEntries = this.maxSlots * 8;
this.connectTokenHistory = new usedConnectToken[this.maxConnectTokenEntries];
initConnectTokenHistory();
this.clientSlots = new RemoteClient[maxSlots];
this.encryptionManager = new EncryptionManager(maxSlots);
this.listenEndpoint = new IPEndPoint(IPAddress.Parse(address), port);
this.listenSocket = socketContext;
this.protocolID = protocolID;
this.privateKey = privateKey;
// generate a random challenge key
this.challengeKey = new byte[32];
KeyUtils.GenerateKey(this.challengeKey);
}
#region Public Methods
/// <summary>
/// Start the server and listen for incoming connections
/// </summary>
public void Start()
{
Start(true);
}
public void Start(bool autoTick)
{
if (disposed) throw new InvalidOperationException("Can't restart disposed server, please create a new server");
resetConnectTokenHistory();
this.listenSocket.Bind(this.listenEndpoint);
isRunning = true;
this.time = DateTime.Now.GetTotalSeconds();
if (autoTick)
{
ThreadPool.QueueUserWorkItem(serverTick);
}
}
/// <summary>
/// Stop the server and disconnect any clients
/// </summary>
public void Stop()
{
disposed = true;
disconnectAll();
isRunning = false;
this.listenSocket.Close();
if (OnClientConnected != null)
{
foreach (var receiver in OnClientConnected.GetInvocationList())
OnClientConnected -= (RemoteClientConnectedEventHandler)receiver;
}
if (OnClientDisconnected != null)
{
foreach (var receiver in OnClientDisconnected.GetInvocationList())
OnClientDisconnected -= (RemoteClientDisconnectedEventHandler)receiver;
}
if (OnClientMessageReceived != null)
{
foreach (var receiver in OnClientMessageReceived.GetInvocationList())
OnClientMessageReceived -= (RemoteClientMessageReceivedEventHandler)receiver;
}
}
/// <summary>
/// Send a payload to the remote client
/// </summary>
public void SendPayload(RemoteClient client, byte[] payload, int payloadSize)
{
sendPayloadToClient(client, payload, payloadSize);
}
/// <summary>
/// Disconnect the remote client
/// </summary>
public void Disconnect(RemoteClient client)
{
disconnectClient(client);
}
#endregion
#region Core
public void Tick() {
Tick(DateTime.Now.GetTotalSeconds());
}
double keepAlive = 0.0;
internal void Tick(double time)
{
this.listenSocket.Pump();
double dt = time - this.time;
this.time = time;
// process datagram queue
Datagram packet;
while (listenSocket != null && listenSocket.Read(out packet)) {
processDatagram(packet.payload, packet.payloadSize, packet.sender);
packet.Release();
}
// send keep alive to clients 10 times per second
keepAlive += dt;
while (keepAlive >= 0.1)
{
keepAlive -= 0.1;
for (int i = 0; i < clientSlots.Length; i++)
{
if (clientSlots[i] != null)
{
sendKeepAlive(clientSlots[i]);
}
}
}
// disconnect any clients which have not responded for timeout seconds
for (int i = 0; i < clientSlots.Length; i++)
{
if (clientSlots[i] == null) continue;
double timeRemaining = time - clientSlots[i].lastResponseTime;
// timeout < 0 disables timeouts
if (clientSlots[i].timeoutSeconds >= 0 &&
(time - clientSlots[i].lastResponseTime) >= clientSlots[i].timeoutSeconds)
{
if (OnClientDisconnected != null)
OnClientDisconnected(clientSlots[i]);
log("Client {0} timed out", NetcodeLogLevel.Debug, clientSlots[i].RemoteEndpoint.ToString());
disconnectClient(clientSlots[i]);
}
}
}
private void serverTick(Object stateInfo)
{
while (isRunning)
{
Tick(DateTime.Now.GetTotalSeconds());
// sleep until next tick
double tickLength = 1.0 / tickrate;
Thread.Sleep((int)(tickLength * 1000));
}
}
// 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;
}
}
}
}
#endregion
#region Receive Packet Methods
// 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 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);
}
// 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];
if (!client.Confirmed) {
// trigger callback
if (OnClientConnected != null)
OnClientConnected(client);
log("Client {0} connected", NetcodeLogLevel.Info, client.RemoteEndpoint);
}
client.Confirmed = true;
client.Touch(time);
// trigger callback
if (OnClientMessageReceived != null)
OnClientMessageReceived(client, payloadPacket.Payload, payloadPacket.Length);
payloadPacket.Release();
}
// 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 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 request packet
private void processConnectionRequest(ByteArrayReaderWriter reader, int size, EndPoint sender)
{
log("Got connection request", NetcodeLogLevel.Debug);
var connectionRequestPacket = new NetcodeConnectionRequestPacket();
if (!connectionRequestPacket.Read(reader, size - (int)reader.ReadPosition, protocolID))
{
log("Failed to read request", NetcodeLogLevel.Debug);
return;
}
// expiration timestamp should be greater than current timestamp
if (connectionRequestPacket.Expiration <= (ulong)Math.Truncate(time))
{
log("Connect token expired", NetcodeLogLevel.Debug);
connectionRequestPacket.Release();
return;
}
var privateConnectToken = new NetcodePrivateConnectToken();
if (!privateConnectToken.Read(connectionRequestPacket.ConnectTokenBytes, privateKey, protocolID, connectionRequestPacket.Expiration, connectionRequestPacket.TonkenNonce))
{
log("Failed to read private token", NetcodeLogLevel.Debug);
connectionRequestPacket.Release();
return;
}
// if this server's public IP is not in the list of endpoints, packet is not valid
bool serverAddressInEndpoints = privateConnectToken.ConnectServers.Any(x => x.Endpoint.CompareEndpoint(this.listenEndpoint, this.Port));
if (!serverAddressInEndpoints)
{
log("Server address not listen in token", NetcodeLogLevel.Debug);
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 as the connect token is already connected, ignore the packet
if (clientSlots.Any(x => x != null && x.ClientID == privateConnectToken.ClientID))
{
log("Client ID {0} already connected", NetcodeLogLevel.Debug, privateConnectToken.ClientID);
return;
}
// if the connect token has already been used by a different endpoint, ignore the packet
// otherwise, add the token hmac and endpoint to the used token history
// compares the last 16 bytes (token mac)
byte[] token_mac = BufferPool.GetBuffer(Defines.MAC_SIZE);
System.Array.Copy(connectionRequestPacket.ConnectTokenBytes, Defines.NETCODE_CONNECT_TOKEN_PRIVATE_BYTES - Defines.MAC_SIZE, token_mac, 0, Defines.MAC_SIZE);
if (!findOrAddConnectToken(sender, token_mac, time))
{
log("Token already used", NetcodeLogLevel.Debug);
BufferPool.ReturnBuffer(token_mac);
return;
}
BufferPool.ReturnBuffer(token_mac);
// if we have no slots, we need to respond with a connection denied packet
var nextSlot = getFreeClientSlot();
if (nextSlot == -1)
{
denyConnection(sender, privateConnectToken.ServerToClientKey);
log("Server is full, denying connection", NetcodeLogLevel.Info);
return;
}
// add encryption mapping for this endpoint as well as timeout
// packets received from this endpoint are to be decrypted with the client-to-server key
// packets sent to this endpoint are to be encrypted with the server-to-client key
// if no messages are received within timeout from this endpoint, it is disconnected (unless timeout is negative)
if (!encryptionManager.AddEncryptionMapping(sender,
privateConnectToken.ServerToClientKey,
privateConnectToken.ClientToServerKey,
time,
time + 30,
privateConnectToken.TimeoutSeconds,
0))
{
log("Failed to add encryption mapping", NetcodeLogLevel.Error);
return;
}
// finally, send a connection challenge packet
sendConnectionChallenge(privateConnectToken, sender);
}
#endregion
#region Send Packet Methods
// disconnect all clients
private void disconnectAll()
{
for (int i = 0; i < clientSlots.Length; i++)
{
if (clientSlots[i] != null)
disconnectClient(clientSlots[i]);
}
}
// sends a disconnect packet to the client
private void disconnectClient(RemoteClient client)
{
for (int i = 0; i < clientSlots.Length; i++)
{
if (clientSlots[i] == client)
{
clientSlots[i] = null;
break;
}
}
var cryptIdx = encryptionManager.FindEncryptionMapping(client.RemoteEndpoint, time);
if (cryptIdx == -1)
{
return;
}
var cryptKey = encryptionManager.GetSendKey(cryptIdx);
for (int i = 0; i < Defines.NUM_DISCONNECT_PACKETS; i++)
{
serializePacket(new NetcodePacketHeader() { PacketType = NetcodePacketType.ConnectionDisconnect }, (writer) =>
{
}, client.RemoteEndpoint, cryptKey);
}
}
// sends a connection denied packet to the endpoint
private void denyConnection(EndPoint endpoint, byte[] cryptKey)
{
if (cryptKey == null)
{
var cryptIdx = encryptionManager.FindEncryptionMapping(endpoint, time);
if (cryptIdx == -1) return;
cryptKey = encryptionManager.GetSendKey(cryptIdx);
}
serializePacket(new NetcodePacketHeader() { PacketType = NetcodePacketType.ConnectionDenied }, (writer) =>
{
}, endpoint, cryptKey);
}
// send a payload to a client
private void sendPayloadToClient(RemoteClient client, byte[] payload, int payloadSize)
{
// if the client isn't confirmed, send a keep-alive packet before this packet
if (!client.Confirmed)
sendKeepAlive(client);
var cryptIdx = encryptionManager.FindEncryptionMapping(client.RemoteEndpoint, time);
if (cryptIdx == -1) return;
var cryptKey = encryptionManager.GetSendKey(cryptIdx);
serializePacket(new NetcodePacketHeader() { PacketType = NetcodePacketType.ConnectionPayload }, (writer) =>
{
writer.WriteBuffer(payload, payloadSize);
}, client.RemoteEndpoint, cryptKey);
}
// send a keep-alive packet to the client
private void sendKeepAlive(RemoteClient client)
{
var packet = new NetcodeKeepAlivePacket() { ClientIndex = client.ClientIndex, MaxSlots = (uint)this.maxSlots };
var cryptIdx = encryptionManager.FindEncryptionMapping(client.RemoteEndpoint, time);
if (cryptIdx == -1) return;
var cryptKey = encryptionManager.GetSendKey(cryptIdx);
serializePacket(new NetcodePacketHeader() { PacketType = NetcodePacketType.ConnectionKeepAlive }, (writer) =>
{
packet.Write(writer);
}, client.RemoteEndpoint, cryptKey);
}
// sends a connection challenge packet to the endpoint
private void sendConnectionChallenge(NetcodePrivateConnectToken connectToken, EndPoint endpoint)
{
log("Sending connection challenge", NetcodeLogLevel.Debug);
var challengeToken = new NetcodeChallengeToken();
challengeToken.ClientID = connectToken.ClientID;
challengeToken.UserData = connectToken.UserData;
ulong challengeSequence = nextChallengeSequenceNumber++;
byte[] tokenBytes = BufferPool.GetBuffer(300);
using (var tokenWriter = ByteArrayReaderWriter.Get(tokenBytes))
challengeToken.Write(tokenWriter);
byte[] encryptedToken = BufferPool.GetBuffer(300);
int encryptedTokenBytes;
try
{
encryptedTokenBytes = PacketIO.EncryptChallengeToken(challengeSequence, tokenBytes, challengeKey, encryptedToken);
}
catch
{
BufferPool.ReturnBuffer(tokenBytes);
BufferPool.ReturnBuffer(encryptedToken);
return;
}
var challengePacket = new NetcodeConnectionChallengeResponsePacket();
challengePacket.ChallengeTokenSequence = challengeSequence;
challengePacket.ChallengeTokenBytes = encryptedToken;
var cryptIdx = encryptionManager.FindEncryptionMapping(endpoint, time);
if (cryptIdx == -1) return;
var cryptKey = encryptionManager.GetSendKey(cryptIdx);
serializePacket(new NetcodePacketHeader() { PacketType = NetcodePacketType.ConnectionChallenge }, (writer) =>
{
challengePacket.Write(writer);
}, endpoint, cryptKey);
BufferPool.ReturnBuffer(tokenBytes);
BufferPool.ReturnBuffer(encryptedToken);
}
// 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 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);
}
#endregion
#region Misc Util Methods
// find or add a connect token entry
// intentional constant time worst case search
private bool findOrAddConnectToken(EndPoint address, byte[] mac, double time)
{
int matchingTokenIndex = -1;
int oldestTokenIndex = -1;
double oldestTokenTime = 0.0;
for (int i = 0; i < connectTokenHistory.Length; i++)
{
var token = connectTokenHistory[i];
if (MiscUtils.CompareHMACConstantTime(token.mac, mac))
matchingTokenIndex = i;
if (oldestTokenIndex == -1 || token.time < oldestTokenTime)
{
oldestTokenTime = token.time;
oldestTokenIndex = i;
}
}
// if no entry is found with the mac, this is a new connect token. replace the oldest token entry.
if (matchingTokenIndex == -1)
{
connectTokenHistory[oldestTokenIndex].time = time;
connectTokenHistory[oldestTokenIndex].endpoint = address;
Buffer.BlockCopy(mac, 0, connectTokenHistory[oldestTokenIndex].mac, 0, mac.Length);
return true;
}
// allow connect tokens we have already seen from the same address