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Implement NAT hole punching and make API server configurable
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@kaenganxt
kaenganxt committed Oct 24, 2022
1 parent 40db973 commit 6ceb89a
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Showing 11 changed files with 236 additions and 66 deletions.
15 changes: 14 additions & 1 deletion src/api/Networking/Status/ClientStatus.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,12 @@ public enum ClientStatus
/// </summary>
Disconnected,

/// <summary>
/// Before starting to actually connect, the global server
/// is queried and NAT punchthrough is attempted.
/// </summary>
PreConnecting,

/// <summary>
/// The client is trying to connect to the server, this phase
/// can take up to 30 seconds.
Expand All @@ -33,6 +39,13 @@ public enum ClientStatus
/// The client is connected to the server and is
/// transmitting information.
/// </summary>
Connected
Connected,

/// <summary>
/// If the connection was rejected by the server.
/// Special case to separate from "Disconnected" during
/// connection attempts. If rejected, no other IPs need to be tried.
/// </summary>
Rejected
}
}
3 changes: 2 additions & 1 deletion src/csm/Commands/CommandInternal.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,8 @@ public void SendToOtherClients(CommandBase command, Player exclude)
/// <param name="command">The command to send.</param>
public void SendToServer(CommandBase command)
{
if (MultiplayerManager.Instance.CurrentClient.Status == ClientStatus.Disconnected)
if (MultiplayerManager.Instance.CurrentClient.Status == ClientStatus.Disconnected ||
MultiplayerManager.Instance.CurrentClient.Status == ClientStatus.PreConnecting)
return;

TransactionHandler.StartTransaction(command);
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2 changes: 1 addition & 1 deletion src/csm/Commands/Handler/Internal/ConnectionResultHandler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ protected override void Handle(ConnectionResultCommand command)
{
Log.Info($"Could not connect: {command.Reason}");
MultiplayerManager.Instance.CurrentClient.ConnectionMessage = command.Reason;
MultiplayerManager.Instance.CurrentClient.Disconnect();
MultiplayerManager.Instance.CurrentClient.ConnectRejected();
if (command.Reason.Contains("DLC")) // No other way to detect if we should display the box
{
DLCHelper.DLCComparison compare = DLCHelper.Compare(command.DLCBitMask, DLCHelper.GetOwnedDLCs());
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2 changes: 1 addition & 1 deletion src/csm/Injections/MainMenuHandler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ public static void CheckForUpdate(bool alwaysShowInfo)
{
try
{
string latest = new CSMWebClient().DownloadString("http://api.citiesskylinesmultiplayer.com/api/version");
string latest = new CSMWebClient().DownloadString($"http://{CSM.Settings.ApiServer}/api/version");
latest = latest.Substring(1);
string[] versionParts = latest.Split('.');
Version latestVersion = new Version(int.Parse(versionParts[0]), int.Parse(versionParts[1]));
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149 changes: 115 additions & 34 deletions src/csm/Networking/Client.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,13 +55,17 @@ public ClientStatus Status {
/// </summary>
public string ConnectionMessage { get; set; } = "Unknown error";

private bool MainMenuEventProcessing = false;
private bool _mainMenuEventProcessing = false;

public Client()
{
// Set up network items
EventBasedNetListener listener = new EventBasedNetListener();
_netClient = new LiteNetLib.NetManager(listener);
_netClient = new LiteNetLib.NetManager(listener)
{
NatPunchEnabled = true,
UnconnectedMessagesEnabled = true
};

// Listen to events
listener.NetworkReceiveEvent += ListenerOnNetworkReceiveEvent;
Expand All @@ -81,21 +85,13 @@ public bool Connect(ClientConfig clientConfig)
// Let the user know that we are trying to connect to a server
Log.Info($"Attempting to connect to server at {clientConfig.HostAddress}:{clientConfig.Port}...");

// if we are currently trying to connect, cancel
// and try again.
if (Status == ClientStatus.Connecting)
if (Status != ClientStatus.Disconnected)
{
Log.Info("Current status is 'connecting', attempting to disconnect first.");
Disconnect();
Log.Warn("Current status is not disconnected, ignoring connection attempt.");
return false;
}

// The client is already connected so we need to
// disconnect.
if (Status == ClientStatus.Connected)
{
Log.Info("Current status is 'connected', attempting to disconnect first.");
Disconnect();
}
Status = ClientStatus.PreConnecting;

// Set the configuration
Config = clientConfig;
Expand All @@ -107,25 +103,95 @@ public bool Connect(ClientConfig clientConfig)
if (!result)
{
Log.Error("The client failed to start.");
ConnectionMessage = "The client failed to start.";
ConnectionMessage = "Client failed to start.";
Disconnect(); // make sure we are fully disconnected
return false;
}

Log.Info("Set status to 'connecting'...");
return SetupHolePunching();
}

private bool SetupHolePunching()
{
// Given string to IP address (resolves domain names).
IPAddress resolvedAddress;
try
{
resolvedAddress = NetUtils.ResolveAddress(Config.HostAddress);
}
catch
{
ConnectionMessage = "Invalid server IP";
Disconnect(); // make sure we are fully disconnected
return false;
}

EventBasedNatPunchListener natPunchListener = new EventBasedNatPunchListener();
Stopwatch timeoutWatch = new Stopwatch();

// Callback on for each possible IP address to connect to the server.
// Can potentially be called multiple times (local and public IP address).
natPunchListener.NatIntroductionSuccess += (point, type, token) =>
{
timeoutWatch.Stop();
if (Status == ClientStatus.PreConnecting)
{
Log.Info($"Trying endpoint {point} after NAT hole punch...");
bool success = DoConnect(point);
if (!success)
{
Status = Status == ClientStatus.Rejected ? ClientStatus.Disconnected : ClientStatus.PreConnecting;
}
}
timeoutWatch.Start();
};

// Register listener and send request to global server
_netClient.NatPunchModule.Init(natPunchListener);
_netClient.NatPunchModule.SendNatIntroduceRequest(new IPEndPoint(IpAddress.GetIpv4(CSM.Settings.ApiServer), 4240), $"client_{resolvedAddress}");

timeoutWatch.Start();
// Wait for NatPunchModule responses.
// 5 seconds include only the time waiting for nat punch management.
// Connection attempts have their own timeout in the DoConnect method
// The waitWatch is paused during an connection attempt.
while (Status == ClientStatus.PreConnecting && timeoutWatch.Elapsed < TimeSpan.FromSeconds(5))
{
_netClient.NatPunchModule.PollEvents();
// Wait 50ms
Thread.Sleep(50);
}

if (Status == ClientStatus.PreConnecting) // If timeout, try exact given address
{
Log.Info($"No registered server on GS found, trying exact given address {resolvedAddress}:{Config.Port}...");
bool success = DoConnect(new IPEndPoint(resolvedAddress, Config.Port));
if (!success)
{
Disconnect(); // Make sure we are fully disconnected
return false;
}

return true;
}

return Status != ClientStatus.Disconnected;
}

private bool DoConnect(IPEndPoint point)
{
// Try connect to server, update the status to say that
// we are trying to connect.
try
{
_netClient.Connect(Config.HostAddress, Config.Port, "CSM");
_netClient.Connect(point, "CSM");
}
catch (Exception ex)
{
ConnectionMessage = "Failed to connect.";
Log.Error($"Failed to connect to {Config.HostAddress}:{Config.Port}", ex);
Chat.Instance.PrintGameMessage(Chat.MessageType.Error, $"Failed to connect: {ex.Message}");
Disconnect();
Log.Error($"Failed to connect to {point.Address}:{point.Port} ", ex);
return false;
}

Expand All @@ -140,7 +206,7 @@ public bool Connect(ClientConfig clientConfig)
waitWatch.Start();

// Try connect for 30 seconds
while (waitWatch.Elapsed < TimeSpan.FromSeconds(30))
while (waitWatch.Elapsed < TimeSpan.FromSeconds(10))
{
// If we connect, exit the loop and return true
if (Status == ClientStatus.Connected || Status == ClientStatus.Downloading || Status == ClientStatus.Loading)
Expand All @@ -154,7 +220,11 @@ public bool Connect(ClientConfig clientConfig)
if (Status == ClientStatus.Disconnected)
{
Log.Warn("Client disconnected while in connecting loop.");
Disconnect(); // make sure we are fully disconnected
return false;
}

if (Status == ClientStatus.Rejected)
{
return false;
}

Expand All @@ -165,12 +235,23 @@ public bool Connect(ClientConfig clientConfig)
// We have timed out
ConnectionMessage = "Could not connect to server, timed out.";
Log.Warn("Connection timeout!");
Status = ClientStatus.PreConnecting;

// Did not connect
Disconnect(); // make sure we are fully disconnected
return false;
}

/// <summary>
/// Called when the connection was rejected by the server in the ConnectionResultCommand.
/// This also means that the network connection was working properly, so we don't
/// need to try any further network endpoints.
/// </summary>
public void ConnectRejected()
{
Status = ClientStatus.Rejected;
_netClient.Stop();
TransactionHandler.ClearTransactions();
}

/// <summary>
/// Attempt to disconnect from the server
/// </summary>
Expand Down Expand Up @@ -199,9 +280,9 @@ public void Disconnect()

public void SendToServer(CommandBase message)
{
if (Status == ClientStatus.Disconnected)
if (Status == ClientStatus.Disconnected || Status == ClientStatus.PreConnecting)
{
Log.Error("Attempted to send message to server, but the client is disconnected");
Log.Error("Attempted to send message to server, but the client is not connected");
return;
}

Expand Down Expand Up @@ -233,7 +314,7 @@ private void ListenerOnNetworkReceiveEvent(NetPeer peer, NetPacketReader reader,
}
catch (Exception ex)
{
Log.Error($"Encountered an error while reading command from {peer.EndPoint.Address}:{peer.EndPoint.Port}:", ex);
Log.Error("Failed to handle command from server: ", ex);
}
}

Expand Down Expand Up @@ -271,7 +352,7 @@ private void ListenerOnPeerDisconnectedEvent(NetPeer peer, DisconnectInfo discon
ConnectionMessage = "Failed to connect!";

// Log the error message
Log.Info($"Disconnected from server. Message: {disconnectInfo.Reason}, Code: {disconnectInfo.SocketErrorCode}");
Log.Info($"Disconnected from server. Message: {disconnectInfo.Reason}");

// Log the reason to the console if we are not in 'connecting' state
if (Status == ClientStatus.Connected)
Expand All @@ -297,7 +378,7 @@ private void ListenerOnPeerDisconnectedEvent(NetPeer peer, DisconnectInfo discon
}

// If we are connected, disconnect
if (Status != ClientStatus.Disconnected && Status != ClientStatus.Connecting)
if (Status == ClientStatus.Downloading || Status == ClientStatus.Loading || Status == ClientStatus.Connected)
MultiplayerManager.Instance.StopEverything();

// In the case of ClientStatus.Connecting, this also ends the wait loop
Expand All @@ -310,7 +391,7 @@ private void ListenerOnPeerDisconnectedEvent(NetPeer peer, DisconnectInfo discon
/// </summary>
private void ListenerOnNetworkErrorEvent(IPEndPoint endpoint, SocketError socketError)
{
Log.Error($"Received an error from {endpoint.Address}:{endpoint.Port}. Code: {socketError}");
Log.Error($"Network error: {socketError}");
}

private void ListenerOnNetworkLatencyUpdateEvent(NetPeer peer, int latency)
Expand All @@ -320,11 +401,11 @@ private void ListenerOnNetworkLatencyUpdateEvent(NetPeer peer, int latency)

public void StartMainMenuEventProcessor()
{
if (MainMenuEventProcessing) return;
if (_mainMenuEventProcessing) return;
new Thread(() =>
{
MainMenuEventProcessing = true;
while (MainMenuEventProcessing)
_mainMenuEventProcessing = true;
while (_mainMenuEventProcessing)
{
// The threading extension is not yet loaded when at the main menu, so
// process the events and go on
Expand All @@ -337,7 +418,7 @@ public void StartMainMenuEventProcessor()

public void StopMainMenuEventProcessor()
{
MainMenuEventProcessing = false;
_mainMenuEventProcessing = false;
}
}
}
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