LANCommander.Interposer 1.4.0

LANCommander.Interposer

.NET bindings for LANCommander Interposer - a Windows DLL that hooks into game processes to provide virtual registry, file redirection, DNS redirection, identity overrides, FastDL, DirectInput fixes, OS version spoofing, and Discord rich presence for LAN gaming.

Everything goes through InterposerService:

• Injection - Launch processes with ProcessStartInfo or inject into running Process instances, with optional runtime overrides for username, computer name, FastDL URL, a config overlay and a per-game base directory.
• Plugin API - Logging, config, virtual registry, and rich presence (in-process only).
• Hook Events - Subscribe to file, registry, DNS, network, and identity events (in-process only).
• Network Relay - Put a game on a virtual LAN through a LANCommander relay server, and drive it from the launcher while it runs.

Everything else the DLL does is driven by .interposer\Config.yml next to the DLL and needs no managed calls - see Configuration below.

Launch and Inject

using System.Diagnostics;
using LANCommander.Interposer;

using var interposer = new InterposerService();
interposer.Username = "Player1";
interposer.ComputerName = "GAMEPC";
interposer.FastDlUrl = "http://fastdl.lan/";

// Launch suspended, inject the DLL, resume - returns a standard Process
var startInfo = new ProcessStartInfo(@"C:\Games\game.exe", "-fullscreen");
Process game = interposer.Start(startInfo);

// Or inject into an already-running process
interposer.Inject(existingProcess);
interposer.Inject(1234);  // by PID

The DLL is located automatically next to the application (interposer.dll or LANCommander.Interposer.dll). Pass an explicit path to override:

interposer.Start(startInfo, dllPath: @"C:\Tools\LANCommander.Interposer.dll");

Plugin API (in-process)

These methods are only callable from within a process that has the Interposer DLL loaded.

using var interposer = new InterposerService();

interposer.Log("[MANAGED]      ", "Hello from .NET!");

string setting = interposer.GetConfigString("Plugins.MyPlugin.ApiKey");
interposer.SetConfigString("Plugins.MyPlugin.LastServer", "192.168.1.10");
interposer.RegisterPluginConfig("MyPlugin", "ApiKey: ''\nEnabled: true");

string username = interposer.GetUsername();

interposer.SetRegistryValue(
    @"HKEY_LOCAL_MACHINE\SOFTWARE\MyGame", "CDKey", "ABCD-1234-EFGH");

interposer.SetPresenceName("My Game");
interposer.SetPresenceDetails("Playing on de_dust2");
interposer.UpdatePresence();

Configuration

The DLL reads .interposer\Config.yml from its own directory at load time. Redirection rules, DirectInput fixes and the reported OS version are configured there, not through this API - injecting the DLL is enough to apply them.

# Report Windows XP SP3 to a game whose version switch has no case past 5.x
OsVersion:
  Version: WindowsXP

# Move a save folder. %TOKEN% resolves environment variables first, then known
# folders Windows tracks but the environment does not (%SAVEDGAMES%, %DOCUMENTS%,
# %MYGAMES%, ...), then %GAMEDIR% and %INTERPOSERDIR%. Tokens work on both sides.
FileRedirects:
  - Pattern: '%APPDATA%\\My Game\\(.+)'
    Replacement: '%SAVEDGAMES%\My Game\$1'

The substituted value of a token in a Pattern is regex-escaped automatically, so never double the backslashes inside a token - only separators you write yourself need \\.

Read any scalar back from inside an injected process:

string osVersion = interposer.GetConfigString("OsVersion.Version");  // "WindowsXP"
string username = interposer.GetConfigString("Player.Username");

GetConfigString resolves the path against the whole document, so it is not limited to the Plugins section. Sequence-valued keys such as FileRedirects are not scalar and return null.

See the OS Version and File Redirection docs for the full option reference.

Network Relay

The DLL can carry a game's LAN traffic - broadcasts, datagrams, TCP connections and emulated IPX - through a relay server, giving each player a virtual LAN address instead of a VPN. A launcher passes the session's options at launch, overriding NetworkRelay in Config.yml key by key, and controls the relay of the running game over a named pipe:

using var interposer = new InterposerService
{
    Relay = new RelayOptions
    {
        Enabled = true,
        Server  = "lancommander.example.com",
        Network = sessionId,
        Ticket  = relayTicket,
    },
};

interposer.RelayStateChanged += (s, e) => Console.WriteLine($"Relay {e.State} as {e.VirtualAddress}");
interposer.RelayPeerJoined   += (s, e) => Console.WriteLine($"{e.Name} joined at {e.VirtualAddress}");
interposer.RelayPeerLeft     += (s, e) => Console.WriteLine($"{e.Name} left");

Process game = interposer.Start(new ProcessStartInfo(@"C:\Games\game.exe"));

RelayStatus status = await interposer.GetRelayStatusAsync();
await interposer.ConnectRelayAsync(new RelayOptions { Network = "another-lobby" });
await interposer.DisconnectRelayAsync();

Setting Relay at all - even with Enabled = false - makes the DLL install its socket hooks, which it can only do at startup; set it whenever the launcher may connect the game later. The relay events also arrive over the event pipe, so they need no EnableEvents. Inside the game process, GetRelayStatus(), ConnectRelay() and DisconnectRelay() call the DLL directly.

The server side is the separate LANCommander.Interposer.Relay library. See the Network Relay docs.

One DLL, Many Games

The package puts the DLL beside your application, and the DLL reads .interposer\ from beside itself, so every game injected from it would share one Config.yml, one virtual registry and one log folder. Give each launch a base directory and a config overlay instead:

using var interposer = new InterposerService
{
    // Stands in for the DLL's own directory: .interposer\ (Config.yml, Registry.reg,
    // Logs, Downloads, Plugins) lives under it, and %INTERPOSERDIR% expands to it
    BaseDirectory = @"C:\Games\MyGame\.lancommander\interposer",

    // Merged over Config.yml for this launch only; the file is not changed
    ConfigOverlay = """
        OsVersion:
          Version: WindowsXP
        RichPresence:
          Discord:
            Enabled: true
            ApplicationId: '123456789012345678'
        AudioDevices: ~
        """,
};

Process game = interposer.Start(new ProcessStartInfo(@"C:\Games\MyGame\game.exe"));

The overlay merges key by key: maps merge recursively, a null (~) removes the key (above, it turns off an AudioDevices filter the file sets), and any other value replaces the file's, so a FileRedirects list in the overlay is the whole list. Username, ComputerName, FastDlUrl and Relay are applied on top of the merged config. A game that has the Interposer installed beside it (InterposerService.IsDeployedAsProxy) takes the overlay too, through StartWithProxy; leave BaseDirectory unset for it, because its own Config.yml and Registry.reg are beside the DLL.

InterposerOptionSchema carries the Interposer redistributable's Id and its LANCommander option schema, read from the redistributable's manifest at build time, so a host that bundles the DLL can offer the same options the redistributable does.

Hook Events (in-process)

Subscribe to hook events from within an injected process. Events fire on the game's thread - subscribers must be thread-safe.

using LANCommander.Interposer;
using LANCommander.Interposer.Events;

using var interposer = new InterposerService();
interposer.EnableEvents();

interposer.FileAccessed += (s, e) =>
    Console.WriteLine($"{e.Verb}: {e.Path}");
interposer.RegistryAccessed += (s, e) =>
    Console.WriteLine($"{e.Verb}: {e.KeyPath} -> {e.ValueName}");
interposer.DnsResolved += (s, e) =>
    Console.WriteLine($"DNS: {e.Hostname} -> {e.RedirectedHostname}");
interposer.NetworkConnection += (s, e) =>
    Console.WriteLine($"Connect: {e.Address}:{e.Port}");
interposer.IdentityQueried += (s, e) =>
    Console.WriteLine($"{e.IdentityType}: {e.Value}");

FileEventArgs.SecondaryPath carries the fully resolved redirect target for FILE REDIRECT - capture groups and %TOKEN% references are already expanded. The redirect diagnostics emitted at Logging.Level Debug and Trace (REDIRECT HIT, REDIRECT MISS, REDIRECT RULE) go to the session log only and never reach this event stream.

Requirements

• Windows - The Interposer DLL and injection APIs are Windows-only.
• .NET 8.0 / 9.0 / 10.0 - Targets modern .NET runtimes.
• The native LANCommander.Interposer.dll (or proxy variant) must be deployed alongside the target process. Download it from Releases.

License

MIT