IPC Commands

This page documents the IPC commands used by ryu_ldn_nx.

Standard LDN Commands

These are the standard Nintendo LDN IPC commands that ryu_ldn_nx intercepts:

Service: ldn:u

| Cmd | Name | Description | |-----|------|-------------| | 0 | CreateUserLocalCommunicationService | Creates a communication session | | 1 | CreateClientProcessMonitor | Internal monitor (not MITMed) |

ICommunicationInterface

| Cmd | Name | Description | |-----|------|-------------| | 0 | GetState | Get current LDN state | | 1 | GetNetworkInfo | Get current network information | | 2 | GetIpv4Address | Get local IPv4 address (Ryujinx format: big-endian uint32) | | 3 | GetDisconnectReason | Get reason for last disconnect | | 4 | GetSecurityParameter | Get security configuration | | 5 | GetNetworkConfig | Get network configuration | | 100 | AttachStateChangeEvent | Get event handle for state changes | | 101 | GetNetworkInfoLatestUpdate | Get network info with update counter | | 102 | Scan | Scan for available networks | | 103 | ScanPrivate | Scan for private networks | | 104 | SetWirelessControllerRestriction | Restrict wireless controllers | | 200 | OpenAccessPoint | Open as network host | | 201 | CloseAccessPoint | Close host mode | | 202 | CreateNetwork | Create a new network | | 203 | CreateNetworkPrivate | Create private network | | 204 | DestroyNetwork | Destroy current network | | 205 | Reject | Reject a connected player | | 206 | SetAdvertiseData | Set advertisement data | | 207 | SetStationAcceptPolicy | Set join policy (allow/reject) | | 208 | AddAcceptFilterEntry | Add entry to accept filter | | 209 | ClearAcceptFilter | Clear accept filter | | 300 | OpenStation | Open as client | | 301 | CloseStation | Close client mode | | 302 | Connect | Connect to a network | | 303 | ConnectPrivate | Connect to private network | | 304 | Disconnect | Disconnect from network | | 400 | Initialize | Initialize the service | | 401 | Finalize | Finalize the service | | 402 | InitializeSystem2 | Alternate initialization |

PIA note: After CreateNetwork/Connect, games call GetIpv4Address() and GetNetworkInfo() separately. The game then matches the IP against NetworkInfo.ldn.nodes[].ipv4_address to find its own node index. If these mismatch, FindLocalNodeId() returns 0xFF (not found) and the game destroys the network.

Custom Config Commands (ryu:cfg)

The standalone ryu:cfg IPC service is available directly via smGetService("ryu:cfg"). The overlay uses this service for live configuration and status display.

Note: GetConnectionStatus (cmd 1) in the standalone ryu:cfg service currently always returns 0 (Disconnected). For actual connection status, use GetLdnState (cmd 24) which returns the CommState enum.

Configuration Commands (0–22)

| Cmd | Name | Parameters | Returns | Description | |-----|------|------------|---------|-------------| | 0 | GetVersion | - | char[32] | Sysmodule version string | | 1 | GetConnectionStatus | - | u32 | Server connection state (currently always 0) | | 2 | GetPassphrase | - | char[64] | Current room passphrase | | 3 | SetPassphrase | char[64] | - | Set room passphrase | | 4 | GetServerAddress | - | ServerAddress | Configured server address | | 5 | SetServerAddress | ServerAddress | - | Change server address | | 6 | GetLdnEnabled | - | u32 | LDN emulation enabled flag | | 7 | SetLdnEnabled | u32 | - | Enable/disable LDN emulation | | 8 | GetUseTls | - | u32 | TLS flag (⚠️ NOT IMPLEMENTED — always plain TCP) | | 9 | SetUseTls | u32 | - | Enable/disable TLS (⚠️ has no effect) | | 10 | GetDebugEnabled | - | u32 | Debug logging flag | | 11 | SetDebugEnabled | u32 | - | Enable/disable debug logging | | 12 | GetDebugLevel | - | u32 | Log level (0-3) | | 13 | SetDebugLevel | u32 | - | Set log level | | 14 | GetLogToFile | - | u32 | File logging flag | | 15 | SetLogToFile | u32 | - | Enable/disable file logging | | 16 | SaveConfig | - | ConfigResult | Persist config to SD card | | 17 | ReloadConfig | - | ConfigResult | Reload config from SD card | | 18 | GetConnectTimeout | - | u32 | Connection timeout in ms | | 19 | SetConnectTimeout | u32 | - | Set connection timeout in ms | | 20 | GetPingInterval | - | u32 | Ping interval in ms (⚠️ parsed but not used — server drives pings) | | 21 | SetPingInterval | u32 | - | Set ping interval in ms (⚠️ has no effect) | | 22 | IsServiceActive | - | u32 | Service ping (returns 1 if active) |

Runtime State Commands (23–28)

| Cmd | Name | Parameters | Returns | Description | |-----|------|------------|---------|-------------| | 23 | IsGameActive | - | u32 | Returns 1 if a game is using LDN | | 24 | GetLdnState | - | u32 | Current CommState enum value | | 25 | GetSessionInfo | - | SessionInfo | Current session information | | 26 | GetLastRtt | - | u32 | Last RTT in milliseconds | | 27 | ForceReconnect | - | - | Request MITM reconnection | | 28 | GetActiveProcessId | - | u64 | PID of active game |

P2P Proxy Commands (29–30)

Note: Commands 29–30 are available in the ryu:cfg service but do not yet have overlay client stubs in ryu_ldn_ipc.c.

| Cmd | Name | Parameters | Returns | Description | |-----|------|------------|---------|-------------| | 29 | GetDisableP2p | - | u32 | Returns 1 if P2P proxy is disabled | | 30 | SetDisableP2p | u32 | - | Enable/disable P2P proxy (0=enable, 1=disable) |

MITM Config Commands (65000+)

The LDN MITM service also exposes a LdnConfigService via command 65000 on ldn:u. This service mirrors the ryu:cfg commands at offset +65000 and adds extended commands 65011-65030:

| Cmd | Name | Description | |-----|------|-------------| | 65000 | (get service) | Obtain LdnConfigService instance | | 65001 | GetHost | Get server hostname | | 65002 | SetHost | Set server hostname | | 65003 | GetPort | Get server port | | 65004 | SetPort | Set server port | | 65005 | GetUseTls | Get TLS setting (⚠️ not implemented — always plain TCP) | | 65006 | SetUseTls | Set TLS setting (⚠️ not implemented) | | 65007 | GetConnectTimeout | Get connect timeout in ms | | 65008 | SetConnectTimeout | Set connect timeout in ms | | 65009 | GetPingInterval | Get ping interval in ms (⚠️ parsed but not used) | | 65010 | SetPingInterval | Set ping interval in ms (⚠️ has no effect) | | 65011 | GetPassphrase | Get room passphrase | | 65012 | SetPassphrase | Set room passphrase | | 65013 | GetLdnEnabled | Get LDN enabled state | | 65014 | SetLdnEnabled | Set LDN enabled state | | 65015 | GetUseTls | Get TLS state (same as 65005) | | 65016 | SetUseTls | Set TLS state (same as 65006) | | 65017 | GetConnectTimeout | Get connect timeout (same as 65007) | | 65018 | SetConnectTimeout | Set connect timeout (same as 65008) | | 65019 | GetPingInterval | Get ping interval (same as 65009) | | 65020 | SetPingInterval | Set ping interval (same as 65010) | | 65021 | GetReconnectDelay | Get reconnect delay in ms | | 65022 | SetReconnectDelay | Set reconnect delay in ms | | 65023 | GetMaxReconnectAttempts | Get max reconnect attempts | | 65024 | SetMaxReconnectAttempts | Set max reconnect attempts (0 = disable auto-reconnect) | | 65025 | GetDebugLevel | Get debug log level | | 65026 | SetDebugLevel | Set debug log level | | 65027 | GetLogToFile | Get log-to-file state | | 65028 | SetLogToFile | Set log-to-file state | | 65029 | SaveConfig | Save current config to file | | 65030 | ReloadConfig | Reload config from file |

Data Structures

ConnectionStatus (enum u32)

| Value | Name | Description | |-------|------|-------------| | 0 | Disconnected | Not connected to server | | 1 | Connecting | Connection in progress | | 2 | Connected | TCP connected, handshake pending | | 3 | Ready | Fully connected and operational | | 4 | Error | Connection error occurred |

Note: In the standalone ryu:cfg service, GetConnectionStatus always returns 0 (Disconnected). Use GetLdnState (cmd 24) for actual status.

LdnState / CommState (enum u32)

| Value | Name | Description | |-------|------|-------------| | 0 | None | Not initialized | | 1 | Initialized | Service initialized | | 2 | AccessPoint | Host mode opened | | 3 | AccessPointCreated | Network created | | 4 | Station | Client mode opened | | 5 | StationConnected | Connected to network | | 6 | Error | Error state |

SessionInfo (struct, 8 bytes)

Important: The overlay SessionInfo is only 8 bytes, not 72 bytes as in some Nintendo SDKs. It does not contain session_duration_ms or game_name.

| Offset | Type | Name | Description | |--------|------|------|-------------| | 0x00 | u8 | node_count | Players in session | | 0x01 | u8 | max_nodes | Maximum players | | 0x02 | u8 | local_node_id | Our node ID | | 0x03 | u8 | is_host | 1 if hosting | | 0x04 | u8[4] | reserved | Padding |

ServerAddress (struct, 68 bytes)

| Offset | Type | Name | Description | |--------|------|------|-------------| | 0x00 | char[64] | host | Server hostname | | 0x40 | u16 | port | Server port | | 0x42 | u16 | padding | Reserved |

ConfigResult (enum u32)

| Value | Name | Description | |-------|------|-------------| | 0 | Success | Operation completed successfully | | 1 | FileNotFound | Config file does not exist | | 2 | ParseError | Config file has syntax errors | | 3 | IoError | File I/O error | | 4 | InvalidValue | Config value out of range or invalid |

Usage Example (C)

// Connect to ryu:cfg service directly
Service cfgService;
smGetService(&cfgService, "ryu:cfg");

// Get LDN state
u32 state;
serviceDispatchOut(&cfgService, 24, &state);
printf("LDN State: %u\n", state);

// Get session info
struct {
    u8 node_count;
    u8 max_nodes;
    u8 local_node_id;
    u8 is_host;
    u8 reserved[4];
} session_info;
serviceDispatchOut(&cfgService, 25, &session_info);

// Force reconnect
serviceDispatch(&cfgService, 27);

// Check P2P status
u32 p2p_disabled;
serviceDispatchOut(&cfgService, 29, &p2p_disabled);

// Save config to SD card
u32 result;
serviceDispatchOut(&cfgService, 16, &result);