NWM Services

These NWM services are used for local-WLAN communications, NWM module handles regular wifi APs as well. These services are used for creating/connecting to networks, and for sending/receiving data over the network etc. NWM module uses the wifi SDIO hardware via the IO registers for this.

NWM local-WLAN service "nwm::UDS"

Command Header	Available since system version	Description
0x00010442		Unknown, probably deprecated. Not used by "Steel Diver: Sub Wars".
0x00020000		Scrap Not used by sub-wars. This sets a state value to 0x2 then signals an event. This is probably some sort of shutdown command since this state write will result in all UDS commands returning an error if used afterwards.
0x00030000		Shutdown
0x00040402		CreateNetwork Deprecated. Only used by very old titles.
0x00050040		EjectClient
0x00060000		EjectSpectator
0x00070080		UpdateNetworkAttribute
0x00080000		DestroyNetwork
0x00090442		ConnectNetwork Deprecated. Only used by very old titles.
0x000A0000		DisconnectNetwork
0x000B0000		GetConnectionStatus
0x000C0000		This writes two output u8 values to cmdreply[2] +0/+1. Not used by sub-wars.
0x000D0040		GetNodeInformation
0x000E0006		Unknown. Not used by sub-wars.
0x000F0404		RecvBeaconBroadcastData
0x00100042		SetApplicationData
0x00110040		GetApplicationData
0x00120100		Bind
0x00130040		Unbind
0x001400C0		PullPacket
0x00150080		SetMaxSendDelay(u32 unk0, u32 unk1) Not used by sub-wars.
0x00160040		(u8 inputval) Unknown. Not used by sub-wars.
0x00170182		SendTo
0x00180040		(u16 inputval) Unknown. Not used by sub-wars.
0x00190040		(u32 inputval) Unknown. Not used by sub-wars.
0x001A0000		GetChannel
0x001B0302		InitializeWithVersion
0x001C0040		(u8 inputval) Unknown. Not used by sub-wars.
0x001D0044	Unknown, >2.0.0-2	BeginHostingNetwork This is a replacement for the original network-creation command.
0x001E0084	Unknown, >2.0.0-2	ConnectToNetwork This is a replacement for the original network-connection command.
0x001F0006	Unknown, >2.0.0-2	DecryptBeaconData
0x00200040	Unknown, >2.0.0-2	Flush (u8 data_frame_index) Unknown. Not used by sub-wars.
0x00210080	Unknown, >2.0.0-2	SetProbeResponseParam Used before using NWMUDS:BeginHostingNetwork. It's unknown why this is used at all, this data isn't stored in the beacons and there doesn't seem to be any(?) probe requests/responses used with UDS either.
0x00220402	Unknown, >2.0.0-2	ScanOnConnection
0x00230000	Unknown, >2.0.0-2	This writes an output u16 value to cmdreply[2]. Unknown. Not used by sub-wars.

PullPacket is used for receiving data over the network and SendTo is for sending data over the network.

NWM infrastructure service "nwm::INF"

Command Header	Description
0x000603C4	RecvBeaconBroadcastData
0x00070742	ConnectToEncryptedAP
0x0008....	ConnectToAP

NWM local-WLAN StreetPass service "nwm::CEC"

Command Header	Description
0x00060002	Unknown, called by CECD module, cmdbuf[2] takes an event handle
0x000D0082	SendProbeRequest

NWM service "nwm::EXT"

Command Header	Available since system version	Description
0x0001....	<=2.0.0-2	?
0x0002....	<=2.0.0-2	?
0x0003....	<=2.0.0-2	?
0x0004....	<=2.0.0-2	?
0x0005....	<=2.0.0-2	?
0x0006....	<=2.0.0-2	?
0x00070000	<=2.0.0-2	This copies 0x1C-bytes from NWM-module state to the data starting at cmdreply[2].
0x00080040	<=2.0.0-2	ControlWirelessEnabled
0x0009....	<=2.0.0-2	?

Local-WLAN

UDS is used for 3DS<>3DS local-WLAN communications, and for 3DS<>Wii U communications. The latter is mainly only used for multi-player in games.

All UDS local-WLAN communications have the CCMP key for data encryption generated via NWM module. The CCMP key passed to nwm::CEC commands(stored in a 0x44-byte input structure) for StreetPass is generated by the CECD module. The input data used with EncryptDecryptAes with keytype1 is a MD5 hash over an input passphrase. This input passphrase is fixed for Download Play, it's unique per local-WLAN protocol. The CTR is a MD5 hash over the below 0x10-byte structure. The output from encrypting that data with AES-CTR is the final CCMP key.

NodeID

This is the u16 ID for each device on the UDS network. NodeID 0xFFFF is a broadcast alias. When spectators are allowed, NodeID value 0x1 is used for spectators, then 0x2 for the host and 0x3 for the first actual client. Otherwise, the NodeID values start at 0x1 for the host followed by the clients.

Application data transfer

The protocol used for sending/receiving data over the network with UDS by official applications is PRUDP(in some cases at least). In some cases at least this is with PRUDPS(additional encryption layer). This includes UDS-specific data in each frame, such as Mii data. Mario Kart 7 uses PRUDPS here.

Data frames

Data is transferred over the network using NWMUDS:PullPacket/NWMUDS:SendTo. That data is transferred using 802.11 data frames using CCMP encryption. The encrypted data contained in the frame starts with a 0xE-byte NWM header, followed by the actual application data from the previously mentioned commands. When NWMUDS:SendTo was used with dst_NodeID = broadcast, the data frame is sent to the 802.11 broadcast MAC address. Otherwise with a specific NodeID, the data frame is sent to the actual MAC address for that device.

Structure used for generating the CTR for CCMP key generation

Offset	Size	Description
0x0	0x4	Local-WLAN communication ID, normally this is: (user_process uniqueID << 8) | val. Where val is 0x10 on retail(configmem UNITINFO bit0 set), 0x90 for devunit. For Download Play, this is always 0x2810 on retail(0x2890 on devunit).
0x4	0x4	u32 networkID, randomly-generated when creating the network. The network SSID used when a client connects to the network is sprintf(out, "%08X", networkID).
0x8	0x6	Host MAC address.
0xE	0x2	ID, for Download Play this is 0x55.

This data is stored as little-endian.

CTR used for beacon tags crypto

Offset	Size	Description
0x0	0x6	Host MAC address
0x6	0x4	wlancommID
0xA	0x1	This ID is also stored at offset 0xE in the CTR-generation structure.
0xB	0x1	Padding, value zero.
0xC	0x4	This is the u32 from offset 0x18 in the network-struct.

This data is stored as little-endian. All data here is all-zero except for the MAC address, when the u8 at offset 0x8 in the network-struct is 0.

Network structure

Offset	Size	Description
0x0	0x6	This is the MAC address of the host. This is all-zero on the host, like with NWMUDS:BeginHostingNetwork.
0x8	0x1	This is non-zero when at least one entry is stored in the array under the encrypted beacon data.
0xC	0x3	This is the OUI value for use with the beacon tags. Normally this is 001F32.
0xF	0x1	OUI type (21/0x15)
0x10	0x4	wlancommID
0x14	0x1	This ID is also stored at offset 0xE in the CTR-generation structure.
0x16	0x2	This u16 bitmask can be written via NWMUDS:UpdateNetworkAttribute. When bitmask 0x2 is set, new Clients are not allowed to connect. Bitmask 0x4 is probably the same as 0x2 except for Spectators.
0x1C	0x1	?
0x1D	0x1	This is the total number of entries stored under the array in the encrypted beacon data.
0x1E	0x1	?
0x1F	0x1	?
0x3F	0x1	Size of additional data. Normally zero.
0x40	0xC8	Additional data, if any. Size of the additional data is specified via the u8 at offset 0x3F. This data is not used when the size-field is zero.

This 0x108-byte structure is used for NWMUDS:BeginHostingNetwork, NWMUDS:ConnectToNetwork, etc. This data is stored as big-endian.

UDS Beacons

The UDS host broadcasts a beacon containing at least two Nintendo-vendor tags(tag number 0xDD, see above for the OUI), normally the data stored in these tags are static. The second tag contains the big-endian u32 networkID, used by the clients when connecting to the host and for the above CCMP key generation. The Nintendo-vendor tag(s) following the first two are unique to the process using UDS, these tags are used for broadcasting metadata regarding the host.

A tool for these beacons is available here: [1]

UDS Beacon Tags

The following is the structure of each tag, starting at the OUI. The order of the tags is the same as listed below. All data stored under these tags are stored as big-endian.

OUI Type 20

Offset	Size	Description
0x0	0x3	OUI, see above.
0x3	0x1	OUI type (20/0x14)
0x4	0x3	Sample data: 0a 00 00

Normally the size of this tag(from the tag size field) is 0x07.

OUI Type 21

Offset	Size	Description
0x0	0x1F	This is the network structure starting at offset 0xC, with the first 0x1F-bytes from there.
0x1F	0x14	SHA1 hash. When doing the hashing, this hash is cleared to zero. The hash data starts at offset 0x0(OUI), and the size is 0x34 + <value of the u8 at offset 0x33>.
0x33	0x1	Size of additional data. Normally zero. When non-zero this additional data is located at offset 0x34.

Normally the size of this tag(from the tag size field) is 0x34.

OUI Type 24

Offset	Size	Description
0x0	0x3	OUI, see above.
0x3	0x1	OUI type (24/0x18)
0x4	See below	Encrypted data

This is the tag0 used with NWMUDS:DecryptBeaconData. The size of data stored under this tag has a maximum size of 0xFA-bytes, however normally the size is smaller than that. Additional encrypted data, if any, is stored under the below tag1.

OUI Type 25

Offset	Size	Description
0x0	0x3	OUI, see above.
0x3	0x1	OUI type (25/0x19)
0x4	See above	Encrypted data

When this exists in the beacon, this is the tag1 used with NWMUDS:DecryptBeaconData. The data stored here is the 0xFA-bytes following the previous encrypted data in tag0, for more space for storing the encrypted data.

Encrypted beacon data

The following structure is for the plaintext version of the encrypted data.

This data is encrypted with AES-CTR, by NWM module in software. The AES key is stored in NWM module itself. See above for the CTR. The size of this encrypted data is 0x12 + (0x1E*val), where val is the u8 from networkstruct offset 0x1D(zero when the u8 at networkstruct offset 0x8 is value zero).

Structure

Offset	Size	Description
0x0	0x10	MD5 over the rest of the data following this(plaintext).
0x10	0x2	?
0x12	0x1E * <total array entries>	This is an array of entries for each of the devices on this network, the first entry is for the host and the rest is for the client(s).

Array entry

Offset	Size	Description
0x0	0x18	This is the first 0x18-bytes of the structure from here.
0x18	0x4	?
0x1C	0x2	?

Errors

Error code	Description
0xC8A06C0D	The operation being performed is already done (e.g., if you run NWMEXT_ControlWirelessEnabled to turn wifi on when it's on already, you can't turn it on again).