NWM Services

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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 ?
0x00020000 Scrap
0x00030000 Shutdown
0x00040402 CreateNetwork
0x00050040 EjectClient
0x00060000 EjectSpectator
0x00070080 UpdateNetworkAttribute
0x00080000 DestroyNetwork
0x00090442 ?
0x000A0000 DisconnectNetwork
0x000B0000 GetConnectionStatus
0x000C0000 This writes two output u8 values to cmdreply[2] +0/+1.
0x000D0040 GetNodeInformation
0x000E0006 ?
0x000F0404 RecvBeaconBroadcastData
0x00100042 SetApplicationData
0x00110040 GetApplicationData
0x00120100 Bind
0x00130040 Unbind
0x001400C0 PullPacket
0x00150080 SetMaxSendDelay(u32 unk0, u32 unk1)
0x00160040 (u8 inputval) ?
0x00170182 SendTo
0x00180040 (u16 inputval) ?
0x00190040 (u32 inputval) ?
0x001A0000 GetChannel
0x001B0302 InitializeWithVersion
0x001C0040 (u8 inputval) ?
0x001D0044 Unknown, >2.0.0-2 BeginHostingNetwork This appears to be a replacement for the original network-creation command(newer titles don't use the original one anymore).
0x001E0084 Unknown, >2.0.0-2 ConnectToNetwork This appears to be a replacement for the original network-connection command(newer titles don't use the original one anymore).
0x001F0006 Unknown, >2.0.0-2 DecryptBeaconData
0x00200040 Unknown, >2.0.0-2 Flush (u8 data_frame_index)
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].

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 socket service "nwm::SOC"

NWM service "nwm::SAP"

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 ?

NWM service "nwm::TST"

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.
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).