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→Metadata frame
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UDS [[NWMUDS:Bind|data_channel]] 0x1 is used for spectator data, while all non-spectator data uses data_channel 0x2. The spectator data is received by connecting to the network as a spectator then receiving data-frames, this is handled when scanning for DLP networks.
UDS [[NWMUDS:Bind|data_channel]] 0x1 is used for spectator data, while all non-spectator data uses data_channel 0x2. The spectator data is received by connecting to the network as a spectator then receiving data-frames, this is handled when scanning for DLP networks.
+
+The spectator data includes the 48x48 icon, this has the same format as [[SMDH]].
This is the data starting at offset 0x0 for UDS PullPacket/SendTo:
This is the data starting at offset 0x0 for UDS PullPacket/SendTo:
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| 0x6
| 0x6
| 0x2
| 0x2
−| ?
+| u16, unknown. For spectator data this is only used for the metadata frame.
|-
|-
| 0x8
| 0x8
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|}
|}
−Total_frames is at least 0x4 normally. When a sysupdate is included, total_frames is 0x4+<total frames required for the titlelist(normally 0x1)>.
+Total_frames is at least 0x4 normally. When a sysupdate is included, total_frames is 0x4+<total frames required for the titlelist(normally 0x1)>. Total_frames should be <=0x20, but the code doesn't check for this specific value.
+==== Checksum ====
+The checksum seed is the 4-byte output from [[PS:EncryptDecryptAes|encrypting]] zeros with AES-CTR using [[PSPXI:EncryptDecryptAes|keytype5]]. The CTR is the output from this: "for(i=0; i<0x10; i++)ctr[i] = ctrseed[i] ^ host_macaddress[i % 6];" This ctrseed is a fixed 0x10-byte random-data block stored in DLP-sysmodule .rodata.
+This seed is initialized after connecting to/creating the DLP network.
+The checksum stored in the above data frame header is then calculated using this checksum seed.
+First, the calc_checksum is initialized to 0. Then calc_checksum is added with ''all'' words in the data frame loaded as big-endian, with the data-frame checksum cleared to zero here. If the frame_size isn't word-aligned, the remaining <4-bytes are loaded as big-endian for adding as well.
+Then this is run:
+ //During init before the above adding, shift and count are initialized:
+ //shift = (((u8*)&checksum_seed)[2] & 0xf) + 0x4;
+ //count = (((u8*)&checksum_seed)[3] & 0x7) + 0x2;
+ for(pos=0; pos<count; pos++)checksum = (checksum<<shift | checksum>>shift) ^ checksum_seed;//The u32 checksum_seed is byte-swapped on 3DS for this.
+Lastly the calculated checksum is written to output as big-endian(hence on 3DS it's byte-swapped before writing to output).
−Frames:
+==== Frames ====
{| class="wikitable" border="1"
{| class="wikitable" border="1"
|-
|-
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| 0x0
| 0x0
| 0x300
| 0x300
−| Various metadata, two UTF-16 strings displayed by the DLP-client, and the start of the icon gfx.
+| Metadata + start of the icon gfx, see below.
|-
|-
| 0x1-0x3
| 0x1-0x3
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The structure of each spectator frame relative to "frame-specific payload" is described below.
The structure of each spectator frame relative to "frame-specific payload" is described below.
−==== Metadata frame ====
+===== Metadata frame =====
{| class="wikitable" border="1"
{| class="wikitable" border="1"
|-
|-
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|-
|-
| 0x0
| 0x0
−| 0x2F0
+| 0x8
−|
+| u64 DLP-child titleID. Must be a CTR TID-high, with the TID-high set for DLP-child. The low 4-bits of the TID-low must be clear.
+|-
+| 0x8
+| 0x2
+| u16, probably the DLP-child title-version.
+|-
+| 0xA
+| 0x1
+| u8, unknown.
+|-
+| 0xB
+| 0x1
+| u8, unknown.
+|-
+| 0xC
+| 0x4
+| u32, chunk_size. This is the chunk_size used for transferring the CIA. This is the exact size used for the FS .cia file-reads on the host, and the exact size used for [[Application_Manager_Services|AM]] CIA file-writes on the client(s). Normally this is 0x0003FFC0. This appears to be validated by the client at some point, using a large value for this triggers an "connection interrupted" error when trying to connect.
+|-
+| 0x10
+| 0x2
+| Unused by the DLP-client(sysmodule).
+|-
+| 0x12
+| 0x2
+| u16, unknown.
+|-
+| 0x14
+| 0x4
+| Unused by the DLP-client(sysmodule).
+|-
+| 0x18
+| 0x10
+| Unknown 0x10-byte structure.
+|-
+| 0x28
+| 0x4
+| u32, unknown.
+|-
+| 0x2C
+| 0x4
+| u32, unknown. Must be <=0x02000000.
+|-
+| 0x30
+| 0x80 (0x3F characters are copied)
+| UTF-16 Application name string. The last u16 is ignored, value 0x0 is always written to output for it instead.
+|-
+| 0xB0
+| 0x100 (0x7F characters are copied)
+| UTF-16 Description string. The last u16 is ignored, value 0x0 is always written to output for it instead.
+|-
+| 0x1B0
+| 0x138
+| Array of 0x9C u16s for the start of the icon gfx.
+|-
+| 0x2E8
+| 0x1
+| u8, unknown. Written to outptr+2.
+|-
+| 0x2E9
+| 0x1
+| u8, unknown. Written to outptr+1.
+|-
+| 0x2EA
+| 0x1
+| u8, unknown. Written to outptr+0.
+|-
+| 0x2EB
+| 0x1
+| u8, unknown. Written to outptr+3.
+|-
+| 0x2EC
+| 0x1
+| u8, unknown. Written to outptr+4.
+|-
+| 0x2ED
+| 0x1
+| u8, unknown. Written to outptr+7.
+|-
+| 0x2EE
+| 0x1
+| u8, unknown. Written to outptr+6.
+|-
+| 0x2EF
+| 0x1
+| u8, unknown. Written to outptr+5.
|}
|}
−==== Icon gfx frame ====
+If the u16 at frameheader+0x6 is less than 0x101, the 8-bytes at outptr are cleared to all-zero, instead of copying the data from offset 0x2E8.
+===== Icon gfx frame =====
{| class="wikitable" border="1"
{| class="wikitable" border="1"
|-
|-
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| 0x0
| 0x0
| 0x598
| 0x598
−|
+| Array of 0x2CC u16s for the gfx data.
|}
|}
−==== Sysupdate titlelist frame ====
+===== Sysupdate titlelist frame =====
{| class="wikitable" border="1"
{| class="wikitable" border="1"
|-
|-