use std::io::{self, Read, Seek, Write};
use tracing::warn;
use crate::{
common::MagicBytes,
disc::DL_DVD_SIZE,
read::{DiscMeta, DiscStream},
util::read::{read_at, read_from, read_u16_be, read_u32_be, read_u64_be, read_vec},
};
#[allow(unused)]
#[repr(u16)]
enum NKitHeaderFlags {
Size = 0x1,
Crc32 = 0x2,
Md5 = 0x4,
Sha1 = 0x8,
Xxhash64 = 0x10,
Key = 0x20,
Encrypted = 0x40,
ExtraData = 0x80,
IndexFile = 0x100,
}
const NKIT_HEADER_V1_FLAGS: u16 = NKitHeaderFlags::Crc32 as u16
| NKitHeaderFlags::Md5 as u16
| NKitHeaderFlags::Sha1 as u16
| NKitHeaderFlags::Xxhash64 as u16;
const fn calc_header_size(version: u8, flags: u16, key_len: u32) -> usize {
let mut size = 8;
if version >= 2 {
size += 4;
}
if flags & NKitHeaderFlags::Size as u16 != 0 {
size += 8;
}
if flags & NKitHeaderFlags::Crc32 as u16 != 0 {
size += 4;
}
if flags & NKitHeaderFlags::Md5 as u16 != 0 {
size += 16;
}
if flags & NKitHeaderFlags::Sha1 as u16 != 0 {
size += 20;
}
if flags & NKitHeaderFlags::Xxhash64 as u16 != 0 {
size += 8;
}
if flags & NKitHeaderFlags::Key as u16 != 0 {
size += key_len as usize + 2;
}
size
}
#[derive(Debug, Clone)]
pub struct NKitHeader {
pub version: u8,
pub size: Option<u64>,
pub crc32: Option<u32>,
pub md5: Option<[u8; 16]>,
pub sha1: Option<[u8; 20]>,
pub xxh64: Option<u64>,
pub junk_bits: Option<JunkBits>,
pub encrypted: bool,
}
impl Default for NKitHeader {
fn default() -> Self {
Self {
version: 2,
size: None,
crc32: None,
md5: None,
sha1: None,
xxh64: None,
junk_bits: None,
encrypted: false,
}
}
}
const VERSION_PREFIX: [u8; 7] = *b"NKIT v";
impl NKitHeader {
pub fn try_read_from(
reader: &mut dyn DiscStream,
pos: u64,
block_size: u32,
has_junk_bits: bool,
) -> Option<Self> {
let magic: MagicBytes = read_at(reader, pos).ok()?;
if magic == *b"NKIT" {
let mut reader = ReadAdapter::new(reader, pos);
match NKitHeader::read_from(&mut reader, block_size, has_junk_bits) {
Ok(header) => Some(header),
Err(e) => {
warn!("Failed to read NKit header: {}", e);
None
}
}
} else {
None
}
}
pub fn read_from<R>(reader: &mut R, block_size: u32, has_junk_bits: bool) -> io::Result<Self>
where R: Read + ?Sized {
let version_string: [u8; 8] = read_from(reader)?;
if version_string[0..7] != VERSION_PREFIX
|| version_string[7] < b'1'
|| version_string[7] > b'9'
{
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Invalid NKit header version string",
));
}
let version = version_string[7] - b'0';
let header_size = match version {
1 => calc_header_size(version, NKIT_HEADER_V1_FLAGS, 0) as u16,
2 => read_u16_be(reader)?,
_ => {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
format!("Unsupported NKit header version: {}", version),
));
}
};
let mut remaining_header_size = header_size as usize - 8;
if version >= 2 {
remaining_header_size -= 2;
}
let header_bytes = read_vec(reader, remaining_header_size)?;
let mut inner = &header_bytes[..];
let flags = if version == 1 { NKIT_HEADER_V1_FLAGS } else { read_u16_be(&mut inner)? };
let size = (flags & NKitHeaderFlags::Size as u16 != 0)
.then(|| read_u64_be(&mut inner))
.transpose()?;
let crc32 = (flags & NKitHeaderFlags::Crc32 as u16 != 0)
.then(|| read_u32_be(&mut inner))
.transpose()?;
let md5 = (flags & NKitHeaderFlags::Md5 as u16 != 0)
.then(|| read_from::<[u8; 16], _>(&mut inner))
.transpose()?;
let sha1 = (flags & NKitHeaderFlags::Sha1 as u16 != 0)
.then(|| read_from::<[u8; 20], _>(&mut inner))
.transpose()?;
let xxh64 = (flags & NKitHeaderFlags::Xxhash64 as u16 != 0)
.then(|| read_u64_be(&mut inner))
.transpose()?;
let junk_bits =
if has_junk_bits { Some(JunkBits::read_from(reader, block_size)?) } else { None };
let encrypted = flags & NKitHeaderFlags::Encrypted as u16 != 0;
Ok(Self { version, size, crc32, md5, sha1, xxh64, junk_bits, encrypted })
}
pub fn is_junk_block(&self, block: u32) -> Option<bool> {
self.junk_bits.as_ref().map(|v| v.get(block))
}
pub fn apply(&self, meta: &mut DiscMeta) {
meta.needs_hash_recovery |= self.junk_bits.is_some();
meta.lossless |= self.size.is_some() && self.junk_bits.is_some();
meta.disc_size = meta.disc_size.or(self.size);
meta.crc32 = self.crc32;
meta.md5 = self.md5;
meta.sha1 = self.sha1;
meta.xxh64 = self.xxh64;
}
fn calc_flags(&self) -> u16 {
let mut flags = 0;
if self.size.is_some() {
flags |= NKitHeaderFlags::Size as u16;
}
if self.crc32.is_some() {
flags |= NKitHeaderFlags::Crc32 as u16;
}
if self.md5.is_some() {
flags |= NKitHeaderFlags::Md5 as u16;
}
if self.sha1.is_some() {
flags |= NKitHeaderFlags::Sha1 as u16;
}
if self.xxh64.is_some() {
flags |= NKitHeaderFlags::Xxhash64 as u16;
}
if self.encrypted {
flags |= NKitHeaderFlags::Encrypted as u16;
}
flags
}
pub fn write_to<W>(&self, w: &mut W) -> io::Result<()>
where W: Write + ?Sized {
w.write_all(&VERSION_PREFIX)?;
w.write_all(&[b'0' + self.version])?;
let flags = self.calc_flags();
match self.version {
1 => {}
2 => {
let header_size = calc_header_size(self.version, flags, 0) as u16;
w.write_all(&header_size.to_be_bytes())?;
w.write_all(&flags.to_be_bytes())?;
}
version => {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
format!("Unsupported NKit header version: {}", version),
));
}
};
if let Some(size) = self.size {
w.write_all(&size.to_be_bytes())?;
}
if let Some(crc32) = self.crc32 {
w.write_all(&crc32.to_be_bytes())?;
} else if self.version == 1 {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Missing CRC32 in NKit v1 header",
));
}
if let Some(md5) = self.md5 {
w.write_all(&md5)?;
} else if self.version == 1 {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Missing MD5 in NKit v1 header",
));
}
if let Some(sha1) = self.sha1 {
w.write_all(&sha1)?;
} else if self.version == 1 {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Missing SHA1 in NKit v1 header",
));
}
if let Some(xxh64) = self.xxh64 {
w.write_all(&xxh64.to_be_bytes())?;
} else if self.version == 1 {
return Err(io::Error::new(
io::ErrorKind::InvalidData,
"Missing XXHash64 in NKit header",
));
}
if let Some(junk_bits) = &self.junk_bits {
junk_bits.write_to(w)?;
}
Ok(())
}
}
#[derive(Debug, Clone)]
pub struct JunkBits(Vec<u8>);
impl JunkBits {
pub fn new(block_size: u32) -> Self { Self(vec![0; Self::len(block_size)]) }
pub fn read_from<R>(reader: &mut R, block_size: u32) -> io::Result<Self>
where R: Read + ?Sized {
Ok(Self(read_vec(reader, Self::len(block_size))?))
}
pub fn write_to<W>(&self, w: &mut W) -> io::Result<()>
where W: Write + ?Sized {
w.write_all(&self.0)
}
pub fn set(&mut self, block: u32, is_junk: bool) {
let Some(byte) = self.0.get_mut((block / 8) as usize) else {
return;
};
if is_junk {
*byte |= 1 << (7 - (block & 7));
} else {
*byte &= !(1 << (7 - (block & 7)));
}
}
pub fn get(&self, block: u32) -> bool {
let Some(&byte) = self.0.get((block / 8) as usize) else {
return false;
};
byte & (1 << (7 - (block & 7))) != 0
}
fn len(block_size: u32) -> usize {
DL_DVD_SIZE.div_ceil(block_size as u64).div_ceil(8) as usize
}
}
pub struct ReadAdapter<'a> {
reader: &'a mut dyn DiscStream,
pos: u64,
}
impl<'a> ReadAdapter<'a> {
pub fn new(reader: &'a mut dyn DiscStream, offset: u64) -> Self { Self { reader, pos: offset } }
}
impl Read for ReadAdapter<'_> {
fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> {
Err(io::Error::from(io::ErrorKind::Unsupported))
}
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
self.reader.read_exact_at(buf, self.pos)?;
self.pos += buf.len() as u64;
Ok(())
}
}
impl Seek for ReadAdapter<'_> {
fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
self.pos = match pos {
io::SeekFrom::Start(pos) => pos,
io::SeekFrom::End(v) => self.reader.stream_len()?.saturating_add_signed(v),
io::SeekFrom::Current(v) => self.pos.saturating_add_signed(v),
};
Ok(self.pos)
}
}