bitcoin_block_parser/
xor.rs

1//! Handles XOR'd Bitcoin-core block data.
2//!
3//! - See https://github.com/bitcoin/bitcoin/pull/28052
4
5use std::io::{Read, Seek, SeekFrom};
6
7/// XOR mask length. It's the length of file `blocks/xor.dat`.
8pub const XOR_MASK_LEN: usize = 8;
9
10/// Transparent reader for XOR'd blk*.dat files.
11pub struct XorReader<R: Read> {
12    /// Inner reader.
13    inner: R,
14    /// Stream position. This is expected to be synchronous with [`Seek::stream_position`],
15    /// but without a syscall to fetch it.
16    pos: u64,
17    /// XOR mask if one exists.
18    mask: Option<[u8; XOR_MASK_LEN]>,
19}
20
21impl<R: Read> XorReader<R> {
22    /// Create a reader wrapper that performs XOR on reads.
23    pub fn new(reader: R, xor_mask: Option<[u8; 8]>) -> Self {
24        Self {
25            inner: reader,
26            pos: 0,
27            mask: xor_mask,
28        }
29    }
30}
31
32impl<R: Read> Read for XorReader<R> {
33    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
34        let size = self.inner.read(buf)?;
35        if let Some(mask) = self.mask {
36            for x in &mut buf[..size] {
37                *x ^= mask[(self.pos % mask.len() as u64) as usize];
38                self.pos += 1;
39            }
40        }
41        Ok(size)
42    }
43}
44
45impl<R: Seek + Read> Seek for XorReader<R> {
46    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
47        let result = self.inner.seek(pos);
48        // Just use a syscall to update the current position.
49        self.pos = self.inner.stream_position()?;
50        result
51    }
52}
bitcoin_block_parser/xor.rs

bitcoin_block_parser/
xor.rs
