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101 lines
2.8 KiB
Rust
101 lines
2.8 KiB
Rust
use std::io;
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use curve25519_dalek::{scalar::Scalar, edwards::{EdwardsPoint, CompressedEdwardsY}};
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pub const VARINT_CONTINUATION_MASK: u8 = 0b1000_0000;
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pub fn write_varint<W: io::Write>(varint: &u64, w: &mut W) -> io::Result<()> {
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let mut varint = *varint;
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while {
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let mut b = (varint & u64::from(!VARINT_CONTINUATION_MASK)) as u8;
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varint >>= 7;
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if varint != 0 {
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b |= VARINT_CONTINUATION_MASK;
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}
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w.write_all(&[b])?;
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varint != 0
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} {}
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Ok(())
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}
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pub fn write_scalar<W: io::Write>(scalar: &Scalar, w: &mut W) -> io::Result<()> {
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w.write_all(&scalar.to_bytes())
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}
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pub fn write_point<W: io::Write>(point: &EdwardsPoint, w: &mut W) -> io::Result<()> {
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w.write_all(&point.compress().to_bytes())
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}
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pub fn write_raw_vec<
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T,
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W: io::Write,
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F: Fn(&T, &mut W) -> io::Result<()>
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>(f: F, values: &[T], w: &mut W) -> io::Result<()> {
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for value in values {
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f(value, w)?;
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}
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Ok(())
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}
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pub fn write_vec<
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T,
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W: io::Write,
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F: Fn(&T, &mut W) -> io::Result<()>
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>(f: F, values: &[T], w: &mut W) -> io::Result<()> {
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write_varint(&values.len().try_into().unwrap(), w)?;
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write_raw_vec(f, &values, w)
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}
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pub fn read_byte<R: io::Read>(r: &mut R) -> io::Result<u8> {
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let mut res = [0; 1];
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r.read_exact(&mut res)?;
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Ok(res[0])
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}
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pub fn read_varint<R: io::Read>(r: &mut R) -> io::Result<u64> {
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let mut bits = 0;
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let mut res = 0;
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while {
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let b = read_byte(r)?;
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res += u64::from(b & (!VARINT_CONTINUATION_MASK)) << bits;
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// TODO: Error if bits exceed u64
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bits += 7;
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b & VARINT_CONTINUATION_MASK == VARINT_CONTINUATION_MASK
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} {}
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Ok(res)
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}
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pub fn read_32<R: io::Read>(r: &mut R) -> io::Result<[u8; 32]> {
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let mut res = [0; 32];
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r.read_exact(&mut res)?;
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Ok(res)
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}
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// TODO: Potentially update to Monero's parsing rules on scalars/points, which should be any arbitrary 32-bytes
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// We may be able to consider such transactions as malformed and accordingly be opinionated in ignoring them
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pub fn read_scalar<R: io::Read>(r: &mut R) -> io::Result<Scalar> {
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Scalar::from_canonical_bytes(
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read_32(r)?
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).ok_or(io::Error::new(io::ErrorKind::Other, "unreduced scalar"))
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}
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pub fn read_point<R: io::Read>(r: &mut R) -> io::Result<EdwardsPoint> {
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CompressedEdwardsY(
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read_32(r)?
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).decompress().filter(|point| point.is_torsion_free()).ok_or(io::Error::new(io::ErrorKind::Other, "invalid point"))
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}
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pub fn read_raw_vec<R: io::Read, T, F: Fn(&mut R) -> io::Result<T>>(f: F, len: usize, r: &mut R) -> io::Result<Vec<T>> {
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let mut res = Vec::with_capacity(
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len.try_into().map_err(|_| io::Error::new(io::ErrorKind::Other, "length exceeds usize"))?
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);
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for _ in 0 .. len {
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res.push(f(r)?);
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}
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Ok(res)
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}
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pub fn read_vec<R: io::Read, T, F: Fn(&mut R) -> io::Result<T>>(f: F, r: &mut R) -> io::Result<Vec<T>> {
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read_raw_vec(f, read_varint(r)?.try_into().unwrap(), r)
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}
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