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|
use std::{
pin::Pin,
task::{self, ready, Poll},
};
use tokio::io::{self, AsyncRead, ReadBuf};
#[derive(Debug)]
pub enum TrailerReader<R> {
Reading {
reader: R,
user_len: u8,
filled: u8,
buf: [u8; 8],
},
Releasing {
off: u8,
len: u8,
buf: [u8; 8],
},
Done,
}
impl<R: AsyncRead + Unpin> TrailerReader<R> {
pub fn new(reader: R, user_len: u8) -> Self {
if user_len == 0 {
return Self::Done;
}
assert!(user_len < 8, "payload in trailer must be less than 8 bytes");
Self::Reading {
reader,
user_len,
filled: 0,
buf: [0; 8],
}
}
}
impl<R: AsyncRead + Unpin> AsyncRead for TrailerReader<R> {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut task::Context,
user_buf: &mut ReadBuf,
) -> Poll<io::Result<()>> {
let this = &mut *self;
loop {
match this {
&mut Self::Reading {
reader: _,
user_len,
filled: 8,
buf,
} => {
*this = Self::Releasing {
off: 0,
len: user_len,
buf,
};
}
Self::Reading {
reader,
user_len,
filled,
buf,
} => {
let mut read_buf = ReadBuf::new(&mut buf[..]);
read_buf.advance(*filled as usize);
ready!(Pin::new(reader).poll_read(cx, &mut read_buf))?;
let new_filled = read_buf.filled().len() as u8;
if *filled == new_filled {
return Err(io::ErrorKind::UnexpectedEof.into()).into();
}
*filled = new_filled;
// ensure the padding is all zeroes
if (u64::from_le_bytes(*buf) >> (*user_len * 8)) != 0 {
return Err(io::ErrorKind::InvalidData.into()).into();
}
}
Self::Releasing { off: 8, .. } => {
*this = Self::Done;
}
Self::Releasing { off, len, buf } => {
assert_ne!(user_buf.remaining(), 0);
let buf = &buf[*off as usize..*len as usize];
let buf = &buf[..usize::min(buf.len(), user_buf.remaining())];
user_buf.put_slice(buf);
*off += buf.len() as u8;
break;
}
Self::Done => break,
}
}
Ok(()).into()
}
}
#[cfg(test)]
mod tests {
use std::time::Duration;
use tokio::io::AsyncReadExt;
use super::*;
#[tokio::test]
async fn unexpected_eof() {
let reader = tokio_test::io::Builder::new()
.read(&[0xed])
.wait(Duration::ZERO)
.read(&[0xef, 0x00])
.build();
let mut reader = TrailerReader::new(reader, 2);
let mut buf = vec![];
assert_eq!(
reader.read_to_end(&mut buf).await.unwrap_err().kind(),
io::ErrorKind::UnexpectedEof
);
}
#[tokio::test]
async fn invalid_padding() {
let reader = tokio_test::io::Builder::new()
.read(&[0xed])
.wait(Duration::ZERO)
.read(&[0xef, 0x01, 0x00])
.wait(Duration::ZERO)
.build();
let mut reader = TrailerReader::new(reader, 2);
let mut buf = vec![];
assert_eq!(
reader.read_to_end(&mut buf).await.unwrap_err().kind(),
io::ErrorKind::InvalidData
);
}
#[tokio::test]
async fn success() {
let reader = tokio_test::io::Builder::new()
.read(&[0xed])
.wait(Duration::ZERO)
.read(&[0xef, 0x00])
.wait(Duration::ZERO)
.read(&[0x00, 0x00, 0x00, 0x00, 0x00])
.build();
let mut reader = TrailerReader::new(reader, 2);
let mut buf = vec![];
reader.read_to_end(&mut buf).await.unwrap();
assert_eq!(buf, &[0xed, 0xef]);
}
#[tokio::test]
async fn no_padding() {
let reader = tokio_test::io::Builder::new().build();
let mut reader = TrailerReader::new(reader, 0);
let mut buf = vec![];
reader.read_to_end(&mut buf).await.unwrap();
assert!(buf.is_empty());
}
}
|
