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use std::ops::RangeBounds;
use tokio::io::AsyncReadExt;
use super::primitive;
#[allow(dead_code)]
/// Read a limited number of bytes from the AsyncRead.
/// Rejects reading more than `allowed_size` bytes of payload.
/// Internally takes care of dealing with the padding, so the returned `Vec<u8>`
/// only contains the payload.
/// This always buffers the entire contents into memory, we'll add a streaming
/// version later.
pub async fn read_bytes<R, S>(r: &mut R, allowed_size: S) -> std::io::Result<Vec<u8>>
where
R: AsyncReadExt + Unpin,
S: RangeBounds<u64>,
{
// read the length field
let len = primitive::read_u64(r).await?;
if !allowed_size.contains(&len) {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidData,
"signalled package size not in allowed range",
));
}
// calculate the total length, including padding.
// byte packets are padded to 8 byte blocks each.
let padded_len = if len % 8 == 0 {
len
} else {
len + (8 - len % 8)
};
let mut limited_reader = r.take(padded_len);
let mut buf = Vec::new();
let s = limited_reader.read_to_end(&mut buf).await?;
// make sure we got exactly the number of bytes, and not less.
if s as u64 != padded_len {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidData,
"got less bytes than expected",
));
}
let (_content, padding) = buf.split_at(len as usize);
// ensure the padding is all zeroes.
if !padding.iter().all(|e| *e == b'\0') {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidData,
"padding is not all zeroes",
));
}
// return the data without the padding
buf.truncate(len as usize);
Ok(buf)
}
#[allow(dead_code)]
/// Read an unlimited number of bytes from the AsyncRead.
/// Note this can exhaust memory.
/// Internally uses [read_bytes], which takes care of dealing with the padding,
/// so the returned `Vec<u8>` only contains the payload.
pub async fn read_bytes_unchecked<R: AsyncReadExt + Unpin>(r: &mut R) -> std::io::Result<Vec<u8>> {
read_bytes(r, 0u64..).await
}
#[cfg(test)]
mod tests {
use tokio_test::io::Builder;
use super::*;
use hex_literal::hex;
#[tokio::test]
async fn test_read_8_bytes_unchecked() {
let mut mock = Builder::new()
.read(&8u64.to_le_bytes())
.read(&12345678u64.to_le_bytes())
.build();
assert_eq!(
&12345678u64.to_le_bytes(),
read_bytes_unchecked(&mut mock).await.unwrap().as_slice()
);
}
#[tokio::test]
async fn test_read_9_bytes_unchecked() {
let mut mock = Builder::new()
.read(&9u64.to_le_bytes())
.read(&hex!("01020304050607080900000000000000"))
.build();
assert_eq!(
hex!("010203040506070809"),
read_bytes_unchecked(&mut mock).await.unwrap().as_slice()
);
}
#[tokio::test]
async fn test_read_0_bytes_unchecked() {
// A empty byte packet is essentially just the 0 length field.
// No data is read, and there's zero padding.
let mut mock = Builder::new().read(&0u64.to_le_bytes()).build();
assert_eq!(
hex!(""),
read_bytes_unchecked(&mut mock).await.unwrap().as_slice()
);
}
#[tokio::test]
/// Ensure we don't read any further than the size field if the length
/// doesn't match the range we want to accept.
async fn test_reject_too_large() {
let mut mock = Builder::new().read(&100u64.to_le_bytes()).build();
read_bytes(&mut mock, 10..10)
.await
.expect_err("expect this to fail");
}
}
|
