diff options
Diffstat (limited to 'tvix/nix-compat/src/wire/bytes/reader.rs')
| -rw-r--r-- | tvix/nix-compat/src/wire/bytes/reader.rs | 464 |
1 files changed, 0 insertions, 464 deletions
diff --git a/tvix/nix-compat/src/wire/bytes/reader.rs b/tvix/nix-compat/src/wire/bytes/reader.rs deleted file mode 100644 index c36729c614..0000000000 --- a/tvix/nix-compat/src/wire/bytes/reader.rs +++ /dev/null @@ -1,464 +0,0 @@ -use pin_project_lite::pin_project; -use std::{ - ops::RangeBounds, - task::{ready, Poll}, -}; -use tokio::io::AsyncRead; - -use super::{padding_len, BytesPacketPosition, LEN_SIZE}; - -pin_project! { - /// Reads a "bytes wire packet" from the underlying reader. - /// The format is the same as in [crate::wire::bytes::read_bytes], - /// however this structure provides a [AsyncRead] interface, - /// allowing to not having to pass around the entire payload in memory. - /// - /// After being constructed with the underlying reader and an allowed size, - /// subsequent requests to poll_read will return payload data until the end - /// of the packet is reached. - /// - /// Internally, it will first read over the size packet, filling payload_size, - /// ensuring it fits allowed_size, then return payload data. - /// It will only signal EOF (returning `Ok(())` without filling the buffer anymore) - /// when all padding has been successfully consumed too. - /// - /// This also means, it's important for a user to always read to the end, - /// and not just call read_exact - otherwise it might not skip over the - /// padding, and return garbage when reading the next packet. - /// - /// In case of an error due to size constraints, or in case of not reading - /// all the way to the end (and getting a EOF), the underlying reader is no - /// longer usable and might return garbage. - pub struct BytesReader<R, S> - where - R: AsyncRead, - S: RangeBounds<u64>, - - { - #[pin] - inner: R, - - allowed_size: S, - payload_size: [u8; 8], - state: BytesPacketPosition, - } -} - -impl<R, S> BytesReader<R, S> -where - R: AsyncRead + Unpin, - S: RangeBounds<u64>, -{ - /// Constructs a new BytesReader, using the underlying passed reader. - pub fn new(r: R, allowed_size: S) -> Self { - Self { - inner: r, - allowed_size, - payload_size: [0; 8], - state: BytesPacketPosition::Size(0), - } - } -} -/// Returns an error if the passed usize is 0. -#[inline] -fn ensure_nonzero_bytes_read(bytes_read: usize) -> Result<usize, std::io::Error> { - if bytes_read == 0 { - Err(std::io::Error::new( - std::io::ErrorKind::UnexpectedEof, - "underlying reader returned EOF", - )) - } else { - Ok(bytes_read) - } -} - -impl<R, S> AsyncRead for BytesReader<R, S> -where - R: AsyncRead, - S: RangeBounds<u64>, -{ - fn poll_read( - self: std::pin::Pin<&mut Self>, - cx: &mut std::task::Context<'_>, - buf: &mut tokio::io::ReadBuf<'_>, - ) -> Poll<std::io::Result<()>> { - let mut this = self.project(); - - // Use a loop, so we can deal with (multiple) state transitions. - loop { - match *this.state { - BytesPacketPosition::Size(LEN_SIZE) => { - // used in case an invalid size was signalled. - Err(std::io::Error::new( - std::io::ErrorKind::InvalidData, - "signalled package size not in allowed range", - ))? - } - BytesPacketPosition::Size(pos) => { - // try to read more of the size field. - // We wrap a BufRead around this.payload_size here, and set_filled. - let mut read_buf = tokio::io::ReadBuf::new(this.payload_size); - read_buf.advance(pos); - ready!(this.inner.as_mut().poll_read(cx, &mut read_buf))?; - - ensure_nonzero_bytes_read(read_buf.filled().len() - pos)?; - - let total_size_read = read_buf.filled().len(); - if total_size_read == LEN_SIZE { - // If the entire payload size was read, parse it - let payload_size = u64::from_le_bytes(*this.payload_size); - - if !this.allowed_size.contains(&payload_size) { - // If it's not in the allowed - // range, transition to failure mode - // `BytesPacketPosition::Size(LEN_SIZE)`, where only - // an error is returned. - *this.state = BytesPacketPosition::Size(LEN_SIZE) - } else if payload_size == 0 { - // If the payload size is 0, move on to reading padding directly. - *this.state = BytesPacketPosition::Padding(0) - } else { - // Else, transition to reading the payload. - *this.state = BytesPacketPosition::Payload(0) - } - } else { - // If we still need to read more of payload size, update - // our position in the state. - *this.state = BytesPacketPosition::Size(total_size_read) - } - } - BytesPacketPosition::Payload(pos) => { - let signalled_size = u64::from_le_bytes(*this.payload_size); - // We don't enter this match arm at all if we're expecting empty payload - debug_assert!(signalled_size > 0, "signalled size must be larger than 0"); - - // Read from the underlying reader into buf - // We cap the ReadBuf to the size of the payload, as we - // don't want to leak padding to the caller. - let bytes_read = ensure_nonzero_bytes_read({ - // Reducing these two u64 to usize on 32bits is fine - we - // only care about not reading too much, not too less. - let mut limited_buf = buf.take((signalled_size - pos) as usize); - ready!(this.inner.as_mut().poll_read(cx, &mut limited_buf))?; - limited_buf.filled().len() - })?; - - // SAFETY: we just did populate this, but through limited_buf. - unsafe { buf.assume_init(bytes_read) } - buf.advance(bytes_read); - - if pos + bytes_read as u64 == signalled_size { - // If we now read all payload, transition to padding - // state. - *this.state = BytesPacketPosition::Padding(0); - } else { - // if we didn't read everything yet, update our position - // in the state. - *this.state = BytesPacketPosition::Payload(pos + bytes_read as u64); - } - - // We return from poll_read here. - // This is important, as any error (or even Pending) from - // the underlying reader on the next read (be it padding or - // payload) would require us to roll back buf, as generally - // a AsyncRead::poll_read may not advance the buffer in case - // of a nonsuccessful read. - // It can't be misinterpreted as EOF, as we definitely *did* - // write something into buf if we come to here (we pass - // `ensure_nonzero_bytes_read`). - return Ok(()).into(); - } - BytesPacketPosition::Padding(pos) => { - // Consume whatever padding is left, ensuring it's all null - // bytes. Only return `Ready(Ok(()))` once we're past the - // padding (or in cases where polling the inner reader - // returns `Poll::Pending`). - let signalled_size = u64::from_le_bytes(*this.payload_size); - let total_padding_len = padding_len(signalled_size) as usize; - - let padding_len_remaining = total_padding_len - pos; - if padding_len_remaining != 0 { - // create a buffer only accepting the number of remaining padding bytes. - let mut buf = [0; 8]; - let mut padding_buf = tokio::io::ReadBuf::new(&mut buf); - let mut padding_buf = padding_buf.take(padding_len_remaining); - - // read into padding_buf. - ready!(this.inner.as_mut().poll_read(cx, &mut padding_buf))?; - let bytes_read = ensure_nonzero_bytes_read(padding_buf.filled().len())?; - - *this.state = BytesPacketPosition::Padding(pos + bytes_read); - - // ensure the bytes are not null bytes - if !padding_buf.filled().iter().all(|e| *e == b'\0') { - return Err(std::io::Error::new( - std::io::ErrorKind::InvalidData, - "padding is not all zeroes", - )) - .into(); - } - - // if we still have padding to read, run the loop again. - continue; - } - // return EOF - return Ok(()).into(); - } - } - } - } -} - -#[cfg(test)] -mod tests { - use std::time::Duration; - - use crate::wire::bytes::write_bytes; - use hex_literal::hex; - use lazy_static::lazy_static; - use rstest::rstest; - use tokio::io::AsyncReadExt; - use tokio_test::{assert_err, io::Builder}; - - use super::*; - - /// The maximum length of bytes packets we're willing to accept in the test - /// cases. - const MAX_LEN: u64 = 1024; - - lazy_static! { - pub static ref LARGE_PAYLOAD: Vec<u8> = (0..255).collect::<Vec<u8>>().repeat(4 * 1024); - } - - /// Helper function, calling the (simpler) write_bytes with the payload. - /// We use this to create data we want to read from the wire. - async fn produce_packet_bytes(payload: &[u8]) -> Vec<u8> { - let mut exp = vec![]; - write_bytes(&mut exp, payload).await.unwrap(); - exp - } - - /// Read bytes packets of various length, and ensure read_to_end returns the - /// expected payload. - #[rstest] - #[case::empty(&[])] // empty bytes packet - #[case::size_1b(&[0xff])] // 1 bytes payload - #[case::size_8b(&hex!("0001020304050607"))] // 8 bytes payload (no padding) - #[case::size_9b( &hex!("000102030405060708"))] // 9 bytes payload (7 bytes padding) - #[case::size_1m(LARGE_PAYLOAD.as_slice())] // larger bytes packet - #[tokio::test] - async fn read_payload_correct(#[case] payload: &[u8]) { - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await) - .build(); - - let mut r = BytesReader::new(&mut mock, ..=LARGE_PAYLOAD.len() as u64); - let mut buf = Vec::new(); - r.read_to_end(&mut buf).await.expect("must succeed"); - - assert_eq!(payload, &buf[..]); - } - - /// Fail if the bytes packet is larger than allowed - #[tokio::test] - async fn read_bigger_than_allowed_fail() { - let payload = LARGE_PAYLOAD.as_slice(); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[0..8]) // We stop reading after the size packet - .build(); - - let mut r = BytesReader::new(&mut mock, ..2048); - let mut buf = Vec::new(); - assert_err!(r.read_to_end(&mut buf).await); - } - - /// Fail if the bytes packet is smaller than allowed - #[tokio::test] - async fn read_smaller_than_allowed_fail() { - let payload = &[0x00, 0x01, 0x02]; - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[0..8]) // We stop reading after the size packet - .build(); - - let mut r = BytesReader::new(&mut mock, 1024..2048); - let mut buf = Vec::new(); - assert_err!(r.read_to_end(&mut buf).await); - } - - /// Fail if the padding is not all zeroes - #[tokio::test] - async fn read_fail_if_nonzero_padding() { - let payload = &[0x00, 0x01, 0x02]; - let mut packet_bytes = produce_packet_bytes(payload).await; - // Flip some bits in the padding - packet_bytes[12] = 0xff; - let mut mock = Builder::new().read(&packet_bytes).build(); // We stop reading after the faulty bit - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = Vec::new(); - - r.read_to_end(&mut buf).await.expect_err("must fail"); - } - - /// Start a 9 bytes payload packet, but have the underlying reader return - /// EOF in the middle of the size packet (after 4 bytes). - /// We should get an unexpected EOF error, already when trying to read the - /// first byte (of payload) - #[tokio::test] - async fn read_9b_eof_during_size() { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..4]) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = [0u8; 1]; - - assert_eq!( - r.read_exact(&mut buf).await.expect_err("must fail").kind(), - std::io::ErrorKind::UnexpectedEof - ); - - assert_eq!(&[0], &buf, "buffer should stay empty"); - } - - /// Start a 9 bytes payload packet, but have the underlying reader return - /// EOF in the middle of the payload (4 bytes into the payload). - /// We should get an unexpected EOF error, after reading the first 4 bytes - /// (successfully). - #[tokio::test] - async fn read_9b_eof_during_payload() { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..8 + 4]) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = [0; 9]; - - r.read_exact(&mut buf[..4]).await.expect("must succeed"); - - assert_eq!( - r.read_exact(&mut buf[4..=4]) - .await - .expect_err("must fail") - .kind(), - std::io::ErrorKind::UnexpectedEof - ); - } - - /// Start a 9 bytes payload packet, but return an error at various stages *after* the actual payload. - /// read_exact with a 9 bytes buffer is expected to succeed, but any further - /// read, as well as read_to_end are expected to fail. - #[rstest] - #[case::before_padding(8 + 9)] - #[case::during_padding(8 + 9 + 2)] - #[case::after_padding(8 + 9 + padding_len(9) as usize)] - #[tokio::test] - async fn read_9b_eof_after_payload(#[case] offset: usize) { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..offset]) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = [0; 9]; - - // read_exact of the payload will succeed, but a subsequent read will - // return UnexpectedEof error. - r.read_exact(&mut buf).await.expect("should succeed"); - assert_eq!( - r.read_exact(&mut buf[4..=4]) - .await - .expect_err("must fail") - .kind(), - std::io::ErrorKind::UnexpectedEof - ); - - // read_to_end will fail. - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..8 + payload.len()]) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = Vec::new(); - assert_eq!( - r.read_to_end(&mut buf).await.expect_err("must fail").kind(), - std::io::ErrorKind::UnexpectedEof - ); - } - - /// Start a 9 bytes payload packet, but return an error after a certain position. - /// Ensure that error is propagated. - #[rstest] - #[case::during_size(4)] - #[case::before_payload(8)] - #[case::during_payload(8 + 4)] - #[case::before_padding(8 + 4)] - #[case::during_padding(8 + 9 + 2)] - #[tokio::test] - async fn propagate_error_from_reader(#[case] offset: usize) { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..offset]) - .read_error(std::io::Error::new(std::io::ErrorKind::Other, "foo")) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = Vec::new(); - - let err = r.read_to_end(&mut buf).await.expect_err("must fail"); - assert_eq!( - err.kind(), - std::io::ErrorKind::Other, - "error kind must match" - ); - - assert_eq!( - err.into_inner().unwrap().to_string(), - "foo", - "error payload must contain foo" - ); - } - - /// If there's an error right after the padding, we don't propagate it, as - /// we're done reading. We just return EOF. - #[tokio::test] - async fn no_error_after_eof() { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await) - .read_error(std::io::Error::new(std::io::ErrorKind::Other, "foo")) - .build(); - - let mut r = BytesReader::new(&mut mock, ..MAX_LEN); - let mut buf = Vec::new(); - - r.read_to_end(&mut buf).await.expect("must succeed"); - assert_eq!(buf.as_slice(), payload); - } - - /// Introduce various stalls in various places of the packet, to ensure we - /// handle these cases properly, too. - #[rstest] - #[case::beginning(0)] - #[case::before_payload(8)] - #[case::during_payload(8 + 4)] - #[case::before_padding(8 + 4)] - #[case::during_padding(8 + 9 + 2)] - #[tokio::test] - async fn read_payload_correct_pending(#[case] offset: usize) { - let payload = &hex!("FF0102030405060708"); - let mut mock = Builder::new() - .read(&produce_packet_bytes(payload).await[..offset]) - .wait(Duration::from_nanos(0)) - .read(&produce_packet_bytes(payload).await[offset..]) - .build(); - - let mut r = BytesReader::new(&mut mock, ..=LARGE_PAYLOAD.len() as u64); - let mut buf = Vec::new(); - r.read_to_end(&mut buf).await.expect("must succeed"); - - assert_eq!(payload, &buf[..]); - } -} |