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// Copyright 2020 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//! This module provides a `Sink` and `Stream` for length-delimited
//! Noise protocol messages in form of [`NoiseFramed`].
use crate::io::Output;
use crate::{protocol::PublicKey, Error};
use bytes::{Bytes, BytesMut};
use futures::prelude::*;
use futures::ready;
use log::{debug, trace};
use std::{
fmt, io,
pin::Pin,
task::{Context, Poll},
};
/// Max. size of a noise message.
const MAX_NOISE_MSG_LEN: usize = 65535;
/// Space given to the encryption buffer to hold key material.
const EXTRA_ENCRYPT_SPACE: usize = 1024;
/// Max. length for Noise protocol message payloads.
pub(crate) const MAX_FRAME_LEN: usize = MAX_NOISE_MSG_LEN - EXTRA_ENCRYPT_SPACE;
static_assertions::const_assert! {
MAX_FRAME_LEN + EXTRA_ENCRYPT_SPACE <= MAX_NOISE_MSG_LEN
}
/// A `NoiseFramed` is a `Sink` and `Stream` for length-delimited
/// Noise protocol messages.
///
/// `T` is the type of the underlying I/O resource and `S` the
/// type of the Noise session state.
pub(crate) struct NoiseFramed<T, S> {
io: T,
session: S,
read_state: ReadState,
write_state: WriteState,
read_buffer: Vec<u8>,
write_buffer: Vec<u8>,
decrypt_buffer: BytesMut,
}
impl<T, S> fmt::Debug for NoiseFramed<T, S> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("NoiseFramed")
.field("read_state", &self.read_state)
.field("write_state", &self.write_state)
.finish()
}
}
impl<T> NoiseFramed<T, snow::HandshakeState> {
/// Creates a nwe `NoiseFramed` for beginning a Noise protocol handshake.
pub(crate) fn new(io: T, state: snow::HandshakeState) -> Self {
NoiseFramed {
io,
session: state,
read_state: ReadState::Ready,
write_state: WriteState::Ready,
read_buffer: Vec::new(),
write_buffer: Vec::new(),
decrypt_buffer: BytesMut::new(),
}
}
pub(crate) fn is_initiator(&self) -> bool {
self.session.is_initiator()
}
pub(crate) fn is_responder(&self) -> bool {
!self.session.is_initiator()
}
/// Converts the `NoiseFramed` into a `NoiseOutput` encrypted data stream
/// once the handshake is complete, including the static DH [`PublicKey`]
/// of the remote, if received.
///
/// If the underlying Noise protocol session state does not permit
/// transitioning to transport mode because the handshake is incomplete,
/// an error is returned. Similarly if the remote's static DH key, if
/// present, cannot be parsed.
pub(crate) fn into_transport(self) -> Result<(PublicKey, Output<T>), Error> {
let dh_remote_pubkey = self.session.get_remote_static().ok_or_else(|| {
Error::Io(io::Error::new(
io::ErrorKind::Other,
"expect key to always be present at end of XX session",
))
})?;
let dh_remote_pubkey = PublicKey::from_slice(dh_remote_pubkey)?;
let io = NoiseFramed {
session: self.session.into_transport_mode()?,
io: self.io,
read_state: ReadState::Ready,
write_state: WriteState::Ready,
read_buffer: self.read_buffer,
write_buffer: self.write_buffer,
decrypt_buffer: self.decrypt_buffer,
};
Ok((dh_remote_pubkey, Output::new(io)))
}
}
/// The states for reading Noise protocol frames.
#[derive(Debug)]
enum ReadState {
/// Ready to read another frame.
Ready,
/// Reading frame length.
ReadLen { buf: [u8; 2], off: usize },
/// Reading frame data.
ReadData { len: usize, off: usize },
/// EOF has been reached (terminal state).
///
/// The associated result signals if the EOF was unexpected or not.
Eof(Result<(), ()>),
/// A decryption error occurred (terminal state).
DecErr,
}
/// The states for writing Noise protocol frames.
#[derive(Debug)]
enum WriteState {
/// Ready to write another frame.
Ready,
/// Writing the frame length.
WriteLen {
len: usize,
buf: [u8; 2],
off: usize,
},
/// Writing the frame data.
WriteData { len: usize, off: usize },
/// EOF has been reached unexpectedly (terminal state).
Eof,
/// An encryption error occurred (terminal state).
EncErr,
}
impl WriteState {
fn is_ready(&self) -> bool {
if let WriteState::Ready = self {
return true;
}
false
}
}
impl<T, S> futures::stream::Stream for NoiseFramed<T, S>
where
T: AsyncRead + Unpin,
S: SessionState + Unpin,
{
type Item = io::Result<Bytes>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = Pin::into_inner(self);
loop {
trace!("read state: {:?}", this.read_state);
match this.read_state {
ReadState::Ready => {
this.read_state = ReadState::ReadLen {
buf: [0, 0],
off: 0,
};
}
ReadState::ReadLen { mut buf, mut off } => {
let n = match read_frame_len(&mut this.io, cx, &mut buf, &mut off) {
Poll::Ready(Ok(Some(n))) => n,
Poll::Ready(Ok(None)) => {
trace!("read: eof");
this.read_state = ReadState::Eof(Ok(()));
return Poll::Ready(None);
}
Poll::Ready(Err(e)) => return Poll::Ready(Some(Err(e))),
Poll::Pending => {
this.read_state = ReadState::ReadLen { buf, off };
return Poll::Pending;
}
};
trace!("read: frame len = {}", n);
if n == 0 {
trace!("read: empty frame");
this.read_state = ReadState::Ready;
continue;
}
this.read_buffer.resize(usize::from(n), 0u8);
this.read_state = ReadState::ReadData {
len: usize::from(n),
off: 0,
}
}
ReadState::ReadData { len, ref mut off } => {
let n = {
let f =
Pin::new(&mut this.io).poll_read(cx, &mut this.read_buffer[*off..len]);
match ready!(f) {
Ok(n) => n,
Err(e) => return Poll::Ready(Some(Err(e))),
}
};
trace!("read: {}/{} bytes", *off + n, len);
if n == 0 {
trace!("read: eof");
this.read_state = ReadState::Eof(Err(()));
return Poll::Ready(Some(Err(io::ErrorKind::UnexpectedEof.into())));
}
*off += n;
if len == *off {
trace!("read: decrypting {} bytes", len);
this.decrypt_buffer.resize(len, 0);
if let Ok(n) = this
.session
.read_message(&this.read_buffer, &mut this.decrypt_buffer)
{
this.decrypt_buffer.truncate(n);
trace!("read: payload len = {} bytes", n);
this.read_state = ReadState::Ready;
// Return an immutable view into the current buffer.
// If the view is dropped before the next frame is
// read, the `BytesMut` will reuse the same buffer
// for the next frame.
let view = this.decrypt_buffer.split().freeze();
return Poll::Ready(Some(Ok(view)));
} else {
debug!("read: decryption error");
this.read_state = ReadState::DecErr;
return Poll::Ready(Some(Err(io::ErrorKind::InvalidData.into())));
}
}
}
ReadState::Eof(Ok(())) => {
trace!("read: eof");
return Poll::Ready(None);
}
ReadState::Eof(Err(())) => {
trace!("read: eof (unexpected)");
return Poll::Ready(Some(Err(io::ErrorKind::UnexpectedEof.into())));
}
ReadState::DecErr => {
return Poll::Ready(Some(Err(io::ErrorKind::InvalidData.into())))
}
}
}
}
}
impl<T, S> futures::sink::Sink<&Vec<u8>> for NoiseFramed<T, S>
where
T: AsyncWrite + Unpin,
S: SessionState + Unpin,
{
type Error = io::Error;
fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
let this = Pin::into_inner(self);
loop {
trace!("write state {:?}", this.write_state);
match this.write_state {
WriteState::Ready => {
return Poll::Ready(Ok(()));
}
WriteState::WriteLen { len, buf, mut off } => {
trace!("write: frame len ({}, {:?}, {}/2)", len, buf, off);
match write_frame_len(&mut this.io, cx, &buf, &mut off) {
Poll::Ready(Ok(true)) => (),
Poll::Ready(Ok(false)) => {
trace!("write: eof");
this.write_state = WriteState::Eof;
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
Poll::Pending => {
this.write_state = WriteState::WriteLen { len, buf, off };
return Poll::Pending;
}
}
this.write_state = WriteState::WriteData { len, off: 0 }
}
WriteState::WriteData { len, ref mut off } => {
let n = {
let f =
Pin::new(&mut this.io).poll_write(cx, &this.write_buffer[*off..len]);
match ready!(f) {
Ok(n) => n,
Err(e) => return Poll::Ready(Err(e)),
}
};
if n == 0 {
trace!("write: eof");
this.write_state = WriteState::Eof;
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
*off += n;
trace!("write: {}/{} bytes written", *off, len);
if len == *off {
trace!("write: finished with {} bytes", len);
this.write_state = WriteState::Ready;
}
}
WriteState::Eof => {
trace!("write: eof");
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
WriteState::EncErr => return Poll::Ready(Err(io::ErrorKind::InvalidData.into())),
}
}
}
fn start_send(self: Pin<&mut Self>, frame: &Vec<u8>) -> Result<(), Self::Error> {
assert!(frame.len() <= MAX_FRAME_LEN);
let this = Pin::into_inner(self);
assert!(this.write_state.is_ready());
this.write_buffer
.resize(frame.len() + EXTRA_ENCRYPT_SPACE, 0u8);
match this
.session
.write_message(frame, &mut this.write_buffer[..])
{
Ok(n) => {
trace!("write: cipher text len = {} bytes", n);
this.write_buffer.truncate(n);
this.write_state = WriteState::WriteLen {
len: n,
buf: u16::to_be_bytes(n as u16),
off: 0,
};
Ok(())
}
Err(e) => {
log::error!("encryption error: {:?}", e);
this.write_state = WriteState::EncErr;
Err(io::ErrorKind::InvalidData.into())
}
}
}
fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
ready!(self.as_mut().poll_ready(cx))?;
Pin::new(&mut self.io).poll_flush(cx)
}
fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
ready!(self.as_mut().poll_flush(cx))?;
Pin::new(&mut self.io).poll_close(cx)
}
}
/// A stateful context in which Noise protocol messages can be read and written.
pub(crate) trait SessionState {
fn read_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error>;
fn write_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error>;
}
impl SessionState for snow::HandshakeState {
fn read_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error> {
self.read_message(msg, buf)
}
fn write_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error> {
self.write_message(msg, buf)
}
}
impl SessionState for snow::TransportState {
fn read_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error> {
self.read_message(msg, buf)
}
fn write_message(&mut self, msg: &[u8], buf: &mut [u8]) -> Result<usize, snow::Error> {
self.write_message(msg, buf)
}
}
/// Read 2 bytes as frame length from the given source into the given buffer.
///
/// Panics if `off >= 2`.
///
/// When [`Poll::Pending`] is returned, the given buffer and offset
/// may have been updated (i.e. a byte may have been read) and must be preserved
/// for the next invocation.
///
/// Returns `None` if EOF has been encountered.
fn read_frame_len<R: AsyncRead + Unpin>(
mut io: &mut R,
cx: &mut Context<'_>,
buf: &mut [u8; 2],
off: &mut usize,
) -> Poll<io::Result<Option<u16>>> {
loop {
match ready!(Pin::new(&mut io).poll_read(cx, &mut buf[*off..])) {
Ok(n) => {
if n == 0 {
return Poll::Ready(Ok(None));
}
*off += n;
if *off == 2 {
return Poll::Ready(Ok(Some(u16::from_be_bytes(*buf))));
}
}
Err(e) => {
return Poll::Ready(Err(e));
}
}
}
}
/// Write 2 bytes as frame length from the given buffer into the given sink.
///
/// Panics if `off >= 2`.
///
/// When [`Poll::Pending`] is returned, the given offset
/// may have been updated (i.e. a byte may have been written) and must
/// be preserved for the next invocation.
///
/// Returns `false` if EOF has been encountered.
fn write_frame_len<W: AsyncWrite + Unpin>(
mut io: &mut W,
cx: &mut Context<'_>,
buf: &[u8; 2],
off: &mut usize,
) -> Poll<io::Result<bool>> {
loop {
match ready!(Pin::new(&mut io).poll_write(cx, &buf[*off..])) {
Ok(n) => {
if n == 0 {
return Poll::Ready(Ok(false));
}
*off += n;
if *off == 2 {
return Poll::Ready(Ok(true));
}
}
Err(e) => {
return Poll::Ready(Err(e));
}
}
}
}