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|
//! TLS server trait implementations for Rustls.
use async_trait::async_trait;
use futures::{AsyncRead, AsyncWrite};
use pin_project::pin_project;
use std::{
borrow::Cow,
io::{Error as IoError, Result as IoResult},
marker::PhantomData,
pin::Pin,
sync::Arc,
task::{Context, Poll},
};
use tracing::instrument;
use crate::{CertifiedConn, StreamOps, tls::TlsAcceptorSettings, tls::TlsConnector};
use futures_rustls::rustls::ServerConfig as RustlsServerConfig;
/// A server-side TLS stream.
///
/// Created by [`RustlsAcceptor`].
#[pin_project]
pub struct RustlsServerStream<S> {
/// The underlying Rustls stream.
///
/// We have to wrap this so that we can also expose the certificate we sent,
/// for use in Tor's link authentication.
#[pin]
stream: futures_rustls::server::TlsStream<S>,
/// The certificate that we sent.
///
/// (If we sent multiple certs, this should be the one corresponding to our private key.)
cert_der: Arc<[u8]>,
}
impl<S: AsyncRead + AsyncWrite + Unpin> AsyncRead for RustlsServerStream<S> {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<IoResult<usize>> {
self.project().stream.poll_read(cx, buf)
}
}
impl<S: AsyncRead + AsyncWrite + Unpin> AsyncWrite for RustlsServerStream<S> {
fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<IoResult<usize>> {
self.project().stream.poll_write(cx, buf)
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<IoResult<()>> {
self.project().stream.poll_flush(cx)
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<IoResult<()>> {
self.project().stream.poll_close(cx)
}
}
impl<S: StreamOps> StreamOps for RustlsServerStream<S> {
fn set_tcp_notsent_lowat(&self, notsent_lowat: u32) -> IoResult<()> {
self.stream.get_ref().0.set_tcp_notsent_lowat(notsent_lowat)
}
fn new_handle(&self) -> Box<dyn StreamOps + Send + Unpin> {
self.stream.get_ref().0.new_handle()
}
}
impl<S: AsyncRead + AsyncWrite + Unpin> CertifiedConn for RustlsServerStream<S> {
fn peer_certificate(&self) -> IoResult<Option<Cow<'_, [u8]>>> {
let (_, session) = self.stream.get_ref();
Ok(session
.peer_certificates()
.and_then(|certs| certs.first().map(|c| Cow::from(c.as_ref()))))
}
fn export_keying_material(
&self,
len: usize,
label: &[u8],
context: Option<&[u8]>,
) -> IoResult<Vec<u8>> {
let (_, session) = self.stream.get_ref();
session
.export_keying_material(vec![0_u8; len], label, context)
.map_err(|e| IoError::new(std::io::ErrorKind::InvalidData, e))
}
fn own_certificate(&self) -> IoResult<Option<Cow<'_, [u8]>>> {
Ok(Some(Cow::from(self.cert_der.as_ref())))
}
}
/// A server implementation for Rustls.
///
/// Accepts asynchronous streams (typically over TCP), and performs the server-side TLS handshake.
#[derive(Clone, derive_more::Debug)]
pub struct RustlsAcceptor<S> {
/// The underlying TLS acceptor.
#[debug(skip)]
acceptor: futures_rustls::TlsAcceptor,
/// The certificate corresponding to our private key.
cert_der: Arc<[u8]>,
/// Phantomdata to mark this type as invariant in S.
_phantom: PhantomData<fn(S) -> S>,
}
#[async_trait]
impl<S> TlsConnector<S> for RustlsAcceptor<S>
where
S: AsyncRead + AsyncWrite + StreamOps + Unpin + Send + 'static,
{
type Conn = RustlsServerStream<S>;
#[instrument(skip_all, level = "trace")]
async fn negotiate_unvalidated(&self, stream: S, sni_hostname: &str) -> IoResult<Self::Conn> {
let _ignore = sni_hostname;
let stream = self.acceptor.accept(stream).await?;
Ok(RustlsServerStream {
stream,
cert_der: Arc::clone(&self.cert_der),
})
}
}
impl<S> RustlsAcceptor<S> {
/// Construct a new RustlsAcceptor from a provided [`TlsAcceptorSettings`]
pub(crate) fn new(settings: &TlsAcceptorSettings) -> IoResult<Self> {
let cert_der = settings.cert_der().into();
let cfg: RustlsServerConfig = rustls_server_config(settings)?;
let acceptor = futures_rustls::TlsAcceptor::from(Arc::new(cfg));
Ok(Self {
acceptor,
cert_der,
_phantom: PhantomData,
})
}
}
/// Try to convert a [`TlsAcceptorSettings`] into a configuration for a rustls server.
///
/// This is not necessarily suitable for general use outside of being a Tor relay.
fn rustls_server_config(settings: &TlsAcceptorSettings) -> IoResult<RustlsServerConfig> {
use futures_rustls::rustls::pki_types as pki;
use futures_rustls::rustls::version::{TLS12, TLS13};
// Convert certificate and key into expected format.
let cert_chain = settings
.identity
.certificates_der()
.into_iter()
.map(|c| pki::CertificateDer::from_slice(c).into_owned())
.collect();
let key_der = settings
.identity
.private_key_pkcs8_der()
.map_err(IoError::other)?;
let key_der =
pki::PrivateKeyDer::Pkcs8(pki::PrivatePkcs8KeyDer::from(key_der.as_ref())).clone_key();
// Initialize the ServerConfig.
let mut config = RustlsServerConfig::builder_with_protocol_versions(&[&TLS12, &TLS13]) // 1.2 and 1.3 only.
.with_no_client_auth() // Don't require client authentication.
.with_single_cert(cert_chain, key_der)
.map_err(|e| IoError::new(std::io::ErrorKind::InvalidData, e))?;
// tor-spec:
// > Implementations SHOULD NOT allow TLS session resumption – it can exacerbate some attacks
// > (e.g. the “Triple Handshake” attack from Feb 2013), and it plays havoc with forward secrecy
// > guarantees.
//
// rustls:
// > If this is 0, no tickets are sent and clients will not be able to do any resumption.
config.send_tls13_tickets = 0;
// TODO: Possibly, modify config. There are numerous fields we could adjust.
Ok(config)
}
|
