feat(transport): Add server side peer cert support (#228)

* feat(transport): Add server side peer cert support

examples/src/tls_client_auth/server.rs

@@ -17,6 +17,10 @@ pub struct EchoServer;
 #[tonic::async_trait]
 impl pb::echo_server::Echo for EchoServer {
     async fn unary_echo(&self, request: Request<EchoRequest>) -> EchoResult<EchoResponse> {
+        if let Some(certs) = request.peer_certs() {
+            println!("Got {} peer certs!", certs.len());
+        }
+
         let message = request.into_inner().message;
         Ok(Response::new(EchoResponse { message }))
     }

tonic/Cargo.toml

@@ -33,8 +33,8 @@ transport = [
     "tower-load",
     "tracing-futures",
 ]
-tls = ["tokio-rustls"]
-tls-roots = ["rustls-native-certs"]
+tls = ["transport", "tokio-rustls"]
+tls-roots = ["tls", "rustls-native-certs"]
 
 # [[bench]]
 # name = "bench_main"

tonic/src/request.rs

@@ -1,7 +1,11 @@
 use crate::metadata::MetadataMap;
+#[cfg(feature = "transport")]
+use crate::transport::Certificate;
 use futures_core::Stream;
 use http::Extensions;
 use std::net::SocketAddr;
+#[cfg(feature = "transport")]
+use std::sync::Arc;
 
 /// A gRPC request and metadata from an RPC call.
 #[derive(Debug)]
@@ -14,6 +18,8 @@ pub struct Request<T> {
 #[derive(Clone)]
 pub(crate) struct ConnectionInfo {
     pub(crate) remote_addr: Option<SocketAddr>,
+    #[cfg(feature = "transport")]
+    pub(crate) peer_certs: Option<Arc<Vec<Certificate>>>,
 }
 
 /// Trait implemented by RPC request types.
@@ -188,6 +194,18 @@ impl<T> Request<T> {
         self.get::<ConnectionInfo>()?.remote_addr
     }
 
+    /// Get the peer certificates of the connected client.
+    ///
+    /// This is used to fetch the certificates from the TLS session
+    /// and is mostly used for mTLS. This currently only returns
+    /// `Some` on the server side of the `transport` server with
+    /// TLS enabled connections.
+    #[cfg(feature = "transport")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "transport")))]
+    pub fn peer_certs(&self) -> Option<Arc<Vec<Certificate>>> {
+        self.get::<ConnectionInfo>()?.peer_certs.clone()
+    }
+
     pub(crate) fn get<I: Send + Sync + 'static>(&self) -> Option<&I> {
         self.extensions.get::<I>()
     }

tonic/src/transport/server/conn.rs

@@ -1,7 +1,8 @@
+use crate::transport::Certificate;
 use hyper::server::conn::AddrStream;
 use std::net::SocketAddr;
 #[cfg(feature = "tls")]
-use tokio_rustls::TlsStream;
+use tokio_rustls::{rustls::Session, server::TlsStream};
 
 /// Trait that connected IO resources implement.
 ///
@@ -13,6 +14,11 @@ pub trait Connected {
     fn remote_addr(&self) -> Option<SocketAddr> {
         None
     }
+
+    /// Return the set of connected peer TLS certificates.
+    fn peer_certs(&self) -> Option<Vec<Certificate>> {
+        None
+    }
 }
 
 impl Connected for AddrStream {
@@ -27,4 +33,18 @@ impl<T: Connected> Connected for TlsStream<T> {
         let (inner, _) = self.get_ref();
         inner.remote_addr()
     }
+
+    fn peer_certs(&self) -> Option<Vec<Certificate>> {
+        let (_, session) = self.get_ref();
+
+        if let Some(certs) = session.get_peer_certificates() {
+            let certs = certs
+                .into_iter()
+                .map(|c| Certificate::from_pem(c.0))
+                .collect();
+            Some(certs)
+        } else {
+            None
+        }
+    }
 }

tonic/src/transport/server/mod.rs

@@ -505,6 +505,7 @@ where
     fn call(&mut self, io: &ServerIo) -> Self::Future {
         let conn_info = crate::request::ConnectionInfo {
             remote_addr: io.remote_addr(),
+            peer_certs: io.peer_certs().map(Arc::new),
         };
 
         let interceptor = self.interceptor.clone();

tonic/src/transport/service/io.rs

@@ -1,4 +1,4 @@
-use crate::transport::server::Connected;
+use crate::transport::{server::Connected, Certificate};
 use hyper::client::connect::{Connected as HyperConnected, Connection};
 use std::io;
 use std::net::SocketAddr;
@@ -71,8 +71,11 @@ impl ServerIo {
 
 impl Connected for ServerIo {
     fn remote_addr(&self) -> Option<SocketAddr> {
-        let io = &*self.0;
-        io.remote_addr()
+        (&*self.0).remote_addr()
+    }
+
+    fn peer_certs(&self) -> Option<Vec<Certificate>> {
+        (&self.0).peer_certs()
     }
 }
 

tonic/src/transport/service/tls.rs

@@ -157,17 +157,17 @@ impl TlsAcceptor {
         })
     }
 
-    pub(crate) async fn accept<IO>(&self, io: IO) -> Result<BoxedIo, crate::Error>
+    pub(crate) async fn accept<IO>(
+        &self,
+        io: IO,
+    ) -> Result<tokio_rustls::server::TlsStream<IO>, crate::Error>
     where
         IO: AsyncRead + AsyncWrite + Connected + Unpin + Send + 'static,
     {
-        let io = {
-            let acceptor = RustlsAcceptor::from(self.inner.clone());
-            let tls = acceptor.accept(io).await?;
-            BoxedIo::new(tls)
-        };
+        let acceptor = RustlsAcceptor::from(self.inner.clone());
+        let tls = acceptor.accept(io).await?;
 
-        Ok(io)
+        Ok(tls)
     }
 }