Rework TLS configuration to use a builder

This commit reworks TLS configuration of both servers and endpoints in
order to provide a more flexible API. We now add options to configure
the selected TLS library using the appropriate 'native' configuration
structures, as well as retaining the existing simplier interface which
is compatible with both.

The new API can also be easily extended to support simple interfaces for
configuring mTLS and a range of other options without creating sprawl
in the builders for `Server` and `Endpoint`.

tonic-examples/src/tls/client.rs

@@ -3,19 +3,22 @@ pub mod pb {
 }
 
 use pb::{client::EchoClient, EchoRequest};
-use tonic::transport::{Certificate, Channel};
+use tonic::transport::{Certificate, Channel, ClientTlsConfig, TlsProvider};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let pem = tokio::fs::read("tonic-examples/data/tls/ca.pem").await?;
     let ca = Certificate::from_pem(pem);
 
+    let tls = ClientTlsConfig::new(TlsProvider::Rustls)
+        .ca_certificate(ca)
+        .domain_name(Some("example.com".into()));
+
     let channel = Channel::from_static("http://[::1]:50051")
-        .rustls_tls(ca, Some("example.com".into()))
+        .tls(tls)
         .channel();
 
     let mut client = EchoClient::new(channel);
-
     let request = tonic::Request::new(EchoRequest {
         message: "hello".into(),
     });

tonic-examples/src/tls/server.rs

@@ -5,7 +5,7 @@ pub mod pb {
 use pb::{EchoRequest, EchoResponse};
 use std::collections::VecDeque;
 use tonic::{
-    transport::{Identity, Server},
+    transport::{Identity, Server, ServerTlsConfig, TlsProvider},
     Request, Response, Status, Streaming,
 };
 
@@ -58,8 +58,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let addr = "[::1]:50051".parse().unwrap();
     let server = EchoServer::default();
 
+    let tls = ServerTlsConfig::new(TlsProvider::Rustls).identity(identity);
+
     Server::builder()
-        .rustls_tls(identity)
+        .tls(tls)
         .clone()
         .serve(addr, pb::server::EchoServer::new(server))
         .await?;

tonic-interop/src/bin/client.rs

@@ -1,6 +1,6 @@
 use std::time::Duration;
 use structopt::{clap::arg_enum, StructOpt};
-use tonic::transport::{Certificate, Endpoint};
+use tonic::transport::{Certificate, ClientTlsConfig, Endpoint, TlsProvider};
 use tonic_interop::client;
 
 #[derive(StructOpt)]
@@ -33,7 +33,11 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     if matches.use_tls {
         let pem = tokio::fs::read("tonic-interop/data/ca.pem").await?;
         let ca = Certificate::from_pem(pem);
-        endpoint.openssl_tls(ca, Some("foo.test.google.fr".into()));
+
+        let tls = ClientTlsConfig::new(TlsProvider::OpenSsl)
+            .ca_certificate(ca)
+            .domain_name(Some("foo.test.google.fr".into()));
+        endpoint.tls(tls);
     }
 
     let channel = endpoint.channel();

tonic-interop/src/bin/server.rs

@@ -2,7 +2,7 @@ use http::header::HeaderName;
 use structopt::StructOpt;
 use tonic::body::BoxBody;
 use tonic::client::GrpcService;
-use tonic::transport::{Identity, Server};
+use tonic::transport::{Identity, Server, ServerTlsConfig, TlsProvider};
 use tonic_interop::{server, MergeTrailers};
 
 #[derive(StructOpt)]
@@ -26,7 +26,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         let key = tokio::fs::read("tonic-interop/data/server1.key").await?;
 
         let identity = Identity::from_pem(cert, key);
-        builder.openssl_tls(identity);
+        builder.tls(ServerTlsConfig::new(TlsProvider::OpenSsl).identity(identity));
     }
 
     builder.interceptor_fn(|svc, req| {

tonic/src/transport/endpoint.rs

@@ -1,6 +1,7 @@
 use super::channel::Channel;
 #[cfg(feature = "tls")]
 use super::{service::TlsConnector, tls::Certificate};
+use crate::transport::tls::TlsProvider;
 use bytes::Bytes;
 use http::uri::{InvalidUriBytes, Uri};
 use std::{
@@ -122,64 +123,6 @@ impl Endpoint {
         self
     }
 
-    /// Enable TLS and apply the CA as the root certificate.
-    ///
-    /// Providing an optional domain to override. If `None` is passed to this
-    /// the TLS implementation will use the `Uri` that was used to create the
-    /// `Endpoint` builder.
-    ///
-    /// ```no_run
-    /// # use tonic::transport::{Certificate, Endpoint};
-    /// # fn dothing() -> Result<(), Box<dyn std::error::Error>> {
-    /// # let mut builder = Endpoint::from_static("https://example.com");
-    /// let ca = std::fs::read_to_string("ca.pem")?;
-    ///
-    /// let ca = Certificate::from_pem(ca);
-    ///
-    /// builder.openssl_tls(ca, "example.com".to_string());
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg(feature = "openssl")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "openssl")))]
-    pub fn openssl_tls(&mut self, ca: Certificate, domain: impl Into<Option<String>>) -> &mut Self {
-        let domain = domain
-            .into()
-            .unwrap_or_else(|| self.uri.clone().to_string());
-        let tls = TlsConnector::new_with_openssl(ca, domain).unwrap();
-        self.tls = Some(tls);
-        self
-    }
-
-    /// Enable TLS and apply the CA as the root certificate.
-    ///
-    /// Providing an optional domain to override. If `None` is passed to this
-    /// the TLS implementation will use the `Uri` that was used to create the
-    /// `Endpoint` builder.
-    ///
-    /// ```no_run
-    /// # use tonic::transport::{Certificate, Endpoint};
-    /// # fn dothing() -> Result<(), Box<dyn std::error::Error>> {
-    /// # let mut builder = Endpoint::from_static("https://example.com");
-    /// let ca = std::fs::read_to_string("ca.pem")?;
-    ///
-    /// let ca = Certificate::from_pem(ca);
-    ///
-    /// builder.rustls_tls(ca, "example.com".to_string());
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg(feature = "rustls")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "rustls")))]
-    pub fn rustls_tls(&mut self, ca: Certificate, domain: impl Into<Option<String>>) -> &mut Self {
-        let domain = domain
-            .into()
-            .unwrap_or_else(|| self.uri.clone().to_string());
-        let tls = TlsConnector::new_with_rustls(ca, domain).unwrap();
-        self.tls = Some(tls);
-        self
-    }
-
     /// Intercept outbound HTTP Request headers;
     pub fn intercept_headers<F>(&mut self, f: F) -> &mut Self
     where
@@ -189,6 +132,12 @@ impl Endpoint {
         self
     }
 
+    /// Configures TLS for the endpoint.
+    pub fn tls(&mut self, tls_config: ClientTlsConfig) -> &mut Self {
+        self.tls = tls_config.tls_connector(self.uri.clone());
+        self
+    }
+
     /// Create a channel from this config.
     pub fn channel(&self) -> Channel {
         Channel::connect(self.clone())
@@ -252,3 +201,95 @@ impl fmt::Debug for Endpoint {
         f.debug_struct("Endpoint").finish()
     }
 }
+
+/// Configures TLS settings for endpoints.
+#[cfg(feature = "tls")]
+pub struct ClientTlsConfig {
+    provider: TlsProvider,
+    domain: Option<String>,
+    cert: Option<Certificate>,
+    #[cfg(feature = "openssl")]
+    openssl_raw: Option<openssl1::ssl::SslConnector>,
+    #[cfg(feature = "rustls")]
+    rustls_raw: Option<tokio_rustls::rustls::ClientConfig>,
+}
+
+impl fmt::Debug for ClientTlsConfig {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ClientTlsConfig")
+            .field("provider", &self.provider)
+            .finish()
+    }
+}
+
+#[cfg(feature = "tls")]
+impl ClientTlsConfig {
+    /// Creates a new `ClientTlsConfig` backed by the specified provider. Enable the `openssl` or
+    /// `rustls` features of the `tonic` crate to use OpenSSL or Rustls respectively.
+    pub fn new(provider: TlsProvider) -> Self {
+        ClientTlsConfig {
+            provider,
+            domain: None,
+            cert: None,
+            #[cfg(feature = "openssl")]
+            openssl_raw: None,
+            #[cfg(feature = "rustls")]
+            rustls_raw: None,
+        }
+    }
+
+    /// Sets the domain name against which to verify the server's TLS certificate. If set to `None`
+    /// (the default), the address specified
+    pub fn domain_name(mut self, domain_name: impl Into<Option<String>>) -> Self {
+        self.domain = domain_name.into();
+        self
+    }
+
+    /// Sets the CA Certificate against which to verify the server's TLS certificate.
+    pub fn ca_certificate(mut self, ca_certificate: Certificate) -> Self {
+        self.cert = Some(ca_certificate);
+        self
+    }
+
+    /// Use options specified by the given `SslConnector` to configure TLS.
+    ///
+    /// This overrides all other TLS options set via other means.
+    #[cfg(feature = "openssl")]
+    pub fn openssl_connector(mut self, connector: openssl1::ssl::SslConnector) -> Self {
+        self.openssl_raw = Some(connector);
+        self
+    }
+
+    /// Use options specified by the given `ClientConfig` to configure TLS.
+    ///
+    /// This overrides all other TLS options set via other means.
+    #[cfg(feature = "rustls")]
+    pub fn rustls_client_config(mut self, config: tokio_rustls::rustls::ClientConfig) -> Self {
+        self.rustls_raw = Some(config);
+        self
+    }
+
+    fn tls_connector(self, uri: Uri) -> Option<TlsConnector> {
+        match self.provider {
+            TlsProvider::None => None,
+            #[cfg(feature = "openssl")]
+            TlsProvider::OpenSsl => {
+                if let Some(connector) = self.openssl_raw {
+                    return Some(TlsConnector::new_with_openssl_raw(connector).unwrap());
+                } else {
+                    let domain = self.domain.unwrap_or_else(|| uri.to_string());
+                    return Some(TlsConnector::new_with_openssl_cert(self.cert, domain).unwrap());
+                }
+            }
+            #[cfg(feature = "rustls")]
+            TlsProvider::Rustls => {
+                if let Some(config) = self.rustls_raw {
+                    return Some(TlsConnector::new_with_rustls_raw(config).unwrap());
+                } else {
+                    let domain = self.domain.unwrap_or_else(|| uri.to_string());
+                    return Some(TlsConnector::new_with_rustls_cert(self.cert, domain).unwrap());
+                }
+            }
+        }
+    }
+}

tonic/src/transport/mod.rs

@@ -19,7 +19,7 @@
 //! ## Client
 //!
 //! ```no_run
-//! # use tonic::transport::{Channel, Certificate};
+//! # use tonic::transport::{Channel, Certificate, ClientTlsConfig, TlsProvider};
 //! # use std::time::Duration;
 //! # use tonic::body::BoxBody;
 //! # use tonic::client::GrpcService;;
@@ -29,7 +29,9 @@
 //! let cert = std::fs::read_to_string("ca.pem")?;
 //!
 //! let mut channel = Channel::from_static("https://example.com")
-//!     .rustls_tls(Certificate::from_pem(&cert), "example.com".to_string())
+//!     .tls(ClientTlsConfig::new(TlsProvider::Rustls)
+//!         .ca_certificate(Certificate::from_pem(&cert))
+//!         .domain_name("example.com".to_string()))
 //!     .timeout(Duration::from_secs(5))
 //!     .rate_limit(5, Duration::from_secs(1))
 //!     .concurrency_limit(256)
@@ -43,7 +45,7 @@
 //! ## Server
 //!
 //! ```no_run
-//! # use tonic::transport::{Server, Identity};
+//! # use tonic::transport::{Server, Identity, ServerTlsConfig, TlsProvider};
 //! # use tower::{Service, service_fn};
 //! # use futures_util::future::{err, ok};
 //! # #[cfg(feature = "rustls")]
@@ -55,7 +57,8 @@
 //! let addr = "[::1]:50051".parse()?;
 //!
 //! Server::builder()
-//!     .rustls_tls(Identity::from_pem(&cert, &key))
+//!     .tls(ServerTlsConfig::new(TlsProvider::Rustls)
+//!         .identity(Identity::from_pem(&cert, &key)))
 //!     .concurrency_limit_per_connection(256)
 //!     .interceptor_fn(|svc, req| {
 //!         println!("Request: {:?}", req);
@@ -89,4 +92,8 @@ pub use self::server::Server;
 pub use self::tls::{Certificate, Identity};
 pub use hyper::Body;
 
+pub use self::endpoint::ClientTlsConfig;
+pub use self::server::ServerTlsConfig;
+pub use self::tls::TlsProvider;
+
 pub(crate) use self::error::ErrorKind;