Add a rustls-tls-native-roots feature

Adds an optional cargo feature to load certificates
from the OS native certificate store.

Cargo.toml

@@ -37,6 +37,7 @@ native-tls-vendored = ["native-tls", "native-tls-crate/vendored"]
 rustls-tls = ["rustls-tls-webpki-roots"]
 rustls-tls-manual-roots = ["__rustls"]
 rustls-tls-webpki-roots = ["webpki-roots", "__rustls"]
+rustls-tls-native-roots = ["rustls-native-certs", "__rustls"]
 
 blocking = ["futures-util/io", "tokio/rt-threaded", "tokio/rt-core", "tokio/sync"]
 
@@ -104,6 +105,7 @@ hyper-rustls = { version = "0.21", default-features = false, optional = true }
 rustls = { version = "0.18", features = ["dangerous_configuration"], optional = true }
 tokio-rustls = { version = "0.14", optional = true }
 webpki-roots = { version = "0.20", optional = true }
+rustls-native-certs = { version = "0.4", optional = true }
 
 ## cookies
 cookie_crate = { version = "0.14", package = "cookie", optional = true }

src/async_impl/client.rs

@@ -21,6 +21,8 @@ use http::Uri;
 use hyper::client::ResponseFuture;
 #[cfg(feature = "native-tls-crate")]
 use native_tls_crate::TlsConnector;
+#[cfg(feature = "rustls-tls-native-roots")]
+use rustls::RootCertStore;
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -258,6 +260,11 @@ impl ClientBuilder {
                     #[cfg(feature = "rustls-tls-webpki-roots")]
                     tls.root_store
                         .add_server_trust_anchors(&webpki_roots::TLS_SERVER_ROOTS);
+                    #[cfg(feature = "rustls-tls-native-roots")]
+                    {
+                        let roots_slice = NATIVE_ROOTS.as_ref().unwrap().roots.as_slice();
+                        tls.root_store.roots.extend_from_slice(roots_slice);
+                    }
 
                     if !config.certs_verification {
                         tls.dangerous()
@@ -1532,6 +1539,11 @@ fn add_cookie_header(headers: &mut HeaderMap, cookie_store: &cookie::CookieStore
     }
 }
 
+#[cfg(feature = "rustls-tls-native-roots")]
+lazy_static! {
+    static ref NATIVE_ROOTS: std::io::Result<RootCertStore> = rustls_native_certs::load_native_certs().map_err(|e| e.1);
+}
+
 #[cfg(test)]
 mod tests {
     #[tokio::test]

src/lib.rs

@@ -174,7 +174,9 @@
 //! - **rustls-tls-manual-roots**: Enables TLS functionality provided by `rustls`,
 //!   without setting any root certificates. Roots have to be specified manually.
 //! - **rustls-tls-webpki-roots**: Enables TLS functionality provided by `rustls`,
-//!   while using root certificates from the `webpki-roots` crate
+//!   while using root certificates from the `webpki-roots` crate.
+//! - **rustls-tls-native-roots**: Enables TLS functionality provided by `rustls`,
+//!   while using root certificates from the `rustls-native-certs` crate.
 //! - **blocking**: Provides the [blocking][] client API.
 //! - **cookies**: Provides cookie session support.
 //! - **gzip**: Provides response body gzip decompression.

tests/badssl.rs

@@ -16,7 +16,10 @@ async fn test_badssl_modern() {
     assert!(text.contains("<title>mozilla-modern.badssl.com</title>"));
 }
 
-#[cfg(feature = "rustls-tls-webpki-roots")]
+#[cfg(any(
+    feature = "rustls-tls-webpki-roots",
+    feature = "rustls-tls-native-roots"
+))]
 #[tokio::test]
 async fn test_rustls_badssl_modern() {
     let text = reqwest::Client::builder()