feat: allow fine-grained root certs for rustls (#2232)

src/async_impl/client.rs

@@ -113,6 +113,10 @@ struct Config {
     root_certs: Vec<Certificate>,
     #[cfg(feature = "__tls")]
     tls_built_in_root_certs: bool,
+    #[cfg(feature = "rustls-tls-webpki-roots")]
+    tls_built_in_certs_webpki: bool,
+    #[cfg(feature = "rustls-tls-native-roots")]
+    tls_built_in_certs_native: bool,
     #[cfg(feature = "__tls")]
     min_tls_version: Option<tls::Version>,
     #[cfg(feature = "__tls")]
@@ -205,6 +209,10 @@ impl ClientBuilder {
                 root_certs: Vec::new(),
                 #[cfg(feature = "__tls")]
                 tls_built_in_root_certs: true,
+                #[cfg(feature = "rustls-tls-webpki-roots")]
+                tls_built_in_certs_webpki: true,
+                #[cfg(feature = "rustls-tls-native-roots")]
+                tls_built_in_certs_native: true,
                 #[cfg(any(feature = "native-tls", feature = "__rustls"))]
                 identity: None,
                 #[cfg(feature = "__tls")]
@@ -499,12 +507,12 @@ impl ClientBuilder {
                     }
 
                     #[cfg(feature = "rustls-tls-webpki-roots")]
-                    if config.tls_built_in_root_certs {
+                    if config.tls_built_in_certs_webpki {
                         root_cert_store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
                     }
 
                     #[cfg(feature = "rustls-tls-native-roots")]
-                    if config.tls_built_in_root_certs {
+                    if config.tls_built_in_certs_native {
                         let mut valid_count = 0;
                         let mut invalid_count = 0;
                         for cert in rustls_native_certs::load_native_certs()
@@ -1333,6 +1341,15 @@ impl ClientBuilder {
     ///
     /// Defaults to `true` -- built-in system certs will be used.
     ///
+    /// # Bulk Option
+    ///
+    /// If this value is `true`, _all_ enabled system certs configured with Cargo
+    /// features will be loaded.
+    ///
+    /// You can set this to `false`, and enable only a specific source with
+    /// individual methods. Do that will prevent other sources from being loaded
+    /// even if their feature Cargo feature is enabled.
+    ///
     /// # Optional
     ///
     /// This requires the optional `default-tls`, `native-tls`, or `rustls-tls(-...)`
@@ -1348,6 +1365,37 @@ impl ClientBuilder {
     )]
     pub fn tls_built_in_root_certs(mut self, tls_built_in_root_certs: bool) -> ClientBuilder {
         self.config.tls_built_in_root_certs = tls_built_in_root_certs;
+
+        #[cfg(feature = "rustls-tls-webpki-roots")]
+        {
+            self.config.tls_built_in_certs_webpki = tls_built_in_root_certs;
+        }
+
+        #[cfg(feature = "rustls-tls-native-roots")]
+        {
+            self.config.tls_built_in_certs_native = tls_built_in_root_certs;
+        }
+
+        self
+    }
+
+    /// Sets whether to load webpki root certs with rustls.
+    ///
+    /// If the feature is enabled, this value is `true` by default.
+    #[cfg(feature = "rustls-tls-webpki-roots")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rustls-tls-webpki-roots")))]
+    pub fn tls_built_in_webpki_certs(mut self, enabled: bool) -> ClientBuilder {
+        self.config.tls_built_in_certs_webpki = enabled;
+        self
+    }
+
+    /// Sets whether to load native root certs with rustls.
+    ///
+    /// If the feature is enabled, this value is `true` by default.
+    #[cfg(feature = "rustls-tls-native-roots")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rustls-tls-native-roots")))]
+    pub fn tls_built_in_native_certs(mut self, enabled: bool) -> ClientBuilder {
+        self.config.tls_built_in_certs_native = enabled;
         self
     }
 

src/blocking/client.rs

@@ -615,6 +615,24 @@ impl ClientBuilder {
         self.with_inner(move |inner| inner.tls_built_in_root_certs(tls_built_in_root_certs))
     }
 
+    /// Sets whether to load webpki root certs with rustls.
+    ///
+    /// If the feature is enabled, this value is `true` by default.
+    #[cfg(feature = "rustls-tls-webpki-roots")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rustls-tls-webpki-roots")))]
+    pub fn tls_built_in_webpki_certs(mut self, enabled: bool) -> ClientBuilder {
+        self.with_inner(move |inner| inner.tls_built_in_webpki_certs(enabled))
+    }
+
+    /// Sets whether to load native root certs with rustls.
+    ///
+    /// If the feature is enabled, this value is `true` by default.
+    #[cfg(feature = "rustls-tls-native-roots")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rustls-tls-native-roots")))]
+    pub fn tls_built_in_native_certs(mut self, enabled: bool) -> ClientBuilder {
+        self.with_inner(move |inner| inner.tls_built_in_native_certs(enabled))
+    }
+
     /// Sets the identity to be used for client certificate authentication.
     ///
     /// # Optional