feat: scaffold native ssh support

Author: plaflamme

gix-transport/src/client/async_io/connect.rs

@@ -40,6 +40,11 @@ pub(crate) mod function {
                     .map_err(|e| Box::new(e) as Box<dyn std::error::Error + Send + Sync>)?,
                 )
             }
+            gix_url::Scheme::Ssh => Box::new(
+                crate::client::async_io::ssh::connect(url, options.version, options.trace)
+                    .await
+                    .map_err(|e| Box::new(e) as Box<dyn std::error::Error + Send + Sync>)?,
+            ),
             scheme => return Err(Error::UnsupportedScheme(scheme)),
         })
     }

gix-transport/src/client/async_io/mod.rs

@@ -11,3 +11,6 @@ pub use traits::{SetServiceResponse, Transport, TransportV2Ext};
 pub mod connect;
 #[cfg(feature = "async-std")]
 pub use connect::function::connect;
+
+#[cfg(feature = "russh")]
+pub mod ssh;

gix-transport/src/client/async_io/ssh/mod.rs

@@ -0,0 +1,53 @@
+use async_trait::async_trait;
+
+use crate::{
+    client::{SetServiceResponse, Transport, TransportWithoutIO},
+    Protocol, Service,
+};
+
+pub struct NativeSsh;
+
+impl TransportWithoutIO for NativeSsh {
+    fn request(
+        &mut self,
+        write_mode: crate::client::WriteMode,
+        on_into_read: crate::client::MessageKind,
+        trace: bool,
+    ) -> Result<super::RequestWriter<'_>, crate::client::Error> {
+        todo!()
+    }
+
+    fn to_url(&self) -> std::borrow::Cow<'_, bstr::BStr> {
+        todo!()
+    }
+
+    fn connection_persists_across_multiple_requests(&self) -> bool {
+        todo!()
+    }
+
+    fn configure(
+        &mut self,
+        config: &dyn std::any::Any,
+    ) -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
+        todo!()
+    }
+}
+
+#[async_trait(?Send)]
+impl Transport for NativeSsh {
+    async fn handshake<'a>(
+        &mut self,
+        service: Service,
+        extra_parameters: &'a [(&'a str, Option<&'a str>)],
+    ) -> Result<SetServiceResponse<'_>, crate::client::Error> {
+        todo!()
+    }
+}
+
+pub async fn connect(
+    url: gix_url::Url,
+    desired_version: Protocol,
+    trace: bool,
+) -> Result<NativeSsh, crate::client::Error> {
+    todo!()
+}