Basic vsock proxying implementation

Currently just connecting to the host's session bus

sidebus-agent/src/main.rs

@@ -0,0 +1,46 @@
+use clap::Parser;
+use tokio::net::UnixListener;
+use tracing::info;
+
+#[derive(Parser)]
+#[command(version, about, long_about = None)]
+struct AgentCli {
+    listen_path: String,
+}
+
+#[tokio::main]
+async fn main() -> eyre::Result<()> {
+    tracing_subscriber::fmt::init();
+
+    let cli = AgentCli::parse();
+
+    let unix_addr = cli.listen_path;
+    let unix_listener = UnixListener::bind(unix_addr.clone())?;
+    info!(%unix_addr, "listening for unix clients");
+    while let Ok((unix_client, client_addr)) = unix_listener.accept().await {
+        info!(?client_addr, "new unix client");
+        tokio::spawn(async move {
+            let vsock_addr = zbus::Address::from(zbus::address::Transport::Vsock(
+                zbus::address::transport::Vsock::new(2, 4269),
+            ));
+            let vsock_conn = zbus::connection::Builder::address(vsock_addr)
+                .unwrap()
+                .p2p()
+                .auth_mechanism(zbus::AuthMechanism::Anonymous)
+                .build()
+                .await
+                .unwrap();
+            info!(guid = %vsock_conn.server_guid(), "connected to vsock bus");
+            let client_conn = zbus::connection::Builder::unix_stream(unix_client)
+                .server(vsock_conn.server_guid())
+                .unwrap()
+                .p2p()
+                .auth_mechanism(zbus::AuthMechanism::External)
+                .build()
+                .await
+                .unwrap();
+            sidebus_common::raw::splice_conns(client_conn, vsock_conn).await;
+        });
+    }
+    Ok(())
+}