Basic vsock proxying implementation

Currently just connecting to the host's session bus

sidebus-broker/src/main.rs

@@ -1,3 +1,33 @@
-fn main() {
-    println!("Hello, world!");
+mod vsock;
+
+use clap::Parser;
+use tracing::info;
+
+#[derive(Parser)]
+#[command(version, about, long_about = None)]
+struct BrokerCli {}
+
+#[tokio::main]
+async fn main() -> eyre::Result<()> {
+    tracing_subscriber::fmt::init();
+
+    let _cli = BrokerCli::parse();
+
+    vsock::ListenerBuilder::new(vsock::VsockAddr::new(vsock::VMADDR_CID_HOST, 4269))
+        .with_label("VM Bus")
+        .listen(async |client| {
+            let session_bus = zbus::connection::Builder::session()
+                .unwrap()
+                .p2p() /* i.e. "raw connection, don't send Hello" */
+                .build()
+                .await
+                .unwrap();
+            info!(guid = %session_bus.server_guid(), "connected to session bus");
+            let client_conn = client.build(session_bus.server_guid().into()).await?;
+            sidebus_common::raw::splice_conns(client_conn, session_bus).await;
+            Ok(())
+        })
+        .await?;
+
+    Ok(())
 }