feat(edge,protocol,test): add configurable edge bind address and expand flow-control test coverage

rust/crates/remoteingress-core/src/edge.rs

@@ -32,6 +32,10 @@ pub struct EdgeConfig {
     pub hub_port: u16,
     pub edge_id: String,
     pub secret: String,
+    /// Optional bind address for TCP listeners (defaults to "0.0.0.0").
+    /// Useful for testing on localhost where edge and upstream share the same machine.
+    #[serde(default)]
+    pub bind_address: Option<String>,
 }
 
 /// Handshake config received from hub after authentication.
@@ -416,6 +420,7 @@ async fn connect_to_hub_and_run(
 
     // Start TCP listeners for initial ports (hot-reloadable)
     let mut port_listeners: HashMap<u16, JoinHandle<()>> = HashMap::new();
+    let bind_address = config.bind_address.as_deref().unwrap_or("0.0.0.0");
     apply_port_config(
         &handshake.listen_ports,
         &mut port_listeners,
@@ -426,6 +431,7 @@ async fn connect_to_hub_and_run(
         next_stream_id,
         &config.edge_id,
         connection_token,
+        bind_address,
     );
 
     // Heartbeat: liveness timeout detects silent hub failures
@@ -492,6 +498,7 @@ async fn connect_to_hub_and_run(
                                         next_stream_id,
                                         &config.edge_id,
                                         connection_token,
+                                        bind_address,
                                     );
                                 }
                             }
@@ -557,6 +564,7 @@ fn apply_port_config(
     next_stream_id: &Arc<AtomicU32>,
     edge_id: &str,
     connection_token: &CancellationToken,
+    bind_address: &str,
 ) {
     let new_set: std::collections::HashSet<u16> = new_ports.iter().copied().collect();
     let old_set: std::collections::HashSet<u16> = port_listeners.keys().copied().collect();
@@ -579,8 +587,9 @@ fn apply_port_config(
         let edge_id = edge_id.to_string();
         let port_token = connection_token.child_token();
 
+        let bind_addr = bind_address.to_string();
         let handle = tokio::spawn(async move {
-            let listener = match TcpListener::bind(("0.0.0.0", port)).await {
+            let listener = match TcpListener::bind((bind_addr.as_str(), port)).await {
                 Ok(l) => l,
                 Err(e) => {
                     log::error!("Failed to bind port {}: {}", port, e);
@@ -840,6 +849,7 @@ mod tests {
             hub_port: 9999,
             edge_id: "e1".to_string(),
             secret: "sec".to_string(),
+            bind_address: None,
         };
         let json = serde_json::to_string(&config).unwrap();
         let back: EdgeConfig = serde_json::from_str(&json).unwrap();
@@ -955,6 +965,7 @@ mod tests {
             hub_port: 8443,
             edge_id: "test-edge".to_string(),
             secret: "test-secret".to_string(),
+            bind_address: None,
         });
         let status = edge.get_status().await;
         assert!(!status.running);
@@ -971,6 +982,7 @@ mod tests {
             hub_port: 8443,
             edge_id: "e".to_string(),
             secret: "s".to_string(),
+            bind_address: None,
         });
         let rx1 = edge.take_event_rx().await;
         assert!(rx1.is_some());
@@ -985,6 +997,7 @@ mod tests {
             hub_port: 8443,
             edge_id: "e".to_string(),
             secret: "s".to_string(),
+            bind_address: None,
         });
         edge.stop().await; // should not panic
         let status = edge.get_status().await;