huskies: merge 1129 story find_free_port fallback returns unbindable port silently when range is exhausted

server/src/chat/transport/matrix/new_project.rs

@@ -431,8 +431,13 @@ async fn handle_adopt_project(
     }
 
     // ── Allocate ports and launch container ──────────────────────────────────
-    let port = find_free_port(3100);
-    let ssh_port = find_free_port(2200);
+    let Some(port) = find_free_port(3100) else {
+        return "No free port in range 3100–3200. Stop unused containers and retry.".to_string();
+    };
+    let Some(ssh_port) = find_free_port(2200) else {
+        return "No free SSH port in range 2200–2300. Stop unused containers and retry."
+            .to_string();
+    };
     let container_url = format!("http://127.0.0.1:{port}");
     let container_name = format!("huskies-{name}");
 
@@ -772,8 +777,17 @@ pub async fn handle_new_project(
 
     // ── Allocate ports and launch container ──────────────────────────────────
 
-    let port = find_free_port(3100);
-    let ssh_port = find_free_port(2200);
+    let Some(port) = find_free_port(3100) else {
+        let _ = tokio::fs::remove_dir_all(&host_path).await;
+        let _ = tokio::fs::remove_dir_all(&ssh_key_dir).await;
+        return "No free port in range 3100–3200. Stop unused containers and retry.".to_string();
+    };
+    let Some(ssh_port) = find_free_port(2200) else {
+        let _ = tokio::fs::remove_dir_all(&host_path).await;
+        let _ = tokio::fs::remove_dir_all(&ssh_key_dir).await;
+        return "No free SSH port in range 2200–2300. Stop unused containers and retry."
+            .to_string();
+    };
     let container_url = format!("http://127.0.0.1:{port}");
     let container_name = format!("huskies-{name}");
 
@@ -924,17 +938,21 @@ fn interpret_docker_run_error(stderr: &str, image: &str) -> String {
     }
 }
 
+/// Scan `start..start+range` for a bindable TCP port on 127.0.0.1.
+///
+/// Returns `Some(port)` for the first port that can be bound, or `None` if all
+/// ports in the range are occupied.
+fn find_free_port_in_range(start: u16, range: u16) -> Option<u16> {
+    (start..start.saturating_add(range))
+        .find(|&port| std::net::TcpListener::bind(("127.0.0.1", port)).is_ok())
+}
+
 /// Find a free TCP port by attempting to bind starting from `start`.
 ///
-/// Scans up to 100 ports above `start` and returns the first available one.
-/// Falls back to `start` if none are found (unlikely in practice).
-fn find_free_port(start: u16) -> u16 {
-    for port in start..start + 100 {
-        if std::net::TcpListener::bind(("127.0.0.1", port)).is_ok() {
-            return port;
-        }
-    }
-    start
+/// Scans up to 100 ports above `start` and returns `Some(port)` for the first
+/// bindable one, or `None` when the entire range `start..start+100` is exhausted.
+fn find_free_port(start: u16) -> Option<u16> {
+    find_free_port_in_range(start, 100)
 }
 
 // ---------------------------------------------------------------------------
@@ -1148,13 +1166,21 @@ mod tests {
 
     #[test]
     fn find_free_port_returns_bindable_port() {
-        let port = find_free_port(2200);
-        // The returned port must be in range and actually bindable.
+        let port = find_free_port(2200).expect("expected Some(port) in range 2200..2300");
         assert!((2200..2300).contains(&port));
         let listener = std::net::TcpListener::bind(("127.0.0.1", port));
         assert!(listener.is_ok(), "returned port {port} is not bindable");
     }
 
+    #[test]
+    fn find_free_port_exhausted_range_returns_none() {
+        // Bind the single port in a 1-wide scan window, then verify None is returned.
+        let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+        let port = listener.local_addr().unwrap().port();
+        // The range [port, port+1) contains only `port`, which is already bound.
+        assert_eq!(find_free_port_in_range(port, 1), None);
+    }
+
     #[test]
     fn detect_stack_go_mod() {
         let dir = tempfile::tempdir().unwrap();