Prevent parameter retrieval crashes (#978)

* fix(params): prevent parameter retrieval crashes in ROS2

- Add check for node's fully qualified name to prevent deadlocks
- Add 2.0s timeout to spin_until_future_complete
- Fix crashes when retrieving parameters via Roslibjs

Fixes #972

* added parameter for timeout

* Add new service to retrieve the different interfaces in the ROS Network (#988)

* Fix rosbridge_websocket symlink

* Don't fail on nodes without parameter services

* Remove added empty line

---------

Co-authored-by: Błażej Sowa <[email protected]>
Co-authored-by: Matthias Rathauscher (LWN) <[email protected]>
Co-authored-by: Lebecque Florian <[email protected]>

rosapi/scripts/rosapi_node

@@ -78,6 +78,7 @@ class Rosapi(Node):
         self.declare_parameter("topics_glob", "[*]")
         self.declare_parameter("services_glob", "[*]")
         self.declare_parameter("params_glob", "[*]")
+        self.declare_parameter("params_timeout", 5.0)
         self.globs = self.get_globs()
         self.register_services()
 
@@ -88,7 +89,9 @@ class Rosapi(Node):
             full_name = self.get_namespace() + self.get_name()
         else:
             full_name = self.get_namespace() + "/" + self.get_name()
-        params.init(full_name)
+
+        timeout_sec = self.get_parameter("params_timeout").value
+        params.init(full_name, timeout_sec)
 
         self.create_service(Topics, "~/topics", self.get_topics)
         self.create_service(Interfaces, "~/interfaces", self.get_interfaces)

rosapi/src/rosapi/params.py

@@ -45,10 +45,14 @@
 """ Methods to interact with the param server.  Values have to be passed
 as JSON in order to facilitate dynamically typed SRV messages """
 
+# Constants
+DEFAULT_PARAM_TIMEOUT_SEC = 5.0
+
 # Ensure thread safety for setting / getting parameters.
 param_server_lock = threading.RLock()
 _node = None
 _parent_node_name = ""
+_timeout_sec = DEFAULT_PARAM_TIMEOUT_SEC
 
 _parameter_type_mapping = [
     "",
@@ -64,12 +68,12 @@
 ]
 
 
-def init(parent_node_name):
+def init(parent_node_name, timeout_sec=DEFAULT_PARAM_TIMEOUT_SEC):
     """
     Initializes params module with a rclpy.node.Node for further use.
     This function has to be called before any other for the module to work.
     """
-    global _node, _parent_node_name
+    global _node, _parent_node_name, _timeout_sec
     # TODO(@jubeira): remove this node; use rosapi node with MultiThreadedExecutor or
     # async / await to prevent the service calls from blocking.
     parent_node_basename = parent_node_name.split("/")[-1]
@@ -81,6 +85,10 @@ def init(parent_node_name):
     )
     _parent_node_name = get_absolute_node_name(parent_node_name)
 
+    if not isinstance(timeout_sec, (int, float)) or timeout_sec <= 0:
+        raise ValueError("Parameter timeout must be a positive number")
+    _timeout_sec = timeout_sec
+
 
 def set_param(node_name, name, value, params_glob):
     """Sets a parameter in a given node"""
@@ -226,21 +234,20 @@ def _get_param_names(node_name):
     # This method is called in a service callback; calling a service of the same node
     # will cause a deadlock.
     global _parent_node_name
-    if node_name == _parent_node_name:
+    if node_name == _parent_node_name or node_name == _node.get_fully_qualified_name():
         return []
 
     client = _node.create_client(ListParameters, f"{node_name}/list_parameters")
 
-    ready = client.wait_for_service(timeout_sec=5.0)
-    if not ready:
-        raise RuntimeError("Wait for list_parameters service timed out")
+    if not client.service_is_ready():
+        return []
 
     request = ListParameters.Request()
     future = client.call_async(request)
     if _node.executor:
-        _node.executor.spin_until_future_complete(future)
+        _node.executor.spin_until_future_complete(future, timeout_sec=_timeout_sec)
     else:
-        rclpy.spin_until_future_complete(_node, future)
+        rclpy.spin_until_future_complete(_node, future, timeout_sec=_timeout_sec)
     response = future.result()
 
     if response is not None:

rosbridge_server/launch/rosbridge_websocket_launch.xml

@@ -23,6 +23,7 @@
   <arg name="topics_glob" default="" />
   <arg name="services_glob" default="" />
   <arg name="params_glob" default="" />
+  <arg name="params_timeout" default="5.0" />
   <arg name="bson_only_mode" default="false" />
 
   <arg name="respawn" default="false"/>
@@ -78,5 +79,6 @@
     <param name="topics_glob" value="$(var topics_glob)"/>
     <param name="services_glob" value="$(var services_glob)"/>
     <param name="params_glob" value="$(var params_glob)"/>
+    <param name="params_timeout" value="$(var params_timeout)"/>
   </node>
 </launch>