Allow server_listen to randomly choose port.

python/fixtool/agent.py

@@ -189,9 +189,10 @@ def listen(self, port):
         self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         self._socket.bind(('', port))
         self._socket.listen(5)
+        actual_port = self._socket.getsockname()[1]
 
         asyncio.get_event_loop().add_reader(self._socket, self.acceptable)
-        return
+        return actual_port
 
     def unlisten(self):
         """Stop listening for client connections."""
@@ -769,9 +770,9 @@ def handle_server_listen(self, control: ControlSession, message: dict):
             control.send(response.to_json().encode())
             return
 
-        server.listen(port)
+        actual_port = server.listen(port)
 
-        response = ServerListenedMessage(name, True, '')
+        response = ServerListenedMessage(name, True, '', actual_port)
         control.send(response.to_json().encode())
         return
 

python/fixtool/message.py

@@ -444,24 +444,27 @@ def from_dict(d):
 
 
 class ServerListenedMessage:
-    def __init__(self, name: str, result: bool, message: str):
+    def __init__(self, name: str, result: bool, message: str, port: int):
         self.type = "server_listened"
         self.name = name
         self.result = result
         self.message = message
+        self.port = port
         return
 
     def to_json(self):
         return json.dumps({"type": self.type,
                            "name": self.name,
                            "result": self.result,
-                           "message": self.message})
+                           "message": self.message,
+                           "port": self.port})
 
     @staticmethod
     def from_dict(d):
         return ServerListenedMessage(d.get("name"),
                                      d.get("result"),
-                                     d.get("message"))
+                                     d.get("message"),
+                                     d.get("port"))
 
 
 class ServerUnlistenMessage:

python/fixtool/proxy.py

@@ -193,10 +193,11 @@ def destroy(self):
         self._destroyed = True
         return
 
-    def listen(self, port: int):
+    def listen(self, port: int = 0):
         """Listen for connections on specified port.
 
-        :param port: TCP port number on which to listen for connections."""
+        :param port: TCP port number on which to listen for connections.
+        :returns: Listening port number."""
         assert not self._destroyed
 
         msg = ServerListenMessage(self._name, port)
@@ -206,8 +207,9 @@ def listen(self, port: int):
         if not response.result:
             raise RuntimeError(response.message)
 
-        self._ports.append(port)
-        return
+        actual_port = response.port
+        self._ports.append(actual_port)
+        return actual_port
 
     def stop_listening(self, port: int):
         """Stop listening for connections on specified port.