Bug28692

sbws/util/stem.py

@@ -1,3 +1,5 @@
+from collections import OrderedDict
+
 from stem.control import (Controller, Listener)
 from stem import (SocketError, InvalidRequest, UnsatisfiableRequest,
                   OperationFailed, ControllerError, InvalidArguments,
@@ -16,6 +18,9 @@
 stream_building_lock = RLock()
 
 
+TORRC_OPTIONS_CAN_FAIL = OrderedDict({'ConnectionPadding': '0'})
+
+
 def attach_stream_to_circuit_listener(controller, circ_id):
     ''' Returns a function that should be given to add_event_listener(). It
     looks for newly created streams and attaches them to the given circ_id '''
@@ -117,6 +122,33 @@ def _init_controller_socket(socket):
     return c
 
 
+def set_torrc_runtime_options(cont):
+    """Set torrc options at runtime."""
+    try:
+        cont.set_conf('__DisablePredictedCircuits', '1')
+        cont.set_conf('__LeaveStreamsUnattached', '1')
+    # Only the first option that fails will be logged here.
+    # Just log stem's exceptions.
+    except (ControllerError, InvalidRequest, InvalidArguments) as e:
+        log.exception(e)
+        exit(1)
+
+
+def set_torrc_options_can_fail(controller):
+    """Set options that can fail, at runtime.
+    They can be set at launch, but since the may fail because they are not
+    supported in some Tor versions, it's easier to try one by one at runtime
+    and ignore the ones that fail.
+
+    """
+    for k, v in TORRC_OPTIONS_CAN_FAIL.items():
+        try:
+            controller.set_conf(k, v)
+        except InvalidArguments as error:
+            log.debug('Ignoring option not supported by this Tor version. %s',
+                      error)
+
+
 def launch_tor(conf):
     assert isinstance(conf, ConfigParser)
     os.makedirs(conf.getpath('tor', 'datadir'), mode=0o700, exist_ok=True)
@@ -194,15 +226,11 @@ def launch_tor(conf):
         fail_hard('Error trying to launch tor: %s', e)
     # And return a controller to it
     cont = _init_controller_socket(conf.getpath('tor', 'control_socket'))
-    # Because we build things by hand and can't set these before Tor bootstraps
-    try:
-        cont.set_conf('__DisablePredictedCircuits', '1')
-        cont.set_conf('__LeaveStreamsUnattached', '1')
-    except (ControllerError, InvalidArguments, InvalidRequest) as e:
-        log.exception("Error trying to launch tor: %s. "
-                      "Maybe the tor directory is being used by other "
-                      "sbws instance?", e)
-        exit(1)
+    # Set options that can fail at runtime
+    set_torrc_options_can_fail(cont)
+    # Set runtime options
+    set_torrc_runtime_options(cont)
+
     log.info('Started and connected to Tor %s via %s', cont.get_version(),
              conf.getpath('tor', 'control_socket'))
     return cont

tests/integration/util/test_stem.py

@@ -4,3 +4,25 @@
 def test_launch_and_okay(persistent_launch_tor):
     cont = persistent_launch_tor
     assert stem_utils.is_bootstrapped(cont)
+
+
+def test_set_torrc_runtime_option_succesful(persistent_launch_tor):
+    controller = persistent_launch_tor
+    runtime_options = controller.get_conf_map(['__LeaveStreamsUnattached'])
+    assert runtime_options == {'__LeaveStreamsUnattached': ['1']}
+
+
+def test_set_torrc_runtime_invalidrequest_option_fail(persistent_launch_tor):
+    controller = persistent_launch_tor
+    try:
+        controller.set_conf('ControlSocket', '/tmp/dummy')
+    except stem_utils.InvalidRequest as e:
+        assert "Unable to set option" in e.message
+
+
+def test_set_torrc_options_can_fail_option_fail(persistent_launch_tor):
+    controller = persistent_launch_tor
+    try:
+        controller.set_conf('BadOption', '0')
+    except stem_utils.InvalidArguments as e:
+        assert "Unknown option" in e.message