core: add NMDevice's GetAppliedConnection D-Bus call

Expose applied connection in D-Bus API.

https://bugzilla.gnome.org/show_bug.cgi?id=760884

2 files changed, 151 insertions, 9 deletions

diff --git a/introspection/nm-device.xml b/introspection/nm-device.xml
index eada289f28..f1033c73f2 100644
--- a/introspection/nm-device.xml
+++ b/introspection/nm-device.xml
@@ -172,15 +172,18 @@
     <method name="Reapply">
       <arg name="connection" type="a{sa{sv}}" direction="in">
         <tp:docstring>
-          The effective connection settings and properties to use. If empty, the connection
-          settings from the connection that is active on the device will be used.
+          The optional connection settings that will be reapplied on the device. If empty, the
+          currently active settings-connection will be used. The connection cannot arbitrarly
+          differ from the current applied-connection otherwise the call will fail.
+          Only certain changes are supported, like adding or removing IP addresses.
         </tp:docstring>
       </arg>
       <arg name="version_id" type="t" direction="in">
         <tp:docstring>
-            If non-zero, the current version id of the applied connection must match.
-            This optional argument allows to catch concurrent modifications when
-            reapplying the currently applied connection with modifications.
+          If non-zero, the current version id of the applied-connection must match.
+          The current version id can be retrieved via GetAppliedConnection.
+          This optional argument allows to catch concurrent modifications between
+          the GetAppliedConnection call and Reapply.
         </tp:docstring>
       </arg>
       <arg name="flags" type="u" direction="in">
@@ -190,10 +193,54 @@
         </tp:docstring>
       </arg>
       <tp:docstring>
-        Attempts to update the configuration of a device without deactivating it.
-        You can either modify the configuration by passing the desired setup via "connection"
-        argument or just omit the argument to bring it in sync with the connection that
-        has been activated but could have been modified  since.
+        Attempts to update the configuration of a device without deactivating it. NetworkManager
+        has the concept of connections, which are profiles that contain the configuration for
+        a networking device. Those connections are exposed via D-Bus as individual objects
+        that can be created, modified and deleted. When activating such a settings-connection
+        on a device, the settings-connection is cloned to become an applied-connection and used to
+        configure the device (see GetAppliedConnection). Subsequent modification of the
+        settings-connection don't propagate automatically to the device's applied-connection
+        (with exception of the firewall-zone and the metered property). For the changes to take
+        effect, you can either re-activate the settings-connection, or call Reapply.
+        The Reapply call allows you to directly update the applied-connection and reconfigure
+        the device.
+        Reapply can also be useful if the currently applied-connection is equal to the connection
+        that is about to be reapplied. This allows to reconfigure the device and revert external
+        changes like removing or adding an IP address (which NetworkManager doesn't revert
+        automatically because it is assumed that the user made these changes intentionally outside
+        of NetworkManager).
+        Reapply can make the applied-connection different from the settings-connection,
+        just like updating the settings-connection can make them different.
+      </tp:docstring>
+    </method>
+
+    <method name="GetAppliedConnection">
+      <arg name="flags" type="u" direction="in">
+        <tp:docstring>
+          Flags which would modify the behavior of the GetAppliedConnection call.
+          There are no flags defined currently and the users should use the value of 0.
+        </tp:docstring>
+      </arg>
+      <arg name="connection" type="a{sa{sv}}" direction="out">
+        <tp:docstring>
+            The effective connection settings that the connection has currently applied.
+        </tp:docstring>
+      </arg>
+      <arg name="version_id" type="t" direction="out">
+        <tp:docstring>
+            The version-id of the currently applied connection. This can be specified during
+            Reapply to avoid races where you first fetch the applied connection, modify it
+            and try to reapply it. If the applied connection is modified in the meantime, the
+            version_id gets incremented and Reapply will fail.
+        </tp:docstring>
+      </arg>
+      <tp:docstring>
+        Get the currently applied connection on the device. This is a snapshot of the last activated
+        connection on the device, that is the configuration that is currently applied on the device.
+        Usually this is the same as GetSettings of the referenced settings connection. However, it
+        can differ if the settings connection was subsequently modified or the applied connection was
+        modified by Reapply. The applied connection is set when activating a device or when calling
+        Reapply.
       </tp:docstring>
     </method>
 
diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 5d9903dc91..f20a0fc581 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -7366,6 +7366,100 @@ impl_device_reapply (NMDevice *self,
 	               reapply_data);
 }
 
+/*****************************************************************************/
+
+static void
+get_applied_connection_cb (NMDevice *self,
+                           GDBusMethodInvocation *context,
+                           NMAuthSubject *subject,
+                           GError *error,
+                           gpointer user_data /* possibly dangling pointer */)
+{
+	NMDevicePrivate *priv;
+	NMConnection *applied_connection;
+	GVariant *settings;
+
+	g_return_if_fail (NM_IS_DEVICE (self));
+
+	if (error) {
+		g_dbus_method_invocation_return_gerror (context, error);
+		return;
+	}
+
+	priv = NM_DEVICE_GET_PRIVATE (self);
+
+	applied_connection = nm_device_get_applied_connection (self);
+
+	if (!applied_connection) {
+		error = g_error_new_literal (NM_DEVICE_ERROR,
+		                             NM_DEVICE_ERROR_NOT_ACTIVE,
+		                             "Device is not activated");
+		g_dbus_method_invocation_take_error (context, error);
+		return;
+	}
+
+	if (applied_connection != user_data) {
+		/* The applied connection changed due to a race. Reauthenticate. */
+		g_signal_emit (self, signals[AUTH_REQUEST], 0,
+		               context,
+		               applied_connection,
+		               NM_AUTH_PERMISSION_NETWORK_CONTROL,
+		               TRUE,
+		               get_applied_connection_cb,
+		               applied_connection /* no need take a ref. We will not dereference this pointer. */);
+		return;
+	}
+
+	settings = nm_connection_to_dbus (applied_connection, NM_CONNECTION_SERIALIZE_NO_SECRETS);
+	if (!settings)
+		settings = g_variant_new_array (G_VARIANT_TYPE ("{sa{sv}}"), NULL, 0);
+
+	g_dbus_method_invocation_return_value (context,
+	                                       g_variant_new ("(@a{sa{sv}}t)",
+	                                                      settings,
+	                                                      nm_active_connection_version_id_get ((NMActiveConnection *) priv->act_request)));
+}
+
+static void
+impl_device_get_applied_connection (NMDevice *self,
+                                    GDBusMethodInvocation *context,
+                                    guint32 flags)
+{
+	NMConnection *applied_connection;
+	GError *error = NULL;
+
+	g_return_if_fail (NM_IS_DEVICE (self));
+
+	/* No flags supported as of now. */
+	if (flags != 0) {
+		error = g_error_new_literal (NM_DEVICE_ERROR,
+		                             NM_DEVICE_ERROR_FAILED,
+		                             "Invalid flags specified");
+		g_dbus_method_invocation_take_error (context, error);
+		return;
+	}
+
+	applied_connection = nm_device_get_applied_connection (self);
+	if (!applied_connection) {
+		error = g_error_new_literal (NM_DEVICE_ERROR,
+		                             NM_DEVICE_ERROR_NOT_ACTIVE,
+		                             "Device is not activated");
+		g_dbus_method_invocation_take_error (context, error);
+		return;
+	}
+
+	/* Ask the manager to authenticate this request for us */
+	g_signal_emit (self, signals[AUTH_REQUEST], 0,
+	               context,
+	               applied_connection,
+	               NM_AUTH_PERMISSION_NETWORK_CONTROL,
+	               TRUE,
+	               get_applied_connection_cb,
+	               applied_connection /* no need take a ref. We will not dereference this pointer. */);
+}
+
+/*****************************************************************************/
+
 static void
 disconnect_cb (NMDevice *self,
                GDBusMethodInvocation *context,
@@ -11724,6 +11818,7 @@ nm_device_class_init (NMDeviceClass *klass)
 	nm_exported_object_class_add_interface (NM_EXPORTED_OBJECT_CLASS (klass),
 	                                        NMDBUS_TYPE_DEVICE_SKELETON,
 	                                        "Reapply", impl_device_reapply,
+	                                        "GetAppliedConnection", impl_device_get_applied_connection,
 	                                        "Disconnect", impl_device_disconnect,
 	                                        "Delete", impl_device_delete,
 	                                        NULL);