Add DBusGMethodInvocation accessor for the DBusGConnection

If you're using two connections, say a shared connection and a private
connection that uses DBusServer, there's no way to figure out which
DBusConnection a method invocation originates from, and thus no way
to do access control based on that.

Private bus setup done with eg:

void new_conn_func(DBusServer *s, DBusConnection *conn, gpointer to_export)
{
  DBusGConnection *gconn;

  /* set access control, eg with dbus_connection_set_unix_user_function() */
  dbus_connection_setup_with_g_main(conn, NULL);

  gconn = dbus_connection_get_g_connection(conn);
  dbus_g_connection_register_object(gconn, "/foo", G_OBJECT (to_export));
}

void start_server(GObject *to_export)
{
  DBusServer *s;

  s = dbus_server_listen("unix:path=/var/foo", NULL);
  dbus_server_setup_with_g_main (s, NULL);
  dbus_server_set_new_connection_function (s, new_conn_func, to_export);
}

Reviewed-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=55729

2 files changed, 18 insertions, 0 deletions

diff --git a/dbus/dbus-glib.h b/dbus/dbus-glib.h
index bd5784c..9aa71c1 100644
--- a/dbus/dbus-glib.h
+++ b/dbus/dbus-glib.h
@@ -329,6 +329,8 @@ void              dbus_g_method_return               (DBusGMethodInvocation *con
 
 void              dbus_g_method_return_error         (DBusGMethodInvocation *context, const GError *error);
 
+DBusGConnection * dbus_g_method_invocation_get_g_connection (DBusGMethodInvocation *context);
+
 /* Probably possible to replace this with a closure */
 typedef struct {
   GCallback cb;
diff --git a/dbus/dbus-gobject.c b/dbus/dbus-gobject.c
index bac91be..9889836 100644
--- a/dbus/dbus-gobject.c
+++ b/dbus/dbus-gobject.c
@@ -3276,6 +3276,22 @@ out:
   g_free (context);
 }
 
+/**
+ * dbus_g_method_invocation_get_g_connection:
+ * @context: the method context
+ *
+ * <!-- Returns: says it all -->
+ *
+ * Returns: (transfer none): the @DBusGConnection from which the method was called.
+ */
+DBusGConnection *
+dbus_g_method_invocation_get_g_connection (DBusGMethodInvocation *context)
+{
+  g_return_val_if_fail (context != NULL, NULL);
+
+  return context->connection;
+}
+
 const char *
 _dbus_gobject_get_path (GObject *obj)
 {