netd: Add primitive NAT control

Update: Add stub function to validate interface existance

Signed-off-by: San Mehat <san@google.com>
diff --git a/NatController.h b/NatController.h
new file mode 100644
index 0000000..4182f1d
--- /dev/null
+++ b/NatController.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _NAT_CONTROLLER_H
+#define _NAT_CONTROLLER_H
+
+#include <linux/in.h>
+
+#include <utils/List.h>
+
+class NatController {
+
+public:
+    NatController();
+    virtual ~NatController();
+
+    int enableNat(const char *intIface, const char *extIface);
+    int disableNat(const char *intIface, const char *extIface);
+
+private:
+    int setDefaults();
+    int runIptablesCmd(const char *cmd);
+    bool interfaceExists(const char *iface);
+};
+
+#endif