Revert "Revert "ipsec: VPP-1316 calculate IP/TCP/UDP inner checksums""

This reverts commit e0d2bd6bd7.

Change-Id: If491e16f9ea66b2493a6a7c7f3c684ed585f8f51
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/vpp_tunnel_interface.py

@@ -0,0 +1,32 @@
+from abc import abstractmethod, ABCMeta
+from vpp_pg_interface import is_ipv6_misc
+from vpp_interface import VppInterface
+
+
+class VppTunnelInterface(VppInterface):
+    """ VPP tunnel interface abstration """
+    __metaclass__ = ABCMeta
+
+    @abstractmethod
+    def __init__(self, test, parent_if):
+        super(VppTunnelInterface, self).__init__(test)
+        self.parent_if = parent_if
+
+    @property
+    def local_mac(self):
+        return self.parent_if.local_mac
+
+    @property
+    def remote_mac(self):
+        return self.parent_if.remote_mac
+
+    def enable_capture(self):
+        return self.parent_if.enable_capture()
+
+    def add_stream(self, pkts):
+        return self.parent_if.add_stream(pkts)
+
+    def get_capture(self, expected_count=None, remark=None, timeout=1,
+                    filter_out_fn=is_ipv6_misc):
+        return self.parent_if.get_capture(expected_count, remark, timeout,
+                                          filter_out_fn)