packet/vxlan: Add method to convert the format of vni

Signed-off-by: Shinpei Muraoka <shinpei.muraoka@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/lib/packet/vxlan.py

@@ -42,8 +42,10 @@ VXLAN Header:
 import struct
 import logging
 
-from . import packet_base
+import six
 
+from . import packet_base
+from ryu.lib import type_desc
 
 LOG = logging.getLogger(__name__)
 
@@ -88,3 +90,21 @@ class vxlan(packet_base.PacketBase):
     def serialize(self, payload, prev):
         return struct.pack(self._PACK_STR,
                            1 << (3 + 24), self.vni << 8)
+
+
+def vni_from_bin(buf):
+    """
+    Converts binary representation VNI to integer.
+    :param buf: binary representation of VNI.
+    :return: VNI integer.
+    """
+    return type_desc.Int3.to_user(six.binary_type(buf))
+
+
+def vni_to_bin(vni):
+    """
+    Converts integer VNI to binary representation.
+    :param vni: integer of VNI
+    :return: binary representation of VNI.
+    """
+    return type_desc.Int3.from_user(vni)

ryu/tests/unit/packet/test_vxlan.py

@@ -73,3 +73,10 @@ class Test_vxlan(unittest.TestCase):
     def test_to_jsondict(self):
         jsondict_from_pkt = self.pkt.to_jsondict()
         eq_(self.jsondict, jsondict_from_pkt)
+
+    def test_vni_from_bin(self):
+        vni = vxlan.vni_from_bin(b'\x12\x34\x56')
+        eq_(self.vni, vni)
+
+    def test_vni_to_bin(self):
+        eq_(b'\x12\x34\x56', vxlan.vni_to_bin(self.vni))