packet: Add VXLAN parser

IANA has assigned the value 4789 for the VXLAN UDP destination port,
this patch registers dst_port 4789 into UDP packet parser.
Additionally, early adopters might be using UDP dst_port 8472,
we register this number for the backward compatibility.

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/lib/packet/udp.py

@@ -18,6 +18,7 @@ import struct
 from . import packet_base
 from . import packet_utils
 from . import dhcp
+from . import vxlan
 
 
 class udp(packet_base.PacketBase):
@@ -49,10 +50,14 @@ class udp(packet_base.PacketBase):
         self.total_length = total_length
         self.csum = csum
 
-    @classmethod
-    def get_packet_type(cls, src_port, dst_port):
-        if (src_port == 68 and dst_port == 67) or (src_port == 67 and dst_port == 68):
+    @staticmethod
+    def get_packet_type(src_port, dst_port):
+        if ((src_port == 68 and dst_port == 67) or
+                (src_port == 67 and dst_port == 68)):
             return dhcp.dhcp
+        if (dst_port == vxlan.UDP_DST_PORT or
+                dst_port == vxlan.UDP_DST_PORT_OLD):
+            return vxlan.vxlan
         return None
 
     @classmethod

ryu/lib/packet/vxlan.py

@@ -0,0 +1,90 @@
+# Copyright (C) 2016 Nippon Telegraph and Telephone Corporation.
+#
+# 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.
+
+"""
+VXLAN packet parser/serializer
+
+RFC 7348
+VXLAN Header:
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|R|R|R|R|I|R|R|R|            Reserved                           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                VXLAN Network Identifier (VNI) |   Reserved    |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+- Flags (8 bits): where the I flag MUST be set to 1 for a valid
+  VXLAN Network ID (VNI).  The other 7 bits (designated "R") are
+  reserved fields and MUST be set to zero on transmission and
+  ignored on receipt.
+
+- VXLAN Segment ID/VXLAN Network Identifier (VNI): this is a
+  24-bit value used to designate the individual VXLAN overlay
+  network on which the communicating VMs are situated.  VMs in
+  different VXLAN overlay networks cannot communicate with each
+  other.
+
+- Reserved fields (24 bits and 8 bits): MUST be set to zero on
+  transmission and ignored on receipt.
+"""
+
+import struct
+import logging
+
+from . import packet_base
+
+
+LOG = logging.getLogger(__name__)
+
+UDP_DST_PORT = 4789
+UDP_DST_PORT_OLD = 8472  # for backward compatibility like Linux
+
+
+class vxlan(packet_base.PacketBase):
+    """VXLAN (RFC 7348) header encoder/decoder class.
+
+    An instance has the following attributes at least.
+    Most of them are same to the on-wire counterparts but in host byte order.
+    __init__ takes the corresponding args in this order.
+
+    ============== ====================
+    Attribute      Description
+    ============== ====================
+    vni            VXLAN Network Identifier
+    ============== ====================
+    """
+
+    # Note: Python has no format character for 24 bits field.
+    # we use uint32 format character instead and bit-shift at serializing.
+    _PACK_STR = '!II'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
+
+    def __init__(self, vni):
+        super(vxlan, self).__init__()
+        self.vni = vni
+
+    @classmethod
+    def parser(cls, buf):
+        (flags_reserved, vni_rserved) = struct.unpack_from(cls._PACK_STR, buf)
+
+        # Check VXLAN flags is valid
+        assert (1 << 3) == (flags_reserved >> 24)
+
+        # Note: To avoid cyclic import, import ethernet module here
+        from ryu.lib.packet import ethernet
+        return cls(vni_rserved >> 8), ethernet.ethernet, buf[cls._MIN_LEN:]
+
+    def serialize(self, payload, prev):
+        return struct.pack(self._PACK_STR,
+                           1 << (3 + 24), self.vni << 8)

ryu/tests/unit/packet/test_vxlan.py

@@ -0,0 +1,75 @@
+# Copyright (C) 2016 Nippon Telegraph and Telephone Corporation.
+#
+# 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.
+
+import logging
+import unittest
+
+from nose.tools import eq_
+from nose.tools import raises
+
+from ryu.lib.packet import ethernet
+from ryu.lib.packet import vxlan
+
+
+LOG = logging.getLogger(__name__)
+
+
+class Test_vxlan(unittest.TestCase):
+    """
+    Test case for VXLAN (RFC 7348) header encoder/decoder class.
+    """
+
+    vni = 0x123456
+    buf = (
+        b'\x08\x00\x00\x00'  # flags = R|R|R|R|I|R|R|R (8 bits)
+        b'\x12\x34\x56\x00'  # vni = 0x123456 (24 bits)
+        b'test_payload'      # for test
+    )
+    pkt = vxlan.vxlan(vni)
+    jsondict = {
+        'vxlan': {
+            'vni': vni
+        }
+    }
+
+    def test_init(self):
+        eq_(self.vni, self.pkt.vni)
+
+    def test_parser(self):
+        parsed_pkt, next_proto_cls, rest_buf = vxlan.vxlan.parser(self.buf)
+        eq_(self.vni, parsed_pkt.vni)
+        eq_(ethernet.ethernet, next_proto_cls)
+        eq_(b'test_payload', rest_buf)
+
+    @raises(AssertionError)
+    def test_invalid_flags(self):
+        invalid_flags_bug = (
+            b'\x00\x00\x00\x00'  # all bits are set to zero
+            b'\x12\x34\x56\x00'  # vni = 0x123456 (24 bits)
+        )
+        vxlan.vxlan.parser(invalid_flags_bug)
+
+    def test_serialize(self):
+        serialized_buf = self.pkt.serialize(payload=None, prev=None)
+        eq_(self.buf[:vxlan.vxlan._MIN_LEN], serialized_buf)
+
+    def test_from_jsondict(self):
+        pkt_from_json = vxlan.vxlan.from_jsondict(
+            self.jsondict[vxlan.vxlan.__name__])
+        eq_(self.vni, pkt_from_json.vni)
+
+    def test_to_jsondict(self):
+        jsondict_from_pkt = self.pkt.to_jsondict()
+        eq_(self.jsondict, jsondict_from_pkt)