packet lib: add linux cooked header support

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/lib/packet/linux.py

@@ -0,0 +1,62 @@
+# Copyright (C) 2014 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 struct
+from . import packet_base
+from . import vlan
+from . import mpls
+from ryu.ofproto import ether
+from ryu.lib import addrconv
+
+
+class linuxcooked(packet_base.PacketBase):
+    _PACK_STR = '!HHH8sH'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
+
+    def __init__(self, pkt_type, arphrd_type, address_length, address,
+                 proto_type):
+        super(linuxcooked, self).__init__()
+        self.pkt_type = pkt_type
+        self.arphrd_type = arphrd_type
+        self.address_length = address_length
+        self.address = address
+        self.proto_type = proto_type
+
+    @classmethod
+    def parser(cls, buf):
+        (pkt_type, arphrd_type, address_length, addres,
+         proto_type) = struct.unpack_from(cls._PACK_STR, buf)
+        l = cls(pkt_type, arphrd_type, address_length, addres, proto_type)
+        return (l, linuxcooked.get_packet_type(proto_type),
+                buf[linuxcooked._MIN_LEN:])
+
+    @classmethod
+    def get_packet_type(cls, type_):
+        """Override method for the ethernet IEEE802.3 Length/Type
+        field (self.ethertype).
+
+        If the value of Length/Type field is less than or equal to
+        1500 decimal(05DC hexadecimal), it means Length interpretation
+        and be passed to the LLC sublayer."""
+        if type_ <= ether.ETH_TYPE_IEEE802_3:
+            type_ = ether.ETH_TYPE_IEEE802_3
+        return cls._TYPES.get(type_)
+
+
+# copy vlan _TYPES
+linuxcooked._TYPES = vlan.vlan._TYPES
+linuxcooked.register_packet_type(vlan.vlan, ether.ETH_TYPE_8021Q)
+linuxcooked.register_packet_type(vlan.svlan, ether.ETH_TYPE_8021AD)
+linuxcooked.register_packet_type(mpls.mpls, ether.ETH_TYPE_MPLS)