From 4d00bc802543dc0585af01ef88d0b33bb3f6f6aa Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Mon, 27 Aug 2012 11:37:31 +0900
Subject: packet lib: add tcp support

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
---
 ryu/lib/packet/ipv4.py |  2 ++
 ryu/lib/packet/tcp.py  | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 ryu/lib/packet/tcp.py

diff --git a/ryu/lib/packet/ipv4.py b/ryu/lib/packet/ipv4.py
index cb5bc4e4..bd7b6330 100644
--- a/ryu/lib/packet/ipv4.py
+++ b/ryu/lib/packet/ipv4.py
@@ -17,6 +17,7 @@ import struct
 from . import packet_base
 from . import packet_utils
 from . import udp
+from . import tcp
 from ryu.ofproto import inet
 
 
@@ -70,4 +71,5 @@ class ipv4(packet_base.PacketBase):
         struct.pack_into('H', hdr, 10, self.csum)
         return hdr
 
+ipv4.register_packet_type(tcp.tcp, inet.IPPROTO_TCP)
 ipv4.register_packet_type(udp.udp, inet.IPPROTO_UDP)
diff --git a/ryu/lib/packet/tcp.py b/ryu/lib/packet/tcp.py
new file mode 100644
index 00000000..975bfcca
--- /dev/null
+++ b/ryu/lib/packet/tcp.py
@@ -0,0 +1,65 @@
+# Copyright (C) 2012 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
+import socket
+from . import packet_base
+from . import packet_utils
+import ipv4
+
+
+class tcp(packet_base.PacketBase):
+    _PACK_STR = '!HHIIBBHHH'
+
+    def __init__(self, src_port, dst_port, seq, ack, offset,
+                 bits, window_size, csum, urgent):
+        super(tcp, self).__init__()
+        self.src_port = src_port
+        self.dst_port = dst_port
+        self.seq = seq
+        self.ack = ack
+        self.offset = offset
+        self.bits = bits
+        self.window_size = window_size
+        self.csum = csum
+        self.urgent = urgent
+        self.length = self.offset * 4
+
+    @classmethod
+    def parser(cls, buf):
+        (src_port, dst_port, seq, ack, offset, bits, window_size,
+         csum, urgent) = struct.unpack_from(cls._PACK_STR, buf)
+        offset = offset >> 4
+        bits = bits & 0x3f
+        msg = cls(src_port, dst_port, seq, ack, offset, bits,
+                  window_size, csum, urgent)
+        return msg, None
+
+    def serialize(self, payload, prev):
+        offset = self.offset << 4
+        h = struct.pack(tcp._PACK_STR, self.src_port, self.dst_port,
+                        self.seq, self.ack, offset, self.bits,
+                        self.window_size, self.csum, self.urgent)
+        if self.csum == 0:
+            length = self.length + len(payload)
+            ph = struct.pack('!IIBBH', prev.src, prev.dst, 0, 6, length)
+            f = ph + h + payload
+            if len(f) % 2:
+                f += '\0'
+            self.csum = socket.htons(packet_utils.checksum(f))
+            h = struct.pack(tcp._PACK_STR, self.src_port, self.dst_port,
+                            self.seq, self.ack, offset, self.bits,
+                            self.window_size, self.csum, self.urgent)
+        return h
-- 
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