From 96d5be05e01489b0371c03b71efabea4dd82874e Mon Sep 17 00:00:00 2001 From: Yuichi Ito Date: Fri, 1 Nov 2013 14:15:52 +0900 Subject: [PATCH] packet lib: tcp: support default parameters and the auto calculation of offset Signed-off-by: Yuichi Ito Signed-off-by: FUJITA Tomonori --- ryu/lib/packet/tcp.py | 35 +++++++++++++++--------- ryu/tests/unit/packet/test_tcp.py | 45 +++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+), 12 deletions(-) diff --git a/ryu/lib/packet/tcp.py b/ryu/lib/packet/tcp.py index e6932ae6..a6f01678 100644 --- a/ryu/lib/packet/tcp.py +++ b/ryu/lib/packet/tcp.py @@ -33,7 +33,8 @@ class tcp(packet_base.PacketBase): dst_port Destination Port seq Sequence Number ack Acknowledgement Number - offset Data Offset + offset Data Offset \ + (0 means automatically-calculate when encoding) bits Control Bits window_size Window csum Checksum \ @@ -47,8 +48,8 @@ class tcp(packet_base.PacketBase): _PACK_STR = '!HHIIBBHHH' _MIN_LEN = struct.calcsize(_PACK_STR) - def __init__(self, src_port, dst_port, seq, ack, offset, - bits, window_size, csum, urgent, option=None): + def __init__(self, src_port=0, dst_port=0, seq=0, ack=0, offset=0, + bits=0, window_size=0, csum=0, urgent=0, option=None): super(tcp, self).__init__() self.src_port = src_port self.dst_port = dst_port @@ -81,20 +82,30 @@ class tcp(packet_base.PacketBase): return msg, None, buf[length:] def serialize(self, payload, prev): - length = len(self) - h = bytearray(length) offset = self.offset << 4 - struct.pack_into(tcp._PACK_STR, h, 0, self.src_port, self.dst_port, - self.seq, self.ack, offset, self.bits, - self.window_size, self.csum, self.urgent) + h = bytearray(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.option: - assert (length - tcp._MIN_LEN) >= len(self.option) - h[tcp._MIN_LEN:tcp._MIN_LEN + len(self.option)] = self.option + h.extend(self.option) + mod = len(self.option) % 4 + if mod: + h.extend(bytearray(4 - mod)) + if self.offset: + offset = self.offset << 2 + if len(h) < offset: + h.extend(bytearray(offset - len(h))) + + if 0 == self.offset: + self.offset = len(h) >> 2 + offset = self.offset << 4 + struct.pack_into('!B', h, 12, offset) if self.csum == 0: - total_length = length + len(payload) + total_length = len(h) + len(payload) self.csum = packet_utils.checksum_ip(prev, total_length, h + payload) struct.pack_into('!H', h, 16, self.csum) - return h + return str(h) diff --git a/ryu/tests/unit/packet/test_tcp.py b/ryu/tests/unit/packet/test_tcp.py index 5618652a..41689026 100644 --- a/ryu/tests/unit/packet/test_tcp.py +++ b/ryu/tests/unit/packet/test_tcp.py @@ -138,3 +138,48 @@ class Test_tcp(unittest.TestCase): def test_malformed_tcp(self): m_short_buf = self.buf[1:tcp._MIN_LEN] tcp.parser(m_short_buf) + + def test_default_args(self): + prev = ipv4(proto=inet.IPPROTO_TCP) + t = tcp() + buf = t.serialize(bytearray(), prev) + res = struct.unpack(tcp._PACK_STR, buf) + + eq_(res[0], 0) + eq_(res[1], 0) + eq_(res[2], 0) + eq_(res[3], 0) + eq_(res[4], 5 << 4) + eq_(res[5], 0) + eq_(res[6], 0) + eq_(res[8], 0) + + # with option, without offset + t = tcp(option='\x01\x02\x03') + buf = t.serialize(bytearray(), prev) + res = struct.unpack(tcp._PACK_STR + '4s', buf) + + eq_(res[0], 0) + eq_(res[1], 0) + eq_(res[2], 0) + eq_(res[3], 0) + eq_(res[4], 6 << 4) + eq_(res[5], 0) + eq_(res[6], 0) + eq_(res[8], 0) + eq_(res[9], '\x01\x02\x03\x00') + + # with option, with long offset + t = tcp(offset=7, option='\x01\x02\x03') + buf = t.serialize(bytearray(), prev) + res = struct.unpack(tcp._PACK_STR + '8s', buf) + + eq_(res[0], 0) + eq_(res[1], 0) + eq_(res[2], 0) + eq_(res[3], 0) + eq_(res[4], 7 << 4) + eq_(res[5], 0) + eq_(res[6], 0) + eq_(res[8], 0) + eq_(res[9], '\x01\x02\x03\x00\x00\x00\x00\x00')