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# Copyright (c) 2005, Neville-Neil Consulting
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# Neither the name of Neville-Neil Consulting nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# File: $Id: tcp.py,v 1.5 2006/07/06 09:31:57 gnn Exp $
#
# Author: George V. Neville-Neil
#
# Description: A class that describes a TCP packet.
import pcs
from pcs.packets import payload
class tcp(pcs.Packet):
"""A TCP class for IPv4"""
layout = pcs.Layout()
def __init__(self, bytes = None):
"""initialize a TCP packet"""
sport = pcs.Field("sport", 16)
dport = pcs.Field("dport", 16)
seq = pcs.Field("sequence", 32)
acknum = pcs.Field("ack_number", 32)
off = pcs.Field("offset", 4)
reserved = pcs.Field("reserved", 6)
urg = pcs.Field("urgent", 1)
ack = pcs.Field("ack", 1)
psh = pcs.Field("push", 1)
rst = pcs.Field("reset", 1)
syn = pcs.Field("syn", 1)
fin = pcs.Field("fin", 1)
window = pcs.Field("window", 16)
cksum = pcs.Field("checksum", 16)
urgp = pcs.Field("urg_pointer",16)
pcs.Packet.__init__(self, [sport, dport, seq, acknum, off, reserved,
urg, ack, psh, rst, syn, fin, window,
cksum, urgp],
bytes = bytes)
self.description = "TCP"
if (bytes != None):
offset = 20
self.data = payload.payload(bytes[offset:len(bytes)])
else:
self.data = None
def __str__(self):
"""Walk the entire packet and pretty print the values of the fields. Addresses are printed if and only if they are set and not 0."""
retval = ""
for field in self.layout:
if (field.type == str):
retval += "%s %s\n" % (field.name, self.__dict__[field.name])
else:
retval += "%s %d\n" % (field.name, self.__dict__[field.name])
return retval
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