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# $Id: tns.py 23 2006-11-08 15:45:33Z dugsong $
# -*- coding: utf-8 -*-
"""Transparent Network Substrate."""
from __future__ import print_function
from __future__ import absolute_import
from . import dpkt
class TNS(dpkt.Packet):
"""Transparent Network Substrate.
TODO: Longer class information....
Attributes:
__hdr__: Header fields of TNS.
TODO.
"""
__hdr__ = (
('length', 'H', 0),
('pktsum', 'H', 0),
('type', 'B', 0),
('rsvd', 'B', 0),
('hdrsum', 'H', 0),
('msg', '0s', b''),
)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
n = self.length - self.__hdr_len__
if n > len(self.data):
raise dpkt.NeedData('short message (missing %d bytes)' %
(n - len(self.data)))
self.msg = self.data[:n]
self.data = self.data[n:]
def test_tns():
s = (b'\x00\x23\x00\x00\x01\x00\x00\x00\x01\x34\x01\x2c\x00\x00\x08\x00\x7f'
b'\xff\x4f\x98\x00\x00\x00\x01\x00\x01\x00\x22\x00\x00\x00\x00\x01\x01X')
t = TNS(s)
assert t.msg.startswith(b'\x01\x34')
# test a truncated packet
try:
t = TNS(s[:-10])
except dpkt.NeedData:
pass
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