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# $Id: sctp.py 23 2006-11-08 15:45:33Z dugsong $
# -*- coding: utf-8 -*-
"""Stream Control Transmission Protocol."""
from __future__ import print_function
from __future__ import absolute_import
from . import dpkt
from . import crc32c
# Stream Control Transmission Protocol
# http://tools.ietf.org/html/rfc2960
# Chunk Types
DATA = 0
INIT = 1
INIT_ACK = 2
SACK = 3
HEARTBEAT = 4
HEARTBEAT_ACK = 5
ABORT = 6
SHUTDOWN = 7
SHUTDOWN_ACK = 8
ERROR = 9
COOKIE_ECHO = 10
COOKIE_ACK = 11
ECNE = 12
CWR = 13
SHUTDOWN_COMPLETE = 14
class SCTP(dpkt.Packet):
"""Stream Control Transmission Protocol.
TODO: Longer class information....
Attributes:
__hdr__: Header fields of SCTP.
TODO.
"""
__hdr__ = (
('sport', 'H', 0),
('dport', 'H', 0),
('vtag', 'I', 0),
('sum', 'I', 0)
)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
l_ = []
while self.data:
chunk = Chunk(self.data)
l_.append(chunk)
if len(chunk) == 0:
self.data = b''
break
self.data = self.data[len(chunk):]
self.chunks = l_
def __len__(self):
return self.__hdr_len__ + sum(len(x) for x in self.chunks)
def __bytes__(self):
l_ = [bytes(x) for x in self.chunks]
if self.sum == 0:
s = crc32c.add(0xffffffff, self.pack_hdr())
for x in l_:
s = crc32c.add(s, x)
self.sum = crc32c.done(s)
return self.pack_hdr() + b''.join(l_)
class Chunk(dpkt.Packet):
__hdr__ = (
('type', 'B', INIT),
('flags', 'B', 0),
('len', 'H', 0)
)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
self.data = self.data[:self.len - self.__hdr_len__]
self.padding = b'' # optional padding for DATA chunks
# SCTP DATA Chunked is padded, 4-bytes aligned
if self.type == DATA and self.len % 4:
plen = 4 - self.len % 4 # padded length
if plen:
pos = self.__hdr_len__ + len(self.data) # end of data in buf
self.padding = buf[pos:pos + plen]
def __len__(self):
return self.len + len(self.padding)
def __bytes__(self):
return self.pack_hdr() + bytes(self.data) + self.padding
__s = (b'\x80\x44\x00\x50\x00\x00\x00\x00\x30\xba\xef\x54\x01\x00\x00\x3c\x3b\xb9\x9c\x46\x00\x01'
b'\xa0\x00\x00\x0a\xff\xff\x2b\x2d\x7e\xb2\x00\x05\x00\x08\x9b\xe6\x18\x9b\x00\x05\x00\x08'
b'\x9b\xe6\x18\x9c\x00\x0c\x00\x06\x00\x05\x00\x00\x80\x00\x00\x04\xc0\x00\x00\x04\xc0\x06'
b'\x00\x08\x00\x00\x00\x00')
def test_sctp_pack():
sctp = SCTP(__s)
assert (__s == bytes(sctp))
sctp.sum = 0
assert (__s == bytes(sctp))
def test_sctp_unpack():
sctp = SCTP(__s)
assert (sctp.sport == 32836)
assert (sctp.dport == 80)
assert (len(sctp.chunks) == 1)
assert (len(sctp) == 72)
chunk = sctp.chunks[0]
assert (chunk.type == INIT)
assert (chunk.len == 60)
def test_sctp_data_chunk(): # https://github.com/kbandla/dpkt/issues/499
# packet 5 from 'sctp-www.cap' downloaded from https://wiki.wireshark.org/SampleCaptures
# chunk len == 419 so requires padding to a 4-byte boundary
d = (b'\x80\x44\x00\x50\xd2\x6a\xc1\xe5\x70\xe5\x5b\x4c\x00\x03\x01\xa3\x2b\x2d\x7e\xb2\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x47\x45\x54\x20\x2f\x20\x48\x54\x54\x50\x2f\x31\x2e\x31\x0d\x0a'
b'\x48\x6f\x73\x74\x3a\x20\x32\x30\x33\x2e\x32\x35\x35\x2e\x32\x35\x32\x2e\x31\x39\x34\x0d'
b'\x0a\x55\x73\x65\x72\x2d\x41\x67\x65\x6e\x74\x3a\x20\x4d\x6f\x7a\x69\x6c\x6c\x61\x2f\x35'
b'\x2e\x30\x20\x28\x58\x31\x31\x3b\x20\x55\x3b\x20\x4c\x69\x6e\x75\x78\x20\x69\x36\x38\x36'
b'\x3b\x20\x6b\x6f\x2d\x4b\x52\x3b\x20\x72\x76\x3a\x31\x2e\x37\x2e\x31\x32\x29\x20\x47\x65'
b'\x63\x6b\x6f\x2f\x32\x30\x30\x35\x31\x30\x30\x37\x20\x44\x65\x62\x69\x61\x6e\x2f\x31\x2e'
b'\x37\x2e\x31\x32\x2d\x31\x0d\x0a\x41\x63\x63\x65\x70\x74\x3a\x20\x74\x65\x78\x74\x2f\x78'
b'\x6d\x6c\x2c\x61\x70\x70\x6c\x69\x63\x61\x74\x69\x6f\x6e\x2f\x78\x6d\x6c\x2c\x61\x70\x70'
b'\x6c\x69\x63\x61\x74\x69\x6f\x6e\x2f\x78\x68\x74\x6d\x6c\x2b\x78\x6d\x6c\x2c\x74\x65\x78'
b'\x74\x2f\x68\x74\x6d\x6c\x3b\x71\x3d\x30\x2e\x39\x2c\x74\x65\x78\x74\x2f\x70\x6c\x61\x69'
b'\x6e\x3b\x71\x3d\x30\x2e\x38\x2c\x69\x6d\x61\x67\x65\x2f\x70\x6e\x67\x2c\x2a\x2f\x2a\x3b'
b'\x71\x3d\x30\x2e\x35\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x4c\x61\x6e\x67\x75\x61\x67\x65'
b'\x3a\x20\x6b\x6f\x2c\x65\x6e\x2d\x75\x73\x3b\x71\x3d\x30\x2e\x37\x2c\x65\x6e\x3b\x71\x3d'
b'\x30\x2e\x33\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x45\x6e\x63\x6f\x64\x69\x6e\x67\x3a\x20'
b'\x67\x7a\x69\x70\x2c\x64\x65\x66\x6c\x61\x74\x65\x0d\x0a\x41\x63\x63\x65\x70\x74\x2d\x43'
b'\x68\x61\x72\x73\x65\x74\x3a\x20\x45\x55\x43\x2d\x4b\x52\x2c\x75\x74\x66\x2d\x38\x3b\x71'
b'\x3d\x30\x2e\x37\x2c\x2a\x3b\x71\x3d\x30\x2e\x37\x0d\x0a\x4b\x65\x65\x70\x2d\x41\x6c\x69'
b'\x76\x65\x3a\x20\x33\x30\x30\x0d\x0a\x43\x6f\x6e\x6e\x65\x63\x74\x69\x6f\x6e\x3a\x20\x6b'
b'\x65\x65\x70\x2d\x61\x6c\x69\x76\x65\x0d\x0a\x0d\x0a\x00') # <-- ends with \x00 padding
sctp = SCTP(d)
assert sctp.chunks
assert len(sctp.chunks) == 1
ch = sctp.chunks[0]
assert ch.type == DATA
assert ch.len == 419
assert len(ch) == 420 # 419 +1 byte padding
assert ch.data[-14:] == b'keep-alive\r\n\r\n' # no padding byte at the end
# no remaining sctp data
assert sctp.data == b''
# test packing of the padded chunk
assert bytes(ch) == d[SCTP.__hdr_len__:]
def test_malformed_sctp_data_chunk():
# packet 7964 from '4.pcap' downloaded from https://research.unsw.edu.au/projects/unsw-nb15-dataset
d = (b'\x27\x0f\xe1\xc3\xc2\x73\x4d\x32\x4f\x54\x27\x8c' #header
b'\x0b\x00\x00\x04' #chunk 0, COOKIE_ACK chunk
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00') #chunk 1, malformed DATA chunk, size labeled as 0
sctp = SCTP(d)
assert sctp.chunks
assert len(sctp.chunks) == 2
ch = sctp.chunks[1]
assert ch.type == DATA
assert ch.len == 0
assert len(ch) == 0
assert ch.data == b'\x00\x00'
# no remaining sctp data
assert sctp.data == b''
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