TCP (Transmission Control Protocol) segment: Python parsing library

TCP is one of the core Internet protocols on transport layer (AKA OSI layer 4), providing stateful connections with error checking, guarantees of delivery, order of segments and avoidance of duplicate delivery.

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of TCP (Transmission Control Protocol) segment using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Parse a local file and get structure in memory:

data = TcpSegment.from_file("path/to/local/file.TCP (Transmission Control Protocol) segment")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

raw = b"\x00\x01\x02..."
data = TcpSegment(KaitaiStream(BytesIO(raw)))

After that, one can get various attributes from the structure by invoking getter methods like:

data.src_port # => get src port

Python source code to parse TCP (Transmission Control Protocol) segment

tcp_segment.py

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

from pkg_resources import parse_version
from kaitaistruct import __version__ as ks_version, KaitaiStruct, KaitaiStream, BytesIO


if parse_version(ks_version) < parse_version('0.7'):
    raise Exception("Incompatible Kaitai Struct Python API: 0.7 or later is required, but you have %s" % (ks_version))

class TcpSegment(KaitaiStruct):
    """TCP is one of the core Internet protocols on transport layer (AKA
    OSI layer 4), providing stateful connections with error checking,
    guarantees of delivery, order of segments and avoidance of duplicate
    delivery.
    """
    def __init__(self, _io, _parent=None, _root=None):
        self._io = _io
        self._parent = _parent
        self._root = _root if _root else self
        self._read()

    def _read(self):
        self.src_port = self._io.read_u2be()
        self.dst_port = self._io.read_u2be()
        self.seq_num = self._io.read_u4be()
        self.ack_num = self._io.read_u4be()
        self.b12 = self._io.read_u1()
        self.b13 = self._io.read_u1()
        self.window_size = self._io.read_u2be()
        self.checksum = self._io.read_u2be()
        self.urgent_pointer = self._io.read_u2be()
        self.body = self._io.read_bytes_full()