This page hosts a formal specification of IPv4 network packet using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = Ipv4Packet.from_file("path/to/local/file.IPv4 network packet")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = Ipv4Packet(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.b1 # => get b1
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
from pkg_resources import parse_version
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
if parse_version(kaitaistruct.__version__) < parse_version('0.9'):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
import protocol_body
class Ipv4Packet(KaitaiStruct):
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.b1 = self._io.read_u1()
self.b2 = self._io.read_u1()
self.total_length = self._io.read_u2be()
self.identification = self._io.read_u2be()
self.b67 = self._io.read_u2be()
self.ttl = self._io.read_u1()
self.protocol = self._io.read_u1()
self.header_checksum = self._io.read_u2be()
self.src_ip_addr = self._io.read_bytes(4)
self.dst_ip_addr = self._io.read_bytes(4)
self._raw_options = self._io.read_bytes((self.ihl_bytes - 20))
_io__raw_options = KaitaiStream(BytesIO(self._raw_options))
self.options = Ipv4Packet.Ipv4Options(_io__raw_options, self, self._root)
self._raw_body = self._io.read_bytes((self.total_length - self.ihl_bytes))
_io__raw_body = KaitaiStream(BytesIO(self._raw_body))
self.body = protocol_body.ProtocolBody(self.protocol, _io__raw_body)
class Ipv4Options(KaitaiStruct):
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.entries = []
i = 0
while not self._io.is_eof():
self.entries.append(Ipv4Packet.Ipv4Option(self._io, self, self._root))
i += 1
class Ipv4Option(KaitaiStruct):
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.b1 = self._io.read_u1()
self.len = self._io.read_u1()
self.body = self._io.read_bytes(((self.len - 2) if self.len > 2 else 0))
@property
def copy(self):
if hasattr(self, '_m_copy'):
return self._m_copy if hasattr(self, '_m_copy') else None
self._m_copy = ((self.b1 & 128) >> 7)
return self._m_copy if hasattr(self, '_m_copy') else None
@property
def opt_class(self):
if hasattr(self, '_m_opt_class'):
return self._m_opt_class if hasattr(self, '_m_opt_class') else None
self._m_opt_class = ((self.b1 & 96) >> 5)
return self._m_opt_class if hasattr(self, '_m_opt_class') else None
@property
def number(self):
if hasattr(self, '_m_number'):
return self._m_number if hasattr(self, '_m_number') else None
self._m_number = (self.b1 & 31)
return self._m_number if hasattr(self, '_m_number') else None
@property
def version(self):
if hasattr(self, '_m_version'):
return self._m_version if hasattr(self, '_m_version') else None
self._m_version = ((self.b1 & 240) >> 4)
return self._m_version if hasattr(self, '_m_version') else None
@property
def ihl(self):
if hasattr(self, '_m_ihl'):
return self._m_ihl if hasattr(self, '_m_ihl') else None
self._m_ihl = (self.b1 & 15)
return self._m_ihl if hasattr(self, '_m_ihl') else None
@property
def ihl_bytes(self):
if hasattr(self, '_m_ihl_bytes'):
return self._m_ihl_bytes if hasattr(self, '_m_ihl_bytes') else None
self._m_ihl_bytes = (self.ihl * 4)
return self._m_ihl_bytes if hasattr(self, '_m_ihl_bytes') else None