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.bin")
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
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (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
self._m_copy = ((self.b1 & 128) >> 7)
return getattr(self, '_m_copy', None)
@property
def opt_class(self):
if hasattr(self, '_m_opt_class'):
return self._m_opt_class
self._m_opt_class = ((self.b1 & 96) >> 5)
return getattr(self, '_m_opt_class', None)
@property
def number(self):
if hasattr(self, '_m_number'):
return self._m_number
self._m_number = (self.b1 & 31)
return getattr(self, '_m_number', None)
@property
def version(self):
if hasattr(self, '_m_version'):
return self._m_version
self._m_version = ((self.b1 & 240) >> 4)
return getattr(self, '_m_version', None)
@property
def ihl(self):
if hasattr(self, '_m_ihl'):
return self._m_ihl
self._m_ihl = (self.b1 & 15)
return getattr(self, '_m_ihl', None)
@property
def ihl_bytes(self):
if hasattr(self, '_m_ihl_bytes'):
return self._m_ihl_bytes
self._m_ihl_bytes = (self.ihl * 4)
return getattr(self, '_m_ihl_bytes', None)