AUTOSAR SOME/IP Service Discovery: Python parsing library

The main tasks of the Service Discovery Protocol are communicating the availability of functional entities called services in the in-vehicle communication as well as controlling the send behavior of event messages. This allows sending only event messages to receivers requiring them (Publish/Subscribe). The solution described here is also known as SOME/IP-SD (Scalable service-Oriented MiddlewarE over IP - Service Discovery).

KS implementation details

License: CC0-1.0
Minimal Kaitai Struct required: 0.9

This page hosts a formal specification of AUTOSAR SOME/IP Service Discovery using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime 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 kaitaistruct

Code

Parse a local file and get structure in memory:

data = SomeIpSd.from_file("path/to/local/file.AUTOSAR SOME/IP Service Discovery")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

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

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

data.flags # => The SOME/IP-SD Header shall start with an 8 Bit field called flags.

Python source code to parse AUTOSAR SOME/IP Service Discovery

some_ip_sd.py

# 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 some_ip_sd_entries
import some_ip_sd_options
class SomeIpSd(KaitaiStruct):
    """The main tasks of the Service Discovery Protocol are communicating the
    availability of functional entities called services in the in-vehicle
    communication as well as controlling the send behavior of event messages.
    This allows sending only event messages to receivers requiring them (Publish/Subscribe).
    The solution described here is also known as SOME/IP-SD
    (Scalable service-Oriented MiddlewarE over IP - Service Discovery).
    
    .. seealso::
       Source - https://www.autosar.org/fileadmin/user_upload/standards/foundation/19-11/AUTOSAR_PRS_SOMEIPServiceDiscoveryProtocol.pdf
    """
    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.flags = SomeIpSd.SdFlags(self._io, self, self._root)
        self.reserved = self._io.read_bytes(3)
        self.len_entries = self._io.read_u4be()
        self._raw_entries = self._io.read_bytes(self.len_entries)
        _io__raw_entries = KaitaiStream(BytesIO(self._raw_entries))
        self.entries = some_ip_sd_entries.SomeIpSdEntries(_io__raw_entries)
        self.len_options = self._io.read_u4be()
        self._raw_options = self._io.read_bytes(self.len_options)
        _io__raw_options = KaitaiStream(BytesIO(self._raw_options))
        self.options = some_ip_sd_options.SomeIpSdOptions(_io__raw_options)

    class SdFlags(KaitaiStruct):
        """
        .. seealso::
           AUTOSAR_PRS_SOMEIPServiceDiscoveryProtocol.pdf - Figure 4.3
        """
        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.reboot = self._io.read_bits_int_be(1) != 0
            self.unicast = self._io.read_bits_int_be(1) != 0
            self.initial_data = self._io.read_bits_int_be(1) != 0
            self.reserved = self._io.read_bits_int_be(5)