protocol_body: Python parsing library

Protocol body represents particular payload on transport level (OSI layer 4).

Typically this payload in encapsulated into network level (OSI layer 3) packet, which includes "protocol number" field that would be used to decide what's inside the payload and how to parse it. Thanks to IANA's standardization effort, multiple network level use the same IDs for these payloads named "protocol numbers".

This is effectively a "router" type: it expects to get protocol number as a parameter, and then invokes relevant type parser based on that parameter.

KS implementation details

License: CC0-1.0
Minimal Kaitai Struct required: 0.8

This page hosts a formal specification of protocol_body 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 = ProtocolBody.from_file("path/to/local/file.protocol_body")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

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

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

data.body # => get body

Python source code to parse protocol_body

protocol_body.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
from enum import Enum


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))

import tcp_segment
import ipv4_packet
import icmp_packet
import udp_datagram
import ipv6_packet
class ProtocolBody(KaitaiStruct):
    """Protocol body represents particular payload on transport level (OSI
    layer 4).
    
    Typically this payload in encapsulated into network level (OSI layer
    3) packet, which includes "protocol number" field that would be used
    to decide what's inside the payload and how to parse it. Thanks to
    IANA's standardization effort, multiple network level use the same
    IDs for these payloads named "protocol numbers".
    
    This is effectively a "router" type: it expects to get protocol
    number as a parameter, and then invokes relevant type parser based
    on that parameter.
    
    .. seealso::
       Source - http://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
    """

    class ProtocolEnum(Enum):
        hopopt = 0
        icmp = 1
        igmp = 2
        ggp = 3
        ipv4 = 4
        st = 5
        tcp = 6
        cbt = 7
        egp = 8
        igp = 9
        bbn_rcc_mon = 10
        nvp_ii = 11
        pup = 12
        argus = 13
        emcon = 14
        xnet = 15
        chaos = 16
        udp = 17
        mux = 18
        dcn_meas = 19
        hmp = 20
        prm = 21
        xns_idp = 22
        trunk_1 = 23
        trunk_2 = 24
        leaf_1 = 25
        leaf_2 = 26
        rdp = 27
        irtp = 28
        iso_tp4 = 29
        netblt = 30
        mfe_nsp = 31
        merit_inp = 32
        dccp = 33
        x_3pc = 34
        idpr = 35
        xtp = 36
        ddp = 37
        idpr_cmtp = 38
        tp_plus_plus = 39
        il = 40
        ipv6 = 41
        sdrp = 42
        ipv6_route = 43
        ipv6_frag = 44
        idrp = 45
        rsvp = 46
        gre = 47
        dsr = 48
        bna = 49
        esp = 50
        ah = 51
        i_nlsp = 52
        swipe = 53
        narp = 54
        mobile = 55
        tlsp = 56
        skip = 57
        ipv6_icmp = 58
        ipv6_nonxt = 59
        ipv6_opts = 60
        any_host_internal_protocol = 61
        cftp = 62
        any_local_network = 63
        sat_expak = 64
        kryptolan = 65
        rvd = 66
        ippc = 67
        any_distributed_file_system = 68
        sat_mon = 69
        visa = 70
        ipcv = 71
        cpnx = 72
        cphb = 73
        wsn = 74
        pvp = 75
        br_sat_mon = 76
        sun_nd = 77
        wb_mon = 78
        wb_expak = 79
        iso_ip = 80
        vmtp = 81
        secure_vmtp = 82
        vines = 83
        ttp_or_iptm = 84
        nsfnet_igp = 85
        dgp = 86
        tcf = 87
        eigrp = 88
        ospfigp = 89
        sprite_rpc = 90
        larp = 91
        mtp = 92
        ax_25 = 93
        ipip = 94
        micp = 95
        scc_sp = 96
        etherip = 97
        encap = 98
        any_private_encryption_scheme = 99
        gmtp = 100
        ifmp = 101
        pnni = 102
        pim = 103
        aris = 104
        scps = 105
        qnx = 106
        a_n = 107
        ipcomp = 108
        snp = 109
        compaq_peer = 110
        ipx_in_ip = 111
        vrrp = 112
        pgm = 113
        any_0_hop = 114
        l2tp = 115
        ddx = 116
        iatp = 117
        stp = 118
        srp = 119
        uti = 120
        smp = 121
        sm = 122
        ptp = 123
        isis_over_ipv4 = 124
        fire = 125
        crtp = 126
        crudp = 127
        sscopmce = 128
        iplt = 129
        sps = 130
        pipe = 131
        sctp = 132
        fc = 133
        rsvp_e2e_ignore = 134
        mobility_header = 135
        udplite = 136
        mpls_in_ip = 137
        manet = 138
        hip = 139
        shim6 = 140
        wesp = 141
        rohc = 142
        reserved_255 = 255
    def __init__(self, protocol_num, _io, _parent=None, _root=None):
        self._io = _io
        self._parent = _parent
        self._root = _root if _root else self
        self.protocol_num = protocol_num
        self._read()

    def _read(self):
        _on = self.protocol
        if _on == self._root.ProtocolEnum.ipv6_nonxt:
            self.body = self._root.NoNextHeader(self._io, self, self._root)
        elif _on == self._root.ProtocolEnum.ipv4:
            self.body = ipv4_packet.Ipv4Packet(self._io)
        elif _on == self._root.ProtocolEnum.udp:
            self.body = udp_datagram.UdpDatagram(self._io)
        elif _on == self._root.ProtocolEnum.icmp:
            self.body = icmp_packet.IcmpPacket(self._io)
        elif _on == self._root.ProtocolEnum.hopopt:
            self.body = self._root.OptionHopByHop(self._io, self, self._root)
        elif _on == self._root.ProtocolEnum.ipv6:
            self.body = ipv6_packet.Ipv6Packet(self._io)
        elif _on == self._root.ProtocolEnum.tcp:
            self.body = tcp_segment.TcpSegment(self._io)

    class NoNextHeader(KaitaiStruct):
        """Dummy type for IPv6 "no next header" type, which signifies end of headers chain."""
        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):
            pass


    class OptionHopByHop(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.next_header_type = self._io.read_u1()
            self.hdr_ext_len = self._io.read_u1()
            self.body = self._io.read_bytes((self.hdr_ext_len - 1))
            self.next_header = ProtocolBody(self.next_header_type, self._io)


    @property
    def protocol(self):
        if hasattr(self, '_m_protocol'):
            return self._m_protocol if hasattr(self, '_m_protocol') else None

        self._m_protocol = KaitaiStream.resolve_enum(self._root.ProtocolEnum, self.protocol_num)
        return self._m_protocol if hasattr(self, '_m_protocol') else None