protocol_body: Lua 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.

Lua source code to parse protocol_body

protocol_body.lua

-- This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
--
-- This file is compatible with Lua 5.3

local class = require("class")
require("kaitaistruct")
local enum = require("enum")

require("icmp_packet")
require("udp_datagram")
require("ipv4_packet")
require("ipv6_packet")
require("tcp_segment")
-- 
-- 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.
-- See also: Source (https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml)
ProtocolBody = class.class(KaitaiStruct)

ProtocolBody.ProtocolEnum = enum.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,
}

function ProtocolBody:_init(protocol_num, io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self.protocol_num = protocol_num
  self:_read()
end

function ProtocolBody:_read()
  local _on = self.protocol
  if _on == ProtocolBody.ProtocolEnum.ipv6_nonxt then
    self.body = ProtocolBody.NoNextHeader(self._io, self, self._root)
  elseif _on == ProtocolBody.ProtocolEnum.ipv4 then
    self.body = Ipv4Packet(self._io)
  elseif _on == ProtocolBody.ProtocolEnum.udp then
    self.body = UdpDatagram(self._io)
  elseif _on == ProtocolBody.ProtocolEnum.icmp then
    self.body = IcmpPacket(self._io)
  elseif _on == ProtocolBody.ProtocolEnum.hopopt then
    self.body = ProtocolBody.OptionHopByHop(self._io, self, self._root)
  elseif _on == ProtocolBody.ProtocolEnum.ipv6 then
    self.body = Ipv6Packet(self._io)
  elseif _on == ProtocolBody.ProtocolEnum.tcp then
    self.body = TcpSegment(self._io)
  end
end

ProtocolBody.property.protocol = {}
function ProtocolBody.property.protocol:get()
  if self._m_protocol ~= nil then
    return self._m_protocol
  end

  self._m_protocol = ProtocolBody.ProtocolEnum(self.protocol_num)
  return self._m_protocol
end

-- 
-- Protocol number as an integer.

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

function ProtocolBody.NoNextHeader:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function ProtocolBody.NoNextHeader:_read()
end


ProtocolBody.OptionHopByHop = class.class(KaitaiStruct)

function ProtocolBody.OptionHopByHop:_init(io, parent, root)
  KaitaiStruct._init(self, io)
  self._parent = parent
  self._root = root or self
  self:_read()
end

function ProtocolBody.OptionHopByHop:_read()
  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)
end