packet_ppi: Ruby parsing library

PPI is a standard for link layer packet encapsulation, proposed as generic extensible container to store both captured in-band data and out-of-band data. Originally it was developed to provide 802.11n radio information, but can be used for other purposes as well.

Sample capture: https://wiki.wireshark.org/SampleCaptures?action=AttachFile&do=get&target=Http.cap

KS implementation details

License: CC0-1.0

This page hosts a formal specification of packet_ppi 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 Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.

The Ruby runtime library can be installed from RubyGems:

gem install kaitai-struct

Code

Parse a local file and get structure in memory:

data = PacketPpi.from_file("path/to/local/file.packet_ppi")

Or parse structure from a string of bytes:

bytes = "\x00\x01\x02..."
data = PacketPpi.new(Kaitai::Struct::Stream.new(bytes))

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

data.header # => get header

Ruby source code to parse packet_ppi

packet_ppi.rb

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

require 'kaitai/struct/struct'

unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
  raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end


##
# PPI is a standard for link layer packet encapsulation, proposed as
# generic extensible container to store both captured in-band data and
# out-of-band data. Originally it was developed to provide 802.11n
# radio information, but can be used for other purposes as well.
# 
# Sample capture: https://wiki.wireshark.org/SampleCaptures?action=AttachFile&do=get&target=Http.cap
# @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 3
class PacketPpi < Kaitai::Struct::Struct

  PFH_TYPE = {
    2 => :pfh_type_radio_802_11_common,
    3 => :pfh_type_radio_802_11n_mac_ext,
    4 => :pfh_type_radio_802_11n_mac_phy_ext,
    5 => :pfh_type_spectrum_map,
    6 => :pfh_type_process_info,
    7 => :pfh_type_capture_info,
  }
  I__PFH_TYPE = PFH_TYPE.invert

  LINKTYPE = {
    0 => :linktype_null_linktype,
    1 => :linktype_ethernet,
    3 => :linktype_ax25,
    6 => :linktype_ieee802_5,
    7 => :linktype_arcnet_bsd,
    8 => :linktype_slip,
    9 => :linktype_ppp,
    10 => :linktype_fddi,
    50 => :linktype_ppp_hdlc,
    51 => :linktype_ppp_ether,
    100 => :linktype_atm_rfc1483,
    101 => :linktype_raw,
    104 => :linktype_c_hdlc,
    105 => :linktype_ieee802_11,
    107 => :linktype_frelay,
    108 => :linktype_loop,
    113 => :linktype_linux_sll,
    114 => :linktype_ltalk,
    117 => :linktype_pflog,
    119 => :linktype_ieee802_11_prism,
    122 => :linktype_ip_over_fc,
    123 => :linktype_sunatm,
    127 => :linktype_ieee802_11_radiotap,
    129 => :linktype_arcnet_linux,
    138 => :linktype_apple_ip_over_ieee1394,
    139 => :linktype_mtp2_with_phdr,
    140 => :linktype_mtp2,
    141 => :linktype_mtp3,
    142 => :linktype_sccp,
    143 => :linktype_docsis,
    144 => :linktype_linux_irda,
    147 => :linktype_user0,
    148 => :linktype_user1,
    149 => :linktype_user2,
    150 => :linktype_user3,
    151 => :linktype_user4,
    152 => :linktype_user5,
    153 => :linktype_user6,
    154 => :linktype_user7,
    155 => :linktype_user8,
    156 => :linktype_user9,
    157 => :linktype_user10,
    158 => :linktype_user11,
    159 => :linktype_user12,
    160 => :linktype_user13,
    161 => :linktype_user14,
    162 => :linktype_user15,
    163 => :linktype_ieee802_11_avs,
    165 => :linktype_bacnet_ms_tp,
    166 => :linktype_ppp_pppd,
    169 => :linktype_gprs_llc,
    170 => :linktype_gpf_t,
    171 => :linktype_gpf_f,
    177 => :linktype_linux_lapd,
    187 => :linktype_bluetooth_hci_h4,
    189 => :linktype_usb_linux,
    192 => :linktype_ppi,
    195 => :linktype_ieee802_15_4,
    196 => :linktype_sita,
    197 => :linktype_erf,
    201 => :linktype_bluetooth_hci_h4_with_phdr,
    202 => :linktype_ax25_kiss,
    203 => :linktype_lapd,
    204 => :linktype_ppp_with_dir,
    205 => :linktype_c_hdlc_with_dir,
    206 => :linktype_frelay_with_dir,
    209 => :linktype_ipmb_linux,
    215 => :linktype_ieee802_15_4_nonask_phy,
    220 => :linktype_usb_linux_mmapped,
    224 => :linktype_fc_2,
    225 => :linktype_fc_2_with_frame_delims,
    226 => :linktype_ipnet,
    227 => :linktype_can_socketcan,
    228 => :linktype_ipv4,
    229 => :linktype_ipv6,
    230 => :linktype_ieee802_15_4_nofcs,
    231 => :linktype_dbus,
    235 => :linktype_dvb_ci,
    236 => :linktype_mux27010,
    237 => :linktype_stanag_5066_d_pdu,
    239 => :linktype_nflog,
    240 => :linktype_netanalyzer,
    241 => :linktype_netanalyzer_transparent,
    242 => :linktype_ipoib,
    243 => :linktype_mpeg_2_ts,
    244 => :linktype_ng40,
    245 => :linktype_nfc_llcp,
    247 => :linktype_infiniband,
    248 => :linktype_sctp,
    249 => :linktype_usbpcap,
    250 => :linktype_rtac_serial,
    251 => :linktype_bluetooth_le_ll,
    253 => :linktype_netlink,
    254 => :linktype_bluetooth_linux_monitor,
    255 => :linktype_bluetooth_bredr_bb,
    256 => :linktype_bluetooth_le_ll_with_phdr,
    257 => :linktype_profibus_dl,
    258 => :linktype_pktap,
    259 => :linktype_epon,
    260 => :linktype_ipmi_hpm_2,
    261 => :linktype_zwave_r1_r2,
    262 => :linktype_zwave_r3,
    263 => :linktype_wattstopper_dlm,
    264 => :linktype_iso_14443,
  }
  I__LINKTYPE = LINKTYPE.invert
  def initialize(_io, _parent = nil, _root = self)
    super(_io, _parent, _root)
    _read
  end

  def _read
    @header = PacketPpiHeader.new(@_io, self, @_root)
    @_raw_fields = @_io.read_bytes((header.pph_len - 8))
    _io__raw_fields = Kaitai::Struct::Stream.new(@_raw_fields)
    @fields = PacketPpiFields.new(_io__raw_fields, self, @_root)
    case header.pph_dlt
    when :linktype_ppi
      @_raw_body = @_io.read_bytes_full
      _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
      @body = PacketPpi.new(_io__raw_body)
    when :linktype_ethernet
      @_raw_body = @_io.read_bytes_full
      _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
      @body = EthernetFrame.new(_io__raw_body)
    else
      @body = @_io.read_bytes_full
    end
    self
  end
  class PacketPpiFields < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @entries = []
      i = 0
      while not @_io.eof?
        @entries << PacketPpiField.new(@_io, self, @_root)
        i += 1
      end
      self
    end
    attr_reader :entries
  end

  ##
  # @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 4.1.3
  class Radio80211nMacExtBody < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @flags = MacFlags.new(@_io, self, @_root)
      @a_mpdu_id = @_io.read_u4le
      @num_delimiters = @_io.read_u1
      @reserved = @_io.read_bytes(3)
      self
    end
    attr_reader :flags
    attr_reader :a_mpdu_id
    attr_reader :num_delimiters
    attr_reader :reserved
  end
  class MacFlags < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @unused1 = @_io.read_bits_int_be(1) != 0
      @aggregate_delimiter = @_io.read_bits_int_be(1) != 0
      @more_aggregates = @_io.read_bits_int_be(1) != 0
      @aggregate = @_io.read_bits_int_be(1) != 0
      @dup_rx = @_io.read_bits_int_be(1) != 0
      @rx_short_guard = @_io.read_bits_int_be(1) != 0
      @is_ht_40 = @_io.read_bits_int_be(1) != 0
      @greenfield = @_io.read_bits_int_be(1) != 0
      @_io.align_to_byte
      @unused2 = @_io.read_bytes(3)
      self
    end
    attr_reader :unused1

    ##
    # Aggregate delimiter CRC error after this frame
    attr_reader :aggregate_delimiter

    ##
    # More aggregates
    attr_reader :more_aggregates

    ##
    # Aggregate
    attr_reader :aggregate

    ##
    # Duplicate RX
    attr_reader :dup_rx

    ##
    # RX short guard interval (SGI)
    attr_reader :rx_short_guard

    ##
    # true = HT40, false = HT20
    attr_reader :is_ht_40

    ##
    # Greenfield
    attr_reader :greenfield
    attr_reader :unused2
  end

  ##
  # @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 3.1
  class PacketPpiHeader < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @pph_version = @_io.read_u1
      @pph_flags = @_io.read_u1
      @pph_len = @_io.read_u2le
      @pph_dlt = Kaitai::Struct::Stream::resolve_enum(PacketPpi::LINKTYPE, @_io.read_u4le)
      self
    end
    attr_reader :pph_version
    attr_reader :pph_flags
    attr_reader :pph_len
    attr_reader :pph_dlt
  end

  ##
  # @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 4.1.2
  class Radio80211CommonBody < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @tsf_timer = @_io.read_u8le
      @flags = @_io.read_u2le
      @rate = @_io.read_u2le
      @channel_freq = @_io.read_u2le
      @channel_flags = @_io.read_u2le
      @fhss_hopset = @_io.read_u1
      @fhss_pattern = @_io.read_u1
      @dbm_antsignal = @_io.read_s1
      @dbm_antnoise = @_io.read_s1
      self
    end
    attr_reader :tsf_timer
    attr_reader :flags
    attr_reader :rate
    attr_reader :channel_freq
    attr_reader :channel_flags
    attr_reader :fhss_hopset
    attr_reader :fhss_pattern
    attr_reader :dbm_antsignal
    attr_reader :dbm_antnoise
  end

  ##
  # @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 3.1
  class PacketPpiField < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @pfh_type = Kaitai::Struct::Stream::resolve_enum(PacketPpi::PFH_TYPE, @_io.read_u2le)
      @pfh_datalen = @_io.read_u2le
      case pfh_type
      when :pfh_type_radio_802_11_common
        @_raw_body = @_io.read_bytes(pfh_datalen)
        _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
        @body = Radio80211CommonBody.new(_io__raw_body, self, @_root)
      when :pfh_type_radio_802_11n_mac_ext
        @_raw_body = @_io.read_bytes(pfh_datalen)
        _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
        @body = Radio80211nMacExtBody.new(_io__raw_body, self, @_root)
      when :pfh_type_radio_802_11n_mac_phy_ext
        @_raw_body = @_io.read_bytes(pfh_datalen)
        _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
        @body = Radio80211nMacPhyExtBody.new(_io__raw_body, self, @_root)
      else
        @body = @_io.read_bytes(pfh_datalen)
      end
      self
    end
    attr_reader :pfh_type
    attr_reader :pfh_datalen
    attr_reader :body
    attr_reader :_raw_body
  end

  ##
  # @see https://web.archive.org/web/20090206112419/https://www.cacetech.com/documents/PPI_Header_format_1.0.1.pdf PPI header format spec, section 4.1.4
  class Radio80211nMacPhyExtBody < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @flags = MacFlags.new(@_io, self, @_root)
      @a_mpdu_id = @_io.read_u4le
      @num_delimiters = @_io.read_u1
      @mcs = @_io.read_u1
      @num_streams = @_io.read_u1
      @rssi_combined = @_io.read_u1
      @rssi_ant_ctl = Array.new(4)
      (4).times { |i|
        @rssi_ant_ctl[i] = @_io.read_u1
      }
      @rssi_ant_ext = Array.new(4)
      (4).times { |i|
        @rssi_ant_ext[i] = @_io.read_u1
      }
      @ext_channel_freq = @_io.read_u2le
      @ext_channel_flags = ChannelFlags.new(@_io, self, @_root)
      @rf_signal_noise = Array.new(4)
      (4).times { |i|
        @rf_signal_noise[i] = SignalNoise.new(@_io, self, @_root)
      }
      @evm = Array.new(4)
      (4).times { |i|
        @evm[i] = @_io.read_u4le
      }
      self
    end
    class ChannelFlags < Kaitai::Struct::Struct
      def initialize(_io, _parent = nil, _root = self)
        super(_io, _parent, _root)
        _read
      end

      def _read
        @spectrum_2ghz = @_io.read_bits_int_be(1) != 0
        @ofdm = @_io.read_bits_int_be(1) != 0
        @cck = @_io.read_bits_int_be(1) != 0
        @turbo = @_io.read_bits_int_be(1) != 0
        @unused = @_io.read_bits_int_be(8)
        @gfsk = @_io.read_bits_int_be(1) != 0
        @dyn_cck_ofdm = @_io.read_bits_int_be(1) != 0
        @only_passive_scan = @_io.read_bits_int_be(1) != 0
        @spectrum_5ghz = @_io.read_bits_int_be(1) != 0
        self
      end

      ##
      # 2 GHz spectrum
      attr_reader :spectrum_2ghz

      ##
      # OFDM (Orthogonal Frequency-Division Multiplexing)
      attr_reader :ofdm

      ##
      # CCK (Complementary Code Keying)
      attr_reader :cck
      attr_reader :turbo
      attr_reader :unused

      ##
      # Gaussian Frequency Shift Keying
      attr_reader :gfsk

      ##
      # Dynamic CCK-OFDM
      attr_reader :dyn_cck_ofdm

      ##
      # Only passive scan allowed
      attr_reader :only_passive_scan

      ##
      # 5 GHz spectrum
      attr_reader :spectrum_5ghz
    end

    ##
    # RF signal + noise pair at a single antenna
    class SignalNoise < Kaitai::Struct::Struct
      def initialize(_io, _parent = nil, _root = self)
        super(_io, _parent, _root)
        _read
      end

      def _read
        @signal = @_io.read_s1
        @noise = @_io.read_s1
        self
      end

      ##
      # RF signal, dBm
      attr_reader :signal

      ##
      # RF noise, dBm
      attr_reader :noise
    end
    attr_reader :flags
    attr_reader :a_mpdu_id
    attr_reader :num_delimiters

    ##
    # Modulation Coding Scheme (MCS)
    attr_reader :mcs

    ##
    # Number of spatial streams (0 = unknown)
    attr_reader :num_streams

    ##
    # RSSI (Received Signal Strength Indication), combined from all active antennas / channels
    attr_reader :rssi_combined

    ##
    # RSSI (Received Signal Strength Indication) for antennas 0-3, control channel
    attr_reader :rssi_ant_ctl

    ##
    # RSSI (Received Signal Strength Indication) for antennas 0-3, extension channel
    attr_reader :rssi_ant_ext

    ##
    # Extension channel frequency (MHz)
    attr_reader :ext_channel_freq

    ##
    # Extension channel flags
    attr_reader :ext_channel_flags

    ##
    # Signal + noise values for antennas 0-3
    attr_reader :rf_signal_noise

    ##
    # EVM (Error Vector Magnitude) for chains 0-3
    attr_reader :evm
  end
  attr_reader :header
  attr_reader :fields
  attr_reader :body
  attr_reader :_raw_fields
  attr_reader :_raw_body
end