Class: PWN::SDR::Decoder::Bluetooth::ExtendedHeader

Inherits:
Object
  • Object
show all
Defined in:
lib/pwn/sdr/decoder/bluetooth.rb

Overview

Length-bounded extended advertising header parser.

Class Method Summary collapse

Class Method Details

.parse(opts = {}) ⇒ Object

Core Vol 6 Part B 2.3.4: flagged fields in fixed order, bounded by ExtHdrLen. Preserve ACAD/SyncInfo as bytes rather than invent fields.



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# File 'lib/pwn/sdr/decoder/bluetooth.rb', line 281

public_class_method def self.parse(opts = {})
  payload = opts[:payload]
  size = payload[0] & 63
  mode = payload[0] >> 6
  return nil if mode == 3 || size + 1 > payload.length

  out = { adv_mode: mode }
  if size.positive?
    flags = payload[1]
    return nil if flags.anybits?(0x80)

    cursor = 2
    { adv_addr: 6, target_addr: 6, cte_info: 1, adi: 2, aux_ptr: 3, sync_info: 18, tx_power: 1 }.each_with_index do |(name, width), bit|
      next if flags[bit].zero?
      return nil if cursor + width > size + 1

      data = payload[cursor, width]
      cursor += width
      case name
      when :adv_addr, :target_addr
        out[name] = data.reverse.map { |b| format('%02X', b) }.join(':')
      when :adi
        out[:advertising_did] = data[0] | ((data[1] & 15) << 8)
        out[:advertising_sid] = data[1] >> 4
      when :tx_power
        out[name] = data[0] >= 128 ? data[0] - 256 : data[0]
      else
        out[:"#{name}_hex"] = data.pack('C*').unpack1('H*').upcase
      end
    end
    out[:acad_hex] = payload[cursor, size + 1 - cursor].pack('C*').unpack1('H*').upcase
  end
  out[:advertising_data_hex] = payload.drop(size + 1).pack('C*').unpack1('H*').upcase
  out
end