Module: PWN::SDR::Decoder::GSM

Defined in:
lib/pwn/sdr/decoder/gsm.rb

Overview

SDR Decoder for GSM signals.

Constant Summary collapse

POWER_THRESHOLD = 
0.1
SLEEP_INTERVAL = 
0.1
HEADER_SIZE = 
44
BURST_DURATION_SEC = 
0.000577
TSC_0 =

TSC 0 binary sequence (26 bits): 00100101110000101010011011

[0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1].freeze

Class Method Summary collapse

Class Method Details

.authors ⇒ Object

Author(s)

0day Inc. <[email protected]>



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# File 'lib/pwn/sdr/decoder/gsm.rb', line 195

public_class_method def self.authors
  "AUTHOR(S):
    0day Inc. <[email protected]>
  "
end

.help ⇒ Object

Display Usage for this Module



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# File 'lib/pwn/sdr/decoder/gsm.rb', line 203

public_class_method def self.help
  puts "USAGE:
    gsm_decoder_thread = PWN::SDR::Decoder::GSM.start(
      freq_obj: 'required - freq_obj returned from PWN::SDR::Receiver::GQRX.init_freq method'
    )

    # To stop the decoder thread:
    PWN::SDR::Decoder::GSM.stop(
      freq_obj: 'required - freq_obj returned from PWN::SDR::Receiver::GQRX.init_freq method'
    )

    #{self}.authors
  "
end

.start(opts = {}) ⇒ Object

Starts the live decoding thread.



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# File 'lib/pwn/sdr/decoder/gsm.rb', line 17

def self.start(opts = {})
  freq_obj = opts[:freq_obj]
  raise ':ERROR: :freq_obj is required' unless freq_obj.is_a?(Hash)

  gqrx_sock = freq_obj[:gqrx_sock]
  freq = freq_obj[:freq]
  bandwidth = freq_obj[:bandwidth].to_i
  record_path = freq_obj[:record_path]

  sleep 0.1 until File.exist?(record_path)

  header = File.binread(record_path, HEADER_SIZE)
  raise 'Invalid WAV header' unless header.start_with?('RIFF') && header.include?('WAVE')

  bytes_read = HEADER_SIZE

  puts "GSM Decoder started for freq: #{freq}, bandwidth: #{bandwidth}"

  Thread.new do
    loop do
      current_size = File.size(record_path)
      if current_size > bytes_read
        new_bytes = current_size - bytes_read
        # Ensure full I/Q pairs (8 bytes)
        new_bytes -= new_bytes % 8
        data = File.binread(record_path, new_bytes, bytes_read)
        process_chunk(
          data: data,
          bandwidth: bandwidth,
          freq: freq
        )
        bytes_read = current_size
      end

      sleep SLEEP_INTERVAL
    end
  rescue StandardError => e
    puts "Decoder error: #{e.message}"
  ensure
    cleanup(record_path: record_path)
  end
end

.stop(opts = {}) ⇒ Object

Stops the decoding thread.



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# File 'lib/pwn/sdr/decoder/gsm.rb', line 61

def self.stop(opts = {})
  freq_obj = opts[:freq_obj]
  raise 'ERROR: :freq_obj is required' unless freq_obj.is_a?(Hash)

  decoder_thread = freq_obj[:decoder_thread]
  decoder_thread.kill if decoder_thread.is_a?(Thread)
end