Class: Unpacker

Inherits:
Object
  • Object
show all
Defined in:
lib/packer.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data) ⇒ Unpacker

Returns a new instance of Unpacker.



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# File 'lib/packer.rb', line 77

def initialize(data)
  @data = data
  @prev = [] # all the data already unpacked
  @parsed = []
  # TODO: delete parsed or document it with examples
  # @parsed.push({ type: 'string', value: str, raw:, len:, pos: })
  @red_bytes = 0
  # { type: 'int', value: 1, raw: "\x01", len: 1, pos: 0 }
  if data.instance_of?(String)
    @data = data.unpack('C*')
  elsif data.instance_of?(Array)
    @data = data
  else
    raise 'Error: Unpacker expects array of integers or byte string'
  end
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/packer.rb', line 75

def data
  @data
end

#parsed ⇒ Object (readonly)

Returns the value of attribute parsed.



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# File 'lib/packer.rb', line 75

def parsed
  @parsed
end

#prev ⇒ Object (readonly)

Returns the value of attribute prev.



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# File 'lib/packer.rb', line 75

def prev
  @prev
end

Instance Method Details

#get_int ⇒ Object 



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# File 'lib/packer.rb', line 136

def get_int
  return nil if @data.nil?
  return nil if @data.empty?

  # TODO: make this more performant
  #       it should not read in ALL bytes
  #       of the WHOLE packed data
  #       it should be max 4 bytes
  #       because bigger ints are not sent anyways
  bytes = @data.map { |byte| byte.to_s(2).rjust(8, '0') }
  first = bytes[0]

  sign = first[1]
  bits = []
  parsed = { type: 'int' }

  # extended
  if first[0] == '1'
    bits << first[2..]
    bytes = bytes[1..]
    consumed = 1
    bytes.each do |eigth_bits|
      bits << eigth_bits[1..]
      consumed += 1

      break if eigth_bits[0] == '0'
    end
    bits = bits.reverse
    @prev += @data[0...consumed]
    parsed[:raw] = @data[0...consumed]
    parsed[:len] = consumed
    parsed[:pos] = @red_bytes
    @red_bytes += consumed
    @data = @data[consumed..]
  else # single byte
    bits = [first[2..]]
    @prev.push(@data[0])
    parsed[:raw] = [@data[0]]
    parsed[:len] = 1
    parsed[:pos] = @red_bytes
    @red_bytes += 1
    @data = @data[1..]
  end
  num = bits.join.to_i(2)
  parsed[:value] = sign == '1' ? -(num + 1) : num
  @parsed.push(parsed)
  parsed[:value]
end

#get_raw(size = -1)) ⇒ Object 



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# File 'lib/packer.rb', line 185

def get_raw(size = -1)
  len = size == -1 ? @data.size : size
  @prev += @data[...len]
  pos = @red_bytes
  @red_bytes += len
  @parsed.push({ type: 'raw', value: @data[...len], raw: @data[...len], len:, pos: })
  # TODO: error if size exceeds @data.size
  @data.shift(len)
end

#get_string(sanitize = SANITIZE) ⇒ Object 



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# File 'lib/packer.rb', line 110

def get_string(sanitize = SANITIZE)
  return nil if @data.nil?

  str = ''
  raw = []
  len = 0
  pos = @red_bytes
  @data.each_with_index do |byte, index|
    @prev.push(byte)
    raw.push(raw)
    @red_bytes += 1
    len += 1
    if byte.zero?
      @data = index == @data.length - 1 ? nil : @data[(index + 1)..]
      str = str_sanitize(str) unless (sanitize & SANITIZE).zero?
      str = str_sanitize_cc(str) unless (sanitize & SANITIZE_CC).zero?
      @parsed.push({ type: 'string', value: str, raw:, len:, pos: })
      return str
    end
    str += byte.chr
  end
  # raise "get_string() failed to find null terminator"
  # return empty string in case of error
  ''
end

#str_sanitize(str) ⇒ Object 



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# File 'lib/packer.rb', line 94

def str_sanitize(str)
  letters = str.chars
  letters.map! do |c|
    c.ord < 32 && c != "\r" && c != "\n" && c != "\t" ? ' ' : c
  end
  letters.join
end

#str_sanitize_cc(str) ⇒ Object 



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# File 'lib/packer.rb', line 102

def str_sanitize_cc(str)
  letters = str.chars
  letters.map! do |c|
    c.ord < 32 ? ' ' : c
  end
  letters.join
end