hackedteam/rcs-common

# here we are re-opening the ruby String class,
# the namespace must not be specified

class String
  
  # returns a string encoded into a pascalized form
  def pascalize
    # the pascalized version is composed as follow:
    # - 4 bytes len in front
    # - UTF-16LE encoded string
    # - UTF-16LE null terminator
    pascalized = [self.encode('UTF-16LE').bytesize + 2].pack('I')
    pascalized += self.encode('UTF-16LE').unpack('H*').pack('H*') 
    pascalized += "\x00\x00"

    # BINARY is an alias for ASCII-8BIT
    return pascalized.encode!('ASCII-8BIT')
  end
  
  # returns a string decoded from its pascalized form
  def unpascalize
    begin
      # get the len (unsigned int 4 bytes)
      len = self.unpack('I')
      # sanity check to avoid
      return nil unless len.first <= self.length - 4
      # get the string
      unpascalized = self.slice(4, len.first).force_encoding('UTF-16LE')
      # convert to UTF-8
      unpascalized.encode!('UTF-8')
      # remove the trailing zero
      unpascalized.chop!
      
      return unpascalized
    rescue
      return nil
    end
  end

  # returns an array containing all the concatenated pascalized strings
  def unpascalize_ary
    many = []
    buffer = self
    len = 0
    
    begin
      # len of the current token
      len += buffer.unpack('I').first + 4
      # unpascalize the token
      str = buffer.unpascalize
      # add to the result array
      many << str unless str.nil?
      # move the pointer after the token
      buffer = self.slice(len, self.length)
      # sanity check
      break if buffer.nil?
    end while buffer.length != 0
    
    return many
  end
end