Method: Rex::Text.pattern_create

Defined in:
lib/rex/text.rb

.pattern_create(length, sets = nil) ⇒ String

Creates a pattern that can be used for offset calculation purposes. This routine is capable of generating patterns using a supplied set and a supplied number of identifiable characters (slots). The supplied sets should not contain any duplicate characters or the logic will fail.

Parameters:

  • length (Fixnum)
  • sets (Array<(String,String,String)>) (defaults to: nil) —

    The character sets to choose from. Should have 3 elements, each of which must be a string containing no characters contained in the other sets.

Returns:

  • (String) —

    A pattern of length bytes, in which any 4-byte chunk is unique

See Also:



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# File 'lib/rex/text.rb', line 1324

def self.pattern_create(length, sets = nil)
  buf = ''
  offsets = []

  # Make sure there's something in sets even if we were given an explicit nil
  sets ||= [ UpperAlpha, LowerAlpha, Numerals ]

  # Return stupid uses
  return "" if length.to_i < 1
  return sets[0][0].chr * length if sets.size == 1 and sets[0].size == 1

  sets.length.times { offsets << 0 }

  until buf.length >= length
    begin
      buf << converge_sets(sets, 0, offsets, length)
    end
  end

  # Maximum permutations reached, but we need more data
  if (buf.length < length)
    buf = buf * (length / buf.length.to_f).ceil
  end

  buf[0,length]
end