Class: BitterDomain::BitShifter

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

Constant Summary collapse

PATTERN =

accept alphanumeric chars and hyphens but no hyphens at the beginning or end of the domain

/^[A-Za-z0-9]-?[A-Za-z0-9]+$/

Instance Method Summary collapse

Constructor Details

#initialize(domain) ⇒ BitShifter

Returns a new instance of BitShifter.



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# File 'lib/bitter_domain/bit_shifter.rb', line 7

def initialize(domain)
  @domain = domain
  @shifts = []
end

Instance Method Details

#gen_shifts(byte) ⇒ Object 



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# File 'lib/bitter_domain/bit_shifter.rb', line 16

def gen_shifts(byte)
  # left-shift 1 through each bit of the byte
  # and XOR to flip a single one at each position
  8.times do |i|
    shifted = byte ^ (1 << i)
    @shifts.push(shifted)
  end

  @shifts
end

#get_shifted_domains ⇒ Object 



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# File 'lib/bitter_domain/bit_shifter.rb', line 27

def get_shifted_domains
  bytes = @domain.bytes
  domains = []

  # iterate over a byte array for the original domain
  # get a set of flips for each byte, swap each new byte
  # and then stringify
  bytes.each.with_index do |byte, idx|
    shifts = gen_shifts(byte)
    swapped_domains = shifts.map do |byte| 
      copied_bytes = bytes.dup
      copied_bytes[idx] = byte
      copied_bytes
        .map(&:chr)
        .join("")
        .downcase
    end
    domains.concat(swapped_domains)
  end

  # kick out anything that doesn't match the pattern above
  domains.keep_if { |domain| valid_domain?(domain) }.uniq
end

#valid_domain?(domain) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bitter_domain/bit_shifter.rb', line 12

def valid_domain?(domain)
  domain.match?(PATTERN) && domain != @domain
end