Module: Girl::Dns

Included in:
ProxyWorker, ProxydWorker
Defined in:
lib/girl/dns.rb

Instance Method Summary collapse

Instance Method Details

#pack_a_query(domain, type = 1) ⇒ Object 



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# File 'lib/girl/dns.rb', line 4

def pack_a_query( domain, type = 1 )
  # https://www.ietf.org/rfc/rfc1035.txt
  # https://www.ietf.org/rfc/rfc3596.txt
  raise "domain may not exceed 255 chars" if domain.bytesize > 255
  raise "invalid domain" if domain =~ /[^\w\.\-]/
  data = [ rand( 65_535 ), 1, 0, 1, 0, 0, 0 ].pack( 'nCCnnnn' )
  data << [ pack_domain( domain ), type, 1 ].pack( 'a*nn' )
  data
end

#pack_domain(domain) ⇒ Object 



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# File 'lib/girl/dns.rb', line 14

def pack_domain( domain )
  data = ''
  
  domain.split( '.' ).each do | label |
    raise "label may not exceed 63 chars" if label.bytesize > 63
    data << [ label.bytesize, label ].pack( 'Ca*' )
  end
  
  data << [ 0 ].pack( 'C' )
  data
end

#seek_dn(data, offset) ⇒ Object 



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# File 'lib/girl/dns.rb', line 26

def seek_dn( data, offset )
  name = ""
  datalen = data.bytesize
  
  loop do
    raise "offset is greater than datalen" if datalen < ( offset + 1 )
  
    len = data.unpack( "@#{ offset } C" ).first
  
    if len == 0
      offset += 1
      break
    elsif ( len & 0xC0 ) == 0xC0
      raise "data ended before offset expand" if datalen < ( offset + 2 )
  
      ptr = data.unpack( "@#{ offset } n" ).first
      ptr &= 0x3FFF
      name2 = seek_dn( data, ptr ).first
      raise "data is malformed" if name2.nil?
  
      name += name2
      offset += 2
      break
    else
      offset += 1
      raise "no expansion found" if datalen < ( offset + len )
  
      elem = data[ offset..offset + len - 1 ]
      name += "#{ elem }."
      offset += len
    end
  end
  
  [ name, offset ]
end

#seek_ip(data) ⇒ Object 



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# File 'lib/girl/dns.rb', line 62

def seek_ip( data )
  ip = nil
  answer_count = data.unpack( "@6 n" ).first
  # puts "debug answer count #{ answer_count }"
  offset = seek_question( data )
  # puts "debug offset #{ offset }"
  
  answer_count.times do
    ip, offset = seek_rr_ip( data, offset )
  
    if ip then
      break
    end
  end
  
  ip
end

#seek_question(data) ⇒ Object 



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# File 'lib/girl/dns.rb', line 80

def seek_question( data )
  offset = 12
  
  loop do
    len = data.unpack( "@#{ offset } C" ).first
    # puts "debug len #{ len } #{ data[ offset + 1, len ] }"
    break if len == 0
    offset += ( 1 + len )
  end
  
  offset += 5
  offset
end

#seek_question_dn(data) ⇒ Object 



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# File 'lib/girl/dns.rb', line 94

def seek_question_dn( data )
  id = data[ 0, 2 ]
  parts = []
  offset = 12
  
  loop do
    len = data.unpack( "@#{ offset } C" ).first
    # puts "debug len #{ len } #{ data[ offset + 1, len ] }"
    break if len == 0
    parts << data[ offset + 1, len ]
    offset += ( 1 + len )
  end
  
  type = data.unpack( "@#{ offset + 1 } n" ).first
  # puts "debug id #{ id.inspect } dn #{ parts.join( '.' ).inspect } type #{ type }"
  [ id, parts.join( '.' ), type ]
end

#seek_rr_ip(data, offset) ⇒ Object 



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# File 'lib/girl/dns.rb', line 112

def seek_rr_ip( data, offset )
  ip = nil
  name, offset = seek_dn( data, offset )
  # puts "debug seek_dn #{ name }, #{ offset }"
  type = data.unpack( "@#{ offset } n" ).first
  # puts "debug type #{ type }"
  offset += 8
  rdlen = data.unpack( "@#{ offset } n" ).first
  # puts "debug rdlen #{ rdlen }"
  offset += 2
  
  if type == 1 then
    raise "rdlen not 4?" if rdlen != 4
    a, b, c, d = data.unpack( "@#{ offset } CCCC" )
    ip = "#{ a }.#{ b }.#{ c }.#{ d }"
  elsif type == 28 then
    tokens = data.unpack("@#{ offset } n8")
    ip = format( "%x:%x:%x:%x:%x:%x:%x:%x", *tokens )
  end
  
  offset += rdlen
  [ ip, offset ]
end