Class: Dnsruby::RR::NSEC

### Home Classes Methods

### In Files

- lib/Dnsruby/resource/NSEC.rb

### Parent

Dnsruby::RR

### Methods

- ::decode_types
- ::encode_types
- ::get_types
- #add_type
- #check_name_in_range
- #check_name_in_wildcard_range
- #encode_types
- #from_string
- #next_domain=
- #types=

### Files

- DNSSEC
- EVENTMACHINE
- EXAMPLES
- README

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No matching classes.

# Dnsruby::RR::NSEC

RFC4034, section 4 The NSEC resource record lists two separate things: the next owner name (in the canonical ordering of the zone) that contains authoritative data or a delegation point NS RRset, and the set of RR types present at the NSEC RR's owner name [RFC3845]. The complete set of NSEC RRs in a zone indicates which authoritative RRsets exist in a zone and also form a chain of authoritative owner names in the zone. This information is used to provide authenticated denial of existence for DNS data, as described in [RFC4035].

### Attributes

next_domain[R]

The next name which exists after this NSEC The Next Domain field contains the next owner name (in the canonical ordering of the zone) that has authoritative data or contains a delegation point NS RRset

types[R]

The Type Bit Maps field identifies the RRset types that exist at the NSEC RR's owner name

### Public Class Methods

decode_types(bytes) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 105
    def self.decode_types(bytes)
      types = []
      #RFC4034 section 4.1.2

      #The RR type space is split into 256 window blocks, each representing

      #the low-order 8 bits of the 16-bit RR type space.  Each block that

      #has at least one active RR type is encoded using a single octet

      #window number (from 0 to 255), a single octet bitmap length (from 1

      #to 32) indicating the number of octets used for the window block's

      #bitmap, and up to 32 octets (256 bits) of bitmap.

      #Blocks are present in the NSEC RR RDATA in increasing numerical

      #order.

      #  Type Bit Maps Field = ( Window Block # | Bitmap Length | Bitmap )+

      #  where "|" denotes concatenation.

      pos = 0
      while (pos < bytes.length)
        #So, read the first two octets

        if (bytes.length-pos < 2)
          raise DecodeError.new("NSEC : Expected window number and bitmap length octets")
        end
        window_number = bytes[pos]
        bitmap_length = bytes[pos+1]
        if (window_number.class == String) # Ruby 1.9

          window_number = window_number.getbyte(0)
          bitmap_length = bitmap_length.getbyte(0)
        end
        pos += 2
        bitmap = bytes[pos,bitmap_length]
        pos += bitmap_length
        #Each bitmap encodes the low-order 8 bits of RR types within the

        #window block, in network bit order.  The first bit is bit 0.  For

        #window block 0, bit 1 corresponds to RR type 1 (A), bit 2 corresponds

        #to RR type 2 (NS), and so forth.  For window block 1, bit 1

        #corresponds to RR type 257, and bit 2 to RR type 258.  If a bit is

        #set, it indicates that an RRset of that type is present for the NSEC

        #RR's owner name.  If a bit is clear, it indicates that no RRset of

        #that type is present for the NSEC RR's owner name.

        index = 0
        bitmap.each_byte do |char|
          if char.to_i != 0
            # decode these RR types

            0..8.times do |i|
              if (((1 << (7-i)) & char) == (1 << (7-i)))
                type = Types.new((256 * window_number) + (8 * index) + i)
                #Bits representing pseudo-types MUST be clear, as they do not appear

                #in zone data.  If encountered, they MUST be ignored upon being read.

                if (!([Types::OPT, Types::TSIG].include?(type)))
                  types.push(type)
                end
              end
            end
          end
          index += 1
        end
      end
      return types
    end

encode_types(nsec) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 170
    def self.encode_types(nsec)
      output=""
      #types represents all 65536 possible RR types.

      #Split up types into sets of 256 different types.

      type_codes = []
      nsec.types.each do |type|
        type_codes.push(type.code)
      end
      type_codes.sort!
      window = -1
      0.step(65536,256) { |step|
        # Gather up the RR types for this set of 256

        types_to_go = []
        while (!type_codes.empty? && type_codes[0] < step)
          types_to_go.push(type_codes[0])
          # And delete them from type_codes

          type_codes=type_codes.last(type_codes.length-1)
          break if (type_codes.empty?)
        end

        if (!types_to_go.empty?)
          # Then create the bitmap for them

          bitmap=""
          # keep on adding them until there's none left

          pos = 0
          bitmap_pos = 0
          while (!types_to_go.empty?)

            # Check the next eight

            byte = 0
            pos += 8
            while (types_to_go[0] < pos + step-256)
              byte = byte | (1 << (pos-1-(types_to_go[0] - (step-256) )))
              # Add it to the list

              # And remove it from the to_go queue

              types_to_go =types_to_go.last(types_to_go.length-1)
              break if (types_to_go.empty?)
            end
            bitmap += " "
            if (bitmap[bitmap_pos].class == String)
              bitmap.setbyte(bitmap_pos, byte) # Ruby 1.9

            else
              bitmap[bitmap_pos]=byte
            end
            bitmap_pos+=1
          end

          # Now add data to output bytes

          start = output.length
          (2+bitmap.length).times do
            output += " "
          end

          if (output[start].class == String)
            output.setbyte(start, window)
            output.setbyte(start+1, bitmap.length)
            bitmap.length.times do |i|
              output.setbyte(start+2+i, bitmap[i].getbyte(0))
            end
          else
            output[start] = window
            output[start+1] = bitmap.length
            bitmap.length.times do |i|
              output[start+2+i] = bitmap[i]
            end
          end
        end
        window += 1

        # Are there any more types after this?

        if (type_codes.empty?)
          # If not, then break (so we don't add more zeros)

          break
        end
      }
      if (output[0].class == String)
        output = output.force_encoding("ascii-8bit")
      end
      return output
    end

get_types(t) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 76
    def self.get_types(t)
      types = nil
      if (t.instance_of?Array)
        # from the wire, already decoded

        types =t
      elsif (t.instance_of?String)
        if (index = t.index";")
          t = t[0, index]
        end
        if (index = t.index")")
          t = t[0, index]
        end
        # List of mnemonics

        types=[]
        mnemonics = t.split(" ")
        mnemonics.each do |m|
          type = Types.new(m)
          types.push(type)
        end
      else
        raise DecodeError.new("Unknown format of types for Dnsruby::RR::NSEC")
      end
      return types
    end

### Public Instance Methods

add_type(t) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 101
    def add_type(t)
      self.types=(@types + [t])
    end

check_name_in_range(n) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 45
    def check_name_in_range(n)
      # Check if the name is covered by this record

      if (@name.wild?)
        return check_name_in_wildcard_range(n)
      end
      if (name.canonically_before(n) && (n.canonically_before(next_domain)))
        return true
      end
      return false
    end

check_name_in_wildcard_range(n) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 56
    def check_name_in_wildcard_range(n)
      #  Check if the name is covered by this record

      return false if !@name.wild?
      return false if @next_domain.canonically_before(n)
      # Now just check that the wildcard is *before* the name

      # Strip the first label ("*") and then compare

      n2 = Name.create(@name)
      n2.labels.delete_at(0)
      return false if n.canonically_before(n2)
      return true
    end

encode_types() click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 166
    def encode_types
      NSEC.encode_types(self)
    end

from_string(input) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 257
    def from_string(input)
      if (input.length > 0)
        data = input.split(" ")
        self.next_domain=(data[0])
        len = data[0].length+ 1
        if (data[1] == "(")
          len = len + data[1].length
        end
        self.types=(input[len, input.length-len])
        @types = NSEC.get_types(input[len, input.length-len])
      end
    end

next_domain=(n) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 40
    def next_domain=(n)
      nxt = Name.create(n)
      @next_domain = nxt
    end

types=(t) click to toggle source

    # File lib/Dnsruby/resource/NSEC.rb, line 68
    def types=(t)
      if (t && t.length > 0)
      @types = NSEC.get_types(t)
      else
        @types = []
      end
    end

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