lib/ipaddress/prefix.rb in ipaddress-0.6.0 vs lib/ipaddress/prefix.rb in ipaddress-0.7.0

@@ -81,34 +81,49 @@
    end # class Prefix
 
 
   class Prefix32 < Prefix
 
+    IN4MASK = 0xffffffff
+    
     #
     # Creates a new prefix object for 32 bits IPv4 addresses
     #
     #   prefix = IPAddress::Prefix32.new 24
     #     #=> 24
     #
     def initialize(num)
       unless (1..32).include? num
-        raise ArgumentError, "Prefix must be in range 1..128, got: #{num}"
+        raise ArgumentError, "Prefix must be in range 1..32, got: #{num}"
       end
       super(num)
     end
 
     #
+    # Returns the length of the host portion
+    # of a netmask. 
+    #
+    #   prefix = Prefix32.new 24
+    #
+    #   prefix.host_prefix
+    #     #=> 8
+    #
+    def host_prefix
+      32 - @prefix
+    end
+    
+    #
     # Transforms the prefix into a string of bits
     # representing the netmask
     #
     #   prefix = IPAddress::Prefix32.new 24
     # 
     #   prefix.bits 
     #     #=> "11111111111111111111111100000000"
     #
     def bits
-      "1" * @prefix + "0" * (32 - @prefix)
+      to_u32.to_s(2)
     end
 
     #
     # Gives the prefix in IPv4 dotted decimal format, 
     # i.e. the canonical netmask we're all used to
@@ -143,11 +158,11 @@
     #
     #   prefix.to_u32
     #     #=> 4294967040
     #
     def to_u32
-      [bits].pack("B*").unpack("N").first
+      (IN4MASK >> host_prefix) << host_prefix
     end
     
     #
     # Shortcut for the octecs in the dotted decimal 
     # representation
@@ -183,11 +198,11 @@
     #     #=> 24
     #
     def self.parse_netmask(netmask)
       octets = netmask.split(".").map{|i| i.to_i}
       num = octets.pack("C"*octets.size).unpack("B*").first.count "1"
-      return IPAddress::Prefix.new(num)
+      return self.new(num)
     end
     
   end # class Prefix32 < Prefix
 
   class Prefix128 < Prefix
@@ -227,10 +242,10 @@
     #
     #   prefix.to_u128
     #     #=> 340282366920938463444927863358058659840
     #
     def to_u128
-      eval "0b#{bits}.to_i"
+      bits.to_i(2)
     end
 
   end # class Prefix123 < Prefix
 
 end # module IPAddress