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module NetAddr
#Mask32 represents a 32-bit netmask.
class Mask32
# mask is the Integer representation of this netmask
attr_reader :mask
# prefix_len is the Integer prefix length of this netmask
attr_reader :prefix_len
# Create a Mask32 from an Integer prefix length. Valid values are 0-32.
# Throws ValidationError on error.
def initialize(prefix_len)
if (!prefix_len.kind_of?(Integer))
raise ValidationError, "Expected an Integer for 'prefix_len' but got a #{prefix_len.class}."
elsif ( (prefix_len < 0) || (prefix_len > 32) )
raise ValidationError, "#{prefix_len} must be in the range of 0-32."
end
@prefix_len = prefix_len
@mask = NetAddr::F32 ^ (NetAddr::F32 >> @prefix_len)
end
# parse will create an Mask32 from its string representation.
# arguments:
# * mask - String representing a netmask (ie. "/24" or "255.255.255.0").
#
# Throws ValidationError on error.
def Mask32.parse(mask)
mask = mask.strip
if (mask.start_with?("/")) # cidr format
mask = mask[1..-1] # remove "/"
end
if (!mask.include?("."))
begin
return Mask32.new(Integer(mask))
rescue ArgumentError
raise ValidationError, "#{mask} is not valid integer."
end
end
# for extended netmask
# determine length of netmask by cycling through bit by bit and looking
# for the first '1' bit, tracking the length as we go. we also want to verify
# that the mask is valid (ie. not something like 255.254.255.0). we do this
# by creating a hostmask which covers the '0' bits of the mask. once we have
# separated the net vs host mask we xor them together. the result should be that
# all bits are now '1'. if not then we know we have an invalid netmask.
maskI = Util.parse_IPv4(mask)
prefix = 32
hostmask = 1
i = maskI
32.downto(1) do
if (i&1 == 1)
hostmask = hostmask >> 1
if (maskI ^hostmask != NetAddr::F32)
raise ValidationError, "#{mask} is invalid. It contains '1' bits in its host portion."
end
break
end
hostmask = (hostmask << 1) | 1
i = i>>1
prefix -= 1
end
return Mask32.new(prefix)
end
# extended returns the Mask32 in extended format (eg. x.x.x.x)
def extended()
Util.int_to_IPv4(@mask)
end
#cmp compares equality with another Mask32. Return:
#* 1 if this Mask128 is larger in capacity
#* 0 if the two are equal
#* -1 if this Mask128 is smaller in capacity
def cmp(other)
if (!other.kind_of?(Mask32))
raise ArgumentError, "Expected an Mask32 object for 'other' but got a #{other.class}."
end
if (self.prefix_len < other.prefix_len)
return 1
elsif (self.prefix_len > other.prefix_len)
return -1
end
return 0
end
#len returns the number of IP addresses in this network. It will always return 0 for /0 networks.
def len()
if (self.prefix_len == 0)
return 0
end
return (self.mask ^ NetAddr::F32) + 1 # bit flip the netmask and add 1
end
# to_s returns the Mask32 as a String
def to_s()
return "/#{@prefix_len}"
end
end # end class Mask32
end # end module
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