require 'rex/socket'

module Rex
module Socket

###
#
# This class provides an interface to enumerating an IP range
#
# This class uses start,stop pairs to represent ranges of addresses.  This
# is very efficient for large numbers of consecutive addresses, and not
# show-stoppingly inefficient when storing a bunch of non-consecutive
# addresses, which should be a somewhat unusual case.
#
###
class RangeWalker

	#
	# Initializes a walker instance using the supplied range
	#
	def initialize(parseme)
		if parseme.is_a? RangeWalker
			@ranges = parseme.ranges.dup
		else
			@ranges = parse(parseme)
		end
		reset
	end

	def self.parse(parseme)
		self.new.parse(parseme)
	end

	def parse(parseme)
		return nil if not parseme
		ranges = []
		parseme.split(' ').each { |arg|
			if arg.include?("/")
				# Then it's CIDR notation and needs special case
				if arg =~ /[,-]/
					# Improper CIDR notation (can't mix with 1,3 or 1-3 style IP ranges)
					return false
				end
				expanded = expand_cidr(arg)
				if expanded
					ranges += expanded
				else
					return false
				end
			elsif arg.include?(":")
				# Then it's IPv6
				# Can't really do much with IPv6 right now, just return it and
				# hope for the best
				addr = Rex::Socket.addr_atoi(arg)
				ranges.push [addr, addr, true]
			elsif arg =~ /[^-0-9,.*]/
				# Then it's a domain name and we should send it on to addr_atoi
				# unmolested to force a DNS lookup.
				addr = Rex::Socket.addr_atoi(arg)
				ranges.push [addr, addr]
			else
				expanded = expand_nmap(arg)
				if expanded
					ranges += expanded
				else
					return false
				end
			end
		}

		return ranges
	end

	#
	# Resets the subnet walker back to its original state.
	#
	def reset
		return false if not valid?
		@curr_range = 0
		@curr_addr = @ranges[0][0]

		@length = 0
		@ranges.each { |r| @length += r[1] - r[0] + 1 }
	end

	#
	# Returns the next IP address.
	#
	def next_ip
		return false if not valid?
		if (@curr_addr > @ranges[@curr_range][1])
			if (@curr_range >= @ranges.length - 1)
				return nil
			end
			@curr_range += 1
			@curr_addr = @ranges[@curr_range][0]
		end
		addr = Rex::Socket.addr_itoa(@curr_addr, @ranges[@curr_range][2])
		@curr_addr += 1
		return addr
	end

	def valid?
		(@ranges and not @ranges.empty?)
	end

	# 
	# Returns true if the argument is an ip address that falls within any of
	# the stored ranges.
	#
	def include?(addr)
		return false if not @ranges
		if (addr.is_a? String)
			addr = Rex::Socket.addr_atoi(addr)
		end
		@ranges.map { |r| 
			if r.start <= addr and addr <= r.stop
				return true
			end
		}
		return false
	end

	# 
	# Calls the given block with each address
	#
	def each(&block)
		while (ip = next_ip)
			block.call(ip)
		end
	end

	#
	# Returns an array with one element, a Range defined by the given CIDR
	# block.
	#
	def expand_cidr(arg)
		start,stop = Rex::Socket.cidr_crack(arg)
		if !start or !stop
			return false
		end
		range = Range.new
		range.start = Rex::Socket.addr_atoi(start)
		range.stop = Rex::Socket.addr_atoi(stop)
		range.ipv6 = (arg.include?(":"))

		return [range]
	end

	#
	# Expands an nmap-style host range x.x.x.x where x can be simply "*" which
	# means 0-255 or any combination and repitition of:
	#    i,n
	#    n-m
	#    i,n-m
	#    n-m,i
	# ensuring that n is never greater than m.
	#
	# non-unique elements will be removed
	#  e.g.: 
	#    10.1.1.1-3,2-2,2 =>  ["10.1.1.1", "10.1.1.2", "10.1.1.3"]
	#    10.1.1.1-3,7 =>  ["10.1.1.1", "10.1.1.2", "10.1.1.3", "10.1.1.7"]
	#
	# Returns an array of Ranges
	#
	def expand_nmap(arg)
		# Can't really do anything with IPv6
		return false if arg.include?(":")

		# nmap calls these errors, but it's hard to catch them with our
		# splitting below, so short-cut them here
		return false if arg.include?(",-") or arg.include?("-,")

		bytes = []
		sections = arg.split('.')
		if sections.length != 4
			# Too many or not enough dots
			return false
		end
		sections.each { |section|
			if section.empty?
				# pretty sure this is an unintentional artifact of the C
				# functions that turn strings into ints, but it sort of makes
				# sense, so why not
				#   "10...1" => "10.0.0.1"
				section = "0"
			end

			if section == "*"
				# I think this ought to be 1-254, but this is how nmap does it.
				section = "0-255"
			elsif section.include?("*")
				return false
			end

			# Break down the sections into ranges like so
			# "1-3,5-7" => ["1-3", "5-7"]
			ranges = section.split(',', -1)
			sets = []
			ranges.each { |r| 
				bounds = []
				if r.include?('-')
					# Then it's an actual range, break it down into start,stop
					# pairs:
					#   "1-3" => [ 1, 3 ]
					# if the lower bound is empty, start at 0
					# if the upper bound is empty, stop at 255
					#
					bounds = r.split('-', -1)
					return false if (bounds.length > 2)

					bounds[0] = 0   if bounds[0].nil? or bounds[0].empty?
					bounds[1] = 255 if bounds[1].nil? or bounds[1].empty?
					bounds.map!{|b| b.to_i}
					return false if bounds[0] > bounds[1]
				else
					# Then it's a single value
					bounds[0] = r.to_i
				end
				return false if bounds[0] > 255 or (bounds[1] and bounds[1] > 255)
				return false if bounds[1] and bounds[0] > bounds[1]
				if bounds[1]
					bounds[0].upto(bounds[1]) do |i| 
						sets.push(i)
					end
				elsif bounds[0]
					sets.push(bounds[0])
				end
			}
			bytes.push(sets.sort.uniq)
		}

		#
		# Combinitorically squish all of the quads together into a big list of
		# ip addresses, stored as ints
		#
		# e.g.: 
		#  [[1],[1],[1,2],[1,2]] 
		#  => 
		#  [atoi("1.1.1.1"),atoi("1.1.1.2"),atoi("1.1.2.1"),atoi("1.1.2.2")]
		addrs = []
		for a in bytes[0]
			for b in bytes[1]
				for c in bytes[2]
					for d in bytes[3]
						ip = (a << 24) + (b << 16) + (c << 8) + d
						addrs.push ip
					end
				end
			end
		end

		addrs.sort!
		addrs.uniq!
		rng = Range.new
		rng.start = addrs[0]
		ranges = []
		1.upto(addrs.length - 1) do |idx|
			if addrs[idx - 1] + 1 == addrs[idx]
				# Then this address is contained in the current range
				next
			else
				# Then this address is the upper bound for the current range
				rng.stop = addrs[idx - 1]
				ranges.push(rng.dup)
				rng.start = addrs[idx]
			end
		end
		rng.stop = addrs[addrs.length - 1]
		ranges.push(rng.dup)
		return ranges
	end

	#
	# The total number of IPs within the range
	#
	attr_reader :ranges
	attr_reader :length

	# for backwards compatibility
	alias :num_ips :length

end

class Range < Array
	def start; self[0]; end
	def stop;  self[1]; end
	def ipv6;  self[2]; end
	def start=(val); self[0] = val; end
	def stop=(val);  self[1] = val; end
	def ipv6=(val);  self[2] = val; end
end

end
end
