Module:IP: Difference between revisions

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(implement IPAddress getNextIP and getPreviousIP)
(use uniqueId table for helper functions to create an IPAddress; implement ip:isInSubnet(); functions like subnet:getPrefix() return an IPAddress not a string, I assume)
Line 3: Line 3:


-- Load modules
-- Load modules
local bit32 = require('bit32')
local libraryUtil = require('libraryUtil')
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkType = libraryUtil.checkType
Line 29: Line 30:
-- Instead, move the metamethods into IPAddress.new(ip) so they can
-- Instead, move the metamethods into IPAddress.new(ip) so they can
-- access the data upvalue?
-- access the data upvalue?
-- Hmmm, that would work only for self, not for the other object.
-- Is there a way of keeping data private but accessing it from metamethods?
-- If getIPParts is kept, perhaps it should be changed to "getParts" or similar
-- as "IP" is redundant in an IPAddress class.


------------------------------------------------------------------------
------------------------------------------------------------------------
-- Functions from Module:IPblock follow.
-- Functions from Module:IPblock follow.
-- TODO Massage for style consistent with this module.
-- TODO Massage following for style consistent with this module.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Line 45: Line 50:
join = function (self, sep)
join = function (self, sep)
return table.concat(self, sep)
return table.concat(self, sep)
⚫
end,
remove = function (self, pos)
if self.n > 0 and (pos == nil or (0 < pos and pos <= self.n)) then
⚫
self.n = self.n - 1
return table.remove(self, pos)
⚫
end
end,
end,
sort = function (self, comp)
sort = function (self, comp)
Line 56: Line 55:
end,
end,
}
}
⚫
end

⚫
local function copyChanged(parts, down)
⚫
-- Return a copy of IPv4 or IPv6 parts, incremented or decremented.
⚫
-- Will wraparound:
⚫
-- increment 255.255.255.255 → 0.0.0.0
⚫
-- ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff → ::
⚫
-- decrement 0.0.0.0 → 255.255.255.255
⚫
-- :: → ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
⚫
local result = { n = parts.n }
⚫
local carry = down and 0xffff or 1
⚫
for i = parts.n, 1, -1 do
⚫
local sum = parts[i] + carry
⚫
if sum >= 0x10000 then
⚫
carry = down and 0x10000 or 1
⚫
sum = sum - 0x10000
⚫
else
⚫
carry = down and 0xffff or 0
⚫
end
⚫
result[i] = sum
⚫
end
⚫
return result
⚫
end

local function copyPrefix(parts, length)
-- Return a copy of IPv4 or IPv6 parts, masked to length.
local result = { n = parts.n }
for i = 1, parts.n do
if length > 0 then
if length >= 16 then
result[i] = parts[i]
⚫
length = length - 16
else
result[i] = bit32.band(parts[i],
bit32.arshift(0xffff8000, length - 1))
length = 0
⚫
end
else
result[i] = 0
end
end
return result
end
end


Line 182: Line 223:
end
end
return false
return false
⚫
end

⚫
local function copyChanged(parts, down)
⚫
-- Return a copy of IPv4 or IPv6 parts, incremented or decremented.
⚫
-- Will wraparound:
⚫
-- increment 255.255.255.255 → 0.0.0.0
⚫
-- ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff → ::
⚫
-- decrement 0.0.0.0 → 255.255.255.255
⚫
-- :: → ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
⚫
local result = { n = parts.n }
⚫
local carry = down and 0xffff or 1
⚫
for i = parts.n, 1, -1 do
⚫
local sum = parts[i] + carry
⚫
if sum >= 0x10000 then
⚫
carry = down and 0x10000 or 1
⚫
sum = sum - 0x10000
⚫
else
⚫
carry = down and 0xffff or 0
⚫
end
⚫
result[i] = sum
⚫
end
⚫
return result
end
end


--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
-- IPAddress class
-- IPAddress class
-- Represents a single ipv4 or ipv6 address.
-- Represents a single IPv4 or IPv6 address.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


local IPAddress = {}
local IPAddress = {}
local uniqueId = {}


do
do
Line 242: Line 262:


function obj:isInSubnet(subnet)
function obj:isInSubnet(subnet)
-- TODO Consider alternative of checking:
-- (ipFirst <= self and self <= ipLast)
if self:getVersion() == subnet:getVersion() then
local masked = IPAddress.new(uniqueId,
copyPrefix(data.parts, subnet:getBitLength()))
return masked == subnet:getPrefix()
end
return false
return false
end
end


function obj:getNextIP()
function obj:getNextIP()
return IPAddress.new(IPAddress, copyChanged(data.parts))
return IPAddress.new(uniqueId, copyChanged(data.parts))
end
end


function obj:getPreviousIP()
function obj:getPreviousIP()
return IPAddress.new(IPAddress, copyChanged(data.parts, true))
return IPAddress.new(uniqueId, copyChanged(data.parts, true))
end
end


Line 259: Line 286:


-- Set initial values
-- Set initial values
if ip == IPAddress then
if ip == uniqueId then
data.parts = parts
data.parts = parts
else
else
Line 310: Line 337:
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
-- Subnet class
-- Subnet class
-- Represents a block of ipv4 or ipv6 addresses.
-- Represents a block of IPv4 or IPv6 addresses.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Line 333: Line 360:


function obj:getPrefix()
function obj:getPrefix()
return '1.2.3.0'
return IPAddress.new('1.2.144.0')
end
end


function obj:getHighestIP()
function obj:getHighestIP()
return '1.2.3.255'
return IPAddress.new('1.2.159.255')
end
end


function obj:getBitLength()
function obj:getBitLength()
return 24
return 20
end
end


Revision as of 07:43, July 17, 2016

Module:IP is a library for working with IP addresses and subnets. It can handle both IPv4 and IPv6. The library exports four classes, IPAddress, Subnet, IPv4Collection, and IPv6Collection.

Loading the library

local IP = require('Module:IP')
local IPAddress = IP.IPAddress
local Subnet = IP.Subnet

IPAddress

The IPAddress class is used to work with single IP addresses. To create a new IPAddress object: 

local ipAddress = IPAddress.new(ipString)

The ipString variable can be a valid IPv4 or IPv6 address.

Examples: 

local ipv4Address = IPAddress.new('1.2.3.4')
local ipv6Address = IPAddress.new('2001:db8::ff00:12:3456')

IPAddress objects can be compared with relational operators: 

-- Equality
IPAddress.new('1.2.3.4') == IPAddress.new('1.2.3.4') -- true
IPAddress.new('1.2.3.4') == IPAddress.new('1.2.3.5') -- false

-- Less than / greater than
IPAddress.new('1.2.3.4') < IPAddress.new('1.2.3.5')  -- true
IPAddress.new('1.2.3.4') > IPAddress.new('1.2.3.5')  -- false
IPAddress.new('1.2.3.4') <= IPAddress.new('1.2.3.5') -- true
IPAddress.new('1.2.3.4') <= IPAddress.new('1.2.3.4') -- true

You can use tostring on them (this is equivalent to using getIP): 

tostring(IPAddress.new('1.2.3.4'))                -- "1.2.3.4"
tostring(IPAddress.new('2001:db8::ff00:12:3456')) -- "2001:db8::ff00:12:3456"

-- Expanded IPv6 addresses are abbreviated:
tostring(IPAddress.new('2001:db8:0:0:0:0:0:0'))   -- "2001:db8::"

You can also concatenate them: 

IPAddress.new('1.2.3.4') .. ' foo'                   -- "1.2.3.4 foo"
IPAddress.new('1.2.3.4') .. IPAddress.new('5.6.7.8') -- "1.2.3.45.6.7.8"

IPAddress objects have several methods, outlined below.

getIP

ipAddress:getIP()

Returns a string representation of the IP address. IPv6 addresses are abbreviated if possible.

Examples: 

IPAddress.new('1.2.3.4'):getIP()                -- "1.2.3.4"
IPAddress.new('2001:db8::ff00:12:3456'):getIP() -- "2001:db8::ff00:12:3456"
IPAddress.new('2001:db8:0:0:0:0:0:0'):getIP()   -- "2001:db8::"

getVersion

ipAddress:getVersion()

Returns the version of the IP protocol being used. This is "IPv4" for IPv4 addresses, and "IPv6" for IPv6 addresses.

Examples: 

IPAddress.new('1.2.3.4'):getVersion()                -- "IPv4"
IPAddress.new('2001:db8::ff00:12:3456'):getVersion() -- "IPv6"

isIPv4

ipAddress:isIPv4()

Returns true if the IP address is an IPv4 address, and false otherwise.

Examples: 

IPAddress.new('1.2.3.4'):isIPv4()                -- true
IPAddress.new('2001:db8::ff00:12:3456'):isIPv4() -- false

isIPv6

ipAddress:isIPv6()

Returns true if the IP address is an IPv6 address, and false otherwise.

Examples: 

IPAddress.new('1.2.3.4'):isIPv6()                -- false
IPAddress.new('2001:db8::ff00:12:3456'):isIPv6() -- true

isInSubnet

ipAddress:isInSubnet(subnet)

Returns true if the IP address is in the subnet subnet, and false otherwise. subnet may be a Subnet object or a CIDR string.

Examples: 

IPAddress.new('1.2.3.4'):isInSubnet('1.2.3.0/24')                             -- true
IPAddress.new('1.2.3.4'):isInSubnet('1.2.4.0/24')                             -- false
IPAddress.new('1.2.3.4'):isInSubnet(Subnet.new('1.2.3.0/24'))                 -- true
IPAddress.new('2001:db8::ff00:12:3456'):isInSubnet('2001:db8::ff00:12:0/112') -- true

getSubnet

ipAddress:getSubnet(bitLength)

Returns a Subnet object for the subnet with a bit length of bitLength which contains the current IP. The bitLength parameter must be an integer between 0 and 32 for IPv4 addresses, or an integer between 0 and 128 for IPv6 addresses.

Examples: 

IPAddress.new('1.2.3.4'):getSubnet(24) -- Equivalent to Subnet.new('1.2.3.0/24')

getNextIP

ipAddress:getNextIP()

Returns a new IPAddress object equivalent to the current IP address incremented by one. The IPv4 address "255.255.255.255" rolls around to "0.0.0.0", and the IPv6 address "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff" rolls around to "::".

Examples: 

IPAddress.new('1.2.3.4'):getNextIP()                -- Equivalent to IPAddress.new('1.2.3.5')
IPAddress.new('2001:db8::ff00:12:3456'):getNextIP() -- Equivalent to IPAddress.new('2001:db8::ff00:12:3457')
IPAddress.new('255.255.255.255'):getNextIP()        -- Equivalent to IPAddress.new('0.0.0.0')

getPreviousIP

ipAddress:getPreviousIP()

Returns a new IPAddress object equivalent to the current IP address decremented by one. The IPv4 address "0.0.0.0" rolls around to "255.255.255.255", and the IPv6 address "::" rolls around to "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff".

Examples: 

IPAddress.new('1.2.3.4'):getPreviousIP()                -- Equivalent to IPAddress.new('1.2.3.3')
IPAddress.new('2001:db8::ff00:12:3456'):getPreviousIP() -- Equivalent to IPAddress.new('2001:db8::ff00:12:3455')
IPAddress.new('0.0.0.0'):getPreviousIP()                -- Equivalent to IPAddress.new('255.255.255.255')

Subnet

The Subnet class is used to work with subnetworks of IPv4 or IPv6 addresses. To create a new Subnet object: 

local subnet = Subnet.new(cidrString)

cidrString must be a valid IPv4 or IPv6 CIDR string.

Subnet objects can be compared for equality: 

Subnet.new('1.2.3.0/24') == Subnet.new('1.2.3.0/24')                           -- true
Subnet.new('1.2.3.0/24') == Subnet.new('1.2.3.0/25')                           -- false
Subnet.new('1.2.3.0/24') == Subnet.new('2001:db8::ff00:12:0/112')              -- false
Subnet.new('2001:db8::ff00:12:0/112') == Subnet.new('2001:db8::ff00:12:0/112') -- true
Subnet.new('2001:db8:0:0:0:0:0:0/112') == Subnet.new('2001:db8::/112')         -- true

You can use tostring on them (this is equivalent to getCIDR): 

tostring(Subnet.new('1.2.3.0/24'))               -- "1.2.3.0/24"
tostring(Subnet.new('2001:db8::ff00:12:0/112'))  -- "2001:db8::ff00:12:0/112"
tostring(Subnet.new('2001:db8:0:0:0:0:0:0/112')) -- "2001:db8::/112"

You can also concatenate them: 

Subnet.new('1.2.3.0/24') .. ' foo'                   -- "1.2.3.0/24 foo"
Subnet.new('1.2.3.0/24') .. Subnet.new('4.5.6.0/24') -- "1.2.3.0/244.5.6.0/24"

Subnet objects have several methods, outlined below.

getPrefix

subnet:getPrefix()

Returns an IPAddress object for the lowest IP address in the subnet.

Examples: 

Subnet.new('1.2.3.0/24'):getPrefix()              -- Equivalent to IPAddress.new('1.2.3.0')
Subnet.new('2001:db8::ff00:12:0/112'):getPrefix() -- Equivalent to IPAddress.new('2001:db8::ff00:12:0')

getHighestIP

subnet:getHighestIP()

Returns an IPAddress object for the highest IP address in the subnet.

Examples: 

Subnet.new('1.2.3.0/24'):getHighestIP()              -- Equivalent to IPAddress.new('1.2.3.255')
Subnet.new('2001:db8::ff00:12:0/112'):getHighestIP() -- Equivalent to IPAddress.new('2001:db8::ff00:12:ffff')

getBitLength

subnet:getBitLength()

Returns the bit length of the subnet. This is an integer between 0 and 32 for IPv4 addresses, or an integer between 0 and 128 for IPv6 addresses.

Examples: 

Subnet.new('1.2.3.0/24'):getBitLength()              -- 24
Subnet.new('2001:db8::ff00:12:0/112'):getBitLength() -- 112

getCIDR

subnet:getCIDR()

Returns a CIDR string representation of the subnet.

Examples: 

Subnet.new('1.2.3.0/24'):getCIDR()               -- "1.2.3.0/24"
Subnet.new('2001:db8::ff00:12:0/112'):getCIDR()  -- "2001:db8::ff00:12:0/112"
Subnet.new('2001:db8:0:0:0:0:0:0/112'):getCIDR() -- "2001:db8::/112"

getVersion

subnet:getVersion()

Returns the version of the IP protocol being used. This is "IPv4" for IPv4 addresses, and "IPv6" for IPv6 addresses.

Examples: 

Subnet.new('1.2.3.0/24'):getVersion()              -- "IPv4"
Subnet.new('2001:db8::ff00:12:0/112'):getVersion() -- "IPv6"

isIPv4

subnet:isIPv4()

Returns true if the subnet is using IPv4, and false otherwise.

Examples: 

Subnet.new('1.2.3.0/24'):isIPv4()              -- true
Subnet.new('2001:db8::ff00:12:0/112'):isIPv4() -- false

isIPv6

subnet:isIPv6()

Returns true if the subnet is using IPv6, and false otherwise.

Examples: 

Subnet.new('1.2.3.0/24'):isIPv6()              -- false
Subnet.new('2001:db8::ff00:12:0/112'):isIPv6() -- true

containsIP

subnet:containsIP(ip)

Returns true if the subnet contains the IP address ip, and false otherwise. ip can be an IP address string, or an IPAddress object.

Examples: 

Subnet.new('1.2.3.0/24'):containsIP('1.2.3.4')                             -- true
Subnet.new('1.2.3.0/24'):containsIP('1.2.4.4')                             -- false
Subnet.new('1.2.3.0/24'):containsIP(IPAddress.new('1.2.3.4'))              -- true
Subnet.new('2001:db8::ff00:12:0/112'):containsIP('2001:db8::ff00:12:3456') -- true

overlapsSubnet

subnet:overlapsSubnet(subnet)

Returns true if the current subnet overlaps with subnet, and false otherwise. subnet can be a CIDR string or a subnet object.

Examples: 

Subnet.new('1.2.3.0/24'):overlapsSubnet('1.2.0.0/16')                         -- true
Subnet.new('1.2.3.0/24'):overlapsSubnet('1.2.12.0/22')                        -- false
Subnet.new('1.2.3.0/24'):overlapsSubnet(Subnet.new('1.2.0.0/16'))             -- true
Subnet.new('2001:db8::ff00:12:0/112'):overlapsSubnet('2001:db8::ff00:0:0/96') -- true

walk

subnet:walk()

The walk method iterates over all of the IPAddress objects in the subnet.

Examples: 

for ipAddress in Subnet.new('192.168.0.0/30'):walk() do
	mw.log(tostring(ipAddress))
end
-- 192.168.0.0
-- 192.168.0.1
-- 192.168.0.2
-- 192.168.0.3

IPv4Collection

The IPv4Collection class is used to work with several different IPv4 addresses and IPv4 subnets. To create a new IPv4Collection object: 

local collection = IPv4Collection.new()

IPv4Collection objects have several methods, outlined below.

getVersion

collection:getVersion()

Returns the string "IPv4".

addIP

collection:addIP(ip)

Adds an IP to the collection. The IP can be either a string or an IPAddress object.

Examples: 

collection:addIP('1.2.3.4')
collection:addIP(IPAddress.new('1.2.3.4'))

This method is chainable: 

collection:addIP('1.2.3.4'):addIP('5.6.7.8')

addSubnet

collection:addSubnet(subnet)

Adds a subnet to the collection. The subnet can be either a CIDR string or a Subnet object.

Examples: 

collection:addSubnet('1.2.3.0/24')
collection:addSubnet(Subnet.new('1.2.3.0/24'))

This method is chainable: 

collection:addSubnet('1.2.0.0/24'):addSubnet('1.2.1.0/24')

addFromString

collection:addFromString(str)

Extracts any IPv4 addresses and IPv4 CIDR subnets from str and adds them to the collection. Any text that is not an IPv4 address or CIDR subnet is ignored.

Examples: 

collection:addFromString('Add some IPs and subnets: 1.2.3.4 1.2.3.5 2001:0::f foo 1.2.4.0/24')

This method is chainable: 

collection:addFromString('foo 1.2.3.4'):addFromString('bar 5.6.7.8')

containsIP

collection:containsIP(ip)

Returns true if the collection contains the specified IP; otherwise returns false. The ip parameter can be a string or an IPAddress object.

Examples: 

collection:containsIP('1.2.3.4')
collection:containsIP(IPAddress.new('1.2.3.4'))

getRanges

collection:getRanges()

Returns a sorted array of IP pairs equivalent to the collection. Each IP pair is an array representing a contiguous range of IP addresses from pair[1] to pair[2] inclusive. pair[1] and pair[2] are IPAddress objects.

Examples: 

collection:addSubnet('1.2.0.0/24')
collection:addSubnet('1.2.1.0/24')
collection:addSubnet('1.2.10.0/24')
mw.logObject(collection:getRanges())
-- Logs the following:
-- table#1 {
--   table#2 {
--     1.2.0.0,
--     1.2.1.255,
--   },
--   table#3 {
--     1.2.10.0,
--     1.2.10.255,
--   },
-- }

overlapsSubnet

collection:overlapsSubnet(subnet)

Returns true, obj if subnet overlaps this collection, where obj is the first IPAddress or Subnet object overlapping the subnet. Otherwise, returns false. subnet can be a CIDR string or a Subnet object.

Examples: 

collection:addIP('1.2.3.4')
collection:overlapsSubnet('1.2.3.0/24') -- true, IPAddress.new('1.2.3.4')
collection:overlapsSubnet('1.2.4.0/24') -- false

IPv6Collection

The IPv6Collection class is used to work with several different IPv6 addresses and IPv6 subnets. IPv6Collection objects are directly analogous to IPv4Collection objects: they contain the same methods and work the same way, but all IP addresses and subnets added to it must be IPv6, not IPv4.

To create a new IPv6Collection object: 

local collection = IPv6Collection.new()



-- IP library
-- This library contains classes for working with IP addresses and IP ranges.

-- Load modules
local bit32 = require('bit32')
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType

-- Constants
local V4 = 'IPv4'
local V6 = 'IPv6'

--------------------------------------------------------------------------------
-- TODO Remove items from these notes when satisfied they are ok.

-- IPAddress does not need mt:__le(obj) as Lua evaluates (a <= b) as (not (b < a))
-- and that is correct for IP addresses.

-- IPAddress obj:getIP() needs thought.
-- At first, it looked like the representation of the IP (the numbers).
-- But perhaps it is intended to be a string as in the testcases.
-- Is it really just a copy of the input string?
-- What if the input is "  1.2.3.4  " (with leading and trailing spaces which
-- the code ignores)?
-- Also, tostring(ip) for an IPv6 address will return the normalized string
-- which might be different from the input. Example:
-- input "1:02:003:0004:0:0:0:0" is "1:2:3:4::" after normalization.

-- Should obj:getIPParts() be removed?
-- Instead, move the metamethods into IPAddress.new(ip) so they can
-- access the data upvalue?
-- Hmmm, that would work only for self, not for the other object.
-- Is there a way of keeping data private but accessing it from metamethods?
-- If getIPParts is kept, perhaps it should be changed to "getParts" or similar
-- as "IP" is redundant in an IPAddress class.

------------------------------------------------------------------------
-- Functions from Module:IPblock follow.
-- TODO Massage following for style consistent with this module.
--------------------------------------------------------------------------------

local function collection()
	-- Return a table to hold items.
	return {
		n = 0,
		add = function (self, item)
			self.n = self.n + 1
			self[self.n] = item
		end,
		join = function (self, sep)
			return table.concat(self, sep)
		end,
		sort = function (self, comp)
			table.sort(self, comp)
		end,
	}
end

local function copyChanged(parts, down)
	-- Return a copy of IPv4 or IPv6 parts, incremented or decremented.
	-- Will wraparound:
	--   increment 255.255.255.255 → 0.0.0.0
	--             ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff → ::
	--   decrement 0.0.0.0 → 255.255.255.255
	--             :: → ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
	local result = { n = parts.n }
	local carry = down and 0xffff or 1
	for i = parts.n, 1, -1 do
		local sum = parts[i] + carry
		if sum >= 0x10000 then
			carry = down and 0x10000 or 1
			sum = sum - 0x10000
		else
			carry = down and 0xffff or 0
		end
		result[i] = sum
	end
	return result
end

local function copyPrefix(parts, length)
	-- Return a copy of IPv4 or IPv6 parts, masked to length.
	local result = { n = parts.n }
	for i = 1, parts.n do
		if length > 0 then
			if length >= 16 then
				result[i] = parts[i]
				length = length - 16
			else
				result[i] = bit32.band(parts[i],
					bit32.arshift(0xffff8000, length - 1))
				length = 0
			end
		else
			result[i] = 0
		end
	end
	return result
end

local function ipv6String(ip)
	-- Return a string equivalent to the given IPv6 address.
	local z1, z2  -- indices of run of zeros to be displayed as "::"
	local zstart, zcount
	for i = 1, 9 do
		-- Find left-most occurrence of longest run of two or more zeros.
		if i < 9 and ip[i] == 0 then
			if zstart then
				zcount = zcount + 1
			else
				zstart = i
				zcount = 1
			end
		else
			if zcount and zcount > 1 then
				if not z1 or zcount > z2 - z1 + 1 then
					z1 = zstart
					z2 = zstart + zcount - 1
				end
			end
			zstart = nil
			zcount = nil
		end
	end
	local parts = collection()
	for i = 1, 8 do
		if z1 and z1 <= i and i <= z2 then
			if i == z1 then
				if z1 == 1 or z2 == 8 then
					if z1 == 1 and z2 == 8 then
						return '::'
					end
					parts:add(':')
				else
					parts:add('')
				end
			end
		else
			parts:add(string.format('%x', ip[i]))
		end
	end
	return table.concat(parts, ':')
end

local function ipString(ip)
	-- Return a string equivalent to given IP address (IPv4 or IPv6).
	if ip.n == 2 then
		-- IPv4.
		local parts = {}
		for i = 1, 2 do
			local w = ip[i]
			local q = i == 1 and 1 or 3
			parts[q] = math.floor(w / 256)
			parts[q+1] = w % 256
		end
		return table.concat(parts, '.')
	end
	return ipv6String(ip)
end

local function ipv4Address(data, ipStr)
	-- If ipStr is a valid IPv4 string, store its parts in data and
	-- return true. Otherwise, return false.
	-- This representation is for compatibility with IPv6 addresses.
	local octets = collection()
	local s = ipStr:match('^%s*(.-)%s*$') .. '.'
	for item in s:gmatch('(.-)%.') do
		octets:add(item)
	end
	if octets.n == 4 then
		for i, s in ipairs(octets) do
			if s:match('^%d+$') then
				local num = tonumber(s)
				if 0 <= num and num <= 255 then
					if num > 0 and s:match('^0') then
						-- A redundant leading zero is for an IP in octal.
						return false
					end
					octets[i] = num
				else
					return false
				end
			else
				return false
			end
		end
		data.parts = collection()
		for i = 1, 3, 2 do
			data.parts:add(octets[i] * 256 + octets[i+1])
		end
		return true
	end
	return false
end

local function ipv6Address(data, ipStr)
	-- If ipStr is a valid IPv6 string, store its parts in data and
	-- return true. Otherwise, return false.
	ipStr = ipStr:match('^%s*(.-)%s*$')
	local _, n = ipStr:gsub(':', ':')
	if n < 7 then
		ipStr, n = ipStr:gsub('::', string.rep(':', 9 - n))
	end
	local parts = collection()
	for item in (ipStr .. ':'):gmatch('(.-):') do
		parts:add(item)
	end
	if parts.n == 8 then
		for i, s in ipairs(parts) do
			if s == '' then
				parts[i] = 0
			else
				local num = tonumber('0x' .. s)
				if num and 0 <= num and num <= 65535 then
					parts[i] = num
				else
					return false
				end
			end
		end
		data.parts = parts
		return true
	end
	return false
end

--------------------------------------------------------------------------------
-- IPAddress class
-- Represents a single IPv4 or IPv6 address.
--------------------------------------------------------------------------------

local IPAddress = {}
local uniqueId = {}

do
	-- Initialize metatable
	local mt = {}

	-- Constructor
	function IPAddress.new(ip, parts)

		-- Set up structure
		local obj = setmetatable({}, mt)
		local data = {}

		-- Public methods
		function obj:getIP()
			return ipString(data.parts)
		end

		function obj:getVersion()
			return data.version
		end

		function obj:isIPv4()
			return data.version == V4
		end

		function obj:isIPv6()
			return data.version == V6
		end

		function obj:isInSubnet(subnet)
			-- TODO Consider alternative of checking:
			--   (ipFirst <= self and self <= ipLast)
			if self:getVersion() == subnet:getVersion() then
				local masked = IPAddress.new(uniqueId,
					copyPrefix(data.parts, subnet:getBitLength()))
				return masked == subnet:getPrefix()
			end
			return false
		end

		function obj:getNextIP()
			return IPAddress.new(uniqueId, copyChanged(data.parts))
		end

		function obj:getPreviousIP()
			return IPAddress.new(uniqueId, copyChanged(data.parts, true))
		end

		-- This is ugly but can't see how else to do it.
		function obj:getIPParts()
			return data.parts
		end

		-- Set initial values
		if ip == uniqueId then
			data.parts = parts
		else
			checkType('IPAddress.new', 1, ip, 'string')
			if not (ipv4Address(data, ip) or ipv6Address(data, ip)) then
				error('invalid IP', 2)
			end
		end
		data.version = data.parts.n == 2 and V4 or V6

		return obj
	end

	-- Metamethods
	function mt:__concat(obj)
		return tostring(self) .. tostring(obj)
	end

	function mt:__eq(obj)
		local lhs, rhs = self:getIPParts(), obj:getIPParts()
		if lhs.n == rhs.n then
			for i = 1, lhs.n do
				if lhs[i] ~= rhs[i] then
					return false
				end
			end
			return true
		end
		return false
	end

	function mt:__lt(obj)
		local lhs, rhs = self:getIPParts(), obj:getIPParts()
		if lhs.n == rhs.n then
			for i = 1, lhs.n do
				if lhs[i] ~= rhs[i] then
					return lhs[i] < rhs[i]
				end
			end
			return false
		end
		return lhs.n < rhs.n
	end

	function mt:__tostring()
		return ipString(self:getIPParts())
	end
end

--------------------------------------------------------------------------------
-- Subnet class
-- Represents a block of IPv4 or IPv6 addresses.
--------------------------------------------------------------------------------

local Subnet = {}

do
	-- Initialize metatable
	local mt = {}

	-- Constructor
	function Subnet.new(options)
		-- Set up structure
		local obj = setmetatable({}, mt)
		local data = {}

		-- Public methods
		function obj:addIPs(...)
		end

		function obj:addIPsFromString(s)
		end

		function obj:getPrefix()
			return IPAddress.new('1.2.144.0')
		end

		function obj:getHighestIP()
			return IPAddress.new('1.2.159.255')
		end

		function obj:getBitLength()
			return 20
		end

		function obj:getCIDR()
			return string.format('%s/%d', self:getPrefix(), self:getBitLength())
		end

		function obj:getVersion()
			return data.version
		end

		function obj:isIPv4()
			return data.version == V4
		end

		function obj:isIPv6()
			return data.version == V6
		end

		function obj:containsIP(ip)
			return false
		end

		function obj:overlapsSubnet(subnet)
		end

		-- Set initial values
		data.version = V4

		return obj
	end

	-- Metamethods
	function mt:__eq(obj)
		return false
	end

	function mt:__tostring()
		return self:getCIDR()
	end
end

return {
	IPAddress = IPAddress,
	Subnet = Subnet,
}
Retrieved from "https://crocwiki.com/wiki/Module:IP?oldid=30966"