path: root/lua/inet/init.lua

-- ipv4 / 24 = network
-- ipv6/56 * 5 = 5 /56 further down

local bit32 = require 'bit32'

local format = string.format

local lshift = bit32.lshift
local rshift = bit32.rshift
local band = bit32.band
local replace = bit32.replace
local bxor = bit32.bxor

local mt2fam = {}

local inet = {}
inet.__index = inet

local inet4 = setmetatable({}, inet)
inet4.__index = inet4
mt2fam[inet4] = 4

local inet6 = setmetatable({}, inet)
inet6.__index = inet6
mt2fam[inet6] = 6

local function get_mt(t)
	if type(t) ~= 'table' then return nil end
	return getmetatable(t)
end

local function is_inet4(t)
	local mt = get_mt(t)
	return mt == inet4
end

local function is_inet6(t)
	local mt = get_mt(t)
	return mt == inet6
end

local function is_inet(t)
	local mt = get_mt(t)
	return mt == inet4 or mt == inet6
end

function inet:__len()
	local mask = self.mask
	if mask == nil then return 0 end -- make metatable inspectable
	return mask
end
inet4.__len = inet.__len
inet6.__len = inet.__len

function inet:family()
	local mt = assert(getmetatable(self))
	return assert(mt2fam[mt])
end

local ipv4_parser
local ipv6_parser
do
	local lpeg = require 'lpeg'
	local C, Ct = lpeg.C, lpeg.Ct
	local S, R = lpeg.S, lpeg.R
	local B, Cc = lpeg.B, lpeg.Cc

	local digit = R('09')

	local ipv4addr
	do
		local dot = S('.')
		local zero = S('0')
		local octet0 = B(zero) * Cc('0')
		local octet1 = R('19')
		local octet2 = R('19') * digit
		local octet31 = S('1') * digit * digit
		local octet32 = R('04') * digit
		local octet325 = S('5') * R('05')
		local octet3 = octet31 + (S('2') * (octet32 + octet325))
		local octet = zero^0 * (C(octet3 + octet2 + octet1) + octet0) / tonumber
		ipv4addr = octet * dot * octet * dot * octet * dot * octet
		local mask12 = R('12') * digit
		local mask3 = S('3') * R('02')
		local netmask = S('/') * C(mask12 + mask3 + digit)
		ipv4_parser = ipv4addr * (netmask + Cc()) * -1
	end

	do
		local function hextonumber(hex) return tonumber(hex, 16) end
		local hexdigit = R('09') + R('af') + R('AF')
		local piece = C(hexdigit * (hexdigit^-3)) / hextonumber
		local col = S(':')
		local colcol = C(col * col)
		local picol = piece * col
		local colpi = col * piece
		local ipv4embed = ipv4addr / function(a,b,c,d)
			return lshift(a, 8) + b, lshift(c, 8) + d
		end
		local last32bits = (ipv4embed + (picol * piece))
		local full = picol * picol * picol * picol * picol * picol * last32bits
		local partial = (piece * (colpi^-6))^-1 * colcol * ((picol^-6)*(ipv4embed+piece))^-1
		local netmask = S('/') * C((digit^-3)) / tonumber
		local pieces = full + partial
		ipv6_parser = Ct(pieces) * ((netmask + Cc())^-1) * -1
	end
end

local function build_bip(o1, o2, o3, o4)
	return lshift(o1, 24) + lshift(o2, 16) + lshift(o3, 8) + o4
end

local function inet4_from_string(ipstr)
	local o1, o2, o3, o4, mask = ipv4_parser:match(ipstr)
	if not o1 then return nil, 'parse error' end

	local bip = build_bip(o1, o2, o3, o4)
	return bip, tonumber(mask)
end

local function inet4_from_number(bip)
	return bip
end

local function inet4_from_table(t)
	if #t ~= 4 then return nil, 'invalid length' end
	for i=1,4 do
		local v = t[i]
		if type(v) ~= 'number' then return nil, 'invalid number' end
		if v < 0 or v > 255 then return nil, 'octet out of range' end
	end
	return build_bip(t[1], t[2], t[3], t[4])
end

local inet4_constructors = {
	string = inet4_from_string,
	number = inet4_from_number,
	table  = inet4_from_table,
}

local function inet6_from_string(ipstr)
	local pcs, netmask = ipv6_parser:match(ipstr)
	if not pcs then return nil, 'parse error' end
	if #pcs > 8 then return nil, 'too many pieces' end
	local zero_pieces = 8 - #pcs
	for i=1,#pcs do
		if pcs[i] == '::' then
			pcs[i] = 0
			for j=#pcs,i,-1 do
				pcs[j+zero_pieces] = pcs[j]
			end
			for j=1,zero_pieces do
				pcs[i+j] = 0
			end
		end
	end
	if #pcs > 8 then return nil, 'too many pieces' end
	if netmask ~= nil and netmask > 128 then
		return nil, 'invalid netmask'
	end
	return pcs, netmask
end

local function inet6_from_table(t)
	if #t ~= 8 then return nil, 'invalid length' end
	for i=1,8 do
		local v = t[i]
		if type(v) ~= 'number' then return nil, 'invalid number' end
		if v < 0 or v > 0xffff then return nil, 'octet out of range' end
	end
	return { t[1], t[2], t[3], t[4], t[5], t[6], t[7], t[8] }
end

local inet6_constructors = {
	string = inet6_from_string,
	table  = inet6_from_table,
}

local function decide_mask(from_ip, override, high)
	local newmask = from_ip
	if override then
		if type(override) == 'number' and override >= 0 and override <= high then
			if from_ip ~= nil then
				return nil, 'multiple masks supplied'
			end
			newmask = override
		else
			return nil, 'invalid mask'
		end
	else
		if not newmask then
			newmask = high
		end
	end
	return newmask
end

local function generic_new(constructors, high, ip, mask)
	local type_ip = type(ip)
	local constructor = constructors[type_ip]
	if not constructor then
		return nil, 'invalid ip argument'
	end
	local iir, ourmask = constructor(ip)
	if not iir then
		return nil, ourmask
	end
	local outmask, err = decide_mask(ourmask, mask, high)
	if not outmask then return nil, err end

	return iir, outmask
end

local function new_inet4(ip, mask)
	local bip, outmask = generic_new(inet4_constructors, 32, ip, mask)
	if not bip then return nil, outmask end
	return setmetatable({
		bip = bip,
		mask = outmask,
	}, inet4)
end

local function new_inet6(ip, mask)
	local pcs, outmask = generic_new(inet6_constructors, 128, ip, mask)
	if not pcs then return nil, outmask end

	local r = setmetatable({
		pcs = pcs,
		mask = outmask,
	}, inet6)

	-- ensure that the result is balanced
	if not r:is_balanced() then
		r:balance()
		return nil, tostring(r)..' unbalanced'
	end

	return r
end

local function new_inet(ip, mask)
	local is_ipv6
	local type_ip = type(ip)
	if type_ip == 'string' then
		is_ipv6 = string.find(ip, ':', 1, true)
	elseif type_ip == 'number' then
		is_ipv6 = false
	elseif is_inet4(ip) then
		mask = mask or #ip
		ip = ip.bip
		is_ipv6 = false
	elseif is_inet6(ip) then
		mask = mask or #ip
		ip = ip.pcs
		is_ipv6 = true
	elseif type_ip == 'table' then
		local n = #ip
		if n == 8 then
			is_ipv6 = true
		elseif n == 4 then
			is_ipv6 = false
		else
			return nil, 'invalid table'
		end
	else
		return nil, 'invalid ip type'
	end

	if is_ipv6 then
		return new_inet6(ip, mask)
	else
		return new_inet4(ip, mask)
	end
end

local function tostr4(self, withmask)
	-- return human readable
	local bip, mask = self.bip, self.mask
	local o1, o2, o3, o4
	o1 = band(rshift(bip, 24), 0xff)
	o2 = band(rshift(bip, 16), 0xff)
	o3 = band(rshift(bip, 8), 0xff)
	o4 = band(bip, 0xff)
	if (mask == nil or mask == 32 or withmask == false) and withmask ~= true then
		return string.format('%d.%d.%d.%d', o1, o2, o3, o4)
	else
		return string.format('%d.%d.%d.%d/%d', o1, o2, o3, o4, mask)
	end
end

function inet4:__tostring()
	return tostr4(self)
end

function inet4:ipstring()
	return tostr4(self, false)
end

function inet4:cidrstring()
	return tostr4(self, true)
end

function inet4:__add(n)
	return new_inet4(self.bip + n, self.mask)
end

function inet4:__sub(n)
	return new_inet4(self.bip - n, self.mask)
end

function inet4:__mul(n)
	local new = self.bip + (n * math.pow(2, 32 - self.mask))
	return new_inet4(new, self.mask)
end

function inet4:__div(n)
	return new_inet4(self.bip, n)
end

function inet4:__pow(n)
	return new_inet4(self.bip, self.mask + n)
end

function inet4:contains(other)
	if self.mask >= other.mask then
		return false
	end
	local mask = self.mask -- make test
	local self_netbits = replace(self.bip, 0, 0, 32-mask)
	local other_netbits = replace(other.bip, 0, 0, 32-mask)
	return self_netbits == other_netbits
end

function inet4:__lt(other)
	if self.bip == other.bip then
		return self.mask < other.mask
	end
	return self.bip < other.bip
end

function inet4:__le(other)
	if self.mask < other.mask then
		return false
	end
	local mask = other.mask
	if mask == 32 then
		return self.bip == other.bip
	else
		local selfnet = replace(self.bip, 0, 0, 32-mask)
		local othernet = replace(other.bip, 0, 0, 32-mask)
		return selfnet == othernet
	end
end

function inet4:__eq(other)
	return self.bip == other.bip and self.mask == other.mask
end

function inet4:network()
	local hostbits = 32 - self.mask
	return new_inet4(lshift(rshift(self.bip, hostbits), hostbits), self.mask)
end

function inet4:netmask()
	local hostbits = 32 - self.mask
	return new_inet4(replace(0xffffffff, 0, 0, hostbits), 32)
end

function inet4:flip()
	-- find twin by flipping the last network bit
	local mask = self.mask
	if mask == 0 then return nil end
	local hostbits = 32 - mask
	local flipbit = lshift(1, hostbits)
	return new_inet4(bxor(self.bip, flipbit), mask)
end

-- each ipv6 address is stored as eight pieces
-- 1111:2222:3333:4444:5555:6666:7777:8888
-- in the table pcs.

function inet6:is_balanced()
	local pcs = self.pcs
	for i=1,8 do
		local piece = pcs[i]
		if piece < 0 or piece > 0xffff then
			return false
		end
	end
	return true
end

function inet6:balance(quick)
	local pcs = self.pcs
	local i = 8
	while i > 1 do
		if quick and pcs[i] > 0 then
			break
		end
		while pcs[i] < 0 do
			pcs[i] = pcs[i] + 0x10000
			pcs[i-1] = pcs[i-1] - 1
		end
		i = i - 1
	end
	i = 8
	while i > 1 do
		local extra = rshift(pcs[i], 16)
		if quick and extra == 0 then
			break
		end
		pcs[i] = band(pcs[i], 0xffff)
		pcs[i-1] = pcs[i-1] + extra
		i = i - 1
	end
	pcs[1] = band(pcs[1], 0xffff)
	return self
end

local function tohex(n)
	if n == nil then return nil end
	return format('%x', n)
end

local function tostr6(self, withmask, embeddedipv4)
	-- return human readable
	local pcs = self.pcs
	local zeros = {}

	if embeddedipv4 == nil then
		embeddedipv4 = false -- TODO check if well-known prefix
	end

	local ipv6pieces = 8
	if embeddedipv4 then
		ipv6pieces = 6
	end

	-- count zero clusters
	local first_zero = 0
	local prev_was_zero = false
	for i=1,ipv6pieces do
		if pcs[i] == 0 then
			if prev_was_zero then
				zeros[first_zero] = zeros[first_zero] + 1
			else
				first_zero = i
				zeros[first_zero] = 1
			end
			prev_was_zero = true
		else
			prev_was_zero = false
		end
	end

	-- find the first largest zero cluster
	local zeros_begin = nil
	local zeros_cnt = 1
	for begin=1,ipv6pieces do
		local cnt = zeros[begin] or 0
		if cnt > zeros_cnt then
			zeros_begin = begin
			zeros_cnt = cnt
		end
	end

	-- format ipv6 address
	local out = ''
	local i = 1
	while i <= ipv6pieces do
		if i == zeros_begin then
			if i > 1 then
				out = out .. ':'
			else
				out = out .. '::'
			end
			i = i + zeros_cnt
		else
			local p = pcs[i]
			local hexdigits = tohex(p)
			out = out .. hexdigits
			if i ~= 8 then
				out = out .. ':'
			end
			i = i + 1
		end
	end

	if embeddedipv4 then
		out = out .. new_inet4(lshift(pcs[7], 16) + pcs[8]):ipstring()
	end

	local mask = self.mask
	if (mask == nil or mask == 128 or withmask == false) and withmask ~= true then
		return out
	else
		return string.format('%s/%d', out, mask)
	end
end

function inet6:__tostring()
	return tostr6(self)
end

function inet6:ipstring()
	return tostr6(self, false)
end

function inet6:ipstring4()
	return tostr6(self, false, true)
end

function inet6:ipstring6()
	return tostr6(self, false, false)
end

function inet6:cidrstring()
	return tostr6(self, true)
end

function inet6:clone()
	return new_inet6(self.pcs, self.mask)
end

function inet6:contains(other)
	-- self contains other
	local mask = self.mask

	if mask > other.mask then
		return false
	end

	local snet = self:network()
	local onet = (other / mask):network()

	return snet == onet
end

function inet6:__lt(other)
	-- self < other
	local spcs = self.pcs
	local opcs = other.pcs

	for i=1,8 do
		if spcs[i] < opcs[i] then
			return true
		end
		if spcs[i] > opcs[i] then
			return false
		end
	end

	return self.mask < other.mask
end

function inet6:__le(other)
	-- self <= other
	local spcs = self.pcs
	local opcs = other.pcs
	for i=1,8 do
		if spcs[i] < opcs[i] then
			return true
		end
		if spcs[i] > opcs[i] then
			return false
		end
	end

	return self.mask <= other.mask
end

function inet6:__eq(other)
	if self.mask ~= other.mask then
		return false
	end
	local spcs = self.pcs
	local opcs = other.pcs
	for i=1,8 do
		if spcs[i] ~= opcs[i] then
			return false
		end
	end
	return true
end

function inet6:__div(n)
	return new_inet6(self.pcs, n)
end

function inet6:__pow(n)
	return new_inet6(self.pcs, self.mask + n)
end

function inet6:__add(n)
	local new = self:clone()
	local pcs = new.pcs
	pcs[8] = pcs[8] + n
	new:balance(true)
	return new
end

function inet6:__sub(n)
	return self + (n*-1)
end

function inet6:network()
	local netbits = self.mask
	local pcs = self.pcs
	local newpcs = { 0, 0, 0, 0, 0, 0, 0, 0 }
	for i=1,8 do
		if netbits >= i*16 then
			newpcs[i] = pcs[i]
		elseif netbits <= (i-1)*16 then
			break -- the rest is already zero
		else
			local netbitsleft = 16-(netbits-((i-1)*16))
			newpcs[i] = lshift(rshift(pcs[i], netbitsleft), netbitsleft)
		end
	end
	return new_inet6(newpcs, netbits)
end

function inet6:flip()
	-- find twin by flipping the last network bit
	local mask = self.mask
	if mask == 0 then return nil end
	local block = rshift(mask, 4)+1
	local maskbits = band(mask, 0xf)
	local bitno = 16 - maskbits
	if bitno == 16 then
		block = block - 1
		bitno = 0
	end
	local flipbit = lshift(1, bitno)
	local r = self:clone()
	local val = r.pcs[block]
	r.pcs[block] = bxor(val, flipbit)
	--print(mask, block, maskbits, bitno, flipbit, self, r:balance())
	return r
end


function inet6:__mul(n)
	local new = self:clone()
	local mask = new.mask
	local pcs = new.pcs
	local netbitoverflow = mask % 16
	local netbitremainder = (128-mask) % 16
	local p = (mask - netbitoverflow) / 16
	if netbitremainder ~= 0 then
		p = p + 1
	end
	local was_negative = false
	if n < 0 then
		n = n * -1
		was_negative = true
	end
	local shiftet = lshift(n, netbitremainder)
	local high_shift = rshift(shiftet, 16)
	local low_shift = band(shiftet, 0xffff)
	--print(p, netbitoverflow, hex(shiftet), hex(high_shift), hex(low_shift))
	if was_negative then
		high_shift = -high_shift
		low_shift = -low_shift
	end
	if p > 2 then
		pcs[p-1] = pcs[p-1] + high_shift
	end
	pcs[p] = pcs[p] + low_shift
	new:balance()
	return new
end

local M = {}
local mt = {}

function mt.__call(_, ...)
	return new_inet(...)
end

M.is4 = is_inet4
M.is6 = is_inet6
M.is  = is_inet

return setmetatable(M, mt)