initial commit

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>

1 files changed, 490 insertions, 0 deletions

diff --git a/lua/inet/init.lua b/lua/inet/init.lua
new file mode 100644
index 0000000..62fa4d7
--- /dev/null
+++ b/lua/inet/init.lua
@@ -0,0 +1,490 @@
+-- ipv4 / 24 = network
+-- ipv6/56 * 5 = 5 /56 further down
+
+local bit32 = require 'bit32'
+
+local inet, inet4, inet6
+
+inet = {}
+inet.__index = inet
+
+function inet.new(ip, mask)
+	local ipv6 = string.find(ip, ':', 1, true)
+	if ipv6 then
+		return inet6.new(ip, mask)
+	else
+		return inet4.new(ip, mask)
+	end
+end
+
+function inet:__len()
+	return self.mask
+end
+
+local lshift = bit32.lshift
+local rshift = bit32.rshift
+local band = bit32.band
+local replace = bit32.replace
+local bxor = bit32.bxor
+
+inet4 = {}
+inet4.__index = inet4
+inet4.__len = inet.__len
+
+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')
+
+	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)
+		local ipv4 = 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 = ipv4 * (netmask + C('')) * -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 full = picol * picol * picol * picol * picol * picol * picol * piece
+		local partial = (piece * (colpi^-6))^-1 * colcol * ((picol^-6)*piece)^-1
+		local netmask = S('/') * C((digit^-3)) / tonumber
+		ipv6_parser = Ct(full + partial) * ((netmask + C(''))^-1) * -1
+	end
+end
+
+local function parse4(ipstr)
+	local o1, o2, o3, o4, mask = ipv4_parser:match(ipstr)
+	if o1 == nil then return nil end
+
+	local bip = lshift(o1, 24) + lshift(o2, 16) + lshift(o3, 8) + o4
+	return bip, tonumber(mask)
+end
+
+function inet4.new(ip, mask)
+	local bip, ourmask
+	if type(ip) == 'string' then
+		bip, ourmask = parse4(ip)
+		if bip == nil then
+			return nil
+		end
+	elseif type(ip) == 'number' then
+		bip = ip
+	end
+	if mask then
+		if type(mask) == 'number' and mask >= 0 and mask <= 32 then
+			ourmask = mask
+		else
+			error('invalid mask')
+		end
+	else
+		if not ourmask then
+			ourmask = 32
+		end
+	end
+	return setmetatable({
+		bip = bip,
+		mask = ourmask,
+	}, inet4)
+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 inet4.new(self.bip + n, self.mask)
+end
+
+function inet4:__sub(n)
+	return inet4.new(self.bip - n, self.mask)
+end
+
+function inet4:__mul(n)
+	local new = self.bip + (n * math.pow(2, 32 - self.mask))
+	return inet4.new(new, self.mask)
+end
+
+function inet4:__div(n)
+	return inet4.new(self.bip, n)
+end
+
+function inet4:__pow(n)
+	return inet4.new(self.bip, self.mask + n)
+end
+
+function inet4:__lt(other)
+	if self.mask <= other.mask then
+		return false
+	end
+	local mask = other.mask
+	local selfnet = replace(self.bip, 0, 0, 32-mask)
+	local othernet = replace(other.bip, 0, 0, 32-mask)
+	return selfnet == othernet
+end
+
+function inet4:__le(other)
+	if self.mask < other.mask then
+		return false
+	end
+	local mask = other.mask
+	local selfnet = replace(self.bip, 0, 0, 32-mask)
+	local othernet = replace(other.bip, 0, 0, 32-mask)
+	return selfnet == othernet
+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 inet4.new(lshift(rshift(self.bip, hostbits), hostbits), self.mask)
+end
+
+function inet4:netmask()
+	local hostbits = 32 - self.mask
+	return inet4.new(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 = 1 << hostbits
+	return inet4.new(self.bip ~ flipbit, mask)
+end
+
+local function parse6(ipstr)
+	local pcs, netmask = ipv6_parser:match(ipstr)
+	if not pcs then return nil 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=1,#pcs-i do
+				pcs[i+j+zero_pieces] = pcs[i+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 == '' then
+		netmask = 128
+	elseif netmask > 128 then
+		return nil, 'invalid netmask'
+	end
+	return pcs, netmask
+end
+
+inet6 = setmetatable({}, inet)
+inet6.__index = inet6
+inet6.__len = inet.__len
+
+function inet6.new(ip, netmask)
+	local pcs, err
+	if type(ip) == 'string' then
+		pcs, err = parse6(ip)
+		if pcs == nil then
+			return nil, err
+		end
+		if not netmask then
+			netmask = err
+		end
+	elseif type(ip) == 'table' then
+		pcs = { ip[1], ip[2], ip[3], ip[4],
+		        ip[5], ip[6], ip[7], ip[8] }
+		if not netmask then
+			netmask = 128
+		end
+	else
+		return nil
+	end
+
+	local r = setmetatable({
+		pcs = pcs,
+		mask = netmask,
+	}, inet6)
+
+	-- ensure that the result is balanced
+	if not r:is_balanced() then
+		r:balance()
+		return nil, tostring(r)..' unbalanced'
+	end
+
+	return r
+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
+	local i = 8
+	for i=i,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 tostr6(self, withmask)
+	-- return human readable
+	local pcs = self.pcs
+	local zeros = {}
+
+	-- count zero clusters
+	local first_zero = 0
+	local prev_was_zero = false
+	for i=1,#pcs 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 largest zero cluster
+	local zeros_begin = nil
+	local zeros_cnt = 0
+	for begin,cnt in pairs(zeros) do
+		if cnt > zeros_cnt then
+			zeros_begin = begin
+			zeros_cnt = cnt
+		end
+	end
+
+	-- format ipv6 address
+	local out = ''
+	local i = 1
+	while i <= 8 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 = string.format('%x', p)
+			out = out .. hexdigits
+			if i ~= 8 then
+				out = out .. ':'
+			end
+			i = i + 1
+		end
+	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:cidrstring()
+	return tostr6(self, true)
+end
+
+function inet6:clone()
+	return inet6.new(self.pcs, self.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 inet6.new(self.pcs, n)
+end
+
+function inet6:__pow(n)
+	return inet6.new(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] = pcs[i] >> netbitsleft << netbitsleft
+		end
+	end
+	return inet6.new(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 = (mask >> 4)+1
+	local maskbits = mask & 0xf
+	local bitno = 16 - maskbits
+	if bitno == 16 then
+		block = block - 1
+		bitno = 0
+	end
+	local flipbit = 1 << bitno
+	local r = self:clone()
+	local val = r.pcs[block]
+	r.pcs[block] = r.pcs[block] ~ 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()
+	-- print(mask % 8)
+	return new
+end
+
+return inet.new