-- Prosody IM

-- Copyright (C) 2008-2011 Florian Zeitz

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local net = require "util.net";

local hex = require "util.hex";

local ip_methods = {};

local ip_mt = {

	__index = function (ip, key)

		return ip_methods[key](ip);

	end,

	__tostring = function (ip) return ip.addr; end,

	__eq = function (ipA, ipB) return ipA.addr == ipB.addr; end

};

local hex2bits = {

	["0"] = "0000", ["1"] = "0001", ["2"] = "0010", ["3"] = "0011",

	["4"] = "0100", ["5"] = "0101", ["6"] = "0110", ["7"] = "0111",

	["8"] = "1000", ["9"] = "1001", ["A"] = "1010", ["B"] = "1011",

	["C"] = "1100", ["D"] = "1101", ["E"] = "1110", ["F"] = "1111",

};

local function new_ip(ipStr, proto)

	local zone;

	if (not proto or proto == "IPv6") and ipStr:find('%', 1, true) then

		ipStr, zone = ipStr:match("^(.-)%%(.*)");

	end

	local packed, err = net.pton(ipStr);

	if not packed then return packed, err end

	if proto == "IPv6" and #packed ~= 16 then

		return nil, "invalid-ipv6";

	elseif proto == "IPv4" and #packed ~= 4 then

		return nil, "invalid-ipv4";

	elseif not proto then

		if #packed == 16 then

			proto = "IPv6";

		elseif #packed == 4 then

			proto = "IPv4";

		else

			return nil, "unknown protocol";

		end

	elseif proto ~= "IPv6" and proto ~= "IPv4" then

		return nil, "invalid protocol";

	end

	return setmetatable({ addr = ipStr, packed = packed, proto = proto, zone = zone }, ip_mt);

end

function ip_methods.bits(ip)

	return hex.to(ip.packed):upper():gsub(".", hex2bits);

end

function ip_methods.bits_full(ip)

	if ip.proto == "IPv4" then

		ip = ip.toV4mapped;

	end

	return ip.bits;

end

local function commonPrefixLength(ipA, ipB)

	ipA, ipB = ipA.bits_full, ipB.bits_full;

	for i = 1, 128 do

		if ipA:sub(i,i) ~= ipB:sub(i,i) then

			return i-1;

		end

	end

	return 128;

end

local function v4scope(ip)

	local fields = {};

	ip:gsub("([^.]*).?", function (c) fields[#fields + 1] = tonumber(c) end);

	-- Loopback:

	if fields[1] == 127 then

		return 0x2;

	-- Link-local unicast:

	elseif fields[1] == 169 and fields[2] == 254 then

		return 0x2;

	-- Global unicast:

	else

		return 0xE;

	end

end

local function v6scope(ip)

	-- Loopback:

	if ip:match("^[0:]*1$") then

		return 0x2;

	-- Link-local unicast:

	elseif ip:match("^[Ff][Ee][89ABab]") then

		return 0x2;

	-- Site-local unicast:

	elseif ip:match("^[Ff][Ee][CcDdEeFf]") then

		return 0x5;

	-- Multicast:

	elseif ip:match("^[Ff][Ff]") then

		return tonumber("0x"..ip:sub(4,4));

	-- Global unicast:

	else

		return 0xE;

	end

end

local function label(ip)

	if commonPrefixLength(ip, new_ip("::1", "IPv6")) == 128 then

		return 0;

	elseif commonPrefixLength(ip, new_ip("2002::", "IPv6")) >= 16 then

		return 2;

	elseif commonPrefixLength(ip, new_ip("2001::", "IPv6")) >= 32 then

		return 5;

	elseif commonPrefixLength(ip, new_ip("fc00::", "IPv6")) >= 7 then

		return 13;

	elseif commonPrefixLength(ip, new_ip("fec0::", "IPv6")) >= 10 then

		return 11;

	elseif commonPrefixLength(ip, new_ip("3ffe::", "IPv6")) >= 16 then

		return 12;

	elseif commonPrefixLength(ip, new_ip("::", "IPv6")) >= 96 then

		return 3;

	elseif commonPrefixLength(ip, new_ip("::ffff:0:0", "IPv6")) >= 96 then

		return 4;

	else

		return 1;

	end

end

local function precedence(ip)

	if commonPrefixLength(ip, new_ip("::1", "IPv6")) == 128 then

		return 50;

	elseif commonPrefixLength(ip, new_ip("2002::", "IPv6")) >= 16 then

		return 30;

	elseif commonPrefixLength(ip, new_ip("2001::", "IPv6")) >= 32 then

		return 5;

	elseif commonPrefixLength(ip, new_ip("fc00::", "IPv6")) >= 7 then

		return 3;

	elseif commonPrefixLength(ip, new_ip("fec0::", "IPv6")) >= 10 then

		return 1;

	elseif commonPrefixLength(ip, new_ip("3ffe::", "IPv6")) >= 16 then

		return 1;

	elseif commonPrefixLength(ip, new_ip("::", "IPv6")) >= 96 then

		return 1;

	elseif commonPrefixLength(ip, new_ip("::ffff:0:0", "IPv6")) >= 96 then

		return 35;

	else

		return 40;

	end

end

local function toV4mapped(ip)

	local fields = {};

	local ret = "::ffff:";

	ip:gsub("([^.]*).?", function (c) fields[#fields + 1] = tonumber(c) end);

	ret = ret .. ("%02x"):format(fields[1]);

	ret = ret .. ("%02x"):format(fields[2]);

	ret = ret .. ":"

	ret = ret .. ("%02x"):format(fields[3]);

	ret = ret .. ("%02x"):format(fields[4]);

	return new_ip(ret, "IPv6");

end

function ip_methods:toV4mapped()

	if self.proto ~= "IPv4" then return nil, "No IPv4 address" end

	local value = toV4mapped(self.addr);

	self.toV4mapped = value;

	return value;

end

function ip_methods:label()

	local value;

	if self.proto == "IPv4" then

		value = label(self.toV4mapped);

	else

		value = label(self);

	end

	self.label = value;

	return value;

end

function ip_methods:precedence()

	local value;

	if self.proto == "IPv4" then

		value = precedence(self.toV4mapped);

	else

		value = precedence(self);

	end

	self.precedence = value;

	return value;

end

function ip_methods:scope()

	local value;

	if self.proto == "IPv4" then

		value = v4scope(self.addr);

	else

		value = v6scope(self.addr);

	end

	self.scope = value;

	return value;

end

function ip_methods:private()

	local private = self.scope ~= 0xE;

	if not private and self.proto == "IPv4" then

		local ip = self.addr;

		local fields = {};

		ip:gsub("([^.]*).?", function (c) fields[#fields + 1] = tonumber(c) end);

		if fields[1] == 127 or fields[1] == 10 or (fields[1] == 192 and fields[2] == 168)

		or (fields[1] == 172 and (fields[2] >= 16 or fields[2] <= 32)) then

			private = true;

		end

	end

	self.private = private;

	return private;

end

local function parse_cidr(cidr)

	local bits;

	local ip_len = cidr:find("/", 1, true);

	if ip_len then

		bits = tonumber(cidr:sub(ip_len+1, -1));

		cidr = cidr:sub(1, ip_len-1);

	end

	return new_ip(cidr), bits;

end

local function match(ipA, ipB, bits)

	local common_bits = commonPrefixLength(ipA, ipB);

	if bits and ipB.proto == "IPv4" then

		common_bits = common_bits - 96; -- v6 mapped addresses always share these bits

	end

	return common_bits >= (bits or 128);

end

return {

	new_ip = new_ip,

	commonPrefixLength = commonPrefixLength,

	parse_cidr = parse_cidr,

	match = match,

};