local bit = require "bit"
local datafiles = require "datafiles"
local nmap = require "nmap"
local stdnse = require "stdnse"
local string = require "string"

description = [[
Shows extra information about IPv6 addresses, such as embedded MAC or IPv4 addresses when available.

Some IP address formats encode extra information; for example some IPv6
addresses encode an IPv4 address or MAC address. This script can decode
these address formats:
* IPv4-compatible IPv6 addresses,
* IPv4-mapped IPv6 addresses,
* Teredo IPv6 addresses,
* 6to4 IPv6 addresses,
* IPv6 addresses using an EUI-64 interface ID,
* IPv4-embedded IPv6 addresses,
* IPv4-translated IPv6 addresses and
* ISATAP Modified EUI-64 IPv6 addresses.

See RFC 4291 for general IPv6 addressing architecture and the
definitions of some terms.
]]

---
-- @output
-- Nmap scan report for ::1.2.3.4
-- Host script results:
-- |_address-info: IPv4-compatible; IPv4 address: 1.2.3.4
--
-- Nmap scan report for ::ffff:1.2.3.4
-- Host script results:
-- |_address-info: IPv4-mapped; IPv4 address: 1.2.3.4
--
-- Nmap scan report for 2001:0:506:708:282a:3d75:fefd:fcfb
-- Host script results:
-- | address-info: Teredo;
-- |   Server IPv4 address: 5.6.7.8
-- |   Client IPv4 address: 1.2.3.4
-- |_  UDP port: 49802
--
-- Nmap scan report for 2002:102:304::1
-- Host script results:
-- |_address-info: 6to4; IPv4 address: 1.2.3.4
--
-- Nmap scan report for fe80::a8bb:ccff:fedd:eeff
-- Host script results:
-- |_address-info: IPv6 EUI-64; MAC address: aa:bb:cc:dd:ee:ff (Unknown)
--
-- Nmap scan report for 64:ff9b::c000:221
-- Host script results:
-- |_address-info: IPv4-embedded IPv6 address; IPv4 address: 192.0.2.33
--
-- Nmap scan report for ::ffff:0:c0a8:101
-- Host script results:
-- |_address-info: IPv4-translated IPv6 address; IPv4 address: 192.168.1.1
--

-- * ISATAP. RFC 5214.
--   XXXX:XXXX:XXXX:XX00:0000:5EFE:a.b.c.d

author = "David Fifield"

license = "Same as Nmap--See http://nmap.org/book/man-legal.html"

categories = {"default", "safe"}


hostrule = function(host)
	return true
end

-- Match an address (array of bytes) against a hex-encoded pattern. "XX" in the
-- pattern is a wildcard.
local function matches(addr, pattern)
	local octet_patterns

	octet_patterns = {}
	for op in pattern:gmatch("([%xX][%xX])") do
		octet_patterns[#octet_patterns + 1] = op
	end

	if #addr ~= #octet_patterns then
		return false
	end

	for i = 1, #addr do
		local a, op

		a = addr[i]
		op = octet_patterns[i]
		if not (op == "XX" or a == tonumber(op, 16)) then
			return false
		end
	end

	return true
end

local function get_manuf(mac)
	if not nmap.registry.mac then
		local catch = function() return end
		local try = nmap.new_try(catch)
		-- Create the table in the registry so we can share between scripts
		nmap.registry.mac = {}
		nmap.registry.mac.prefixes = try(datafiles.parse_mac_prefixes())
	end
	local prefix = string.upper(string.format("%02x%02x%02x", mac[1], mac[2], mac[3]))
	local manuf = nmap.registry.mac.prefixes[prefix] or "Unknown"
	return manuf
end

local function format_mac(mac)
	local octets

	octets = {}
	for _, v in ipairs(mac) do
		octets[#octets + 1] = string.format("%02x", v)
	end

	return stdnse.strjoin(":", octets) .. " (" .. get_manuf(mac) .. ")"
end

local function format_ipv4(ipv4)
	local octets

	octets = {}
	for _, v in ipairs(ipv4) do
		octets[#octets + 1] = string.format("%d", v)
	end

	return stdnse.strjoin(".", octets)
end

local function do_ipv4(addr)
end

-- EUI-64 from MAC, RFC 4291.
local function decode_eui_64(eui_64)
	if eui_64[4] == 0xff and eui_64[5] == 0xfe then
		return { bit.bxor(eui_64[1], 0x02),
			eui_64[2], eui_64[3], eui_64[6], eui_64[7], eui_64[8] }
	end
end

local function format_output(label, lines)
	local output

	output = ""
	if #lines == 0 then
		return label
	elseif #lines == 1 then
		if label then
			output = output .. label .. "; "
		end
		return output .. lines[1]
	else
		if label then
			output = output .. label .. ";"
		end
		return output .. "\n  " .. stdnse.strjoin("\n  ", lines)
	end
end

local function do_ipv6(addr)
	local label
	local output

	output = {}

	if matches(addr, "0000:0000:0000:0000:0000:0000:XXXX:XXXX")
		and not matches(addr, "0000:0000:0000:0000:0000:0000:0000:0001") then
		-- RFC 4291 2.5.5.1. Specifically exclude ::1 for localhost.
		local ipv4 = { addr[13], addr[14], addr[15], addr[16] }
		return format_output("IPv4-compatible",
			{ "IPv4 address: " .. format_ipv4(ipv4) })
	elseif matches(addr, "0000:0000:0000:0000:0000:ffff:XXXX:XXXX") then
		-- RFC 4291 2.5.5.2.
		local ipv4 = { addr[13], addr[14], addr[15], addr[16] }
		return format_output("IPv4-mapped",
			{ "IPv4 address: " .. format_ipv4(ipv4) })
	elseif matches(addr, "2001:0000:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX") then
		-- Teredo, RFC 4380.
		local server_ipv4 = { addr[5], addr[6], addr[7], addr[8] }
		-- RFC 5991 makes the flags mostly meaningless.
		local flags = addr[9] * 256 + addr[10]
		local obs_port = addr[11] * 256 + addr[12]
		local obs_client_ipv4 = { addr[13], addr[14], addr[15], addr[16] }
		local port, client_ipv4

		-- Invert obs_port.
		port = bit.bxor(obs_port, 0xffff)

		-- Invert obs_client_ipv4.
		client_ipv4 = {}
		for _, octet in ipairs(obs_client_ipv4) do
			client_ipv4[#client_ipv4 + 1] = bit.bxor(octet, 0xff)
		end

		output[#output + 1] = "Server IPv4 address: " .. format_ipv4(server_ipv4)
		output[#output + 1] = "Client IPv4 address: " .. format_ipv4(client_ipv4)
		output[#output + 1] = "UDP port: " .. tostring(port)

		return format_output("Teredo", output)
	elseif matches(addr, "0064:ff9b:XXXX:XXXX:00XX:XXXX:XXXX:XXXX") then
		--IPv4-embedded IPv6 addresses. RFC 6052, Section 2

		--skip addr[9]
		if matches(addr,"0064:ff9b:0000:0000:0000:0000:XXXX:XXXX") then
			local ipv4 = {addr[13], addr[14], addr[15], addr[16]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		elseif addr[5] ~= 0x01 then
			local ipv4 = {addr[5], addr[6], addr[7], addr[8]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		elseif addr[6] ~= 0x22 then
			local ipv4 = {addr[6], addr[7], addr[8], addr[10]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		elseif addr[7] ~= 0x03 then
			local ipv4 = {addr[7], addr[8], addr[10], addr[11]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		elseif addr[8] ~= 0x44 then
			local ipv4 = {addr[8], addr[10], addr[11], addr[12]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		elseif addr[10] == 0x00 and addr[11] == 0x00 and addr[12] == 0x00 then
			local ipv4 = {addr[13], addr[14], addr[15], addr[16]}
			return format_output("IPv4-embedded IPv6 address",{"IPv4 address: "..format_ipv4(ipv4)})
		end
	elseif matches(addr, "0000:0000:0000:0000:ffff:0000:XXXX:XXXX") then
		-- IPv4-translated IPv6 addresses. RFC 2765, Section 2.1 
		return format_output("IPv4-translated IPv6 address", 
			{"IPv4 address: "..format_ipv4( {addr[13], addr[14], addr[15], addr[16]})})
	elseif matches(addr, "XXXX:XXXX:XXXX:XX00:0000:5efe:XXXX:XXXX") then
		-- ISATAP. RFC 5214, Appendix A
		-- XXXX:XXXX:XXXX:XX00:0000:5EFE:a.b.c.d
		return format_output("ISATAP Modified EUI-64 IPv6 Address", 
			{"IPv4 address: "..format_ipv4( {addr[13], addr[14], addr[15], addr[16]})})
	end

	-- These following use common handling for the Interface ID part
	-- (last 64 bits).

	if matches(addr, "2002:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX") then
		-- 6to4, RFC 3056.
		local ipv4 = { addr[3], addr[4], addr[5], addr[6] }
		local mac = decode_eui_64({ addr[9], addr[10], addr[11], addr[12],
			addr[13], addr[14], addr[15], addr[16] })

		label = "6to4"
		output[#output + 1] = "IPv4 address: " .. format_ipv4(ipv4)
	end

	local mac = decode_eui_64({ addr[9], addr[10], addr[11], addr[12],
		addr[13], addr[14], addr[15], addr[16] })
	if mac then
		output[#output + 1] = "MAC address: " .. format_mac(mac)
		if not label then
			label = "IPv6 EUI-64"
		end
	end

	return format_output(label, output)
end

action = function(host)
	local addr_s, addr_t

	addr_s = host.bin_ip
	addr_t = { string.byte(addr_s, 1, #addr_s) }

	if #addr_t == 4 then
		return do_ipv4(addr_t)
	elseif #addr_t == 16 then
		return do_ipv6(addr_t)
	end
end