description = [[
Multicast echo ping.
Do a very fast host discovery on link-local IPv6 network.
]]

---
-- @usage
-- ./nmap -6 --script=targets-ipv6-multicast-echo.nse --script-args 'newtargets,interface=eth0,ipv6.src=2001:da8:215:3320:223:aeff:fe5d:3b10' -sL
-- @args newtargets  If true, add discovered targets to the scan queue.
-- @args interface  The interface to use for host discovery.
-- @args ipv6.src  The source IPv6 address in the probe packets.

author = "David and Weilin"

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

categories = {"discovery"}

require 'nmap'
require 'target'
require 'packet'
local bit = require 'bit'

prerule = function()
  return nmap.is_privileged() and
	(stdnse.get_script_args("interface") or nmap.get_interface())
end

catch = function()
	dnet:ethernet_close()
	pcap:pcap_close()
end
try = nmap.new_try(catch)

local function get_ipv6_interface_info_by_name(if_name)
	local ifaces = nmap.list_interfaces()
	local iface
	local if_nfo
	for _,iface in pairs(ifaces) do
		if if_name == iface.device and (#iface.address>15 or string.find(iface.address, "::")) then
			if_nfo = iface
			return if_nfo
		end
	end
	return nil
end

local function get_identifier(ip6_addr)
	return string.sub(ip6_addr, 9, 16)
end

action = function()
	local if_name = stdnse.get_script_args("targets-ipv6-multicast.interface") or nmap.get_interface()
	local if_nfo = get_ipv6_interface_info_by_name(if_name)	
	if not if_nfo then
		stdnse.print_debug("Invalid interface: " .. if_name)
		return false
	end
	local src_mac = if_nfo.mac
	local src_ip6 = packet.ip6tobin(stdnse.get_script_args("ipv6.src")) or packet.ip6tobin(if_nfo.address)
	local dst_mac = packet.mactobin("33:33:00:00:00:01")
	local dst_ip6 = packet.ip6tobin("ff02::1")
	local id_set = {}
	
----------------------------------------------------------------------------
--Multicast echo ping probe
	
	local dnet = nmap.new_dnet()
	local pcap = nmap.new_socket()
	
	try(dnet:ethernet_open(if_name))
	pcap:pcap_open(if_name, 128, false, "icmp6 and ip6[6:1] = 58 and ip6[40:1] = 129")
	
	local probe = packet.Frame:new()
	probe.mac_src = src_mac
	probe.mac_dst = dst_mac
	probe.ip6_src = src_ip6
	probe.ip6_dst = dst_ip6
	probe.echo_id = 5
	probe.echo_seq = 6
	probe.echo_data = "Nmap host discovery."
	probe:build_icmpv6_echo_request()
	probe:build_icmpv6_header()
	probe:build_ipv6_packet()	
	probe:build_ether_frame()
	
	try(dnet:ethernet_send(probe.frame_buf))
	
	pcap:set_timeout(1000)	
	local pcap_timeout_count = 0
	local nse_timeout = 5
	local start_time = nmap:clock()
	local cur_time = nmap:clock()
	
	local found_targets = 0
				
	repeat		
		local status, length, layer2, layer3 = pcap:pcap_receive()
		cur_time = nmap:clock()
		if not status then
			pcap_timeout_count = pcap_timeout_count + 1
		else
			local reply = packet.Frame:new(layer2..layer3)			
			if reply.mac_dst == src_mac then
				local identifier = get_identifier(reply.ip6_src)				
				if not id_set[identifier] then
					id_set[identifier] = true
					local target_str = packet.toipv6(reply.ip6_src)
					target.add(target_str)
					found_targets = found_targets + 1
				end			
			end			
		end
	until pcap_timeout_count >= 2 or cur_time - start_time >= nse_timeout
	
	stdnse.print_debug(0, "[Echo ping] Found %d targets.", found_targets)
		
	dnet:ethernet_close()
	pcap:pcap_close()
	
	return true
end