o [NSE] Added gps library and the gpsd-info script that collects GPS data

from the gpsd daemon. [Patrik Karlsson]

CHANGELOG

@@ -1,5 +1,8 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE] Added gps library and the gpsd-info script that collects GPS data
+  from the gpsd daemon. [Patrik Karlsson]
+
 o [NSE] Ported the pop3-brute script to use the brute library.
   [Piotr Olma]
 

nselib/gps.lua

@@ -0,0 +1,116 @@
+---
+-- A smallish gps parsing module.
+-- Currently does GPRMC NMEA decoding
+--
+-- @author "Patrik Karlsson <patrik@cqure.net>"
+--
+--
+
+module(... or "gps", package.seeall)
+
+local bit = require('bit')
+
+NMEA = { 
+
+	-- Parser for the RMC sentence
+	RMC = {
+	
+		parse = function(str)
+		
+			local time, status, latitude, ns_indicator, longitude,
+			  	ew_indicator, speed, course, date, variation,
+				ew_variation, checksum = str:match("^%$GPRMC,([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^,]*),([^%*]*)(.*)$")
+			
+			if ( not(latitude) or not(longitude) ) then
+				return
+			end
+			
+			local deg, min = latitude:match("^(..)(.*)$")
+			if ( not(deg) or not(min) ) then
+				return
+			end
+			latitude = tonumber(deg) + (tonumber(min)/60)
+			
+			deg, min = longitude:match("^(..)(.*)$")
+			if ( not(deg) or not(min) ) then
+				return
+			end
+			longitude = tonumber(deg) + (tonumber(min)/60)
+			if ( ew_indicator == 'W' ) then
+				longitude = -longitude
+			end
+
+			if ( ns_indicator == 'S' ) then
+				latitude = -latitude
+			end
+			
+			return { time = time, status = status, latitude = latitude,
+					longitude = longitude, speed = speed, course = course,
+					date = date, variation = variation, 
+					ew_variation = ew_variation }
+		end,
+		
+	},
+	
+	-- Calculates an verifies the message checksum
+	--
+	-- @param str containing the GPS sentence
+	-- @return status true on success, false if the checksum does not match
+	-- @return err string if status is false
+	checksum = function(str)
+		local val = 0
+		for c in str:sub(2,-4):gmatch(".") do
+			val = bit.bxor(val, string.byte(c))
+		end
+				
+		if ( str:sub(-2):upper() ~= stdnse.tohex(string.char(val)):upper() ) then
+			return false, ("Failed to verify checksum (got: %s; expected: %s)"):format(stdnse.tohex(string.char(val)), str:sub(-2))
+		end
+		return true
+	end,
+
+	-- Parses a GPS sentence using the apropriate parser
+	--
+	-- @param str containing the GPS sentence
+	-- @return entry table containing the parsed response or 
+	--         err string if status is false
+	-- @return status true on success, false on failure
+	parse = function(str)
+	
+		local status, err = NMEA.checksum(str)
+		if ( not(status) ) then
+			return false, err
+		end
+	
+		local prefix = str:match("^%$GP([^,]*)")
+		if ( not(prefix) ) then
+			return false, "Not a NMEA sentence"
+		end
+
+		if ( NMEA[prefix] and NMEA[prefix].parse ) then
+			local e = NMEA[prefix].parse(str)
+			if (not(e)) then
+				return false, ("Failed to parse entry: %s"):format(str)
+			end
+			return true, e
+		else
+			local err = ("No parser for prefix: %s"):format(prefix)
+			stdnse.print_debug(2, err)
+			return false, err
+		end
+	
+	end
+	
+}
+
+Util = {
+
+	convertTime = function(date, time)
+		local d = {}
+		d.hour, d.min, d.sec = time:match("(..)(..)(..)")
+		d.day, d.month, d.year = date:match("(..)(..)(..)")		
+		d.year = d.year + 2000
+		return os.time(d)
+	end
+}
+

scripts/gpsd-info.nse

@@ -0,0 +1,99 @@
+description = [[
+Retrieves GPS time, coordinates and speed from the GPSD network daemon.
+]]
+
+---
+-- @usage
+-- nmap -p 2947 <ip> --script gpsd-info
+--
+-- @output
+-- PORT     STATE SERVICE REASON
+-- 2947/tcp open  gpsd-ng syn-ack
+-- | gpsd-info: 
+-- |   Time of fix: Sat Apr 14 15:54:23 2012
+-- |   Coordinates: 59.321685,17.886493
+-- |_  Speed: - knots
+--
+
+
+author = "Patrik Karlsson"
+license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
+categories = {"discovery", "safe"}
+
+local shortport = require 'shortport'
+local gps       = require 'gps'
+local json      = require 'json'
+local match     = require 'match'
+
+portrule = shortport.port_or_service(2947, "gpsd-ng", "tcp")
+
+local arg_timeout = tonumber(stdnse.get_script_args(SCRIPT_NAME .. ".timeout")) or 10
+
+local function updateData(gpsinfo, entry)
+	for k, v in pairs(gpsinfo) do
+		if ( entry[k] and 0 < #tostring(entry[k]) ) then
+			gpsinfo[k] = entry[k]
+		end
+	end
+end
+
+local function hasAllData(gpsinfo)
+	for k, v in pairs(gpsinfo) do
+		if ( k ~= "speed" and v == '-' ) then
+			return false
+		end
+	end
+	return true
+end
+
+local function fail(err) return ("\n  ERROR: %s"):format(err or "") end
+
+action = function(host, port)
+	
+	local gpsinfo = {
+		longitude = "-",
+		latitude = "-",
+		speed = "-",
+		time  = "-",
+		date  = "-",
+	}
+
+	local socket = nmap.new_socket()
+	socket:set_timeout(1000)
+	
+	local status = socket:connect(host, port)
+	
+	if ( not(status) ) then
+		return fail("Failed to connect to server")
+	end
+
+	-- get the banner
+	local status, line = socket:receive_lines(1)
+	socket:send('?WATCH={"enable":true,"nmea":true}\r\n')
+	
+	local start_time = os.time()
+	
+	repeat
+		local entry
+		status, line = socket:receive_buf("\r\n")
+		if ( status ) then
+			status, entry = gps.NMEA.parse(line)
+			if ( status ) then
+				updateData(gpsinfo, entry)
+			end
+		end
+	until( os.time() - start_time > arg_timeout or hasAllData(gpsinfo) )
+
+	socket:send('?WATCH={"enable":false}\r\n')
+
+	if ( not(hasAllData(gpsinfo)) ) then
+		return
+	end
+
+	local output = {
+		("Time of fix: %s UTC"):format(os.date("%c", gps.Util.convertTime(gpsinfo.date, gpsinfo.time))),
+		("Coordinates: %.4f,%.4f"):format(tonumber(gpsinfo.latitude), tonumber(gpsinfo.longitude)),
+		("Speed: %s knots"):format(gpsinfo.speed)
+	}	
+	return stdnse.format_output(true, output)
+end

scripts/script.db

@@ -94,6 +94,7 @@ Entry { filename = "ftp-vuln-cve2010-4221.nse", categories = { "intrusive", "vul
 Entry { filename = "ganglia-info.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "giop-info.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "gopher-ls.nse", categories = { "default", "discovery", "safe", } }
+Entry { filename = "gpsd-info.nse", categories = { "discovery", "safe", } }
 Entry { filename = "hadoop-datanode-info.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "hadoop-jobtracker-info.nse", categories = { "default", "discovery", "safe", } }
 Entry { filename = "hadoop-namenode-info.nse", categories = { "default", "discovery", "safe", } }