Move the format_difftime function out of http-date.nse and into

stdnse.lua. It can be useful in other scripts.

scripts/http-date.nse

@@ -19,12 +19,11 @@ categories = {"discovery", "safe"}
 
 require("http")
 require("shortport")
+require("stdnse")
 
 portrule = shortport.port_or_service({80, 443, 631, 8080},
 	{"http", "https", "ipp", "http-alt"})
 
-local format_difftime
-
 action = function(host, port)
 	-- Get the local date in UTC.
 	local request_date = os.date("!*t")
@@ -39,85 +38,8 @@ action = function(host, port)
 	end
 
 	-- Should account for estimated RTT too.
-	local diff = format_difftime(response_date, request_date)
+	local diff = stdnse.format_difftime(response_date, request_date)
 
 	return string.format("%s; %s from local time.",
 		response.header["date"], diff)
 end
-
--- Turn a positive or negative number of seconds into a string in one of the
--- forms. Signs can of course vary.
--- 0s
--- -4s
--- +2m38s
--- -9h12m34s
--- +5d17h05m06s
--- -2y177d10h13m20s
-format_difftime = function(t2, t1)
-	local d, s, sign, yeardiff
-
-	d = os.difftime(os.time(t2), os.time(t1))
-	if d > 0 then
-		sign = "+"
-	elseif d < 0 then
-		sign = "-"
-		t2, t1 = t1, t2
-		d = -d
-	else
-		sign = ""
-	end
-	-- t2 is always later than or equal to t1 here.
-
-	-- The year is a tricky case because it's not a fixed number of days
-	-- the way a day is a fixed number of hours or an hour is a fixed
-	-- number of minutes. For example, the difference between 2008-02-10
-	-- and 2009-02-10 is 366 days because 2008 was a leap year, but it
-	-- should be printed as 1y0d0h0m0s, not 1y1d0h0m0s. We advance t1 to be
-	-- the latest year such that it is still before t2, which means that its
-	-- year will be equal to or one less than t2's. The number of years
-	-- skipped is stored in yeardiff.
-	if t2.year > t1.year then
-		local tmpyear = t1.year
-		-- Put t1 in the same year as t2.
-		t1.year = t2.year
-		d = os.difftime(os.time(t2), os.time(t1))
-		if d < 0 then
-			-- Too far. Back off one year.
-			t1.year = t2.year - 1
-			d = os.difftime(os.time(t2), os.time(t1))
-		end
-		yeardiff = t1.year - tmpyear
-		t1.year = tmpyear
-	else
-		yeardiff = 0
-	end
-
-	local s, sec, min
-	s = ""
-	-- Seconds (pad to two digits).
-	sec = d % 60
-	d = math.floor(d / 60)
-	if d == 0 and yeardiff == 0 then
-		return sign .. string.format("%gs", sec) .. s
-	end
-	s = string.format("%02gs", sec) .. s
-	-- Minutes (pad to two digits).
-	min = d % 60
-	d = math.floor(d / 60)
-	if d == 0 and yeardiff == 0 then
-		return sign .. string.format("%dm", min) .. s
-	end
-	s = string.format("%02dm", min) .. s
-	-- Hours.
-	s = string.format("%dh", d % 24) .. s
-	d = math.floor(d / 24)
-	if d == 0 and yeardiff == 0 then
-		return sign .. s
-	end
-	-- Days.
-	s = string.format("%dd", d) .. s
-	if yeardiff == 0 then return sign .. s end
-	-- Years.
-	s = string.format("%dy", yeardiff) .. s
-	return sign .. s
-end